Circulating Vitamin D Concentrations and Risk of Atrial Fibrillation:A Mendelian Randomization Study Using Non-deficient Range Summary Statistics

Vitamin D deficiency is a common disorder and has been linked with atrial fibrillation (AF) in several observational studies, although the causal relationships remain unclear. We conducted a Mendelian randomization (MR) analysis to determine the causal association between serum 25-hydroxyvitamin D [25(OH)D] concentrations and AF. The analyses were performed using summary statistics obtained for single-nucleotide polymorphisms (SNPs) identified from large genome-wide association meta-analyses conducted on serum 25(OH)D ( = 79,366) and AF ( = 1,030,836). Six SNPs related to serum 25(OH)D were used as instrumental variables. The association between 25(OH)D and AF was estimated using both the fixed-effect and random-effects inverse variance weighted (IVW) method. The MR analyses found no evidence to support a causal association between circulating 25(OH)D level and risk of AF using random-effects IVW (odds ratio per unit increase in log 25(OH)D = 1.003, 95% CI, 0.841-1.196; = 0.976) or fixed-effect IVW method (OR = 1.003, 95% CI, 0.876-1.148; = 0.968). Sensitivity analyses yielded similar results. No heterogeneity and directional pleiotropy were detected. Using summary statistics, this MR study suggests that genetically predicted circulating vitamin D concentrations, especially for a non-deficient range, were not causally associated with AF in the general population. Future studies using non-linear design and focusing on the vitamin D deficiency population are needed to further evaluate the causal effect of vitamin D concentrations on AF

Strategic Business Management: A Practical Framework and Causal Model of Empowering Leadership, Team Cohesion, Knowledge-Sharing Behavior, and Team Performance

Research objectives were to determine a practical framework and to create a causal model of empowering leadership, team cohesion, knowledge-sharing behavior, and team performance of petroleum refinery plant employees in Thailand. The study reported the responses of 594 operational employees from seven petroleum refinery plants operating in different parts of Thailand. Data were analyzed with descriptive statistics using SPSS (version 11.5) and path analysis using LISREL (version 8). Research findings indicate that dimensions of empowering leadership, team cohesion, and knowledge-sharing behavior have mediated positive effect on team performance. Knowledge-sharing behavior positively mediates the relationships between empowering leadership and team performance and between team cohesion and team performance. Furthermore, empowering leadership is positively correlated with team cohesion

Strategic Human Resource Practice: A Functional Framework and Causal Model of Leadership Behavior, Job Satisfaction, Organizational Commitment, and Job Performance

Research objectives were to determine a functional framework and to synthesize a causal model of leadership behavior, job satisfaction, organizational commitment, and job performance of sugar company employees in Thailand. The study reported the responses of 591 operational employees from 24 sugar companies operating in different parts of Thailand. Data were analyzed with descriptive statistics using SPSS (version 11.5) and path analysis using LISREL (version 8). Research findings indicated that dimensions of leadership behavior, job satisfaction, and organizational commitment have mediated positive effect on job performance. Organizational commitment positively mediates the relationships between leadership behavior and job performance and between job satisfaction and job performance. Furthermore, leadership behavior is positively correlated with job satisfaction

Strategic Human Resource Practice: A Systematic Framework and Causal Model of Learning Orientation, Quality of Leader-Member Exchange, Goal Orientation, and Workgroup Performance

Research objectives were to determine a systematic framework and to blend a causal model of learning orientation, quality of leader-member exchange, goal orientation, and workgroup performance of pharmaceutical company employees in Thailand. The study reported the responses of 583 operational employees from 39 pharmaceutical companies operating in different parts of Thailand. Data were analyzed with descriptive statistics using SPSS (version 11.5) and path analysis using LISREL (version 8). Research findings indicated that dimensions of learning orientation, quality of leader-member exchange, and goal orientation have mediated positive effect on workgroup performance. Goal orientation positively mediates the relationships between learning orientation and workgroup performance and between quality of leader-member exchange and workgroup performance. Furthermore, learning orientation is positively correlated with the quality of leader-member exchange

Understanding the complex genetic architecture connecting rheumatoid arthritis, osteoporosis and inflammation:discovering causal pathways

