Bioactivation and reactivity research advances - 2023 year in review.

Advances in the field of bioactivation have significantly contributed to our understanding and prediction of drug-induced liver injury (DILI). It has been established that many adverse drug reactions, including DILI, are associated with the formation and reactivity of metabolites. Modern methods allow us to detect and characterize these reactive metabolites in earlier stages of drug development, which helps anticipate and circumvent the potential for DILI. Improved in silico models and experimental techniques that better reflect in vivo environments are enhancing predictive capabilities for DILI risk. Further, studies on the mechanisms of bioactivation, including enzyme interactions and the role of individual genetic differences, have provided valuable insights for drug optimizations. Cumulatively, this progress is continually refining our approaches to drug safety evaluation and personalized medicine.

Unraveling the Heat- and UV-Induced Degradation of Mixed Halide Perovskite Thin Films via Surface Analysis Techniques.

In recent years, organic-inorganic hybrid perovskite materials have become one of the most promising materials in the new generation of solar cells. These perovskites can provide excellent photoelectric properties after a simple fabrication process. Although perovskite solar cells have achieved high power conversion efficiency, instability concerns regarding material exposure to heat, moisture, air, and UV light present hindrances to commercialization. In this study, three kinds of perovskites (MAPbI3, MAPbI3-xBrx, and MAPbI3-xClx) were used to investigate the crystal stability upon exposure to heat and UV light. SEM, XRD, and FTIR were used to observe the surface morphology, crystal structure, and functional groups of the perovskite thin films. XPS was used to examine the surface composition and chemical state of the perovskite thin films under different conditions. Among these three types of perovskites, it was found that the MAPbI3-xBrx crystal demonstrated the best stability. ToF-SIMS was used to confirm the molecular distribution of the MAPbI3-xBrx films upon exposure to heat and UV light at different depths. ToF-SIMS revealed that [Pb]+ and [PbI]+ aggregated at the interface between the perovskite and ITO substrate after 14 days of thermal treatment. On the other hand, [Pb]+ and [PbI]+ were distributed uniformly after 3 days of UV exposure. This study systematically analyzed and revealed the thermal- and UV-induced degradation process of three perovskite films by using surface analysis techniques. It was concluded that bromine-doped perovskite films had better stability, and UV light caused more severe damage than heat.

Diazobutanone-assisted isobaric labelling of phospholipids and sulfated glycolipids enables multiplexed quantitative lipidomics using tandem mass spectrometry.

Mass spectrometry-based quantitative lipidomics is an emerging field aiming to uncover the intricate relationships between lipidomes and disease development. However, quantifying lipidomes comprehensively in a high-throughput manner remains challenging owing to the diverse lipid structures. Here we propose a diazobutanone-assisted isobaric labelling strategy as a rapid and robust platform for multiplexed quantitative lipidomics across a broad range of lipid classes, including various phospholipids and glycolipids. The diazobutanone reagent is designed to conjugate with phosphodiester or sulfate groups, while accommodating various functional groups on different lipid classes, enabling subsequent isobaric labelling for high-throughput multiplexed quantitation. Our method demonstrates excellent performance in terms of labelling efficiency, detection sensitivity, quantitative accuracy and broad applicability to various biological samples. Finally, we performed a six-plex quantification analysis of lipid extracts from lean and obese mouse livers. In total, we identified and quantified 246 phospholipids in a high-throughput manner, revealing lipidomic changes that may be associated with obesity in mice.

Allosteric modulation and G-protein selectivity of the Ca2+-sensing receptor.

