Comparative evaluation of modified trichrome and Uvitex 2B stains for detection of low numbers of microsporidial spores in stool specimens

At present, the laboratory diagnosis of intestinal infections caused by microsporidia depends on the detection of the typical spores either with a modified trichrome stain (MTS) or by staining with fluorochromes. The purpose of the present study was (i) to compare staining with MTS (MTS method) and the staining with the fluorochrome Uvitex 2B (U2B method) with respect to their sensitivities and specificities, particularly in the presence of low numbers of spores, and (ii) to evaluate their reliabilities under routine laboratory conditions. First, 30 negative human stool specimens as well as 30 specimens enriched with a low concentration of microsporidial spores were examined. The U2B and MTS methods detected 27 and 30, of the positive samples, respectively (95% confidence intervals for sensitivity, 0.73 to 0.98 for the U2B method and 0.88 to 1.00 for the MTS method) without yielding false-positive results (95% confidence intervals for specificity, 0.88 to 1.00 for the MTS and U2B methods). In addition, analysis of serial dilutions of 17 stool specimens from AIDS patients containing microsporidia revealed comparable detection thresholds (P = 0.52) for both methods. Finally, 40 slides prepared from one stool specimen containing very few microsporidia and 40 negative slides were included in the routine diagnostic program during 1 month in order to monitor laboratory handling and run-to-run variations. Again, both methods exhibited comparable sensitivities (95% confidence intervals, 0.83 to 0.99 for the MTS method and 0.91 to 1.00 for the U2B method) and specificities (95% confidence intervals, 0.91 to 1.00 for the MTS and U2B methods). In conclusion, MTS and U2B methods are equally useful in the diagnosis of microsporidiosis. However, since detection thresholds for both methods differed considerably in all diluted stool specimens, performance of a combination of both methods may be more sensitive than the performance of only one procedure in the event of very low numbers of microsporidial spores.     

Usage of polymer brushes as substrates of bone cells

Implant medical research and tissue engineering both target the design of novel biomaterials for the improvement of human health and clinical applications. In order to develop improved surface coatings for hard tissue (bone) replacement materials and implant devices, we are developing micropatterned coatings consisting of polymer brushes. These are used as organic templates for the mineralization of calcium phosphate in order to improve adhesion of bone cells. First, we give a short account of the current state-of-the-art in this particular field of biomaterial development, while in the second part the preliminary results of cell culture experiments are presented, in which the biocompatibility of polymer brushes are tested on human mesenchymal stem cells.     

Rapid prototyping of nanofluidic systems using size-reduced electrospun nanofibers for biomolecular analysis

Biomolecular transport in nanofluidic confinement offers various means to investigate the behavior of biomolecules in their native aqueous environments, and to develop tools for diverse single-molecule manipulations. Recently, a number of simple nanofluidic fabrication techniques has been demonstrated that utilize electrospun nanofibers as a backbone structure. These techniques are limited by the arbitrary dimension of the resulting nanochannels due to the random nature of electrospinning. Here, a new method for fabricating nanofluidic systems from size-reduced electrospun nanofibers is reported and demonstrated. As it is demonstrated, this method uses the scanned electrospinning technique for generation of oriented sacrificial nanofibers and exposes these nanofibers to harsh, but isotropic etching/heating environments to reduce their cross-sectional dimension. The creation of various nanofluidic systems as small as 20 nm is demonstrated, and practical examples of single biomolecular handling, such as DNA elongation in nanochannels and fluorescence correlation spectroscopic analysis of biomolecules passing through nanochannels, are provided.     

Determination of Clozapine and its Metabolite,Norclozapine in Various Biological Matrices Using High-Performance Liquid Chromatography

Purpose. To develop and validate an HPLC method for the quantitation of clozapine and its metabolite, norclozapine in human plasma, rat plasma, and the various human plasma lipoprotein fractions. Methods. Using liquid-liquid extraction, clozapine, and norclozapine are extracted from the biological matrix with MTBE. After concentration, the residue was reconstituted in 1mM HCl and injected on to a C6 Phenyl column (3μm, 2.0×150 mm). Mobile phase was 10mM Ammonium Acetate, pH 5—Acetonitrile—Methanol (5:3:2, v/v/v). Loxapine served as the internal standard. Absorbance was measured at 254 nm. Results. Quantitation limits for clozapine and norclozapine was 100 ng/mL and 50 ng/mL, respectively. Recovery for both clozapine and norclozapine was near 100%. Percent accuracy for intraday variability in human plasma, rat plasma, and human TRL, HDL, LDL, and LPDP lipoprotein fraction was between 92 to 113% for both analytes. Intraday precision for the same matrices was less than 9% CV for both analytes. Percent accuracy and precision for interday variability in human plasma was 97 to 103% and less than 10% CV, respectively. Samples were stabile in the autosampler for 80 h at 10°C and on the benchtop for 2 h. It should be noted, Clozapine-N-oxide, which is a known metabolite of Clozapine, was not determined since it is not clinically active. Conclusions. This method is a simple, fast and robust HPLC assay for the determination of clozapine and norclozapine in various matrices and lipoprotein fractions.     

