Search PubMed⌕ Search

Biomedical subjects

K Weber

Publications and source records attributed to K Weber.

At least 397 records · Page 22Linked to original sources
PubMed1987

Keratin polypeptides in malignant epithelial liver tumors. Differential diagnostic and histogenetic aspects.

Five monoclonal antibodies recognizing different keratin polypeptides in immunoblotting or different epithelial cell types in complex tissues were studied for their suitability as reagents for the differential diagnosis of primary and secondary malignant epithelial liver tumors. The broad specificity keratin antibodies lu-5 and KL-1 stained all epithelial liver neoplasms. In contrast the antibodies CK-7 (Ker-7-specific), CK-2 (Ker-18-specific) and KA-4 (Ker-19-specific in liver) allow these neoplasms to be divided into three groups: Hepatocellular carcinomas were CK-2-positive and CK-7-negative. Cholangiocellular carcinomas, liver metastases of extrahepatic bile duct carcinomas, liver metastases of a ductal carcinoma of breast, and a follicular thyroid carcinoma were stained positively by CK-2, CK-7, and KA-4. In 1 of 6 hepatocellular carcinomas neoplastic hepatocytes were focally labeled by KA-4. In a focal nodular hyperplasia of the liver modified hepatocytes were decorated not only by CK-2 but also by CK-7 and KA-4. Liver metastases of colorectal adenocarcinomas and of a carcinoid tumor were stained positively by CK-2 and KA-4 but not by CK-7.

Adenoma, Bile Duct↗
PubMed1987

Coexpression of keratin and vimentin in damaged and regenerating tubular epithelia of the kidney.

Most renal cell carcinomas coexpress vimentin and keratin, while renal tubular epithelia express only keratin. Investigation of the intermediate filament composition of tubular epithelia in diseased rat and human kidneys now shows that altered tubular epithelia unequivocally coexpress keratin and vimentin. In rats, pronounced coexpression of vimentin and keratin was observed in chronic nephrosis induced by daunomycin, and the extent of coexpression seemed to increase with the incidence of altered collapsed and cystically dilated tubules and with the degree of tubular epithelial proliferation. It was also seen during tubular regeneration after acute tubulotoxic injury induced by mercury chloride poisoning, with vimentin expression being lost in fully regenerated tubular epithelium. In man, expression was seen in chronically and irreversibly damaged kidneys. Thus, vimentin can be expressed temporarily in acutely and reversibly damaged kidneys and chronically in irreversibly damaged kidneys. Vimentin could perhaps be regarded as an indicator of the regenerating and proliferating activity of tubular lesions.

Animals↗
PubMed1987

Morphological changes in Neisseria gonorrhoeae induced by various subinhibitory concentrations of cefotiam.

A wide variety of morphological changes is induced in gonococci exposed to subinhibitory concentrations of cefotiam. The spectrum reaches from phenomena like enlargement or lysis of cells which can already be seen on the light microscopic level to others which can only be detected by ultrastructural analysis. Most of the changes rarely also occur during the life cycle of gonococci not exposed to an antibiotic. Yet they are more frequent and also more distinct even in the presence of rather low concentrations of cefotiam. The development of mixed (layered and tubular) and even further disorganized mesosomes, however, seems to be characteristic of antibiotic interference.

Cefotaxime↗
PubMed1987

[The auxiliary transplantation of a portion of liver in an animal experiment].

The authors inform about a model for auxiliary liver part transplantation in pig. Intra-abdominal narrowness which can lead to failure of the transplant can avoided by this model. In the transplant was carried out an extensive left resection with purse-string ligature of all visible vessels and cystic ducts. The resection surface is sealed by a tissue adhesive. An auxiliary transplanted part of the liver can also operate on a heterotopic location of the organism.

Animals↗
PubMed1987

[Possibilities of behavior therapy in neurologic practice].

