931 resultados para Current-potential


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Parastichopus regalis (Cuvier, 1817) is the most expensive seafood product on the Catalonian market (NE Spain), with prices at approximately 130 €/Kg (fresh weight). Despite its ecological and economic importance, biological and genetic information on this sea cucumber species is scarce. Here, we provide both the first insight on the genetic structure of P. regalis using sequences of cytochrome oxidase I (COI) and 16S genes and a morphological description of its population. Individual sea cucumbers were collected in six locations along the Spanish Mediterranean coast, including an area under fishery pressure (Catalonia). We found high haplotype diversity and low nucleotide diversity for both genes, with higher levels of genetic diversity observed in the COI gene. The population pairwise fixation index (FST), AMOVA and correspondence analysis (CA) based on the COI gene revealed significant genetic differentiation among some locations. However, further analysis using nuclear markers (e.g., microsatellites) is necessary to corroborate these results. Moreover, the genetic and morphological data may indicate fishery effects on the Catalonian population with a decrease in the size and weight averages and lower genetic diversity compared with locations that lack fishery pressure. For the appropriate management of this species, we suggest the following: 1) accurately assessing the stock status along the Spanish coasts; 2) studying the reproductive cycle of this target species and the establishment of a closed fishery season according to the reproductive cycle; and 3) establishing protected areas (i.e., not take zones) to conserve healthy populations and favour recruitment in the nearby areas.

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A pressão humana sobre os serviços ecossistêmicos tem resultado em impactos indesejáveis sobre o bem-estar humano. Com o Projeto Millennium, várias pesquisas interdisciplinares têm sido desenvolvidas em todo o mundo com o objetivo de entender esses impactos sobre os fluxos e os processos dos ecossistemas e internalizar os custos e os benefícios dos serviços ecossistêmicos para a produção. O solo fornece muitos serviços ecossistêmicos, uma vez que sua multifuncionalidade é a base para a produção de alimentos, filtração de água, ciclagem de nutrientes e outros bens essenciais à vida. Este artigo apresenta os principais conceitos e classificações dos serviços ecossistêmicos do solo e de suas funções; os indicadores e os métodos de avaliação, modelagem e valoração dos serviços ecossistêmicos; algumas aplicações recentes para avaliar impactos de práticas de manejo agrícola sobre os serviços ecossistêmicos do solo; bem como os desafios e as oportunidades para a pesquisa e para o desenvolvimento de políticas públicas relacionadas à sustentabilidade agroambiental no Brasil. Apesar de o papel do solo para prestação de serviços ecossistêmicos ainda ser subestimado, os cientistas têm gradualmente reconhecido os processos e as funções do solo como fundamentais para avaliar os serviços ecossistêmicos e os efeitos do uso e manejo da terra sobre eles. Abordagens interdisciplinares que integrem ciência e políticas públicas são necessárias para construir uma governança com base em serviços ecossistêmicos

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Cardiac arrhythmias are one of the main causes of death worldwide. Several studies have shown that inflammation plays a key role in different cardiac diseases and Toll-like receptors (TLRs) seem to be involved in cardiac complications. In the present study, we investigated whether the activation of TLR4 induces cardiac electrical remodeling and arrhythmias, and the signaling pathway involved in these effects. Membrane potential was recorded in Wistar rat ventricle. Ca(2+) transients, as well as the L-type Ca(2+) current (ICaL) and the transient outward K(+) current (Ito), were recorded in isolated myocytes after 24 h exposure to the TLR4 agonist, lipopolysaccharide (LPS, 1 μg/ml). TLR4 stimulation in vitro promoted a cardiac electrical remodeling that leads to action potential prolongation associated with arrhythmic events, such as delayed afterdepolarization and triggered activity. After 24 h LPS incubation, Ito amplitude, as well as Kv4.3 and KChIP2 mRNA levels were reduced. The Ito decrease by LPS was prevented by inhibition of interferon regulatory factor 3 (IRF3), but not by inhibition of interleukin-1 receptor-associated kinase 4 (IRAK4) or nuclear factor kappa B (NF-κB). Extrasystolic activity was present in 25% of the cells, but apart from that, Ca(2+) transients and ICaL were not affected by LPS; however, Na(+)/Ca(2+) exchanger (NCX) activity was apparently increased. We conclude that TLR4 activation decreased Ito, which increased AP duration via a MyD88-independent, IRF3-dependent pathway. The longer action potential, associated with enhanced Ca(2+) efflux via NCX, could explain the presence of arrhythmias in the LPS group.

