1327

and urticaria have been found more often in therelatives of colitic patients than in controls,5,6 and thefirst three of these have been found especially oftenin the relatives of Crohn’s disease patients.5 Theseassociations are in keeping with the clinical and patho-logical features of both Crohn’s disease and ulcerativecolitis which suggest abnormalities of immunologicalmechanisms. There may be immunological abnor-malities specific for Crohn’s disease,7-10 but in thepast findings which seemed to offer a differentiationbetween Crohn’s disease and colitis have not beenconfirmed. Antibodies have been detected in thesera of colitic patients which react with an antigenderived from human colons.il In addition commonfeatures have been found between antigens derivedfrom colon and an Escherichia coli variant, 0: 14,12whilst bacterial injection has been found to inducethe formation of autoantibodies to gut mucosa.13However, similar antibody responses have been de-tected in Crohn’s disease.14 Delayed hypersensitivityreactions have been compared in colitis and Crohn’sdisease without any difference being found,15 andclearcut differences in serum-immunoglobulin con-centrations have yet to be demonstrated.16 Thedermal basophil response to diphtheria toxoid wassaid to differ in colitis and Crohn’s disease,17 butthis has not been confirmed.l8 Thus the clinico-

pathological differentiation of the conditions has notbeen paralleled by clear separation of their bio-chemical immunological or epidemiological features.They remain disease(s) in search of cause(s).

PLAN FOR FOOD

AGRICULTURE is the most important economic andsociological factor in the Third World: nearly 7 out ofevery 10 people depend directly on it for their living;it provides almost one-third of the developing coun-tries’ gross domestic product; for most of these coun-tries it provides 80-90% of exports (the countrieswith oil and mineral resources being the few exceptions).It is clear, therefore, that agriculture must be developedto provide the foundation of a healthy economy in thedeveloping regions. The United Nations Food and5. Hammer, B., Ashurst, A., Naish, J. Gut, 1968, 9, 17.6. Binder, V., Weeke, E., Olsen, J. H., Anthonisen, P., Riis, P.

Scand. J. Gastroent. 1966, 1, 49.7. Jones, J. V., Housley, J., Ashurst, P. M., Hawkins, C. F. Gut, 1969,

10, 52.8. Mitchell, D. N., Cannon, P., Dyer, N. H., Hinson, K. F. W.,

Willoughby, J. M. T. Lancet, 1969, ii, 571.9. Bendixen, G. Scand. J. Gastroent. 1967, 2, 214.10. Brown, S. M., Taub, R. N., Present, D. H., Janowitz, H. D. Lancet,

May 23, 1970, p. 1112.11. Broberger, O., Perlmann, P. J. exp. Med. 1959, 110, 657.12. Perlmann, P. Hammarstrom, S., Lagercrantz, R., Gustafsson, B. E.

Ann. N.Y. Acad. Sci. 1965, 124, 377.13. Asherson, G. L., Holborow, E. J. Immunology, 1966, 10, 161.14. Thayer, W. R., Brown, M., Sangree, M. H., Katz, J., Hersh, T.

Gastroenterology, 1969, 53, 311.15. Binder, H. J., Spiro, H. M., Thayer, W. R. Am. J. dig. Dis. 1966,

11, 572.16. Hobbs, J. R. Br. J. Hosp. Med. 1970, 3, 669.17. Rebuck, J. W., Hodson, J. M., Priest, R. J. Ann. N.Y. Acad. Sci.

1963, 103, 409.18. Tung, K. S. K., Hawk, W. A. Am. J. Gastroent. 1968, 50, 431.

