The Wellcome Trust Review 1999 A selection of research projects and major initiatives 1 f H !©
The Wellcome Trust Sir Henry Wellcome (1853-1936), the founder of the Wellcome Trust, stated in his will that his The Director charity should support "scientific research which may 3 Changing times Michael Dexter conduce to the improvement of" the physical conditions of mankind".Today, the Trust funds a great diversity of biomedical research in the UK and overseas, SCIENCE FUNDING and supports active programmes in science communication and research in the history of / Viral paralysis medicine.This year©s Wellcome Trust Review samples O Japanese paralytic syndrome just a few of the many excellent projects funded by A new clinical variant of a common viral infection the Trust, and examines how research discoveries Tom Solomon and insights in differing fields can broaden our understanding of the human body in health and disease, an understanding that will underpin the healthcare advances of the next century.
JT\ Cell traffic 10 Coats of many colours: Transporting proteins around the cell Margaret S Robinson
Thalassaemias 14 In the blood: Thalassaemias in South-East Asia David Weatherall ©A I*
40 ChiChild development I \J HapHappy families?: Non-traditional families and hildren©s well-being Susan Goiombok
A A Tuberculosis Bone adaptation II The persistent plague: New strategies for tackling 18 Taking the strain: Bones, exercise and oestrogen tuberculosis Douglas Young Lance Lanyon
©"J "*) Neurodevelopment Segments and eyes: Building the hindbrain and visual system Andrew Lumsden and William Hams
Upsetting the balance: Tuberculosis in 48 South Africa Albert Beyers, Paul van He/den ond Nulda Beyers
Wound healing r-MEDICINE, SOCIETY AND HISTORY Health scar story: Wound healing and ageing Malaria in East Africa Gillian Ashcmft 54 Roll back malaria: The history of malaria and its control in twentieth-century East Africa Blood pressure Mary \ Dobson, Robert A/I Snow and A pressure situation: The control of blood 32 Maureen J Malowany pressure John Mullins
Edinburgh "} / Campylobacter 58 The Trojan horse: The B.ochemical Laboratory The full Campy: The genome of the Royal Infirmary of Edinburgh 1921-1939 sequence of a food-borne Mike Bo/foot, pathogen Julian Forkful/, Chris Lowrence Ban Barrell, Julian Ketley ond Stew Sturdy and Brendan Wren
Theatre 62 Staging science: Theatre, debate and schools Peter F/nego/d ©"i v THE DIRECTOR Chan times
Medicine and biomedicalresearch are never static. Constant advances in technology and techniques ensure that researchers must adapt to ensure that they stay ahead of the field. That they do so successfully is apparent in the breakthroughs that come every year in our understanding of the human body and of the microorganisms that wage war against our immune systems. This issue of the Wellcome Trust Review covers only a fraction of the Trust-funded research in the UK and overseas, but highlights how modern genetics underpins and drives forward research across a broad span of fields.
The genome revolution Only a decade ago, sequencing DNA was a laborious, manual process, and discovering the code tor a single gene was a masterful piece of work. Today, automation and powerful computers have revolutionized the process, enabling the sequences of thousands of genes to be available to all, over the Internet. With the first drafr of the human genome to be completed by spring 2000, and the fine detail by 2003, the next challenge will be to make use of" this vast resource of information. Above: Dr Michael Dexter, Director of the Wellcome Trust. As has been the case in much of biomedicme, research on Left: Segmentation in the microbes is leading the way. The completed genome chick embryo hindbrain. sequence of the bacterium Camfiylobiicter jejtini has brought together six UK groups into a consortium using powerful new techniques to discover why it is a leading cause of food poisoning. In London, Professor Douglas Young is using THE DIRECTOR
products of these genes work together to influence the development of such complex systems.
Effecting change Despite the efforts of the research and medical communities, problems and pitfalls often arise. In the case of the worldwide eradication campaigns - so successful in removing the scourge of smallpox - little is straightforward. The mass vaccination of children against polio in South- East Asia has not reduced the incidence of paralysis to the extent expected, and Dr Tom Solomon©s work in Vietnam has uncovered a hidden role of Japanese encephalitis virus in such paralysis. In the case of the campaign against malaria. Dr Mary Dobson and colleagues in Oxford and Kenya look back over the last 50 years to ask why the promised eradication has yet to yield results in Africa. Some Above: Mycobocterium luberoilos/s, which causes TB. of the obstacles have been man-made, but most are due to the genome sequence of Mycvbacteriiini tiilwmilmi in the the changing characteristics of the malarial parasite and its search for new vaccines against the bacterium that is the vector, the mosquito. single largest killer in the world today. Such work is key in regions such as the Western Cape Province of South Africa, The structure of society is also undergoing change. With where tuberculosis is rife. Yet the fight against tuberculosis sophisticated technology helping couples with fertility must not focus on the bacterium alone - in the Cape, problems and single or lesbian women to have children, Professor Albert Beyers and colleagues have found that Professor Susan Colombok is investigating the development other factors, such as infection with intestinal parasites, also of children with non-traditional family backgrounds - with reduce the effectiveness of the hodys immune response to encouraging results. At the other end of the age spectrum, M. tuberculosis. diseases of the elderly are becoming more prevalent as the population itself ages. Professor Lance Lanyon and Genetics research is not only about sequence hunting. With colleagues at London LIniversity©s Royal Veterinary College genetic diseases likely to become an increasingly important are investigating how physical strain - such as exercise health burden in the developing world, Professor Sir David helps to strengthen the skeleton and protect against Wcatherall and colleagues at Oxford are investigating the osteoporosis and bone fracture. At Manchester, Dr Gillian frequency and effects on health of the thalassaemias in Ashcrort is looking at the decline in the rate of wound South-East Asia. In Edinburgh meanwhile. Professor lohn healing that comes with old age, often causing chronic Mullins and colleagues are using cutting-edge genetic wounds to develop but, paradoxically, reducing the amount manipulation techniques, allied to classic physiology, to of scarring that results. unravel how the body controls blood pressure. Now and then Cell biology and neuroscicnce have already gained much If the genome revolution is upon us now, an equally from the new technologies of the l l)9()s. The ubiquity of the significant revolution occurred 70 years ago and the face Internet, with its freely available online databases, enabled of medical education and research in the UK universities Dr Margaret Robinson and colleagues at Cambridge to might have looked very different had the events then forge important collaborations with researchers in the USA, transpired differently. Drs Mike Bartoot, Chris Lawrence pushing ahead her research on the transportation systems and Steve Sturdy discuss the role of the Rockefeller inside the cell. The research teams led by Professors Andrew Foundation in the Biochemical Laboratory at the Royal Lumsden and William Harris, examining the development Infirmary of Edinburgh, and the events that helped to of the chick hindbrain and frog eye, respectively, have found bring fully professional academic medicine to the UK. a. plethora or genes involved in each of these most delicate of processes - now the challenge is to determine how the Dr Michael Dexter, Director of the Wellcome Trust 93U
TOM SOLOMON
The WHO©s programme to eradicate polio by the year 2000 has had Japanese many successes, but there have been difficulties and controversy over the clinical diagnosis of polio. In Vietnam, Dr Tom Solomon and colleagues have paralytic found that many children who were thought to have polio were actually infected with a completely unrelated virus - Japanese encephalitis virus. syndrome A new clinical variant of a common viral infection
nthused by the successful eradication of smallpox in the 1970s, in 1988 the World Health Organization E (WHO) embarked upon a global programme to eradicate polio. Polio was considered a suitable target lor eradication because poliovirus is found only in humans, and a cheap and effective vaccine is readily available. Polio viruses infect and destroy nerve cells in the front of the spinal cord (anterior horn cells) that transmit impulses to muscles, making them contract. With the destruction < these anterior horn cells, the muscles are paralysed and become floppy (flaccid) and wasted. Thus polio patients typically suffer from acute flaccid paralysis of the legs ©- and/or arms.
The campaign launched by the WHO has consisted, in essence, of mass vaccination (with live oral polio vaccine),1 Anterior and disease surveillance: all new cases of acute flaccid horn cell paralysis are reported, poliomyelitis is diagnosed clinically (motor and then confirmed virologically by culturing the virus neuron) from the stool. Soon after the campaign began there was some controversy, particularly about the clinical diagnosis of polio. Whilst some authorities suggested this was a straightforward diagnosis, others argued that most polio patients may not have polio at all.
In Vietnam, where Dr Tom Solomon and colleagues have been studying patients with central nervous system
Right: At risk from poliovirus: the anterior horn cells of the spinal cord, which transmit impulses to muscles. Left:The regions affected by Japanese encephalitis virus.
infections since 1994, the polio eradication campaign his team had a lucky break. While testing a newly started in the early 1990s. By 1993 over 90 per cent of developed rapid diagnostic kit for Japanese encephalitis infants had been vaccinated, and the number ot virus, Dr Solomon included samples from paralysis patients virologically proven polio cases had fallen dramatically. to make up a batch. To his surprise, these samples gave However, the overall impact on cases of acute Haccid positive results. Naturally there was scepticism at first - paralysis and clinically diagnosed cases of polio was the kit had not been validated before - but repeated testing disappointing. In 1995, 450 cases of acute flaccid paralysis continued to give the same results. The samples were then were reported, including 130 cases diagnosed clinically as sent to collaborators in Bangkok, who tested the samples poliomyelitis, yet polio virus was isolated in only seven of with the accepted standard diagnostic technique for Japanese these cases. encephalitis virus. There was great excitement when the results came back confirming the team©s suspicions: many That year, Dr Solomon and his colleagues studied all children who clinically appeared to have polio were actually children with acute flaccid paralysis who came to the Centre infected with Japanese encephalitis virus. for Tropical Diseases in Ho Chi Minh City. Disconcertingly, although many children had clinical features typical of polio - a short fever followed immediately by a rapid onset of asymmetrical paralysis - it proved almost impossible to culture polio- virus from the stool. The- obvious practical explanations - problems in the collection, transport or culture of the stool - were ruled out because other harmless gut-dwelling viruses were easily grown. Whilst they were considering these puzzlintr , "" c AboveThe impact of the polio findings, Dr Solomon and eradication campaign in Vietnam. VIRAL PARALYSIS
New views of an old foe studies provided So what is known about Japanese encephalitis virus? It is evidence for endemic through most of Asia, causing more than 50 000 anterior horn cases of encephalitis and over 10 000 deaths every year. cell damage, and Epidemics of encephalitis were described in Japan more electromyography than 100 years ago, and the virus was first isolated in confirmed that the 1935. The epidemiology of the virus has changed in muscles were losing the last 50 years. In Japan, Korea and parts of China, their nerve supply. mass vaccination has reduced the number of cases. But Interestingly, a series of autopsies the geographical area affected by the virus has expanded of Japanese encephalitis patients published 50 years to include all of South-Fast Asia, most of China and ago reported that the spinal cord often looked similar the Indian subcontinent and, in recent years, northern to that seen in polio. Australia. It looks likely to remain an important public health problem into the next century. The discovery that Japanese encephalitis virus causes a poliomyelitis-like syndrome raises more questions than it The virus is transmitted by mosquitoes between pigs, answers. Has this syndrome been around for a long rime, chickens and other animals; humans become infected and simply been overlooked, or does it represent a new when living or working in close proximity to such sources variant of the disease? WHO figures for 1996 show that of virus. Although most people in rural Asia are infected more than half the world©s ©clinically diagnosed© polio cases during childhood, only about 1 in 300 people actually occurred in Asia, yet less than 10 per cent were proven develop disease symptoms, typically mental confusion, virologicallv. How many of these patients were infected with vomiting, neck stiffness, convulsions and coma. Until Japanese encephalitis virus? Is there a particular form of the this point, however, Japanese encephalitis virus had not virus which invades the spinal cord in preference to the been implicated as a cause of acute flaccid paralysis in brain, or is there some feature of the host that leads to the fully conscious patients. unusual clinical symptoms? With the support of a Wellcome Trust Fellowship, and the help of colleagues in Asia, Oxford, Because the virus is ubiquitous and many people are Liverpool and the USA, Dr Solomon is planning to infected without symptoms, Dr Solomon had to be investigate the immunology and molecular virology sure that the presence of Japanese encephalitis virus of Japanese encephalitis virus to try to answer antibodies - which is what the diagnostic tests some of these questions. detected - was not simply due to a recent coincidental infection with the virus. Comparison
with a hospital control group showed this was Top: A Vietnamese extremely unlikely - children at the hospital child receiving the polio vaccine. with acute flaccid paralysis were much more
likely to have Japanese encephalitis virus Left: A Vietnamese infection than matched hospital controls. child with polio-like illness due to Japanese encephalitis virus. The next challenge was to work out which part of the nervous system is damaged by the- Japanese encephalitis virus. If the virus causes Or Io»i Solomons work in Vietnam a disease that looks like polio clinically, is ii©iis funded l>y it Wellcome Trust it damaging the same cells in the anterior Advanced ©Imining Fellowship in horn of the spinal cord? The only way to Tropical Medicine between 199-t and answer this question was to bring all the 1998. He now holds a Wellcome Trust children back to hospital and study them Research Career Development electrophysiologically - not an easy task Fellowship tit the Departments of when they were spread across remote parts Neurological Science and Medical of southern Vietnam. Nerve conduction Microbiolog}; University of Liverpool. MARGARET 5 ROBINSON Coats of many colours Transporting proteins around the cell
Proteins are transported between various organelles of the cell by vesicles, which bud from one membrane and fuse with another. The formation of these vesicles and the selection of the right sort of cargo is dependent on coat proteins. There are several examples of human genetic disorders where a particular type of cargo is defective and is not packaged into a vesicle because it is not recognized by a coat, but up until now there have been no instances where the coat itself is defective. However, Dr Margaret Robinson and colleagues at the University ot Cambridge have discovered a new type of coat protein which is mutated in some strains of mice and some humans with a rare genetic disorder that alters pigmentation and causes kidney problems.
typical cell is packed full of membrane-bound icentrated in specialized indentations of the plasma organelles, or ©little organs , each with its own mbrane called coated pits. These pinch off to form A in and protein ated vesicles, bringing the lipoprotein to the inside of the ivhere it is then transported to lysosomes, the degradative is essential for the cell, since diftere nt events take place in gaudies in the cell. These studies showed for the first each organelle. However, cells conr nually send proteins and lie that the cell has the ability to select for specific cargo other molecules back and forth bet ©een various organelles ecules when transport vesicles are formed, and Brown inside vesicular containers. How is his accomplished d Goldstein proposed that the coat might somehow without all the organelles getting n pin re these molecules by specifically interacting with them.
The first clue came from studies by Mike Brown and |oe I irification and characterization of the coated vesicles, Goldstein in the mid-1970s on the uptake of low-density st accomplished by Barbara Pearse in 1975, revealed lipoproceins bound to the surface of human cells. They that the coats consist ot two components. One is clathrin, discovered that normally the lipoprotein is highly a remarkable molecule with a three-legged structure which
10 v,
sSf —
Plasma membrane Trans-Golgi network
Endoplasmic reticulum EndosQoie Proteins and other molecules are transported around the cell inside spherical ,»T • vesicles The adaptor Intermediate compartment 'o . "•' Lysosome protein (AP) complexes cargo inside the vesicle and with the surrounding Golgi stack clathrin cage. can spontaneously assemble into A new adaptor complex cages consisting of hexagons and As there are many membrane pentagons - an ability thought trafficking pathways in the cell to allow a spherical vesicle to in addition to those mediated form from a flat piece of by clathrin-coated vesicles, the membrane. The other search was on for novel proteins component is the adaptor related to the subunits of the protein or AI©, a complex of AIM and AP-2 complexes. four different suhunits, with a Other labs discovered the first structure resembling Mickey two such proteins - |J3, which Mouse. The adaptors attach the is homologous to the (J subunits clathrin to the membrane, and ofAP-1 and AP-2, and P3B, (as predicted by Brown and a neuronal-specific protein Cioldstein) they also interact with homologous to the p subunits of specific sorting signals on the proteins the two complexes. Work by Fiona that will be included in the vesicle. Simpson, a former PhD student in I)r Robinson©s lab, indicated that p.3 and In addition to the clathrin-coatcd vesicles P3B were part of the same complex, and Above:The Drosophi/o garnet that bud from the plasma membrane, Dr Robinson and her co-workers found the gene encodes the AP-3 rt subunit electron microscopists observed a second Flies with a garnet mutation missing rwo subunits: O3, which is related population of clathrin-coated vesicles, (left and right) have reduced eye R) the o sub units of AP-1 and AP-2; and 5, pigmentation compared to a budding from an organelle known as the wild-type fly (bottom). which is related to the y and (X subunits. trans-Golgi network - where proteins are They also found P3A - a variant of p3 sorted into different types of vesicles. While she was a found in all cells of the body, not just neurons. postdoctoral fellow in Barbara Pearses lab, Dr Margaret Robinson found that although the clathrin associated A more difficult task was establishing the role of this new with the two populations of coated vesicles is the same, the complex, now called AP-3. Localization studies indicated AP complexes are different. This led to the identification that AP-3 participates in a trafficking pathway involving and eventual cloning and sequencing of the four subunits the trans-Golgi network and endosomes, and a database of two distinct complexes, AP-I (associated with the search revealed that the 5 subunit resembles the protein trans-Golgi network and consisting of y, pi, jal, and Ol product of a Divsophila gene called gimit-f, one of the subunits) and AP-2 (associated with the plasma membrane classical eye-colour genes first described in 1915. Flies and consisting of a, P2, |a2, and O2 subunits). Both with the garnet mutation have defective pigment granules, AP complexes bind to similar types of sorting signals particularly in their eyes. There is evidence that in flies, as in proteins, although generally with different affinities, in vertebrates, pigment granules are related to lysosomes, suggesting that different but overlapping sets of cargo suggesting that AP-3 might have a more fundamental role proteins are sequestered into the two types of clathrin- in lysosomal biogenesis or in the transport of a particular coated vesicle. type of cargo to the lysosomc.
