334 research outputs found

    How Many Subpopulations is Too Many? Exponential Lower Bounds for Inferring Population Histories

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    Reconstruction of population histories is a central problem in population genetics. Existing coalescent-based methods, like the seminal work of Li and Durbin (Nature, 2011), attempt to solve this problem using sequence data but have no rigorous guarantees. Determining the amount of data needed to correctly reconstruct population histories is a major challenge. Using a variety of tools from information theory, the theory of extremal polynomials, and approximation theory, we prove new sharp information-theoretic lower bounds on the problem of reconstructing population structure -- the history of multiple subpopulations that merge, split and change sizes over time. Our lower bounds are exponential in the number of subpopulations, even when reconstructing recent histories. We demonstrate the sharpness of our lower bounds by providing algorithms for distinguishing and learning population histories with matching dependence on the number of subpopulations. Along the way and of independent interest, we essentially determine the optimal number of samples needed to learn an exponential mixture distribution information-theoretically, proving the upper bound by analyzing natural (and efficient) algorithms for this problem.Comment: 38 pages, Appeared in RECOMB 201

    Three Decades of Internet- and Computer-Based Interventions for the Treatment of Depression: Protocol for a Systematic Review and Meta-Analysis

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    Background: Depression is one of the leading causes of disability worldwide. Internet- and computer-based interventions (IBIs) have been shown to provide effective, scalable forms of treatment. More than 100 controlled trials and a growing number of meta-analyses published over the past 30 years have demonstrated the efficacy of IBIs in reducing symptoms in the short and long term. Despite the large body of research, no comprehensive review or meta-analysis has been conducted to date that evaluates how the effectiveness of IBIs has evolved over time.Objective: This systematic review and meta-analysis aims to evaluate whether there has been a change in the effectiveness of IBIs on the treatment of depression over the past 30 years and to identify potential variables moderating the effect size.Methods: A sensitive search strategy will be executed across the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and PsycINFO. Data extraction and evaluation will be conducted by two independent researchers. Risk of bias will be assessed. A multilevel meta-regression model will be used to analyze the data and estimate effect size.Results: The search was completed in mid-2019. We expect the results to be submitted for publication in early 2020.Conclusions: The year 2020 will mark 30 years since the first paper was published on the use of IBIs for the treatment of depression. Despite the large and rapidly growing body of research in the field, evaluations of effectiveness to date are missing the temporal dimension. This review will address that gap and provide valuable analysis of how the effectiveness of interventions has evolved over the past three decades; which participant-, intervention-, and study-related variables moderate changes in effectiveness; and where research in the field may benefit from increased focus.</p

    Test of a conceptual model of uncertainty in children and adolescents with cancer

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    Despite recognition as a significant stressor in childhood cancer, illness-related uncertainty from the perspective of children remains under-studied. We tested a conceptual model of uncertainty, derived from Mishel’s uncertainty in illness theory, in 68 school-aged children and adolescents with cancer. As hypothesized, uncertainty was significantly related to psychological distress, but only one hypothesized antecedent (parental uncertainty) significantly predicted children’s uncertainty. An alternative model incorporating antecedent developmental factors (age and illness-specific expertise) explained 21% of the variance in child uncertainty; controlling for stage of treatment, uncertainty was higher in children with shorter time since diagnosis, older age, lower cancer knowledge, and higher parental uncertainty. These findings provide the foundation for further studies to understand children’s management of uncertainty and its contribution to psychological adjustment to illness

    Immune Responses to Viral Gene Therapy Vectors

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    Several viral vector-based gene therapy drugs have now received marketing approval. A much larger number of additional viral vectors are in various stages of clinical trials for the treatment of genetic and acquired diseases, with many more in pre-clinical testing. Efficiency of gene transfer and ability to provide long-term therapy make these vector systems very attractive. In fact, viral vector gene therapy has been able to treat or even cure diseases for which there had been no or only suboptimal treatments. However, innate and adaptive immune responses to these vectors and their transgene products constitute substantial hurdles to clinical development and wider use in patients. This review provides an overview of the type of immune responses that have been documented in animal models and in humans who received gene transfer with one of three widely tested vector systems, namely adenoviral, lentiviral, or adeno-associated viral vectors. Particular emphasis is given to mechanisms leading to immune responses, efforts to reduce vector immunogenicity, and potential solutions to the problems. At the same time, we point out gaps in our knowledge that should to be filled and problems that need to be addressed going forward

    Innate immunity: ignored for decades, but not forgotten.

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    The innate immune system must recognize and rapidly respond to microbial pathogens, providing a first line of host defense. This is accomplished through an array of pattern recognition receptors (PRRs) that reside in specific subcellular compartments and can bind pathogen-associated molecular patterns. PRRs also recognize self-molecules that are released after cell damage or death, known as danger-associated molecular patterns, which can be actively transported across cell membranes. The activation of PRRs leads to host defense pathways in infectious diseases, but can also contribute to tissue injury in autoimmune diseases. The identification of these pathways has provided new insight into mechanisms of vaccination and holds promise for developing better vaccines. Finally, the identification of PRRs, their ligands, and signaling pathways provides an opportunity for developing new immunotherapeutic approaches to skin conditions in which activation of the innate immune response contributes to disease pathogenesis

    Variation in endoglin pathway genes is associated with preeclampsia: A case-control candidate gene association study

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    Background: Preeclampsia is a hypertensive, multi-system pregnancy disorder whose pathophysiology remains unclear. Elevations in circulating soluble endoglin (sENG) and placental/blood ENG mRNA expression antedate the clinical onset of preeclampsia. This study investigated if endoglin (ENG) pathway genetic variation was also associated with the development of preeclampsia.Methods: We used a case-control candidate gene association design. Data from 355 white (181 preeclampsia cases/174 controls) and 60 black (30 preeclampsia cases/30 controls) women matched on ancestry, age, and parity were analyzed. Tagging single nucleotide polymorphisms (tSNPs) and potentially functional SNPs in ENG, TGFβ1, TGFβR1, ALK1, and TGFβR2 were genotyped with iPLEX® and TaqMan®. Chi-square or Fisher's exact tests were used to conduct allele/genotype/haplotype tests in white/black subgroups separately. Odds ratios were computed with binary logistic regression for tSNPs with significant genotype tests.Results: Of the 49 SNPs evaluated, variation in two ENG tSNPs (rs11792480, rs10121110) and one TGFβR2 tSNP (rs6550005) was associated with preeclampsia in white women (P <0.05, each). In black women, variation in two TGFβ1 tSNPs (rs4803455, rs4803457), one TGFβR1 tSNP (rs10739778), and three TGFβR2 tSNPs (rs6550005, rs1346907, rs877572) was associated with preeclampsia (P <0.05, each). Further evaluation of ENG tSNP rs10121110 revealed that white women inheriting the AA genotype were 2.29 times more likely to develop preeclampsia compared to the GG genotype (P = 0.008, [99% CI: 1.02 to 5.13]). For black women, similar evaluation of TGFβ1 tSNP rs4803457 revealed women inheriting the CT genotype were 7.44 times more likely to develop preeclampsia than those with the CC genotype (P = 0.005, [99% CI: 1.19 to 46.41]).Conclusions: ENG pathway genetic variation is associated with preeclampsia. Different ENG pathway genes may be involved in preeclampsia development among white and black women. Additional studies are needed to validate these findings and to determine if genetic variation in ENG pathway genes impacts ENG and sENG levels in preeclampsia. © 2013 Bell et al.; licensee BioMed Central Ltd
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