Selection of strains of Streptomyces griseus Kr., the producer of a streptothricin antibiotic grisin, using the method of protoplast fusion

The effect of protoplasting on antibiotic activity of the grisin-producing organism was shown. High frequency of Grn- mutants after strain VG307f protoplasting and no capacity in these mutants for reversion to the initial Grn+ phenotype were shown. The reversion frequency was less than 10(-8). Moreover, it was shown that all the Grn- mutants lost their stability (GrnR) to the effect of their own antibiotic. With respect to strain VG212 there was noted a significant increase in the number of both the minus and the plus variants after the protoplast formation and regeneration. Fusing of protoplasts of strains VG307f and VG212 belonging to the divergent lines in selection of S. griseus Kr. yielded the phage stable strain VG7849 with high levels of the antibiotic production and improved technological properties.     

Effect of the gene for bacterial hemoglobin vhb on the effectiveness of the process of Escherichia coli-Streptomyces interspecies conjugation and production of antibiotics in streptomycetes

The bacterial hemoglobin vhb gene was cloned from sliding bacterium Vitreoscilla sp. as an element of the system ensuring survival of this microorganism in an environment that contains insufficient amount of oxygen. The vhb gene was transferred from Escherichia coli to some Streptomyces strains, producers of antibiotics, by the method of intergeneric conjugation using conjugative-integrative plasmid vectors pIH1 and pCH2. The stability of plasmid DNA inheritance was analyzed in the genomes of exconjugants. A positive effect of the vhb gene on processes of conjugation and antibiotic production in a number of examined strains was shown.     

Role of magnetic resonance imaging in the complex radiation diagnosis of hormonally active adrenal tumors

Based on the results of examination of 30 patients with hormonally active adrenal tumors, the authors consider the MRI sympatomatology of their different types and the potentialities of the technique in the complex radiation diagnosis of this pathology. The authors present their assessments of the relative intensity of a signal and the structure of each type of hormone-producing tumors of the glands by using different MRI pulse sequences that may be useful in establishing a presumptive morphological diagnosis. They identify MRI sequences that are of the greatest informative value for the diagnosis of each type of hormonally active adrenal tumors. There is evidence for that MRI is highly effective in detecting all types of hormonally active adrenal tumors and, in the context of their topographic and anatomic diagnosis, has an unquestionable advantage over ultrasonography and X-ray computed tomography in some cases.     

Role of secondary phosphoinositide messengers in storage of Ca2+ ions in retinal rod microsomes

The influence of guanosine-5'-triphosphate and secondary messengers forming in rod outer segment membranes during light-stimulated hydrolysis of phosphoinositides on the ATP-dependent Ca(2+)-uptake in microsomes of the retinal rod inner segment was studied. The water-soluble cytoplasmic components of the retinal rod outer segment were shown to be capable of stimulating the Ca(2+)-pump of endoplasmic reticulum after light illumination. This process is likely to proceed with the participation of 1,2-diacylglycerol localized in microsome membrane.     

Crimean-Congo hemorrhagic fever in Rostov Province: the epidemiological characteristics of an outbreak

The results of the epidemiological analysis of the outbreak of hemorrhagic fever which was caused by Crimean-Congo hemorrhagic fever virus and occurred during the period of July 3-19, 1999, in the Oblivskaya district of Rostov Province are presented. The specific epidemiological features of the outbreak have been determined. The possible versions of the appearance of the focus of infection and the role of Ixodes ticks in the circulation of the infective agent are discussed.     

Human fetal ventricular cardiomyocytes in vitro: proliferation and differentiation

In this study, in the primary cell culture of human fetal cardiomyocytes proliferation of myocytes combines with their differentiation. The cells were isolated enzymatically from 19-22 week-old human fetuses and cultured for 14 days. DNA synthesis, ultrastructure and presence of atrial natriuretic peptide (ANP) were examined. In 7 day-old culture, the myocytes make about 60%, in 14 day-old culture--about 50%. Myocytes synthesize DNA and divide mitotically. After a 24 h incubation with 3H-thymidine in 7 day-old culture 1.8 +/- 0.5% of muscle and 25.2 +/- 11.7% of non-muscle cells are labeled, in 14 day-old culture--2.5 +/- 0.5 and 8.1 +/- 1.7% of cells are labeled, respectively. In 7 and 14 day-old cultures the degree of redifferentiation of contractile apparatus in myocytes varies from scattered actin and myosin filaments surrounded by ribosomes to differentiating myofibrils with distinct sarcomeres and Z-discs. Single electron-dense granules, morphologically similar to secretory atrial granules, display ANP-immunoreactivity. Thus, human fetal ventricular cardiomyocytes in cell culture proliferate, differentiate and synthesize ANP for 14 days; this is indicative of vitality of these cells.     

Postural stability during static strain before and after submaximal aerobic bycycle test in athletes

The aim of study was to investigate static balance control in wrestlers (n = 31) and effects of fatigue on postural regulation in two position: bipedal stance and squat position with open eyes prior to and 2 min after bicycle PWC(170) test. A force platform ("Ritm". Russia) was used to determine static balance control. We found a minimum difference in postural control between wrestlers and controls prior to exercise in bipedal stance. In squat position linear and angular (all p < 0.001) sway velocity of centre of pressure were lower in wrestlers and were negatively correlated to PWC(170) index (r = 0.454 and r = 455, p < 0.001 with linear and angular sway velocities respectively) indicating that 20% dispersion of sway velocities in static strain position may be determined to physical working capacity. After PWC(170) test all parameters of sway were increased in both groups both in bipedal stance (p < 0.01) and squat position (p < 0.001) indicating an important role of muscular fatigue in the decrease of postural stability in both groups. Linear velocity after PWC(170) in bipedal stance increased to an equal extent in both groups but the increases of velocities of sway of centre of pressure in squat position were lower in athletes (ANOVA, p = 0.037 for linear and p = 0.008 for angular sway velocities respectively) and were negatively correlated to an extent of recovery of heart rate after PWC(170) indicating some contribution (6.5-14.2% of dispersion of linear and angular sway velocities) of an recovery rate to maintenance of a high level of postural stability in an static strain position in wrestlers during physical fatigue.     

Immunolocalization of ANP in mast cells of rat and human pericardium

It is known that many heart diseases are accompanied by a significant increase in the level of atrial natriuretic peptide (ANP), a regulator of cardiovascular homeostasis, in the pericardial fluid. Cellular sources of ANP in pericardial cavity remain uncertain. By EM immunocytochemistry, we have examined the presence and localization of ANP in rat and human pericardium. ANP-immunoreactive material was revealed in granules of mast cells (MCs) situated in connective tissue of the pericardium. MCs have an oval form and measure about 6.5 x 12.5 and 9.1 x 13.6 microm in the rat and human pericardium, respectively. Density of MC population makes up about 50 and 10 cells/mm2 in the rat and human pericardium, respectively. Our data suggest possible participation of the pericardial MCs in endocrine function of pericardium and in control of the ANP level in pericardial cavity.