26 August 1967 Leading Articles MEDIBALJOURNAL 509 her patients or the hospital midwife to undertake the home lation has been found between arsenic level in the blood and visiting of them after discharge. degree of renal insufficiency as indicated by blood creatinine Br Med J: first published as 10.1136/bmj.3.5564.509 on 26 August 1967. Downloaded from From the Bradford reports it can be seen that the final measurements. But speculative inquiries of this kind are decision to permit a mother and baby home after 48 hours worth while because they may sometimes provide the first must be made by someone at least of registrar status. It clue to the solution of an intractable problem. Information would also be of considerable value if the general practitioner of a more immediately useful kind can be expected from and district midwife in charge of such a case could freely using activation analysis in problems where the underlying obtain an opinion by domiciliary consultation from either the biochemical and physiological considerations are better hospital obstetric or paediatric department on any puerperal understood. or neonatal complication before readmission of the woman Thyroid metabolism, much studied by radioactive isotopes, after she has returned home. offers interesting problems for attack by activation analysis. When early discharge was discussed in these columns three Semi-automatic methods for the routine determination of years ago' the conclusion was drawn that, though it might protein-bound stable iodine have been elaborated, notably be suitable in emergency conditions, it had little part in in France,2 where the establishment of a laboratory to carry long-term planning. That reflected an opinion then preva- out such tests on a commercial basis is now being considered. lent and previously advanced by the Royal College of The basis of the estimation is the partial conversion, under Obstetricians and Gynaecologists.4 But it may well need bombardment by thermal neutrons, of stable iodine-127 to revision. G. D. Pinker and A. C. Fraser' reported after a the radioactive isotope iodine-128, which has a half-life of trial over three years at St. Mary's Hospital that the scheme 25 minutes. Chemical manipulation is necessary to remove was "safe and desirable" for both mother and baby and radioactive isotopes of sodium and other elements formed in recommended that the voluntary early discharge of selected abundance along with the iodine-128. patients should be an accepted part of the maternity services. New prospects have resulted from the development (also Advice on the planning of arrangements has been given by in France) of techniques using iodine-129. This isotope has the Ministry of Health.6 Now the two reports from Bradford a very long half-life (1.6 x 107 years) and a number of other indicate that it would be reasonable. to explore the whole properties particularly useful for clinical applications. The question further. gamma-radiation which it emits is of very low energy and gives a correspondingly small radiation dose to the patient, but can be detected in the thyroid gland by an external scintillation counter. It 'would be possible, by daily admini- Activation Analysis stration of small doses of iodine-129 to a patient, to attain Radioactive isotopes have contributed to many advances in isotopic equilibrium. When this state has been reached, the clinical science, especially during the last 20 years, when ratio of the concentration of\iodine-129 to iodine-127 is the ample supplies have been available as by-products of the same throughout the body. Isotopic equilibrium cannot be atomic energy programme. The complementary technique reached with iodine-125 or iodine-131 because of the heavy of activation analysis offers some distinctive advantages which dose of radiation which the patient would incur. With iodine- http://www.bmj.com/ deserve closer study. 129 the total dose over a period of a year in isotopic equili- The basis of this technique is that most elements are brium would be very much less than that incurred in a single partially converted to radioactive isotopes on exposure to tracer test with iodine-131, but the amount of information to neutrons-for example, inside a nuclear reactor. The be obtained by radioactive assay of blood, urine, and the induced radioactivity is highly specific for the elements thyroid itself would be substantially greater. The usefulness contributing to it. It is therefore possible to identify and of this isotope is further enhanced by the fact that, on exposure estimate many of the elements present in a sample by study- to irradiation by thermal neutrons, it is partly converted to ing the radioactivity induced by a short spell inside a nuclear another radioactive isotope, iodine-130 (and its isomeric on 30 September 2021 by guest. Protected copyright. reactor. This apparently roundabout procedure is, for many form, iodine-130m) allowing detection at excellent sensitivity elements, the most sensitive