Viral hepatitis in different population groups of Republic of Sakha (Iakutia)

A survey for the presence of markers of viral hepatitis B, delta, C and E among different groups of the population of the arctic and agricultural zones of the Republic of Sakha (Yakutia), as well as in Yakutsk, was carried out. The survey revealed that viral hepatitides with the parenteral mechanism of the transmission of infective agents were widely spread among the population. In the arctic zone HBsAg was detected in persons aged 20 years and older in 10.8-17.1% of cases. On the average, in the arctic zone antibodies to virus delta were detected in 2.4% of cases. In different regions of the agricultural zone the detection rate of HBsAg was also high (10.4-23.8%). In the Namsk and Vilyui regions delta infection was registered among adolescents (15-19 years of age) in 8.7 and 22.4% of cases respectively. In the Mountainous region anti-delta antibodies were detected among persons aged 20 years and older in 31% of cases. The survey showed the presence of considerable differences in the detection rate of the markers of hepatitis B, depending on the ethnic origin of the examined patients. Similar tendencies were found to exist with respect to delta infection.     

The effect of alcoholization on the behavioral reactions of rats in an 8-arm radial maze

The influence of 20% alcohol consumption on training of low-active rats in 8-arm radial maze was studied. One group of animals was trained before and the other group after the alcoholization. All the animals acquired the conditioned reaction in the radial maze. However, the behavioral difference between the groups consisted in spatially-motor asymmetry. The rats trained before the alcohol consumption had less stereotyped behavior and more distinctly preferred to enter the maze arms at the angle of 45 degrees than the animals trained after the alcohol consumption. After the alcohol consumption, rats more frequently refused from behavioral task performance in comparison with the animals trained after the alcoholization. The influence of alcohol consumption of learning and memory in low-active rats is discussed.     

Two groups control light-induced schiff base deprotonation and the proton affinity of asp(85) in the Arg(82)His mutant of bacteriorhodopsin

Arg(82) is one of the four buried charged residues in the retinal binding pocket of bacteriorhodopsin (bR). Previous studies show that Arg(82) controls the pK(a)s of Asp(85) and the proton release group and is essential for fast light-induced proton release. To further investigate the role of Arg(82) in light-induced proton pumping, we replaced Arg(82) with histidine and studied the resulting pigment and its photochemical properties. The main pK(a) of the purple-to-blue transition (pK(a) of Asp(85)) is unusually low in R82H: 1.0 versus 2.6 in wild type (WT). At pH 3, the pigment is purple and shows light and dark adaptation, but almost no light-induced Schiff base deprotonation (formation of the M intermediate) is observed. As the pH is increased from 3 to 7 the M yield increases with pK(a) 4.5 to a value approximately 40% of that in the WT. A transition with a similar pK(a) is observed in the pH dependence of the rate constant of dark adaptation, k(da). These data can be explained, assuming that some group deprotonates with pK(a) 4.5, causing an increase in the pK(a) of Asp(85) and thus affecting k(da) and the yield of M. As the pH is increased from 7 to 10.5 there is a further 2.5-fold increase in the yield of M and a decrease in its rise time from 200 &mgr;s to 75 &mgr;s with pK(a) 9. 4. The chromophore absorption band undergoes a 4-nm red shift with a similar pK(a). We assume that at high pH, the proton release group deprotonates in the unphotolyzed pigment, causing a transformation of the pigment into a red-shifted "alkaline" form which has a faster rate of light-induced Schiff base deprotonation. The pH dependence of proton release shows that coupling between Asp(85) and the proton release group is weakened in R82H. The pK(a) of the proton release group in M is 7.2 (versus 5.8 in the WT). At pH < 7, most of the proton release occurs during O --> bR transition with tau approximately 45 ms. This transition is slowed in R82H, indicating that Arg(82) is important for the proton transfer from Asp(85) to the proton release group. A model describing the interaction of Asp(85) with two ionizable residues is proposed to describe the pH dependence of light-induced Schiff base deprotonation and proton release.     

Participation of plasma membrane proteins in the formation of tight junction by cultured epithelial cells

