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H Denk

Publications and source records attributed to H Denk.

At least 73 records · Page 4Linked to original sources
PubMed1991

Enzyme-histochemical studies of griseofulvin-intoxicated mouse livers.

Enzyme-histochemical studies were conducted on livers of mice chronically fed griseofulvin (GF) in order to produce Mallory bodies (MBs) in hepatocytes. The development of MBs is associated with derangement of the immunohistochemically detectable intermediate filament (IF) cytoskeleton of the cytokeratin (CK) type, although no strict correlation between appearance or involution of MBs and the cytoskeletal alterations exists. Since the function of the IF cytoskeleton and the relationship of its disturbance to cell injury is unknown, the aim of the present study was to correlate the activities of several key enzymes of cellular metabolic pathways with the disturbance of the cytoskeleton architecture. For that purpose enzyme-histochemistry in combination with immunohistochemical CK-IF stainings were performed on identical sections. In GF-intoxicated mouse livers the normal topography of enzyme activities was disturbed, but no strict colocalization of enzymatic and cytoskeletal changes was found. Glucose-6-phosphatase, a microsomal enzyme involved in glucose output and gluconeogenesis, showed elevated activity in MB-free hepatocytes with diminished immunostainable CK-IF cytoskeleton refuting the concept of a disability of those cells to export glucose. It could indeed indicate that those cells without MBs are in the state of recovery. However, these cells could also resemble "hyperactive foci". Glycogen was decreased in MB-containing hepatocytes with disturbed cytoskeleton, and this feature favours the assumption of cell degeneration. On the other hand, the mitochondrial marker enzymes, i.e. succinate dehydrogenase, cytochrome-c-oxidase and 3-hydroxybutyrate dehydrogenase, remained unchanged in altered hepatocytes. Alkaline phosphatase activity at the canalicular pole of GF-intoxicated hepatocytes was elevated, indicating cholestatic features associated with this disorder. However, since altered hepatocytes did not show impairment of oxido-reductase activities, a severe impairment of bile secretion as a consequence of cell damage is unlikely. Unchanged or even increased ATPase activity of altered hepatocytes also indicated their sustained metabolic abilities. The results presented provide indirect evidence that hepatocytes with disturbed IF cytoskeleton do not significantly differ from normal cells with respect to oxidative metabolism, fatty acid synthesis and gluconeogenesis. This suggests that alterations of the IF cytoskeleton associated with GF intoxication and MB formation have no significant adverse influence on the metabolic functions of liver cells, as far as can be assessed by evaluation by enzyme-histochemical staining of several key enzymes.

Animals↗
PubMed1991

Changes of cytokeratin filament organization in human and murine Mallory body-containing livers as revealed by a panel of monoclonal antibodies.

Mallory bodies (MBs) are characteristics morphologic features of alcoholic hepatitis and can be produced in mouse hepatocytes by chronic griseofulvin (GF) intoxication. The formation of MBs, which share some immunological, biochemical, and ultrastructural features with cytokeratin (CK) filaments of normal liver, is accompanied by derangement and even loss of the CK cytoskeleton of hepatocytes ("empty cells") as revealed by immunofluorescence microscopy. To clarify whether this diminution or lack of CK-related staining of MB-containing hepatocytes was due to loss of CK filaments or changes in antigenicity or accessibility of antigenic determinants immunohistochemical studies using a battery of monoclonal and polyclonal CK antibodies were performed. It could be shown that all these antibodies directed against different CK polypeptide components and antigenic determinants of CKs revealed a highly reduced or even undetectable cytoplasmic CK meshwork in most cells with fully developed large MBs. In the light of our present knowledge of the organization of CK intermediate filaments, these results indicate that the phenomenon of the "empty cells" reflects a diminution of CK meshwork rather than altered antigenic determinants.

Animals↗
PubMed1991

High molecular weight components are main constituents of Mallory bodies isolated with a fluorescence activated cell sorter.

