Genome reduction in a hemiclonal frog Rana esculenta from radioactively contaminated areas. (1/960)

A decrease in genome size was found in the hemiclonal hybridogenetic frog Rana esculenta (R. ridibunda x R. lessonae) from areas of radioactive contamination that resulted from the Chernobyl fallout. This genome reduction was of up to 4% and correlated with the background level of gamma-radiation (linear regression corresponded on average to -0.4% per doubling of radiation level). No change in genome size was observed in the coexisting parental species R. lessonae. There was no correlation between genome size and body mass in R. esculenta froglets, which have metamorphosed in the year of the study. The hemiclonal forms may become a suitable object for study on biological significance of individual DNA sequences (and of genome size as a whole) because mutant animals with deletions in a specified genome can arise after a low radiation dose. The proneness to genetic damage makes such forms also a prospective bioindicator of radioactive (and possibly other mutagenic) pollution with the effects of genetic damage conveniently and rapidly monitored by DNA flow cytometry.  (+info)

Asthma mortality in Russia between 1980 and 1989. (2/960)

There is evidence that mortality due to asthma has increased in a number of nations over the last two decades. This study was conducted to assess asthma mortality rates in Russia from 1980 to 1989. Data obtained were compared with figures from other countries. National asthma deaths were obtained from the Ministry of Health of the Russian Federation. Age- and sex-specific rates per 100,000 population per year were adjusted to the European population. Annual changes in mortality rates for the study period were estimated by linear regression analysis. Between 1980 and 1989, asthma mortality rates per 100,000 population per year increased from 3.7 to 5.3 in the total Russian population. Differences according to age and sex were observed. Asthma deaths increased with age and in most cases males showed higher death rates than females. There was a statistically significant annual increase in mortality rates for young males < 5 yrs of age and for adult males aged 35-64 yrs, as well as for females aged > or = 65 yrs. Asthma mortality rates in Russia between 1980 and 1989 may be considered moderate as compared with death rates reported for the same period in other countries.  (+info)

Mitochondrial DNA sequence diversity in Russians. (3/960)

The article presents the results of the first regular study of Russian populations by sequencing the control region of mitochondrial DNA (mtDNA). The sequenced region is the most variable on mtDNA molecule and is commonly used for population and evolutionary studies. Russians form one of the largest ethnic groups (more than 129 million). However, their genetic diversity had only been characterized with RFLP and biochemical markers, although there are already established mtDNA sequence databases for many ethnic groups of the world. We have obtained sequence data from 103 individuals living in three Russian regions: Kostroma, Kursk, and Rjazan. The sequenced fragment analyzed is 360 bp in length (positions from 16024 to 16383). Fifty nine nucleotide positions have been found polymorphic in Russians, among those were 57 transitions and two transversions. One individual is found having two insertions of two cytosines between positions 16184 and 16193. Among 64 different mitotypes identified in the study 52 were unique in these samples. The index of genetic diversity (Nei, 1987) for Russians is 0.96. This value is within the established range for European populations (0.93 to 0.98). Genetic distances calculated from our data show that Russians form a cluster with Germans, Bulgarians, Swedes, Estonians, and Volgo-Finns are more distant from Karelians and Finns, and much more differ from Turks and especially Mongolians.  (+info)

Heart period and heart period variability during sleep on the MIR space station. (4/960)

The long-term acclimation of cardiac rhythms to microgravity was studied in four astronauts aboard the Russian space station MIR during wakefulness and sleep. Sleep polygraphies were obtained between the third and the 30th day in space and, in addition, prior to mission on the ground. From each of the sleep polygraphies, beat-to-beat intervals of cardiac rhythms were determined. The response of heart period and heart period variability to the stimulus microgravity was tested during sleep across sleep stages and during waking. A lengthening of heart period by about 100 ms was found in space compared to measurements on the ground. The slowing of heart rate was more pronounced for non-REM sleep than for REM sleep. A systematic change in heart period in relation to the duration of the stay in space could not be detected. An analysis of heart period variability in the high frequency (respiratory sinus arrhythmia) band supports the hypothesis that the decrease of heart rate under microgravity is produced by an increase in parasympathetic activity. Testing the response of cardiac rhythms to microgravity across distinct behavioural states seems to be a powerful tool to investigate the cardiovascular system.  (+info)