The calcium-sensing receptor (CaSR) is a family C G-protein-coupled receptor1 (GPCR) that has a central role in regulating systemic calcium homeostasis2,3. Here we use cryo-electron microscopy and functional assays to investigate the activation of human CaSR embedded in lipid nanodiscs and its coupling to functional Gi versus Gq proteins in the presence and absence of the calcimimetic drug cinacalcet. High-resolution structures show that both Gi and Gq drive additional conformational changes in the activated CaSR dimer to stabilize a more extensive asymmetric interface of the seven-transmembrane domain (7TM) that involves key protein-lipid interactions. Selective Gi and Gq coupling by the receptor is achieved through substantial rearrangements of intracellular loop 2 and the C terminus, which contribute differentially towards the binding of the two G-protein subtypes, resulting in distinct CaSR-G-protein interfaces. The structures also reveal that natural polyamines target multiple sites on CaSR to enhance receptor activation by zipping negatively charged regions between two protomers. Furthermore, we find that the amino acid L-tryptophan, a well-known ligand of CaSR extracellular domains, occupies the 7TM bundle of the G-protein-coupled protomer at the same location as cinacalcet and other allosteric modulators. Together, these results provide a framework for G-protein activation and selectivity by CaSR, as well as its allosteric modulation by endogenous and exogenous ligands.

Wall-mounted folding chairs to promote resident physician sitting at the hospital bedside.

BACKGROUND: Sitting at the bedside may improve patient-clinician communication; however, many clinicians do not regularly sit during inpatient encounters. OBJECTIVE: To determine the impact of adding wall-mounted folding chairs inside patient rooms, beyond any impact from a resident education campaign, on the patient-reported frequency of sitting at the bedside by internal medicine resident physicians. DESIGN, SETTING, AND PARTICIPANTS: Prospective, controlled pre-post trial between 2019 and 2022 (data collection paused 2020-2021 due to COVID-19) at an academic hospital in Baltimore, Maryland. Folding chairs were installed in two of four internal medicine units and educational activities were delivered equally across all units. MAIN OUTCOME AND MEASURES: Patient-reported frequency of sitting at bedside, assessed as means on Likert-type items with 1 being "never" and 5 being "every single time." We also examined the frequency of other patient-reported communication behaviors. RESULTS: Two hundred fifty six and 206 patients enrolled in the pre and post-intervention periods, respectively. The mean frequency of patient-reported sitting by resident physicians increased from 1.8 (SD 1.2) to 2.3 (1.2) on education-only units (absolute difference 0.48 [95% CI: 0.21-0.75]) and from 2.0 (1.3) to 3.2 (1.4) on units receiving chairs (1.16, [0.87-1.45]). Comparing differences between groups using ordered logistic regression adjusting for clustering within residents, units with added chairs had greater increases in sitting (odds ratio 2.05 [1.10-3.82]), spending enough time at the bedside (2.43 [1.32-4.49]), and checking for understanding (3.04 [1.44-6.39]). Improvements in sitting and other behaviors were sustained on both types of units. CONCLUSIONS: Adding wall-mounted folding chairs may help promote effective patient-clinician communication.

A New Reaction Mode of 3-Halooxindoles: Acting as C-C-O Three-Atom Components for (3+3) Cycloaddition to Access Indolenine-Fused 2H-1,4-Oxathiines.

Herein, we report an unprecedented implementation of 3-halooxindoles as C-C-O three-atom components for (3+3) cycloaddition with pyridinium 1,4-zwitterionic thiolates, affording structurally diverse indolenine-fused 2H-1,4-oxathiines in moderate to high yields. A combined experimental and computational mechanistic study suggests that the reaction proceeds through addition of a S conjugate to the o-azaxylylene intermediate, followed by O-Michael addition and a sequential retro-Michael addition/pyridine extrusion pathway.

CHRISTMAS: Chiral Pair Isobaric Labeling Strategy for Multiplexed Absolute Quantitation of Enantiomeric Amino Acids.

