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W Gwinner

Publications and source records attributed to W Gwinner.

At least 19 recordsLinked to original sources
PubMed2006

Pivotal role of xanthine oxidase in the initiation of tubulointerstitial renal injury in rats with hyperlipidemia.

Hyperlipidemia can induce or aggravate renal tubulointerstitial injury. Experiments in a complex rat model with chronic glomerulonephritis and long-standing, coexisting hyperlipidemia suggested that induction of xanthine oxidase (XO), with increased oxygen radical generation, is involved in aggravation of tubulointerstitial injury. To separate the role of XO in the initial events of lipid-mediated tubulointerstitial injury, short-term experiments with diet-induced hyperlipidemia over 21 and 35 days were performed in otherwise healthy rats. XO expression in relation to the antioxidant enzymes was examined in the cortical tubulointerstitium (TIS) and proximal tubules (PT). Subsequent experiments with XO inhibition were performed, examining tubulointerstitial infiltration with ED1-positive cells and expression of adhesion molecules and monocyte chemoattractant protein-1 (MCP-1) as indicators of early injurious events. Hyperlipidemia increased XO activity in TIS by 40 and 86%, and in PT by 28 and 90% at days 21 and 35, compared with controls on regular diet. This increased activity was associated with increased reactive oxygen species. Among the antioxidant enzymes, glutathione peroxidase activity increased in TIS by 40% and in PT by 90%. Histological evaluation showed a three-fold increase in ED1-positive cells and increased MCP-1 and vascular cell adhesion molecule-1 (VCAM-1) expression at day 35 in the TIS. Inhibition of XO prevented tubulointerstitial ED1 cell infiltration, together with a decreased expression of MCP-1 and VCAM-1. These results point to an important role for XO in the early stage of hyperlipidemia-associated renal injury, mediating macrophage infiltration by a putatively redox-dependent upregulation of MCP-1 and VCAM-1.

Animals↗
PubMed2005

Biocompatibility parameters of different dialysis membranes assessed during systemic inflammation.

BACKGROUND: We explored whether biocompatible dialyzer membranes modulate the inflammatory response during blood contact in patients with systemic inflammation. METHODS: 15 patients with end-stage renal disease and systemic inflammation (mean serum C-reactive protein 86 +/- 4 mg/l) were randomly treated with Cuprophan (CU), polyamide (PA) and vitamin-E coated (VEC) membrane-based dialyzers. RESULTS: Changes in blood pressure, capillary blood oxygen saturation and differential blood counts during the hemodialysis session were not significantly different between the three dialyzers. Baseline blood levels of activated circulating complement (C3a) were more than 100 times above normal, and unlike expected they decreased during hemodialysis treatments (CU: from 7,389 +/- 783 to 5,423 +/- 761 ng/ml; PA: from 7,379 +/- 980 to 5,690 +/- 714 ng/ml; VEC: from 7.377 +/- 714 to 5,360 +/- 1,005 ng/ml; all n.s.). No significant differences between treatments were found with respect to changes in blood concentrations of TNF-alpha, interleukin-6 and interleukin-1 receptor antagonist as well as ICAM-1 (CU: from 451 +/- 41 to 477 +/- 41 ng/ml; PA: from 437 +/- 42 to 449 +/- 40 ng/ml; VEC: from 461 +/- 43 to 460 +/- 47 ng/ml). Furthermore, generation of reactive oxygen species by mononuclear blood cells was comparable during hemodialysis with the CU, PA and VEC dialyzer. CONCLUSION: The choice of dialyzer membrane material does not affect most aspects of biocompatibility when patients have significant systemic inflammation. This confounding variable should be taken into account in studies exploring the effects of biocompatible dialyzer membranes.

Female↗
PubMed2005

Life-threatening complications of extracorporeal treatment in patients with severe eosinophilia.

We report three patients with massive eosinophilia of different etiology who developed bronchoconstriction, hypotension, and shock shortly after dialysis or leukapheresis had been begun. In two cases, ethylene oxide-free materials had been used ruling out an allergic reaction related to this compound. Degranulation of eosinophils with release of eosinophil peroxidase may have caused the observed adverse reactions, as suggested by in vitro experiments with blood from the three patients. Our observations draw attention to the fact that extracorporeal therapies may initiate life-threatening complications in patients with severe eosinophilia.

Acute Kidney Injury↗
PubMed2000

Oxidant stress in hyperlipidemia-induced renal damage.

