Biotransformation and intracellular binding of arsenic in tissues of rabbits after intraperitoneal administration of 74As labelled arsenite

the fate of arsenite was studied in rabbits injected i.p. with 1 μg As/kg body wt as ⁷⁴As labelled AsO₂^?. Eight tissues plus plasma and urine were analyzed for ⁷⁴As content at different times. Arsenic was rapidly metabolized and poorly retained in the tissues. The main metabolite present in urine and plasma was dimethylarsinic acid. Sixty percent of the dose was excreted via urine and 6% with feces during the first day. In plasma arsenic was present mainly in a diffusible form, showing a very poor binding afffinity to plasma proteins. Chromatographic separations and membrane ultrafiltrations showed that in liver and kidney cytosols, arsenic was significantly associated to proteins. the diffusible fraction disappeared within 48 h. The fraction of arsenic bound to proteins was suggested to be inorganic arsenic whereas the methylation process was closly related to the elimination and the detoxification of inorganic arsenic.     

Color interaction of dental materials: blending effect of layered composites.

OBJECTIVES: To evaluate the in vitro blending effect (BE) of layered resin composites related to material, shade, and differences in color and translucency between compared materials. METHODS: Specimens made of two composites (2CS, n=5) consisted of the outer composite with an outer diameter of 10mm, 4mm thick and an inner diameter of 4mm, 2mm thick for the inner composite. Thus, the inner composite was encircled by a 3mm outer composite around its circumference and backed by a 2mm thick outer composite, to simulate a dental restoration surrounded by hard dental tissues. The outer composite was Palfique Estelite (PE, C2 shade, standard shade), while the inner composites were PE A2, B2 and C2 shades and corresponding shades of Point 4 (P4), Tetric Ceram (TC) and Filtek A110 (FA) composites (batch shades). Single-composite, disk-shaped specimens (1CS) of all five shades (D=10mm, 2mm thick, n=5) were made as well. Visual color assessments were done by six observers using a lightbooth and 1 (mismatch) to 5 (perfect match) scale. The BE was calculated as a difference in scores between corresponding 2CS and 1CS. Z-scores and corresponding BE values (BE(Z)) were calculated. 1CS were also evaluated using a spectrophotometer. RESULTS: Blending effect ranged from -0.4 to 2.2, while BE(Z) ranged from -0.6 to 3.0. Mean visual scores for 1CS and 2CS were 1.8 (1.2) and 2.2 (1.3), respectively. BE increased with a decrease in color difference (r=0.41) and increase of translucency parameter (TP, r=0.77). High agreement was recorded among pairs of observers for both 1CS, r=0.95 (0.03) and 2CS, r=0.96 (0.02). SIGNIFICANCE: Blending effect is composite and shade dependent. Quantifying of blending potential of dental materials might provide useful clinical information for dental professionals.     

Effects of melatonin on oxidative stress parameters and pathohistological changes in rat skeletal muscle tissue following carbon tetrachloride application

Animal models demonstrating skeletal muscle (SM) disorders are rarely investigated, although these disorders accompany liver disorders and can occur during prolonged exercise/training. In cases of SM disorders exogenous antioxidants, such as melatonin, could help by generally improving tissues antioxidant capacities. We aimed to analyze the potential of melatonin in preventing biochemical and structural changes in rat biceps muscle (BM) occurring after an acute exposure to carbon tetrachloride (CCl₄). Biceps muscles obtained from male Wistar rats belonging to different experimental groups were biochemically (determination of tissue MDA, total antioxidant capacity, GSH, CAT, SOD and GPx activities) and pathologically analyzed. Also, serum levels of potassium, LHD and CK were analyzed in all experimental animals. The obtained results were statically compared with those from vehicle-treated control group. The applied melatonin prevented potassium and intracellular enzyme leakage (CK and LDH) that was induced by CCl₄, as well as an increase in tissue MDA. From a panel of determined oxidative stress parameters melatonin was able to statistically significantly prevent changes in total antioxidative capacity and in CAT, SOD and GPx activities induced by CCl₄. Microscopic analysis of BM from the animals exposed to CCl₄ revealed significant muscle fiber disorganization and massive inflammatory cell infiltration. All these changes were significantly ameliorated in the group that received melatonin prior to CCl₄. Changes in serum and tissue biochemical parameters accompanied the observed pathological changes, which demonstrated a significant influence of melatonin in preventing skeletal muscle damage induced by CCl₄.