Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0035078 (renal failure)
 31,970 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have utilized [(15)N]alanine or (15)NH(3) as metabolic tracers in order to identify sources of nitrogen for hepatic ureagenesis in a liver perfusion system. Studies were done in the presence and absence of physiologic concentrations of portal venous ammonia in order to test the hypothesis that, when the NH(4)(+):aspartate ratio is >1, increased hepatic proteolysis provides cytoplasmic aspartate in order to support ureagenesis. When 1 mm [(15)N]alanine was the sole nitrogen source, the amino group was incorporated into both nitrogens of urea and both nitrogens of glutamine. However, when studies were done with 1 mm alanine and 0.3 mm NH(4)Cl, alanine failed to provide aspartate at a rate that would have detoxified all administered ammonia. Under these circumstances, the presence of ammonia at a physiologic concentration stimulated hepatic proteolysis. In perfusions with alanine alone, approximately 400 nmol of nitrogen/min/g liver was needed to satisfy the balance between nitrogen intake and nitrogen output. When the model included alanine and NH(4)Cl, 1000 nmol of nitrogen/min/g liver were formed from an intra-hepatic source, presumably proteolysis. In this manner, the internal pool provided the cytoplasmic aspartate that allowed the liver to dispose of mitochondrial carbamyl phosphate that was rapidly produced from external ammonia. This information may be relevant to those clinical situations (renal failure, cirrhosis, starvation, low protein diet, and malignancy) when portal venous NH(4)(+) greatly exceeds the concentration of aspartate. Under these circumstances, the liver must summon internal pools of protein in order to accommodate the ammonia burden.
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PMID:Alanine metabolism in the perfused rat liver. Studies with (15)N. 1142 41

Osteocytes comprise a heterogenous population of terminally differentiated osteoblasts that direct bone remodeling in response to applied mechanical loading of bone. Increased osteocyte density accompanies the anabolic effect of PTH in vivo, whereas accelerated osteocyte death may be precipitated by estrogen deficiency or excess glucocorticoid exposure (conditions benefitted by intermittent PTH therapy) and by renal failure (where circulating intact PTH and, especially, PTH carboxylfragments are elevated). Osteocytes express type-1 PTH/ PTHrP receptors (PTH1Rs), which are fully activated by aminoterminal PTH fragments and couple to multiple signal transducers, including adenylyl cyclase and phospholipase C. Activation of PTH1Rs in osteocytes promotes gap junction-mediated intercellular coupling, increases expression of MMP-9, potentiates calcium influx via stretch-activated cation channels, amplifies the osteogenic response to mechanical loading in vivo, and regulates apoptosis. Control of osteocyte apoptosis by PTH1Rs is complex, in that intermittent PTH(1-34) administration reduces the fraction of vertebral apoptotic osteocytes at 1 month in adult mice but increases femoral metaphyseal osteocyte apoptosis at 1-2 weeks in young rats. In MLO-Y4 cells, PTH(1-34) prevents apoptosis otherwise induced within 6 hr by dexamethasone. In older studies, large doses of intact PTH(1-84) caused rapid "degenerative" morphologic changes in osteocytes, similar to those described in renal osteodystrophy. We isolated clonal conditionally immortalized osteocytic (OC) cell lines from mice homozygous for targeted ablation of the PTH1R gene. OC cells express abundant (2-3 x 10(6) per cell) receptors specific for the carboxyl(C)-terminus of intact PTH(1-84) ("CPTHRs") but, as expected, do not express PTH1Rs or respond to PTH(1-34). CPTHRs are expressed at much lower levels by other skeletally-derived cell lines. Several highly conserved ligand determinants of CPTHR binding have been identified, including PTH(24-27), PTH(53-54) and the sequence PTH(55-84), loss of which reduces binding affinity by over 100-fold. Human PTH(53-84), like PTH(1-84), PTH(24-84), and PTH(39-84), increases OC cell apoptosis. Ala-scanning mutagenesis to define sequences within PTH(55-84) important for binding and bioactivity is underway. We conclude that osteocytes may be important targets for CPTH fragments that are secreted by the parathyroid glands or generated by peripheral metabolism of intact PTH and that accumulate in blood, especially in renal failure. Studies of functional interplay between responses to CPTHRs and (transfected) PTH1Rs, using receptor-specific ligands in OC cells, should provide new insight into PTH regulation of osteocyte function and survival.
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PMID:PTH receptors and apoptosis in osteocytes. 1575 45

