Crimean-Congo hemorrhagic fever in Rostov Province: the epidemiological characteristics of an outbreak

The results of the epidemiological analysis of the outbreak of hemorrhagic fever which was caused by Crimean-Congo hemorrhagic fever virus and occurred during the period of July 3-19, 1999, in the Oblivskaya district of Rostov Province are presented. The specific epidemiological features of the outbreak have been determined. The possible versions of the appearance of the focus of infection and the role of Ixodes ticks in the circulation of the infective agent are discussed.     

Serum leptin levels in patients with sideropenic and pernicious anemia: the influence of anemia treatment

Leptin is a 16 kDa protein hormone involved in food intake, energy expenditure regulation and numerous other physiological processes. Recently, leptin has been demonstrated to stimulate hematopoietic stem cells in vitro. The aim of our study was to measure serum leptin and erythropoietin levels in patients with sideropenic (n = 18) and pernicious anemia (n=7) before and during anemia treatment. Blood samples for the blood count, leptin and erythropoietin determinations were obtained by venepunction at the time of the diagnosis of anemia and after partial and complete anemia recovery. The relationships of serum leptin levels to erythropoietin levels and blood count parameters were also studied. No significant differences in serum leptin levels between the groups studied were found. The serum leptin levels in none of groups were modified by treatment of anemia (basal levels, the levels during treatment and after anemia recovery were 13.1+/-14.5 vs 12.8+/-15.6 vs 12.0+/-14.8 ng/ml in patients with sideropenic anemia and 7.8+/-8.5 vs 9.5+/-10.0 vs 8.9+/-6.6 ng/ml in patients with pernicious anemia). The erythropoietin levels were higher at the time of anemia in both groups and decreased significantly after partial or complete recovery. Serum leptin levels in both groups correlated positively with the body mass index. No significant relationships were found between serum leptin levels and erythropoietin values or various parameters of the peripheral blood count. We conclude that serum leptin levels in patients with sideropenic and pernicious anemia positively correlate with the body mass index but are not influenced by the treatment of anemia.     

The return of the Red Queen, or the law of the growth in the mean duration of the existence of genera during evolution

Phanerozoic marine genera apparently do not become less extinction-prone with age. Higher extinction probability in "young" cohorts of genera is better explained by initially different levels of extinction-tolerance of genera in the cohort. This fact agrees with one of the two basic statements of the "Red Queen" hypothesis (Van Valen, 1973). In the second statement (the idea that the increase in fitness lowers extinction probability) the term "fitness" should be changed to "adaptability". The increase of extinction-tolerance, that can be interpreted as the increase of adaptability to unpredictable changes of environment, is found in succession of "generations" of genera that replace one another through time. This increase reveals itself, firstly, in the growth of mean duration of genera, as well as in the decrease of extinction/origination rates, gradual accumulation of long-lived genera and origination of genera with higher duration. The increase of adaptability may be caused by selective extinction of stenotopic, ecologically specialized forms; Cope's law; evolution of ecosystems that involves development of more effective mechanisms of sustaining homeostasis which may stimulate the recovery of a genus after partial extinction.     

The migrations of the green oak tortrix Tortrix viridana L. (Lepidoptera, Torticidae): an analytical study

The author analyses mono-factorial theories of population dynamics of Tortrix viridana and discusses the hypothesis of its distant and attended migrations together with its specialized parasitoid Dirophanes invisor. Data on T. viridana temporal-spatial distribution for the period of 1938-1995 are presented. It was shown that the main factors caused the decrease in population numbers are intra-population mechanisms, providing the initiation long embryonic diapause for some part of population, the decrease in the frequency of its outbreaks. Some data indicate that large scale migrations are not important for spreading of T. viridana outbreaks.     

Relics of the Europe's warm past: phylogeography of the Aesculapian snake

Understanding how species responded to past climate change can provide information about how they may respond to the current global warming. Here we show how a European reptile species responded to the last natural global warming event at the Pleistocene-Holocene transition that led to the Holocene climatic optimum approximately 5000-8000 years ago. The Aesculapian snake, Zamenis longissimus, is a thermophilous species whose present-day distribution in the southern half of Europe is a remnant of much wider range during the Holocene climatic optimum when populations occurred as far north as Denmark. These northern populations went extinct as the climate cooled, and presently the species is extinct from all central Europe, except few relic populations in locally suitable microhabitats in Germany and the Czech Republic. Our phylogenetic and demographic analyses identified two major clades that expanded from their respective western and eastern refugia after the last glacial maximum (18,000-23,000 years ago) and contributed approximately equally to the present range. Snakes from the relic northern populations carried the Eastern clade, showing that it was primarily the snakes from the eastern, probably Balkan, refugium that occupied the central and northern Europe during the Holocene climatic optimum. Two small, deep-branching clades were identified in near the Black Sea and in Greece. These clades provide evidence for two additional refugia, which did not successfully contribute to the colonization of Europe. If, as our results suggest, some populations responded to the mid-Holocene global warming by shifting their ranges further north than other populations of the same species, knowing what populations were able to expand in different species may provide information about what populations will be important for the species' ability to cope with the current global warming.     