Rheumatoid arthritis (RA) and osteoporosis (OP) are two comorbid complex inflammatory conditions with evidence of shared genetic background and causal relationships. We aimed to clarify the genetic architecture underlying RA and various OP phenotypes while additionally considering an inflammatory component, C-reactive protein (CRP). Genome-wide association study summary statistics were acquired from the GEnetic Factors for OSteoporosis Consortium, Cohorts for Heart and Aging Research Consortium and UK Biobank. Mendelian randomization (MR) was used to detect the presence of causal relationships. Colocalization analysis was performed to determine shared genetic variants between CRP and OP phenotypes. Analysis of pleiotropy between traits owing to shared causal single nucleotide polymorphisms (SNPs) was performed using PL eiotropic A nalysis under CO mposite null hypothesis (PLACO). MR analysis was suggestive of horizontal pleiotropy between RA and OP traits. RA was a significant causal risk factor for CRP (β = 0.027, 95% confidence interval = 0.016-0.038). There was no evidence of CRP→OP causal relationship, but horizontal pleiotropy was apparent. Colocalization established shared genomic regions between CRP and OP, including GCKR and SERPINA1 genes. Pleiotropy arising from shared causal SNPs revealed through the colocalization analysis was all confirmed by PLACO. These genes were found to be involved in the same molecular function 'protein binding' (GO:0005515) associated with RA, OP and CRP. We identified three major components explaining the epidemiological relationship among RA, OP and inflammation: (1) Pleiotropy explains a portion of the shared genetic relationship between RA and OP, albeit polygenically; (2) RA contributes to CRP elevation and (3) CRP, which is influenced by RA, demonstrated pleiotropy with OP.</p

Causal graphical models in systems genetics: A unified framework for joint inference of causal network and genetic architecture for correlated phenotypes

Causal inference approaches in systems genetics exploit quantitative trait loci (QTL) genotypes to infer causal relationships among phenotypes. The genetic architecture of each phenotype may be complex, and poorly estimated genetic architectures may compromise the inference of causal relationships among phenotypes. Existing methods assume QTLs are known or inferred without regard to the phenotype network structure. In this paper we develop a QTL-driven phenotype network method (QTLnet) to jointly infer a causal phenotype network and associated genetic architecture for sets of correlated phenotypes. Randomization of alleles during meiosis and the unidirectional influence of genotype on phenotype allow the inference of QTLs causal to phenotypes. Causal relationships among phenotypes can be inferred using these QTL nodes, enabling us to distinguish among phenotype networks that would otherwise be distribution equivalent. We jointly model phenotypes and QTLs using homogeneous conditional Gaussian regression models, and we derive a graphical criterion for distribution equivalence. We validate the QTLnet approach in a simulation study. Finally, we illustrate with simulated data and a real example how QTLnet can be used to infer both direct and indirect effects of QTLs and phenotypes that co-map to a genomic region.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS288 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Nexo TIC-finanzas-crecimiento: hallazgos empíricos de los países de los Próximos 11

This study assesses the causal relationship between information and communication technology (ICT) penetration, financial development, and economic growth in Next-11 countries between 1961 and 2012. A panel vector auto-regressive (VAR) model is used to detect the direction of causality between ICT, financial sector development and economic growth for these countries. The results reveal that there is Granger-causality among the variables both in the short run and in the long run, although the exact nature of the results varies by the ICT penetration indicators for the sample countries. Empirical results from this study provide valuable insights on policies pertaining to ICT penetration, financial sector development and economic growthEl presente estudio evalúa la relación causal entre la penetración de las tecnologías de la información y comunicación (TIC), el desarrollo financiero y el crecimiento económico en los Próximos 11 entre 1961 y 2012. Se utilizó un modelo de panel de vectores autorregresivos países para detectar la dirección de causalidad entre las TIC, el desarrollo del sector financiero y el crecimiento económico para estos países. Los resultados revelan que existe una causalidad de Granger entre las variables tanto a corto como a medio plazo, si bien la naturaleza exacta de los hallazgos varía conforme a los indicadores de penetración de las TIC para los países dela muestra. Los resultados empíricos de este estudio suponen una valiosa perspectiva a cerca de las políticas de penetración de las TIC, el desarrollo del sector financiero y el crecimiento económic