Oxygen Tensions

It may seem obvious that cells from warm-blooded animals should be maintained at 37 °C but the importance of so doing is nicely illustrated by 

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The presence of hemoglohin-S (Hb-S) ia red blood cells leads to the formation of Hquid crystalline aggregates iaside the ceU under conditions of low oxygen tension (43,44). The morbid aggregates ultimately arrange themselves iato a gel-like material composed of long fibers that extend the entire length of the ceU and distort its usual shape. 

Facultative The ability to live under more than one set of conditions, usually in relation to oxygen tension prevailing in the medium, that is aerobic or anaerobic (e.g., facultative anerobes). 

The control of glucose oxidase production is still not fully eluddated, nor is the role of gluconic add in cells. However, elevated levels of glucose oxidase are found in conditions of high glucose concentrations and above normal oxygen tension. 

Biomass formation and transamination activity within the cells develop in a similar manner. Growth usually continues until limited by the availability of dissolved oxygen tension (DOT). After 10-15 hours a dry weight biomass concentration of 10 g V is normally reached. 

Explain clearly why and how the response of glucose oxidase-based enzyme electrodes is influenced by fluctuations in the oxygen tension. 

Two important examples of reductive metabolism of xenobiotics are the reductive dehalogenation of organohalogen compounds, and the reduction of nitroaromatic compounds. Examples of each are shown in Figure 2.13. Both types of reaction can take place in hepatic microsomal preparations at low oxygen tensions. Cytochrome P450 can catalyze both types of reduction. If a substrate is bound to P450 in the... 

Neufeld, 0. Smith, J. R. and Goldman, S. L. Arterial Oxygen Tension in Relation to Age in Hospital Patients. 

Gordh, T. Linderholm, H. and Norlander, 0. Pulmonary Function in Relation to Anaesthesia and Surgery Evaluated by Analysis of Oxygen Tension of Arterial Blood. Acta Anaesth. Scand. (1958), 2 15-26. 

Tetanus occurs when Cl. tetani, ubiquitous in the soil and faeces, contaminates wounds, especially deep puncture-type lesions. These might be minor traumas such as a splinter, or major ones such as battle injury. At these sites, tissue necrosis and possibly microbial growth reduce the oxygen tension to allow this anaerobe to multiply. Its growth is accompanied by the production of a highly potent toxin which passes up peripheral nerves and diSuses locally within the central nervous system. It acts like strychnine by affecting normal function at the synapses. Since the motor nerves of the brain stem are the shortest, the cranial nerves are the first affected, with twitches of the eyes and spasms of the jaw (lockjaw). 

The release of iron from intracellular ferritin stores is thought to involve the reduction of Fe to Fe " (Funk et al., 1985) and one would expect this reduction to be fecilitated by the low oxygen tension, increased levels of reducing species and the low pH shown by nuclear magnetic resonance (NM to be as low as 6.9 after only 6 h of cold storage (Fuller et al., 1988). Exogenous redox-active quinones such as adriamycin have been shown to catalyse lipid peroxidation in the presence of ferritin under hypoxic conditions (Vile and Winterbourne, 1988), and lipid peroxidation is stimulated in micro-somes in the presence of purified ferritin and flavin... 

Richman, A.L., Su, E.Y. and Ho, G. (1981). Reciprocal relationship of synovial fluid volume and oxygen tension. Arthritis Rheum. 24, 701-705. 

Unsworth, J., Outhwaithe, J., Blake, D.R., Morris, C.J., Freeman, J. and Lunec, J. (1988). Dynamic studies of the relationship between intra-articular pressure, synovial fluid oxygen tension, and lipid peroxidation in the inflamed knee an example of reperfusion injury. Ann. Clin. Biochem. 25, 8S-11S. 

It is known that the endothelial cells lining the capillary bed are markedly damaged during hyperoxic exposure. However, it is not at present known whether this damage is due to free-radical-induced injury of the endothelial cells or whether endothelial cells are simply responding to the diminished blood flow produced by the severe vasoconstriction. The theoretical basis for free-radical involvement is sound and it has been proposed that low oxygen tensions (hypoxia) followed by periods of reoxygenation are the most likely explanation for the disorder (Kelly, 1993). 

Flower, R.W. and Patz, A. (1971). Oxygen studies in retrolental fibroplasia. IX. The effects of elevated arterial oxygen tension on retinal vascular dynamics in the kitten. Arch. Ophthamol. 85, 197-208. 

Phagocyte-derived ROMs have been implicated in the pathogenesis of a number of pulmonary diseases, including emphysema, acute respiratory distress syndrome, and various environmental diseases such as asbestos-related fibrosis and cancer (Mossman and Marsh, 1985). The relatively high oxygen tension in pulmonary tissue renders the lung prone to oxidative stress (Edwards and Lloyd, 1988). 

MRSE MethiciUin-resistant Staphylococcus epidermitis Pao2 Arterial oxygen tension... 

Chen G and Djuric Z. 2001. Carotenoids are degraded by free radicals but do not affect lipid peroxidation in unilamellar liposomes under different oxygen tensions. FEBS Letters 505(1) 151-154. colorMaker, Inc. Anaheim, CA, http //www.colormaker.com/CM/AboutNC/annatto.asp. 

Figure 7.4 Summary of some of the wide array of afferent and efferent connections of midbrain dopaminergic neurons (SN/A9, RRF/A8, and VTA/A10 in center of figure). This emphasizes their potential involvement in coordination of seemingly disparate behaviors inclusive of the sleep-wake state of the organism. Abbreviations BP, blood pressure BST, bed nucleus of the stria terminalis CEA, central nucleus of the amygdala MEA, midbrain extrapyramidal area NTS, nucleus of the solitary tract O2, oxygen tension PPN, pedunculopontine tegmental nucleus RRF, retrorubral field SN, substantia nigra VTA, ventral tegmental area.

The parasitic nematode, Ascaris suum, undergoes a number of well-characterized metabolic transitions during its development (Table 14.1), but little is known about the regulation of these events (Barrett, 1976 Komuniecki and Komuniecki, 1995). Adults reside in the porcine small intestine and fertilization takes place under low oxygen tensions. The unembryonated egg that leaves the host is metabolically quiescent, has no detectable cytochrome oxidase activity or ubiquinone and appears to be transcriptionally inactive (Cleavinger et al., 1989 Takamiya et al., 1993). Embryonation requires oxygen and after about 48-72 h is accompanied by... 

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