Preliminary study of the effects of caspase inhibitors on vasospasm in dog penetrating arteries

This preliminary study was undertaken to explore the possible protective effect of caspase inhibitors Z-VDVAD-FMK and Z-DEVD-FMK in apoptosis and vasospasm in penetrating arteries during cerebral vasospasm. Experimental subarachnoid hemorrhage (SAH) was induced in 16 dogs by an intracisternal injection of autologous arterial blood (0.4 ml/kg) on Day 0 and Day 2. The dogs were then randomly divided into four groups: control-SAH, vehicle-control, and two treatment groups. In the treatment groups, caspase inhibitors (10 microM) were intracisternally injected each day beginning on Day 2 until Day 6. Effects of the inhibitors were analyzed utilizing angiography, the clinical status of the dogs (activity, appetite, and neurological deficits), and transmission electron microscopy of the penetrating arteries. All the dogs were sacrificed on Day 7. In control-SAH and vehicle-control groups, severe angiographic vasospasm, poor clinical status, and penetrating vasospasm were registered in all the dogs. In the treatment groups, all the dogs developed angiographic vasospasm and vasospasm in penetrating arteries, however, with benign clinical statues. The occurrence of apoptosis in endothelial cells was reduced by caspase-2 but not by caspase-3 inhibitor. Caspase inhibitors failed to prevent vasospasm either in major or in penetrating arteries. The improvement of clinical scores by the caspase inhibitors may be related to their protection of the endothelial cells. Further investigations using more rigorous clinical scoring system and quantitative information on the degree of apoptosis in the vessels, as well as in the brain parenchyma are recommended.     

The structure of O-specific polysaccharide of Yersinia frederiksenii serotype O:16,29 lipopolysaccharide

A branched chain octose, 3,6-dideoxy-4-C-(L-glycero-1'-hydroxyethyl)-D-xylo- hexose, was isolated from the lipopolysaccharide of Yersinia frederiksenii, serovar O: 16.29 and identified as yersiniose A from Y. pseudotuberculosis, serovar VI. Mild hydrolysis of the lipopolysaccharide with acetic acid afforded a rhamnan. Structural features of the trisaccharide repeating unit were elucidated on the basic of 13C NMR spectral data, methylation studies and periodate oxidation. Using these data as well as data on sugar composition and methylation studies of the lipopolysaccharide, the following structural pattern of the repeating unit of O-specific polysaccharide was proposed: (formula; see text)     

Invariable biomass-specific primary production of taxonomically discrete picoeukaryote groups across the Atlantic Ocean

Oceanic photosynthetic picoeukaryotes (< 3 μm) are responsible for > 40% of total primary production at low latitudes such as the North-Eastern tropical Atlantic. In the world ocean, warmed by climate changes, the expected gradual shift towards smaller primary producers could render the role of photosynthetic picoeukaryotes even more important than they are today. Little is still known, however, about how the taxonomic composition of this highly diverse group affects primary production at the basin scale. Here, we combined flow cytometric cell sorting, NaH1?CO? radiotracer incubations and class-specific fluorescence in situ hybridization (FISH) probes to determine cell- and biomass-specific inorganic carbon fixation rates and taxonomic composition of two major photosynthetic picoeukaryote groups on a ～7500-km-long latitudinal transect across the Atlantic Ocean (Atlantic Meridional Transect, AMT19). We show that even though larger cells have, on average, cell-specific CO? uptake rates ～5 times higher than the smaller ones, the average biomass-specific uptake is statistically similar for both groups. On the other hand, even at a high taxonomic level, i.e. class, the contributions to both groups by Prymnesiophyceae, Chrysophyceae and Pelagophyceae are significantly different (P < 0.001 in all cases). We therefore conclude that these group's carbon fixation rates are independent of the taxonomic composition of photosynthetic picoeukaryotes across the Atlantic Ocean. Because the above applies across different oceanic regions the diversity changes seem to be a secondary factor determining primary production.     

Flow cytometric enumeration of DNA-stained oceanic planktonic protists

The aim of this study was to test the practicality of enumeratingfixed, DNA-stained heterotrophic protists (H) and phototrophicprotists (P) in contrasting regions of the Atlantic Ocean. Oceanicprotists were enumerated using a standard flow cytometer (FACSort,BD) at an enhanced flow rate of up to 1.0 mL min^–1 toincrease numbers of counted cells. The enumeration error ofprotists decreased hyperbolically from 30–40 to < 5%corresponding to the number (<100 to > 2000) of enumeratedcells. H and P were discriminated using the extra red chlorophyll-derivedplastidic fluorescence of the latter. The relationship betweencounts of stained and unstained fixed and unfixed P was statisticallyclose to 1:1, confirming the accuracy of stained protist countingby flow cytometry and adequate discrimination of P from H cells.The estimated average abundance of H in the surface mixed layerof the southern and northern oligotrophic gyres was remarkablysimilar, with 400 ± 140 and 450 ± 60 cells mL^–1,respectively, adding further evidence to the suggestion thatthese regions are in steady state. In agreement with earlierstudies in more productive aquatic environments, a significantcorrelation (correlation coefficient 0.84, P < 0.0001) wasfound between the H and the total bacterioplankton numbers,with an average ratio of 1300 prokaryotes to 1 H cell, suggestinga relatively constant trophic interaction between these twogroups. This study demonstrates that flow cytometric enumerationof protists is 100 times faster compared with microscopy and,thus, represents a major improvement for quantifying protistsin ocean waters, including oligotrophic gyres.     

