Mcgill-Trained Md, Experiment Give June 20 Shuttle Flight Strong Canadlin Flavour

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MCGILL-TRAINED MD, EXPERIMENT GIVE JUNE 20 SHUTTLE FLIGHT STRONG CANADLIN FLAVOUR

Robert Thirsk, MD, CM, PEng

ences experiments will probe

.1 W.111WE"MIffil.., k...... :,t,:,2,:,.,:,.,:",.,.,:,:,.".",.:,. %'. .h changes in plants, animals and humans under spaceflight conditions. The materials-science investigations will examine protein crystallization, fluid physics and high-temperature solidification of multiphase materials in a microgravity environment. (Mi- crogravity describes experimental conditions in the shuttle, which are not perfectly weightless. As the shuttle orbits Earth, it is subjected to small decelerations from atmospheric drag. Other factors, such as the loca- tion of experiments relative to the shuttle's centre of gravity and vibra- tions from spacecraft machinery in- duce small accelerations on the order of one millionth the force of Earth's gravity, or one microgravity.) The US National Aeronautics and the Queen Elizabeth Hospital in Our initial training took place in Space Administration (NASA) is Montreal. A year later, as backup as- the investigators' laboratories and at completing final preparations for the tronaut for shuttle mission 41 -G, I NASA centres, where we were in- Life and Microgravity Spacelab got a taste of what it would be like to structed in the theory, hardware and (LMS) mission. Also known as STS- participate in a space mission. How- operations involved in the experi- 78, this space shuttle flight is sched- ever, training is not the same as ac- ments. Training for the flight took uled to lift off from the Kennedy tual flying. I am delighted and feel place at the Marshall (Alabama) and Space Center in Florida June 20. Last very fortunate to be chosen for a Johnson (Texas) space centres, where year I had the good fortune to be mission that seems uniquely de- in-flight operations involving ground chosen to fly as a payload specialist signed for my interests and abilities. controllers were realistically simu- -a highlight of my career with the My six LMS crewmates, our two lated in high-fidelity spacecraft train- Canadian Space Agency and the ful- backups and I represent five interna- ers. Everyone involved in the mission filment of a personal dream. tional space agencies - NASA and - scientists, ground controllers, as- This dream began in 1983 when I the French, European, Italian and tronauts - participated in several was named one of the original mem- Canadian agencies. We have been multiday simulations to rehearse bers of the Canadian Astronaut Pro- training for the last 15 months to planned operations, communication gram. At the time I was a second- prepare for 16 days in space aboard procedures and problem-solving year resident in family medicine at the space shuttle Columbia. On behalf techniques. Thorough training is es- of scientists from the US, Europe and sential, because in human space Family physician Robert Thirsk is an astronaut with the Cana- dian Space Agency. Canada, we will perform 43 investi- flight we have only one in-orbit gations devoted to the study of life chance to perform the experiments 0 1996 Canadian Space Agency and materials sciences. The life-sci- properly.

1884 CAN MED ASSOC J * 15 JUIN 1996; 154 (12) Due to my clinical background I sions have been rare occurrences on and biochemical changes in every or- have also trained as one of the desig- other spacecraft and have had a seri- gan system. My crewmates and I will nated crew medical officers, and will ous impact on mission objectives. be both onboard researchers and diagnose and treat any in-flight med- A well-stocked medical kit will al- subjects for several experiments in- ical problems in consultation with low me to deliver ambulatory care, vestigating these changes. Most LMS the flight surgeon on the ground. first aid and basic life support. It con- scientific investigations will be con- Fortunately, significant illness and tains oral, topical and injectable ducted in the Spacelab laboratory. injury have been uncommon on drugs, intravenous fluids, bandages This cylindrical pressurized module shuttle flights. Rigorous medical and the equipment and supplies in the cargo bay provides a shirt- screening of candidates ensures that needed to treat routine medical and sleeve working environment that in- astronauts are in good health. Fur- dental problems. A contaminant cludes work stations, experiment fa- thermore, a 7-day quarantine period clean-up kit contains equipment to cilities, freezers, storage compart- prior to launch minimizes crew expo- protect crew members from toxic ments and other support equipment. sure to infectious diseases, and the substances and a pair of eye goggles I have an interest in all these experi- relatively short duration of shuttle that can be used to flush contami- ments and feel I am part of the pio- missions - it ranges from 7 to 16 nants from the eyes. neering effort to understand mecha- days - reduces the probability of in- I am eagerly anticipating the nisms behind the adaptive changes. I flight illness. bone-rattling launch, the tranquillity will outline a few of these LMS ex- Minor illnesses such as space mo- of weightlessness and gazing in awe periments. tion sickness, nasal congestion, at vast regions of our planet. I am headache and backache are com- equally excited by the broad range of TORSO-ROTATION mon. More serious problems, such as human physiological investigations EXPERIMENT renal colic, chronic prostatitis, pneu- we will conduct, which will occupy monitis, cardiac arrhythmias, decom- most of our work time. Spaceflight The torso-rotation experiment pression sickness and corneal abra- results in significant physiological (TRE) is the only one from Canada; Dr. Douglas Watt of McCill Univer- NAS4 photos sity's Aerospace Medical Research Unit is the principal investigator. The idea was hatched several years ago when one of Watt's colleagues suffered an injury that required him to wear a rigid neck brace. He began to feel nauseated after several min- utes moving about his laboratory with his head braced to his torso. Voluntarily fixing the head to the torso, as with a neck brace, has been termed "torso rotation," since the upper body must move to turn the head. On the ground this gradually leads to motion sickness in most subjects. Torso rotation is an example of a deliberate "egocentric" motor strategy, in which the subject concen- trates on a body frame of reference rather than an external world reference. A motor strategy similar to torso rotation is often inadvertently adopted by astronauts during the early days of a space mission. While this may be a means of reducing head movement to combat motion sickness, it might actually exacerbate Dr. Robert Thirsk: the fulfilment of a personal dream the symptoms.

