Synthetic melatoninergic ligands: achievements and prospects.

Pineal hormone melatonin is widely used in the treatment of disorders of circadian rhythms. The presence of melatonin receptors in various animal tissues motivates the use of this hormone in some other diseases. For this reason, in recent years investigators continued the search for synthetic analogues of melatonin which are metabolically stable and selective to receptors.

Non-obvious Problems in Clark Electrode Application at Elevated Temperature and Ways of Their Elimination.

Well-known cause of frequent failures of closed oxygen sensors is the appearance of gas bubbles in the electrolyte. The problem is traditionally associated with insufficient sealing of the sensor that is not always true. Study of a typical temperature regime of measurement system based on Clark sensor showed that spontaneous release of the gas phase is a natural effect caused by periodic warming of the sensor to a temperature of the test liquid.

[Ambient air interference in oxygen intake measurements in liquid incubating media with the use of open polarographic cells].

A model of oxygen intake by aerobic bio-objects in liquid incubating media was applied to investigate the influence air-media interface area on accuracy of measuring the oxygen intake and error value. It was shown that intrusion of air oxygen increases the relative error to 24% in open polarographic cells and to 13% in cells with a reduced interface area. Results of modeling passive media oxygenation laid a basis for proposing a method to reduce relative error by 66% for open cells and by 15% for cells with a reduced interface area.

[Determination of cholesterol esterase activity using micro-thin layer chromatography].

A procedure is developed for estimation of the cholinesterase activity in biological materials immediately on the plates for micro-thin-layer chromatography using a chamber of original construction. The procedure involved incubation of cholesterol esters, used as substrates and biological materials containing the enzyme, directly on the chromatographic plates in the chamber and the subsequent chromatography of the hydrolysis products. The enzymatic activity was calculated on the basis of the decrease in the substrate content per min per mg of protein.