Agriculture Organisation has brought out an Indica-tive World Plan for Agricultural Development, a workrunning to three volumes of technical and economicanalysis and conclusions. The regions studied are LatinAmerica, Africa south of the Sahara, the Near East andnorth-west Africa, and Asia and the Far East. Thebroad lines of the Plan have now been made accessibleto a wider readership. The basic need, of course, is forenough food to prevent famine. Population is growingat a rate of 2-5-3% a year in the developing countries:by 1985 nearly 21/2 times as much food will be neededas in 1962. But the challenge is not only to producehuge additional quantities of staple food to banishhunger; there must also be more and different kinds ofprotein-rich foods to reduce, if not to eliminate, mal-nutrition. Production must also be adjusted to changingpatterns in demand for food. For example, in Asiademand for cereals for human consumption will havedoubled by 1985, while demand for meat, fish, andeggs together, will have increased by 250%.The increase in the non-agricultural population is

another factor to be considered, since it will necessitatean increase of around 5-6% a year in marketed farmoutput. This obviously cannot be met by the sub-sistence agriculture which characterises much of thedeveloping regions-where most of the food is con-sumed by the farmers who produce it. But, in thewords of the Plan, " the problem of employment loomsas far more intractable than that of food supply ".Idle or partly idle people are by the far the greatestwaste of resources in the developing regions. Workersremain on farms, even though they may have work todo for only a small portion of their time, because it

provides at least the security of food and some sort ofhousing, and a protective family environment. But it isimperative that labour is released from the productionof food, and found other jobs to do.The Plan has two stages. In the first stage, priority is

given to increasing the yield per hectare of the basicfood crops-chiefly by intensifying the use of high-yielding varieties of wheat and rice. At the same timethe production of poultry, eggs, and (where acceptableas food) pork, must be stepped up. Increased produc-tion of milk, beef, veal, and other meat is urged, but isinevitably slow because the biological cycle of cattleand other ruminants is long. Poultry and pig produc-tion is essential to combat protein malnutrition at thisstage. In the second stage, production of cereals fordirect human consumption should expand less rapidlyas other foods are able to supply a larger proportion ofcalories. Land can then be released for other crops and

livestock, and an increasing proportion of cereals willbe used for feeding livestock. Crop-production mustthen become more varied as high-yielding varieties ofcrops other than cereals become available. Poultry,eggs, and pork would give way to some extent to beefand veal, and fresh milk must gradually take over thevital role that processed milk from developed coun-tries will have to play in the transition period. Mean-while, research programmes into new varieties of

cereal, and into the use of fertilisers and pesticides indifferent regions, must be carried out. The Plan warns,1. A Strategy for Plenty: The Indicative World Plan for Agricultural

Development. Food and Agriculture Organisation of the UnitedNations. World Food Problems, no. 11. S1.50; 12s.

1328

however, that preventing malnutrition is an even harderjob than providing enough staple food to abolish hun-ger. If the production figures proposed in the Plan aremet, food-supplies in terms of calories will just matchthe nutritional requirements of the developing countriesas a whole in 1975, but, because of inequalities in in-come, a large fraction of the population of these coun-tries will remain undernourished. The Plan also dis-cusses how to expand the agricultural export trade ofthe developing countries, and how to reduce imports;the necessity for training agricultural workers (par-ticularly in the middle technical grades); the cost ofproviding equipment, seed, fertilisers, and pesticides;the development of land and water resources; and therole of international aid.

POLAR MEDICINE

NOWADAYS man tends to adapt his environment tohis needs rather than himself to his environment. Buttechnical advances in environmental control create new

problems, and environmental physiologists are becom-ing increasingly preoccupied with the difficulties ofsurvival when that control breaks down. The UnitedStates base on the South Polar plateau is an exampleof a hostile environment successfully controlled:in a symposium of medical investigations done at thebase Shurley 1 reports that temperature seems to havebeen insignificant among the everyday environmentalstresses. Personnel at the base seem to have spent mostof their time in well-heated buildings, and whenessential tasks took them outside, their clothing ade-quately protected them against thermal stress. The

only symptoms commonly noted among people arrivingat the base were minor ones in which cold played littledirect part. Principal among them were dyspnoea,anorexia, insomnia, and headache. These symptomsare characteristic of altitude sickness induced by sud-den ascent to 10,000 feet or more 2 and were attributableto the low air-pressure at the base, equivalent to 11,000feet altitude in non-polar regions although the actualaltitude was 9280 feet. As with typical altitude sicknessthe symptoms improved or ceased within a few days.Contributory factors were mild carbon-monoxide

