Disentangling the complex racial disparities in health among adult beneficiaries under Medicaid managed care: A structural equation modeling approach

There are few studies of the important issue of racial and ethnic disparities in Medicaid managed care settings. This study addresses this deficiency using data collected by telephone interviews from a randomly stratified sample of adults who were continuously enrolled in North Carolina Medicaid managed care for at least six months prior to sampling in 2006. It uses univariate statistics to describe health status and conducts a Pearson chi-square test to examine health status between non-Hispanic black adults and non-Hispanic white adults. Because chronic conditions were significantly related to health status, the study also computes three separate structural equation models to investigate the complex relationships between race, health status, and a number of other independent variables that theory suggests. The Medicaid managed care adult population had bad health: 50.02% reported “poor” or “fair” health, and 63.60% suffered from a chronic condition. Yet, contrary to most of the literature on race and health, the health status of non-Hispanic black adults in this study was significantly superior to that reported by non-Hispanic white adults. This surprising finding held for both the model of overall sample of adults, which fitted adequately with the sample data (CFI=0.921; RMSEA=.035) and explained 31% of the variance in health, and the model of adults with chronic conditions, which also fitted adequately with the sample data (CFI=0.93; RMSEA=.036) and explained 22% of the variance in health

Hepatic zinc deficiency in alcoholic liver disease: dysregulation of zinc transporters and activation of mitochondrial apoptotic cell death pathway

Excessive alcohol consumption exerts health concerns, and alcoholic liver disease (ALD) is a major cause of morbidity and mortality in the United States. However, there is still lack of an effective treatment. Zinc deficiency has been found in alcoholics over a half century ago. Experimental animals chronically exposed to alcohol exhibit decreased zinc level in the liver as well. Therefore, it is critical to determine the role of zinc deficiency in the pathogenesis of ALD. Our laboratory has repeatedly demonstrated that alcohol feeding significantly decreased hepatic zinc levels in rodents. In addition, clinical studies have shown that the severity of zinc deficiency is positively correlated with the stage of ALD. However, the mechanism that underlies alcohol-induced hepatic zinc deficiency is still unclear. Therefore, we hypothesized that dysregulation of hepatic zinc transporters, ZIP and ZnT, result in alcohol-induced zinc deficiency in the liver and decreased zinc levels in the liver enhanced intrinsic apoptotic cell death pathway via endoplasmic reticulum (ER) and mitochondrial stress. Aim 1 of this project investigated the expression of zinc transporters in alcohol- and pair-fed mice at different time points, along with the effect of reactive oxygen species (ROS) on the expression of zinc transporters. The results indicate that increased ROS due to chronic alcohol exposure altered the expression of zinc transporters, which account for the decrease in hepatic zinc level. Our laboratory also demonstrated that zinc deficiency contributes to ALD by decreasing ß-oxidation and blunting very low density lipoprotein (VLDL) secretion. Furthermore, zinc deficiency is associated with increased oxidative stress. Zinc supplementation protects against alcohol-induced liver injury. Given the fact that increased oxidative stress and impaired mitochondrial functions are closely linked with the pathogenesis of apoptosis and increased hepatic apoptosis plays a critical role in the development of ALD, the role of zinc deficiency in the pathogenesis of apoptosis was assessed in Aims 2 and 3. In Aim 2, increased endoplasmic reticulum (ER) stress indicated by C/EBP homologous protein (CHOP) expression after zinc deprivation was linked with the activation of mitochondrial apoptotic cell death pathway, which was partially dependent on oxidative stress. Data obtain in Aim 3 demonstrated that mitochondrial biogenesis regulators were downregulated by zinc deprivation, which resulted in defect of the mitochondrial electron transport chain. As a result, overproduction of ROS and decreased mitochondrial membrane potential occurred. Collectively, these findings provided critical insights into the molecular mechanisms of alcohol consumption-induced zinc deficiency and zinc deficiency-induced activation of apoptosis. However, we still need to investigate i) the direct effect of subcellular zinc deficiency on organelle functions, and ii) the beneficial effect of dietary zinc supplementation on subcellular zinc deficiency as well as organelle functions

EVALUATING AND EXTENDING THE CONCEPT OF WISDOM OF CROWDS IN THE CONTEXT OF PROBLEM SOLVING

James Surowiecki in his book on the wisdom of crowds [Jame04] wrote about the decisions made based on the aggregation of information in groups. Knowing the many case studies and anecdotes which show the success of wisdom of crowds, he argues that under certain circumstances the wisdom of crowds is often better than that of any single member in the group. This paper provides a new way of problem solving– using the wisdom of crowds (collective wisdom) to handle continuous decision making problems, especially in a complex and rapidly changing world. By extending the concept of Wisdom of Crowds, the method of using collective wisdom is applied to various fields, from Prisoner‘s Dilemma to simplified stock market. Simulations are built to evaluate this new problem solving method and different aggregation strategies are suggested based on different environments

