Borrelia species new to Russia--possible causative agents of ixodid tick-borne borreliosis]

18 Borrelia isolates, obtained in 1996-1997 from adult Ixodes ricinus collected from plants in the environs of Stavropol', were identified with the use of the polymerase chain reaction and the analysis of the polymorphism of the length of restriction fragments. Among them, in addition to B. garinii and B. afzelii, widely spread in Eurasia, 2 recently described species, B. valaisiana and B. lusitaniae, were found in Russia for the first time. Their possible spread and their importance in infectious pathology are described.     

Ultrastructure of cyanobacterium <Emphasis Type="Italic">Nostoc</Emphasis> sp. f. <Emphasis Type="Italic">Blasia</Emphasis> cell forms in persisting populations

Cell clusters formed in persistent populations of Nostoc sp. f. Blasia, a cyanobacterium capable of cell differentiation, under prolonged storage in the dark at low temperatures were studied for the first time. Cell reorganization was observed, including changes in the ultrastructure of thylakoids, the cell wall peptidoglycan layer, and carboxysomes. Subcellular structures involved in intercellular communication within the clusters were revealed (structures similar to microplasmodesms and contact pores, secretory vesicles, etc.) Persistence of cyanobacterial populations was concluded to result from formation not only of specialized dormant cells (akinetes), but also L-forms, as well as from the modification changes of the clustered vegetative cells. A cluster containing the vegetative cells and L-like forms within a common intercellular matrix is considered a structural unit at the supracellular level, which is responsible for survival of cyanobacterial populations when mass akinete formation does not occur.     

Steady potential and extracellular potassium shifts in the rat neocortex during sustained low-frequency electrical stimulation of the cortical surface

Cyclic excitation arising in the rat neocortex under the influence of low-frequency electrical stimulation was studied. The duration of the excitation cycles and intervals between them depended on the stimulation parameters. In the period of excitation the negative shift of steady potential reached 4–5 mV, and the extracellular potassium ion concentration, measured with the aid of potassium-selective microelectrodes, rose to 8–10 mM. The process of periodic excitation was not self-maintained and it ceased after the current was stopped. As a result of small doses of pentobarbital (10–20 mg/kg) the response thresholds rose, and intervals between excitation phases were increased by several times. Pentobarbital in a dose of 30–40 mg/kg completely abolished cyclic excitation for 2–3 h. Correlation between shifts of steady potential and extracellular potassium concentration differed in anesthetized and unanesthetized animals.     

Characteristics of the role of the hydroxyl group in serotonin in the pharmacological and antiradiation effect of serotonin

It was shown that omega-hydroxylation of O-alkyl serotonin derivatives can slightly improve the radioprotective and pharmacological properties of these substances but fails to remove completely the unfavourable action of O-alkylation of serotonin. There is a close correlation between the radioprotective effect of 5-oxyalkoxytryptamines and their action on blood supply of mouse spleen. The introduction of the alkoxy-group or the tertiary amino-group into omega-position removes the radioprotective effect of 5-alkoxytryptamines.