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Search Results: 1 - 10 of 147312 matches for " Alex K Harris "
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Oxidative stress and the use of antioxidants in diabetes: Linking basic science to clinical practice
Jeanette Johansen, Alex K Harris, David J Rychly, Adviye Ergul
Cardiovascular Diabetology , 2005, DOI: 10.1186/1475-2840-4-5
Abstract: It is a well-established fact that diabetes is a risk factor for cardiovascular disease [1,2]. While microvascular complications of diabetes include nephropathy and retinopathy, macrovascular complications resulting in atherosclerotic cardiovascular disease such as coronary artery disease, cerebrovascular disease and peripheral vascular disease are the leading cause of death in the diabetic population [3,4]. The Diabetes Control and Complications trial (DCCT) demonstrated that tight control of blood glucose is effective in reducing clinical complications significantly, but even optimal control of blood glucose could not prevent complications suggesting that alternative treatment strategies are needed [4]. Since numerous studies demonstrated that oxidative stress, mediated mainly by hyperglycemia-induced generation of free radicals, contributes to the development and progression of diabetes and related contributions, it became clear that ameliorating oxidative stress through treatment with antioxidants might be an effective strategy for reducing diabetic complications. To this end, several clinical trials investigated the effect of the antioxidant vitamin E on the prevention of diabetic complications. However, these trials failed to demonstrate relevant clinical benefits of this antioxidant on cardiovascular disease [5-7]. The negative results of the clinical trials with antioxidants prompted new studies focusing on the mechanisms of oxidative stress in diabetes in order to develop causal antioxidant therapy. In this article, sources of free radicals contributing to oxidative stress and the natural defense mechanisms in diabetes are briefly reviewed. Experimental and clinical evidence with respect to the use of conventional antioxidants in diabetes is summarized and causal therapy approaches with novel antioxidants are discussed.Oxidative stress is defined in general as excess formation and/or insufficient removal of highly reactive molecules such as reactive oxygen
Common statistical and research design problems in manuscripts submitted to high-impact medical journals
Sara Fernandes-Taylor, Jenny K Hyun, Rachelle N Reeder, Alex HS Harris
BMC Research Notes , 2011, DOI: 10.1186/1756-0500-4-304
Abstract: The Editors-in-Chief and statistical reviewers of the 38 medical journals with the highest impact factor in the 2007 Science Journal Citation Report and the 2007 Social Science Journal Citation Report were invited to complete an online survey about the statistical and design problems they most frequently found in manuscripts. Content analysis of the responses identified major issues. Editors and statistical reviewers (n = 25) from 20 journals responded. Respondents described problems that we classified into two, broad themes: A. statistical and sampling issues and B. inadequate reporting clarity or completeness. Problems included in the first theme were (1) inappropriate or incomplete analysis, including violations of model assumptions and analysis errors, (2) uninformed use of propensity scores, (3) failing to account for clustering in data analysis, (4) improperly addressing missing data, and (5) power/sample size concerns. Issues subsumed under the second theme were (1) Inadequate description of the methods and analysis and (2) Misstatement of results, including undue emphasis on p-values and incorrect inferences and interpretations.The scientific quality of submitted manuscripts would increase if researchers addressed these common design, analytical, and reporting issues. Improving the application and presentation of quantitative methods in scholarly manuscripts is essential to advancing medical research.Attention to statistical quality in medical research has increased in recent years owing to the greater complexity of statistics in medicine and the focus on evidence-based practice. The editors and statistical reviewers of medical journals are charged with evaluating the scientific merit of submitted manuscripts, often requiring authors to conduct further analysis or content revisions to ensure the transparency and appropriate interpretation of results. Still, many manuscripts are rejected because of irreparable design flaws or inappropriate analytical strategi
Effect of neutrophil depletion on gelatinase expression, edema formation and hemorrhagic transformation after focal ischemic stroke
Alex K Harris, Adviye Ergul, Anna Kozak, Livia S Machado, Maribeth H Johnson, Susan C Fagan
BMC Neuroscience , 2005, DOI: 10.1186/1471-2202-6-49