Mallory bodies (MBs) are cytoplasmic filamentous aggregates containing cytokeratin (CK) material. They occur in hepatocytes of patients with alcoholic liver disease (i.e., alcoholic hepatitis) and can also be induced experimentally in mice by chronic griseofulvin intoxication. To further investigate components and mechanisms involved in MB formation, a new method for MB purification was established. MBs present in a liver homogenate of griseofulvin-fed mice were labeled with a murine monoclonal antibody specific for MBs and a second fluorescein isothiocyanate-conjugated (anti-mouse IgG and IgM) antibody and subsequently isolated by two sequential sorting procedures using a fluorescence activated cell sorter (FACS). Purity of MB isolates was over 90% as revealed by computer analysis of sorting signals and fluorescence and electron microscopy. Electrophoretic separation on sodium dodecyl sulfate-polyacrylamide gels revealed three MB-related polypeptides with apparent molecular masses of 48, 55, and 65 kilodaltons but most of the highly purified MB material did not enter the gel or remained at the interphase between stacking and resolving gels. Western blotting with CK-specific antibodies showed the presence of CK epitopes in the high molecular weight MB material, which has a similar amino acid composition as normal liver CKs. These results establish that very high molecular weight material is the main constituent of MBs and suggest that a post-translational modification of CKs by covalent crosslinks is a principal mechanism of MB pathogenesis.

Amino Acids↗
PubMed1991

Modulation of alpha smooth muscle actin and desmin expression in perisinusoidal cells of normal and diseased human livers.

It has been suggested that perisinusoidal liver cells (PSC) play a pivotal role in the pathogenesis of fibrocontractive changes. Using light and electron microscopic immunolocalization techniques, a series of 207 normal and pathologic human liver specimens were evaluated for the expression of alpha smooth muscle (SM) actin and desmin in this and other nonparenchymal cell types. In normal adult liver tissue, PSCs were practically devoid of desmin and exceptionally stained for alpha-SM actin, whereas this actin isoform frequently was encountered in PSCs from the embryonic to the adolescent period. A broad spectrum of pathologic conditions was accompanied by the presence of alpha-SM actin containing PSCs; these were detected preferentially in periportal or perivenular zones according to the predominant location of the underlying hepatocellular damage. The occurrence of this PSC phenotype generally was associated with fibrogenesis and was in some cases detected earlier than overt collagen accumulation. Fibrous bands subdividing liver tissue in cirrhosis and focal nodular hyperplasia, as well as desmoplastic reaction to malignant tumors, contained alpha-SM actin-rich cells admixed with variable proportions of cells coexpressing desmin. In end stages, this population was less numerous than in active fibrotic or cirrhotic processes. Using immunogold electron microscopy, alpha-SM actin was localized in microfilament bundles of typical PSCs. Our results are compatible with the assumption that the appearance of alpha-SM actin and desmin-expressing myofibroblasts results at least in part from a phenotypic modulation of PSCs.

Actins↗
PubMed1991

[Impulse cytophotometry determination of the DNA content of paraffin-fixed neuroblastoma].

The aim of the study was to develop a method to obtain a single cell suspension from paraffin fixated neuroblastoma tissue for measuring the DNA content by flow cytometry, and to detect possible correlation between the histological grading and the DNA stemline, and to relate these findings to the patients' prognosis. 51 samples of the fixated neuroblastoma tissue were measured. It was possible to determine the DNA content in 38 probes of the material. 79% of the evaluated samples showed aneuploid DNA stemlines, 21% showed euploid stemlines. Despite the small number of probes it was found, that in relation to the histological grading of neuroblastoma a lower grade of malignancy correlated with an euploid DNA content and a higher grade of malignancy correlated with an aneuploid DNA content. A correlation between DNA stemlines and the patients' prognosis was not found.

Adolescent↗
PubMed1990

Fate of Mallory body-containing hepatocytes: disappearance of Mallory bodies and restoration of the hepatocytic intermediate filament cytoskeleton after drug withdrawal in the griseofulvin-treated mouse.

Mallory bodies are characteristic morphological features of alcoholic hepatitis in man and can be produced in the mouse by chronic griseofulvin intoxication. The appearance of Mallory bodies in hepatocytes is associated with derangement of the cytokeratin intermediate filament cytoskeleton, at least as revealed by immunofluorescence and suggested by immunoelectron microscopy. Immunohistochemical studies were performed to answer the question whether Mallory body formation and cytoskeleton alterations finally lead to cell death or are reversible phenomena. Chronically griseofulvin-intoxicated mice killed at different stages of recovery on a normal diet served as experimental animals. It could be shown that (a) Mallory bodies are very durable structures and are found for up to 6 mo after griseofulvin withdrawal as a result of persistence and neoformation; (b) new Mallory bodies can appear even several months after cessation of griseofulvin feeding; (c) Mallory body formation and cytoskeletal changes by themselves do not lead to irreversible cell damage; (d) the cytoskeletal changes are reversible within 7 mo after griseofulvin withdrawal; (e) a dissociation between disappearance of Mallory bodies and restoration of a regularly immunostained cytoplasmic cytokeratin meshwork is observed.

