1,165 research outputs found

    Synthesis and characterization of a metal complex containing naringin and Cu, and its antioxidant, antimicrobial, antiinflammatory and tumor cell cytotoxicity

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    The antioxidant activity of flavonoids is believed to increase when they are coordinated with transition metal ions. However, the literature on this subject is contradictory and the outcome seems to largely depend on the experimental conditions. In order to understand the contribution of the metal coordination and the type of interaction between a flavonoid and the metal ion, in this study a new metal complex of Cu (II) with naringin was synthesized and characterized by FT-IR, UV-VIS, mass spectrometry (ESI-MS/MS), elemental analysis and H-1-NMR. The results of these analyses indicate that the complex has a Cu (II) ion coordinated via positions 4 and 5 of the flavonoid. The antioxidant, anti-inflammatory and antimicrobial activities of this complex were studied and compared with the activity of free naringin. The Naringin-Cu. (H) complex 1 showed higher antioxidant, anti-inflammatory and tumor cell cytoxicity activities than free naringin without reducing cell viability.1271352136

    Merging Resource Availability with Isotope Mixing Models: The Role of Neutral Interaction Assumptions

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    Background: Bayesian mixing models have allowed for the inclusion of uncertainty and prior information in the analysis of trophic interactions using stable isotopes. Formulating prior distributions is relatively straightforward when incorporating dietary data. However, the use of data that are related, but not directly proportional, to diet (such as prey availability data) is often problematic because such information is not necessarily predictive of diet, and the information required to build a reliable prior distribution for all prey species is often unavailable. Omitting prey availability data impacts the estimation of a predator's diet and introduces the strong assumption of consumer ultrageneralism (where all prey are consumed in equal proportions), particularly when multiple prey have similar isotope values. Methodology: We develop a procedure to incorporate prey availability data into Bayesian mixing models conditional on the similarity of isotope values between two prey. If a pair of prey have similar isotope values (resulting in highly uncertain mixing model results), our model increases the weight of availability data in estimating the contribution of prey to a predator's diet. We test the utility of this method in an intertidal community against independently measured feeding rates. Conclusions: Our results indicate that our weighting procedure increases the accuracy by which consumer diets can be inferred in situations where multiple prey have similar isotope values. This suggests that the exchange of formalism for predictive power is merited, particularly when the relationship between prey availability and a predator's diet cannot be assumed for all species in a system.National Science Foundation (NSF) [DEB-0608178]U.S. Environmental Protection AgencyDepartment of EducationSigma XiUniversity of ChicagoFundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)(CAPES) Coordenacao de Aperfeicoamento de Pessoal de Nivel Superiori

    The Pseudomonas Quinolone Signal (PQS) Balances Life and Death in Pseudomonas aeruginosa Populations

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    When environmental conditions deteriorate and become inhospitable, generic survival strategies for populations of bacteria may be to enter a dormant state that slows down metabolism, to develop a general tolerance to hostile parameters that characterize the habitat, and to impose a regime to eliminate damaged members. Here, we provide evidence that the pseudomonas quinolone signal (PQS) mediates induction of all of these phenotypes. For individual cells, PQS, an interbacterial signaling molecule of Pseudomonas aeruginosa, has both deleterious and beneficial activities: on the one hand, it acts as a pro-oxidant and sensitizes the bacteria towards oxidative and other stresses and, on the other, it efficiently induces a protective anti-oxidative stress response. We propose that this dual function fragments populations into less and more stress tolerant members which respond differentially to developing stresses in deteriorating habitats. This suggests that a little poison may be generically beneficial to populations, in promoting survival of the fittest, and in contributing to bacterial multi-cellular behavior. It further identifies PQS as an essential mediator of the shaping of the population structure of Pseudomonas and of its response to and survival in hostile environmental conditions

    Prevalence of nonmedical methamphetamine use in the United States

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    <p>Abstract</p> <p>Background</p> <p>Illicit methamphetamine use continues to be a public health concern in the United States. The goal of the current study was to use a relatively inexpensive methodology to examine the prevalence and demographic correlates of nonmedical methamphetamine use in the United States.</p> <p>Methods</p> <p>The sample was obtained through an internet survey of noninstitutionalized adults (n = 4,297) aged 18 to 49 in the United States in 2005. Propensity weighting methods using information from the U.S. Census and the 2003 National Survey on Drug Use and Health (NSDUH) were used to estimate national-level prevalence rates.</p> <p>Results</p> <p>The overall prevalence of current nonmedical methamphetamine use was estimated to be 0.27%. Lifetime use was estimated to be 8.6%. Current use rates for men (0.32%) and women (0.23%) did not differ, although men had a higher 3-year prevalence rate (3.1%) than women (1.1%). Within the age subgroup with the highest overall methamphetamine use (18 to 25 year olds), non-students had substantially higher methamphetamine use (0.85% current; 2.4% past year) than students (0.23% current; 0.79% past year). Methamphetamine use was not constrained to those with publicly funded health care insurance.</p> <p>Conclusion</p> <p>Through the use of an internet panel weighted to reflect U.S. population norms, the estimated lifetime prevalence of methamphetamine use among 18 to 49 year olds was 8.6%. These findings give rates of use comparable to those reported in the 2005 NSDUH. Internet surveys are a relatively inexpensive way to provide complimentary data to telephone or in-person interviews.</p

    Temporal Controls of the Asymmetric Cell Division Cycle in Caulobacter crescentus

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    The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, biochemical and physiological properties of proliferating bacteria. Different controls for both swarmer and stalked cell cycles are represented in the mathematical scheme. The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions. Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella)

    Does the mind map learning strategy facilitate information retrieval and critical thinking in medical students?

