Comparison of Antitumor Effects of Combined and Separate Treatment with NO Synthase Inhibitor T1023 and PDK1 Inhibitor Dichloroacetate.

Combined chronic treatment of Ehrlich solid carcinoma (EC) with an NOS inhibitor 1-isobutanoyl-2-isopropylisothiourea hydrobromide (T1023) and a PDK1 inhibitor dichloroacetate was accompanied by statistically significant synergetic antitumor effects manifested in a significant and stable suppression of neoplasm growth (by 55-65%). Separate treatment with T1023 and dichloroacetate induced moderate short-term inhibition of tumor growth (by 30-35%) followed by weakening of tumor sensitivity to these substances. These results attest to synergetic antitumor effects NOS inhibitor T1023 and PDK1 inhibitor dichloroacetate producing antiangiogenic and hypoxia-targeted cytotoxic effects, during their combined administration, which allows overcoming the adaptive potential of the tumors.

[Radioprotective Properties of NO-Synthase Inhibitor T1023: I. Indicators of Radioprotective Activity and Interaction with Other Radioprotectors].

The study of radioprotective activity of NO-synthase inhibitor, N-S-isothiourea derivative T1023 showed that this compound has a significant therapeutic range of radioprotective activity (5.5-6.0) and its optimal radioprotective dose is 1/4 LD16. The value of its Radiation Dose-Reduction Factor totaled 1.4-1.8. We have demonstrated a pronounced pharmacodynamic interaction of T1023 with some known radioprotectors. The character of the interaction was determined by its vasoactive properties. Combined use of T1023 and cystamine, which causes a decrease in vascular tone, was accompanied by a statistically significant weakening of the radioprotective effect. But, the combined use of T1023 with serotonergic and adrenergic radioprotectors having a pressor action caused a statistically significant increase in the radioprotective effect. Moreover, T1023 combined with such radioprotectors caused the synergistic radioprotective effect even when used at small doses that do not have any radioprotective effect alone. The findings suggest that NOS inhibitors can be effective radioprotectors and are able to create new opportunities for the development of safer radioprotective agents. The very same compound T1023, according to current criteria of pharmacological screening, is certainly promising for further investigations.

[Radioprotective Properties of NO-synthase Inhibitor T1023: II. The Ability for Selective Protection of Normal Tissues During Radiotherapy of Tumors].

We studied the effect of T1023, NO-synthase inhibitor, N-acyl-S-alkyl-isothiourea in a single administration at a dose of 75 mg/kg on the growth of transplantable rat sarcoma M-1 and the development of acute skin reactions after the local impact of γ-radiation at the doses of 32 and 36 Gy. The results showed that the T1023 at a single dose had no effect on the growth of sarcoma, and did not modify the radiosensitivity of the tumor and anti-tumor efficacy of γ-rays. However, at both doses T1023 significantly reduced the severity of acute radiation skin reactions. NOS inhibitor did not change the duration of the inflammatory and regenerative processes, but significantly limited the degree of radiation alteration of the deep layers of the skin and underlying tissues. The findings suggest that the hypoxic mechanism of antitumor action allows T1023 to selectively protect the non-malignant tissue during radiation therapy of solid tumors. Therefore, this compound may be regarded as a promising basis for the development of pharmacological prevention of radiotherapy complications.

[On the mechanism of radioprotective effect of NO-synthase inhibitors].

We studied the influence on hemodynamics and radioprotective activity of two inhibitors of NO-synthase (NOS)--isothiourea derivatives with different NOS isoform selectivity: T1023--a selective inhibitor of endothelial and inducible NOS; and NTT2--a highly selective inhibitor of neuronal NOS. Both compounds at a dose of 1/7 LD50/15 caused a vasopressive effect and baroreflex response in normal Wistar rats. However, the nature of hemodynamic changes was qualitatively different. T1023 caused a prolonged elevation of vascular tone and reflex shift resulted in a significant and lasting reduction in the systemic blood flow (35-45%), which created conditions for the development of circulatory hypoxia. The use of NTT2 caused a reflex change in hemodynamics accompanied by vasodilation; and systemic blood flow was maintained at the initial level. T1023 effectively protected mice subjected to 10 Gy γ-irradiation and their bone marrow stem cells irradiated with 6 Gy, not yielding to the radioprotective effect of cystamine. NTT2 at these doses did not show any radioprotective effect. The obtained results support the leading mechanism of the radioprotective effect of NOS inhibitors is the induction of hypoxia. With this mechanism of action a significant radioprotective activity can be expected for the inhibitors which effectively suppress primarily endothelial NOS.

