[Stable isotope diagnostics in Russia; results and prospects, 13C-preparations, instruments, methods].

The basis of the highly effective method for diagnostics of many dangerous diseases with the use of breathing tests and stable 13C isotope-labeled preparations has been developed in Russia during the past years. The technology for manufacturing 13C-preparations using domestically produced starting materials satisfies the requirements for isotopes in this and many foreign countries. New instruments for respiratory tests and diagnostic methods make it possible to carry out diagnostics in large populations including that in the course of regular medical examination. This paper reports high efficacy of 13C-based breath tests for diagnostics of gastrointestinal disorders, possibilities and prospects for their further application in oncology, endocrinology, pulmonology, neurology, cardiology, surgery, etc. Special attention is given to the use of 13C-magnetic resonance techniques for visualization of tumours and blood vessels, studies of metabolic processes and energy balance in man and animals with the use of 13C-biomarkers. The main advantages of these new diagnostic approaches are high accuracy, safety (for both patients and personnel), simplicity, and possibility of application in different fields of medicine.

[Mass spectrum and uniformity of decomposition of certain 2-substituted 9-(o-chlorbenzyl)-8-azahypoxanthines]. / Mass-spektry i zakonomernosti raspada nekotorykh 2-zameshchennykh 9-(o-khlorbenzil)-8-azagipoksantinov.

The regularities of mass spectrometric fragmentation under electron impact of new 9-(o-chlorobenzyl)-8-azahypoxantines with (N-aryl)amidocarbonylmethylthiomethyl substituents in position 2 were studied. The main fragmentation pathways are the elimination of Ar-NH+ and o-chlorobenzyl ions and cleavage of C-S bonds, characteristic of organic sulfides. During the fragmentations, some rearrangements occur, consisting in the transfer of labile hydrogen atoms from the alpha-positions to ions being eliminated. Fragmentation of 8-azapurine parts of the molecules does not prevail. Peaks of molecular ions are clearly visible in the mass spectra of all the substances studied. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 1; see also http://www.maik.ru.

[Use of ion-exchange sorbents for determining drug preparations and their metabolites in biological fluids by high-performance liquid chromatography]. / Primenenie ionoobmennykh sorbentov pri opredelenii lekarstvennykh preparatov i ikh metabolitov v biologicheskikh zhidkostiakh metodom vysokoéffektivnoi zhidkostnoi khromatografii.

High performance liquid chromatography has acquired great importance recently for an analysis of the drugs in biological fluids of the body. Phase inversion sorbents are particularly widely used today. However, the use of ion-exchange sorbents is fairly promising for an analysis of the drugs capable of ionizing in an aqueous solution. The authors illustrate the use of the latter ones for determination in the blood, urine and saliva of man of a number of the cardiologic drugs (etmozine, nonachlazine, verapamil, prazosin, propranolol, nadolol). Ion-exchange sorbents make it possible to attain better results than inverse phase ones, since they retain the drugs selectively and do not retain the endogenous substances of lipid nature. As regards verapamil, prazosin and propranolol, the unchanged drug and polar metabolites could be determined jointly, with such a determination being not feasible with the use of phase inversion sorbents. Separation of the diastereoisomers of nadolol was achieved in the blood and urine of patients who received the drug.