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H Zerban

Publications and source records attributed to H Zerban.

50 records · Page 3Linked to original sources
PubMed1981

Mitochondrial anomalies in renal oncocytes induced in rat by N-nitrosomorpholine.

Renal oncocytes were induced in male Sprague-Dawley rats by oral application of N-nitrosomorpholine (NNM) in a concentration of 12 or 50 mg per 100 ml drinking water and analysed by transmission electron microscopy. The oncocytes exhibited mitochondrial anomalies which were very similar to those of human oncocytoma oncocytes. The most striking mitochondrial changes were an unusually large number of the organelles and an excess of the cristae mitochondriales. The shape of the mitochondria varied from round and oval to extremely elongated slender or cup-shaped organelles often piled up to form complex bodies. Rarely large ramifying mitochondria were found. In addition to transversely orientated cristae or tubules the inner mitochondrial membranes frequently formed dense stacks of unusually long cristae often arranged longitudinally. In some mitochondria straight and strictly parallelly arranged neighbouring cristae were found to be connected by a paracrystalline array of pillars bridging the mitochondrial matrix. In the majority of oncocytes the mitochondrial matrix contained prominent dense granules (diameter 30-50 nm), but sometimes these were rare or absent. Individual mitochondria of many oncocytes showed membrane-bound deposits of glycogen particles which usually formed rosettes (alpha-particles) with a diameter of about 80 nm. Partitioned mitochondria were not seen. Often autophagic vacuoles containing portions of degraded mitochondria and dense bodies, probably autophagosomes, were observed. The nature and significance of the oncocytes remains unclear, but we suggest from these and earlier experimental results that oncocytes represent a special type of a neoplastically transformed cell which usually has only a low potential for "autonomous" growth. Renal oncocytes induced in rats by chemical carcinogens appear to be an excellent experimental model for the further investigation of this cell type.

Animals↗
PubMed1980

[Morphogenesis and micromorphology of epithelial tumors induced in the rat kidney by nitrosomorpholine. IV. Tubular lesions and basophilic tumors (author's transl)].

The genesis of basophilic cell kidney tumors was investigated stepwise by light and electron microscopy in rats treated with N-nitrosomorpholine for a limited time (stop experiment). Seven weeks after the beginning of the experiment the kidney tubules sometimes showed unusually large "chromophobic" and basophilic cells. After a lag period of 22-97 weeks more than 60% of the animals had developed these atypical tubules. Parallel to the appearance of chromophobic tubules 50% of the carcinogen-treated animals developed basophilic cell kidney tumors. All intermediate stages between chromophobic or basophilic cell tubules and tumors were found. During the neoplastic transformation chromophobic epithelia appeared to change into basophilic cells. Some of the chromophobic renal tubules and most of the renal tubules which consisted of chromophobic and basophilic epithelia stored acid mucopolysaccharides as demonstrated by histochemical methods. The fine structure of the basophilic epitheliomas was relatively uniform. The basophilia observed under the light microscope correlated with abundant membrane-bound and free ribosomes as seen under the electron microscope. The frequent appearance of brush borders and microbodies indicated the origin of the basophilic cell tumors from proximal renal tubules. In some tumor cells many mitochondria were found. These cells resembled oncocytes. However, in contrast to typical oncocytes the mitochondria of these cells were poor in cristae or showed tubular formations of the inner membrane. In some mitochondria homogeneous condensations could be detected in the intracristal space and tooth-like formations were seen on the surface of the cristae. In perpendicular sections these cristae resembled saw blades. Acute tubular lesions and cellular regeneration, as described earlier by other authors in early stages of the development of kidney tumors, were not found. It is suggested that the storage of acid mucopolysaccharides observed in many tubules and in some renal tumors indicates a disturbance of the cellular metabolism which plays an important role in tumor development.

Animals↗
PubMed1980

Liver tumors distinguished by immunofluorescence microscopy with antibodies to proteins of intermediate-sized filaments.

Antibodies against constitutive proteins of different types of intermediate-sized filaments were used in immunofluorescence microscopy on frozen sections of normal rat liver and various rat liver tumors induced by treatment with nitrosamines. Antibodies to tonofilament prekeratin stained bile duct epithelia and hepatocytes of normal liver and hepatocellular carcinoma cells and ductal cells of cholangiofibromas. These cells were not significantly stained by antibodies to vimentin. By contrast, antibodies to vimentin stained mesenchymal cells of normal liver and cells of early and advanced angiosarcomas and of undifferentiated spindle cell sarcoma. These mesenchymal tumor cells were not stained with antibodies to prekeratin. The presence of intermediate-sized filaments in these tumors, often in large whorl-like aggregates, was also demonstrated by electron microscopy. The results show that immunofluorescence microscopy with antibodies to cytoskeletal proteins is a powerful tool for the classification and differential diagnosis of mesenchymal and epithelial liver tumors. We propose that staining with antibodies to proteins of different types of intermediate filaments can be used to improve the identification of tumors of other organs, including metastases, as well as non-neoplastic proliferative lesions.

