Possible role of the T-cells in regulating in situ hematopoiesis

The aim of the study was to reveal the possible role of T cells in the negative regulation of hematopoiesis. The main experimental approach included incubation of bone marrow cells obtained from mice of different strains with the anti-serum against a specific marker of suppressor T cells--antigen I-J. Anti-I-Jk serum-treated cells and cells treated with nontoxic normal mouse serum or non-treated cells (controls) were further incubated with complement and tested for their CFUs content, using Till & McCulloch exocolonization technique. Treatment with anti-I-Jk serum had a stimulating effect on the CFUs colony formation in mice of the appropriate haplotype (CBA, AKR, A/Sn) bearing I-Jk, but not I-Jb (CC57Br) allele. The same results were obtained in transfer experiments using spleen cells; only in this case stimulating effect was observed in 7-8-day CFUs, while with the marrow transplant augmentation it was seen both 7-8 and 11-12 days following grafting. The seeding efficiency of CFUs was not changed after incubation with anti-I-J serum. The data prove that indigenous for the spleen and bone marrow of mice cells expressing I-J determinants are involved in the negative regulation of hematopoiesis in situ.     

Within and between species competition in a seabird community: statistical exploration and modeling of time-series data

In a changing environment, the maintenance of communities is subject to many constraints (phenology, resources, climate, etc.). One such constraint is the relationship between conspecifics and competitors. In mixed colonies, seabirds may have to cope with interspecific and intraspecific competition for both space and food resources. We applied competitive interaction models to data on three seabird breeding populations: black-legged kittiwake (Rissa tridactyla), common guillemot (Uria aalge) and Brünnich's guillemot (Uria lomvia) collected over 27-years at Kharlov Island in the Barents Sea. We found a competitive effect only for the kittiwake breeding population size on the common guillemot breeding population size when kittiwakes were abundant. The timing of kittiwake breeding negatively affected the number of breeding Brünnich's guillemots. The timing of breeding was negatively correlated to biomass of the main pelagic fish in the Barents Sea, the capelin (Mallotus villosus), which suggests an indirect action. The community matrix shows that the community was not stable. The kittiwake population did not decrease as seen in north Norwegian populations. Likewise, the common guillemot population, after a crash in 1985, was recovering at Kharlov while Norwegian populations were decreasing. Only the Brünnich's guillemot showed a decrease at Kharlov until 1999. We suggest that the stability of the kittiwake and common guillemot populations at Kharlov is due to better feeding conditions than in colonies of the Norwegian coast, linked to a possible eastward shift of the capelin population with the temperature increase of the Barents Sea.     

Influence of Lactobacillus on the migration activity of macrophages

Influence of Lactobacillus on the migration activity of intact macrophages during their cultivation with serum and supernatant of cells from Peyer's patches and spleen that were obtained from mice of CBA line orally sensibilized with lactobacteria was studied. Data about stimulation of production of factor inhibiting migration of macrophages by immunocompetent cells and development of delayed-hypersensivity reaction are obtained. Mechanisms of complex influence of lactobacteria on cell factors of innate and adaptive immunity are discussed.     

The presence of nitric oxide synthase in mucosal epithelial cells of the frog urinary bladder

In experiments on frog Rana temporaria L. urinary bladder, we investigated localization of NO-synthase (NOS) in urinary bladder slices and measured NOS activity in the suspension of mucosal epithelial cells. Intensive NADPH-diaphorase staining which is widely used as an indicator of NOS activity was found in mucosal epithelium. Almost all mucosal epithelial cells isolated in Ca2+ -free conditions demonstrated positive NADPH-diaphorase reactivity. Direct measurement of NOS activity in suspension of mucosal cells determined by the rate of conversion of L-arginine to L-citrullin showed that the enzyme activity was reduced in absence of external Ca2+ and was inhibited by L-NAME: non-specific NOS inhibitor, and 1400 W: a highly selective iNOS inhibitor (control: 754 +/- 184; L-NAME, 1 mM 329 +/- 87; 1400 W, 20 mM: 547 +/- 25; Ca2+ -free/EDTA: 490 +/- 184 cpm [3H]-citrullin/10(6) cells per 45 min, p < 0.05, n = 7-8). The data obtained demonstrate that frog urinary bladder mucosa epithelial cells provided antidiuretic hormone-induced increase of osmotic water permeability contain nitric oxide synthase. The presence of inducible (iNOS) as well as constitutive isoform(s) revealed in these cells allows to suggest involvement of NOS in intracellular signaling pathways regulated water transport across the epithelium.     

Does collagen microunfolding stimulate fibril formation?

The data on the effect of temperature on the kinetics of collagen fibril formation at physiological pH values and ionic strength in the temperature range 26–39°C have been analyzed. The temperature of 35°C optimal for collagen fibril formation has been defined as the point of inflection for half-maximal turbidity and collagen molecule microunfolding values, which corresponds to the temperature of the first transition on the heat absorption curve. The temperature range (32–35°C) in which collagen microunfolding stimulates fibril formation has been determined.     

The decline in antibodies to hepatitis C virus during antiviral therapy

The goal of the study was to analyze B-cell response to hepatitis C virus during antiviral therapy among responders and non-responders. The content of antibodies to individual structural and non-structural HCV proteins was investigated during two years in three groups of patients: initial responders, non-responders and a reference group (without therapy). Treated patients in all groups exhibited the decrease in antibodies to analyzed HCV proteins, but with different patterns. The first statistically significant differences in the decline of the virus-specific antibodies between initial responders and non-responders were observed within the first three months after the beginning of therapy. Some treated patients demonstrated the decrease in antibody levels to HCV proteins after the end of therapy.