Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As manifest by tubular collapse and the virtual absence of flow into the glomerulotubular junction (GTJ), filtration in most nephrons (SNGFR) of rats poisoned with 9 mg/kg body wt HgCl2 16 to 28 hours earlier was virtually absent. Arterial colloid osmotic pressure (COPA) and Bowman's space pressure (PBS) were modestly depressed (P less than 0.05 or below), and mean blood pressure was reduced from 115 +/- 2 mm Hg (SEM) to 97 +/- 1 mm Hg (P less than 0.001). Glomerular capillary hydraulic pressure (Pg), 25.6 +/- 1.3 mm Hg was some 24 mm Hg lower than control (P less than 0.001) and yielded a net afferent effective filtration pressure (Pnet) of 4.1 +/- 1.2 mm Hg. Excluding three rats with values greater than 10 mm Hg, Pnet averaged 2.0 +/- 0.9 mm Hg (N = 17 rats) versus 20.0 +/- 1.8 mm Hg in controls (N = 10, P less than 0.001), the former being statistically almost indistinguishable from 0 mm Hg and barely able to support any filtration. This decrease in Pg was caused by a major increase in preglomerular resistance (RA) and a reciprocal fall in efferent arteriolar resistance (RE), the RA/RE ratio of 7.2 +/- 0.8 being fourfold higher than control (P less than 0.001). Renocortical blood flow was not different from control (P greater than 0.2). A wide spread of Pg values in individual glomeruli and the absence of tubular flow despite the appearance of i.v. injected lissamine green in a quadrant of surface glomeruli suggested the possibility of a greatly increased, glomerular capillary resistance. It is concluded that reciprocal changes in RA and RE are the immediate cause of filtration failure in this form of ARF and that, in the virtual absence of filtration, tubular leakage can play no important role. Since PBS was depressed in both the developmental and established phases of ARF, tubular obstruction appears to play no direct role in the pathogenesis of this particular model of murine acute renal failure.
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PMID:Glomerular hemodynamics in mercury-induced acute renal failure. 365 37

Adult female Wistar rats were injected with 1 mg/kg body weight of uranyl nitrate (UN). Evaluation of renal function, histopathology studies, and determination of plasma erythropoietin (Ep) titers after exposure to 456 mb for 16 h were performed at 1, 2, 7, 10, 15, and 21 days after drug injection. Plasma urea and creatinine concentrations markedly increased during the first seven days after injection, reaching maximal values on day 7 and decreasing thereafter. Significant increases in urine volume and significant depressions in urine osmolality also were observed; both alterations were most marked on day 7 after injection. A coagulative necrosis of the epithelium of proximal convoluted tubules, desquamation of the necrotic cells, and dilation or collapse of the tubular lumen were observed; the lesions were more marked on day 7. Plasma Ep levels in UN-treated rats exposed to hypobaria were markedly lower than in noninjected controls similarly exposed. Measurements were performed one, two, and seven days after UN injection, with maximal depression observed on day 7. These observations indicate that there is a correlation between the extent of both tubule damage and degree of renal dysfunction and plasma Ep production during exposure to hypoxia in UN-treated rats. This suggests that the renal Ep component is derived primarily from tubular cells.
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PMID:Relationship between severity of renal damage and erythropoietin production in uranyl nitrate-induced acute renal failure. 369 9

Two single amino acid mutant proteins of beta-lactamase PC1 from Staphylococcus aureus, P2 Thr40----Ile and P54 Asp146----Asn, have been investigated using urea-gradient polyacrylamide gel electrophoresis, circular dichroism and sedimentation velocity. Investigation of the folded states of the mutants has shown that compared to wild-type PC1 they are slightly more expanded, and have reduced aromatic circular dichroism, but the same content of secondary structure as PC1. The mutants exhibit fast refolding kinetics to the folded state, in contrast to PC1, which refolds only slowly. We conclude from these results that the folded mutants are in a state close to but distinct from the native state of PC1 and have certain properties in common with the compact intermediate in the folding of beta-lactamase. Therefore, these single amino acid substitutions result in a folding pathway blocked at a point located after collapse of the already folded structural units into a globular shape, and close to the final reshuffling step that leads to the native state of the wild-type enzyme.
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PMID:Single amino acid mutations block a late step in the folding of beta-lactamase from Staphylococcus aureus. 387 72

