PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Vitamins”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1977

[Methods for determination of vitamins by means of high performance liquid chromatography (HPLC). I. Determination of vitamin D in vitamin concentrates, vitamin mixtures and mineral feedstuffs].

A method is described for the determination of vitamin D in vitamin-concentrates, -mixtures, and mineral feedstuffs. After saponification of the sample, vitamin D is extracted and purified on two columns. Vitamin D is separated by HPLC and determined photometrically.

Chromatography, High Pressure Liquid↗
PubMed1977

Vitamin A stimulation of parathyroid hormone: interactions with calcium, hydrocortisone, and vitamin E in bovine parathyroid tissues and effects of vitamin A in man.

The effect of vitamin A, a membrane surface-active agent, on parathyroid hormone secretion was studied in vitro, using bovine parathyroid tissue, and in vivo in man. Parathyroid tissues were incubated with vitamin A (retinol), retinoic acid, and calcium, and with hydrocortisone and vitamin E, agents that antagonize the membrane effects of vitamin A. The stimulation of parathyroid hormone release by vitamin A, 10(-6) to 10(-9) mol/1 in vitro, was dose and time dependent. Retinoic acid did not stimulate secretion. High calcium concentration, hydrocortisone, 10(-5) mol/1 and 10(-6) mol/1, and vitamin E, 10(-5) mol/1, antagonized vitamin A-induced parathyroid hormone secretion. Vitamin A increased the lysosomal cathepsin D activity of parathyroid tissues. In human studies, eleven healthy men received two intramuscular injections of vitamin A palmitate, 25 000 units each, within 24 h. In every subject, serum parathyroid hormone increased after vitamin A administration. Our studies indicate that: (1) vitamin A stimulates parathyroid hormone secretion in vitro, possibly through modification of the cell or secretion granule membrane, or through stimulation of lysosomal proteolytic activity, and (2) vitamin A increases serum parathyroid hormone in vivo, and this effect may be important in clinical states of vitamin A excess.

Adult↗
PubMed1975

Human plasma R-type vitamin B12-binding proteins. II. The role of transcobalamin I, transcobalamin III, and the normal granulocyte vitamin B12-binding protein in the plasma transport of vitamin B12.

The normal human granulocyte vitamin B12-binding protein, transcobalamin I, and transcobalamin III, have been labeled with 125I-labeled N-succinimidyl 3-(4-hydroxyphenyl)propionate and utilized for plasma clearance studies performed with rabbits. Both moieties of 125I-labeled granulocyte vitamin B12-binding protein-[57Co]vitamin B12 were cleared rapidly from the plasma (is less than 90% by 5 min) by the liver. After 30 min, the bulk of the 125I reappeared in the plasma in small molecular weight (less than 1000) form and was rapidly excreted in the urine. After 60 min the bulk of the [57Co]vitamin B12 reappeared in the plasma bound to rabbit transcobalamin II and was subsequently taken up by a variety of tissues. Approximately 15% of the 125I-labeled granulocyte vitamin B12-binding protein-[57Co-a1vitamin B12 was excreted intact into the bile during the period from 10 to 80 min after injection. The hepatic uptake of the protein-vitamin B12 complex was blocked by the prior injection of desialyzed fetuin but not by native fetuin. Similar results were obtained with 125I-labeled transcobalamin III-[57Co]vitamin B12. Approximately 90% of both moieties of 125I-labeled transcobalamin I-[57Co]vitamin B12 had prolonged plasma survivals similar to that of 125I-labeled bovine serum albumin. After treatment with neuraminadase, both moieties of the 125I-labeled transcobalamin I-[57Co]vitamin B12 complex were cleared rapidly from the plasma by the liver in a manner that was indistinguishable from that observed in the case of untreated granulocyte vitamin B12-binding protein and transcobalamin III. These observations indicate that desialyzed transcobalamin I and the native forms of the granulocyte vitamin B12-binding protein and transcobalamin III are cleared from plasma by the mechanism elucidated by Ashwell and Morell (Ashwell, G., and Morell A. G. (1974) Adv. Enzymol. 41, 99-128) that is capable of clearing a wide variety of asialoglycoproteins. These observations have implications concerning the function of the human R-type vitamin B12-binding proteins, the nature of the enterohepatic circulation of vitamin B12, the biological significance of the mechanism described by Ashwell and Morell, and the etiology of the increased plasma concentration of human R-type protein that occurs frequently in chronic myelogenous leukemia and occasionally in hepatocellular carcinoma and other solid tumors.

