Biomedical subjects

H Holthöfer

Publications and source records attributed to H Holthöfer.

At least 19 recordsLinked to original sources

PubMed1999

Podocalyxin in rat platelets and megakaryocytes.

Podocalyxin is a membrane protein of rat podocytes and endothelial cells. It has not been described in other cell types, and no amino acid or DNA sequence data are available about it. Here we show that podocalyxin antigens are present in rat platelets and megakaryocytes. In resting platelets, the antigens are mainly intracellular but become surface exposed after thrombin stimulation, as shown by immunofluorescence and flow cytometry. By Western blotting, platelet podocalyxin has an apparent Mr of 140,000. Cytocentrifuge slides of rat bone marrow show that anti-podocalyxin antibodies recognize large polyploid cells also expressing CD62P, indicating that the cells are megakaryocytes. From a rat glomerular cDNA library we isolated a clone covering the carboxyl-terminal nucleotides of rat podocalyxin. Its putative transmembrane or intracellular domains are 100% or >93% identical, respectively, with the human and rabbit podocalyxin-like proteins. The truncated extracellular domain extends to include two of the four conserved cysteines shared by podocalyxin-like proteins. By Northern blotting, a 5.5-kb renal cortical transcript is seen. By in situ hybridization, cRNA probes recognize podocytes, endothelial cells, and megakaryocytes, and by reverse transcription polymerase chain reaction, platelets are shown to contain podocalyxin mRNA. Our results show that rat podocalyxin is a homologue of the previously cloned podocalyxin-like proteins and suggest that also in mammals podocalyxin has a role in hematopoiesis, as previously shown in the chicken.

Amino Acid Sequence↗

PubMed1999

Altered gene expression and functions of mitochondria in human nephrotic syndrome.

The molecular basis of glomerular permselectivity remains largely unknown. The congenital nephrotic syndrome of the Finnish type (CNF) characterized by massive proteinuria already present but without extrarenal symptoms is a unique human disease model of pure proteinuria. In search of genes and pathophysiologic mechanisms associated with proteinuria, we used differential display-PCR to identify differences in gene expression between glomeruli from CNF and control kidneys. A distinctly underexpressed PCR product of the CNF kidneys showed over 98% identity with a mitochondrially encoded cytochrome c oxidase (COX I). Using a full-length COX I cDNA probe, we verified down-regulation of COX I mRNA to 1/4 of normal kidney values on Northern blots. In addition, transcripts of other mitochondrially encoded respiratory chain complexes showed a similar down-regulation whereas the respective nuclearly encoded complexes were expressed at comparable levels. Additional studies using histochemical, immunohistochemical, in situ hybridization, RT-PCR, and biochemical and electron microscopic methods all showed a mitochondrial involvement in the diseased kidneys but not in extrarenal blood vessels. As a secondary sign of mitochondrial dysfunction, excess lipid peroxidation products were found in glomerular structures in CNF samples. Our data suggest that mitochondrial dysfunction occurs in the kidneys of patients with CNF, with subsequent lipid peroxidation at the glomerular basement membrane. Our additional studies have revealed similar down-regulation of mitochondrial functions in experimental models of proteinuria. Thus, mitochondrial dysfunction may be a crucial pathophysiologic factor in this symptom.

Adolescent↗

PubMed1999

Renoprotective effects of captopril in hypertension induced by nitric oxide synthase inhibition in experimental nephritis.

OBJECTIVE: To investigate effects of angiotensin I converting enzyme (ACE) inhibition in experimental nephritis during chronic inhibition of nitric oxide (NO) synthase. METHODS: Rats with and without autoimmune Heymann nephritis were treated with a NO synthase inhibitor L-NAME (50 mg/100 ml) and/or an ACE inhibitor captopril (20 mg/100 ml) in drinking water for 12 weeks. Urinary cGMP excretion was used as an indirect measure of NO activity. Blood pressure, urinary albumin, nitrite and nitrate levels, plasma ANP, and plasma renin activity were measured. Kidneys were examined with light microscopy and immunohistochemical methods. RESULTS: Captopril treatment protected rats receiving L-NAME and none of the captopril-treated rats died. Mortality was greatest in the nephritis-L-NAME (57%) and L-NAME (43%) groups. Captopril normalized cGMP excretion, blood pressure, and prevented partly the appearance of albuminuria. Peritubular infiltration of mononuclear cells was clearly enhanced in the nephritis-L-NAME group (found in 80% of the rats) as compared with the nephritis (20%), L-NAME (40%), and control (0%) groups. The peritubular cell infiltration caused by L-NAME was prevented by captopril treatment. L-NAME-induced hypertension was associated with cardiac hypertrophy and this was prevented by captopril. CONCLUSIONS: NO may play an important renoprotective role in disease progression of chronic membranous glomerulonephritis. Captopril prevents L-NAME-induced hypertension, improves survival, and ameliorates renal damage in this type of nephritis. Dysfunction of renal NO pathways may be an important factor causing progressive renal damage in chronic nephritis. Our results suggest that the dysfunctional renal NO system may be beneficially activated by ACE inhibitors.