发酵乳制品与中老年人群健康相关性研究进展：来自队列研究的证据

发酵乳制品因发酵而发生结构和质地改变,并产生独特营养物质,且具有特殊的风味和营养特点,对中老年人健康具有较多健康益处。基于全球队列研究的相关证据,本文综述了发酵乳制品摄入与中老年人群超重/肥胖、心脑血管疾病、糖尿病前期和糖尿病、认知、肿瘤发生间的相关性,以及发酵乳制品潜在健康作用机制的研究进展。     

Single‐cell gel electrophoresis: a tool for investigation of DNA protection or damage mediated by dietary antioxidants

One method of assessing DNA damage is the comet assay, which was developed in 1988. The comet assay enables the detection of DNA strand breaks in individual cells. This test has also been used to study the in vitro and in vivo genotoxic or genoprotective effects of certain agents such as dietary antioxidants. This paper aims to consolidate the antioxidant and pro‐oxidant effects of a series of dietary agents which have been evaluated by comet assay. Copyright © 2007 Society of Chemical Industry     

A Cell‐Based Model for Multi‐class Doubly Stochastic Dynamic Traffic Assignment

Abstract: This article proposes a cell‐based multi‐class dynamic traffic assignment problem that considers the random evolution of traffic states. Travelers are assumed to select routes based on perceived effective travel time, where effective travel time is the sum of mean travel time and safety margin. The proposed problem is formulated as a fixed point problem, which includes a Monte–Carlo‐based stochastic cell transmission model to capture the effect of physical queues and the random evolution of traffic states during flow propagation. The fixed point problem is solved by the self‐regulated averaging method. The results illustrate the properties of the problem and the effectiveness of the solution method. The key findings include the following: (1) Reducing perception errors on traffic conditions may not be able to reduce the uncertainty of estimating system performance, (2) Using the self‐regulated averaging method can give a much faster rate of convergence in most test cases compared with using the method of successive averages, (3) The combination of the values of the step size parameters highly affects the speed of convergence, (4) A higher demand, a better information quality, or a higher degree of the risk aversion of drivers can lead to a higher computation time, (5) More driver classes do not necessarily result in a longer computation time, and (6) Computation time can be significantly reduced by using small sample sizes in the early stage of solution processes.     

Combinatorial auction under fuzzy environment

Combinatorial auction (CA) mechanism allows bundling of multiple items in packages, which can be solved through a clearing method termed as the winner determination problem (WDP). However, to date, there has yet to be a CA model that accounts for the fuzziness of bidders’ submitted prices. The imprecision in submitted prices is the result of the time gap between bid placement and winning bid announcement, which reflects the bidders’ expected values of the goods at the point of contract sale. Despite this common understanding, conventional CA modeling still treats the prices as deterministic. This causes a major shortcoming when an uncertain environment is assumed to be deterministic and solved through conventional WDP. This study shows that a fuzzy environment modeled via a deterministic WDP approach provides overly optimistic revenue for the auctioneer. A method of using possibilistic distributions of submitted prices to account for price uncertainty is proposed and formalized as Fuzzy Combinatorial Auction Winner Determination Problem (Fuzzy CA WDP). The difference in optimal solutions in deterministic WDP and fuzzy WDP reflects the amount of over estimation when a fuzzy situation is treated as though it is precise. It also reflects the information value when the uncertainty inherent in the fuzzy environment is resolved. Given that the information value is quantified in unit dollars, the fuzzy WDP approach allows the auctioneer to estimate its “true” revenue despite price uncertainties.     

Risk-Averse Traffic Assignment with Elastic Demands: NCP Formulation and Solution Method for Assessing Performance Reliability

How reliable the transport network is greatly affects the mobility and economy of a country. To assess the reliability of the network accurately and design a reliable transport network properly, one should consider the risk taking and elastic behaviour of travel demand. This paper develops a Nonlinear Complementarity Problem (NCP) formulation considering this behaviour. The NCP formulation is transformed to a smooth and unconstrained mathematical program via a Fischer function and then solved by the proposed modified αBB (branch and bound) algorithm, while guaranteeing finite convergence to a point arbitrarily close to the global minimum (ɛ-convergence). To speed up the computation, a sampling method is suggested. A small numerical study is set up to illustrate the properties and the performance of the algorithm. The results show that the bound improving strategy, the sampling size on estimating the value of α for the convex lower bounding function, and choice of α have a strong influence of the rate of convergence.