Development of a solid‐phase microextraction LC–MS/MS method for determination of oxidative stress biomarkers in biofluids

Recently the connection between oxidative stress and various diseases, including cancer and Alzheimer's, attracts notice as a pathway suitable for diagnostic purposes. 8‐Oxo‐deoxyguanosine and 8‐oxo‐deoxyadenosine produced from the interaction of reactive oxygen species with DNA become prominent as biomarkers. Several methods have been developed for their determination in biofluids, including solid‐phase extraction and enzyme‐linked immunosorbent assays. However, still, there is a need for reliable and fast analytical methods. In this context, solid‐phase microextraction offers many advantages such as flexibility in geometry and applicable sample volume, as well as high adaptability to high‐throughput sampling. In this study, a solid‐phase microextraction method was developed for the determination of 8‐oxo‐deoxyguanosine and 8‐oxo‐deoxyadenosine in biofluids. The extractive phase of solid‐phase microextraction consisted of hydrophilic–lipophilic balanced polymeric particles. In order to develop a solid‐phase microextraction method suitable for the determination of the analytes in saliva and urine, several parameters, including desorption solvent, desorption time, sample pH, and ionic strength, were scrutinized. Analytical figures of merit indicated that the developed method provides reasonable interday and intraday precisions (<15% in both biofluids) with acceptable accuracy. The method provides a limit of quantification for both biomarkers at 5.0 and 10.0 ng/mL levels in saliva and urine matrices, respectively.     

Capability of Urine Analysis for the Disease Blastomycosis Using Infrared Spectroscopy with Eigenvector Signal to Noise Assessment

ABSTRACT

Blastomyces dermatitidis is the etiological agent of the relatively common disease blastomycosis found in certain regions of the United States. In order to discern the presence of blastomycosis, microorganisms present in biofluids of infected individuals must be incubated and cultured and then identified by microscopic observation. This procedure is time consuming due to difficult incubation conditions and necessitates special safeguards. An enzyme-linked immunosorbent assay (ELISA) was developed in an attempt to quicken diagnosis. The immunological assay, however, also requires incubations as well as special reagents. This paper explores the potential of using infrared spectroscopy for determination of blastomycosis in urine samples from infected dogs. The regression methods of principal component regression (PCR) and partial least squares (PLS) are used to develop models. Recently introduced regression diagnostics in conjunction with new diagnostic tools described in this paper are used to determine final models. One of the new tools allows for an estimate of the signal (information) to noise ratio, i.e., reliability, for each eigenvector's contribution to the model. Based on diagnostic information, it is concluded that PCR and PLS are generating the same models.     

硝酸镥急性毒性的体液核磁共振氢谱研究

采用现代核磁共振技术,通过分析灌胃给药0．01、0．05、0．2、2、10和100ms／kg剂量Lu(NO3)3 24h内大鼠尿液及24h后大鼠血清的核磁共振氢谱(^1HNMR),由体液中内源性代谢物浓度的变化研究了稀土化合物在动物体内急性毒性。较高剂量组体液中的氨基酸、尿囊素、柠檬酸、氮氧三甲胺和肌酸酐等重要内源性代谢物的核磁共振谱峰强度发生了明显的变化,说明动物体内的代谢物出现异常：高剂量的稀土的引入可能使动物肾脏和肝脏均受到损害,且受损程度随稀土剂量的增高而渐趋严重。     

关于飞行和游动的生物力学研究

论述了飞行和游动生物力学的任务和意义,以及重大科学问题和与仿生技术相关的重大需求,并概要地介绍了与生物外部流体力学有关的科学问题、研究现状以及我国现有的研究基础和特色.文中针对如下若干重点科学问题进行了论述,具体包括Gray疑题及鱼类阻力的测定问题、鱼类机动运动的特征和机理、鱼类游动的流-固耦合及整体模化等交叉问题、昆虫运动的非定常流动控制机理和能耗、昆虫翼的柔性变形效应及抗风机制、昆虫和鱼的自由运动的运动学和动力学测量.图0参72      

Analysis of high gradient magnetic field effects on distribution of nanoparticles injected into pulsatile blood stream

Magnetic nanoparticles are widely used in a wide range of applications including data storage materials, pharmaceutical industries as magnetic separation tools, anti-cancer drug carriers and micro valve applications. The purpose of the current study is to investigate the effect of a non-uniform magnetic field on bio-fluid (blood) with magnetic nanoparticles. The effect of particles as well as mass fraction on flow field and volume concentration is investigated. The governing non-linear differential equations, concentration and Navier-stokes are coupled with the magnetic field. To solve these equations, a finite volume based code is developed and utilized. A real pulsatile velocity is utilized as inlet boundary condition. This velocity is extracted from an actual experimental data. Three percent nanoparticles volume concentration, as drug carrier, is steadily injected in an unsteady, pulsatile and non-Newtonian flow. A power law model is considered for the blood viscosity. The results show that during the systole section of the heartbeat when the blood velocity increases, the magnetic nanoparticles near the magnetic source are washed away. This is due to the sudden increase of the hydrodynamic force, which overcomes the magnetic force. The probability of vein blockage increases when the blood velocity reduces during the diastole time. As nanoparticles velocity injection decreases (longer injection time) the wall shear stress (especially near the injection area) decreases and the retention time of the magnetic nanoparticles in the blood flow increases.     

Enhancement of measurement accuracy of X‐ray PIV in comparison with the micro‐PIV technique

The X‐ray PIV (particle image velocimetry) technique has been used as a non‐invasive measurement modality to investigate the haemodynamic features of blood flow. However, the extraction of two‐dimensional velocity field data from the three‐dimensional volumetric information contained in X‐ray images is technically unclear. In this study, a new two‐dimensional velocity field extraction technique is proposed to overcome technological limitations. To resolve the problem of finding a correction coefficient, the velocity field information obtained by X‐ray PIV and micro‐PIV techniques for disturbed flow in a concentric stenosis with 50% severity was quantitatively compared. Micro‐PIV experiments were conducted for single‐plane and summation images, which provide similar positional information of particles as X‐ray images. The correction coefficient was obtained by establishing the relationship between velocity data obtained from summation images (V_S) and centre‐plane images (V_C). The velocity differences between V_S and V_C along the vertical and horizontal directions were quantitatively analysed as a function of the geometric angle of the test model for applying the present two‐dimensional velocity field extraction technique to a conduit of arbitrary geometry. Finally, the two‐dimensional velocity field information at arbitrary positions could be successfully extracted from X‐ray images by using the correction coefficient and several velocity parameters derived from V_S.     

The journal Communications in Numerical Methods in Engineering with Biomedical Applications becomes the International Journal for Numerical Methods in Biomedical Engineering (IJNMBE) from 1st January 2010

Communications in Numerical Methods in Engineering, founded by Roland W. Lewis in 1985, will change its title to the ‘International Journal for Numerical Methods in Biomedical Engineering’ and has a revised Aims and Scope. Copyright © 2009 John Wiley & Sons, Ltd.