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Biomedical subjects

W O Fenn

Publications and source records attributed to W O Fenn.

At least 19 recordsLinked to original sources
PubMed1971

Pressure sensitivity of streptococcal growth in relation to catabolism.

The sensitivity of Streptococcus faecalis growth to hydrostatic pressures ranging up to 550 atm was found to depend on the source of adenosine triphosphate for growth. Barotolerance of cultures growing in a complex medium with ribose as major catabolite appeared to be determined primarily by the pressure sensitivity of ribose-degrading enzymes. Apparent activation volumes for growth were nearly identical to those for lactate production from ribose, and yield coefficients per mole of ribose degraded were relatively independent of pressure. In contrast, cultures with glucose as main catabolite were less sensitive to pressure; glycolysis was less severely restricted under high pressure than was growth, and yield coefficients declined with pressure, especially above 400 atm. Thus, two distinct types of barotolerance could be defined-one dominated by catabolic reactions and one dominated by noncatabolic reactions. The results of experiments with a series of other catabolites further supported the view that catabolic reactions can determine streptococcal barotolerance. We also found that growing, glucose-degrading cultures increased in volume under pressure in the same manner that they do at 1 atm. Thus, it appeared that the bacterium has no alternative means of carrying out glycolysis under pressure without dilatation. Also, the observation that cultures grown under pressure did not contain abnormally large or morphologically deformed cells suggested that pressure did not inhibit cell division more than cell growth.

Adenosine Triphosphate↗
PubMed1968

Growth of Streptococcus faecalis under high hydrostatic pressure and high partial pressures of inert gases.

Growth of Streptococcus faecalis in a complex medium was inhibited by xenon, nitrous oxide, argon, and nitrogen at gas pressures of 41 atm or less. The order of inhibitory potency was: xenon and nitrous oxide > argon > nitrogen. Helium appeared to be impotent. Oxygen also inhibited streptococcal growth and it acted synergistically with narcotic gases. Growth was slowed somewhat by 41 atm hydrostatic pressure in the absence of narcotic gases, but the gas effects were greater than those due to pressure. In relation to the sensitivity of this bacterium to pressure, we found that the volume of cultures increased during growth in a volumeter or dilatometer, and that this dilatation was due mainly to glycolysis. A volume increase of 20.3 +/- 3.6 ml/mole of lactic acid produced was measured, and this value was close to one of 24 ml/mole lactic acid given for muscle glycolysis, and interestingly, close to the theoretic volume increase of activation calculated from the depression of growth rate by pressure.

Argon↗
PubMed1967

Oxygen poisoning in Drosophila.

Fruit flies live longer at the partial pressure of oxygen found in air than at either larger or smaller partial pressures. Flies exposed to 1 atm of oxygen for 8 hr every day do not recover completely in the remaining 16 hr. In general, intermittent exposures to 1 atm of oxygen are better tolerated than continuous exposure to the same average oxygen concentration per day, but exposures to higher pressures of 2-5 atm of oxygen for as little as a half hour every two days markedly shorten the life-span. Older flies consume more oxygen per minute and are more sensitive to oxygen poisoning than young flies, and the rate of dying in 6 atm of O(2), or the reciprocal of the survival time, is a linear function of the age. The oxygen pressure-time curve can be well expressed by the general empirical equation (P(OO2))(2) x time = 120 where P is in atmosphere and survival time in hours. The progress of oxygen poisoning appears to be linear with time rather than exponential.

Aging↗
PubMed1966

Interactions of oxygen at high pressure and radiation in Drosophila.

Oxygen at high pressure (OHP) and X-irradiation can interact in the fruit fly Drosophila melanogaster to potentiate toxic actions characteristic of one agent alone. 1000 kvp X-irradiation in doses of 30, 60, and 75 kr accelerated the acute immobilization of young male Drosophila by oxygen at 7.8 atm, up to rates twice that observed with such oxygen pressure alone. X-irradiation alone in these dosages did not acutely immobilize the Drosophila. X-irradiation during exposure to 7.8 atm pO(2) was more effective and consistent in producing this potentiation than was X-irradiation that preceded exposure to OHP. Acute OHP toxicity in young female Drosophila was not potentiated by 75 kr of X-irradiation. On the other hand, shortening of the life span of young male Drosophila by the above doses of X-irradiation was augmented significantly by a concurrent 40 min exposure to OHP (which alone did not significantly decrease life span). This shows, for the first time, that oxygen can affect not only the acute effects of radiation, but also the residual irreversible effects indicated by the life span shortening.

Animals↗