CAN MED ASSOC J * JUNE 15, 1996; 154 (12) 1885 Watt's aim is to monitor our eye, train future astronauts to avoid such the weightless environment. The head and torso movements for evi- movements or to pre-adapt them by LMS work is actually an aggressive dence of egocentric motor strategies mimicking the provocative move- and coordinated effort involving six as we perform typical in-orbit activi- ments under controlled conditions. research teams from the US and Eu- ties. Eye movements will be mea- rope. They will investigate both sured with electro-oculogram (EOG) SKELETAL-MUSCLE flexor and extensor muscle groups electrodes, and head and torso EXPERIMENTS acting at the ankle, knee, wrist and movements with angular velocity elbow. They will provide a detailed transducer units securely mounted on Previous missions have shown analysis of the relative importance of the top of the head and upper back. that microgravity produces signifi- weightlessness-induced changes in Each of us will perform the TRE cant skeletal muscle wasting, particu- motor perception, recruitment and three times during the mission - a larly in the postural muscles. The ex- hormonal and cellular factors in me- few hours after launch, halfway tent and responsible mechanisms are diating the reduced performance of through the mission and near the only partially understood, and this is these limb muscle groups. end of the flight. a medical concern during extended A sophisticated torque-velocity The data will be analysed for evi- stays aboard space stations or for fu- dynamometer facility has been de- dence of unusual gaze control during ture missions to the inner planets. veloped to support the in-flight in- coordinated eye-head movements. Crews returning from long missions vestigations. It measures the torque As well, head rotation will be com- likely will show decreased muscle and the angular velocity produced pared with torso rotation to assess strength and endurance, which will during predefined types of contrac- our overall motor strategy and how it pose health and safety concerns. tions of the flexor and extensor mus- might change during the mission. If This will be the first space mission cles of the elbow and the ankle. motor activities similar to torso rota- to investigate comprehensively the These two measurements enable in- tion contribute to motion sickness in changes in human skeletal muscle vestigators to quantitate several mus- space, it would be relatively easy to structure and function induced by cle-performance and function properties. We will test the hypothesis that the primary factors reducing limb- muscle function can be attributed to alterations at the cellular level, specifically a selective loss in the contractile proteins. We expect that space flight will result in increased muscle fatigability due to preferential atrophy of slow-twitch muscle fibres, coupled with a percentage increase in the more fatigable fast-twitch fibres and an inhibition in the ability of muscle cells to metabolize fats. Furthermore, a greater atrophy of predominantly slow-twitch muscles such as the soleus compared with fast muscles such as the gastrocnemius may be detected by changes in muscle volume when postflight magnetic resonance images of our muscles are compared with preflight images. Data from earlier spaceflights sug- gest that the decrease in limb-muscle strength is out of proportion to the corresponding degree of muscle atrophy, so other mechanisms also may play a role. We will examine the pos- sibility that at least a portion of the

1886 CAN MED ASSOC J * 15 JUIN 1996; 154 (12) decline in muscular strength is Because of the electromyograph ness on muscle function and to pro- caused by alterations in motoneuron (EMG) and percutaneous-stimulation vide useful recommendations to im- function or motor-fibre recruitment. electrodes that we will be wearing prove both rehabilitation programs Muscle biopsy samples will be ob- and the number of blood and tissue in clinical situations where muscu- tained from the gastrocnemius and samples that will be taken to support loskeletal unloading is a component soleus muscle of each participating the muscle physiology investigation, and countermeasures for preventing crew member. The mechanical, mor- we lightheartedly refer to ourselves spaceflight deconditioning. phologic and metabolic properties of as the "rat crew" (as in laboratory the muscle fibres that are biopsied rats)! However, the LMS investiga- PULMONARY FUNCTION postflight will be compared with tors hope to gain a deeper under- those obtained preflight. standing of the effect of weightless- Our lungs are also sensitive to gravity. The mass of lung parenchyma, airways, chest wall and diaphragm causes them to deform under their own weight. As well, hy- drostatic gradients within the body influence intrathoracic blood volume, the distribution of pulmonary blood flow and the return of blood to the right side of the heart. During the LMS mission we will perform a series of noninvasive pulmonary- function tests to gain understanding of the intrinsic behaviour of the lung in a unique laboratory setting unaf- fected by the force of gravity. We will utilize a computerized pulmonary-function-testing system built around three inspiration and ex- halation bags, a variety of test gases, flow and volume measurement systems and a respiratory mass spec- trometer. Specific tests designed at the University of California at San Diego will evaluate resting gas ex- change, distribution of ventilation and perfusion, diffusing capacity, lung volumes and fluid content, cardiac output, mechanisms of gas mix- ing in the lungs, ventilatory control mechanisms and respiratory mechan- ics. Little is known about the car- diopulmonary system's response to heavy exercise in microgravity. Such knowledge is important when astronauts work hard during space walks and while performing other duties during extended tours in space. For this reason we will perform the pulmonary-function tests ._. '. ' , ...... ,_ _as ~~~~~~...... Medical experiments are nothing new on space shuttle flights. In this 1993 flight, David Wolf at rest and shortly after completing drew blood from Martin Fettman. Regular blood tests played a critical role in several experi- a session of heavy exercise on a cy- ments during that flight. cle ergometer.

