121 results on '"Larson RS"'
Search Results
2. Absence of biallelic TCRgamma deletion predicts early treatment failure in pediatric T-cell acute lymphoblastic leukemia.
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Gutierrez A, Dahlberg SE, Neuberg DS, Zhang J, Grebliunaite R, Sanda T, Protopopov A, Tosello V, Kutok J, Larson RS, Borowitz MJ, Loh ML, Ferrando AA, Winter SS, Mullighan CG, Silverman LB, Chin L, Hunger SP, Sallan SE, and Look AT
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- 2010
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3. High-sensitivity bone marrow aspiration technology enhances detection of leukemia cells.
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Larson RS
- Published
- 2009
4. Relationship of CD4 and CD34 expression in acute leukemia [letter; comment]
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Larson, RS and McCurley, TL 3rd
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- 1995
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5. Next steps in designing for diffusion of pre-exposure prophylaxis: demonstration projects.
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Dearing JW, Norton WE, and Larson RS
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- 2013
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6. A Comparison of Pediatric Mental Health Diagnoses and Selective Serotonin Reuptake Inhibitor Prescribing Before and During the COVID-19 Pandemic.
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Keares PP, Pho NT, Larson RS, and Vallejo JC
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- Humans, Child, Pandemics, Mental Health, Cross-Sectional Studies, Selective Serotonin Reuptake Inhibitors therapeutic use, COVID-19
- Abstract
Purpose: To assess the rate of mental health diagnoses and selective serotonin reuptake inhibitor (SSRI) prescribing before and during the Coronavirus Disease 2019 pandemic., Methods: We conducted a cross-sectional study at an ambulatory pediatric clinic. A prepandemic (June 2018 to June 2019) and intrapandemic (June 2020 to June 2021) cohort were reviewed. The rate of mental health visits and new SSRI prescriptions were compared. Chi-squared analyses demonstrated a variance of statistical significance., Results: From 15,414 encounters (9,791 prepandemic and 5,623 intrapandemic), 397 mental health encounters were identified. 231 (4.1%) encounters occurred during the pandemic (vs. 1.7% prepandemic) and 63 (27.3%) SSRIs were prescribed (vs. 5.4% prepandemic). Mental health encounters (prevalence ratio 2.42, 95% confidence interval, 1.99-2.95, p < .001) and SSRI prescriptions (prevalence ratio 5.03, 95% confidence interval, 2.58-9.82, p < .001) were higher during the pandemic., Discussion: Our findings demonstrate increased rates of SSRI prescribing and mental health diagnoses during the Coronavirus Disease 2019 pandemic, suggesting an increased incidence of these conditions. Clinicians should be prepared to manage and screen for mental health conditions., (Published by Elsevier Inc.)
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- 2023
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7. An Effective Intervention: Limiting Opioid Prescribing as a Means of Reducing Opioid Analgesic Misuse, and Overdose Deaths.
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Fink BC, Uyttebrouck O, and Larson RS
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- Federal Government, Government Regulation, Humans, State Government, United States epidemiology, Analgesics, Opioid therapeutic use, Opiate Overdose mortality, Practice Patterns, Physicians' legislation & jurisprudence, Practice Patterns, Physicians' statistics & numerical data, Practice Patterns, Physicians' trends, Prescription Drug Misuse trends
- Abstract
Overdose deaths involving prescription opioids killed more than 17,000 Americans in 2017, marking a five-fold increase since 1999. High prescribing rates of opioid analgesics have been a substantial contributor to prescription opioid misuse, dependence, overdose and heroin use. There was recognition approximately ten years ago that opioid prescribing patterns were contributing to this startling increase in negative opioid-related outcomes, and federal actions, including Medicare reimbursement reform and regulatory actions, were initiated to restrict opioid prescribing. The current manuscript is a description of those actions, the effect of those actions on opioid prescribing and related patient outcomes. We also describe our proposal of methods of expanding these efforts as an important piece to further reduce opioid-related misuse, dependence, and overdose death.
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- 2020
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8. Toward the improvement of total nitrogen deposition budgets in the United States.
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Walker JT, Beachley G, Amos HM, Baron JS, Bash J, Baumgardner R, Bell MD, Benedict KB, Chen X, Clow DW, Cole A, Coughlin JG, Cruz K, Daly RW, Decina SM, Elliott EM, Fenn ME, Ganzeveld L, Gebhart K, Isil SS, Kerschner BM, Larson RS, Lavery T, Lear GG, Macy T, Mast MA, Mishoe K, Morris KH, Padgett PE, Pouyat RV, Puchalski M, Pye HOT, Rea AW, Rhodes MF, Rogers CM, Saylor R, Scheffe R, Schichtel BA, Schwede DB, Sexstone GA, Sive BC, Sosa Echeverría R, Templer PH, Thompson T, Tong D, Wetherbee GA, Whitlow TH, Wu Z, Yu Z, and Zhang L
- Abstract
Frameworks for limiting ecosystem exposure to excess nutrients and acidity require accurate and complete deposition budgets of reactive nitrogen (Nr). While much progress has been made in developing total Nr deposition budgets for the U.S., current budgets remain limited by key data and knowledge gaps. Analysis of National Atmospheric Deposition Program Total Deposition (NADP/TDep) data illustrates several aspects of current Nr deposition that motivate additional research. Averaged across the continental U.S., dry deposition contributes slightly more (55%) to total deposition than wet deposition and is the dominant process (>90%) over broad areas of the Southwest and other arid regions of the West. Lack of dry deposition measurements imposes a reliance on models, resulting in a much higher degree of uncertainty relative to wet deposition which is routinely measured. As nitrogen oxide (NO
x ) emissions continue to decline, reduced forms of inorganic nitrogen (NHx = NH3 + NH4 + ) now contribute >50% of total Nr deposition over large areas of the U.S. Expanded monitoring and additional process-level research are needed to better understand NHx deposition, its contribution to total Nr deposition budgets, and the processes by which reduced N deposits to ecosystems. Urban and suburban areas are hotspots where routine monitoring of oxidized and reduced Nr deposition is needed. Finally, deposition budgets have incomplete information about the speciation of atmospheric nitrogen; monitoring networks do not capture important forms of Nr such as organic nitrogen. Building on these themes, we detail the state of the science of Nr deposition budgets in the U.S. and highlight research priorities to improve deposition budgets in terms of monitoring and flux measurements, leaf- to regional-scale modeling, source apportionment, and characterization of deposition trends and patterns., (Published by Elsevier B.V.)- Published
- 2019
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9. Long-term trends of wet inorganic nitrogen deposition in Rocky Mountain National Park: Influence of missing data imputation methods and associated uncertainty.
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Schichtel BA, Gebhart KA, Morris KH, Cheatham JR, Vimont J, Larson RS, and Beachley G
- Abstract
Excess reactive nitrogen (N
r ) deposition is occurring in Rocky Mountain National Park and impacting sensitive ecosystems. In 2006, the National Park Service, State of Colorado, and Environmental Protection Agency established the goal to reduce Nr deposition to below the ecosystem critical load by 2032. Progress is tracked using 5-year averages of annual wet inorganic nitrogen (IN) deposition measured at Loch Vale, Colorado, by the National Atmospheric Deposition Program (NADP). This remote high alpine site is challenging to operate, and large fractions of the annual precipitation, at times >40%, had invalid IN concentrations. Annual wet IN deposition is calculated using the NADP protocol, which replaces missing concentrations with the annual precipitation-weighted mean (PWM) concentration of valid samples. This protocol does not account for seasonal variations in IN concentrations and the inverse relationship between concentration and precipitation amounts. Invalid samples occurred more frequently in the winter and at high and low precipitation amounts, and the NADP protocol generally overestimated annual deposition rates, by as much as 20%. Here, a new method for imputing missing weekly IN concentrations that accounts for their seasonal and precipitation dependence is introduced. Using a bootstrapping analysis shows that the new method reduced the errors in the annual deposition rates by about 30% compared to the NADP protocol and the biases were near zero. The overall trend in the wet IN deposition rates was found to be flat from 1990 to 2017, but the nitrate contribution decreased about 33%, which was offset by a nearly equal increase in ammonium wet deposition. These trends are consistent with known changes in nitrate and ammonium precursor emissions. The long-term trends in the annual IN deposition rates were similar using both data imputation methods, but the 2013-2017 average was about 10% smaller using the new method., (Published by Elsevier B.V.)- Published
- 2019
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10. A Path to Better-Quality mHealth Apps.
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Larson RS
- Abstract
The rapid growth of mobile health (mHealth) apps has resulted in confusion among health care providers and the public about which products rely on evidence-based medicine. Only a small subset of mHealth apps are regulated by the US Food and Drug Administration. The system similar to that used to accredit and certify laboratory testing under the Clinical Laboratory Improvement Amendment offers a potential model for ensuring basic standards of quality and safety for mHealth apps. With these products expanding into the realm of diagnosis and treatment, physicians and consumers are in a strong position to demand oversight that delivers safe and high-quality mHealth apps., (©Richard S Larson. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 30.07.2018.)
- Published
- 2018
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11. Inclusion of special populations in clinical research: important considerations and guidelines.
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Winter SS, Page-Reeves JM, Page KA, Haozous E, Solares A, Nicole Cordova C, and Larson RS
- Abstract
Background: Trials that involve human participants call for experiments or observations that are performed in a clinical research setting. Currently, there are over 16,000 clinical trials open in the United States. Despite continuing efforts to include "special populations" in clinical trials, there are gaps in participation for people who are either minors or elderly adults, are from historically under-represented minorities, or live in rural communities. The inclusion of these special populations in clinical trials research is essential for conclusions that benefit all populations. Data suggest that study partic-ipation rates for special populations have fallen to levels that could endanger the successful performance of some types of research. This is particularly concerning in the 21st century, where demographic trends in the United States continue to shift towards an older and Hispanic population with fewer rural dwellers. Trends in New Mexico and other minority-majority states mirror many of these shifts., Relevance for Patients: In this review, we highlight improvement strategies for enhanced clinical trial participation by members of special populations. Key drivers for disparate clinical trials participation and outcomes often include differences in genetics, physiology, and perceptions of mistrust towards researchers. To overcome these barriers, we focus on best practices in recruitment strategies from the perspectives of the participants, the researchers and the institutions that support clinical trials.
