524 research outputs found

    Absorption on horizon-wrapped branes

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    We compute the absorption cross section of space-time scalars on a static D2 rane, in global coordinates, wrapped on the S^2 of an AdS_2 X S^2 X CY_3 geometry. We discuss its relevance for the construction of the dual quantum mechanics of Calabi-Yau black holes.Comment: 18 pages, 2 figure

    Distance between Midline and Vertebral Artery Groove of Atlas -A Real Aid to the Neurosurgeon

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    Abstract The knowledge of the relationship of the vertebral artery with the atlas is very important, in order to avoid any injury to the vertebral artery, during surgeries in the craniovertebral region. Different researchers have measured the distance of the vertebral artery from the midline along the posterior arch of atlas (oblique distance), but some authors have measured the perpendicular distance of vertebral artery from the midline. Usually, it is the perpendicular distance along which the surgeons are exploring in this region. Hence, the present study was planned to study and compare both oblique and perpendicular distances of the vertebral artery from the midline and find out statistical differences between these two parameters. It was carried out on 30 atlas vertebrae of Indian origin. The oblique and perpendicular distances of vertebral artery groove from midline and the thickness of vertebral artery groove were measured. The results suggest that dissection on the posterior aspect of the arch of atlas should remain 17.00 mm lateral to the midline and dissection on the superior aspect of the arch of atlas should remain 8.00 mm from the midline to prevent injury to the vertebral artery. It was also observed that "oblique distances of vertebral artery groove from the midline to the medial margin of inner and outer cortex are larger than the corresponding perpendicular distances from the midline". Although, the differences of oblique and perpendicular distances are not statistically significant but it may be clinically significant for the surgeons operating in the craniovertebral region. Hence, it is concluded that the surgeon should be aware of both the distances while operating in the craniovertebral region to avoid any iatrogenic injury to the vertebral artery

    Effects of Long-term Induced Hyperthyroidism on Egg Quality Traits in Cobb 500 Broiler Breeder Hens

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    Published data on 4-week-long administration of exogenous thyroxine in broiler breeder hens to decline the cold-induced ascites in their progeny suggest that the long-term maternal hyperthyroidism would affect egg quality characteristics traits in Cobb 500 broiler breeder hens. Seventy 47-w-old broiler breeder Cobb 500 hens (5 replicates and 7 hens each) were assigned in separate cages and allotted to two treatments, control and hyperthyroid. Thyroxine was orally administered to the hyperthyroid group (0.3 mg hen/day) for a period of 100 days consecutively. Simultaneously, distilled water was orally administered to the control group. The blood sampling was done every two weeks to analyze T3, T4, and estrogen assays, using commercially kits and the egg quality attributes were evaluated for weeks 0, 3, 6, 9, and 12. Thyroxine treatment resulted in an increase in plasma concentration of T4; however, the T3 level and estrogen were not affected. The results of this study showed that the long-term administration of thyroxine had adverse effect on the most of egg quality traits in broiler breeder hens; although the results may be distinct for treatments that using other birds, doses and duration of treatments, among the different egg quality traits of broiler breeder hens evaluated in this research. Therefore, further studies should be done to make a final conclusion to use of long-term maternal hyperthyroidism treatment to reduce the ascites incidence

    Comparison of Life History Characteristics of the Genetically Modified OX513A Line and a Wild Type Strain of Aedes aegypti

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    The idea of implementing genetics-based insect control strategies modelled on the traditional SIT (Sterile Insect Technique), such as RIDL (Release of Insects carrying a Dominant Lethal), is becoming increasingly popular. In this paper, we compare a genetically modified line of Aedes aegypti carrying a tetracycline repressible, lethal positive feedback system (OX513A) with a genetically similar, unmodified counterpart and their respective responses to increasing larval rearing density using a constant amount of food per larva. The parameters that we examined were larval mortality, developmental rate (i.e., time to pupation), adult size and longevity

    Micronucleus frequency in children exposed to biomass burning in the Brazilian Legal Amazon region: a control case study

