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6409 citation(s) found for "Ma, Christopher".

Circadian Disruption and Diet-Induced Obesity Synergize to Promote Development of β-Cell Failure and Diabetes in Male Rats
Qian, Jingyi , Yeh, Bonnie, Rakshit, Kuntol, Colwell, Christopher S. , Matveyenko, Aleksey V.

Endocrinology | September 8, 2015 | Volume: 156 | Issue: 12 | Pages: 4426-4436

10.1210/en.2015-1516 | PMID 26348474 Get It

There are clear epidemiological associations between circadian disruption, obesity, and pathogenesis of type 2 diabetes. The mechanisms driving these associations are unclear. In the current study, we hypothesized that continuous exposure to constant light (LL) compromises pancreatic β-cell functional and morphological adaption to diet-induced obesity leading to development of type 2 diabetes. To address this hypothesis, we studied wild type Sprague Dawley as well as Period-1 luciferase reporter transgenic rats (Per1-Luc) for 10 weeks under standard light-dark cycle (LD) or LL with concomitant ad libitum access to either standard chow or 60% high-fat diet (HFD). Exposure to HFD led to a comparable increase in food intake, body weight, and adiposity in both LD- and LL-treated rats. However, LL rats displayed profound loss of behavioral circadian rhythms as well as disrupted pancreatic islet clock function characterized by the impairment in the amplitude and the phase islet clock oscillations. Under LD cycle, HFD did not adversely alter diurnal glycemia, diurnal insulinemia, β-cell secretory function as well as β-cell survival, indicating successful adaptation to increased metabolic demand. In contrast, concomitant exposure to LL and HFD resulted in development of hyperglycemia characterized by loss of diurnal changes in insulin secretion, compromised β-cell function, and induction of β-cell apoptosis. This study suggests that circadian disruption and diet-induced obesity synergize to promote development of β-cell failure, likely mediated as a consequence of impaired islet clock function.
Desiderata for computable representations of electronic health records-driven phenotype algorithms
Mo, Huan , Thompson, William K. , Rasmussen, Luke V. , Pacheco, Jennifer A. , Jiang, Guoqian , Kiefer, Richard C. , Zhu, Qian , Xu, Jie , Montague, Enid , Mentch, Frank , Ni, Yizhao , Wehbe, Firas , Peissig, Peggy , Tromp, Gerard , Larson, Eric B. , Pathak, Jyotishman , Denny, Joshua C. , Speltz, Peter, Jarvik, Gail P. , Bejan, Cosmin A, Borthwick, Kenneth M., Kitchner, Terrie, Roden, Dan M. , Bejan, Cosmin A. , Kiefer, Richard, Carrell, David , Lingren, Todd , Chute, Christopher G. , Kho, Abel , Bejan, Cosmin A, Williams, Marc S , Roden, Dan M. , Harris, Paul A. , Denny, Joshua C , Jarvik, Gail P , Rasmussen, Luke V , Pacheco, Jennifer A

Journal of the American Medical Informatics Association | September 6, 2015 | Volume: 22 | Issue: 6 | Pages: 1220-1230

10.1093/jamia/ocv112 | PMID 26342218 Get It

AbstractBackground Electronic health records (EHRs) are increasingly used for clinical and translational research through the creation of phenotype algorithms. Currently, phenotype algorithms are most commonly represented as noncomputable descriptive documents and knowledge artifacts that detail the protocols for querying diagnoses, symptoms, procedures, medications, and/or text-driven medical concepts, and are primarily meant for human comprehension. We present desiderata for developing a computable phenotype representation model (PheRM).Methods A team of clinicians and informaticians reviewed common features for multisite phenotype algorithms published in PheKB.org and existing phenotype representation platforms. We also evaluated well-known diagnostic criteria and clinical decision-making guidelines to encompass a broader category of algorithms.Results We propose 10 desired characteristics for a flexible, computable PheRM: (1) structure clinical data into queryable forms; (2) recommend use of a common data model, but also support customization for the variability and availability of EHR data among sites; (3) support both human-readable and computable representations of phenotype algorithms; (4) implement set operations and relational algebra for modeling phenotype algorithms; (5) represent phenotype criteria with structured rules; (6) support defining temporal relations between events; (7) use standardized terminologies and ontologies, and facilitate reuse of value sets; (8) define representations for text searching and natural language processing; (9) provide interfaces for external software algorithms; and (10) maintain backward compatibility.Conclusion A computable PheRM is needed for true phenotype portability and reliability across different EHR products and healthcare systems. These desiderata are a guide to inform the establishment and evolution of EHR phenotype algorithm authoring platforms and languages.
The islet circadian clock: entrainment mechanisms, function and role in glucose homeostasis
Rakshit, Krishna Pada, Qian, Jingyi , Colwell, Christopher S. , Matveyenko, Aleksey V.