Right: A mocha (mh) mouse (right), which has a null mutation in the AP-3 6 subunit, next to its heterozygous littermate.The mh mouse has reduced pigmentation and a poor sense of balance
12 CELL TRAFFIC
Mocha mice and Hermansky- Cells labelled with antibodies Pudlak syndrome against AP-1 But AP-1 has also been implicated in trafficking to (red) and the lysosomes, so why is AP-3 needed as well and, in particular, AP-3 rt subunit (blue). what does the AP-3 complex do in mammals? Just as Dr Robinson and her group were considering ©knocking out one of the AP-3 genes in mice, they discovered that such mice already exist in nature. Within days of depositing the DNA sequences of the 5 and [33A genes in the database, endoplasmic reticulum at the non-permissive temperature they were contacted by three mouse geneticists in the USA: (interestingly, this is the same mutation that occurs in the Margit Burmeister, who had been working on a gene called Siamese cat, which accounts for the cat©s distinctive nwcha (which matched AP-3 5), and Michael Gorin and markings - only the cooler extremities being pigmented). Dick Swank, who had been collaborating on a gene called pearl (which matched AP-3 (53A). The mocha and pearl Are AP-3 subunits mutated in Hermansky-Pudlak genes are two out of 14 mouse genes with a mutant syndrome patients? In 1997, the Hermansky-Pudlak phenorype that resembles a human genetic disorder, syndrome gene was cloned in two different populations of Hermansky Pudlak syndrome. In both mice and humans, patients and, in both cases, it was found to be the human abnormalities in lysosomes and lysosome-relatcd organelles version of the mouse pale ear gene another of the mouse such as melanosomes (the mammalian pigment granules) mutants that resembles the human syndrome. However, cause reduced pigmentation - and unusual coat colours in not all patients appear to have mutations in that particular the mice - as well as prolonged bleeding and impaired gene, and very recently Juan Bonifacino and Bill Gahl at kidney function. the National Institutes of Health, USA, have identified a Hermansky-Pudlak syndrome patient with a mutation in What happens to protein sorting in the AP-3-deficient the (33A gene. Thus, it now seems likely that, in humans cells? Andrew Peden is studying the sorting of various as well as in mice, there are a number of different genes lysosomal proteins in cells from the mocha mice. Two which, when mutated, give rise to a Hermansky-Pudlak proteins show increased trafficking via the plasma syndrome phenotype. membrane, suggesting that the cell uses a ©belt and braces© approach to transport some proteins to the And are there more AP complexes waiting to be discovered? correct organelle. In other words, lysosomal membrane Dr Jennifer Hirst has recently identified all four subunits proteins are usually transported directly to the lysosome of a new complex, AP-4, using the same approach of using the AP-3 pathway, but in the absence or that pathway searching through the databases (a strategy they call more of these proteins leak out to the plasma membrane. ©armchair cloning©). Establishing the function of AP-4 will The cell is then able to retrieve them from the plasma not be easy, but Dr Robinson and her group are hoping membrane using the AP-2 pathway, and eventually they that once again genetics may provide some clues. Certainly arrive at the correct destination, although less efficiently. the Ending that mutations in AP-3 subunits can give rise to Hermansky-Pudlak syndrome is one of a growing Because there are more obvious abnormalities in number of examples where basic cell biology has led to melanosomes than in lysosomes in AP-3-deficient mice, insights into a human genetic disorder, while at the same Alex Theos is characterizing melanosome-specific proteins time the human genetic disorder has led to fundamental in mocha cells, focusing in particular on tyrosinase, the key insights into cell biology. enzyme in melanin biosynthesis. One advantage of- working with tyrosinase is that there are already a number of mutant Dr Margaret Robinson is at the Department of Clinical alleles available (because the mutant mice are so easy to Biochemistry, University of Cambridge, and currently holds a spot) which can be used in trafficking studies. These include Wellcome Trust Senior Research Fellowship in Basic Biomedical the platinum allele, where the protein is mis-sorted to the Science. In July 1999, she begins a Wellcome Trust Principal plasma membrane because it is missing the sorting signals Research Fellowship. Andrew Peden and Alex Theos an PhD that bind to AP complexes, and the Himalayan allele, where students in Dr Robinson©s lab, and Dr Jennifer Hirst is a the protein is temperature-sensitive and accumulates in the postdoctoral fellow.
13 DAVID WEATHERALL n tne b?ood Thalassaemias in South-East Asia
Genetic diseases are seldom considered to be a major public health problem in developing countries. This will not be the case for much longer, however. There is increasing evidence that the inherited disorders of haemoglobin, in particular the
thalassaemias and sickle cell anaemia the commonest singleC? Oeene diseases in humans - will pose an increasing health burden in the new millennium. Professor Sir David Weatherall and colleagues at the University of Oxford are investigating the frequency and effects on health of the thalassaemias in South-East Asia.
14 THALASSAEMIAS
u and (3 thalassaemias
Malaria
The world distribution of a and p thalassaermas, compared with that of malaria in pre- eradication days
s populations become richer, and the standards the population would have to be blood donors, and the of nutrition and public health improve, then total cost would equal or exceed the island©s health budget. Achildhood mortality tends to fall. With the exception of sub-Saharan Africa, where sickle Thalassaemias are inherited disorders cell anaemia is particularly common, of the globin chains that constitute childhood mortality has declined haemoglobin, the oxygen-carrying markedly in the developing world protein of the blood. Normal adults over the last 30 years. Throughout have a major haemoglobin consisting the Middle East, the Indian of two different pairs or chains, subcontinent and South-Hast Asia, a and (3, the production of either many thousands of children with of which may be affected to cause thalassaemia are born each year. a or P thalassaemias, respectively. Because many of these children will not, If the synthesis of one pair of globin chains as before, succumb to malnutrition and is defective, the other is made in excess, so infection, they will live long enough to damaging developing red blood cells. These require treatment for their blood disease. Above:A blood film of a diseases are inherited in a Mendelian recessive patient with thalassaemia, showing the abnormally fashion; children who inherit defective a or P The consequences of demographic changes pale red blood cells, many globin genes from both parents often have of this kind were graphically illustrated in of which are distorted. profound anaemia which necessitates life-long
Cyprus after World War II. After a Below:A normal blood film. blood transfusion. Their parents, who as successful malaria eradication programme carriers have only one set of defective genes, and accompanying improvements in are usually healthy except for mild anaemia. public health, it became clear that many Cypriot children suffered from For many years, Prolessor David a common form of anaemia, which Weatherall and his colleagues in Oxford was identified as thalassaemia in have been studying the a and P globin 1944. By the early 1970s, it was genes of thalassaemic children. Their estimated that, if no steps were goal is to determine why the taken to control the disease, in about production of the globin chains is 40 years© time the island would require defective, and how these abnormalities 78 000 units of blood per year to treat all interact with one another to produce the the severely affected children, 40 per cent of broad spectrum of diseases of differing severity
15 THALASSAEMIAS
that constitute the different forms of thalassaemia. that of the mainland, indicating that it had arisen de novo More recently. Professor Weatherall has led a collaborative in the islands. programme between workers in the MRL Molecular
Haematology Unit and Wellcome Trust-funded scientists To follow upr this observation, Steve Alien and Angelat> in the Institute of Molecular Medicine to investigate these O©Oonnell established a study in Papua New Guinea to diseases in South-East Asia. In particular, the group has ask whether having o. thalassaemia affects the likelihood tried to determine why the thalassaemias are so common, that an individual will develop serious complications of the potential health burden the}© will pose in the future, Pltisniodhim fiilcipannii malaria. They found, in fact, that and how, by a better understanding of the mechanism the milder forms of O. thalassaemia offered up to 60 per of disease, they may be managed more rationally. cent protection against malaria and, as an unexpected bonus, also protected against other severe infections. OL thalassaemia and malaria With between 20 and 70 per cent of children in many parts In 1949, J B S Haldane suggested that thalassaemia might of Asia being carriers of OC thalassaemia, this effect is clearlv be so prevalent because carriers were protected against an important determinant of the health of children in severe forms of malaria. For many years it proved very tropical climates, with profound public health implications. difficult to obtain any evidence that this was the case. While studying thalassaemia in Melanesia, however, the The study in Papua New Guinea was accompanied by a Oxford team noted a relationship between the frequency of parallel investigation on the island of Vanuatu. Tom O. thalassaemia and that of present or past malaria in Papua Williams and Kath Maitland determined the thalassaemia New Guinea and the island populations of Melanesia. status of over 900 newborn babies, and then observed their Furthermore, the type of a. thalassaemia was different to patterns of infection for several years. Surprisingly, babies THALASSAEMIAS
with Ot thalassaemia were more prone to To help redress this neglect, the both P. vivax and P, falciparum malaria Oxford team is now focusing on the infections, but only in the first year of natural history and pathophysiology of life. This suggests that the later protection haemoglobin E thalassaemia. A few years afforded against malaria may result from ago, Professor Weatherall was asked by an early immunizing infection, at a time Dr Shanthimala de Silva and her colleagues in their development when babies are in Sri Lanka to help them to identify the protected against malaria in other ways. different types of thalassaemia in their population; 500 600 children are receiving These observations are of particular regular blood transfusion for the disease. interest because of the increasing It turned out that there are two common likelihood that there is cross- P thalassaemia mutations and these, immunization between P. vivax and P. togedier with haemoglobin E, comprise falciparum an infection with P. vivax over 90 per cent of the thalassaemia alleles possibly reducing the severity of a later in Sri Lanka; about a third of the patients infection with P. falciparum. Thus, as in each of the main centres on the island well as providing considerable insights have haemoglobin E thalassaemia. A into the mechanism of protection against ... _ , ... . new study, involving over 150 children r b Top: Professor Weatherall with a malaria by 01 thalassaemia, these studies child with haemoglobin E thalassaemia with this form of thalassaemia, aims to have raised some important issues for from Bangladesh. understand why the disease is so variable,
malariologists - not in the least the Above:The thalassaemia blood to identify those who do not require inadvisability of ttying to eradicate transfusion ward in the Gerom Hospital, transfusion, and to help evolve the Anuradhapura, Sri Lanka. early P. vivax infections. most logical and economic approach to management. (3 thalassaemia and haemoglobin E In southern and South-East Asia, the important forms As haemoglobin E thalassaemia will provide such a of thalassaemia are P thalassaemia, haemoglobin E challenge in the new millennium, when over 3000 cases (a structural variant which is associated with a mild form will be born each year in Thailand alone, this information of p thalassaemia) and CX thalassaemia. Those who inherit is urgently needed. The outlook for more definitive forms genes for both p thalassaemia and haemoglobin E have a of treatment of the thalassaemias, by marrow- clinical disorder, haemoglobin E p thalassaemia, which transplantation or gene therapy, is currently fairly bleak. varies greatly in its severity - ranging from a condition Even if these tteatments do become available, their expense which is lethal without blood transfusion to one which may prohibit their widespread use. The best bet for success seems to be compatible with relatively normal development. at present is to work towards a rationalized management of the disease. In addition, if some form of control The Oxford team have been attempting to ascertain the programme for the very severe forms of homozygous P gene frequencies for these variants in parts of South-East thalassaemia can be developed along the lines of successful Asia. They have almost completed a study of the Indonesian Mediterranean programmes - in which the incidence of islands, and have calculated that approximately 4000-5000 serious thalassaemia has been markedly reduced by babies with homozygous P thalassaemia and haemoglobin E screening and prenatal diagnosis - it may be possible to P thalassaemia will be born into the population each year. If control these diseases in the future, only a proportion of these children receive regular blood transfusions, it will require approximately 1.7 million units of blood a year to sustain them in the future. Many patients with haemoglobin E thalassaemia are also being transfused at present, although it is not clear whether this is necessary - despite being probably the most common form of Professor Sir David Weatherall is at the Institute of Molecular thalassaemia globally, haemoglobin E thalassaemia has been Medicine, John Radclijfe Hospital, University of Oxford, and neglected by researchers over the years. holds a Wellcome Trust programme grant.