Hyperlipoproteinemia can aggravate glomerulosclerosis and chronic tubulointerstitial (ti) damage in kidneys without primary immunologic disease. We evaluated whether the effect of hyperlipidemia on progression of renal damage differed between kidneys without preexisting glomerular disease and kidneys with mesangioproliferative glomerulonephritis and whether the renal actions of hyperlipidemia were dependent on oxidant-antioxidant balance. Hyperlipidemia was induced by high-fat and high-cholesterol diet in uninephrectomized rats. In rats without glomerulonephritis, hyperlipidemia led to a rise in glomerular and ti generation of reactive oxygen species (ROS). Oxygen radicals were mainly generated by enhanced xanthine oxidoreductase (XO), which rose with protein concentration and activity during hyperlipidemia; concurrently, glomerulosclerosis and chronic ti injury were noticed during hyperlipidemia [ti damage (% of total tubulointerstitium (TI) after 150 days): normolipidemia 0.1 +/- 0% vs. hyperlipidemia 3.4 +/- 0. 9%; P < 0.05]. In mesangioproliferative Thy-1 nephritis, ti injury was significantly accelerated by hyperlipidemia (ti damage after 150 days: normolipidemic Thy-1 nephritis 2.5 +/- 0.6% vs. hyperlipidemic Thy-1 nephritis 12.5 +/- 3.1%; P < 0.05). Antioxidant enzyme activities decreased and XO activity rose markedly in the TI (XO activity in TI after 150 days: normolipidemic Thy-1 nephritis 2.2 +/- 0.5 vs. hyperlipidemic Thy-1 nephritis 4.5 +/- 0.7 cpm/microg protein; P < 0.05). In hyperlipidemic Thy-1 nephritis rats, which had a higher urinary protein excretion than normolipidemic rats, hypochlorite-modified proteins, an indirect measure for enhanced myeloperoxidase activity, were detected in renal tissue and in urine, respectively. During hyperlipidemia, chronic damage increased in renal TI. Enhanced generation of ROS, rise in oxidant enzyme activity, and generation of hypochlorite-modified proteins in renal tissue and urine were noticed. These data suggest that oxidant stress contributed to the deleterious effects of hyperlipidemia on the renal TI.

Animals↗
PubMed1999

Role of increased production of superoxide anions by NAD(P)H oxidase and xanthine oxidase in prolonged endotoxemia.

Superoxide anions (O2-) are supposedly involved in the pathogenesis of endothelial dysfunction. We investigated whether the enhanced formation of O2- is involved in the attenuation of endothelium-dependent relaxation induced by lipopolysaccharide (LPS). Rats were injected with LPS (10 mg/kg IP), the aorta was removed after 12 or 30 hours, and generation of O2-, H2O2, and ONOO- was measured using chemiluminescence assays. Protein tyrosine nitration and expression of xanthine oxidase (XO), NAD(P)H oxidase, and manganese superoxide dismutase were determined by Western or Northern blotting, and endothelium-dependent relaxation in aortic rings was studied. LPS treatment increased vascular O2- (from 35+/-2 cpm/ring at baseline to 166+/-21 cpm/ring at 12 hours and 225+/-16 cpm/ring at 30 hours) and H2O2 formation, which was partially sensitive to the NAD(P)H oxidase inhibitor diphenylene iodonium at both time points studied and to the XO inhibitor oxypurinol only 30 hours after LPS treatment. Expression of XO and NAD(P)H oxidase (p22phox, p67phox, and gp91phox) were increased by LPS in a time-dependent manner, as were protein tyrosine nitration and ONOO- formation. LPS also induced expression of the oxidative stress-sensitive protein manganese superoxide dismutase. Endothelium-dependent relaxation was impaired after LPS treatment and could not be restored by inhibition of inducible NO synthase. Inhibition of O2- with superoxide dismutase, oxypurinol, tiron, or the superoxide dismutase mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride did not restore but further deteriorated the relaxation of LPS-treated rings. In summary, treatment of rats with LPS enhances vascular expression of XO and NAD(P)H oxidase and increases formation of O2- and ONOO-. Because removal of O2- compromised rather than restored endothelium-dependent relaxation, a direct role of O2- in the induction of endothelial dysfunction is unlikely. Other mechanisms, such as prolonged protein tyrosine nitration by peroxynitrite (which is formed from NO and O2-) or downregulation of the NO effector pathway, are more likely to be involved.

Analysis of Variance↗
PubMed1999

Role of xanthine oxidase in passive Heymann nephritis in rats.

