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Biomedical subjects

J Rauterberg

Publications and source records attributed to J Rauterberg.

At least 55 records · Page 3Linked to original sources
PubMed1985

Connective tissue proteins on the injured endothelium of the rat aorta.

Type V collagen (TVC), fibronectin (FN), and laminin (LAM) were detected on the endothelial surface of mechanically injured rat aortas with the help of monospecific antisera and protein A - gold conjugates, carbon film surface replicas, and conventional embedding techniques. Deendothelialized tracks were produced in the thoracic aorta, and the presence of the connective tissue proteins on the luminal surface of the endothelium was studied. The changes in the distribution of the proteins during repair of the endothelial surface was followed for up to 6 days after injury. From 1 to 3 days after injury small numbers of gold particles, indicating the presence of TVC, were found between the adherent platelets on the freshly deendothelialized subendothelial matrix and in higher amounts on cell debris and collagen fibers. On the sixth day after injury, however, the amount of TVC between the sparsely distributed platelets on the deendothelialized areas was significantly higher than it was previously. FN and LAM were readily detectable on the subendothelial matrix and on the damaged marginal endothelial cells. These proteins were especially obvious on both margins of the tracks even from the first day after treatment. FN was found also in connection with fibrin precipitations as well as on the surface of some platelets and monocytes. The amount of FN and LAM present on the damaged area decreased slightly up to the sixth day. Monocytes and leukocytes adhered mostly at the margin of the wound area in the vicinity of the lesions on the endothelium. FN and LAM were often detectable under and around these adherent cells. Little of the connective tissue proteins was found on the uninjured and on the regenerated endothelial cells. The results showed subtle transitory changes in the surface pattern of the subendothelial connective tissue matrix of the injured intima. The adhesion of blood-borne cells may have been induced by FN and LAM on the endothelial surface near the lesions, and later partly prevented by increasing amounts of TVC on the surface.

Animals↗
PubMed1984

7 S collagen: a method for the measurement of serum concentrations in man.

A radioimmunoassay was developed for the detection of 7 S collagen, a basement membrane component derived from type IV collagen, in sera of patients. Two forms of 7 S collagen were isolated by limited collagenase digestion of type IV collagen from bovine placenta. Antisera against both forms were raised in rabbits. The antigens were labeled by conjugation with the Bolton Hunter reagent or by the Chloramine T method. Free and bound antigen were separated using a second antibody directed against rabbit-IgG. Serum concentrations of 7 S collagen ranged from 5-14 micrograms/l. Serum levels of 7 S collagen were increased in diabetic patients as compared to normal subjects.

Adolescent↗
PubMed1984

A collagen-like glycoprotein of the extracellular matrix is the undegraded form of type VI collagen.

The 140 000-dalton collagenous glycoprotein (CGP) from calf aorta and ligament characterized by Gibson & Cleary (1982) [Gibson, M.A., & Cleary, E.G. (1982) Biochem. Biophys. Res. Commun. 105, 1288-1295] has been studied. In the electron microscope, rotary-shadowed CGP molecules appear similar to the dimers of type VI collagen (short-chain collagen, intima collagen) described by other authors [Furthmayr, H., Wiedemann, H., Timpl, R., Odermatt, E., & Engel, J. (1983) Biochem. J. 211, 303-311] except that they have larger globular domains. As shown by gel electrophoresis, pepsin treatment of CGP at 4 degrees C either before or after reduction releases polypeptide chains corresponding in size to those of type VI collagen. Electron microscopic examination shows that pepsin digestion of nonreduced CGP removes the outer globular domains, reduces the size of the inner ones, and separates the paired central strands. The residual structures look like type VI collagen dimers. When intact CGP is reduced, monomers with two large globular ends are obtained. Pepsin digestion of monomers removes most or all of both globular domains. In immunoblots, CGP and its pepsin-derived fragments react with antibodies directed against type VI collagen. The results indicate that type VI collagen is an integral component of CGP.

Amino Acids↗
PubMed1984

Presence of connective tissue proteins on the endothelium of the rat aorta.

