Oxygen lack

Aviation has stimulated interest in the effects of oxygen lack (anoxia) on human beings and has brought the realization that some individuals are affected much more readily than others. The literature on the subject is full of allusions to the ever-present variation, but it is difficult to find definitive data. In connection with training of Air Force... 

Oxygen is a substrate for enzymes located in every cell of the body and, since the corresponding participating enzymes are not of the same efficiency in different individuals, variability in the effects of oxygen lack should be expected. As Nims says "It is obvious that anoxia affects many functions and that these are not affected in the same degree from one individual to another. "21... 

Hochachka PW, Buck LT, Doll CJ et al (1996) Unifying theory of hypoxia tolerance molecular/metabolic defense and rescue mechanisms for surviving oxygen lack. Proc Natl Acad Sci USA 93 9493-9498... 

Increase in the input of the organic matter and nutrients into the Black Sea causes increase of total phytoplankton biomass. In summer due to formation of the temperature, salinity and density stratification and algal blooms, decay of dead phytoplankton leads, in turn, to the oxygen lack and near-bottom hypoxia [9]. These processes have to consider as the consequence of anthropogenic eutrophication of the sea [9]. 

Traditionally, biologists views of cell-level responses to 02 limitation are formalized in the concept of the Pasteur effect as ATP generation by oxidative phosphorylation begins to fall off due to oxygen lack, the energetic deficit... 

In a first attempt at a synthesis of information in this research (Hochachka, 1986), a channel arrest component of a hypoxia tolerance theory postulated (i) that hypoxia tolerant cells would have an inherent low permeability (either low channel densities or low channel activities) and (ii) that they would sustain a further suppression of membrane permeability to ions when exposed to oxygen lack (further channel arrest by either suppression of channel densities or channel activities). Turtle liver cells display both of these characteristics (especially when compared to mammalian homologs) thus they clearly fit the classical definition of metabolic and channel arrest as two telling signatures of hypoxia tolerance. 

Comparable studies in turtle hepatocytes found (Land and Hochachka, 1995) quite a complex situation. Under conditions of prolonged oxygen lack, the expression of four proteins in turtle hepatocytes was preferentially up-regulated, while the expression of five proteins was preferentially down-regulated. The hypoxia dependence of this system appeared similar to... 

From these studies, it is now possible to construct a generalized framework or working hypothesis for how hypoxia-tolerant cells respond to oxygen lack (figure 3.18). During the very early acute phases, a poorly understood hypoxia-sensing and signal transduction system orchestrates a series of molecular hypoxia defense processes, which include ... 

Protonation of the aldehyde carbonyl carbon gives cation 4-61. This is a very unstable intermediate. It is not stabilized by resonance, and the positive oxygen lacks an octet of electrons. Notice that the double bond and the positive ojqrgen are not conjugated because they are separated by an -hybridized carbon. 

Victims of heart attacks often die within hours of the onset of the infarction. This is due to ventricular fibrillation, a deadly event in which the heart muscle goes crazy and beats rapidly and chaotically. This is the heart s response to oxygen-lack called hypoxia. If this dangerous "runaway heart" condition can be controlled, then the patient has an excellent opportunity to survive. 

Oxygen lack not only stops the machine hut wrecks the machinery. 

The organisms that form methane live in anaerobic (oxygen-lacking) conditions. Those significant for global methane are found in the digestive systems of ruminants (cattle, sheep, etc.) and termites and in organic carbon-rich aquatic systems (shallow freshwater sediments and rice paddies). 

Krasney JA (1967). Efficient components of the cardioaccelerator responses to oxygen lack and cyanide. Am J Physiol, 213, 1475-1479. 

Water, HjO. Water is composed of molecules that contain two atoms of hydrogen (subscript 2) and one atom of oxygen (lack of a subscript means one atom). 

Potassium permanganate 5 HjS from oxygen-lacking gases... 

Animal respiration is usually less sensitive to oxygen lack than it is to the presence of carbon... 

Shepard, M. P. (1955). Resistance and tolerance of young speckled trout (Salvelinus fontinalis) to oxygen lack, with special reference to low oxygen acclimation, /. Fish. Res. Bd. Canada 12, 387-444. 

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