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H Denk

Publications and source records attributed to H Denk.

At least 109 records · Page 6Linked to original sources
PubMed1984

Immunohistochemical demonstration of cytokeratins in endocrine cells of the human pituitary gland and in pituitary adenomas.

Ten non-neoplastic pituitary glands and 22 pituitary adenomas producing different hormones were studied by immunofluorescence microscopy as well as peroxidase-antiperoxidase and biotin-avidin techniques on frozen sections and formalin-fixed, paraffin-embedded material using antibodies to cytokeratin, vimentin, GFAP, neurofilament protein and different pituitary hormones. The endocrine cells in non-neoplastic pituitary glands as well as in most pituitary adenomas were cytokeratin-positive. The cytoplasmic cytokeratin distribution patterns of non-neoplastic and tumor cells were similar and typical of the type of hormone produced: GH-producing normal cells showed a paranuclear condensation of cytokeratin-reactive intermediate filaments; this accumulation was even further accentuated in GH-producing adenomas resulting in fibrous bodies (Kovacs and Horvath 1978) decorated by cytokeratin antibodies. Prolactin-producing cells showed a less intense cytoplasmic cytokeratin-specific staining with focal paranuclear accentuation in non-neoplastic as well as in neoplastic glands. ACTH-producing cells in normal pituitary glands as well as in adenomas exhibited a strong and more uniform cytoplasmic cytokeratin staining. The cytokeratin reactivity in glycoprotein hormone-producing cells of non-neoplastic tissue and adenomas was weak. Vimentin and GFAP reactivity was confined to agranular folliculo-stellate cells. The specific and different distribution patterns of cytokeratins in pituitary cells can, therefore, provide an (indirect) indication to the production of a specific hormone if immunocytochemistry fails to demonstrate hormone production.

Adenoma↗
PubMed1984

New immunocytochemical observations with diagnostic significance in cutaneous neuroendocrine carcinoma.

The presence and distribution of cytokeratins, actin, neurofilament protein, neuron-specific enolase, S-100 protein, and different neuropeptides were studied immunohistochemically by the peroxidase-antiperoxidase immunoenzyme method or the avidin-biotin-peroxidase technique in 10 patients with primary cutaneous neuroendocrine carcinoma. In all cases of cutaneous neuroendocrine carcinoma, immunoreactivity for neuron-specific enolase, cytokeratin, and neurofilament was identified. No staining was found after incubation with antibodies to S-100 protein, actin, and other tested neuropeptides. The cytoplasmic cytokeratin and neurofilament immunoreactivity was particularly strong in perinuclear areas, sometimes showing an annular pattern or displaying a discoid profile. The diagnosis of cutaneous neuroendocrine carcinoma may be reliably made by the immunocytochemical demonstration of neuron-specific enolase and intermediate filaments (cytokeratin, neurofilament protein) by conventional microscopy. Cutaneous neuroendocrine carcinoma has morphological, immunological, and histogenetic similarities to carcinoid neoplasms of the gut. We favor the concept that cutaneous neuroendocrine carcinoma is derived from, or differentiates toward, dermal neuroendocrine cells.

Apudoma↗
PubMed1984

Effect of griseofulvin treatment and neoplastic transformation on transglutaminase activity in mouse liver.

The present study was undertaken in order to elucidate the effect of liver injury exerted by the antimicrotubular drug griseofulvin on hepatic transglutaminase activity in mice. Griseofulvin treatment of mice leads to a significant increase of transglutaminase activity associated with the 105 000 X g supernatant of liver homogenate, which is readily reversible after replacement of the griseofulvin-containing diet by a normal diet. Neoplastic nodules originally induced by prolonged griseofulvin feeding also show increased transglutaminase activity in contrast to reports in the literature. The increase in hepatic transglutaminase activity in griseofulvin-fed mice could be due either to mitotic inhibition exerted by the drug or to disturbance of intracellular Ca++ homeostasis following membrane injury. The second possibility could also account for the increased enzyme activity in neoplastic nodules. Similar events have been described as occurring in aging erythrocytes and terminally differentiating keratinocytes. The pathologic consequences and the substrates of increased hepatic transglutaminase activity have still to be elucidated.

