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PubMed2006

Ham's F-10 medium and Ham's F-10 medium plus vitamin E have protective effect against oxidative stress in human semen.

OBJECTIVES: To investigate possible protective effects of vitamin E and Ham's F-10 medium (HF-10) on lipid peroxidation, apoptosis, motility, and vitality of spermatozoa. METHODS: Normozoospermic semen samples were obtained from 35 volunteers. Normal saline solution, HF-10 only, or HF-10 with vitamin E were added to split semen samples (control, group 1, and group 2, respectively). Sperm motility and vitality were evaluated at the end of 1, 2, and 24 hours. Superoxide dismutase, catalase, and malondialdehyde levels were assessed at the end of the first hour. Flow cytometric DNA analysis was performed at the end of 24 hours. RESULTS: Superoxide dismutase, sperm motility, and vitality were not different among the groups. The catalase values decreased in group 1, but not in group 2. Malondialdehyde values in supernatants decreased in group 2 and apoptosis of spermatozoa decreased in groups 1 and 2. CONCLUSIONS: Our data suggest that vitamin E and HF-10 protect against the reactive oxygen species-mediated damage on spermatozoa.

Adult↗
PubMed1986

New disorder of vitamin B12 metabolism (cobalamin F) presenting as methylmalonic aciduria.

An infant with vitamin B12-responsive methylmalonic aciduria and no homocystinuria or megaloblastic anemia presented with stomatitis, glossitis, convulsions, and developmental delay. Cultured fibroblasts showed defective incorporation of both [14C]5-methyltetrahydrofolate and [14C]propionate into protein by whole cells and a decrease of methionine synthase activity in cell extracts. Despite excessive incorporation of [57Co]cyano-B12 by fibroblasts from the patient, free vitamin B12 was unable to efflux from lysosomes, and, therefore, synthesis of both adenosyl-B12 and methyl-B12 was impaired.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2005

Effects of feeding vitamin A and lactoferrin on epithelium of lymphoid tissues of intestine of neonatal calves.

Circulating levels of vitamin A (retinol) and lactoferrin (Lf) are low in calves at birth. Bovine colostrum contains relatively high amounts of vitamin A and Lf, and both substances are intestinally absorbed by neonatal calves. There is evidence that these compounds interact with insulin-like growth factor binding proteins and thus influence the status and effects of insulin-like growth factor. The hypothesis was therefore tested that vitamin A and Lf influence epithelial growth, development, and absorptive capacity of the small and large intestine and modulate intestinal immune tissues (Peyer's patches; PP). Four groups of calves (n = 7 per group) were fed a milk-based formula with or without vitamin A and (or) Lf. Group F received formula (F) only; group F(A) was fed F supplemented with vitamin A; group F(L) was fed F supplemented with Lf, and group F(AL) received F plus vitamin A plus Lf. An additional group of calves (group C; n = 7) served as positive control and was fed colostrum (C) from pooled milk obtained on d 1, 2, and 3 of lactation. Amounts of nutritive components in formula and colostrum were similar. Blood samples were taken to measure vitamin A and Lf, and plasma xylose (added on d 4 to feeds) was measured postprandially for 8 h as a marker of intestinal absorptive capacity. Plasma vitamin A was low at birth and further decreased in groups F and F(L), but increased in groups F(A), F(AL), and C. Plasma Lf was low at birth and transiently increased up to 4 h after the first meal in group C. Xylose absorption was higher in group C than in other groups. Incorporation of 5-bromo-2'-deoxyuridine into DNA (as a measure of cell proliferation rate) was enhanced in intestinal crypts in groups F and F(L) at all intestinal sites. Ileum villus heights of groups F and F(L) were smaller than of groups F(A) and F(AL). Villus height to crypt depth ratios were smaller in F-fed groups (especially in groups F and F(L)) than in C-fed calves in the duodenum and jejunum. Incorporation of 5-bromo-2'-deoxyuridine into colon crypt cells of group F was greater than in groups F(L) and F(A). Sizes of follicles of PP in the ileum were greater in group F(A) than in group F. In the ileum, vitamin A and Lf tended to interact with PP size. In conclusion, feed supplementation of vitamin A and Lf influenced growth of the ileum and colon. Interactions were observed between vitamin A and Lf on epithelial cell maturation, villus growth, and size of follicles in PP of neonatal calves.

Analysis of Variance↗
PubMed1991

Vitamin B12 metabolism in a photosynthesizing green alga, Chlamydomonas reinhardtii.

To elucidate vitamin B12 (cobalamin) metabolism in green algae, Chlamydomonas reinhardtii was labeled with radioactive cobalamin for 4 days. The Chlamydomonas cells did not require cobalamin for growth, but nevertheless took up and accumulated exogenous cobalamin. The level of the accumulated cobalamin reached a maximum (about 20 fmol/10(6) cells) at day 1 of the cell growth. The cobalamin accumulated by the 4-day cells was partly converted to the coenzymes (5'-deoxyadenosylcobalamin, 20.7% and methylcobalamin, 4.8%). The cells contained NADH- and NADPH-linked aquacobalamin reductases (35.9 and 31.5 nmol/min per mg protein, respectively) involved in the synthesis of the coenzymes. Most of the accumulated cobalamin was associated with two heat-labile macromolecules; the coenzymes synthesized were recovered in the macromolecular fraction with a molecular weight of 230,000, while non-coenzyme forms (cyanocobalamin and hydroxocobalamin) predominated in that with a molecular weight of 40,000. Evidence for de novo biosynthesis of cobalamin was also obtained in the alga, indicating that it has both ability to synthesize cobalamin and take up the exogenous vitamin.