Diabetes, Obesity and Metabolism | September 2, 2015 | Volume: 17 | Issue: S1 | Pages: 115-122

10.1111/dom.12523 | PMID 26332976 Get It

Circadian regulation of glucose homeostasis and insulin secretion has long been appreciated as an important feature of metabolic control in humans. Circadian disruption is becoming increasingly prevalent in today's society and is likely responsible in part for the considerable rise in type 2 diabetes ( T2DM ) and metabolic syndrome worldwide. Thus, understanding molecular mechanisms driving the inter‐relationship between circadian disruption and T2DM is important in context of disease prevention and therapeutics. In this regard, the goal of this article is to highlight the role of the circadian system, and islet circadian clocks in particular, as potential regulators of β‐cell function and survival. To date, studies have shown that islet clocks respond to changes in feeding patterns, and regulate a multitude of critical cellular processes in insulin secreting β‐cells (e.g. insulin exocytosis, mitochondrial function and response to oxidative stress). Subsequently, either genetic or environmental disruption of normal islet clock performance compromises β‐cell function and leads to loss of glycaemic control. Future work is warranted to further unravel the role of circadian clocks in human islet function in health and contributions to pathogenesis of T2DM .
Genome-Wide Association Study of Prostate Cancer–Specific Survival
Szulkin, Robert , Whitington, Thomas, Aly, Markus , Grönberg, Henrik , Eeles, Rosalind A. , Easton, Douglas F. , Olama, Ali Amin Al , Benlloch, Sara, Muir, Kenneth , Giles, Graham G. , Southey, Melissa C. , FitzGerald, Liesel M. , Henderson, Brian E., Schumacher, Fredrick R. , Haiman, Christopher A. , Sipeky, Csilla , Tammela, Teuvo L.J. , Nordestgaard, Børge G. , Travis, Ruth C. , Neal, David E. , Donovan, Jenny , Hamdy, Freddie C. , Pashayan, Nora , Stanford, Janet L. , Thibodeau, Stephen N. , McDonnell, Shannon K. , Schaid, Daniel J. , Maier, Christiane, Vogel, Walther , Luedeke, Manuel, Herkommer, Kathleen , Kibel, Adam S. , Lubiński, Jan , Kluźniak, Wojciech , Cannon‐Albright, Lisa , Brenner, Hermann , Herrmann, Volker, Holleczek, Bernd , Sellers, Thomas A. , Lim, Hui-Yi, Kaneva, Radka , Mitev, Vanio , Teixeira, Manuel R. , Paulo, Paula , Maia, Sofia , Pandha, Hardev , Michael, Agnieszka , Batra, Jyotsna , Clements, Judith A. , BioResource, on behalf of the Australian Prostate Cancer, Albanes, Demetrius, Andriole, Gerald L. , Berndt, Sonja I., Gapstur, Susan M. , Giovannucci, Edward L. , Ma, Jing , Mondul, Alison M. , Stampfer, Meir J. , Stevens, Victoria L. , Weinstein, Stephanie J. , Trichopoulou, Antonia , Bueno-de-Mesquita, Bas H., Tjønneland, Anne , Cox, David G. , Mæhle, Lovise, Schleutker, Johanna , Lindström, Sara , Karlsson, Robert , Kote‐Jarai, Zsofia , Key, Tim , Pharoah, Paul D.P. , Khaw, Kay‐Tee , Cybulski, Cezary , Park, Jong Y. , Slavov, Chavdar , Spurdle, Amanda B. , Kierzek, Andrzej , BioResource, on behalf of the Australian Prostate Cancer, Berndt, Sonja I. , Chanock, Stephen Jacob , Hunter, David J. , Kraft, Peter , Marchand, Loı̈c Le , Penney, Kathryn , Wiklund, Fredrik E. , Giles, Graham G , Teixeira, Manuel R , Eeles, Rosalind A , Southey, Melissa C , Tjønneland, Anne , Donovan, Jenny L , Muir, Kenneth , Schleutker, Johanna , Travis, Ruth C , Pashayan, Nora , Cannon-Albright, Lisa A , Michael, Agnieszka , Brenner, Hermann , Batra, Jyotsna , Clements, Judith , Lubinski, Jan , McDonnell, Shannon K

Cancer Epidemiology, Biomarkers & Prevention | August 25, 2015 | Volume: 24 | Issue: 11 | Pages: 1796-1800

10.1158/1055-9965.epi-15-0543 | PMID 26307654 Get It

Abstract Background: Unnecessary intervention and overtreatment of indolent disease are common challenges in clinical management of prostate cancer. Improved tools to distinguish lethal from indolent disease are critical. Methods: We performed a genome-wide survival analysis of cause-specific death in 24,023 prostate cancer patients (3,513 disease-specific deaths) from the PRACTICAL and BPC3 consortia. Top findings were assessed for replication in a Norwegian cohort (CONOR). Results: We observed no significant association between genetic variants and prostate cancer survival. Conclusions: Common genetic variants with large impact on prostate cancer survival were not observed in this study. Impact: Future studies should be designed for identification of rare variants with large effect sizes or common variants with small effect sizes. Cancer Epidemiol Biomarkers Prev; 24(11); 1796–800. ©2015 AACR.
Aβ-degrading enzymes: modulators of Alzheimer's disease pathogenesis and targets for therapeutic intervention
Eckman, Christopher B., Eckman, Elizabeth A.