Acyltransferases↗
PubMed1984

Influence of long-term anticonvulsant treatment on liver ultrastructure in man.

In 35 patients on long-term anticonvulsant treatment (7-35 years, means = 19.6 years), various liver enzymes were measured. In 32 cases (91.4%), elevated levels of serum-gamma-glutamyl-transpeptidase (GGT) were found. Liver biopsy was performed in five of 13 patients with GGT levels of greater than 60 U/l (75-257, means = 123 U/l). Light microscopy showed a minimal steatosis and fine granular appearance of hepatocytes in two cases, and a slight portal fibrosis in one case. Two cases showed an unremarkable histology. Electron microscopy revealed signs of enzyme induction as overall swelling of the smooth endoplasmic reticulum and additionally a dilatation of the rough endoplasmic reticulum in all five specimens. No signs of liver damage or disturbance of liver function could be observed.

Adult↗
PubMed1983

Differential distribution of microtubule-associated proteins MAP-1 and MAP-2 in neurons of rat brain and association of MAP-1 with microtubules of neuroblastoma cells (clone N2A).

To study the individual location of the microtubule proteins MAP-1 and MAP-2 in neuronal tissues and cells, antisera to electrophoretically purified MAP-1 and MAP-2 components were raised in rabbits. When frozen sections through rat brain were examined by immunofluorescence microscopy the antibodies to MAP-1 strongly stained a variety of nerve cells including dendrites and myelinated axons in the cerebrum and cerebellum. Antibodies to MAP-2 showed similar staining patterns, except that myelinated axons were unstained. These results were confirmed by immunoelectron microscopy of frozen sections through cerebellum using the peroxidase technique. Thereby, the association of MAP-1 with microtubules was also clearly demonstrated. When cultured mouse neuroblastoma N2A cells were examined by immunofluorescence microscopy the antiserum to MAP-1 brightly stained filamentous structures resembling microtubules, whereas relatively weak and diffuse staining of the cytoplasm was observed with the antiserum to MAP-2. In agreement with the immunolocalization, MAP-1, but not MAP-2, was found as a prominent component of microtubules proteins polymerized in vitro by taxol from soluble N2A cell extracts. Together these results indicate that neuronal microtubules are preferentially associated with distinct high mol. wt. polypeptides. Therefore, they support the concept that different complements of associated proteins determine distinct functions of microtubules.

Animals↗
PubMed1983

Immunocytochemical identification of epithelium-derived human tumors with antibodies to desmosomal plaque proteins.

Epithelial cells contain desmosomes, special intercellular junctions providing sites of membrane attachment for intermediate-sized filaments of the cytokeratin type (tonofilaments). Such sites of anchorage of tonofilaments appear as dense plaques on the cytoplasmic side of the desmosomal membrane. We have isolated desmosome-enriched fractions from bovine snout epidermis and tongue mucosa and have characterized the major protein associated with the desmosomal plaque. This protein occurs in equimolar amounts of two polypeptides of Mr 250,000 (desmoplakin I) and Mr 215,000 (desmoplakin II) which are chemically and immunologically related. Antibodies raised against desmoplakins allow the identification and localization of this protein in epithelial cells grown in tissues or in vitro and show crossreaction in species as diverse as man, mouse, and chicken. Using immunolocalization at the light and electron microscope levels, we show that these antibodies bind specifically to desmosomal plaques. Antibodies to desmoplakins have been used successfully for detection of desmosomal proteins in a broad variety of epithelium-derived human tumors, including primary carcinomas and their metastases, irrespective of the morphology of the specific tumor. Nonepithelial tumors examined have been negative. We propose to use antibodies to desmoplakins and to cytokeratins in pathological diagnosis as two independent markers for the positive immunocytochemical identification and classification of epithelium derived tumors.

Animals↗
PubMed1983

Occurrence and immunolocalization of plectin in tissues.