Nonparametric pricing kernel models

The capital asset pricing model (CAPM) and the arbitrage asset pricing theory (APT) have been the cornerstone in theoretical and empirical finance for the recent few decades. The classical CAPM usually assumes a simple and stable linear relationship between an asset’s systematic risk and its expected return. However, this simple relationship assumption has been challenged and rejected by several recent studies based on empirical evidences of time variation in betas and expected returns. It is well documented that large pricing errors could be due to the linear ap- proach used in a nonlinear model and treating a non-linear relationship as a linear could lead to serious prediction problems in estimation. To overcome these problems, in the first part of this dissertation I would like to investigate a general nonpara- metric asset pricing model to avoid functional form misspecification of betas, risk premia, and the stochastic discount factor by considering estimating unknown func- tional involved in the nonparametric pricing kernel. To estimate the nonparametric functionals, I propose a new nonparametric estimation procedure, termed as non- parametric generalized estimation equations (NPGEE), which combines the local linear fitting and the generalized estimation equations. I establish the asymptotic properties of the resulting estimator. Also, as a rule of thumb, I propose a data- driven method to select the bandwidth and provide a consistent estimate of the asymptotic variance. The nonparametric method may provide a useful insight for further parametric fitting, while parametric models for time-varying betas can be most efficient if the underlying betas are specified. However, a misspecification may cause serious bias and model constraints may distort the betas in local area. Hence, to test whether the pricing kernel model has some specific parametric form becomes essentially impor- tant. In the second part of this dissertation, I propose a consistent nonparametric testing procedure to test whether the model is correctly specified and I establish the asymptotic properties of the test statistic using a U-statistic technique. Finite sample results are investigated using Monte Carlo simulation studies in order to show the usefulness of the estimation method and the test statistics. The empirical applications using CRSP monthly returns are also implemented to illustrate our proposed models and methods

An experimental and theoretical study of cobalt (II) and nickel (II) complexes with acetonitrile as ligands

Acetonitrile is a weak base and is not frequently used as a ligand in coordination chemistry investigations. Due to the nature of this ligand, it was thought that cobalt(II) and nickel(II) complexes with acetonitrile ligands would be unstable and that the solid state of these complexes probably would not exist. Basolo1 indicated that solid salts separated from solution easiest for combinations of either small-small or large-large cations and anions, preferably with systems having the same but opposite charges on the counter ions. The driving force for the large cation-large anion combination to form solid is the small hydration energy of the ions. When Co (II) and Ni(II) are completely solvated by acetonitrile, they form large cations; these large cations could be effectively stabilized by large anions such as tetrachlorometallates or tetrabromometallates. The purpose of this study is fourfold. The first is to synthesize the complexes by using large anions, BCl4 and BBr4. The second is to compare results with similar systems. The third is to make theoretical investigations of the molecular model assuming distortion and the last is to analyze the complexes experimentally

Ancient gene transfer from algae to animals: Mechanisms and evolutionary significance

Background Horizontal gene transfer (HGT) is traditionally considered to be rare in multicellular eukaryotes such as animals. Recently, many genes of miscellaneous algal origins were discovered in choanoflagellates. Considering that choanoflagellates are the existing closest relatives of animals, we speculated that ancient HGT might have occurred in the unicellular ancestor of animals and affected the long-term evolution of animals. Results Through genome screening, phylogenetic and domain analyses, we identified 14 gene families, including 92 genes, in the tunicate Ciona intestinalis that are likely derived from miscellaneous photosynthetic eukaryotes. Almost all of these gene families are distributed in diverse animals, suggesting that they were mostly acquired by the common ancestor of animals. Their miscellaneous origins also suggest that these genes are not derived from a particular algal endosymbiont. In addition, most genes identified in our analyses are functionally related to molecule transport, cellular regulation and methylation signaling, suggesting that the acquisition of these genes might have facilitated the intercellular communication in the ancestral animal. Conclusions Our findings provide additional evidence that algal genes in aplastidic eukaryotes are not exclusively derived from historical plastids and thus important for interpreting the evolution of eukaryotic photosynthesis. Most importantly, our data represent the first evidence that more anciently acquired genes might exist in animals and that ancient HGT events have played an important role in animal evolution

Transcriptome sequencing of Crucihimalaya himalaica (Brassicaceae) reveals how Arabidopsis close relative adapt to the Qinghai-Tibet Plateau

