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Biomedical subjects

C H Wyndham

Publications and source records attributed to C H Wyndham.

At least 37 records · Page 2Linked to original sources
PubMed1981

The loss from premature deaths of economically active manpower in the various populations of the RSA. Part I. Leading causes of death: health strategies for reducing mortality.

Age-adjusted mortality rates (MRs) per 100 000 for the leading causes of death were calculated for 1970 for Asians, Coloureds and Blacks and compared with the MRs of Whites for the economically active age-group of 15 - 64 years. Marked differences in mortality patterns were shown by this comparison. At the one extreme were the Whites in whom the five leading causes of death in rank order were ischaemic heart disease, motor vehicle accidents, cerebrovascular accidents (CVA), cancer of the digestive system and bronchitis and associated respiratory diseases--a mortality pattern which is characteristic of a developed Western community. At the other extreme were the Blacks in whom the five leading causes of death in rank order were "ill-defined" diseases, the pneumonias, tuberculosis, CVA and homicide and unspecified violence -- a mortality pattern commonly seen in less developed communities. Reducing mortality in the various populations will not come about by spending more money on hospital-bases curative medicine but by greater emphasis on health promotion and disease prevention. Quite different health strategies are needed to reduce mortality in the Whites and Asians on the one hand, and the Coloureds and Blacks on the other. The health strategies required for Whites and Asians involve behavioural changes in lifestyles, whereas for Coloureds and Blacks they involve elementary public health measures such as clean water, proper sanitation, better housing improved nutrition and health education.

Adolescent↗
PubMed1980

The prevalence of ischaemic heart disease risk factors in middle-aged White miners.

The prevalence of ischaemic heart disease (IHD) risk factors was studied in a random sample of 3930 White miners, aged 45 - 62 years, of whom 202 had evidence of a definite or probable myocardial infarct (MI) on electrocardiographic and chest pain criteria. Ninety-two were classified as "suspect" MI cases and were excluded from the study. The prevalence of the major IHD risk factors (mildly elevated serum total cholesterol levels and blood pressure, and cigarette-smoking) in the 3636 White miners who had not had Mls did not differ from those in comparable populations in the UK, USA and Australia, nor did those of secondary IHD risk factors (elevated blood glucose and plasma uric acid levels and being overweight) differ in the various populations. There was, however, a relatively high percentage of middle-aged White miners with two (25.2%) and three (4.4%) simultaneous IHD risk factors. Such men have a much higher probability of an MI within 8 years than men with no IHD risk factors. This study indicates that 770 out of every 1000 middle-aged White miners would have one or more major IHD risk factors; of these, 252 would have two risk factors and 44 three risk factors. This finding points to the urgent need for an intervention programme for the early detection and prevention of IHD risk factors.

Blood Glucose↗
PubMed1980

A comparison of the mortality rates of white South Africans with those of the population of England and Wales.

The health of Whites in South Africa in 1970 was poorer than that of the population of England and Wales, judged by the higher mortality rates (MRs) for all causes of death of White South Africans, for all ages combined and for every age interval from infancy to old age. Two groups of causes of disease were the main reasons for the poorer health of White South Africans: (i) 'diseases of the circulatory system' accounted for 50-60% of the higher MRs for all causes of death; ischaemic heart disease and cerebrovascular disease were the two main causes of circulatory deaths, and MRs for these two diseases were much higher in White South Africans than in England and Wales; (ii) 'accidents, poisonings and violence' accounted for 38% of the higher MRs for all causes of death in males and for 17% of those in females. Motor vehicle accidents and suicide were the main causes of accidental deaths, MRs of White South Africans being much higher than those in England and Wales. These MRs were among the highest in the world. Other diseases which contributed, to a small extent, to the poorer health of White South Africans because of the higher MRs compared with those in England and Wales were cirrhosis of the liver in adults, gastro-enteritis, meningitis and septicaemia in infants and children, and 'other ill-defined and unknown causes of death' in elderly people.

Adolescent↗
PubMed1979

Mortality from cardiovascular diseases in the various population groups in the Republic of South Africa.