Passive Heymann nephritis (PHN) in rats is a model of human membranous nephropathy characterized by formation of subepithelial immune deposits in the glomerular capillary wall and complement activation. Oxygen radicals have been implicated in the subsequent glomerular damage which leads to proteinuria. This study examines the involvement of xanthine oxidase in this process. Xanthine oxidase activity was increased nearly twofold in glomeruli isolated 1 and 12 d after induction of PHN, and this was associated with increased glomerular superoxide anion generation. Analysis of glomerular samples by Northern and Western blotting revealed no quantitative changes in xanthine oxidoreductase expression in PHN, suggesting conversion of xanthine dehydrogenase to the oxidase form as the cause of increased activity. Treatment of rats with tungsten, an inhibitor of xanthine oxidase, before induction of PHN resulted in a marked decrease in glomerular xanthine oxidase activity and superoxide anion generation, and decreased proteinuria by 80% (day 12: 423+/-245 mg/d in PHN versus 78+/-53 mg/d in tungsten-treated PHN animals, P < 0.01). These findings point to a pivotal role of xanthine oxidase in the pathophysiology of PHN and could be of importance in the therapy of human membranous nephropathy.

Animals↗
PubMed1998

Antioxidant-oxidant balance in the glomerulus and proximal tubule of the rat kidney.

1. Antioxidant and oxidative enzymes were examined in renal glomeruli and proximal tubules of healthy young rats (10-12 weeks old), and results were related to the superoxide anion generation of these tissues. 2. Activities of superoxide dismutases, catalase, and glutathione peroxidase were 3- to 6-fold higher in proximal tubules than in glomeruli. Similarly, enzyme levels and mRNA levels of superoxide dismutases and catalase were significantly higher in proximal tubules. 3. NADH- and NADPH-dependent oxidase activity and xanthine oxidase activity were not different in glomeruli and proximal tubules. 4. Measurements with lucigenin-enhanced chemiluminescence in vital tissues indicated 10-fold higher rates of superoxide anion in glomeruli than in tubules. 5. Compared with the young rats, tubules of 8-month-old rats had significantly higher superoxide anion rates and lower superoxide dismutase activity, whereas NADH- and NADPH-dependent oxidase activities were unchanged. 6. We conclude that considerable differences in the antioxidant-oxidant balance exist between the glomerulus and proximal tubule. Results from experiments using chemiluminescence in vital tissues suggest that changes in the antioxidant-oxidant balance have an effect on oxygen radical levels. The relevance of the observed differences to glomerular and tubulo-interstitial disease remains to be determined, but a greater susceptibility of the glomerulus to oxidant stress might be anticipated.

Animals↗
PubMed1998

Endothelium-dependent vasodilatation in Sprague-Dawley rats with postinfarction hypertrophy: lack of endothelial dysfunction in vitro.

The hypothesis was tested whether postinfarction hypertrophy/congestive heart failure in rats is associated with endothelial dysfunction and increased vascular generation of reduced oxygen species. Myocardial infarction was induced in Sprague-Dawley rats by ligation of the left coronary artery. After 16 weeks, endothelium-dependent (with acetylcholine) and -independent (with sodium nitro-prusside) relaxations were studied in isolated aortic rings, and isolated rings from the femoral and mesenteric arteries. The generation of superoxide, hydrogenperoxide, and peroxynitrite was measured in arteries using lucigenin- and luminol-enhanced chemiluminescence techniques. Systolic blood pressure decreased over the 16 week study period as compared to shamoperated control rats; organ weights (lungs, right and left ventricles) significantly increased in coronary artery ligated rats indicating development of congestive heart failure. Surprisingly, concentration response curves with acetylcholine and sodium nitroprusside were almost identical in myocardial infarction rats as compared to control animals, irrespective of which type of vessel was studied (aorta, femoral or mesenteric arteries). In addition, no differences in the production of reduced radical species were found in aortic tissue from heart failure rats as compared to control rats.

Acetylcholine↗
PubMed1997

Reactive oxygen species and antioxidant defense in puromycin aminonucleoside glomerulopathy.

