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At least 1,135 records · Page 63Linked to original sources
PubMed2002

Novel effect of vitamin K(1) (phylloquinone) and vitamin K(2) (menaquinone) on promoting nerve growth factor-mediated neurite outgrowth from PC12D cells.

The nerve growth factor (NGF)-potentiating effect of K vitamins on PC12D cells was investigated. Treatment of PC12D cells with vitamin K(1) or K(2) in the presence of NGF significantly enhanced the proportion of neurite-bearing cells and acetylcholinesterase activity compared with NGF treatment alone. The K vitamins-enhanced neurite outgrowth on PC12D cells was completely blocked by a protein kinase A (PKA) inhibitor or mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059, whereas a protein kinase C inhibitor chelerythrine chloride did not significantly inhibit the enhancing effect of the K vitamins. These results suggest that the K vitamins enhance neurite outgrowth via the activation of PKA and MAPK-mediated signaling pathways in PC12D cells.

Animals↗
PubMedDate not supplied

Ligands for the vitamin D endocrine system: different shapes function as agonists and antagonists for genomic and rapid response receptors or as a ligand for the plasma vitamin D binding protein.

The integrated operation of the vitamin D endocrine system which produces the steroid hormone 1alpha,25(OH)(2)-vitamin D(3) (1alpha,25(OH)(2)D(3)) is dependent on four classes of proteins each of which have inherent in their secondary and tertiary structure a ligand binding domain (LBD) that allows the stereospecific binding of 1alpha,25(OH)(2)D(3) or related analogs as a substrate or ligand. These LBDs include: (a) the cytochrome P450 enzymes in the liver, kidney, and other tissues which metabolize vitamin D(3) into biologically active metabolites; (b) the plasma vitamin D binding protein (DBP) which selectively transports these hydrophobic molecules to the various target organs of the vitamin D endocrine system; (c) the nuclear receptor VDR(nuc) that is involved in regulation of gene transcription in over 30 cell types which possess this receptor; and (d) a plasma membrane receptor, VDR(mem), that is involved in initiation of signal transduction pathways which generate rapid biological responses. This article reviews the evidence that supports the conclusions that the LBD of the DBP, VDR(mem) and VDR(nuc) each select as their preferred ligand a unique shape of the conformationally flexible 1alpha,25(OH)(2)D(3). Two critical aspects of the conformationally flexible 1alpha,25(OH)(2)D(3) molecule which defines the optimum ligand shape are (a) the orientation and relative rigidity of the flexible 8 carbon side chain and (b) the position of the A ring in relation to the C/D rings as determined by the extent of rotation around the 6,7 single carbon bond of the seco B ring. These conclusions are based on consideration of structure-function studies of over 300 analogs of 1alpha,25(OH)(2)D(3), of these, 22 analogs are highlighted in this presentation.

Animals↗
PubMed1980

Vitamin K dependent carboxylase: subcellular location of the carboxylase and enzymes involved in vitamin K metabolism in rat liver.

Vitamin K dependent carboxylation of an exogenous peptide substrate and endogenous protein substrates, vitamin K epoxidation, and reduction of vitamin K epoxide were measured in subcellular fractions from rat liver. The rough microsomal fraction was highly enriched in all four activities; lower levels were found in smooth microsomes. Mitochondria, nuclei, and cytosol had negligible activities. The addition of 0.2% Triton X-100 to intact microsomes resulted in a 10-20-fold stimulation in carboxylation of a peptide substrate. This marked latency suggests that the active site of the carboxylase may be accessible only from the lumen of the microsomal membrane. A lumen-facing orientation of the carboxylase was also supported by its inaccessibility to trypsin in intact microsomes contrasted with marked inhibition by trypsin in detergent-permeabilized microsomes. Vitamin K epoxidase and epoxide reductase activities were also inhibited by trypsin much more effectively in permeabilized than in intact microsomes, although some degree of exposure at the cytosolic surface was also indicated. These data suggest that carboxylation is an early event in prothrombin synthesis occurring primarily on the lumen side of the rough endoplasmic reticulum membrane. The location of the vitamin K epoxidation-reduction cycle enzymes is consistent with their possible role in the carboxylation reaction.