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Nitrofurazone (NF) presents activity against Chagas' disease, yet it has a high toxicity. Its analog, hydroxymethylnitrofurazone (NFOH), is more potent against Trypanosoma cruzi and much less toxic than the parent drug, NF. The electrochemical reduction of NFOH in an aqueous medium using a glassy carbon electrode (GCE) is presented. By cyclic voltammetry in anacidic medium, one irreversible reduction peak related to hydroxylamine derivative formation was registered, being linearly pH dependent. However, from pH > 7, a reversible reduction peak at a more positive potential appears and corresponds to the formation of a nitro radical anion. The radical-anion kinetic stability was evaluated by Ip(a)/Ip(c) the current ratio of the R-NO(2)/R-NO(2)-redox couple. The nitro radical anion decays with a second-order rate constant (k(2)) of 6.07, 2.06, and 1.44(X 10(3)) L mol(-1) s(-1) corresponding to pH 8.29, 9.29, and 10.2, respectively, with a corresponding half-time life (t(1/2)) of 0.33, 0.97, and 1.4 s for each pH value. By polishing the GCE surface with diamond powder and comparing with the GCE surface polished with alumina, it is shown that the presence of alumina affects the lifetime of the nitro radical anion. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3130082] All rights reserved.

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Cleft lip and palate (CLP), one of the most frequent congenital malformations, affects the alveolar bone in the great majority of the cases, and the reconstruction of this defect still represents a challenge in the rehabilitation of these patients. One of the current most promising strategy to achieve this goal is the use of bone marrow stem cells (BMSC); however, isolation of BMSC or iliac bone, which is still the mostly used graft in the surgical repair of these patients, confers site morbidity to the donor. Therefore, in order to identify a new alternative source of stem cells with osteogenic potential without conferring morbidity to the donor, we have used orbicular oris muscle (OOM) fragments, which are regularly discarded during surgery repair (cheiloplasty) of CLP patients. We obtained cells from OOM fragments of four unrelated CLP patients (CLPMDSC) using previously described preplating technique. These cells, through flow cytometry analysis, were mainly positively marked for five mesenchymal stem cell antigens (CD29, CD90, CD105, SH3, and SH4), while negative for hematopoietic cell markers, CD14, CD34, CD45, and CD117, and for endothelial cell marker, CD31. After induction under appropriate cell culture conditions, these cells were capable to undergo chondrogenic, adipogenic, osteogenic, and skeletal muscle cell differentiation, as evidenced by immunohistochemistry. We also demonstrated that these cells together with a collagen membrane lead to bone tissue reconstruction in a critical-size cranial defects previously induced in non-immunocompromised rats. The presence of human DNA in the new bone was confirmed by PCR with human-specific primers and immunohistochemistry with human nuclei antibodies. In conclusion, we showed that cells from OOM have phenotypic and behavior characteristics similar to other adult stem cells, both in vitro and in vivo. Our findings suggest that these cells represent a promising source of stem cells for alveolar bone grafting treatment, particularly in young CLP patients.