Cardiovascular mortality rates (MRs) for 1970 were calculated from Department of Statistics reports for the various populations of the RSA and showed that the MRs for chronic rheumatic heart disease were highest in Coloureds and lowest in Whites, the rates for Asians and Blacks being intermediate, and that a relatively high proportion of all cardiovascular deaths in the 15- 24-year group were due to this disease. It was also found that the pattern of cardiovascular diseases differed in the various population groups as follows: in White males the MRs for ischaemic heart disease (IHD) were high (4 times the rate for cerebrovascular disease (CVD). In White females the MRs for IHD and CVD were similar and accounted for most deaths from cardiovascular disease. The MRs for hypertensive disease were low in Whites. Asians in the older age groups had the highest MRs for IHD, CVD and hypertensive disease of all the population groups. The MRs for IHD of Asians in general exceeded those of Whites. Coloureds had high MRs for CVD, relatively high MRs for hypertensive disease and other forms of heart disease (mainly ill-defined heart disease) and relatively low MRs for IHD (compared with Asians and Whites). Blacks had high MRs for CVD and other forms of heart disease (mainly ill-defined heart disease), relatively high MRs for hypertensive disease and very low MRs for IHD. The MRs for cardiovascular diseases in Blacks are not reliable.

Adolescent↗
PubMed1979

The role of physical activity in the prevention of ischaemic heart disease. A review.

It has been demonstrated that vigorous leisure-time physical activity and hard physical occupational work protect against ischaemic heart disease (IHD), but the protective mechanisms are not clear. According to most research reports programmes of regular physical activity do not lower serum cholesterol concentrations, but they do lower serum triglyceride levels. Dedicated marathon runners have lower serum low density lipoprotein and higher high density lipoprotein levels than controls, but it has not been proved that this lipoprotein pattern is the result of regular, high-intensity exercise. Regular physical exercise lowers the blood pressure to a greater degree in hypertensives than in controls. An exercise programme plus diet had no greater effect on serum total cholesterol levels than did diet alone on subjects with primary hyperlipoproteinaemia types IIa, IIb and IV. However, in types IIb and IV the exercise programme plus diet was more effective than diet alone in lowering serum triglyceride levels. The results of these studies are not valid for deciding whether regular exercise decreases the IHD risk factors studied. Such judgements must be based upon the results of randomized, controlled trials. The only satisfactory trial of this nature to date was done in Helsinki, and its results were inconclusive.

Adult↗
PubMed1978

Climate and disease.

A summary of the literature shows that there are well-marked seasonal variations in mortality for total deaths, for respiratory and cardiovascular diseases and for diabetes, the mortality rate being higher in winter than in summer. These seasonal variations in mortality are seen in infants under 1 year of age and in older people but not in youths and young adults. The amplitude of the seasonal variation in mortality increases with increasing age because of the higher incidence of cardiovascular and respiratory mortality in older people. Seasonal variations in air temperature are a more important determinant of seasonal variations in respiratory and cardiovascular deaths than are fluctuations in air pollution; there is usually a time-lag of up to a week in the change in air temperature before the mortality rate for these diseases increases; a run of 4 - 5 days of stressful temperatures (either hot or cold) has more effect on mortality than an isolated hot or cold day. Examination of the seasonal variations in all causes of death of the four population groups in South Africa shows that Whites and Asians display the typical pattern of a winter high and a summer low mortality of populations in developed countries. The seasonal variation in mortality of Coloureds and Blacks is quite different. It shows two peaks, one in winter and one in summer. This bimodal pattern in the seasonal variation is due to the fact that one-third of all Coloured and Black deaths occur in infants under 1 year of age and most of these deaths occur in summer as a result of gastro-enteritis. Comparison was made of the seasonal variations in mortality rates for all causes of death and for respiratory and ischaemic heart disease (IHD) deaths of Whites over 40 years of age in Durban and Johannesburg. This showed that the seasonal variation for all causes of death is greater in Johannesburg than in Durban, i.e. proportionately more older Whites die during winter in Johannesburg than in Durban. The reason for this difference is that the seasonal variation in respiratory disease mortality is much greater in Johannesburg than it is in Durban, but the seasonal variation in IHD mortality is the same in the two cities.

Adolescent↗
PubMed1976

Acclimatization in a hot, humid environment: energy exchange, body temperature, and sweating.