Animals↗
PubMed2001

On-line supercritical fluid extraction/enzymatic hydrolysis of vitamin a esters: a new simplified approach for the determination of vitamins a and e in food.

An on-line supercritical fluid extraction (SFE)/enzymatic hydrolysis procedure using immobilized lipase has been developed for the determination of vitamin A in dairy and meat products. Several lipases were tried, of which Novozyme 435 (Candida antarctica type B) showed the highest activity toward retinyl palmitate. There was no observed activity with alpha-tocopheryl acetate. When pressure, temperature, modifiers, flow rate, extraction time, and water content were varied, high vitamin A recovery was obtained in milk powder. Collected extracts were analyzed by reversed-phase high-performance liquid chromatography with ultraviolet and fluorescence detection without additional sample cleanup. The procedure gave reliable values of vitamin A as well as of vitamin E in other food items such as infant formula, minced pork and beef meat, and low- and high-fat liver paste. The described method is faster and more automated than conventional methods based on liquid-liquid extraction, or SFE using off-line saponification, for vitamin A and E determination. Results obtained with the new method did not differ significantly from those obtained with the other two methods mentioned above.

Animals↗
PubMed1990

Substituted vitamin K epoxide analogues. New competitive inhibitors and substrates of vitamin K1 epoxide reductase.

2- and 3-substituted vitamin K 2,3-epoxide analogues were synthesized and tested as inactivators, inhibitors, and substrates for beef liver microsomal vitamin K1 epoxide reductase. 2-(X)-3-phytyl-1,4-naphthoquinone 2,3-epoxides, where X is hydroxymethyl, chloromethyl, fluoromethyl, difluoromethyl, and formyl were all competitive inhibitors, but none was an inactivator. Only the 2-hydroxymethyl analogue was reduced to a quinone that was stable enough under the conditions of the experiment to be detected. Vitamin K1 epoxide analogues with modified phytyl chains (1'-hydroxy, 3'-fluoro with isomerized double bond, 1'-hydroxy and 1'-fluoro with saturated double bond, and the corresponding unsubstituted chains) were synthesized. All of the analogues were competitive inhibitors of vitamin K1 epoxide reductase. The nonfluorinated analogues also were shown to be substrates, being reduced to the corresponding quinone without enzyme inactivation. At least one other enzyme besides vitamin K1 epoxide reductase in beef liver microsomes also metabolizes all of these analogues.

Animals↗
PubMed1997

Vitamin A and vitamin E statuses of preschool children of socioeconomically disadvantaged families living in the midwestern United States.

OBJECTIVE: To determine the vitamin A and vitamin E statuses of socioeconomically disadvantaged preschool American children. DESIGN: Cross-sectional study of preschool children from socioeconomically disadvantaged families. SETTING: Central Iowa, USA. SUBJECTS: A group of 77 apparently healthy children was studied with the following characteristics: 5 mo-6 y; 37 males, 40 females, 56 non-Hispanic Caucasians, 3 Hispanics, 18 Afro-Americans. METHODS: Modified relative dose response (MRDR) test for vitamin A status assessment; serum retinol, alpha-tocopherol, cholesterol, and carotenoids; weight for age. RESULTS: Although the mean weight for age was the 53rd percentile of the NCHS standard, a significant number of children (P = 0.006, chi(2)) were either markedly underweight or overweight. Ratios of 3,4-didehydroretinol to retinol (DR/R) were > 0.030, in 32% of the children. Mean serum retinol, alpha-tocopherol and cholesterol (+/- s.d.) were 1.09 +/- 0.23 microM/L, 16.8 +/- 6.3 microM/L and 4.01 +/- 0.8 microM/L. Three children (3.9%) showed a serum retinol value < 0.7 microM/L. One child with a serum retinol value < 0.7 microM/L and one additional child showed a ratio of alpha-tocopherol to cholesterol < 1.44 mumol/mmol. The mean alpha-tocopherol to cholesterol ratio for the group (4.31 +/- 1.71 mumol/mmol), however, was satisfactory. The only significant (P < or = 0.05) age-related changes were an increase in the serum cholesterol (P = 0.005) and decrease in the alpha-tocopherol to cholesterol ratio (P < 0.005) between the 0-2 y and the 2-4 y groups. Serum cholesterol (P = 0.0165, two-tailed) and lycopene (P = 0.004) concentrations of Afro-Americans were significantly higher than those of Caucasians. Median serum concentrations of alpha-carotene and beta-carotene were lower and, of lycopene higher than those found in children studied in a national survey. Serum carotenoid concentrations generally increased with age. CONCLUSIONS: Larger percentages of underweight and overweight children and a significant degree (32%) of inadequate vitamin A status were found in this group of socioeconomically disadvantaged children. Afro-Americans showed higher serum cholesterol and lycopene concentrations than did Caucasians, but otherwise were nutritionally similar. Age-related changes were small. Of nutritional parameters considered, the vitamin A status of socioeconomically disadvantaged segments of our population clearly needs attention.

