1,472 research outputs found
Repeated significance tests of a multi-parameter in survival analysis
[[abstract]]This paper illustrates a martingale method of constructing repeated significance tests for a multi-dimensional parameter in survival analysis by reducing it to tests for one-dimensional parameters. This illustration is made with parametric survival data with staggered entry. A simulation study is included to indicate its numerical performance.[[notice]]補正完
Shape restricted regression with random Bernstein polynomials
Shape restricted regressions, including isotonic regression and concave
regression as special cases, are studied using priors on Bernstein polynomials
and Markov chain Monte Carlo methods. These priors have large supports, select
only smooth functions, can easily incorporate geometric information into the
prior, and can be generated without computational difficulty. Algorithms
generating priors and posteriors are proposed, and simulation studies are
conducted to illustrate the performance of this approach. Comparisons with the
density-regression method of Dette et al. (2006) are included.Comment: Published at http://dx.doi.org/10.1214/074921707000000157 in the IMS
Lecture Notes Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
Profiling time course expression of virus genes---an illustration of Bayesian inference under shape restrictions
There have been several studies of the genome-wide temporal transcriptional
program of viruses, based on microarray experiments, which are generally useful
in the construction of gene regulation network. It seems that biological
interpretations in these studies are directly based on the normalized data and
some crude statistics, which provide rough estimates of limited features of the
profile and may incur biases. This paper introduces a hierarchical Bayesian
shape restricted regression method for making inference on the time course
expression of virus genes. Estimates of many salient features of the expression
profile like onset time, inflection point, maximum value, time to maximum
value, area under curve, etc. can be obtained immediately by this method.
Applying this method to a baculovirus microarray time course expression data
set, we indicate that many biological questions can be formulated
quantitatively and we are able to offer insights into the baculovirus biology.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS258 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
A Bayesian measurement error model for two-channel cell-based RNAi data with replicates
RNA interference (RNAi) is an endogenous cellular process in which small
double-stranded RNAs lead to the destruction of mRNAs with complementary
nucleoside sequence. With the production of RNAi libraries, large-scale RNAi
screening in human cells can be conducted to identify unknown genes involved in
a biological pathway. One challenge researchers face is how to deal with the
multiple testing issue and the related false positive rate (FDR) and false
negative rate (FNR). This paper proposes a Bayesian hierarchical measurement
error model for the analysis of data from a two-channel RNAi high-throughput
experiment with replicates, in which both the activity of a particular
biological pathway and cell viability are monitored and the goal is to identify
short hair-pin RNAs (shRNAs) that affect the pathway activity without affecting
cell activity. Simulation studies demonstrate the flexibility and robustness of
the Bayesian method and the benefits of having replicates in the experiment.
This method is illustrated through analyzing the data from a RNAi
high-throughput screening that searches for cellular factors affecting HCV
replication without affecting cell viability; comparisons of the results from
this HCV study and some of those reported in the literature are included.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS496 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
ESTIMATION IN A PROPORTIONAL HAZARD MODEL FOR SEMI-MARKOV COUNTING PROCESS
Abstract: Estimation is studied in a regression model for counting processes whose baseline intensity processes are of semi-Markov form. Asymptotic normality is established for a Breslow-type estimator of the cumulative baseline hazard for each gap time of the counting process
Tuberculosis in Children and Adolescents, Taiwan, 1996–2003
Analysis of data from Taiwan’s National Tuberculosis (TB) Registry showed that incidence of TB in persons <20 years of age was 9.61/100,000 person-years, biphasic, and age-relevant, with a major peak in persons slightly >12 years. Aboriginal children were 8.1–17.4× more likely to have TB than non-Aboriginal children
Epidemiological characteristics of varicella from 2000 to 2008 and the impact of nationwide immunization in Taiwan
