The effects of prolonged exposure to elevated temperatures and elevated CO2 levels on the growth, yield and dry matter partitioning of field-sown meadow fescue

Selostus: Kohotetun lämpötilan ja kohotetun CO2-pitoisuuden vaikutukset peltoon kylvetyn nurminadan kasvuun, satoon ja kuiva-aineen jakautumiseen

Prolonged exposure to palmitate impairs fatty acid oxidation despite activation of AMP-activated protein kinase in skeletal muscle cells

The aim of this study was to investigate the chronic effects of palmitate on fatty acid (FA) oxidation, AMPK/ACC phosphorylation/activation, intracellular lipid accumulation, and the molecular Mechanisms involved in these processes in skeletal muscle cells. Exposure of L6 myotubes for 8 h to 200, 400, 600, and 800 mu M of palmitate did rot affect cel viability but significantly reduced FA oxidation by similar to 26.5%, similar to 43.5%, similar to 50%, and similar to 47%, respectively. Interestingly, this occurred despite significant increases in AMPK (similar to 2.5-fold) and ACC (similar to 3-fold) phosphorylation and in malonyl-CoA decarboxylase activity (similar to 38-60%). Low concentrations of palmitate (50-100 mu M) caused an increase (similar to 30%) in CPT-I activity. However, as the concentration of palmitate increased, CPT-I activity decreased by similar to 32% after exposure for 8 h to 800 mu M of palmitate. Although FA uptake was reduced (similar to 35%) in cells exposed to increasing, palmitate concentrations, intracellular lipid accumulation increased in a dose-dependent manner, reaching values similar to 2.3-, similar to 3-, and 4-fold higher than control in muscle cells exposed to 400, 600, and 800 mu M palmitate, respectively. Interestingly, myotubes exposed to 400 mu M of palmitate for 1h increased basal glucose uptake and glycogen synthesis by similar to 40%. However, as time of incubation in the presence of palmitate progressed from 1 to 8h, these increases were abolished and a time-dependent inhibition of insulin-stimulated glucose uptake (similar to 65%) and glycogen synthesis (30%) was observed in myotubes. These findings may help explain the dysfunctional adaptations that occur in glucose and FA Metabolism in skeletal muscle under conditions of chronically elevated circulating levels of non-esterified FAs. Such as in obesity and Type 2 Diabetes.

Biomarker evaluation in fish after prolonged exposure to nano-TiO2: influence of illumination conditions and crystal phase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of catecholamines on hepatic and skeletal muscle mitochondrial respiration after prolonged exposure to faecal peritonitis in pigs

Use of norepinephrine to increase blood pressure in septic animals has been associated with increased efficiency of hepatic mitochondrial respiration. The aim of this study was to evaluate whether the same effect could be reproduced in isolated hepatic mitochondria after prolonged in vivo exposure to faecal peritonitis. Eighteen pigs were randomized to 27 h of faecal peritonitis and to a control condition (n = 9 each group). At the end, hepatic mitochondria were isolated and incubated for one hour with either norepinephrine or placebo, with and without pretreatment with the specific receptor antagonists prazosin and yohimbine. Mitochondrial state 3 and state 4 respiration were measured for respiratory chain complexes I and II, and state 3 for complex IV using high-resolution respirometry, and respiratory control ratios were calculated. Additionally, skeletal muscle mitochondrial respiration was evaluated after incubation with norepinephrine and dobutamine with and without the respective antagonists (atenolol, propranolol and phentolamine for dobutamine). Faecal peritonitis was characterized by decreasing blood pressure and stroke volume, and maintained systemic oxygen consumption. Neither faecal peritonitis nor any of the drugs or drug combinations had measurable effects on hepatic or skeletal muscle mitochondrial respiration. Norepinephrine did not improve the efficiency of complex I- and complex II-dependent isolated hepatic mitochondrial respiration [respiratory control ratio (RCR) complex I: 5.6 ± 5.3 (placebo) vs. 5.4 ± 4.6 (norepinephrine) in controls and 2.7 ± 2.1 (placebo) vs. 2.9 ± 1.5 (norepinephrine) in septic animals; RCR complex II: 3.5 ± 2.0 (placebo) vs. 3.5 ± 1.8 (norepinephrine) in controls; 2.3 ± 1.6 (placebo) vs. 2.2 ± 1.1 (norepinephrine) in septic animals]. Prolonged faecal peritonitis did not affect either hepatic or skeletal muscle mitochondrial respiration. Subsequent incubation of isolated mitochondria with norepinephrine and dobutamine did not significantly influence their respiration.