Abstract: Anti-PMN treatment caused successful depletion of neutrophils in treated animals. There was no difference in either infarct volume or hemorrhage between control and PMN depleted animals. While there were significant increases in gelatinase (MMP-2 and MMP-9) expression and activity and edema formation associated with ischemia, neutrophil depletion failed to cause any change.The main finding of this study is that, in the absence of circulating neutrophils, MMP-2 and MMP-9 expression and activity are still up-regulated following focal cerebral ischemia. Additionally, neutrophil depletion had no influence on indicators of ischemic brain damage including edema, hemorrhage, and infarct size. These findings indicate that, at least acutely, neutrophils are not a significant contributor of gelatinase activity associated with acute neurovascular damage after stroke.The matrix metalloproteinases (MMPs) are a family of some 23 zinc dependent proteases that, collectively, possess the ability to degrade nearly every component of the extra-cellular matrix [1-3]. The activity of the MMPs is tightly controlled through proteolytic activation of the zymogen forms and stoichiometric binding of tissue inhibitors of metalloproteinases (TIMPs). The MMPs play an important role in many physiological processes due to their inherent ability to remodel tissues [2,3]. However, in disease states such as vascular disease and stroke, the MMPs may become deleterious due to dysregulation and can result in tissue injury and inflammation. Specifically, the MMPs may be involved in the degradation of the basal lamina in reperfusion injury resulting in disruption of the blood brain barrier and hemorrhagic transformation [4].Recently, several lines of evidence have demonstrated the involvement of the MMPs in cerebral ischemia. Studies in rat, mouse, and baboon models have shown that MMP-9 is up-regulated following transient focal ischemia [5-8]. Additionally, Asahi et al. have shown that MMP-9 knockout as
Module Selection in Microarchitectural Synthesis forMultiple Critical Constraint Satisfaction
Ian G. Harris,Alex Orailoğlu
VLSI Design , 1997, DOI: 10.1155/1997/81902
Abstract:
Regression Conformal Prediction with Nearest Neighbours
Harris Papadopoulos,Vladimir Vovk,Alex Gammerman
Computer Science , 2014, DOI: 10.1613/jair.3198
Abstract: In this paper we apply Conformal Prediction (CP) to the k-Nearest Neighbours Regression (k-NNR) algorithm and propose ways of extending the typical nonconformity measure used for regression so far. Unlike traditional regression methods which produce point predictions, Conformal Predictors output predictive regions that satisfy a given confidence level. The regions produced by any Conformal Predictor are automatically valid, however their tightness and therefore usefulness depends on the nonconformity measure used by each CP. In effect a nonconformity measure evaluates how strange a given example is compared to a set of other examples based on some traditional machine learning algorithm. We define six novel nonconformity measures based on the k-Nearest Neighbours Regression algorithm and develop the corresponding CPs following both the original (transductive) and the inductive CP approaches. A comparison of the predictive regions produced by our measures with those of the typical regression measure suggests that a major improvement in terms of predictive region tightness is achieved by the new measures.
Reviewer acknowledgement 2012
Harris Philippa K
BMC Microbiology , 2013, DOI: 10.1186/1471-2180-13-21
Abstract: Contributing reviewers The editors of BMC Microbiology would like to thank all our reviewers who have contributed to the journal in Volume 12 (2012).
Reviewer acknowledgement 2012
Harris Philippa K
BMC Developmental Biology , 2013, DOI: 10.1186/1471-213x-13-5
Abstract: Contributing reviewers The editors of BMC Developmental Biology would like to thank all our reviewers who have contributed to the journal in Volume 12 (2012).
Excerpt from God’s Arbiters: Americans and the Philippines, 1898–1902
Susan K. Harris
Journal of Transnational American Studies , 2011,
Abstract:
A remark on the Schottky locus in genus 4
J. Harris,K. Hulek
Mathematics , 2003,
Abstract: We determine the class of the (closure of the) Schottky locus in genus 4 in the Igusa- and the Voronoi compactification of A_4 and comment on the weight 8 modular form which vanishes on it.
Sphk1 Expression and Survival Outcomes in Squamous Cell Carcinoma of the Oral Cavity  [PDF]
Brianna N. Harris, Rizwan Masood, Uttam K. Sinha
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.43086
Abstract:

Sphingosine kinase 1 (SphK1) is an important mediator of apoptosis and the proliferation of cancer cells. It is upregulated in cells showing increasing radioresistance. Here we present the correlation between SphK1 expression and survival outcomes in patients with carcinoma of the oral cavity. A retrospective chart review was performed between January 2009 and August 2010 at the University of Southern California. Patients diagnosed with an advanced-stage primary tumor restricted to the oral cavity and a minimum follow-up of two years were included. Patients who did not receive post-operative radiation therapy were excluded. Eighteen patients met the inclusion criteria with 10 (55.6%) patients demonstrating high expression of SphK1 and 8 (44.4%) patients demonstrating a low-to-moderate expression of SphK1. Tumor recurrence occurred in 9 patients (50.0%): 5 patients (27.8%) in the SphK1high cohort at a mean time to progression of 2.5 mo and 4 patients (22.2%) in the SphK1low cohort at a mean time to progression of 11.0 mo (p = 0.023). Death occurred in 8 patients (66.7%) in the SphK1high cohort and 3 patients (16.7%) in the SphK1low cohort (p = 0.036). Higher expression of SphK1 correlates with greater radioresistance and poorer survival outcomes in patients with HNSCC of the oral cavity.

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