Results from several radical scavenger studies indirectly suggested an involvement of reactive oxygen species in the pathogenesis of puromycin aminonucleoside glomerulopathy. In this study, generation of reactive oxygen species was examined directly in glomeruli isolated from rats in the acute phase of puromycin aminonucleoside nephrosis and related to the changes in the glomerular antioxidant defense. Five and nine days after puromycin aminonucleoside injection, gross proteinuria, reduced creatinine clearances, and typical changes of glomerular morphology were present. Levels of reactive oxygen species were increased eightfold in glomeruli isolated 15 min after puromycin aminonucleoside injection, returned to baseline levels on days 1 and 5 after injection, and rose again to 14-fold on day 9 after injection, as determined by chemiluminescence with luminol. Further analysis of increased glomerular radical generation, using the chemiluminescence enhancer lucigenin and different radical scavengers, suggested a predominant involvement of hydroxyl radical and hydrogen peroxide in the initial increase in reactive oxygen species 15 min after puromycin aminonucleoside. Nine days after induction of nephrosis, primarily superoxide anion and hydroxyl radical were found to contribute to increased reactive oxygen species. Despite oxidative stress, antioxidant enzymes were not induced in the course of nephrosis. On the contrary, catalase and glutathione peroxidase activities declined 9 d after puromycin aminonucleoside injection. The results indicate that a transient increase in glomerular reactive oxygen species is sufficient to induce the oxidative glomerular injury observed in this model and that the glomerulus may not necessarily respond to oxidative stress with an induction of antioxidant enzymes.

Animals↗
PubMed1995

Regulation of manganese superoxide dismutase in glomerular epithelial cells: mechanisms for interleukin 1 induction.

Reactive oxygen species have been implicated as mediators of tissue injury in glomerular inflammation. The expression of the antioxidant enzyme, manganese superoxide dismutase (MnSOD), was examined in primary cultures of rat glomerular epithelial cells (GEC) in response to inflammatory mediators. The results demonstrate that GEC respond to interleukin-1 (IL-1) and bacterial lipopolysaccharride (LPS) with an increase in MnSOD steady-state mRNA levels. The IL-1 alpha-mediated induction of MnSOD mRNA levels was both time- and dose-dependent. Maximal levels approximately 40-fold above controls, were observed at 12 hours with 2 ng/ml of IL-1 alpha. MnSOD protein levels were also markedly elevated by IL-1 alpha. The induction of MnSOD mRNA by IL-1 alpha required de novo transcription as well as some degree of protein synthesis. To elucidate the potential intracellular signal that mediates IL-1 alpha-dependent MnSOD expression, three classical signaling pathways were examined. We found no evidence that MnSOD induction by IL-1 alpha is mediated by either the cyclooxygenase or lipoxygenase pathway or via activation of protein kinase C. Based on the presence of IL-1 alpha in several forms of glomerular inflammation, the observed increase in MnSOD expression by this immunoregulatory cytokine must have an important role in the antioxidant defense of glomerular epithelial cells.

Animals↗
PubMed1994

Early urinary markers of target nephron segments as studied in cadmium toxicity.

A number of chemicals may adversely affect one or more of the anatomical structures of the kidney, such as the glomerulus, the tubular apparatus, the medullary, or interstitial cells. To recognize subclinical renal dysfunction, a battery of new, non-invasive tests was applied in comparison to established ones. The study on cadmium exposed subjects, performed within the framework of a collaborative European research project, exemplifies the concept of target selectivity within a nephron. One hundred seventy-two subjects were classified according to urinary cadmium excretion as controls (< 1.5 micrograms/g creatinine), or subjects with moderate or high cadmium body burden (1.5 to 5 micrograms/g creatinine, > 5 micrograms/g creatinine). Twenty-six urinary analytes (such as serum derived proteins, tubular enzymes, eicosanoids) and four plasma markers, related to the function or integrity of specific nephron segments, were investigated in a cross-sectional study. The group with the moderate cadmium body burden showed alterations of proximal tubular integrity, that is, increased excretion of tubular brush-border antigens. The group with higher cadmium body burden revealed an involvement of the whole nephron. The most prominent quantitative changes were found for the glomerular markers high molecular weight proteins, and thromboxane B2 and for the proximal tubular markers retinol binding protein, alpha 1-microglobulin, N-acetyl-beta-D-glucosaminidase, and the intestinal alkaline phosphatase. A diagnostic approach to screen for nephrotoxicity due to environmental hazards like cadmium should include proximal tubular markers (alpha 1-microglobulin and tubular enzymes, that is, intestinal alkaline phosphatase) but the measurement of glomerular markers is also advisable.

Adult↗
PubMed1993

Origin of urinary fibronectin.

