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Biomedical subjects

J Quatacker

Publications and source records attributed to J Quatacker.

At least 19 recordsLinked to original sources
PubMed1992

Spondylarthropathy and gut inflammation: immunopathogenetic mechanisms.

In 62% of patients with spondylarthropathy (SpA) we found clinically unsuspected gut inflammation to feature acute or chronic enterocolitis on ileocolonoscopy. A proportion of patients of the latter group had subclinical Crohn's disease as demonstrated clinically, endoscopically, genetically, histologically and immunopathologically. There is a relation between the activity of the gut inflammation and clinical rheumatic symptoms. A pathogenetic mechanism is increased handling of luminal (bacterial or nutritional) antigen, hence inducing T-cell activation and intestinal inflammation. In ileal mucosal biopsies we showed two different cellular events: increased enterocytic expression of class II molecules in active inflammation and an increase of membranous (M) cells overlying lymphocytes in inflamed mucosa. Although the number of intraepithelial lymphocytes was not increased in inflammation, intraepithelial T lymphocytes had protruding processes in close apposition to the tips of epithelial plasma membranes. Lymphocytes crossing the basement membrane were a frequent finding. These features indicate that the intestinal immune response caused by increased antigen processing in the terminal ileum induces an inflammatory immunocascade responsible for the clinical picture of SpA.

Adolescent↗
PubMed1991

Persisting chloroquine-induced myasthenia?

A middle-age woman had intermittently had chloroquine as an antimalarial agent for 21 years. Although she had discontinued the drug for more than 10 years due to occurrence of a retinopathy, mild ocular myasthenic symptoms persisted. Cardiac conduction disturbances were detected as well. A quadriceps muscle biopsy revealed mild neurogenic changes and interstitial lymphorrhages. The decremental response after repetitive stimulation was reversed by edrophonium administration. The history suggests that the persisting myasthenia might have been caused by chloroquine intake.

Chloroquine↗
PubMed1990

Nephrosis in two siblings with infantile sialic acid storage disease.

The diagnosis of infantile sialic acid storage disease (ISSD) was established in two siblings on the basis of typical clinical signs and the biochemical findings of hyperexcretion and intracellular storage of free sialic acid. A severe, steroid resistant nephrosis occurred in both siblings. The activities of lysosomal enzymes, including sialidase, were normal. A combined detection method for sialic acids with Limax flavus agglutinin labelling and phosphotungstic acid staining showed severely alterated sialic acid components in epithelial kidney cells and indicate a causal relationship between the nephrosis and the underlying biochemical defect. Further observations of ISSD patients with renal involvement will prove if a separate nephropathic phenotype exists.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1990

The selective counterstaining of the plasma membrane improves the immunoelectron microscopic detection of neu protein at the cell border.

The distribution of the neu protein has been studied with two monoclonal antibodies in a post-embedding immunogold method on glycolmethacrylate sections. Labeling of the cytoplasm was due to binding to mitochondrial cristae. The detection of label at the plasma membrane was optimized by selectively staining the plasma membrane with phosphotungstic acid at low pH. Strong labeling was observed in breast carcinoma cells and faint labeling in other tissues. Brush borders were also found to be reactive. neu protein can thus be localized to baso-lateral and apical cell membranes. An important homology exists with a mitochondrial protein.

Breast↗
PubMed1989

The subcellular localization of the neu protein in human normal and neoplastic cells.

We have examined the subcellular localization of the neu protein by immunohistochemistry and immuno-electron microscopy, associated with immunoblotting of normal and neoplastic tissues with 2 monoclonal antibodies (MAbs). Immunoelectron microscopy clearly reveals that neu protein resides only on the lateral plasma membrane of the simple epithelium of the breast and on the plasma membrane of malignant breast cells. It is also found on the membranes of the microvilli and the apical vacuoles of the cells of the proximal convoluted tubule of the kidney. In the cytoplasm, the only immunoreactivity detected with both antibodies was on the membrane of the mitochondrial cristae of normal and malignant cells. Immunoblotting reveals that the molecular weight of the membrane protein is 185 and 155 kDa for the mitochondrial protein. The cell membrane staining pattern can be revealed by light microscopic immunohistochemistry only in malignant cells and is therefore specific for malignancy. The membrane expression in normal cells cannot be visualized in this way. The mitochondrial reactivity appears as a cytoplasmic granular staining when examined under the light microscope. Similar cytoplasmic staining has been described previously in other studies with other antibodies against the neu protein and has lead to speculation about its function in normal and malignant cells. However, it is demonstrated in this study that it is not the known neu-oncogene product.