Adenoma, Bile Duct↗
PubMed1978

Milk fat globule membranes devoid of intramembranous particles.

When isolated milk fat globule membranes from bovine, human, and murine (rat) milk were examined by freeze-fracturing most of the membrane faces were devoid of membrane-intercalated particles whereas a minor portion showed relatively few particles, either in clusters or in apparent random distribution. A reduced particle density was also noted in membranes of intra-alveolar milk fat globules of cows and rats, in contrast to high particle densities in the apical plasma membrane of lactating epithelial cells. The observations suggest that certain membrane constituents recognized as intramembranous particles either are displaced from the region of the apical surface of the mammary epithelial cell which is involved in milk fat globule budding or are dislocated and rearranged during the budding process.

Animals↗
PubMed1978

Modified desmosomes in cultured epithelial cells.

Junctional complexes are described in various cultured cells of epithelial origin and morphology which show structural features different from those of both typical maculae adhaerentes and fasciae adhaerentes. Established rat kangaroo kidney-derived cell lines (PtK1 and PtK2) and secondary cultures of cells derived from lactating bovine mammary gland epithelium (BMGE) have been studied in particular detail. Several types of modified desmosomes are described which are characterized by altered dimensions and spacings of the individual desmosomal units, variations in intercellular gap width, less distinct submembranous coats and midline structures (dense strata) of the intercellular space, and lack of attachment of typical tonofibril-like bundles of tonofilaments. The observations suggest that progressive changes in junction morphology from desmosome-like to that of a more intermediate junction frequently occur during in vitro culturing of epithelial cells.

Cell Line↗
PubMed1977

Structures indicative of keratinization in lactating cells of bovine mammary gland.

Keratohyalin granule-like aggregates and tangles of filaments similar to epidermal prekeratin fibrils have been observed in lactating cells of bovine mammary epithelium. The concomitant occurence of such structures, which are characteristic of early stages of keratinization, with typical secretory products such as casein micelles demonstrates that keratinization can take place in functional secretory cells. The observations are discussed in relation to current concepts of keratinization in epidermal and in non-epidermal epithelia.

Animals↗
PubMed1976

Involvement of vesicle coat material in casein secretion and surface regeneration.

The ultrastructure of the apical zone of lactating rat mammary epithelial cells was studied with emphasis on vesicle coat structures. Typical 40-60 nm ID "coated vesicles" were abundant, frequently associated with the internal filamentous plasma membrane coat or in direct continuity with secretory vesicles (SV) or plasma membrane proper. Bristle coats partially or totally covered membranes of secretory vesicles identified by their casein micelle content. This coat survived SV isolation. Exocytotic fusion of SV membranes and release of the casein micelles was observed. Frequently, regularly arranged bristle coat structures were identified in those regions of the plasma membrane that were involved in exocytotic processes. Both coated and uncoated surfaces of the casein-containing vesicles, as well as typical "coated vesicles", were frequently associated with microtubules and/or microfilaments. We suggest that coat materials of vesicles are related or identical to components of the internal coat of the surface membrane and that new plasma membrane and associated internal coat is produced concomitantly by fusion and integration of bristle coat moieties. Postexocytotic association of secreted casein micelles with the cell surface, mediated by finely filamentous extensions, provided a marker for the integrated vesicle membrane. An arrangement of SV with the inner surface of the plasma membrane is described which is characterized by regularly spaced, heabily stained membrane to membrane cross-bridges (pre-exocytotic attachment plaques). Such membrane-interconnecting elements may represent a form of coat structure important to recognition and interaction of membrane surfaces.

Animals↗
PubMed1975

Growth of the nuclear envelope in the vegetative phase of the green alga Acetabularia. Evidence for assembly from membrane components synthesized in the cytoplasm.

The primary nucleus of the green alga Acetabularia grows about 25,000-fold in volume while it is separated from the endoplasmic reticulum and the whole cytoplasm by a special paranuclear cisterna of a vacuolar labyrinthum system which shows only very few (two to six per square micrometer) and small (ca. 40-120 nm in diamter) fenestrations. The nuclear envelope does not bear polyribosomes, nor do they occur in the entire zone intermediate between the nuclear envelope and the paranuclear cisterna. It is suggested that this special form of nuclear envelope growth takes place by assembly from cytoplasmically synthesized proteins that are translocated across the paranuclear cisterna in a nonmembrane-structured form.

Acetabularia↗