Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033687 (proteinuria)
 24,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the effect of biochemical modifications not possible in vivo, filters of dog glomerular basement membrane (GBM) were constructed in ultrafiltration cells in vitro. The sieving coefficients (SCs) of three protein markers of differing size and charge (native, anionic bovine albumin-BSA; cationized BSA-cBSA; and immunoglobulin G-IgG) were determined using filters of differing amounts of control GBM, and under varying transmembrane pressures (delta P). Flow rates did not increase proportionately with increasing delta P, indicating filter compressibility. Protein SCs did not change with changing delta P, but did decrease with increasing filter thickness. Control filters showed a small but definite charge selectivity (SCcBSA++ - SCBSA greater than 0); a much greater degree of size selectivity (SCcBSA - SCIgG) was observed. Hexadimethrine (HDM), a polycation which causes proteinuria in vivo, led to marked increases in protein SCs. In contrast, removal of the major population of intrinsic GBM negative charges by carboxyl group methylation only produced a small increase in the filtration of BSA, with no change in filtration of cBSA or IgG. Other biochemical modifications (heparinase or neuraminidase treatment) had no effect on filter permselectivity. Carboxyl group methylation essentially abolished filter binding of cationized ferritin, which showed substantial binding to control filters. These in vitro studies provide confirmatory evidence for a direct effect of HDM on the permselective properties of GBM. In addition, biochemical modification studies suggest a fundamental difference between the binding of an exogenous polycation to GBM anionic sites and the removal of intrinsic charges.
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PMID:Macromolecular sieving by glomerular basement membrane in vitro: effect of polycation or biochemical modifications. 207 68

To label specific anionic sites on glomerular capillary wall structures, biotin was covalently linked to sialic acid residues by sequential treatment with mild peroxidation and biotin hydrazide, while carboxyl groups were biotinylated by exposure to the combination of biotin hydrazide and a water-soluble carbodiimide reagent. Optimal specific labeling of rat glomerular structures was obtained with in situ perfusion of the biotinylation reagents, followed by fixation in 4% phosphate-buffered paraformaldehyde, embedment in LR White resin, and post-embedment detection of biotinylated sites using a sequence of anti-biotin antibodies followed by a secondary antibody-colloidal gold conjugate. Attempts to use streptavidin-gold conjugates were not successful. Specificity of labeling was confirmed by enzymatic (neuraminidase) pre-treatment or by modification of carboxyl groups, as evaluated by electron microscopy and by solid-phase assays of solubilized glomerular basement membrane (GBM) components. In two rats with heavy proteinuria induced by doxorubicin (Adriamycin), a marked reduction in sialic acid residues within the GBM and on the epithelial cell surfaces was found, suggesting that reduced charge density attributable to abnormal sialylation may be important in the pathogenesis of nephrotic proteinuria.
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PMID:Affinity cytochemical labeling of glomerular basement membrane anionic sites using specific biotinylation and colloidal gold probes. 230 3

A single i.v. injection of a mAb 5-1-6 to rats was found to cause massive though transient proteinuria. This mAb 5-1-6, IgG1 was produced by immunization of BALB/c mice with collagenase-treated Wistar rat glomeruli and was highly organ and species specific. Immunoelectron microscopy using immunoperoxidase with the avidin-biotin complex and immunogold staining indicated mAb 5-1-6 to bind in vitro to the surface of glomerular epithelial foot processes, mainly to slit diaphragms. The recognized antigenic molecule was not susceptible to neuraminidase treatment and its Mr was about 51 kDa by immunoprecipitation. A one-shot i.v. injection of this mAb induced proteinuria in rats starting immediately, reaching the peak on day 8 (mean value of 150 mg/24 h), then gradually decreasing to normal level on day 18. The in vivo localization of administrated mAb 5-1-6 changed with time. Linear binding along glomerular capillary walls was observed 2 h after injection. However, 3 days later, it partially shifted to a fine granular pattern. The linear pattern disappeared and the size as well as intensity of the fluorescent granules decreased on day 12 to trace positive on day 18. Immunoelectron microscopy revealed the binding pattern of in vivo injected mAb 5-1-6 after 2 h to be similar to that in vitro. Three days later, injected mAb was observed within multivesicular bodies in glomerular epithelial cells as well as along the surface of foot processes and around slit diaphragms. Twelve days after injection, mAb along the surface of the foot processes and around slit diaphragms decreased but those in multivesicular bodies were observed more frequently. Rat IgG and C3 could not be detected throughout the period of observation. No histologic abnormalities were noted except for partial retraction of epithelial foot processes at the peak of proteinuria on day 8. This mAb thus provides a valuable means for examining the mechanism of proteinuria.
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PMID:Massive proteinuria induced in rats by a single intravenous injection of a monoclonal antibody. 339 34

