Colloid-SEM method for the investigation of magnetic domain structures.

The paper presents scanning electron microscopy (SEM) studies on the magnetic domain structure (DS) using magnetic colloid. The possibility of colloid-SEM method for observing the DS of mono- and polycrystalline samples in the secondary (SEI) and backscattered electrons modes (BEC) is demonstrated. Owing to the large focal depth of SEM, it is possible to observe the overall DS and fine features, even in unpollished samples.

[The influence of testosterone on activity of glycosidases and proteinases in the intestine of the sterlet (Acipenser ruthenus)].

Observation of the influence oftestosterone (0.7 mg/kg) on the activity ofglycosidases and proteinases, which function in the chime and the mucous coat of the sterlet intestine (Acipenser ruthenus), revealed a decrease in enzyme activity of both chains as against that one typical for intact individuals. The activity of the investigated enzymes changes in both the experimental and control groups offish. Nevertheless, they have unlike dynamics of this activity. In a number of cases, we indicated a significant increase in enzyme activity of both chains in comparison to the control group. We also observed an increase in activity of chime glycosidases, which was significant on the 21st day as compared to intact fish.

[Influence of genetic and phenotypical factors on the efficiency of the vaccination of young children against diphtheria and measles].

The child's sex was shown to influence the character of antibody formation only after immunization against diphtheria with live measles vaccine: girls exhibited stronger reaction to vaccination than boys. Children of different gender were found to have characteristic HLA DR markers of humoral immune response to diphtheria toxoid and measles vaccine. HLA DR7 proved to be the marker of low production of antibodies to diphtheria toxoid and measles vaccine in boys.

Photosensitized light-induced damage of IRBP (interphotoreceptor retinoid-binding protein): effects on binding properties.

PURPOSE: To determine if IRBP (interphotoreceptor retinoid-binding protein) is damaged following irradiation by visible light in the presence of bound all-trans retinal. METHODS: Following irradiation of the IRBP-all-trans retinal complex, the retinal was removed and damage to IRBP measured as loss of titratable thiol groups, loss of tryptophan fluorescence, and changes in retinol-binding-induced fluorescence. RESULTS: IRBP irradiated by itself showed only minimal loss of tryptophan fluorescence; this loss was substantially increased by irradiation in the presence of all-trans retinal. Thiol groups and retinol-binding activity were also shown to be reduced. The damage to IRBP seemed to involve photosensitization by the all-trans retinal, which was in turn protected from bleaching by the IRBP. The binding affinity was shown to be reduced ten-fold following irradiation. CONCLUSION: In the eye, IRBP can stabilise vitamin A and debatably may be responsible for transport of different forms of vitamin A between the photoreceptor cells and pigment epithelium. If this is the case, it would play a key role in rhodopsin regeneration after bleaching. IRBP also appears to be necessary to sustain photoreceptor cells. Light was shown to cause photosensitized damage to IRBP, and thus might impair the regeneration process and photoreceptor viability.