Study of the metabolism on tobacco-specific N-nitrosamines in the rabbit by solid-phase extraction and liquid chromatography–tandem mass spectrometry

Metabolism of four tobacco-specific N-nitrosamines (TSNAs), N′-nitrosonornicotine (NNN), N′-nitrosoanatabine (NAT), N′-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been studied by solid-phase extraction (SPE) and liquid chromatography–tandem mass spectrometry (LC–MS–MS). 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL) was used as internal standard. SPE and LC–MS–MS was found to be a rapid, simple, sensitive, and selective method for analysis of TSNAs in rabbit serum. The relative standard deviation (R.S.D., n = 6) for analysis of 5 ng mL⁻¹ and 0.5 ng mL⁻¹ standards and of serum sample spiked with 5 ng mL⁻¹ standards of five TSNAs was 2.1–11% and recovery of 5 ng mL⁻¹ standards from serum was 100.2–112.9%. A good linear relationship was obtained between peak area ratio and concentration in the range of 0.2–100 ng mL⁻¹ for NNAL and 0.5–100 ng mL⁻¹ for other four TSNAs, with correlation coefficients (R ²) >0.99 (both linear and log–log regression). Detection limits for standards in solvent were between 0.04 and 0.10 ng mL⁻¹. Doses of TSNAs administered to rabbits via the auricular vein were 4.67 μg kg⁻¹ and 11.67 μg kg⁻¹, in accordance with the different levels in cigarettes. Metabolic curves were obtained for the four TSNAs and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of NNK; on the basis of these curves we modeled metabolic kinetic equations for these TSNAs by nonlinear curve fitting.     

A parallel chiral-achiral liquid chromatographic method for the determination of the stereoisomers of ketamine and ketamine metabolites in the plasma and urine of patients with complex regional pain syndrome

A parallel chiral/achiral LC-MS/MS assay has been developed and validated to measure the plasma and urine concentrations of the enantiomers of ketamine, (R)- and (S)-Ket, in complex regional pain syndrome (CRPS) patients receiving a 5-day continuous infusion of a sub-anesthetic dose of (R,S)-Ket. The method was also validated for the determination of the enantiomers of the Ket metabolites norketamine, (R)- and (S)-norKet and dehydronorketamine, (R)- and (S)-DHNK, as well as the diastereomeric metabolites hydroxynorketamine, (2S,6S)-/(2R,6R)-HNK and two hydroxyketamines, (2S,6S)-HKet and (2S,6R)-Hket. In this method, (R,S)-Ket, (R,S)-norKet and (R,S)-DHNK and the diastereomeric hydroxyl-metabolites were separated and quantified using a C₁₈ stationary phase and the relative enantiomeric concentrations of (R,S)-Ket, (R,S)-norKet and (R,S)-DHNK were determined using an AGP-CSP. The analysis of the results of microsomal incubations of (R)- and (S)-Ket and a plasma and urine sample from a CRPS patient indicated the presence of 10 additional compounds and glucuronides. The data from the analysis of the patient sample also demonstrated that a series of HNK metabolites were the primary metabolites in plasma and (R)- and (S)-DHNK were the major metabolites found in urine. The results suggest that norKet is the initial, but not the primary metabolite and that downstream norKet metabolites play a role in (R,S)-Ket-related pain relief in CRPS patients.     

几种浮游单细胞藻类磷代谢的初步研究

用３２ＰＯ４３－同位素稀释法研究了单种一次培养的几种浮游单细胞藻类的磷代谢．小球藻（Ｃｈｌｏｒｅｌｌａｓｐ．）和一种绿藻对ＰＯ４３－的最大吸收速率（Ｖｍａｘ）与细胞磷含量成负相关，半饱和速率常数（Ｋｓ）与藻类的种类相关．光照与黑暗对中华盒形藻（ＢｉｄｄｕｌｐｈｉａｓｉｎｅｎｓｉｓＧｒｅｖｉｌｅ）和金藻（Ｄｉｃｒａｔｅｒｉａｓｐ）ＰＯ４３－的吸收和再生代谢无明显影响，其昼夜变化是藻类细胞新陈代谢的反映；处于细胞周期Ｇ１期与Ｓ期的藻类有较高的磷吸收和再生代谢速率，而Ｇ２期与Ｍ期的磷代谢速率较低．藻类磷代谢的动力学及其昼夜变化是围绕着对营养盐磷最大程度地利用和维持藻类持续生长的机制展开的．     

金属硫蛋白研究进展

介绍了金属硫蛋白的结构、理化性质和主要功能,金属硫蛋白转录与表达,并对国内外金属硫蛋白与锌、铅、镉、钙的代谢研究,金属硫蛋白与辐射关系,肿瘤的发生、治疗及预后的一些进展进行了介绍,说明了金属硫蛋白有着广阔的应用前景。     