Acute renal failure (ARF) is a frequent and serious complication of endotoxemia caused by lipopolysaccharide (LPS) and contributes significantly to mortality. The present studies were undertaken to examine the roles of nitric oxide (NO) and caspase activation on renal peritubular blood flow and apoptosis in a murine model of LPS-induced ARF. Male C57BL/6 mice treated with LPS (Escherichia coli) at a dose of 10 mg/kg developed ARF at 18 h. Renal failure was associated with a significant decrease in peritubular capillary perfusion. Vessels with no flow increased from 7 +/- 3% in the saline group to 30 +/- 4% in the LPS group (P < 0.01). Both the inducible NO synthase inhibitor L-N(6)-1-iminoethyl-lysine (L-NIL) and the nonselective caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone (Z-VAD) prevented renal failure and reversed perfusion deficits. Renal failure was also associated with an increase in renal caspase-3 activity and an increase in renal apoptosis. Both L-NIL and Z-VAD prevented these changes. LPS caused an increase in NO production that was blocked by L-NIL but not by Z-VAD. Taken together, these data suggest NO-mediated activation of renal caspases and the resulting disruption in peritubular blood flow are an important mechanism of LPS-induced ARF.
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PMID:Disruption of renal peritubular blood flow in lipopolysaccharide-induced renal failure: role of nitric oxide and caspases. 1599 45

ClC-4 and ClC-5 are members of the CLC gene family, with ClC-5 mutated in Dent's disease, a nephropathy associated with low-molecular-mass proteinuria and eventual renal failure. ClC-5 has been proposed to be an electrically shunting Cl- channel in early endosomes, facilitating intraluminal acidification. Motivated by the discovery that certain bacterial CLC proteins are secondary active Cl-/H+ antiporters, we hypothesized that mammalian CLC proteins might not be classical Cl- ion channels but might exhibit Cl(-)-coupled proton transport activity. Here we report that ClC-4 and ClC-5 carry a substantial amount of protons across the plasma membrane when activated by positive voltages, as revealed by measurements of pH close to the cell surface. Both proteins are able to extrude protons against their electrochemical gradient, demonstrating secondary active transport. H+, but not Cl-, transport was abolished when a pore glutamate was mutated to alanine (E211A). ClC-0, ClC-2 and ClC-Ka proteins showed no significant proton transport. The muscle channel ClC-1 exhibited a small H+ transport that might be physiologically relevant. For ClC-5, we estimated that Cl- and H+ transport contribute about equally to the total charge movement, raising the possibility that the coupled Cl-/H+ transport of ClC-4 and ClC-5 is of significant magnitude in vivo.
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PMID:Chloride/proton antiporter activity of mammalian CLC proteins ClC-4 and ClC-5. 1603 21

Aquaporin-11 (AQP11) has been identified with unusual pore-forming NPA (asparagine-proline-alanine) boxes, but its function is unknown. We investigated its potential contribution to the kidney. Immunohistochemistry revealed that AQP11 was localized intracellularly in the proximal tubule. When AQP11 was transfected in CHO-K1 cells, it was localized in intracellular organelles. AQP11-null mice were generated; these mice exhibited vacuolization and cyst formation of the proximal tubule. AQP11-null mice were born normally but died before weaning due to advanced renal failure with polycystic kidneys, in which cysts occupied the whole cortex. Remarkably, cyst epithelia contained vacuoles. These vacuoles were present in the proximal tubules of newborn mice. In 3-week-old mice, these tubules contained multiple cysts. Primary cultured cells of the proximal tubule revealed an endosomal acidification defect in AQP11-null mice. These data demonstrate that AQP11 is essential for the proximal tubular function. AQP11-null mice are a novel model for polycystic kidney diseases and will provide a new mechanism for cystogenesis.
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PMID:Disruption of aquaporin-11 produces polycystic kidneys following vacuolization of the proximal tubule. 1610 22