- Published
- 2018
12. Shortage or Surplus of Physicians in the United States.
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Farnbach Pearson AW and Larson RS
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- Humans, United States, Health Services Needs and Demand, Physicians
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- 2017
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13. Health Extension and Clinical and Translational Science: An Innovative Strategy for Community Engagement.
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Kaufman A, Rhyne RL, Anastasoff J, Ronquillo F, Nixon M, Mishra S, Poola C, Page-Reeves J, Nkouaga C, Cordova C, and Larson RS
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- Awards and Prizes, Biomedical Research methods, Financial Management methods, Humans, New Mexico, Universities economics, Biomedical Research economics, Community-Based Participatory Research economics, Community-Institutional Relations economics, Health Priorities economics, Health Services Needs and Demand, Research Personnel economics
- Abstract
Health Extension Regional Officers (HEROs) through the University of New Mexico Health Sciences Center (UNMHSC) help to facilitate university-community engagement throughout New Mexico. HEROs, based in communities across the state, link priority community health needs with university resources in education, service, and research. Researchers' studies are usually aligned with federal funding priorities rather than with health priorities expressed by communities. To help overcome this misalignment, the UNM Clinical and Translational Science Center (CTSC) provides partial funding for HEROs to bridge the divide between research priorities of UNMHSC and health priorities of the state's communities. A bidirectional partnership between HEROs and CTSC researchers was established, which led to: 1) increased community engaged studies through the CTSC, 2) the HERO model itself as a subject of research, 3) a HERO-driven increase in local capacity in scholarship and grant writing, and 4) development of training modules for investigators and community stakeholders on community-engaged research. As a result, 5 grants were submitted, 4 of which were funded, totaling $7,409,002.00, and 3 research articles were published. Health extension can serve as a university-funded, community-based bridge between community health needs and Clinical and Translational Science Award (CTSA) research capacity, opening avenues for translational research., (© Copyright 2017 by the American Board of Family Medicine.)
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- 2017
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14. Novel ABCG2 Antagonists Reverse Topotecan-Mediated Chemotherapeutic Resistance in Ovarian Carcinoma Xenografts.
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Ricci JW, Lovato DM, Severns V, Sklar LA, and Larson RS
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- ATP Binding Cassette Transporter, Subfamily G, Member 2 genetics, Animals, Antineoplastic Agents administration & dosage, Carcinoma drug therapy, Carcinoma pathology, Cell Line, Tumor, Cell Survival drug effects, Disease Models, Animal, Dose-Response Relationship, Drug, Female, Humans, Mice, Ovarian Neoplasms drug therapy, Ovarian Neoplasms genetics, Ovarian Neoplasms pathology, Topotecan administration & dosage, Tumor Burden drug effects, Xenograft Model Antitumor Assays, ATP Binding Cassette Transporter, Subfamily G, Member 2 antagonists & inhibitors, Antineoplastic Agents pharmacology, Carcinoma metabolism, Drug Resistance, Neoplasm genetics, Ovarian Neoplasms metabolism, Topotecan pharmacology
- Abstract
Chemotherapeutic resistance remains a challenge in the treatment of ovarian carcinoma, especially in recurrent disease. Despite the fact that most patients with newly diagnosed tumors attain complete remission following cytoreductive surgery and chemotherapy, ovarian carcinoma has a recurrence rate that exceeds 75%. The ATP-binding cassette family G member 2 (ABCG2) efflux protein has been described as one mechanism that confers multiple-drug resistance to solid tumors and contributes to topotecan resistance in ovarian carcinoma. In fact, one clinical trial demonstrated ABCG2 expression in all patients with primary or recurrent ovarian carcinoma. On the basis of our previous work, we hypothesized that three compounds (CID44640177, CID1434724, and CID46245505), which represent a new piperazine-substituted pyrazolo[1,5]pyrimidine substructure class of ABCG2-specific antagonists, would restore chemosensitivity to drug-resistant ovarian cancer in vitro and in vivo To address the treatment difficulties associated with chemotherapeutic resistance in ovarian cancer, we combined each compound (CID44640177, CID1434724, and CID46245505) with topotecan and administered the mixture to chemoresistant Igrov1/T8 ovarian cancer cells in vitro and Igrov1/T8 xenografts in CB-17 SCID mice. We found that only nanomolar concentrations of each ABCG2 inhibitor in combination with topotecan were required to restore chemosensitivity to Igrov1/T8 cells in vitro In vivo, substantial tumor reduction was achieved with each compound in 4 days, with CID1434724 causing the largest reduction in excess of 60%. No signs of secondary toxic effects were observed with the ABCG2 antagonists. These novel compounds should be viewed as promising drug candidates to reverse ABCG2-mediated chemoresistance. Mol Cancer Ther; 15(12); 2853-62. ©2016 AACR., (©2016 American Association for Cancer Research.)
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- 2016
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15. MLL rearrangements impact outcome in HOXA-deregulated T-lineage acute lymphoblastic leukemia: a Children's Oncology Group Study.
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Matlawska-Wasowska K, Kang H, Devidas M, Wen J, Harvey RC, Nickl CK, Ness SA, Rusch M, Li Y, Onozawa M, Martinez C, Wood BL, Asselin BL, Chen IM, Roberts KG, Baruchel A, Soulier J, Dombret H, Zhang J, Larson RS, Raetz EA, Carroll WL, Winick NJ, Aplan PD, Loh ML, Mullighan CG, Hunger SP, Heerema NA, Carroll AJ, Dunsmore KP, and Winter SS
- Subjects
- Adolescent, Adult, Child, Child, Preschool, Disease-Free Survival, Female, Gene Rearrangement, Humans, Male, Neoplasm Recurrence, Local mortality, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma mortality, Prognosis, Retrospective Studies, Cell Lineage, Drug Resistance, Neoplasm genetics, Histone-Lysine N-Methyltransferase genetics, Homeodomain Proteins genetics, Myeloid-Lymphoid Leukemia Protein genetics, Neoplasm Recurrence, Local genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics
- Abstract
Competing Interests: The authors have no financial conflicts to disclose.
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- 2016
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16. Presentation of Coronary Artery Disease in a Chiropractic Clinic: A Report of 2 Cases.
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Larson RS
- Abstract
Objective: The purpose of this report is to describe 2 patients with coronary artery disease presenting with musculoskeletal symptoms to a chiropractic clinic., Clinical Features: A 48-year-old male new patient had thoracic spine pain aggravated by physical exertion. A 61-year-old man under routine care for low back pain experienced a secondary complaint of acute chest pain during a reevaluation., Intervention and Outcome: In both cases, the patients were strongly encouraged to consult their medical physician and were subsequently diagnosed with coronary artery disease. Following their diagnoses, each patient underwent surgical angioplasty procedures with stenting., Conclusion: Patients may present for chiropractic care with what appears to be musculoskeletal chest pain when the pain may be generating from coronary artery disease necessitating medical and possibly emergency care.
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- 2016
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17. Rapid detection of Ebola virus with a reagent-free, point-of-care biosensor.
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Baca JT, Severns V, Lovato D, Branch DW, and Larson RS
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- Humans, Biosensing Techniques methods, Ebolavirus isolation & purification
- Abstract
Surface acoustic wave (SAW) sensors can rapidly detect Ebola antigens at the point-of-care without the need for added reagents, sample processing, or specialized personnel. This preliminary study demonstrates SAW biosensor detection of the Ebola virus in a concentration-dependent manner. The detection limit with this methodology is below the average level of viremia detected on the first day of symptoms by PCR. We observe a log-linear sensor response for highly fragmented Ebola viral particles, with a detection limit corresponding to 1.9 × 104 PFU/mL prior to virus inactivation. We predict greatly improved sensitivity for intact, infectious Ebola virus. This point-of-care methodology has the potential to detect Ebola viremia prior to symptom onset, greatly enabling infection control and rapid treatment. This biosensor platform is powered by disposable AA batteries and can be rapidly adapted to detect other emerging diseases in austere conditions.
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- 2015
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18. Vision 2020 measures University of New Mexico's success by health of its state.
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Kaufman A, Roth PB, Larson RS, Ridenour N, Welage LS, Romero-Leggott V, Nkouaga C, Armitage K, and McKinney KL
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- Capacity Building methods, Capacity Building organization & administration, Capacity Building standards, Healthy People Programs methods, Healthy People Programs standards, Humans, New Mexico, Organizational Case Studies, Universities, Community-Institutional Relations, Health Priorities, Healthy People Programs organization & administration, Social Determinants of Health
- Abstract
The University of New Mexico Health Sciences Center (UNMHSC) adopted a new Vision to work with community partners to help New Mexico make more progress in health and health equity than any other state by 2020. UNMHSC recognized it would be more successful in meeting communities' health priorities if it better aligned its own educational, research, and clinical missions with their needs. National measures that compare states on the basis of health determinants and outcomes were adopted in 2013 as part of Vision 2020 target measures for gauging progress toward improved health and health care in New Mexico. The Vision focused the institution's resources on strengthening community capacity and responding to community priorities via pipeline education, workforce development programs, community-driven and community-focused research, and community-based clinical service innovations, such as telehealth and "health extension." Initiatives with the greatest impact often cut across institutional silos in colleges, departments, and programs, yielding measurable community health benefits. Community leaders also facilitated collaboration by enlisting University of New Mexico educational and clinical resources to better respond to their local priorities. Early progress in New Mexico's health outcomes measures and state health ranking is a promising sign of movement toward Vision 2020., (Copyright © 2015 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.)
