Prolonged incubation

Experiments examined a chlorocatechol-contaminated sediment, and interstitial water prepared from it. These showed that the concentrations of total 3,4,5-tri- and tetrachloro-catechols (i.e., including the fraction that is released only after alkaline extraction) were apparently unaltered during prolonged incubation even after addition of cnltnres with established dechlorinating capability for the soluble chlorocatechols (Allard et al. 1994). 

In experiments where relatively small volumes of sediment suspensions are employed, autoclaving may significantly alter the structure of the sediment as well as introducing possibly severe analytical difficulties. In such circumstances, there are few alternatives to incubation in the presence of toxic agents such as NaNj, which has been used at a concentration of 2g/L. There remains, of course, the possibility that azide-resistant strains could emerge during prolonged incubation, and the possible occurrence of reactions between the substrate and azide must also be taken into consideration. 

Embryos of the common tem (Sterna hirundo) from eight colonies in the Netherlands and Belgium were analyzed for PAHs in May-July 1991. In general, eggs containing embryos with elevated PAH concentrations in the yolk sac and with elevated hepatic EROD activity levels were laid later, had a more prolonged incubation period, were of smaller volume, and produced smaller chicks (Murk et al. 1996). 

A frequently asked question concerns the actual functional state of the crystallised protein. EPR analyses have shown, for example, that the enzyme present in aerobically prepared crystals of [NiFe] hydrogenase from D. gigas is mainly in its inactive, unready (Ni-A) state. However, it can be activated after prolonged incubation under hydrogen in the presence of methyl viologen (NiviHe et al. 1987). 

CYP enzymes are induced, resulting in reduced plasma drug levels. Alternatively, CYP enzymes could also undergo mechanism-based inhibition, whereby a CYP enzyme can be completely inactivated by covalent bonding to a component of the herb. Furthermore, botanicals can elicit a biphasic cellular response, whereby CYP activity may be inhibited initially, followed by induction after prolonged incubation or repeated administration. Such factors would need to be considered in future studies in order to establish the true risk of ginseng in herb-drug interactions. 

Essentially pure xylo-oligosaccharides in 0.5% concentration were incubated with Xylanase II at 50°C in 0.05M sodium citrate buffer, pH 5.0 for X5 through X7 and pH 6.05 for Xg and X9, and samples after varying periods were submitted to HPLC. With X5, X2 and X3 were the major products, with smaller amounts of X4 and D-xylose produced. Incubation of gave X3 as the major product, followed by X4 and X2. With prolonged incubation the X4 was consumed to form X2 and smaller amounts of D-xylose and X3. Hydrolysis of X7 led to the formation of X4 and X3, with smaller amounts of X5, and X2, and a very small amount of Xg. Tlie course... 

Since hemoproteins such as lactoperoxidase and catalase are inhibited more rapidly than the sulfhydryl oxidation occurs, it is unlikely that the rapid activation of guanylate cyclase occurs by sulfhydryl oxidation [132]. Prolonged incubation of the papain or dehydrogenase enzymes with substrate and nitroprusside yielded a turbidity which indicated denaturation of the enzyme to an insoluble form, possibly by the formation of disulfide bridges via the dimerization of thiyl radicals [132]. 

Upon prolonged incubation, formation of the species responsible for the broadened signal was shown to involve the nucleophilic (reductive) addition of Qo to a J-64 cysteinyl thiol group on Hb. The resultant conjugate was then oxidised by the parent quinone ... 

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