Albuminuria↗

PubMed1998

Immune-mediated congenital heart block (CHB): identifying and counseling patients at risk for having children with CHB.

OBJECTIVE: To identify patterns of maternal antibodies associated with an increased risk of having a child with congenital heart block (CHB) and to provide a basis for counseling women with a previously affected child. METHODS: This retrospective clinical study of the obstetric histories of 46 Finnish women with a CHB child compared the strength and specificity of the immune response to SS-A/Ro and SS-B/La, as determined by immunoblot and ELISA, in 44 affected women with 85 women with systemic lupus erythematosus (SLE) and 32 women with primary Sjögren's syndrome (SS) with healthy children. RESULTS: High levels of anti-SS-A/Ro and anti-SS-B/La by practically all assays were associated with a significantly increased risk of having a CHB child. The best single test to identify high-risk mothers was anti-52 kd SS-A/Ro by immunoblot (OR 18.9), and it was the only assay to detect mothers at increased risk of CHB as compared with controls with primary SS. Low risk of CHB was indicated by undetectable or low levels of antibodies in the ELISA assays and no reactivity on immunoblot. Mothers with a previous child with CHB had a history of fetal loss (mostly spontaneous abortions) or a history of recurrent fetal losses (> or = 3) slightly more often than controls. Late-trimester obstetric complications in non-CHB pregnancies were insignificant. The relative risk for a female child compared with a male child to have CHB was 1.9 (1.2-2.9, P = .009), and the risk of the mother having another child with CHB was 12% (4 of 34). CONCLUSION: Although there is no unique antibody profile specific for CHB, mothers with a high or low risk of having a child with CHB can be identified. Female children appear to have an increased risk of CHB, but the risk of the mother having another child with CHB is low.

Abortion, Spontaneous↗

PubMed1998

Tyrosine phosphorylation of p72syk induced by anti-9-O-acetyl GD3 antibodies in human peripheral blood mononuclear cells.

We have previously shown that a subpopulation of peripheral blood CD4+ T-cells are strongly positive for the ganglioside 9-O-acetyl GD3. Treatment of peripheral blood mononuclear cells (PBMC) with monoclonal anti-9-O-acetyl GD3 antibodies (MoAb 27A) induced a dose-dependent proliferative response in the cells. Here we show that binding of 27A IgG to PBMC induces rapid tyrosine phosphorylation of p72syk and mobilization of phosphoinositides. Equal phosphorylation was not seen after stimulation of PBMC with anti-GD3 antibodies (MoAb R24) despite the apparent similar cell surface distribution of the two gangliosides. This suggests that the O-acetyl modification enhances the signal transduction mediated by GD3 ganglioside.

Antibodies, Monoclonal↗

PubMed1998

Morphologic changes suggesting abnormal renal differentiation in congenital nephrotic syndrome.

Retrograde differentiation (or dedifferentiation) has recently been proposed as a pathogenetic mechanism involved also in various renal diseases. Here we studied whether evidence of these mechanisms can be found in the kidneys of patients with congenital nephrotic syndrome of the Finnish type (CNF). These patients show isolated massive proteinuria but no primary symptoms from any other organ systems. For the analysis we used antibody markers of early (fibronectin, stem cell factor, Wilms' tumor gene product, cytokeratin) and later (laminin, midgestation and kidney, heparin binding growth-associated molecule) stages of nephron differentiation as well as for apoptosis (acridine orange staining), rescue from apoptosis (anti-Bcl-2 antibodies) and cell proliferation (antibodies to proliferating cell nuclear antigen). In the peritubular spaces atypically organized areas were found which appeared positive with markers of low stages of differentiation, but neither abnormal cell proliferation nor activation of the apoptotic pathway could be detected. As morphologic signs of abnormal tissue organization, we found clusters of tightly compacted and large glomeruli corresponding to the size of two to three normal glomeruli. However, all individual glomerular cell compartments (mesangial, endothelial, visceral epithelial cells) appeared balanced in relative cell numbers. Together these results may indicate abnormal early mesenchymoepithelial tissue interaction leading to excessive and poorly organized formation of glomeruli. This could be causally related also to the serious functional immaturity of CNF kidneys presented as isolated proteinuria.