Animals↗
PubMed1979

Assay for vitamin D2 and vitamin D3 in plasma of dairy cows: changes after massive dosing of vitamin D3.

A sensitive, precise assay for vitamin D in plasma is described. Three to five milliliters of plasma were extracted with methanol:methylene chloride (2:1). The lipid extract was chromatographed on Sephadex LH-20 and then on lipidex-5000 columns. After high pressure liquid chromatography with a reverse phase chromatographic system, vitamin D2 and vitamin D3 were quantitated by ultraviolet absorbance. We used this assay system for monitoring daily changes of vitamin D3 in plasma of two Jersey cows after four intramuscular doses (15 x 10(6) IU) of vitamin D3 administered at weekly intervals. Basal vitamin D in plasma was 3.2 +/- .99 ng/ml with a range of 1.7 to 4.9 ng/ml. Vitamin D3 in plasma remained relatively low (10 to 45 ng/ml) the week after the first vitamin D3 injection. Vitamin D3 was high (130 to 234 ng/ml) after the second, third, and fourth injections. Vitamin D3 decreased steadily to 88 ng/ml by 38 days after the fourth vitamin D3 injection. Phosphorus in plasma increased sharply to a plateau at 9.5 mg/100 ml during the week after the second vitamin D3 injection and returned to normal (4.5 mg/100 ml) at the end of the experiment. Calcium, however, gradually increased to 14.0 mg/100 ml 20 days after the fourth vitamin D3 injection. Both animals remained hypercalcemic (calcium 11.5 mg/100 ml) during the experiment.

Animals↗
PubMed1979

Vitamin B6 nutriture during pregnancy and lactation. I. Vitamin B6 intake, levels of the vitamin in biological fluids, and condition of the infant at birth.

Vitamin B6 nutriture was assessed during pregnancy and lactation to determine possible relationships among vitamin B6 intake, levels of the vitamin in biological fluids and the condition of the infant at birth. Vitamin B6 levels were measured in maternal serum and in urine at 5 and 7 months gestation and at delivery, in cord serum and in milk at 3 and 14 days postpartum. Intake of vitamin B6, less than the Recommended Dietary Allowances (1974) for pregnancy and lactation, 2.5 mg/day, resulted in lower levels of the vitamin in maternal serum at delivery and in cord serum than higher intakes. Mothers whose infants had unsatisfactory Apgar scores at 1 min, (less than 7) had significantly low intakes of vitamin B6 and lower levels of the vitamin in both serum and milk than mothers whose infants had satisfactory scores, (greater than or equal to 7). At 5 months gestation, levels of vitamin B6 in maternal serum were significantly correlated with levels of the vitamin in cord serum and in milk at 14 days postpartum. This stage of gestation precedes the period of rapid growth of the central nervous system of the fetus, and is, therefore, a critical time for the assessment of maternal vitamin B6 nutriture.

Adolescent↗
PubMed1979

Analysis of fat-soluble vitamins. XXIII. High performance liquid chromatographic assay for vitamin D in vitamin D3 and multivitamin preparations.

Vitamin D is determined in preparations containing other fat-soluble vitamins by high performance liquid chromatography (HPLC). The unsaponifiable residue is extracted and separated from interferences by reverse phase chromatography; the fraction corresponding to vitamin D3 is collected and quantitated using normal phase chromatography (amylalcohol-n-hexane as mobile phase) by measuring the vitamin D3 and pre-vitamin D3 peaks at 254 nm. Previtamin D3 content is calculated as vitamin D3 with a conversion factor (determined on the equipment used). Application of the method to vitamin AD3 mixtures in oils gives 98-102% recovery. The reproducibility, using an external standard, is 2-3%, calculated as the coefficient of variation; with an internal standard, the coefficient of variation is 1-1.5%. The method measures potential vitamin D3 content in preparations containing greater than or equal to 200 IU/g in the presence of all known vitamin D3 isomers, vitamin A, and vitamin E.

