769 research outputs found

    Common carp (Cyprinus carpio L.) alters its feeding niche in response to changing food resources: direct observations in simulated ponds

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    We used customized fish tanks as model fish ponds to observe grazing, swimming, and conspecific social behavior of common carp (Cyprinus carpio) under variable food-resource conditions to assess alterations in feeding niche. Different food and feeding situations were created by using only pond water or pond water plus pond bottom sediment or pond water plus pond bottom sediment and artificial feeding. All tanks were fertilized twice, prior to stocking and 2 weeks later after starting the experiment to stimulate natural food production. Common carp preferred artificial feed over benthic macroinvertebrates, followed by zooplankton. Common carp did not prefer any group of phytoplankton in any treatment. Common carp was mainly benthic in habitat choice, feeding on benthic macroinvertebrates when only plankton and benthic macroinvertebrates were available in the system. In the absence of benthic macroinvertebrates, their feeding niche shifted from near the bottom of the tanks to the water column where they spent 85% of the total time and fed principally on zooplankton. Common carp readily switched to artificial feed when available, which led to better growth. Common carp preferred to graze individually. Behavioral observations of common carp in tanks yielded new information that assists our understanding of their ecological niche. This knowledge could be potentially used to further the development of common carp aquaculture

    Implementation of Web-Based Respondent-Driven Sampling among Men who Have Sex with Men in Vietnam

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    Objective: Lack of representative data about hidden groups, like men who have sex with men (MSM), hinders an evidence-based response to the HIV epidemics. Respondent-driven sampling (RDS) was developed to overcome sampling challenges in studies of populations like MSM for which sampling frames are absent. Internet-based RDS (webRDS) can potentially circumvent limitations of the original RDS method. We aimed to implement and evaluate webRDS among a hidden population. Methods and Design: This cross-sectional study took place 18 February to 12 April, 2011 among MSM in Vietnam. Inclusion criteria were men, aged 18 and above, who had ever had sex with another man and were living in Vietnam. Participants were invited by an MSM friend, logged in, and answered a survey. Participants could recruit up to four MSM friends. We evaluated the system by its success in generating sustained recruitment and the degree to which the sample compositions stabilized with increasing sample size. Results: Twenty starting participants generated 676 participants over 24 recruitment waves. Analyses did not show evidence of bias due to ineligible participation. Estimated mean age was 22 year and 82% came from the two large metropolitan areas. 32 out of 63 provinces were represented. The median number of sexual partners during the last six months was two. The sample composition stabilized well for 16 out of 17 variables. Conclusion: Results indicate that webRDS could be implemented at a low cost among Internet-using MSM in Vietnam. WebRDS may be a promising method for sampling of Internet-using MSM and other hidden groups. Key words: Respondent-driven sampling, Online sampling, Men who have sex with men, Vietnam, Sexual risk behavio

    Anticancer Gene Transfer for Cancer Gene Therapy

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    Gene therapy vectors are among the treatments currently used to treat malignant tumors. Gene therapy vectors use a specific therapeutic transgene that causes death in cancer cells. In early attempts at gene therapy, therapeutic transgenes were driven by non-specific vectors which induced toxicity to normal cells in addition to the cancer cells. Recently, novel cancer specific viral vectors have been developed that target cancer cells leaving normal cells unharmed. Here we review such cancer specific gene therapy systems currently used in the treatment of cancer and discuss the major challenges and future directions in this field

    Family history in stone disease: how important is it for the onset of the disease and the incidence of recurrence?