- Published
- 2015
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19. Modeling the efficiency of a magnetic needle for collecting magnetic cells.
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Butler KS, Adolphi NL, Bryant HC, Lovato DM, Larson RS, and Flynn ER
- Subjects
- Microspheres, Nanoparticles chemistry, Polystyrenes chemistry, Time Factors, Cell Separation instrumentation, Magnetic Phenomena, Models, Biological, Needles
- Abstract
As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in (1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and (2) water in which 3, 5, 10 and 100% of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency versus time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium.
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- 2014
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20. Breast cancer screening in an insured population: whom are we missing?
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Kempe KL, Larson RS, Shetterley S, and Wilkinson A
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- Aged, Breast Neoplasms ethnology, Colorado, Delivery of Health Care, Integrated organization & administration, Ethnicity statistics & numerical data, Female, Health Maintenance Organizations statistics & numerical data, Humans, Mass Screening statistics & numerical data, Middle Aged, Patient Acceptance of Health Care ethnology, Regression Analysis, Retrospective Studies, Risk Factors, United States, Breast Neoplasms diagnostic imaging, Mammography, Medically Uninsured statistics & numerical data, Patient Acceptance of Health Care statistics & numerical data
- Abstract
Introduction: Kaiser Permanente Colorado is an integrated health care system that uses automatic reminder programs and reduces barriers to access preventive services, including financial barriers. Breast cancer screening rates have not improved during the last five years, and rates differ between subgroups: for example, black and Latina women have lower rates of mammography screening than other racial groups., Methods: We retrospectively evaluated data from 47,946 women age 52 to 69 years who had continuous membership for 24 months but had not undergone mammography. Poisson regression models estimated relative risk for the impact of self-identified race/ethnicity, socioeconomic characteristics, health status, and use of health care services on screening completion., Results: The distribution of race/ethnicity among unscreened women was 55.5% white, 7.0% Latina, and 3.7% black, but race/ethnicity data were missing for 29%. Of these, no record of race/ethnicity was available for 86.7%, and for 5.1%, the data request was recorded but the women declined to identify their race/ethnicity. Nonwhite ethnicity increased risk of screening failure if black, Latina, "other" (eg, American Indian), or missing race/ethnicity. Population-attributable risks were low for minorities compared with the group for whom race/ethnicity data was missing. A greater number of office visits in any setting was associated with greater likelihood of undergoing mammography. Women with missing race/ethnicity data had fewer visits and were less likely to have an identified primary care physician., Conclusions: Greater improvement in mammography screening rates could be achieved in our population by increasing screening among women with missing race/ethnicity data, rather than by targeting those who are known to be of racial/ethnic minorities. Efforts to address screening disparities have been refocused on inreach and outreach to our "missing women."
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- 2013
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21. Inactivation of the Cdkn2a locus cooperates with HMGA1 to drive T-cell leukemogenesis.
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Di Cello F, Dhara S, Hristov AC, Kowalski J, Elbahloul O, Hillion J, Roy S, Meijerink JP, Winter SS, Larson RS, Huso DL, and Resar L
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- Animals, Disease Models, Animal, Female, Gene Expression, Genetic Loci, Humans, Immunophenotyping, Leukemia, T-Cell metabolism, Male, Mice, Mice, Knockout, Cell Transformation, Neoplastic genetics, Cyclin-Dependent Kinase Inhibitor p16 genetics, Epistasis, Genetic, Gene Silencing, HMGA1a Protein genetics, Leukemia, T-Cell genetics
- Abstract
T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia with high relapse rates compared to B-lineage ALL. We previously showed that HMGA1a transgenic mice develop aggressive T-ALL, indicating that HMGA1 causes leukemic transformation in vivo. HMGA1 is also highly expressed in embryonic stem cells, hematopoietic stem cells and diverse, refractory human cancers. Disruption of the CDKN2A tumor suppressor locus occurs in most cases of T-ALL and is thought to contribute to leukemic transformation. To determine whether loss of function of CDKN2A cooperates with HMGA1 in T-ALL, we crossed HMGA1a transgenics onto a Cdkn2a null background. We discovered that T-ALL is markedly accelerated in HMGA1a transgenic Cdkn2a null mice. In addition, these mice recapitulate salient clinical and pathologic features of human T-ALL. HMGA1 is also highly overexpressed in human T-ALL. These findings suggest that HMGA1 plays a causative role in T-ALL and could represent a rational therapeutic target.
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- 2013
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22. Fluorescent substrates for flow cytometric evaluation of efflux inhibition in ABCB1, ABCC1, and ABCG2 transporters.
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Strouse JJ, Ivnitski-Steele I, Waller A, Young SM, Perez D, Evangelisti AM, Ursu O, Bologa CG, Carter MB, Salas VM, Tegos G, Larson RS, Oprea TI, Edwards BS, and Sklar LA
- Subjects
- ATP Binding Cassette Transporter, Subfamily B, ATP Binding Cassette Transporter, Subfamily B, Member 1 antagonists & inhibitors, ATP Binding Cassette Transporter, Subfamily B, Member 1 genetics, ATP Binding Cassette Transporter, Subfamily B, Member 1 metabolism, ATP Binding Cassette Transporter, Subfamily G, Member 2, ATP-Binding Cassette Transporters genetics, Cell Line, Humans, Multidrug Resistance-Associated Proteins antagonists & inhibitors, Multidrug Resistance-Associated Proteins genetics, Multidrug Resistance-Associated Proteins metabolism, Neoplasm Proteins antagonists & inhibitors, Neoplasm Proteins genetics, Neoplasm Proteins metabolism, Protein Binding, ATP-Binding Cassette Transporters antagonists & inhibitors, ATP-Binding Cassette Transporters metabolism, Flow Cytometry methods, Fluorescent Dyes metabolism
- Abstract
ATP binding cassette (ABC) transmembrane efflux pumps such as P-glycoprotein (ABCB1), multidrug resistance protein 1 (ABCC1), and breast cancer resistance protein (ABCG2) play an important role in anticancer drug resistance. A large number of structurally and functionally diverse compounds act as substrates or modulators of these pumps. In vitro assessment of the affinity of drug candidates for multidrug resistance proteins is central to predict in vivo pharmacokinetics and drug-drug interactions. The objective of this study was to identify and characterize new substrates for these transporters. As part of a collaborative project with Life Technologies, 102 fluorescent probes were investigated in a flow cytometric screen of ABC transporters. The primary screen compared substrate efflux activity in parental cell lines with their corresponding highly expressing resistant counterparts. The fluorescent compound library included a range of excitation/emission profiles and required dual laser excitation as well as multiple fluorescence detection channels. A total of 31 substrates with active efflux in one or more pumps and practical fluorescence response ranges were identified and tested for interaction with eight known inhibitors. This screening approach provides an efficient tool for identification and characterization of new fluorescent substrates for ABCB1, ABCC1, and ABCG2., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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23. Rapid detection of human immunodeficiency virus types 1 and 2 by use of an improved piezoelectric biosensor.
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Bisoffi M, Severns V, Branch DW, Edwards TL, and Larson RS
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- Biosensing Techniques instrumentation, Clinical Laboratory Techniques instrumentation, Humans, Point-of-Care Systems, Sensitivity and Specificity, Virology instrumentation, Biosensing Techniques methods, Clinical Laboratory Techniques methods, HIV Infections diagnosis, HIV-1 isolation & purification, HIV-2 isolation & purification, Virology methods
- Abstract
Disasters can create situations in which blood donations can save lives. However, in emergency situations and when resources are depleted, on-site blood donations require the rapid and accurate detection of blood-borne pathogens, including human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). Techniques such as PCR and antibody capture by an enzyme-linked immunosorbent assay (ELISA) for HIV-1 and HIV-2 are precise but time-consuming and require sophisticated equipment that is not compatible with emergency point-of-care requirements. We describe here a prototype biosensor based on piezoelectric materials functionalized with specific antibodies against HIV-1 and HIV-2. We show the rapid and accurate detection of HIV-1 and HIV-2 in both simple and complex solutions, including human serum, and in the presence of a cross-confounding virus. We report detection limits of 12 50% tissue culture infective doses (TCID50s) for HIV-1 and 87 TCID50s for HIV-2. The accuracy, precision of measurements, and operation of the prototype biosensor compared favorably to those for nucleic acid amplification. We conclude that the biosensor has significant promise as a successful point-of-care diagnostic device for use in emergency field applications requiring rapid and reliable testing for blood-borne pathogens.
- Published
- 2013
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24. ATP Binding Cassette C1 (ABCC1/MRP1)-mediated drug efflux contributes to disease progression in T-lineage acute lymphoblastic leukemia.
- Author
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Winter SS, Ricci J, Luo L, Lovato DM, Khawaja HM, Serna-Gallegos T, Debassige N, and Larson RS
- Abstract
Purpose: In acute lymphoblastic leukemia (ALL), multidrug resistance is often mediated by ATPase Binding Cassette (ABC) proteins, which principally involve ABCB1 (multidrug resistance 1, MDR1 ) and ABCC1 (multidrug resistance protein 1, MRP1 ). However, direct comparisons between the differential effects of ABCB1 and ABCC1 have been difficult, since identical cell lines with differential expression of these transporters have not been developed., Experimental Design: In this study, we developed and compared the biological profiles of Jurkat cell lines that selectively over-expressed ABCB1 and ABCC1. Vincristine (VCR) plays an important role in the treatment of T-lineage ALL (T-ALL), and is often the first drug given to newly-diagnosed patients. Because of its importance in treatment, we provided escalating, sub-lethal doses of VCR to Jurkat cells, and extended our observations to expression profiling of newly diagnosed patients with T-ALL., Results: We found that VCR-resistant cells over-expressed ABCC1 nearly 30-fold. The calcein AM assay confirmed that VCR-resistant cells actively extruded VCR, and that ABCC1-mediated drug resistance conferred a different spectrum of multidrug resistance than other T-ALL induction agents. siRNA experiments that blocked ABCC1 export confirmed that VCR resistance could be reversed in vitro. Analyses of T-lymphoblasts obtained from 92 newly diagnosed T-ALL patients treated on Children's Oncology Group Phase III studies 8704/9404 showed that induction failure could be explained in all but one case by the over-expression of ABCB1 or ABCC1., Conclusions: Taken together, these results suggest that over-expression of ABC transporters plays a contributing role in mediating treatment failure in T-ALL, and underscore the need to employ alternate treatment approaches in patients for whom induction failed or for those with relapsed disease.
