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H De Waard

Publications and source records attributed to H De Waard.

3 recordsLinked to original sources

Contributions of ovarian failure and aging to blood pressure in normotensive perimenopausal women: a mixed longitudinal study.

Epidemiologic studies have shown that blood pressure increases more rapidly in middle-aged women than in middle-aged men. Whether or not ovarian failure contributes to this rapid rise is still not clear. In a follow-up study begun in 1979 and to continue for 10 years, the blood pressure of 193 healthy normotensive perimenopausal women, who lived in the mixed rural/industrial community of Ede, the Netherlands and who were initially aged between 49 and 56 years, was measured annually. During the course of the study, the onset of menopause of each participant could be established. Because of the mixed longitudinal design of the study, it was possible to evaluate the effects of both chronologic aging and time pre- or postmenopause on blood pressure. After the first seven years of follow-up, it was demonstrated that blood pressure did not increase in 168 women whose body weight was relatively stable. After multivariate analyses, systolic as well as diastolic pressure showed a significant negative relation (slope, 1.34 mmHg per year and 0.63 mmHg per year, respectively) with the years since menopause. On the other hand, the observed positive relation (slope, 0.81 mmHg per year) of systolic pressure with chronologic aging was not significant. No consistent association was found between diastolic pressure and chronologic aging. It is concluded that menopause cannot be regarded as a cause of hypertension; on the contrary, ovarian failure appears to have a protective effect on the increase in blood pressure as a result of chronologic aging. on the increase in blood pressure as a result of chronologic aging.

Aging

Casein-induced hypercholesterolaemia in rabbits is calcium-dependent.

Young male rabbits were fed semi-purified diets containing either casein or soy protein, both at a normal (0.84%, w/w) and a high (1.44%, w/w) level of dietary calcium. At the normal calcium level, casein, as compared with soy protein, increased the concentration in serum of total and free cholesterol and the ratio of free cholesterol to phospholipid. Also, casein increased the intestinal phosphate absorption and decreased the faecal fat excretion. The hypercholesterolaemic response of the rabbits on the casein diet was significantly correlated with both phosphate absorption (r = +0.744) and fat excretion (r = -0.701). The increased amount of dietary calcium inhibited the casein-specific effects on both the intestinal and the serum lipid parameters. In contrast, calcium did not change these parameters in rabbits fed the soy protein diet. These results support the hypothesis that the degree of phosphorylation of casein is involved in the mechanism of the casein-induced hypercholesterolaemia by means of its effect on the enterohepatic cycle of bile acids.

Animals