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Biomedical subjects

O Pineda

Publications and source records attributed to O Pineda.

27 records · Page 2Linked to original sources
PubMed1981

Rise of blood pressure in calcium-deprived pregnant rats.

It has been postulated that calcium uptake is inversely related to blood pressure (BP) in animals and pregnant women. To test this hypothesis, 34 female, 142-day-old Wistar rats were studied prospectively. They were randomly assigned to either a calcium-free diet (16 rats) or a normal diet (18 rats). Weekly measurements of tail systolic BP showed a statistically significant increase in BP in the calcium-free group after 6 weeks of treatment. After 9 weeks on this diet, the animals were mated. Five in the control group and six in the calcium-free group became pregnant. Thereafter, both of these subgroups (pregnant and nonpregnant calcium-free diet) continued with significantly higher BP until they were put to death. Blood samples taken at the end of the study showed significantly lower values of calcium/magnesium (Ca/Mg) ratio, but higher inorganic phosphate in the group consuming a calcium-free diet. Blood pressure during the last 3 weeks of the study was significantly inversely correlated with the blood Ca/Mg ratio and directly correlated with magnesium and inorganic phosphate values. This article supports the hypothesis that a low-calcium diet is associated with high BP in pregnant and nonpregnant female rats.

Animals↗
PubMed1979

Studies on the bioavailability of zinc in man. III. Effects of ascorbic acid on zinc absorption.

As ascorbic acid is known to enhance the absorption of dietary iron and to inhibit the absorption of dietary copper, studies were undertaken to examine the effect of ascorbic acid on the bioavailability of zinc in human subjects. The index of absorption was the change in plasma zinc concentration after a 110-mg aqueous dose of ZnSO4.7H2O (containing 25 mg of elemental zinc). Doses of 0.5, 1.0, and 2.0 g of ascorbic acid, representing a spectrum of Zn:ascorbic acid molar ratios from the dietary to the pharmacological range, failed to produce any significant change in the pattern of zinc absorption. Moreover, 2.0 g of ascorbic acid, equivalent to a Zn:ascorbic acid ratio of 0.145 failed to improve the absorption of 108 mg of elemental zinc incorporated into 120 g of black bean gruel. Ascorbic acid over a range of dosages commonly consumed by man had no demonstrable effect on the absorption of inorganic zinc.

Absorption↗
PubMed1978

[Use of tests based on the analysis of expired air in nutritional studies].

Tests based on the analysis of the gaseous components of expired air have been developed to study intestinal absorption and intermediary metabolism of various nutrients. This paper reviews the breath-analysis tests based on the measurement of CH4, H2, and isotopically-labelled CO2 for studying the intestinal absorption of carbohydrates, fats, and bile salts, and intrahepatic metabolism. New technology employing mass spectrometry allows the use of the stable isotope, carbon-13, instead of the radioactive isotope, carbon-14, for CO2 breath tests. The nutritional application of the breath-analysis tests is discussed, and the advantages of the non-radioactive, non-invasive procedures, especially for use in children and pregnant women in whom standard investigational methods represent a discomfort or a radioactive hazard, are emphasized.

Bile Acids and Salts↗
PubMedDate not supplied

Serum alkaline phosphatase activity and skeletal maturation in Guatemalan adolescents.

Serum alkaline phosphatase activity (AP), stature and Tanner-Whitehouse-2 RUS skeletal age (SA) were determined for 873 rural Guatemalan youth and young adults 11-25 years of age. Mean AP decreases systematically with chronological age (CA) in girls, while an adolescent increase in mean AP occurs at 14 years in boys. When mean AP is calculated within SA groups, clear adolescent increases are apparent in girls, peaking at 11 years SA, and at 14 years SA in boys. Correlations between AP and relative skeletal age (SA-CA) decrease systematically from moderately positive at the youngest CA groups to moderately negative at the older ages, crossing zero at the chronological ages of maximum adolescent AP values. Analyses suggest the patterns of mean AP in adolescence follow closely the timing and patterns of growth velocity in stature in each sex, and are only indirectly related to SA as it is a proxy for the maturational timing of the adolescent spurt in stature.

Adolescent↗
PubMedDate not supplied

Calcium metabolism in children recovering from severe protein-energy malnutrition.

Twenty preschool children with severe edematous protein-energy malnutrition (PEM) were studied during the first 45 days of recovery. All children received 4 g/kg/day of protein and 150 kcal/kg/day of energy from a milk-based recovery formula, providing 130-140 mg/kg/day of calcium (Ca). Children were randomized to two treatment groups, one receiving intact milk formula and the other a lactose-free preparation. Both groups showed a high efficiency of intestinal calcium absorption, sustained even after the normalization of weight for height and lean body mass. The presence or absence of lactose in the diet did not affect intestinal calcium absorption, and increased stool volume in the early period of recovery in the children receiving intact milk was not associated with higher fecal Ca losses. Urinary Ca excretion was within the range reported for healthy children under a normal diet. These results suggest that therapeutic amounts of calcium should be delivered to children with PEM well beyond the normalization of body weight and lean body mass.

Animals↗