Amino acids (AAs) in the d-form are involved in multiple pivotal neurological processes, although their l-enantiomers are most commonly found. Mass spectrometry-based analysis of low-abundance d-AAs has been hindered by challenging enantiomeric separation from l-AAs, low sensitivity for detection, and lack of suitable internal standards for accurate quantification. To address these critical gaps, N,N-dimethyl-l-leucine (l-DiLeu) tags are first validated as novel chiral derivatization reagents for chromatographic separation of 20 pairs of d/l-AAs, allowing the construction of a 4-plex isobaric labeling strategy for enantiomer-resolved quantification through single step tagging. Additionally, the creative design of N,N-dimethyl-d-leucine (d-DiLeu) reagents offers an alternative approach to generate analytically equivalent internal references of d-AAs using d-DiLeu-labeled l-AAs. By labeling cost-effective l-AA standards using paired d- and l-DiLeu, this approach not only enables absolute quantitation of both d-AAs and l-AAs from complex biological matrices with enhanced precision but also significantly boosts the combined signal intensities from all isobaric channels, greatly improving the detection and quantitation of low-abundance AAs, particularly d-AAs. We term this quantitative strategy CHRISTMAS, which stands for chiral pair isobaric labeling strategy for multiplexed absolute quantitation. Leveraging the ion mobility collision cross section (CCS) alignment, interferences from coeluting isomers/isobars are effectively filtered out to provide improved quantitative accuracy. From wild-type and Alzheimer's disease (AD) mouse brains, we successfully quantified 20 l-AAs and 5 d-AAs. The significant presence and differential trends of certain d-AAs compared to those of their l-counterparts provide valuable insights into the involvement of d-AAs in aging, AD progression, and neurodegeneration.

Cysteine Counting via Isotopic Chemical Labeling for Intact Mass Proteoform Identifications in Tissue.

Top-down proteomics, the tandem mass spectrometric analysis of intact proteoforms, is the dominant method for proteoform characterization in complex mixtures. While this strategy produces detailed molecular information, it also requires extensive instrument time per mass spectrum obtained and thus compromises the depth of proteoform coverage that is accessible on liquid chromatography time scales. Such a top-down analysis is necessary for making original proteoform identifications, but once a proteoform has been confidently identified, the extensive characterization it provides may no longer be required for a subsequent identification of the same proteoform. We present a strategy to identify proteoforms in tissue samples on the basis of the combination of an intact mass determination with a measured count of the number of cysteine residues present in each proteoform. We developed and characterized a cysteine tagging chemistry suitable for the efficient and specific labeling of cysteine residues within intact proteoforms and for providing a count of the cysteine amino acids present. On simple protein mixtures, the tagging chemistry yields greater than 98% labeling of all cysteine residues, with a labeling specificity of greater than 95%. Similar results are observed on more complex samples. In a proof-of-principle study, proteoforms present in a human prostate tumor biopsy were characterized. Observed proteoforms, each characterized by an intact mass and a cysteine count, were grouped into proteoform families (groups of proteoforms originating from the same gene). We observed 2190 unique experimental proteoforms, 703 of which were grouped into 275 proteoform families.

Cotton Ti-IMAC: Developing Phosphorylated Cotton as a Novel Platform for Phosphopeptide Enrichment.

Protein phosphorylation is an important post-translational modification (PTM), which is involved in many important cellular functions. Understanding protein phosphorylation at the molecular level is critical to deciphering its relevant biological processes and signaling networks. Mass spectrometry (MS) has become a powerful tool for the comprehensive profiling of protein phosphorylation. Yet the low ionization efficiency and low abundance of phosphopeptides among complex biological samples make its MS analysis challenging; an enrichment strategy with high efficiency and selectivity is always necessary prior to MS analysis. In this study, we developed a phosphorylated cotton-fiber-based Ti(IV)-IMAC material (termed as Cotton Ti-IMAC) that can serve as a novel platform for phosphopeptide enrichment. The cotton fiber can be effectively grafted with phosphate groups covalently in a single step, where the titanium ions can then be immobilized to enable capturing phosphopeptides. The material can be prepared using cost-effective reagents within only 4 h. Benefiting from the flexibility and filterability of cotton fibers, the material can be easily packed as a spin-tip and make the enrichment process convenient. Cotton Ti-IMAC successfully enriched phosphopeptides from protein standard digests and exhibited a high selectivity (BSA/ß-casein = 1000:1) and excellent sensitivity (0.1 fmol/µL). Moreover, 2354 phosphopeptides were profiled in one LC-MS/MS injection after enriching from only 100 µg of HeLa cell digests with an enrichment specificity of up to 97.51%. Taken together, we believe that Cotton Ti-IMAC can serve as a widely applicable and robust platform for achieving large-scale phosphopeptide enrichment and expanding our knowledge of phosphoproteomics in complex biological systems.