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    <p>Abstract</p> <p>Background</p> <p>The Amazon represents an area of 61% of Brazilian territory and is undergoing major changes resulting from disorderly economic development, especially the advance of agribusiness. Composition of the atmosphere is controlled by several natural and anthropogenic processes, and emission from biomass burning is one with the major impact on human health. The aim of this study was to evaluate genotoxic potential of air pollutants generated by biomass burning through micronucleus assay in exfoliated buccal cells of schoolchildren in the Brazilian Amazon region.</p> <p>Methods</p> <p>The study was conducted during the dry seasons in two regions of the Brazilian Amazon. The assay was carried out on buccal epithelial cells of 574 schoolchildren between 6-16 years old.</p> <p>Results</p> <p>The results show a significant difference between micronucleus frequencies in children exposed to biomass burning compared to those in a control area.</p> <p>Conclusions</p> <p>The present study demonstrated that in situ biomonitoring using a sensitive and low cost assay (buccal micronucleus assay) may be an important tool for monitoring air quality in remote regions. It is difficult to attribute the increase in micronuclei frequency observed in our study to any specific toxic element integrated in the particulate matters. However, the contribution of the present study lies in the evidence that increased exposure to fine particulate matter generates an increased micronuclei frequency in oral epithelial cells of schoolchildren.</p

    The prevalence of nutritional anemia in pregnancy in an east Anatolian province, Turkey

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    <p>Abstract</p> <p>Background</p> <p>Anemia is considered a severe public health problem by World Health Organization when anemia prevalence is equal to or greater than 40% in the population. The purpose of this study was to determine the anemia prevalence with the associated factors in pregnant women and to determine the serum iron, folate and B12 vitamin status in anaemic pregnants in Malatya province.</p> <p>Methods</p> <p>This is a cross-sectional survey. A multi-sage stratified probability-proportional-to-size cluster sampling methodology was used. A total of 823 pregnant women from sixty clusters were studied. Women were administered a questionnaire related with the subject and blood samples were drawn. Total blood count was performed within four hours and serum iron, folate and B12 vitamin were studied after storing sera at -20 C for six months.</p> <p>Results</p> <p>Anemia prevalence was 27.1% (Hb < 11.0 gr/dl). Having four or more living children (OR = 2.2), being at the third trimester (OR = 2.3) and having a low family income (OR = 1.6) were determined as the independent predictors of anemia in pregnancy. Anemia was also associated with soil eating (PICA) in the univariate analysis (p < 0.05). Of anaemic women, 50.0% had a transferrin saturation less than 10% indicating iron deficiency, 34.5% were deficient in B12 vitamin and 71.7% were deficient in folate. Most of the anemias were normocytic-normochromic (56.5%) indicating mixed anemia.</p> <p>Conclusions</p> <p>In Malatya, for pregnant women anemia was a moderate public health problem. Coexisting of iron, folate and B vitamin deficiencies was observed among anaemics. To continue anemia control strategies with reasonable care and diligence was recommended.</p

    Prediction of conformational B-cell epitopes from 3D structures by random forests with a distance-based feature

