Three new flavans in dragon's blood from Daemonorops draco

Three new flavans were isolated from chloroform extracts of dragon's blood from Daemonorops draco, together with eight known compounds. The structures of the new flavans were determined by 1D and 2D NMR spectroscopic analysis. These compounds are the first examples of 2-methoxyflavans from D. draco and regarded as derivatives of biogenetic intermediates from flavans to chalcones, which are characteristic of the dragon's blood.     

Mathematical modelling of the patent ductus arteriosus (PDA)

The heart is one of the most important and vital body organs, which is responsible for pumping blood to different body tissues. Abnormalities in each part of heart can lead to lack of proper blood circulation. The arterial duct is one of the most important parts of embryonic cycles which may provide the possibility of a relationship between the aorta and the pulmonary artery. The failure of this duct to close after birth causes the abnormality called patent ductus arteriosus (PDA). In this article, we propose a novel model for accurate simulation of PDA abnormality in the human heart. The model is obtained by exploiting the mathematical relation between hemodynamic parameters of heart, including pressure, blood, volume and flow. The proposed model is verified using clinical data.     

Automated high throughput analysis of antiretroviral drugs in dried blood spots

For therapeutic drug monitoring in remote settings, dried blood spots (DBS) are particularly advantageous, as blood sample collection and handling is uncomplicated. The aim of this study was to develop and validate an automated extraction method for the analysis of nevirapine, efavirenz and lopinavir in DBS samples. Automated extraction was performed with methanol : water (70 : 30 v /v ), using a DBS‐MS 500 autosampler coupled to a liquid chromatography tandem mass spectrometry system. The autosampler used digital images of each DBS to position the extraction head, sprayed 10 μl of internal standard onto each DBS and extracted a 4‐mm disc (Ø) from the centre of each spot by unilateral flow using 25‐μl extraction solvent. The analytes were baseline separated on a pentafluorophenyl column and analysed by using electrospray ionization with multiple reaction monitoring in positive polarity mode for nevirapine and lopinavir and in negative mode for efavirenz. The method was linear between 10 and 10 000 ng/ml for all analytes. Automated sample extraction resulted in consistent recoveries (nevirapine: 70 ± 6%, efavirenz: 63 ± 11% and lopinavir: 60 ± 10%) and matrix effects between different donors and concentration levels. Intra‐day and inter‐day accuracy and precision deviations were ≤15%. Manual and automated extractions of DBS samples collected within the framework of an adherence assessment study in rural Tanzania showed good agreements with deviations of less than 10%. Our study highlights that therapeutic drug monitoring samples obtained in the resource‐constrained setting of rural Africa can be reliably determined by automated extraction of DBS. Overall, automatization improved method sensitivity and facilitates analysis of large sample numbers. Copyright © 2017 John Wiley & Sons, Ltd.     

On the Preparation and Distribution of two S35-Labelled Hypoglycemic Agents

Two S³⁵-labelled hypoglycemic agents were prepared by the interaction of labelled sulphonamide and urea derivatives. The R values of the intermediates as well as the products wer determined and compared with tolbutamide. The purity of the products was checked by melting point determination, infrared spectrum, and radioactivity investigations. Localization of the separated products on the chromatograms was done by colour reaction, radioscaning, and radioautography. Distribution of the labelled drung in different tissues of rats was also carried out to prove the site of action of the drung and to show its accumulation. Counting of these tissues has been carried out by means of a liquid scintillation counter type Nuclear Chicago.     

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.