Effect of irradiation on proteins and phagocytic activity of rat blood leukocytes

The method of chromatography on DEAE-cellulose was used to study the effect of radiation (180.6 mC/kg) on the physicochemical properties of rat leukocyte proteins. The qualitative changes were noted in the protein spectrum of leukocytes which were indicative of the substantial changes in the cell proteins. A fraction was isolated which caused a 44% inhibition of the phagocytic activity of intact leukocytes in vitro.     

Viscoelastic characteristics of protein solutions and micromechanics of their motion in porous carriers

The interactions of model proteins with the templates of porous carriers in biosensors were analyzed in terms of events occurring during the molecular contact of biopolymers with a solid. The viscoelastic properties of casein and albumin at small widths of the layer of the solution applied to the crystal were estimated using the dynamic method of piezoqartz resonator. The experimental data on the viscoelastic characteristics of protein solutions of different concentrations were compared with the characteristics of their tangential motion in porous carriers from cellulose nitrate. It was found that the parameters of dynamic viscosity correlate with the time of motion of protein solution in a porous polymeric carrier.     

Interaction of glutamate- and adenosine-induced decrease of acetylcholine quantal release at frog neuromuscular junction

In a frog neuromuscular preparation of m. sartorius, glutamate had a reversible dose-dependent inhibitory effect on both spontaneous miniature endplate potentials (MEPP) and nerve stimulation-evoked endplate potentials (EPP). The effect of glutamate on MEPP and EPP is caused by the activation of metabotropic glutamate receptors, as it was eliminated by MCPG, an inhibitor of group I metabotropic glutamate receptors. The depression of evoked EPP, but not MEPP frequency was removed by inhibiting the NO production in the muscle by L-NAME and by ODQ that inhibits the soluble NO-sensitive guanylyl cyclase. The glutamate-induced depression of the frequency of spontaneous MEPP is apparently not caused by the stimulation of the NO cascade. The particular glutamate-stimulated NO cascade affecting the evoked EPP can be down-regulated also by adenosine receptors, as the glutamate and adenosine actions are not additive and application of adenosine partially prevents the further decrease of quantal content by glutamate. On the other hand, there is no obvious interaction between the glutamate-mediated inhibition of EPP and inhibitory pathways triggered by carbacholine and ATP. The effect of glutamate on the evoked EPP release might be due to NO-mediated modulation (phosphorylation) of the voltage-dependent Ca2+ channels at the presynaptic release zone that are necessary for evoked quantal release and open during EPP production.     

Dynamics of antibiotic resistance of Staphylococcus aureus isolated from chronic osteomyelitis patients

The level of antibiotic resistance of 365 S.aureus strains, isolated from chronic osteomyelitis patients in 1990 and 2000, was determined. As revealed in this study, over 10 years the isolation rate of strains adapted to the antimicrobial action of all tested preparations increased in some degree. The increase of the resistance level to aminoglycosides was most significant. The proportion of polyresistant strains was 9.1% in 1990 and 30.5% in 2000. The isolation rate of methicillin-resistant S. aureus (MRSA) did not increase during these 10 years, but the range of preparations suitable for the treatment of MRSA-infected patients was shown to become essentially narrower. These data confirm the view on the possibility of further decrease in the effectiveness of the conservative treatment of chronic osteomyelitis due to the rapid growth of the antibiotic resistance of S. aureus.     

Mitochondrial DNA and bindin gene sequence evolution among allopatric species of the sea urchin genus Arbacia

Sea urchins of the genus Arbacia (order Stirodonta) have discontinuous allopatric distributions ranging over thousands of kilometers. Mitochondrial DNA (mtDNA) sequences were used to reconstruct phylogenetic relationships of four Arbacia species and their geographic populations. There is little evidence of genetic structuring of populations within species, except in two cases at range extremes. The mtDNA sequence differentiation between species suggests that divergence occurred about 4-9 MYA. Gene sequences encoding the sperm protein bindin and its intron were obtained and compared with the mtDNA phylogeny. Sea urchins among the well-studied echinoid order Camarodonta, with degrees of mtDNA divergence similar to those of Arbacia species, are known to have remarkable variation in bindin. However, in Arbacia, little variation in deduced amino acid sequences of bindin was found, indicating that purifying selection acts on the protein. In contrast, bindin intron sequences showed much differentiation, including numerous insertion/deletions. Fertilization experiments performed between a divergent pair of Arbacia species from the Atlantic and Pacific Oceans revealed no evidence of blocks to gamete recognition. In Arbacia, fertilization specificities may have evolved relatively slowly as a result of extensive gene flow within species, greater functional constraint on the bindin polypeptide, or reduced selective pressure for species recognition in singly occurring species.      