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The sustainability of current harvest practices for high-value Meliaceae can be assessed by quantifying logging intensity and projecting growth and survival by post-logging populations over anticipated intervals between harvests. From 100%-area inventories of big-leaf mahogany (Swietenia macrophylla) covering 204 ha or more at eight logged and unlogged forest sites across southern Brazilian Amazonia, we report generally higher landscape-scale densities and smaller population-level mean diameters in eastern forests compared to western forests, where most commercial stocks survive. Density of trees >= 20 cm diameter varied by two orders of magnitude and peaked at 1.17 ha(-1). Size class frequency distributions appeared unimodal at two high-density sites, but were essentially arnodal or flat elsewhere; diameter increment patterns indicate that populations were multi- or all-aged. At two high-density sites, conventional logging removed 93-95% of commercial trees (>= 45 cm diameter at the time of logging), illegally eliminated 31-47% of sub-merchantable trees, and targeted trees as small as 20 cm diameter. Projected recovery by commercial stems during 30 years after conventional logging represented 9.9-37.5% of initial densities and was highly dependent on initial logging intensity and size class frequency distributions of commercial trees. We simulated post-logging recovery over the same period at all sites according to the 2003 regulatory framework for mahogany in Brazil, which raised the minimum diameter cutting limit to 60 cm and requires retention during the first harvest of 20% of commercial-sized trees. Recovery during 30 years ranged from approximately 0 to 31% over 20% retention densities at seven of eight sites. At only one site where sub-merchantable trees dominated the population did the simulated density of harvestable stems after 30 years exceed initial commercial densities. These results indicate that 80% harvest intensity will not be sustainable over multiple cutting cycles for most populations without silvicultural interventions ensuring establishment and long-term growth of artificial regeneration to augment depleted natural stocks, including repeated tending of outplanted seedlings. Without improved harvest protocols for mahogany in Brazil as explored in this paper, future commercial supplies of this species as well as other high-value tropical timbers are endangered. Rapid changes in the timber industry and land-use in the Amazon are also significant challenges to sustainable management of mahogany. (C) 2007 Elsevier B.V. All rights reserved.

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Crop rotation can play a valuable role in managing plant parasitic nematodes, depending on the availability of profitable non-host or poor host crops. Alternatively, non-host cover crops or green manures can be used in succession to summer cash Crops for this Purpose. The aim of the current study was to evaluate, under greenhouse conditions, the host status of commercial hybrids and cultivars of grain and silage sorghum (Sorghum bicolor) for Meloidogyne javanica, and to assess the effect of sorghum on nematode population in comparison with pearl millet (poor host for M. javanica), showy crotalaria and sunn hemp (both non-hosts). Based on two experiments, it was stated that, as a rule, grain sorghum is a poor host for M. javanica, but silage sorghum is a good host. Silage sorghum `BRS 601` was an exception. In other experiments, grain sorghum, pearl millet (Pennisetum glaucum `BN 2`), showy crotalaria (Crotolaria spectabilis `Comum`) and sunn hemp (C. juncea `IAC-KR-1`) reduced M. javanica population level, while silage sorghum increased the nematode density.

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Globalisation, increasing complexity, and the need to address triple-bottom line sustainability has seen the proliferation of Learning Organisations (LO) who, by definition, have the capacity to anticipate environmental changes and economic opportunities and adapt accordingly. Such organisations use system dynamics modelling (SDM) for both strategic planning and the promotion of organisational learning. Although SDM has been applied in the context of tourism destination management for predictive reasons, the current literature does not analyse or recognise how this could be used as a foundation for an LO. This study introduces the concept of the Learning Tourism Destinations (LTD) and discusses, on the basis of a review of 6 case studies, the potential of SDM as a tool for the implementation and enhancement of collective learning processes. The results reveal that SDM is capable of promoting communication between stakeholders and stimulating organisational learning. It is suggested that the LTD approach be further utilised and explored.

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Despite the widespread use of psychological debriefing, serious concerns have been raised about its effectiveness and potential to do harm. 1 2 Psychological debriefing is broadly defined as a set of procedures including counselling and the giving of information aimed at preventing psychological morbidity and aiding recovery after a traumatic event. In 1995 Raphael and colleagues emphasised that there was an urgent need for reliable evidence from randomised controlled trials on the impact and worth of debriefing.3 Unfortunately, the news has not been good for debriefing. Debriefing is generally applied within the first few days after a traumatic event, lasts one to three hours, and usually includes procedures that encourage and normalise emotional expression. Debriefing can also be more narrowly defined in terms of the procedures used, the information provided and the target population. One example of this type of debriefing is known as critical incident stress debriefing.4