17 suisiimpgm jEjnjpD pire ajnjEu 9ip Supojdxg si
UOA"U1T[ 9311^ JOSS9JOIJ ©9§9TJO3 ^JBUIJ3J3^
- sisojodoajso yEsnBdouaui-jsod UT su ©Xpoq 3i^a ui
U3§OJJS3O JO S|3A3| 91JJ UT JTEJ V SI 9J9lja JI |IBJ OJ
©p9A|OAUl S9SS9J}S 9IJJ
E gip - 9SIDJ9X9 poisij unoiijj 9JB
SpBO| OJ p9Sodx9 9JB S9UOq U3l|^
U9OJ;S9O 9SIDJ9X9 'S9UOQ
i " r sjqissod si ji JsqjsqAv ui psjsajsjui si uoXuE-j JOSSSJGJJ -as Md spA3| usSojjsao paDTipai UEqj jaqjEj ©smsjqojd ssnro qoiqAv XEA\qjBd slip u; ssSuEqo pjsuBdousui-jsod sq XEUI jj
XEAvqjEd uouiiuo:> E qSnojqj SJ33JJ3 jpqj JJ3X3 U3§oijs30 pire UIBJJS jBqj siS3qjodXq aqj qjiAv JUSJSISUOD si ©SUIEJJS puoijaunj panmjucn sjidssp ©sstiBdouaui sqj JB SJTODO U3JLJO qaiqAV SSBUI suoq jo sso| aqj puE ©siqj^ UIBJJS SUIAVOJJOJ jBip osp jnq ©uopBjajijojd paonpui -uaSojjsao aqj Xjuo jou s>|3ojq sj]33 aqj oj sjsiuoSEjuE
Xpoq aqj ui jnoiABqaq Jiaqj SupjDiuiivu sd^qjad
©3JEJ3JI[Ojd Asqj ©U3§OJJS30 JO UIBJ1S J3l|J|3 O) p3Sodx3 pUC ajnjpo ui UMOiS SJE (s|po Supnpojd-suoq) sjscjqosjso usq/)\ -uopBuiquioD ui puc XpjciEdss ©areus puB
U3§OJ1S3O O) S||33 9UOq JO S3SUOdS3J 3qi §UIApnjS SI UIB3J
S(UoXuEq JOSS3JOJJ ©USSOIJSSO JO 3|OJ 3qj 3JE§US3AUI OJL U3UIOMJO 33UBU3 3qj ©QC) JO 9§B 3qj UIOJJ ©SnOpJBZBq 3q UB3 PUB ©u3UJOA\ ui p35[jBUi XpEjiiDijJBd si SSBUI suoq uj auipsp urejjs oj uoijEidcpB jo lusiuEqasui pnjDe 3qj ui pSAjoAui S!HX ©3JH J3JBI u! ssvm woo, Suiuipsp jsureSB Suijosjojd XBA\ duios ui si U3§ojjS3O jBqj sjS3§3ns siqj^ "SuiusqjSusjis ©uoi3]3j[S Suojjs ©sSjBj E pjinq oj dpq UB3 3uiij siqj
pUB UIBJJS 3UOq U33AtJ3q diqSUOIJEpJ 3IJEJSO3UJOq JB 3SIDJ3X3 poisXqd jo pupj jqSu 3qj^ "Suisu puE q8iq SJB
3qj UI U38OJJS3O .JO >[3B| B JOJ 31ESUaduJO3 JOU S3Op UIBJ1S (uoijBjdEpB suoq ui sjsXBjd ajqEqojd J3ipo) SJOJDEJ qjA\oj§
UI 3SB3J3UI UB ©3JOUIJ3qun,J ©pSAJOAUI SI U3§OJJS3O JBqj puB U3§OJ1S30 jo spA3| sqj usqM ©sjdosd SunoX ui yfesd sissSSns XjSuojis ©Xdcjsqi iu3ui33B]d3j suouuoq Xq ssoj siqi sji JE si UIBJJS jEpSajji jo J33JJ3 8uiU3ipSu3Jjs-3uoq sqj^ jo JS3JJB sqj puB ©3snBdou3ui sqj JB JRDOO UBD qDiqM ssoj
suoq pidBJ aqj jnq ©USUIOAV japjo ui SuiJB3q-pBoj oj jdBpB SJ3UIIUIMS pUE SJSlpXa UBqj (SSBUI 3UOq JO 3JHSE3UI
oj XjijiqB sji 3soj XBUI uojsp^s 3qj XqA\ UAVOUJJ jou si j[ 3AISEAUI-UOU B) XjISUSp pJSUIUI 3UOq J3l|§]L| 3AEq OJ
pU3J - SJJods (3IJSI]pq ; UI p3AJOAUI S3J3|qjB - SJSEUUlXS uounuon sjoui U3A3 3JB S3jnjDBJj pjqsjj3A SuunSgsip puB PUB sasXBjd jjBqX3||OA ©qsEnbs ©siuusj :Suipug siqj
SuijqBsip ©jnjuiBd 3|iqM ©XpAijssdssi ©auan jad /_\ puB juaa qjIM JU3JSISUOD 3JE SUBUjnq UI S3Ipnj§ -XjIAIJDE 3AIJIJ3d3J
jsd ^\ ©JU3D jsd g si snipBj jo diq ©snjsumq sqj SuiJnjaBjj p3[|OJ3UO3 3JOUI JO SpOIJdd 3uO| Xj3A U3A3 UEqj SSEUI 3UOq
SuiSBSJDUI UI 3AIJD3JJ3 3JOUI JBJ 3J3A\ SUIEJJS §Ul8uEq3 XjpidBj ©qSiqjo spoyjsd uoqs jBtp punoj UTESJ s^oXuB^
JOSS3JOJJ ©S33J§3p JU3J3JJIp OJ p3pEO| 3J3A\ SJBUIUIBUI puB spjiq jo sauoq 3i[j sjsqM s]U3uiuad\3 uj
USUIOAV psnBdousui
-JSOd JO JBqj JB|n3IJJBd UI pUE ©[BJ3U3§
UI qj3u3JJS SUOq 3JOUIOjd OJ sXEAiV pDI§O|O3BUIJBqd pUB pDisXqd PAOU Xjuuspi dpq XBUI q3JE3S3J sij-j -uojspjjs
8UOJJS E UIBJUIEUJ OJ J3BJ3JUI SJOJ3BJ OAVJ 3S3qj A\Oq pUB ©usSojjsso puB UIBJJS oj puodssj s|]33 suoq puE ssuoq A\oq
8uiJE8lJS3AUI 3JB S3n§E3||O3 pUB UoXuE^ 3DUE^ JOSS3JOJJ
©UOpUOq JO XjISJ3AIUQ ©3S3|JO^) XjEUIJ3J3/^ pXo")J 3qj jy uaSojjsso pire (SuipBoj uiojj sjjnssj qaiqA\) UIEJJS paisXqd
3JE UOIJBjdEpB Siqj UI SjaXBjd X3)J OAAJL ©3DU3U3dx3 Xsqj JBqj spBOj XBpXj3A3 3qj puBjsqj|A\ oj pssu Xsqj 3inj33jiq3JB I puE qjSusjjs sqj UIBJUIBUJ puE dopAsp oj jdBpB oj. 3AEq S3uoq ©ssjnjanjjs SuiSuEqaun Supq uiojj JB
N oiividva v 3 N o a to manipulate this pathway to amplify die this deterrence is removed. Alternatively, or imitate a strain-related stimulus, ^N^ signals emitted during apoptosis may influence and thereby artificially create a bone- osteoclasts directly. strengthening challenge from a load which would otherwise be relatively trivial and The functional relationships between bone not potentially harmful. cell types are clearly complex. For example, in ^ bone explants, where all the normal cell types What makes bones stronger? are present with their natural connections Changing bone architecture and adjusting __ _,_ intact, strain and oestrogen have a synergistic bone strength is not only the work of effect on osteoblast proliferation; in culture, osteoblasts forming new bone, but also of however, the combined effect is only additive. osteoclasts removing bone which is damaged In the intact situation, therefore, there are or inappropriately placed. Ostebolasts and other factors that contribute to the amount osteocytes reside in the bone itself, and are ^ of osteoblast rproliferation, factors that are not likely to be exposed and respond to both ^ present when the cells are in culture. It is also oestrogen and strain. Osteoclasts are derived |^V clear that, in the body, there are many other from the circulation, probably receiving their competing influences for bone cell activity, strain-related information indirectly from the resident and that when these are resolved, the strain-related cells which act as their ©sensors© and controllers. influences may be overwhelmed. And not all bones are similarly sensitive to strain. Those of the skull for One of the main themes of Professor Lanyon©s current instance, which need to be strong for reasons other than research is exploring the functional relationship between being repeatedly loaded, react differently from those in these bone cell types, with particular attention to whether the limbs whose prime reason is to resist functional loads. the programmed cell death - apoptosis - of osteocytes influences the activity of osteoclasts. Indeed, Dr Brendan Although physical activity has long been thought to Noble, who has recently joined the research team, has help bone architecture, traditional investigations into already shown that both strain and oestrogen reduce the the relationship between physical activity and human incidence of osteocycte apoptosis, while bone resorption adaptation generally focus on measures of cardiovascular by osteoclasts occurs preferentially in regions where performance. Such measures pay scant regard to the osteocyte apoptosis is high. This opens the possibility that stimuli to which bones adapt their architecture, and fail osteocytes may normally deter osteoclasts, and when they to assess these responses. Furthermore, the most common
Increased deposition Deposition
UNLOADED LOADED
Resorption Deposition
Fluorescent micrographs showing cross-sections of left and right ulnae in growing rats. Left: In the unloaded bone, new bone is being formed on one surface and removed on the opposite one. Right: In the bone loaded for an extra ten minutes a day, the amount of bone formation has increased and the resorption has been reversed into formation. jnq ©uoijdjossj auoq Suijiqiqui uo snaoj S3uoq JIEJI
©aSajjoj LivuuawA p£oy aqi iv si uo/Ctivj 33uvj uosssfojj JElfJ SJ3§UBp 31JJ SuipIOAB 3JIl{A\ ©p3p33U SI JI 3J3l{A\
SB3JB UI l|jSlI3J)S 3UOq SuiSE3J3UI Xq3J3l|J - UOIJBjdEpE
JE3p 3UJO33q XEUJ SUOIJSStlb 3S31JJ JO 3UJOS OJ SJ3MSUB 3l|J pajEpj-uiEJis SupuBijua jo 8up|3iuiiui jo sXBA\ puy ©ipuiijs paiuEipaui oj jdBpB oj sauoq jo sjnjrej aip oj oj sadoij uoXuBq JQSSSJOJJ ©uoijEjdcpE auoq psanpui
UOIJBpJ UI SISOJOdoajSO JO §UIpUBJSJ3pUn J3JB3J§ E IJJIjXV -pEO[ UI p3A[OAUI SUJSIUEq33UI JB|n||33 3qj SuiJ3AO3SIp Xg ;sisojodo3iso jo aauappui Suisu 3qj oj ps>juij ©X|p:3ixopEJEd snopjEZEi] sq pjnoAV suojap>[s 3|i8Bjj qjiA\ asoi|i oj siuuaj sdeijjad ©juauiuojiAua sqj ui susSojjsso ppyjjji; ui asu aip jo jjEqXsjjOA ©i{SEnbs jo usiuiSaj E Suiqu^sajd jnqj si paipnjs XppiAv 3JOUI jou SJB amjaajiijajB auoq jo [OJJUOD sn 8unjnd ©spAaj uaSojfisao AVO| oj ps^uij si ipiuM ©ssauuiip pajB|3J-3SpJ3X3 jo siijausq aijj XqM SUOSBSJ aqj jo 3UQ
JOJ UOIljSBj §U|SE3JDU1 3l)J SJ JUIBJ1S 8uiU3lJj3u3JJS-3«Oq
SS3| Ol Sn 3Sodx3 t[3iqA\ ©S3|XlS3jI| XjB)U3p3S X|§UISE3JDUT S3insE3Ui sjEudojddBUi ssn uajjo JJSA\ XEUJ suoq jo
01 p35JUIJ SJE3X ()Z 1SB| 3lp J3AO SISOJodoSlSO JO S3JBJ Xji|iqEjms [EjnjDnjjs ui saSuBija oj aspjaxa ursaSuEip 3je[3j oj p3pu3ju; saipnjs uEumij ©snqj_ ©Xjisusp [EJ3uiui suoq
3|ll|M ©3pIA\p|JOA\ STSOJodo3JSO JO S3JEJ JS3l|SllJ 31JJ 3AEIJ UI 32UEU,3 OU JO 3JJJIJ IJJIAV ©qj§U3JJS UO SJ33JJ3 pUHOJOjd
pUB|UI.J pUB JJJBUJU3Q UJ3IJ1JOU JO Sjdosd 31JJ Op ^U^ 3AEq UE3 SoSuEqD 3S31JJL 3EjnD3qBJJ JI31JJ JO JUSUJJSnfpE pUE uoXuB^ jossajojj anSujui suoijssnb jai|jo jo Xjusjj 3uoq ajoijAvjo ajnjEAjns suoq SB \pr\s ©sdBijs ui saSuEijo juBjjoduii jnq sjjqns Xq pgyipoui XjsnoaSBjuBApE aq XEUJ
"SJD3JJ3 UIJ3J-SuOJ JSJJSq qjIAV IplUAV ©3jnjD3JiqDJE 3UOq SS3SSE lJ3A3MOq ©JOU S3Op SJHSESUI maipSuajjs auoq pajBjaj-uiBjjs sau^qua oj 3|qi> aq XEUI siqjL ©suoq psuuEDS E jo Xjisusp JBJSUIIU 3qj jo JEIJJ uaaq
iVJJBUOIJIpEJJ SBl[ JpSJI SSEUJ 3UOq JO 3jn$E3UI 3AISBAUI-UOU
si SSELU auoq puE paqjosa.1 si auoq 'ssuipap UIEJJS j\ n»aj|L|DjE auoq pus sassajDUj SSEUJ auoq 'sasEajDUj iojsnD ;| -ISOD |E3|So|O!q puE XaajES uasMiaq aauE|Eq E
D 9UOq 'UOJ3|35|S 9U.J U| UOIJEDO| q3E3 JOJ auoq S33uan|ju; Xq anssjj auoq uo ?nd UIEJJS aip MOH
uojjdjosaj
sn|nuj;)s paivp^
NO I IVld VQ V 3 N O9 Above right and below lefc Segmentation in the chick hindbrain. Segments and eyes ANDREW LUMSDEN WILLIAM HARRIS
I To build a brain and visual system, the he central nervous system develops from the neural plate, a sheet of cells that rolls up into a tube that embryo must coordinate a myriad of T ns the length of the embryo. The front end of the genes and proteins during development. neural tube expands and then partitions into regions that will become the forebrain, midbrain and hindbrain. The The processes involved are similar in all back end of the neural tube is long and uniformly narrow; vertebrates, so researchers can use it will become the spinal cord. For normal function, each region of the nervous system must develop the appropriate different model organisms to investigate arrangement of different types of neurons, each with a different problems. At King©s College distinct identity in terms of shape, size, neurotransmitter content and synaptic connections with target cells. London, Professor Andrew Lumsden©s team is looking at the development of At Kings College London, Professor Andrew Lumsden and colleagues are investigating the development of the the hindbrain in the chick, while at the chick embryo hindbrain, perhaps the most primitive brain University of Cambridge, Professor region, and one whose basic structure and function vary little between different vertebrate species, be they fish, William Harris and colleagues are chicken or human. In addition to its internal connections exploring eye development in the within the central nervous system, the hindbrain makes extensive connections with the head and body, controlling African claw-toed frog Xenopus laevis. the muscles responsible for jaw movement and facial
Building the hindbrain and visual system
expression, as well as regulating respiration, heartbeat and other visceral functions. The researchers at King©s College have found that the hindbrain depends on segmentation for its correct development.
Segmentation is a developmental strategy that enables an embryo to form cell patterns on a modular basis - a small repeated scale - the pattern of which can be modified locally within each segment. Many invertebrates, such as flies, earthworms and lobsters, use segmentation to organize their whole body plan. In vertebrates, segmentation operates not only in the development of the hindbrain, but also in the spinal cord; here, however, the nervous system The hindbrain of a itself is unsegmented and it is the cartilage blocks lying three-day chick embr alongside and around the spinal cord that are segmented, is divided into eight rhombomeres (r1 to imposing their repeat pattern on the formation of spinal sensory ganglia and motor nerves.
Bumps in the hindbrain Immediately after the neural tube closes in the hindbrain region, it becomes constricted at evenly spaced intervals to form a series of eight bulges called rhombomeres.
23 NEURODEVELOPMENT
as could those from even-numbered rhombomeres. But cells in odd-numbered rhombomeres would not mix with cells in even-numbered rhombomeres - suggesting that there is a pair-wise, alternating pattern to the cell©s properties that allow, or prevent, cell mixing.
Although the mechanism that sets up these repeats is not known, it is thought to involve surface molecules, called Eph receptors, and their ligands, Ephrins. Cells in the odd-numbered rhombomeres express the receptors, and the evens express the ligands. A meeting between hgand and receptor at a rhombomere boundary may inhibit certain cell-adhesion mechanisms - specifically those that involve calcium-dependent adhesion molecules called cadherins - such that cells cannot move into the neighbouring territory. This pair-wise arrangement of rhombomeres therefore sets up the boundaries not by the expression of different adhesion molecules in different segments, but by turning off a common adhesion mechanism at the boundary - hence, Setting the boundaries: the cells in a particular rhombomere ©stick© together in If a cell is labelled with preference to sticking to those in the neighbouring segment. a fluorescent dye (red) before the rhombomere boundaries form, its The Hox code descendants can be found in more than one Once the repeat pattern is set up in the hindbrain rhombomere; if labelled through the expression of Eph receptor and Ephrin ligand at a later stage, the cell's genes, other genes that govern the final identity of each descendants (blue) are always found in one rhombomere are expressed. In the fruitHy. this process compartment. of segment determination is carried out by the homeotic genes - the Antennapedia/Bithorax complexes of genes. These rhombomeres are found in all vertebrate embryos Homologues of these genes, called the Hox genes, carry out and are developmental compartments - cells within a the same role in vertebrates. Unlike the fly, which has one rhombomere do not mix or merge with cells in adjacent cluster of these genes, vertebrates have four closely related rhombomeres. In collaboration with Scott Fraser at Caltech, clusters. Dr David Wilkinson and Dr Robb Krumlauf at USA - who perfected a technique for labelling single cells the National Institute for Medical Research, London, were in chick embryos with fluorescent dyes - Professor I.umsden the first to find that the boundaries of Hox gene expression and colleagues found that if a hindbrain cell is labelled coincide with rhombomere boundaries. For example, Hoxa2 before rhombomeres form, its descendants can be found is expressed in all the rhombomeres except rhombomere 1, on both sides of a boundary between rhombomeres. whereas Hoxb2 is not expressed in rhombomeres 1 or 2. If a cell is labelled after the boundaries form, however, the The identity of each rhombomere could thus depend on descendants never cross the line. This compartmentation the particular combination of Hox genes expressed within is transient but persists during the critical period of it, and on the level of expression of each gene. development when neurons arc being produced in the hindbrain. Changing the pattern of expression of a gene can often give valuable clues about its role. For example, expression How does the hindbrain set up these boundaries? When can be prevented - by ©knocking out© the gene from the Professor I.umsden©s group transplanted rhombomeres whole organism or by blocking its activity in a particular to different positions in the hindbrain - such as putting region or it can be increased. At present, it is not rhombomere 3 next to rhombomere 5 - they found that possible to ©knock-out a gene in avians, but a mouse cells from odd-numbered rhombomeres could mix together, knockout of Hoxbl, produced by Dr Michele Studer at
24 NEURODEVELOPMENT
NIMR, and interpreted in collaboration with Professor The neural Crest Lumsden, showed that the loss ot this gene, which is normally In vertebrates, most of the cartilage, bone and connective expressed at high levels in rhombomere 4, gives rhombomere tissues are formed from precursor tissue, mesoderm, lying 4 the identity of rhombomere 2. The chick is ideal for the beneath and beside the central nervous system. However, opposite experiment, however, as engineered avian viruses the head has such a large neural plate for developing the can be used to overexpress genes in specific regions. When brain that there is little room for mesoderm. So the neural Professor Lumsden and colleagues used such viruses to express crest - a migrarory population of cells that forms at the Hoxbl in rhombomere 2 (where it is not normally expressed), edge of the neural plate - takes on the role of the they found that specific cells in rhombomere 2 that normally mesoderm, producing the cartilage, bone and connective connect with the jaw muscles instead grew out and connected tissues of the head, as well as the dentine of teeth. In the with facial muscles, the normal target of rhombomere 4 case of the hindbrain, the neural crest cells migrate out neurons. So the Hox genes specify not only the identity of from the top edges of the rhombomeres into three the rhombomeres, but also the guidance system that allows ©branchial arches© that lie beneath the hindbrain. The first the extending cellular processes of neurons to navigate to arch, which fills with neural crest cells from rhombomeres the right place in the embryo. 1 and 2, builds the jaws, while the second (from rhombomere 4) and diird (from rhombomeres 6 and 7) The alteration in segmental identity produced by adding; arches build the structures ot the throat, including the the expression of the Hox gene is called homeotic, because hyoid - a small delicate bone in the base ot the tongue. it makes one segment take on the appearance of another segment in the series. The significance of these homeotic Not only do individual rhombomeres contain neurons with transformations of hindbrain segment identity is that they specific identities, but they also impose their individual show how cell pattern, itself involving probably hundreds character on the structures produced by their associated ot genes, can be controlled and profoundly varied by one neural crest cells. For example, it crest cells ot rhombomere or a few master control genes. 4 are replaced before migration by rhombomere 2
Developmental mechanisms of the chick hindbrain The left-hand side shows the expression boundaries of the Hox genes; the right-hand side shows how the motor neurons migrate into the branchial arches behind the neural crest cells, whose identity is also specified by Hox genes. Neural crest cells do not migrate from rhombomeres 3 and 5.