The microdistribution of type V collagen, fibronectin, and laminin on the luminal surface of perfusion-fixed normal rat aortic endothelium has been studied by an immunoelectron microscopic method using monospecific antibodies and a protein A-gold complex. Gold particles indicating the presence of these biologically active connective tissue proteins were localized in groups on and in the vicinity of the interendothelial border. They were also found on the small flaps of cell junctions as well as on certain cell projections and scattered on the cell surface. Correlative transmission electron-microscopic examinations proved the specificity of these localizations. The endothelial cells of the aorta differed markedly in the amount of scattered connective tissue proteins on their surface, suggesting that there are several types of aortic endothelial cells with distinct functional differences. The findings provide evidence that connective tissue proteins may contribute to the surface pattern of the normal endothelium, especially on cell borders. It is likely that these proteins influence functions such as the permeability and chemotactic activity of the endothelium pertinent to the development of vascular disease.

Animals↗
PubMed1984

Ehlers-Danlos syndrome type VI: collagen type specificity of defective lysyl hydroxylation in various tissues.

The Ehlers-Danlos syndrome type VI is an inherited disorder of collagen metabolism characterized by a defective lysyl hydroxylase. The resulting lack of hydroxylysine has been found in several connective tissues, all of which show varying degrees of clinical symptoms. In the present study, collagen was isolated from different connective tissues and the degree of hydroxylation of lysyl residues was determined. Subsequently, collagen types I, II, III, IV, and V have been prepared from a number of tissues. Insufficient hydroxylation of lysyl residues was found in type I and type III collagen, whereas types II, IV, and V showed normal amounts of hydroxylysine. The expression of the defect, even for type I and type III collagen, varied widely from one tissue to another. A complete lack of hydroxylysine was observed in skin, while it was less pronounced in tissues such as bone, tendon, lung, or kidney. The data suggest the presence of several isoenzymes having varying affinities to the different collagen types.

Adult↗
PubMed1983

Further characterization of the three polypeptide chains of bovine and human short-chain collagen (intima collagen).

Short-chain collagen was isolated from bovine and from human placenta after limited pepsin digestion. By reductive cleavage of disulfide bonds under non-denaturing conditions, mainly non-collagenous domains were cleaved off yielding a uniform component composed of three polypeptide chains with molecular masses between 37 kDa and 48 kDa in a nearly equimolar ratio. The chains (SC1*, SC2* and SC3*) were isolated and characterized. By comparison of peptide patterns obtained after various cleavage procedures, they could be identified as more or less shortened forms of SC1, SC2 and SC3, the isolation of which from bovine short-chain collagen has been described [Jander et al. (1981) Eur. J. Biochem. 114, 17-25]. The peptide patterns; as well as N-terminal sequence determination, give evidence for the genetic individuality of the three chains; the data so far available suggest that together they form one triple-helical structure which represents the collagenous domain of the basic molecular unit of short-chain collagen.

Amino Acids↗
PubMed1983

Biologic characterization of human bone tumors. II. Distribution of different collagen types in osteosarcoma--a combined histologic, immunofluorescence and electron microscopic study.

Sixteen cases of typical highly malignant osteosarcoma were investigated by light, electron, and immunofluorescence microscopy to demonstrate the presence of collagen types I-III. It was shown that, in light-microscopically anaplastic areas of the tumor, collagen type III predominates, while only very few membranes of collagen type I are observed. Ultrastructurally, the cells are characterized by numerous free ribosomes in their cytoplasm and only a few membranes of granular endoplasmic reticulum (ER). In osteoblastic areas, collagen type I is increased, while type-III collagen is decreased. The cytoplasm of cells contains markedly more granular ER. An increasing mineralization of matrix is observed. In fibroblastic areas of the tumors, collagen types I and III are codistributed. Tumor cells have a fibroblast appearance with elongated nuclei and well developed granular ER. The chondroblastic areas, characterized by immature neoplastic cartilage, contain varying amounts of collagen type II. Chondroblast-like tumor cells have typical ring-shaped membranes of granular ER in their cytoplasm. The evidence of different collagen types in osteosarcomas lends additional support to the concept that a pluripotent mesenchymal cell is the stem cell of osteosarcomas.

Adolescent↗
PubMed1982

Connective tissue components of the normal and fibrotic human liver. II. Clinical aspects.

In this second part, clinical aspects of connective tissue metabolism in the liver will be described and two main aspects considered. The first is the possibility to monitor the activity of fibrosis by the use of metabolites and enzymes of connective tissue metabolism. In recent studies the qualification for this purpose of enzymes such as procollagen prolyl hydroxylase and lysosomal N-Acetyl-beta-glucosaminidase and the N-terminal peptide of procollagen type III has been tested. The serum activities or concentrations of these substances in patients with chronic active liver diseases increase in due relation to the histologically estimated activity of liver fibrosis. The second aspect deals with therapeutic approaches to fibrosis in the liver by using connective tissue specific agents. So far none of the antifibrotic substances such as proline analogues, colchicine, lathyrogens and penicillamine has been used in longer-term antifibrotic treatment.

