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Biomedical subjects

A Kirksey

Publications and source records attributed to A Kirksey.

69 records · Page 4Linked to original sources
PubMed1975

Influence of dietary lipids on iron and copper levels of rats administered oral contraceptives.

Interrelationships between oral contraceptives and dietary lipids on iron and copper levels in plasma and tissues were investigated in rats. Diets containing either 20% (by weight) safflower oil or hydrogenated coconut oil with and without cholesterol (0.5%) were fed to weanling, female, Wistar-strain rats for a period of 19 weeks. Three types of oral contraceptive agents differing in estrogen/progesterone ratios were administered during weeks 16 through 19 of the experiment. Control rats received the dietary treatment without oral contraceptives. Hemoglobin concentration, hematocrit, red blood cell counts, mean cell hemoglobin and hemoglobin concentration, and mean cell volume values were similar among the various dietary and drug-treatment groups. Elevated levels of copper were found in livers of drug-treated animals fed diets containing cholesterol and safflower oil, whereas levels of copper or iron in spleen and kidney were not influenced by oral contraceptives. Dietary safflower or coconut oil had no influence on levels of iron or copper in plasma. However, iron levels were higher in liver, spleen, and kidneys of rats fed coconut oil compared with those fed safflower oil. Cholesterol-fed rats had reduced levels of iron in plasma and tissues and increased levels of copper in plasma and liver. Iron deficiency in cholesterol-fed rats was indicated by low levels of iron in plasma, liver, spleen, and kidney. In experiment 2, animals were fed the 20% safflower oil diet, with and without sodium glycocholate or cholesterol, to determine whether the apparent malabsorption of iron resulted from sodium glycocholate or cholesterol. Sodium glycocholate resulted in a marked increase in the absorption of iron, whereas cholesterol depressed absorption.

Animals↗
PubMed1975

Effects of different levels of pyridoxine fed during pregnancy superimposed upon growth in the rat.

Effects of pregnancy superimposed upon a rapid phase of growth in the rat on the vitamin B-6 needs during gestation were examined. Rats were fed 1.2, 2.4, 4.8, 9.6, or 19.2 mg pyridoxine-HCl/kg diet from weaning. Some animals from each dietary treatment were mated at 55 (P-55) and 115 (P-115) days of age; others of the same ages served as nonpregnant controls. Analyses were made on day 21 of gestation. Excepting the 1.2-mg diet treatment, maternal weight gains during gestation were greater for P-55 groups compared with gains of the P-115 groups, possibly reflecting maternal growth. Both maternal weight gains and fetal weights were less for the 1.2-mg, P-55 group; otherwise reproductive performance was similar among the groups. On the basis of stimulation of erythrocyte alanine aminotransferase activity by pyridoxal phosphate added in vitro, the needs in all pregnant and nonpregnant groups were met by 2.4 mg pyridoxine/kg diet. However, on the basis of vitamin B-6 saturation of tissues, the pyridoxine needs were 9.6 mg/kg diet for young growing animals and 4.8 mg/kg diet for older animals in which growth had almost ceased. The needs for both young and older pregnant animals possibly exceeded 19.2 mg pyridoxine/kg diet for vitamin B-6 saturation of maternal liver, fetus, and fetal brain. Pregnancy superimposed upon a rapid phase of growth in conjunction with a restricted intake of pyridoxine resulted in low values for most parameters used in the assessments compared with values for animals fed the same vitamin level but mated after growth velocity had diminished.

Age Factors↗
PubMedDate not supplied

A micromethod for determination of plasma pyridoxal phosphate and its use in assessment of storage stability of the vitamer.

A widely used macromethod employing tyrosine apodecarboxylase for measurement of pyridoxal phosphate (PLP) concentration in 0.5-1.0-ml plasma was modified to a microscale utilizing 0.1-ml plasma. Mean PLP levels in 12 plasma samples were 160.6 +/- 32.8 pmol/ml (mean +/- SD) when analyzed by the macromethod, and were not significantly different compared to those obtained by the micromethod (158.4 +/- 28.2 pmol/ml). Results of the two methods were significantly correlated (r = +0.97, p less than 0.001). Plasma PLP concentrations of 11 samples determined by the micromethod (means = 151.8 +/- 30.0 pmol/ml) were similar and significantly correlated (r = +0.95, p less than 0.001) to levels measured in the same samples 1-2 years earlier (means = 145.1 +/- 26.2 pmol/ml). This suggests that plasma PLP content of the samples was stable for up to 2 years of storage when the micromethod was utilized for analysis. The strong significant correlation between macro- and micromethods attests that the micromethod is a reliable alternative to the macromethod. The micromethod is useful in instances where only small samples of plasma are available for measurement of PLP.

Blood Chemical Analysis↗
PubMedDate not supplied

Variation in zinc, calcium, and magnesium concentrations of human milk within a 24-hour period from 1 to 6 months of lactation.

Longitudinal changes in nutrient levels of human milk have been observed with the progression of lactation, but less is known about changes at different feedings during a 24-h period. In this study, calcium, magnesium, and zinc levels were examined in milk obtained from 49 women at every breast feeding during one 24-h period each month for the first 6 months of lactation. Magnesium and zinc concentrations showed significant diurnal variation at each stage of lactation examined, whereas calcium levels were relatively constant. Maximum variations of 7.5, 17, and 48% were observed within a 24-h period in mean levels of calcium, magnesium, and zinc, respectively. Irrespective of variability, zinc and magnesium concentrations in a single milk sample obtained between 10:00 a.m. and 2:00 p.m. were highly correlated with the mean value of samples collected at each feeding during a 24-h period.

Adult↗