Black People↗
PubMed2005

Estimation of intake and status of vitamin A, vitamin E and folate in older European adults: the ZENITH.

OBJECTIVE: To report selected dietary intake and vitamin status at baseline of volunteers participating in the ZENITH study and the correlation of vitamin status with zinc. DESIGN: A multicentre prospective intervention study employing a randomised double-blind design. SETTING: Clermont-Ferrand, Theix (France), Coleraine (Northern Ireland), Grenoble (France), Rome (Italy). PARTICIPANTS: In total, 387 healthy middle-aged (55-70 y) and older (70-87 y) men and women participated in the study. METHODS: Dietary intake was assessed by means of a validated 4-d recall record. Fasting blood samples were simultaneously analysed for retinol and alpha-tocopherol by the HLPC method. Erythrocyte folates were measured by a competitive immunoassay with direct chemiluminescence detection on an automatised immunoanalyser. RESULTS: In all centres, men had a significantly (P < 0.0001) higher mean nutrient intake than women. Comparison between age-groups showed that older individuals had significantly lower intakes of macro- and selected micronutrients than middle-aged subjects (P < 0.0001). A high fat intake (from 36 to 40% of total energy) was observed in all examined groups. In relation to biochemical measures of vitamin status, all parameters were above their respective cut-off values for normality and, thus, none of the subjects had biochemical evidence of deficiency of these selected vitamins. A moderate correlation was found with plasma vitamin A and serum zinc (r = 0.12, P < 0.05) or red blood cell zinc (r = 0.12, P < 0.01) and with erythrocyte folates and red blood cell zinc (r = 0.11, P < 0.05). CONCLUSIONS: There were only moderate differences in the nutrient intake of the ZENITH study volunteers among the four European centres. Their biochemical status for retinol, alpha-tocopherol and folate appeared adequate.

Age Factors↗
PubMed2003

Vitamin A capsule distribution to control vitamin A deficiency in Indonesia: effect of supplementation in pre-school children and compliance with the programme.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a widespread vitamin A supplementation programme and to describe indicators of compliance with the programme in Indonesia. DESIGN: Prospective cohort study. Children's anthropometric data were gathered at baseline (June 2000) and 4 months later (2 months after supplementation in August 2000). Serum retinol, haemoglobin, ferritin, alpha1-acid glycoprotein and C-reactive protein were measured at baseline and at follow-up. Caregivers of the children were interviewed using a questionnaire. SETTING: Semi-urban and rural areas of Semarang district, Central Java, Indonesia. SUBJECTS: Children aged 1-5 years. RESULTS: After the supplementation, the proportion of children with a low concentration of retinol decreased in recipients from 18.8 to 14.5%. However, in non-recipients, the prevalence of vitamin A deficiency increased from 31.9 to 37.5%, this prevalence being significantly higher than in recipients. A significant decrease occurred in the proportion of recipients with low ferritin (26.5 to 16.2%) and haemoglobin (25.7 to 15.3%), whereas the proportions did not show a significant change after supplementation for non-recipients. Modest linear growth was detected in recipients after supplementation but there was no effect on ponderal growth. The coverage rate of the supplementation in the study areas was 60%. There was an association between compliance of the caregivers and their knowledge about the potential benefit of vitamin A supplementation, the place where sick children were taken and age of the children. CONCLUSIONS: The vitamin A supplementation programme marginally decreased the proportion of vitamin A deficiency and had a marginal effect on the nutritional status of recipients. More than one micronutrient intervention is needed to increase the effectiveness of the supplementation programme. To increase compliance and coverage in the supplementation programme, nutrition communication and private healthcare practices need to be included in the programme.