Neural crest NEURODEVELOPMENT
crest cells from another individual, the transplanted many of these genes are also to be found at work cells enter the second arch but build structures in the development of invertebrates such as the characteristic of the first arch. This, can result in the fruitfly, although in this case the final product - development of a chick embryo with two sets ot the faceted eye - looks very different. At the jaws. Professor Lumsclen and colleagues have University of Cambridge, Professor William also found that neural crest cells do not mix The separating Harris and his colleagues are exploring eye when they are building the structures associated eye field labelled for development in the African claw-toed frog, an eye-field-specific Xenopus laevis, an animal with a long history with the branchial arches. A portion ot the- gene in an early lower jaw is normally derived from Xenopus embryo. of experimental embryology. rhombomere 4 crest cells, and there is a very sharp boundary where these cells meet those from About 12 hours after fertilization, the ball of cells that rhombomere 2, with no intermingling. This has no is the Xenopus embryo is beginning to organize itself consequence for morphology, as the lower jaw is a single into different types of tissue. Within the prospective unit and the junction between the cells is invisible. neural tissue, a small, rather undistinguished disc of cells However, it shows how, during development, the - the eye field - is destined to become the eyes. Only vertebrate head is built piecemeal, as if of ©Lego bricks , 36 hours later, the now tadpole-shaped ©tailbud embryo© with clearly defined cell territories. The building blocks has two perfect, tiny eyes, capable of seeing the world can be independent of the structures they make. and guiding visual behaviour. Within this short span of time, the eye field has split into two, cells have moved Looking forward to opposite sides of the head, and each optic cup has Why is the hindbrain the ©most primitive© part of the brain? formed the key components of the eye - pigmented The earliest vertebrates were probably filter-feeders with cells at the back, retinal layers in the middle, and a a basket-like branchial arch region and a simple neural focusing lens at the front. regulator (what became the hindbrain) to pump water in one end and out the sides. Later, the vertebrates gained This remarkable transformation depends on a precisely propulsion at the back end - also using segmentation 10 regulated sequence of events. Specific genes must be build the mesodermal spinal column - and then added expressed not only at the right time, but also in the sense organs at the front, to avoid bumping into things right place in the embryo. Professor Harris and his and enlarging the area of the brain associated with the team are working to pick apart the roles of the plethora nose and eyes. Whether this area - the forebrain - of of genes and interactions involved. modern vertebrates is also built by segmentation is a question now being investigated by Professor Lumsden©s The origin of the eyes team, although a more elaborate mechanism, with extensive What occurs in the eye field, driving these cells to become cell communication between component regions, is likely eyes instead of another body part or another region of the to be involved. Although it is doubtful that development brain© The key factors appear to be a series of genes whose of the forebrain cortex employs segmentation, the expression is turned on specifically in this small region. researchers at King©s College ate hopeful that what they Several of these genes have been identified in the past have learned about hindbrain development will help few years - Optix2, Si.\3, ET, Pax6 and Rxl among others. begin to unravel the complexity of btain development. Professor Harris and colleagues have recently been examining the role ot Optix2, which drives the enlargement of the eye. Loss of the chromosomal region containing the human Opti.\2 gene results in anophthalmia (where the eyes fail to develop). In Xenopus, if Opnx2 is overexpressed on Making eyes one side of the animal, the expression of other eye field genes is upregulated on that side, and the result is a giant eye. Whether fish, frogs or humans, vertebrates have remarkably similar eyes. All are shaped in the same way and the Having defined a single eye field, the embryo must developmental processes follow similar pathways and work towards producing two eyes. A signal from a protein involve many of the same genes and gene families. Indeed, called Sonic hedgehog tells a central strip of cells in the
26 NEURODEVELOPMENT
eye field to switch off eye-specific genes such as Pax6 and the amount of cell division, which Is intrinsically switch on Pax2 instead. Pax2 promotes the formation of determined by the level of expression of the O/>to"2gene. the optic stalk, linking the eye to the brain. Without this This, in turn, controls the expression of genes that control signal, for example if Sonic hedgehog is not delivered cell division more directly. correctly, the eye field will not separate and the animal - whether frog or human - will develop a single, cyclopic To discover the mechanisms involved in the regulation eye. Indeed, pregnant sheep in the USA that have of cell division in the retina. Professor Harris and his team wandered off pasture and eaten corn lily, which contains are looking at the role of the cell-cycle genes - which have a mutagen that interferes with hedgehog signalling, been well studied in Xenopus oocytes - in the developing have produced cyclopic lambs. The mutagen isolated eye. In particular, they are interested in the Xicl gene, from these plants is appropriately called ©cyclopamine©. which appears 10 put the brakes on the cell cycle by In Xenopus, overactivity of the hedgehog pathway at inhibiting a cell-cycle klnase. In the retina, the cells that this stage of development does just the opposite, and are ready to pull out of the cell cycle and differentiate turns ventral retina into extra optic stalk tissue. start uprcgulating the expression of Xicl - reducing the
Stage 15
Left:A front-on look at the progressive retinal cell types. Right;The development sequence of gene expression (orange) driving of the eye is only part of the complex the development of the Xenopus eye. Stage 15. transformation undertaken by the Xenopus a tailbud embryo (stage 26-28), and by stage separating eye field; stage 23-28, formation of embryo The neurula (stage 15). where the 45 a mature tadpole hatches out of its jelly the optic cups; stage 35/36, differentiation of first neural tissue is specified, quickly becomes covering and begins to swim and feed.
Eye size and cell division prospects for further division of these cells. When Xicl is The cells in the two halves of the eye field then begin overexpressed in scattered cells in the retina, these cells pull streaming to outpocketings on opposite sides of the head. out of the cell cycle prematurely and start differentiating. It Having reached the optic cup, the cells diverge into the two is hoped that such studies \v\ll provide missing links major layers of the retina the pigment epithelium and the between cell-cycle control and cellular differentiation. neural retina. Each layer expresses its own set of genes. 1 he cells keep dividing throughout the eye field and migration In frogs and fish, the retina keeps growing throughout the stages, but at the optic cup some cells stop dividing and life of the animal - hence a small goldfish has small eyes, begin differentiating as eye-specific cell types. Different while a giant goldfish has giant eyes. Cells are added in species of animals have different-sized eyes relative to the rings at the periphery - like a tree - so the oldest cells arc size of their heads, the size of the eye being determined by in the centre. I his periphery, or marginal zone, retains a
27 NEURODEVELOPMENT
population of undifterentiated stem Having differentiated, the ;anglion cells produce a ganglion cells at its outetmost edge; the progeny of these stem cells divide a tew cell-inhibiting factor, so that more times and then differentiate. the next set of cells to As one looks from the edgi differentiate will become towards the centre ot the a different type of marginal zone in the cell, such as neural retina there is a photoreceptors. As spatial ordering of gene the number of cell expression: in the outermost types increases, cells region, the cells express the genes driving will differentiate in an b---- them to become retinal and the genes that increasingly complex environment of Proliferation and retinal specification keep the cell cycle going. In the middle different inhibitory factors. Vertebrates (Six3,Kx1,Pox6) part of the marginal zone, cells express space out cell subtypes in a mosaic, neural cell-type genes and genes like Xicl so that cells of the same subtype are Proneural and neurogenic region spread evenly and regularly across that slow down division. Finally, in the (Xashl) inner part of the marginal zone, cell-type- the retina. Another thread of Professor specifie genes start to be turned on as Harriss work is to understand the Cellular detei role of the regulator)© proteins in the new cells select their particular retinal (XothS) fates. By examining the ordering of Molecular P - • - • this spacing process. As with ganglion gene expression in the marginal zone, development Post-mitotic region cells inhibiting later differentiating in the ciliary cells from becoming ganglion cells, which recapitulates in space the temporal marginal zone y------development of the whole retina, The cells at the very Differentiation cells of a particular subclass inhibit Professor Harris and his team have been edge of the retina (left) (Brn3) their immediate neighbours, through are proliferating and ready able to identify key stages in the transition to form new retina ceNs; a molecular lateral inhibitory pathway, from dividing cell to fully fledged retinal further in, proneural and from becoming a member of the neurogenic genes are pushing the cell. Altering the expression or function same subclass. cells towards a neural fate.The cells of these genes causes predictable defects stop proliferating in the post-mitotic in retinal development region, and mature into fully differentiated These myriad factors, and the cascade retinal cell types. (Many other genes are also likely to be involved at each stage.) of signalling and gene transcription A retinal mosaic that leads a cell down a particular To be fully functional, the final retina requires seven different path, will take many years of research to pick apart. As in classes ot cell, including photoreceptors (where the visual input many areas of biology, each discovery in eye development signal is transduced into a neural signal), ganglion cells (the throws up new questions and uncovers further complexity. output cells of the eye that send messages to the rest of the Professor Harris hopes that his work will help to generate brain) and several other cell types in between. But each type a ©genetic matrix©, in which we fully understand the of cell consists of many subclasses. For instance the photore relationship between the genes and processes involved in ceptors consist of one type of rod cell (for black and white the 36 hours ot eye development in the Xenopus embryo. vision) and three types of cone cell (red, green and blue), so in all, 50 or more different cell types must be specified. Professor Andrew Lmmden is in the Department of Developmental Neurobiology, King©s College, Guy©s Hospital Professor Harris and colleagues have shown that it is not the Campus, London, and holds a Wellcome Trust programme birth date of the cells that influences the final type of cell they grant. Professor William Harris is at the Department of will become, but their differentiation order. So, for example. Anatomy, University of Cambridge, and holds a Wellcome the first cells to differentiate will become ganglion cells. Trust programme grant.
28 GILLIAN A5HCROFT
Skin is the largest organ in the body, acting as a barrier to protect our ealth internal structures from environmental insults. When this barrier is disrupted, a complex series of events is set in motion, ultimately leading to repair of scar the defect and resulting in a scar. In the fetus, complete regeneration of the skin can occur after wounding, story but healing becomes compromised with age. This results in slow healing and the development of chronic Wound healin; wounds, costing the Health Services and ageing in the UK up to f 1 billion each year. At the University of Manchester, ; we age, our skin becomes less resilien Dr Gillian Ashcroft is investigating ts capacity for rapid and efficient repa r. In the A.elderly, the healing of wounds is often mpaired the effects of ageing on wound healing, significantly, leading to pain, immobility, infect on and and has shown that sex hormones may sometimes death. Not only are there problems vith healing following acute wounding, such as that from reverse age-related changes. surgical operations, but relatively minor skin injuries can often lead to the development of chronic ulcers. At the University of Manchester, Dr Gillian Ashcroft is investigating why ageing influences the rate and quality of healing. With an understanding of non- healing in the elderly, she hopes that treatments suitable for skin or wounds can be devised in the future.
Two French Army surgeons in World War I, Carrell and DuNouy, first suggested that ageing impairs the healing of skin. Their study was criticized, however, because the soldiers they studied were aged between 20 and 39 years. Other studies addressing One of the most marked age-related changes observed, both the question of ageing and healing have failed to take in normal skin and during wound repair, was a substantial account of factors such as other illnesses, types of increase in the levels of proteases which break down the medication, diet and smoking - all of which can delay linking proteins of the matrix. This increase in proteolytic wound healing irrespective of patient age. activity may delay the rate of wound repair in the elderly by degrading newly formed matrix and, in normal aged skin, To dissect out the role of ageing in the pathogenesis may predispose these individuals to delayed healing following of impaired healing, as opposed to the role ot external minor cuts and abrasions. factors, healthy subjects must be studied. Dr Ashcroft has undertaken the first large-scale study of over 180 healthy Regeneration in the elderly subjects aged from 19 to 96 years of age, often recruiting; In prenatal life, the fetus can regenerate damaged tissue elderly people from tea dances and old people©s clubs. completely, but wounds incurred after birth often leave scars. The examination of skin and wound samples taken from Severe scarring presents several clinical problems, not only in each individual showed that ageing in healthy humans is terms ot cosmetic appearance, but also by impairing the associated with a marked delay in the laying-down of function of the skin and restricting further growth. Surprisingly, new skin epithelial cells and of the extracellular matrix Dr Ashcroft has shown that, even though the rate of healing is that holds the cells together. There were also significant slower in the elderly, the amount of scarring is dramatically differences in the inflammatory response at the wound site. reduced - so the quality of healing actually improves with age.
30 WOUND HEALING
One particular molecule, transforming growth factor |3l have supported these findings, as oestrogen regulates (TGF-(5l), has received a great amount of attention in the functions of both connective-tissue cells and immune the context of wound repair - being involved in cell cells, with effects on the production of both TGF-(3l and proliferation, differentiation and the production of proteases. extracellular matrix. Indeed, an increase in the levels of TGF-|3l - whether applied at the site of a wound or As wound healing and scarring in humans appears to injected systemically - accelerates the rate of repair in be under the control of oestrogen, there are numerous animals. Interestingly, females heal more quickly than interesting therapeutic implications. In particular, one can males, and the wounds of females have significantly envisage ways to accelerate the healing by the application greater levels of TGF-(3l compared to those of males. of oestrogen directly to a wound, or to reduce scarring by Although TGF-(3l would appear to have only beneficial the use of compounds that antagonize oestrogen. These effects on the rate of wound healing, its levels at the site effects of ageing and hormones on molecules such as of the wound may determine the amount of scarring. For TGF-)3l may also be applicable to problems such as skin example, previous research in Professor Mark Ferguson©s ageing and ulceration, the lysis of atherosclerotic plaques, laboratory at the University of Manchester found that the and osteoporosis, and point to the overall beneficial effects neutralization ofTGF-(3l could reduce or prevent scars. of hormone replacement therapy. Dr Ashcroft©s research has extended these findings in the context of ageing: the levels of TGF-(3l are significantly Finally, it is interesting that the two extreme time-points lower in the wounds of the elderly - which may account of life - fetal and old age - share similar regenerative not only for the delay in healing, but also, paradoxically, mechanisms of wound healing, both being characterized for the improved quality of scarring observed. by reduced levels of TGF-(3l and reduced scarring. This suggests that the adult scarring phenotype has either been Although the treatment of acute and chronic wounds actively selected for during evolution perhaps as a with specific molecules such asTGF-pl is an attractive reminder of previous inappropriate behaviour- or proposition, the high levels of proteases in the wound passively selected for as a result of co-selection for would be likely to degrade it immediately. Dr Ashcroft©s other advantageous phenomena such as an enhanced results suggested another approach: if those middle-aged inflammatory response or the speed of healing. In this females who had been experimentally wounded were context, it is interesting that no animal scars as badly divided inro pre- and post-menopausal groups, then pre- following wounding as man and woman. menopausal females healed similarly to the young, but the post-menopausal females healed slowly albeit with less Dr Gillian Ashcroft holds a Wellcome Trust Clinician Scientist scarring - like the elderly females. This suggested that Fellows!}!f> at the Department of Cell and Structural Biology, hormones may be pivotal to the wound healing process. School of Biological Sciences, University of Manchester.