Antibodies, Monoclonal↗
PubMed1987

Ultrastructural alterations in the sialic acid distribution in minimal change disease and membranous glomerulonephritis.

Kidney biopsy specimens from patients with minimal change disease and membranous glomerulonephritis were embedded in glycolmethacrylate and stained with phosphotungstic acid (PTA) at low pH. Biopsy specimens from patients without proteinuria served as a control. The PTA staining at low pH on glycolmethacrylate sections was used to study the changes in the sialic acid content of the lamina rara externa of the glomerular basement membrane. This method also gives a clear picture of the changes occurring at the epithelial cell coat and these alterations have implications on the distribution of the negative charges. In minimal change disease no alterations could be observed in the sialic acid content of the lamina rara externa. But the luminal epithelial cell coat showed obvious changes in conjunction with extensive foot process widening. In membranous glomerulonephritis with heavy deposits the staining of the lamina rara externa became almost completely negative and the foot process architecture was strongly affected. Obvious defects at the luminal epithelial cell coat, as observed in minimal change disease, were also found regularly. The alterations at the epithelial cell coat are tentatively related to the selective proteinuria reported in minimal change disease. In addition the non-selective proteinuria observed in non-minimal glomerulopathies, may find its origin in the absence of sialic acid molecules from the lamina rara externa.

Basement Membrane↗
PubMed1987

Ehlers-Danlos syndrome type I: a clinical and ultrastructural study of a family with reduced amounts of collagen type III.

Ehlers-Danlos syndrome (EDS) type I was diagnosed in an 18-year-old girl on the basis of marked skin hyperextensibility with generalized loose-jointedness, pigmented paper-tissue scars, and a pronounced tendency to bruising. Her father and one of her sisters showed a similar phenotype. Her mother was normal. Light microscopy of skin biopsies showed large, irregular collagen fibres in the father and daughter, with normal findings in the mother. Electron microscopy of the skin sections revealed a variation in diameter and shape of the collagen fibrils as well as slight dilatation of the rough endoplasmic reticulum of fibroblasts in father and daughter, but normal findings in the mother. Cultured fibroblasts did not show these changes. Measurements of collagen synthesis by fibroblast cultures showed that type III collagen levels were reduced to 50% of normal in the father and daughter, and were normal in the mother. The alpha I (III) proteins had a normal molecular weight, determined by SDS-PAGE electrophoresis. The phenotypes and biochemical results in the family members tested were compatible with autosomal dominant transmission. To our knowledge, this is the first report of a type III collagen deficiency in Ehlers-Danlos syndrome type I. The findings in this family, especially the pronounced bruising tendency, illustrate the heterogeneity within type I EDS.

Chromatography, Thin Layer↗
PubMed1987

Decrease in the sialoglycoprotein content of the glomerular basement membrane in experimental nephrosis.

Phosphotungstic acid at low pH on glycolmethacrylate sections allows the detection of sialic acid groups in the lamina rara externa of the glomerular basement membrane. This staining procedure was used to study the alterations in puromycin aminonucleoside nephrosis and adriamycin nephrosis. In both model systems defects were detected in the sialic acid content of the lamina rara externa and the epithelial cell coat was also affected. The possible role of sialic acid in glomerular filtration is discussed.

Animals↗
PubMed1986

Alterations in the sialic acid content of the rat glomerular filter in aminonucleoside nephrosis.