Are there age-, strain-, and sex-differences in the prolonged exposure to methylphenidate?

Repeated treatment with psychostimulants produces behavioral sensitization that results in increased locomotor responses so that lower drug doses are required to obtain the same effect and cross-sensitization with other stimulants. Methylphenidate (MPD; Ritalin) is most frequently prescribed to treat children having attention deficit hyperactivity disorder (ADHD), a syndrome with onset in childhood characterized by high levels of inattention, hyperactivity, and impulsivity. Little is known of the consequences involving the long-term use of MPD as treatment for ADHD. This study investigates if there are age, genetic/strain, and sex differences in the prolonged exposure to MPD and cross-sensitization with amphetamine. The objective is to determine whether (a) early exposure to MPD in adolescent rats increases their sensitivity to the drug when they are adult rats, (b) there are strain and sex differences in the response to MPD, and (c) treatment with MPD in adolescent and adult Wistar-Kyoto (WKY), spontaneously hyperactive/hypertensive rat (SHR), and Sprague-Dawley (SD) rat results in cross-sensitization with amphetamine. The hypotheses are that (1) early exposure to MPD in adolescent rats increases their sensitivity to the drug when they reach adulthood, and that this hypersensitivity is dose-, strain-, and sex-dependent and (2) adult rats treated with MPD as adolescents will show a greater cross-sensitization to amphetamine than those adult rats treated with saline as adolescents, and that this cross-sensitization is dose-, strain-, and sex-dependent. The study consists of recording and evaluating locomotor activity of female and male WKY, SHR, and SD rats before and after acute and repeated MPD administration when these rats are young and as adults follows by an amphetamine treatment. Results showed that repeated treatment with MPD elicited behavioral sensitization and cross-sensitization with amphetamine in these animals. The study also found that strain and sex play a crucial role in the differentiated sensitivity to the acute and chronic effects of MPD. The development of behavioral sensitization and cross-sensitization are also dependent on the dose of MPD and the age of the rat. ^

Effects of metformin on BRIN-BD11 beta-cell insulin secretory desensitization induced by prolonged exposure to sulphonylureas

Aims: Prolonged exposure of pancreatic beta-cells in vitro to the sulphonylureas tolbutamide and glibenclamide induces subsequent desensitization of insulinotropic pathways. Clinically, the insulin-sensitizing biguanide drug metformin is often administered alongside sulphonylurea as antidiabetic therapy. The present study examines the functional effects of metformin (200 µM) on tolbutamide- and glibenclamide-induced desensitisation. Methods: Acute and prolonged (18 h) effects of exposure to tolbutamide and glibenclamide alone, or in the presence of metformin, were examined in insulin-secreting BRIN-BD11 cells. Results: In acute 20 min incubations at 1.1 mM glucose, metformin increased (1.2-1.7-fold; p <0.001) the insulin-releasing actions of tolbutamide and glibenclamide. At 16.7 mM glucose, metformin significantly enhanced glibenclamide-induced insulin release at all concentrations (50-400 µM) examined, but tolbutamide-stimulated insulin secretion was only augmented at higher concentrations (300-400 µM). Exposure for 18 h to 100 µM tolbutamide or glibenclamide significantly impaired insulin release in response to glucose and a broad range of insulin secretagogues. Concomitant culture with metformin (200 µM) prevented or partially reversed many of the adverse effects on K channel dependent and independent insulinotropic pathways. Beneficial effects of metformin were also observed in cells exposed to glibenclamide for 18 h with significant improvements in the insulin secretory responsiveness to alanine, GLP-1 and sulphonylureas. The decrease of viable cell numbers observed with glibenclamide was reversed by co-culture with metformin, but cellular insulin content was depressed. Conclusions: The results suggest that metformin can prevent the aspects of sulphonylurea-induced beta-cell desensitization. © 2010 Blackwell Publishing Ltd.

Evaluation of Sphingolipids in Wistar Rats Treated to Prolonged and Single Oral Doses of Fumonisin B(1)

The objective of the present study was to evaluate sphingolipid levels (sphingosine-So and sphinganine-Sa) and to compare the Sa/So ratio in liver, serum and urine of Wistar rats after prolonged administration (21 days) of fumonisin B(1) (FB(1)). In parallel, the kinetics of sphingolipid elimination in urine was studied in animals receiving a single dose of FB(1). Prolonged exposure to FB(1) caused an increase in Sa levels in urine, serum and liver. The most marked effect on sphingolipid biosynthesis was observed in animals treated with the highest dose of FB(1). Animals receiving a single dose of FB(1) presented variations in Sa and So levels and in the Sa/So ratio.

