Citations

Aim: Missing data, particularly missing variables, can create serious analytic challenges in observational comparative effectiveness research studies. Statistical linkage of datasets is a potential method for incorporating missing variables. Prior studies have focused upon the bias introduced by imperfect linkage. Methods: This analysis uses a case study of hepatitis C patients to estimate the net effect of statistical linkage on bias, also accounting for the potential reduction in missing variable bias. Results: The results show that statistical linkage can reduce bias while also enabling parameter estimates to be obtained for the formerly missing variables. Conclusion: The usefulness of statistical linkage will vary depending upon the strength of the correlations of the missing variables with the treatment variable, as well as the outcome variable of interest.

ABSTRACTEpithelial‐mesenchymal transition (EMT) is a process whereby epithelial cells assume mesenchymal characteristics to facilitate cancer metastasis. However, EMT also contributes to the initiation and development of primary tumors. Prior studies that explored the hypothesis that EMT gene variants contribute to epithelial ovarian carcinoma (EOC) risk have been based on small sample sizes and none have sought replication in an independent population. We screened 15,816 single‐nucleotide polymorphisms (SNPs) in 296 genes in a discovery phase using data from a genome‐wide association study of EOC among women of European ancestry (1,947 cases and 2,009 controls) and identified 793 variants in 278 EMT‐related genes that were nominally (P < 0.05) associated with invasive EOC. These SNPs were then genotyped in a larger study of 14,525 invasive‐cancer patients and 23,447 controls. A P‐value <0.05 and a false discovery rate (FDR) <0.2 were considered statistically significant. In the larger dataset, GPC6/GPC5 rs17702471 was associated with the endometrioid subtype among Caucasians (odds ratio (OR) = 1.16, 95% CI = 1.07–1.25, P = 0.0003, FDR = 0.19), whereas F8 rs7053448 (OR = 1.69, 95% CI = 1.27–2.24, P = 0.0003, FDR = 0.12), F8 rs7058826 (OR = 1.69, 95% CI = 1.27–2.24, P = 0.0003, FDR = 0.12), and CAPN13 rs1983383 (OR = 0.79, 95% CI = 0.69–0.90, P = 0.0005, FDR = 0.12) were associated with combined invasive EOC among Asians. In silico functional analyses revealed that GPC6/GPC5 rs17702471 coincided with DNA regulatory elements. These results suggest that EMT gene variants do not appear to play a significant role in the susceptibility to EOC.

Background Most patients with atrial fibrillation ( AF ) require rate control; however, the optimal target heart rate remains under debate. We aimed to assess rate control and subsequent outcomes among patients with permanent AF . Methods and Results We studied 2812 US outpatients with permanent AF in the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation. Resting heart rate was measured longitudinally and used as a time‐dependent covariate in multivariable Cox models of all‐cause and cause‐specific mortality during a median follow‐up of 24 months. At baseline, 7.4% (n=207) had resting heart rate <60 beats per minute (bpm), 62% (n=1755) 60 to 79 bpm, 29% (n=817) 80 to 109 bpm, and 1.2% (n=33) ≥110 bpm. Groups did not differ by age, previous cerebrovascular disease, heart failure status, CHA 2 DS 2 ‐ VAS c scores, renal function, or left ventricular function. There were significant differences in race ( P =0.001), sinus node dysfunction ( P =0.004), and treatment with calcium‐channel blockers ( P =0.006) and anticoagulation ( P =0.009). In analyses of continuous heart rates, lower heart rate ≤65 bpm was associated with higher all‐cause mortality (adjusted hazard ratio [ HR ], 1.15 per 5‐bpm decrease; 95% CI , 1.01 to 1.32; P =0.04). Similarly, increasing heart rate >65 bpm was associated with higher all‐cause mortality (adjusted HR , 1.10 per 5‐bpm increase; 95% CI , 1.05 to 1.15; P <0.0001). This relationship was consistent across endpoints and in a broader sensitivity analysis of permanent and nonpermanent AF patients. Conclusions Among patients with permanent AF , there is a J‐shaped relationship between heart rate and mortality. These data support current guideline recommendations, and clinical trials are warranted to determine optimal rate control. Clinical Trial Registration URL : http://clinicaltrials.gov/ . Unique identifier: NCT01165710.

Abstract Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored. Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium. Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 × 10−4; OR, 1.04; 95% confidence interval (CI), 1.02–1.07] and rs77928427 (P = 1.86 × 10−4; OR, 1.04; 95% CI, 1.02–1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 ≥ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factor–binding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue. Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2. Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk. Cancer Epidemiol Biomarkers Prev; 24(11); 1680–91. ©2015 AACR.

Cell therapy is a potential therapeutic method for cerebral ischemia, which remains a serious problem. In the search for more effective therapeutic methods, many kinds of stem cells from various tissues have been developed and tested as candidate therapeutic agents. Among them, human umbilical cord blood (hUCB)‐derived mesenchymal stem cells (MSCs) are widely used for cell therapy because of their genetic flexibility. To confirm that they are effective and understand how they affect ischemic neural cells, hUCB‐MSCs were directly administered ipsilaterally into an ischemic zone induced by middle cerebral artery occlusion (MCAO). We found that the neurobehavioral performance of the hUCB‐MSC group was significantly improved compared with that of the vehicle‐injected control group. The infarct was also remarkably smaller in the hUCB‐MSC group. Additionally, hUCB‐MSC transplantation resulted in a greater number of newly generated cells and angiogenic and tissue repair factors and a lower number of inflammatory events in the penumbra zone. To determine why these events occurred, hUCB‐MSCs were assayed under hypoxic and normoxic conditions in vitro. The results showed that hUCB‐MSCs exhibit higher expression levels of thrombospondin1, pantraxin3, and vascular endothelial growth factor under hypoxic conditions than under normoxic conditions. These results were found to be correlated with our in vivo immunofluorescent staining results. On the basis of these findings, we suggest that hUCB‐MSCs may have a beneficial effect on cerebral ischemia, especially through angiogenesis, neurogenesis, and anti‐inflammatory effects, and thus could be used as a therapeutic agent to treat neurological disorders such as cerebral ischemia. © 2015 Wiley Periodicals, Inc.