In vivo pharmacokinetics of and tissue distribution study of physalin B after intravenous administration in rats by liquid chromatography with tandem mass spectrometry

A rapid and sensitive liquid chromatography tandem mass spectrometry quantitative analysis method was established for the pharmacokinetics and tissue distribution study of physalin B in rat. Physalin B and physalin H (internal standard, IS) were separated on an Agilent Eclips XDB C₈ column. MS detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction monitoring mode with a positive eletrospray ionization source. The assay was validated in the concentration ranges of 22.6–22600 ng/mL for heart and lung and 4.52–4520 ng/mL for other tissues. The intra‐ and inter‐day precisions (RSD) were ≤9.23 and ≤12.51%, respectively, with accuracy (%) in the range of 88.07–113.2%. A pharmacokinetic study showed that physalin B has a long dwell time with a half‐life of 321.2 ± 29.5 min and clearance of 175.4 ± 25.7 mL/min/kg after intravenous administration. Additionally, physalin B showed a wide tissue distribution with a special higher penetration in lung. The data presented in this study could provide useful information for the further study of physalin B. Copyright © 2016 John Wiley & Sons, Ltd.     

A rapid UPLC‐MS/MS method for the determination of oleanolic acid in rat plasma and liver tissue: application to plasma and liver pharmacokinetics

A reliable high‐throughput ultra‐high performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method was developed and validated for oleanolic acid (OA) determination in rat plasma and liver tissue using glycyrrhetic acid as the internal standard (IS). Plasma and liver homogenate samples were prepared using solid‐phase extraction. Chromatographic separation was achieved on a C₁₈ column using an isocratic mobile phase system. The detection was performed by multiple reaction monitoring mode via positive electrospray ionization interface. The calibration curves showed good linearity (R² > 0.9997) within the tested concentration ranges. The lower limit of quantification for plasma and liver tissue was ≤0.75 ng/mL. The intra‐ and inter‐day precision and accuracy deviations were within ±15% in plasma and liver tissue. The mean extraction recoveries ranged from 80.8 to 87.0%. In addition, the carryover, matrix effect, stability and robustness involved in the method were also validated. The method was successfully applied to the plasma and hepatic pharmacokinetics of OA after oral administration to rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Strain-dependent internal parameters in hyperelastic biological materials

The behavior of hyperelastic energies depending on an internal parameter, which is a function of the deformation gradient, is discussed. As an example, the analysis of two models where the parameter describes the activation of a tetanized skeletal muscle tissue is presented. In those models, the activation parameter depends on the strain and it is shown the importance of considering the derivative of the parameter with respect to the strain in order to capture the proper stress–strain relations.     

Bioprinting of Collagen: Considerations,Potentials, and Applications

Collagen is the most abundant extracellular matrix protein that is widely used in tissue engineering (TE). There is little research done on printing pure collagen. To understand the bottlenecks in printing pure collagen, it is imperative to understand collagen from a bottom‐up approach. Here it is aimed to provide a comprehensive overview of collagen printing, where collagen assembly in vivo and the various sources of collagen available for TE application are first understood. Next, the current printing technologies and strategy for printing collagen‐based materials are highlighted. Considerations and key challenges faced in collagen printing are identified. Finally, the key research areas that would enhance the functionality of printed collagen are presented.     

Optimization and validation of organochlorine compounds in adipose tissue by SPE‐gas chromatography

Scientific evidence has shown an association between organochlorine compounds (OCC) exposure and human health hazards. Concerning this, OCC detection in human adipose samples has to be considered a public health priority. This study evaluated the efficacy of various solid‐phase extraction (SPE) and cleanup methods for OCC determination in human adipose tissue. Octadecylsilyl endcapped (C₁₈‐E), benzenesulfonic acid modified silica cation exchanger (SA), poly(styrene‐divinylbenzene (EN) and EN/RP₁₈ SPE sorbents were evaluated. The relative sample cleanup provided by these SPE columns was evaluated using gas chromatography with electron capture detection (GC–ECD). The C₁₈‐E columns with strong homogenization were found to provide the most effective cleanup, removing the greatest amount of interfering substance, and simultaneously ensuring good analyte recoveries higher than 70%. Recoveries > 70% with standard deviations (SD) < 15% were obtained for all compounds under the selected conditions. Method detection limits were in the 0.003–0.009 mg/kg range. The positive samples were confirmed by gas chromatography coupled with tandem mass spectrometry (GC‐MS/MS). The highest percentage found of the OCC in real samples corresponded to HCB, o,p′‐DDT and methoxychlor, which were detected in 80 and 95% of samples analyzed respectively. Copyright © 2012 John Wiley & Sons, Ltd.