Impact of COVID-19 prevention and control on tuberculosis and scarlet fever in China's Guizhou.

China has implemented a series of long-term measures to control the spread of COVID-19, however, the effects of these measures on other chronic and acute respiratory infectious diseases remain unclear. Tuberculosis (TB) and scarlet fever (SF) serve as representatives of chronic and acute respiratory infectious diseases, respectively. In China's Guizhou province, an area with a high prevalence of TB and SF, approximately 40,000 TB cases and hundreds of SF cases are reported annually. To assess the impact of COVID-19 prevention and control on TB and SF in Guizhou, the exponential smoothing method was employed to establish a prediction model for analyzing the influence of COVID-19 prevention and control on the number of TB and SF cases. Additionally, spatial aggregation analysis was utilized to describe spatial changes in TB and SF before and after the COVID-19 outbreak. The parameters of the TB and SF prediction models are R2 = 0.856, BIC = 10.972 and R2 = 0.714, BIC = 5.325, respectively. TB and SF cases declined rapidly at the onset of COVID-19 prevention and control measures, with the number of SF cases decreasing for about 3-6 months and the number of TB cases remaining in decline for 7 months after the 11th month. The spatial aggregation of TB and SF did not change significantly before and after the COVID-19 outbreak but exhibited a marked decrease. These findings suggest that China's COVID-19 prevention and control measures also reduced the prevalence of TB and SF in Guizhou. These measures may have a long-term positive impact on TB, but a short-term effect on SF. Areas with high TB prevalence may continue to experience a decline due to the implementation of COVID-19 preventive measures in the future.

Epidemiological characteristics of pulmonary tuberculosis among students in Guizhou, China: a retrospective study from 2010 to 2020.

OBJECTIVE: We described epidemiological characteristics of pulmonary tuberculosis (PTB) among students and evaluated susceptible populations and areas in Guizhou province and also to provide scientific suggestions for prevention and control. SETTING: Guizhou, China. DESIGN: This is a retrospective epidemiological study on PTB in students. METHODS: Data are from the China Information System for Disease Control and Prevention. We collected all PTB cases among the student population from 2010 to 2020 in Guizhou. Incidence, composition ratio and hotspot analysis were used to describe epidemiological and some clinical characteristics. RESULTS: A total of 37 147 new student PTB cases were registered among the population aged 5-30 years during 2010-2020. The proportions of men and women were 53.71% and 46.29%, respectively. Cases aged 15-19 years dominated (63.91%), and the proportion of ethnic groups was increasing during the period. Generally, the raw annual incidence of PTB among the population was increasing from 32.585 per 100 000 persons in 2010 to 48.872 per 100 000 persons in 2020 (c 2 trend=1283.230, p<0.001). March and April were the peak months of a year, and cases were clearly grouped in Bijie city. New cases were mainly identified via physical examination, and cases from active screening were still low (0.76%). Additionally, secondary PTB accounted for 93.68%, positive rate of pathogen was only 23.06%, and the recovery rate was 94.60%. CONCLUSIONS: The population aged 15-19 years is the vulnerable population, and Bijie city is the susceptible area. BCG vaccination and promotion for active screening should be the priority of futural PTB prevention and control. Tuberculosis laboratory capacity should be improved.