During one year one day the week a psychiatrist and a behavior therapist cooperate in treating neurotic patients asking for help in the psychiatrist's praxis. The main interest has been to orientate the whole way of treatment-beginning with intake interview in the psychiatrist's praxis continuing in some cases with an offer of immediate behavioral therapy-at those principles the modern behavior therapy commonly uses. Those kinds of "behavioral" problem analyses the outpatient unit for behavior modification University Clinic Hamburg has developed the last ten years have been very helpful; further the different kinds of exposure in real life (in vivo) situations, but also exposure in sensu seemed to be applicable; both because of offering immediate help without looking at sex, age, socio-economic status.

Adjustment Disorders↗
PubMed1986

Functionally distinct serine phosphorylation sites of p36, the cellular substrate of retroviral protein kinase; differential inhibition of reassociation with p11.

P36 was originally defined as the major cytoplasmic target of retrovirally coded tyrosine-kinases. While recently much has been learned about its biochemistry, the functional importance of its tyrosine and serine phosphorylation has not been approached. As p36 is now understood as a multi-ligand protein its in vitro phosphorylation by three different serine/threonine kinases was followed. Monomeric p36 is a much better substrate than the complex containing two copies each of p36 and p11 (protein I). All p36 phosphorylation sites occur within the amino-terminal 29 residues specifically released by mild proteolysis. As this region harbors an important interaction site for p11 the reduced phosphorylation of p36 in the protein I complex results most likely from a lowered accessibility. Phosphorylation of p36 is serine specific. Reconstitution experiments define at least two functionally distinct sites. One product of protein kinase C reconstitutes with p11 to protein I, while this complex formation normal for p36 is observed neither for the second phosphorylation product nor for the derivatives resulting from phosphorylation by calmodulin or cAMP dependent kinases. The results lend direct support to the hypothesis that phosphorylation of p36 can modulate one of its molecular functions. Obvious implications for other Ca2+-dependent lipid binding proteins are discussed.

Amino Acids↗
PubMed1986

Repeating sequence homologies in the p36 target protein of retroviral protein kinases and lipocortin, the p37 inhibitor of phospholipase A2.

Although considerable information has emerged on the molecular properties of the p36 target protein its function as well as the possible implications of its tyrosine phosphorylation have remained elusive. Here we show that all sequence segments of p36 published so far can be aligned by homology along the complete sequence of lipocortin, which has been reported recently. This alignment extends beyond multiple Geisow motifs, thought to indicate a sequence principle implicated in Ca2+ and/or lipid binding. While the latter properties are already established for p36 one may expect them also for lipocortin, an inhibitor of phospholipase A2 activity. Certain implications of these results are discussed.

Annexins↗
PubMed1986

Binding sites for calcium, lipid and p11 on p36, the substrate of retroviral tyrosine-specific protein kinases.

Biochemical and partial sequence data reveal the two-domain structure of p36. A loose structure of some 30 residues at the amino-terminus contains the phosphorylatable tyrosine and the binding site for the p11 regulatory chain. The following p33 domain retains the lipid-binding site as well as the Ca2+ site which influences the spectral properties of the single tryptophan and one tyrosine. The combined sequence data covering about 25% of the molecule identify p36 as a unique polypeptide.

Amino Acid Sequence↗
PubMed1986

Isolation of a domain of villin retaining calcium-dependent interaction with G-actin, but devoid of F-actin fragmenting activity.

Villin is an F-actin binding protein located in the microfilament bundle of intestinal epithelial cell microvilli. Extensive in vitro proteolysis with Staphylococcus aureus V8 protease results in the production of a stable domain (apparent Mr 44000) which can be isolated due to its Ca2+-dependent interaction with G-actin bound to immobilized DNase-I, the standard procedure for the purification of villin. This 44-kDa fragment retains a single Ca2+ binding site with an apparent Kd = 2 X 10(-6) M, binds to G-actin, and inhibits the rate of actin polymerization. However, the 44-kDa domain does not shown any Ca2+-activated severing activity nor does it compete with villin for F-actin binding. These results suggest that villin contains three domains: headpiece containing an F-actin binding site, 44-kDa fragment containing a G-actin binding site, and an amino-terminal fragment responsible for the Ca2+-dependent severing activity.

Actins↗
PubMed1986

Pleomorphic adenomas, adenoid cystic carcinomas and adenolymphomas of salivary glands analysed by a monoclonal antibody against myoepithelial/basal cells. An immunohistochemical study.

