ß-Like DNA polymerases and prospects for their use as targets in chemotherapy of tumors.

DNA polymerases ß are enzymes that perform repair of damaged DNA. In the cells of malignant tumors, there is a change in the production and properties of these enzymes, which is accompanied by altered viability of tumor cells. Analysis of the publications available in Russian and international databases (Pubmed, Elsevier) on the structure and properties of DNA polymerases ß and their role in cell growth and proliferation, published over the past 20 years, has shown overexpression of genes encoding ß-like DNA polymerases in many types of malignant tumors cells. This explains the maintenance of their viability and proliferative activity. Targeted inhibition of ß-like DNA polymerases is accompanied by antiproliferative and antitumor effects. Stable paramagnetic isotopes of magnesium (25Mg2+) or other divalent metals (43Ca2+ and 67Zn2+) with uncompensated nuclear spin isotopes, as well as short single-stranded polydeoxyribonucleotides, can be used as promising antitumor pharmacophores.

Oligomerization of ß-Like DNA Polymerases in the Presence of Fe2+ Ions.

This work presents data on the relationship between the oligomeric state and catalytic activity of ß-like DNA polymerases isolated from three cancer cell lines upon replacement of magnesium ions with iron. It was shown that the suppression of the catalytic activity of ß-like DNA polymerases in the presence of divalent iron ions is related to enzyme oligomerization that can be responsible for the suppression of the magnetic isotope effect.

Radiation-Chemical Biotechnology for Producing Ultrashort (50-100n) Single-Chain Polydeoxyribonucleotides with Anticancer Activity.

The fundamental possibility of obtaining ultrashort (50n-100n) single-stranded polydeoxyribonucleotides by the method of radiation-chemical destruction of total yeast DNA was established and their anticancer activity was shown.

L, D-Polydeoxyribonucleotides to provide an essential inhibitory effect on DNA polymerase ß of human myeloid leukemia HL60 cells.

The inhibitory effect of D and L-polynucleotides of a given length (40-50n) on the catalytic activity of DNA polymerase ß isolated from chromatin cells of acute myeloid leukemia HL-60 was evaluated. The synthesized L enantiomer was found to have a higher inhibitory activity than the synthesized and isolated D enantiomers of polynucleotides. The work also proposes a biophysical model that describes this effect.

Effect of Calcium on Slow Force Responses in Isolated Right Ventricle Preparations of Healthy and Hypertrophied Myocardium in Male and Female Rats.

Effect of different Ca2+ concentrations in the bathing solution [Ca2+]o on the parameters of single isometric contraction and slow force response to stretching was studied in isolated preparations of healthy and hypertrophied myocardium of male and female Wistar rats. In all groups of experimental animals, the increase in calcium concentration was followed by a decrease in the myocardium slow response intensity. We revealed a complementary relationship between the current and medium-term systems of myocardial contractility regulation by the length of the myocardium aimed at the maintenance of the constant level during adaptation to the load. Slow responses of the hypertrophied rat heart myocardium were suppressed in comparison with those in the healthy myocardium and their intensity did not depend on animal sex.

Contractility of Right Ventricular Myocardium in Male and Female Rats during Physiological and Pathological Hypertrophy.

Sex differences in the morphogenesis and adaptation of the mechanisms controlling myocardium contractility during physiological and pathological hypertrophy of the right ventricle were demonstrated in mature rats. The study revealed sex-dependent effects of physiological and pathological cardiac hypertrophy on the coefficient of variation of the cardiomyocyte diameter, length-dependent control of the contractile force, and the maximum velocity of isotonic shortening.

[MORPHOLOGICAL AND VISCOELASTIC PROPERTIES OF ISIAH RATS MYOCARDIUM DURING THE DEVELOPMENT OF ARTERIAL HYPERTENSION].

The comprehensive study of morphometrical parameters and viscoelastic properties of right ventricle and left ventricle papillary muscles of ISIAH rats during the development of arterial hypertension has been carried out. It is established the significant increase of the index of heart mass to body mass and to tibia length of ISIAH rats in comparison with WAG rats of the same age. There are no any significant differences of "stress-strain" dependences of all experimental groups.

[Characteristics of load dependent relaxation of normal and hypertrophied myocardium in male and female rats].

Under monocrotaline treatment of rat right ventricle myocardium preparations significant changes in morphometric indices for male, but not for female preparations are adduced as compared to the control group. Peculiarities of adaptation of mechanocalcium uncoupling mechanism, one of important regulation mechanisms of rat myocardial contractility, were first revealed. Myocardial pressure overload results in the increase of time to peak force without alteration of characteristic time of isometric tension, relaxation for male rats under myocardial hypertrophy compared with control group rats. In addition, the decrease of the load dependent relaxation index in the male rats was obtained. Characteristics of myocardial contractility of female rats have not significant changes as compared to the control group.

