1,720,963 research outputs found
Bisphenol a and bisphenol S oxidative effects in sheep red blood cells: An in vitro study
No full textBisphenols (BPs) are plastic components widely used worldwide and occurring in the environment. Exposure to these compounds is known to be harmful for animals and humans at different levels. The aim of this study was to evaluate and compare the oxidative effects of bisphenol A (BPA) and bisphenol S (BPS) in sheep. Reactive oxygen species (ROS) production and correlated structural alterations in sheep erythrocytes were investigated in vitro. Blood samples from four ewes were collected at fasting from the jugular vein using vacuum collection tubes containing EDTA. For ROS assay in erythrocytes, blood was properly diluted and BPA or BPS was added to obtain final bisphenol concentrations in the range between 1 and 300 μM. 2′,7′-Dichlorodihydrofluorescein diacetate (H2DCF-DA) 3 μM was added to the samples, and fluorescence was read in four replicates using a microplate reader. To evaluate erythrocyte shape, blood smears of blood treated with the different concentrations of BPS and BPA were prepared. A significant increase in ROS production was observed when concentrations of BPS and BPA increased from 1 to 100 μM (p < 0:05). At the higher concentrations of the two studied BPs (300 μM of BPS and 200-300 μM of BPA), a ROS decrease was observed when compared to the control group (p < 0:01). Erythrocytes' shape alterations were observed in cells treated with BPS and BPA 200-300 μM 4 hours after the beginning of the treatment. This study confirms that BPA and BPS exhibit oxidative effects on sheep erythrocytes. At higher concentrations, BPA was able to modify erythrocytes' shape, while BPS altered their membrane as a sign of a protein clustering that could lead to eryptosis. These BPs' effects are consequent to intracellular ROS increase
Evaluation of curcuma and ginger mixture ability to prevent ROS production induced by bisphenol S: an in vitro study
No full textThe use of bisphenol S (BPS) as a substitute of Bisphenol A is increasing in several products and it can be found in different environmental and biological matrices. Its toxicity has been studied at different levels and one of BPS toxic mechanisms at high concentrations seems to be the induction of oxidative stress through the generation of reactive oxygen species (ROS). This study evaluates the ability of a curcuma and ginger (CG) mixture to exert an antioxidant effect on rat hepatocytes treated with BPS. The effects of the mixture were compared to those of a well-known antioxidant (Trolox). Three different BPS concentrations were used in order to verify ROS production. 70 μg/mL and 150 μg/mL of BPS generated a significant ROS increase (p < 0.01) as compared to control, while CG mixture was able to decrease this ROS production in hepatic cells, as compared to cells treated with 70 μg/ml of BPS (p < 0.01) restoring control levels. BPS 70 μg/mL was tested for total antioxidant capacity (TEAC), superoxide dismutase (SOD) and total thiols. TEAC and SOD significant decreased (p < 0.05 and p < 0.01, respectively) as compared to controls and CG mixture was able to restore control values. Given the widespread BPS use, results obtained in this study can be of high impact for the community, demonstrating the ability of a mixture of natural products to prevent BPS-induced oxidative stress
An overview of antibiotics as emerging contaminants: Occurrence in bivalves as biomonitoring organisms
Full text linkAntibiotics are used for therapeutic and prophylactic purposes in both human and veterinary medicine and as growth promoting agents in farms and aquaculture. They can accumulate in environmental matrices and in the food chain, causing adverse effects in humans and animals including the development of antibiotic resistance. This review aims to update and discuss the available data on antibiotic residues, using bivalves as biomonitoring organisms. The current research indicates that antibiotics’ presence in bivalves has been investigated along European, American and Asian coasts, with the majority of studies reported for the last. Several classes of antibiotics have been detected, with a higher frequency of detection reported for macrolides, sulfonamides and quinolones. The highest concentration was instead reported for tetracyclines in bivalves collected in the North Adriatic Sea. Only oxytetracycline levels detected in this latter site exceeded the maximum residual limit established by the competent authorities. Moreover, the risk that can be derived from bivalve consumption, calculated considering the highest concentrations of antibiotics residues reported in the analyzed studies, is actually negligible. Nevertheless, further supervisions are needed in order to preserve the environment from antibiotic pollution, prevent the development of antimicrobial resistance and reduce the health risk derived from seafood consumption
Bisphenols' occurrence in bivalves as sentinel of environmental contamination
