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At least 811 records · Page 45Linked to original sources
PubMed1996

All-trans retinoic acid inhibits binding of 1,25-dihydroxy-vitamin D3 to the vitamin D receptor in cultured human keratinocytes.

Psoriasis is characterized by hyperproliferation and impared differentiation of epidermal keratinocytes (KCs). Psoriasis can be treated with derivatives of retinoic acid (RA) and vitamin D3. Analogues of vitamin D3 are able to inhibit proliferation and stimulate differentiation of KCs. In contrast, RA inhibits terminal differentiation of KCs. Interactions are known to occur between RA and vitamin D3 signalling pathways. The purpose of the present study was to determine the effect of all-trans RA on the binding of 1,25-dihydroxy-vitamin D3 (1,25 (OH)2D3) to the vitamin D3 receptor (VDR) of cultured human KCs. Cultured KCs from normal adults were incubated with or without RA (10-9-10-7M) for 4-24 h. Cells were then harvested, homogenized and ultrasonicated. The extracted protein was incubated with 3H-1,25 (OH)2D3 (0.015-1.0 nM) with or without 250-fold excess nonradioactive 1,25 (OH)2D3 for 24 h and specific binding was determined by use of the dextran coated charcoal binding assay. Western blot analysis utilizing the monoclonal antibody 9A7 gamma to VDR was performed on protein extracted from the KCs. The bands resulting from Western blot analysis were visualized by enhanced chemiluminescence. From Scatchard analysis it was found that KCs bind 1,25 (OH)2D3 with high affinity (Kd = 0.175 nM). This binding was dose and time dependently inhibited by RA (60% inhibition at 10-7 M after 24 h of incubation). By Western blot analysis, RA had no effect on the amount of protein extracted from KCs at any of the RA concentrations tested. In conclusion, these results show that binding of vitamin D3 to its receptor of human KCs can be inhibited markedly by RA without effecting the amount of protein. These results are in contrast to results with other cell types in which RA upregulates binding of 1,25 (OH)2D3 to the VDR. Because interaction between retinoids and vitamin D3 may occur at different levels during signal transduction, it is not possible to predict from our results whether RA will inhibit the effects of vitamin D3 in vivo.

Calcitriol↗
PubMed2003

Vitamin D receptor is expressed in pancreatic cancer cells and a vitamin D3 analogue decreases cell number.

BACKGROUND AND AIM: The vitamin D-receptor (VDR) has been detected in both normal and malignant cells of different tissues. Treatment with vitamin D(3) has been suggested as a possible therapy in malignant diseases such as pancreatic cancer. Synthetic analogues of vitamin D(3) have a less hypercalcemic effect than native vitamin D(3). The aim was to study the expression of the VDR in human pancreatic cancers and to study the in vitro effect of an analogue to vitamin D(3) on cell lines established from these cancers. METHODS: The pancreatic cancer cell lines were established from primary cultures with only cancer cells. A probe specific for the human VDR was used. After reverse-transcriptase PCR and Northern blotting, the expression of the VDR in normal pancreas and in pancreatic cancers was compared. The cell lines were incubated with EB 1089, a synthetic analogue vitamin of D(3), in dose-response studies. The cell number was measured by the XTT colorimetric method. RESULTS: The VDR was expressed in all cancers and in six of the cell lines the expression was increased more than 3-fold compared to normal pancreas. All cell lines developed from human pancreatic cancers responded with a decreased cell number to the vitamin D(3) analogue at concentrations of 10(-5) M or higher. CONCLUSION: The VDR was expressed in all pancreatic cancers studied. Cell lines derived from these cancers responded with a decrease in cell number to high concentrations of a vitamin D(3) analogue. These results, and the doses to use, have to be confirmed with in vivo studies.

Antineoplastic Agents↗
PubMed2002

Vitamin D3 and vitamin D3 analogues as an adjunct to cancer chemo-therapy and radiotherapy.