BACKGROUND: Fibronectin (FN) is a major component of the glomerular extracellular matrix and it is also abundant in plasma. In physiologic conditions, FN fragments are excreted into urine. Increased urinary FN excretion has been observed in renal diseases raising the question whether urinary FN could reflect changes in the renal extracellular matrix. This study examines whether urinary FN is filtered from plasma or derived from the kidney and it attempts to specify the potential renal source of urinary FN. EXPERIMENTAL DESIGN: (a) To investigate whether urinary FN is filtered from plasma, labeled, biotinylated FN (b-FN) was injected into rats and urine samples were specifically analyzed for b-FN by an immunoblot procedure. (b) To specify the renal source of urinary FN and to evaluate possible alterations of this protein during passage into final urine, tubular fluid was collected from distinct localizations of the nephron by micropuncture techniques. The samples were analyzed for endogenous FN by a highly sensitive immunoblot system, and the pattern was compared with that normally found in final urine. RESULTS: (a) Urine samples collected over a period of 5 days after injection of b-FN contained no labeled FN. Control experiments in rats with highly elevated glomerular permeability confirmed that the plasma levels of injected b-FN were sufficiently high since b-FN was detected in urine in this condition. (b) The FN fragment pattern, with two protein bands at 75 and 45 kilodaltons, that is normally found in final urine, was already present in samples taken from the early proximal tubule and the distal tubule. CONCLUSIONS: The fibronectin fragments normally found in urine originate from the kidney and are not derived from plasma. Since these fragments are already observed in early proximal tubular fluid, the glomerulus is the probable source of urinary FN. The FN fragment pattern of early proximal tubular fluid is not substantially altered during passage into final urine, thus reflecting glomerular FN release in urine. It is suggested that examination of urinary FN excretion could be helpful in the assessment of altered glomerular extracellular matrix in pathologic conditions.

Animals↗
PubMed1991

Metabolic heterogeneity of isolated cortical and juxtamedullary glomeruli in adriamycin nephrotoxicity.

The anticancer drug adriamycin (ADR) is selectively toxic to glomerular cells when administered intravenously (5 mg/kg b.w.) to female MWF/Ztm rats. Recent data have shown that the proteinuria associated with the lesion does not occur in cortical glomeruli, suggesting the selective injury of juxtamedullary glomeruli. In the present study, the effect of ADR on glomerular metabolism was studied with special reference to possible differences between cortical and juxtamedullary glomeruli. On day 7 after ADR treatment, cortical and juxtamedullary glomeruli were separately isolated by the sieving method and 14C glucose oxidation to 14CO2 and the incorporation of 3H proline into macromolecules were measured in vitro and used to study target selective injury in ADR-treated rats compared to control rats. The investigations revealed differences in the response of cortical and juxtamedullary glomeruli to ADR. ADR treatment increased proline incorporation over a 4-hour incubation period in both glomerular populations compared to controls, but the effect was significantly (p less than 0.05) more pronounced in juxtamedullary glomeruli (juxtamedullary: 187 +/- 8% of control; cortical: 167 +/- 4% of control). Glucose oxidation was enhanced after 4 h only in juxtamedullary glomeruli (juxtamedullary: 132 +/- 3% of control; cortical: 82 +/- 10% of control). These data show that glomerular damage caused by ADR is associated with a stimulating effect on glomerular metabolism which is more marked in juxtamedullary than in cortical glomeruli, thus indicating a heterogenous response of different glomerular populations and supporting the concept that the selective damage of juxtamedullary glomeruli accounts for the proteinuria.

Animals↗
PubMed1991

Altered renal fibronectin excretion in early adriamycin nephrosis of rats.

The anticancer drug adriamycin (ADR) induces severe nonselective glomerular proteinuria in rats. The proliferation of the glomerular mesangium in chronic ADR nephrosis suggests a disturbed metabolism of extracellular matrix proteins. In the present study the structural protein fibronectin was analyzed by immunological methods in urine and plasma in two rat strains after a single injection of 5 mg of ADR/kg b.wt. After ADR administration the excretion of 220 kd-plasma fibronectin, identified by its electrophoretic mobility and Western blotting, increased. This was confirmed by quantitative measurement (ELISA) of total urinary fibronectin (ADR-treated Munich Wistar Frömter rats: 85.4 +/- 49.5 ng/hr, N = 31; controls: 1.7 +/- 0.7 ng/hr, N = 26; day 7 after ADR injection). Control urines contained distinct fragments of fibronectin with a molecular weight range of 40 to 60 kd. It is suggested that these fragments did not originate from plasma inasmuch as only little correspondence between the fibronectin patterns of urine and plasma was found, and also because in ADR-treated rats the excretion of the fibronectin fragments decreased from day 4 of ADR administration. The data suggest that the urinary fibronectin fragments are released from cellular fibronectin during the normal catabolism of the glomerular extracellular matrices, and that ADR interferes in the metabolism of matrix components. Only as a consequence of an enhanced glomerular permeability is plasma fibronectin excreted in ADR-treated rats.

Animals↗