[[abstract]]Background: Varicella has an important impact on public health. Starting in 2004 in Taiwan, nationwide free varicella vaccinations were given to 1-year-old children.Methods: Our study investigated the epidemiological characteristics of varicella from 2000 to 2008, and assessed the change of varicella epidemiology after the mass varicella immunization. ICD-9-CM codes related to varicella or chickenpox (052, 052.1, 052.2, 052.7, 052.8, 052.9) were analyzed for all young people under 20 years of age through the National Health Insurance database of Taiwan from 2000 to 2008.Results: Case numbers of varicella or chickenpox significantly declined after the nationwide immunization in 2004. Winter, particularly January, was the epidemic season of varicella. We found a significant post-vaccination decrease in incidence among preschool children, especially 3 to 6 year-old children-- the peak incidence was 66 per thousand for 4 and 5 year-old children before the nationwide immunization (2000 to 2003), and the peak incidence was 23 per thousand for 6 year-old children in 2008 (p < 0.001). Varicella-related hospitalization also significantly decreased in children younger than 6 years after the nationwide immunization.Conclusion: The varicella annual incidence and varicella-related hospitalization markedly declined in preschool children after nationwide varicella immunization in 2004
Bmi-1 Regulates Snail Expression and Promotes Metastasis Ability in Head and Neck Squamous Cancer-Derived ALDH1 Positive Cells
Recent studies suggest that ALDH1 is a putative marker for HNSCC-derived cancer
stem cells. However, the regulation mechanisms that maintain the stemness and metastatic capability
of HNSCC-ALDH1+ cells remain unclear. Initially, HNSCC-ALDH1+ cells from HNSCC patient showed
cancer stemness properties, and high expression of Bmi1 and Snail. Functionally, tumorigenic properties
of HNSCC-ALDH1+ cells could be downregulated by knockdown of Bmi-1. Overexpression of Bmi-1 altered in
expression property ALDH1− cells to that of ALDH1+ cells. Furthermore, knockdown of Bmi-1 enhanced
the radiosensitivity of radiation-treated HNSCC-ALDH1+ cells. Moreover, overexpression of Bmi-1 in
HNSCC-ALDH1− cells increased tumor volume and number of pulmonary metastatic lesions by xenotransplant
assay. Importantly, knock-down of Bmi1 in HNSCC-ALDH1+ cells significantly decreased distant metastases in
the lungs. Clinically, coexpression of Bmi-1/Snail/ALDH1 predicted the worst prognosis in HNSCC
patients. Collectively, our data suggested that Bmi-1 plays a key role in
regulating Snail expression and cancer stemness properties of HNSCC-ALDH1+ cells
Combining prostrate-specific antigen and Gleason score increases the diagnostic power of endorectal coil magnetic resonance imaging in prostate cancer pathological stage
Abstract Background: The proper use of endorectal coil MRI (eMRI) images provide detailed information for the real extent of locally prostate cancer invasion and involvement of pelvic lymph nodes. This study evaluated the accuracy of endorectal coil magnetic resonance imaging (eMRI) results, combining the preoperative prostate-specific antigen (PSA), and the biopsy Gleason score to improve the diagnostic accuracy of prostate cancer (PCa) with organ-confined disease (OCD) or extracapsular extension (ECE)/seminal vesicle invasion (SVI). Methods: Between 2001 and 2007, 94 PCa patients received eMRI testing during presurgical evaluation and underwent radical prostatectomy. As a part of routine patient workup, serum PSA level and Gleason score after pathology examination were recorded. The eMRI images were used to help assess patient PCa staging status regarding OCD or ECE/SVI. These stage assessments as evaluated through the use of MRI were compared with the final specimen pathological stage after the patients underwent radical prostatectomy. Results: Of the total 94 patients in our study, 65 had stage pT2, 12 had stage pT3a, and 17 had stage pT3b PCa. In patients with clinical stage T2 PCa, the Gleason score significantly improved the discriminative ability of eMRI to successfully predict PCa at the OCD stage. Otherwise, in cases of clinical stage T3 PCa, accurate determination of PSA levels significantly improved eMRI predictive ability to assess ECE or SVI staging. Conclusion: In clinical stage T2 PCa patients, integrating the biopsy Gleason score improved the discriminative ability to assess OCD PCa staging. Additionally, combining the preoperative PSA levels of clinical T3 prostate cancer cases with Gleason scores significantly improved the sensitivity and accuracy of eMRI diagnosis to distinguish ECE from SVI
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