The development of drugs that are highly selective and yet produce minimal toxicity to host tissue remains one of the most difficult challenges in cancer therapeutics. Since the majority of malignancies are treated with drugs in combination rather than single agents, one practical approach to circumvent this problem is to develop new therapeutic agents that will potentiate the effectiveness of current clinical protocols. This strategy would accelerate the acceptance of new drugs as adjunct therapies since these agents could be used at concentrations well below their maximal tolerated doses. Tumor cells derived from a variety of different sources have been shown to express the Vitamin D(3)receptor and to be susceptible to growth arrest and/or cell death in response to Vitamin D(3)and its analogues. The hypercalcemia that generally accompanies the utilization of pharmacological concentrations of Vitamin D(3) has been ameliorated in part through the development of Vitamin D(3) analogues. Studies in cell culture and in animal model systems as well as clinical trials have established the potential utility of Vitamin D(3) and Vitamin D(3) analogues as agents which can enhance the antiproliferative and/or cytotoxic effects of conventional chemotherapeutic drugs as well as ionizing radiation. Consequently, Vitamin D(3) and Vitamin D(3) analogues, utilized at concentrations which produce limited hypercalcemia, are likely to prove effective as adjuncts to conventional chemotherapy and radiotherapy.

Animals↗
PubMed2002

[Efficacy of combined administration of vitamin D3 and vitamin K2 for primary osteoporosis].

The literatures that reported the efficacy of combined administration of vitamin D(3) and vitamin K(2) for primary osteoporosis are reviewed. Combined administration of vitamin D(3) and vitamin K(2) potentially stimulates bone formation (mineralization) in patients with primary osteoporosis, resulting in an increase in lumbar bone mineral density. Combined administration of vitamin D(3) and vitamin K(2) seems to have the greatest effect on lumbar bone mineral density in the studies in which the mean age and years since menopause of the subjects were low, in contrast to administration of antiresorptive agents, bisphosphonates that has the greatest effects on bone mineral density and incidence of vertebral fractures in the studies in which the mean age and years since menopause are high, and the subjects have marked clinical evidence of osteoporosis. Further prospective, randomized, well-controlled study with long duration of observation is needed to confirm the efficacy of combined administration of vitamin D(3) and vitamin K(2) for primary osteoporosis.

English Abstract↗
PubMed1991

A unique mutation in the vitamin D receptor gene in three Japanese patients with vitamin D-dependent rickets type II: utility of single-strand conformation polymorphism analysis for heterozygous carrier detection.

Vitamin D-dependent rickets type II is a hereditary disease resulting from a defective vitamin D receptor. In three Japanese patients with vitamin D-dependent rickets type II whose fibroblasts displayed normal cytosol binding and impaired nuclear uptake of 1,25-dihydroxyvitamin D3, western, Southern, and northern analyses failed to disclose any abnormalities in vitamin D3 receptor protein and its gene. Exons 2 and 3 of the vitamin D receptor cDNA, which encode the DNA-binding domain consisting of two zinc fingers, were amplified by PCR and sequenced to identify the specific mutations in the vitamin D receptor gene. In the three patients and one normal control a T-to-C transition was found in the putative initiation codon, while this transition was not observed in another normal control. This finding suggested that an original initiation codon was located at positions 10-12 in the human vitamin D receptor cDNA sequence reported previously. In contrast, a unique G-to-A transition at position 140 in exon 3, resulting in substitution of arginine by glutamine at residue 47, was revealed only in these three patients. The arginine at 47 is located between two zinc fingers and is conserved within all steroid hormone receptors. Therefore, it is highly conceivable that this amino acid substitution is responsible for the defect of the vitamin D receptor in the patients. Single-strand conformation polymorphism analysis of amplified DNA confirmed that all patients were homozygous and that parents from one family were heterozygous carriers for this mutation.

Amino Acid Sequence↗
PubMedDate not supplied

The value of the dehydroepiandrosterone-annexed vitamin C infusion treatment in the clinical control of chronic fatigue syndrome (CFS). I. A Pilot study of the new vitamin C infusion treatment with a volunteer CFS patient.

