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Multidrug resistance (MDR) against chemotherapeutic agents has become one of the major obstacles to successful cancer therapy and MDR-associated proteins (MRPs)-mediated drug efflux is the key factor for MDR. In this study, a redox-responsive polymer based on dextran (DEX) and indomethacin (IND), which could reduce MRPs-mediated efflux of chemotherapeutics, was synthesized, and the obtained polymer could spontaneously form stable micelles with well-defined core-shell structure and a uniform size distribution with an average diameter of 50 nm and effectively encapsulate doxorubicin (DOX); the micelles contain a disulfide bridge (cystamine, SS) between IND and DEX (DEX-SS-IND). In vitro drug release results indicated that DEX-SS-IND/DOX micelles could maintain good stability in a stimulated normal physiological environment and promptly depolymerized and released DOX in a reducing environment. After incubating DEX-SS-IND/DOX micelles with drug-resistant tumor (MCF-7/ADR) cells, the intracellular accumulation and retention of DOX were significantly increased under the synergistic effects of redox-responsive delivery and the inhibitory effect of IND on MRPs. In vitro cytotoxicity showed that DEX-SS-IND/DOX micelles exhibited higher cytotoxicity against MCF-7/ADR cells. Moreover, DEX-SS-IND/DOX micelles showed significantly enhanced inhibition of tumor in BALB/c nude mice bearing MCF-7/ADR tumors and reduced systemic toxicity. Overall, the cumulative evidence indicates that DEX-SS-IND/DOX micelles hold significant promise for overcoming MDR for cancer therapy.

Literature about healthcare-associated infection (HCAI) in China is scarce. A cross-sectional anonymous survey was conducted on 647 clinicians (199 physicians and 448 nurses) from six Shanghai hospitals (grades A–C) to investigate their cognizance, knowledge, attitude, self-reported practice, and risks regarding HCAI with emphasis on precautions. The mean overall score of HCAI knowledge was 40.89±11.4 (mean±SD; range, 13∼72) out of 100 for physicians and 43.48±9.9 (10∼70) for nurses. The respondents generally received high scores in hand hygiene, HCAI core concept, and healthcare worker safety but low scores in HCAI pathogen identification and isolation precautions. There were substantial variations in the knowledge scores of various demographic groups across individual hospitals and within hospital grades (ps<0.05). Within-hospital comparisons showed that the nurses were better than physicians particularly in hand hygiene knowledge in 4 hospitals (ps<0.05). Multiple linear regression analysis showed that longer work experience was inversely and independently associated with the overall and categorical knowledge of nurses, whereas independent associations between older age or higher education and categorical knowledge were noted for physicians. The respondents' self-reported practices and adherence to standard precautions were less than satisfactory. This multi-center study reports a high level of cognizance, patchy knowledge, suboptimal adherence to infection control precautions, and self-protective attitudes among the practicing clinicians regarding HCAI, with potential safety risk to patients and healthcare providers. Providing quality learning resources, enforcing knowledge-informed practice, and promoting a healthcare safety culture are recommended as interventions. Future studies are warranted for social and behavioral aspects of healthcare safety with emphasis on infection control.

Dendrobine, considered as the major active alkaloid compound, has been used for the quality control and discrimination of Dendrobium which is documented in the Chinese Pharmacopoeia. In this work, a sensitive and simple ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for determination of dendrobine in rat plasma is developed. After addition of caulophyline as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 (2.1 ×100 mm, 1.7 µm) column with acetonitrile and 0.1% formic acid as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring mode was used for quantification using target fragment ions m/z 264.2 → 70.0 for dendrobine and m/z 205.1 → 58.0 for IS. Calibration plots were linear throughout the range 2-1000 ng/mL for dendrobine in rat plasma. The RSDs of intra-day and inter-day precision were both <13%. The accuracy of the method was between 95.4 and 103.9%. The method was successfully applied to pharmacokinetic study of dendrobine after intravenous administration. Copyright © 2015 John Wiley & Sons, Ltd.

A specific ultra-performance liquid chromatography tandem mass spectrometry method is described for the simultaneous determination of bupropion, metroprolol, midazolam, phenacetin, omeprazole and tolbutamide in rat plasma with diazepam as internal standard, which are the six probe drugs of the six cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19 and CYP2C9. Plasma samples were protein precipitated with acetonitrile. The chromatographic separation was achieved using a UPLC® BEH C18 column (2.1 × 100 mm, 1.7 µm). The mobile phase consisted of acetonitrile and water (containing 0.1% formic acid) with gradient elution. The triple quadrupole mass spectrometric detection was operated by multiple reaction monitoring in positive electrospray ionization. The precisions were <13%, and the accuracy ranged from 93.3 to 110.4%. The extraction efficiency was >90.5%, and the matrix effects ranged from 84.3 to 114.2%. The calibration curves in plasma were linear in the range of 2-2000 ng/mL, with correlation coefficient (r(2) ) >0.995. The method was successfully applied to pharmacokinetic studies of the six probe drugs of the six CYP450 isoforms and used to evaluate the effects of erlotinib on the activities of CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19 and CYP2C9 in rats. Erlotinib may inhibit the activity of CYP2B6 and CYP3A4, and may induce CYP2C9 of rats.

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