Ultrasonic monitoring of droplets’ evaporation: Application to human whole blood

During a colloidal droplet evaporation, a sol–gel transition can be observed and is described by the desiccation time τ_D and the gelation time τ_G. These characteristic times, which can be linked to viscoelastic properties of the droplet and to its composition, are classically rated by analysis of mass droplet evolution during evaporation. Even if monitoring mass evolution versus time seems straightforward, this approach is very sensitive to environmental conditions (vibrations, air flow…) as mass has to be evaluated very accurately using ultra-sensitive weighing scales. In this study we investigated the potentialities of ultrasonic shear reflectometry to assess τ_D and τ_G in a simple and reliable manner. In order to validate this approach, our study has focused on blood droplets evaporation on which a great deal of work has recently been published. Desiccation and gelation times measured with shear ultrasonic reflectometry have been perfectly correlated to values obtained from mass versus time analysis. This ultrasonic method which is not very sensitive to environmental perturbations is therefore very interesting to monitor the drying of blood droplets in a simple manner and is more generally suitable for complex fluid droplets evaporation investigation.     

Determination of Glutathione on High Performance Liquid Chromatography Using N-Chlorodansylamide (NCDA)

Abstract

Glutathione was found to fluoresce on reaction with N-chloro-5-dimethylaminonaphthalene-l-sulfonamide (NCDA). NCDA was applied to the assay of glutathione in solution and on reversed phase high-performance liquid chromatography using tetra-n-butylammonium bromide as a paired ion. The latter method was applicable to the assay of blood glutathione.     

Determination of gemifloxacin on dried blood spots by hydrophilic interaction liquid chromatography with fluorescence detector: application to pharmacokinetics in rats

A highly selective, sensitive and rapid hydrophilic liquid interaction chromatographic method was developed and validated for determination of gemifloxacin on dried blood spots. The chromatographic separation was achieved on a reversed‐phase zwitterionic hydrophilic interaction liquid chromatographic ZIC®HILIC‐C₁₈ (4.6 × 100 mm; 5 µm) column using acetonitrile–10 mM ammonium acetate (pH 3.5; 80:20, v/v) as a mobile phase in an isocratic elution mode at a flow rate 0.6 mL/min at 27 °C. An on‐line fluorescence detector set at excitation and emission wavelengths of 269 and 393 nm, respectively was used for monitoring column eluents. Ciprofloxacin was used as an internal standard. The method was validated for accuracy, precision, linearity and selectivity by design of experiments following ICH guidelines. The assay exhibited a linear range of 25–5000 ng/mL for gemifloxacin on dried blood spots. The lower limit of detection was found to be 10 ng/mL. The intra‐ and inter‐assay coefficients of variation did not exceed 7.4% deviation of the nominal concentration. The recovery of GFX from dried blood spots was >95.0% and its stability was excellent with no evidence of degradation during sample processing for at least 3 months storage in a freezer at ?20 °C. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of acetone,butanol and carbon dioxide as new breath biomarkers for convenient and noninvasive diagnosis of obstructive sleep apnea syndrome

The objective of the present study was to investigate whether analysis of carbon dioxide, acetone and/or butanol present in human breath can be used as a simple and noninvasive diagnosis method for obstructive sleep apnea syndrome (OSAS). For this purpose, overnight changes in the concentrations of these breath molecules were measured before and after sleep in 10 patients who underwent polysomnography and were diagnosed with OSAS, and were compared with the levels of these biomarkers determined after sleep in 10 healthy subjects. The concentrations of exhaled carbon dioxide were measured using external cavity laser‐based off‐axis cavity enhanced absorption spectroscopy, whereas the levels of exhaled acetone and butanol were determined using thermal desorption gas chromatography mass spectrometry. We observed no significant changes in the levels of exhaled acetone and carbon dioxide in OSAS patients after sleep compared with pre‐sleep values and compared with those in healthy control subjects. However, for the first time, to our knowledge, analyses of expired air showed an increased concentration of butanol after sleep compared with that before sleep and compared with that in healthy subjects. These results suggest that butanol can be established as a potential biomarker to enable the convenient and noninvasive diagnosis of OSAS in the future.     