Body Height↗
PubMed1955

The minimum vitamin requirements of the L and HeLa cells in tissue culture, the production of specific vitamin deficiencies, and their cure.

SEVEN VITAMINS HAVE TO DATE PROVED ESSENTIAL FOR THE SURVIVAL AND MULTIPLICATION OF A MOUSE FIBROBLAST (STRAIN L) AND A HUMAN CARCINOMA CELL (STRAIN HELA) IN TISSUE CULTURE: choline, folic acid, nicotinamide, pantothenic acid, pyridoxal, riboflavin, and thiamin. It was necessary to cultivate the cells for 5 to 15 days in a medium lacking the specific vitamin before the deficiency became apparent in the cessation of multiplication and the development of specific cytopathogenic effects. In their early stages these changes could be reversed by the addition of the missing vitamin, an in vitro, "cure" of a vitamin deficiency. The maximally effective concentrations were in the range 10(7) to 10(8) gm. per ml. The probability that additional vitamins not demonstrably essential under the conditions of the present experiments are nevertheless required for survival and growth is discussed in the text.

Animals↗
PubMed1978

Rehabilitating effect of vitamin E therapy on the ultrastructural changes in skeletal muscles of vitamin E-deficient rabbits.

Ultrastructural repair of the morphological damages produced in nutritional muscular dystrophy was studied by refeeding dystrophic rabbits with vitamin E. Weanling (1.2 kg body weight) rabbits were fed a vitamin E-deficient diet for 24 days. Half of this group was then sacrificed and the remainder was given an initial oral dose of 50 mg of DL-alpha-tocopherol acetate and a vitamin E supplemented diet for 28 days. Control animals were fed a vitamin E supplemented diet with 50 mg of DL-alpha-tocopherol acetate per kilogram of diet. Abnormalities of dystrophic muscles included streaming Z-disk, degenerated mitochondria, fragmented sacroplasmic reticulum and development and aggregation of myelin figures. The effect of vitamin E therapy resulted in significant repair of the dystrophic muscle. Small localized sections of rehabilitated muscle revealed abnormal mitochondria and residual myelin figures.

Animals↗
PubMed1994

A 210-mumol dose of vitamin A provides more prolonged impact on vitamin A status than 105 mumol among preschool children.

A randomized controlled clinical trial was conducted to determine the relative protection afforded by two large doses of vitamin A against subclinical vitamin A deficiency among 345 preschool children. At baseline, children either had or were at high risk of developing non-corneal xerophthalmia. Vitamin A status was assessed by the relative dose response (RDR) test, serum retinol concentration, and ocular examination before and 3 and 6 mo following one oral dose of 105 mumol or 210 mumol of vitamin A. At 3 and 6 mo, mean serum retinol concentration was significantly higher in the 210-mumol group than in the 105-mumol group. The proportion of children with a positive RDR did not differ between groups at 3 mo, but by 6 mo there were three times more children positive in the 105-mumol group. Most of the observed difference was confined to children with xerophthalmia at baseline. The relative benefit of the 210-mumol dose was related to baseline vitamin A status. The current World Health Organization recommended prophylactic dose of 210 mumol seems appropriate.

Child, Preschool↗
PubMed1984

Vitamin E concentrations in the brains and some selected peripheral tissues of selenium-deficient and vitamin E-deficient mice.

Weanling male CD-l mice were fed control, vitamin E-deficient or selenium-deficient diets for periods of 12 to 20 weeks. alpha-Tocopherol concentrations in plasma, liver, and testes, as well as in three specific areas in the brain (cerebral hemisphere, cerebellum, and medulla plus pons) were determined by high performance liquid chromatography. Significant concentrations of alpha-tocopherol were found in all brain samples from vitamin E-deficient animals long after the peripheral tissues were depleted, indicating that brain is more resistant to vitamin E deficiency than peripheral tissues. Cerebellar concentrations of alpha-tocopherol were consistently lower than those of cerebral hemisphere and medulla-pons. Furthermore, the cerebellar alpha-tocopherol concentration sustained a larger decline than the other two brain areas within 6 weeks of vitamin E deficiency treatment. These and other data suggest that cerebellum may be more susceptible to damage from vitamin E deficiency than other parts of the brain. Selenium deficiency did not affect brain alpha-tocopherol concentrations during the 12 weeks of the study.

