Dried blood spot on‐card derivatization: an alternative form of sample handling to overcome the instability of thiorphan in biological matrix

Thiorphan, the active metabolite of racecadotril, can undergo oxidation in biological matrices such as blood and plasma. In bioanalysis, a general approach for the stabilization of such a molecule is to derivatize the thiol group to a more stable thioether, often requiring complex handling procedures at the clinical site. In this research, the concept of dried blood spot (DBS) on‐card derivatization was evaluated to stabilize thiorphan. DBS cards were in‐house pre‐treated with 2‐bromo‐3′‐methoxyacetophenone and left to dry prior to blood spotting. Thiorphan was shown to be effectively derivatized to thiorphan–methoxyacetophenone once applied on the in‐house pre‐treated cards. Thiorphan–methoxyacetophenone was extracted by soaking a 6 mm DBS punch in methanol containing the internal standard (thiorphan–methoxyacetophenone‐D₅). Chromatographic separation was achieved on a Waters XBridge C₁₈ column with a gradient elution of 5 m m NH₄HCO₃ and methanol in 2.5 min and detection by ESI(+)/MS/MS. A linear (weighted 1/x²) relationship was obtained over a concentration range of 5.00–600.00 ng/mL. The assay met regulatory guidelines acceptance criteria for sensitivity, selectivity, precision and accuracy, matrix effect, recovery, dilution integrity and multiple stability evaluations. The DBS on‐card derivatization has shown to be an easy and reliable alternative form of sample collection for the quantification of thiorphan. Copyright © 2012 John Wiley & Sons, Ltd.     

Three-dimensional cellular automaton simulation of tumour growth in inhomogeneous oxygen environment

Cellular automaton theory has previously been used to study cell growth. In this study, we present a three-dimensional cellular automaton model performing the growth simulation of normal and cancerous cells. The necessary nutrient supply is provided by an artificial arterial tree which is generated by constrained constructive optimization. Spatial oxygen diffusion is approximated again by a cellular automaton model. All results could be illustrated dynamically by three-dimensional volume visualization. Because of the chosen modelling approach, an extension of the model to simulate angiogenic processes is possible.     

Tb(III) Speciation in Human Blood Plasma by Computer Simulation

With the wide application of rare earth fertilizer and medicines1, more and more rare earths enter into environment, and also into human body via food chain. Now it is very urgent to study the biological effect of rare earths on human health and environment. After entering into human body by whatever route, lanthanide ions are transported to secondary deposition sites mainly via the plasma in the blood stream. So it is very important to study lanthanides speciation in human blood plasma. Becau…     

Instrumental Requirements for Non-Invasive Blood Glucose Measurement Using NIR Spectroscopy

The magnitude of spectral change in blood glucose measurements with diffuse reflectance spectroscopy is investigated. Spectral change is estimated by simulation of light propagation in skin tissue and measurements of absorbance spectra of aqueous glucose solution. Required sensitivity of spectrophotometers for monitoring change in the blood glucose concentration as small as 10 mg/dL has been obtained using the estimated change in the absorbance spectrum and mean pathlength of light in tissue.     

Fluorescence assay of tyrosine in blood plasma

A more simple and sensitive assay for the quantitative determination of tyrosine in blood plasma is developed on the basis of a modification of the method of S. Udenfriend (1962). A volume of 0.2 ml of plasma is used in the analysis; after its deproteinization with trichloroacetic acid, it is reacted with sodium nitride, nitrous acid, and 1-nitroso-2-naphthol at 65°C, and the content of the reaction product is measured by the fluorescence at λ_ex/λ_em=460/570 nm. The consumption of plasma and reagents is reduced by a factor of 5–10 compared to the original method; in addition, the stage of extraction with an organic solvent is excluded. The linear dependence of the fluorescence signal on the tyrosine concentration within the range of 2–60 μg/ml, high specificity, accuracy, and reproducibility of the assay are shown. The importance of tyrosine determination in monitoring of glucocorticoid therapy and protein catabolism is discussed. Institute of Photobiology, National Academy of Sciences of Belarus, 27, Akademicheskaya St., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 366–371, May–June, 1998.     

功率谱和相关函数在脑血氧监测中的应用

采用自制的近红外双波长脑血氧监测仪实时采集人脑血和氧的数据，应用功率谱和相关函数的方法对采集的脑血氧的数据波形进行分析．结果发现正常人脑血氧波形之间有着严格的相关性，功率谱曲线主频峰清晰，血氧的功率谱曲线吻合好；脑缺氧病人血氧波形间的相关性差，功率谱曲线表现为主频峰不清晰，功率谱曲线吻合性差。临床试验表明：脑血氧波形、功率谱和相关函数对于分析人脑血、氧生理状况及其变化具有较好的效果。     

Taking into account scattering of polarized laser radiation by cuvet walls when probing blood

We have studied the ratio of the intensities of radiation scattered by a layer of blood in a cuvet and by the cuvet walls for normal incidence or incidence at the Brewster angle for probing radiation from a He-Ne laser, linearly polarized in the plane of incidence (plane of observation) or orthogonal to that plane. We have compared it with the intensity of the radiation reflected by the surface of the cuvet wall, as estimated based on the geometric approximation. We have found the optimal conditions for probing and observing scattering for the layer in a cuvet, where such conditions are characterized by a minimal effect from the cuvet walls and the maximum ratio of useful signal to background. Report given at the Fifth International Scientific and Technical Conference on Quantum Electronics, 22–25 November 2004, Minsk, Belarus. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 270–272, March–April, 2006.     

Multidimensional Pattern Recognition and Classification of White Blood Cells Using Support Vector Machines

This study introduces a new algorithm to optimize the pattern recognition of different white blood cell types in flow cytometry. The behavior of parametric data clusters in a multidimensional space is analyzed using the learning system known as Support Vector Machines (SVM). Beckman‐Coulter Corporation supplied flow cytometry data of numerous patients to be used as training and testing sets for the algorithm. Subsequently, the characteristics of the cells provided in these sets were used to train a SVM based classifier. The objective in developing this algorithm was to identify the category of a given blood sample and provide information to medical doctors in the form of diagnostic references for a specific disease state, lymphocytic leukemia. With the application of the hypothesis space, the learning bias and the learning algorithm, the SVM classifier was successfully trained to evaluate misclassification ratios in flow cytometry data in an effort to recognize abnormal blood cell patterns and address the ubiquitous problem of data overlap through the use of the maximal margin classifier.     

激光生物热作用的一维瞬态温度分布规律研究

采用数学物理方程的定解求法解一维热传导偏微分方程 ;讨论结果的物理意义 ,与相关实验作对比分析。结果表明 ,激光热源在一维生物组织空间引起的温升一般随时间呈指数形式增大 ;随激光照射处的距离呈指数形式减少。     

Displacement wave of the blood vessel —A mechanical model

According to clinical observations and model experiment, we have developed a theoretical model and obtained its mathematical equations to investigate the displacement wave of the blood vessel. The waveform and its occurrence criterion have been obtained by using perturbation theory and numerical method. The present study suggests that the displacement wave is associated with the blood velocity waveform and the machanical behaviour of the blood vessel, but not with the pressure waveform. The clinical criterion is in agreement with the observations.