The morphological changes of the inner ear were observed after intravenous administration of 2 g/kg of urea to the guinea pigs with endolymphatic hydrops which had previously been produced by injecting 10% silver nitrate solution into the endolymphatic sac. They showed membranous collapse extensively in the saccule, moderately in the lower turns of the cochlea and less in the upper turns and the utricle. Because of these changes, it is reasonable to assume that urea is causing the endolymph to be reabsorbed in the endolymphatic duct. Furthermore, the effect of urea seemed to depend on the pathological condition of the duct which sometimes showed a varying degree of atrophied change after silver nitrate injection.
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PMID:Effect of urea on endolymphatic hydrops in guinea pigs. 408 Mar 35

The ribonucleic acid (RNA) of murine leukemia virus (MLV) Rauscher strain was observed by the aid of electron microscopy with the use of the protein monolayer technique. RNA was observed directly after release from virus particles or after isolation by sedimentation in sucrose density gradients. Molecules were found in an extended linear form. Many of the RNA filaments released by detergent treatment contained curled regions, suggesting the linear filaments were originally coiled within the virus particle. The relationship of the curled areas to the containment of the RNA within the virus particle is discussed, and a mechanism for the inclusion of RNA in the budding virion is proposed. Treatment of the extended MLV-RNA with dimethyl sulfoxide resulted in the collapse of the molecule forming a tangled complex. Treatment with urea or heating at 50 C in 3 mm NaCl also produced this effect. Also under the conditions in which MLV-RNA was linear, RNA from Rous sarcoma virus also was linear, but Newcastle disease virus RNA and ribosomal RNA of rat liver had collapsed structures. The results indicated that the RNA of MLV, and perhaps other RNA-containing tumor viruses, has a specific unique conformation dependent upon hydrogen bonds.
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PMID:Electron microscopic observations on the ribonucleic acid of murine leukemia virus. 430 80

1. Highly purified resealed chromaffin-granule ;ghosts' were assayed for ATPase and ATP-driven H(+)-translocation and 5-hydroxytryptamine-uptake activities, and for 5-hydroxytryptamine uptake driven by an imposed transmembrane H(+)-gradient. The effects of several inhibitors on these activities were studied. 2. Dicyclohexylcarbodi-imide inhibits all of these activities, but not in parallel; at low concentrations it decreases the permeability of the membrane to protons. 3. 4-Chloro-7-nitrobenzofuran (Nbf-Cl) and silicotungstate inhibit ATP-dependent activities, without effect on 5-hydroxytryptamine uptake driven by an imposed H(+)-gradient. 4. Tributyltin chloride inhibits all of the activities. 5. Treatment of the ;ghosts' with low concentrations of urea inhibits 5-hydroxytryptamine uptake and ATP-dependent generation of a transmembrane H(+)-gradient, without inhibiting ATPase activity. 6. Nbf-Cl and silicotungstate are without effect on the rate of leakage of 5-hydroxytryptamine from preloaded ;ghosts', whereas dicyclohexylcarbodi-imide and tributyltin chloride accelerate the rate of leakage. 7. Treatment of the membranes with (14)C-labelled Nbf-Cl labels several proteins; membranes treated with dicyclohexyl[(14)C]carbodi-imide are labelled predominantly in a protein of low molecular weight, which may be analogous to the mitochondrial H(+)-conducting proteolipid. 8. It is concluded that Nbf-Cl and silicotungstate inhibit the H(+)-translocating ATPase of the granule membrane; that dicyclohexylcarbodi-imide inhibits the ATPase, and inhibits 5-hydroxytryptamine accumulation by accelerating leakage of the amine; and that the effects of tributyltin chloride are due to inhibition of the ATPase, and collapse of the transmembrane H(+)-gradient through OH(-)-anion exchange.
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PMID:Inhibition of adenosine triphosphatase, 5-hydroxytryptamine transport and proton-translocation activities of resealed chromaffin-granule 'ghosts'. 625 64

The clinical and biochemical data obtained in 85 patients with diabetic ketoacidosis (DKA) are presented. DKA is an acute exacerbation of diabetes, a characteristic clinico-biochemical syndrome including increasing thirst, polyuria, adynamia, dryness of the skin and mucous membranes, anorexia, nausea, vomiting, occasionally abdominal pain, Kussmaul's breath, acetone odour in the exhaled air, circulatory collapse, prerenal azotemia, stupor, coma. Glycemia level exceeds 19 mmol/l, blood pH over 7.3. The disease is marked by neutrophilic leukocytosis, blood count shift to the left, elevated blood content of creatinine and urea. It was established that the degree of consciousness abnormality does not always correlate with the degree of the clinico-biochemical manifestations of DKA. During DKA, coma occurs relatively seldom (5.9%). It is suggested to use the term "diabetic ketoacidosis", incipient or marked, indicating the degree of consciousness abnormality (stupor, coma).
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PMID:[Diabetic ketoacidosis (causes, clinico-biochemical correlations and terminology problems)]. 644 Dec 97