Formaldehyde: exposure and genotoxicity assessments and potential health effects

Worldwide formaldehyde is manipulated with diverse usage properties, since industrial purposes to health laboratory objectives, representing the economic importance of this chemical agent. Therefore, many people are exposed to formaldehyde environmentally and/or occupationally. Considering the latter, there was recommended occupational exposure limits based on threshold mechanisms, limit values and indoor guidelines. Formaldehyde is classified by the International Agency for Cancer Research (IARC) as carcinogenic to humans (group 1), since a wide range of epidemiological studies in occupational exposure settings have suggested possible links between the concentration and duration of exposure and elevated risks of nasopharyngeal cancer, and others cancers, and more recently, with leukemia. Although there are different classifications, such as U.S. EPA that classified formaldehyde as a B1 compound, probable human carcinogen under the conditions of unusually high or prolonged exposure, on basis of limited evidence in humans but with sufficient evidence in animals. Formaldehyde genotoxicity is well-known, being a direct-acting genotoxic compound positively associated for almost all genetic endpoints evaluated in bacteria, yeast, fungi, plants, insects, nematodes, and cultured mammalian cells. There are many human biomonitoring studies that associate formaldehyde occupational exposure to genomic instability, and consequently possible health effects. Besides the link with cancer, also other pathologies and symptoms are associated with formaldehyde exposure, namely respiratory disorders such as asthma, and allergic contact dermatitis. Nowadays, there are efforts to reduce formaldehyde exposure, namely indoor. Europe and United States developed more strict regulation regarding formaldehyde emissions from materials containing this agent. Despite the regulations and restrictions, formaldehyde still continues to be difficult to eliminate or substitute, being biomonitoring an important tool to control possible future health effects.

Responses of the alga Pseudokirchneriella subcapitata to long-term exposure to metal stress

The green alga Pseudokirchneriella subcapitata has been widely used in ecological risk assessment, usually based on the impact of the toxicants in the alga growth. However, the physiological causes that lead algal growth inhibition are not completely understood. This work aimed to evaluate the biochemical and structural modifications in P. subcapitata after exposure, for 72 h, to three nominal concentrations of Cd(II), Cr(VI), Cu(II) and Zn(II), corresponding approximately to 72 h-EC10 and 72 h-EC50 values and a high concentration (above 72 h-EC90 values). The incubation of algal cells with the highest concentration of Cd(II), Cr(VI) or Cu(II) resulted in a loss of membrane integrity of ~16, 38 and 55%, respectively. For all metals tested, an inhibition of esterase activity, in a dose-dependent manner, was observed. Reduction of chlorophyll a content, decrease of maximum quantum yield of photosystem II and modification of mitochondrial membrane potential was also verified. In conclusion, the exposure of P. subcapitata to metals resulted in a perturbation of the cell physiological status. Principal component analysis revealed that the impairment of esterase activity combined with the reduction of chlorophyll a content were related with the inhibition of growth caused by a prolonged exposure to the heavy metals.

Gold nanoparticles for the detection of DNA adducts as biomarkers of exposure to acrylamide

The main objective of this thesis was the development of a gold nanoparticle-based methodology for detection of DNA adducts as biomarkers, to try and overcome existing drawbacks in currently employed techniques. For this objective to be achieved, the experimental work was divided in three components: sample preparation, method of detection and development of a model for exposure to acrylamide. Different techniques were employed and combined for de-complexation and purification of DNA samples (including ultrasonic energy, nuclease digestion and chromatography), resulting in a complete protocol for sample treatment, prior to detection. The detection of alkylated nucleotides using gold nanoparticles was performed by two distinct methodologies: mass spectrometry and colorimetric detection. In mass spectrometry, gold nanoparticles were employed for laser desorption/ionisation instead of the organic matrix. Identification of nucleotides was possible by fingerprint, however no specific mass signals were denoted when using gold nanoparticles to analyse biological samples. An alternate method using the colorimetric properties of gold nanoparticles was employed for detection. This method inspired in the non-cross-linking assay allowed the identification of glycidamide-guanine adducts and DNA adducts generated in vitro. For the development of a model of exposure, two different aquatic organisms were studies: a goldfish and a mussel. Organisms were exposed to waterborne acrylamide, after which mortality was recorded and effect concentrations were estimated. In goldfish, both genotoxicity and metabolic alterations were assessed and revealed dose-effect relationships of acrylamide. Histopathological alterations were verified primarily in pancreatic cells, but also in hepatocytes. Mussels showed higher effect concentrations than goldfish. Biomarkers of oxidative stress, biotransformation and neurotoxicity were analysed after prolonged exposure, showing mild oxidative stress in mussel cells, and induction of enzymes involved in detoxification of oxygen radicals. A qualitative histopathological screening revealed gonadotoxicity in female mussels, which may present some risk to population equilibrium.