The role of oestrogen After the menopause, female skin undergoes profound changes - for example, it becomes thinner and contains less collagen. As oestrogen creams can improve the external appearance of post-menopausal facial skin, and hormone replacement therapy increases the amount of collagen and limits the thinning of the skin, the decline in circulating levels of oestrogen that occurs after the menopause may also influence the scarring potential. To explore this idea, Dr Ashcroft has studied the effects of oestrogen on wound healing in post-menopausal females, and has extended these studies to animal models. She has found that both oral and topically applied oestrogen affects wound healing, reversing ,n oestrogen skin the age-related changes in inflammation and increases in the patch, used in hormone levels of proteases at the site of the wound. Studies in ritro replacement therapy. JOHN MULLINS A pressure situation The control of blood pressure High blood pressure significantly increases the risk of having a stroke or of developing heart disease. Although smoking, obesity and alcohol are known risk factors, many people with high blood pressure have no obvious single underlying cause. At the University of Edinburgh, Professor John Mullins and colleagues are using a combination of classic physiology and modern genetic techniques in rats and mice to investigate renin, a key regulator of blood pressure.
0 40 20 300 / mmHg BLOOD PRESSURE
ammalian blood pressure is controlled by the interaction of M several mechanisms. Some respond very quickly to changes in blood pressure - tor example, to counteract a sudden drop in blood pressure after a severe wound - while others continue to work over a longer time scale. One of the key latter mechanisms is the renin-angiotensin system, which acts to relieve abnormally low blood pressure.
At the entrance to each glomerulus - where the blood vessels feed in to the filtration units ot the kidney - lie some very specialized renin-producing cells. These juxtaglomerular cells, wrhich are modified arterial smooth muscle cells, store huge amounts of the renin precursor Angiotensin- protein, proremn, in granules, allowing the renin time to , converting • ** enzyme (ACE) mature into its active form before being released into the circulation. In the blood, renin begins a cascade that ends in the production of angiotensin-2; this peptide stimulates blood vessels to constrict, so the stimulation of angiotensin-2 concentration will raise blood pressure very rapidly.
At the University of Edinburgh, Professor John Mullins and colleagues are investigating how the juxtaglomerular cells produce, store and release renin. Using a combination of Constriction of blood vessels genetics and physiology in both rats and mice, they hope to understand how the juxtaglomerular cells respond to blood Renin, produced from prorenin by the kidney, acts on angiotensinogen, pressure and how, in times of low pressure, more artery cells produced by the liver, to create angiotensin-LThis is converted to at the entrance to the glomerulus begin producing renin. A angiotei,sm-2, which stimulates blood vessels to constrict, thereby raising blood pressure.The role of the low levels of prorenin found in basic knowledge of how these cells respond to physiological the circulation is unknown. change will not only enhance our understanding of blood pressure control by the renin-angiotensin system, but is likely to yield insights into cellular differentiation in response to physiologically important stimuli - such as pressure and stretch - and lead to possible new targets tor antihypertensive and vascular therapies.
Rodents large and small Historically, studies ot blood pressure have been carried out in the rat. There are several strains of rat with high blood pressure, some of which have arisen poncaneously and some of which have been produced by selective breeding. Their thick tails are ideal tor taking measurements of blood pressure, in a manner identical to that used in humans - add a cuff, pump it up until the blood flow stops, and then relieve the pressure and follow the heart cats. But studies of the genetics of blood pressure are difficult in rats, as it is still not yet possible to knock-
33 ;LOOD PRESSURE
out a gene in a rat. Genetic technologies are much more Losing renin advanced in mice, hut until recently it has been difficult to When the renin-2 gene was knocked out, the mice had take measurements of blood pressure in such small animals. perfectly normal blood pressure - indicating that renin-2 Only in the last year has electronic miniaturi/ation enabled is not essential for normal homcostasis - but when pressure sensors to be implanted in mice - without Professor Mullins and his team knocked-out the renin-1 deleterious effects on their health and lifespan. gene, they found a rather different effect. While the males had normal blood pressure, the females were unable to Mice are the only mammals known to have two renin genes. regulate their blood pressure correctly without renin-1 About ten years ago, it was thought that the rennt-2 gene and were hypotensive - they had low pressure. When the was merely a curiosity, with no real biological effect and no researchers looked at the juxtaglomerular cells in either role in the regulation of blood pressure. Indeed, some strains males or females, they found that there were no renin of wild mice cope with just the one renin gene. But renin-2 storage granules present. So these cells were now able to turns out to be a very interesting protein in its own right. make only miin-2, which was not stored and was secreted directly out of the cells into the circulation. Although it is In the juxtaglomerular cells, the two renin genes are expressed not clear why the males have normal blood pressure, at approximately the same level - so, in principle, each gene Professor Mullins suspects that it is because the males could contribute to blood pressure regulation to the same produce large amounts of renin-2 outside the kidney, extent. To test the roles of each gene, Professor Mullins and his which may compensate for the loss of renin-1. team have ©knocked out© each gene independently in mice.
Arterial smooth muscle cells
Juxtaglomerular cells
Blood flow out
Normal blood pressure Juxtaglomerular cells, with renin Blood filtration storage granules
Chronic high Glomerulus blood pressure (or no renin-1 gene in mouse) Expression of renin undetectable.
Changes in blood pressure influence the expression of renin and the Chronic low differentiation of the juxtaglomerular cells. When blood pressure is too blood pressure low, the expression of renin increases in the juxtagbmerular cells and Synthesis of renin more smooth muscle cells of the artery differentiate into renin-producing increases, and more cells. When blood pressure is too high, or when the renin-? gene is arterial smooth muscle 'knocked out' in mice, no storage granules of renin can be detected in the cells differentiate into cells at the entrance to the glomerulus. renin-producing cells.
34 BLOOD PRESSURE
Renin at the heart If the miin-1 knockout mice arc not able to store and mature prorenin in the kidney, how are males able to regulate their blood pressure normally? Does the body have other mechanisms that can activate renin? These questions point to other, as yet undetermined effects of renin. Although the juxtaglomerular cells in the kidney are the primary sources of renin, prorenin is also produced in many other tissues, such as the testes.
A clue to the effects of prorenin has come from transgenic rats - produced using techniques pioneered by Professor Mullms and colleagues. When they expressed the mouse renin-2 protein in the rat - the function of which was not known - they found that the rats become hypertensive, with large amounts of prorenin-2 in the bloodstream. But there was also active processed renin-2 in the circulation, even when expression was restricted to the liver (which does not process prorenin). Particularly high levels of renin were detected in the heart, suggesting that the heart is able to take up prorenin, and may activate it locally.
In this rat, the renin has a potent effect on the heart, which by six weeks of age is double the size of the hearts of its normal counterparts. The effects are exaggerated because the expression levels of prorenin are so high, but these results suggest that prorenin in the bloodstream may also be having
The expression of renin-! (dark blue) in the mouse kidney. subtle, as yet undetected effects on the human heart.
The renin-1 and renin-2 genes produce very similar This marriage between modern genetic technologies proteins, with few - but potentially important - differences and classic physiology enables Professor Mullins and in their sequences. One key difference is that the renin-1 colleagues to ask key questions about the regulation of protein is a glycosylated enzyme with sugar molecules blood pressure. But they also hope to understand the role added to specific sites - while renin-2 is non-glycosylared. of renin in other parts of the body - such as the heart - Glycosylation is thought to affect how the cells producing and how the juxtaglomerular cells detect changes in renin actually deal with the enzyme: if it is glycosylated, it pressure by the amount of©stretch© in their cell walls. For will be stored in vesicles in the cell and matured, while the these latter experiments, as well as studying isolated cells, non-glycosylated enzyme will be secreted out of the cell into they plan to add zebrafish for which a powerful array the bloodstream immediately in its inactive precursor form. of genetic technologies has been developed - to their line up of experimental organisms. With these additional tools, To discover whether glycosylation is, in fact, the key Professor Mullins and colleagues hope to gain further storage signal, Dr Matthew Sharp and Dr Cathy I©ayne insights into the detection and control of blood pressure are engineering mutant renin-1 and renin-2 genes with in vertebrates. specific changes to the glycosylation sites. When these variants are introduced into the renin-1 knock-out, they should reveal which part of the mouse renin-1 protein - and, by inference, which part of the human renin enzyme - Professor John Mulliiis is ir Wellcome Trust Principal Research specifies the ability to be stored in granules and matured Fellow itt the Medical School, Tevior Place, Lhiiversity of in the juxtaglomerular cells. Edinburgh, and holds a Wellcome Trust progriiinme "mm.
35 KH1LL ' BART BARRELL I JULIAN KETLEY I BRENDAN WREN JULIAN PAR The fu Campy The genome sequence of a food-borne pathogen
In September 1998, after barely nine months, the Pathogen Genome Sequencing group at the Sanger Centre finished reading the genome of Campylobacter jejuni - the most frequently reported cause of bacterial gastroenteritis. Using the complete sequence - which has already yielded a number of interesting clues - linked to powerful new technologies, researchers hope to identify why Campylobacter causes food poisoning and, in some cases, neuromuscular disease.
36 CAMPYLOBACTER
alf the poultry destined for human consumption Sequencing Campylobacter harbour Campylobacter jejitni. Although it is Sequencing the 1.64 million nucleotides of the genome killed by proper cooking, it is perhaps unsurprising of C. jejuni began in January 1998 at the Sanger Centre that this gut-dwelling bacterium has risen from relative in Hinxton, Cambridgeshire, under the direction of obscurity to become the leading cause of reported bacterial Dr Julian Parkhill and Dr Bart Barrel!. The organism food poisoning worldwide. There were 58 068 reported lent itself to sequencing: the genome is small (just over cases in the UK in 1998 - an 18 per cent increase on the a third of the size of Escherichia tv/i or Salmonella typhi) 1997 figures - and, as only a fraction of cases is reported, and has a favourably low G+C (guanine + cytosine) base Campylobacter infection represents a major public health and composition of 31 per cent, allowing long and accurate economic burden. Infection with C. jejuni \s very unpleasant sequences to be read. Unlike other bacterial genomes, - a drawn-out form of severe inflammatory bloody C. jejuni is surprisingly free of repetitive DNA elements, diarrhoea that usually lasts up to one week. On occasions, so the DNA sequences are relatively easy to fit together. which are thankfully rare, food poisoning with C. jejuni Thus, after a total of 33 824 sequencing experiments, the can be followed by severe neuromuscular symptoms known entire genome sequence of C. /ejtiiirwas complete and as Guillain-Barre syndrome (GBS), for which patients may immediately released into the public domain through require intensive care and take a year to recover. the Sanger Centres website in September 1998.
Current understanding of C. jejuni is poor, despite it The sequencing approach chosen by Dr Parkhill and being twice as frequent as the well-studied Salmonella. Dr Barrell at the Sanger Centre enabled them to make a It remains a mystery why this food-borne pathogen has striking discover)©. Each DNA strand was sequenced seven to become the most frequent cause of gastroenteritis, why eight times to ensure the highest possible accuracy: if one of infection can lead to Guillain-Barre syndrome, and why, the sequences included an error, there were several others to in the developing world, infection has different symptoms: a non-inflammatory watery diarrhoea. What is known to date is that C. jejuni an contaminate all types of meat, mostly of bird species, and that the organism survives in water and milk sources. Now, with the entire DNA sequence of the Campylobacter genome to hand, researchers have an opportunity to understand the organism fully and search for answers. To exploit this invaluable new resource, six UK Campylobacter research groups have formed a consortium - each group bringing different approaches and techniques to the collaboration.
Left: Campylobacter jejuni.
Below: Sequencing the Campylobacter genome was funded through the Trust's Beowulf initiative, conceived to tackle microbial genomes with a major impact on human health CAMPYLOBACTER
compare against and correct the ambiguity. Unexpectedly, of genes, not found in H. pylori, which may help to the repetitive read-outs also revealed 25 small regions of explain the broader range of environments (such as extreme variability - runs of Cs or Gs of differing lengths, for avian and human gastrointestinal tracts, and aqueous insuince 18, 19 or 20 Gs in a row. According to Dr Brendan environments) in which C. jejmii can survive. Wren, of St Bartholomew©s and the Royal London School of Medicine and Dentistry, these ©hotspots© of variation could Similarly, initial computer matching of C. jejuni©s provide the organism with a rapid means o( changing its genome to protein databases has not turned up any surface structure in response to changing environments distinct virulence factors, such as enterotoxins used encountered in the infective process - a survival strategy. bv bacteria to attack their hosts or adhesins used for During replication, the length of these tracts ot DNA may colonization and invasion. Thus C. jejuni genome change; if shorter or longer runs are produced, the encoded sequence has not revealed all its secrets in terms of protein may fall in and out of frame and thus protein survival and virulence, and is probably using unique expression is changed. These minor reversible mutations in strategies to destroy cells, interact with the host and the DNA of C. jeji/ni can create phase and/or antigenic cause diarrhoea. If this is true, potentially unique variants that enable the organism to evade the host. Dr Wren proteins will provide excellent targets for selective is currently investigating these variable regions to determine it therapy. Indeed, ot the 1731 genes predicted for they are responsible for changes in Cainpylobitctefs surface C. jejuni, about 30 per cent are complete mysteries, the structure, resistance to intestinal bile, and motilitv in the host. so-called ORFans, for which there is no known function.