- Published
- 2013
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25. Development of antibody-tagged nanoparticles for detection of transplant rejection using biomagnetic sensors.
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Butler KS, Lovato DM, Adolphi NL, Belfon R, Fegan DL, Monson TC, Hathaway HJ, Huber DL, Tessier TE, Bryant HC, Flynn ER, and Larson RS
- Subjects
- Animals, Antibodies immunology, CD3 Complex immunology, Graft Rejection immunology, Humans, Immunohistochemistry, Jurkat Cells, Magnetometry, Male, Mice, Mice, Inbred C57BL, Microscopy, Confocal, Microscopy, Electron, Transmission, Skin pathology, Skin Transplantation, T-Lymphocytes immunology, T-Lymphocytes metabolism, T-Lymphocytes pathology, Antibodies chemistry, Graft Rejection diagnosis, Magnetite Nanoparticles chemistry
- Abstract
Organ transplantation is a life-saving procedure and the preferred method of treatment for a growing number of disease states. The advent of new immunosuppressants and improved care has led to great advances in both patient and graft survival. However, acute T-cell-mediated graft rejection occurs in a significant quantity of recipients and remains a life-threatening condition. Acute rejection is associated with decrease in long-term graft survival, demonstrating a need to carefully monitor transplant patients. Current diagnostic criteria for transplant rejection rely on invasive tissue biopsies or relatively nonspecific clinical features. A noninvasive way is needed to detect, localize, and monitor transplant rejection. Capitalizing on advances in targeted contrast agents and magnetic-based detection technology, we developed anti-CD3 antibody-tagged nanoparticles. T cells were found to bind preferentially to antibody-tagged nanoparticles, as identified through light microscopy, transmission electron microscopy, and confocal microscopy. Using mouse skin graft models, we were also able to demonstrate in vivo vascular delivery of T-cell targeted nanoparticles. We conclude that targeting lymphocytes with magnetic nanoparticles is conducive to developing a novel, noninvasive strategy for identifying transplant rejection.
- Published
- 2013
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26. Designing for diffusion of a biomedical intervention.
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Dearing JW, Smith DK, Larson RS, and Estabrooks CA
- Subjects
- Humans, Primary Prevention, Anti-HIV Agents administration & dosage, Diffusion of Innovation, HIV Infections prevention & control, Social Marketing
- Published
- 2013
- Full Text
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27. Primary care and public health partnerships for implementing pre-exposure prophylaxis.
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Norton WE, Larson RS, and Dearing JW
- Subjects
- Continuity of Patient Care, Humans, Anti-HIV Agents administration & dosage, HIV Infections prevention & control, Primary Health Care, Primary Prevention
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- 2013
- Full Text
- View/download PDF
28. A selective ATP-binding cassette subfamily G member 2 efflux inhibitor revealed via high-throughput flow cytometry.
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Strouse JJ, Ivnitski-Steele I, Khawaja HM, Perez D, Ricci J, Yao T, Weiner WS, Schroeder CE, Simpson DS, Maki BE, Li K, Golden JE, Foutz TD, Waller A, Evangelisti AM, Young SM, Chavez SE, Garcia MJ, Ursu O, Bologa CG, Carter MB, Salas VM, Gouveia K, Tegos GP, Oprea TI, Edwards BS, Aubé J, Larson RS, and Sklar LA
- Subjects
- ATP Binding Cassette Transporter, Subfamily B, ATP Binding Cassette Transporter, Subfamily B, Member 1 antagonists & inhibitors, ATP Binding Cassette Transporter, Subfamily B, Member 1 metabolism, ATP Binding Cassette Transporter, Subfamily G, Member 2, ATP-Binding Cassette Transporters metabolism, Animals, Cell Line, Drug Resistance, Neoplasm, Flow Cytometry, High-Throughput Screening Assays, Humans, Inhibitory Concentration 50, Mice, Mice, SCID, Neoplasm Proteins metabolism, Small Molecule Libraries, Structure-Activity Relationship, Tumor Burden drug effects, Xenograft Model Antitumor Assays, ATP-Binding Cassette Transporters antagonists & inhibitors, Antineoplastic Agents pharmacology, Neoplasm Proteins antagonists & inhibitors, Pyrazoles pharmacology, Pyrimidines pharmacology
- Abstract
Chemotherapeutics tumor resistance is a principal reason for treatment failure, and clinical and experimental data indicate that multidrug transporters such as ATP-binding cassette (ABC) B1 and ABCG2 play a leading role by preventing cytotoxic intracellular drug concentrations. Functional efflux inhibition of existing chemotherapeutics by these pumps continues to present a promising approach for treatment. A contributing factor to the failure of existing inhibitors in clinical applications is limited understanding of specific substrate/inhibitor/pump interactions. We have identified selective efflux inhibitors by profiling multiple ABC transporters against a library of small molecules to find molecular probes to further explore such interactions. In our primary screening protocol using JC-1 as a dual-pump fluorescent reporter substrate, we identified a piperazine-substituted pyrazolo[1,5-a]pyrimidine substructure with promise for selective efflux inhibition. As a result of a focused structure-activity relationship (SAR)-driven chemistry effort, we describe compound 1 (CID44640177), an efflux inhibitor with selectivity toward ABCG2 over ABCB1. Compound 1 is also shown to potentiate the activity of mitoxantrone in vitro as well as preliminarily in vivo in an ABCG2-overexpressing tumor model. At least two analogues significantly reduce tumor size in combination with the chemotherapeutic topotecan. To our knowledge, low nanomolar chemoreversal activity coupled with direct evidence of efflux inhibition for ABCG2 is unprecedented.
- Published
- 2013
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29. Imaging of Her2-targeted magnetic nanoparticles for breast cancer detection: comparison of SQUID-detected magnetic relaxometry and MRI.
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Adolphi NL, Butler KS, Lovato DM, Tessier TE, Trujillo JE, Hathaway HJ, Fegan DL, Monson TC, Stevens TE, Huber DL, Ramu J, Milne ML, Altobelli SA, Bryant HC, Larson RS, and Flynn ER
- Subjects
- Animals, Antibodies, Monoclonal immunology, Antibodies, Monoclonal metabolism, Breast Neoplasms metabolism, Female, Humans, Mice, Quantum Theory, Receptor, ErbB-2 metabolism, Tumor Cells, Cultured, Breast Neoplasms diagnosis, Ferric Compounds, Magnetic Resonance Imaging, Magnetite Nanoparticles, Molecular Imaging, Receptor, ErbB-2 immunology, Refractometry instrumentation
- Abstract
Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by superconducting quantum interference device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 (breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125 000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T(2)-weighted MRI yielded a detection limit of 15 600 cells in a 150 µl volume, with r(1) = 1.1 mm(-1) s(-1) and r(2) = 166 mm(-1) s(-1). Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies., (Copyright © 2012 John Wiley & Sons, Ltd.)
- Published
- 2012
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30. Advances in nuclear magnetic resonance for drug discovery.
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Sillerud LO and Larson RS
- Subjects
- High-Throughput Screening Assays methods, Models, Molecular, Molecular Structure, Drug Discovery methods, Magnetic Resonance Spectroscopy methods
- Abstract
Nuclear Magnetic Resonance (NMR) techniques are widely used in the drug discovery process. The primary feature exploited in these investigations is the large difference in mass between drugs and receptors (usually proteins) and the effect this has on the rotational or translational correlation times for drugs bound to their targets. Many NMR parameters, such as the diffusion coefficient, spin diffusion, nuclear Overhauser enhancement, and transverse and longitudinal relaxation times, are strong functions of either the overall tumbling or translation of molecules in solution. This has led to the development of a wide variety of NMR techniques applicable to the elucidation of protein and nucleic acid structure in solution, the screening of drug candidates for binding to a target of choice, and the study of the conformational changes which occur in a target upon drug binding. High-throughput screening by NMR methods has recently received a boost from the introduction of sophisticated computational techniques for reducing the time needed for the acquisition of the primary NMR data for multidimensional studies.
- Published
- 2012
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31. Drug Repurposing from an Academic Perspective.
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Oprea TI, Bauman JE, Bologa CG, Buranda T, Chigaev A, Edwards BS, Jarvik JW, Gresham HD, Haynes MK, Hjelle B, Hromas R, Hudson L, Mackenzie DA, Muller CY, Reed JC, Simons PC, Smagley Y, Strouse J, Surviladze Z, Thompson T, Ursu O, Waller A, Wandinger-Ness A, Winter SS, Wu Y, Young SM, Larson RS, Willman C, and Sklar LA
- Abstract
Academia and small business research units are poised to play an increasing role in drug discovery, with drug repurposing as one of the major areas of activity. Here we summarize project status for a number of drugs or classes of drugs: raltegravir, cyclobenzaprine, benzbromarone, mometasone furoate, astemizole, R-naproxen, ketorolac, tolfenamic acid, phenothiazines, methylergonovine maleate and beta-adrenergic receptor drugs, respectively. Based on this multi-year, multi-project experience we discuss strengths and weaknesses of academic-based drug repurposing research. Translational, target and disease foci are strategic advantages fostered by close proximity and frequent interactions between basic and clinical scientists, which often result in discovering new modes of action for approved drugs. On the other hand, lack of integration with pharmaceutical sciences and toxicology, lack of appropriate intellectual coverage and issues related to dosing and safety may lead to significant drawbacks. The development of a more streamlined regulatory process world-wide, and the development of pre-competitive knowledge transfer systems such as a global healthcare database focused on regulatory and scientific information for drugs world-wide, are among the ideas proposed to improve the process of academic drug discovery and repurposing, and to overcome the "valley of death" by bridging basic to clinical sciences.