Individualizing exposure therapy of PTSD: the case of Caroline

In therapy for chronic posttraumatic stress disorder (PTSD), prolonged exposure (PE) to stimuli associated with an original trauma experience is considered a state-of-the-art treatment method. The present case report outlines the use of Foa and Rothbaum's (1998) manual for this type of treatment in the year-long, 40-session treatment of Caroline, an adult female victim of child sexual abuse. The manual was supplemented by Caspar's (1995, 2007) Plan Analysis technique for individualized case formulation and treatment planning, along with Caspar's concept of the Motive-Oriented Therapeutic Relationship (MOTR). As indicated by standardized, quantitative measures, by changes in the client's behavior patterns, and by the client's subjective report, the treatment was very effective. An analysis of the therapy process illustrates the importance of a combination of manual-based procedures with individualized case formulations and interventions. The case is discussed in the context of enhancing the cognitive-behavioral treatment of PTSD.

Different addictive drug exposure induces selective alterations of the Endogenous Opioid System : modulation of transcription and epigenetic mechanisms

Drug addiction manifests clinically as compulsive drug seeking, and cravings that can persist and recur even after extended periods of abstinence. The fundamental principle that unites addictive drugs is that each one enhances synaptic DA by means that dissociate it from normal behavioral control, so that they act to reinforce their own acquisition. Our attention has focused on the study of phenomena associated with the consumption of alcohol and heroin. Alcohol has long been considered an unspecific pharmacological agent, recent molecular pharmacology studies have shown that acts on different primary targets. Through gene expression studies conducted recently it has been shown that the classical opioid receptors are differently involved in the consumption of ethanol and, furthermore, the system nociceptin / NOP, included in the family of endogenous opioid system, and both appear able to play a key role in the initiation of alcohol use in rodents. What emerges is that manipulation of the opioid system, nociceptin, may be useful in the treatment of addictions and there are several evidences that support the use of this strategy. The linkage between gene expression alterations and epigenetic modulation in PDYN and PNOC promoters following alcohol treatment confirm the possible chromatin remodeling mechanism already proposed for alcoholism. In the second part of present study, we also investigated alterations in signaling molecules directly associated with MAPK pathway in a unique collection of postmortem brains from heroin abusers. The interest was focused on understanding the effects that prolonged exposure of heroin can cause in an individual, over the entire MAPK cascade and consequently on the transcription factor ELK1, which is regulated by this pathway. We have shown that the activation of ERK1/2 resulting in Elk-1 phosphorylation in striatal neurons supporting the hypothesis that prolonged exposure to substance abuse causes a dysregulation of MAPK pathway.

Influence of PH3 exposure on silicon substrate morphology in the MOVPE growth of III-V on silicon multijunction solar cells

Dual-junction solar cells formed by a GaAsP or GaInP top cell and a silicon bottom cell seem to be attractive candidates to materialize the long sought-for integration of III-V materials on silicon for photovoltaic applications. One of the first issues to be considered in the development of this structure will be the strategy to create the silicon emitter of the bottom subcell. In this study, we explore the possibility of forming the silicon emitter by phosphorus diffusion (i.e. exposing the wafer to PH3 in a MOVPE reactor) and still obtain good surface morphologies to achieve a successful III-V heteroepitaxy as occurs in conventional III-V on germanium solar cell technology. Consequently, we explore the parameter space (PH3 partial pressure, time and temperature) that is needed to create optimized emitter designs and assess the impact of such treatments on surface morphology using atomic force microscopy. Although a strong degradation of surface morphology caused by prolonged exposure of silicon to PH3 is corroborated, it is also shown that subsequent anneals under H-2 can recover silicon surface morphology and minimize its RMS roughness and the presence of pits and spikes.

Accessing occupational exposure to fungi in a cork industry

Different forms of fungal diseases affecting the nose and paranasal sinuses are recognized, including invasive and non-invasive fungal rhinosinusitis. Penicillium glabrum complex is associated with respiratory diseases such as suberosis, a typical disease of cork industry workers. In addition, Chrysonilia sitophila has been described as causing occupational asthma, associated to prolonged exposure to high counts of spores. In this study we aimed to access fungal exposure in workers from one cork industry through the mycological analysis of their nasal exudate and the environmental fungal contamination of their surroundings as well.