Animals↗
PubMed1990

One-year treatment of chronic non-A, non-B hepatitis with interferon alfa-2b.

Thirty patients with chronic non-A, non-B hepatitis (24 male, six female; median age 38 years, range: 15-68 years) were treated with recombinant interferon alfa-2b for 1 year. Treatment was started with 5 million units interferon alfa-2b daily for 2 weeks followed by 2 million units daily for another 2 weeks. Further doses were titrated according to alanine aminotransferase values. After 1 year, treatment was stopped and a follow-up biopsy was obtained. Thereafter, patients were followed for 6 months. Of the 24 patients who completed the 1-year treatment period, 14 (58%) had normal alanine aminotransferase values at the end of the study, eight of whom showed transient increases while on treatment. In another seven (29%), alanine aminotransferase levels decreased by more than 50% of pre-treatment values but remained above the normal range. Biopsies at the end of treatment showed a complete disappearance of inflammatory activity in four and a marked improvement in eleven other patients. The results of this study indicate that a 1-year treatment with recombinant interferon alfa-2b of patients with non-A, non-B hepatitis was very effective at normalizing or improving serum transaminases and liver histology. However, the overall relapse rate was 57%, with relapse occurring in a greater proportion of patients with temporary breakthroughs during therapy (requiring dosage increase), and particularly of patients with only a partial response to treatment (serum transaminases decreased by greater than or equal to 50%). Thus, further studies are needed to establish the optimal dose and duration of treatment to induce a complete resolution of the disease.

Adult↗
PubMed1990

Peculiar changes in Rosenthal fibres in an atypical astrocytoma.

A 50-year-old female patient died of an untreatable glioma apoplecticum. At autopsy a strongly vascularized glial tumour was found. The criteria for malignancy according to the WHO classification were only partially fulfilled by this tumour which displayed morphological features of an astrocytoma but could not be further subclassified. By light microscopy, angioma-like vascular proliferations, large cells with brightly eosinophilic cytoplasm, and small cells with hyperchromatic nuclei were found. Most large cells had vesicular, excentrically placed nuclei and contained fibrillary whorls or amorphous, irregular cytoplasmic inclusions. By immunohistochemical staining, using antibodies to glial fibrillary acidic protein (GFAP) the fibrillary whorls were identified as aggregates of glial filaments. The amorphous inclusions lacked GFAP immunoreactivity and appeared in the electron microscope as electron dense material surrounded by a dense network of glial filaments. The abnormal perikaryal inclusions of these atypical astrocytoma cells appeared to be peculiar alterations of Rosenthal fibres closely mimicing Mallory bodies.

Astrocytes↗
PubMed1990

High molecular weight component of Mallory bodies detected by a monoclonal antibody.

To identify Mallory body (MB) constituents, monoclonal antibodies to murine MBs induced by long-term griseofulvin (GF) feeding were produced. One of these, antibody MM 120-1, specifically reacted in immunofluorescence microscopy with MBs in all developmental stages but not with other cell structures of human and mouse liver and other organs. The MM 120-1 antigen was present in murine MBs induced by griseofulvin or 3,5-diethoxycarbonyl-1,4-dihydrocollidine feeding and also in human MBs in livers of patients with alcoholic hepatitis. In immunoblots, the MM 120-1 antigen was detectable in the high molecular weight fraction of MB preparations, most of which remained in the well and at the interphase between stacking and resolving gel. No reactivity with cytokeratin polypeptides of different conformational states (i.e., isolated cytoker atin components A and D, heterotetramers A2D2, reconstituted intermediate filaments) was found. It is concluded that the antibody MM 120-1 is a highly specific and sensitive marker for murine and human MBs recognizing a high molecular weight nonkeratin component. This component could play a central role in the pathogenesis of MBs.

Animals↗
PubMed1990

[Cytoskeleton--function and pathology: studies on the pathology of the intermediate filament cytoskeleton of liver cells].

