Serum concentrations of 25-hydroxy vitamin D in Europeans and Asians after oral vitamin D3.

Serum concentrations of 25-hydroxy vitamin D (25-OHD3) were measured in seven Asians of Indian extraction and eight Europeans before and at intervals after taking 1 mg vitamin D3 by mouth. In all subjects the concentrations rose in the 24 hours after ingestion. There was little change over the next nine days in the concentrations in the Europeans but those in the Asians continued to rise until about day 10. Subsequent rates of fall in 25-OHD3 were similar in the two groups. Our observations suggest that the low serum concentrations of 25-OHD3 found in Asians are not caused by either impaired intestinal absorption of vitamin D or rapid clearance of 25-ODH3 from the plasma.     

Changes in blood viscosity after administration of vitamin E in the rabbit

Vitamin E is an essential factor to maintain biological membranes stability and its lack may affect membranes structures and reduce erythrocyte life-span. Vitamin E also play a role in the maintenance of a normal platelet aggregation. A.A. studied the effects of a ten days supply of d-1-alpha tocopherol acetate (50 mg/Kg/die) on blood viscosity in 8 rabbits. Results obtained show a significant reduction of blood viscosity on 6th day of treatment in the male rabbits and a progressive reduction of values from the 6th till the 10th day in female rabbits. The most significant decrease of blood viscosity were obtained at the lowest shear-rates, due to an increased red cells deformability to the antioxidative action of vitamin E on the erythrocytes membrane and to a reduced red cells aggregation. Such modifications on the red blood cells caratheristics can be determined by vitamin E through different mechanism: a) inhibiting red cell membrane's polyunsaturable fatty acids oxidation; b) by removal of abnormal lipids from erythrocyte membrane; c) physical and chemical stabilization of membrane's surface.     

Methylmalonic acid and coenzyme A concentrations in the livers of pair-fed vitamin B12-deficient and vitamin B12-treated sheep

The concentrations of CoA in the livers of severely vitamin B(12)-deficient ewes were about 2.6 times those in pair-fed animals treated with vitamin B(12). When the feeding rates of the pair-fed animals were closely similar, the concentrations of methylmalonic acid in deficient livers were about twice those in vitamin B(12)-sufficient livers. The molar concentrations of CoA present were more than three times those of methylmalonic acid in both deficient and treated animals, and it is concluded that the elevated concentrations of CoA in the deficient livers were not primarily due to accumulation of methylmalonyl-CoA.     

Dietary zinc deficiency decreases plasma concentrations of vitamin E

Experiments were conducted to examine the effects of dietary zinc (Zn) upon plasma vitamin E (E) concentrations to test the hypothesis that there may be a significant dietary interaction between these two nutrients. Weanling female Sprague-Dawley rats were fed diets that were (i) Zn-deficient (less than 0.9 micrograms Zn/g diet) ad libitum; (ii) Zn-adequate (50.9 micrograms Zn/g diet), pair-fed to the Zn-deficient group; and (iii) Zn-adequate (50.9 micrograms Zn/g diet) ad libitum. Plasma E in Zn-deficient animals (4.02 +/- 1.20 micrograms/ml) was significantly reduced (P less than or equal to 0.05) compared with results in both Zn-adequate pair-fed (9.21 +/- 0.70 micrograms/ml) and Zn-adequate ad libitum-fed (9.47 +/- 0.90 micrograms/ml) animals. Zn deficiency in this model system also resulted in significant (P less than or equal to 0.05) reductions in femur and plasma Zn concentrations as well as in plasma retinol, plasma triglyceride, and plasma cholesterol concentrations. Plasma albumin and total plasma protein concentrations were normal in Zn-deficient animals. With dietary Zn deficiency, the decrease in plasma E appeared to be out of proportion to associated decreases in plasma triglyceride and plasma cholesterol concentrations. Since E is associated with plasma lipoproteins, these data suggest that lipid and/or E malabsorption may be a consequence of Zn deficiency. In response to increased dietary intake of E, increments of plasma E were lower in Zn-depleted than in Zn-adequate, pair-fed animals. These findings suggest that dietary Zn deficiency possibly may increase the nutritional requirement for E necessary to maintain adequate plasma concentrations.     

Serum concentrations of reproductive hormones after administration of various anesthetics to immature and young adult male rats

Immature and young adult male rats were either castrated or unoperated. One of seven anesthetic agents (Rompun, Bio-Tal, Thiopental, pentobarbital, ketamine, halothane, or ether) was administered. When the animals were clearly anesthetized, they were decapitated. Control rats were decapitated without anesthesia. Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, testosterone, and androstenedione were determined by radioimmunoassay. None of the anesthetics was clearly suitable for study of all these hormones. Most would be suitable for acute LH studies. Ketamine and halothane appeared inappropriate for FSH studies in immature rats. Pentobarbital, Rompun, and ether caused increases in serum prolactin. Most of the agents appeared to cause a reduction in serum testosterone in intact rats but an increase in castrated animals, suggesting an inhibition of testicular androgen secretion and a stimulation of adrenal androgen secretion.     

