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This paper reports the experimental data on the conservability of zolpidem and zalepion in the samples of the cadaveric liver tissue stored under different conditions. The authors describe the method that includes isolation of the substances of interest from the hepatic tissue by means of acetone extraction, their solvent and chromatographic purification, and subsequent identification with the help of the spectrophotometric technique. It is shown that zolpidem and zaleplon remain in the cadaveric hepatic tissue within 6 months after intoxication regardless of temperature which makes possible their detection, isolation, and identification by the proposed method.

A new aliphatic amidase gene (ami), having a level of similarity with the nearest homologs of no more than 77%, was identified in the Rhodococcus erythropolis TA37 strain, which is able to hydrolyze a wide range of amides. The amidase gene was cloned within a 3.7 kb chromosomal locus, which also contains putative acetyl-CoA ligase and ABC-type transportergenes. The structure of this locus in the R. erythropolis TA37 strain differs from the structure of loci in other Rhodococcus strains. The amidase gene is expressed in Escherichia coli cells. It was demonstrated that amidase (generated in the recombinant strain) efficiently hydrolyzes acetamide (aliphatic anmide) and does not use 4'-nitroacetanilide (N-substituted amide) as a substrate. Insertional inactivation of the amidase gene in the R. erythropolis TA37 strain results in a considerable decrease (by at least 6-7 times) in basal amidase activity, indicating functional amidase activity in the R. erythropolis TA37 strain.

Two groups of male volunteers for 4-day dry immersion with and w/o countermeasures (support load imitator (SLI) or high-frequency electrostimulator) underwent ultrasonic investigation (USI) of the liver, gastroduodenal organs and vessels, and blood biochemical analysis. Two other groups of volunteers performed the 13C-methacetin breath test (13C-MBT) to study the effects of immersion and SLI on the liver detox activity and metabolic capacity. In immersion, USI diagnosed slowdown of blood flow along the hepatic vein and signs of plethora in the abdominal venous system. In addition, immersion was accompanied by increases in blood pepsinogen, pancreatic amylase, total bilirubin, the "indirect" fraction specifically, insulin and C-peptide. 13C-MBT detected deceleration of 13C-methacetin inactivation and diminution of the liver metabolic capacity. Administration of the countermeasures did not improve the ultrasonic image of hemodynamic alterations in the liver and abdomen significantly. High-frequency electrostimulation cancelled out changes in all biochemical parameters except C-peptide; SLI was favorable to recovery of pepsinogen and amylase baseline values only. Besides, the SLI wearing prevented loss of the 13C-methacetin inactivation rate but was not effective enough against diminution of the hepatic metabolic capacity.

In spite of decades of research, our understanding of the principles of antibiotic binding to the ribosome and the mechanisms of drug action remains only fragmentary. Recent progress in biochemical and genetic studies of some "old" and new antibiotics and the availability of high-resolution structures of the ribosome subunits allows mapping the antibiotic-binding sites at atomic resolution. In this review, interaction of three groups of antibiotics with the ribosome and the mechanisms of the drug action are discussed, considering the data used to map the binding sites of the new macrolide derivatives, ketolides, a novel clinically important antibiotic linezolid, and a still experimental drug evernimicin.

Nitrasepam is transformed to amino and acetamide derivatives in the rat intestine. Reduction of nitrasepam and its following acetylation in the duodenum and small intestine are catalyzed by the mucosal enzymes. In the cecum and the large intestine these processes are mediated through the action of the microbes and tissue enzymes, whereas in the rectum--through the microbes only.

The model system for the proton transfer on the amide atom of the substrate leaving group based on the existence of "charge relay system" in the serine type proteases was analysed by the CNDO/2 method. The unfitness of this model to explain the action mechanism of serine proteases was shown. The model system for proton transfer with the water molecule as the intermediate acceptor of the Ser-195 proton was suggested and analysed by the same method. The acylation activation barrier of this system was shown to localize on the stage of synchronous transfer of the Ser-195 alcoholic proton and the water molecule proton hydrogen bound to the His-57 N epsilon 2-atom on the water molecule oxygen atom and the N epsilon 2-atom, respectively. The protonation of substrate in the case of the model system with the water molecule as the intermediate acceptor of proton was demonstrated to begin before the completion of the tetrahedral intermediate substance and the protonated from of the tetrahedral intermediate was shown to form only. A hypothesis considering the role of this water molecule as the nucleophilic reagent on the deacylation stage is presented.