Effect of UV irradiation on the mitotic cycle of Chinese hamster cells with varying UV sensitivity. I. The time ratios after irradiation of the cells with UV light

The distribution of cells through the phases of the cell cycle by DNA flow cytofluorimetry was analysed to investigate the effects of UV irradiation on cell cycle progression in asynchronous Chinese hamster cells with different UV-sensitivity: cell line V79 (UV-resistant cells), and UV-sensitive clones: B6, CHS1, CHS2 and XII. The UV-irradiated cultures show a large accumulation of cells in S phase, the effect increasing with UV dose increase, which may point to an inhibition of the DNA chain elongation. UV-sensitive clones show a larger and more prolongated increase in the proportion of cells in S phase after irradiation with smaller dose than UV-resistant cells. Besides, the UV-sensitive clone XII shows an inhibition of movement of irradiated cells from G1 into S phase, that may testify to an inhibition of replicon initiation. These results suggest that there is a correlation in UV-irradiated Chinese hamster cells between alteration in cell cycle progression and UV-sensitivity of cells.     

Gangliosides of sea urchin embryos. Their localization and participation in early development

The influence of antibodies to gangliosides of sea urchin Strongylocentrotus intermedius eggs on early embryos of this species was studied. gamma-Globulins were isolated from rabbit anti-ganglioside serum by micropreparative electrophoresis. These gamma-globulins produced anomalies in the development of embryos permeabilized in Triton X-100. The anomalies were not observed when anti-ganglioside gamma-globulins were added to the incubation medium together with gangliosides or when the permeabilized embryos were incubated with gamma-globulins of normal rabbit serum. Pretreatment of S. intermedius embryos with serotonin, tryptamine or some other indole derivatives led to the disappearance of ganglioside determinants from the cell surface and sharply increased immunofluorescence within the cell. Such pretreatment of embryos increased the amount of cell-associated gangliosides more than threefold as compared to untreated embryos. Serotonin was shown to bind specifically to sea urchin gangliosides immobilized on octyl-Sepharose. These observations suggest that cell-surface gangliosides, after binding drugs, are internalized and that serotonin and its antagonists inhibit the transport of newly synthesized gangliosides to the cell-surface membrane.     

Changes in the innervational connections of the urinary bladder upon experimental stimulation of the hypothalamus]

The innervation of the urinary bladder was studied in 40 rabbits, 5 of which were control and in 35 animals the posterior and anterior nuclei of the hypothalamus were stimulated by electric current through bipolar electrodes. The efferent innervation connections in whose terminal plexuses there occurred absorption of catecholamines were shown histochemically and neurohistologically to be involved in the pathological process. Reactive and degenerative changes were found to take place in receptory nerve terminations, and first of all in free ones. Then the bodies of pseudounipolar neurons of spinal ganglia were changed. Changes were also found in the connections of sensory neurons with the cells of Goll's and Burdach's nuclei.     

Localization of heat shock protein 70 in rat mast cells

Heat shock proteins (Hsp) are intracellular chaperons, as well as extracellular molecules with immunomodulatory and signaling functions engaged in adaptation to stress on the cellular and organism levels. The presence of Hsp in secretory granules of mast cells (MCs) may be correlated with mast cells’ active participation in adaptation to stress. Using immunoelectron microscopy, we showed that Hsp70 was localized in secretory granules of rat pericardial and peritoneal mast cells. Localization of Hsp70 in rat peritoneal mast cells isolated by Percoll density gradient centrifugation was confirmed by immunoblotting. The possible involvement of mast cells in production of extracellular Hsp70, as well as Hsp70 functions inside the mast cells, is discussed.     

Evaluation of the size of the microsphere loss from the myocardium in rats in a chronic experiment

The loss of radioactive microspheres (15 microns in diameter) from the rat myocardium was investigated during chronic experiment. Microspheres were injected to donor rats, the hearts were removed 20-30 min later and the number of microspheres trapped in the heart was determined on gamma-counter. After that the hearts were transplanted into the abdominal cavity of recipient rats using microsurgery technique. 5-24 days later the recipients were killed, the transplanted hearts were removed and radioactivity was measured again. It was shown that not more than 10% of microspheres were lost from the myocardium over a 5-24-day period, with the value of microsphere loss independent of the time period.     

Features of blood-brain barrier formation affected by the modulation of HIF activity in astroglial and neuronal cells in vitro

Barriergenesis is the process of maturation of the primary vascular network of the brain responsible for the establishment of the blood-brain barrier. It represents a combination of factors that, on the one hand, contribute to the process of migration and tubulogenesis of endothelial cells (angiogenesis), on the other hand, contribute to the formation of new connections between endothelial cells and other elements of the neurovascular unit. Astrocytes play a key role in barriergenesis, however, mechanisms of their action are still poorly examined. We have studied the effects of HIF-1 modulators acting on the cells of non-endothelial origin (neurons and astrocytes) on the development of the blood-brain barrier in vitro. Application of FM19G11 regulating expression of HIF-1 activity and GSI-1 suppressing gamma-secretase and/or proteasomal activity resulted in the elevated expression of thrombospondins and matrix metalloproteinases in the developing blood-brain barrier. However, it caused the opposite effect on VEGF expression thus promoting barrier maturation in vitro.     

Molecular biological monitoring for Streptococcus pneumoniae isolated from patients with invasive pneumococcal infection

Pneumococcal infection is one of the most important problems of the modern medicine. Need for organization of system of epidemiological surveillance for this infection with obligatory assessment of epidemic genovariants by molecular biological methods is evident. Assessment of pneumococci isolated from patients and carriers by using multilocus sequence typing, pulse-field electrophoresis, and restriction fragments length polymorphism analysis allowed to conclude that the latter method, which have high discriminating ability, is advantageous for these purposes.     

Monoclonal antibody to dengue capsid protein: Its application in dengue studies

Dengue fever (DF) and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) are considered the most important arthropod-borne viral diseases in terms of morbidity and mortality. The emergency and severity of dengue (Den) infections increase the necessity of an early, quick and effective dengue laboratory diagnostic. Viral isolation is considered a gold standard for diagnosis of dengue infection using monoclonal antibodies (mAbs) as a tool for determining serotype specificity. Alternatives have been used to improve sensitivity and time to dengue diagnosis. Based on the early expression of dengue C protein in the life cycle, we focused our study on the application of an anti-dengue 2 virus capsid protein mAb in dengue diagnosis. The kinetic expression of dengue-2 capsid in mosquito cells and its immuno-localization in experimentally infected suckling albin Swiss (OF-1) mice brain tissues was established. The results demonstrate the possible utility of this mAb in early dengue diagnosis versus traditional isolation. In addition, a preliminary study of an enzyme immunoassay method using 8H8 mAb for specific detection of dengue C protein antigen was performed, making possible recombinant C protein quantification. The results suggest that detection of dengue capsid protein could be useful in the diagnosis of early dengue infection.Key words: monoclonal antibodies, capsid protein, dengue virus, diagnosis, immunoassays