- Published
- 2011
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32. Detection of breast cancer cells using targeted magnetic nanoparticles and ultra-sensitive magnetic field sensors.
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Hathaway HJ, Butler KS, Adolphi NL, Lovato DM, Belfon R, Fegan D, Monson TC, Trujillo JE, Tessier TE, Bryant HC, Huber DL, Larson RS, and Flynn ER
- Subjects
- Animals, Breast Neoplasms metabolism, Cell Line, Tumor, Cell Membrane immunology, Cell Membrane metabolism, Female, Ferric Compounds, Humans, Immunoconjugates, Mice, Mice, Nude, Phantoms, Imaging, Receptor, ErbB-2 immunology, Receptor, ErbB-2 metabolism, Sensitivity and Specificity, Xenograft Model Antitumor Assays, Breast Neoplasms diagnosis, Magnetic Resonance Spectroscopy methods, Magnetite Nanoparticles
- Abstract
Introduction: Breast cancer detection using mammography has improved clinical outcomes for many women, because mammography can detect very small (5 mm) tumors early in the course of the disease. However, mammography fails to detect 10 - 25% of tumors, and the results do not distinguish benign and malignant tumors. Reducing the false positive rate, even by a modest 10%, while improving the sensitivity, will lead to improved screening, and is a desirable and attainable goal. The emerging application of magnetic relaxometry, in particular using superconducting quantum interference device (SQUID) sensors, is fast and potentially more specific than mammography because it is designed to detect tumor-targeted iron oxide magnetic nanoparticles. Furthermore, magnetic relaxometry is theoretically more specific than MRI detection, because only target-bound nanoparticles are detected. Our group is developing antibody-conjugated magnetic nanoparticles targeted to breast cancer cells that can be detected using magnetic relaxometry., Methods: To accomplish this, we identified a series of breast cancer cell lines expressing varying levels of the plasma membrane-expressed human epidermal growth factor-like receptor 2 (Her2) by flow cytometry. Anti-Her2 antibody was then conjugated to superparamagnetic iron oxide nanoparticles using the carbodiimide method. Labeled nanoparticles were incubated with breast cancer cell lines and visualized by confocal microscopy, Prussian blue histochemistry, and magnetic relaxometry., Results: We demonstrated a time- and antigen concentration-dependent increase in the number of antibody-conjugated nanoparticles bound to cells. Next, anti Her2-conjugated nanoparticles injected into highly Her2-expressing tumor xenograft explants yielded a significantly higher SQUID relaxometry signal relative to unconjugated nanoparticles. Finally, labeled cells introduced into breast phantoms were measured by magnetic relaxometry, and as few as 1 million labeled cells were detected at a distance of 4.5 cm using our early prototype system., Conclusions: These results suggest that the antibody-conjugated magnetic nanoparticles are promising reagents to apply to in vivo breast tumor cell detection, and that SQUID-detected magnetic relaxometry is a viable, rapid, and highly sensitive method for in vitro nanoparticle development and eventual in vivo tumor detection.
- Published
- 2011
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33. Real-time analysis of the inside-out regulation of lymphocyte function-associated antigen-1 revealed similarities to and differences from very late antigen-4.
- Author
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Chigaev A, Smagley Y, Zhang Y, Waller A, Haynes MK, Amit O, Wang W, Larson RS, and Sklar LA
- Subjects
- Fluorescent Dyes chemistry, Humans, Integrin alpha4beta1 agonists, Protein Binding, U937 Cells, GTP-Binding Protein alpha Subunits, Gi-Go metabolism, Integrin alpha4beta1 metabolism, Leukocyte Rolling physiology, Lymphocyte Function-Associated Antigen-1 metabolism, Receptors, G-Protein-Coupled metabolism
- Abstract
Ten years ago, we introduced a fluorescent probe that shed light on the inside-out regulation of one of the major leukocyte integrins, very late antigen-4 (VLA-4, CD49d/CD29). Here we describe the regulation of another leukocyte integrin, lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18) using a novel small fluorescent probe in real time on live cells. We found that multiple signaling mechanisms regulate LFA-1 conformation in a manner analogous to VLA-4. LFA-1 can be rapidly activated by Gα(i)-coupled G protein-coupled receptors (GPCRs) and deactivated by Gα(s)-coupled GPCRs. The effects of Gα(s)-coupled GPCR agonists can be reversed in real time by receptor-specific antagonists. The specificity of the fluorescent probe binding has been assessed in a competition assay using the natural LFA-1 ligand ICAM-1 and the LFA-1-specific α I allosteric antagonist BIRT0377. Similar to VLA-4 integrin, modulation of the ligand dissociation rate can be observed for different LFA-1 affinity states. However, we also found a striking difference in the binding of the small fluorescent ligand. In the absence of inside-out activation ligand, binding to LFA-1 is extremely slow, at least 10 times slower than expected for diffusion-limited binding. This implies that an additional structural mechanism prevents ligand binding to inactive LFA-1. We propose that such a mechanism explains the inability of LFA-1 to support cell rolling, where the absence of its rapid engagement by a counterstructure in the inactive state leads to a requirement for a selectin-mediated rolling step.
- Published
- 2011
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- View/download PDF
34. Small molecule inhibitors of hantavirus infection.
- Author
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Hall PR, Leitão A, Ye C, Kilpatrick K, Hjelle B, Oprea TI, and Larson RS
- Subjects
- Dose-Response Relationship, Drug, Orthohantavirus drug effects, Humans, Integrin beta3, Peptides, Cyclic pharmacology, Structure-Activity Relationship, Hantavirus Infections prevention & control, Integrin alphaVbeta3 antagonists & inhibitors, Peptides, Cyclic chemistry
- Abstract
Hantaviruses use α(v)β(3) integrins on the surface of human host cells as a gateway to invasion, hence compounds that target this receptor may be used as antiviral agents. To accomplish this aim, new peptidomimetic compounds were selected based on similarity to a cyclic peptide known to bind the α(v)β(3) receptor. This first round of biological screening identified peptidomimetic molecules which were effective hantavirus inhibitors in the low micromolar range, two thousand times more potent than the original cyclic peptide. Pharmacophore models were built to broaden the structural diversity of the second set of compounds screened. Structure-activity relationships (SAR) were drawn from the entire dataset. Further characterization by dose-response studies revealed that three compounds had potency in the nanomolar range. Selectivity assays with a panel of hantaviruses supported the mechanism of inhibition by targeting the α(v)β(3) receptor, through the β(3) integrin., (Copyright © 2010. Published by Elsevier Ltd.)
- Published
- 2010
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- View/download PDF
35. Characterization of single-core magnetite nanoparticles for magnetic imaging by SQUID relaxometry.
- Author
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Adolphi NL, Huber DL, Bryant HC, Monson TC, Fegan DL, Lim J, Trujillo JE, Tessier TE, Lovato DM, Butler KS, Provencio PP, Hathaway HJ, Majetich SA, Larson RS, and Flynn ER
- Subjects
- Antibodies chemistry, Antibodies metabolism, Humans, Jurkat Cells, Microscopy, Electron, Transmission, Nanoconjugates chemistry, Particle Size, Electric Conductivity, Magnetics, Magnetite Nanoparticles chemistry, Molecular Imaging methods
- Abstract
Optimizing the sensitivity of SQUID (superconducting quantum interference device) relaxometry for detecting cell-targeted magnetic nanoparticles for in vivo diagnostics requires nanoparticles with a narrow particle size distribution to ensure that the Néel relaxation times fall within the measurement timescale (50 ms-2 s, in this work). To determine the optimum particle size, single-core magnetite nanoparticles (with nominal average diameters 20, 25, 30 and 35 nm) were characterized by SQUID relaxometry, transmission electron microscopy, SQUID susceptometry, dynamic light scattering and zeta potential analysis. The SQUID relaxometry signal (detected magnetic moment/kg) from both the 25 nm and 30 nm particles was an improvement over previously studied multi-core particles. However, the detected moments were an order of magnitude lower than predicted based on a simple model that takes into account the measured size distributions (but neglects dipolar interactions and polydispersity of the anisotropy energy density), indicating that improved control of several different nanoparticle properties (size, shape and coating thickness) will be required to achieve the highest detection sensitivity. Antibody conjugation and cell incubation experiments show that single-core particles enable a higher detected moment per cell, but also demonstrate the need for improved surface treatments to mitigate aggregation and improve specificity.
- Published
- 2010
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36. Assessment of barriers to changing practice as CME outcomes.