The polycation hexadimethrine (HDM) binds to anionic sites in the glomerular basement membrane (GBM) and causes heavy proteinuria when infused in vivo. An in vitro assay of 3H-HDM binding to isolated dog GBM was developed, to permit further analysis of the GBM components binding HDM. 3H-HDM binding to isolated GBM was saturable, reversible in dose-dependent fashion by competing polycations, and inhibited by increasing salt concentration and low pH. The pH dependence of binding suggested that most of the HDM binds to carboxyl groups rather than to the sulfate groups of proteoglycans. Removal of heparan sulfate by heparinase or purified heparatinase had no detectable effect on HDM binding. Treatment of GBM with neuraminidase, hyaluronidase, or chondroitinase reduced binding of HDM by a maximum of 20 to 38%. However, substitution of carboxyl anions with nonionizable glycine methyl ester residues resulted in complete elimination of HDM binding. Parallel results were obtained in studies of glomerular localization of cationized ferritin (CatF), pI 8.5. After carboxyl substitution, GBM did not bind CatF; heparinase-treated GBM bound CatF in a distribution not demonstrably different from normal. Cellulose acetate electrophoresis of glycosaminoglycan fractions prepared from treated GBM confirmed that carboxyl modification did not alter the content or charge of the heparan sulfate of GBM, but heparinase treatment removed at least 90% of heparan sulfate. The results indicate that carboxyl groups are quantitatively more important than heparan sulfate for binding of HDM in vitro. Since HDM causes proteinuria in vivo, carboxyl groups may be important for maintenance of normal permselectivity.
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PMID:Polycation binding to glomerular basement membrane. Effect of biochemical modification. 380 16

Several lines of evidence suggest that increased neuraminidase activity may be responsible for the loss of glomerular N-acetylneuraminic acid (AcNeu) observed in various glomerular diseases. However, virtually no information is available on the activity of neuraminidase in glomeruli or the potential role of this enzyme in glomerular pathophysiology. Utilizing 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid (4MU-AcNeu) as substrate, we defined optimal assay conditions and characterized neuraminidase activity in glomeruli and, for comparison, in other renal fractions and liver. Neuraminidase activity in glomeruli, cortex and tubules was maximal at pH 4.4. The Km for 4MU-AcNeu was estimated to be 195 microM for glomeruli and 226 microM for cortex. Glomerular neuraminidase was inhibited by AcNeu (90% at 25 mM) and high concentrations of Triton X-100 (26% at 0.5%), but unaffected by CaCl2, EDTA or N-ethylmaleimide (each 1 mM). Neuraminidase activity (nmol/h per mg of protein; mean +/- S.E.M.) in normal rat kidney was: cortex, 14.47 +/- 0.76; medulla, 7.85 +/- 0.64; papilla, 2.64 +/- 0.11; tubules, 13.79 +/- 0.70; glomeruli, 5.57 +/- 0.28. In comparison, neuraminidase activity in rat liver was 2.58 +/- 0.14. Puromycin aminonucleoside (PAN)-induced nephrotic syndrome is a model of glomerular disease in which the loss of glomerular AcNeu is well documented. In two separate studies, we observed no change in the specific activity of neuraminidase in either glomeruli or cortex isolated from rats treated with PAN (15 mg/100 g, intraperitoneally) and killed at either the onset or the peak of proteinuria. Results were similar whether neuraminidase activity was expressed per mg of protein or per microgram of DNA.
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PMID:Renal neuraminidase. Characterization in normal rat kidney and measurement in experimentally induced nephrotic syndrome. 382 21