Cancer mortality in Russia and Ukraine: validity, competing risks and cohort effects. (5/960)

BACKGROUND: The dramatic increase in mortality in Russia and Ukraine in the late 1980s and 1990s has been due to increases in certain causes of death, particularly cardiovascular disease and accidents and violence. In contrast, there has been a slight fall in mortality from cancer. METHODS: This paper presents an analysis of trends and patterns in cancer mortality and examines four possible explanations for its recent fall: changes in data collection; cohort effects; competing mortality from other causes of death; and improvements in health care. RESULTS: All contribute to some extent to the observed changes, with each affecting predominantly different age groups. There is evidence of a significant underrecording of cancer deaths among the elderly especially in rural areas and of significant changes in coding practices in the early 1990s. Competing mortality from cardiovascular diseases and accidents can explain some reduction in male deaths from cancer in middle age. Birth cohort effects can explain some reduction among males after early middle age and among females at all ages. The impact of changes in health care are more difficult to identify with certainty but there is evidence of reduced deaths from childhood leukaemia. IMPLICATIONS: Recent changes in mortality in Russia are complex and their understanding will require a multidisciplinary approach embracing demography, epidemiology and health services research.  (+info)

Genetic diversity in the protective antigen gene of Bacillus anthracis. (6/960)

Bacillus anthracis is a gram-positive spore-forming bacterium that causes the disease anthrax. The anthrax toxin contains three components, including the protective antigen (PA), which binds to eucaryotic cell surface receptors and mediates the transport of toxins into the cell. In this study, the entire 2,294-nucleotide protective antigen gene (pag) was sequenced from 26 of the most diverse B. anthracis strains to identify potential variation in the toxin and to further our understanding of B. anthracis evolution. Five point mutations, three synonymous and two missense, were identified. These differences correspond to six different haploid types, which translate into three different amino acid sequences. The two amino acid changes were shown to be located in an area near a highly antigenic region critical to lethal factor binding. Nested primers were used to amplify and sequence this same region of pag from necropsy samples taken from victims of the 1979 Sverdlovsk incident. This investigation uncovered five different alleles among the strains present in the tissues, including two not seen in the 26-sample survey. One of these two alleles included a novel missense mutation, again located just adjacent to the highly antigenic region. Phylogenetic (cladistic) analysis of the pag corresponded with previous strain grouping based on chromosomal variation, suggesting that plasmid evolution in B. anthracis has occurred with little or no horizontal transfer between the different strains.  (+info)

Problems of transition from tax-based system of health care finance to mandatory health insurance model in Russia. (7/960)

This article examines three problems burdening the Russian system of health care finance in transition period: (a) unrealistic government promise to cover health care coverage too wide to be achieved with available resources; (b) inefficient management of health care delivery systems; and (c) lack in evidence of actual positive changes effected by the new players: mandatory health insurance carriers and funds. Radical reshaping of the health benefits promised by the government and introduction of patient co-payments are considered as a way to normalize public health sector finance and operations. Two alternative approaches to the reform of the existing eclectic system of health care management are available. Institutional preconditions for operational effectiveness of third-party purchasers of health services in public-financed health sector are defined.  (+info)

Reflections on a painful transition: from socialized to insurance medicine in Russia. (8/960)

After the collapse of the Soviet Union in 1991, Russia decided to replace its deeply flawed and under-funded system of socialized medicine by a scheme of health insurance that involved the decentralization of health services and of off-budget financing. Every enterprise would pay 3.6% of its salary fund into a Regional Health Insurance Fund, and the Fund would finance private insurance companies that would compete for clients. The non-working population would have its insurance premiums paid from the budgets of regions or municipalities. The transition from one system to another has been problematic and plagued with a variety of problems not the least of which is that the Russian economic structure is not geared to sustain an insurance system at the present time. The Russian case presents an instructive experiment with the premature introduction of a scheme touted as an "anti-model" to socialized medicine and geared to market and legal arrangements that are, as yet, largely non-existent. Under-funding of health services remains and leads to the polarization of the population into those few who can afford private care, and the vast majority for whom this care is difficult to obtain, or unobtainable. This has ominous political implications.  (+info)

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