[Radioprotective properties of isothiourea derivatives with NO-inhibitory mechanism of action].

The study of the radioprotective activity of S-[2-alkyl (aryl) sulfonyl]-S-ethyl derivatives of (vinyl)-isothiourea in (he model of the survival of mice exposed to gamma-radiation at a dose of 10 Gy has shown that the incorporation of additional sulfur-containing groups does not increase the radioprotective properties of compounds. In contrast to aminoalkil thiols, the effectiveness of the radiation protection action of the isothiourea (ITU) derivatives studied clearly correlates with the NO-inhibitory activity. This fact allowed us to assume that the radioprotective effect of S-substituted ITU caused inhibition of the endogenous synthesis of NO, which promotes the development of circulatory hypoxia, and that a further search for the radioprotective agents in this class of chemicals should be considered as the search for effective inhibitors of NO-synthase (NOS). The theoretical analysis of the conformity of molecular structures to the composition and topology of the active center of NOS-inhibitors allowed us to prognosticate a number of new ITU derivatives with the potential NOS-inhibiting ability. As a result of further theoretical and experimental studies, four S,N-disubstituted ITU derivatives - active non-selective NOS-inhibitors, were first identified and synthesized. These compounds exhibited a pronounced and prolonged vasopressive effects at doses of 0.01-0.05 LD50/15 in the models of severe hemorrhagic and endotoxic shock, and provided 65-100% 30-day survival at doses of 0.2-0.3 LD50/15 in the mice irradiated by gamma-rays at a dose of 10 Gy (LD98/30).The findings suggest the pronounced radioprotective effect of NOS-inhibitors among the ITU-derivatives.

Effect of NO inhibitors on hypovolemic shock-induced hypotension.

In vivo effect of isothiourea derivatives on NO production was studied by the method of electron paramagnetic resonance spectroscopy with a spin trap. We evaluated the influence of these compounds on hemodynamic parameters in anesthetized rats with hypovolemic shock. A correlation was found between the size of S,N-substituents in isothiourea derivatives (methyl, ethyl, and isopropyl) and NO inhibitory activity of compounds. The antihypotensive effect was more pronounced in compounds with high NO inhibitory activity containing the isopropyl radical.

[Lipid peroxidation and antioxidant system status in patients with acute myeloblast leukemia and toxic damage of the liver].

Patients with acute myelogenous leucosis with toxic damage of the liver against polychemotherapy have an expressed disbalance in the lipid peroxidation-anti-oxidant system, which is possible to correct effectively using S-adenozilmetionin (heptral) was observed.

Possible involvement of NO in the stimulating effect of pifithrins on survival of hemopoietic clonogenic cells.

Pifithrin alpha (PFTalpha), one of the first known low molecular weight modulators of activity of tumor suppressor p53, increases survival of hemopoietic clonogenic cells (evaluated by the criterion of formation of endogenous spleen CFU-C8 colonies in irradiated animals). This effect appeared when PFTalpha was administered either before or after irradiation. Increase in CFU-C8 was also observed after administration of two PFTalpha analogs, derivatives of 2-amino-4,5,6,7-tetrahydrobenzothiazole. These included a parent compound, 2-ATBT (2-amino-4,5,6,7-tetrahydrobenzothiazole), which is used for synthesis of PFTalpha, and a product of its intramolecular cyclization under physiological conditions, cyclo-PFT (2-(4-methylphenyl)imidazo[2,1-b]-5,6,7,8-tetrahydrobenzothiazole). Earlier we found that many low molecular weight compounds increasing number of CFU-C8 (e.g. isothiourea derivatives) demonstrate NO inhibitory activity. Such activity was also found in 2-ATBT and cyclo-PFT by means of EPR spectroscopy of NO. These compounds caused more than twofold inhibition of NO production in vivo. Thus, it has been demonstrated that PFTalpha and its structural analogs increase survival of hemopoietic clonogenic cells in vivo, and NO may play a role in the mechanism of this effect.