Combined disruption of T cell inflammatory regulators Regnase-1 and Roquin-1 enhances antitumor activity of engineered human T cells.

A fundamental limitation of T cell therapies in solid tumors is loss of inflammatory effector functions, such as cytokine production and proliferation. Here, we target a regulatory axis of T cell inflammatory responses, Regnase-1 and Roquin-1, to enhance antitumor responses in human T cells engineered with two clinical-stage immune receptors. Building on previous observations of Regnase-1 or Roquin-1 knockout in murine T cells or in human T cells for hematological malignancy models, we found that knockout of either Regnase-1 or Roquin-1 alone enhances antitumor function in solid tumor models, but that knockout of both Regnase-1 and Roquin-1 increases function further than knockout of either regulator alone. Double knockout of Regnase-1 and Roquin-1 increased resting T cell inflammatory activity and led to at least an order of magnitude greater T cell expansion and accumulation in xenograft mouse models, increased cytokine activity, and persistence. However double knockout of Regnase-1 and Roguin-1 also led to a lymphoproliferative syndrome and toxicity in some mice. These results suggest that regulators of immune inflammatory functions may be interesting targets to modulate to improve antitumor responses.

Extending Normative Data of the Paced Auditory Serial Addition Test to Account for Preliminary Psychometric Properties among Elderly Individuals in Taiwan.

OBJECTIVE: The Paced Auditory Serial Addition Test (PASAT) is widely used to assess cognitive performance in clinical settings. However, availability of normative data for Revised Version of PASAT (PASAT-R) is often constrained by sample size among elderly individuals. In this study, we sought to establish normative data for PASAT-R for elderly individuals in Taiwan. METHODS: This study recruited 166 individuals aged over 65 years stratified in accordance with the general population in terms of demographic characteristics, including age, educational level, and sex. We assessed PASAT-R test results in terms of psychometric properties. RESULTS: PASAT-R demonstrated good internal consistency and test-retest reliability. Performance on PASAT-R was correlated with performance on the criterion tests. Performance on PASAT-R was negatively correlated with age and positively correlated with educational level. This study provides normative data for PASAT-R for elderly Taiwanese individuals. CONCLUSIONS: PASAT-R is applicable to neuropsychological assessment among elderly Taiwanese individuals.

Formononetin regulates dilated cardiomyopathy-mediated heart failure in rats via HSP90/AKT cardiomyocyte apoptosis and mechanism / 西安交通大学学报(医学版)

【Objective】 To investigate the effects of formononetin (FMN) on cardiomyocyte apoptosis and HSP90/AKT in rats with dilated cardiomyopathy-mediated heart failure. 【Methods】 Echocardiography, ELISA, histological staining, and TUNEL staining were used to observe the protective effect of different doses of FMN on dilated cardiomyopathy-mediated heart failure in rats and the apoptosis of cardiomyocytes. The potential targets of formononetin on dilated cardiomyopathy-mediated heart failure were obtained from TCMSP, DisGeNet, GeneCards, and other databases, the key targets were obtained according to the protein-protein interaction (PPI) network, and the key targets were verified by molecular docking. Western blotting was used to further verify the regulatory role of key targets in the treatment of dilated cardiomyopathy-mediated heart failure with formononetin. 【Results】 Formononetin could reduce the levels of LVIDS, LVIDD, NT-pro BNP, cTn-T, CK, CK-MB, and LDH in rats with dilated cardiomyopathy-mediated heart failure, increase the levels of EF and FS, and reduce the apoptosis of cardiomyocytes. FMN had a strong binding effect on 10 key targets (AKT1, HSP90AA1, CASP3, MAPK1, MMP9, SRC, ALB, HRAS, IGF1, and EGFR) screened by network pharmacology, with HSP90AA1 and AKT1 having the strongest binding effect. Formononetin decreased the expression of HSP90, AKT and downstream CASP3 protein, but increased the expression of p-AKT in myocardial tissue. 【Conclusion】 Formononetin may inhibit the expression of HSP90, promote phosphorylation of AKT to p-AKT, and inhibit the expression of CASP3, thereby reducing the apoptosis of cardiomyocytes and improving myocardial tissue damage, so as to achieve the purpose of treating dilated cardiomyopathy-mediated heart failure.

