Short-term administration of melatonin or ghrelin on diabetic rats: effects on angiotensin II and vasopressin-induced uterine contractility

The aim of the present study was to investigate the effects of Angiotensin II (Ang II) and Arginin-Vasopressin (AVP) on contractility of non-pregnant uterus in diabetic Wistar rats and to explore whether one-week administration of Melatonin (MLT) or Ghrelin (GHR) will change the response of diabetic uterine muscle to AngII and AVP. Uterine horns, prepared by the method of isolated tissues were investigated as well as glycemic profile, blood pressure and body weight. The research of smooth muscle contractions was made by a new method of analysis, characterizing in detail the various phases of the myometrial activity. Differences in the development of the peptide-mediated smooth muscle contractions depending on the phase of the estrous cycle were observed. Experimental diabetes had a pronounced negative effect on force and time-parameters of AngII and AVP-stimulated uterine contractions. Administration of GHR or MLT had a beneficial effect on the glycemic status of diabetic rats and partially improved the response of uterine preparations to the peptides. The application of MLT increased both force and time-parameters of Ang II-and AVP-stimulated uterine contractions while treatment with GHR increased power characteristics and shortened contraction and relaxation of the smooth muscle process.

Effect of the spin-labelled 1-ethyl-1-nitrosourea on CCNU-induced oxidative liver injury

This study was carried out to determine the effects of 1-ethyl-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-l-nitrosourea (SLENU), recently synthesised in our laboratory, and vitamin E as positive control on 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) - free radical induced oxidative injuries in the liver of mice. Specifically, alterations in malonyl dialdehyde (MDA) level and activities of some antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were measured in liver homogenates from tumour-bearing C57 black mice after treatment with solutions of CCNU (30 mg/kg) and SLENU (100 mg/kg), both administered intraperitoneally. CCNU-induced increase in MDA level, SOD and CAT activities were suppressed by SLENU. The present results and those from a previous report demonstrated superoxide scavenging activities (SSA) of the nitrosourea SLENU and enabled us explain the protective effect of the spin-labelled nitrosourea on CCNU-induced oxidative stress in the liver of mice. This protective effect is through the scavenging of *O2- and by an increased production of *NO. Thus, a potential for developing new combination chemotherapy in cancer is seen.

Erythrocyte membrane defects in hemolytic anemias found through derivative thermal analysis of electric impedance

Hereditary hemolytic anemias originate mainly from defects in hemoglobin and plasma membrane proteins. Here, we propose a new method, thermal analysis of impedance, sensitive to membrane defects. It detects three processes in erythrocyte membrane; fall in membrane capacity at 49.5 degrees C and activation of passive PO(4)(2+) permeability at 37 degrees C and inorganic ions at 61.5 degrees C. The denaturation of spectrin is involved in the first process whilst the anion channel is involved in latter processes. Using this method three persons with xerocytosis were found whereby the fall in membrane capacity and spherization of erythrocytes were both postponed (53 degrees C) compared to control (49.5 degrees C). In contrast to control cells, strong activation of passive permeability for Cl(-) at 37 degrees C and sucrose at 61 degrees C were detected that were both eliminated by pre-inhibition of the anion channel with 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS). In addition, erythrocytes from 15 patients with various forms of anemia were studied in intact state and after refreshment. The results were compared with the data of clinical laboratory and osmotic fragility test. The final conclusion is that this method detects membrane defects with altered spectrin and anion channel syndrome (hereditary xerocytosis, spherocytosis, poikilocytosis and pyropoikilocytosis, elliptocytosis and stomatocytosis) and, after refreshment, helps differentiate them from the anemia with hemoglobinopathy.

Beneficial effects of spin-labelled nitrosourea on CCNU-induced oxidative stress in rat blood compared with vitamin E

This study was carried out to determine the effects of a recently synthesized 1-ethyl-3-[4-(2,2,6,6-tetra-methylpiperidine-1-oxyl)]-1-nitrosourea (SLENU), compared with vitamin E as a positive control, on 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU)-induced oxidative stress in rats. We determined plasma malonyl dialdehyde (MDA) levels and the activities of erythrocyte superoxide dismutase (SOD) and catalase (CAT). Forty two white albino healthy rats were treated once daily for 30 days with oral preparations of CCNU (12.5 mg/kg and 25 mg/kg), SLENU (25-200 mg/kg), and combinations of these. The CCNU-induced increase in plasma MDA level and the usual decrease in erythrocyte SOD and CAT activities were reversed by SLENU, but not by vitamin E. We have previously demonstrated that SLENU is a superoxide scavenger. A combination of our present findings with previous results thus leads us to proposing a new chemotherapeutic combination of CCNU and SLENU that is devoid of high toxicity.

Hepatoprotective effect of isonicotinoylhydrazone SH7 against chronic isoniazid toxicity

This study was carried out to investigate whether 3,5-dichloro-salicylaldehyde isonicotinoyl hydrazone (SH7), an analogue of the antituberculosis drug isoniazid (INH), recently synthesized in our laboratory, could prevent isoniazid-induced liver damage. Forty-two white healthy mice were treated, once daily for 30 days, with solutions of INH, SH7 and combinations of them at doses of 7.5 mg/kg p.o. and 15 mg/kg p.o. At the end of this period, livers were harvested for histopathological analysis. The levels of lipid peroxidation products (MDA) and the activities of antioxidant defense enzymes, superoxide dismutase (SOD) and catalase (CAT), were also measured in the liver homogenates. Treatments with combinations of INH and SH7 decreased the levels of MDA, normalized the previously depressed levels of SOD and CAT and prevented isoniazid-induced liver damages. A previously demonstrated tuberculostatic and superoxide scavenger activity (SSA) of the isonicotinoylhydrazone SH7 and results from the present study thus set out a proposal for a new isoniazid/SH7 combination therapy designed to provide hepatoprotection.

Lipid peroxidation, superoxide dismutase and catalase activities in brain tumor tissues

Free radical-mediated damages may play an important role in cancerogenesis. To investigate their relevance in the cancer process, malonyl dialdehyde (MDA) level, superoxide dismutase (SOD), and catalase (CAT) activities were determined in the normal brain tissue and brain tumor tissue. When compared with the normal brain tissue, we have detected: (i) significantly lower MDA concentration in brain tumor tissue (1.63 nmol/mg Pr vs 2.04 nmol/mg Pr; p = 0.03); (ii) SOD activity in brain tumor tissue was significantly lower (3.15 U/mg Pr vs 4.97 U/mg Pr; p = 0.0002); and (iii) CAT activity in brain tumor tissue was 106.3% higher than that in controls.

Schematic illustration of some of the mechanisms for maintenance of homeostasis in organism

The aim of the present paper is to illustrate schematically by a non-equal arm lever system the mechanisms that maintain the homeostasis of reactive oxygen species, glucose, mean arterial pressure and electrolytes. All regulating factors that increase the values of each physiological parameter are placed on the same arm of the lever system. The regulating factors that decrease this value are placed on the other arm of the lever. In this way the two types of factors interact with one another and maintain the lever system in a dynamic equilibrium, i.e., contribute to keeping the homeostasis. Illustrating the maintenance of homeostasis by a non-equal arm lever system gives the opportunity to express the quickness, flexibility, stability and effectiveness of physiological regulations.

Schematic illustration of the mechanisms for maintenance of electrolyte and glucose homeostasis

The aim of the present paper is to give a schematic illustration of the basic humoral mechanisms of sodium, calcium and glucose homeostasis regulation. These can be compared to a lever system that maintains a dynamic equilibrium.