Microstructure assessment of Co alloy intended for dentistry

Cobalt–chromium–molybdenum (CoCrMo) alloys are known for medical use due to their biocompatibility, corrosion and wear resistance. The chemical and phase composition, as well as microstructure of the alloy directly affect the mechanical properties. In this investigation, CoCrMo alloy samples were obtained by vacuum precise casting. The procedure of melting and casting process as well as their parameters are given. Molds fabricated of copper, gray iron, steel, ceramics and graphite were used during the casting process. In this way, the cooling rate influence on the obtained microstructure was examined. Besides, different casting temperatures (1400°C, 1450°C and 1500°C) were applied for each kind of mold. After metallographic preparation, the microstructure was examined on the cross section of samples by optical microscopy. The obtained results show that by increasing the cooling rate, the microstructure of samples become finer and more homogeneous

Gender modulates development of the metabolic syndrome phenotype in fructose-fed rats

We analyzed the effects of a fructose-rich diet (FRD) to test the assumption that the expression of metabolic syndrome phenotype is different in male and female rats. Two-way ANOVA revealed a significant effect of FRD on feeding behavior and carbohydrate/lipid metabolism. The increased caloric intake in FRD rats of both sexes was followed by a cluster of gender-specific changes typical for the metabolic syndrome. Female rats were characterized by decreased glycemia, increased triglycerides, enlarged visceral adipose tissue and increased absolute mass of liver, without changes in systolic blood pressure and insulin sensitivity. In contrast, male rats developed less disturbances in physical and biochemical characteristics, but blood pressure and insulin sensitivity were impaired by FRD. The results emphasize the detrimental effects of fructose consumption on cardiovascular risk and insulin action in males, whereas females are affected by other metabolic disturbances. These results support the idea of gender-dependent differences in the expression of the metabolic syndrome phenotype.Projekat ministarstva br. 4100

Gender modulates development of the metabolic syndrome phenotype in fructose-fed rats

We analyzed the effects of a fructose-rich diet (FRD) to test the assumption that the expression of metabolic syndrome phenotype is different in male and female rats. Two-way ANOVA revealed a significant effect of FRD on feeding behavior and carbohydrate/lipid metabolism. The increased caloric intake in FRD rats of both sexes was followed by a cluster of gender-specific changes typical for the metabolic syndrome. Female rats were characterized by decreased glycemia, increased triglycerides, enlarged visceral adipose tissue and increased absolute mass of liver, without changes in systolic blood pressure and insulin sensitivity. In contrast, male rats developed less disturbances in physical and biochemical characteristics, but blood pressure and insulin sensitivity were impaired by FRD. The results emphasize the detrimental effects of fructose consumption on cardiovascular risk and insulin action in males, whereas females are affected by other metabolic disturbances. These results support the idea of gender-dependent differences in the expression of the metabolic syndrome phenotype.Projekat ministarstva br. 4100

Anxiety-like behavioural effects of extremely low-frequency electromagnetic field in rats

In recent years, extremely low-frequency electromagnetic field (ELF-EMF) has received considerable attention for its potential biological effects. Numerous studies have shown the role of ELF-EMF in behaviour modulation. The aim of this study was to investigate the effect of short-term ELF-EMF (50 Hz) in the development of anxiety-like behaviour in rats through change hypothalamic oxidative stress and NO. Ten adult male rats (Wistar albino) were divided in two groups: control group-without exposure to ELF-EMF and experimental group-exposed to ELF-EMF during 7 days. After the exposure, time open field test and elevated plus maze were used to evaluate the anxiety-like behaviour of rats. Upon completion of the behavioural tests, concentrations of superoxide anion (O-2 center dot(-)), nitrite (NO2-, as an indicator of NO) and peroxynitrite (ONOO-) were determined in the hypothalamus of the animals. Obtained results show that ELF-EMF both induces anxiety-like behaviour and increases concentrations of O-2 center dot(-) and NO, whereas it did not effect on ONOO- concentration in hypothalamus of rats. In conclusion, the development of anxiety-like behaviour is mediated by oxidative stress and increased NO concentration in hypothalamus of rats exposed to ELF-EMF during 7 days

Biotransformation and nitroglycerin-induced effects on antioxidative defense system in rat erythrocytes and reticulocytes

The effects of nitroglycerin (glyceryl trinitrate - GTN) are mediated by liberated nitric oxide (NO) and formed reactive nitrogen species, which induces oxidative stress during biotransformation in red blood cells (RBCs). The aim of this study was to evaluate effects of GTN on antioxidative defense system (AOS) in rat erythrocytes (without) and reticulocytes (with functional mitochondria). Rat erythrocyte and reticulocyte-rich RBC suspensions were aerobically incubated (2 h, 37 degrees C) without (control) or in the presence of different concentrations of GTN (0.1-1.5 mM). After incubation, concentrations of non-enzymatic components of AOS, activities of antioxidative enzymes and oxidative pentose phosphate (OPP) pathway activity were followed in RBC suspensions. In rat reticulocytes, GTN decreased the activity of mitochondrial MnSOD and increased the activity of CuZnSOD. In rat RBCs, GTN induced increase of Vit E concentration (at high doses), but decreased glutathione content and activities of all glutathione-dependent antioxidative enzymes; the OPP pathway activity significantly increased. GTN biotransformation and induction of oxidative stress were followed by general disbalance of antioxidative capacities in both kinds of RBCs. We suggest that oxidative stress, MnSOD inhibition and depletion of glutathione pool in response to GTN treatment lead to decreased bioavailability of NO after GTN biotransformation in rat reticulocytes.Serbian Ministry of Education, Science and Technological Development {[}III41010, OI173041

