94 research outputs found

    A Genome-Wide association Study of Obstructive Heart Defects among Participants in the National Birth Defects Prevention Study

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    Obstructive heart defects (OHDs) share common structural lesions in arteries and cardiac valves, accounting for ~25% of all congenital heart defects. OHDs are highly heritable, resulting from interplay among maternal exposures, genetic susceptibilities, and epigenetic phenomena. A genome-wide association study was conducted in National Birth Defects Prevention Study participants (

    A bootstrap approach for assessing the uncertainty of outcome probabilities when using a scoring system

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    Background: Scoring systems are a very attractive family of clinical predictive models, because the patient score can be calculated without using any data processing system. Their weakness lies in the difficulty of associating a reliable prognostic probability with each score. In this study a bootstrap approach for estimating confidence intervals of outcome probabilities is described and applied to design and optimize the performance of a scoring system for morbidity in intensive care units after heart surgery. Methods: The bias-corrected and accelerated bootstrap method was used to estimate the 95% confidence intervals of outcome probabilities associated with a scoring system. These confidence intervals were calculated for each score and each step of the scoring-system design by means of one thousand bootstrapped samples. 1090 consecutive adult patients who underwent coronary artery bypass graft were assigned at random to two groups of equal size, so as to define random training and testing sets with equal percentage morbidities. A collection of 78 preoperative, intraoperative and postoperative variables were considered as likely morbidity predictors. Results: Several competing scoring systems were compared on the basis of discrimination, generalization and uncertainty associated with the prognostic probabilities. The results showed that confidence intervals corresponding to different scores often overlapped, making it convenient to unite and thus reduce the score classes. After uniting two adjacent classes, a model with six score groups not only gave a satisfactory trade-off between discrimination and generalization, but also enabled patients to be allocated to classes, most of which were characterized by well separated confidence intervals of prognostic probabilities. Conclusions: Scoring systems are often designed solely on the basis of discrimination and generalization characteristics, to the detriment of prediction of a trustworthy outcome probability. The present example demonstrates that using a bootstrap method for the estimation of outcome-probability confidence intervals provides useful additional information about score-class statistics, guiding physicians towards the most convenient model for predicting morbidity outcomes in their clinical context

    A Versatile and Efficient Novel Approach for Mendelian Randomization Analysis with Application to Assess the Causal Effect of Fetal Hemoglobin on Anemia in Sickle Cell Anemia

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    Mendelian randomization (MR) is increasingly employed as a technique to assess the causation of a risk factor on an outcome using observational data. The two-stage least-squares (2SLS) procedure is commonly used to examine the causation using genetic variants as the instrument variables. The validity of 2SLS relies on a representative sample randomly selected from a study cohort or a population for genome-wide association study (GWAS), which is not always true in practice. For example, the extreme phenotype sequencing (EPS) design is widely used to investigate genetic determinants of an outcome in GWAS as it bears many advantages such as efficiency, low sequencing or genotyping cost, and large power in detecting the involvement of rare genetic variants in disease etiology. In this paper, we develop a novel, versatile, and efficient approach, namely MR analysis under Extreme or random Phenotype Sampling (MREPS), for one-sample MR analysis based on samples drawn through either the random sampling design or the nonrandom EPS design. In simulations, MREPS provides unbiased estimates for causal effects, correct type I errors for causal effect testing. Furthermore, it is robust under different study designs and has high power. These results demonstrate the superiority of MREPS over the widely used standard 2SLS approach. We applied MREPS to assess and highlight the causal effect of total fetal hemoglobin on anemia risk in patients with sickle cell anemia using two independent cohort studies. A user-friendly Shiny app web interface was implemented for professionals to easily explore the MREPS

    A genome-wide association study of obstructive heart defects among participants in the National Birth Defects Prevention Study