A series of publications from our laboratory have indicated that the practice of megadose vitamin C drip infusion treatment enhanced the activity of endogenous glucocorticoids in such a way as to improve the clinical course of allergy and autoimmune disease-a disease entity that is known to respond to the therapeutic effect of glucocorticoids. The present paper represents an extention of our vitamin C studies, and intends to investigate the problem whether or not chronic fatigue syndrome (CFS), an acquired immunodeficiency disease, can also be counted as one of the candidate diseases for the vitamin C infusion treatment. We prepared two kinds of vitamin C infusion sets for the clinical use: the dehydroepiandrosterone-annexed vitamin C infusion set (the new set) and the annex-free vitamin C infusion set (the old set). The new set was expected to enhance the endogenous activities of both glucocorticoids and gonadal steroids. We followed the clinical course of a male CFS patient using the old and new vitamin C infusion sets, and with and without the oral intake of erythromycin and chloramphenico. Results obtained are as follows: a) the observation period of a study subject covered a period of August 1995 to May 1996. Combination of pneumonia signs and dermatomyositis signs marked the onset of his CFS. b) Old infusion treatment together with the short term antibiotics treatment was found effective for the control of pneumonia in the first stage of the disease (from August to October, 1995). c) Signs of pneumonia recurrence gradually became eminent in the second stage of disease (from November, 1995, to January, 1996) in spite of the moderate frequency of the old treatment together with stepwise prolongation of the antibiotics treatment. d) The alternate practice of the old and new infusion treatments together with the long-term antibiotics treatment, as conducted in the 3rd stage of disease (from February to May, 1996) led to substantial extinction of pneumonia signs (leucocytosis, tachycardia etc). e) The practice of the new infusion treatment markedly increased the excretion of both 17-ketosteroids and 17-hydroxycorticosteroids in the urine. Evidence was also available to indicate that the dehydroepiandrosterone annex was converted to testosterone, which in turn made a contribution to the control of CFS. f) The immunological survey of lymphocyte subsets including NK cell percent failed to find a coherent change in a study subject with CFS. In conclusion, the above results could be taken as evidence to indicate that the new vitamin C infusion treatment effectuates the clinical control of CFS by fortifying the endogenous activities of both cortisol and testosterone. The significance of parallelism between pulmonary infection and CFS, as observed in the clinical course of the test subject, was discussed in the light of the focal infection theory of nephritis.

17-Hydroxycorticosteroids↗
PubMed1977

[Thiamine, riboflavin and vitamin B6 contents of organs in the aged rat. I. Effect of vitamin supplementation administered in drinking water].

Respectualy ten and twenty-two months old rats, fed an equilibrated diet, were given daily and for one month an extra supplementation of thiamine, riboflavin and vitamin B6 in drinking water. Control animals of the same age were fed identical diets but without vitamin extra supplementation. Vitamin contents of organs (liver, heart, kidneys, spleen, lungs, brain) were determined in order to evaluate both the influence of aging and of vitamin supplementation. Twenty-three months old rats show lower values of thiamin contents (except in liver and brain), riboflavin contents (except in heart and spleen) and vitamin B6 contents (except in heart, lungs and brain) than younger rats. Vitamin extra-supplementation reduces some of these differences: thiamine contents in heart, kidneys and spleen, riboflavin contents in brain, vitamin B6 contents in kidneys and spleen. In all other cases, the extra-supplementation has no effect. Therefore, it seems that the decrease in vitamin contents in organs of old rats is, in many cases an unavoidable consequence of aging.

Age Factors↗
PubMed1998

[The effect of furosemide on urinary excretion of oxalic acid, vitamin C and vitamin B6 in chronic kidney failure].