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    The aim of this study was to evaluate the possible effect of a positive family history on the age at the onset of urinary stone disease and the frequency of subsequent symptomatic episodes relating to the disease. Between March 2006 and April 2009, patients with either a newly diagnosed or a previously documented stone disease were included in the study program. They were required to fill in a questionnaire and divided into two groups according to the positive family history of stone disease; group I comprised patients with a family history for urinary calculi and group II those without. Depending on the data obtained from questionnaires, all patients were evaluated in detail with respect to the age at the onset of the stone disease, stone passage and interventions over time, time to first recurrence (time interval between the onset of the disease and the first recurrence), number of total stone episodes and recurrence intervals. 1,595 patients suffering from urolithiasis with the mean age of 41.7 (14–69 years) were evaluated with respect to their past history of the disease. There were 437 patients in group I and 1,158 in group II. There was no statistically significant difference between the mean age value of two groups (P = 0.09). When both genders in group I were analyzed separately, female patients tended to have higher rate of family history positivity than males. Comparative evaluation of the age at the onset of the disease between the two groups did reveal that stone formation occured at younger ages in patients with positive family history [P = 0.01 (males), P = 0.01 (females)] and the mean age of onset of the disease was lower in males than females in group I (P = 0.01). Patients in group I had relatively more stone episodes from the onset of the disease [P < 0.01 (2–4 episodes), P < 0.01 (≥5 episodes)]. Male patients were associated with higher number of stone episodes (P = 0.01). Mean time interval between recurrences was noted to be significantly shorter in group I patients when compared with patients in group II [P < 0.01 (males), P = 0.02 (females)]. In conclusion, our results showed that urinary stone formation may occur at younger ages and that the frequency of symptom episodes may be higher in patients with a positive family history. We believe that the positive family history for urinary stone disease could give us valuable information concerning the onset as well as the severity of the disease

    Benzodiazepine Use and Misuse Among Patients in a Methadone Program

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    <p>Abstract</p> <p>Background</p> <p>Benzodiazepines (BZD) misuse is a serious public health problem, especially among opiate-dependent patients with anxiety enrolled in methadone program because it puts patients at higher risk of life-threatening multiple drug overdoses. Both elevated anxiety and BZD misuse increase the risk for ex-addicts to relapse. However, there is no recent study to assess how serious the problem is and what factors are associated with BZD misuse. This study estimates the prevalence of BZD misuse in a methadone program, and provides information on the characteristics of BZD users compared to non-users.</p> <p>Methods</p> <p>An anonymous survey was carried out at a methadone program in Baltimore, MD, and all patients were invited to participate through group meetings and fliers around the clinic on a voluntary basis. Of the 205 returned questionnaires, 194 were complete and entered into final data analysis. Those who completed the questionnaire were offered a $5 gift card as an appreciation.</p> <p>Results</p> <p>47% of the respondents had a history of BZD use, and 39.8% used BZD without a prescription. Half of the BZD users (54%) started using BZD after entering the methadone program, and 61% of previous BZD users reported increased or resumed use after entering methadone program. Compared to the non-users, BZD users were more likely to be White, have prescribed medication for mental problems, have preexistent anxiety problems before opiate use, and had anxiety problems before entering methadone program. They reported more mental health problems in the past month, and had higher scores in anxiety state, depression and perceived stress (p < .05).</p> <p>Conclusions</p> <p>Important information on epidemiology of BZD misuse among methadone-maintenance patients suggests that most methadone programs do not address co-occurring anxiety problems, and methadone treatment may trigger onset or worsening of BZD misuse. Further study is needed to explore how to curb misuse and abuse of BZD in the addiction population, and provide effective treatments targeting simultaneously addiction symptoms, anxiety disorders and BZD misuse.</p

    Genetic analysis of the capsule polysaccharide (K antigen) and exopolysaccharide genes in pandemic Vibrio parahaemolyticus O3:K6