Chlamydomonas↗
PubMed1987

Effect of an infection on vitamin A status of children as measured by the relative dose response (RDR).

The effect of an infective episode of chickenpox on the vitamin A status of preschool-aged children was evaluated by use of the relative dose response (RDR) test. Status was determined before and 30, 120, and 180 d after administration of a single oral high-dosage (200,000 IU) supplement of vitamin A. No differences in mean blood levels of retinol or percentage of children showing a positive RDR were apparent until after the infective episode that occurred approximately 90 d after dosing. At 180 d postsupplementation, 74% of children who had been infected tested positive by the RDR, indicative of an inadequate liver reserve of vitamin A, in contrast to only 10% who had not been infected. Paired RDR observations at 0 and 180 d postsupplementation confirmed that the infective episode caused an accelerated depletion of liver reserves of vitamin A.

Chickenpox↗
PubMed1999

The effect of vitamin A on epithelial integrity.

Vitamin A is the generic term for a variety of fat-soluble substances including retinol, retinyl palmitate and the provitamin A carotenoids such as all-trans-beta-carotene. Vitamin A is commonly known as the anti-infective vitamin and has an essential role in vision and cellular differentiation, the latter providing a unique core mechanism helping to explain the influence of vitamin A on epithelial barriers. Alterations in the epithelial lining of vital organs occur early in deficiency, suggesting a potentially important role for the barrier function. Vitamin A deficiency (VAD) is most commonly recognized in the eye. The conjunctival-impression cytology test detects the presence of larger irregular keratinized cells and the absence of mucous-secreting goblet cells, indicative of VAD. The method is simple, quick and sensitive in populations where VAD is present. In the respiratory tract, observational studies all show an association with VAD, although vitamin A supplementation studies appear to have little effect on respiratory disease. Organ-specific targeting may improve success rates. The dual-sugar intestinal-permeability test allows the effect of vitamin A supplementation to be monitored on the gastrointestinal tract. Two vitamin A supplementation studies were carried out recently in Orissa State, India. Healthy infants of weaning age were administered orally eight weekly doses of 5.0 mg retinol equivalents and hospitalized infants received one large oral dose 60 mg retinol equivalents in the form of retinyl palmitate. Improvements in gut integrity and haematological status were observed in both studies. In summary, the response of the eye to vitamin A supplementation is well established; the present review highlights some of the more recent observations examining the effects of vitamin A.

Dietary Supplements↗
PubMed1993

Vitamin A absorption in children with ascariasis.

The effect of Ascaris lumbricoides infection on retinol absorption was investigated in young children from a slum area of Dhaka City, Bangladesh. Twenty-four children aged 4-10 years were screened and in every case eggs of either Ascaris, Trichuris or hookworm were isolated from the stool. The average serum retinol was 0.91 (SD 0.35) mumol/l and sixteen children had levels below 1.05 mumol/l. This compared with a serum retinol concentration of 1.70 (SD 0.52) mumol/l in five reference children from a more privileged social background. An oral dose of retinol (41.8 mumol) was given to ten children in whom the concentration of Ascaris eggs in the stool varied. Less than 1% of the supplement could be recovered in the stools collected over the following 48 h. Ascaris worms were isolated from the stool and assayed for retinol content. In no case was retinol detected in the worms. These findings do not support the contention that infection with Ascaris predisposes to malabsorption of vitamin A.

Animals↗
PubMed1987

Vitamin A status in the grey seal (Halichoerus grypus) on Sable Island.

Vitamin A and beta-carotene concentrations in serum, liver and blubber fat were investigated in 65 grey seals of different age and sex in the pupping colony on Sable Island, Canada to determine the vitamin A status. In none of the investigated samples could beta-carotene be detected. There were no differences in the concentration of vitamin A in serum, liver and blubber between male (213 micrograms/l, 376 micrograms/g, 22 micrograms/g respectively) and female (205 micrograms/l, 319 micrograms/g, 19 micrograms/g respectively) juveniles. In adult males concentrations of vitamin A in serum, liver and blubber were higher (260 micrograms/l, 503 micrograms/g, 34 micrograms/g respectively) than in juveniles indicating an age dependent increase of vitamin A in liver and blubber. Contrary to this in lactating females concentrations of vitamin A in serum, liver and blubber were significantly different than in the other animals. While the level of vitamin A in serum and blubber was two times higher with 413 micrograms/1 and 62 micrograms/g respectively, the concentration of vitamin A in liver was much lower (265 micrograms/g) compared to juveniles and adult males. It is possible that the intensified lipid metabolism during lactation, necessary to match the energy requirements of the rapidly growing pup, causes these extreme differences in vitamin A concentrations in serum, liver and blubber of lactating females compared to juveniles and adult males. Due to high concentration of vitamin A in blubber and the high proportion in blubber to total body weight, the blubber represents approximately 40% of total body reserves of vitamin A.

Adipose Tissue↗