- Author
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Price DW, Miller EK, Rahm AK, Brace NE, and Larson RS
- Subjects
- Family Practice organization & administration, Gynecology organization & administration, Humans, Internal Medicine organization & administration, Obstetrics organization & administration, Pediatrics organization & administration, Qualitative Research, Attitude of Health Personnel, Education, Medical, Continuing, Practice Patterns, Physicians'
- Abstract
Introduction: Continuing medical education (CME) is meant to drive and support improvements in practice. To achieve this goal, CME activities must move beyond simply purveying knowledge, instead helping attendees to contextualize information and to develop strategies for implementing new learning. CME attendees face different barriers to implementing learning, depending on both personal and practice specific contexts. We sought to develop a framework, applicable across multiple CME activities, for categorizing barriers that learners anticipated encountering after CME activities., Methods: Building on previous work, qualitative research methods were used to develop an enhanced framework classifying attendee-perceived barriers to implementing CME learnings in practice. Three thousand one hundred thirty (3130) narrative responses on attendee-perceived barriers to implementing learnings were collected from 75 Kaiser Permanente Colorado live CME activities for family medicine, internal medicine, pediatric, and OB/GYN clinicians in 2008 and 2009., Results: Our CME Learning Transfer Barrier Framework contains 27 discrete barriers in 12 barrier categories (including "none"). The barrier framework was applicable across two years of live CME activities for different clinician target audiences., Discussion: Assessing, characterizing, and summarizing barriers to implementing learning during CME activities can provide valuable information to inform subsequent CME interventions, and provide feedback to organizational leaders to inform performance improvement efforts. The framework may be applicable to other CME formats and to CME activities for audiences in different practice settings.
- Published
- 2010
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37. Recognition of decay accelerating factor and alpha(v)beta(3) by inactivated hantaviruses: Toward the development of high-throughput screening flow cytometry assays.
- Author
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Buranda T, Wu Y, Perez D, Jett SD, BonduHawkins V, Ye C, Edwards B, Hall P, Larson RS, Lopez GP, Sklar LA, and Hjelle B
- Subjects
- Animals, Calibration, Cell Line, Chlorocebus aethiops, Hantavirus Pulmonary Syndrome metabolism, Humans, Protein Binding, Sin Nombre virus chemistry, Sin Nombre virus ultrastructure, Ultraviolet Rays, Vero Cells, Virion chemistry, Virion ultrastructure, CD55 Antigens metabolism, Flow Cytometry methods, High-Throughput Screening Assays methods, Integrin alphaVbeta3 metabolism, Sin Nombre virus metabolism, Virion metabolism
- Abstract
Hantaviruses cause two severe diseases in humans: hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). The lack of vaccines or specific drugs to prevent or treat HFRS and HCPS and the requirement for conducting experiments in a biosafety level 3 laboratory (BSL-3) limit the ability to probe the mechanism of infection and disease pathogenesis. In this study, we developed a generalizable spectroscopic assay to quantify saturable fluorophore sites solubilized in envelope membranes of Sin Nombre virus (SNV) particles. We then used flow cytometry and live cell confocal fluorescence microscopy imaging to show that ultraviolet (UV)-killed SNV particles bind to the cognate receptors of live virions, namely, decay accelerating factor (DAF/CD55) expressed on Tanoue B cells and alpha(v)beta(3) integrins expressed on Vero E6 cells. SNV binding to DAF is multivalent and of high affinity (K(d) approximately 26pM). Self-exchange competition binding assays between fluorescently labeled SNV and unlabeled SNV are used to evaluate an infectious unit-to-particle ratio of approximately 1:14,000. We configured the assay for measuring the binding of fluorescently labeled SNV to Tanoue B suspension cells using a high-throughput flow cytometer. In this way, we established a proof-of-principle high-throughput screening (HTS) assay for binding inhibition. This is a first step toward developing HTS format assays for small molecule inhibitors of viral-cell interactions as well as dissecting the mechanism of infection in a BSL-2 environment., (2010 Elsevier Inc. All rights reserved.)
- Published
- 2010
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38. Inactivation of LEF1 in T-cell acute lymphoblastic leukemia.
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Gutierrez A, Sanda T, Ma W, Zhang J, Grebliunaite R, Dahlberg S, Neuberg D, Protopopov A, Winter SS, Larson RS, Borowitz MJ, Silverman LB, Chin L, Hunger SP, Jamieson C, Sallan SE, and Look AT
- Subjects
- Alleles, Antigens, CD biosynthesis, Antigens, CD genetics, Child, Child, Preschool, Clinical Trials as Topic, Female, Gene Expression Regulation, Leukemic genetics, Genome-Wide Association Study, Humans, Lymphoid Enhancer-Binding Factor 1 biosynthesis, Male, Multigene Family, Neoplasm Proteins biosynthesis, Oligonucleotide Array Sequence Analysis methods, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma drug therapy, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma metabolism, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma pathology, Codon, Terminator, Lymphoid Enhancer-Binding Factor 1 genetics, Neoplasm Proteins genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics, Sequence Deletion
- Abstract
To further unravel the molecular pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL), we performed high-resolution array comparative genomic hybridization on diagnostic specimens from 47 children with T-ALL and identified monoallelic or biallelic LEF1 microdeletions in 11% (5 of 47) of these primary samples. An additional 7% (3 of 44) of the cases harbored nonsynonymous sequence alterations of LEF1, 2 of which produced premature stop codons. Gene expression microarrays showed increased expression of MYC and MYC targets in cases with LEF1 inactivation, as well as differentiation arrest at an early cortical stage of thymocyte development characterized by expression of CD1B, CD1E, and CD8, with absent CD34 expression. LEF1 inactivation was associated with a younger age at the time of T-ALL diagnosis, as well as activating NOTCH1 mutations, biallelic INK4a/ARF deletions, and PTEN loss-of-function mutations or activating mutations of PI3K or AKT genes. These cases generally lacked overexpression of the TAL1, HOX11, HOX11L2, or the HOXA cluster genes, which have been used to define separate molecular pathways leading to T-ALL. Our findings suggest that LEF1 inactivation is an important step in the molecular pathogenesis of T-ALL in a subset of young children.
- Published
- 2010
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39. Interconnecting molecular pathways in the pathogenesis and drug sensitivity of T-cell acute lymphoblastic leukemia.
- Author
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Sanda T, Li X, Gutierrez A, Ahn Y, Neuberg DS, O'Neil J, Strack PR, Winter CG, Winter SS, Larson RS, von Boehmer H, and Look AT
- Subjects
- Amyloid Precursor Protein Secretases antagonists & inhibitors, Animals, Cell Cycle, Cell Line, Tumor, Cell Proliferation, Cell Survival, Cell Transformation, Neoplastic genetics, Down-Regulation, Enzyme Inhibitors pharmacology, Gene Expression Profiling, Genes, myc, Humans, In Vitro Techniques, Leukemia, Experimental drug therapy, Leukemia, Experimental etiology, Leukemia, Experimental genetics, Leukemia, Experimental metabolism, Mice, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma drug therapy, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma etiology, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma metabolism, Receptor, Notch1 genetics, Signal Transduction, Species Specificity, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics
- Abstract
To identify dysregulated pathways in distinct phases of NOTCH1-mediated T-cell leukemogenesis, as well as small-molecule inhibitors that could synergize with or substitute for gamma-secretase inhibitors (GSIs) in T-cell acute lymphoblastic leukemia (T-ALL) therapy, we compared gene expression profiles in a Notch1-induced mouse model of T-ALL with those in human T-ALL. The overall patterns of NOTCH1-mediated gene expression in human and mouse T-ALLs were remarkably similar, as defined early in transformation in the mouse by the regulation of MYC and its target genes and activation of nuclear factor-kappaB and PI3K/AKT pathways. Later events in murine Notch1-mediated leukemogenesis included down-regulation of genes encoding tumor suppressors and negative cell cycle regulators. Gene set enrichment analysis and connectivity map algorithm predicted that small-molecule inhibitors, including heat-shock protein 90, histone deacetylase, PI3K/AKT, and proteasome inhibitors, could reverse the gene expression changes induced by NOTCH1. When tested in vitro, histone deacetylase, PI3K and proteasome inhibitors synergized with GSI in suppressing T-ALL cell growth in GSI-sensitive cells. Interestingly, alvespimycin, a potent inhibitor of the heat-shock protein 90 molecular chaperone, markedly inhibited the growth of both GSI-sensitive and -resistant T-ALL cells, suggesting that its loss disrupts signal transduction pathways crucial for the growth and survival of T-ALL cells.
- Published
- 2010
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40. Enhanced leukemia cell detection using a novel magnetic needle and nanoparticles.
- Author
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Jaetao JE, Butler KS, Adolphi NL, Lovato DM, Bryant HC, Rabinowitz I, Winter SS, Tessier TE, Hathaway HJ, Bergemann C, Flynn ER, and Larson RS
- Subjects
- Ferric Compounds chemistry, Humans, Sensitivity and Specificity, Tumor Cells, Cultured, Antigens, CD34 analysis, Bone Marrow Cells pathology, Leukemia diagnosis, Magnetics, Metal Nanoparticles, Neoplasm, Residual diagnosis
- Abstract
Acute leukemia is a hematopoietic malignancy for which the accurate measurement of minimal residual disease is critical to determining prognosis and treatment. Although bone marrow aspiration and light microscopy remain the current standard of care for detecting residual disease, these approaches cannot reliably discriminate less than 5% lymphoblast cells. To improve the detection of leukemia cells in the marrow, we developed a novel apparatus that utilizes antibodies conjugated to superparamagnetic iron oxide nanoparticles (SPION) and directed against the acute leukemia antigen CD34, coupled with a "magnetic needle" biopsy. Leukemia cell lines expressing high or minimal CD34 were incubated with anti-CD34-conjugated SPIONs. Three separate approaches including microscopy, superconducting quantum interference device magnetometry, and in vitro magnetic needle extraction were then used to assess cell sampling. We found that CD34-conjugated nanoparticles preferentially bind high CD34-expressing cell lines. Furthermore, the magnetic needle enabled identification of both cell line and patient leukemia cells diluted into normal blood at concentrations below those normally found in remission marrow samples. Finally, the magnetic needle enhanced the percentage of lymphoblasts detectable by light microscopy by 10-fold in samples of fresh bone marrow aspirate approximating minimal residual disease. These data suggest that bone marrow biopsy using antigen-targeted magnetic nanoparticles and a magnetic needle for the evaluation of minimal residual disease in CD34-positive acute leukemias can significantly enhance sensitivity compared with the current standard of care.