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    <p>Abstract</p> <p>Background</p> <p>Pandemic <it>Vibrio parahaemolyticus </it>has undergone rapid changes in both K- and O-antigens, making detection of outbreaks more difficult. In order to understand these rapid changes, the genetic regions encoding these antigens must be examined. In <it>Vibrio cholerae </it>and <it>Vibrio vulnificus</it>, both O-antigen and capsular polysaccharides are encoded in a single region on the large chromosome; a similar arrangement in pandemic <it>V. parahaemolyticus </it>would help explain the rapid serotype changes. However, previous reports on "capsule" genes are controversial. Therefore, we set out to clarify and characterize these regions in pandemic <it>V. parahaemolyticus </it>O3:K6 by gene deletion using a chitin based transformation strategy.</p> <p>Results</p> <p>We generated different deletion mutants of putative polysaccharide genes and examined the mutants by immuno-blots with O and K specific antisera. Our results showed that O- and K-antigen genes are separated in <it>V. parahaemolyticus </it>O3:K6; the region encoding both O-antigen and capsule biosynthesis in other vibrios, i.e. genes between <it>gmhD </it>and <it>rjg</it>, determines the K6-antigen but not the O3-antigen in <it>V. parahaemolyticus</it>. The previously identified "capsule genes" on the smaller chromosome were related to exopolysaccharide synthesis, not K-antigen.</p> <p>Conclusion</p> <p>Understanding of the genetic basis of O- and K-antigens is critical to understanding the rapid changes in these polysaccharides seen in pandemic <it>V. parahaemolyticus. </it>This report confirms the genetic location of K-antigen synthesis in <it>V. parahaemolyticus </it>O3:K6 allowing us to focus future studies of the evolution of serotypes to this region.</p

    Pinealectomy affects bone mineral density and structure - an experimental study in sheep

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    <p>Abstract</p> <p>Background</p> <p>Osteoporosis and associated fractures are a major public health burden and there is great need for a large animal model. Melatonin, the hormone of the pineal gland, has been shown to influence bone metabolism. This study aims to evaluate whether absence of melatonin due to pinealectomy affects the bone mass, structure and remodeling in an ovine animal model.</p> <p>Methods</p> <p>Female sheep were arranged into four groups: Control, surgically ovariectomized (Ovx), surgically pinealectomized (Px) and Ovx+Px. Before and 6 months after surgery, iliac crest biopsies were harvested and structural parameters were measured using μCT. Markers of bone formation and resorption were determined. To evaluate long term changes after pinealectomy, bone mineral density (BMD) was analyzed at the distal radius at 0, 3, 9, 18 and 30 months.</p> <p>Results</p> <p>Cancellous bone volume (BV/TV) declined after 6 months by -13.3% Px and -21.5% OvxPx. The bone loss was due to increased trabecular separation as well as decreased thickness. The histomorphometric quantification and determination of collagen degradation products showed increased bone resorption following pinealectomy. Ovariectomy alone results in a transient bone loss at the distal radius followed by continuous increase to baseline levels. The bone resorption activity after pinealectomy causes a bone loss which was not transient, since a continuous decrease in BMD was observed until 30 months.</p> <p>Conclusions</p> <p>The changes after pinealectomy in sheep are indicative of bone loss. Overall, these findings suggest that the pineal gland may influence bone metabolism and that pinealectomy can be used to induce bone loss in sheep.</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

    Identification of Fast-Evolving Genes in the Scleractinian Coral Acropora Using Comparative EST Analysis

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    To identify fast-evolving genes in reef-building corals, we performed direct comparative sequence analysis with expressed sequence tag (EST) datasets from two acroporid species: Acropora palmata from the Caribbean Sea and A. millepora from the Great Barrier Reef in Australia. Comparison of 589 independent sequences from 1,421 A. palmata contigs, with 10,247 A. millepora contigs resulted in the identification of 196 putative homologues. Most of the homologous pairs demonstrated high amino acid similarities (over 90%). Comparisons of putative homologues showing low amino acid similarities (under 90%) among the Acropora species to the near complete datasets from two other cnidarians (Hydra magnipapillata and Nematostella vectensis) implied that some were non-orthologous. Within 86 homologous pairs, 39 exhibited dN/dS ratios significantly less than 1, suggesting that these genes are under purifying selection associated with functional constraints. Eight independent genes showed dN/dS ratios exceeding 1, while three deviated significantly from 1, suggesting that these genes may play important roles in the adaptive evolution of Acropora. Our results also indicated that CEL-III lectin was under positive selection, consistent with a possible role in immunity or symbiont recognition. Further studies are needed to clarify the possible functions of the genes under positive selection to provide insight into the evolutionary process of corals
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