Biochemical Society Transactions | August 11, 2015 | Volume: 33 | Issue: 5 | Pages: 1101-1105

10.1042/bst0331101 Get It

The accumulation of Aβ (amyloid β-protein) peptides in the brain is a pathological hallmark of all forms of AD (Alzheimer's disease) and reducing Aβ levels can prevent or reverse cognitive deficits in mouse models of the disease. Aβ is produced continuously and its concentration is determined in part by the activities ofseveral degradative enzymes, including NEP (neprilysin), IDE (insulin-degrading enzyme), ECE-1 (endothelinconverting enzyme 1) and ECE-2, and probably plasmin. Decreased activity of any of these enzymes due to genetic mutation, or age- or disease-related alterations in gene expression or proteolytic activity, may increase the risk for AD. Conversely, increased expression of these enzymes may confer a protective effect. Increasing Aβ degradation through gene therapy, transcriptional activation or even pharmacological activation of the Aβ-degrading enzymes represents a novel therapeutic strategy for the treatment of AD that is currently being evaluated in cell-culture and animal models. In this paper, we will review the roles of NEP, IDE, ECE and plasmin in determining endogenous Aβ concentration, highlighting recent results concerning the regulation of these enzymes and their potential as therapeutic targets.
Diabetes Mellitus as a Risk Factors for Death following Acute Pulmonary Embolism
Scott, J. Christopher, Peters, S.A.

Clinical Science | August 7, 2015 | Volume: 98 | Issue: s42 | Pages: 15P-15P

10.1042/cs098015p Get It

Abstract 1360: Combination therapy of reovirus and PD-1 blockade effectively establishes tumor control via innate and adaptive immune responses
Parrish, Christopher , Errington‐Mais, Fiona , Thompson, Jill , Kottke, Tim , Maria-Diaz, Rosa, Selby, Peter J. , Pandha, Hardev , Harrington, Kevin J. , Melcher, Alan , Zaidi, Shane, Vile, Richard G. , Rajani, Karishma , Shim, Kevin G. , Ilett, Elizabeth J. , Coffey, Matt C. , Errington-Mais, Fiona , Melcher, Alan A , Harrington, Kevin

Cancer Research | August 5, 2015 | Volume: 75 | Issue: 15_Supplement | Pages: 1360-1360

10.1158/1538-7445.am2015-1360 Get It

Abstract We have developed the use of reovirus as a systemically delivered oncolytic agent in both pre-clinical models and in early Phase clinical trials. Reovirus has direct oncolytic activity against many human/murine tumor cells, partly because of disruption of the PKR-mediated anti-viral response in malignant cells. In addition however, we have shown that anti-tumor therapy is directly associated with immune activation by virus replication in tumors. The immune mechanisms of therapy include both innate immune activation against virally infected tumor cells, as well as the generation of adaptive anti tumor immune responses as a result of in vivo priming against tumor associated antigens released during that killing. Therefore, to exploit the immune components of reovirus anti-tumor therapy, we hypothesized that the combination of reovirus therapy with systemic checkpoint inhibition would augment therapeutic efficacy. To test the hypothesis, we used C57Bl/6 mice, an immune-competent murine model, with established subcutaneous (s.c.) B16 melanomas. In this model, intra-tumoral injection of reovirus into s.c. tumors generated moderate therapy. Provision of systemic anti-PD-1 antibody along with i.t. reovirus, significantly enhanced survival compared to i.t. reovirus alone (p<0.01) and led to >40% of mice being cured long term. Immune analysis suggested that the enhanced therapeutic benefit of reovirus plus checkpoint inhibition is contributed by at least two factors. First, blockade of PD-1 significantly enhanced the ability of NK cells to recognize (TNF-α secretion), and kill, reovirus-infected target tumor cells. Second, anti PD-1 antibody led to a significant reduction in Treg activity in reovirus-treated mice, with the overall effect of increasing the adaptive CD8+ anti-tumor T cell response. Furthermore, in vivo depletion studies demonstrated that NK cells had a dramatic effect in reducing the therapeutic efficacy of reovirus plus anti-PD-1 therapy. Overall, the results indicate that combination therapy of reovirus with PD-1 blockade confers significant survival benefit, by augmenting tumor-specific NK responses and specifically attenuating tumor-specific immunosuppression. These data also suggest that combination of PD-1 inhibition therapy with reovirus oncolytic/immunotherapy represents a readily translatable method to enhance the therapeutic efficacy. Citation Format: Karishma Rajani, Christopher Parrish, Kevin Shim, Liz Ilett, Fiona Errington-Mais, Jill Thompson, Tim Kottke, Rosa Maria-Diaz, Peter Selby, Hardev Pandha, Kevin Harrington, Alan Melcher, Matt Coffey, Shane Zaidi, Richard Vile. Combination therapy of reovirus and PD-1 blockade effectively establishes tumor control via innate and adaptive immune responses. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1360. doi:10.1158/1538-7445.AM2015-1360