- Published
- 2009
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41. Phage display selection of cyclic peptides that inhibit Andes virus infection.
- Author
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Hall PR, Hjelle B, Njus H, Ye C, Bondu-Hawkins V, Brown DC, Kilpatrick KA, and Larson RS
- Subjects
- Amino Acid Sequence, Animals, Antiviral Agents chemical synthesis, Chlorocebus aethiops, Humans, Microbial Sensitivity Tests, Models, Molecular, Molecular Sequence Data, Peptide Library, Peptides, Cyclic chemical synthesis, Peptides, Cyclic genetics, Vero Cells, Antiviral Agents isolation & purification, Antiviral Agents pharmacology, Orthohantavirus drug effects, Peptides, Cyclic isolation & purification, Peptides, Cyclic pharmacology
- Abstract
Specific therapy is not available for hantavirus cardiopulmonary syndrome caused by Andes virus (ANDV). Peptides capable of blocking ANDV infection in vitro were identified using antibodies against ANDV surface glycoproteins Gn and Gc to competitively elute a cyclic nonapeptide-bearing phage display library from purified ANDV particles. Phage was examined for ANDV infection inhibition in vitro, and nonapeptides were synthesized based on the most-potent phage sequences. Three peptides showed levels of viral inhibition which were significantly increased by combination treatment with anti-Gn- and anti-Gc-targeting peptides. These peptides will be valuable tools for further development of both peptide and nonpeptide therapeutic agents.
- Published
- 2009
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42. Characterization of magnetite nanoparticles for SQUID-relaxometry and magnetic needle biopsy.
- Author
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Adolphi NL, Huber DL, Jaetao JE, Bryant HC, Lovato DM, Fegan DL, Venturini EL, Monson TC, Tessier TE, Hathaway HJ, Bergemann C, Larson RS, and Flynn ER
- Abstract
Magnetite nanoparticles (Chemicell SiMAG-TCL) were characterized by SQUID-relaxometry, susceptometry, and TEM. The magnetization detected by SQUID-relaxometry was 0.33% of that detected by susceptometry, indicating that the sensitivity of SQUID-relaxometry could be significantly increased through improved control of nanoparticle size. The relaxometry data were analyzed by the moment superposition model (MSM) to determine the distribution of nanoparticle moments. Analysis of the binding of CD34-conjugated nanoparticles to U937 leukemia cells revealed 60,000 nanoparticles per cell, which were collected from whole blood using a prototype magnetic biopsy needle, with a capture efficiency of >65% from a 750 µl sample volume in 1 minute.
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- 2009
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43. Speaking the right language: the scientific method as a framework for a continuous quality improvement program within academic medical research compliance units.
- Author
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Nolte KB, Stewart DM, O'Hair KC, Gannon WL, Briggs MS, Barron AM, Pointer J, and Larson RS
- Subjects
- Cooperative Behavior, Female, Humans, Interprofessional Relations, Language, Male, New Mexico, Organizational Innovation, Program Development, Program Evaluation, Academic Medical Centers organization & administration, Biomedical Research organization & administration, Communication, Total Quality Management
- Abstract
The authors developed a novel continuous quality improvement (CQI) process for academic biomedical research compliance administration. A challenge in developing a quality improvement program in a nonbusiness environment is that the terminology and processes are often foreign. Rather than training staff in an existing quality improvement process, the authors opted to develop a novel process based on the scientific method--a paradigm familiar to all team members. The CQI process included our research compliance units. Unit leaders identified problems in compliance administration where a resolution would have a positive impact and which could be resolved or improved with current resources. They then generated testable hypotheses about a change to standard practice expected to improve the problem, and they developed methods and metrics to assess the impact of the change. The CQI process was managed in a "peer review" environment. The program included processes to reduce the incidence of infections in animal colonies, decrease research protocol-approval times, improve compliance and protection of animal and human research subjects, and improve research protocol quality. This novel CQI approach is well suited to the needs and the unique processes of research compliance administration. Using the scientific method as the improvement paradigm fostered acceptance of the project by unit leaders and facilitated the development of specific improvement projects. These quality initiatives will allow us to improve support for investigators while ensuring that compliance standards continue to be met. We believe that our CQI process can readily be used in other academically based offices of research.
- Published
- 2008
- Full Text
- View/download PDF
44. Multivalent presentation of antihantavirus peptides on nanoparticles enhances infection blockade.
- Author
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Hall PR, Hjelle B, Brown DC, Ye C, Bondu-Hawkins V, Kilpatrick KA, and Larson RS
- Subjects
- Amino Acid Sequence, Animals, Chlorocebus aethiops, Humans, Models, Molecular, Peptide Library, Sin Nombre virus metabolism, Sin Nombre virus pathogenicity, Sin Nombre virus physiology, Vero Cells, Antiviral Agents chemical synthesis, Antiviral Agents chemistry, Antiviral Agents metabolism, Antiviral Agents pharmacology, Nanoparticles chemistry, Peptides, Cyclic chemical synthesis, Peptides, Cyclic chemistry, Peptides, Cyclic metabolism, Peptides, Cyclic pharmacology, Sin Nombre virus drug effects
- Abstract
Viral entry into susceptible host cells typically results from multivalent interactions between viral surface proteins and host entry receptors. In the case of Sin Nombre virus (SNV), a New World hantavirus that causes hantavirus cardiopulmonary syndrome, infection involves the interaction between viral membrane surface glycoproteins and the human integrin alpha(v)beta(3). Currently, there are no therapeutic agents available which specifically target SNV. To address this problem, we used phage display selection of cyclic nonapeptides to identify peptides that bound SNV and specifically prevented SNV infection in vitro. We synthesized cyclic nonapeptides based on peptide sequences of phage demonstrating the strongest inhibition of infection, and in all cases, the isolated peptides were less effective at blocking infection (9.0% to 27.6% inhibition) than were the same peptides presented by phage (74.0% to 82.6% inhibition). Since peptides presented by the phage were pentavalent, we determined whether the identified peptides would show greater inhibition if presented in a multivalent format. We used carboxyl linkages to conjugate selected cyclic peptides to multivalent nanoparticles and tested infection inhibition. Two of the peptides, CLVRNLAWC and CQATTARNC, showed inhibition that was improved over that of the free format when presented on nanoparticles at a 4:1 nanoparticle-to-virus ratio (9.0% to 32.5% and 27.6% to 37.6%, respectively), with CQATTARNC inhibition surpassing 50% when nanoparticles were used at a 20:1 ratio versus virus. These data illustrate that multivalent inhibitors may disrupt polyvalent protein-protein interactions, such as those utilized for viral infection of host cells, and may represent a useful therapeutic approach.
- Published
- 2008
- Full Text
- View/download PDF
45. Detection of viral bioagents using a shear horizontal surface acoustic wave biosensor.
- Author
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Bisoffi M, Hjelle B, Brown DC, Branch DW, Edwards TL, Brozik SM, Bondu-Hawkins VS, and Larson RS
- Subjects
- Acoustics, Sensitivity and Specificity, Biosensing Techniques instrumentation, Biosensing Techniques methods, Enterovirus B, Human isolation & purification, Sin Nombre virus isolation & purification
- Abstract
Viruses are of high medical and biodefense concern and their detection at concentrations well below the threshold necessary to cause health hazards continues to be a challenge with respect to sensitivity, specificity, and selectivity. Ideally, assays for accurate and real time detection of viral agents would not necessitate any pre-processing of the analyte, which would make them applicable for example to bodily fluids (blood, sputum) and man-made as well as naturally occurring bodies of water (pools, rivers). We describe herein a robust biosensor that combines the sensitivity of surface acoustic waves (SAW) generated at a frequency of 325MHz with the specificity provided by antibodies for the detection of viral agents. A lithium tantalate-based SAW transducer with silicon dioxide waveguide sensor platform featuring three test and one reference delay lines was used to adsorb antibodies directed against either Coxsackie virus B4 or the category A bioagent Sin Nombre virus (SNV), a member of the genus Hantavirus, family Bunyaviridae, negative-stranded RNA viruses. Rapid detection (within seconds) of increasing concentrations of viral particles was linear over a range of order of magnitude for both viruses, although the sensor was approximately 5 x 10(5)-fold more sensitive for the detection of SNV. For both pathogens, the sensor's selectivity for its target was not compromised by the presence of confounding Herpes Simplex virus type 1. The biosensor was able to detect SNV at doses lower than the load of virus typically found in a human patient suffering from hantavirus cardiopulmonary syndrome (HCPS). Further, in a proof-of-principle real world application, the SAW biosensor was capable to selectively detect SNV agents in complex solutions, such as naturally occurring bodies of water (river, sewage effluent) without analyte pre-processing. This is the first study that reports on the detection of viral agents using an antibody-based SAW biosensor that has the potential to be used as a hand-held and self-contained device for rapid viral detection in the field.
