Depth distribution of absorbed dose on the external surface of Cosmos 1887 biosatellite

Significant absorbed dose levels exceeding 1.0 Gy day(exp -1) have been measured on the external surface of the Cosmos 1887 biosatellite as functions of depth in stacks of thin thermoluminescent detectors (TLD's) made in U.S.S.R. and U.S.A. The dose was found to decrease rapidly with increasing absorber thickness, thereby indicating the presence of intensive fluxes of low-energy particles. Comparison between the U.S.S.R. and U.S.A. results and calculations based on the Vette Model environment are in satisfactory agreement. The major contribution to the dose under thin shielding thickness is shown to be from electrons. The fraction of the dose due to protons and heavier charged particles increases with shielding thickness

Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887

The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied. The seeds were located inside the satellite in an open space, protected with aluminum foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminum foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival rate and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can thus be regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors

Potential of machine learning methods in operational risk stratification in patients with coronary artery disease scheduled for coronary bypass surgery

Aim. To develop and evaluate the effectiveness of models for predicting mortality after coronary bypass surgery, obtained using machine learning analysis of preoperative data.Material and methods. As part of a cohort study, a retrospective prediction of in-hospital mortality after coronary artery bypass grafting (CABG) was performed in 2182 patients with stable coronary artery disease. Patients were divided into 2 following samples: learning (80%, n=1745) and training (20%, n=437). The initial ratio of surviving (n=2153) and deceased (n=29) patients in the total sample indicated a pronounced class imbalance, and therefore the resampling method was used in the training sample. Five machine learning (ML) algorithms were used to build predictive risk models: Logistic regression, Random Forrest, CatBoost, LightGBM, XGBoost. For each of these algorithms, cross-validation and hyperparameter search were performed on the training sample. As a result, five predictive models with the best parameters were obtained. The resulting predictive models were applied to the learning sample, after which their performance was compared in order to determine the most effective model.Results. Predictive models implemented on ensemble classifiers (CatBoost, LightGBM, XGBoost) showed better results compared to models based on logistic regression and random forest. The best quality metrics were obtained for CatBoost and LightGBM based models (Precision — 0,667, Recall — 0,333, F1-score — 0,444, ROC AUC — 0,666 for both models). There were following common high-ranking parameters for deciding on the outcome for both models: creatinine and blood glucose levels, left ventricular ejection fraction, age, critical stenosis (>70%) of carotid arteries and main lower limb arteries.Conclusion. Ensemble machine learning methods demonstrate higher predictive power compared to traditional methods such as logistic regression. The prognostic models obtained in the study for preoperative prediction of in-hospital mortality in patients referred for CABG can serve as a basis for developing systems to support medical decision-making in patients with coronary artery disease

FOUNDATIONS FOR SPECIAL-PURPOSE MODELING IN THE REGIONAL SYSTEMS OF ADMINISTRATIVE RESERVE

The present paper covers the issues of designated purpose of the systems, which provide formation of the regional reserve of managerial personnel. The problem is given against a wide overview of the original roots and comprehensive study of the governance, business and personality interests in terms of development of regional professional management

Differences in the Formation of Reactive Oxygen Species and Their Cytotoxicity between Thiols Combined with Aqua- and Cyanocobalamins

Cobalamin is an essential nutrient required for the normal functioning of cells. Its deficiency can lead to various pathological states. Hydroxocobalamin (HOCbl) and cyanocobalamin (CNCbl) are the forms of vitamin B12 that are most commonly used for supplementation. There is substantial evidence indicating that cobalamins can both suppress and promote oxidative stress; however, the mechanisms underlying these effects are poorly understood. Here, it was shown that the oxidation of thiols catalyzed by HOCbl and CNCbl is accompanied by reactive oxygen species (ROS) production and induces, under certain conditions, oxidative stress and cell death. The form of vitamin B12 and the structure of thiol play a decisive role in these processes. It was found that the mechanisms and kinetics of thiol oxidation catalyzed by HOCbl and CNCbl differ substantially. HOCbl increased the rate of oxidation of thiols to a greater extent than CNCbl, but quenched ROS in combination with certain thiols. Oxidation catalyzed by CNCbl was generally slower. Yet, the absence of ROS quenching resulted in their higher accumulation. The aforementioned results might explain a more pronounced cytotoxicity induced by combinations of thiols with CNCbl. On the whole, the data obtained provide a new insight into the redox processes in which cobalamins are involved. Our results might also be helpful in developing new approaches to the treatment of some cobalamin-responsive disorders in which oxidative stress is an important component

QUALITY MANAGEMENT OF REZINOTEKHNICHESKY PRODUCTION WITH USE OF NANOTECHNOLOGIES

Improvement of quality is inseparably linked with development of new approaches to increase of stability of operational properties of elastomeric composites. One of such ways is use of carbon nanomaterials as the modifier of properties of a polymeric matrix

P119

Acute myelomonocytic leukemia (FAB M4) is one of the most common forms of acute myeloid leukemia (AML). This AML form is characterized by rapid accumulation transformed myeloblasts and monoblasts in bone marrow, with the rapid suppression of normal hematopoiesis. Bone marrow microenvironment is one of the main factors determining drug resistance of leukemic cells. It is known that the adhesion of leukemic cells to mesenchymal stem cell and bone marrow extracellular matrix (laminin, collagen) enhances their drug resistance. However, it remains unknown whether the emergence of drug resistance when cell–cell contacts are formed only between leukemia cells, without the involvement of bone marrow stromal elements. We studied the role of cell aggregation in drug resistance of leukemic cells. We used the bone marrow mononuclear cells (BMMC) isolated from the patients with acute myelomonocytic leukemia. For the formation of multicellular aggregates, BMMC were cultivated in 96-well plates coated with 1.5% agarose. We showed that resistance of BMMC to bortezomib, doxorubicin and fludarabine in multicellular aggregates was increased. In three-dimensional multicellular aggregates of BMMC index IC50 for bortezomib, doxorubicin and fludarabine was 7 ± 1 ng/ml, 1 ± 0.4 mkM and 0.8 ± 0.05 mkM, respectively. In control condition, index IC50 bortezomib, doxorubicin and fludarabine was significantly lower, 2 ± 0.5 ng/ml, 0.3 ± 0.05 mkM and 0.07 ± 0.001 mkM, respectively. In multicellular aggregates of BMMC number of mitotic cells and expression of Ki-67 protein were not significantly different from the control. It has also been shown that cells in multicellular aggregates increased expression antiapoptotic protein Bcl-2. Suppression of BMMC aggregation by culturing the cells in medium containing 0.9% methylcellulose resulted in decreased IC50 index for bortezomib, doxorubicin and fludarabine, 2 ± 0.7 ng/ml, 0.12 ± 0.004 mkM and 0.04 ± 0.005 mkM, respectively. Expression of the Bcl-2 protein was also decreased. This work demonstrates the involvement of cell aggregation in the formation of drug resistance phenotype in leukemic cells. The work was supported by the Russian Foundation for Basic Research (Russia) (No. 14-04-32183, 14- 04-32191), the scholarship of the President of the Russian Federation (Russia) (No. SP-6867.2013.4, SP-1519.2015.4), and by the Government of the Russian Federation (Russia) (No.14.Z50.31.0028)