Effect of gamma irradiation on magnesium content in rat tissues

Studies in the field of radiation chemistry have shown that the greatest damage induced by ionizing radiation appears as a consequence of uncontrolled production of free radicals in the living organism, which have their origin in oxidative stress induced by ionizing radiation. Ionizing radiation also has an influence on the content of bio-essential elements in mammalian tissues. Analysis of the concentration of magnesium (Mg) seven days after whole body irradiation with a single dose of 4.2 Gy of gamma rays from a Co-60 source, showed a slight reduction in Mg content in the following analyzed tissues: front brain (cerebral hemispheres with underlying structures except pituitary gland and hypothalamus) and adrenal glands from irradiated animals as compared to the non-irradiated controls, this difference however being not statistically significant. No significant differences in the content of Mg were detected in the pituitary glands between the two groups of animals. In contrast, a significantly higher concentration of Mg seven days after irradiation was measured in the hind brain-containing cerebellum with lateral lobes and flocculi (p LT 0.005), hypothalamus (p LT 0.0001) and testes (p LT 0.05) of irradiated animals, when compared to the non-irradiated controls. This accumulation of Mg, in particular tissues of the Central Nervous System (CNS) and endocrine glands regulated by the pituitary gland and hypothalamus, may indicate the differential role Mg++ ions have in keeping the homeostasis of certain tissues, those of the brain, adrenal glands and testes after exposure to ionizing radiation

Selective inhibition of brain Na,K-ATPase by drugs

The effect of drugs from the class of cardiac (methyldigoxin, verapamil, propranolol), antiepileptic ( carbamazepine), sedative (diazepam) and antihistaminic (promethazine) drugs on Na,K-ATPase activity of plasma membranes was studied in rat brain synaptosomes. Methyldigoxin in a concentration of 0.1 mmol/l inhibits enzyme activity by 80%. Verapamil, propranolol and promethazine in concentrations of 20, 20 and 2 mmol/l respectively, entirely inhibit the ATPase activity. Carbamazepine and diazepam in concentrations of 0.02-60 mmol/l have no effect on the activity of this enzyme. According to the drug concentrations that inhibit 50% of enzyme activity (IC50), the potency can be listed in the following order: methyldigoxin GT GT promethazine GT verapamil GT = propranolol. From the inhibition of commercially available purified Na, K-ATPase isolated from porcine cerebral cortex in the presence of chosen drugs, as well as from kinetic studies on synaptosomal plasma membranes, it may be concluded that the drugs inhibit enzyme activity, partly by acting directly on the enzyme proteins. Propranolol, verapamil and promethazine inhibitions acted in an uncompetitive manner. The results suggest that these three drugs may contribute to neurological dysfunctions and indicate the necessity to take into consideration the side effects of the investigated drugs during the treatment of various pathological conditions

Inhibition of rat brain ecto-ATPase activity by various drugs

The in vitro effect of digoxin, verapamil, propranolol, carbamazepine, diazepam and promethazine were investigated on the ecto-ATPase activity of synaptosomal plasma membranes from the rat brain. ATP hydrolyzing activities of the enzyme were not affected by digoxin while the use of all other drugs resulted in significant and dose-dependent ihibition in ATP hydrolysis. According to values Of IC50 and K-iapp, the order of inhibitory potency of the drugs applied was: diazepam GT promethazine GT verapamil GT propranolol GT GT carbamazepine. Kinetic analysis of the nature of the ATPase inhibition revealed that it resulted from a direct action of drugs on the enzyme protein. The aim of the present study was to determine the potential neuromodulatory side effects of the drugs investigated. The results achieved indicated that all investigated drugs, except digoxin, may modulate neuronal activities via the purinergic receptors P2 by increasing extracellular concentrations of ATP as a consequence of inhibition of the ecto-ATPase activity. Our findings indicate that it may be useful to take into consideration the possible side effects of the investigated drugs, when they are used in treatment of different pathologies, particularly in the treatment of epilepsy by carbamazepine and diazepam

Detection of elements and radioactivity in pellets from long-eared owls (Asio otus) inhabiting the city of Belgrade (Serbia)