Cholecalciferol↗
PubMed1979

The effects of vitamin C, vitamin B6, and vitamin B12 supplementation on the breast milk and maternal status of well-nourished women.

The effects of vitamin supplements and/or diet on the levels of vitamin C, vitamin B6, and vitamin B12 in milk and blood of lactating women were determined. At the end of gestation, subjects were divided into two lactation groups: supplemented (10 subjects) and nonsupplemented (seven subjects). Milk samples were collected from 5 to 7 days and 43 to 45 days postpartum. Fasting blood samples were drawn at 8 and 46 days postpartum for vitamin C, B6, and B12 status measurements. Dietary records of all foods consumed by the subject were kept for 4 days at 1 and 6 weeks postpartum. The vitamin B6 level in breast milk of the unsupplemented group of mothers was significantly lower (P less than 0.05) than the supplemented group of women at 5 to 7 days postpartum. Vitamin B12 concentration in milk of nonsupplemented mothers at 43 to 45 days postpartum was significantly lower (P less than 0.05) than the supplemented group of women at 43 to 45 days postpartum. None of the milk values or the maternal blood levels measured in the women was less than published norms for vitamin C, vitamin B6, and vitamin B12.

Ascorbic Acid↗
PubMed1979

Response of plasma levels of vitamin A to a dose of vitamin A as an indicator of hepatic vitamin A reserves in rats.

Rats were fed diets deficient [-A] or sufficient [+A] (3 mg retinol equivalents/kg) in vitamin A, and without [-RA] or with [+RA] (12 mg/kg) retinoic acid supplementation for up to 33 days. Rats with plasma vitamin A levels ranging from 7 to 62 micrograms/dl were studied at intervals during progressive depletion of liver stores of vitamin A (expt. 2) and when liver stores were nearly exhausted (less than 10 micrograms/g) or replete (up to 100 micrograms/g) with vitamin A (expt. 1). A dose of retinyl acetate in corn oil (20 micrograms retinol equivalents) was administered by intubation directly into the stomach. The relative dose response (RDR), expressed as a percentage and defined as the absolute magnitude of the rise in plasma vitamin A levels 5 hours after the dose of retinyl acetate, divided by the plasma level of vitamin A attained after 5 hours, was determined for each rat and correlated over a wide range of vitamin A plasma and liver levels. An RDR above 50% invariably was associated with low plasma levels (10 to 30 micrograms/dl) and low liver stores (less than 10 micrograms/g) of vitamin A, whereas an RDR of less than 40% was associated with plasma levels above 30 micrograms/dl and liver stores ranging from 3 to 100 micrograms/g.

Animals↗
PubMed1978

[Studies on the vitamin requirement and vitamin supply in fattening turkeys. 2. Checking the vitamin supplements to state-approved mixed animal feed for fattening turkeys].

In turkey fattening experiments, the vitamin A, vitamin D3, vitamin B6, vitamin B12, niacine, pantothenic acid, folic acid, biotine and choline chloride additions to mixed feeds for fattening turkeys were checked. The vitamin A requirement of the fattening turkey is met, in all stages of growth, by adding 3,000 I.U./kg feed. For vitamin D3 the necessary supplements are 1,000 and 500 I.U./kg for starter feed and fattening mixes, respectively. The requirements for vitamins B2, B6, B12, niacine, pantothenic acid, folic acid and biotine of the fattening turkey are covered by the respective amounts contained in the ration components. To ensure adequate choline supply (optimum gain, small losses) during the starter period, the addition of 500 mg/kg feed proved necessary. On the basis of the results presented, recommendations are given for requirement norms and mixed feed supplementation that have been fully implemented in the meantime.

Animal Feed↗
PubMed1978

[Tissue thiamine, riboflavin and vitamin B6 in the aged rat. II. Effects of vitamin supplementation in the diet on the excretion of vitamins and its tissue levels].

Nine and twenty-one months old rats fed a balanced diet were given for 5 weeks an extra supplementation in thiamine, riboflavin and vitamin B6. Control animals were given the same diet but without vitamin extra supplementation. Fecal and urinary vitamin excretions were determined during this 5 weeks period. They were shown to be less important in older rats than in younger ones. Influence of aging and vitamin supplementation on the vitamin contents of organs and tissues were studied on these animals: previous results were confirmed [see LECLERC, Ann. nutrit, Aliment., 1976, 30, 10--25]. From these results and others published elsewhere, it is conclused that in older animals there could be an increased intestinal destruction of the above mentionned vitamin although changes in vitamin metabolism can be involved too.