Catalytic Enantioselective α-Allylation of Deconjugated Butenolides with Aza-π-allylpalladium 1,4-Dipoles: Access to Optically Pure 2-Piperidones Bearing an All-Carbon Quaternary Stereocenter.

A palladium-catalyzed enantioselective α-allylation of deconjugated butenolides with aza-π-allylpalladium 1,4-diploes, in situ generated from palladium-mediated decarboxylation of cyclic carbamates and amide-substituted acyclic carbonates, has been successfully developed. An array of enantioenriched 2-piperidones bearing an all-carbon quaternary stereocenter were obtained in high yields with excellent enantioselectivities (up to 99% yield and 99% ee). The utility of this method was also showcased by a large-scale reaction and synthetic transformations of the product.

Enantioselective Construction of Vicinal Quaternary-Tetrasubstituted Carbon Stereocenters by Copper-Catalyzed Decarboxylative Propargylic Substitution.

Enantioselective construction of vicinal tetrasubstituted carbon stereocenters is a formidable challenge in organic synthesis. A copper-catalyzed asymmetric decarboxylative propargylic substitution with 3-amino oxindoles as trisubstituted carbon nucleophiles and propargylic cyclic carbonates as tertiary carbon electrophiles was developed. A range of 3-amino-3,3'-disubstituted oxindoles bearing vicinal quaternary-tetrasubstituted carbon stereocenters were obtained in high yields and good to excellent stereoselectivities (up to 98% yield, >20:1 dr, and 98.5:1.5 er).

Quantitative Analysis and Structural Elucidation of Fatty Acids by Isobaric Multiplex Labeling Reagents for Carbonyl-Containing Compound (SUGAR) Tags and m-CPBA Epoxidation.

In this study, a novel analytical method was developed to investigate fatty acids (FAs) for relative quantification, carbon-carbon double-bond localization, and cis-/trans-geometry differentiation by isobaric multiplex labeling reagents for carbonyl-containing compound (SUGAR) tag conjugation and meta-chloroperoxybenzoic acid (m-CPBA) epoxidation. FAs are essential components of cells and have diverse functions in energy storage and as complex lipid constituents. It has been reported that FAs play different roles in various biological processes such as the functional development of the brain. The comprehensive characterization and quantification of FAs are crucial to further elucidate their biological roles. However, it is challenging to perform relative quantification and structural elucidation of FAs using integrated mass spectrometry (MS)-based methods. Recently, our group developed isobaric multiplex SUGAR tags for quantitative glycomics. Besides aldehyde/ketone groups on glycans, hydrazide groups also possess reactivity toward carboxylic acids on FAs. In this study, we extended SUGAR tag labeling with FAs for the quantitative analysis by liquid chromatography (LC)-MS/MS in the positive ion mode and applied this strategy for the comparative analysis of FAs hydrolyzed from oil samples. In addition, to comprehensively elucidate the structures of unsaturated FAs, epoxidation by m-CPBA was performed before SUGAR tag labeling to enable carbon-carbon double-bond localization. Moreover, the cis- and trans-geometries of carbon-carbon double bonds in multiple pairs of monounsaturated FAs could also be differentiated in higher-energy collisional dissociation (HCD)-MS/MS. This study developed a high-throughput comprehensive FA analysis platform, which could be widely applied and utilized in biological and clinical studies.

Boost-DiLeu: Enhanced Isobaric N,N-Dimethyl Leucine Tagging Strategy for a Comprehensive Quantitative Glycoproteomic Analysis.