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    <p>Abstract</p> <p>Background</p> <p>Antigen-antibody interactions are key events in immune system, which provide important clues to the immune processes and responses. In Antigen-antibody interactions, the specific sites on the antigens that are directly bound by the B-cell produced antibodies are well known as B-cell epitopes. The identification of epitopes is a hot topic in bioinformatics because of their potential use in the epitope-based drug design. Although most B-cell epitopes are discontinuous (or conformational), insufficient effort has been put into the conformational epitope prediction, and the performance of existing methods is far from satisfaction.</p> <p>Results</p> <p>In order to develop the high-accuracy model, we focus on some possible aspects concerning the prediction performance, including the impact of interior residues, different contributions of adjacent residues, and the imbalanced data which contain much more non-epitope residues than epitope residues. In order to address above issues, we take following strategies. Firstly, a concept of 'thick surface patch' instead of 'surface patch' is introduced to describe the local spatial context of each surface residue, which considers the impact of interior residue. The comparison between the thick surface patch and the surface patch shows that interior residues contribute to the recognition of epitopes. Secondly, statistical significance of the distance distribution difference between non-epitope patches and epitope patches is observed, thus an adjacent residue distance feature is presented, which reflects the unequal contributions of adjacent residues to the location of binding sites. Thirdly, a bootstrapping and voting procedure is adopted to deal with the imbalanced dataset. Based on the above ideas, we propose a new method to identify the B-cell conformational epitopes from 3D structures by combining conventional features and the proposed feature, and the random forest (RF) algorithm is used as the classification engine. The experiments show that our method can predict conformational B-cell epitopes with high accuracy. Evaluated by leave-one-out cross validation (LOOCV), our method achieves the mean AUC value of 0.633 for the benchmark bound dataset, and the mean AUC value of 0.654 for the benchmark unbound dataset. When compared with the state-of-the-art prediction models in the independent test, our method demonstrates comparable or better performance.</p> <p>Conclusions</p> <p>Our method is demonstrated to be effective for the prediction of conformational epitopes. Based on the study, we develop a tool to predict the conformational epitopes from 3D structures, available at <url>http://code.google.com/p/my-project-bpredictor/downloads/list</url>.</p

    Cornelia-de Lange syndrome-associated mutations cause a DNA damage signalling and repair defect

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    Cornelia de Lange syndrome is a multisystem developmental disorder typically caused by mutations in the gene encoding the cohesin loader NIPBL. The associated phenotype is generally assumed to be the consequence of aberrant transcriptional regulation. Recently, we identified a missense mutation in BRD4 associated with a Cornelia de Lange-like syndrome that reduces BRD4 binding to acetylated histones. Here we show that, although this mutation reduces BRD4-occupancy at enhancers it does not affect transcription of the pluripotency network in mouse embryonic stem cells. Rather, it delays the cell cycle, increases DNA damage signalling, and perturbs regulation of DNA repair in mutant cells. This uncovers a role for BRD4 in DNA repair pathway choice. Furthermore, we find evidence of a similar increase in DNA damage signalling in cells derived from NIPBL-deficient individuals, suggesting that defective DNA damage signalling and repair is also a feature of typical Cornelia de Lange syndrome

    Identification of Plasmodium vivax Proteins with Potential Role in Invasion Using Sequence Redundancy Reduction and Profile Hidden Markov Models

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    BACKGROUND: This study describes a bioinformatics approach designed to identify Plasmodium vivax proteins potentially involved in reticulocyte invasion. Specifically, different protein training sets were built and tuned based on different biological parameters, such as experimental evidence of secretion and/or involvement in invasion-related processes. A profile-based sequence method supported by hidden Markov models (HMMs) was then used to build classifiers to search for biologically-related proteins. The transcriptional profile of the P. vivax intra-erythrocyte developmental cycle was then screened using these classifiers. RESULTS: A bioinformatics methodology for identifying potentially secreted P. vivax proteins was designed using sequence redundancy reduction and probabilistic profiles. This methodology led to identifying a set of 45 proteins that are potentially secreted during the P. vivax intra-erythrocyte development cycle and could be involved in cell invasion. Thirteen of the 45 proteins have already been described as vaccine candidates; there is experimental evidence of protein expression for 7 of the 32 remaining ones, while no previous studies of expression, function or immunology have been carried out for the additional 25. CONCLUSIONS: The results support the idea that probabilistic techniques like profile HMMs improve similarity searches. Also, different adjustments such as sequence redundancy reduction using Pisces or Cd-Hit allowed data clustering based on rational reproducible measurements. This kind of approach for selecting proteins with specific functions is highly important for supporting large-scale analyses that could aid in the identification of genes encoding potential new target antigens for vaccine development and drug design. The present study has led to targeting 32 proteins for further testing regarding their ability to induce protective immune responses against P. vivax malaria
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