Stephen J. O'Brien

Bio: Stephen J. O'Brien is an academic researcher from Saint Petersburg State University of Information Technologies, Mechanics and Optics. The author has contributed to research in topics: Population & Gene. The author has an hindex of 153, co-authored 1062 publications receiving 93025 citations. Previous affiliations of Stephen J. O'Brien include University College Cork & QIMR Berghofer Medical Research Institute.

Deteminants of cross‐contamination during home food preparation

Abstract: Purpose – This paper aims to determine the potential for the spread of bacteria from raw meat and poultry during home food preparation to the surrounding kitchen environment, hands and prepared food due to unsafe handling practices, which are predicted by consumers' knowledge, behaviour and attitudes.Design/methodology/approach – The potential for transfer of E.coli and C. jejuni was monitored in a simulated domestic kitchen environment while food preparation was filmed (n=60 respondents). A survey was also administered.Findings – The results of the study show that transfer of bacteria around the kitchen environment and onto prepared meals are predicted by a lack of thoroughly washing contaminated hands, knives and chopping boards both during and after meal preparation. A higher level of perceived importance of correct food handling behaviour is associated with higher levels of educational attainment and age and food risk perceptions are positively associated with age.Practical implications – The results ...

Feline Lymphomas: Immunological and Cytochemical Characterization

Abstract: The immunological and cytochemical phenotypes of five primary feline lymphomas and six feline lymphoma lines are reported. Thymic lymphomas induced by the Rickard strain of FeLV (FeLV-R) are of prothymocyte or (immature) cortical thymocyte origin, as these express terminal deoxynucleotidyl transferase, the guinea pig erythrocyte rosette receptor, Ia antigens, partial cortisone sensitivity, and nonspecific esterase. Lymphomas associated with other strains of FeLV form rosettes with guinea pig erythrocytes, frequently have Ia antigens and cytoplasmic nonspecific esterase, and probably originate from helper T-cells, monocyte/macrophages, or null cells. These data belie previous conclusions that FeLV leukemogenesis is restricted to mature T-cells; rather, the considerable heterogeneity in the surface and cytochemical phenotype of feline lymphomas probably reflects transformation of multipotent lymphoid or monocytoid precursors in the bone marrow by FeLV.

A comparative chromosome banding analysis of the Ursidae and their relationship to other carnivores

Abstract: Trypsin G-banded karyotypes of eight species of Ursidae were prepared from retrovirus-transformed skin fibroblast cultures. The banding patterns of all bears are highly conserved, even though their diploid numbers range from 42 to 72. A comprehensive analysis of the homologous banding patterns within the Ursidae and with a hypothesized ancestral carnivore karyotype permitted the reconstruction of three significant chromosomal reorganization events that occurred during the evolution of the modern ursids. The first was a multichromosomal fissioning away from the biarmed (2n = 44) primitive carnivore karyotype, leading to six species of the Ursinae subfamily (2n = 78). The second was a comprehensive chromosome fusion in the lineage that led to the Ailuropodinae (giant panda) subfamily (2n = 44). The third event was a second, independent, but less extensive, centromeric fusion occurring in the line that led to the Tremarctinae (spectacled bear) subfamily (2n = 52). Ursidae karyotypes are not only highly conserved within the family but also exhibit extensive chromosome banding homology with other carnivore families.

Molecular Phylogeny and Dating of Early Primate Divergences

Abstract: Rapid evolutionary radiations characterize many higher-level taxa. This pattern of diversification poses a challenge for accurate phylogenetic reconstruction, since the few synapomorphies defining short internal branches are often overwritten over long periods of evolutionary time, making determination of homology difficult and rendering the outgroup method of rooting prone to error for both molecular and morphological systematic investigations (Carroll, 1988; Novacek, 1992; Swofford et al., 1996). These issues can be addressed and hopefully overcome by employing comprehensive taxon sampling, large numbers of characters, multiple data sets (derived from different sources), and diverse inferential techniques. In spite of being limited to samples of only living or recently extinct taxa, molecular data have great potential to help decipher the pattern and timing of rapid and ancient radiations. Specifically, they provide a means to collect larger numbers of phylogenetic characters than most morphological data matrices, and present a simpler and better understood mode of evolution that can be currently modeled within a maximum likelihood (ML) framework (e.g., Goldman et al., 2000; Swofford et al., 1996; Whelan et al., 2001).

Initial sequencing and analysis of the human genome.

Abstract: The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls

Abstract: There is increasing evidence that genome-wide association ( GWA) studies represent a powerful approach to the identification of genes involved in common human diseases. We describe a joint GWA study ( using the Affymetrix GeneChip 500K Mapping Array Set) undertaken in the British population, which has examined similar to 2,000 individuals for each of 7 major diseases and a shared set of similar to 3,000 controls. Case-control comparisons identified 24 independent association signals at P < 5 X 10(-7): 1 in bipolar disorder, 1 in coronary artery disease, 9 in Crohn's disease, 3 in rheumatoid arthritis, 7 in type 1 diabetes and 3 in type 2 diabetes. On the basis of prior findings and replication studies thus-far completed, almost all of these signals reflect genuine susceptibility effects. We observed association at many previously identified loci, and found compelling evidence that some loci confer risk for more than one of the diseases studied. Across all diseases, we identified a large number of further signals ( including 58 loci with single-point P values between 10(-5) and 5 X 10(-7)) likely to yield additional susceptibility loci. The importance of appropriately large samples was confirmed by the modest effect sizes observed at most loci identified. This study thus represents a thorough validation of the GWA approach. It has also demonstrated that careful use of a shared control group represents a safe and effective approach to GWA analyses of multiple disease phenotypes; has generated a genome-wide genotype database for future studies of common diseases in the British population; and shown that, provided individuals with non-European ancestry are excluded, the extent of population stratification in the British population is generally modest. Our findings offer new avenues for exploring the pathophysiology of these important disorders. We anticipate that our data, results and software, which will be widely available to other investigators, will provide a powerful resource for human genetics research.