Research on Oxygen Toxicity at the Cellular Level PDF Download
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Author: Willis H. Riesen
Publisher:
ISBN:
Category :
Languages : en
Pages : 88
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Book Description
Author: Willis H. Riesen
Publisher:
ISBN:
Category :
Languages : en
Pages : 88
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Book Description
Author: Olen R. Brown
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Book Description
Studies using vitamins, precursors, and intermediates with analysis of carbohydrate, amino acid, lipid, protein, RNA and DNA synthesis and of enzyme activities in suspected pathways support the following events during oxygen intoxication of Escherichia coli. Biosynthesis of several amino acids are inhibited. Within less than 5 minutes valine is limiting for protein synthesis (subsequently 9 other amino acids become limiting). The resultant unloaded tRNA's stimulate the 'stringent response' (production of the powerful inhibitor guanosine tetraphosphate) which completely stops biosynthesis. Some of these sites (including quinolinate phosphoribosyl transferase, required for NAD synthesis) should be relevant to man. The data suggest that the vitamins thiamin pyrophosphate and niacin should be tested as potential protective agents against the toxicity in man of oxygen and of chemicals which produce cellular oxidative stress.
Author: Willis H. Riesen
Publisher:
ISBN:
Category : Oxygen
Languages : en
Pages : 84
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Book Description
The use of pure oxygen atmospheres at reduced pressure in manned spacecraft has stimulated new research interest. Exposure of humans to pure oxygen at total pressures of 5 to 7 psia for up to 30 days has generally produced only subjective and occasional symptomatic distress. Nevertheless, studies with animals have clearly documented toxicity if the exposure to pure oxygen is at higher total pressures. The selection of suitable oxygen atmospheres for manned space flight and the development of protective measures against toxic manifestations will be considerably facilitated by a clearer understanding of the toxic syndrome. Rats, dogs, and monkeys were exposed to pure (98.5%) oxygen at 1 atm and 1/3 atm in a closed, recirculating chamber and in a nonrecirculating chamber. Rats exposed to a pressure of 1 atm showed significant reduction in efficiency of liver mitochondrial oxidative phosphorylation. Weight loss accompanied this change. Insignificant changes were found in liver or lung mitochondrial oxygen consumption; liver or lung NAD, NADH, or NAD/NADH; and arterial blood lactate and pyruvate, and lactate/pyruvate ratio. A composite index of oxygen toxicity was derived from a multivariant data analysis. Exposure of rats to pure oxygen at 1/3 atm showed slight elevation in P/O ratio in 7 days. The ratio returned to normal in 2 weeks and remained so for 8 months. No significant weight changes were observed. Only preliminary experiments with the dogs and monkeys were conducted, therefore no conclusions can as yet be made. There is an indication that monkeys are more resistant to oxygen toxicity at 1 atm than rats.
Author: D. Danon
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
Author: Olen R. Brown
Publisher:
ISBN:
Category : Oxygen
Languages : en
Pages : 36
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Book Description
The most significant finding has been the demonstration that even five minute exposures to oxygen at four atmospheres produces a severe, but reversible (upon removal from hyperoxia), inhibition of active transport of glucose, using Escherichia coli as a model cell system. Experimental data is so far consistent with the current operating theory that a site in membrane transport is the primary target in acute oxygen toxicity at the cell level. The inhibition of transport apparently is not due to lack of energy (ATP) for transport, nor to oxidative destruction of the membrane, but the true mechanism is unknown. (Modified author abstract).