[Viscoelastic properties of relaxed papillary muscle at physiological hypertrophy].

Viscoelastic properties of relaxed rat papillary muscles at physiological hypertrophy (intensive swimming for 5 weeks) have been obtained. It has been ascertained that viscoelastic properties of hypertrophied muscles are not significantly distinguished from those of control papillary muscles. A three-dimensional model of myocardial fascicle has been verified in compliance with experimental data of biomechanical tests of hypertrophied muscles. Elastic and viscous parameters of structural elements of the model negligibly differ from the parameters of the model of a control muscle. It is shown that physiological hypertrophy has a slight influence on viscoelastic properties of papillary muscles.

[Balloon-assisted enteroscopy in surgical practice].

The authors analyze their experience with video-capsular enteroscopy and balloon-assisted enteroscopy in 184 patients. High diagnostic significance of enteroscopy and the possibility to perform minimally invasive operations are shown.

[Enteroscopy in the diagnostics of the jejunum and ileum tumors].

Small bowel tumors are very uncommon and account for 3% to 6% of all gastrointestinal neoplasms. Practical application of videocapsule endoscopy and balloon-assisted enteroscopy have allowed to investigate and reveal neoplasmatic leasions in deep parts of gastrointestinal tract which earlier were hard to access. The modern techniques allow to evaluate the macroscopic picture of tumors more clearly, to determine its nature and location, take biopsy sample, to prescribe reasonable chemotherapy, to remove a tumor endoscopically or define indications for a planned surgical intervention. This article presents a widely overview over epidemiology, classification, clinical aspects, methods and diagnostic possibilities of different diagnostic techniques of revealing small bowel tumors, and own results of diagnosis and treatment of patients (n = 48) with small bowel tumors (2003-2010).

[The study of the creatine kinase radiation stability in 25Mg-enzyme enrichment experiment].

The radiation inactivation technique was applied to conduct the study on catalytic activity changes of creatine kinase species isolated from the Mid-Asian Death Adder venom. Both intact and the 25Mg-enriched enzyme samples were separately tested. Some differences in radiation stability levels were found to be indicating to a shift in conformational condition (a so called "conformational distribution") of the native enzyme that had happen in the presence of the magnetic nuclei excess.

[Angiotensin-converting enzyme stability in the presence of zinc-ions different concentrations].

Stability of angiotensin-converting enzyme was studied as a dependence on the zinc-ions concentrations brining in the apo-enzyme. Our data were discussed in the terms of a set of initial permissible conformation conditions of a protein (conformation distribution). Apo-enzyme was shown to be able to the radiation activation that is disappearing in the presence of even 10(-6 )mol/l of the zinc-ions.

The porphyrin-fullerene nanoparticles to promote the ATP overproduction in myocardium: 25Mg2+-magnetic isotope effect.

This is a first case ever reported on the fullerene-based low toxic nanocationite particles (porphyrin adducts of cyclohexyl fullerene-C(60)) designed for targeted delivery of the paramagnetic magnesium stable isotope to the heart muscle providing a sharp clinical effect close to about 80% recovery of the tissue hypoxia symptoms in less than 24 h after a single injection (0.03-0.1 LD(50)). A whole principle of this therapy is novel: (25)Mg(2+)-magnetic isotope effect selectively stimulates the ATP overproduction in the oxygen-depleted cells due to (25)Mg(2+) released by the nanoparticles. Being membranotropic cationites, these "smart nanoparticles" release the overactivating paramagnetic cations only in response to the metabolic acidic shift. The resulting positive changes in the heart cell energy metabolism may help to prevent and/or treat the local myocardial hypoxic disorders and, hence, protect the heart muscle from a serious damage in a vast variety of the hypoxia-caused clinical situations including both doxorubicin and 1-methylnicotineamide cardiotoxic side effects. Both pharmacokinetics and pharmacodynamics of the drug proposed make it suitable for safe and efficient administration in either single or multi-injection (acute or chronic) therapeutic schemes.

[The efficiency of ATP synthase as a molecular machine].

On the basis of the experimentally measured isotope effect of magnesium (25)Mg on the rate of ATP synthesis by mithochondrial ATP synthase, the rate constants of the reactions in the catalytic site have been estimated. The limiting step of the synthesis is shown to be the addition of8phosphoryl anion-radical of ADP to the P=O bond of phosphate with the rate constant of 1,2 x 10(8) s(-1). From the ratio of the rate constants, the mechanochemical efficiency of ATP synthase was estimated to be about 10% for enzymes with (24, 26)Mg isotopes and to be doubled for enzymes with (25)Mg in the catalytic site.

