Effect of short-term hypoxia and re-oxygenation on mice peritoneal macrophages in vitro

Microfluorimetry of single cells could help to analyze their morphology and function state during changes of gas environment. It is very important to have a possibility of the cell visual control during hypoxia and collection of dynamic fluorimetric data in digital form. The effects of short-term pO2 decrease were studied. For estimating the effects of hypoxia and reoxygenation we used the mice peritoneal macrophages, which are very sensitive to physical, chemical and regulatory stimuli. A special small chamber for fluorimetric measurements during pO2 changes, was developed. The level of active oxygen forms, intracellular pH, and cell membrane instability were investigated during replacement of air by nitrogen or argon (of the basal level decreased to 20% of basic level) and in subsequent reoxygenation. The increase of active oxygen forms was shown during 30 min of hypoxia and their level continued to rise immediately after reoxygenation. A short-term decrease and subsequent increase of pO2 in the medium led to an increase of intracellular pH level. The shifts of measured cell indices were stabilized after 30-40 min of pO2 changes thus suggesting a fast comprehension of countermeasure cell mechanisms. No macrophages with membrane disorders were found despite the rise of the active oxygen forms level during hypoxia and reoxygenation in vitro. There were no significant differences between nitrogen and argon used for replacement of air in the medium. The data obtained suggest a high resistance of macrophages against pO2 changes and an involvement of the antioxidative mechanisms for cell protection especially during reoxygenation period.     

Visual afferentation deficit during diffuse photosensitivity period in nestlings affects morphogenesis in Wulst neurons

Golgi-stained preparations were processed with computerized morphometry to study the effect of the deprivation (eyes covered with nontransparent caps) on the development of neurons in the Wulst (the structure analogous to mammalian visual cortex) of pied flycatcher nestlings. Six-day-old nestlings that have only one form of the visual perception--diffuse photosensitivity--were studied. In the previous paper [Korneeva et al., 1994] in was shown that the Wulst of 6-day-old nestlings consisted of non-differentiated neurons and stellate-like cells at different stages of maturation; the latter group was subdivided into more- and less-mature cells. This work proved that even a 1.5-day-long deprivation (actual duration being counted off from the moment of appearance of the first retinal photoreceptors at the age of 4.5 days) resulted in significant changes in the geometry of stellate-like neurons. The changes in less-mature cells were predominantly destructive (decline of all quantitative indices of a cell, including the significant decrease in the total length of dendrites, maximal radius of the dendritic field and cell branching index), while the changes in more-mature cells were constructive (increase in all quantitative cell indices, including statistically significant increase in the soma section area, total length of dendrites, maximal radius of dendritic field and the number of foci of maximal branching). Different reactions of these cell types to the limitation of visual afferentation may be connected with differences in the afferent inflow to less- and more-mature cells or/and with different maturational stages of these neurons at the onset of deprivation.     

Evaluation of the usefulness of three collections of bacteriophages for typing methicillin-resistant Staphylococcus aureus,isolated in Moscow hospitals

The typing of S. aureus methicillin-resistant strains, isolated in different hospitals of Moscow; was carried out with the use of three collections of phages: the International Set of Phages; the set of phages of the International Center of S. aureus phage typing in London (L); and the experimental collection of phages of the Gamaleya Institute of Epidemiology and Microbiology in Moscow (M). In this study made with the use of both the phages of the International Diagnostic Set and phages L in the standard typing dose of 1 TP about 6% of the cultures under study proved to be sensitive. When the typing dose was increased to 100 TP the phages of the international diagnostic set lyzed 75.5% of the cultures. The typed strains were found to belong to phage types 77 (71.7%), 77/84/85 (19.6%) and 94/96 (6.5%). At a concentration of 100 TP phages L lyzed 83.7% of the cultures, but the dominating phage types could not be determined due to a great variety of phage markers. In contrast to the two preceding collections, the third phage collection M was composed in such a way that in the study of the investigated culture the specificity of its restriction modification was primarily evaluated and only then the presence of antiphage immunity was determined. This latter collection was used in the evaluation of 93.1% of the cultures. By the specificity of their restriction specification system the majority of them were classified with two new groups, heretofore not described. Only this collection M made it possible to differentiate epidemic and sporadic strains and to evaluate the epidemic situation in all 6 hospitals.     

Dynamics of local shifts in oscillations and energy metabolism of the rabbit cerebral cortex during formation of a conditioned defensive reflex

Brain energy metabolism in different functional states or activities of humans and animals is characterized by dynamic changes in the degree of coupling between glycolysis and tissue respiration in different cell compartments (Fox et al., 1988; Fox, 1989; Pellerin et Magistretti, 1994; Prichard et al., 1991; Schur et al., 1999). These processes determine variations in the brain redox state (Siesjo, 1978) that can be potentiometrically recorded with implanted platinum electrodes as the brain tissue redox state potential E (Puppi et Fely, 1983). This potential was recorded in rat brain cortex with four pairs of platinum electrodes implanted into different symmetrical cortical region (one electrode of a pair being located in the cortical layers, another being located epidurally). In the course of defensive conditioning (after 5-15 combination of a bulb light and a weak electrodermal stimulation of a ear), E oscillations (6-10 per minute) appeared. In this period, stimuli combinations produced the generalized E shifts. Later on (with accumulation of stimuli combinations), the episodes of E increase were replaced by the episodes of E decrease. To the 200-400th combinations, E oscillations disappeared, and E shifts became local and stable. The findings suggest that conditioning shifts the balance between the main energy-producing systems in the brain tissue: at the initial stages of conditioning brain functions are predominantly supported by the energy obtained from tissue respiration, while during the realization of defensive conditioning glycolysis is the main source of energy.     