Acetylglucosaminidase↗
PubMed1982

Biologic characterization of human bone tumors. I. Ewing's sarcoma. A comparative electron and immunofluorescence microscopic study.

Six cases of Ewing's sarcoma were investigated by electron and immunofluorescence microscopy. A layer of basement membrane-like deposits was found between typical principal and secondary tumor cells. To clarify the nature of these ultrastructural deposits, antibodies against collagen type IV were applied to frozen sections of corresponding tumor tissue. This reaction revealed type IV collagen as a regular component of basement membranes in nonneoplastic tumor capillaries, but it was equally able to localize collagen type IV between single tumor cells in capillary-free areas. With the same method, factor-VIII-associated protein, predominantly found in endothelial cells, could be demonstrated in some tumor cells. These results demonstrate that, in addition to anaplastic cells, some tumor cells are found in Ewing's sarcoma that share certain differentiating features with the endothelial cell.

Adolescent↗
PubMed1982

[The significance of structural glycoproteins, demonstrated by the example of the fibronectins. Biochemical principles and clinical use].

Fibronectin, a structural glycoprotein on cell surfaces, appears in significant concentrations too in human blood plasma. Fibronectin influences cell interactions and cell growth and is an essential part of the extracellular matrix. The following review summarizes the biochemistry and function of fibronectin--or rather of fibronectins, bearing in mind the difference in protein structure between plasma fibronectin and cell surface fibronectin. Fibronectin is identical with one opsonin (alpha 2-opsonic glycoprotein). During shock and septicemia it undergoes a marked decrease. The diminished concentration in the plasma indicates a reduced function of the reticulo-endothelial system. A report is given on initial substitution trials.

Cell Membrane↗
PubMed1982

[Clinical aspects and pathology of connective tissue metabolism of the liver].

Reactions in the connective tissue metabolism are of considerable importance in the pathophysiological process of diseases. It is from this aspect that new findings in chronic liver diseases are reported in the present paper. A report is given on cellular and extracellular pathological changes in connective tissue functions. Diagnostic and pharmacological methods undergoing continued development for controlling and influencing liver fibrosis are discussed.

Antifibrinolytic Agents↗
PubMed1981

Connective tissue components of the normal and fibrotic liver. I. Structure, local distribution and metabolism of connective tissue components in the normal liver and changes in chronic liver diseases.

The first part of this review describes the chemistry, the occurrence and the metabolism of extracellular connective tissue components in the liver. The normal liver contains typical connective tissue proteins (collagens, structural glycoproteins and proteoglycans) not only in vessel walls, perivascular areas and in the capsule, but they occur also in small amounts in the parenchyma, mainly in the space of Disse along the sinusoidal walls. The "interstitial" collagens type I and III represent the major amount of collagen in the normal as well as in fibrotic liver, showing a relative increase of type III in fibrosis. Basement membrane collagens type IV and V as well as the cysteine-rich collagenous components "7 S collagen" and "short chain collagen" have been shown to occur in extracts prepared after limited pepsin digestion. In the normal liver, basement membrane collagen can hardly be detected within the parenchyma by immunofluorescence microscopy; increased occurrence, however, can be shown along the sinusoids even in early stages of chronic liver diseases. The glycoprotein fibronectin was shown to be distributed very similarly to collagens type I and III, whereas the basement membrane specific glycoprotein laminin is restricted to vessel walls and the epithelial layer of bile ductuli in the normal liver but is also found in the parenchyma in fibrosis. Occurrence of proteoglycans is increased in fibrosis: a change in the composition of glycosaminoglycans from mainly heparan sulfate in the normal to dermatan- and chondroitin sulfate in the fibrotic liver was observed. It is not yet clear which cell type is mainly responsible for increased connective tissue synthesis in fibrosis. The occurrence of cells resembling smooth muscle cells ("myofibroblasts") in connective tissue septa of fibrotic livers and the fact that similar cells which actively synthesize collagen grow from explants of fibrotic livers may indicate the significance of this cell type in the process of liver fibrosis.

Basement Membrane↗