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    Date Issued2020 (2)2019 (1)2011 (1)Author
    Liu, Wei (4)
    Allison, Jeroan J. (2)Barton, Bruce A. (2)Danila, Maria I. (2)Fischer, Melissa A. (2)View MoreUMass Chan AffiliationDepartment of Population and Quantitative Health Sciences (2)Meyers Primary Care Institute (2)UMass Worcester Prevention Research Center (2)Department of Medicine (1)Department of Medicine, Division of Internal Medicine (1)View MoreDocument TypeJournal Article (4)KeywordBiostatistics (2)Health Policy (2)Health Services Administration (2)Health Services Research (2)Investigative Techniques (2)View MoreJournalContemporary clinical trials communications (1)Journal of evaluation in clinical practice (1)Journal of molecular and cellular cardiology (1)Nature communications (1)

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    A deep learning diagnostic platform for diffuse large B-cell lymphoma with high accuracy across multiple hospitals

    Li, Dongguang; Bledsoe, Jacob R.; Zeng, Yu; Liu, Wei; Hu, Yiguo; Bi, Ke; Liang, Aibin; Li, Shaoguang (2020-11-26)
    Diagnostic histopathology is a gold standard for diagnosing hematopoietic malignancies. Pathologic diagnosis requires labor-intensive reading of a large number of tissue slides with high diagnostic accuracy equal or close to 100 percent to guide treatment options, but this requirement is difficult to meet. Although artificial intelligence (AI) helps to reduce the labor of reading pathologic slides, diagnostic accuracy has not reached a clinically usable level. Establishment of an AI model often demands big datasets and an ability to handle large variations in sample preparation and image collection. Here, we establish a highly accurate deep learning platform, consisting of multiple convolutional neural networks, to classify pathologic images by using smaller datasets. We analyze human diffuse large B-cell lymphoma (DLBCL) and non-DLBCL pathologic images from three hospitals separately using AI models, and obtain a diagnostic rate of close to 100 percent (100% for hospital A, 99.71% for hospital B and 100% for hospital C). The technical variability introduced by slide preparation and image collection reduces AI model performance in cross-hospital tests, but the 100% diagnostic accuracy is maintained after its elimination. It is now clinically practical to utilize deep learning models for diagnosis of DLBCL and ultimately other human hematopoietic malignancies.
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    Simulation-based power and sample size calculation for designing interrupted time series analyses of count outcomes in evaluation of health policy interventions

    Liu, Wei; Ye, Shangyuan; Barton, Bruce A.; Fischer, Melissa A.; Lawrence, Colleen; Rahn, Elizabeth J.; Danila, Maria I.; Saag, Kenneth G.; Harris, Paul A.; Lemon, Stephenie C.; et al. (2020-03-01)
    Objective: The purpose of this study was to present the design, model, and data analysis of an interrupted time series (ITS) model applied to evaluate the impact of health policy, systems, or environmental interventions using count outcomes. Simulation methods were used to conduct power and sample size calculations for these studies. Methods: We proposed the models and analyses of ITS designs for count outcomes using the Strengthening Translational Research in Diverse Enrollment (STRIDE) study as an example. The models we used were observation-driven models, which bundle a lagged term on the conditional mean of the outcome for a time series of count outcomes. Results: A simulation-based approach with ready-to-use computer programs was developed to calculate the sample size and power of two types of ITS models, Poisson and negative binomial, for count outcomes. Simulations were conducted to estimate the power of segmented autoregressive (AR) error models when autocorrelation ranged from -0.9 to 0.9, with various effect sizes. The power to detect the same magnitude of parameters varied largely, depending on the testing level change, the trend change, or both. The relationships between power and sample size and the values of the parameters were different between the two models. Conclusion: This article provides a convenient tool to allow investigators to generate sample sizes that will ensure sufficient statistical power when the ITS study design of count outcomes is implemented.
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    Design, analysis, power, and sample size calculation for three-phase interrupted time series analysis in evaluation of health policy interventions

    Zhang, Bo; Liu, Wei; Lemon, Stephenie C.; Barton, Bruce A.; Fischer, Melissa A.; Lawrence, Colleen; Rahn, Elizabeth J.; Danila, Maria I.; Saag, Kenneth G.; Harris, Paul A.; et al. (2019-08-19)
    OBJECTIVE: To discuss the study design and data analysis for three-phase interrupted time series (ITS) studies to evaluate the impact of health policy, systems, or environmental interventions. Simulation methods are used to conduct power and sample size calculation for these studies. METHODS: We consider the design and analysis of three-phase ITS studies using a study funded by National Institutes of Health as an exemplar. The design and analysis of both one-arm and two-arm three-phase ITS studies are introduced. RESULTS: A simulation-based approach, with ready-to-use computer programs, was developed to determine the power for two types of three-phase ITS studies. Simulations were conducted to estimate the power of segmented autoregressive (AR) error models when autocorrelation ranged from -0.9 to 0.9 with various effect sizes. The power increased as the sample size or the effect size increased. The power to detect the same effect sizes varied largely, depending on testing level change, trend changes, or both. CONCLUSION: This article provides a convenient tool for investigators to generate sample sizes to ensure sufficient statistical power when three-phase ITS study design is implemented.
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    Deprivation of MKK7 in cardiomyocytes provokes heart failure in mice when exposed to pressure overload

    Liu, Wei; Zi, Min; Chi, Hongbo; Jin, Jiawei; Prehar, Sukhpal; Neyses, Ludwig; Cartwright, Elizabeth J.; Flavell, Richard A.; Davis, Roger J.; Wang, Xin (2011-04-01)
    There is little doubt that members of mitogen-activated protein kinase (MAPK) families play key roles in the transition from adaptive hypertrophic remodeling to heart failure. Mitogen-activated protein kinase kinase 7 (MKK7) is a critical component of stress-activated MAP kinase signaling pathway. The role of MKK7 plays in mediating cardiac remodeling in response to load stress has yet to be defined. Herein, we investigate the role of MKK7 in regulating cardiac remodeling in response to pressure overload. We generated and examined the phenotype of mice with cardiomyocyte-specific deletion of the mkk7 gene (MKK7(cko)). Following one week of pressure overload, MKK7(cko) mice exhibited characteristic phenotypes of heart failure evidenced by deterioration in ventricular function and pulmonary congestion. Cell death assays revealed an increased prevalence of cardiomyocyte apoptosis in the MKK7(cko) heart, in which elevated p53 levels and attenuated expression of manganese superoxide dismutase (MnSOD) were found. Moreover, extensive interstitial fibrosis was discovered in the knockout heart likely attributable to upregulation of transforming growth factor beta (TGF-beta) signaling. These results reveal an essential role of MKK7 in cardiomyocytes for protecting the heart from hypertrophic insults thereby preventing the transition to heart failure.
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