Adult↗

PubMed1997

Characterization of nephropathy induced by immunization with high molecular weight dextran.

BACKGROUND: Injection of DEAE dextran into Lewis rats can produce proteinuria and has been reported as a model of IgA nephropathy. METHODS: Cationic diethyl aminoethyl (DEAE) dextran of molecular weight 500 kDa was injected into male Lewis rats. After a pre-immunization period of 3 weeks, the animals were divided into two groups: group 1 (n = 14) received daily i.v, injections of 3.5 mg of antigen, group 2 (n = 14) was injected with 1.5 mg three times per week for a total period of 6 weeks. I.v. treatment was initiated with gradually increasing doses of DEAE dextran in both groups for 1 week, after which the maintenance dose was reached. RESULTS: We observed the appearance of proteinuria in a nephrotic range after 5 weeks of i.v. injections in group 1 (urinary excretion: 332 +/- 83 mg/24 h, controls: 53 +/- 14 mg/24 h). In group 2, the proteinuria was almost equal to protein excretion of healthy rats of the same weight (67 +/- 20 mg/24 h). The serum and urine creatinine were normal. By light microscopy of kidney biopsies, the presence of focal and segmental proliferation of mesangial cells after 6 weeks of i.v. injections was identified. Immunohistochemistry revealed no deposition of IgA, IgM, IgG, or C3. Using anti-ED1 antibodies, there was no evidence of interstitial infiltration of monocytes/macrophages after 6 weeks of i.v. injections. Staining for proliferating cell nuclear antigen (PCNA) did not show the presence of proliferating cells either in glomeruli or in the interstitium. Staining with FITC-WGA lectin revealed focal and segmental loss of the negative charge in the capillary wall. By electron microscopy there was deposition of dextran in the basal membrane and segmental and focal damage of the podocyte foot processes. As the chemokine RANTES may be involved in glomerular injury, we examined the kidneys of proteinuric and non-proteinuric rats for the presence of RANTES. By indirect immunofluorescence only the proteinuric rats showed RANTES deposition in the mesangium. CONCLUSIONS: Injection of rats with DEAE dextran leads to dose-dependent proteinuria without deposition of immune complexes but with podocyte damage. This is associated with local expression of the chemokine RANTES which may play a role in proteinuria of glomerular disease.

Animals↗

PubMed1996

Sequential morphologic events during apoptosis of human neutrophils. Modulation by lipoxygenase-derived eicosanoids.

Dual-laser flow cytometry, based on the properties of the DNA-binding dyes Hoechst 33342 and propidium iodide, was used, with light and electron microscopy and DNA fragmentation studies, to define the influence of lipoxygenase-derived eicosanoids on apoptosis of human polymorphonuclear neutrophils (PMN) in vitro. Apoptosis was characterized by progression through an early apoptotic phase characterized by condensation of chromatin and coalescence of nuclear lobes, to a late apoptotic phase characterized by nuclear degradation and evanescence, and secondary necrosis. Prolonged exposure of PMN to leukotriene B4 (LTB4) afforded dose-dependent inhibition of constitutive PMN apoptosis (percentage of normal and apoptotic PMN, respectively, after aging for 18 h: vehicle, 30.5 +/- 2.7% and 61.8 +/- 3.2%; LTB4 10(-7) M, 57.6 +/- 1.2% and 37.6 +/- 1.0%) and apoptosis triggered by the classic peptide chemoattractant FMLP. In contrast, apoptosis was not affected by the LTB4 precursor 5(S)-hydroxyeicosatetraenoic acid (HETE), the omega-oxidation LTB4 metabolites 20-hydroxy-LTB4 and 20-carboxy-LTB4, the cysteinyl leukotriene LTC4, the 15-lipoxygenase product 15(S)-HETE, or the lipoxygenase interaction product lipoxin A4. The anti-apoptotic effect of LTB4 was mimicked by 20,20,20-trifluoro-LTB4, LTB4-dimethylamide, and 14,15-dehydro-LTB4, and was blunted by pertussis toxin and genistein, inhibitors of G alpha i GTP-binding proteins and tyrosine kinases, respectively, but not by staurosporine, 15(S)-HETE, or lipoxin A4. This unique pharmacologic profile suggested that LTB4 attenuated apoptosis through activation of cell surface receptors and signaling events distinct from those involved with PMN trafficking, degranulation, and respiratory bursts.