Four trained young men, worked for 4 h/day at 43-50% of their maximum aerobic capacity for 3 days at 25 degrees C db, 18 degrees C wb and then for 10 consecutive days at 45 degrees C db, 32 degrees C wb. Their thermal status was assessed using direct calorimetry. As a group, the men showed classical acclimization responses, but there were marked individual differences. The calorimetric analysis revealed that reductions in strain were associated with minor changes in heat balance confined to the first and last hours of exposure. Events occurring within the first 4 days appeared to have little effect on body temperatures. Significant decreases in body temperature took place only when sweat and evaporation rate increased. A 10% increase in evaporation rate was accompanied by a 30% increase in sweat rate and a 200% increase in unevaporated sweat; thus, there is a wasteful overproduction of sweat. By the 10th day skin temperature was confined to the level necessary to evaporate sufficient sweat to achieve thermal balance with a fully wet body surface. The efficiency of heat transport within the body did not change with acclimatization.

Acclimatization↗
PubMed1976

Acclimization in a hot, humid environment: cardiovascular adjustments.

Four trained young men worked for 4 h/day at 40-50% of their maximum aerobic capacity first for 3 days at 25 degrees C db, 18 degrees C wb, and then for 10 consecutive days at 45 degrees C db, 32 degrees C wb. This portion of the study was mainly concerned with central circulatory changes during acclimatization. The central circulatory adaptation to work in heat could be divided into four distinct phases: phase I (day 1) was characterized by a progressive fall in stroke volume (SV) during heat exposure but cardiac output (CO) was maintained above control values by high heart rates. Phase II (days 2 and 3) was marked by increases in SV ande decreases in heart rate but with little change in CO from phase I. During phase III (days 4-8 of acclimatization), CO increased due to increases in SV. Phase IV (days 6-8) was associated with decreases in rectal and skin temperature towards control levels. SV and HR both decline in this phase so that CO was not elevated greatly above control levels. The results indicated that central circulatory and temperature regulating events are not casually associated in acclimatization.

Acclimatization↗
PubMed1976

Acclimatization in a hot, humid environment: body fluid adjustments.

Four trained men worked 4 h/day at 40-50% of their maximum aerobic capacity first for 3 days at 25 degrees C db, 18 degrees C wb and then for 10 consecutive days at 45 degrees C db, 32 degrees C wb. Between days 1 and 2 of heat exposure mean total circulating protein (TCP) and plasma volume (PV) increased 11.6% and 9%, respectively. Preexposure TCP and PV increased until day 6 of heat exposure. Of the protein fractions beta-globulins underwent the largest relative increase. During work movement of protein into and out of the vascular compartment was similar in control and acclimatizing subjects but the latter generally maintained a greater amount of protein and fluid within the vascular volume. There was no evidence of salt and water retention. The increase in vascualr volume was ascribed to transfer of interstitial protein and water to the vascular volume. Regression coefficients indicated significant correlations for changes in plasma volume versus heart rate, stroke volume, and cardiac output during acclimatization. It was concluded that the most critical event in heat acclimatization is the expansion of the plasma volume.

Acclimatization↗
PubMed1975

Orthostatic responses in Caucasians and Bantu.

Nine Caucasian and 13 Bantu young men, all untrained and unacclimated to heat, were tilted head-up for 20 min before and after 4 h of exercise performed at a load of 35 W at room temperature of 23 degrees C and in heat (33.9 degrees C DB, 32.2 degrees C WB). In heat, all Bantu but only four Caucasians completed the 4 h of exposure. The change in systolic blood pressure from recumbency to orthostasis was negligible in the Bantu and adverse in the Caucasians, during pre-exercise tilting at 23 degrees C. Similar differences were found during tilting after exercise at 23 degrees C. Post-exercise orthostatic heart rate did not differ between the two groups despite higher exercise heart rats of the Bantu. Seven subjects in each group fainted during heart-orthostatism, and the difference in systolic blood pressure between recumbency and orthostasis in heat was substantially more adverse in the Caucasians. High relationships were found between exercise heart rate, orthostatic heart rate, and fainting episodes. The results suggested that Bantu make better orthostatic adjestments than Caucasians.

Adult↗