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The pitfalls of altitude studies were shown veryclearly by Dr I. G. Pawson (University of California)in his comparison of child-growth surveys in Peru,Ethiopia, and inepal. The earliest studies on the

physiological effects of altitude were done in Peru,and the validity of assumptions made from the interest-ing findings there has seldom been questioned.Peruvian children born above 3500 m. tended to besmaller at birth, grew more slowly, and stoppedgrowing later, had a poorly defined adolescent growthspurt, and were delayed in some aspects by psycho-motor development, compared with children bornlower down the mountains. It was natural to assumethat at least some of these effects were an adaptiveresponse to hypoxia, especially since hypoxia wasshown experimentally to retard growth in animals.In Ethiopia, however, children living at high altitudeswere actually taller and heavier and matured earlierthan the lowland children, even though the two

populations were genetically homogeneous (as DrA. E. Mourant showed at the meeting with his studiesof blood-groups, plasma-proteins, red-cell enzymes,and hæmoglobin variants). It is difficult to separategenetic and environmental influences on growth, butthe most likely explanation of these reported differences,suggested Dr Pawson, is that growth retardation inhigh-altitude Peruvian children is a genetic adaptationto hypoxia in a population that has lived at a consider-able height for more than 2000 years, whereas theEthiopian plateau has been occupied for only 500years, and the effects of natural selection on the popula-tion have not yet had time to emerge. Moreover, thehypoxic stress encountered in the Ethiopian highlandsmay not even be enough to retard growth. And sincethe growth trend in Ethiopia is, in fact, the reverseof the expected, other environmental influences mustsurely be at work. For instance, the higher prevalenceof infections at lower altitudes may tend to slow growthas well as reduce blood-pressure; and the effects ofdifferences in weather and socioeconomic circum-stances are not known. Dr Pawson’s own studies inthe Himalayas question further some assumptionsabout the effects of altitude on growth. He has lookedat two populations of Tibetan origin-children ofTibetan refugees now living in Katmandu, at 4000 m.,and Sherpa children raised much higher up in theEverest region. In both groups growth was consider-ably retarded overall, not only by U.S. and Europeanstandards but also by Peruvian and Ethiopian measure-ments ; and the average age of menarche was perhapsthe latest in the world (Tibetans 16 years, Sherpas18.1 years). The Tibetan refugee children were

slightly more advanced than the Sherpas, but this isprobably because they had the advantage of food andhealth benefits from international agencies in Nepal.In Dr Pawson’s view, growth retardation in Peru ismost likely to be a developmental adaptation to hypoxiaassociated with high altitude ; in Tibetan and Sherpachildren altitude seems to have little effect on develop-ment, and growth retardation in these Himalayanpeople probably represents an extremely ancientTibetan gene pool; and in Ethiopia growth differencescan best be seen as a complex pattern of genetic andenvironmental interaction. These comparative studiesshow, above all, that patterns of growth are population-

specific and that it is just not possible to extrapolatethe effects of environmental stress from one populationto another.

STRAINING, SITTING, AND SQUATTINGAT STOOL

SIXTEEN years ago, an editorial 1 remarked that the

dynamic changes that result from straining at stoolwere understood but little. Unfortunately, this is stilltrue today. The act of defæcation alters anatomical

relationships. The angles between the sigmoid,rectum, and anus change and the actions of bothsmooth and voluntary muscles are coordinated, butthe mechanisms responsible for faecal continence andfor the voiding of stools remain ill-defined. 2 Defaeca-tion involves the Valsalva manœuvre. The rises in theintra-abdominal and intra-thoracic pressures havefar-reaching effects on the circulation. The return ofvenous blood from the limbs to the heart is impeded orhalted so that cardiac output falls. The arterialpressure is then maintained by reflex constriction ofperipheral blood-vessels. In affluent societies thereturn of blood from the lower limbs is furtherhindered, not only by gravity but also by the pressureof the lavatory seat upon the soft tissues of the thighs.These changes result in temporary stasis of blood inthe veins of the leg, and it has been claimed that theyfavour the dislodgment of any venous thrombi thatmay have formed. Pulmonary embolism is commonin the industrialised countries of the West as is the

constipation which leads to straining at stool. These

pressure changes in the venous system are greater inconstipated patients, who frequently need to strain

repeatedly while seated for a considerable time.3It has been claimed that the need to strain can be

reduced by adopting a squatting position when at

stool. This position is said to be natural since it isused by primitive peoples who pass large stools easily.The height of a modern lavatory seat prevents squattingand has been blamed for the prevalence of constipationin the United States, so that low-level toilets havebeen designed. 4,5 Surgeons who examine patients inthe lithotomy position are well aware that flexing thehips alters the position of the rectum relative to thebuttocks and tend to agree that squatting should makedefæcation easier. Other pro-squatters maintain thatthe full flexion of the thighs upon the trunk protectsthe valves of the leg veins against the transmittedforces of raised intra-abdominal pressure and so

lessens the likelihood of varicose veins developing.Does the position adopted for defaecation really

make a difference ? The man who squats because hehas no modern plumbing also tends to eat food that isless refined than that of his urbanised contemporaries.The need to strain and its undesirable secondary

1. Lancet, 1959, ii, 121.2. Connell, A. M. in the Management of Constipation (edited by

F. Avery Jones and E. W. Godding); p. 18. Oxford, 1972.3. Halpern, A., Selman, D., Shaftel, N., Samuels, S. S., Shaftel, H.,

Kuhn, P. H. Am. J. med. Sci. 1959, 237, 453.4. Bockus, H. L. Gastroenterology, 1944, 2, 54.5. Kira, A. The Bathroom. New York, 1967.

