Interaction of Loach DNA Polymerase δ with DNA Duplexes with Single-Strand Gaps

The interaction of DNA polymerase purified from eggs of the teleost fish Misgurnus fossilis (loach) with DNA duplexes with single-strand gaps of 1-13 nucleotides was studied. In the absence of template-restricting DNA, the enzyme elongated primers on single-stranded DNA templates in a distributive manner. However, in the presence of the proximal 5"-terminus restricting the template, the enzyme activity significantly increased. In this case, the enzyme was capable of processive synthesis by filling gaps of 5-9 nucleotides in DNA duplexes. These data indicate that DNA polymerase can interact with both the 3"- and 5"-termini located upstream and downstream from the gap. Analysis of the complexes formed by DNA polymerase and different DNA substrates by electrophoretic mobility shift assay confirmed the assumption that this enzyme can interact with the proximal 5"-terminus restricting the gap. DNA polymerase displayed much higher affinity in duplexes with gaps of approximately 10 nucleotides compared to the standard template–primer complexes. Maximal affinity was observed in experiments with DNA substrates containing unpaired 3"-tails in primers. The results of this study suggest that DNA polymerase exerts high activity in the cell nuclei during repair of DNA intermediates with single strand gaps and unpaired 3"-termini.     

Helper B cells promote cytotoxic T cell survival and proliferation independently of antigen presentation through CD27/CD70 interactions

CD8-expressing cytotoxic T cell (CTL) interactions with APCs and helper T cells determine their function and ability to survive. In this study, we describe a novel interaction independent of Ag presentation between activated CTLs and bystander CD19-expressing B lymphocytes. Ag-stimulated CTLs serially engage autologous B lymphocytes through CD27/CD70 contact that promotes their survival and proliferation. Moreover, these interactions induce the release of proinflammatory cytokines that follows two general patterns: 1) an epitope-dependent enhancement of cytokine release, and 2) a previously undiscovered coordinate release of cytokines independent of epitope exposure. The latter includes chemoattractants targeting activated T cells. As a result, activated T cells are attracted to B cells, which exert a "helper" role in lymphatic organs or in areas of inflammation. This observation provides a mechanistic explanation to previously reported experimental observations suggesting that B cells are required for T cell priming in vivo.     

Involvement of endogenous digitalis-like factors in voluntary selection of alcohol by rats.

This study tested the hypothesis that endogenous digitalis-like factor (DLF) is involved in the development of alcohol dependence in rats. In 33 male Wistar rats in conditioned place preference (CPP) experiment, ethanol evoked increase in time spent in the ethanol-associated compartment (702+/-82 in ethanol-treated vs. 426+/-86 sec in the controls). Digoxin pretreatment (125 microg/kg, i/p) did not affect the time spent in the water-associated compartment (476+/-80 sec), but prevented the acquisition of ethanol CPP (385+/-112 sec in ethanol-paired side, P<0.05). In a two bottle choice test, where rats (n=6 per group) chose between drinking water and 9% ethanol, immunization against two putative DLFs, marinobufagenin and ouabain (MBG and OLC) resulted in a 60% increase of ethanol consumption. Acute intragastric administration of 9% ethanol to the rats was associated with increased OLC in cerebrospinal fluid, and stimulated urinary excretion of MBG and OLC. Thus, in rats, digoxin, which mimics the effects of DLFs, suppresses the free choice of alcohol, while immunization against DLFs is associated with alcohol seeking behavior.     

A comparative evaluation of methods of radiologic diagnosis in determining the functional status of the right ventricular myocardium in tetralogy of Fallot

In order to study the informative value of two-dimensional echocardiography (EchoCG) in the assessment of right ventricular function in Fallot's tetrad the results of echocardiography were compared with those of angiocardiography. A total of 40 patients aged 2 to 13 with the cyanotic form of the defect were investigated. Functional indices were calculated using Simpson's rule. The highest correlation in comparing echo- and angiocardiography results was obtained for the end-diastolic volume (r = 0.94), a slightly lower one--for the end-systolic volume (r = 0.92). The mean value of the right ventricular ejection fraction (EF) by the results of echocardiography was 0.62 +/- 0.05 +/- 0.08, by the results of angiocardiography--0.62 +/- 0.05 +/- 0.09. The correlation coefficient characterizing the proximity of EF values, obtained by the above methods, was 0.89. The greatest divergences in the results were noted in the calculation of the minute volume. It can be accounted for by the patients' different state at the time of invasive and non-invasive investigation. A high informative value and accuracy of two-dimensional echocardiography was proved in the assessment of right ventricular function in Fallot's tetrad.     

Interaction of cells from murine organs with liposomes of various composition

The distribution of liposomes prepared from total mouse liver lipids and containing (3H)-labelled platelet activation factor in mouse organs was studied. It was shown that the majority of intraperitoneally injected liposomes prepared from total mouse liver lipids were transported to mouse liver and spleen. The interaction of liposomes with spleen cells in vitro revealed that the affinity of liposomes prepared from total spleen macrophage or total spleen lymphocyte lipids for mouse spleen cells was much higher than that of liposomes prepared from a model lipid mixture. The liposome binding to isolated spleen macrophages or lymphocytes was much higher than the liposome uptake by these cells in the total population of mouse spleen cells.     

Peculiarities of somatovisceral reactions in early postnata ontogenesis

To reveal possible ways of the somatovisceral interaction, in the 0–5-day, 11–13-day and one-month-old rats, reactions of the spontaneous contractile activity of the gastric antrum were studied to a rhythmic stimulation of the tibial nerve for 30 s with frequency 30 imp/s and strength equal to 3–4 thresholds of the gastrocnemial muscle motor response. Only the stimulations of the central, but not of peripheral, nerve segments were effective, which indicates the reflex nature of the reactions. It has been established that in the process of development, a shift occurs of the predominantly inhibitory reactions to predominantly activating the gastric wall reactions. Similar data were obtained by skin pain stimulation in the region of the tail base. Thus, the age-dependent change of direction of the observed somatoautonomous reactions can be produced by stimulation of different high-threshold somatic afferents. The efferent pathway both of inhibitory and of stimulatory reactions is mediated mainly, but not exclusively, by the gastric branches of the vagus nerve, which is confirmed by consequences of vagotomy and of section of the splanchnic nerve. As a whole, the results of the study can suggest that one of possible pathways of effects of the skeletal muscle contraction on rhythmic activity of the gastrointenstinal tract can be activation of muscle receptors.