Sporadic increases of radioactive aerosols as a possible reason for heavy nuclides enhancements recorded with the en-detectors.

Some unexpected sporadic increases of an environmental radioactive background have been recorded at mountain level at Baksan Neutrino Observatory (BNO, 1700 m above sea level) using electron-neutron detectors (en-detectors), which could be explained by radioactive aerosol enhancements. The large area inorganic scintillator en-detectors developed for cosmic ray study are continuously monitoring environmental thermal neutron fluxes at various geophysical conditions. Application of the pulse shape discrimination method allows us to select and separately measure both thermal neutrons and radioactive beta-decay nuclides being products of radon decays in air (mostly Rn-222 and Rn-220). There are two en-detector setups running now at BNO, one deep underground while another one at surface. Both installations had recorded some strange sporadic increases of radioactive nuclides in air. In this paper, we present results and the most probable explanation of the significant increases joint by radioactive aerosols production but caused by different reasons: Baksan river floods or nearby underground experiment with powerful Cr-51 radioactive source.

Microbiological and epidemiological investigation of cholera epidemic in Ukraine during 1994 and 1995.

The Ukraine cholera epidemic of 1994 and 1995 was caused by Vibrio cholerae O1, serotype Ogawa, biotype El Tor. This epidemic was centred in the area around Respublika Krim (Crimea) and Mykolajiv, and spread to include parts of southern Ukraine. Cases of cholera occurred between September and November of 1994 and between June and October of 1995. The 32 fatalities among 1370 recorded cases (case fatality ratio, 2.3%) occurred throughout the course of the epidemic. V. cholerae from patients with cholera produced cholera toxin and were resistant to multiple antibiotics, though no resistance plasmids were found. Conjugation experiments suggested that resistance to multiple antibiotics may be present on a self-transmissible genetic element. Environmental sources of V. cholerae O1 El Tor included sewage, sea and surface water, and fresh water and marine fish. All but one of the environmental V. cholerae isolated during the epidemic were very similar to selected isolates from patients at the same time, supporting the role of these environmental sources in the spread of disease.

[The cellular fatty acid composition of bacteria in the family Vibrionaceae]. / Sostav kletochnykh zhirnykh kislot bakterii semeistva Vibrionaceae.

It is shown that strains of Vibrio cholerae of serovar O1, biovar eltor, subtype Ogawa, museum strains V. cholerae of serovar O1 and NAG-vibrios (isolated from various sources: sea, river and sewage water, canal water and people) possess identical composition of cell fatty acids with prevailing hexadecenoic, hexadecanoic and octadecenoic acids. Being identical, fatty acid profiles of V. parahaemolyticus and V. alginolyticus, are close to that of V. cholerae differing from the latter mainly by the higher content of dodecanoic acid. Similarity of Aeromonas sp. and Vibrio strains in the fatty acid composition proves phylogenetic relation-ship of these bacteria. Fatty acid composition of Plesiomonas shigelloides cells characterized by the presence of methylenhexadecanoic acid as well as by similarity with Vibrio and Aeromonas by the content of most fatty acids confirms a supposition of R. R. Colwell on the intermediate status of genus Plesiomonas between the families Enterobacteriaceae and Vibrionaceae. Independent of the growth medium, the strains Vibrio. Aeromonas and Plesiomonas preserved a fatty-acid profile, inherent in them, with variations mainly in the content of fatty acids with the odd number of carbon atoms. Allowing for relative stability of fatty acid composition and its peculiarity in certain taxonomic groups of the studied bacteria, the above test may be used as additional objective criterion to identify the representatives of Vibrionaceae family.

[The cellular fatty acid composition of bacteria in the family Vibrionaceae]. / Sostav kletochnykh zhirnykh kislot bakterii semeistva Vibrionaceae.

Vibrio cholerae strains, serovar O1, biovar eltor, subtype Ogawa, isolated from different sources, V. cholerae classica and NAG vibrios have identical cell fatty acid composition with the prevalence of hexadecenoic, hexadecanoic and octadecenoic acids. V. parahaemolyticus and V. alginolyticus fatty acid profiles, being identical, are similar to V. cholerae profile, differing from it mainly by a higher content of dodecanoic acid. The similarity of the fatty acid profiles of Aeromonas sp. and Vibrio strains is indicative of their phylogenetic relationship. The fatty acid composition of Plesiomonas shigelloides characterized by the presence of methylenehexadecanoic acid and at the same time by its similarity to that of Vibrio and Aeromonas in the content of the majority of fatty acids, confirms the position on the intermediate status of the genus Plesiomonas between the families Enterobacteriaceae and Vibrionaceae.

[The characteristic properties of Vibrio cholerae eltor isolated from environmental objects on the territory of the former USSR during the 7th cholera pandemic]. / Kharakteristika nekotorykh svoistv Vibrio cholerae eltor, vydelennykh iz ob''ektov okruzhaiushchei sredy na territorii byvshego SSSR vo vremia sed'moi pandemii kholery.

The properties of 22,382 V. eltor strains isolated from environmental objects on the territory of different climatic and geographical zones during the period of 1970-1988 were studied. The study was made on the morphology of their colonies, the agglutinability of the strains by cholera O serum, type-specific serum and RO serum, their capacity for being lyzed by V. eltor bacteriophage, their hemolytic activity and virulence. Differences in the occurrence of strains with any of the above-mentioned properties, depending on the object from which they were isolate, the climatic and geographical zone and the intensity of the epidemiological situation with regard to cholera.

[Cholera in Ukraine and Moldova during the 7th pandemic]. / Kholera na Ukraine i v Moldove v period sed'moi pandemii.

The epidemic manifestations of cholera in the Ukraine and Moldova in 1970-1991 are analyzed. In the Ukraine the peak of cholera morbidity in 1970 was caused by infection brought to the ports of Odessa and Kerch with its subsequent spread to other territories. This infection was characterized by outbreaks transmitted through water, mainly sea water, with the isolation of Vibrio eltor toxigenic virulent strains and outbreaks of vibrio carriership of alimentary (dairy) origin with the isolation of avirulent strains. In Moldova local outbreaks of water origin were registered in 1970-1972. In both territories prolonged (up to 16 years and even longer) circulation of cholera vibrios, mainly nontoxigenic and avirulent, were registered. The retrospective epidemiological analysis and the epidemiological situation in some regions of the Ukraine in 1991 completely confirmed the prognostic importance of the division of territories into regions according to the type of epidemiological manifestations and the necessity of differentiating the measures to be taken in the system of epidemiological surveillance.

[The ecological and geographical aspects of the spread of Vibrio cholerae in environmental objects]. / Ekologo-geograficheskie aspekty rasprostraneniia Vibrio cholerae v ob''ektakh okruzhaiushchei sredy.

The results of studies carried out over the period of 24 years have revealed that V. eltor is widely spread in different ecological systems over a considerable part of the territory of the former USSR in the temperate and subtropical climatic zones. The duration and seasonal character of the isolation of these bacteria depend on climatic and geographical conditions, and their isolation rate greatly depends on the epidemic situation. The intensity and seasonal character of the isolation of V. eltor have been shown to depend on the character of the ecological system. For some water reservoirs definite biotic and abiotic factors capable of influencing the isolation rate of V. eltor have been determined, but no general regularities involving the above-mentioned factors and constantly ensuring such influence have been established.