Effects of Salmonella typhimurium infection and ofloxacin treatment on glucose and glutamine metabolism in Caco-2/TC-7 cells.

The effects of both Salmonella typhimurium infection and 5 mM ofloxacin treatment on 2 mM glutamine and 5 mM glucose metabolism in the enterocyte-like Caco-2/TC-7 cell line were studied. These cells utilized glutamine (212.07 +/- 16.75 [mean +/- standard deviation] nmol per h per 10(6) viable cells) and, to a lesser extent, glucose (139.63 +/- 11.52 nmol per h per 10(6) viable cells). Metabolism of these substrates in Caco-2/TC-7 cells resembled that in rat, pig, or human enterocytes. Infection by S. typhimurium C53-enhanced glucose and glutamine substrate utilization by 32 and 22%, respectively and enhanced glucose and glutamine substrate oxidation by eight- and twofold, respectively. These increases in glucose and glutamine metabolism (especially glucose metabolism) were due in part to the metabolism of intracellular bacteria and/or to the activation of cellular metabolism. Substrate metabolism (especially glucose metabolism) in C53-infected cells was partially reduced by treatment with ofloxacin. It was concluded that cellular fuel metabolism is stimulated at the earliest stage of infection (3 to 4 h) and that treatment with 5 mM ofloxacin does not completely restore substrate metabolism to the levels observed in uninfected cells, possibly because this treatment does not eradicate intracellular S. typhimurium completely.

Determination of ethambutol in plasma by high-performance liquid chromatography after pre-column derivatization.

A new HPLC assay using UV detection (200 nm) was developed to determine ethambutol (EMB) concentrations in plasma. Following extraction (0.1 ml plasma) with chloroform, EMB and octylamine (used as internal standard) were derivatized with phenylethylisocyanate. Quantitation in plasma was achieved at 200 nm. There were no interferences from endogenous compounds. Intra- and inter-day variabilities were lower than 5.2 and 7.6%, respectively. The limit of quantitation of the method was 0.2 microg/ml. In plasma, ethambutol was found to be stable for at least one month when samples were stored at -20 degrees C. This assay was applied to the therapeutic monitoring of EMB concentrations in 19 patients suffering from tuberculosis.

Fast specific separation and sensitive quantification of bactericidal and sporicidal aldehydes by high-performance liquid chromatography: example of glutaraldehyde determination.

This article describes the design and the validation of the HPLC determination of glutaraldehyde at g/l and mg/l concentrations, after derivatization by 2,4-dinitrophenylhydrazine and using the external standard method. At low concentrations, the reaction mixture needs to be heated and a weight ratio of 500 for the 2,4-dinitrophenylhydrazine reagent and the glutaraldehyde ensures a linear calibration curve. In contrast, high concentrations do not require heating of the reaction mixture and a weight ratio of 32 proved to be sufficient. The optimized HPLC method has been validated for both ranges of concentrations. Between 1.25 and 10 mg/l, the content can be determined by the external standard method, with a repeatability of 0.5%. The detection limit is 0.2 mg/l. Between 0.31 and 2.5 g/l, the content can also be determined by the external standard method, with a repeatability of 0.4%. Finally, statistical analysis has demonstrated that aqueous solutions of glutaraldehyde are stable for at least three days at 4 degrees C within the mg to g range.