Animals↗

PubMed1996

Cytokines, adhesion molecules, and cellular infiltration in nephropathia epidemica kidneys: an immunohistochemical study.

Puumala hantavirus-induced nephropathia epidemica (NE) is an important cause for an acute reversible renal failure in Scandinavia, European Russia, and the Balkans. The characteristic histopathological renal finding is an acute tubulointerstitial nephritis. Mild to massive proteinuria, hematuria, and a rise in the serum creatinine level are typically seen. The pathogenetic mechanisms of NE kidney failure are incompletely understood. Therefore we studied the infiltrating cell populations and local expression of cytokines and growth factors in the kidney during the acute disease. Results of the histological and immunohistological studies of eight kidney biopsies show mild to moderate interstitial infiltration of lymphocytes, plasma cells, monocytes/macrophages, and polymorphonuclear leukocytes, mainly eosinophilic granulocytes and neutrophils. An increased expression of the cytokines tumor necrosis factor-alpha, transforming growth factor-beta, and platelet-derived growth factor was seen at the same sites mainly in the peritubular area of the distal nephron. Concomitantly also at the same locations expression of the endothelial adhesion molecules ICAM-1, VCAM, and PECAM was seen. Light microscopic changes in tubuli were common. Interestingly, despite the often massive transient proteinuria, no marked changes were seen in the glomeruli of NE kidneys. No evidence of Puumala virus was found in the kidney biopsies.

Adult↗

PubMed1996

Sphingolipid activator proteins in a human hereditary renal disease with deposition of disialogangliosides.

Congenital nephrotic syndrome of the Finnish type is a recessively inherited renal disease with glomerular deposits of the disialoganglioside O-acetyl-GD3. Sphingolipid activator proteins (saposins) stimulate the degradation of glycosphingolipids by lysosomal enzymes, and defects in saposins cause accumulation of substrate lipids in the affected tissues in lysosomal storage disease. Here we report a study of the role of saposins in the accumulation of O-acetyl-GD3 in kidneys of congenital nephrotic syndrome patients. At the mRNA level, the expression of saposin precursor in diseased kidneys appeared normal, and the nucleotide sequence analysis of cDNA clones did not reveal abnormalities in the prosaposin gene. Immunohistologically, saposins were localized mainly to the epithelial cells of the distal renal tubules or to the parietal epithelial cells of glomeruli. In the nephrotic syndrome kidneys, the staining pattern was highly granular and appeared mostly in the apical part of the epithelial lining, unlike the control kidneys. These results show that a major site of ganglioside metabolism is located in the distal nephron. Furthermore, these results suggest that saposins are not directly involved in the metabolism of the terminal sialic acids of disialogangliosides in the nephrotic syndrome kidneys.

Adult↗

PubMed1996

Mechanisms of proteinuria: vascular permeability factor in congenital nephrotic syndrome of the Finnish type.

Vascular permeability factor (VPF) is the most potent known mediator of vessel wall permeability. In the kidney, it is expressed preferentially in the glomerular visceral epithelial cells. The present study was designed to clarify the proposed role of VPF in diseases with increased glomerular permeability as here exemplified by the congenital nephrotic syndrome of the Finnish type (CNF). For this, we studied the expression levels and the sites of synthesis of VPF and its kinase-insert domain receptor (KDR) in kidneys of patients with CNF using Northern and in situ hybridization techniques and immunohistologic staining with anti-VPF antibody. In addition, we extended the study to include analysis of fetal kidney tissue and cultured glomerular cells of normal and CNF kidneys. In CNF and in normal kidneys VPF was localized in the visceral epithelial aspect of the glomeruli and in the collecting ducts, as also earlier described. A new finding was its localization also in the juxtaglomerular area. The VPF receptor KDR was found in glomeruli in the endothelial cells, but it was not detected in the peritubular capillaries. no consistent differences in the levels of VPF or KDR mRNAs or in their sites of production were seen in CNF and control samples. Also the distribution of VPF antigen in the CNF kidneys and normal kidneys was similar. Thus, we propose that VPF and KDR are not directly involved in the pathogenesis of the proteinuria in CNF.

Cells, Cultured↗

PubMed1996

Decrease of glomerular disialogangliosides in puromycin nephrosis of the rat.

