Regulation by oxygen

Larsen, K. Jochimsen, B.U. (1986). Expression of nodule-specific uricase of soybean callus tissue is regulated by oxygen. The EM BO Journal 5, 15-19. 

Kannenberg, E.L., Brewin, N.J. Expression of a cell surface antigen from Rhizobium legumi-nosarum 3841 is regulated by oxygen and pH. J Bacteriol 171 (1989) 4543 1548. 

Dweik, R., Laskowski, D, Abu-Soud, HM, Kaneko, F. Hutte, R, Stuehr. DJ and Erzurum, SC. 1998. Nitric oxide synthesis in the lung. Regulation by oxygen through a kinetic mechanism. J. Clin. Invest. 101 660-666. 

There are a multitude of activators of NF-kB, such as viral infections, bacterial infections, radiation, interleukin (IL)-l, and tumor necrosis factor (TNF). Most of the activators of NF-kB can be blocked with the use of antioxidants (Schulze et al., 1997). Other transcription factors, such as AP-1 (Xanthoudakis et al., 1994), MAF, and NRL (Kerppola and Curran, 1994), and NF-IL6 (Hsu et al., 1994) are regulated by oxygen-dependent mechanisms that cause redox cycling of cysteinyl residues. 

Lois AF, Weinstein M, Ditta GS, Helinski DR. Autophosphorylation and phosphatase activities of the oxygen-sensing protein FixL of Rhizobium meliloti are coordinately regulated by oxygen. J Biol Chem 1993 268 4370-4375. 

However, a weakness of these experimental approaehes is that they eannot clearly define the point of moleeular interaetion with the HIF system. For example, redox-active agents that are proposed to affeet the oxygen-sensing meehanism might do so directly, or very indireetly in a way that does not mimie physiological regulation by oxygen. 

The dopamine is then concentrated in storage vesicles via an ATP-dependent process. Here the rate-limiting step appears not to be precursor uptake, under normal conditions, but tyrosine hydroxylase activity. This is regulated by protein phosphorylation and by de novo enzyme synthesis. The enzyme requites oxygen, ferrous iron, and tetrahydrobiopterin (BH. The enzymatic conversion of the precursor to the active agent and its subsequent storage in a vesicle are energy-dependent processes. 

Internal pressure may be caused by several potential sources. One source is the vapor pressure of the Hquid itself. AH Hquids exert a characteristic vapor pressure which varies with temperature. As the temperature iacreases, the vapor pressure iacreases. Liquids that have a vapor pressure equal to atmospheric pressure boH. Another source of internal pressure is the presence of an iaert gas blanketing system. Inert gas blankets are used to pressuri2e the vapor space of a tank to perform speciali2ed functions, such as to keep oxygen out of reactive Hquids. The internal pressure is regulated by PV valves or regulators. 

The amount of oxygen in the combustion gas is regulated by controlling the ratio of air to fuel in the primary section. As previously mentioned, the ideal volumetric ratio of air to methane is 10 1. If less than 10 volumes of air are used with one volume of methane, the combustion gas will contain carbon monoxide. The reaction is as follows ... 

The flow rates of the two gases are regulated by flow meters inserted in parallel between the gas-mixing chamber and the chlorine and oxygen tanks. Appropriate flow rates for chlorine and oxygen are 80-100 and 40-50 ml. per minute, respectively. The checkers purchased gas flow meters from Arthur H. Thomas Company, Philadelphia, Pennsylvania. 

Entry into confined spaces where there is likely to be a danger from toxic or flammable gases, or oxygen deficiency or enrichment (Table 11.12). Such work requires well rehearsed procedures regulated by a permit. Figure 11.3 identifies the procedures for entry into confined spaces and Table 11.13 lists associated safety requirements with a specimen permit (Figure 11.4). 

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