A daily injection protocol with puromycin aminonucleoside (PAN) causes loss of sialic acid from the glomerular filter. These changes have been studied previously by colloidal iron staining, but we have recently shown that phosphotungstic acid (PTA) at low pH allows the demonstration of sialic acid groups in the glomerular basement membrane in ultrathin sections of glycolmethacrylate(GMA)-embedded rat kidney. With this technique the slit diaphragm is seen as a continuation of the luminal cell coat and the method also gives an idea of the sialic acid distribution at the podocyte plasma membrane. The availability of this method made it possible to reevaluate the results obtained earlier in aminonucleoside (PAN) nephrosis indicating a decrease in the sialic acid content of the glomerulus. Although there are changes in the epithelial architecture, the ultrastructural appearances of the basement membrane are only slightly altered in PAN nephrosis. Detachment of epithelial cells was variable in different animals. Seven days after the first injection of PAN, staining with PTA revealed local defects in the lamina rara externa which later became more extensive. In PAN-treated animals the luminal cell coat showed reduced staining and large areas of the plasma membrane were completely devoid of a cell coat. These changes coincided with the onset of heavy proteinuria. The results indicate that both the basement membrane and the epithelial plasma membrane are affected in PAN nephrosis, as revealed by decreased staining for sialic acid-containing molecules in the basement membrane and by changes in the epithelial cell coat. The defects in the cell coat material point to functional alterations at the level of the slit pores and it is suggested that the decrease in sialic acid content of the lamina rara externa may be partly responsible for defects in the size-selective filtration barrier in PAN nephrosis.

Animals↗
PubMed1985

Demonstration of sialic acid groups in the glomerular basement membrane of the rat with phosphotungstic acid at low pH.

This paper reports an unrecognized aspect of phosphotungstic acid staining at low pH. It provides an on-section staining method in which sialic acid-containing molecules can be demonstrated in the laminae rarae of the rat glomerular basement membrane. The staining in the basement membrane became negative after perfusion with the following cations: protamine sulphate, hexadimethrine, Alcian Blue, Ruthenium Red and Toluidine Blue. Blocking was not achieved with Alcian Blue at about pH 1. The staining was also abolished after mild methylation and demethylation restored the contrast. This is suggestive of the involvement of carboxyl groups. Prior digestion with pronase, trypsin and neuraminidase rendered the laminae rarae negative, whereas hyaluronidase, chondroitinase ABC and crude heparinase were without effect. This indicates that sialic acid groups are detected by this method and that heparan sulphate does not interfere. The staining of the epithelial plasma membrane, also carrying sialic acid groups, remained positive after neuraminidase treatment. It is presumed that this method can be applied successfully for detecting changes in the sialic acid content of the laminae rarae in rat glomerular basement membranes under normal and pathological conditions.

Animals↗
PubMed1976

Gastric xanthoma.

Gastric xanthoma (GX) consists of a small yellowish lesion of the gastric mucosa, frequently of multiple occurrence; histologically, there is an accumulation of lipid-laden histiocytes in the lamina propria. Seven cases are reported. One patient also had jejunal localizations. There is no correlation with hypercholesterolemia but in four cases a slight hypertriglyceridemia was found. A control gastroscopy, performed in four cases, revealed no changes in the first patient but a decrease in size in a second and the disappearance of GX in two other patients.

Aged↗
PubMed1975

Endocytosis and multivesicular body formation in rabbit luteal cells during pseudopregnancy.

Horseradish peroxidase (HRP) was injected directly into the corpora lutea of rabbits on different days of pseudopregnancy. Young luteal cells have also been incubated "in vitro" in a medium containing horseradish peroxidase. In the "in vivo" experiments the 5 to 9 days old luteal cells take up far more horseradish peroxidase than the older ones (14-20 days). Different types of endocytic vacuoles, MvB's and also some DB's are already peroxidase positive shortly (15-20 min) after injection of the tracer. In the "in vitro" experiments the cells are more heavily loaded. The normal morphology of pale, dense and terminal MvB's is also described and staining with PTA at low pH provides further information on changes occurring in the MvB's. The various findings on multivesicular bodies are compared and two possible pathways for endocytic vacuoles are proposed: one to DB's the other to MvB's. The related phenomena of the uptake of material and the internalization of plasma membrane are discussed in the light of the possible function of endocytosis in luteal cells.

Animals↗