Mutations in the alanine-glyoxylate amino transferase gene (AGXT) are responsible for primary hyperoxaluria type I, a rare disease characterized by excessive hepatic oxalate production that leads to renal failure. We generated a null mutant mouse by targeted mutagenesis of the homologous gene, Agxt, in embryonic stem cells. Mutant mice developed normally, and they exhibited hyperoxaluria and crystalluria. Approximately half of the male mice in mixed genetic background developed calcium oxalate urinary stones. Severe nephrocalcinosis and renal failure developed after enhancement of oxalate production by ethylene glycol administration. Hepatic expression of human AGT1, the protein encoded by AGXT, by adenoviral vector-mediated gene transfer in Agxt(-/-) mice normalized urinary oxalate excretion and prevented oxalate crystalluria. Subcellular fractionation and immunofluorescence studies revealed that, as in the human liver, the expressed wild-type human AGT1 was predominantly localized in mouse hepatocellular peroxisomes, whereas the most common mutant form of AGT1 (G170R) was localized predominantly in the mitochondria.
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PMID:Alanine-glyoxylate aminotransferase-deficient mice, a model for primary hyperoxaluria that responds to adenoviral gene transfer. 1711 Apr 43

Rokumi-gan (TJ-87) has beneficial effects on renal diseases, including pollakisuria, dysuria and edema. We previously reported that its long-term administration clinically improved serum protein concentration and edema in renal failure. In this study, we focused on amino acid/protein contents in Rokumi-gan as one of its effectors. Commercially prepared Rokumi-gan contained arginine, aspartate and glutamate at the high levels, alanine, phenylalanine and serine at the moderate levels, and glycine, histidine, isoleucine, leucine, lysine and valine at the low levels. To examine effects of Rokumi-gan on serum amino acid concentrations, 6 healthy Japanese volunteers were treated with commercially prepared Rokumi-gan, an amino acid mixture, and lactose. In subjects treated with an amino acid mixture containing similar amounts of amino acids in Rokumi-gan (10 g), or lactose, serum amounts of many amino acids, except for arginine, gradually and significantly decreased until 6 hr after their treatments. In contrast, a single treatment with Rokumi-gan (10 g) increased serum levels of several amino acids, alanine, arginine, glutamate, glycine and serine. Serum concentrations of almost of all tested amino acids showed the peak value 1-2 hr after administration, and they were sustained at the basal level even 6 hr after the treatment. Our present results suggest that Rokumi-gan may be a beneficial amino acid supplier, because it could sustain serum amino acid concentration at the higher level than an amino acid mixture supplement.
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PMID:Effects of single administration of Rokumi-gan (TJ-87) on serum amino acid concentration of 6 healthy Japanese male volunteers. 1738 19

The purpose of this study was to evaluate the safety of cryopreserved and thawed peripheral blood stem cell (PBSC) fractionated return infusions in children. 35 children patients with malignant tumors (13 acute leukaemias, 15 neuroblastomas and 7 malignant lymphomas) received fractionated return infusions of cryopreserved stem cells after undergoing high-dose chemotherapy without or with total body irradiation. The toxicities of 70 return infusions were evaluated. All patients were mobilized by chemotherapy plus recombination human granulocyte colony-stimulating factor (rhG-CSF), and then PBSCs were collected by a separator CS-3000 plus or COBE spectra-4. The grafts were cryopreserved in 10% dimethyl sulfoxide (DMSD) and stored in liquid nitrogen. There were totally 70 PBSC transfusions. The total volume of PBSCs transfused: 190 - 420 ml (265 +/- 73 ml or 13.7 +/- 4.2 ml/kg) with a mean of (4.43 +/- 1.91) x 10(8)/kg of PBSCs, and 0.94 +/- 0.18 g/kg of DMSO. The single dose: 90 - 300 ml (132 +/- 37 ml or 6.6 +/- 5.2 ml/kg) with a mean of 0.68 +/- 0.12 g/kg of DMSO. Symptoms occurring during the infusions were recorded. All patients were monitored for 24 hours after infusion. Pulse, blood pressure, body temperature, and respiratory rate were recorded every 15 minutes. At four hours before and 8 hours after infusion, urinalysis was performed. Serum potassium, sodium, creatinine, total bilirubin, aspartate amino transferase (AST), and alanine amino transferase (ALT) levels were examined within 24 hours before and after the first infusion. The results showed that the toxicities observed included hemoglobinuria in 54 return infusions (77.1%), headache in 28 (40.0%), nausea in 24 (34.3%), vomiting in 17 (24.3%), and abdominal pain in 8 (11.4%). Patients who received a graft > 200 ml tended to have a higher frequency of hemoglobinuria, headache, nausea, vomiting, or abdominal pain (P<0.01), and they disappeared quickly, too. Total bilirubin increased after the first return infusion (P<0.01), and there was a significant correlation between the volume of infusion and the degree of total bilirubin increase (r=0.8977, P<0.01). No renal failure or shock occurred. It is concluded that transient hemoglobinuria, headache, nausea, vomiting, and abdominal pain are common toxicities associated with PBSC autograft, and these toxicities are related with a single volume of PBSCs transfused. Total bilirubin increase is correlated with the volume of infusion. In a word, the toxicity is less frequent and lower severe in children with fractionated infusions of cryopreserved peripheral blood stem cell.
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PMID:[Relevant low toxicities with rhG-CSF mobilized and cryopreserved autologous peripheral blood stem cell return infusions in children]. 1749 57

