排序方式: 共有35条查询结果,搜索用时 15 毫秒
31.
Raska P Iversen E Chen A Chen Z Fridley BL Permuth-Wey J Tsai YY Vierkant RA Goode EL Risch H Schildkraut JM Sellers TA Barnholtz-Sloan J 《PloS one》2012,7(5):e35235
We investigated the ability of several principal components analysis (PCA)-based strategies to detect and control for population stratification using data from a multi-center study of epithelial ovarian cancer among women of European-American ethnicity. These include a correction based on an ancestry informative markers (AIMs) panel designed to capture European ancestral variation and corrections utilizing un-thinned genome-wide SNP data; case-control samples were drawn from four geographically distinct North-American sites. The AIMs-only and genome-wide first principal components (PC1) both corresponded to the previously described North or Northwest-Southeast axis of European variation. We found that the genome-wide PCA captured this primary dimension of variation more precisely and identified additional axes of genome-wide variation of relevance to epithelial ovarian cancer. Associations evident between the genome-wide PCs and study site corroborate North American immigration history and suggest that undiscovered dimensions of variation lie within Northern Europe. The structure captured by the genome-wide PCA was also found within control individuals and did not reflect the case-control variation present in the data. The genome-wide PCA highlighted three regions of local LD, corresponding to the lactase (LCT) gene on chromosome 2, the human leukocyte antigen system (HLA) on chromosome 6 and to a common inversion polymorphism on chromosome 8. These features did not compromise the efficacy of PCs from this analysis for ancestry control. This study concludes that although AIMs panels are a cost-effective way of capturing population structure, genome-wide data should preferably be used when available. 相似文献
32.
Liu Y Melin BS Rajaraman P Wang Z Linet M Shete S Amos CI Lau CC Scheurer ME Tsavachidis S Armstrong GN Houlston RS Hosking FJ Claus EB Barnholtz-Sloan J Lai R Il'yasova D Schildkraut J Sadetzki S Johansen C Bernstein JL Olson SH Jenkins RB Lachance D Vick NA Wrensch M Davis F McCarthy BJ Andersson U Thompson PA Chanock S;The Gliogene Consortium Bondy ML 《Human genetics》2012,131(9):1507-1517
The risk of glioma has consistently been shown to be increased twofold in relatives of patients with primary brain tumors (PBT). A recent genome-wide linkage study of glioma families provided evidence for a disease locus on 17q12-21.32, with the possibility of four additional risk loci at 6p22.3, 12p13.33-12.1, 17q22-23.2, and 18q23. To identify the underlying genetic variants responsible for the linkage signals, we compared the genotype frequencies of 5,122 SNPs mapping to these five regions in 88 glioma cases with and 1,100 cases without a family history of PBT (discovery study). An additional series of 84 familial and 903 non-familial cases were used to replicate associations. In the discovery study, 12 SNPs showed significant associations with family history of PBT (P?0.001). In the replication study, two of the 12 SNPs were confirmed: 12p13.33-12.1 PRMT8 rs17780102 (P?=?0.031) and 17q12-21.32 SPOP rs650461 (P?=?0.025). In the combined analysis of discovery and replication studies, the strongest associations were attained at four SNPs: 12p13.33-12.1 PRMT8 rs17780102 (P?=?0.0001), SOX5 rs7305773 (P?=?0.0001) and STKY1 rs2418087 (P?=?0.0003), and 17q12-21.32 SPOP rs6504618 (P?=?0.0006). Further, a significant gene-dosage effect was found for increased risk of family history of PBT with these four SNPs in the combined data set (P (trend) <1.0?×?10(-8)). The results support the linkage finding that some loci in the 12p13.33-12.1 and 17q12-q21.32 may contribute to gliomagenesis and suggest potential target genes underscoring linkage signals. 相似文献
33.
Standard Reference Materials (SRMs) from the National Institute of Standards and Technology (NIST) are often used in methods development and interlaboratory comparison studies since they are homogeneous and readily available to the scientific community. SRM 1649 (urban dust/organics), SRM 1650 (diesel particulate matter), and SRM 1597 (complex mixture of polycyclic aromatic hydrocarbons from coal tar) are three environmental samples which have been used by the scientific community for these purposes. These SRMs were originally developed to assist laboratories in validating analytical procedures for the determination of polycyclic organic compounds in complex mixtures. In addition, these SRMs have been valuable for the comparison of methodologies for bacterial bioassays and the development of bioassay-directed fractionation and bioassay-directed chemical analysis techniques. Most recently these SRMs were chosen for use as test samples in a collaborative study coordinated by the World Health Organization--International Programme on Chemical Safety. This paper provides a summary of much of the work to date (published and unpublished) on the chemical and biological characterization of these three SRMs. Information regarding the availability of other NIST SRMs that might be useful for these types of studies are provided also. 相似文献
34.
M. J. Bennett K. M. Ogilvy. G. M. Blake N. Lewtas W. R. Timperley 《Journal of neurochemistry》1976,26(6):1139-1143
The activities of a number of glycolytic and hexose-monophosphate shunt cnzymes in 14 cases of intracranial pathology have been compared with specific uptake of the radioactive tracer 99m Tc-pertechnetate. Strong positive correlations were observed betwcen isotope uptake and the activities of hexokinase and glucose-6-phosphate dehydrogenase. No close correlation was observed with other enzymes studied. Hexokinase is considered to be one of the major rate determining enzymes for the glycolytic catabolism of carbohydratcs and the subsequent production of nucleotidc triphophosphates which are vital in active transport mechanisms. This could indicate an important role for this enzyme in blood-brain barrier kinetics. 相似文献
35.