The authors describe the effect of a single i.v. dose of 20 mg furosemide on the excretion of oxalic acid, vitamin C and vitamin B6 in a control group and in patients with chronic renal failure without dialyzation treatment. An increased urinary excretion of oxalic acid, vitamin C and vitamin B6 was found during the first three hours after furosemide administration in both groups. The effect of furosemide persisted for six hours in patients with chronic renal failure without dialyzation treatment. The authors described a new hitherto unknown positive side-effect of furosemide, i.e. enhanced urinary oxalic acid excretion in the control group and in patients with chronic renal failure without dialyzation treatment and a negative side-effect of furosemide, i.e. increased urinary vitamin B6 excretion in both examined groups. With regard to the assembled results the authors recommend in addition to monitoring of vitamin C also monitoring of vitamin B6 in plasma during long-term administration of large doses of furosemide to patients with chronic renal failure as deficiency of these vitamins could develop.

Adult↗
PubMed1991

Serum vitamin A, retinyl esters and vitamin E in nephrotic syndrome.

Serum vitamin A, retinyl esters and vitamin E were increased in a group of 33 patients with chronic glomerulonephritis and nephrotic syndrome without reduction of mean glomerular filtration rate. Despite hypoproteinaemia and reduced values of serum proteins with a different molecular weight, increased values of vitamin A protein carriers were found. Serum total cholesterol, LDL cholesterol, triglyceride, prebeta und beta lipoproteins were increased, HDL cholesterol was within the reference range. Direct relationships were found between serum retinyl esters and vitamin A, and between serum retinyl esters and prealbumin. Indirect relationships were detected between serum total cholesterol and total proteins, serum total cholesterol and albumin, and serum vitamin E and albumin. The increased values of vitamin A, retinyl esters as well as its protein carriers and of vitamin E were probably a manifestation of enhanced protein and lipid synthesis in the liver as a result of albumin depletion. These results show true A and E hypervitaminosis in patients with nephrotic syndrome.

Blood Proteins↗
PubMed2001

Role of vitamin K and vitamin K-dependent proteins in vascular calcification.

OBJECTIVES: To provide a rational basis for recommended daily allowances (RDA) of dietary phylloquinone (vitamin K1) and menaquinone (vitamin K2) intake that adequately supply extrahepatic (notably vascular) tissue requirements. BACKGROUND: Vitamin K has a key function in the synthesis of at least two proteins involved in calcium and bone metabolism, namely osteocalcin and matrix Gla-protein (MGP). MGP was shown to be a strong inhibitor of vascular calcification. Present RDA values for vitamin K are based on the hepatic phylloquinone requirement for coagulation factor synthesis. Accumulating data suggest that extrahepatic tissues such as bone and vessel wall require higher dietary intakes and have a preference for menaquinone rather than for phylloquinone. METHODS: Tissue-specific vitamin K consumption under controlled intake was determined in warfarin-treated rats using the vitamin K-quinone/epoxide ratio as a measure for vitamin K consumption. Immunohistochemical analysis of human vascular material was performed using a monoclonal antibody against MGP. The same antibody was used for quantification of MGP levels in serum. RESULTS: At least some extrahepatic tissues including the arterial vessel wall have a high preference for accumulating and using menaquinone rather than phylloquinone. Both intima and media sclerosis are associated with high tissue concentrations of MGP, with the most prominent accumulation at the interface between vascular tissue and calcified material. This was consistent with increased concentrations of circulating MGP in subjects with atherosclerosis and diabetes mellitus. CONCLUSIONS: This is the first report demonstrating the association between MGP and vascular calcification. The hypothesis is put forward that undercarboxylation of MGP is a risk factor for vascular calcification and that the present RDA values are too low to ensure full carboxylation of MGP.

Arteriosclerosis↗
PubMed1985

Serum vitamin K1 concentration and vitamin K-dependent clotting factor activity in maternal and fetal cord blood.