Brown spiders have world-wide distribution and are the cause of health problems known as loxoscelism. Necrotic cutaneous lesions surrounding the bites and less intense systemic signs like renal failure, DIC, and hemolysis were observed. We studied molecular mechanism by which recombinant toxin, biochemically characterized as phospholipase-D, causes direct hemolysis (complement independent). Human erythrocytes treated with toxin showed direct hemolysis in a dose-dependent and time-dependent manner, as well as morphological changes in cell size and shape. Erythrocytes from human, rabbit, and sheep were more susceptible than those from horse. Hemolysis was not dependent on ABO group or Rhesus system. Confocal and FACS analyses using antibodies or GFP-phospholipase-D protein showed direct toxin binding to erythrocytes membrane. Moreover, toxin-treated erythrocytes reacted with annexin-V and showed alterations in their lipid raft profile. Divalent ion chelators significantly inhibited hemolysis evoked by phospholipase-D, which has magnesium at the catalytic domain. Chelators were more effective than PMSF (serine-protease inhibitor) that had no effect on hemolysis. By site-directed mutation at catalytic domain (histidine 12 by alanine), hemolysis and morphologic changes of erythrocytes (but not the toxin's ability of membrane binding) were inhibited, supporting that catalytic activity is involved in hemolysis and cellular alterations but not toxin cell binding. The results provide evidence that L. intermedia venom phospholipase-D triggers direct human blood cell hemolysis in a catalytic-dependent manner.
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PMID:Identification of a direct hemolytic effect dependent on the catalytic activity induced by phospholipase-D (dermonecrotic toxin) from brown spider venom. 1945 8

Primary hyperoxaluria type 1 (PH1) is a rare metabolic disorder caused by a defect in glyoxylate metabolism attributable to low or absent activity of the liver-specific peroxisomal enzyme alanine/glyoxylate aminotransferase. This defect leads to enhanced conversion of glyoxylate to poorly soluble oxalate, which is then excreted into the urine. This process may lead to deposition of calcium oxalate crystals in many tissues as well as in the kidneys, resulting in nephrolithiasis, nephrocalcinosis, and/or renal failure. We present a 39-year-old patient with end-stage renal failure due to PH1, who was admitted with symptoms of feeling bloated, vomiting, diarrhea, and abdominal pain related to encapsulating peritoneal sclerosis (EPS). He had been treated with peritoneal dialysis for a total period of 5 years. EPS is a rare condition characterized by fibrosis and adhesions of the peritoneum to loops of the small intestine and has been described secondary to treatment with peritoneal dialysis. It also occurs in a variety of other clinical conditions such as autoimmune diseases and peritoneal and intra-abdominal malignancies. The calcium oxalate crystals found in the peritoneal fascia of this particular patient may suggest a causative relationship between crystal deposits and evolution to fibrosis and sclerosis of the peritoneum. The degree of impact of the peritoneal dialysis treatment itself on the development of EPS, however, is uncertain.
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PMID:Encapsulating peritoneal sclerosis in a patient with primary hyperoxaluria type 1: a case report. 2005 90


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