The Sanger Centre
The full sequence of C, jejuni may also shed light on The completion of the genome sequence has already had an the virulence of another pathogen - Helicobacter pylori. impact on specific research projects on Campylobacter. For the organism responsible for most stomach ulcers in example, Dr Julian Ketley from the University of Leicester is humans. These two gastrointestinal pathogens share so using the DNA sequence to study different systems that play many features that, when H. pylori WAS first identified a role in survival in and out of the intestinal environment. 15 years ago, it was initially classified as Campylobacter. Two members of the iron responsive regulatory family were With the full sequence of H. pylori also available, round, with one affecting the expression of a previously Dr Wren has performed ©comparative genomics© between unknown iron transport system and the other regulating the two organisms, the electronic matching of translated stress responses. In another project, the genome sequence gene sequences. By highlighting what is present in one was a great help in identifying the many genes involved in organism and absent in another, or what they have in the production of lipopolysaccharides, speeding up the work common, he hopes to uncover the genes that enable these to characterize the types of these surface molecules in related pathogens to cause distinct disease syndromes. For C. jejuni and the contribution they may make to the example, certain groups of genes important for H. pylori induction of GBS. The G/C hotspots may also have an to survive the harsh acid environment of the stomach are effect on the production of lipopolysaccharides, as several absent in C. jejuni. Conversely, C. jejuni has four groups are present in lipopolysaccharide biosynthesis genes. CAMPYLOBACTER
Beyond the sequence Completing the triangle are peptide ©fingerprinting© studies With the whole bacterial genome complete, every gene using mass spectrometry, as the entire complement of proteins of C. jejuni is now open to scrutiny. Homology studies expressed by a cell, the proteome, can now be investigated. through computer matching, however, can only provide The research teams led by Dr Ketley, Dr Wren and clues - they do not prove function. Fortunately for Dr Charles Perm (University of Birmingham) will use biologists, the explosion in sequencing information proteome analysis to study the regulatory networks that allow has coincided with major biotechnological advances C. jejuni to adapt to different environments during survival. that can help translate computer-based analysis into an understanding of the biology of a pathogen 1 hese powerful new techniques will result in a quantum leap in the understanding of the biology of C. jejuni. This By integrating three different approaches - in what knowledge should aid in intervention strategies to reduce Dr Wren terms the ©magic triangle - a sequenced Ctiiiipy/abiicti©rtrom the food chain, and by highlighting organism can be studied at the functional, potential drug targets or vaccine components, transcriptional and translational levels. equencing the genomes of pathogens is opening Understanding the function of different ass mutageness whole new avenues for treating disease. In the genes is now possible using the large-scale Global deletion long; term, niicrobial scientists also have a
The ©magic triangle© Integrating modern biotechnology to study the gene function of Campylobocter. ^
©Transcriptome Proteome ^Expression profile of Expression profile all transcripts of all proteins
systematic construction of mutants, and each mutant can stake in the Human Genome Project as it will help be individually ©tagged© - allowing the changes in function shed some light on the other side of the coin: the of hundreds of mutants to be followed simultaneously. For host©s susceptibility to bacterial infection. studies at the transcriptional level, Dr Wren, in collaboration with Drs Phillip Butcher and Jo Mangan at St George©s Dr Julian Parkliill and Dr Bart Barrell at the Sanger Hospital, London, Dr Neil Stoker at the London School Centre, Hiiixton, (.iimhridgeshire; Dr Brendan Wren at of Hygiene and Tropical Medicine, and Drs Parkhill and tlie Department of Medical Microbiology*, St Bartholomew©s Barrell, is preparing high-density DNA micro-arrays Hospital, London- and Dr Julian Ketley at the Department containing every one of C. jejuni"s 1731 genes. Using these of Genetics, University of Leicester, are funded hy the Wellcome micro-arrays, Dr Wren hopes to obtain a bird©s-eye view of Trust to investigate thepathophysiology of C. jejuni. The all the genes that are switched on or off in response to website of the c/A"Campylobacter consortium can be found environmental changes and/or at different stages of infection. at www. med m icro. mds.qmw.ac.uk/cam pylobac ter
39 SUSAN GOLOMBOK appy families? Non-traditional families and children's well-bein;
The technology of reproduction is becoming increasingly sophisticated. Couples with fertility problems can turn to sperm, egg or embryo donation, in vitro fertilization or surrogacy, and such techniques are also helping single heterosexual and lesbian women to bear children. But how do children from such backgrounds fare, emotionally and behaviourally, as they grow up? How are they affected by learning about their origins,O or indeed havingO the facts concealed from them, or by living within non-traditional families? These questions are the focus of Professor Susan Golombok©s research at the Family and Child Psychology Research Centre, City University, London. hile government attention puts the Assisting reproduction family firmly back under the spotlight, the ©Test-tube babies© became a household phrase more than Wcircumstances into which children are born 20 years ago. Today, in vitro fertilization (where an externally and brought up become increasingly diverse. Policy-makers fertilized embryo is re-introduced into the mother in the and parents need to know the psychological impact of non- hope of a successful pregnancy) is a common clinical traditional family backgrounds on the children raised technique, and the number of couples seeking treatment for within them. At City University, London, Professor Susan infertility using donated sperm or eggs is growing every year. Golombok and colleagues are exploring these issues. But do these means of creating families affect the development of children, or influence the relationships between the children and parents? In one of the first studies of its kind in the world, Professor Golombok and colleagues are assessing the psychological development of children of almost 500 couples in Italy, Spain, The Netherlands and the UK: those born following /©;/ vitro fertilization, those conceived from donated sperm or eggs, those born to parents with infertility problems but who nevertheless conceived naturally, and families where children were adopted at birth. The study has used interviews and questionnaires with mothers, fathers and teachers to investigate the quality of parenting and
Above: Storing embryos for in vitro fertilization CHILD DEVELOPMENT
Lesbian mothers Research suggests that children in single-parent families do less well psychologically and educationally than those raised in two-parent families. Many would assume that The first phase of the study has looked at the development this shows the value of growing up with a heterosexual of children aged four to eight years. Reassuringly, Professor couple, although children with single parents have often Golombok©s team found that the children appeared to be experienced the break-up of a family, or associated well adjusted emotionally and psychologically, and enjoying difficulties such as poverty, which could be contributing the benefits of a close family relationship. There were no to their problems. But it may be that a second significant differences between the ;;/ vitro fertilization and donor adult is important, regardless of their gender, and Professor insemination families, so at this age neither culture nor the Ciolomboks team is investigating the well-being of children lack of a genetic link between the child and one or both raised by lesbian mothers - whether alone or in a couple. parents appear to affect family relationships adversely. In the UK, fostering and adoption by lesbian women is The next phase of the study - following up the children as they permitted by law although it is often extremely difficult, reach 12 years of age - may provide the most illuminating and lesbian women are also commonly denied access to answers. Adolescence is often a difficult time, with assisted reproduction. Mothers who ©come out© as self-identity and relationships with parents lesbian after heterosexual relationships may becoming important issues. A key question face intense scrutiny and ultimately at this age is whether the parents who be denied custody of their children had used sperm or egg donation will because of their sexuality. Reasons tell the children about their given for this include the background as, perhaps surprisingly, assumption that they will not be most of these parents in the study good parents, the possibility that had not done so - commonly the children will become lesbian fearing that children would be or gay themselves in adulthood distressed by this knowledge, and = (an outcome often considered would feel less love for their ©non- undesirable), or that their children genetic© parent. This contrasts markedly may develop emotional and with adoptive parents, most of whom tell behavioural problems - perhaps as a their children at an early age. result of being ostracized by their peers.
Another method of helping infertile couples In vitro fertilization Yet a significant body of research, A needle (top) injecting the DMA is the use of surrogate mothers. The practice of a sperm into a human egg. including that of Professor Golombok, is still quite rare in the UK, and carefully does not support these assumptions. Her regulated by law, and there is a marked work indicates that children brought up lack of knowledge about how children by lesbian mothers do not have higher feel knowing that their surrogate levels of emotional or behavioural mother has ©given them up© to the problems than other children, or family in which the}© live. Professor atypical gender development Golombok has been part of a (the concept they have of government committee reviewing themselves as male or female). surrogacy law in the UK, and is just beginning a study at the To extend these studies, Professor Family and Child Psychology Golombok is gathering information Research Centre that aims to about children born to lesbian examine the outcomes of surrogacy for mothers, in collaboration with Professor all concerned: the surrogate mother, Jean Golding at the University of Bristol. the parents and the child. The Avon Longitudinal Study of Pregnancy
42 Above and right: Assisted reproduction techniques are enabling lesbian couples to bear children.
and Childhood has extensive information on, and ongoing access to, about 14 000 mothers and children from pregnancy onwards. The mothers and children arc from the general population rather than a self-selected group, and the group includes a number of lesbian mothers who have been raising their children alone, in partnership with another woman from birth, or after separation from the children©s father. Data are being collected from mothers, children at age 7, and their teachers, concerning developmental, behavioural, emotional and academic progress.
The study will compare the children raised by lesbian and lesbian families, and the arrival of sophisticated mothers with those raised by single heterosexual mothers techniques to assist reproduction. Yet Professor Golombok©s and by heterosexual couples. The researchers hope to research shows that these developments do not themselves determine whether maternal sexual orientation affects alter child-parent relationships, and many of the assumptions children©s psychological development, and whether and speculations about the influence of lesbian mothers children are affected by the presence of a second parent - or assisted reproduction on children©s psychological be they male or female. Professor Golombok hopes that development are unfounded. It may boil down to a information on these families will continue to be collected simple generalization, also borne out by Professor in the future, allowing a detailed picture of the effects of Golombok©s research - ©wanted© babies do better lesbian parenting on children at 12 years, and again when than ©unwanted© babies, and enjoy a happy family life. they become adults.
The last generation has seen significant changes to UK society, with an increasing number of single-parent
43
DOUGLAS YOUNG The persistent , I ague
New strategies for tackling tuberculosis
Tuberculosis continues to he identification of the tubercle bacillus plague mankind, seeding by Robert Koch (left) in 1882 was a Ti ddefining point in the nineteenth-century itself within communities and revolution in microbiology that underpinned focusing its deadly attack on dramatic progress in control of infectious diseases in the present century. However, in spite of this individuals whose immunity early success, Mycobacterinm tuberculosis continues is reduced by poverty or by HIV. to kill more people each year than any other single infectious agent, and the World Health Organization Professor Douglas Young and his has declared tuberculosis a global emergency. There is no colleagues at the Imperial College reliable vaccine against tuberculosis and the emergence of Hiltidtug-resistant strains threatens our existing lines of School of Medicine, London, are Using defence. As with many other emerging and re-emerging information r fromr the1 eenome sequence infections, , , there. is an, urgent, .need tor new strategies in L the battle against tuberculosis. of Mycobacterium tuberculosis to assist in understandingi i. thei intimate interactions |ust as.,,,©,- discovery of the microbesL , that cause disease 0 provided the driving force for infection research at the Between the pathogen and itS start of this century, the elucidation of their complete r , , -ill- 1 eenome sequences provides the impetus for renewed mrected host, with the ultimate goal % M . ^ efforts as we enter a new century. A collaborative effort of designing new interventions between scientists at the Institut Pasteur and at the Sanger Centre has solved the complete sequence of to turn back the global spread of AI. tuberculosis. Every piece of information required to tuberculosis in the new millennium. make the tuberculosis bacterium tick is contained within
Left: A cluster of the bacteria Mycobaaenum tuberculosis.
RightrThe recovery of mycobacterial DMA from medieval bones - in this case, a female skeleton from AD1270-1410 - is helping researchers to understand the evolution of the bacterium.
45 The genome of M. tuberculosis H37Rv: Vital statistics • A single circle of 4 411 529 base pairs
• 3924 predicted open reading frames form during the persistent phase of the • A relatively high G+C ratio (65.6 per cent) infection, or is it rather an ongoing battle • Only one rRNA operon (related to slow growth?) 1 in which the rate of bacterial replication is • Potential to synthesize all essential amino i matched by the rate of their killing by the acids, vitamins and cofactors immune system? Using molecular genetic • An extensive range of genes encoding enzymes involved in lipid metabolism tools, ©reporter© strains of mycobacteria have • Over 10 per cent of the genome encodes been constructed that emit light signals, enabling two families of genes (PE and PPE) of investigators to monitor the changing fortunes of unknown function • There are -50 insertion sequences the bacteria as the infection proceeds. Expression of a (including 16 copies of IS6) 10) Huorescent protein from jellyfish allows researchers to track the movement of mycobacteria through infected cells and tissues, while an enzyme derived originally from luminescent
. J*-\_ aquatic bacteria provides information about changes in mycobacterial viability. In each case, the reporter signals .jr can be hooked up to different genes in the mycobacteria, allowing researchers to map out those parts of the genome that play a key role at different stages of the infection. the 4 million base pairs of DNA sequence; the challenge racing researchers is to learn to inrerpret this information One application of the reporter strains is in assessment of and to use it to identify the vulnerable parts of the organism immune status. In collaboration with Professor Mike Levin most suitable for targeting with novel drugs and vaccines. in the Department of Paediatrics at St Mary©s, London, Professor Youngs team are investigating the use of reporter Bacteria are generally designed to take advantage of mycobacteria as living ©thermometers©, adding them to any nutritionally favourable opportunity to reproduce blood samples from different individuals and using the themselves as fast as possible with the aim of enhancing response of the mycobacteria as a gauge of the effectiveness their survival and dissemination. By investing all their of the ensuing immune response. resources in this rush for growth, they can typically double their numbers within 20 minutes. In contrast, M. tuberculosis Changing with the times? divides only once in 24 hours even in the most advantageous A feature of the current epidemiology of tuberculosis in circumstances. Its success as a pathogen derives from an low-incidence countries (such as the UK and the L^SA) is aptitude for patient persistence in infected individuals, the occurrence or ©outbreaks©, in which an initial index case maintaining a low profile without any obvious effect on can spread the disease to multiple contacts in the household health. Estimates based on immunological tests suggest and workplace. Such outbreaks are particularly serious that up to one-third of the worlds population may be when they involve transmission of a strain that has acquired infected in this way. Occasionally, however, the bacteria resistance to the drugs used to treat tuberculosis. In other are stirred into action, resulting in debilitating damage instances, a single isolated case of tuberculosis can occur in to lungs ot 10 million individuals ever)© year and causing the absence ot any further disease in contacts. Differences around 3 million deaths. It is these active cases of in transmissibility of different strains of M. tuberculosis tuberculosis that ensure continued transmission of the may be a contributing factor. Professor Young©s group infection. What triggers this Jekyll and Hyde transformation are investigating whether variations they have observed in from quiescent passenger to lethal aggressor? Is it a change the genetic makeup of different isolates result in differing in the way that the bacteria behave, or is it a change in the biological properties. By studying genetic diversity, they way the infected individual responds to their presence? hope to learn how differenr strains have evolved, and to be able to assess the potential for future evolution and Shedding light on infection selection of strains with enhanced transmission properties. A major goal of the work under way in Professor Young©s laboratory is an attempt to understand the dynamics of One interesting way to look at the evolution of the infectious process from the perspective of the invading M. tuberculosis is to study genetic samples obtained from mycobacterium. Do the bacteria hide awav in some dormant archaeological material. In collaboration with archaeologists;
46 TUBERCULOSIS
from English Heritage, mycobacterial DNA has been Researchers worldwide arc using the M. tuberculosis genome isolated from the bones of tuberculosis patients in medieval information as a blueprint to design novel vaccine- burial sites, for example, allowing a detailed comparison candidates, based either on knocking out genes involved in with present-day isolates. Researchers are hoping to use pathogenesis to generate live attenuated vaccine strains, or such material to investigate historical lines of transmission on identification of genes encoding the key immunological between humans and domesticated animals, helping them determinants of the bacteria which can be used in the form to understand the origins ot human tuberculosis and to ol ©subunit© vaccines. These new candidates are being actively determine whether the disease we experience today differs screened in laboratory models of infection, with the aim of from that of previous centuries. identifying those that perform better than the current poorly effective BCG vaccine. While new vaccines may work in the TB in the next millennium laboratory, there are formidable problems associated with The ultimate goal of the research programme is to translate assessment of their efficacy in humans. The use of reporter fundamental understanding of host pathogen interactions mycobacteria to compare the effectiveness of the immune into a new generation of more effective drugs and vaccines response in control and vaccinated individuals represents one for tuberculosis control. Current drugs are able to kill possible approach to initial clinical testing ot new vaccines. mycobactena actively growing in the diseased lung, but leave a. residual population of persisting bacteria which are In spite of the gains achieved over the last century, more removed only by prolonged treatment. The search is on for people will die of tuberculosis in 1999 than in any other new drugs that target different stages of the disease process; year in history. There is a pressing need to invest additional drugs that inhibit the specific interactions with host cells resources in making the best possible use of the drugs we that underlie the pathogenic process, for example, and have available right now, while at the same time laying the drugs that can directly attack the population of persisting foundation for development of improved tools to combat bacteria. The goal is to reduce the timecourse of the current this scourge in the next millennium. six-month therapy to six weeks or even six days. Ultimately, success in global control of tuberculosis will probably Professor Douglas Noting is in the Department of Infections depend on combination of drug treatment with effective Diseases and Microbiology, Imperial College School ofAtefficine, preventive vaccination. London, and Isolds a Wellcome Trust programme grain.
Two strategies for the production of new tuberculosis vaccines Left: Genes encoding proteins responsible for bacterial virulence can be deleted to generate live attenuated vaccine candidates. Mycobacterium tuberculosis Right: Genes encoding proteins important for recognition by the immune system can be used to make subunit vaccines. vLBERT BEYERS ' PAUL VAN HELDEN i NULDA BEYER5 Upsettin balance Tuberculosis in South Africa
Tuberculosis is very common in the he World Health Organization estimates that two nillion people - approximately one-third of the world©s impoverished communities in the Tpopulation - have been infected with Mycobacterium suburbs of Cape Town. Overcrowding tuberculosis, the bacterium that causes the lung disease tuberculosis. In the majority of individuals, the body©s undoubtedly aids the spread of the immune system halts the infection, but there are still causal bacterium, Mycobacterium about 10 million people with active tuberculosis worldwide, and about 3 million people die from the disease every year. tuberculosis, but a research team F.ven in those who resist the disease, the bacterium often from the University of Stellenbosch, lies dormant in the body.