method of analysis now available. by activation analysis. Recently the use of this technique in the identification of The technique of activation analysis in vivo, first reported human hair was discussed in these columns.' on by J. Anderson and others' in 1964, offers the possibility The uses of activation analysis in clinical science are more of direct measurement of the total stable iodine content of often commended than practised, but useful progress was the thyroid. In principle, the stable iodine-127 in the thyroid reviewed and discussed at the symposium on Nuclear Activa- can be activated by neutron bombardment to yield radio- tion Techniques in the Life Sciences held in Amsterdam from active iodine-128, which can be measured by external 8 to 12 May under the auspices of the International Atomic counting. In practice this simple technique cannot give Energy Agency. Several research projects are at present accurate results, mainly because of the impossibility of concerned with the elemental analysis of various body achieving uniform irradiation of the thyroid gland by constituents in the hope of correlating pathological signs with neutrons. A technique entailing prior administration of abnormalities in the metabolism of minor elements not iodine-129, followed by neutron irradiation of the thyroid normally within the purview of the biochemist. and simultaneous estimation (by external scintillation count- A typical inquiry entailed the estimation of seven trace -ing) of iodine-128, 130, and 130m, provides an accurate elements in blood from normal persons and from patients estimate of thyroid iodine in the sheep and may soon be with chronic uraemia. Levels of arsenic in the blood were applicable to man.' on average three times higher in the uraemic patients. A Brit. med. 7., 1967, 1, 584. suggestion that the apparent retention of arsenic may contri- 2 Comar, D., and Le Poec, C., Proceedings of the International Confer- ence on Modern Trends in Activation Analysis, p. 351. 1966. Texas bute to toxic manifestations of uraemia can hardly be Agricultural and Mechanical University, College Station, Texas. supported, partly because the quantities are so small (about 3 Anderson, J., et al., Lancet, 1964, 2, 1201. I Lenihan, J. M. A., Comar, D., Riviere, R., and Kellershohn, C., 5 pug. of arsenic per litre of blood) and also because no corre- Nature (Lond.), 1967, 214, 1221. 510 26 August 1967 Leading Artides The remarkable sensitivity of activation analysis has been the Royal Institute of British Architects, the Royal Institution exploited in studies of the electrolyte equilibrium of the fluids of Chartered Surveyors, and various Government depart- Br Med J: first published as 10.1136/bmj.3.5564.509 on 26 August 1967. Downloaded from of the inner ear. The dynamic equilibrium between peri- ments. lymph (which is a fluid of the extracellular type, with sodium The new code covers ambulant-disabled people and the predominating over potassium) and endolymph (in which wheelchair-bound especially, but also incorporates a short potassium ions greatly outnumber sodium ions) is linked with section on the special requirements of the blind and the the functions of hearing and balance. Reliable estimates of deaf. It is based both on empirical observation and on the concentrations of sodium and potassium have been specific pieces of research-for example, into suitability of obtained by activation analysis of small samples of fluid different designs of door handles,' into the manoeuvring space (2-10 pul.) obtained from experimental animals, and there of wheelchairs, and into the layout of sanitary and cloakroom are grounds for hoping that this technique also may be accommodation. Many of these studies were sponsored by extended before long to man. the. bodies represented on the committee. The recommenda- tions are such as can be carried out, for they are realistic rather than idealistic and economic considerations have been taken fully into account, as indeed they must be when any Architectural Aids for Disabled public building is planned. The new code of practice follows One of the shocks a patient commonly experiences on becom- the lead of the American7 and Canadian' standards, though ig severely disabled is to find how many activities that he it departs from the former in one significant feature in stress- formerly took for granted are now beyond his reach. Many ing the need for the signposting of- special facilities for disabled people adjust to restrictions on movement and activi- disabled people. ties by developing new skills, by using ingenuity to surmount Nobody knows how many disabled there are in Britain. obstacles, and so by sheer determination contrive to manage The American7 and Canadian8 recommendations take the for themselves in an unsympathetic environment. Part of figure of one in seven of the population as having a permanent their' adjustment lies in appreciating the things they cannot physical disability or an infirmity associated with age.