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Query: UMLS:C0392674 (exhaustion)
 13,658 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dependence of growth formation of citric acids (citrate: isocitrate = 1:1) on oxygen parital pressure of an alkane utilising yeast Saccharomycopsis lipolytica was investigated. During growth oxygen corresponds to a Michaelis-Menten-kinetics (Ks = 2.0 . 10(-5) M). The respiration quotient RQ for a dissolved oxygen concentration in the range of 10-100% (air saturation) is 0.46 +/- +/- 0.04. The phase of product formation is characterized by 3 sections. Immediately after N-exhaustion the cell activities are the highest. They decline during the first 30 hours of production. Besides the production of reserve material in this first section the highest production rate for citrate and isocitrate is observed. The rate of citric acid production depends on the oxygen partial pressure and is governed by Michaelis-Menten-kinetics. The specific production rate and the rate of oxygen consumption correspond to KS-values of 4.0 X 10(-5) and 3.3 X 10(-5) M, respectively. The RQ-value declines to a constant value of 0.23 +/- 0.02 and is not influenced by oxygen partial pressures in the range of 10--100% (related to air saturation). During the second section cell activities remain nearly constant for about 100 h. Due to this constancy the following equation could be derived: 14 O2 + C15H32 leads to 2 C6H8O7 + 3 CO2 + 8 H2O. In the third section the cell activities decline again.
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PMID:[Effect of oxygen partial pressure on citric acid synthesis in Saccharomycopsis lipolytica using n-alkanes]. 733 71

At the first International Congress of Physiologists in Basel, Switzerland, the Italian physiologist Angelo Mosso (1846-1910) discussed his findings on muscular fatigue while demonstrating the functioning of an ergograph (work recorder). One hundred sixteen years later, Mosso's career, scientific accomplishments, and legacy in the study of muscular fatigue were commemorated at the 2005 International Congress of Physiological Sciences. After receiving his degree in Medicine and Surgery from Turin, Italy, in 1870, Mosso was able to study and interact with renowned physiologists as Wilhelm Ludwig, Du Bois-Reymond, Hugo Kronecker, and Etienne Marey. By 1879, he was Professor of Physiology at the University in Turin, where he conducted research pertaining to blood circulation, respiration, physical education, high-altitude physiology, and muscular fatigue. Using tracings from the ergograph (concentric contractions of the flexor muscles of the middle finger that were volitionally or electrically stimulated), he was able to characterize muscle fatigue and to associate its occurrence with central or peripheral influences. He demonstrated that exercise would increase muscular strength and endurance while prolonging the occurrence of fatigue, which he postulated was a chemical process that involved the production of toxic substances such as carbonic acid. The phenomenon of contracture was described, and his collective studies led to the formulation of laws pertaining to exhaustion and to the 1891 publication of La Fatica (Fatigue). Besides La Fatica, Mosso will be remembered as a scientist with a love for physiology, a concern for the social welfare of his countrymen, and as one who sought to integrate physiological, philosophical, and psychological concepts in his experimental studies.
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PMID:Angelo Mosso and muscular fatigue: 116 years after the first Congress of Physiologists: IUPS commemoration. 1670 33