Tygerberg, has found that the The Western Cape Province of South Africa has one of reactivation of the bacterium, lying the highest incidences of active tuberculosis in the world. For the past five years, a research group from the University dormant in the body after previous of Stellenbosch, Tygerberg - Professor Albert Beyers©s team infection, may also contribute to the of immunologists, Professor Paul van Helden©s team of high incidence of the disease. They molecular epidemiologists, and Dr Nulda Beyers and colleagues from the Department of Paediatrics and are now looking for factors in the Child Health - has been studying the epidemiology of communities that can lower the body©s tuberculosis in two suburbs of Cape Town. Their findings suggest that the high rates of tuberculosis in these immune defences against tuberculosis. npoverished communities are due not only to )vercrowding - helping the infection to spread but Below: Overcrowding and poverty in Ravensmead and Uitsig can contribute to the spread ofTB. Iso to other factors that upset the balance of the mmune system, allowing previous, contained nfections to reactivate. ^•#; Tuberculosis in the Western Cape © f*l( Over the last ten years, one in every three houses in the ©©8JE?r3fc_*?~ rwo suburbs of Ravensmead and Uitsig has had a case ^j.. of tuberculosis. The 34 000 people who live in these Above:A mobile X-ray unit, used for detection ofTB in South Africa. Below:Tuberculosis can strike irrespective of age in deprived communities.
communities are ot mixed racial descent (©Cape Coloured© T helper cells people), and the researchers do not expect there to be The immune response is carefully regulated so that significant genetic variation between individuals in the pathogens can be recognized and eliminated with minimal 39 subdistricts of these two suburbs. There was, however, damage to the host. The first task for the immune system a marked variation in the incidence of tuberculosis in the is to recognize an infection - a role undertaken by T helper subdistricts - the disease being most common in the (Th) cells. When a T cell recognizes a foreign protein and subdistricts with the lowest socioeconomic status and becomes activated, it secretes polypeptides called cytokmes, literacy rates. which regulate the activity of other immune cells. The cytokines produced at the earliest stages of an immune The association of tuberculosis with poverty and response direct the subsequent development of ©naive© T deprivation is well known, and is usually ascribed to helper cells into one ot two different subsets -T helper crowding, assisting the rapid spread ot M tuberculosis cell types 1 and 2 (Thl and Th2). Which particular subset from person to person in airborne droplets (produced develops is strongly dictated by the type of microorganism by coughing and sneezing). But in Ravensmead and invading the host. Uitsig, the most crowded subdistricts were not necessarily those with the highest rates of the disease, and there were Thl and Th2 cells have difterent patterns of cytokine many different strains of M. tuberculosis in the production, with difterent effects on the immune response community. These findings suggest that follows. Th 1 cells, which that a rapid spread of disease is not produce interleukin 2 and interteron the only cause of the high incidence y, activate macrophages (to engulf of tuberculosis, and that the and destroy bacteria), and are thought reactivation of latent infection may to be necessary for the effective also play a significant role. In which responses of cytotoxic I cells, which case, why has the immune system©s destroy cells infected with viruses. previous success in controlling Th2 cells produce interleukins 4, 5, M. tuberculosis become compromised? 10 and 13, activating B lymphocytes Tuberculosis
Above: Parasites and stress may cause a to produce antibodies. Once a Thl or Th2 response has shift from aTM immune response to a been established it tends to be maintained - the cytokines Th2 response, undermining the body's resistance to M. tuberculosis. secreted by Thl cells inhibit Th2 cells and vice versa.
Opposite:A doctor at aTB clinic examining a young patient. The immune system©s Th response is key to its success in resisting an infection. For example, certain strains of mice Below:ATB patient receiving respond to Leishmania (single-celled parasites that cause physiotherapy to loosen phlegn from the lungs. leishmaniasis, diseases of the skin and internal organs) with a Ih 1 response and recover, while other mouse strains that respond with a Th2 response are highly susceptible and die from the disease. Such clear distinctions between Thl and Th2 responses are seldom so obvious in human diseases, although a Th 1 response is associated with the efficient elimination of M. lepme, while a Th2 response is associated with uncontrolled growth of the organism and the eventual development of leprosy. A Thl response is also required for the elimination ot M. tuberculosis: individuals who mount a strong inrerferon y response to the organism contain the infection, while this response is blunted in individuals who progress to active tuberculous diseases.
Parasites and stress What factors in the environment might upset the immune system©s control of M tuberculosis, allowing tuberculosis to develop or a previous, contained infection to reactivate? As almost all school children in deprived communities of the Western Cape are infected with
TUBERCULOSIS
intestinal parasites, particularly roundworm and whipworm, parasites have been shown to induce a shift from Thl to Th2 Professor Beyers and colleagues are investigating whether responses, so this change to the immune system©s response these infections distract the immune system from keeping may be a common mechanism that enhances susceptibility tuberculosis at bay. to tuberculosis in deprived developing world communities. The effects of stress and glucocorticoid levels on immune Intestinal parasites, which are too large to be ingested by responses to M. tuberculosis will be addressed in further macrophages, usually elicit a Th2 response - characterized studies by the research team at the University of Stellenbosch. by Th2 cytokines and high levels of immunoglobulin E. (The immunoglobulin E is thought to coat the parasites, Taken together, the incidence of tuberculosis is highest attracting eosinophils and mast cells - immune cells that in the subdistricts of Ravensmead and Uitsig with the attack parasites by releasing toxic proteins from storage most pronounced poverty, unemployment, illiteracy and granules.) To examine whether there is a connection crowding. These conditions contribute to tuberculosis between intestinal parasites and tuberculosis, Professor not only by crowding and enhanced spread, but also by Beyers©s team tested the levels of immunoglobulin E in reactivation of bacteria lying dormant in the system after the serum of healthy control individuals throughout previous, contained infections. With the emergence of Ravensmead and Uitsig. They found a marked correlation strains of M tuberculosis resistant to many of the available between the immunoglobulin E levels and the incidence antibiotics, these findings strengthen arguments for a of tuberculosis - the highest levels being found in the more active approach to eliminate intestinal parasites in subdistricts where the disease is most common. As Th2 developing world communities. cytokines suppress Thl responses, individuals infested with intestinal parasites might be more likely to develop tuberculosis after infection with AL tuberculosis. Professors Albert D Beyers and Paul van Helden are in Professor Beyers and colleagues also think that chronic the Department of Medical Bwchemistry/MRC Centre stress may be another causal factor in the high incidence for Molecular and Cellular Biology, and Dr Nulda Beyers of tuberculosis in the most deprived subdistricts. Stress is in the Department of Paediatrics and Child Health, increases the levels ol glucocorticosteroid hormones at the University of Stellenbosch, Tygerberg, South Africa. which enhance susceptibility to M. tuberculosis. Professor Beyers held a Wellcome Trust Overseas Senior Interestingly, both glucocordcoids and intestinal Fellowship between 1993 and 1998.
Cross-regulation ofTM and Th2 responses.
IL-2, Destruction Interferon y of bacteria
Destruction of parasites
52 m/^ * id Societv•w'V/VIV-'L-y/
*j •"£ '•* «*•«•'•:*
rec metcme, ciactpoff 6j ^, phy ;|?ff^^A. -,t^ art au(x6ooXiov, congress. 'ttstmiu 01 n JMO 5MII10SON r ^ ROBERT M SNOW MAUREEN I MALOWANY Roll back malaria The history of malaria and its control in twentieth-century East Africa
From the spiralling optimism of the (.its Eighth World Assembly in May 19S5, the World Health Organization (WHO) 1900s when Ross made his path- A adopted a programme for the Global Eradication breaking discovery, to the 1950s with the of Malaria. An ancient disease, which had so eluded all human attempts to interrupt the pathways of transmission, euphoria of DDT, and the late 1990s was to be the target of the first worldwide eradication with the WHO's campaign to Roll Back programme in history. Since the discovery of the transmission of the malaria parasite by the Anoplieles Malaria, the markers for the history of mosquito in 1897 by Sir Ronald Ross, malariologists the disease belie a long struggle to had looked forward with optimism to the removal of this disease through vector control, only to be defeated understand and control malaria. A time and again in their efforts to clear swamps and destroy collaborative project between Dr Mary Anoplieles larvae. The apparent answer to the scientists' dream was, of course, DDT, recognized as a powerful Dobson at Oxford and Dr Robert Snow residual insecticide in 1942. This was a weapon which at Nairobi, Kenya, is looking at the could be directed towards the adult mosquito and, the WHO hoped, eliminate the vector and eradicate malaria. politics and economics of control in East Africa - from the colonial period, Nearly half a century later, the global malaria scenario looks as bleak, if not bleaker, than it did during the heyday through independence in the 1960s, to of malaria eradication. Not only has the mosquito become the present. The project is investigating resistant to insecticides such as DDT, but the parasite has proved to be extremely resilient and adaptable - quickly the local and international debates on becoming resistant to antimalarial drugs such as chloroquine immunity, treatment, endemicity and and presenting few straightforward targets for vaccine development. With as many as 360 million people exposed control, as well as the successes and to the risk of infection from Plasmoeiiuni falciparum, and with someone dying from malaria once every 12 seconds, failures of control strategies of the scientists are once more desperate for a new solution. mosquito vector and the parasite. That solution appears elusive, and yet the WHO has
55 MALARIA IN EAST AFRICA
targeted malaria with the launch of their new campaign One of the issues emerging from the research is the need to 'Roll Back Malaria'. The word 'eradication' i.s no longer to explain why, when the WHO launched its global on the agenda but the WHO aims to reduce mortality by eradication programme in 1955, it explicitly excluded sub- 50 per cent by 2010. How and whether this will be possible Saharan Africa. The peculiarities of this decision are all the is the concern of researchers and scientists using old and more puzzling considering that the Conference on Malaria new strategies, from bed nets to drugs and vaccines. Control in Equatorial Africa, held in Kampala in 1950, had announced the decision to control malaria "...by modern While scientists are developing control strategies for the methods as soon as feasible, whatever the original degree RitLite, historians of medicine are looking back over the of endemicity, and without awaiting the outcome of further century and asking why so little has been achieved in experiments". In just five years, the pendulum had swung reducing the burden of malaria in endemic and epidemic from one of commitment and cautious optimism with situations. In a project that brings together specialists in respect to Africa to one of attenuated delay - as the 1955 the history of medicine and in tropical medicine, Health Assembly's report stated: "The problem of finding Dr Mary Dobson, from the Wellcome Unit for the History an effective and economical method of eradicating malaria of Medicine in Oxford, is collaborating with Dr Robert in tropical Africa has not yet been solved". While the rest Snow, a researcher on the epidemiology of malaria in of the world was caught up in the euphoria of DDT and sub-Saharan Africa in Nairobi, Kenya. Together, they eradication, Africa was left out of the campaign. There was have begun to reconstruct the history of malaria and never a 'failure' of malaria eradication in Africa - it simply its control in twentieth-centurv East Africa. never got off the ground.
Malaria in sub-Saharan Africa Unpublished documents tor East Africa reveal behind- Africa claims the ancient birthplace of malaria and today the-scenes conversations, negotiations and debates carries the burden of 90 per cent of the world's malaria cases. between leading malariologists of the 1950s. Whatever Yet, from the historical perspective, sub-Saharan Africa is one the published decisions, there has never been a clear of the least studied areas of the world. In this new project, consensus on how best to address the challenge of Dr Maureen Malowany, a medical historian of East Africa, malaria in Africa. "Don't rush at Africa. Take it slow and research assistants and graduate students in Nairobi and and easy , were the recorded private conversations of Oxford have been delving into the archives of East Africa, participants at Kampala, while publicly supporting WHO and the UK, including the wealth of historical the 1950 Kampala decision to "Go ahead with malaria material at the Wellcome Trust. Oral history research is control in Africa whatever". "Time is of the essence", documenting the lives, experiences and research activities of announced the Director-General, when, recognizing scientists, malariologists and entomologists who have worked that mosquitoes were already becoming resistant to in the field and laboratories. Important, too, are the oral his DD f, he launched the Global Eradication Campaign tories taken from local populations who have been recipients in 1955: "There is therefore today no other logical and participants in attempts to control malaria in East Africa. choice". Without a backward glance at the continent Films and unpublished materials are being collared and that bore the greatest burden, worldwide eradication collected as a repository in Oxford to share with others who commenced. In the opinion of international experts, will be inspired to extend and expand upon this research. Africa was not ready.
56 MALARIA IN EAST AFRICA
Immunity, epidemics and drug resistance of malaria? To address these questions of the history and A persistent, and as yet unsolved, controversy which predictability of malaria cases, Drs Dobson and Snow are this project has documented has been the dilemma of searching back in the records for a series of data on interrupting naturally acquired immunity through the climate, particularly rainfall and temperature, and plotting application of control measures. For a number of leading them alongside malaria epidemics. They also hope to shed malariologists throughout this century, it has been not so light on the complexities of malaria in relation to poverty much a question of how to control malaria in Africa, it has and nutrition, and rhe shifts in approaches to control been a question of whether to do so. In the 1900s, leading where these are linked to political upheavals and malariologists, Christophers and Stephens, believed that economic difficulties. African populations endured malaria without ill effects, concluding that "[t]o stamp out native malaria is at Another area of major concern today is drug resistance. present chimerical", while recommending the segregation From the 1940s, when chlorinated salt programmes began of Europeans for their protection from the local reservoir in East Africa, through the uncontrolled administration of of infection. In the 1930s, S P James, at the League of antimalanal drugs, many of which, particularly Nations Conference, authored the report that stated: "it chloroquine, were sold over the counter, growing resistance would be extremely unwise, in certain malarious countries to all antimalarials is now a worrying reality. Alongside the (Dark Africa, for example) to intervene radically in the prolific use and widespread distribution of Western natural process, that to which the natives are immunised antimalarials, herbal and other remedies have been used by against the disease". Such cautions were repeated in the local communities. Uncovering the historical layers of the
1950 Kampala debate by Bagster Wilson, Garnham and production, distribution, use and efficacy of synthetic and Swellengrebel: "it would be unwise, in regions of natural antimalarials is an essential element of the project. hyperendemicity in tropical Africa or elsewhere, to embark lightly upon unrestricted measures of control". In the Today Africa is not left out of the campaign against 1990s, with international agencies promoting impregnated malaria. Rather, Africa and Africans are driving it forward, bed nets, such concerns are once more being voiced: involved in all aspects of research and policy. Revisiting of interrupting naturally acquired immunity in the absence of old data and old debates will bring a historical a long-term sustainable control strategy may lead to the risk understanding of what has gone before, informing the of delayed mortality - a phenomenon being labelled current and future issues of malaria control. 'bounce back malaria.
In early 1998, the damaging intensity of the El Nino rains precipitated a massive epidemic of malaria in north-eastern Dr Mary Dobsoii and Dr Maureen Malowany are at Kenya, claiming hundreds of lives a day at its peak. the Wellcome Unit for the History of Medicine in Oxford. Epidemic malaria has grasped the attention of leading Dr Robert Snow is a Wellcome Trust Senior Research Fellow scientists, but how have malariologists defined epidemics in at the Wellcome Trust Collaborative Programme!KEMRl the past? What are the links between epidemic malaria and in Nairobi, Kenya. Their research is funded by a Wellcome shifts in meteorological conditions and human experience Trust History of Medicine project grant.
57 MIKE BARFOOT I CHRIS LAWRENCE j STEVE STURDY Trojan
Above: Outside the biochemical laboratory. norse The Biochemical Laboratory of the Royal Infirmary of Edinburgh 1921-1939
The biochemical laboratory of the he history of the biochemical laboratory1 of the Royal T;nfirmary of Edinburgh (opposite page) 1921-1939 may Royal Infirmary of Edinburgh I soundS( like an obscure subject and of academic or antiquarian revolutionized medical education in interest only. In fact, the study of this institution promises to shed light on the structure of modern medical education. the UK and throughout the British The biochemical laboratory was the Trojan horse through which Empire. The driving force behind thc Rockefeller Foundatlon of New York funnelled mone>' to bring American academic medicine to Edinburgh. In doing this quiet revolution Was the this, because of the huge numbers of graduates Edinburgh RockefellerT-) i f 11 roundationT- j andi its• turned. out,r reformers,. . , expressed, their, ndesire . . , to„ transform. the practice or medicine throughout the British empire. skilled negotiator Richard Pearce, • i i i r -i 1-1 Before World War I, only Germany had a medical who rpersuaded the ocottisn medical education, system on a thoroughly.' , , 'academic . . rooting.c . establishment tO accept the need for There, professional scientists taught the preclinical subjects /- II ...... or anatomy and physiology while, on the wards, full-time rull-time chairs in clinical academic university professorsf ' with• , access to ,beds , and, laboratory, , medicine. Dr Chris Lawrence of the ^cilities taught the clinical specialities. Meanwhile, in the UK and USA, honorary part-time consultants in hospitals Wellcome Institute Academic Unit, cook nmc from their private practlce to teach studcnts> DrS Mike BarfoOt and Steve Sturdy °ften in schools with no university affiliation. The great exception to this generalization was the Johns Hopkins of the University of Edinburgh, and Medical School and its hospital in Baltimore. Hopkins research assistant Helen Coyle are vv'ls modcllcd on German lines and was the source of admiration tor medical reformers on both sides of the reconstructing the Story. Atlantic - including those in the Rockefeller Foundation.