Various tissues from rat were examined for the occurrence and cellular localization of plectin, a 300,000-dalton polypeptide component present in intermediate filament-enriched cytoskeletons prepared from cultured cells by treatment with nonionic detergent and high salt solution. The extraction of liver, heart, skeletal muscle, tongue, and urinary bladder with 1% Triton/0.6 M KCl yielded insoluble cell residues that contained polypeptides of Mr 300,000 in variable amounts. These high Mr polypeptide species and a few bands of slightly lower Mr (most likely proteolytic breakdown products) were shown to react with antibodies to rat glioma C6 cell plectin using immunoautoradiography and/or immunoprecipitation. By indirect immunofluorescence microscopy using frozen sections (4 micron) of stomach, kidney, small intestine, liver, uterus, urinary bladder, and heart, antigens reacting with antibodies to plectin were found in fibroblast, endothelial, smooth, skeletal, and cardiac muscle, nerve, and epithelial cells of various types. Depending on the cell type, staining was observed either throughout the cytoplasm, or primarily at the periphery of cells, or in both locations. In hepatocytes, besides granular staining at the cell periphery, conspicuous staining of junctions sealing bile canaliculi was seen. In cardiac muscle strong staining was seen at intercalated disks and, as in skeletal muscle, at Z-lines. In cross sections through smooth muscle, most strikingly of urinary bladder, antibodies to plectin specifically decorated regularly spaced, spot-like structures at the cell periphery. By immunoelectron microscopy using the peroxidase technique, antiplectin-reactive material was found along cell junctions of hepatocytes and was particularly enriched at desmosomal plaques and structures associated with their cytoplasmic surfaces. A specific immunoreaction with desmosomes was also evident in sections through tongue. In cardiac muscle, besides Z-lines, intercalated disks were reactive along almost their entire surface, suggesting that plectin was associated with the fascia adherens, desmosomes, and probably gap junctions. In smooth muscle cells, regularly spaced lateral densities probably representing myofilament attachment sites were immunoreactive with plectin antibodies. The results show that plectin is of widespread occurrence with regard to tissues and cell types. Furthermore, immunolocalization by light and electron microscopy at junctional sites of various cell types and at attachment sites of cytoplasmic filaments in epithelial and muscle cells suggests that plectin possibly plays a universal role in the formation of cell junctions and the anchorage of cytoplasmic filaments.

Animals↗
PubMed1983

Proteins of intermediate filaments. An immunohistochemical and biochemical approach to the classification of soft tissue tumors.

The intermediate filament cytoskeleton of various types of human soft tissue tumors was analyzed by immunofluorescence microscopy with the use of specific antibodies against cytokeratins, vimentin, and desmin, as well as by one- and two-dimensional gel electrophoresis of high-salt buffer- and detergent-resistant cytoskeletal preparations. All leiomyomas as well as a leiomyosarcoma contained desmin. Leiomyomas of both gastrointestinal and uterine derivation and the retroperitoneal leiomyosarcoma showed strong reaction for desmin in the smooth muscle cells, but the latter two exhibited also vimentin staining. In embryonal rhabdomyosarcomas, desmin prevailed in the large, apparently well-differentiated rhabdomyoblasts; whereas the smaller, less differentiated tumor cells preferentially contained vimentin. Cells of malignant fibrous histiocytomas were characterized by their content of vimentin as the only intermediate filament protein present. In alveolar soft part sarcoma, a rare tumor of hitherto unknown histogenesis, vimentin and desmin co-existed within the same tumor cells, indicating, together with chemical determinations, the myogenic derivation of this neoplasm. The results show that immunologic and biochemical analysis of proteins associated with the intermediate filament cytoskeleton is a useful adjunct in the diagnosis of diverse neoplasms, particularly those with equivocal histologic features, and thus aids in the histogenetic classification of soft tissue tumors.

Desmin↗
PubMed1982

[Immunohistochemical studies on the association between hepatitis B surface antigen and primary hepatocellular carcinoma (author's transl)].

