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Biomedical subjects

F Roels

Publications and source records attributed to F Roels.

At least 109 records · Page 6Linked to original sources
PubMed1983

Peroxisomes (microbodies) in human liver: cytochemical and quantitative studies of 85 biopsies.

The number, intracellular distribution, and staining characteristics of human hepatocellular peroxisomes that had been made visible by cytochemical staining for catalase were evaluated in biopsies from 75 patients with hepatic, inflammatory, or malignant disease and ten normal individuals. Intensity of staining was found to be proportional to enzymatic activity by microspectrophotometry. Scanning transmission electron microscopy (STEM) image analysis demonstrated an inverse relationship between peroxisomal size and contrast. Peroxisomes were more abundant, and often concentrated in a perinuclear configuration in cholestatic and cirrhotic livers. Decreased peroxisomal staining was common in cholestasis, cirrhosis, hepatitis, and in almost all patients with malignancies, both with and without hepatic metastases.

Biopsy↗
PubMed1981

Quantitation of catalase activity by microspectrophotometry after diaminobenzidine staining.

The absorbance of the reaction product of catalase staining with diaminobenzidine is linearly proportional to enzyme activity. This is shown in semithin Epon sections of model systems containing serum albumin and catalase from bovine or guinea pig liver. Absorbance measurements were also performed on semithin sections of guinea pig liver, and from these, the activity of cytoplasmic (extraperoxisomal) catalase has been derived.

3,3'-Diaminobenzidine↗
PubMed1979

Cytochemistry of human catalase. The demonstration of hepatic and renal peroxisomes by a high temperature procedure.

The cytochemical demonstration of marker enzymes for subcellular organelles permits light microscopic analysis of their structure and function in normal and diseased tissues. Currently available staining procedures for the peroxidatic activity of catalase in peroxisomes of plant and animal cells yield weak and inconsistent light microscopic staining when applied to human tissues. We have developed a simple and sensitive high temperature procedure that clearly and reproducibly stains these abundant, but poorly understood, organelles in biopsy specimens of human liver and kidney. This method utilizes formaldehyde fixation, a modified diaminobenzidine (DAB) medium, incubation at 45 degrees C and postosmication for both light and electron microscopy.

Catalase↗
PubMed1977

Spontaneous shedding of plasma membrane fragments by human cells in vivo and in vitro.

Human duodenal fluid, secretion fluid of a villous adenoma of the rectum, urine and culture medium of HeLa cells contain plasma membrane fragments which can be revealed by electrophoresis in different media, gel filtration on Sepharose 4-B, electron microscopy and cytochemistry. They carry plasma membrane enzymes (alkaline phosphatase EC 3.1.3.1, leucine aminopeptidase EC 3.4.1.1, 5'-nucleotidase EC 3.1.3.5, maltase EC 3.2.1.20) in the same ratio as the membranes of the cells of origin. Equilibrium density centrifugation results in recovery of these plasma membrane fragments at density 1.190 (g/ml) in CsCl, 1.165 (g/ml) in sucrose, and 1.135 (g/ml) in metrizamide. Similar plasma membrane fragments were decribed previously in the serum of certain liver patients. These observations give evidence that shedding of whole plasma membrane fragments (koinozymic shedding) is a widespread feature of viable cells.

Aged↗
PubMed1976

Cytochemical demonstration of extraperoxisomal catalase. I. Sheep liver.

In sheep hepatocytes catalase activity was demonstrated both within peroxisomes and within the cytosol. In the cytosol the catalase reaction product is contiguous to the plasma membrane and surrounds the nuclei, rough endoplasmic reticulum, cisternae, mitochondria and Golgi apparatus. This is the first cytochemical demonstration of guine extraperoxisomal catalase. No catalase reaction product was seen in the cytosol of nonparenchymal cells. To demonstrate catalase, both glutaraldehyde and formaldehyde fixation were used, followed by a diaminobenzidine technique modified from Novikoff and Goldfischer. Control reactions were performed to distinguish catalase reaction product from adsorption of oxidized diaminobenzidine and from precipitate due to oxidase-, peroxidase- or heat-stable peroxidatic activities. The results were evaluated in the light and electron microscopes.

Animals↗
PubMed1975

Cytochemical discrimination between catalases and peroxidases using diaminobenzidine.

The influence on diaminobenzidine staining of four variables: prefixation in aldehyde, temperature and pH of incubation, and H2O2 concentration, was investigated in catalase-, as well as in peroxydase-containing material. Catalase from five different sources and five types of peroxidase were examined. It is concluded: (a) when cells are incubated without prior fixation, in a DAB medium at room temperature and pH 7.3 with 0.003% H2O2, peroxidases produce a visible cytochemical stain, while catalases do not; (b) the cytochemical reaction elicited by catalases is stimulated by prior aldehyde fixation in specified conditions, and incubation at 45 degrees C and pH 9.7 with 0.06% H2O2; (c) under the latter circumstances several peroxidases also stain. Ultrastructural preservation is satisfactory in tissues incubated prior to fixation.

Aminobiphenyl Compounds↗