Distribution and activity of microorganisms in the deep repository for liquid radioactive waste at the Siberian Chemical Combine

The physicochemical conditions, composition of microbial communities, and the rates of anaerobic processes in the deep sandy horizons used as a repository for liquid radioactive wastes (LRW) at the Siberian Chemical Combine (Seversk, Tomsk oblast), were studied. Formation waters from the observation wells drilled into the production horizons of the radioactive waste disposal site were found to be inhabited by microorganisms of different physiological groups, including aerobic organotrophs, anaerobic fermentative, denitrifying, sulfate-reducing, and methanogenic bacteria. The density of microbial population, as determined by cultural methods, was low and usually did not exceed 10(4) cells/ml. Enrichment cultures of microorganisms producing gases (hydrogen, methane, carbon dioxide, and hydrogen sulfide) and capable of participation in the precipitation of metal sulfides were obtained from the waters of production horizons. The contemporary processes of sulfate reduction and methanogenesis were assayed; the rates of these terminal processes of organic matter destruction were found to be low. The denitrifying bacteria from the underground repository were capable of reducing the nitrates contained in the wastes, provided sources of energy and biogenic elements were available. Biosorption of radionuclides by the biomass of aerobic bacteria isolated from groundwater was demonstrated. The results obtained give us insight into the functional structure of the microbial community inhabiting the waters of repository production horizons. This study indicates that the numbers and activity of microbial cells are low both inside and outside the zone of radioactive waste dispersion, in spite of the long period of waste discharge.     

Comparison of Cellular and Biomass Specific Activities of Dominant Bacterioplankton Groups in Stratified Waters of the Celtic Sea

A flow-sorting technique was developed to determine unperturbed metabolic activities of phylogenetically characterized bacterioplankton groups with incorporation rates of [³⁵S]methionine tracer. According to fluorescence in situ hybridization with rRNA targeted oligonucleotide probes, a clade of α-proteobacteria, related to Roseobacter spp., and a Cytophaga-Flavobacterium cluster dominated the different groups. Cytometric characterization revealed both these groups to have high DNA (HNA) content, while the α-proteobacteria exhibited high light scatter (hs) and the Cytophaga-Flavobacterium cluster exhibited low light scatter (ls). A third abundant group with low DNA (LNA) content contained cells from a SAR86 cluster of γ-proteobacteria. Cellular specific activities of the HNA-hs group were 4- and 1.7-fold higher than the activities in the HNA-ls and LNA groups, respectively. However, the higher cellular protein synthesis by the HNA-hs could simply be explained by their maintenance of a larger cellular protein biomass. Similar biomass specific activities of the different groups strongly support the main assumption that underlies the determination of bacterial production: different bacteria in a complex community incorporate amino acids at a rate proportional to their protein synthesis. The fact that the highest growth-specific rates were determined for the smallest cells of the LNA group can explain the dominance of this group in nutrient-limited waters. The metabolic activities of the three groups accounted for almost the total bacterioplankton activity, indicating their key biogeochemical role in the planktonic ecosystem of the Celtic Sea.     

Comparison of linezolid and vancomycin in nosocomial pneumonia: results of the multicenter double-blind study]

The results of multicenter, randomized, double-blind comparative study of linezolid and vancomycin efficacy, safety and tolerability in the treatment of nosocomial pneumonia are presented. The trial was performed on 69 patients. Clinical efficacy of linezolid was 83 per cent, of vancomycin--79 per cent. Bacteriological effect (pathogen eradication) was 83 per cent for linezolid group and 86 per cent for vancomycin group. During the study good clinical tolerability of linezolid was demonstrated along with lower side effects incidence and shortened recovery period when compared to vancomycin.     

Assimilation efficiency of Vibrio bacterial protein biomass by the flagellate Pteridomonas : assessment using flow cytometric sorting

A flow cytometric sorting technique for direct determination of bacterial biomass assimilation by phagotrophic flagellates was developed and tested in laboratory culture experiments. Living Vibrio bacteria were quantitatively pulse-chase labelled with [(35)S]methionine tracer and fed to Pteridomonas flagellates. Flow sorting revealed that the isotopically labelled material is in either bacterial prey or flagellate predators and the egested bacterial debris contained negligible amounts of tracer. These experimental results confirm an earlier hypothesis that flagellates release metabolised bacterial proteins primarily in a dissolved form. The assimilation efficiency of the Vibrio protein biomass by Pteridomonas was low, only about 20%, independently of the amount of consumed bacterial biomass, confirming our earlier indirect estimates. Additionally, against expectations that cells decrease their metabolic activity whilst preparing for and engaged in division, we found that the precursor uptake rates by flow sorted bacterial cells at the S+G(2) cell cycle stages were constantly 1.5 times higher than those of cells at the G(1) stage.