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Biomedical subjects

M Karasek

Publications and source records attributed to M Karasek.

At least 91 records · Page 5Linked to original sources
PubMed1979

Limitations in the use of [3H]thymidine incorporation into DNA as an indicator of epidermal keratinocyte proliferation in vitro.

The validity of using the incorporation of [3H]thymidine into DNA as an indicator of epidermal keratinocyte proliferation in vitro has been investigated. Other parameters of cell proliferation, direct count of cell number and measurement of DNA content, consistently fail to correlate with changes in [3H]thymidine incorporation into DNA in primary and first passage cultures of rabbit and human epidermal keratinocytes. Maximum incorporation of [3H]thymidine precedes the active growth period by three days. Incorporation declines markedly during the proliferative period. Thymidine kinase activity decreases during the proliferative growth phase. Incorporation of another pyrimidine nucleotide precursor, [14C]aspartic acid, suggests that in epidermal keratinocytes in vitro the extent of utilization of the salvage and the de novo pathways may be inversely related. In such cases [3H]thymidine incorporation into TCA precipitable material fails to reflect accurately cell proliferation.

Animals↗
PubMed1978

Ultrastructure of rat pinealocytes in vitro: influence of gonadotropic hormones and LH-RH.

The influence of gonadotropic hormones on the ultrastructure of rat pinealocytesin short-term organ culture was studied. Human chorionic gonadotropin (HCG), as well as pregnant mare serum gonadotropin (PMSG), caused a marked activation of pinealocytes. An hypothesis is discussed implying the presence of a feedback mechanism between the pineal organ and the hypothalamo-hypophysial system.

Animals↗
PubMed1978

Influence of gonadotropic hormones on the ultrastructure of rat pinealocytes.

The influence of gonadotropic hormones on the ultrastructure of rat pinealocytes was studied. Human chorionic gonadotropin (HCG) as well as pregnant mare serum gonadotropin (PMSG) caused a marked activation of pinealocytes. It is characterised by a conspicuous proliferation of the granular endoplasmic reticulum and Golgi apparatus as well as an increase in number of dense core vesicles, mitochondria, dense bodies, subsurface cisternae and vesicles in the terminal buds of pinealocyte processes. The changes after HCG administration were more pronounced than after PMSG.

Animals↗
PubMed1978

Isolation and serial cultivation of rabbit skin epithelial cells.

A method to isolate and to serially cultivate rabbit skin epithelial cells from adult trunk skin has been developed. Using a collagen gel as substrate and trypsin and EDTA to dissociate cells, nonproliferative primary cultures of rabbit cells may be converted to proliferative populations, and at least 3 serial passages achieved. In the presence of large concentrations of methotrexate (up to 1000 microgram/ml), epithelial cells in primary culture show no decrease in their ability to attach, spread, or keratinize. Following conversion to proliferative populations by trypsin and EDTA low concentrations of methotrexate (1 microgram/ml) are strongly cytotoxic. When the incorporation of 32PO4(3-) and 3H-thymidine into DNA of proliferative and nonproliferative cells is compared, the incorporation of 32PO4(3-), but not that of 3H-thymidine, correlates with changes in cell number and DNA content. In both primary and serially cultivated cells, L-serine is required for optimal growth.

Animals↗
PubMed1978

Isolation and growth of adult human epidermal keratinocytes in cell culture.

Human epidermal keratinocytes may be isolated in high yield from 0.1 mm keratotome sections of adult skin by short-term trypsin release. When plated on a collagen-coated plastic surface or on a collagen gel, keratinocytes attach with high efficiencies (greater than 70%) and form confluent, stratified cultures. Cell populations of predominantly basal cells produce proliferative primary cell cultures while populations of basal cells and malpighian cells result in nonproliferative primary cultures. Both nonproliferative and proliferative primary cultures may be subcultured on collagen gels following dispersion by trypsin and EDTA. Methotrexate strongly inhibits proliferative keratinocytes at low concentrations (0.1 microgram/ml) but has no cytotoxic effect on non-proliferative cells. L-serine and dexamethasone increase the multiplication rate of both primary and subcultured human keratinocytes.

Adult↗