Animals↗
PubMed1994

Vitamin K--its essential role in craniofacial development. A review of the literature regarding vitamin K and craniofacial development.

The normal vitamin K status of the human embryo appears to be close to deficiency. Maternal dietary deficiency or use of a number of therapeutic drugs during pregnancy, may result in frank vitamin K deficiency in the embryo. First trimester deficiency results in maxillonasal hypoplasia in the neonate with subsequent facial and orthodontic implications. A rat model of the vitamin K deficiency embryopathy shows that the facial dysmorphology is preceded by uncontrolled calcification in the normally uncalcified nasal septal cartilage, and decreased longitudinal growth of the cartilage, resulting in maxillonasal hypoplasia. The developing septal cartilage is normally rich in the vitamin K-dependent protein matrix gla protein (MGP). It is proposed that functional MGP is necessary to maintain growing cartilage in a non-calcified state. Developing teeth contain both MGP and a second vitamin K-dependent protein, bone gla protein (BGP). It has been postulated that these proteins have a functional role in tooth mineralization. As yet this function has not been established and abnormalities in tooth formation have not been observed under conditions where BGP and MGP should be formed in a non-functional form.

1-Carboxyglutamic Acid↗
PubMed1978

Effects of cortisol on adrenal phenylethanolamine-N-methyltransferase: antagonistic effects of vitamin D in hypophysectomized rats fed a vitamin D free diet.

The influence of individual or combined administration of vitamin D and hydrocortisone on adrenal phenyl-N-methyltransferase (PNMT) in hypophysectomized rats deprived of vitamin D for 1 month has been studied, as well as adrenal and urinary epinephrine and norepinephrine. Daily administration of vitamin D for 11 days decreased PNMT activity and increased adrenal norepinephrine, whereas adrenal epinephrine remained unaffected. Epinephrine and norepinephrine urinary excretion increased after four and nine injections of vitamin D from the hypophysectomized rats fed a vitamin D free diet for 1 month. Hydrocortisone treatment produced increases in adrenal PNMT and epinephrine as well as in urinary excretion of both monoamines. The effects of individual administration are neutralized when the two products are injected together.

Adrenal Glands↗
PubMed2001

Plasma folate but not vitamin B(12) or homocysteine concentrations are reduced after short-term vitamin B(6) supplementation.

Adverse effects of high vitamin B(6) intake include peripheral neuropathy. Recent studies focussing on the reduction of plasma homocysteine as a risk factor for vascular disease showed that vitamin B(6) reduces plasma folate levels. The significance of this finding is unclear. We therefore analyzed plasma folate and basal homocysteine levels as well as the response to an oral methionine loading test in 8 healthy individuals before and after a controlled supplementation with oral doses of 25 mg pyridoxine for 10 days. Plasma pyridoxal phosphate increased from 40.6 +/- 13.6 to 426.8 +/- 200.3 nmol/l (p < 0.001), whereas plasma folate decreased from 6.3 +/- 1.6 to 4.6 +/-1.5 ng/ml (p < 0.01), respectively. Plasma vitamin B(12) and basal homocysteine levels remained unchanged (234.0 +/- 27.8 vs. 217.1 +/- 50.4 pg/ml and 10.9 +/- 4.8 vs. 10.1 +/- 3.6 micromol/l). There was no significant effect of vitamin B(6) supplementation on the area under methionine and homocysteine concentration versus time curve. Significant correlations were found between pre- and post-supplement levels of folate as well as PLP levels (r = 0.73, p < 0.05; r = 0.75, p < 0.05). These data suggest that a dose of 25 mg vitamin B(6) supplemented for 10 days reduces plasma folate but did not affect basal and postprandial homocysteine levels suggesting (1) a normal cellular availability of folate or (2) a compensation of impaired homocysteine remethylation by increased transsulfuration.