An Enzyme-Loaded Metal–Organic Framework-Assisted Microfluidic Platform Enables Single-Cell Metabolite Analysis

Colonization of cancer cells at secondary sites, a decisive step in tumor metastasis, is strongly dependent on the formation of metastatic microenvironments regulated by intrinsic single-cell metabolism traits. Herein, we report a single-cell microfluidic platform for high-throughput dynamic monitoring of tumor cell metabolites to evaluate tumor malignancy. This microfluidic device empowers efficient isolation of single cells (>99 %) in a squashed state similar to tumor extravasation, and employs enzyme-packaged metal–organic frameworks to catalyze tumor cell metabolites for visualization. The microfluidic evaluation was confirmed by in vivo assays, suggesting that the platform allowed predicting the tumorigenicity of captured tumor cells and screening metabolic inhibitors as anti-metastatic drugs. Furthermore, the platform efficiently detected various aggressive cancer cells in unprocessed whole blood samples with high sensitivity, showing potential for clinical application.     

The Future of (Radio)-Labeled Compounds in Research and Development within the Life Science Industry

In this review the applications of isotopically labeled compounds are discussed and put into the context of their future impact in the life sciences. Especially discussing their use in the pharma and crop science industries to follow their fate in the environment, in vivo or in complex matrices to understand the potential harm of new chemical structures and to increase the safety of human society.     

The Metabolostasis Network and the Cellular Depository of Aggregation-Prone Metabolites

The vital role of metabolites across all branches of life and their involvement in various disorders have been investigated for decades. Many metabolites are poorly soluble in water or in physiological buffers and tend to form supramolecular aggregates. On the other hand, in the cell, they should be preserved in a pool and be readily available for the execution of biochemical functions. We thus propose that a quality-control network, termed “metabolostasis”, has evolved to regulate the storage and retrieval of aggregation-prone metabolites. Such a system should control metabolite concentration, subcellular localization, supramolecular arrangement, and interaction in dynamic environments, thus enabling normal cellular physiology, healthy development, and preventing disease onset. The paradigm-shifting concept of metabolostasis calls for a reevaluation of the traditional view of metabolite storage and dynamics in physiology and pathology and proposes unprecedented directions for therapeutic targets under conditions where metabolostasis is imbalanced.     

锌的营养研究进展

本文综述了锌的代谢,锌吸收的影响因素和锌的生物学功能,为锌营养研究和应用提供参考。     

Effect of Flower Removal on Senescence and Metabolism of Faba Bean(Vicia Faba L.)

In pot experiments at Xichang,China,during 1989～1994,visual senescencesymptoms and associated changes in constituent contents and activities of leaves of fababean(Vicia faba L.)were compared in respones to flower removal.The leaves from upper,middle and lower positions were sampled six times during reproductive developmentphase.At 70 DAP flower removal had caused 37%～189% and 82%～197% increase ofgreen leaf area and green leaf dry weight per plant respectively.Flower removal led to asignificant increase in the chlorophyll,soluble sugar and protein contents and the catalaseactivity.The leaf cell relative electroconductivity of those plants was maintained at a lowerlevel,relative to the control,during the late growing stage.These results certainly impliedthat the leaves of flower removal plants were still fully functional at a very late growingstage,consequently the plants increased many new branches per plant.     

4D-proteomics-based breast cancer progressionEI北大核心CSCD

：The occurrence and development of breast cancer go through multiple processes，and the protein molecular information in its evolution is intricate and complex. The 4D-proteomics technique was used to investigate the tumor progression of MMTV-PyMT transgenic mice. The results of protein identification and differential expression analysis showed that a total of 5819 proteins were identified in 4D-proteomics analysis and 5667 proteins were quantifiable. Compared with 3-week-old tumors，a total of 270 differentially expressed proteins were found in the 5-week-old tumors，while 255 proteins in the 7-week-old tumors. We also detected 23 of proteins （such as，Srpk11 and Tinagl1）with gradual up-regulation and 35 of proteins （such as，Pdgfrb， Col1a2 and Col1a1）with gradual down-regulation during the tumor progression，including 3-，5-and 7-weeks. We also performed bioinformatics analysis，including subcellular localization，GO function analysis and pathway enrichment analysis. The results showed that the biological processes（immune regulation and lipid metabolism） and enrichment pathways （metabolic pathway）involved in differentially expressed proteins remained the same during the tumor progression，but some cellular components and molecular functions changed，such as，protein locations were extracellular region and membrane in 5-weeks-old tumors as well as cytoplasm in 7-weeks-old tumors. And important protein functions were protein binding functions in 5-weeks-old tumors as well as nucleotide binding in 7-weeks-old tumors. The acquired protein biomarkers and pathways could help with the accurate exploration of molecular mechanisms of tumor progression，screening of molecular targets of breast cancer，and evaluation of personalized treatment programs. © 2023, Youke Publishing Co.,Ltd. All rights reserved.