Measurements of the transepithelial electrical resistance correlated with freeze-fracture observations have been used to study the process of tight junction formation under various experimental conditions in monolayers of the canine kidney epithelial cell line MDCK. Cells derived from previously confluent cultures and plated immediately after trypsin- EDTA dissociation develop a resistance that reaches its maximum value of several hundred ohms-cm(2) after approximately 24 h and falls to a steady-state value of 80-150 ohms- cm(2) by 48 h. The rise in resistance and the development of tight junctions can be completely and reversibly prevented by the addition of 10 μg/ml cycloheximide at the time of plating, but not when this inhibitor is added more than 10 h after planting. Thus tight junction formation consists of separable synthetic and assembly phases. These two phases can also be dissociated and the requirement for protein synthesis after plating eliminated if, following trypsinization, the cells are maintained in spinner culture for 24 h before plating. The requirement for protein synthesis is restored, however, if cells maintained in spinner culture are treated with trypsin before plating. Actinomycin D prevents development of resistance only in monolayers formed from cells derived from sparse rather than confluent cultures, but new mRNA synthesis is not required if cells obtained from sparse cultures are maintained for 24 h in spinner culture before plating. Once a steady-state resistance has been reached, its maintenance does not require either mRNA or protein synthesis; in fact, inhibition of protein synthesis causes a rise in the resistance over a 30-h period. Following treatments that disrupt the junctions in steady- state monolayers recovery of resistance also does not require protein synthesis. These observations suggest that proteins are involved in tight junction formation. Such proteins, which do not turn over rapidly under steady-state conditions, are destroyed by trypsinization and can be resynthesized in the absence of stable cell-cell or cell-substratum contact. Messenger RNA coding for proteins involved in tight junction formation is stable except when cells are sparsely plated, and can also be synthesized without intercellular contacts or cell-substratum attachment.     

Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig

Isometric tension and isotonic shortening were measured at constant levels of calcium activation of varying magnitude in mechanically disrupted EGTA-treated ventricular bundles from guinea pigs. The results were as follows: (a) The effect of creatine phosphate (CP) on peak tension and rate of shortening saturated at a CP concentration more than 10 mM; below that level tension was increased and shortening velocity decreased. We interpreted this to mean that CP above 10 mM was sufficient to buffer MgATP(2-) intracellularly. (b) The activated bundles exhibited an exponential stress-strain relationship and the series elastic properties did not vary appreciably with degree of activation or creatine phosphate level. (c) At a muscle length 20 percent beyond just taut, peak tension increased with Ca(2+) concentration over the range slightly below 10(-6) to slightly above 10(-4)M. (d) By releasing the muscle length-active tension curves were constructed. Force declined to 20 percent peak tension with a decrease in muscle length (after the recoil) of only 11 percent at 10(-4)M Ca(2+) and 6 percent at 4x10(-6)M Ca(2+). (e) The rate of shortening after a release was greater at lower loads. At identical loads (relative to maximum force at a given Ca(2+) level), velocity at a given time after the release was less at lower Ca(2+) concentrations; at 10 M(-5), velocity was 72 percent of that at 10(-4)M, and at 4x10(-6)M, active shortening was usually delayed and was 40 percent of the velocity at 10(-4) M. Thus, under the conditions of these experiments, both velocity and peak tension depend on the level of Ca(2+) activation over a similar range of Ca(2+) concentration.     

The phylogenetic position of Rhopalura ophiocomae (Orthonectida) based on 18S ribosomal DNA sequence analysis

The Orthonectida is a small, poorly known phylum of parasites of marine invertebrates. Their phylogenetic placement is obscure; they have been considered to be multicellular protozoans, primitive animals at a "mesozoan" grade of organization, or secondarily simplified flatworm- like organisms. The best known species in the phylum, Rhopalura ophiocomae, was collected on San Juan Island, Wash. and a complete 18S rDNA sequence was obtained. Using the models of minimum evolution and parsimony, phylogenetic analyses were undertaken and the results lend support to the following hypotheses about orthonectids: (1) orthonectids are more closely aligned with triploblastic metazoan taxa than with the protist or diploblastic metazoan taxa considered in this analysis; (2) orthonectids are not derived members of the phylum Platyhelminthes; and (3) orthonectids and rhombozoans are not each other's closest relatives, thus casting further doubt on the validity of the phylum Mesozoa previously used to encompass both groups.      

Alpha 1-adrenergic receptors in the liver parenchyma of children: the changes in cirrhosis]

In the present study alpha 1-adrenergic receptors have been investigated in liver parenchyma, obtained at the resection of prehepatic portal hypertension children without parenchymal affection (control group, n = 7) and the resection of children in parenchymal affection (group of cirrhosis, n = 8). It has been shown, that the binding of alpha 1-adrenergic antagonist 3H-prasozin (3H-PRZ) in liver parenchyma membranes of both control and cirrhosis groups is saturable and shows a high affinity. The Scatchard analysis of the binding data indicated that the binding site is characterized by Kd and Bmax of 0.6 +/- 0.12 nM, 92.8 +/- 8.0 fmol/mg, respectively, for the control group; and 1.5 +/- 0.4 nM, 254.1 +/- 28.4 fmol/mg, respectively, for the group of cirrhosis; (mean +/- SEM). It has been found that the number of binding sites of 3H-PRZ significantly increases in cirrhosis liver parenchyma in comparison with the control group. The results obtained suggest that alpha 1-adrenergic receptors play an important role in cirrhosis formation in children, showing liver parenchyma affection severity and its regenerative properties.