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

Using Hybrid Angle/Distance Information for Distributed Topology Control in Vehicular Sensor Networks

In a vehicular sensor network (VSN), the key design issue is how to organize vehicles effectively, such that the local network topology can be stabilized quickly. In this work, each vehicle with on-board sensors can be considered as a local controller associated with a group of communication members. In order to balance the load among the nodes and govern the local topology change, a group formation scheme using localized criteria is implemented. The proposed distributed topology control method focuses on reducing the rate of group member change and avoiding the unnecessary information exchange. Two major phases are sequentially applied to choose the group members of each vehicle using hybrid angle/distance information. The operation of Phase I is based on the concept of the cone-based method, which can select the desired vehicles quickly. Afterwards, the proposed time-slot method is further applied to stabilize the network topology. Given the network structure in Phase I, a routing scheme is presented in Phase II. The network behaviors are explored through simulation and analysis in a variety of scenarios. The results show that the proposed mechanism is a scalable and effective control framework for VSNs

Factors that influence survival in colorectal cancer with synchronous distant metastasis

AbstractBackgroundTreatments for the purposes of curing or more effectively managing metastatic colorectal cancer (CRC) are evolving. Our study focused on patients with primary CRC with synchronous distant metastasis, and we analyzed the factors influencing patient survival.MethodsData review was conducted retrospectively. Clinicopathological parameters included age, sex, site of primary cancer, tumor cell differentiation, number of liver metastasis, presence of extrahepatic metastasis, treatment of liver metastasis, pre-treatment carcinoembryonic antigen (CEA) level, status of treatment response, salvage treatment and survival.ResultsA total of 420 patients were identified and considered for our study. Of those, 275 patients (65.4%) had liver-only metastasis, 100 patients (23.8%) had concomitant lung metastasis, and 40 patients (9.5%) had other metastases. Additionally, 145 patients (34.5%) had liver-directed treatment including surgical resection (28.5%), radiofrequency ablation (RFA) (10.6%) and transcatheter arterial chemoembolization (TAE) (1.2%). There were 80 patients (19%) with CEA levels < 10, 135 patients (32.1%) with CEA 10–100, and 165 patients (39.2%) with CEA > 100. There were 200 patients (47.6%) who had received chemotherapy, 130 patients (30.9%) with target therapy, and 40 patients (9.5%) who had not undergone any salvage treatment. Three significant factors were identified, including treatment of liver metastasis (p=0.027), pre-treatment CEA (p=0.04), and salvage treatment (p=0.005).ConclusionWe demonstrated three factors influencing patient survival including treatment of liver metastasis, pre-treatment CEA level, and salvage treatment. Aggressive treatment of liver metastasis including surgical resection or RFA combined with chemotherapeutic agents appear to provide an increased rate of survival to patients

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

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

Emergency Open Cardiac Massage via Subxyphoid Approach in Ruptured Type A Aortic Dissection

Patient sustained cardiac tamponade caused by rupture of type A aortic dissection may result in sudden death. Pericardiocentesis is a lifesaving procedure; nevertheless, blood may occlude the catheter and fail to relieve the pressure. However, open-chest cardiac massage in resuscitation has been studied in animal models by some medical centers and laboratories with inspiring results. We report a 58-year-old woman who was transferred from a local hospital with the diagnosis of cardiac tamponade caused by ruptured type A aortic dissection. Pulseless electrical activity followed by cardiac arrest occurred thereafter. Successful resuscitation in the emergency department was achieved using open cardiac massage through the sub-xyphoid region by opening a pericardial window. Therefore, in unstable patients with cardiac tamponade due to aortic dissection, this resuscitative procedure is feasible, safe and efficient

Ganoderma lucidum polysaccharides enhance CD14 endocytosis of LPS and promote TLR4 signal transduction of cytokine expression

We have previously reported that a well-characterized glycoprotein fraction containing fucose residues in an extract of Ganoderma lucidum polysaccharides (EORP) exerts certain immuno-modulation activity by stimulating the expression of inflammatory cytokines via TLR4. Continuing our studies, we have demonstrated that EORP increases the surface expression of CD14 and TLR4 within murine macrophages J774A.1 cells in vitro, and further promotes LPS binding and uptake by J774A.1 cells in a CD14-dependent fashion. Moreover, we observed the co-localization of internalized LPS with lysosome- and Golgi-apparatus markers within 5 min after J774A.1 cells stimulated with LPS. In addition, EORP pretreatment of J774A.1 cells and human blood-derived primary macrophages, followed by LPS stimulation, results in the super-induction of interleukin-1beta (IL-1) expression. Endocytosis inhibitors: such as cytochalasin D and colchicine effectively block EORP-enhanced LPS internalization by J774A.1 cells; yet they fail to decrease the LPS-induced phosphorylation of certain mitogen-activated protein kinases, and IL-1 mRNA and proIL-1 protein expression, indicating that LPS internalization by J774A.1 cells is not associated with LPS-dependent activation. Our current results could provide a potential EORP-associated protection mechanism for bacteria infection by enhancing IL-1 expression and the clearance of contaminated LPS by macrophages. J. Cell. Physiol. 212: 537–550, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56052/1/21050_ftp.pd