Browsing by Author "Chen, Hung-Chia"

Now showing 1 - 7 of 7

Association of IL28B gene variations with mathematical modeling of viral kinetics in chronic hepatitis C patients with IFN plus ribavirin therapy
(2011-03-01)
Hsu, Ching-Sheng
;
Hsu, Shih-Jer
;
Chen, Hung-Chia
;
Tseng, Tai-Chung
;
Liu, Chen-Hua
Asian patients with chronic hepatitis C (CHC) are known to have better virological responses to pegylated (Peg) IFN-based therapy than Western patients. Although IL28B gene polymorphisms may contribute to this difference, whether favorable hepatitis C virus (HCV) kinetics during treatment plays a role remains unclear. We enrolled 145 consecutive Taiwanese patients with CHC receiving Peg-IFN alpha-2a plus ribavirin for the study. Blood samples were taken more frequently at defined intervals in the first 3 d. Peg-IFN was administered at week 1. It was then administered weekly in combination with daily ribavirin for 24 or 48 wk. A mathematical model fitted to the observed HCV kinetics was constructed, which could interpret the transient HCV titer elevation after Peg-IFN treatment. The results demonstrated a comparable viral clearance rate (c = 3.45 +/- 3.73) (day(-1), mean +/- SD) but lower daily viral production rate (P = 10(6)-10(12)) in our patients than those reported previously in Western patients. Of 110 patients with a sustained virological response (SVR), 47 (43%) had a transient elevation of viral titer within 12 h (proportion of 12 h/3 d: 44% in non-SVR vs. 70% in SVR; P = 0.029). Among 91 patients with available rs8099917 data, patients with the TT genotype had an early surge of viral titer after therapy and a higher SVR and viral clearance rate than those with the GT genotype. In conclusion, Taiwanese patients with CHC receiving Peg-IFN plus ribavirin therapy have a lower daily viral production rate than Western patients, and the rs8099917 TT genotype may contribute to the increased viral clearance rate and better virological responses in these patients.
Association of IL28B genotypes with metabolic profiles and viral clearance rate in chronic hepatitis C patients
(2013-03-01)
Hsu, Ching-Sheng
;
Hsu, Shih-Jer
;
Chen, Hung-Chia
;
Liu, Chen-Hua
;
Jeng, Jenher
IL28B genotypes have a strong impact on treatment outcomes of chronic hepatitis C (CHC) and on-treatment viral kinetics. Since metabolic regulation and interferon response are highly integrated, metabolic profiles may play an important role in the link between IL28B genotypes and hepatitis C virus (HCV) infection. Thus, the association of IL28B rs8099917 genotypes with metabolic profiles and the impact of metabolic profiles on hepatitis C viral kinetic parameters were examined. A case-control analysis including 278 CHC patients and 280 subjects without chronic HCV infection was performed. The associations of IL28B rs8099917 genotype with pretreatment metabolic profiles and early viral kinetic parameters were evaluated. Compared to HCV genotype 1 patients, the differences in metabolic profiles were more significant in genotype 2 patients. HCV genotype 2 patients with TT genotype had higher serum total cholesterol and high density lipoprotein (HDL) levels than those with GT genotype, and the differences remained significant when adjusted for age, sex, and body mass index (p = 0.005 for total cholesterol; p = 0.006 for HDL). In addition, patients with higher serum TG, higher fasting blood glucose, and lower HDL had a lower viral clearance rate. IL28B genotypes may affect lipid profiles of CHC patients, especially in HCV-genotype 2 patients. Patients with higher serum fasting blood glucose, triglyceride, and lower HDL have a lower viral clearance rate during pegylated interferon plus ribavirin therapy.
Parametric coverage interval
(2007-04-01)
Chen, Lin-An
;
Huang, Jing-Ye
;
Chen, Hung-Chia
;
統計學研究所
;
Institute of Statistics
Parametric estimation of coverage interval is useful since the parametric intervals are generally narrower than the non-parametric ones; however, it has been considered only for the measurement variable with normal distribution. Here we propose a general technique for constructing parametric coverage intervals that may deal with all distributions, both symmetric and asymmetric, in measurement science.
Reply to Guedj et al.: Early transient increase of hepatitis C virus viral load in genotype 1 and 2 infections, and the use of mathematical modeling
(2011-07-19)
Hsu, Ching-Sheng
;
Chen, Hung-Chia
;
Jeng, Jenher
;
Kao, Jia-Horng
;
Chen, Ding-Shinn
Statistical inferences based on outliers for gene expression analysis
(2017-08-01)
Lai, Yi-Hsuan
;
Chen, Hung-Chia
;
Chen, Lin-An
;
Chen, Dung-Tsa
;
Hung, Hui-Nien
Discovering differential genes through the detection of outliers in samples from disease group subjects is a new and important approach for gene expression analysis. Extending the outlier mean of Chen et al. (2010a), we develop the asymptotic distributions of the outlier least squares estimator (LSE) and the outlier proportion for the linear regression model. An optimal property of the best linear outlier mean acting as an outlier estimator version of the Gauss Markov theorem for the outlier LSE is presented. Power comparisons demonstrate that tests based on outlier estimators are competitive in detecting a shift of the parent tail distribution. An analysis of DNA microarray data from samples of pancreatic breast tumors supports the use of outlier-based methods. (C) 2017 Elsevier B.V. All rights reserved.
The density control chart: a general approach for constructing a single chart for simultaneously monitoring multiple parameters
(2012)
Chen, Hung-Chia
;
Yeh, Arthur B.
;
Yen, Chia-Ling
;
Chen, Lin-An
;
統計學研究所
"The majority of the existing literature on simultaneous control charts, i.e. control charting mechanisms that monitor multiple population parameters such as mean and variance on a single chart, assume that the process is normally distributed. In order to adjust and maintain the overall type-I error probability, these existing charts rely largely on the property that the sample mean and sample variance are independent under the normality assumption. Furthermore, the existing charting procedures cannot be readily extended to non-normal processes. In this article, we propose and study a general charting mechanism which can be used to construct simultaneous control charts for normal and non-normal processes. The proposed control chart, which we call the density control chart, is essentially based on the premise that if a sample of observations is from an in-control process, then another sample of observations is no less likely to be also from the in-control process if the likelihood of the latter is no less than the likelihood of the former. The density control chart is developed for normal and non-normal processes where the distribution of the plotting statistic of the density control chart can be explicitly derived. Real examples are given and discussed in these cases. We also discuss how the density control chart can be constructed in cases when the distribution of the plotting statistic cannot be determined. A discussion of potential future research is also given."
Uncertainty analysis for measurement of measurand
(2010-11-01)
Chen, Hung-Chia
;
Wu, Pei-Chen
;
Huang, Jing-Ye
;
Chen, Lin-An
;
統計學研究所
For measuring the true value of a measurand, vague statistical concept of measurand results in inefficient uncertainty analysis of measurement. The vagueness is caused by the fact that true value of the measurand is an unknown parameter such as population mean or median and the measurement of this true value is a random variable. Generally a parameter may be estimated remarkably more efficiently than the prediction of the random variable. The classical uncertainty analysis in the literature has been developed based on the structure that a measurand is a random variable. This misspecification of statistical concept costs serious price of sacrificing efficiency in terms of length of the uncertainty interval. The purpose of present study is to formally formulate a statistical model for the true value of measurand and provide an uncertainty analysis for the measurement of this true value. (C) 2010 Elsevier Ltd. All rights reserved.