Author: Roland N. Pittman
Publisher: Biota Publishing
ISBN: 1615047212
Category : Medical
Languages : en
Pages : 117
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Book Description
This presentation describes various aspects of the regulation of tissue oxygenation, including the roles of the circulatory system, respiratory system, and blood, the carrier of oxygen within these components of the cardiorespiratory system. The respiratory system takes oxygen from the atmosphere and transports it by diffusion from the air in the alveoli to the blood flowing through the pulmonary capillaries. The cardiovascular system then moves the oxygenated blood from the heart to the microcirculation of the various organs by convection, where oxygen is released from hemoglobin in the red blood cells and moves to the parenchymal cells of each tissue by diffusion. Oxygen that has diffused into cells is then utilized in the mitochondria to produce adenosine triphosphate (ATP), the energy currency of all cells. The mitochondria are able to produce ATP until the oxygen tension or PO2 on the cell surface falls to a critical level of about 4–5 mm Hg. Thus, in order to meet the energetic needs of cells, it is important to maintain a continuous supply of oxygen to the mitochondria at or above the critical PO2 . In order to accomplish this desired outcome, the cardiorespiratory system, including the blood, must be capable of regulation to ensure survival of all tissues under a wide range of circumstances. The purpose of this presentation is to provide basic information about the operation and regulation of the cardiovascular and respiratory systems, as well as the properties of the blood and parenchymal cells, so that a fundamental understanding of the regulation of tissue oxygenation is achieved.
Author: O. R. Brown
Publisher:
ISBN:
Category : Oxygen
Languages : en
Pages : 24
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Book Description
Oxygen at elevated pressures is toxic for life forms from microbes to man. Growth is inhibited in Escherichia coli and results primarily from poisoning of specific enzymes in the following biosynthetic pathways: branched-chain and aromatic amino acids, NAD-niacin, phosphoribosylpyrosphosphate (PRPP) and reverse glycolysis. Inhibition of amino acid biosynthesis indirectly stops protein synthesis and induces 'stringency' (production of pp-guainine-pp, a powerful inhibitor of metabolic processes) which accounts for inhibition in metabolic processes where there is no observed enzymatic poisoning. Inhibitions in the PRPP, NAD-niacin, and reverse glycolysis pathways are significant to bacterial (and perhaps to human) oxygen toxicity where products of the pathways protect. (Summary, p. 2-3)
Author: Tom S. Neuman
Publisher: Elsevier Health Sciences
ISBN: 1416034064
Category : Medical
Languages : en
Pages : 637
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Book Description
Written by internationally recognized leaders in hyperbaric oxygen therapy (HBOT) research and practice, this exciting new book provides evidence-based, practical, useful information for anyone involved in HBOT. It outlines the physiologic principles that constitute the basis for understanding the clinical implications for treatment and describes recent advances and current research, along with new approaches to therapy. This book is an essential tool for anyone who cares for patients with difficult-to-heal wounds, wounds from radiation therapy, carbon monoxide poisoning, and more. Provides comprehensive coverage of pathophysiology and clinically relevant information so you can master the specialty. Covers the relevance of HBOT in caring for diverse populations including critical care patients, infants and pediatric patients, and divers. Features a section on the technical aspects of HBOT to provide insight into the technology and physics regarding HBO chambers. Presents evidence to support the effectiveness of HBOT as well as the possible side effects. Describes situations where HBOT would be effective through indication-specific chapters on chronic wounds, radiation and crush injuries, decompression sickness, and more.
Author: Jack D. Hackney
Publisher:
ISBN:
Category : Cell division
Languages : en
Pages : 181
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Book Description
Author: Giuseppe Buonocore
Publisher: Springer
ISBN: 9783319294872
Category : Medical
Languages : en
Pages : 0
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Book Description
This landmark book, a reference work now in its second edition, provides healthcare practitioners in neonatology with an up-to-date, comprehensive source of readily accessible practical advice that will assist in the expert management of patients and their diverse illnesses. Leading experts in their fields discuss the underlying causes and mechanisms and all aspects of the treatment of the full range of neonatal diseases and abnormalities, citing the evidence base whenever appropriate. In addition, detailed information is provided on epidemiology and fetal medicine; therapeutic issues such as the organization of care, transport services, and home care after discharge; legal issues; nutrition; and the consequences of medication use during pregnancy, maternal drug abuse and smoking, and maternal diabetes. The inclusion of summaries, tables, and carefully selected guidelines and recommendations will supply practitioners with quick references and instant solutions during daily practice. The book will be a superb resource for all involved in the care of newborn babies, including neonatologists, pediatricians, pediatric surgeons, anesthesiologists, midwives, and nursing staff. It is published within the SpringerReference program, which delivers access to living editions constantly updated through a dynamic peer-review publishing process.
