Hypoxic coordinate regulation of mitochondrial enzymes in mammalian cells

The effect of hypoxic exposure on various mitochondrial enzymes and on cell mitochondrial genomic content was studied in two types of mammalian cells. Hypoxia depressed the activity of six enzymes to the same degree. The kinetics of depression and of recovery during reexposure to normoxia were statistically similar for three marker enzymes. Despite the global and symmetrical decrease in enzyme activities, mitochondrial DNA remained constant. This suggests either symmetrical loss of mitochondrial enzymes from all mitochondria or complete loss of enzymes from a subpopulation of mitochondria with retention of an intact mitochondrial genome.

The determination of the triazolobenzodiazepine triazolam in post mortem samples

A post mortem case involving the triazolobenzodiazepine triazolam is reported. Levels of 38 ng/g in the liver and 6.7 ng/mL in the blood were determined by reversed-phase high-performance liquid chromatography (HPLC) using an eluent of 0.06% acetic acid:acetonitrile (61:39) and ultraviolet detection at 221 nm. The presence of triazolam in the post mortem samples was verified by its oxidation to a benzophenone with potassium dichromate, followed by the analysis of the oxidized extract by HPLC using a silica column and an eluent of dichloromethane:methanol (97.5:2.5) at 250 nm.

The carbanion mechanism of olefin-forming elimination. VIII. Theoretical analysis of substituent and isotope effects in proton transfers from 2,2-Diaryl-1,1,1-trichloroethanes

Rate constants for the dehydrochlorination of the title compounds by anionic bases in alcoholic solvents are those for simple proton transfer. Rate and estimated equilibrium data for these reactions can be approximately analysed in terms of the Marcus theory of proton transfer. In one reaction series comprising the reactions of para-substituted Ar2CHCC13 compounds with NaOMe in MeOH, the work term (wr) and the intrinsic free energy of activation (ΔG?) are comparable and large. The change in kH/kD with variation in substituent can be quantitatively rationalized, and the fact that kH/kD does not pass through a maximum even though ΔpK = 0 within the series can be understood. Although the required rate-equilibrium parabolic relationship for a second series involving the reactions of (p-ClC6H4)2CHCCl3 with a series of bases is obtained, anomalous Marcus parameters are derived, and reasons for the anomalies are given. A revised set of approximate pKa values for Ar2CHCCl3 compounds is presented, and more precise experimental values of rate constants for the reactions of (p-NO2C6H4)2CHCC13 and (p-NO2C6H4)2CDCCl3 with NaOMe in MeOH are provided.