An adaptive finite element method for the modeling of the equilibrium of red blood cells

This contribution is concerned with the numerical modeling of an isolated red blood cell (RBC), and more generally of phospholipid membranes. We propose an adaptive Eulerian finite element approximation, based on the level set method, of a shape optimization problem arising in the study of RBCs. We simulate the equilibrium shapes that minimize the elastic bending energy under prescribed constraints of fixed volume and surface area. An anisotropic mesh adaptation technique is used in the vicinity of the cell membrane to enhance the robustness of the method. Efficient time and spatial discretizations are considered and implemented. We address in detail the main features of the proposed method, and finally we report several numerical experiments in the two‐dimensional and the three‐dimensional axisymmetric cases. The effectiveness of the numerical method is further demonstrated through numerical comparisons with semi‐analytical solutions provided by a reduced order model. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of high dose isoflurane on cerebral blood flow in macaque monkeys

The effect of high dose isoflurane on cerebral blood flow (CBF) was investigated in adult macaque monkeys receiving 1% to 2% isoflurane with the pseudo continuous arterial-spin-labeling (pCASL) MRI technique. High concentration (2%) of isoflurane resulted in significant increase in the mean CBF of the global, cortical, subcortical regions and the regional CBF in all subcortical structures and most cortical structures (such as motor cortex, anterior cingulate cortex, but not media prefrontal cortex). In addition, the changes of regional CBF in the affected regions correlated linearly with increasing isoflurane concentrations. The study demonstrates region-specific CBF abnormal increase in adult macaque monkeys under high dose (2%) isoflurane and suggests that the brain functionality in the corresponding structures may be affected and need to be taken consideration in either human or non-human primate neuroimaging studies.     

Intravoxel incoherent motion (IVIM) imaging at different magnetic field strengths: What is feasible?

Background

Due to limited SNR the cerebral applications of the intravoxel incoherent motion (IVIM) concept have been sparse. MRI hardware developments have resulted in improved SNR and this may justify a reassessment of IVIM imaging for non-invasive quantification of the cerebral blood volume (CBV) as a first step toward determining the optimal field strength.

Purpose

To investigate intravoxel incoherent motion imaging for its potential to assess cerebral blood volume (CBV) at three different MRI field strengths.

Materials and methods

Four volunteers were scanned twice at 1.5 T, 3 T as well as 7 T. By correcting for field-strength-dependent effects of relaxation, estimates of corrected CBV (cCBV) were obtained in deep gray matter (DGM), frontal gray matter (FGM) and frontal white matter (FWM), using Bayesian analysis. In addition, simulations were performed to facilitate the interpretation of experimental data.

Results

In DGM, FGM and FWM we obtained cCBV estimates of 2.2 ml/100 ml, 2.7 ml/100 ml, 1.4 ml/100 ml at 1.5 T; 3.7 ml/100 ml, 5.0 ml/100 ml, 3.2 ml/100 ml at 3 T and 15.5 ml/100 ml, 20.3 ml/100 ml, 7.0 ml/100 ml at 7 T.

Conclusion

Quantitative cCBV values obtained at 1.5 T and 3 T corresponded better to physiological reference values, while 7 T showed the largest deviation from expected values. Simulations of synthetic tissue voxels indicated that the discrepancy at 7 T can partly be explained by SNR issues. Results were generally more repeatable at 7 T (intraclass correlation coefficient, ICC = 0.84) than at 1.5 T (ICC = 0.68) and 3 T (ICC = 0.46).     

大鼠的发炎白细胞的喇曼光谱研究

为了研究大鼠处于正常状态和发炎状态下白细胞内部的物质是否发生变化,制备了35%总体表面积Ⅲ度烫伤导致全身炎症的模型,采用一个激发波长为780 nm的半导体激光束来囚禁和激发正常与发炎两种状态下单个白细胞的喇曼光谱.结果显示,正常状态和发炎状态下的白细胞喇曼光谱有显著的区别,主要在726、785、935、1 093、1 371和1 657 cm－1处发炎白细胞的峰值强度比正常白细胞明显高出很多|通过光谱指认表明,当机体发炎时,白细胞中的蛋白质氨基酸含量基本没有变化,但是蛋白质结构发生明显改变|核酸的碱基含量增加,DNA双螺旋结构发生改变.利用PCA主成份对单个白细胞的喇曼光谱进行分析,发现通过PCA可以完全区分出正常状态和发炎状态的白细胞.     

中红外无创血糖研究进展并论角质层影响

在介绍中红外无创血糖研究进展的基础上,实验探讨了组织液渗透到手指皮肤表面时,角质层对血糖测量的影响.加入角质层干扰信息前,用偏最小二乘法(PLSR)建立了模拟组织液中葡萄糖定标模型,其内部交叉验证均方差(RMSECV)为9.6 mg/dL;加入三个志愿者手指皮肤吸收的干扰信息后,所得三个模型的RMSECV分别为17.4...