Glomerular epithelial cells (GECs) in vitro provide a useful model for the study of the mechanism(s) underlying the nephrotic syndrome of rats induced by the aminonucleoside of puromycin (PAN). Some of the toxicities of PAN are nonspecific, in that the constituent molecules of PAN (adenosine and puromycin) cause similar effects in vitro. These include GEC blebbing and rounding, reduced uptake of precursors of protein (leucine) and glycoprotein (glucosamine) synthesis, and increased permeability of the GEC membrane to adenosine. Some of the effects of PAN are not reproduced by adenosine or puromycin and are inhibited by the simultaneous presence of N6-monomethyl adenosine (MMA), a PAN analog and an in vivo blocker of nephrosis due to PAN. These processes may be related to the nephrotic syndrome and include the loss of adhesion to plastic; a reduction in the incorporation of 14C-glucosamine and 35S-sulfate both into molecules removable from the GEC surface by neuraminidase and into those moieties precipitated from the culture media by TCA; a marked reduction in the "ordering" of the lipids of the rigid GEC membrane, which is possibly dependent upon cell-surface proteins. These morphologic alterations in GECs and in the distribution of negatively charged molecules, which are either secreted or on the cell surface, correlate with observations made in PAN-induced nephrosis in rats in vivo. These include changes in the turnover and the array of sialic acid and heparan sulfate glycoprotein on the GECs and the glomerular basement membrane. The in vitro sensitivity of GECs to PAN and the effects of MMA suggest a role for these cells in in vivo aminonucleoside nephrotoxicity, where alterations in both the morphology and the anionic topology of GECs participate in the development of proteinuria.
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PMID:Effects of the aminonucleoside of puromycin on glomerular epithelial cells in vitro. 397 43

Previous reports have suggested that, in proteinuria induced by adriamycin (ADR), the functional size barrier of the glomerular basement membrane (GBM) is altered as the result of a sieving defect, whereas the functional charge barrier of the glomeruli remains intact. The aim of this study was to reevaluate the effect of ADR on anionic constituents in the glomerular capillary wall (GCW). Kidneys of nephrotic rats, induced by the injection of 7.5 mg/kg ADR, and controls were resected, and cortices were isolated 24 h and 10 days postinjection, fixed with formaldehyde, and embedded in paraffin. For the histochemical evaluation of sialyl residues, deparafinized sections were treated with biotin-labeled peanut agglutinin (PNA), before or after neuraminidase treatment. PNA binding was visualized by the avidin-biotin-peroxidase complex and interacted with hydrogen peroxide and diaminobenzidine. For electron microscopy, kidney cortices were fixed with glutaraldehyde and embedded in araldite or LR-white. The postembedding localization of anionic sites was carried out by cationic colloidal gold (CCG), directly applied on thin LR-white sections. Although in the 24-h ADR group, kidney functions and glomerular morphology were generally unaltered, the 10-day ADR group exhibited severe proteinuria, hypoalbuminemia, and massive fusion of intercalated foot processes of the podocytes. Intense PNA binding was observed after neuraminidase treatment in the GCW of the controls. This was gradually decreased in the 24-h ADR kidneys and further decreased in the 10-day ADR, indicating a gradual decrease in glomerular sialic acid content.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Modifications in glomerular polyanion distribution in adriamycin nephrosis. 778 47

