938 research outputs found

    A clinical comparison of visual acuity between the Cardiff acuity test and the Teller acuity and Snellen acuity tests in an adult population

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    The newly introduced Cardiff Acuity Test developed at the University of Wales College, Cardiff UK was compared to the standard Snellen Acuity charts and the Teller Acuity cards. Acuity readings were obtained from 100 eyes (50 subjects) at distances of 1 meter and 3 meters. A significant difference was found between the 3 acuity tests with a greater deviation at distance (3 meters) than at near (1 meter). The Teller cards measured the highest (best) acuity level followed by the Cardiff and the Sneilen measuring the lowest (worst) acuity

    Insecticide Resistance Mechanisms in the Green Peach Aphid Myzus persicae (Hemiptera: Aphididae) I: A Transcriptomic Survey

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    BACKGROUND: Insecticide resistance is one of the best examples of rapid micro-evolution found in nature. Since the development of the first synthetic insecticide in 1939, humans have invested considerable effort to stay ahead of resistance phenotypes that repeatedly develop in insects. Aphids are a group of insects that have become global pests in agriculture and frequently exhibit insecticide resistance. The green peach aphid, Myzus persicae, has developed resistance to at least seventy different synthetic compounds, and different insecticide resistance mechanisms have been reported worldwide. METHODOLOGY/PRINCIPAL FINDINGS: To further characterize this resistance, we analyzed genome-wide transcriptional responses in three genotypes of M. persicae, each exhibiting different resistance mechanisms, in response to an anti-cholinesterase insecticide. The sensitive genotype (exhibiting no resistance mechanism) responded to the insecticide by up-regulating 183 genes primarily ones related to energy metabolism, detoxifying enzymes, proteins of extracellular transport, peptidases and cuticular proteins. The second genotype (resistant through a kdr sodium channel mutation), up-regulated 17 genes coding for detoxifying enzymes, peptidase and cuticular proteins. Finally, a multiply resistant genotype (carrying kdr and a modified acetylcholinesterase), up-regulated only 7 genes, appears not to require induced insecticide detoxification, and instead down-regulated many genes. CONCLUSIONS/SIGNIFICANCE: This study suggests strongly that insecticide resistance in M. persicae is more complex that has been described, with the participation of a broad array of resistance mechanisms. The sensitive genotype exhibited the highest transcriptional plasticity, accounting for the wide range of potential adaptations to insecticides that this species can evolve. In contrast, the multiply resistant genotype exhibited a low transcriptional plasticity, even for the expression of genes encoding enzymes involved in insecticide detoxification. Our results emphasize the value of microarray studies to search for regulated genes in insects, but also highlights the many ways those different genotypes can assemble resistant phenotypes depending on the environmental pressure

    Quantifying the success of feral cat eradication, San Nicolas Island, California

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    It is usually uncertain when to declare success and stop control in pest eradication operations that rely on successive reductions of the population. We used the data collected during a project to eradicate feral cats from San Nicolas Island, California to estimate both the number of cats remaining towards the end of the project, and the amount and type of surveillance effort required to declare successful eradication after the last known cat was removed. Fifty seven cats were removed between June 2009 and April 2010 and our model estimated that there was a 95% chance that a further 1 to 4 cats remained, with 1 cat being the most likely number. After this time a further two cats were detected and removed and the model predicted this outcome with a probability of 0.25. If managers wished to confirm eradication success at this point, we estimated that 55 km of effort searching for recent evidence of cats over the whole island without detecting any would provide 99% certainty that no cats remained (stopping rule 1). Alternatively, the optimal amount of search effort for evidence that minimized the joint cost of searching and the cost of wrongly declaring eradication was 75 km (stopping rule 2). The equivalent amount of camera-nights (26 cameras were available) required to declare successful eradication were 416 (stopping rule 1) and 1196 camera nights (stopping rule 2). During the confirmation phase, 270 km of sign search effort and 3294 camera-nights surveillance were used from late June 2010, when the last cat was removed, through August 2010, without detecting signs of survivors. Managers can be very confident that eradication has been successful

    CD4+FoxP3+ regulatory T cells confer infectious tolerance in a TGF-β–dependent manner

