Showing papers by "World Health Organization published in 1973"

Immunoglobulin d as a lymphocyte receptor

Abstract: A large proportion of the human peripheral blood lymphocytes of adults and newborns having IgD were found also to have IgM on their membranes and vice versa. A few lymphocytes had one of these classes only. IgD and IgM could be capped independently on the same cell. The possibility that IgD was acquired by a cytophilic process was excluded by the finding that IgD-bearing cells were of one light chain type only, and by the direct demonstration of reappearance of IgD on the lymphocyte membrane during incubation in an IgD-free culture medium. On the basis of these findings, it is proposed that IgD functions as a lymphocyte antigen receptor.

Diel periodicity in the landing of Aedes aegypti on man.

Abstract: The dynamics of transmission of disease agents by vectors depends, in part, on the probability of host-vector contact, which can vary with fluctuations of both host and vector. As important as seasonal variations is 24-hour periodicity in activity. Periodicity in the landing of males and females of Aedes aegypti on man has been assessed by means of catches of 15 hours or longer, with several persons as a bait. The assessments were made in a suburban area of Tanzania and continued throughout one year. Activity was observed to be almost entirely diurnal and diphasic. Whereas the detailed activity pattern of males agreed closely with that found elsewhere in East Africa, that of the females was unusual on account of the symmetry of the morning and afternoon peaks. Possible causes of differences among studies are discussed.

Design of High-Rate Settlers

Abstract: The result of a comparison indicates that downflow settlers may have better performance provided the effluent collection system presents no problem. If the design criteria on overflow rate for conventional settling tanks are used for designing high-rate settlers, the latter will give better performance within the normal range of practical design. It appears that a high-rate settler system can handle considerable overloading without serious reduction in its turbidity removal efficiency. A settler with its flow through velocity less than 0.6 fpm (18.3 cm/min) tends to perform better than that with a higher flow through velocity even though the design overflow rate is kept the same. The theoretical design equation is found to incorporate the effects of angle of inclination and relative settler length reasonably well.

Mosquito‐borne disease problems In reply to: The urbanization of tropical countries

Abstract: (1973). Mosquito‐borne disease problems In reply to: The urbanization of tropical countries. C R C Critical Reviews in Environmental Control: Vol. 3, No. 1-4, pp. 455-495.

The Siphonaptera of the Indian Subregion

Abstract: This publication deals with the Siphonaptera known to occur in the Indian Subregion. 76 species of fleas have so far been recorded and the literature pertaining to them is scattered and not easy of access. In this paper the systematics of the flea fauna of the subregion is revised and presented in a consolidated form. Large numbers of specimens, including types and paratypes, have been studied for this work and the morphological characters differentiating the species have been redescribed using more generally accepted terminology. Synoptic tables for the identification of the families, genera and species recorded in the subregion have been worked out and a species distribution table is presented for the first time.

Toxicological evaluation of food additives and pesticide residues and their "acceptable daily intakes" for man: the role of WHO, in conjunction with FAO.

Abstract: Along with the increasing world population, there has been a growing demand for more food. To increase the production of food, a variety of pesticides is used to control pests, not only through the various stages of agricultural production but also during the storage and transportation of the food. In addition, as many urban communities have been created, there has been a growing need for large quantities of preserved or otherwise processed foods which are suitable for long-distance transportation and prolonged storage. Advances in science and technology and the concomitant general improvement of living standards have also directly or indirectly created the need for a greater variety of foods in terms of colour, flavour, texture, convenience, etc. In order to provide such foods, more and more pesticidal and other chemicals have been developed and utilized.

Immunity to cancer. Naturally occurring tumours in domestic animals as models for research. Part 2

Abstract: Part 1 of this Memorandum appeared in Vol. 49, pages 81-91. Part 2 covers neoplasia of the bovine urinary bladder; tumours of unknown cause (including melanomas, osteosarcomas, mammary tumours, lymphosarcomas, mastocytomas, transmissible venereal tumours, and histiocytomas); and the applications of animal models in studies of neoplasia. A summary of animal models is included as an annex.

Tissue explants used for enhancement of herpesvirus isolations.

Abstract: Herpesvirus recovery from normal and experimentally infected simian tissues prepared into 10 to 20% homogenates was compared with that obtained by explanting these same tissues. The explant procedure was by far the more sensitive of the two methods. As a result, 8 herpesvirus isolations were obtained by conventional virus isolation procedures in contrast to 74 isolates when explants were made from these same tissue sources. There is also evidence to suggest that the explant method is more sensitive than the use of tissue homogenates for recovery of other viruses as well.

