45 research outputs found

    SAMHD1 is a biomarker for cytarabine response and a therapeutic target in acute myeloid leukemia.

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    The nucleoside analog cytarabine (Ara-C) is an essential component of primary and salvage chemotherapy regimens for acute myeloid leukemia (AML). After cellular uptake, Ara-C is converted into its therapeutically active triphosphate metabolite, Ara-CTP, which exerts antileukemic effects, primarily by inhibiting DNA synthesis in proliferating cells. Currently, a substantial fraction of patients with AML fail to respond effectively to Ara-C therapy, and reliable biomarkers for predicting the therapeutic response to Ara-C are lacking. SAMHD1 is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase that cleaves physiological dNTPs into deoxyribonucleosides and inorganic triphosphate. Although it has been postulated that SAMHD1 sensitizes cancer cells to nucleoside-analog derivatives through the depletion of competing dNTPs, we show here that SAMHD1 reduces Ara-C cytotoxicity in AML cells. Mechanistically, dGTP-activated SAMHD1 hydrolyzes Ara-CTP, which results in a drastic reduction of Ara-CTP in leukemic cells. Loss of SAMHD1 activity-through genetic depletion, mutational inactivation of its triphosphohydrolase activity or proteasomal degradation using specialized, virus-like particles-potentiates the cytotoxicity of Ara-C in AML cells. In mouse models of retroviral AML transplantation, as well as in retrospective analyses of adult patients with AML, the response to Ara-C-containing therapy was inversely correlated with SAMHD1 expression. These results identify SAMHD1 as a potential biomarker for the stratification of patients with AML who might best respond to Ara-C-based therapy and as a target for treating Ara-C-refractory AML

    Levers of change: a review of contemporary interventions to enhance diversity in medical schools in the USA

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    Alexis Danielle Vick,1 Aaron Baugh,2 Julie Lambert,1 Allison A Vanderbilt,3 Evan Ingram,1 Richard Garcia,4 Reginald F Baugh5 1College of Medicine and Life Sciences, 2Department of Internal Medicine, 3Department of Family Medicine, College of Medicine and Life Science, University of Toledo, Toledo, OH, 4Consultant, The Ethnic Health Institute, Oakland, CA, 5Department of Surgery, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA Abstract: A growing body of research illustrates the importance of aligning efforts across the operational continuum to achieve diversity goals. This alignment begins with the institutional mission and the message it conveys about the priorities of the institution to potential applicants, community, staff, and faculty. The traditional themes of education, research, and service dominate most medical school mission statements. The emerging themes of physician maldistribution, overall primary-care physician shortage, diversity, and cost control are cited less frequently. The importance and salience of having administrative leaders with an explicit commitment to workforce and student diversity is a prominent and pivotal factor in the medical literature on the subject. Organizational leadership shapes the general work climate and expectations concerning diversity, recruitment, and retention. Following the Bakke decision, individual medical schools, supported by the Association of American Medical Colleges, worked to expand the frame of reference for evaluating applicants for medical school. These efforts have come together under the rubric of “holistic review”, permitted by the US Supreme Court in 2003. A large diverse-applicant pool is needed to ensure the appropriate candidates can be chosen for the incoming medical school class. Understanding the optimal rationale and components for a successful recruitment program is important. Benchmarking with other schools regionally and nationally will identify what should be the relative size of a pool. Diversity is of compelling interest to us all, and should pervade all aspects of higher education, including admissions, the curriculum, student services and activities, and our faculties. The aim of medical education is to cultivate a workforce with the perspectives, aptitudes, and skills needed to fuel community-responsive health-care institutions. A commitment toward diversity needs to be made. Keywords: diversity, inclusion, medical school admissions, admissions committe
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