Puromycin aminonucleoside nephrosis (PAN) is a model for human minimal change nephropathy induced in rats by injection of puromycin. In PAN, defective sialylation of a major sialoprotein of podocytes, podocalyxin, has been demonstrated and the consequent decrease of anionic charge suggested as a causative factor for increased glomerular permeability and proteinuria. Whether defective sialylation is a general feature of PAN affecting also glomerular glycosphingolipids is not known. We have shown that rat glomeruli are rich in disialogangliosides GD3 and O-acetyl GD3, the functions of which are not known. Here, we made a sequential analysis of the glomerular gangliosides, especially of GD3 and its O-acetyl derivative in acute PAN using immunohistochemical and biochemical techniques and compared the results with another rat model of glomerular disease, Heymann nephritis. The prominent immunohistochemical finding was the almost total disappearance of glomerular O-acetyl GD3 and a substantial decrease of its precursor GD3 peaking at 10 days after injection of puromycin. Segmental areas lacking these gangliosides remained in glomeruli still at 30 days after injection. The response was dose dependent. Semiquantitative analysis by thin layer chromatograms showed that O-acetyl GD3 was decreased by 41% already at 3 days and by 60% at 10 days after injection of puromycin. Also GD3, the immediate precursor of O-acetyl GD3, was decreased by 20 and 19%, respectively, at 3 and 10 days after injection. At 3 days after injection, overt proteinuria had not started. At these times, no other changes were observed in the glomerular gangliosides. The decrease of glomerular GD3 and O-acetyl GD3 indicates a decrease of GD3 synthase activity and perhaps of O-acetyltransferase activity in PAN nephrosis. As these changes preceded the overt proteinuria, they may have a causal relationship to it. In the glomeruli of Heymann nephritic rats, no similar changes were seen, suggesting that the sialylation defect is not due to proteinuria but is a consequence of targeted puromycin action on cells.

Albuminuria↗

PubMed1995

Increased renal expression of cytokines and growth factors induced by DOCA-NaCl treatment in Heymann nephritis.

DOCA-NaCl treatment causes hypertension, accelerates development of proteinuria, and leads to glomerulosclerosis in rats with autoimmune Heymann nephritis. To study the mechanisms of kidney injury induced by renal haemodynamic load in chronic nephritis, we studied by immunohistochemistry the local expression of various cytokines, growth factors and adhesion molecules in the kidneys of Heymann nephritic rats with or without DOCA-NaCl-induced hypertension. The DOCA-NaCl-nephritis group developed hypertension and marked renal enlargement as compared with the nephritis group, the DOCA-NaCl group, and the controls. Albuminuria appeared earlier and was heavier in the DOCA-NaCl-nephritis group compared with the nephritic rats without DOCA-NaCl. Expression of IL-6, TNF-alpha, GM-CSF, b-FGF, NGF, TGF-beta, and ICAM-1 was enhanced in the kidneys of the DOCA-NaCl-nephritis group as compared with other groups, localized mainly in the glomerular mesangium (IL-6, GM-CSF, TGF-beta), glomerular and peritubular endothelium (ICAM-1), and collecting ducts (TNF-alpha, b-FGF, NGF, TGF-beta), possibly associated with the observed tubulointerstitial mononuclear cellular infiltration. Thus in autoimmune Heymann nephritis, DOCA-NaCl treatment causes hypertension and increased renal mass together with upregulation of local cytokine and growth factor production, which may further aggravate hypertension and accelerate progression of renal damage.

Animals↗

PubMed1995

Glomerular antigens in severe hereditary nephrosis.

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.

Autoantigens↗

PubMed1995

Glomerular anionic charge in congenital nephrotic syndrome of the Finnish type.

Decrease of the anionic charge of the glomerular basement membrane and especially the reduced amount of heparan sulphate proteoglycan in the lamina rara externa has been suggested to be the basic pathogenetic defect in congenital nephrotic syndrome. In the present study the anionic charge of glomeruli was examined in the congenital nephrotic syndrome of the Finnish type and in controls using cationic stains (polyethyleneimine, Ruthenium Red) in electron microscopy. Chondroitinase and heparinase treatments were used to characterize further the anionic elements detected. Scanning electron microscopy (SEM) was used in addition to transmission electron microscopy (TEM) to examine the tridimensional structure and secondary changes of podocytes in this syndrome. The number (mean +/- SD) of polyethyleneimine granules per 1 micron length of lamina rara externa of the glomerular basement membrane was 24.9 +/- 4.5 in control and 23.2 +/- 4.3 [corrected] in congenital nephrotic syndrome subjects. The Ruthenium Red staining pattern was closely similar in syndrome and control kidneys. The granules evident after staining with either cationic stain were seen after chondroitinase but not after heparinase treatment in control as well as in syndrome patient kidney samples. No denuded areas of basement membrane in 42 glomeruli from four syndrome patients were found in SEM. In conclusion, the amount of anionic sites in the lamina rara externa as detected by either cationic stain was comparable to controls. These results do not support the hypothesis of decreased anionic sites in the lamina rara externa of the glomerular basement membrane in congenital nephrotic syndrome of the Finnish type.