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Objectives-To investigate the feasibility of selective screening for abdominal aortic aneurysm (AAA) based on identification of a target group of manageable size defined by risk factors for AAA. Setting-Male residents of Perth, Western Australia, aged 65-83 years, who participated in a randomised controlled trial of ultrasound screening for AAA. Methods-Eligible men were identified from the electoral roll and invited to attend a screening clinic. Those who attended completed a questionnaire, had a limited physical examination, and underwent an ultrasound examination to identify the maximum diameter of the infrarenal aorta. Data on risk factors collected from the first 8995 men seen were used to calculate a multivariate risk score for the remaining 2755 men who were screened. Gentiles of the risk score were used to define potential target groups for screening and the sensitivity and specificity of each of these selective screening strategies were calculated. We repeated the calculation separately for AAAs of at least 30 mm, 40 mm, and 50 mm in diameter. Results-We found that screening half of the male population aged 65-83 years would find approximately 75% of AAAs, regardless of their size, whereas screening only current smokers in this population would find approximately 20% of AAAs. Conclusions-Selective screening for AAA using easily recognisable risk factors is feasible but is not worthwhile as approximately 25% of clinically significant cases would be missed.

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Background: Despite significant advancements in psychopharmacology, treating major depressive disorder (MDD) is still a challenge considering the efficacy, tolerability, safety, and economical costs of most antidepressant drugs. One approach that has been increasingly investigated is modulation of cortical activity with tools of non-invasive brain stimulation - such as transcranial magnetic stimulation and transcranial direct current stimulation (tDCS). Due to its profile, tDCS seems to be a safe and affordable approach. Methods and design: The SELECT TDCS trial aims to compare sertraline vs. tDCS in a double-blinded, randomized, factorial trial enrolling 120 participants to be allocated to four groups to receive sertraline + tDCS, sertraline, tDCS or placebo. Eligibility criteria are moderate-to-severe unipolar depression (Hamilton Depression Rating Scale >17) not currently on sertraline treatment. Treatment will last 6 weeks and the primary outcome is depression change in the Montgomery-Asberg Depression Rating Score (MADRS). Potential biological markers that mediate response, such as BDNF serum levels, Val66Met BDNF polymorphism, and heart rate variability will also be examined. A neuropsychological battery with a focus on executive functioning will be administered. Discussion: With this design we will be able to investigate whether tDCS is more effective than placebo in a sample of patients free of antidepressants and in addition, we will be able to secondarily compare the effect sizes of sertraline vs. tDCS and also the comparison between tDCS and combination of tDCS and sertraline. (C) 2010 Elsevier Inc. All rights reserved.

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Preliminary findings suggest that transcranial direct current stimulation (tDCS) can have antidepressant effects. We sought to test this further in a parallel-group, double-blind clinical trial with 40 patients with major depression, medication-free randomized into three groups of treatment: anodal tDCS of the left dorsolateral prefrontal cortex (active group-`DLPFC`); anodal tDCS of the occipital cortex (active control group-`occipital`) and sham tDCS (placebo control group-`sham`). tDCS was applied for 10 sessions during a 2-wk period. Mood was evaluated by a blinded rater using the Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI). The treatment was well tolerated with minimal side-effects that were distributed equally across all treatment groups. We found significantly larger reductions in depression scores after DLPFC tDCS [HDRS reduction of 40.4 % (+/-25.8%)] compared to occipital [HDRS reduction of 21.3 % ( +/-12.9%)] and sham tDCS [HDRS reduction of 10.4 % (+/-36.6%)]. The beneficial effects of tDCS in the DLPFC group persisted for 1 month after the end of treatment. Our findings support further investigation on the effects of this novel potential therapeutic approach - tDCS - for the treatment of major depression.

