Adenylate cyclase of the causative agent of plague: its purification and properties

Three forms of adenylate cyclase have been detected in Y. pestis: membrane-bound, cytoplasmic and extracellular. Extracellular adenylate cyclase has been purified so as to achieve a homogeneous state, and some of its physicochemical parameters have been investigated. In the process of purification the initial preparation of this enzyme has been subjected to heating at 100 degrees C for 15 minutes, fractionation with ammonium sulfate, and gel filtration on Sephadex G-100. The homogeneity of adenylate cyclase has been confirmed by electrophoresis in 7.5% polyacrylamide gel and precipitation by the plague agglutinating serum. The enzyme has been found to have a molecular weight of 30,000 daltons and to show the optimum activity at pH 7.0-7.2 and at a temperature between 37 and 40 degrees C. Monospecific rabbit serum to the homogeneous preparation of adenylate cyclase has been obtained.     

The effect of the adhesion pili of Yersinia pestis on the physiological activity of the leukocytes and macrophages in experimental animals

The data on the influence of the preparation of Y. pestis adhesion pili on peritoneal macrophages in white mice and guinea pigs are presented. Y. pestis adhesion pili have been found to induce the dose-dependent increase of cell chemiluminescence. They have also been found to induce a number of biochemical changes in target cells: the secretion of myeloperoxidase, an increase in the activity of cAMP-dependent protein kinases.     

Thermostable leukocyte alpha-glycoprotein: immunochemical study and enzyme activity research

Using immunochemical analysis with standard antisera, leukocyte thermostable alpha-glycoprotein (LT alpha G) was shown to be distinct from lactoferrin, lysozyme, and fibronectin. The determination of peroxidase and nonspecific elastase in immune precipitates of LT alpha G gave negative results. Affinity sorption of LT alpha G onto the pus protein component was revealed. Purified LT alpha G had amidolytic activity in response to a substrate for elastase (p-nitroanilide succinyl-trialanyl). The ability of LT alpha G to cause the hydrolysis of substrates for thrombin, kallikrein, plasmin was investigated. The identity of LT alpha G and granulocyte elastase is suggested.     

Diurnal dynamics of red blood indicators after carotid glomectomy in rats]

After bilateral carotid glomectomy the rat resistance to acute hypoxia reduces and phenomena of anemia arise. There appear correlations between resistance to hypoxia and red cell count, hemoglobin and hematocrit. The diurnal fluctuation of rat resistance to acute hypoxia after the glomectomy does not change while hemodynamics undergo marked changes.     

Persistent histone modifications at the BDNF and Cdk‐5 promoters following extinction of nicotine‐seeking in rats

Drugs of addiction lead to a wide range of epigenetic changes at the promoter regions of genes directly implicated in learning and memory processes. We have previously shown that the histone deactylase inhibitor, sodium butyrate (NaB), accelerates the extinction of nicotine‐seeking and provides resistance to relapse. Here, we explore the potential molecular mechanisms underlying this effect. Rats received intravenous nicotine or saline self‐administration, followed by 6 days of extinction training, with each extinction session followed immediately by treatment with NaB or vehicle. On the last day of extinction, rats were killed and the medial ventral prefrontal cortex retained for chromatin immunoprecipitation and quantitative polymerase chain reaction (qPCR). A history of nicotine exposure significantly decreased H3K14 acetylation at the brain‐derived neurotrophic factor (BDNF) exon IV promoter, and this effect was abolished with NaB treatment. In contrast, nicotine self‐administration alone, resulted in a significant decrease in histone methylation at the H3K27me3 and H3K9me2 marks in the promoter regions of BDNF exon IV and cyclin‐dependent kinase 5 (Cdk‐5). Quantitative PCR‐identified changes in several genes associated with NaB treatment that were independent of nicotine exposure; however, an interaction of nicotine history and NaB treatment was detected only in the expression of BDNF IV and BDNF IX. Together these results suggest that nicotine self‐administration leads to a number of epigenetic changes at both the BDNF and Cdk‐5 promoters, and that these changes may contribute to the enhanced extinction of nicotine‐seeking by NaB.     

The Role of GSK-3β Phosphorylation in the Regulation of Slow Myosin Expression in Soleus Muscle during Functional Unloading

Skeletal muscle myosin phenotype (i.e., the predominance in the muscle of a particular isoform or isoforms of myosin heavy chains (MyHC)) determines the properties of muscle, such as contraction speed and fatigue. The aim of this study was to identify the functional relationship between the decrease of the nitric oxide (NO) content, the GSK-3β phosphorylation (leading to the GSK-3β activation), the NFATc1 amount in the muscle nuclei, and the MyHC I(β) isoform expression in the rat soleus muscle under gravitational unloading. Male Wistar rats were divided into five groups: the vivarium control group; the group of animals with a 7-day hind limb suspension receiving placebo; the group of animals with a hind limb suspension receiving a NO donor (L-arginine); the group of animals with a hind limb suspension receiving a NO donor and a NO-synthase inhibitor (L-NAME); and the group of animals with a hind limb suspension receiving a GSK-3β inhibitor. We have shown that a 7-day unloading leads to a NO content decrease in the soleus muscle, and this effect is prevented by L-arginine administration. In addition, administration of L-arginine blocks the GSK-3β phosphorylation decrease, NFATc1 export from the muscle nuclei, and MyHC I(β) expression decrease caused by unloading. The L-arginine effect in each case can be blocked by the NO-synthase inhibitor. Administration of the GSK-3β inhibitor prevents the unloading-induced NFATc1 export from the muscle nuclei and a decrease of the MyHC I(β) expression. The prevention of the MyHC I(β) expression decrease and the NFATc1 export from the nucleus by the selective GSK-3β inhibition confirms the hypothesis on the NO influence on the MyHC I(β) expression and the NFATc1 export from the nucleus via the GSK-3β phosphorylation decrease. Thus, the NO level decrease in the rat soleus muscle in unloading leads to the GSK-3β activation, which in turn, promotes the NFATc1 export from the nucleus and stabilization of the fast myosin phenotype.