In this study, we analysed pellets from long-eared owls (Asio otus) collected from four localities in Belgrade (Serbia). The pellets contained the remains of prey, namely voles (Arvicola terrestris) and field mice (Apodemus agrarius). The concentrations of 14 elements (Ca, P, Mg, Na, K, Fe, Zn, Sr, Ba, Mn, Ti, Cu, Si, B) were evaluated in whole pellets and in samples containing only bone tissue, which were dissected from the whole pellet. The increased levels of certain elements, including Mn, Zn, Ba, Cu and radioactive K-40, indicate contamination of the soil by various sources, such as industrial plants and agricultural practices. From the results presented in this article, we suggest that the analysis of owl pellets may indicate the quality of the local environment

TGF-beta1 in breast cancer-estrogen regulation

TGF-beta1 is a pluripotent cytokine with diverse effects in the normal development of mammary glands, and in the development of malignant tumors of the breast. The aim of the study was to determine the levels of TGF-beta1 in the group of advanced breast cancer, in which increased TGF-beta1 levels were most likely to be expected. TGF-beta1 levels were also compared with estradiol levels. Our results suggested that TGF-beta1 synthesis may be regulated by estrogen or anti-estrogen through ER. Finding of increased TGF-beta1 levels, due to its possible role in predicting invasive phenotype in later phases of tumor progression, may indicate the tendency of tumor tissue towards autonomy

Comparison of retrospective and contemporary indoor radon measurements in a high-radon area of Serbia

In Niska Banja, Serbia, which is a high-radon area, a comparison was made between two retrospective radon measuring methods and contemporary radon measurements. The two retrospective methods derive the radon concentrations that occurred in dwellings over longer periods in the past, based on the amount of trapped 2 Po-10 on the surface of glass objects (surface traps, ST) or in the bulk of porous materials (volume traps, VT). Both surface implanted 2 1 Po-210 in glass objects and contemporary radon in air were measured in 46 rooms, distributed in 32 houses of this radon spa-town, using a dual alpha track detector configuration (CR-39 and LR115) and CR-39 track etched detectors, respectively. In addition to the use of surface trap measurements, in 18 rooms (distributed in 15 houses) VT samples of suitable material were also collected, allowing to compare ST and VT retrospective radon concentration estimates. For each room, contemporary annual radon concentrations (CONT) were measured or estimated using seasonal correction factors. The distribution of the radon concentration in all data sets was found to be close to lognormal (Chi-square test GT 0.05). Geometric means (GM) are similar, 3 ranging from 1040 to 1380 Bq m(-3) whereas geometric standard deviations (GSD) for both the retrospective methods are greater than for the CONT method, showing reasonable agreement between VT, ST and CONT measurements. A regression analysis, with respect to the lognormal distribution of each data set, shows that for VT-ST the correlation coefficient r is 0.85, for VT-CONT r is 0. 82 and for ST-CONT r is 0.73. Comparison of retrospective and contemporary radon concentrations with regard to supposed long-term indoor radon changes further supports the principal agreement between the retrospective and conventional methods. (C) 2007 Elsevier B.V. All rights reserved

High natural radiation exposure in radon spa areas: a detailed field investigation in Niska Banja (Balkan region)

The measurement campaigns have been done in the rural community of Niska. Banja, a spa town located in southern Serbia, to evaluate population exposure to natural radioactivity. After a screening survey in 200 houses, annual radon and thoron concentrations were measured in 34 houses, and in 2004 a detailed investigation was carried out at six houses with elevated indoor radon concentrations. The paper presents the results of these detailed measurements. The complementary techniques were applied to determine radon and thoron concentrations in indoor air, in soil gas, radon exhalation from soil, soil permeability, and indoor and outdoor gamma doses. Soil and water samples were collected and analysed in the laboratory. Indoor radon and thoron. concentrations were found to be more than 1 kBq m(-3) and 200 Bq m(-3) respectively. Extremely high concentrations of soil-gas radon ( GT 2000 kBq m(-3)) and radon exhalation rates (1.5 mBq m(-2) s(-1)) were observed. These results will be utilised to set up the methodology for a more systematic investigation. (c) 2006 Elsevier Ltd. All rights reserved