No full textBisphenols are massively used in several manufacture processes such that bisphenol A (BPA) is ubiquitous in environment worldwide. After the implementation of regulations about BPA use, manufacturers have moved their production toward alternative substances structurally similar to it. Unfortunately, BPA analogues, given their structural similarity, exert also similar adverse effects. This review aims to investigate the occurrence of bisphenols (BPs) in bivalve molluscs. In this way, valuable information on the amount of BPs released into the environment in different areas are given. The current research indicates that BPA presence in bivalve molluscs has been investigated in Asia (Indian Ocean and Pacific Ocean), Europe (Mediterranean Sea, Baltic Sea and Atlantic Ocean) and America (Lake Mead, Nevada) with the highest amount of studies reported in bivalves harvested in Asian Coasts. BPA analogues are frequently detected in several matrices and their levels will continuously increase in the environment. Nevertheless, there is a current lack of studies analysing BPs other than BPA in bivalves. Further investigations should be conducted in this direction, in order to assess environmental distribution and the hazard for animals and human health given that seafood consumption could be an important pathway of bisphenols intake
Role of nitric oxide synthase inhibition in the acute hypertensive response to intracerebroventricular cadmium. Brit. J. Pharmacol., 123, 129-135 (1998)
No full text1. In the rat, intracerebroventricular (i.c.v.) injection of cadmium, a pollutant with long biological half-life, causes a sustained increase in blood pressure at doses that are ineffective by peripheral route. Since cadmium inhibits calcium-calmodulin constitutive nitric oxide (NO) synthase in cytosolic preparations of rat brain, this mechanism may be responsible for the acute pressor action of this heavy metal. 2. To test this possibility, we evaluated the effect of i.c.v. injection of 88 nmol cadmium in normotensive unanaesthetized Wistar rats, which were i.c.v. pre-treated with: (1) saline (control), (2) L-arginine (L-Arg), to increase the availability of substrate for NO biosynthesis, (3) D-arginine (D-Arg), (4) 3-[4-morpholinyl]-sydnonimine-hydrochloride (SIN-1), an NO donor, or (5) CaCl2, a cofactor of brain calcium-calmodulin-dependent cNOS(I). In additional experiments, the levels of L-citrulline (the stable equimolar product derived from enzymatic cleavage of L-Arg by NO synthase) were determined in the brain of vehicle- or cadmium-treated rats. 3. The pressor response to cadmium reached its nadir at 5 min (43+/-4 mmHg) and lasted over 20 min in controls. L-Citrulline/protein content was reduced from 35 up to 50% in the cerebral cortex, pons, hippocampus, striatus, hypothalamus (P<0.01) of cadmium-treated rats compared with controls. Central injection of N(G) nitro-L-arginine-methylester (L-NAME) also reduced the levels of L-citrulline in the brain. 4. Both the magnitude and duration of the response were attenuated by 1.21 and 2.42 micromol SIN-1 (32+/-3 and 15+/-4 mmHg, P<0.05), or 1 micromol CaCl2 (6+/-4 mmHg, P<0.05). Selectivity of action exerted by SIN-1 was confirmed by the use of another NO donor, S-nitroso-N-acetyl-penicillamine (SNAP). Both L-Arg and D-Arg caused a mild but significant attenuation in the main phase of the pressor response evoked by cadmium. However, only L-Arg reduced the magnitude of the delayed, pressor response. Despite their similarity in ability to attenuate the cadmium-induced pressure effect, L-Arg and its isomer exerted differential biochemical changes in brain L-citrulline, as L-Arg normalized cadmium-induced reduction in L-citrulline levels, whereas i.c.v. D-Arg did not. 5. We conclude that the pressor effect of i.c.v. cadmium is due, at least in part, to reduced NO formation, consequent to inhibition of brain NO synthase. Accumulation of cadmium in the central nervous system could interfere with central mechanisms (including NO synthase) implicated in the regulation of cardiovascular function
LC-MS/MS analysis of two new designer drugs (FLY serie) in rat plasma and its application to a pharmacokinetic study
No full textThe widespread diffusion of new psychoactive substances, requires a continuous update and development of new methods able to identify and quantify these new molecules in biological matrices. In this study an analytical method for the determination of two new benzodifuranyl derivatives, 1-(2,3,6,7-tetrahydrofuro[2,3-f][1]benzofuran-4-yl)propan-2-amine and 2-(2,3,6,7-tetrahydrofuro[2,3-f][1]benzofuran-4-yl)ethanamine, in rat plasma was developed. A solid phase extraction using C18 cartridges was carried out obtaining good recoveries with low matrix effect. Quantification was performed by a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Separation was carried out on a C18 reverse phase column with water/methanol containing 0.1% of formic acid as mobile phase. These conditions allowed to achieve adequate separation, resolution and signal-to-noise ratio for analytes and internal standard. Calibration curves were linear over the concentration range from 10 to 400 ng/ml with correlation coefficients that exceeded 0.995. Obtained precision, accuracy and recovery showed good reproducibility and selectivity. Finally, the validation method was successfully applied to an in vivo study in order to evaluate the pharmacokinetic profile of these new amphetamines
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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