Eradication of smallpox: the critical year ahead.

Abstract: a global programme for smallpox eradication. At that time many, if not most authorities, were openly sceptical of eradication as a realistic objective, let alone in a period of ten years, the time target proposed in Assembly debate. Such doubts seemed not unreasonable as the history of attempts to eradicate other diseases have been disappointing. As is well known, the discovery of jungle yellow fever thwarted an otherwise promising effort to eradicate this disease from the Americas and the problems experienced in the malaria eradication programme are a matter of record. Particularly pertinent, of course, is the fact that the global eradication of any disease has no precedent. However, during the past six years, sufficient progress has been made in the smallpox eradication programme to permit the inauguration in September 1972 of what has been termed the 'final phase', the object being to reduce smallpox incidence to nil throughout the world by mid1974.

Maximum number of statistically significant associations between risk factors and the frequency of an event in observational studies

Abstract: SUMMARY Follow-up studies often record a large number of factors that are suspected of being related to the occurrence of an event. How many of them can one hope to discover as being statistically significantly associated with this event? The number of such associations depends on the degree of risk they impart, the sample size used, the number of factors considered and their distribution in the population under study. An analysis is given when all factors are dichotomous.

Immunity to cancer. Naturally occurring tumours in domestic animals as models for research. Part 1

Abstract: PREVENTIVE VACCINATION IS SUCCESSFULLY PRACTISED TODAY AGAINST TWO NEOPLASTIC DISEASES OF DOMESTIC ANIMALS: fibropapillomatosis of cattle and Marek's disease of chickens (a lymphoproliferative disease). Also it may soon be possible to immunize cats against lymphosarcoma. This memorandum describes these diseases and the immunological reactions involved. It also mentions a number of other tumours that could be used for immunological studies.The greatest advances in immunity have been made with the tumours caused by viruses. The killed papillomavirus vaccine used against bovine papillomatosis produces demonstrable antibodies against the virus. In the case of Marek's disease of chickens, which is due to a herpesvirus, a live virus vaccine is used. This does not prevent infection with virulent virus, but prevents the development of neoplasia. The mechanism by which the vaccine produces its effect is not yet known. Immunization with live and with killed vaccines has been successfully carried out experimentally against leukosis of chickens, which is caused by an oncornavirus. There is evidence that it will be possible to vaccinate cats against lymphosarcoma with non-living vaccine.Naturally occurring cancer in domestic animals parallels cancer in man more closely than does experimentally induced cancer in inbred laboratory animals; therefore immunological studies with the former are more likely to yield results relevant to the problem in man. Experimental cancer in rodents provides models that have the great advantages of uniformity and availability, and they cannot be replaced. However, models in domestic animals offer valuable supplementary systems for research aimed at elucidating the basic principles of immunity to cancer. (Less)

Science's role in the World Health Organization.

Abstract: (WHO) has a clear but unachievable mission consciously bestowed by its founders in 1947. According to the WHO Constitution that mission is \"the attainment by all peoples of the highest possible level of health,\" with health defined as \"a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.\" The role of science in WHO, then, is to chart the shortest and most economical paths, in infinite progression, from a lower to a higher level of health toward a final goal which remains ever elusive but alluring. WHO is now entering its 25th year of operations, the last 12 of which have seen a considerable intensification of research activities. This is a respectable enough period of time to afford some perspective on the successes, failures, and problems of the United Nations arm that is perhaps most broadly involved in research and the application of science and technology to worldwide problems. Our involvement ranges the spectrum of the hard and soft sciences-physics, chemistry, biology, and sociology, and their components of mathematics, engineering, and economics-and applies them to problems of mental and physical health. Such problems are of immediate concern to peoples in all countries, but they assume special significance in the economically underdeveloped areas of the world where well over a half of the world's population dwells.

Pest Control Strategies Ten Years Hence: Malaria

Abstract: Every entomologist knows that malaria is due to a protozoan transmitted by Anopheles mosquitos, and the target of pest control strategy is the malaria Plasmodium . The discipline involved is more medical than entomological, and the criterion of success is essentially epidemiological. Although the present strategy of attack is directed against the mosquito vector, antimalarial drugs are important to protect against infection or to eliminate the vector. Immunization is an ultimate possibility.