In search of the basic defect and cell type responsible for the massive treatment-resistant proteinuria of congenital nephrotic syndrome of the Finnish type (CNF), we examined tissue samples of CNF kidneys using established antibody and lectin markers of various glomerular cell types. Markers of vascular endothelium (antibodies to factor VIII and a human homologue of podocalyxin (anti-PHM5) and UEA I lectin) showed no qualitative changes in the endothelial cells of glomeruli or peritubular areas in CNF as compared with controls. Markers of glomerular mesangial cells (antibodies to desmin, smooth muscle actin, RCA I lectin) revealed a secondary increase in mesangial reactivity reflecting the sclerosis and expansion of the mesangial areas in CNF. Markers of visceral epithelial cells (antibodies to a human homologue of podocalyxin, C3b receptor, vimentin, common lymphocytic leukemia antigen, gp44, and the WGA, LFA and, after neuraminidase treatment, PNA lectin) failed to show appreciable qualitative changes in CNF kidney samples. Interestingly, the alpha 2 beta 1 integrins appeared greatly reduced in all CNF samples studied, possibly explaining the mechanisms of CNF-associated proteinuria.
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PMID:Glomerular antigens in severe hereditary nephrosis. 854 48

A defect of lysosomal neuraminidase (sialidase N-acetyl-neuramine acid hydrolase EC 3.2.1.18) leads to a wide spectrum of phenotypes, the most severe of which is nephrosialidosis. A 4-year-old boy of related parents, born at term with hydrops fetalis, is reported. Hydrocephalus was detected at 2 months of age. The child's course over 3 years was characterized by slow growth and psychomotor development. He had mild hepatosplenomegaly, joint restriction, gingival hypertrophy, lens opacities and cherry-red spot. Coarse facial features and depressed nasal bridge were discreet. At the age of 3.5 years, he developed gradual progressive edema, decreased activity and increased fatigue. A diagnosis of nephrotic syndrome was made because of massive proteinuria. Thin-layer chromatography of urinary oligosaccharides revealed the presence of several abnormal sialyloligosaccharides. The diagnosis was confirmed by measurement of neuraminidase activity in cultured skin fibroblasts.
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PMID:Neuraminidase deficiency presenting as a nephrosialidosis: the first case detected in Poland. 894 16

Heparan sulfates (HS) are long, unbranched, negatively charged polysaccharides that are bound to core proteins. HS in the glomerular basement membrane (GBM) is reported to be important for charge-selective permeability. Aberrant GBM HS expression has been observed in several glomerular diseases, such as diabetic nephropathy and membranous glomerulopathy, and a decrease in HS generally is associated with proteinuria. This study, with the use of a controlled in vivo approach, evaluated whether degradation of HS in rat GBM resulted in acute proteinuria. Rats received two intravenous injections of either heparinase III to digest HS or neuraminidase to remove neuraminic acids (positive control). Urine samples were taken at various time points, and at the end of the experiment, kidneys were removed and analyzed. Injection with heparinase III resulted in a complete loss of glomerular HS as demonstrated by immunofluorescence staining using anti-HS antibodies and by electron microscopy using cupromeronic blue in a critical electrolyte concentration mode. In the urine, a strong increase in HS was found within 2 h after the first injection. Staining for agrin, the major HS proteoglycan core protein in the GBM, was unaltered. No urinary albumin or other proteins were detected at any time point, and no changes in glomerular morphology were noticed. Injection of rats with neuraminidase, however, resulted in a major increase of urinary albumin and was associated with an increase in urinary free neuraminic acid. An increased glomerular staining with Peanut agglutinin lectin, indicative of removal of neuraminic acid, was noted. In conclusion, removal of HS from the GBM does not result in acute albuminuria, whereas removal of neuraminic acid does.
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PMID:In vivo degradation of heparan sulfates in the glomerular basement membrane does not result in proteinuria. 1830 8


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