[The Prediction Model of Cardiovascular Events Among the Russian Population: Methodological Aspects].

Modeling is the common approach for predicting not only the population health, but also the social and economic burden of disease, which is an important argument while making decisions in health care and prevention. AIM: To develop the model for predicting cardiovascular risk, applicable for the assessment of clinical and socio-economic effects of preventive and therapeutic actions at the level of the whole population or part (region, city, group of patients). MATERIAL AND METHODS: An analytical model for making decision was performed by using a Markov model consisting of Markov states and probabilities of transition from one state to another within a certain time interval. The model included risk factors and cardiovascular diseases (blood pressure, cholesterol, smoking) and probabilities of transition between them. Data was standardized by age for both males and females. Multivariate sensitivity analysis was performed. The literature search conducted using eLIBRARY.RU (http://elibrary.ru) and CyberLeninka (http://cyberleninka.ru). Consultations with experts in the field of coronary heart disease, stroke, heart failure were carried out. RESULTS: The model, allowing to compare the outcomes of two scenarios (absence/presence of intervention). The model included risk factors: arterial hypertension, smoking, hypercholesterolemia, and important CVD: coronary artery disease, myocardial infarction, unstable angina, heart failure, chronic heart failure after myocardial infarction, transient ischemic attack, stroke, atrial fibrillation. There was absorbent state - death. At the output from the model the patient state was defined as the sum of the Markov states characteristics during the model time horizon. Each result had the cost and outcome, which values could be calculated by simulation modeling ("cohort simulation"). The data analysis from prospective study had shown that mortality increases with age, as expected, but in different age groups impact of cardiovascular causes was different and declined with age. In the case of the blood pressure there was the expected increase of the death risk with the growth of pressure levels, both for males and females, except for males 60-64 years old who had a minimal risk of death at the blood pressure 140-149/90-99 mmHg, and among males with normal blood pressure the risk was higher. Smoking was associated with an expected increase of the death risk among all age groups in both sexes. In males, aged 40-64 years, the death risk was higher at the normal levels of cholesterol (2-5 mmol/l), than at the cholesterol levels equal 5-7 mmol/l. There were no data sources to assess probability of occurrence of the risk factors (hypertension, smoking, hypercholesterolemia) in patients who did not have these factors previously in our studies, and available literature. This requires the prospective studies on at least two slices of surveys (not just with the endpoint analysis). Analysis of the literature on search of prospective Russian studies that would evaluate the probability of transition from one state to another, and consultations with experts have identified that currently conducted studies do not provide all the necessary probability of transition on the basis of national data. In the absence of local data for the model is acceptable to use the results of meta-analyzes of international studies. CONCLUSION: Markov model will allow for prediction the effectiveness of different interventions, including their socio-economic consequences. The created model will allow in the future to make changes with the appearance of the results of new studies or new data in order to improve modeling accuracy.

[Economic efficiency of renal denervation in patients with resistant hypertension: results of Markov modeling].

Aim of this study was to evaluate the cost-effectiveness of renal denervation (RD) in resistant arterial hypertension (AH) in Russia. Modeling of Markov conducted economic impact of RD on the Russian population of patients with resistant hypertension in combination with optimal medical therapy (OMT) compared with OMT using a model developed by American researchers based on the results of international research. The model contains data on Russian mortality, and costs of major complications of hypertension. The simulation results showed a significant reduction in relative risk reduction of adverse outcomes in patients with resistant hypertension for 10 years (risk of stroke is reduced by 30%, myocardial infarction - 32%). RD saves 0.9 years of quality-adjusted life (QALY) by an average of 1 patient with resistant hypertension. Costs for 1 year stored in the application of quality of life amounted to RD 203 791.6 rubles. Which is below the 1 gross domestic product and therefore indicates the feasibility of this method in Russia.

Fe(III) reduction during pyruvate fermentation by Desulfotomaculum reducens strain MI-1.

Desulfotomaculum reducens MI-1 is a Gram-positive, sulfate-reducing bacterium also capable of reducing several metals, among which is Fe(III). Very limited knowledge is available on the potential mechanism(s) of metal reduction among Gram-positive bacteria, despite their preponderance in the microbial communities that inhabit some inhospitable environments (e.g., thermal or hyperthermal ecosystems, extreme pH or salinity environments, heavy metal or radionuclide contaminated sediments). Here, we show that in the presence of pyruvate, this micro-organism is capable of reducing both soluble Fe(III)-citrate and solid-phase hydrous ferric oxide, although growth is sustained by pyruvate fermentation rather than Fe(III) respiration. Despite the fact that Fe(III) reduction does not support direct energy conservation, D. reducens uses it as a complementary means of discarding excess reducing equivalent after H2 accumulation in the culture headspace renders proton reduction unfavorable. Thus, Fe(III) reduction permits the oxidation of greater amounts of pyruvate than fermentation alone. Fe(III) reduction by D. reducens is mediated by a soluble electron carrier, most likely riboflavin. Additionally, an intracellular electron storage molecule acts as a capacitor and accumulates electrons during pyruvate oxidation for slow release to Fe(III). The reductase responsible for the transfer of electrons from the capacitor to the soluble carrier has not been identified, but data presented here argue against the involvement of c-type cytochromes.