[New mechanisms of biological effects of electromagnetic fields].

The production of ATP in mitochondria depends on the magnesium nuclear spin and magnetic moment of a Mg2+ ion in creatine kinase and ATPase. This suggests that enzymatic synthesis of ATP is an ion-radical process and thus depends on the external magnetic field (magnetobiology originates from this fact) and microwave fields, which control the spin states of ion-radical pairs and affect the ATP synthesis. The chemical mechanism of ATP synthesis and the origin of biological effects of electromagnetic (microwave) fields are discussed.

[The effect of magnesium pool isotopy on reactivation of mitochondrial ATP synthesis suppressed by 1-methyl-nicotine amide].

The ATP-generating activity of both rat myocardial mitochondria and intramitochondrial creatine phosphokinase (CPK) was examined as a function of the incubation medium magnesium pool isotopy. The in vitro systems tested were prepared from the hearts of animals treated with single injection of 1-methyl-nicotine amide (MNA) suppressing the NAD(P)-dependent reactions in vivo. The presense of the 25Mg paramagnetic cations leads to essential compensation of intramitochondrial ATP deficiency caused by the MNA induced blockade of oxidative phosphorylation. This effect is merely unreachable in those systems where the magnesium pool consists of isotopes with a zero nuclear spin (24Mg, 26Mg). The reactivation of mitochondrial ATP synthesis described here involves CPK activity which does not depends on MNA. In this case, a high efficiency of this reactivation seems to be a spin selective phenomenon which requires, predominantly, 25Mg2+ cations.

[Magnesium magnetic isotope effect: a key towards mechanochemistry of phosphorylating enzymes as molecular machines].

A discovery of the huge magnesium isotope effect in enzymatic ATP synthesis provides a new insight into mechanochemistry of enzymes as the molecular machines. It has been found that the catalytic activity values of ATPase, creatine kinase and phosphoglycerate kinase are 2 to 4-fold higher once their active sites contain magnetic (25Mg) not spinless, non-magnetic (24Mg, 26Mg), magnesium cation isotopes. This clearly proves that the ATP synthesis is a spin-selective process involving Mg2+ as the electron accepting reagent. The formation of ATP takes place in an ion-radical pair resulted by two partners, ATP oxyradical and Mg+. The magnesium bivalent cation is a key player in this process, this ion transforms the protein molecule mechanics into a mere chemistry. This ion is a most critical detail of structure of the magnesium dependent phosphorylation enzymes as the mechanochemical molecular machines.

[Comparative analysis of EEG characteristics in patients with acute phase of ischemic stroke (according to data of computer electroencephalography)].

A complex clinical and computer-assisted EEG study was carried out. 97 patients with acute ischemic cerebral hemisphere and 27 patients with acute ischemic brain stem stroke have been observed. A computer-assisted EEG was found to improve considerably diagnostic quality of stroke patients. It enables to determine the degree of functional lesions of the brain. Local changes of EEG-pattern prevail in patients with acute ischemic cerebral hemisphere stroke. Patients with acute ischemic brain stem stroke developed diffuse changes of EEG-pattern. Background EEG is the most representative technique to reflect bioelectric activity of the brain and it enables to assess the plasticity and reactivity of processes of the brain.

[Stable isotopes of Mg2+ as activators of the suppressed ATP-generating function of mitochondria].

The ATP-generating activity of rat myocardial mitochondria and intramitochondrial creatine kinase was examined as a function of the isotopy of the incubation medium magnesium pool. The study was performed using in vitro systems prepared from the hearts of animals injected with 1-methylnicotine amide, which suppresses the NAD (NADP)-dependent reactions in vivo. It was shown that the presence of the 25Mg paramagnetic cations essential by compensates for the intramitochondrial ATP deficiency caused by the 1-methyl-nicotine amide-induced blockade of oxidative phosphorylation. This effect is hardey achievable in systems where the magnesium pool consists of isotopes with a zero nuclear spin (24Mg, 26Mg). The restoration of mitochondrial ATP synthesis involves the participation of creatine kinase since the activity of the latter does not depend on 1-methyl-nicotine amide. In this case, the high efficiency of this restaration seems to be a spin-selective phenomenon which requires predominantly 25Mg2+ cations. A possible meaning of the data for further studies on the mechanisms of enzymatic catalysis regulation is discussed.