[Study of bioavailability of different forms of synthetic beta-carotene in volunteers]. / Izuchenie biodostupnosti razlichnykh form sinteticheskogo beta-karotina na dobrovol'tsakh.

The concentration of beta-carotene analyzed in blood serum of 30 healthy men and women aged 17-50 years by the method of HPLC in May-June 1990 was in range 3.3-29.5 and in average 12.0 +/- 1.2 micrograms/100 ml. Concentration of carotene determined by Bessay's spectrophotometric method as sum of carotenoids composed 58.0-215.0 and in average 120.5 +/- 7.5 micrograms/100 ml. This level of carotenoids is higher by 10 times than level of beta-carotene detected by HPLC. But the levels of carotenes in blood serum detected by two methods are in positive correlation (r = 0.8). Single intake by volunteers 25 mg of synthetic beta-carotene in three different forms (as cyclodextrin derivation, or 30% microcrystalic suspension in vegetable oil, or 10% water-soluble form produced by Hoffman-La Roche company) caused increasing of beta-carotene concentration in serum with maximum within 24-48 hours. Bioavailability of cyclodextrin derivation of beta-carotene, determined by absolute increasing of beta-carotene concentration in serum, was lowest than that of other forms. Bioavailability of beta-carotene as 30% microcrystalic suspension in vegetable oil or 10% water-soluble form was practically the same. Intake of beta-carotene did not effect on level of retinol in serum which was in normal range.

[Bioavailability and pharmacodynamics of various forms of synthetic beta-carotene in volunteers]. / Izuchenie biodostupnosti i farmakodinamiki razlichnykh form sinteticheskogo beta-karotina na dobrovol'tsakh.

The biological availability of artificial beta-carotene as a water-soluble versus oily formulation based on cyclodextrin (Cyclocar tablets) was studied on volunteers given a single dose of 25 mg. The concentrations of beta-carotene and major carotenoids were measured in the blood serum during the experiment by high performance liquid chromatography. The maximum content of beta-carotene in the serum was attained 24-30 and 30-48 hrs after oily formulations and Cyclocar and were 48.0 +/- 7.7 and 28.1 +/- 3.6 mg/dl, respectively. The rate of beta-carotene utilization from Cyclocar was 2.2 times less than that from the oil paste. Besides, beta-carotene absorbed from these oily drugs retained in the blood serum for longer period than that form Cyclocar.

Kinetics of soybean lipoxygenase reaction in hydrated reversed micelles.

The rate of linoleic acid peroxidation catalysed by soybean lipoxygenase I was studied as a function of the hydration degree of aerosol OT (bis(2-ethylhexyl) sulfosuccinate sodium salt) reversed micelles in octane. Lipoxygenase reaction parameters for the micelle-bound substrate were spectrophotometrically determined. The linoleic acid distribution between the micelles and octane was detected by the sedimentation method, with the concentration of linoleic acid in supernatant after settling of micelles (i.e. the concentration of free linoleic acid) being estimated by the enzymatic method. The apparent constant of linoleic acid distribution (the ratio of the bound and free substrate concentrations) was enhanced with increasing hydration of reversed micelles. The dependence of the enzymatic reaction rate on the bound substrate concentration obeyed the empiric Hill equation. The Hill coefficient remained practically constant (h = 1.34) as the hydration degree changed. Parameters of the lipoxygenase reaction, enzyme reaction limiting rate V and semi-saturation substrate concentration [S]0.5 increased with increasing degree of hydration and reached the optimum at [H2O]/[AOT] approximately 30, where dimensions of the micellar internal cavity coincided with those of the enzyme molecule. Some aspects of kinetic behavior of membrane-bound enzymes participating in chemical transformation of non-polar compounds dispersed in lipid phase are discussed.

[Electric charge of the surface of lymphocytes and their ability to divide mitotically during induced carcinogenesis]. / Elektricheskii zariad poverkhnosti limfotsitov i ikh sposobnost' k mitoticheskomu deleniiu pri indutsirovannom kartsinogeneze.

Electrophoretic mobility of murine lymphocytes of the spleen was investigated during the development of reaction to damage and to the initial stages of induced cancerogenesis. These two processes differ in kinetics data of the change of electrophoretic mobility. A correlation was found between the electrophoretic mobility and ability of the cell for blast transformation under the influence of lectin PHA.