Microfilaments, microtubules and intermediate filaments (IF) are major filamentous components of the cytoskeleton and play a role in the modulation of cell shape, in cellular movements, cellular stability, intracellular organisation as well as cell-to-cell and cell-to-stroma interactions. Particular interest was concentrated in the last few years on IF because of their cell type-specificity and, consequently, their suitability as cell markers in diagnostic pathology. Despite their apparent stability, IF are dynamic structures which may be modified under pathologic conditions. In recent years, pathologic alterations related to the IF cytoskeleton have been described in a diversity of chronic and degenerative disorders, including alcoholic hepatitis and neurologic diseases (e.g. M. Alzheimer, M. Parkinson). Our studies were particularly devoted to the elucidation of the pathogenesis of severe alcoholic liver injury (alcoholic hepatitis), which is associated with inflammation, liver cell degeneration and necrosis and morphologically characterized by the appearance of cytoplasmic hyaline inclusions (i.e., Mallory bodies). In the present review morphologic, immunologic and biochemical studies on nature and pathogenesis of Mallory bodies are summarized. Moreover, similarities between Mallory bodies and other cytoskeleton-related inclusion bodies suggest common routes of pathogenesis. Consequently, studies along these lines may not only lead to the understanding of mechanisms involved in alcoholic injury but may also provide information on general principles of cell damage as well as on regulation and function of the IF cytoskeleton.

Animals↗
PubMed1989

[Hepatitis delta virus infection: an immunohistochemical study].

Hepatitis delta virus (HDV) is a pathogenic and transmissible virus which requires the helper function of hepatitis B virus for its replication. Epidemiological studies have shown that HDV infection is distributed world-wide, with a higher prevalence in southern areas, especially in Italy. HDV may increase the severity of chronic hepatitis and may be responsible for the fulminant course of this disease. To assess the prevalence and pathogenic role of HDV infection in our geographic area we examined 118 biopsies from HBsAg-positive patients by immunofluorescence microscopy. HDV was detected in 3 biopsies with the histological features of chronic active hepatitis. Our findings show that HDV infection is a rare event among HBsAg carriers in our area.

Adult↗
PubMed1989

Hepatocellular cytokeratins as substrates of transglutaminases.

To examine whether hepatocellular cytokeratins can serve as substrates of transglutaminases (TG) TG-catalyzed incorporation of [3H]putrescine into, as well as cross-linking of, cytokeratins was studied. Purified guinea pig liver TG and mouse liver TG present in 105,000 x g supernatants were used as enzymes. Isolated mouse liver cytokeratin filaments, heterotypic tetramers (A2D2), as well as cytokeratin filaments reconstituted from isolated and column-purified liver cytokeratin polypeptides A and D served as substrates. Moreover, to more closely mimic the situation within the cell, mouse liver homogenate containing cytokeratins was also used. Cross-linked proteins were identified as cytokeratins by immunoblotting after sodium dodecyl sulfate-polyacrylamide gel electrophoresis using cytokeratin antibodies. The results indicated that mouse liver cytokeratins can serve as substrates of homologous and heterologous TG. However, liver cytokeratin components A and D differed in this respect. Depending on the experimental conditions either components D or components A were better substrates of TG-mediated cross-linking as revealed by increased high molecular weight aggregates, which failed to enter the gels, concomitant with a decrease of the monomer band suggesting a more intimate relationship between homologous cytokeratin polypeptides within the filament. The results presented provide the basis for studies of TG-induced cross-linking of cytoskeletal components in hepatocytes that may occur during liver cell injury associated with increased intracellular Ca2+ concentrations.

Animals↗
PubMed1989

[Immunohistochemical analysis of 42 renal cell carcinomas and one oncocytoma with mono- and polyclonal antibodies against vimentin and cytokeratin].

42 renal cell carcinomas and 1 oncocytoma were investigated by means of immunofluorescence (including double immunofluorescence) using a panel of mono- and polyclonal antibodies to vimentin and cytokeratins. In all tumors except chromophobe cell renal carcinoma (CCRC) and oncocytoma generally a coexpression of vimentin and cytokeratins could be demonstrated; however, the intermediate filament expression was often very heterogeneous with regard to the distribution of vimentin and cytokeratins in general, depending on the mono- and polyclonality of the antibodies and on the areas of a tumor investigated. In CCRC and oncocytoma all tumor cells contained cytokeratin filaments. In addition, as revealed by double immunofluorescence, in only occasional tumor cells we could demonstrate vimentin.

Adenocarcinoma↗
PubMed1989

[Is percutaneous liver biopsy using the Trucut (Travenol) needle superior to Menghini puncture?].