Protective role of supplemental vitamin E and selenium on lipid peroxidation, vitamin E, vitamin A, and some mineral concentrations of Japanese quails reared under heat stress

This study was conducted to determine the effects of vitamin E and selenium (Se) on lipid peroxidation (MDA), serum and liver concentration of antioxidant vitamins, and some minerals of Japanese quails reared under heat stress (34°C). One hundred twenty 10-d-old Japanese qualis (60 males, 60 females) were randomly assigned to 4 treatment groups, 3 replicates of 10 birds each. The experiment was designed in a 2×2 factorial arrangement using two levels of vitamin E (125 and 250 mg/kg of diet) and two levels of selenium (0.1 and 0.2 mg/kg of diet). Greater dietary vitamin E and selenium inclusions resulted in a greater (p=0.001) serum vitamin E and vitamin A, but lower (p=0.001) MDA concentrations. Liver vitamin E and vitamin A concentrations increased (p=0.001) and MDA concentrations decreased (p=0.001) when both dietary vitamin E and selenium increased. No interactions between vitamin E and selenium were detected (p≥0.11) for any parameters. Increasing both dietary vitamin E and selenium caused an increase in serum concentrations of Fe and Zn (p=0.001), but a decrease in serum concentration of Cu (p=0.001). Results of the present study showed that dietary vitamin E and selenium have synergistic effects and that supplementing a combination of dietary vitamin E (250 mg/kg of diet) and selenium (0.2 mg/kg of diet) offers a good management practice to reduce heat stress-related depression in performance of Japanese quails.     

Effect of simultaneous administration of vitamin C, L-cysteine and vitamin E on the melanogenesis

The effect of simultaneous administration of vitamin C (ascorbic acid), L-cystein (Cys) and vitamin E (tocopherol) on the melanogenesis in vivo and in vitro was studied. Forty-eight brownish guinea pigs were divided into 4 groups as follows: VC group, VC+Cys group, VC+Cys+VE group and control group. They were given these vitamins by oral administration every day. UV-B exposure (0.384 J/cm2) on their depleted back skin was done at the day 8, 10, 12, 15 17 and 19. After UV-B irradiation, vitamins were administrated further 3 weeks. The luminosity score was measured using a Color Reader CR-11 (Minolta, Co) and the numbers of DOPA-positive melanocytes of their back skin were counted. B16 melanoma cells were incubated with VC, N-acetyl cystein (NAC) and VE. After 4 days of incubation, cells were harvested. The melanin contents and the tyrosinase activities in cells were measured. The luminosity score in the VC+VE+Cys group was higher than those in the other groups. The numbers of DOPA-positive melanocytes of guinea pigs treated with VC, VE and Cys were significantly decreased compared with those in VC group. In B16 melanoma cells, simultaneous treatment of VC, VE and NAC was the most effective to decrease the melanin contents and to inhibit tyrosinase activity.     

Serum concentrations of vitamin D-binding protein (Group-specific component) in cystic fibrosis

Summary Vitamin D-binding protein (DBP) concentrations were determined in the sera of 90 cystic fibrosis homozygotes, 57 obligate heterozygotes, and 46 normal controls. Very significantly lower mean concentrations were found in the sera of CF homozygotes compared with both heterozygotes and controls (P<0.01, Wilcoxon Rank Sums Test). Subdivision of the samples by Gc phenotype showed that this relationship held true both in the Gc1 and Gc2-1 phenotypes. The small sample size of the Gc2 genotype makes the significance levels of limited usefulness, but the pattern of variation of DBP levels among CF homozygotes, heterozygotes, and controls was consistent with that observed for the Gc1 and Gc2-1 classes. Haptoglobin levels showed high coefficients of variation when compared among CF homozygotes, obligate heterozygotes, and controls, presumably because of nonspecific elevation in the acute-phase response. Alpha₂-macroglobulin levels were, if anything, slightly elevated in CF homozygotes compared with controls, while albumin levels showed no significant mean differences between these groups. Since the DBP concentration does not vary with age nor with levels of vitamin D and its metabolites, we interpret our results to mean that DBP levels are specifically decreased in cystic fibrosis, perhaps as the result of impaired glycosylation of the protein.A preliminary report of this work appeared in the Proceedings of the 8th International Congress on Cystic Fibrosis.