Relationship between the alpha diversity of communities and the appearance rates of new genera in the evolution of phanerozoic marine biota

The influence of the alpha diversity of communities on the appearance rates of new species may be either positive (due to coevolution and niche construction) or negative (due to community saturation). The development of global paleontological databases allows the extrapolation of the analysis of these effects to past geological epochs. To assess the effect of alpha diversity on the rates of generic formation in the evolution of the Phanerozoic marine biota, the correlation of the parameters D (mean generic diversity of paleontological collections containing representatives of a large taxon) and B (relative rate of the appearance of new genera in the given large taxon) was analyzed. The majority of large taxa, and the Phanerozoic biota in general, characteristically show predominance of periods of positive correlation (synchronous changes) of B and D, separated by shorter periods of negative correlation (opposite phase changes). These can be interpreted as periods of positive and negative influence of alpha diversity on diversification, although positive correlation can be generated by other factors, including taphonomic ones. Apparently, in the evolution of the Phanerozoic marine biota, the coevolution and “niche construction” played a more significant role than the effect of “saturation” of communities.     

Prevalence of hyperthyroidism after exposure during childhood or adolescence to radioiodines from the chornobyl nuclear accident: dose-response results from the Ukrainian-American Cohort Study

Relatively few data are available on the prevalence of hyperthyroidism (TSH concentrations of <0.3 mIU/liter, with normal or elevated concentrations of free T4) in individuals exposed to radioiodines at low levels. The accident at the Chornobyl (Chernobyl) nuclear plant in Ukraine on April 26, 1986 exposed large numbers of residents to radioactive fallout, principally to iodine-131 ((131)I) (mean and median doses = 0.6 Gy and 0.2 Gy). We investigated the relationship between (131)I and prevalent hyperthyroidism among 11,853 individuals exposed as children or adolescents in Ukraine who underwent an in-depth, standardized thyroid gland screening examination 12-14 years later. Radioactivity measurements taken shortly after the accident were available for all subjects and were used to estimate individual thyroid doses. We identified 76 cases of hyperthyroidism (11 overt, 65 subclinical). Using logistic regression, we tested a variety of continuous risk models and conducted categorical analyses for all subjects combined and for females (53 cases, n = 5,767) and males (23 cases, n = 6,086) separately but found no convincing evidence of a dose-response relationship between (131)I and hyperthyroidism. There was some suggestion of elevated risk among females in an analysis based on a dichotomous dose model with a threshold of 0.5 Gy chosen empirically (OR = 1.86, P = 0.06), but the statistical significance level was reduced (P = 0.13) in a formal analysis with an estimated threshold. In summary, after a thorough exploration of the data, we found no statistically significant dose-response relationship between individual (131)I thyroid doses and prevalent hyperthyroidism.     

Heterologous expression of leader-less <Emphasis Type="Italic">pga</Emphasis> gene in <Emphasis Type="Italic">Pichia pastoris</Emphasis>: intracellular production of prokaryotic enzyme

Background  

Penicillin G acylase of Escherichia coli (PGA_Ec) is a commercially valuable enzyme for which efficient bacterial expression systems have been developed. The enzyme is used as a catalyst for the hydrolytic production of β-lactam nuclei or for the synthesis of semi-synthetic penicillins such as ampicillin, amoxicillin and cephalexin. To become a mature, periplasmic enzyme, the inactive prepropeptide of PGA has to undergo complex processing that begins in the cytoplasm (autocatalytic cleavage), continues at crossing the cytoplasmic membrane (signal sequence removing), and it is completed in the periplasm. Since there are reports on impressive cytosolic expression of bacterial proteins in Pichia, we have cloned the leader-less gene encoding PGA_Ec in this host and studied yeast production capacity and enzyme authenticity.     

Response of glycine and glycyl-L-valine uptake parametrs across in vitro everted sacs of chicken gut to variations in oxygenation rate and fasting

Energy-dependent accumulation of glycine and glycyl-L-valine within the small intestinal mucosa in a chicken model of in vitro local oxygenation of the small intestinal preparation was studied. It has been shown that the most effective bilateral oxygenation significantly increase accumulation of glycyl-L-valine in the proximal segment as compared to that under oxygenation only from serosal surface both in the fed and 24-hour fasted chickens, whereas in other segments these differences was less apparent. This may be due to increased H+/ peptide cotransporter expression in the proximal segment. Thus the bilateral oxygenation probably may turn on an additional amount of already existing (but non-functional during serosal oxygenation) H+/ peptide co-transporters. Moreover, low glycine transporter expression may be the reason why supplemental oxygen (bilateral oxygenation) has no effect on glycine accumulation in the distal segment of fed chickens. A 48-hour fasting decreases glycyl-L-valine accumulation in the proximal (and medial) segments, possibly due to progressive decrease in villus height. It is concluded that: a) the accumulation rate of glycine was greater when presented as the glycyl-L-valine than when presented as the equivalent amount of free amino acid; b) the rates of accumulation of glycyl-L-valine are highest in the proximal segment, decrease in the medial segment and are the lowest in the distal segment; c) the serosal oxygenation is less effective than the mucosal and bilateral oxygenation, which markedly stimulates accumulation of nutrients in the intestinal mucosa; d) a 24-hour fasting increases glycyl-L-valine accumulation in the proximal segment only, while glycine uptake was increased in the distal segment.