Oxygen supply, enhanced

Injuries and fatalities from asphyxiation are often associated with personnel entry into inerted equipment or enclosures. Guidance on safe procedures for confined space access are provided by OSHA (OSHA, 29 CFR 1910.146, Confined Space Entry Standard, 2000), the American National Standards Institute (ANSI, Z117.1, Safety Requirements for Confined Spaces, 2003), Hodson (Hodson, Safe Entry into Confined Spaces, Handbook of Chemical Health and Safety, American Chemical Society, 2001), and BP (BP, Hazards of Nitrogen and Catalyst Handling, 2003). OSHA has established 19.5 vol % as the minimum safe oxygen concentration for confined space entry without supplemental oxygen supply (see Table 23-18). Note that OSHA imposes a safe upper limit on 02 concentration of 23.5 vol % to protect against the enhanced flammability hazards associated with 02-enriched atmospheres. 

Nifedipin causes relaxation of smooth musculature, dilation of coronary and peripheral arteries, and reduction of peripheral resistance and arterial blood pressure, and enhances oxygen supply to the heart. 

In 1993, the cost of using hydrogen peroxide to enhance biodegradation was been reported to be as high as 2.81 to 4.63/kg of oxygen supplied (D13000N, p. 524 D13003Q, pp. 154-158). 

G, whereas cell-free extracts acting on penicillin N had been stimulated by ATP [19], Increasing cell mass enhanced the concentration of DAOG formed from penicillin G, the optimum concentration being 19 mg/ml. Higher cell concentrations inhibited the reaction, probably because oxygen supply was limiting under such conditions. In the studies of Cho et al. [14], the buffer used for bioconversion was 50 mM Tris-HCl [Tris = tris(hydroxymethyl)aminomethane] at pH 7.4. It was later found that 50 mM MOPS buffer or 50 mM HEPES [N-(2-hydroxyethyl) piperazine-N -(2-ethanesulfonic acid] buffer at pH 6.5 improved activity [41]. 

Cell death induced by AmB in the medullary thick ascending limb is prevented by ouabain [108]. A reasonable explanation for this observation is that ouabain, by inhibiting transport, decreases the oxygen demand of an area of the nephron that already has a hmited oxygen supply. This is consistent with the observation that AmB exhibits preferential damage to the medullary ray, an area that is vulnerable to hypoxic injury [48]. It is also conceivable that AmB-induced renal vasoconstriction and ischemia to this section of the nephron enhances cell death produced by a direct toxic action. Thus, any maneuver that improves renal perfusion, or decreases oxygen demand, would be expected to be protective. This may explain the salutary effect of salt loading, theophylline, calcium channel... 

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