Capillary electrophoretic separations of enzyme inhibitors with activity-based detection

A technique for separating and detecting enzyme inhibitors was developed using capillary electrophoresis with an enzyme microreactor. The on-column enzyme microreactor was constructed using one or two NdFeB magnets in two configurations to immobilize alkaline phosphatase-coated superparamagnetic beads with diameters of 2.8 µm inside a capillary before the detection window. Enzyme inhibition assays were performed by injecting a plug of inhibitor into a capillary filled with an alkaline phosphatase substrate, AttoPhos. Product generated in the enzyme microreactor was detected by laser-induced fluorescence. Inhibitor zones electrophoresed through the capillary, passed through the enzyme microreactor, and were observed as negative peaks due to decreased product formation in the presence of the inhibitors. The goal of this study was to improve peak capacities for inhibitor separations relative to previous work, which combined continuous engagement electrophoretically mediated microanalysis (EMMA) and transient engagement EMMA to study enzyme inhibition. The effects of electric field strength, bead injection time and inhibitor concentrations on peak capacity and peak width were investigated. Increasing the electric field strength from 100 V/cm to 500 V/cm caused a 2-3-fold decrease in peak capacity for alkaline phosphatase inhibition assays with arsenate, a reversible, competitive inhibitor. When the bead injection time was increased to increase the length of the immobilized bead plug, the peak capacity for arsenate reached a minimum value at 60.0 s for the one-magnet configuration and at 30.0 s for the two-magnet configuration. The peak capacity was enhanced to 20 under optimal conditions of electric field strength and bead injection time for inhibition assays with arsenate and theophylline. The inhibition peak width increased as the concentrations of arsenate and theophylline increased. Five reversible inhibitors of alkaline phosphatase (theophylline, orthovanadate, arsenate, L-tryptophan and tungstate) were separated and detected to demonstrate the ability of this technique to analyze complex inhibitor mixtures. A well-resolved, individual inhibition peak was observed for each inhibitor. Enzyme inhibition assays with a mixture of the five inhibitors were also performed with the previous EMMA method, and a peak capacity of only 3 was obtained (all 5 inhibitors could not be resolved)

trans-2,3-Bis(2,4,5-trimethyl-3-thien­yl)but-2-enedinitrile

In title compound, C18H18N2S2, the dihedral angle between two thio­phene rings is 61.83 (8)°

Health Outcomes and Socio-Economic Status among the Elderly in China: Evidence from the CHARLS Pilot

We are concerned in this paper with measuring health outcomes among the elderly in Zhejiang and Gansu provinces, China, and examining the relationships between different dimensions of health status and measures of socio-economic status (SES). We use the China Health and Retirement Longitudinal Study (CHARLS) pilot data to document health conditions among the elderly in Gansu and Zhejiang provinces, where the survey was fielded. We use a very rich set of health indicators that include both self-reported measures and biomarkers. We also examine correlations between these health outcomes and two important indicators of socioeconomic status (SES): education and log of per capita expenditure (log pce), our preferred measure of household resources. While there exists a very large literature that examines the relationships between SES and health measures, little has been done on Chinese data to see whether correlations reported in many other countries are replicated in China, particularly so for the aged. In general education tends to be positively correlated with better health outcomes, as it is in other countries. However, unmeasured community influences turn out to be highly important, much more so than one usually finds in other countries. While it is not yet clear which aspects of communities matter and why they matter, we set up an agenda for future research on this topic. We also find a large degree of under-diagnosis of hypertension, a major health problems that afflicts the aged. This implies that the current health system is not well prepared to address the rapid aging of the Chinese population, at least not in Gansu and Zhejiang.health, China

Energy Finite Element Analysis Developments for High Frequency Vibration Analysis of Composite Structures.

Energy finite element analysis (EFEA) has been proven to be an effective and reliable tool for high frequency vibration analysis. It uses the averaged energy density as the primary variable to form the governing differential equations and provides a practical approach to evaluate the structural response at high frequencies, which is hard to reach with conventional finite element analysis because of the computational cost. In the past, EFEA has been applied successfully to different structures, such as beams, rods, plates, curved panels etc. Until recently, however, not much work has been done in the field of composite structures. Research for developing a new EFEA formulation for modeling composite laminate plates is presented in this dissertation. The EFEA governing differential equation, with the time- and space- averaged energy density as the primary variable, is developed for general composite laminate plates. The power transmission characteristics at plate junctions of non-isotropic materials, including orthotropic plates and composite laminate plates are studied in order to obtain the power transmission coefficients at the junction. These coefficients are utilized to compute the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations can be solved numerically and the energy density distribution within the entire system can then be obtained. The results from the EFEA formulation have been validated through comparison with results from very dense FEA models.Ph.D.Naval Architecture & Marine EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/58531/1/yanxy_1.pd

Validity of self-reported weight, height and resultant body mass index in Chinese adolescents and factors associated with errors in self-reports

<p>Abstract</p> <p>Background</p> <p>Validity of self-reported height and weight has not been adequately evaluated in diverse adolescent populations. In fact there are no reported validity studies conducted in Asian children and adolescents. This study aims to examine the accuracy of self-reported weight, height, and resultant BMI values in Chinese adolescents, and of the adolescents' subsequent classification into overweight categories.</p> <p>Methods</p> <p>Weight and height were self-reported and measured in 1761 adolescents aged 12-16 years in a cross-sectional survey in Xi'an city, China. BMI was calculated from both reported values and measured values. Bland-Altman plots with 95% limits of agreement, Pearson's correlation and Kappa statistics were calculated to assess the agreement.</p> <p>Results</p> <p>The 95% limits of agreement were -11.16 and 6.46 kg for weight, -4.73 and 7.45 cm for height, and -4.93 and 2.47 kg/m²for BMI. Pearson correlation between measured and self-reported values was 0.912 for weight, 0.935 for height and 0.809 for BMI. Weighted Kappa was 0.859 for weight, 0.906 for height and 0.754 for BMI. Sensitivity for detecting overweight (includes obese) in adolescents was 56.1%, and specificity was 98.6%. Subjects' area of residence, age and BMI were significant factors associated with the errors in self-reporting weight, height and relative BMI.</p> <p>Conclusions</p> <p>Reported weight and height does not have an acceptable agreement with measured data. Therefore, we do not recommend the application of self-reported weight and height to screen for overweight adolescents in China. Alternatively, self-reported data could be considered for use, with caution, in surveillance systems and epidemiology studies.</p