The serum concentration of phylloquinone (vitamin K1) was measured in 34 healthy mothers and in the arterial cord blood of their newborn infants. In addition, the activities of factor II and of factors VII plus X were determined simultaneously in 16 paired maternal and fetal bloods. The serum vitamin K1 concentration was similar to that of control subjects in 27 mothers: 9.03 +/- 4.9 micrograms/L (mean and SD), with a simultaneous concentration of 10.4 +/- 5.3 micrograms/L in cord blood. Six mothers exhibited high serum vitamin K1 concentrations from 40 to 240 micrograms/L (median, 82) and the concentration in cord blood ranged from 25 to 115 micrograms/L (median, 71). One mother had a normal concentration of vitamin K1: 9 micrograms/L while no vitamin K1 was detectable in the serum of her infant. The activity of factor II and factors VII plus X was 7% and 7%, respectively, in this infant and 100% in the mother. All other mothers showed normal factor II and factors VII plus X activity, while the median activity was 47% (28%-56%) for factor II and 65% (35%-100%) for factors VII plus X in cord blood. These data suggest that vitamin K1 can cross the placental barrier but not in every case. Therefore the systematic administration of vitamin K1 to the newborn infant seems to be required to prevent the occurrence of the hemorrhagic disease.

Blood Coagulation Factors↗
PubMed1978

Plasma vitamin D-binding globulin in vitamin D deficiency, pregnancy and chronic liver disease.

Plasma concentrations of vitamin D-binding globulin were measured by radial immunodiffusion in healthy subjects, pregnancy, and during oestrogen therapy. Subjects with disorders of vitamin D metabolism (dietary deficiency, malabsorption, anticonvulsant therapy, chronic liver disease) were also studied. Neither sex nor age influenced the plasma vitamin D-binding globulin concentration in healthy subjects, but there was a significant increase in concentration during pregnancy and oestrogen therapy. Elevated levels were found in vitamin D deficient elderly but not younger subjects, while levels in subjects with chronic liver disease were significantly reduced. Normal levels of vitamin D-binding globulin were present in hypervitaminosis D and no vitamin D-binding globulin was detected in human milk. No correlation was observed between plasma 25-hydroxycholecalciferol levels and plasma vitamin D-binding globulin concentrations.

Adult↗
PubMed1981

Studies on interactions of vitamin E with thiamine, niacin and vitamin B12.

The effects of simultaneous administration of thiamine, niacin or vitamin B12 with vitamin E on plasma vitamin E levels were studied in 20 adult male volunteers belonging to the low socio-economic class. The effect of vitamin E on the nutritional status of pyridoxine, riboflavin and thiamine as judged by the erythrocyte enzymes, aspartate aminotransferase, glutathione reductase and transketolase, respectively was also studied. None of the members of the B-complex vitamins studied here had any effect on plasma vitamin E levels. This was in contrast to the observation made earlier that pyridoxine and riboflavin can reduce plasma vitamin E. There was a transient reduction in both the basal and stimulated activities of erythrocyte aspartate aminotransferase, the significance of which needs further investigation.

Adult↗
PubMed1987

Rat and human liver vitamin K epoxide reductase: inhibition by thiol blockers and vitamin K1.

1. Reduction of vitamin K1 2,3-epoxide by rat and human liver vitamin K epoxide reductase is inhibited by N-ethylmaleimide and iodoacetamide. 2. Both enzymes are protected from inhibition by N-ethylmaleimide by vitamin K1 or vitamin K1 2,3-epoxide. 3. Vitamin K1 inhibits reduction of vitamin K1 2,3-epoxide to vitamin K1 which suggests product inhibition of the enzyme.

Animals↗
PubMed1990

Comparison of the vitamins K1, K2 and K3 as cofactors for the hepatic vitamin K-dependent carboxylase.

The vitamins phylloquinone (K1), menadione (K3) and various menaquinones (K2) were compared for their ability to serve as a cofactor for the hepatic vitamin K-dependent carboxylase. It was found that the cofactor activity of the menaquinones varied with the length of the aliphatic side-chain and showed an optimum at MK-3. Menadione was not active at all. The concentration required for half-maximal reaction velocity (K 1/2) was determined for the various menaquinones and decreased at increasing chain length. The K 1/2 value for MK-4 was 3-times lower than that for vitamin K1. Under our in vitro conditions both vitamin K1 and the K2 vitamins were rapidly metabolized into a mixture of the quinone, the hydroquinone and the epoxide form. The fact that at equilibrium the level of these three metabolites was independent of the starting material shows that the vitamin K cycle is operational for vitamin K1 as well as for K2.