Females of the sea urchin Strongylocentrotus purpuratus differ in the structures of their egg jelly sulfated fucans

The egg jelly coats of sea urchins contain sulfated fucans which bind to a sperm surface receptor glycoprotein to initiate the signal transduction events resulting in the sperm acrosome reaction. The acrosome reaction is an ion channel regulated exocytosis which is an obligatory event for sperm binding to, and fusion with, the egg. Approximately 90% of individual females of the sea urchin Strongylocentrotus purpuratus spawned eggs having only one of two possible sulfated fucan electrophoretic isotypes, a slow migrating (sulfated fucan I), or a fast migrating (sulfated fucan II) isotype. The remaining 10% of females spawned eggs having both sulfated fucan isotypes. The two sulfated fucan isotypes were purified from egg jelly coats and their structures determined by NMR spectroscopy and methylation analysis. Both sulfated fucans are linear polysaccharides composed of 1-->3-linked alpha-L-fucopyranosyl units. Sulfated fucan I is entirely sulfated at the O -2 position but with a heterogeneous sulfation pattern at O -4 position. Sulfated fucan II is composed of a regular repeating sequence of 3 residues, as follows: [3-alpha-L-Fuc p - 2,4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)- 1]n. Both purified sulfated fucans have approximately equal potency in inducing the sperm acrosome reaction. The significance of two structurally different sulfated fucans in the egg jelly coat of this species could relate to the finding that the sperm receptor protein which binds sulfated fucan contains two carbohydrate recognition modules of the C-type lectin variety which differ by 50% in their primary structure.      

Reactivity of the hypothalamo-hypophyseal-adrenal complex of adult rats after the administration of hydrocortisone to their mothers during pregnancy

The effect of single and repeated injection of hydrocortisone to rats during the last week of pregnancy on the reactivity of the hypothalamic-hypophysial-suprarenal complex of their adult descendants was studied. The reaction of hypophysial-suprarenal system of the adult rats to an amotional stressor and injection of norepinephrine in the brain lateral vesicle was shown to decrease. Under similar experimental conditions the reaction to ether and combined stressors, as well as to intraventricular injection of 5-HT or carbocholine resembled that in the control animals. It is suggested that hydrocortisone injected during the prenatal period exerts, to a certain extent, the selective influence on the central adrenergic mechanisms the changes in which may serve as one of the causes of decrease in emotional reactivity of adult animals.     

Association between Tph2 gene polymorphism, brain tryptophan hydroxylase activity and aggressiveness in mouse strains

The brain neurotransmitter serotonin is involved in the regulation of aggressive behavior. The main factor determining the brain serotonin level is the activity of the rate-limiting enzyme in the biosynthesis of the neurotransmitter--tryptophan hydroxylase isoform (TPH) 2 encoded by the Tph2 gene. Recently the C1473G single-nucleotide polymorphism in the Tph2 gene was reported. Here we study the C1473G polymorphism in 10 inbred mouse strains (C57BL/6J, AKR/J, DD/He, C3H/HeJ, YT/Y, BALB/cJLac, CC57BR/Mv and A/He) and demonstrate the association of the polymorphism with brain TPH activity and intermale aggressiveness. TPH activity in the midbrain of mice homozygous for the 1473C allele was higher than that in mice carrying 1473G alleles. A close association of the 1473C allele with increased number of attacks towards another male was found. The results support a link between the C1473G polymorphism in Tph2 gene, tryptophan hydroxylase activity and intensity of intermale aggression.     

Solid cancer incidence among the Chernobyl emergency workers residing in Russia: estimation of radiation risks

An analysis is presented of solid cancer incidence during 11 years of follow-up (1991–2001) of Chernobyl emergency workers residing in Russia. The analysis is based on data from the cohort of male emergency workers from 6 regions in Russia including 55,718 persons with documented external radiation doses in the range of 0.001–0.3 Gy who worked within the 30 -km zone in 1986–1987. The mean age at exposure for these persons was 34.8 years and the mean external radiation dose 0.13 Gy. In the cohort 1,370 cases of solid cancer were diagnosed and 3 follow-up periods were considered: 1991–1995, 1996–2001 and 1991–2001. The second follow-up period was chosen to allow for a minimum latency period of 10 years being characteristic of solid cancers. For risk assessment two control groups have been introduced, the first external one representing incidence rates for corresponding ages in Russia in general, the second internal one consisting of emergency workers. The risk estimates were based on spontaneous incidence rates of solid cancer. The estimated standardized incidence ratio (SIR) is in good agreement (95% CI) with that of the control. The values of excess relative risk per unit dose (ERR/Gy) for solid malignant neoplasms have been estimated to be 0.33 (95% CI: –0.39, 1.22) (internal control) for the follow-up period 1991–2001 and 0.19 (95% CI: –0.66, 1.27) for 1996–2001.