- Published
- 2008
- Full Text
- View/download PDF
46. High-throughput flow cytometry to detect selective inhibitors of ABCB1, ABCC1, and ABCG2 transporters.
- Author
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Ivnitski-Steele I, Larson RS, Lovato DM, Khawaja HM, Winter SS, Oprea TI, Sklar LA, and Edwards BS
- Subjects
- ATP Binding Cassette Transporter, Subfamily B, ATP Binding Cassette Transporter, Subfamily G, Member 2, Benzimidazoles, Carbocyanines, Cell Line, Cell Survival drug effects, Dose-Response Relationship, Drug, Drug Resistance, Drug Screening Assays, Antitumor, Electrophysiology, Fluorescent Dyes, Humans, Oligonucleotide Array Sequence Analysis, ATP Binding Cassette Transporter, Subfamily B, Member 1 antagonists & inhibitors, ATP-Binding Cassette Transporters antagonists & inhibitors, Drug Evaluation, Preclinical methods, Flow Cytometry methods, Multidrug Resistance-Associated Proteins antagonists & inhibitors, Neoplasm Proteins antagonists & inhibitors
- Abstract
Up-regulation of pump (transporter) expression and selection of resistant cancer cells result in cancer multidrug resistance to diverse substrates of these transporters. While more than 48 members of the ATP binding cassette (ABC) transporter superfamily have been identified, up to now only three human ABC transporters-ABCB1, ABCC1, and ABCG2-have unambiguously been shown to contribute to cancer multidrug resistance. The use of low-toxicity and high-specificity agents as a targeted transporter inhibition strategy is necessary to effectively overcome multiple drug resistance. An objective of the present studies was to develop and validate HyperCyt (IntelliCyt, Albuquerque, NM) flow cytometry high-throughput screeening assays to assess the specificity of test compounds that inhibited transporters as an integral part of the screen. Two separate duplex assays were constructed: one in which ABCB1 and ABCG2 transporters were evaluated in parallel using fluorescent J-aggregate-forming lipophilic cation 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide as substrate, and the other in which ABCB1 and ABCC1 transporters were evaluated in parallel using fluorescent calcein acetoxymethyl ester as substrate. ABCB1-expressing cells were color-coded to allow their distinction from cells expressing the alternate transporter. The assays were validated in a screen of the Prestwick Chemical Library (Illkirch, France). Three novel selective inhibitors of the ABCC1 transporter were identified in the screen, and the activity of each was confirmed in follow-up chemosensitivity shift and reversal studies. This high-throughput screening assay provides an efficient approach for identifying selective inhibitors of individual ABC transporters, promising as probes of transporter function and therapeutic tools for treating chemotherapy-resistant cancers.
- Published
- 2008
- Full Text
- View/download PDF
47. High-throughput screening for daunorubicin-mediated drug resistance identifies mometasone furoate as a novel ABCB1-reversal agent.
- Author
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Winter SS, Lovato DM, Khawaja HM, Edwards BS, Steele ID, Young SM, Oprea TI, Sklar LA, and Larson RS
- Subjects
- Biological Assay, Carbocyanines metabolism, Drug Resistance, Multiple drug effects, Humans, Inhibitory Concentration 50, Jurkat Cells, Mometasone Furoate, Pregnadienediols chemistry, Up-Regulation drug effects, ATP Binding Cassette Transporter, Subfamily B, Member 1 metabolism, Daunorubicin pharmacology, Drug Resistance, Neoplasm drug effects, Drug Screening Assays, Antitumor methods, Pregnadienediols analysis, Pregnadienediols pharmacology
- Abstract
The overexpression of P-glycoprotein, encoded by the ATP Binding Cassette B1 (ABCB1) gene, contributes to multidrug resistance (MDR) and is considered one of the major obstacles to successful cancer chemotherapy. The authors previously developed a T-lineage acute lymphoblastic leukemia (T-ALL) cell line that overexpresses ABCB1 and exhibits MDR to daunorubicin (DNR), prednisolone, and vincristine. Using this cell line and the fluorescent probe JC-1, they developed a flow cytometry-based, high-throughput screening (HTS) assay that quantifies ABCB1 efflux. They screened a library of 880 off-patent drugs for their ability to inhibit ABCB1 efflux and then measured the ability of 11 lead compounds to reverse in vitro DNR-mediated drug resistance and the toxic doses for each agent. Seven of the 11 drugs were able to reverse drug resistance at a concentration significantly below its toxic dose. Of the remaining 7, only 1 compound, mometasone furoate, has not been previously described as an ABCB1 antagonist to DNR-mediated drug resistance. On the basis of its high ABC modulator activity and relatively large in vitro therapeutic window, this drug warrants further investigation. In addition, the approach used in this study is useful for identifying off-patent drugs that may be repurposed for novel clinical indications.
- Published
- 2008
- Full Text
- View/download PDF
48. Genetic alterations determine chemotherapy resistance in childhood T-ALL: modelling in stage-specific cell lines and correlation with diagnostic patient samples.
- Author
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Estes DA, Lovato DM, Khawaja HM, Winter SS, and Larson RS
- Subjects
- ATP Binding Cassette Transporter, Subfamily B, Member 1 genetics, Argininosuccinate Synthase genetics, Asparaginase therapeutic use, Aspartate-Ammonia Ligase genetics, Child, Daunorubicin therapeutic use, Gene Expression Profiling, Humans, Jurkat Cells, Leukemia-Lymphoma, Adult T-Cell drug therapy, Leukemia-Lymphoma, Adult T-Cell pathology, Oligonucleotide Array Sequence Analysis, Prednisolone therapeutic use, RNA Interference, RNA, Small Interfering administration & dosage, Reverse Transcriptase Polymerase Chain Reaction, Vincristine therapeutic use, Cell Line, Tumor, Drug Resistance, Neoplasm genetics, Gene Expression Regulation, Leukemic, Genes, MDR, Leukemia-Lymphoma, Adult T-Cell genetics
- Abstract
Acquired drug resistance eventually leads to treatment failure in T-cell acute lymphoblastic leukaemia (T-ALL). Immunophenotypic and cytogenetic heterogeneities within T-ALL influence susceptibility to cytotoxic therapy, and little is known about the mechanisms of drug resistance at specific stages of T-cell ontogeny. We developed tolerance to therapeutic concentrations of daunorubicin (DNR) and L-asparaginase (L-asp) in Jurkat (CD1a(-), sCD3(+)) and Sup T1 (CD1a(+), sCD3(-)) cell lines, having respective 'mature' and 'cortical' stages of developmental arrest. DNR resistant cells acquired multidrug resistance: 310-fold increased resistance to vincristine (VCR) and a 120-fold increased resistance to prednisolone (PRED). Microarray analysis identified upregulation of asparagine synthetase (ASNS) and argininosuccinate synthase 1 (ASS1) to cell lines with acquired resistance to L-asp, and in the case of DNR, upregulation of ATP-binding cassette B1 (ABCB1). Suppression of ABCB1, ASNS and ASS1 by RNA interference revealed their functional relevance to acquired drug resistance. Expression profiling of these genes in 80 T-ALL patients showed correlation with treatment response. This study expands the pool of available drug resistant cell lines having cortical and mature stages of developmental arrest, introduces three new drug resistant T-ALL cell lines, and identifies gene interactions leading to L-asp and DNR resistance.
- Published
- 2007
- Full Text
- View/download PDF
49. Identification of genomic classifiers that distinguish induction failure in T-lineage acute lymphoblastic leukemia: a report from the Children's Oncology Group.
- Author
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Winter SS, Jiang Z, Khawaja HM, Griffin T, Devidas M, Asselin BL, and Larson RS
- Subjects
- Adolescent, Adult, Blast Crisis classification, Blast Crisis drug therapy, Blast Crisis mortality, Child, Child, Preschool, Female, Gene Expression Profiling, Humans, Infant, Leukemia-Lymphoma, Adult T-Cell classification, Leukemia-Lymphoma, Adult T-Cell drug therapy, Leukemia-Lymphoma, Adult T-Cell mortality, Male, Oligonucleotide Array Sequence Analysis, Predictive Value of Tests, Remission Induction, Retrospective Studies, Up-Regulation, Blast Crisis genetics, Gene Expression Regulation, Leukemic, Genes, Neoplasm, Genome, Human, Leukemia-Lymphoma, Adult T-Cell genetics
- Abstract
The clinical and cytogenetic features associated with T-cell acute lymphoblastic leukemia (T-ALL) are not predictive of early treatment failure. Based on the hypothesis that microarrays might identify patients who fail therapy, we used the Affymetrix U133 Plus 2.0 chip and prediction analysis of microarrays (PAM) to profile 50 newly diagnosed patients who were treated in the Children's Oncology Group (COG) T-ALL Study 9404. We identified a 116-member genomic classifier that could accurately distinguish all 6 induction failure (IF) cases from 44 patients who achieved remission; network analyses suggest a prominent role for genes mediating cellular quiescence. Seven genes were similarly upregulated in both the genomic classifier for IF patients and T-ALL cell lines having acquired resistance to neoplastic agents, identifying potential target genes for further study in drug resistance. We tested whether our classifier could predict IF within 42 patient samples obtained from COG 8704 and, using PAM to define a smaller classifier for the U133A chip, correctly identified the single IF case and patients with persistently circulating blasts. Genetic profiling may identify T-ALL patients who are likely to fail induction and for whom alternate treatment strategies might be beneficial.
- Published
- 2007
- Full Text
- View/download PDF
50. Magnetic needles and superparamagnetic cells.
- Author
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Bryant HC, Sergatskov DA, Lovato D, Adolphi NL, Larson RS, and Flynn ER
- Subjects
- Computer Simulation, Nanostructures radiation effects, Cell Separation methods, Immunomagnetic Separation methods, Magnetics, Micromanipulation methods, Models, Biological, Nanostructures chemistry, Needles
- Abstract
Superparamagnetic nanoparticles can be attached in great numbers to pathogenic cells using specific antibodies so that the magnetically-labeled cells themselves become superparamagnets. The cells can then be manipulated and drawn out of biological fluids, as in a biopsy, very selectively using a magnetic needle. We examine the origins and uncertainties in the forces exerted on magnetic nanoparticles by static magnetic fields, leading to a model for trajectories and collection times of dilute superparamagnetic cells in biological fluids. We discuss the design and application of such magnetic needles and the theory of collection times. We compare the mathematical model to measurements in a variety of media including blood. For more information on this article, see medicalphysicsweb.org.
- Published
- 2007
- Full Text
- View/download PDF
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