Amino Acid Sequence↗
PubMed1995

Assay of vitamin A palmitate and vitamin E acetate in cosmetic creams and lotions by supercritical fluid extraction and HPLC.

The use of supercritical fluid extraction (SFE) as an alternative to liquid extraction was examined for the isolation of vitamin A palmitate and vitamin E acetate from cream and lotion preparations. Investigation of the factors controlling the extraction efficiency in SFE indicated that vitamin recoveries were affected mainly by the extraction pressure and by the degree of sample dispersion. The vitamins were analysed by high-performance liquid chromatography after a 30-min extraction of the cosmetic product with supercritical carbon dioxide at 40 degrees C and at a pressure of 250 atm. Compared with conventional liquid extraction SFE produced slightly lower recoveries (> 91.6%) but afforded a more effective purification of the cosmetic matrices. Moreover, SFE minimized sample handling and the use of harmful solvents and provided mild extraction conditions for the analysis of the labile vitamins. Vitamin E acetate and vitamin A palmitate were assayed in commercial cream and lotion formulations using the proposed SFE technique.

Anticarcinogenic Agents↗
PubMed2004

Response element binding proteins and intracellular vitamin D binding proteins: novel regulators of vitamin D trafficking, action and metabolism.

Using vitamin D-resistant New World primates as model of natural diversity for sterol/steroid action and metabolism, two families of novel intracellular vitamin D regulatory proteins have been discovered and their human homologs elucidated. The first family of proteins, heterogeneous nuclear ribonucleoproteins (hnRNPs), initially considered to function only as pre-mRNA-interacting proteins, have been demonstrated to be potent cis-acting, trans-dominant regulators of vitamin D hormone-driven gene transactivation. The second group of proteins bind 25-hydroxylated vitamin D metabolites. Their overexpression increases vitamin D receptor (VDR)-directed target gene expression. We found that these intracellular vitamin D binding proteins (IDBPs) are homologous to proteins in the heat shock protein-70 family. Our ongoing studies indicate directly or indirectly through a series of protein interactions that the IDBPs interact with hydroxylated vitamin D metabolites and facilitate their intracellular targeting.

Animals↗
PubMed2002

Vitamin K 2,3-epoxide reductase and the vitamin K-dependent gamma-carboxylation system.

Vitamin K is an essential cofactor for post translational gamma-carboxylation of vitamin K-dependent coagulation factors. The modification is carried out by a system of integral proteins of the endoplasmic reticulum (ER) membrane where the warfarin sensitive vitamin K 2,3-epoxide reductase (VKOR) produces the reduced hydroquinone form of vitamin K (vit.KH(2)) needed by the gamma-carboxylase as the active cofactor. Currently, we have only limited knowledge about how the system functions at the molecular level. VKOR harbors a thiol red/ox center that is essential for electron transfer leading to vitamin K reduction. Reduction of this center with hydrophilic and hydrophobic trialkylphosphines shows that it is located in a hydrophobic environment which must be accessible by an as yet unidentified in vivo reductant of the center. Furthermore, we have addressed the question of whether VKOR or the gamma-carboxylase is the rate-limiting step in the vitamin K-dependent gamma-caboxylation system. A detailed kinetic analysis of an in vitro preparation of the system was undertaken in which gamma-carboxylation of the carboxylase peptide substrate FLEEL was measured as the gamma-carboxylation capacity of the system. Adding VKOR to the test system increased the gamma-carboxylation capacity of the system suggesting that VKOR is the rate-limiting step in the system. This finding puts VKOR in a central position to regulate biosynthesis of biologically active vitamin K-dependent proteins.

Animals↗