Myoepithelial and basal cells were identified by a monoclonal antibody raised against keratin. This antibody (CK B1) which detects myoepithelial cells in normal salivary glands, labels spindle shaped and polygonal cells in pleomorphic adenomas. Most cells in adenoid cystic carcinomas and some basal cells in adenolymphomas were also positive for this antibody. The oncocytic epithelium of adenolymphoma was negative. An inverse reaction was seen with an antibody against cytokeratin 18. The antibody CK B1 seems to be of interest for the detection of myoepithelial/basal cells in salivary glands and salivary gland tumours.

Adenolymphoma↗
PubMed1986

A monoclonal antibody that detects myoepithelial cells in exocrine glands, basal cells in other epithelia and basal and suprabasal cells in certain hyperplastic tissues.

Myoepithelial and luminal cells of human exocrine glands can be positively identified with two different monoclonal antibodies. Myoepithelial cells including those of the salivary gland, mammary gland and sweat gland are positively identified by an antibody CKB1. This antibody does not stain luminal cells, but stains the basal cell layer of certain human stratified epithelia and a few basal cells in simple epithelia. Thus myoepithelial cells and basal cells have certain common features. Luminal cells can be positively stained with the CK5 monoclonal keratin antibody specific for keratin polypeptide 18; this antibody does not stain myoepithelial cells. Of interest is that CKB1 also appears to stain basal and suprabasal cells in certain hyperplastic conditions.

Antibodies, Monoclonal↗
PubMed1986

Keratin polypeptide distribution in benign and malignant breast tumors: subdivision of ductal carcinomas using monoclonal antibodies.

Monoclonal antibodies which recognize one or only a few keratin polypeptides have been used to study the distribution of different keratins in benign and malignant breast lesions by immunocytochemical methods. Seven monoclonal antibodies which recognized either different keratin polypeptides by immunoblotting techniques, or identified different epithelial cell types in complex tissues were used. In two mastopathies and three fibroadenomas the antibody lu5 stained luminal cells as well as myoepithelial cells. In contrast the antibodies CK7, Troma 1, CK2 and KA4 labeled only luminal cells, whereas antibody CKB1 decorated only myoepithelial cells. All 15 ductal carcinomas showed a uniform staining of tumor cells with the antibodies Troma 1, CK2, KA4 and lu5. The antibody CK7 also stained all ductal carcinomas, but in two specimens the staining was heterogeneous. The antibody CKB1 decorated only the pre-existing myoepithelial cells in 11 of 12 ductal carcinomas but in the remaining specimen the tumor cells were also strongly positive. Tumor cells in lobular carcinomas were labeled by antibodies CK7, Troma 1, CK2, KA4, bu not by CKB1. The antibody CKS1 showed no staining of any of the benign and malignant breast lesions.

Antibodies, Monoclonal↗
PubMed1986

Microinjection of monoclonal antibodies to vimentin, desmin, and GFA in cells which contain more than one IF type.

Microinjection of antibodies to vimentin into fibroblast cell lines causes intermediate filaments (IFs) to build perinuclear caps. We have extended these findings by microinjection of monoclonal antibodies specific for different IF types to non-epithelial cell lines of human origin, which co-express two different IF proteins. Thus GFA and vimentin IgGs have been microinjected in separate experiments into a glioma cell line, desmin and vimentin IgGs into RD cells, and vimentin IgGs into a cell line which co-expresses neurofilaments and vimentin. In all instances, microinjection of a single antibody causes the formation of perinuclear caps in which the two different IF proteins co-localize, suggesting that vimentin and the second IF type present in each cell line localize to the same 10-nm filaments. Immunoelectron microscopy using desmin and vimentin antibodies made in different species and appropriate second antibodies labelled with 5 and 20 nm gold particles confirm this result for RD cells. When Fab' fragments of the vimentin IgGs are microinjected into different cell types, formation of perinuclear caps is observed in immunofluorescence microscopy. In RD cells immunoelectron microscopy shows that the Fab' fragments induce caps which appear less dense than the caps seen after microinjection of IgGs.

Animals↗