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    Obstructive heart defects (OHDs) share common structural lesions in arteries and cardiac valves, accounting for ~25% of all congenital heart defects. OHDs are highly heritable, resulting from interplay among maternal exposures, genetic susceptibilities, and epigenetic phenomena. A genome-wide association study was conducted in National Birth Defects Prevention Study participants (Ndiscovery = 3978; Nreplication = 2507), investigating the genetic architecture of OHDs using transmission/disequilibrium tests (TDT) in complete case-parental trios (Ndiscovery_TDT = 440; Nreplication_TDT = 275) and case–control analyses separately in infants (Ndiscovery_CCI = 1635; Nreplication_CCI = 990) and mothers (case status defined by infant; Ndiscovery_CCM = 1703; Nreplication_CCM = 1078). In the TDT analysis, the SLC44A2 single nucleotide polymorphism (SNP) rs2360743 was significantly associated with OHD (pdiscovery = 4.08 × 10−9; preplication = 2.44 × 10−4). A CAPN11 SNP (rs55877192) was suggestively associated with OHD (pdiscovery = 1.61 × 10−7; preplication = 0.0016). Two other SNPs were suggestively associated (p < 1 × 10−6) with OHD in only the discovery sample. In the case–control analyses, no SNPs were genome-wide significant, and, even with relaxed thresholds (× discovery < 1 × 10−5 and preplication < 0.05), only one SNP (rs188255766) in the infant analysis was associated with OHDs (pdiscovery = 1.42 × 10−6; preplication = 0.04). Additional SNPs with pdiscovery < 1 × 10−5 were in loci supporting previous findings but did not replicate. Overall, there was modest evidence of an association between rs2360743 and rs55877192 and OHD and some evidence validating previously published findings

    Immune-mediated genetic pathways resulting in pulmonary function impairment increase lung cancer susceptibility

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    Impaired lung function is often caused by cigarette smoking, making it challenging to disentangle its role in lung cancer susceptibility. Investigation of the shared genetic basis of these phenotypes in the UK Biobank and International Lung Cancer Consortium (29,266 cases, 56,450 controls) shows that lung cancer is genetically correlated with reduced forced expiratory volume in one second (FEV1: r(g) = 0.098, p = 2.3 x 10(-8)) and the ratio of FEV1 to forced vital capacity (FEV1/FVC: r(g) = 0.137, p = 2.0 x 10(-12)). Mendelian randomization analyses demonstrate that reduced FEV1 increases squamous cell carcinoma risk (odds ratio (OR) = 1.51, 95% confidence intervals: 1.21-1.88), while reduced FEV1/FVC increases the risk of adenocarcinoma (OR = 1.17, 1.01-1.35) and lung cancer in never smokers (OR = 1.56, 1.05-2.30). These findings support a causal role of pulmonary impairment in lung cancer etiology. Integrative analyses reveal that pulmonary function instruments, including 73 novel variants, influence lung tissue gene expression and implicate immune-related pathways in mediating the observed effects on lung carcinogenesis

    DEVELOPMENT OF A METHOD OF CALCULATION OF THE LAMELLAR SCRAPER HEATEXCHANGE DEVICE

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    The current work presents a method of calculating the required heat exchange area for the scraper plate- type heat exchanger for high viscosity products. Calculations are performedusing theappliedcomputingpackageMathCAD. Based on results of calculations, temperaturegraphswere constructedforstraight-flowandcountercurrentflowpatterns in liquid environment

    Viscose liquid heat treatment using plate scraper heat exchanger

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    The current work analyzes the use of different types of heat exchangers, depending on the technology of production. It is taken the detail analysis of the ways of applicability of various types of heat exchangers, depending on the viscosity of the processed product. It is posed the problem of the analytical determination of the required area of heat exchange with the use of differential equations of heat transfer in a moving liquid media, written in cylindrical coordinates, for symmetrical temperature distribution, without taking in account the energy dissipation

    Heat treatment regularity for viscose products in plate scrapers heat exchanger

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    The current work describesthe construction of scraperplate-typeheat exchangerscurrently usedin industryand thetraffic patternof the productin it. Ananalytical model is represented and it is also posed the problemofthe analyticaldetermination ofthe requiredarea of heat exchangewith the use ofdifferential equations ofheat transfer in amovingliquid media, written in cylindrical coordinates, for symmetrical temperature distribution,without taking into accountthe energy dissipation

    The thermal characteristics of thawing silts of glacial genesis

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