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U Ott

Publications and source records attributed to U Ott.

9 recordsLinked to original sources
PubMed1999

Colocalization of BAX and BCL-2 in small intestine and kidney biopsies with different degrees of DNA fragmentation.

Morphological changes associated with apoptosis are closely correlated with the expression of specific proteins. However, the cause-effect relationships between the expression of these proteins and DNA degradation are barely known. For studying expression of apoptosis-related proteins in relation to different degrees of DNA fragmentation, the small intestine with its spatially organized continuum of proliferation, differentiation and death is a very useful preparation. Enterocytes towards the apex of the villi become increasingly susceptible to apoptosis. Here, this "apoptotic gradient" is used to demonstrate the presence of BAX and BCL-2 proteins in the cytoplasm of cells at the onset of apoptosis. In semithin serial sections of the small intestine, BAX, BCL-2 and DNA fragmentation were demonstrated. BAX and BCL-2 are always colocalized and only in cells with fragmented DNA. The gradient of BAX or BCL-2 staining is similar to the gradient of DNA fragmentation. Immunoreactivity for BCL-2 or BAX is most intense in cells that are prone to become apoptotic next in the course of cellular turnover but not in cells in an advanced apoptotic state, showing strongly condensed chromatin. When using the same technique on semithin sections of kidney biopsies, containing epithelia with low cellular turnover, we found DNA fragmentation mainly in the epithelial cells of the distal tubules. Similar to the situation in the enterocytes, BAX staining was confined to the cytoplasm of epithelial cells with a moderate degree of DNA fragmentation and reduced in epithelial cells with a high degree of DNA fragmentation. In contrast to the situation in the small intestine, very low levels of BCL-2 were found. The results suggest that expression of BCL-2 and BAX is related to cell damage as indicated by DNA fragmentation but not to advanced stages of cellular death, as indicated by chromatin condensation and cellular shrinkage.

Animals↗
PubMed1996

Reflectance enzyme histochemistry (REH): visualization of cerium-based and DAB primary reaction products of phosphatases and oxidases in cryostat sections by confocal laser scanning microscopy.

In the present study the reflectance mode of confocal laser scanning microscopy was adapted to detect and to assess semiquantitatively cerium-based primary reaction products of oxidases [Ce(IV) perhydroxide] and phosphatases [Ce(III) hydroxyphosphate converted into Ce(IV) perhydroxyphosphate] as well as of the 3,3'-diaminobenzidine (DAB)-based primary reaction product of cytochrome c oxidase in cryostat sections. Confocal laser scanning microscopy offers a unique way of making visible histochemical reaction products which are weakly absorbant but sufficiently reflective. It was easily possible to record simultaneously the reflectance signals at the wavelength of the exciting laser (preferentially 488 nm) and the autofluorescence signals ( > 580 nm in our set-up) of glutaraldehyde-fixed tissue. The results of an imbibition study of cerium-containing model precipitates indicate that the cerium, generally, should be oxidized prior to observation because the index of refraction of Ce(IV) compounds is considerably higher than that of the corresponding Ce(III) compounds. An attempt at comparative numerical assessment of reflection intensities from reflectant parts in morphologically similar sections is presented. The proposed technique may open new possibilities in enzyme- and immunohistochemistry.

3,3'-Diaminobenzidine↗
PubMed1982

Laminin.

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Animals↗
PubMed1980

[Liver fibrosis. 2].

The mortality of liver cirrhosis has doubled during the past two decades and is still increasing in most of the European countries. One important feature and precursor of liver cirrhosis is liver fibrosis. Its aetiology includes a wide spectrum of well known causes, in Europe most frequently alcohol, virus infection, and chemical agents. The pathomechanism of liver fibrosis is unknown. Diagnostic and therapeutic approaches for early detection and treatment have been recently developed applying the results of pathobiochemical, cellular and clinical research. The composition of the excess hepatic connective tissue suggests the involvement of myofibroblasts and shows similarities to atherosclerotic plaques and lung fibrosis. The isolation, purification and cultivation of cells from liver biopsies offers new avenues for the study of fibroplastic cells. Clinical studies are now facilitated, since products of the collagen synthetic pathway - procollagen peptides - can be measured in serum with a sensitive radioimmunoassay. Further prospective studies including additional parameters of fibroplasia, such as N-acetyl-beta-D-glucosaminidase, lysyl-oxidase and prolyl-hydroxylase will have to demonstrate the diagnostic value of such methods. Even today, they should be applied in therapeutic trials of chronic fibrotic liver diseases. Better knowledge of the molecular regulation of connective tissue and the use of new animal models and cellular systems support a successful search for new therapeutic tools. Above all, limitation of alcohol consumption, vaccination for viral hepatitis and elimination of chemical agents offer the prevention of fibrosis, which calls for major efforts on a nation-wide scale.

Acetylglucosaminidase↗
PubMed1980

[Liver fibrosis. 1 (author's transl)].

The mortality of liver cirrhosis has doubled during the past two decades and is still increasing in most of the European countries. One important feature and precursor of liver cirrhosis is liver fibrosis. Its aetiology includes a wide spectrum of well known causes, in Europe most frequently alcohol, virus infection, and chemical agents. The pathomechanism of liver fibrosis is unknown. Diagnostic and therapeutic approaches for early detection and treatment have been recently developed applying the results of pathobiochemical, cellular and clinical research. The composition of the increased hepatic connective tissue suggests the involvement of myofibroblasts and shows similarities to atherosclerotic plaques and lung fibrosis. The isolation, purification and cultivation of cells from liver biopsies offers new avenues for the study of fibroplastic cells. Clinical studies are now facilitated, since products of the collagen synthetic pathway -- procollagen peptides--can be measured in serum with a sensitive radioimmunoassay. Further prospective studies including additional parameters of fibroplasia, such as N-acetyl-beta-D-glucosaminidase, lysyloxidase and prolylhydroxylase will have to demonstrate the diagnostic value of such methods. Even today, they should be applied in therapeutic trials of chronic fibrotic liver diseases. Better knowledge of the molecular regulation of connective tissue, and the use of new animal models and cellular system support a successful search for new therapeutic tools. Above all, limitation of alcohol consumption, vaccination for viral hepatitis and elimination of chemical agents offer the prevention of fibrosis, which calls for major efforts on a nation-wide scale.

Adolescent↗