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    <p>Abstract</p> <p>Background</p> <p>A learning strategy underutilized in medical education is mind mapping. Mind maps are multi-sensory tools that may help medical students organize, integrate, and retain information. Recent work suggests that using mind mapping as a note-taking strategy facilitates critical thinking. The purpose of this study was to investigate whether a relationship existed between mind mapping and critical thinking, as measured by the Health Sciences Reasoning Test (HSRT), and whether a relationship existed between mind mapping and recall of domain-based information.</p> <p>Methods</p> <p>In this quasi-experimental study, 131 first-year medical students were randomly assigned to a standard note-taking (SNT) group or mind map (MM) group during orientation. Subjects were given a demographic survey and pre-HSRT. They were then given an unfamiliar text passage, a pre-quiz based upon the passage, and a 30-minute break, during which time subjects in the MM group were given a presentation on mind mapping. After the break, subjects were given the same passage and wrote notes based on their group (SNT or MM) assignment. A post-quiz based upon the passage was administered, followed by a post-HSRT. Differences in mean pre- and post-quiz scores between groups were analyzed using independent samples <it>t</it>-tests, whereas differences in mean pre- and post-HSRT total scores and subscores between groups were analyzed using ANOVA. Mind map depth was assessed using the Mind Map Assessment Rubric (MMAR).</p> <p>Results</p> <p>There were no significant differences in mean scores on both the pre- and post-quizzes between note-taking groups. And, no significant differences were found between pre- and post-HSRT mean total scores and subscores.</p> <p>Conclusions</p> <p>Although mind mapping was not found to increase short-term recall of domain-based information or critical thinking compared to SNT, a brief introduction to mind mapping allowed novice MM subjects to perform similarly to SNT subjects. This demonstrates that medical students using mind maps can successfully retrieve information in the short term, and does not put them at a disadvantage compared to SNT students. Future studies should explore longitudinal effects of mind-map proficiency training on both short- and long-term information retrieval and critical thinking.</p

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Cost effectiveness of epidural steroid injections to manage chronic lower back pain

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    Background The efficacy of epidural steroid injections in the management of chronic low back pain is disputed, yet the technique remains popular amongst physicians and patients alike. This study assesses the cost effectiveness of injections administered in a routine outpatient setting in England. Methods Patients attending the Nottingham University Hospitals’ Pain Clinic received two injections of methylprednisolone plus levobupivacaine at different dosages, separated by at least 12 weeks. Prior to each injection, and every week thereafter for 12 weeks, participants completed the EQ-5D health-related quality of life instrument. For each patient for each injection, total health state utility gain relative to baseline was calculated. The cost of the procedure was modelled from observed clinical practice. Cost effectiveness was calculated as procedure cost relative to utility gain. Results 39 patients provided records. Over a 13-week period commencing with injection, mean quality adjusted life year (QALY) gains per patient for the two dosages were 0.028 (SD 0.063) and 0.021 (SD 0.057). The difference in QALYs gained by dosage was insignificant (paired t-test, CIs -0.019 – 0.033). Based on modelled resource use and data from other studies, the mean cost of an injection was estimated at £219 (SD 83). The cost utility ratio of the two injections amounted to £8,975 per QALY gained (CIs 5,480 – 22,915). However, at costs equivalent to the tariff price typically paid to providers by health care purchasers, the ratio increased to £27,459 (CIs 16,779 – 70,091). Conclusions When provided in an outpatient setting, epidural steroid injections are a short term, but nevertheless cost effective, means of managing chronic low back pain. However, designation of the procedure as a day case requires the National Health Service to reimburse providers at a price which pushes the procedure to the margin of cost effectiveness

    Does Proximity to Retailers Influence Alcohol and Tobacco Use Among Latino Adolescents?

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    Despite decades of research surrounding determinants of alcohol and tobacco (A&T) use among adolescents, built environment influences have only recently been explored. This study used ordinal regression on 205 Latino adolescents to explore the influence of the built environment (proximity to A&T retailers) on A&T use, while controlling for recognized social predictors. The sample was 45% foreign-born. A&T use was associated with distance from respondents’ home to the nearest A&T retailer (−), acculturation (+), parents’ consistent use of contingency management (−), peer use of A&T (+), skipping school (+), attending school in immediate proximity to the US/Mexico border (+), and the interaction between the distance to the nearest retailer and parents’ consistent use of contingency management (+). The association between decreasing distance to the nearest A&T retailer and increased A&T use in Latino adolescents reveals an additional risk behavior determinant in the US–Mexico border region
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