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    CD4+FoxP3+ regulatory T (T reg) cells comprise a separate lineage of T cells that are essential for maintaining immunological tolerance to self. The molecular mechanism(s) by which T reg cells mediate their suppressive effects remains poorly understood. One molecule that has been extensively studied in T reg cell suppression is transforming growth factor (TGF)-β, but its importance remains controversial. We found that TGF-β complexed to latency-associated peptide (LAP) is expressed on the cell surface of activated but not resting T reg cells. T reg cell LAP–TGF-β plays an important role in the suppression of the proliferation of activated T cells, but it is not required for the suppression of naive T cell activation. More importantly, T reg cell–derived TGF-β could generate de novo CD4+FoxP3+ T cells in vitro from naive precursors in a cell contact–dependent, antigen-presenting cell–independent and αV integrin–independent manner. The newly induced CD4+FoxP3+ T cells are suppressive both in vitro and in vivo. Transfer of activated antigen-specific T reg cells with naive antigen-specific responder T cells to normal recipients, followed by immunization, also results in induction of FoxP3 expression in the responder cells. T reg cell–mediated generation of functional CD4+FoxP3+ cells via this TGF-β–dependent pathway may represent a major mechanism as to how T reg cells maintain tolerance and expand their suppressive abilities

    Time to Renal Disease and End-Stage Renal Disease in PROFILE: A Multiethnic Lupus Cohort

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    BACKGROUND: Renal involvement is a serious manifestation of systemic lupus erythematosus (SLE); it may portend a poor prognosis as it may lead to end-stage renal disease (ESRD). The purpose of this study was to determine the factors predicting the development of renal involvement and its progression to ESRD in a multi-ethnic SLE cohort (PROFILE). METHODS AND FINDINGS: PROFILE includes SLE patients from five different United States institutions. We examined at baseline the socioeconomic–demographic, clinical, and genetic variables associated with the development of renal involvement and its progression to ESRD by univariable and multivariable Cox proportional hazards regression analyses. Analyses of onset of renal involvement included only patients with renal involvement after SLE diagnosis (n = 229). Analyses of ESRD included all patients, regardless of whether renal involvement occurred before, at, or after SLE diagnosis (34 of 438 patients). In addition, we performed a multivariable logistic regression analysis of the variables associated with the development of renal involvement at any time during the course of SLE. In the time-dependent multivariable analysis, patients developing renal involvement were more likely to have more American College of Rheumatology criteria for SLE, and to be younger, hypertensive, and of African-American or Hispanic (from Texas) ethnicity. Alternative regression models were consistent with these results. In addition to greater accrued disease damage (renal damage excluded), younger age, and Hispanic ethnicity (from Texas), homozygosity for the valine allele of FcγRIIIa (FCGR3A*GG) was a significant predictor of ESRD. Results from the multivariable logistic regression model that included all cases of renal involvement were consistent with those from the Cox model. CONCLUSIONS: Fcγ receptor genotype is a risk factor for progression of renal disease to ESRD. Since the frequency distribution of FCGR3A alleles does not vary significantly among the ethnic groups studied, the additional factors underlying the ethnic disparities in renal disease progression remain to be elucidated

    Genomic resources for Myzus persicae: EST sequencing, SNP identification, and microarray design

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    <p>Abstract</p> <p>Background</p> <p>The green peach aphid, <it>Myzus persicae </it>(Sulzer), is a world-wide insect pest capable of infesting more than 40 plant families, including many crop species. However, despite the significant damage inflicted by <it>M. persicae </it>in agricultural systems through direct feeding damage and by its ability to transmit plant viruses, limited genomic information is available for this species.</p> <p>Results</p> <p>Sequencing of 16 <it>M. persicae </it>cDNA libraries generated 26,669 expressed sequence tags (ESTs). Aphids for library construction were raised on <it>Arabidopsis thaliana</it>, <it>Nicotiana benthamiana</it>, <it>Brassica oleracea, B. napus</it>, and <it>Physalis floridana </it>(with and without <it>Potato leafroll virus </it>infection). The <it>M. persicae </it>cDNA libraries include ones made from sexual and asexual whole aphids, guts, heads, and salivary glands. <it>In silico </it>comparison of cDNA libraries identified aphid genes with tissue-specific expression patterns, and gene expression that is induced by feeding on <it>Nicotiana benthamiana</it>. Furthermore, 2423 genes that are novel to science and potentially aphid-specific were identified. Comparison of cDNA data from three aphid lineages identified single nucleotide polymorphisms that can be used as genetic markers and, in some cases, may represent functional differences in the protein products. In particular, non-conservative amino acid substitutions in a highly expressed gut protease may be of adaptive significance for <it>M. persicae </it>feeding on different host plants. The Agilent eArray platform was used to design an <it>M. persicae </it>oligonucleotide microarray representing over 10,000 unique genes.</p> <p>Conclusion</p> <p>New genomic resources have been developed for <it>M. persicae</it>, an agriculturally important insect pest. These include previously unknown sequence data, a collection of expressed genes, molecular markers, and a DNA microarray that can be used to study aphid gene expression. These resources will help elucidate the adaptations that allow <it>M. persicae </it>to develop compatible interactions with its host plants, complementing ongoing work illuminating plant molecular responses to phloem-feeding insects.</p
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