Aging↗
PubMed1977

Analysis of fat-soluble vitamins. XVI. Antirachitic activity of 5,6-trans-vitamin D3 alone and in the presence of 5,6-cis-vitamin D3 resin, using chick bioassays.

Two biological assays were conducted in which the antirachitic activity in chicks of 5,6-trans-vitamin D3 added to feed is compared with that of 5,6-cis-vitamin D3. On the basis of the results obtained it is concluded that the relative potency of the trans isomer is, at the most, 5% and that the antirachitic activity of the trans isomer is not markedly enhanced (an increase to a relative potency of 16%, at the most) if the cis isomer is also included in the diet. The results are not conclusive on the inhibition or lack of inhibition of the antirachitic activity of 5,6-cis-vitamin D3 by the presence of 5,6-trans-vitamin D3 in the feed.

Animal Feed↗
PubMed1978

[Methods for the determination of vitamins by means of HPLC. IV. Determination of vitamin K3 in vitamin premixes and mineral supplements (author's transl)].

A method is described for rapid determination of vitamin K3 (menadione) in vitamin premixes and mineral supplements. The menadione is extracted in the form of the bisulphite compound. After conversion into menadione the vitamin is taken up in n-hexane and is determined by HPLC without further clean-up.

Chromatography, High Pressure Liquid↗
PubMed1979

Analysis of fat-soluble vitamins. XXI. High pressure liquid chromatographic assay methods for vitamin D in vitamin D concentrates.

Two high pressure liquid chromatographic methods, a straight and a reverse phase system, were developed and compared with the official (chemical) AOAC method for vitamin D concentrates. The effects of the systematic error and the reproducibility of using an internal or external standard were studied, as well as the effect of using peak height or peak height X retention time for calculating the potential vitamin D content. A method is given for determining the conversion factor to calculate previtamin D as vitamin D. Based on the results of the comparison, the following conditions were selected for collaborative study: straight phase, amyl alcohol-hexane mobile phase, external standard, and calculation of potency by peak height.

Cholecalciferol↗
PubMed1975

Influence of excess vitamin E on vitamin A toxicity in rats.

Male Holtzman rats (78 g) were fed semipurified 16% protein diets for 8 weeks using a food grade soy protein concentrate as the protein source. The basal diet (A) contained added DL-methionine (0.26%) and adequate amounts of vitamins A (14,535 IU/kg as retinyl acetate) and E (60 IU/kg as DL-alpha-tocopheryl acetate) and all other required nutrients. Experimental diets included: (B) basal plus 600 IU of vitamin E/kg; (C) basal plus 6,000 IU of vitamin E/kg; (D) basal plus 2.9 X 10(6) IU of vitamin A/kg; (E) basal plus 2.9 X 10(6) IU of vitamin A plus 600 IU of vitamin E/kg; and (F) basal plus 2.9 X 10(6) IU of vitamin A plus 6,000 IU of vitamin E/kg. Both vitamin A and vitamin E had a significant (P less than 0.05) effect on growth. There was an increase in growth with vitamin E intake and a decrease in growth with vitamin A intake. The net result of these two effects was that the groups fed both vitamins tended to be quite close in mean values to the group fed only the basal diet. Vitamin A significantly (P less than 0.05) increased relative weights of spleen and testes; vitamin E reduced that effect. Vitamin E also significantly (P less than 0.05) reduced relative adrenal weight whereas vitamin A significantly increased it. The two effects tend to cancel each other in the sense that the group fed both vitamins had an average relative adrenal weight quite close to that of the group fed only the basal diet. However, vitamin A still had an effect even when 6,000 IU of vitamin E was fed. The interaction effect of the two vitamins was significant (P less than 0.05) for plasma total protein and liver vitamin A. There was an increase in liver vitamin A with increasing levels of vitamin E in the diet. Blood urea nitrogen and plasma cholesterol were unchanged. A significant interaction of vitamins A and E was found to effect plasma total protein, liver vitamin A, and relative weight of spleen and testes.

Animals↗