Bìofìzičnij Vìsnik

Number 37, 2017

5-8
Mathematical modeling of the second tumors formation and estimation of the distribution of the anti-oncogenes among humans

Authors: V.G. Knigavko, E.B.Radzishevskaya, M.A. Bondarenko, O.V. Zaytseva, O.P. Meshcheryakova

Abstract

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Number of views: 474

The relevance of the work is caused by the fact the cancer is a significant factor in human mortality, and cancer incidence is increasing worldwide. As a consequence, the study of the process of carcinogenesis in general and Second tumors, in particular, is an important issue for medical physics. The aim of this study was to uncover the regularities of the secondary tumors formation in cancer patients. Such a study should enable the solution of a number of related problems, viz. estimation of the distribution of the a-genes among humans, which damage seems to be one of the most essential factors of carcinogenesis. To achieve the aim of the study the probabilistic mathematical modeling was employed, resulting in the generation of the mathematical models, capable of estimating such probabilities: 1) probability of the second tumor formation in a patient at some age, provided that the first tumor is formed in this patient at certain age; 2) probability of two tumors formation in a patient at certain age. Furthermore, the proposed models enable employment of the statistics of the second tumors to refine the parameters of the carcinogenesis model. In conclusion, the probabilistic mathematical modeling allows evaluation of a number of important quantitative characteristics of the carcinogenesis.

9-15
Analysis of stability of tomographic reconstruction of x-ray medical images

Authors: L.A. Bulavin, Y.F. Zabashta, O.V. Motolyha, S.P. Senchurov

Abstract

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Number of views: 500

Slice reconstruction in X-ray computed tomography is reduced to the solution of integral equations, or a system of algebraic equations in discrete case. It is considered to be an ill-posed problem due to the inconsistencies in the number of equations and variables and due to errors in the experimental data. Therefore, determination of the best method of the slice reconstruction is of great interest. Furthermore, all available methods give approximate results. The aim of this article was two-fold: i) to compare two methods of image reconstruction, viz. inverse projection and variation, using the numerical experiment; ii) to obtain the relationship between image accuracy and experimental error. It appeared that the image obtained by inverse projection is unstable: there was no convergence of the approximate image to the accurate one, when the experimental error reached zero. In turn, the image obtained by variational method was accurate at zero experimental error. Finally, the latter showed better slice reconstruction, despite the low number of projections and the experimental errors.

16-29
Characterization of zigzag patterns on the surface of bovine serum albumin films

Authors: D. M. Glibitskiy, O. A. Gorobchenko, O. T. Nikolov, A. V. Shestopalova, M. A. Semenov

Abstract

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Number of views: 516

Analysis of the patterns formed during the drying of biological fluids is employed for research and diagnosis in medicine and agriculture. Saline solutions of native proteins and DNA are characterized by zigzag patterns, which could be quantitatively described using the specific length of zigzags Lspecific. The aim of this study was to analyze a wide number of characteristics in order to identify those most sensitive to the effects of various physical and chemical factors on the protein structure. We examined the films prepared from salt solutions of bovine serum albumin (BSA) under varying conditions, viz.: a proportional change in the concentration of the components, substitution of NaCl with NaF and NaBr, temperature treatment, gamma irradiation, and addition of trivalent iron and biologically active flavin mononucleotide. The results revealed that the distribution of zigzag segment lengths was approximately lognormal, and the distribution of angles between the segments was approximately logistic. Two parameters appeared to be the most informative, viz. the average length of the segments, mainly depending on Cl– concentration, and the number of segments, depending on: Cl– concentration, concentration of the non-aggregated (but not necessarily unfragmented) protein, and the excess concentration of ions and low molecular weight compounds.

30-41
Redox interactions of methylene blue with cysteine amino acid as a possible mechanizm of biological action of the dye

Authors: V.S. Shelkovsky, M.V. Kosevich, O.A. Boryak, V.G. Zobnina, A.M. Plokhotnichenko

Abstract

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Number of views: 526

Design of the inhibitors of the pathogenic protein aggregation, associated with the neural cell damage, is of great importance for the therapy of the neurodegenerative diseases. In this work redox interactions of methylene blue as a potential drug against Alzheimer’s disease with its potential target – cysteine of the active cite of Tau proteins, have been studied in vitro, in order to establish the molecular mechanism of methylene blue biological action. First, a single product of direct oxidation of cysteine by methylene blue, viz. cystine, possessing a disulfide bridge between two cysteine molecules, has been detected by mass spectrometry. Such modification of cysteine residues was suggested to affect secondary structure of Tau-proteins, hampering amyloid fibril formation. Notably, we failed to detect any oxygen-containing products of cysteine oxidation. Finally, reduction of methylene blue in the above reaction resulted in the formation of its leuco form, which could be also considered as a potential drug in the therapy of neurodegenerative diseases.

42-50
Effect of rare-earth-based nanoparticles on the erythrocyte osmotic adaptation

Authors: O.K. Pakulova, V.K. Klochkov, N.S. Kavok, I.A. Kostina, A.S. Sopotova, V.A. Bondarenko

Abstract

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Number of views: 495

Rare-earth-based nanoparticles (REB NPs) have been employed in molecular and cell biology due to their unique features. However, their interaction with biosystems and the influence on cell functioning are poorly understood. In this study effect of REB NPs (composed of dielectric nanocrystalls of cerium dioxide and orthovanadates of gadolinium and yttrium) with different form-factor as well as REB NPs-cholesterol complexes on the adaptation of human erythrocytes to hypertonic lysis (4 M NaCl) has been evaluated spectrophotometrically. It appeared that the degree of cell damage in the presence of REP NPs under hyperosmotic conditions varied with geometric parameters of REB NPs. Specifically: i) ultra-small (2 nm) spherical CeO2 or GdYVO4:Eu3+ NPs, penetrating through the plasma membrane, ii) grain-like (8´30 nm) GdVO4:Eu3+ NPs, adsorbed on the membrane surface, iii) and spherical GdYVO4:Eu3+ NPs-cholesterol complexes promoted cell adaptation to hypertonic lysis. Furthermore, the composition of nanoparticles affected their stabilizing effect on the cells. E.g., orthovanadate NPs at 0.1 g/l had the highest antihemolytic activity after short preincubation, while cerium dioxide NPs showed the same effect after prolonged preincubation. In conclusion, REB NPs promoted hyperosmotic cell adaptation by the two different mechanisms, viz. membrane stabilization by the adsorption on the cell surface and/or penetration into the cell.