19

: effects can be lessened by senna. 3 Addition ofI millers’ bran to the diet enabled patients who had

been constipated to defxcate without effort and to

empty their bowels completely 6-without loweringany lavatory seats. If bran achieves the desired effect,the design of our plumbing need not be changed.This point will only be settled when the mechanics ofdefaecation has been investigated further.

NOTTINGHAM NOW

ONLY two medical schools in Britain, Nottinghamand Southampton, have had the chance to experiment,from the outset, with the new ideas in medical educa-tion. The first doctors graduated from Nottinghamthis week. What is the state of play in Nottingham,and what has been the experience of the first cohort ?1975 sees the medical school, with its annual intakeof 48 (to be doubled in October), settling into definitiveaccommodation on the site of the massive universityhospital under construction. 14 professorial chairs havebeen established over the past eight years, and theacademic side has 150 clinical teachers, among whomare a committed group of general practitioners andall hospital consultants in Nottingham with some fromadjacent centres. Most of the hospital-based clinicalteaching is divided between the two main hospitalsin the city.The aim in theory behind Nottingham’s five-year

course is a merging of basic scientific and clinical

disciplines, so that from the first week students areput into live clinical situations and given a chanceto identify with their eventual role as doctors. How-ever, the first three years of the curriculum are describedas basic medical sciences, leading to the B.MED.SCI.,and just over two years are allowed for essentiallyclinical work. The basic-sciences component is

imaginatively oriented towards three broad themes-(A) the cell, (B) man, and (C) the community-inan attempt to cut across the artificial packaging ofknowledge encouraged by competing disciplines. As

examples, human morphology, biochemistry, and

pathology are taught in theme A, physiology andbehavioural sciences in theme B, and theme C includessocial science and community health.Not surprisingly there are many stumbling-blocks to

integration. There is a tendency to identify specificdisciplines with themes, and academic demarcationdisputes persist. The rigid assessment system and thehighly competitive selection procedure encouragecompulsive achievers and impose their own logic. Infact, the first two years turn out not to be at all thatdifferent from the traditional second M.B., the majorinnovations being the greater emphasis on projectteaching, small-group work, the demonstration of therelevance of structure to function, the inclusionof behavioural issues and the context of man in society,and a population-based approach to health and disease.The third year of the honours course is probably themost successful educational experience-an elective

6. Painter, N. S., Almeida, A. Z., Colebourne, K. W. Br. med. J.1972, i, 137.

in a chosen subject leading to an original dissertation,several of which have been up to mastership standard.The clinical years in contrast look remarkably tradi-tional, with rotations between specialist firms and aheavy hospital emphasis (except for a month in generalpractice and an enterprising community follow-upscheme). Outpatient contact is limited. There is not

nearly enough involvement with local communities;and there is no shared learning with other membersof the health-care team.

Faced with the fundamental issue of how relevantthis education is to people’s needs, Nottingham hascome down on the side of the scientist rather than thehumanist. Beside McMaster or Case Western,Nottingham looks pretty staid, but its first gradu-ates are very competent clinicians and the seeds of thenew educational ideas may well be germinating withinthem. The real test is what sort of medicine thesedoctors will be practising ten years hence.

AINHUM

AiNHUM continues to be one of the minor but

mysterious problems of tropical medicine-and per-haps not such a minor one in Nigeria. Cole 1 studied1000 individuals in Ibadan who were not complainingof their feet and found 22 with evidence of past orpresent ainhum, a percentage far higher than the usualfigures. The process starts in the cleft between thefourth and little toes, involving usually the skin-grooveat the plantar/digital junction; and ultimately thetoe is encircled, with resultant autoamputation.1-3110 or so years after this curious disease was describedfrom South America the pathogenesis remains puzzling.Most sufferers have been Black, in the Old World 1and the New,3 and the fibrogenetic tendency of Blackswas long a suspected factor till this was disproved byKean and his colleagues. 3,4 The condition has beendescribed in Whites in Polynesians,6 and in Indians 7with or without some metabolic or associated dermato-

logical disorder. In some cases considerable fibrosis 6

and vascular changes have been described, thoughoften the changes seem secondary to the local lesion. i

Possibly there may be two types of ainhum: one

could be secondary to a skin disease, with a fibrousconstricting band; the other might be a primary diseasewith no fibrosis, only a deepening and extendinggroove with, in its early stages, gross thickening of thestratum corneum, calcification of ducts and sweat-

glands, and no evidence of parasites or infection.Ulcerated areas may become infected later, giving apicture of chronic inflammation deep to hyperkeratoticepithelium, with normal vessels, normal nerves, andsterile bone absorption. It is the groove, not fibroustissue, that constricts. The absence 4 of specific

1. Cole, G. J. J. Bone Jt Surg. 1965, 47B, 43.2. Spinzig, E. W. Am. J. Roentg. 1939, 42, 246.3. Kean, B. H., Tucker, H. A., Miller, W. C. Trans. R. Soc. trop. Med.

Hyg. 1946, 39, 331.4. Kean, B. H., Tucker, H. A. Archs Path. 1946, 41, 639.5. Shaffer, L. J. O. ibid. 1947, 43, 170.6. Browne, S. G. Ann. trop. Med. Parasitol. 1961, 55, 314.7. Aggarwal, N. D., Singh, H.J. Bone Jt Surg. 1963, 45B, 376.8. Davies, J. N. P., Hewer, T. F. Trans. R. Soc. trop. Med. Hyg. 1941,

35, 125.