poisoning associated with poor ventilation of livingquarters, dryness of the air, lack of the normal dailycycle of light and darkness, and psychological dis-turbance associated with isolation. These problems,like environmental temperature, can be corrected-bybetter ventilation, oxygen inhalation, or entertainmentfacilities.The more severe the climate, the greater the risk if

the artificial environment fails. Some contributors tothe symposium described how newcomers to the polarplateau became exhausted after a ten-minute walk at—50°F. More serious examples would be the pilotor indoor technician who is suddenly stranded by anaccident on the polar ice, the survivor whose ship hassunk in cold water,4 or even the British city-dweller1. Shurley, J. T. Archs intern Med. 1970, 125, 625.2. Jungmann, H., Halhuber, M. J. in Medical Climatology (edited

by S. H. Licht); p. 257. Baltimore, 1964.3. Guenter, C. A., Joern, A. T., Shurley, J. T., Pierce, C. M. Archs

intern. Med. 1970, 125, 630.4. Keatinge, W. R. Survival in Cold Water. Oxford, 1969.

who goes hill-walking in wet weather with inadequateclothing. All of these face sudden and intense coldstress without the benefit of the behavioural and

physiological adjustment that is normally made to agradual, though possibly severe, change in climate.As the technology of environmental control improves,deaths from such accidents are becoming more fre-quent year by year. Yet the number of such deaths canbe much reduced by simple measures-for instance, byusing the fattest volunteers for tasks in which pro-longed cold exposure is inevitable, and by advisingsurvivors to avoid unnecessary exertion while awaitingrescue from cold water.Man adapts to long-term cold exposure mainly by

behavioural changes and by changes in thermoregu-latory responses to cold of the habituation or con-ditioned-reflex type. 4,6-8 Other long-term physiolo-gical adjustments are comparatively slight, and it isfortunate that many of the learning processes under-lying natural human acclimatisation can be replacedor even improved on by formal advice and training.The main lesson of these studies is perhaps that en-vironmental control, and the physiology of severeenvironmental stress, will need both to progress andto be applied together if man is to operate safely andeffectively in the more inhospitable parts of thisand other planets.

VARIANT ANGINA WITH NORMAL CORONARYARTERIOGRAM

ANGINA pectoris is generally believed to resultfrom myocardial hypoxia, usually caused by a restrictionof coronary blood-flow which limits the supply ofoxygen needed by the heart under mechanical load orneurosympathetic drive. Coronary arteriography 9,10has demonstrated the connection between angina andatherosclerotic narrowing of the coronary arteries.Anaerobic metabolism in the myocardium duringangina has also been illustrated by the detection oflactate discharge from the heart during coronary-sinuscatheterisation.11

Pathophysiological mechanisms associated with

angina are incompletely understood, and Whiting etal.12 now point to some deficiencies in knowledge. A52-year-old woman had the anginal type of chest dis-comfort, arising spontaneously at rest and duringsleep, but not with exertion. Pain was not at first

provoked by exercise testing, but definite S-T elevationaccompanied the rest pain. Ventricular prematurebeats, ventricular tachycardia, and one episode ofventricular fibrillation were recorded. Syncope due tocomplete heart-block associated with the pain requiredinsertion of a transvenous demand pacemaker. This

5. Pugh, L. G. C. E. Br. med. J. 1966, i, 123.6. Burton, A. C., Edholm, O. G. Man in a Cold Environment. Lon-

don, 1955.7. Glaser, E. M., Whittow, G. C. J. Physiol., Lond. 1957, 136, 98.8. Keatinge, W. R. ibid. 1961, 157, 209.9. Likoff, W., Kasparian, H., Segal, B. L., Novack, P., Lehman, J. S.

Am. J. Cardiol. 1965, 16, 159.10. Proudfit, W. L., Shirey, E. K., Sones, M. F. Circulation, 1966,

33, 901.11. Cohen, L. S., Elliott, W. C., Klein, M. D., Gorlin, R. Am. J.

Cardiol. 1966, 17, 153.12. Whiting, R. B., Klein, M. D., Vander Veer, J., Lown, B. New

Engl. J. Med. 1970, 282, 709.