Role of proteins in controlling selenium nanoparticle size.

This work investigates the potential for harnessing the association of bacterial proteins to biogenic selenium nanoparticles (SeNPs) to control the size distribution and the morphology of the resultant SeNPs. We conducted a proteomic study and compared proteins associated with biogenic SeNPs produced by E. coli to chemically synthesized SeNPs as well as magnetite nanoparticles. We identified four proteins (AdhP, Idh, OmpC, AceA) that bound specifically to SeNPs and observed a narrower size distribution as well as more spherical morphology when the particles were synthesized chemically in the presence of proteins. A more detailed study of AdhP (alcohol dehydrogenase propanol-preferring) confirmed the strong affinity of this protein for the SeNP surface and revealed that this protein controlled the size distribution of the SeNPs and yielded a narrow size distribution with a three-fold decrease in the median size. These results support the assertion that protein may become an important tool in the industrial-scale synthesis of SeNPs of uniform size and properties.

Electron diffraction and high resolution transmission electron microscopy in the characterization of calcium phosphate precipitation from aqueous solutions under biomineralization conditions.

Calcium phosphate precipitation obtained from aqueous solutions at room and body temperature and pH 5.5-7.5 were investigated by high-resolution transmission electron microscopy (HRTEM), transmission electron diffraction, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Supersaturated solutions of calcium phosphates were prepared by different methods of mixing of the stock solutions: diffusion-controlled mixing in space, convection-controlled mixing on earth and forced mixing on earth and with typical physiological parameters (pH and temperature). Concentrations of the stock solutions, rate of solution mixing and duration of precipitation influence very strongly the chemical composition of the precipitation, the phase composition of individual crystals, their sizes, morphology and structure. Microdiffraction and HRTEM techniques showed an incontestable advantage on other techniques like SEM and XRD in the investigation of small particles and mixtures of calcium phosphates (hydroxyapatite and octacalcium phosphate) with different proportions.

Terrestrial and space-grown HAP and OCP crystals: effect of growth conditions on perfection and morphology.

This paper reports comparative characterizations of calcium phosphate crystals grown on earth and in space. At the CaCl2 and KH2PO4 + K2HPO4 solution concentrations and the pH used, only hydroxyapatite (HAP) crystals grow under terrestrial condition while both HAP and octacalcium phosphate (OCP) crystals grew during the space experiment. The space-grown OCP crystals reach 3 mm in size, the space-grown HAP crystals reach sizes up to 100 times larger than the earth-grown crystallites. It was found also that the space-grown crystallites are more perfect than the terrestrial ones, being more stable under electron beam during HRTEM examination. Spherolites of hydroxyapatite consist of small and thin HAP crystals with different orientations. Space-grown OCP crystals containing almost pure OCP phase show strong striations along the c direction due to thickness variations. Terrestrial OCP crystals grown at lowest supersaturation on earth may be almost as large as the space-grown ones, possess a regular habit and are homogeneous in thickness. However, they always contain substantial regions of HAP structure. Also, in these crystals electron irradiation induces phase transformation from crystalline to amorphous (disordered) state during transmission electron microscopy observations. In the space-grown crystals, such transformation needs longer radiation time. We believe that the differences described above come from much lower supersaturation and different pH for crystals nucleating and growing in space compared to those formed on earth.

Calcium phosphate crystallization under terrestrial and microgravity conditions.

Calcium phosphate crystalline powders grown under terrestrial and space (EURECA 1992-1993 flight) conditions in the Solution Growth Facility are analyzed and compared by optical and electron microscopy (scanning and transmission), electron and X-ray microdiffraction and microanalyses. On earth, only small, micrometer size scale, spherolites of hydroxyapatite (HAP) grow. In space, the HAP spherolites reach hundreds of micrometer. Also, octacalcium phosphate (OCP) spherolites up to 3 mm have been obtained. Computer modelling of diffusion in a real chamber has been performed. It suggests high spatial supersaturation gradients at zero gravity which may provide much higher local supersaturations on earth, where convection takes place. The analyses suggest that the dramatic difference between the terrestrial and space samples should come from much lower supersaturation in space.

Crystallization of calcium phosphate in microgravity.

Dilute solutions of CaCl2 and KH2PO4 + K2HPO4 were diffusing from either side into a mixing chamber with KCl solution. The microgravity experiment yielded aggregates of large crystals of OCP (Ca8H2(PO4)3,5H2O) and spherolites of smaller, but still visible crystals of HAP (Ca5OH(PO4)3), the stable final phase. Ground-based experiments yielded submicroscopic HAP crystals. Results of calculations of diffusion and crystal growth on the basis of previous knowledge agree well with observations.