Growth and metabolism of L cells in a chemically defined medium in a controlled environment culture system. I. Effects of O2 tension on L-cell cultures

Comparison of the optimal culture conditions for cell growth and tissue plasminogen activator production by human embryo lung cells on microcarriers

Optimization of culture conditions such as the dissolved O2 (DO) concentration, temperature and pH was attempted regarding both cell growth and the production of tissue plasminogen activator (TPA) in a microcarrier cell culture of human embryo lung cells. The growth rate was suppressed at a DO concentration below 30% saturation. From the pH range 7.2-7.6, both the specific growth rate and maximal cell concentration decreased. At a lower temperature than 37 degrees C, although both the specific growth rate and the maximal cell concentration decreased, the cell concentration was maintained for a longer time during the production period, high TPA productivity being maintained. As the optimal conditions for culture growth, a DO concentration of 30% saturation or over, temperature of 37 degrees C and pH of 7.4 are recommended. However, for TPA production after cell culture growth, the DO concentration should be in the range 20-30% O2 saturation, and the temperature and pH should be lowered to 33 degrees C and 6.8, respectively.

Poly(adenosine dephosphate ribose) metabolism and regulation of myocardial cell growth by oxygen

Control of the rate of cardiac cell division by oxygen occurs most probably by altering the redox state of a control substance, e.g. NAD(+)right harpoon over left harpoonNADH. NAD(+) (and not NADH) forms poly(ADP-ribose), an inhibitor of DNA synthesis, in a reaction catalysed by poly(ADP-ribose) polymerase. Lower partial pressure of oxygen, which increases the rate of division, would shift NAD(+)-->NADH, decrease poly(ADP-ribose) synthesis, and increase DNA synthesis. Chick-embryo heart cells grown in culture in 20% O(2) (in which they divide more slowly than in 5% O(2)) did exhibit greater poly(ADP-ribose) polymerase activity (+83%, P<0.001) than when grown in 5% O(2). Reaction product was identified as poly(ADP-ribose) by its insensitivity to deoxyribonuclease, ribonuclease, NAD glycohydrolase, Pronase, trypsin and micrococcal nuclease, and by its complete digestion with snake-venom phosphodiesterase to phosphoribosyl-AMP and AMP. Isolation of these digestion products by Dowex 1 (formate form) column chromatography and paper chromatography allowed calculation of average poly(ADP-ribose) chain length, which was 15-26% greater in 20% than in 5% O(2). Thus in 20% O(2) the increase in poly(ADP-ribose) formation results from chain elongation. Formation of new chains also occurs, probably to an even greater degree than chain elongation. Additionally, poly(ADP-ribose) polymerase has very different K(m) and V(max.) values and pH optima in 20% and 5% O(2). These data suggest that poly(ADP-ribose) metabolism participates in the regulation of heart-cell division by O(2), probably by several different mechanisms.

System for studying uninfected and virus-infected cell cultures in hyperbaric chambers

Equipment and techniques previously used to investigate the effect of hyperbaric gases on bacteria were modified to permit comparable investigations with uninfected and virus-infected tissue cell cultures. This report describes the modified equipment and related methodology. Use of the system is illustrated with findings on the effect of oxygen-helium mixtures at 68 atm on cell physiology and virus growth in two cell types. Our results suggested that, under those experimental conditions, several synthetic processes in chick fibroblast monolayers are inhibited but that Sindbis virus growth in the cells is increased. Growth of Japanese encephalitis virus in porcine kidney cells was found to be unaffected by oxygen-helium gas at partial pressures of oxygen between 0 and 700 mm Hg, but morphological alterations in the cells occurred at low and high pO(2) levels.