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Biomedical subjects

B E Hopwood

Publications and source records attributed to B E Hopwood.

9 recordsLinked to original sources
PubMed1990

The Kenyan Luo migration study: observations on the initiation of a rise in blood pressure.

OBJECTIVE: To demonstrate the magnitude, timing, and cause of changes in blood pressure that occur in migrants from a low blood pressure population on moving to an urban area. DESIGN: A controlled longitudinal observational study of migrants as soon after migration as possible and follow up at three, six, 12, 18, and 24 months after migration. A cohort of controls living in a rural area who were matched for age, sex, and locality were also observed at the same periods. SETTING: 35 Villages on the northern shores of Lake Victoria in western Kenya and Nairobi. PARTICIPANTS: 325 Members of the Luo tribe aged 15 to 34 years who had migrated to Nairobi and 267 controls living in villages. The numbers of both groups reduced during follow up such that only 63 migrants and 143 controls were followed up for two years. MAIN OUTCOME MEASURES: A medical questionnaire and three 24 hour diet histories were completed by migrants and controls. Height, weight, pulse, and blood pressure were measured. Three 12 hour overnight urine samples were collected from all participants and analysed for sodium, potassium, and creatinine concentrations. RESULTS: The mean systolic blood pressure of migrants was significantly higher than that of controls throughout the study, and the distribution of blood pressure was shifted to the right compared with controls. The mean diastolic blood pressure of the two groups diverged over time. Blood pressure differences were not due to selective migration. The migrants' mean urinary sodium:potassium ratio was higher than that of controls (p less than 0.001) throughout, and weight and pulse rate were also higher among migrants, although differences diminished with time. CONCLUSIONS: Urinary sodium:potassium ratio, pulse rate, and weight are important predictors of increased blood pressure among migrants from a low blood pressure community and may also be implicated in the initiation of essential hypertension.

Adolescent↗
PubMed1985

Determinants of blood pressure changes due to urbanization: a longitudinal study.

Changes in blood pressure (BP) and associated factors which occur on migration from a rural to an urban environment are under observation in a longitudinal study. Blood pressures, heart rate (HR), urinary electrolytes, sociological and anthropometric data are recorded at 0, 3, 6, 12, 18 and 24 months following migration and compared with a cohort of age and sex-matched rural based controls. Data from the first 6 months' follow-up reveal that the migrants' BPs are higher and tend to rise compared with controls, in whom BP falls progressively with time. Changes in body weight and dietary electrolytes appear to explain some of the BP differences, while differences in pulse rates between groups suggest that a further mechanism operative through the autonomic nervous system is responsible for some of the elevation of systolic BP shown amongst migrants, particularly on arrival in the urban area.

Adult↗
PubMed1984

Salt and blood pressure in various populations.

A relationship between salt intake and blood pressure has been described in cross-sectional studies of several populations. However, serious methodological problems in many studies could have resulted in erroneous results. In the present studies, the blood pressure profiles of a Kenyan tribe have been shown to differ according to environment, being lower in rural and higher in urban communities. Although several factors could explain the observed blood pressure differences, dietary factors, including sodium and potassium intake, could be important determinants of the observed differences. A within-population study of 1,737 rural male subjects was carried out in which it was found that systolic and diastolic pressures correlated positively with urinary sodium/potassium ratios. In this rural group, within subject day-to-day variations in dietary electrolytes are small, as indicated from multiple urinary collections, and are less than those observed in Western societies. We have demonstrated in this rural population that causal samples of urine correlated well with average sodium and potassium excretion over a 7-day period. Preliminary results are reported of a longitudinal study of migrants from a low to a high blood pressure environment and a nonmigrant population. The blood pressure rise consequent to migration was related independently to changes in body weight and urinary electrolytes. The implications of these observations for active intervention studies are discussed.

Adolescent↗
PubMed1984

Blood pressure and its correlates in an African tribe in urban and rural environments.

As part of a longitudinal study of migrants who move from a subsistence farming rural society to Nairobi, blood pressures and associated factors were measured in cross sectional studies of members of the Luo tribe in their traditional rural environment and in the urban environment of Nairobi. Blood pressures in Nairobi correlated with duration of urban residence. In the rural area men showed a negligible rise in blood pressure with age, and both sexes showed a significantly smaller rise than in the urban area. Although mean weights of the rural group were smaller, this did not account for all the urban/rural differences in blood pressures. Nevertheless, mean urinary sodium concentration and sodium ratios (sodium/potassium and sodium/creatinine) were significantly higher in the urban group whereas mean urinary potassium concentration and potassium/creatinine ratio were significantly lower. Perhaps the ratio of sodium to potassium in the diet contributes to the different blood pressure profiles of these two populations.

Adult↗
PubMedDate not supplied

Blood pressure and associated factors in a rural Kenyan community.

Blood pressure (BP) and associated factors were determined in 1737 men in a remote Kenyan agricultural community. Systolic BP showed no significant rise with age until after 54 years; diastolic BP showed a small rise with age. Both systolic and diastolic BP correlated with weight independent of age. Systolic and diastolic BP correlated positively with casual urinary sodium/potassium and negatively with potassium/creatinine ratios. Both systolic and diastolic BP correlated significantly with the number of years of education, as did urinary sodium/potassium and sodium/creatinine ratios. Potassium/creatinine ratios were negatively correlated with the number of years of education. Blood pressure and urinary sodium/creatinine ratios were significantly lower in subsistence farmers compared with those in other occupations, and potassium/creatinine ratios were significantly higher. Two pilot studies of Luo tribesmen showed a strong correlation between casual urinary electrolyte ratios and those derived from 24-hour urine samples and a greater variance of sodium excretion between these people than that found within individuals. These results suggest that a relationship between BP and casual urine electrolyte estimations may be identifiable in communities where there is less day-to-day dietary variation. They also suggest that some of the changes in BP associated with urbanization could be mediated by changes in dietary electrolytes.

Adolescent↗