Patients hospitalized in critical care unit for acute renal failure (ARF) in a multiorgan failure syndrome have often a poor intra-dialysis tolerance. Change from Ac to Bi for dialysate buffering has been advocated to improve this dialytic tolerance. In a retrospective study, 70 patients who received Bi hemodialysis are compared with 106 patients who received Ac hemodialysis. If the mortality is not different between these two groups, intra-dialysis tolerance is significantly better (p less than 0.001) in the Bi group according to the mean intra-dialysis systolic blood pressure decrease, the collapse occurrence and the mean vascular volume infusion. Ultrafiltration rate is higher and reach more often the desired values. On a biochemical point of view, hemodialysis efficacy is the same in the two groups according to urea and creatinin clearance, but end dialysis Bi plasma concentrations are higher and nearer of the normal range in the Bi group even though predialysis Bi plasma concentrations were similar. The only side effect observed with Bi dialysis was a hypoglycemic episode without clinical consequence, due to the lack of glucose in the bicarbonate dialysate. Nevertheless, in patients under controlled ventilation, a end dialysis alkalosis can occur if a hyperventilation is imposed. Change from Ac to Bi in dialysate buffering improves the intra-dialysis tolerance of patients with ARF in a multiorgan failure syndrome. This kind of hemodialysis is now used routinely in our critical care unit.
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PMID:[Acute kidney failure in a resuscitation milieu: improvement of dialysis tolerance using bicarbonates in the dialysate]. 666 39

Based on the hypothesis that rapid corrections of pH, Na+ and osmolality give rise to disequilibrium (DES) during efficient haemodialysis (HD), a 14 compartment model has been designed for dynamic analysis of the induced fluid shifts and the resulting haemodynamic reactions. Simulated HD and ultrafiltration (UF) on the model were based on data from 11 steady state dialysis (RDT) patients (diffusion coefficients for urea, body fluid compartments, haemodynamic monitoring by Swan-Ganz catheters). The model reactions correlated remarkably with clinical findings and indicate how far a patient's haemodynamic compensation can prevent circulatory collapse and hypovolaemia, mainly through lowering the mean pressure in a major portion of the capillaries. Steady weight dialysis causes reduction of blood volume up to 65 per cent before circulatory collapse occurs.
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PMID:Computer modelling of haemodialysis/ultrafiltration explaining the pathogenesis of the disequilibrium syndrome. 687 51

In an effort to stimulate the in vivo formation of active enzyme from newly synthesized polypeptide chains, we have studied the in vitro assembly of the active catalytic subunits of aspartate transcarbamoylase from unfolded polypeptide chains. Hydrodynamic and spectroscopic measurements showed that incubating the catalytic trimers in 4.7 M urea for 45 min at 9 degrees C produced unfolded polypeptide chains largely devoid of the secondary and tertiary structures characteristic of native subunits. Dilution of the urea solutions led to the slow restoration of enzyme activity and the formation of trimers at a rate which could be measured quantitatively by a hybridization technique using succinylated polypeptide chains as a "chase" to "stop" the assembly. Kinetic studies showed that reactivation and assembly of trimers were coincident with a half-time for completion of about 50 min at 0 degrees C. Also, the rate-limiting reaction was first order. Although these results suggest that chain folding is the slow process, spectroscopic studies indicated that large changes in the environments of the aromatic amino acid residues occur very rapidly. Indeed the changes in the absorption spectrum are largely complete before significant reactivation and trimer formation occur. The results are consistent with an assembly mechanism in which the first step is the rapid collapse of the expanded randomly coiled chains to give partially folded monomers. These monomers are not enzymically active and cannot associate to form trimers until a rate-limiting conformational change occurs. Subsequent to this slow process, the "competent" monomers associate via a series of reactions to form active trimers.
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PMID:Assembly of the catalytic trimers of aspartate transcarbamoylase from unfolded polypeptide chains. 709 28


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