Adult↗
PubMed1988

Effect of therapy with vitamin B12 and folic acid on elderly patients with low concentrations of serum vitamin B12 or erythrocyte folate but normal blood counts.

To help understand the haematological significance of the low concentrations of serum vitamin B12 and erythrocyte folate occurring in elderly patients, 17 acute admissions to a geriatric unit with a low concentration of serum vitamin B12 or erythrocyte folate but a normal blood count were treated with vitamin B12 and folic acid for 3 months. Bone marrow deoxyuridine suppression was abnormal in 3 of these 17 patients, 2 of whom also had megaloblastic change in the marrow. With treatment, the MCV fell in 13 of the 17, and the average MCV fell from 90.5 to 87.9 fl (p = 0.007), but the mean Hb did not change. Ten untreated similar patients showed no change in their MCV over the same period, but the mean Hb fell from 14.0 to 13.1 g/dl (p = 0.04). Thus the low concentrations of serum vitamin B12 or erythrocyte folate found in approximately a quarter of acutely admitted elderly patients may indicate true tissue deficiency of these vitamins, even when the blood count is normal.

Blood Cell Count↗
PubMed2002

Vitamin E as an antioxidant of the lung: mechanisms of vitamin E delivery to alveolar type II cells.

Oxidants play an important role in the development of acute and chronic lung injuries. Alveolar surfactant is the first target of air-borne oxidants. Surfactant contains, besides dipalmitoyl phosphatidylcholine, cholesterol and polyunsaturated phospholipids that play an important functional role. Therefore, vitamin E could be important for protecting surfactant lipids against oxidation and subsequent lung injury. Alveolar type II cells play a central role in synthesis and secretion of surfactant lipids and also supplement the surfactant with vitamin E during intracellular assembly. High density lipoprotein (HDL) is the primary source of vitamin E for type II cells. The uptake of vitamin E by specific lipid transfer is mediated by at least three HDL-specific receptors (scavenger receptor BI, membrane dipeptidase, and HDL-binding protein-2). In addition, cubilin and megalin mediate in a cooperative manner HDL-holoparticle uptake by alveolar type II cells. A temporary vitamin E deficiency induces a reversible change of the expression of pro- and antiinflammatory markers and of markers defining apoptosis, and reduces surfactant lipid synthesis in alveolar type II cells. These metabolic changes of type II cells may prime the lung to develop clinically manifest injury in response to an additional insult, e.g., hyperoxia.

Animals↗
PubMed1987

Vitamin K1 increases sister chromatid exchange in vitro in human leukocytes and in vivo in fetal sheep cells: a possible role for "vitamin K deficiency" in the fetus.

The levels of the vitamin K-dependent clotting factors are markedly lower in the human fetus and newborn than in older infants and adults. Direct measurement of vitamin K1 in cord plasma records low or undetectable levels. This phenomenon, although the norm, is referred to as vitamin K deficiency and is a significant risk factor for hemorrhage in the fetus and newborn. Sister chromatid exchange (SCE), which may be used as an index of mutagenic activity, was assayed in cultured leukocytes of placental and adult blood following phytohemagglutinin stimulation. The mean number of SCEs per metaphase in human placental blood was 3.32 +/- SE 0.219 as compared with levels of 5.13 +/- SE 0.273 in young adults (p less than 0.01), and in the presence of added vitamin K1 at a concentration of 1 X 10(-6) M the SCE increased significantly in both adult and placental cells. In vitro SCE dose response curves to K1 in the blood of fetal and maternal sheep were obtained. When five fetal sheep were given 1 mg of K1 by catheter into the femoral vein the SCE increased from 3.94 +/- SE 0.15 preinjection to 5.38 +/- SE 0.23 at 24 h postinjection (p less than 0.01). In the pretreatment fetal sheep, serum vitamin K1 was below detectable levels in all seven animals in which it was assayed and reached levels as high as 0.3 X 10(-6) M 1 h post-K1 injection. The low level of K1 in the fetus may in fact confer some biological advantage by reducing the risk of mutagenic events during a period of rapid cell proliferation.

Adult↗