Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Decreased bone mass has been reported in patients with idiopathic hypercalciuria. Previous studies, using bioassays, have suggested a role of interleukin-1 (IL-1), in the decreased bone mineral density (BMD) of fasting hypercalciuria. The present study was designed to determine which IL-1 fraction (alpha or beta) correlates with bone resorption and whether other known bone resorting cytokines like interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) may play a role in this process. Cytokines production was determined by quantitative and specific analysis, enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR). Dual-energy X-ray absorptiometry and cytokine production by unstimulated and lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) were determined in a group of 29 patients with recurrent nephrolithiasis (17 hypercalciurics and 12 normocalciurics), and 12 healthy controls. The hypercalciuric subjects showed lower vertebral BMD than the normocalciuric or normal controls. There was no difference in spinal or femoral BMD between absorptive or fasting hypercalciurics. A significant negative correlation existed between urinary calcium excretion and vertebral BMD (r = -0.55, P < 0.01). Basal IL-1 alpha production correlated with vertebral BMD (r = -0.45, P < 0.02). This correlation was not seen with IL-1 beta, IL-6 or TNF-alpha production. LPS-induced IL-6 and TNF-alpha production were enhanced in the hypercalciuric patients, when compared to normocalciurics or controls. Control and normocalciuric subjects showed minimal amounts of IL-1 alpha mRNA. In contrast, hypercalciuric patients showed a significant increase of spontaneous IL-1 alpha mRNA transcription. These results suggest that different cytokines could be involved in the bone resorption process observed in hypercalciuria.
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PMID:Possible role of cytokines on the bone mineral loss in idiopathic hypercalciuria. 877 Sep 75

Previous studies from our laboratory demonstrated that bone mineral content is affected in patients with idiopathic hypercalciuria and that there is a correlation between bone mineral loss and in-vitro cytokine production. At the same time we found that short term treatment with alendronate decreased urinary calcium in these subjects. In the present study we have examined the long-term effects of alendronate treatment (10 mg/day for one year) on urinary calcium, urinary hydroxyproline and bone mineral content in 18 idiopathic hypercalciuric and 8 normocalciuric stone formers. Clinical characteristics, as well as gender and age distribution were similar in both groups. Urinary calcium and hydroxyproline, were measured monthly. Calcium excretion decreased significantly at the end of the first month, and remained lower thereafter (277 +/- 28, before vs. 202 +/- 26 mg/g creatinine, after 12 months on alendronate, p < 0.01). Urinary hydroxyproline decreased significantly during the study (125.5 +/- 32.1 vs. 39.66 +/- 17.5 mg/g creatinine, p < 0.05). Serum calcium, glomerular filtration rate, and urinary sodium, did not change during the study. Lumbar spine bone density (trabecular bone) obtained with X ray absorptiometry revealed a significant increase from 1.162 +/- 0.231 to 1.197 +/- 0.248 g/cm2 (p < 0.01). These changes were associated with a significant decrease in IL-1 alpha mRNA transcription by unstimulated and lipopolysaccharide stimulated blood mononuclear cells, as tested by the reverse transcriptase polymerase chain reaction. No changes were observed in bone cortical sites (femoral neck). Normocalciuric subjects showed no significant changes in urinary calcium. In summary, the changes observed in urinary calcium excretion and different bone metabolic parameters, suggest a role of bone in the pathophysiology of idiopathic hypercalciuria.
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PMID:[Role of bones in the physiopathology of idiopathic hypercalciuria: effect of amino-bisphosphonate alendronate]. 956 54

Calbindin D28k has been reported to be involved in the transcellular calcium transport along the rat distal tubule. It has also been shown that chronic metabolic acidosis (CMA) induces significant hypercalciuria. The present study investigated whether CMA affects the mRNA and the protein expression of calbindin D28k along isolated distal tubule (DT) of rats. The animals were made acidotic by adding 0.28 mol/L NH4Cl to the drinking water for 7 d. This maneuver was associated with an increase in plasma ionized calcium. Inulin clearance experiments demonstrated that metabolic acidosis did not affect GFR, but it significantly increased both total and fractional urinary calcium excretion. To define the role of calbindin D28k, total RNA was extracted from DT, identified, and microdissected from collagenase-treated kidneys. cDNA was synthesized from RNA using reverse transcriptase and oligo(dT)(12-18) primers. Calbindin D28k mRNA abundance was semiquantified by a competitive reverse transcription-PCR, using an internal standard of cDNA that differed from the wild-type calbindin D28k by a deletion of 86 bp. The reverse transcription-PCR was performed starting from the same amount of total RNA. For each set of experiments, control and acidotic rats were studied in parallel. The identity of the DT was further verified by the presence of the thiazide-sensitive NaCl cotransporter (rTSC1) mRNA. Calbindin D28k mRNA abundance was 0.89 +/- 0.21 amol/ng total RNA in DT of CMA rats (n = 5) compared with 0.30 +/- 0.12 amol/ng total RNA of control rats (n = 5) (P < 0.05). Using specific rabbit polyclonal anti-calbindin D28k antibody, Western blotting was performed starting from thin slices of outer cortex. Densitometric analysis revealed that in acidotic rats (n = 7) there was a 17 +/- 5% (P < 0.05) increase in calbindin D28k protein abundance compared with controls (n = 7). These results indicate that in the rat, ammonium chloride loading induces an increase in filtered ionized calcium load that is associated with a significant upregulation of calbindin D28k both at the mRNA and protein level. These last effects will help to reduce the concomitant hypercalciuria, thus mitigating the consequence of CMA on calcium metabolism.
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PMID:Effect of chronic metabolic acidosis on calbindin expression along the rat distal tubule. 1066 27

The novel member of the claudin multigene family, paracellin-1/claudin-16, encoded by the gene PCLN1, is a renal tight junction protein that is involved in the paracellular transport of magnesium and calcium in the thick ascending limb of Henle's loop. Mutations in human PCLN1 are associated with familial hypomagnesemia with hypercalciuria and nephrocalcinosis, an autosomal recessive disease that is characterized by severe renal magnesium and calcium loss. The complete coding sequences of mouse and rat Pcln1 and the murine genomic structure are here presented. Full-length cDNAs are 939 and 1514 bp in length in mouse and rat, respectively, encoding a putative open-reading frame of 235 amino acids in both species with 99% identity. Exon-intron analysis of the human and mouse genes revealed a 100% homology of coding exon lengths and splice-site loci. By radiation hybrid mapping, the murine Pcln1 gene was assigned directly to marker D16Mit133 on mouse chromosome 16 (syntenic to a locus on human chromosome 3q27, which harbors the human PCLN1 gene). Mouse multiple-tissue Northern blot showed Pcln1 expression exclusively in the kidney. The expression profile along the nephron was analyzed by reverse transcriptase-PCR on microdissected nephron segments and immunohistochemistry of rat kidney. Paracellin-1 expression was restricted to distal tubular segments including the thick ascending limb of Henle's loop, the distal tubule, and the collecting duct. The identification and characterization of the rodent Pcln1 genes provide the basis for further studies of paracellin-1 function in suitable animal models.
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PMID:Primary gene structure and expression studies of rodent paracellin-1. 1172 35