CAN MED ASSOC J * JUNE 15, 1996; 154 (12) 1887 SLEEP AND CIRCADIAN be measured by core body tempera- sualization hinders basic understand- STUDIES ture and urinary variables (volume, ing of macromolecular structure as sodium, potassium, melatonin, corti- well as the rational, systematic design Humans have a biological clock sol), and performance by cognitive- of drugs intended to interact with tar- that ensures we are physiologically function tests and subjective reports get proteins and nucleic acids. and psychologically prepared for ac- of mood, vigilance, stress and work- Protein crystallization on Earth is tive wakefulness or restful sleep at load. As human spaceflights become disturbed by gravity effects such as appropriate times. Our preparation is longer, the results from this experi- convection and sedimentation, re- accomplished by circadian rhythms ment may have operational signifi- sulting in the production of defects that are generated, at least in part, by cance. Modification of work sched- and reduced crystal size and quality. a self-sustaining master oscillator lo- ules and the provision of time cues Small, inhomogeneous crystals are cated near the suprachiasmatic nu- may be recommended to maintain as- poor candidates for x-ray diffraction clei. However, abrupt changes in en- tronaut performance levels and feel- analysis. The APCF experiment will vironmental factors or daily routine ings of well-being. attempt to determine whether can result in misalignment of our bio- We will participate in several macromolecular crystals nucleate and logical clock relative to our activities. other physiological studies of neu- grow larger and more uniformly in The environment and routine as- rovestibular adjustment, regulatory microgravity. Ninety-six separate ex- sociated with life in space are quite physiology, bone demineralization periments under controlled tempera- different from those on Earth. Space- and cognitive function. On behalf of ture conditions are accommodated in flight is characterized by weightless- biologists, we will collect data on the the facility. A video microscopy sys- ness, 16 sunsets and sunrises per day, adaptation of other living systems tem will allow the facility's multiple social isolation, cramped living con- (plants, fish embryos and rats) to the users to observe the crystallization ditions and the absence of the Earth's microgravity environment. Together process in 24 of the reactor cells. 24-hour temporal structure. Over the these experiments complement each The long-term goal is not to estab- duration of a mission astronauts other to provide a comprehensive lish a protein crystallization facility might experience a progressive ten- view of the effects of space travel on in space, but to better understand dency towards circadian dysfunction, living systems. crystal growth on Earth. Improve- with resulting decrements in sleep ments in the crystallization process and performance. MATERIALS SCIENCE in conventional terrestrial labs may The aim of the sleep and circadian then accelerate advances in biotech- studies experiment from the Univer- The materials-science experi- nology, medicine and agriculture. sity of Pittsburgh is to evaluate our ments are less crew intensive because sleep, circadian rhythms and task per- mostly they will be controlled auto- POSTSCRIPT formance. For several nights the qual- matically or commanded from the ity and quantity of our sleep will be ground during the night while we Since 1984 1 have put my clinical evaluated by electroencephalograms, sleep. During the day, we will career partially on hold. My work as EOGs and EMGs, and computerized change samples and film for these in- an astronaut is a full-time commit- sleep diaries. Circadian rhythms will vestigations. ment that focuses primarily on oper- Of interest to the biotechnology ational training, medical research and industry is the Advanced Protein flight payload design. My employer, Crystallization Facility (APCF). With the Canadian Space Agency, recog- recent refinements in the technique nizes that my clinical skills benefit of x-ray crystallography, biochemists the goals of the Canadian space pro- and molecular biologists now have a gram, and has facilitated my contin- powerful tool for probing the struc- ued involvement in part-time med- ture of complicated macromolecules ical practice and continuing medical in three dimensions at the atomic education. level. The limiting factor in x-ray I miss contact with my patients crystallography is no longer the tech- and the challenges of diagnosis and nique itself but the availability of treatment, but I am doing what I en- macromolecular crystals. Most of the joy. My return to clinical medicine is thousands of known proteins and nu- postponed while I pursue present and cleic acids do not crystallize readily. future opportunities that are simply Failure to obtain these crystals for vi- out of this world. a

1888 CAN MED ASSOC J * 15 JUIN 1996; 154 (12)