Phenotypic features of Ferroplasma acidiphilum strains Yt and Y-2

Earlier, we described a new family of mesophilic, strictly autotrophic Fe(2+)-oxidizing archaebacteria, Ferroplasmaceae, which belongs to the order Thermoplasmales and includes the genus Ferroplasma and species F. acidiphilum (strain YT) [1]. The present work is concerned with a comparative study of phenotypic characteristics of the type strain YT and a new strain, F. acidiphilum Y-2, isolated from dense pulps produced during oxidation of arsenogold concentrates from the Bakyrchikskoe (Kazakhstan) and Olimpiadinskoe (Krasnoyarsk Krai) ore deposits, respectively. The G + C content of DNA from strains YT and Y-2 comprised 35.1 and 35.2 mol%, respectively; the level of DNA-DNA homology between the strains was 84%. Restriction profiles of chromosomal DNA from both strains exhibited a similarity coefficient of 0.87. Genotypic characteristics of these strains indicate their affiliation to the same species. The cells of both strains are polymorphic and lack cell walls. Strains of F. acidiphilum oxidized ferrous oxide and pyrite as the sole source of energy and fixed carbon dioxide as the sole carbon source. Strains required yeast extract as a growth factor. Optimum pH for cell growth ranged from 1.7 to 1.8; the temperature optima for the growth of strains YT and Y-2 were 34-36 and 40-42 degrees C, respectively. Comparative analysis of total lipids revealed their close similarity in the strains; two glycophospholipids comprised 90% of total lipids: lipid I, beta-D-glucopyranosylcaldarchaetidylglycerol (about 55%), and lipid II, trihexosylcaldarchaetidylglycerol (26%), whose isopranyl chains contained no cyclopentane rings. The carbohydrate fraction of lipid I hydrolysate contained only D-glucose, whereas hydrolysate of lipid II contained both D-glucose and D-galactose in a molar ratio of 2:1. Thus, it was established that the intraspecific phylogenetic divergence within F. acidiphilum is manifested in two the strains by different temperature optima against the background of similarity in other phenotypic properties.     

Formation and dynamics of plasma layers formed on the foil surface under the action of a high-current pulse

Results are presented from studies of the possibility of using a thin metal foil for recyclable vacuum transmission lines with magnetic insulation in a conceptual fusion reactor based on high-voltage high-current electromagnetic generators. Numerical simulations and experiments in the Angara-5-1 facility were carried out to determine both the threshold for the explosion of a foil heated by a current pulse and the parameters of the plasma layer formed at the foil surface. It was found experimentally that an additional plasma current channel forms on the surface of a 120-μm stainless-steel foil at a linear current density of 0.25–0.5 MA/cm, which corresponds to a magnetic field of 0.3–0.6 MG. For the same conditions, one-dimensional computer simulations of the foil heating were performed in an MHD model by using a wide-range semiempirical equation of state for stainless steel. The calculated threshold for plasma generation on the foil surface is compared with the experimental data. The main parameters of the plasma layer are also calculated at linear current densities of 2–10 MA/cm, which far exceed the threshold current density. The plasma layer parameters as functions of the linear current density are determined for the case of an iron foil.     

Neuronal reactions in the dorsolateral pontine area during the immobility response in rats

Reactions of 277 neurones located in the brain pons dorsolateral portion were analised in staying awake and narcotized rats during immobility reflex, induced by the skin constriction on the neck dorsal surface. Got excited: fast adaptive tactile neurons (n = 32), interneurons (n = 42), and cells forming monosynaptic inputs to the parts of medulla oblongata, which inhibit the movements (n = 10). Were inhibited: somatosensory (n = 42), nociceptive (n = 24) and nonidentificated (n = 14) neurons. In some neurons charge characteristics were stable or slightly modified, namely: respiratory neurons (n = 16), cell group, having stable background firing (n = 72) and stimulating antidromically spontaneously silent ponto-medullar neurons (n = 22).     

Effects of delta-sleep-inducing peptide during ischemic injury of the rat brain

An anti-ischemic effect of the delta-sleep-inducing peptide (DSIP) was found in rats. The DSIP effect was more obvious than that of the MK-801. The data obtained is discussed considering a possible use of the DSIP for brain stroke prophylaxis.     

Gas exchange and oxygen transport during long term hypothermia following a hypothermal apnea in rats

The data obtained show that, at the initial stages of hypothermia, a decrease in the oxygen consumption and carbon dioxide production, cardiac output, and heart rate occurred in accordance with the temperature coefficient. Suppression of the tissue gas exchange was unrelated to disorders in the lung gas exchange but determined rather by a progressing weakening of heart activity, decrease in the cardiac output, and increase in the general vascular peripheral resistance.