Search results for "Calcitriol"
showing 10 items of 49 documents
The relative roles of intragenic polymorphisms of the vitamin d receptor gene in lumbar spine degeneration and bone density.
2001
Study Design. A retrospective cohort study. Objectives. To compare the magnitudes of the associations of TaqI polymorphisms of the vitamin D receptor gene with bone density and lumbar spine degeneration in the same sample. Summary of Background Data. Vitamin D receptor gene variations are associated with osteoporosis, osteoarthritis, and disc degeneration. Their role in these conditions remains poorly understood. Methods. Bone density of the spine and femur were determined through DEXA, and lumbar disc degeneration was determined from magnetic resonance imaging assessments of signal intensity, disc narrowing, bulging, anular tears, herniations, and osteophytes. Associations between these me…
The effect of cholecalciferol for lowering albuminuria in chronic kidney disease: a prospective controlled study.
2013
Background. Growing evidence indicates that vitamin D receptor activation may have antiproteinuric effects. We aimed to evaluate whether vitamin D supplementation with daily cholecalciferol could reduce albuminuria in proteinuric chronic kidney disease (CKD) patients. Methods. This 6-month prospective, controlled, intervention study enrolled 101 non-dialysis CKD patients with albuminuria. Patients with low 25(OH) vitamin D [25(OH)D] and high parathyroid hormone (PTH) levels (n = 50; 49%) received oral cholecalciferol (666 IU/day), whereas those without hyperparathyroidism (n = 51; 51%), independent of their vitamin D status, did not receive any cholecalciferol, and were considered as the co…
Evolutionary History and Functional Characterization of the Amphibian Xenosensor CAR
2011
AbstractThe xenosensing constitutive androstane receptor (CAR) is widely considered to have arisen in early mammals via duplication of the pregnane X receptor (PXR). We report that CAR emerged together with PXR and the vitamin D receptor from an ancestral NR1I gene already in early vertebrates, as a result of whole-genome duplications. CAR genes were subsequently lost from the fish lineage, but they are conserved in all taxa of land vertebrates. This contrasts with PXR, which is found in most fish species, whereas it is lost from Sauropsida (reptiles and birds) and plays a role unrelated to xenosensing in Xenopus. This role is fulfilled in Xenopus by CAR, which exhibits low basal activity a…
Valproate and Short-Chain Fatty Acids Activate Transcription of the Human Vitamin D Receptor Gene through a Proximal GC-Rich DNA Region Containing Tw…
2022
The vitamin D receptor (VDR) mediates 1,25-dihydroxyvitamin D3 pleiotropic biological actions through transcription regulation of target genes. The expression levels of this ligand-activated nuclear receptor are regulated by multiple mechanisms both at transcriptional and post-transcriptional levels. Vitamin D3 is the natural VDR activator, but other molecules and signaling pathways have also been reported to regulate VDR expression and activity. In this study, we identify valproic acid (VPA) and natural short-chain fatty acids (SCFAs) as novel transcriptional activators of the human VDR (hVDR) gene. We further report a comprehensive characterization of VPA/SCFA-responsive elements in the 5…
Management of secondary hyperparathyroidism in uremic patients : the role of the new vitamin D analogs
2007
Secondary hyperparathyroidism - a common comorbid condition in patients with chronic renal insufficiency - is considered a consequence of critical determinants such as hypocalcemia, phosphate retention and reduced levels of calcitriol production. In this complex mechanism, the skeletal apparatus and the nonskeletal targets such as vascular and heart valves are often involved, thus explaining the increased risk of cardiovascular morbidity and mortality of uremic patients. In this review we will focus on the major role played by Calcitriol deficiency as a trigger of secondary hyperparathyroidism and the crucial need for obiquitous vitamin D receptor activation in order to have an optimal PTH …
Nuclear receptors modulate the interaction of Sp1 and GC-rich DNA via ternary complex formation
2000
Binding sites for transcription factor Sp1have been implicated in the transcriptional regulation of several genes by hormones or vitamins, and here we show that a GC-rich element contributes to the retinoic acid response of the interleukin 1β promoter. To explain such observations, it has been proposed that nuclear receptors can interact with Sp1 bound to GC-rich DNA. However, evidence supporting this model has remained indirect. So far, nuclear receptors have not been detected in a complex with Sp1 and GC-rich DNA, and the expected ternary complexes in non-denaturing gels were not seen. In search for these missing links we found that nuclear receptors [retinoic acid receptor (RAR), thyroid…
Inorganic Polyphosphate in Human Osteoblast-like Cells
1998
Significant amounts of inorganic polyphosphates and of polyphosphate-degrading exopolyphosphatase activity were detected in human mandibular-derived osteoblast-like cells. The amount of both soluble and insoluble long-chain polyphosphate in unstimulated osteoblast-like cells was higher than in human gingival cells, erythrocytes, peripheral blood mononuclear cells, and human blood plasma. The cellular content of polyphosphate in osteoblast-like cells strongly decreased after a combined treatment of the cells with the stimulators of osteoblast proliferation and differentiation, dexamethasone, beta-glycerophosphate, epidermal growth factor, and ascorbic acid. The amount of soluble long-chain p…
Vitamin D receptor gene polymorphisms in atopy
2021
Abstract Background The occurrence of allergic conditions, for example allergic asthma, rhinitis, and atopic dermatitis, is rising worldwide. These allergic conditions are associated with poor life quality. Vitamin D is proposed to be linked with increased risk and severe forms of allergic diseases. Aims This review article aimed to evaluate the vitamin D level role and polymorphisms of vitamin D receptor gene (VDR) in atopy. Methods & Materials We analyzed publications that were focusing on levels of vitamin D and/or polymorphism analysis of vitamin D receptor gene in allergic asthma, rhinitis, and atopic dermatitis patients. Results We noticed that levels of vitamin D are extensively stud…
Diagnostic and therapeutical role of vitamin D in chronic hepatitis C virus infection
2011
Although initially identified as a calcium homeostatic hormone, vitamin D is now known to have pleiotropic functions, dealing with both innate and adaptative immunity. Calcitriol mediates its biological effects by binding to the vitamin D receptor (VDR), which is expressed not only by intestine, bone and kidney but also on cell membranes of T lymphocytes, B lymphocytes, dendritic cells and macrophages. Vitamin D plays a role on the degree of liver damage in patients with chronic hepatitis C (CHC): low vitamin D levels have been associated with high hepatic necroinflammatory activity and progression of liver fibrosis. Vitamin D, in CHC patients, could also affect the response to antiviral th…
The Hepatic Expression of Vitamin D Receptor Is Inversely Associated With the Severity of Liver Damage in Genotype 1 Chronic Hepatitis C Patients
2015
BACKGROUND/AIMS: Low 25-hydroxyvitamin D serum levels have been associated with the severity of liver fibrosis in genotype 1 chronic hepatitis C patients (G1CHC), and experimental evidence suggested a hepatoprotective role of vitamin D via interaction with hepatic vitamin D receptor (VDR). We assessed the hepatic expression of VDR protein and its association with liver disease severity. METHODS: Ninety-one consecutive patients with biopsy-proven G1CHC and available frozen liver tissue were evaluated. Ten subjects without chronic liver diseases and nine patients with autoimmune hepatitis served as controls. The hepatic expression of VDR protein was assessed by Western blot for quantification…