[Effect of new hemocorrectors on heart mitochondrial oxidation in hemorrhagic shock]. / Izuchenie vliianiia novykh gemokorrektorov na mitokhondrial'noe okislenie v serdtse pri gemorragicheskom shoke.

In experimental model of hemorrhagic shock, the influence of new hemocorrectors, succinasole and sucksivil (1,4-naphtoquinone) on rabbit myocardial mitochondrial oxidation was studied. Both substances improved function of myocardial mitochondria. Administration of new hemocorrectors increased duration of life of animals subjected to hemorrhagic shock, improved hemodynamics, metabolism, normalized myocaidla mitochondrial functions and increased positive effect of shock therapy.

[Succivil efficacy in endogenous intoxication]. / Issledovanie éffektivnosti suktsivila pri énogennykh intoksikatsiiakh.

Succivil, a drug based on the blood substitute succinasol and containing 1,4-naphthoquinone, was studied as a means of restoring the living activity of cells occurring under extremal conditions of alcohol, heliotrin, or combined intoxication. A thorough investigation of the role of the free-radical oxidation in the dynamics of cell damage, in combination with histological, morphological, and biochemical data, showed that the aforementioned extremal intoxication factors lead to disorders in the cell energetics and intracell detoxicant system and to more or less manifested changes in the hemodynamic, biochemical, and physiological parameters. Succivil is capable of reanimating the cells damaged by the extremal factors studied.

[Status of glycolysis in newborns with hypoxia]. / Sostoianie glikoliza u novorozhdennykh s gipoksiei.

An incriase has been shown in the blood content of lactate, NADH2, pyruvate, activity of lactatedehydrogenase in hypoxic newborn infants, which fact is believed to have a positive character. Under conditions of deficient supply of tissues with oxygen activization of glycolysis is of compensatory character. The results obtained should be regarded as a positive factor aimed to make up for the fund of NADH2, a potential energy product securing ATP synthesis through aerobic mechanism.

[The coagulation link of the hemostatic system in newborn infants from mothers with extragenital pathology]. / Stan koahuliatsiinoï lanky systemy hemostazu u novonarodzhenyjh vid materiv z ekstrahenital'noiu patolohiieiu.

Overall, fifty newborn infants born to mothers with extragenital pathology (diabetes mellitus) were studied for the coagulative link of the homeostasis system as were 20 babies born to essentially healthy mothers. The studies were made by day 1 to 3 and 5 to 7 the babies' life. The conducted studies revealed signs of hypercoagulation presenting with activation of the external and internal route of hemostasis in those infants born to mothers with diabetes mellitus (DM). Toward the period of early neonatal adaptation shifts are still observable in the coagulating system at the expense of stimulation of the first phase of coagulation. The disclosed abnormalities in the coagulative link of the coagulating system in infants born to DM mothers pose a threat of development of thrombohaemorrhagic complications.

[Hypoxia, lipid peroxidation, and defence antioxidant system in children born to mothers with extragenital pathology]. / Gipoksiia i stan perekysnogo okyslennia lipidiv ta antyoksidantnoi systemy zakhystu u ditei, narodzhenykh vid materiv iz ekstragenital'nymy zakhvoriuvanniamy.

