[Metformin impact on purine metabolism in breast cancer]. / Vliianie metformina na metabolizm purinov pri rake molochnoi zhelezy.

Large-scale epidemiological and clinical studies have demonstrated the efficacy of metformin in oncology practice. However, the mechanisms of implementation of the anti-tumor effect of this drug there is still need understanding. In this study we have investigated the effect of metformin on the activity of adenosine deaminase and respectively adenosinergic immunosuppression in tumors and their microenvironment. The material of the study was taken during surgery of breast cacer patients receiveing metformin, and also patients which did not take this drug. The adenosine deaminase activity and substrate (adenosine) and products (inosine, hypoxanthine) concentrations were determined by HPLC. Results of this study suggest that metformin significantly alters catabolism of purine nucleotides in the node breast adenocarcinoma tisue. However, the metformin-induced increase in the adenosine deaminase activity is not sufficient to reduce the level of adenosine in cancer tissue. Thus, in metformin treated patients the adenosine concentration remained unchanged, and inosine and hypoxanthine concentration significantly increased.

Adsorption of proteins at the aqueous solution/alkane interface: Co-adsorption of protein and alkane.

The equations of state, adsorption isotherms and functions of the distribution of protein molecules in liquid interfacial layers with respect to molar area and the equations for their viscoelastic behavior are presented. This theory was used to determine the adsorption characteristics of ß-casein and ß-lactoglobulin at water/oil interfaces. The experimental results are shown to be describable quite adequately by the proposed theory with consistent model parameters. The data analysis demonstrated that the ß-casein molecule adsorbed at equilibrium conditions is more unfolded as compared with dynamic conditions, and this fact causes the significant increase of the adsorption equilibrium constant. The theory assumes the adsorption of protein molecules from the aqueous solution and a competitive adsorption of alkane molecules from the alkane phase. The comparison of the experimental equilibrium interfacial tension isotherms for ß-lactoglobulin at the solution/hexane interface with data calculated using the proposed theoretical model demonstrates that the assumption of a competitive adsorption is essential, and the influence of the hexane molecules on the shape of the adsorption isotherm does in fact exist.

[Analysis of heart rate variability in assessment of baroreflex sensitivity in anesthetized rats].

Spectral analysis of the heart rate variability can be used as a measure of baroreflex sensitivity in ketamine anesthetized rats. Stimulation of delta1-receptors with phenylephrine (0.01 mg/kg, i.v.) results in a rise of the strength of heart rate regulation, principally in the low frequency band. Maximal deviations of spectral indexes from basal level were observed on 4-8 min for low (0.2-1 Hz) and high (1-3 Hz) frequencies bands and on 10-15 min for very low (0.08-0.2 Hz) frequency band after phenylephrine injection.

[Effect of superoxide dismutase on the resistance of myocardium to isadrin ]. / Vplyv superoksiddismutazy na stiikist miokarda do izadrynu.

The model of isolated totally ischemic rat heart perfused by physiological saline containing isadrinum was used to study the influence of superoxiddismutase (SOD) additions on the characteristics of perfusate, flowing from the heart. Isadrinum has promoted revealing the cardiotoxic effect of high catecholamine doses: the activity of lactate dehydrogenase, creatine phosphokinaze, acid phosphatase, catepsine D increased significantly in the perfusate. Concentration of middle-weight peptides (MWP) increased 1.7 times, the phospholipide level (PL) increased 2 times. These changes were combined with the abnormally high content of the POL products in the perfusate. Addition of SOD to the perfused saline decreased the activity of perfusate enzymes and the content of POL products, PL, MWP and Ca in the perfusate. It is assumed that the cardioprotective effect of SOD can be related not only to the ability of SOD to neutralize the superoxide radical, but also to the suppression of the specific adrenergic myocardium responses.

[Content of selected prostanoids in the rabbit myocardium as effected by izadrin]. / Vmist deiakykh prostanoidiv v miokardi kroliv pid vplyvom izadrynu.

The content of stable metabolites of prostacyclin and thromboxane A2 in the rabbit myocardium in normal conditions and after single izadrin injection (comparison of survived and dead animals) has been comparatively analyzed. It has been shown that in all the cases izadrin injection induces the synthesis of these prostaglandins. But the cases with lethal outcome are characterized by predominance of the thromboxane-synthetase activity. The revealed peculiarities of prostaglandins synthesis in myocardium need experimental check on the isolated heart.

[The cyclic nucleotide content of the blood plasma in rabbits administered izadrin]. / Vmist tsyklichnykh nukleotidiv u plazmi krovi krolykiv pry vvedenni izadrynu.

The influence of cyclic nucleotides system on the rabbit resistance to injection of exogenic sympathomimetic was studied in this experiment. Absolute concentration value and ratio of cAMP to cGMP in animals with different resistance were determined.