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Principal cells of the medial nucleus of the trapezoid body (MNTB) are simple round neurons that receive a large excitatory synapse (the calyx of Held) and many small inhibitory synapses on the soma. Strangely, these neurons also possess one or two short tufted dendrites, whose function is unknown. Here we assess the role of these MNTB cell dendrites using patch-clamp recordings, imaging and immunohistochemistry techniques. Using outside-out patches and immunohistochemistry, we demonstrate the presence of dendritic Na(+) channels. Current-clamp recordings show that tetrodotoxin applied onto dendrites impairs action potential (AP) firing. Using Na(+) imaging, we show that the dendrite may serve to maintain AP amplitudes during high-frequency firing, as Na(+) clearance in dendritic compartments is faster than axonal compartments. Prolonged high-frequency firing can diminish Na(+) gradients in the axon while the dendritic gradient remains closer to resting conditions; therefore, the dendrite can provide additional inward current during prolonged firing. Using electron microscopy, we demonstrate that there are small excitatory synaptic boutons on dendrites. Multi-compartment MNTB cell simulations show that, with an active dendrite, dendritic excitatory postsynaptic currents (EPSCs) elicit delayed APs compared with calyceal EPSCs. Together with high- and low-threshold voltage-gated K(+) currents, we suggest that the function of the MNTB dendrite is to improve high-fidelity firing, and our modelling results indicate that an active dendrite could contribute to a `dual` firing mode for MNTB cells (an instantaneous response to calyceal inputs and a delayed response to non-calyceal dendritic excitatory postsynaptic potentials).

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Objective: Meningococcal disease continues to be a serious public health concern, being associated with high morbidity and mortality rates in many countries from Latin America. In addition to discussing recent changes in the epidemiology of meningococcal disease in the region, we also analyse the development and potential impact of new vaccines on the prevention of meningococcal disease. Methods: MEDLINE, SciELO, LILACS and websites of the national Ministries of Health databases were searched using the terms meningococcal disease, meningococcal epidemiology, Neisseria meningitidis, meningococcal vaccines and the name of Latin America countries, from 1998 to 2008, with emphasis on review articles, clinical trials and epidemiological studies. Results: Epidemiology of meningococcal disease in Latin America is characterized by marked differences from country to country. The overall incidence of meningococcal disease per year varied from less than 0.1 cases per 100,000 inhabitants in countries like Mexico to two cases per 100,000 inhabitants in Brazil. The highest age-specific incidence of meningococcal disease occurred in infants less than 1 year of age. Serogroups B and C were responsible for the majority of cases reported, but the emergence of serogroups W135 and Y was reported in some countries. Serogroup A disease is now rare in Latin America. Discussion: Although a few countries have established meningitis surveillance programs, the information is not uniform, and the quality of the reported data is poor in the majority of the region. The availability of new effective meningococcal conjugate vaccines and promising protein-based vaccine candidates against meningococcus B highlights the importance of a better understanding of the true burden of meningococcal disease in Latin America and also the need for cost-effectiveness studies before incorporating the new meningococcal vaccines to national immunization programs.

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Background: There is little, though growing, interest in the research area of attitudes held among physicians towards disclosing the diagnosis of dementia and Alzheimer`s disease (AD), or the current practice on AD disclosure. This study aimed to investigate the practice and attitudes of specialized physicians towards AD diagnosis disclosure in Brazil. Methods: A questionnaire was devised to survey the current practice and attitudes regarding diagnosis disclosure of AD in Brazil and sent to specialized physicians (170 geriatricians, 300 neurologists and 500 psychiatrists) by electronic mail. Results: From 970 potential respondents, 181 physicians who usually attend AD patients returned the questionnaire. There were no significant differences between the three specialties regarding the frequency with which they informed patients of their AD diagnosis (p = 0.17). The results revealed that only 44.8% of the physicians would regularly inform the patient of the diagnosis, although 85.6% of these use clear terminology. Despite their usual practice, 76.8% would want to know their diagnosis if they themselves were affected by AD. Conclusions: Disclosure of AD diagnosis is not common among specialized physicians in Brazil and different factors are involved. In the clinical context, discussion on advantages of diagnosis disclosure can be useful for improving the care of AD patients and their families.