The extreme environment of the Qinghai-Tibet Plateau (QTP) provides an ideal natural laboratory for studies on adaptive evolution. Few genome/transcriptome based studies have been conducted on how plants adapt to the environments of QTP compared to numerous studies on vertebrates. Crucihimalaya himalaica is a close relative of Arabidopsis with typical QTP distribution, and is hoped to be a new model system to study speciation and ecological adaptation in extreme environment. In this study, we de novo generated a transcriptome sequence of C. himalaica, with a total of 49,438 unigenes. Compared to five relatives, 10,487 orthogroups were shared by all six species, and 4,286 orthogroups contain putative single copy gene. Further analysis identified 487 extremely significantly positively selected genes (PSGs) in C. himalaica transcriptome. Theses PSGs were enriched in functions related to specific adaptation traits, such as response to radiation, DNA repair, nitrogen metabolism, and stabilization of membrane. These functions are responsible for the adaptation of C. himalaica to the high radiation, soil depletion and low temperature environments on QTP. Our findings indicate that C. himalaica has evolved complex strategies for adapting to the extreme environments on QTP and provide novel insights into genetic mechanisms of highland adaptation in plants

A new assessment model for tumor heterogeneity analysis with [18]F-FDG PET images

It has been shown that the intratumor heterogeneity can be characterized with quantitative analysis of the [18]F-FDG PET image data. The existing models employ multiple parameters for feature extraction which makes it difficult to implement in clinical settings for the quantitative characterization. This article reports an easy-to-use and differential SUV based model for quantitative assessment of the intratumor heterogeneity from 3D [18]F-FDG PET image data. An H index is defined to assess tumor heterogeneity by summing voxel-wise distribution of differential SUV from the [18]F-FDG PET image data. The summation is weighted by the distance of SUV difference among neighboring voxels from the center of the tumor and can thus yield increased values for tumors with peripheral sub-regions of high SUV that often serves as an indicator of augmented malignancy. Furthermore, the sign of H index is used to differentiate the rate of change for volume averaged SUV from its center to periphery. The new model with the H index has been compared with a widely-used model of gray level co-occurrence matrix (GLCM) for image texture characterization with phantoms of different configurations and the [18]F-FDG PET image data of 6 lung cancer patients to evaluate its effectiveness and feasibility for clinical uses. The comparison of the H index and GLCM parameters with the phantoms demonstrate that the H index can characterize the SUV heterogeneity in all of 6 2D phantoms while only 1 GLCM parameter can do for 1 and fail to differentiate for other 2D phantoms. For the 8 3D phantoms, the H index can clearly differentiate all of them while the 4 GLCM parameters provide complicated patterns in the characterization. Feasibility study with the PET image data from 6 lung cancer patients show that the H index provides an effective single-parameter metric to characterize tumor heterogeneity in terms of the local SUV variation, and it has higher correlation with tumor volume change after radiotherapy (R2 = 0.83) than the 4 GLCM parameters (R2 = 0.63, 0.73, 0.59 and 0.75 for Energy, Contrast, Local Homogeneity and Entropy respectively). The new model of the H index has the capacity to characterize the intratumor heterogeneity feature from 3D [18]F-FDG PET image data. As a single parameter with an intuitive definition, the H index offers potential for clinical applications

Magnetic vortex oscillator driven by dc spin-polarized current

Transfer of angular momentum from a spin-polarized current to a ferromagnet provides an efficient means to control the dynamics of nanomagnets. A peculiar consequence of this spin-torque, the ability to induce persistent oscillations of a nanomagnet by applying a dc current, has previously been reported only for spatially uniform nanomagnets. Here we demonstrate that a quintessentially nonuniform magnetic structure, a magnetic vortex, isolated within a nanoscale spin valve structure, can be excited into persistent microwave-frequency oscillations by a spin-polarized dc current. Comparison to micromagnetic simulations leads to identification of the oscillations with a precession of the vortex core. The oscillations, which can be obtained in essentially zero magnetic field, exhibit linewidths that can be narrower than 300 kHz, making these highly compact spin-torque vortex oscillator devices potential candidates for microwave signal-processing applications, and a powerful new tool for fundamental studies of vortex dynamics in magnetic nanostructures.Comment: 14 pages, 4 figure

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Deletion of a gene encoding a putative deacetylase, Agd3, leads to defects in GAG deacetylation, biofilm formation, and virulence. Here, we show that Agd3 deacetylates GAG in a metal-dependent manner, and is the founding member of carbohydrate esterase family CE18. The active site is formed by four catalytic motifs that are essential for activity. The structure of Agd3 includes an elongated substrate-binding cleft formed by a carbohydrate binding module (CBM) that is the founding member of CBM family 87. Agd3 homologues are encoded in previously unidentified putative bacterial exopolysaccharide biosynthetic operons and in other fungal genomes. The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Here, the authors study an A. fumigatus enzyme that deacetylates GAG in a metal-dependent manner and constitutes a founding member of a new carbohydrate esterase family.Bio-organic Synthesi