58
EDINBURGH
The beginnings of the theories and techniques- measurement Biochemical Laboratory of basal metabolic rate, of blood gases, The laboratory was a joint endeavour and of acid-base balance - to the between the Infirmary and the University. elucidation of conditions such as nephritis, It was first set up in 1921 under the thyroid disorders and respiratory problems. direction of Jonathan Meakins, the In effect, the laboratory served not so much University's Christison Professor of as a means of promoting collaboration Therapeutics. Meakins was trained in berween clinicians and academics, bur clinical science and was an admirer of rather as a site at which academic scientists American full-time professorial units. could gain access to clinical material tor Such units were just being introduced the pursuit of their own relatively abstract into Britain at this time, but were far from research programmes. popular among consultants - most of whom valued private practice and some of whom Enter the Rockefeller resented what they perceived as the claims American industrialists of the turn of of laboratory science over the clinical art. the century, such as John D. Rockefeller, The units were not in favour with the majority of the Andrew Carnegie (a Scottish emigrant) and Johns Hopkins Edinburgh medical faculty - who preferred the time- himself made fortunes out of oil, steel and the railroads. honoured, part-time teaching system. It was Meakins who Many of them saw the means to producing a more efficient, was chiefly responsible for prevailing upon the University well-ordered and healthy industrial society in the funding of and the Infirmary to build the laboratory in an old isolation higher education. After World War I, the Rockefeller ward in the grounds of the hospital. It was to have a dual Foundation, which had a serious interest in medical function: conducting routine work for the clinical staff of" the education, began targeting a number of British medical Infirmary, and providing Meakins and his assistants schools as potential channels for effecting wider reform. with the facilities for clinical research. In February 1923, Richard Pearce, the Foundations The history of the routine work of the laboratory - which Director of Medical Education, arrived in Edinburgh for is fully recorded - is a story in its own right. By the early a week of talks with local medical teachers and University twentieth century, biochemical urine analysis was a regular officials — who, of course, had their own ideas about how feature of clinical practice, but before about 1920 testing Rockefeller money might help medical education in the city. for chemicals in the blood was scarcely recognized. Tests Pearce was frank about the Foundation's concerns. It would were time-consuming and required special apparatus. not assist any project that gave anybody except the During the 1920s, Meakins and his successor gradually University the control of research. Pearce was particularly made the lab indispensable in the management of various impressed with Meakins, and wrote back glowingly of conditions. The introduction of insulin in 1923 particularly him to the New York office. helped this move, as blood testing for sugar was presented as essential to sound practice. In this way, Edinburgh Pearce decided that if the Foundation were to influence clinicians were gradually educated into the procedures clinical education in Edinburgh, it would be by advancing and practices of academic medicine. Meakins's programme and prospects. As well as hatching a plan to expand Meakins's laboratory and supplement his Under Meakms's direction too, the laboratory quickly salary so that he could work full-time, Pearce hoped that developed into a site for clinical research of a distinctly Meakins would eventually be selected to fill the chair of academic kind. With grants from the Medical Research medicine, due to fall vacant in two or three years' time. Council, full-time research fellows conducted research that was relatively remote from the immediate practical Pearce realized that he was taking a gamble. A number of concerns of the Infirmary clinicians, and was not of a kind North American universities were already eyeing Meakins that those clinicians would themselves have had the time as a possible leader for their own medical reforms. Equally, or the skills to pursue. Meakins and his collaborators there was no guarantee that the Edinburgh medical men concentrated chiefly on the application of physiological would countenance his promotion from the chair of
60 EDINBURGH
therapeutics to that of medicine proper. Pearce proposed therapeutics, but they also agreed to the creation of a to support Meakins on annual grants so he could develop full-time chair in surgery. Pearce got exactly what he a 'true university clinic' on a whole-time scale. wanted, and did so with remarkably little ruffling of feather
Pearce did not reveal these calculations to the Edinburgh Rather more heat would be generated within Edinburgh Faculty members, but he did indicate the possibility of itself, as differences flared up between the University and Rockefeller support if they built up professorial teaching, the Infirmary over the site of the clinical laboratory, and eliminated non-university teachers and created more over the terms and conditions of the full-time surgery chair. laboratory facilities. There followed seven months of But Pearce maintained a position of calm detachment, negotiations between Pearce and the Faculty over just occasionally nudging the protagonists in the directions what kind ol proposals the Rockefeller Foundation he desired, but leaving the in-fighting to those on the spot. would be prepared to support. Whether the majority of those involved even realized the extent of his influence is unclear. When the new clinical During these exchanges, as they are recorded in the laboratory duly opened in 1927, and the Principal of the archives of the University and the Foundation, Pearce University', Sir Alfred Ewing, wrote to Pearce to thank him displayed a formidable talent for steering others towards tor the Foundation's support, Pearce smoothly replied to his own desired goals. He played an astute political game: the effect that it was the Faculty's idea all along. marginalizing those who seemed most set on other schemes, choosing to communicate officially with the Faculty through Nothing could have been further from the truth. At the those most sympathetic to his ideals of academic medicine, beginning of 1923, the Medical Faculty' was enthusiastically and privately getting Meakins to draw up plans and costings committed to a programme of scientific development that for a new clinical laboratory and a full-time chair. was peculiarly Scottish and was intended to obviate the threat of purely academic clinical teaching. By the end of Coming to fruition the year, Pearce had swung the Faculty- round to support By the autumn of 1923, the Edinburgh plans had been precisely what they had originally opposed: full-time chairs. focused on the establishment of a new clinical laboratory Faced with Rockefeller money, and the consummate for Meakins, and the creation of a full-time chair in managerial skills of the Rockefeller officers, Scottish therapeutics. A Faculty meeting was called for Friday medical politicians had found themselves out-classed and 5 October, when these plans would be considered for out-manoeuvred. For the time being at least, the greatest formal approval or rejection. Pearce arrived in the city' on medical school in the British Empire had tied itself to the Monday for 3 final intense round of talks and meetings, the leash of Rockefeller internationalism. first with Meakins and then with those members of the Faculty who were less likely to support his plans. Once again, he deployed his political skills to good effect — not Dr Chris Lawrence is m the Academic Unit of the only did the Faculty unanimously approve the proposals Wellcome Institute for the History ofMedicine, for a new clinical laboratory and a full-time chair of London, and holds a Wellcome Trust History of Medicine project yriint. Dr Mike Barfoot and Dr Stei>e Sturdy are at Below: With Rockefeller funding in 1923 the Biochemical Laboratory the University of Edinburgh. The research in Edinburgh was was expanded and came to be known as the New Clinical Laboratory, which opened at the Infirmary in 1928. also supported by a Rockefeller Research Center Travel Grant. 9JT01J9cbj 9l[J 0} ABjd AV9U B ppB pUB ©SJOOlpS SB JJ9A\ SB S9JJB9lp UT
SABjd Sip J SJnOJ JBUOTJBU XTS JQJ ^Bd ||TAV ©X§O|OUl{D9JL pUB 33U9p§ JO
jnoijSnoiip SJOOIJDS oj - S9nssi |BDip9iu jnoqB 9jBqgp 9JBJ9U9S puB UIJOJUT
OJ SUITB IJ3IIJAV JO IJ3B9 - sXBjd 99Jl[J U95JBJ SBl| 9UJUJBjSojd UOlJB3Hp9
9ApBAOUUI UB S9JTnb9J UOTJ39|9S OA\jqUI9 pUB UOIJBJUBjdsUBJJ UBUJtiq-OJ -|BUiiuB SB ipns saidoj inoqB uoissnasip UT 9§B§U9 01 sjugpnjs §ui§BJtio3U9 'uinjnDiJjriD |OOIJDS pgpBopgAO XpB9J|B UB UT 3DB|d nojAt|o on ifjj^ •uoijBjuE|dsuBjj UEiunq
MTIOJ pUOIJEU 5J33AV- % \ -OJ-pUIIUB JO S3T1SSI 3IJJ UO S3JJU3D ©UOjdfl XpnJ" Xq U3JJUA1 v Xq paA\o|joj — /66I UF H^jncluTP3 u? Xauspissj puE saiijjsoig uo jiauno^ ppiyn^ sip Xq psuoissimuroa
5J33M-OAU B I3AO 3J3IUJ3jd SJl p^Elf ^V^JKQ JO JtlOJ JSjy ©y/ppif\[ ytft ttt Sij ajjqAv 'ApAijasdsaj 'ssaujj; pjuaui pire sijj 'XjjEjiuiig 'uoisiAspj joj psjdEpE uasq SEIJ puE S3ij3U3§ sssjppE uiMppg Ejoaif^j Xq payyv^ pire ifif-) acjj^
'ssDusiptiB jno-jps oj aSuuj pjAijs3,j qSinquipjj sip IE 3UIOD OJ SJB3X 3qj UI l[J|E3H JHO UBqj 3JOUI J33JJB X^UJ
S33U3I3S 3JIJ 31JJ UI IpJE3S3J A\OIJ JHOqB UOISSHDSIp 3JEJ3U3§ sjooips Suunoj SB [pM SB pu« pUB 3JBDnp3 ©UIBJJ3JU3 OJ U3JJIJM U33q §UIAEq XB|d q3E3
©5[fl 3MJ P3JnoJ 3AE1J sXBjd 33JIJJL "3AIJEIJIUI XjSpOJ UI 'uBsijjBd-uou i|3ns JQJ punuiap aupipsj^ sji i{2noiip Xpusasj jsoui 'suiuiEjSojd uoijBanps
-Ul-3«E3lp E unj SEIJ JSnjJ^ SUIODJpAJ; 3qj ©^661 33UJ§
ACS JI31JJ 3ABIJ 01 UI3I|1
§UIAVO[|E pUB M.OIDJ OJ }UBM XsiJJ JBtJM JHO pug OJ 3|dO3d Sj33UOO 3lJIJU3pS 3qj I|JIA\ JUSpgUOD SS3|
SunoX aip 3u||qBU3 — JEUIJOJ sjcqsp jo doqs^jOM B ui U3JJO 3JB S3I1SSI JBI3OS I3AOD SE3JB JOsfqnS 3SOqA\ SJ31JDE3J
3DUBUIJO.JJ3d 31JJ J3JJE S3HSSI 31JJ SSHSSIp OJ SJOJDB 3tjJ JO_J SI SSOqj 3|ll{M ©SUOSS3J (EUOIJU3AU03 q8uOJqj SUJ3DU03 pJ3iql3
'auiuiEjSojd snjj ui psjaSjE) sjuapnjs pjo-jBsX-gj— ^| IJJIM 8uiJE3p U3l|A\ XsB3Un p3J SJ3lpB3J 3DU3pS XuEJAJ ©OAAJ
3ijj qjiM pasn '3|Xjs uoijEonp3-u;-3jj«3i|j s^uunoj^ f^ JO 3pE3Sp JX3U 31JJ UI S3AIJ JHO 8uiJ33JJE 3q ||IA\ UIOOJSSEp jo 5JJEUIJJEIJ y -apBaap B joj ssuiuiEjSojd puoijEDtips 3ip ui jqSriBj 3DU31DS 3ijj Avoq ssnDSip oj judsajd JE sjqEun pssBq-sanssi §uijB|niuijs pue pui8;jo SuipiAOjd 3JE Xsqj jEqj jruipE sjooqas jsoiu 'JSJJEUI usaq SEIJ ipiiJA\ - XuBdmoD 3ijB3i|j |Buoissajojd sy^jJ^A jasfqns A\au sanpojjui oj sdoas psjiiuij puE / \ / \ lunpaujnD aqj dopAsp oj suiij 3|Hi| qij/
•|Ejaua3 ui ssau||i jEiuaai jo EuiSijs au,i sa3u3||Eip puE 'js8ue agEuaai q Xq pajnquiic si qj|M UO{Sn/UO3 Slj pUE UO|SS3jd3p }U3DS3|OpE )O 553USS3|d|3L| 3L{1 sajnjdED pa>/3Djp -spaau ai|s d|aq sip Suiuieiqo uioj^ juq^ s:u3A9jd }Ei|) ELuSns 3qi spnj jaqjjnj puE uojssajdap p sjnoq UMO S|q ssn3S|p 01 sssnpj J3qac( paqjosqE-jias Jan -JEIS >|3OJ SuiuijEq-^as e Pig in the Middle - animal-to-human transplantation Set in the near future, Pig in the Middle begins with Ryan and his the operation on ideological grounds and unconvinced that the girlfriend Gemma undergoing renal dialysis at their local hospital.When Ryan is offered the opportunity to take part in clinical trials to receive viruses capable of infecting humans. Pig in the Middle encourage a new kidney, he is overjoyed — that is, until he informs militant vegan students to reflect about how it might feel to consider risk and Gemma that it is a pig's kidney on offer. Gemma is opposed to ethics in forming decisions about their own lives.
Creating new debates January 1999 saw the start of Creating the Debate Theatre-in-education programmes undoubtedly provoke for the New Millennium, a three-year programme interest and stimulate discussion. The impact is perhaps taking the three plays to a wider audience and adding best expressed by a student's comments shortly after a yet-to-be- commissioned fourth play to the repertoire. seeing The Gift. "...I would find it hard to alter the genes The £600 000 award, funded jointly by the Office of my future child, as I am not convinced that I have the of Science and Technology and the Wellcome Trust, is right to choose for them...Some people are not very open paying for six national tours of the plays, taking the minded - It would be nice to have children who weren't successful national school-based format of the disabled, but I don't know if it's up to me to choose. We productions and extending it to theatre venues. An don't get many opportunities like this to find out about extensive independent evaluation of the project has been issues which may concern us in later life." commissioned, aiming to provide information about the effectiveness of the programme, identify longer-term Peter Finegold is Project Manager for Education in changes in attitude, and explore ways in which the scheme the Wellcome Trust©s Medicine in Society Programme. can become self-sustaining after funding ceases in 2002. The Gift video is to be broadcast on the BBC Learning Zone on 28 October 1999. As the pace of discovery accelerates, educational initiatives will become V> increasingly important; raising >&. awareness amongst those who will ^s The Gift - genetics and embryo selection The Gift guides the audience through the emotions be most affected by revolutions in ^ and thought processes of a family whose life is turned biomedical science. The Medicine in Society upside-down by the appearance of a rare genetic Programme aims to work with students and disorder, Friedreich's ataxia, in 17-year-old Annie Kay. Annie inherits a defective gene from each of her carrier adults to facilitate debate about scientific issues i parents, and her health progresses along the predictable amongst the public, scientists and policy- ' path for this condition: slurred speech,'wonky legs that won't work' through paralysis and eventually death. makers. The five-year, £15 million initiative Annie's carrier brother, Ryan, is spurred on to become supports innovative research and activities within a geneticist.Years later, when Ryan's wife Jennifer finds education, media and public consultation. The out that she too is a carrier for the condition, Ryan selects an embryo without the faulty gene for programme also sets out to embrace the need for a implantation. His decision not only to select out the strong intellectual community of bioethicists in the rogue gene, but also to choose a male baby, likely to develop athletic prowess, takes the post-performance UK, whilst supporting research on the public policy discussion between the characters and the audience implications of biomedical advance. into the ethics of selecting a perfect baby. Science Editor: Dr Giles Newton ACKNOWLEDGEMENTS We are gratelui to everyone who agreed to be reviewed in this issue, the scientific referees who commented on early drafts, Assistant Editor: Lucy Moore everyone who supplied pictures or gave us permission for their pictures to be used, and the many members of Wellcome Trust Design and art direction: Pnt Parmar staff who he ped produce this yo ; ume Picture Research: Anne Marie Margetson
Photographic Library, except as follows: IFC jnd page 9. Illustration: Chnstos Magganos. Private View vaccination. IFC and page 14, blood tubes, page 16, taking blood samp'e.pjge -!Q •^cb.k"rB unit, page 50, physiotherapy, pages 1 Additional writing: Lisa Melton, Sophie Zeman .-,--,- ' -ores); page 9, child on crutches n -e. page 13. distribution of APs Printed by: Empress Litho L'mited 'li ...... _.:.•_ '_.-_.,- films,page 17. DWeatherall ana child. Si i Lani an rjjra (DWeatherall); pages 1,15,16, gymnasts Produced by: The We'lcome Trust Publishing Department (Action-Plus), page 16. bone sections (L Lanyon): pages 2 and 22. chick hindbram segmentation, page 3, motor neurons (A Lumsden); Design Manager: Michael Wilcox page 22. Xenopus retina, page 26, po Comments on The Wellcome Trust Revit are welcomed and should be sent to: Publishing Manager Publishing Department The Wellcome Trust 210Euston Road London NW1 2BE The We/'come Trus' Re«ew 15 distributed via a mailing list held in the Marketing Department of the Wellcome Trust. If you would like to be added to this list, or if you have a colleague who would like to receive The We/tome Trust Review, please contact Lucy Evans at the address below The Wellcome Trust is a registered charity, no 210183 Trustee: The Wellcome Trust Lmtec Registered in England, nc. 2711000 Registered office: 183 Euston Road. London NW1 2BE First published by the Wellcome Trust. 1999 ©The Trustee of the Wellcome Trust. London. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any shape or foTn by any means electronic, mechanical photocopying, recording or otherwise without the prior permission of the Wellcome Trust Tel: +44 (0)171 611 8888 Fax: +44 (0)171 611 8545 E-mail (Marketing): [email protected] E-mail (General information): irfoserv@wellcome i Web: www.wellcome.ac uk I i