Scheduling personnel with an artificial intelligence program.
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Biomedical subjects
T Hefley
Publications and source records attributed to T Hefley.
Enzymatic isolation of cells from bone: cytotoxic enzymes of bacterial collagenase.
The enzymatic isolation of cells from fetal rat calvaria is most effectively achieved with crude Clostridium histolyticum collagenase. However, this bacterial collagenase damages the cells during the digestion of the tissue. We have used cell density, as measured by isopycnic centrifugation on polysucrose gradients, as an indicator of cell damage. There are at least two enzymes in crude bacterial collagenase capable of damaging the cells in this tissue. One of these is clostripain that has been well characterized. The other cytotoxic enzyme is uncharacterized, and its effects are not evident until the clostripain activity has been inhibited by alpha-tosyl-lysyl chloromethane. The apparent activity of this second enzyme can be inhibited by withholding magnesium from the digestion medium and by increasing the potassium concentration of the digestion medium.
Animals↗
Potassium, sodium, and the intracellular fluid space of cells from bone.
Cells enzymatically dispersed from fetal rat calvaria were analyzed for sodium and potassium content and intracellular fluid space (ICF). Even when obtained in comparatively high yield, the cells are damaged by the isolation procedure as evidenced by high sodium and low potassium content immediately after isolation. During a post-incubation period potassium is accumulated and sodium extruded to steady-state levels. Although electrolyte content of cells after recovery did not vary as a function of cell yield, ICF was increased in cells obtained in lower yield, suggesting cell swelling as a result of membrane damage. The weighted mean values obtained for the best cell preparations were 117 mM K+ and 27 mM Na+. Based on DNA assay of isolated cells and the whole tissue, 20- to 21-day calvaria were found to have an average of 8.1 x 10(6) cells/calvarium. Combining cell data with analysis of total tissue sodium, potassium, and water, it was concluded that the tissue extracellular sodium is in equilibrium with blood but that the potassium concentraiton is approximately 5-fold higher than blood levels.
Animals↗