Biomedical subjects

L Malick

Publications and source records attributed to L Malick.

7 recordsLinked to original sources

PubMed1979

Maintenance of adult rat hepatocytes on C3H/10T1/2 cells.

A procedure is described for maintaining primary cultures of adult rat hepatocytes on a layer of irradiated C3H/10T1/2 cells. These hepatocytes were capable of metabolizing the liver carcinogen N-2-acetylaminofluorene to water-soluble products and after 14 days in culture could still metabolize approximately 70% of the Day 1 level. Hepatocytes maintained on the C3H/10T1/2 cells were inducible for the liver-specific enzyme tyrosine aminotransferase, and exhibited approximately a 4-fold induction by hydrocortisone during a 10-day culture period. Morphologically, these hepatocytes retained many characteristics of hepatocytes in vivo. By contrast, hepatocytes maintained on plastic lost both N-2-acetylaminofluorene-metabolizing ability and tyrosine aminotransferase activity by Day 5. This was presumably due to degeneration of the hepatocytes and an overgrowth by fibroblasts. The maintenance of morphologically and biochemically functional hepatocytes in culture on feeder cells may provide a valuable approach for studying drug metabolism and liver cell transformation in vitro.

2-Acetylaminofluorene↗

PubMed1978

Ganglioside and morphological changes in mouse embryo cells with time.

Ganglioside and morphological changes were observed in C3H/10T1/2CL8 cells during a 4-year period of maintenance in the laboratory. The cellular morphology at confluency, as determined by scanning electron microscopy, changed from being polygonal and flattened to a fusiform shape with some piling up of cells. The saturation density increased about three-fold and the level of the simplest ganglioside GM3 (N-acetylneuraminylgalactosylglucosylceramide) increased about two-fold. While the reasons for the alterations are unknown, the data suggest a relationship among ganglioside composition, cellular morphology and regulation of cell growth. The possible implications of such biochemical and biological changes on studies comparing normal and transformed cells are discussed.

Cells, Cultured↗

PubMed1976

Scanning electron-microscopic study of the surface characteristics of neoplastic endothelial cells of blood vessels.

The morphological surface characteristics of neoplastic endothelial cells of blood vessels induced by oral administration of 1,2-dimethylhydrazine dihydrochloride in mice were studied by scanning electron microscopy. The interconnecting vascular channels were lined by malignant endothelial cells which formed bridges, cord-like structures and had extended cytoplasmic processes which made the network more intricate. The endothelial cells were often in close approximation to each other and exhibited irregular growth patterns and orientation. The cell surface displayed a rugged, terrace-like microcontour of elevations, depressions, blebs and nodular structures. These findings correlate with the earlier morphological observation obtained by transmission electron microscopy.

Animals↗

PubMed1976

Production of intestinal and other tumours by 1,2-dimethylhydrazine dihydrochloride in mice. II. Scanning electron microscopic and cytochemical study of colonic neoplasms.

Thum of colon induced by repeated subcutaneous injections of 1,2-dimethyl-hydrazine dihydrochloride in mice were studied by scanning electron microscopy. In addition, the surface composition of normal and malignant colonic epithelial cells were investigated by ultrastructural cytochemistry. The neoplastic, nodular tumour masses which protruded into the lumen of colon displayed an asymmetrical, irregular growth pattern and surface contour. In contrast to the normal surface structure, the shape of crypt openings in malignant areas was distorted and they were irregularly spaced. Cells varying in size and shape in the intercrypt regions often formed random patterns of elevations and depressions. Microvilli on neoplastic cells were larger, more club-shaped and showed more disorderly arrangement than their normal counterparts. The distribution and quantity of surface acid mucopolysaccharide content and adenosine triphosphatase activity varied considerably from cell to cell in the neoplastic epithelium while they were more uniform in the normal colonic surface cells.

Adenocarcinoma↗

PubMed1976

The ultrastructure of oncolytic spores found on pig skin.

A new type of clostridium spore, derived from melanotic hamster tumors treated with pig skin extracts, was examined in a lyophylized form by electron microscopy (EM). Scanning EM indicated that two out of five preparations contained only spores. The spores exhibited oval forms (1.5 X 1.0 MU)with elongated, sometimes infolded, poles indicating an overlying membrane. These structures corresponded to the exosporium as seen by transmission EM. The size of the spores, including the cortex (350-550 A), inner membranes, and cytoplasm averaged 5100 X 5900 A. Cytochemical findings suggest that acid mucopolysaccharides and polypeptides containing N-acetyl-neuraminic acid are localized within the exterior and interior layers of the exosporium and at the surface of the outer coat, which could have a tumor inhibiting effect.

Animals↗

PubMed1976

Pancreatic neoplasms induced in Syrian golden hamsters. I. Scanning electron microscopic observations.

Pancreases from Syrian golden hamsters treated with N-nitrosobis(2-hydroxy-proply)amine for 10 to 25 weeks were examined under scanning electron microscopy (SEM). Findings indicate that the neoplasms originated from the ductal epithelium and developed progressively. Adenomas were lined by epithelium of differing cells types, ranging from a flat singly ciliated form to cuboidal-columnar types, or to mixed cell populations. The epithelial lining of the ductal carcinomas exhibited tubular and papillary cystic spaces, and cell surfaces were similar to the cuboidal and columnar epithelium of adenomas and of ductal epithelial hyperplasia. However, microvilli were dense and of varied lengths. The SEM observations correlated with patterns seen in routine histologic preparations.

Animals↗

PubMed1976

Production of intestinal and other tumors by 1, 2-dimethylhydrazine dihydrochloride in mice. I. A light and transmission electron microscopic study of colonic neoplasms.

Single or ten weekly subcutaneous injection(s) of 1, 2-dimethylhydrazine dihydrochloride were administered separately to Swiss mice. The repeated application gave rise mainly to high incidences of tumors in the large intestine. These neoplasms occurred most frequently in the colorectal area and in cecum adjacent to ileum. Light microscopically, these lesions were classified as polypoid adenomas and adenocarcinomas. Most of the adenocarcinomas were highly invasive, although they metastasized rarely. The fine structure of the malignant cells exhibited features typical of columnar absorptive cells. A distinctive alteration was the disorderly arrangement and abnormal size and shape of the microvilli. In addition, the cells exhibited numerous free ribosomes, little RER, priminent Golgi bodies, and uniformly dispersed nuclear chromatin. Morphologically, the intestinal tumors were similar to those found in man. In addition, the repeated administration of 1, 2-DMH also induced significant incidences of neoplasms in blood vessels, lungs, anus, and kidneys while the single application produced tumors in blood vessels and liver. The main hypotheses attempting to explain the selective induction of large intestinal neoplasms are discussed.

Adenocarcinoma↗