Quantitative determination of tiamenidine hydrochloride in human serum using gas chromatography mass spectrometry

A method has been developed for the blood level determination of the antihypertensive agent tiamenidine hydrochloride. The serum samples are mixed with deuterium labelled tiamenidine hydrochloride as an internal standard and extracted with methylene chloride. The extracts are derivatized with heptafluorobutyric acid anhydride and analysed by means of gas chromatography mass spectrometry using the selected ion monitoring technique to measure the molecular ion intensities of the bis-heptafluorobutyryl derivatives of tiamenidine hydrochloride and of the internal standard. Using 5 ml serum, the limit of detection is 0.2 ng ml-1 with an accuracy of +/- 0.17 ng (Syx of the calibration curve).     

The study of Salmonellaenteritidis growth kinetics using Rapid Automated Bacterial Impedance Technique

In order to study strain-specific differences in their growth behaviour at different, and particularly lower, temperatures, generation times for 45 strains of Salmonella enteritidis isolated from food were determined impedimetrically over a temperature range from 7 to 42 °C. In practical terms, 7 °C is the minimum requirement for Salm. enteritidis growth, and generation time variability increases markedly as this temperature is reached. Reports in the literature describing psychrotrophic behaviour and multiplication at lower temperatures cannot be confirmed. Generation time variability increased as temperature moved away from the optimal range with variation coefficients tending to rise as temperature fell. The great variability of multiplication parameters near the growth limit found in Salm. enteritidis may also be a characteristic of other bacterial species. It is therefore imperative to commence studies on larger numbers of strains to allow prediction of their behaviour at lower temperatures.     

2-((2-Pyridylmethyl)sulfinyl)benzimidazoles: acid sensitive suicide inhibitors of the proton transport system in the parietal cell

2-((2-Pyridylmethyl)sulfinyl)benzimidazoles, selective inhibitors of the H+/K+-ATPase in the parietal cells of the stomach, have been investigated concerning their chemical behaviour in acidic medium. Protonation of the sulfoxide and subsequent elimination of water forms a sulfenium ion or a chemical equivalent thereof. If no external nucleophiles are present, a rearrangement process takes place. In the presence of mercaptans, the sulfenium ion is trapped giving rise to a variety of products. On the basis of these results, a mechanistic scheme is proposed for the inactivation of the H+/K+-ATPase by these compounds.