The aim of this study was to compare the quality of biopsy cylinders obtained by the Menghini or Trucut liver biopsy-method as well as the frequency of complications observed with both these methods. For this purpose, 74 Menghini and 62 Trucut biopsies were analyzed. Both groups were comparable with respect to histologic diagnosis, but no final diagnosis could be made in eight cases of Menghini biopsy because of insufficiency of the material obtained. Fragmentation of the sample occurred significantly more often in the Menghini group (p less than 0.05; chi 2 test). Trucut biopsies were significantly longer (12 mm versus 8 mm mean value; p less than 0.001; Wilcoxon rank sum test) and contained significantly more portal tracts (16 versus 6 mean value; p less than 0.001). None of the total 136 biopsies led to serious complications. We conclude that Trucut liver biopsy is superior to the Menghini method since tissue yield is better and both methods are equally safe.

Adolescent↗
PubMed1988

[Colorectal cancer: classification and aspects of the proliferation kinetics].

The exact tumor classification by the pathologist is the basis of adequate therapy of colorectal carcinomas. The classification includes the determination of the histological type of the carcinoma and the grading according to the criteria of the WHO and the UICC, as well as the staging according to the TNM system of the UICC and the Dukes classification. Most colorectal carcinomas are adenocarcinomas of tubular, tubulo-papillary and papillary subtypes. Mucinous adenocarcinomas are characterized by a pronounced extracellular mucus production. Signet ring cell carcinomas with intracellular mucus production are very rare and predominantly localized in the right-sided colon. Adeno-squamous carcinomas and squamous cell carcinomas are extremely rare in the large bowel. They are only mentioned for completeness. The histological grading proposed by the WHO distinguishes carcinomas of well (G1), moderately well (G2) and poor (G3) differentiation. Well and moderately well differentiated tumors can be regarded as carcinomas with low grade of malignancy, whereas poorly differentiated ones are carcinomas with high grade of malignancy. The new grading of the UICC distinguishes in addition to the well, moderately well and poorly differentiated carcinomas the undifferentiated tumors (G4). G1 and G2 correspond to low grade, G3 and G4 to high grade of malignancy. According to the 1987 nomenclature of the UICC-TNM system pT1 denotes tumor spread to the mucosa, or mucosa and submucosa, pT2 to the muscularis propria, pT3 into the subserosa or into nonperitonealized pericolic or perirectal tissue and pT4 a perforation of the visceral peritoneum or a spread into other organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Colonic Neoplasms↗
PubMed1988

[Classification of colorectal cancers: current results from the catchment area of the Graz Institute of Pathology].

In comparison with the results of Dukes the percentage of stage Dukes A of colorectal carcinomas could be increased from 15% to about 27%, whereas the percentage of stage Dukes C decreased from 51 to 40% in some international medical centers during the seventies of this century. Our results in Styria are comparable. However, there was no further progress in the early diagnosis of colorectal carcinomas in Styria from 1984 to 1986 (42% of Dukes C stage cases) as compared with 1974 to 1979 (41% of Dukes C stage cases). The percentage of endoscopically removed tumors increased from 3% (1974 bis 1979) to 9% (1984 to 1986) of all curatively treated carcinomas. Because of the fact that the endoscopically removed tumors (stage pT1pNx) could not be classified according to Dukes, the percentage of Dukes stage A decreased from 30% (1974 to 1979) to 24% (1984 to 1986). But the small numbers of endoscopically removed tumors did not significantly influence the percentage of Dukes C stages. There was only partial success in the predominantly rural areas in which the percentage of Dukes C stages decreased from 47% (1974 to 1979) to 39% (1984 to 1986). 39% Dukes stage C in rural areas correspond to the percentage of the predominantly municipal areas (40%). This progress can be explained by the availability of colonoscopy to all hospitals in 1984 to 1986, which was not the case previously.(ABSTRACT TRUNCATED AT 250 WORDS)

Austria↗
PubMed1988

Immunohistologic heterogeneity of malignant tumors.

Intratumor heterogeneity exists in most, if not all, human solid tumors and is reflected by differences in morphology, antigenicity, chromosomal and biochemical markers, invasion, metastatic spread, as well as sensitivity to therapy. Heterogeneity may be the result of genetic and/or environmental mechanisms. To be assessed by immunohistochemistry, heterogeneity of tumor cells has to be expressed by antigenic changes, i.e. quantitative or qualitative differences in antigen expression, secretion or uptake. Consequently, presence and distribution of hormones, steroid hormone receptors (e.g., in mammary carcinomas), blood group antigens (e.g., in diverse carcinomas), and cytoskeletal components, particularly intermediate filament-associated proteins (e.g., in neoplasms of diverse origin), can indicate heterogeneity within a tumor.

Breast Neoplasms↗