Anions↗

PubMed1995

The glomerular mesangium: studies of its developmental origin and markers in vivo and in vitro.

Cultured mesangial cells are widely used to explore their role in kidney glomerular functions, but methods to reliably identify these cells in vivo and in vitro are lacking. Furthermore, the proposed relationship of mesangial cells to e.g. fibroblasts and smooth muscle cells has not been systematically studied. Here we wanted to search for markers of practical use also in identifying cultured mesangial cells, and to apply these markers in a study of the origin of glomerular mesangium. No epitopes specific for only mesangial cells could be identified, and no evidence of their true relationship with neural or lymphocytic lineages could be found. Findings with the variety of markers used suggest that mesangial cells may be indistinguishable from smooth muscle cells and fibroblasts. A panel of antibodies, including those against Thy1.1, smooth muscle actin, desmin, cellular fibronectin and beta 1 integrin alpha 1 and alpha 5 chains, and Wistaria floribunda (WFA) and Ricinus communis (RCA I) lectins, were found useful for mesangial cell detection in vivo and in vitro. The origin of glomerular mesangial cells could not be conclusively determined, although the results indirectly suggest that mesangial cells together with endothelial cells migrate to the glomerulus from the outside.

Animals↗

PubMed1994

Nephron segment and cell-type specific expression of gangliosides in the developing and adult kidney.

Despite the increasing knowledge of the role of gangliosides in normal and diseased tissues, little is known of the presence, distribution and functions of these molecules in the kidney. In this study we analyzed the main gangliosides of isolated glomeruli and cortical, medullary and papillary fractions of the human, rat and bovine kidneys biochemically. In addition, we used immunohistochemistry to visualize the distribution of GM1/GM2, GD2, GD3 and O-acetyl GD3 gangliosides along the nephron. Furthermore, we explored the species specific expression of gangliosides by comparing those from the rat, bovine and human kidney, and studied the pattern of ganglioside expression during development. In glomeruli, cortical tubuli, medullae and papillae, a relatively simple pattern of main gangliosides was observed as revealed by thin layer chromatographic (TLC) analysis in each species studied. Furthermore, considerable changes in the glomerular gangliosides during maturation were observed, with a complex type of gangliosides predominating during the fetal age and with a preference to more simple precursors upon maturation. Interestingly, the immunohistochemical detection revealed a distinct pattern of ganglioside compartmentation to various nephron segments or cell types. These findings provide a basis for studying the role of segment- and cell type-specific gangliosides for local functions.

Aging↗

PubMed1994

Characterization of platelet-activating factor synthesis in glomerular endothelial cell lines.

Platelet-activating factor synthesis in two transformed lines of glomerular endothelial cells was characterized and contrasted with platelet-activating factor production in macrovascular-derived endothelial cells as well as with glomerular cells of mesenchymal origin. Platelet-activating factor synthesis was assessed in intact cells and in cell-free preparations. Glomerular endothelial cells constitutively synthesize bio-active alkyl-PAF, and this basal activity can be chronically augmented by various inflammatory and thrombotic agents. In contrast, thrombin-mediated platelet-activating factor formation in bovine pulmonary aortic endothelial cells as well as in glomerular mesangial cells is acute and transient. The potential role of anti-inflammatory prostanoids to function as negative feedback modulators of thrombin- or endothelin-mediated platelet-activating factor synthesis was also investigated, as the synthesis of platelet-activating factor is often associated with the formation of these prostanoids. Indomethacin augmented receptor-mediated platelet-activating factor synthesis while prostanoids of the E and I series reduced agonist-stimulated PAF synthesis. In summary, the unique capacity of glomerular endothelial cells to respond to inflammatory stimuli with sustained platelet-activating factor synthesis is a clear indication of this cell's pivotal role in augmenting the inflammatory response in the limited environment of the glomerulus.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