Performance Evaluation of Automated Magnetic Beads Extraction Method for Extraction of Serum Fat-soluble Vitamins by LC-MS/MS Detection / 现代检验医学杂志

Objective To evaluate the performance of the automated magnetic beads extraction method for extraction of serum fat-soluble vitamins by liquid chromatography-tandem mass spectrometry(LC-MS/MS).Methods A total of 120 clinical residual serum samples were collected automated magnetic beads extraction method was applied to extract serum fat-soluble vitamins A,D2,D3,E and K.The linearity,limit of quantification,precision,accuracy,carryover and matrix effect of fat-soluble vitamins A,D2,D3,E and K were detected by LC-MS/MS.The consistency of the method and conventional extraction method was compared.Results The linear correlation coefficients for extracting fat-soluble vitamins A,D2,D3,E and K by automated magnetic beads extraction method were all greater than 0.99,and the quantitative limits for these five fat-soluble vitamins were 5,0.25,0.25,125 and 0.025 ng/ml.The intra-batch precision and inter-batch precision were 0.66%～4.83%and 0.15%～3.70%,respectively,and the average spike recovery rate was 87.05%～111.11%.The matrix effect was 95.43%～99.07%,and the difference between the mean value of the cyclic injection results of high-low value samples and the mean value of the cyclic injection results of low-low value samples was less than 3s of the mean value of the cyclic injection results of low-low value samples.The statistical analysis showed that the correlation between the results of the automated magnetic beads extraction method and the conventional extraction method was good(r＞0.99),and there was no significant bias in the detection results of the two methods.Conclusion The automated magnetic beads extraction method for extraction of fat-soluble vitamins had good detection performance,which may be expected to improve sample flux and analysis efficiency.

Central neural mechanism of increased pain sensitivity induced by nicotine abstinence / 生理学报

Nicotine is the main addictive component in cigarettes that motivates dependence on tobacco use for smokers and makes it difficult to quit through regulating a variety of neurotransmitter release and receptor activations in the brain. Even though nicotine has an analgesic effect, clinical studies demonstrated that nicotine abstinence reduces pain threshold and increases pain sensitivity in smoking individuals. The demand for opioid analgesics in nicotine abstinent patients undergoing surgery has greatly increased, which results in many side effects, such as nausea, vomiting, and respiratory depression, etc. In addition, these side effects would hinder patients' physical and psychological recovery. Therefore, identifying the neural mechanism of the increase of pain sensitivity induced by nicotine abstinence and deriving a way to cope with the increased demand for postoperative analgesics would have enormous basic and clinical implications. In this review, we first discussed different experimental pain stimuli (e.g., cold, heat, and mechanical pain)-induced pain sensitivity changes after a period of nicotine dependence/abstinence from both animal and human studies. Then, we summarized the effects of the brain neurotransmitter release (e.g., serotonin, norepinephrine, endogenous opioids, dopamine, and γ-aminobutyric acid) and their corresponding receptor activation changes after nicotine abstinence on pain sensitivity. Finally, we discussed the limits in recent studies. We proposed that more attention should be paid to human studies, especially studies among chronic pain patients, and functional magnetic resonance imaging might be a useful tool to reveal the mechanisms of abstinence-induced pain sensitivity changes. Besides, considering the influence of duration of nicotine dependence/abstinence and gender on pain sensitivity, we proposed that the effects of nicotine abstinence and individual differences (e.g., duration of abstinence from smoking, chronic/acute abstinence, and gender) on abstinence-induced pain sensitivity should be fully considered in formulating pain treatment protocols. In summary, this paper could deepen our understanding of nicotine abstinence-induced pain sensitivity changes and its underlying neural mechanism, and could also provide effective scientific theories to guide clinical pain diagnosis and treatment, which has important clinical significance.

Spinal cord magnetic resonance imaging: methods and applications / 生理学报

Spinal cord magnetic resonance imaging (MRI) is an advanced imaging technique (mainly in the cervical cord) and has been gradually used in basic scientific research such as human sensation and motor function, and clinical applications such as spinal cord injury, myelitis, and chronic pain, etc. The development of spinal cord MRI is still at the early stage compared with brain MRI and limited by the current MRI technology and data analysis methods. This review focuses on the methods and applications of spinal cord MRI technology in the basic research fields of cognitive neuroscience and clinical application. Firstly, we will introduce the imaging principle, methods, measurement standards, and applications of most commonly used multimodal spinal cord MRI techniques, including quantitative spinal cord MRI (such as structural, diffusion, spectroscopy, myelin water, magnetization transfer, and chemical exchange saturation transfer imaging, etc.) and spinal functional MRI (fMRI). Secondly, we will discuss the technical challenges and possible solutions of spinal cord MRI data processing from the three dimensions of denoising, data processing pipeline optimization, and repeatability and reliability. Finally, we will discuss the application status and development prospects of spinal cord MRI.

Synthesis and monoamine oxidase B inhibitory activities of isoquiritigenin derivatives / 中国中药杂志

Isoquiritigenin,one of the active constituents in the Chinese herb liquorice,is found to have moderate inhibitory activity against rat monoamine oxidase B(MAO-B,IC5047. 2 μmol·L-1). However,the structure-activity relationship(SAR) remains unclear until now. In an attempt to reveal the SAR of inhibition by isoquiritigenin,and to identify more potent and selective inhibitors of MAOB,a series of 13 derivatives based on the scaffold of isoquiritigenin were prepared,and their purities and structures were confirmed by UPLC,1 H-NMR,13 C-NMR and HRMS. These compounds were then evaluated for their ability to inhibit the enzymatic activity of human MAO-B. The SAR of inhibition was summarized and a potent compound C8 with high inhibitory activity(IC501. 4 μmol·L-1) and selectivity(>57 folds over MAO-A) was identified. Enzyme kinetics studies suggested that C8 acted as a competitive inhibitor. In addition,C8 showed little cytotoxicity to glial cells in vitro,which could be a promising lead compound for further study.