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Biomedical subjects

J Litwin

Publications and source records attributed to J Litwin.

At least 55 records · Page 3Linked to original sources
PubMed1971

Standardization of human diploid fibroblast cultivation: trypsinization procedure.

Human embryonic diploid lung fibroblasts were used to examine the influence of the trypsinizing procedure on the growth and adsorption of these cells. The best buffer for trypsinizing these cells was Hanks balanced salt solution containing 0.5% lactalbumin hydrolysate. Trypsinizing cells at 4 C gave better growth results than trypsinization at higher temperatures. The presence of antibiotics in the trypsin buffer increased the longevity of the cells. Cells initially trypsinized from tissue in phosphate-buffered saline without Ca(2+) or Mg(2+) and 0.33 m sucrose plus 10(-3)m Mg(2+) gave rise to better subsequent growth and adsorption than cells from tissue trypsinized in other buffers.

Adsorption↗
PubMed1971

Standardization of human diploid fibroblast cultivation: centrifugation procedure.

The effect of varying centrifugal forces on the growth rate, longevity, and adsorption on glass of human embryonic diploid lung fibroblasts was studied. Cells centrifuged at 120, 500, or 1,500 x g at each passage had similar growth rates but their longevity decreased slightly with increasing force. These forces had no influence on the proportion of cells attaching to the glass. When the material in the first supernatant was recentrifuged at 2,000 x g for 30 min and added to the cells precipitated in the first centrifugation, the longevity of these cells was increased by several cell divisions. Cells which were not centrifuged but added directly from the cell suspension in trypsin to the new culture grew at a slightly slower rate than the centrifuged cells and became senescent at an earlier time. However, the noncentrifuged cells adsorbed to glass better than those centrifuged.

Cell Adhesion↗
PubMed1970

Standardization of human diploid cell cultivation.

Human embryonic diploid lung fibroblasts grown in Eagle's medium were exposed continually to a variety of environmental conditions over a large number of passages to observe how these conditions affected the growth and longevity of these cells in vitro. The cells grew well at temperatures between 34 and 37 C and some cells could be adapted to grow at 40 C. Very limited growth occurred at 30 to 31 C; however, confluent monolayers of cells could be maintained for months at 30 C and still give rise to actively growing cultures. Increasing the amino acid concentration in Eagle's medium or the calf serum concentration above 10% had no effect on the growth rate or longevity. One per cent calf serum could not support prolonged active growth. Trypsin concentrations between 1 and 0.1% and crystalline trypsin at 50 mug/ml showed no influence on cell growth. Ethylenediaminetetraacetic acid treatment and scraping, however, destroyed many of the cells, and the survivors grew poorly. The clonal morphology varied with age. Young cells frequently gave rise to densely packed clones, whereas older cells gave rise to clones with widely scattered cells. The cloning efficiency was high when the cells were young but decreased rapidly with successive passage. It was relatively constant from the 7th to 20th passage at about 15%.

Amino Acids↗