In many geographical areas especially in African and South-east-Asian countries hepatitis B virus infection is considered to be a major etiological factor in the development of primary hepatocellular carcinoma. 107 autopsy- and 15 biopsy-specimens were studied by means of immunohistochemistry [peroxidase-antiperoxidase-(PAP-)method] to demonstrate the association between primary hepatocellular carcinoma and hepatitis B surface antigen (HBsAg). HBsAg was found in 8 of 107 tumour specimens (7.4%) and liver cirrhosis in 102 of the 107 autopsy specimens with hepatocellular carcinoma (95%). 10 of the 15 biopsy-specimens showed neoplastic and non-neoplastic liver tissue, and in 2 of these 10 cases HBsAg was found. Liver cirrhosis could be seen in 9 of those 10 specimens. HBsAg was also studied in 90 cases with liver cirrhosis and was found to be positive in 2 of them (2,2%). HBsAg associated with primary hepatocellular carcinoma was only found in non-neoplastic liver cells of cirrhotic livers. Our studies indicate that in our geographical area the association of HBsAg with primary hepatocellular carcinoma is much less conspicuous than in Asian, African and even Southern European communities.

Africa↗
PubMed1982

Antibodies to intermediate filament proteins as molecular markers in clinical tumor pathology. Differentiation of carcinomas by their reaction with different cytokeratin antibodies.

Antibodies to human and bovine epidermal prekeratin and antibodies to mouse liver cytokeratin component D (Mr 49 000) have been applied in indirect immunofluorescence microscopy on sections of human tumors of mammary gland and liver. In non-neoplastic mammary gland all epithelial cells were stained with these antibodies. In pre-invasive and invasive ductal and lobular carcinomas a cell population was observed which was not significantly stained with antibodies to epidermal prekeratin but did strongly react with antibodies to liver cytokeratin D. In the liver, the antibodies to epidermal prekeratin as well as those directed against liver cytokeratin D strongly decorated bile duct epithelia. In contrast, significant staining of the hepatocytes was only achieved with antibodies to liver cytokeratin D. This different staining reaction was maintained in liver tumors of hepatocellular and cholangiocellular origin. Antibodies to vimentin stained mesenchymal cells and tumors of mesenchymal derivation but reacted not significantly with any of the epithelial and carcinoma cells examined. The difference is of practical importance for the discrimination between anaplastic carcinomas and sarcomas of unknown origin. Cytokeratin could also be detected by antibody staining using the peroxidase-antiperoxidase (PAP) technique in formaldehyde-fixed and paraffin-embedded material of skin, gastrointestinal, respiratory, urinary and genital tract as well as various glands, liver and kidney. Examples of positive reactions were shown in a squamous cell carcinoma, a basalioma and a pleomorphic adenoma of the parotis. It is concluded that the immunohistochemical analysis of intermediate filament proteins has diagnostic potential in clinical pathology and may help to elucidate histogenesis and differentiation of tumors and possibly also prognosis of tumor growth. It is further suggested to use antibodies recognizing different subsets of proteins of the cytokeratin family in order to distinguish between different types of carcinomas.

Adenoma, Pleomorphic↗
PubMed1982

Immunological and biochemical characterization of the keratin-related component of Mallory bodies: a pathological pattern of hepatocytic cytokeratins.

Mallory bodies induced by long-term griseofulvin feeding in mouse liver were isolated and analyzed by one- and two-dimensional gel electrophoresis and reaction of the separated polypeptides with cytokeratin antibodies using the blotting technique. Comparison with normal intermediate filament cytoskeletons from mouse hepatocytes revealed that Mallory bodies contain two polypeptides: Component II (Mr: 55,000; apparent isoelectric point values: 6.45, 6.1, 5.9) and component III (Mr: 48,000; apparent isoelectric point values: 5.7, 5.5, 5.43, 5.38, 5.2) which appear to be similar, if not identical, to liver cytokeratins A and D, respectively. By contrast, component I of Mallory bodies (Mr: 65,000; apparent isoelectric point values: 5.4, 5.38, 5.2) was not found in appreciable amounts in normal hepatocytes. Component II was positive in immunoreaction with antibodies to murine hepatocyte keratins A and D as well as epidermal prekeratin. Component III showed reaction with the antibodies to murine hepatocyte keratins A and D but not with those raised against epidermal prekeratins. By contrast, the unusual component I reacted with antibodies to murine hepatocyte keratin D and to epidermal prekeratins. The results prove that cytokeratin polypeptides are major constituents of Mallory bodies and suggest that the pattern of liver cytokeratin polypeptides is altered during the toxic treatment and/or Mallory body formation.

Animals↗