Racial differences in susceptibility to infection by Mycobacterium tuberculosis

Article Abstract:

The prevalence of tuberculosis among blacks is about twice that of whites; however, this knowledge alone cannot be used to distinguish environmental from genetic factors, nor does it permit distinguishing susceptibility to infection from development of active disease once infected. In controlled environments, however, such distinctions can be made. In 227 nursing homes and two prisons, in which whites and blacks were completely integrated, records of tuberculin testing were examined to determine how many originally tuberculin-negative individuals converted to a tuberculin-positive, events which indicate infection with Mycobacterium tuberculosis. In the nursing homes, which represented 25,398 initially negative individuals, the conversion rate for blacks was 19 times that of whites. Similar results were obtained from the examination of prison records. Although blacks have a higher prevalence of tuberculosis, it was found that there was no racial difference in the percentage of blacks or whites who go on to develop clinical tuberculosis once they have been infected. Blacks are apparently more susceptible to tuberculosis than whites, and the factors that govern the progression from infection to disease are independent of those governing initial infection. (Consumer Summary produced by Reliance Medical Information, Inc.)

Case studies, Demographic aspects, Tuberculosis, Health, Health and race, Ethnic groups, Epidemiological research, Cross sectional studies, Disease susceptibility

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Racial differences in aldosterone excretion and plasma aldosterone concentrations in children

Article Abstract:

Afro-Americans are known to have a greater risk of elevated blood pressure (hypertension) than white Americans. A study was conducted of 249 Afro-American and 466 White children from 5 to 16 years of age recruited from 18 schools in Indianapolis. Nighttime urine specimens were collected, from which dietary sodium and potassium intake were estimated. Blood pressures were measured and samples of blood and urine were analyzed for levels of aldosterone. Aldosterone is the most powerful mineralocorticoid (electrolyte-mediating hormone) produced by the adrenal gland. Aldosterone works on the kidney to increase retention of sodium and to facilitate secretion of potassium. There was a clear reduction in the secretion of aldosterone levels by Afro-American children, who produced only 60 percent of the amount secreted by similarly aged white children. Afro-American children also had a statistically significant increase in both systolic and diastolic blood pressure. The physiological and pathological effects of these differences are not understood, but could they could represent an important mechanism responsible for the higher risk of hypertension in Afro-Americans.

Measurement, Risk factors, Blood pressure, Aldosterone assay, Aldosterone

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Effects of regular exercise on blood pressure and left ventricular hypertrophy in African-American men with severe hypertension

Article Abstract:

Exercise may be effective in reducing blood pressure and enlargement of the heart in African-American men with severe hypertension. Of 46 African-American men with severe hypertension, 23 were assigned to receive drug therapy alone and 23 to receive drug therapy and follow an exercise program. The exercise program involved riding an exercise bicycle three times a week at 60% to 80% maximal heart rate for 20 to 60 minutes. After 16 weeks, the average systolic pressure decreased from 88 millimeters (mm) of Hg to 83 mm Hg in the exercise group, and increased from 88 mm Hg to 90 mm Hg in the non-exercise group. Enlargement of the left ventricle decreased more in the exercise group than in the non-exercise group after 16 weeks. During a second 16 week phase, medication was decreased successfully in 10 of 14 exercisers but in none of the non-exercisers.

Care and treatment, Evaluation, Exercise therapy, Heart enlargement, Heart hypertrophy

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