Specific regulation of ACTH secretion under the influence of low and high ambient temperature-The role of catecholamines and vasopressin

The response of hypothalamo-pituitary-adrenocortical (HPA) axis to different stressors depends on numerous stimulatory and inhibitory signals gathering from various parts of the brain to the hypothalamic nuclei. The present study was aimed at determining whether catecholamines (CA) and vasopressin (VP) play the role in the specific regulation of adrenocorticotropic hormone (ACTH) secretion under the influence of thermal stressors, cold (+4 degrees C) and heat (+38 degrees C), applied acutely for 1 h or repeatedly during 7 and 14 day (1 h daily). The results showed that following acute exposure to those stressors, hypothalamic dopamine (DA), noradrenaline (NA) and adrenaline (ADR) concentrations were significantly decreased as compared to non stressed controls. The prolonged exposure to either of the two stressors left hypothalamic CA concentration unaffected. The amount of pituitary VP significantly increased only under the influence of acute heat stress. Prolonged exposure to both stressors induced significant decrease in the pituitary VP content. Unlike the heat, the cold-caused changes in circulating VP did not follow those in the pituitary. The applied stressors significantly increased the amount of the pituitary V1b receptor (V1bR) mainly present at the surface of corticotrophs, depending on both duration of exposure and nature of stressor. Additionally, both cold and heat specifically induced an increase in blood ACTH. In conclusion, this studys results suggest that the role of VP in the regulation of the ACTH secretion in response to cold and heat depends on the type of stressor, whereas the role of the CA depends on the manner of exposure. (C) 2012 Elsevier Ltd. All rights reserved

The influence of filler type on the corrosion stability of the sulfure concrete

Sulfur concrete was prepared by using the initial components: sand as an aggregate, modified sulfur binder, and talc, alumina, microsilica, and fly ash as fillers. Portland cement concrete was made of the same aggregate and fillers and portland cement. The durability of prepared concrete samples was tested in following aggressive solutions: 10% HCl, 20% H2SO4, and 3% NaCl as a function of time. Changes in mass and strength of the sulfur concrete were monitored periodicallly during the immersion time of 360 days in above solutions. These changes were used as a measure of deterioration level. It should be highlighted that the samples with the ash and especially talc exhibit higher durability in the solutions of HCl and H2SO4 than the samples with alumina and microsilica. In the solutions of NaCl all samples shown excellent durability while the samples with talc were the best. Portland cement concrete samples after two months lost 20 % of mass and shown degradation of mechanical properties. By usage of sulfur for sulfur concrete production, huge environmental problem regarding storage of waste sulfur from oil refining process is solved. On the other hand, sulfur concrete with its low price has an excellent quality for the application in aggressive environments unlike more expensive PCC

Gender modulates development of the metabolic syndrome phenotype in fructose-fed rats

We analyzed the effects of a fructose-rich diet (FRD) to test the assumption that the expression of metabolic syndrome phenotype is different in male and female rats. Two-way ANOVA revealed a significant effect of FRD on feeding behavior and carbohydrate/lipid metabolism. The increased caloric intake in FRD rats of both sexes was followed by a cluster of gender-specific changes typical for the metabolic syndrome. Female rats were characterized by decreased glycemia, increased triglycerides, enlarged visceral adipose tissue and increased absolute mass of liver, without changes in systolic blood pressure and insulin sensitivity. In contrast, male rats developed less disturbances in physical and biochemical characteristics, but blood pressure and insulin sensitivity were impaired by FRD. The results emphasize the detrimental effects of fructose consumption on cardiovascular risk and insulin action in males, whereas females are affected by other metabolic disturbances. These results support the idea of gender-dependent differences in the expression of the metabolic syndrome phenotype. [Projekat Ministarstva nauke Republike Srbije, br. 41009

Effect of aspartame on biochemical and oxidative stress parameters in rat blood

Aspartame (ASP) is one of the most widely used nonnutritive sweeteners. This study investigates the chronic effects of ASP on hematological and biochemical parameters, and its effects on the oxidative/antioxidative status in the red blood cells of Wistar albino rats. Rats were provided with ASP (40 mg/kg/daily for six weeks) in drinking water. Increased food and fluid intake was observed in the ASP-treated rats. Total body mass was significantly decreased in the ASP-treated rats. Treatment with ASP caused an increase in the concentrations of glucose, cholesterol, LDL-cholesterol, and in the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), as well as a decrease in the levels of HDL-cholesterol in the serum. A significant decline in the number of white blood cells (WBC) was observed after ASP uptake. Based on the results we conclude that ASP induces oxidative stress, observed as an alteration of the glutathione redox status, which leads to increased concentrations of nitric oxide (NO) and lipid peroxides (LPO) in the red blood cells. Changes in biochemical parameters, lipid metabolism, as well as changes in the levels of oxidative stress markers and the appearance of signs of liver damage indicate that chronic use of ASP can lead to the development of hyperglycemia, hypercholesterolemia and associated diseases. [Projekat Ministarstva nauke Republike Srbije, br. 173041