A study was made on the condition of lipid peroxidation and of the antioxident system of defence in 20 infants born to healthy mothers (control group), 12 babies born to mothers with diabetes mellitus, 15 infants born to mothers with neurocirculatory asthenia and 12 infants born to mothers with congenital heart diseases. In infants born to mothers with diabetes mellitus and cardiovascular pathology, the system of regulation was found to have gotten out of balance, the compensatory-and-adaptive reactions upset. Accumulation of peroxidic products and depletion of the antioxidant system of defence tended to be more readily seen in those babies born to mothers with diabetes mellitus. The results secured attest to the need for employment of drugs endowed with antioxidant activity.

[The status of the stress-limiting and stress-realizing links in adaptation in newborn rabbits with experimental chronic fetal hypoxia]. / Stan deiakykh streslimituiuchykh i stresrealizuiuchykh laok adaptatsiï u novonarodzhenykh kroliv z eksperymental'noiu khronichnoiu hipoksiieiu ploda.

The model of chronic intrauterine hypoxia was made according to the method, devised in physiology and experimental medicine laboratory of Institute of Pediatrics, Obstetrics and Gynecology Ukrainian AM Sci. This method consist in dose narrowing of the basal venous columns from cornua of uterus in rabbits on 14-15 days of pregnancy. The obtained experimental results confirm previous clinical date about disturbances in antistress mechanisms of protection under chronic fetus hypoxia. Evidently, this disturbances are the important pathogenetic links in behinding of newborn rabbits in physical development and, especially, in its lethality.

[Comparative evaluation of the effects of crystalloid solutions containing sodium lactate and sodium succinate on the hemodynamic indicators in different types of hemorrhage]. / Sravnitel'naia otsenka vliianiia kristalloidnykh rastvorov, soderzhashchikh laktat i suktsinat natriia, na pokazateli gemo- dinamiki pri razlichnykh vidakh krovopoteri.

The results are presented of the hemodynamics investigations under the influence of two saline infusion solutions in varying types of hemorrhage. The suggested crystalloid solution succinasol contains sodium succinate (instead of lactate that is present in lactasol) which improves energetic processes in tissues under conditions of circulatory hypoxia. The results of the study of hemodynamics parameters and animal survival rate have shown succinasol advantages as compared to the lactate-saline blood substitute in acute massive hemorrhage and reversible hemorrhagic shock.

[A comparative evaluation of methods for determining the activity of rheumatic diseases]. / Sravnitel'naia otsenka nekotorykh metodov opredeleniia aktivnosti revmaticheskikh zabolevanii.

The blood concentration of soluble complexes of monomere fibrin (SCMF), fibrin/fibrinogen splitting products (FSP) and sigma-ESB were determined in 11 patients with rheumatic diseases showing an articular syndrome. The authors revealed the diagnostic significance of SCMF in arthritis of any etiology and FSP in rheumatic diseases with systemic manifestations.

[Indices of the blood fibrinolytic system in osteoarthrosis and rheumatoid arthritis]. / Pokazateli fibrinoliticheskoi sistemy krovi pri osteoartroze i revmatoidnom artrite.

The fibrinolytic system of the blood was studied in 46 patients with osteoarthrosis (OA) associated with reactive synovitis or without it, 44 patients with rheumatoid arthritis (RA) without visceral manifestations. It was found that a slowing of enzymatic, nonenzymatic and XIIa-dependent fibrinolysis is typical of RA but not of OA. Products of fibrin breaking in the general blood flow were absent in patients with OA but may be observed in RA. Increase of the level of fibrin monomers (FM) in the blood are observed in OA with reactive synovitis. The concentration of FM in the blood in RA and OA with reactive synovitis is an informative and dynamic sign of the activity of the inflammatory process and efficacy of treatment.

[The fibrinogen-fibrin-fibrinolysis system in rheumatoid arthritis]. / Sistema fibrinogen-fibrin-fibrinoliz pri revmatoidnom artrite.

The enzymatic, nonenzymatic and XIIa-dependent fibrinolysis was inhibited. In RA without systemic manifestations the main cause of appearance of soluble complexes of monomeric fibrins (SCMF) in the blood is a local activation of coagulation in the inflamed joint tissues. It is suggested that an increase of SCMF concentration in the blood in patients with RA is a reliable and dynamic index of the activity of the inflammatory process.