Intact glycopeptide analysis has been of great interest because it can elucidate glycosylation site information and glycan structural composition at the same time. However, mass spectrometry (MS)-based glycoproteomic analysis is hindered by the low abundance and poor ionization efficiency of glycopeptides. Relatively large amounts of starting materials are needed for the enrichment, which makes the identification and quantification of intact glycopeptides from samples with limited quantity more challenging. To overcome these limitations, we developed an improved isobaric labeling strategy with an additional boosting channel to enhance N,N-dimethyl leucine (DiLeu) tagging-based quantitative glycoproteomic analysis, termed as Boost-DiLeu. With the integration of a one-tube sample processing workflow and high-pH fractionation, 3514 quantifiable N-glycopeptides were identified from 30 µg HeLa cell tryptic digests with reliable quantification performance. Furthermore, this strategy was applied to human cerebrospinal fluid (CSF) samples to differentiate N-glycosylation profiles between Alzheimer's disease (AD) patients and non-AD donors. The results revealed processes and pathways affected by dysregulated N-glycosylation in AD, including platelet degranulation, cell adhesion, and extracellular matrix, which highlighted the involvement of N-glycosylation aberrations in AD pathogenesis. Moreover, weighted gene coexpression network analysis (WGCNA) showed nine modules of glycopeptides, two of which were associated with the AD phenotype. Our results demonstrated the feasibility of using this strategy for in-depth glycoproteomic analysis of size-limited clinical samples. Taken together, we developed and optimized a strategy for the enhanced comprehensive quantitative intact glycopeptide analysis with DiLeu labeling, showing significant promise for identifying novel therapeutic targets or biomarkers in biological systems with a limited sample quantity.

Simultaneous multiplexed quantification and C=C localization of fatty acids with LC-MS/MS using isobaric multiplex reagents for carbonyl-containing compound (SUGAR) tags and C=C epoxidation.

Fatty acids (FAs) possess highly diverse structures and can be divided into saturated and unsaturated classes. For unsaturated FAs, both the numbers and positions of carbon-carbon double bond (C=C) determine their biological functions. Abnormal levels of FA isomers have been reported to be involved in various disease development, such as cancer. Despite numerous advances in lipidomics, simultaneous quantifying and pinpointing C=C bond positions in a high-throughput manner remains a challenge. Here we conducted epoxidation of C=C bonds of unsaturated FAs followed by the conjugation with isobaric SUGAR tags. With the assistance of LC-MS, FA isomers with the same masses were separated on the C18 column and individually subjected to MS/MS fragmentation. Upon higher-energy collisional dissociation, not only reporter ions for multiplexed quantification but also diagnostic ions for C=C localization were generated at the same time, allowing quantitative analyses of different unsaturated FA isomers in samples. The performance of this approach including epoxidation, labeling efficiencies, quantitation accuracy, and capability to pinpoint C=C bond position were evaluated. To evaluate our method, free FA extracts from healthy human serum were used to demonstrate the feasibility of this method for complex sample analysis. Finally, this method was also applied to investigate the changes of unsaturated FA isomers between heathy human and Alzheimer's disease (AD) patient serum.

Copper-Catalyzed Decarboxylative Cascade Cyclization of Propargylic Cyclic Carbonates/Carbamates with Pyridinium 1,4-Zwitterionic Thiolates to Fused Polyheterocyclic Structures.

A copper-catalyzed decarboxylative cascade cyclization of propargylic cyclic carbonates/carbamates with pyridinium 1,4-zwitterionic thiolates is developed. A range of fused polyheterocyclic compounds are obtained in moderate to good yields with excellent diastereoselectivities. Of particular note is that four new bonds (two C-C, one C-O/N, one C-S) and four new stereocenters could be efficiently embedded into the tetracyclic fused scaffolds in a single step.