细菌感染成像的研究进展

由致病菌或条件致病菌侵入机体繁殖而产生的毒素和其它代谢产物所引起的感染性疾病是目前全球范围内的主要死亡原因之一. 感染性疾病的早期诊断是对其进行有效治疗与控制的重要途径. 分子影像技术的快速发展给体内细菌感染的评估带来了前所未有的变化和机遇. 本文综合评述了计算机断层扫描、 正电子发射断层扫描、 超声成像、 磁共振成像、 荧光成像及光声成像等成像方式在细菌感染体内成像中的研究进展、 不足和发展方向等, 以期为活体细菌感染检测方法的发展提供参考.     

Rapid Preparation of Mesoporous Methylsilsesquioxane Aerogels by Microwave Heating Technology

Microwave heating technology is known as an alternative to traditional gas and electric heating sources. In this work, mesoporous methylsilsesquioxane (MSQ) aerogels were prepared via a sol–gel process accompanied by microwave heating technology, and microwave heating was used in the gelation of sol and the drying of wet gels, respectively. The effects of hexadecyltrimethylammonium chloride (CTAC) as a surfactant and template, hydrochloric acid (HCl) as a catalyst, ethanol as a solvent, sodium hydroxide (NaOH) as a gelation agent, and microwave power on the pore structure of as-prepared MSQ aerogels were investigated in detail. Microwave heating at low power results in the acceleration of sol–gel transition and achieves the gelation within a few minutes. Appropriate amounts of chemical reagents and microwave heating at high power allow the preparation of mesoporous MSQ aerogels with a BET-specific surface area of 681.6 m²·g⁻¹ and a mesopore size of 19 nm, and the resultant MSQ aerogel still has a BET specific surface area as high as 134 m²·g⁻¹ after heat treatment at 600 °C for 2 h, showing high thermal stability. The MSQ aerogels/fibre composite possesses a low thermal conductivity of 0.039 W/(m·k)⁻¹, displaying good thermal insulation. Microwave heating technology is a promising heating method for the preparation of other aerogels.     

化学反应-顶空气相色谱法测定气相二氧化硅表面硅羟基

建立了一种基于化学反应-顶空气相色谱测定气相二氧化硅表面硅羟基含量的新方法。实验取气相二氧化硅放入顶空瓶中于105 ℃烘箱中加热2 h去除水分,将甲苯稀释的格氏试剂注入密闭的顶空瓶中,格氏试剂与气相二氧化硅表面硅羟基快速反应产生甲烷(CH₄),甲烷量与气相二氧化硅表面硅羟基含量成正比。经过气相色谱-氢火焰离子化检测器测定甲烷,通过外标法定量,根据化学反应方程式计算出样品中羟基含量。同时对反应溶液用量与反应时间等条件进行优化,确定2.0 mL反应溶液,反应15 min为最优的前处理条件。结果表明,硅羟基含量与气相色谱信号值之间存在良好的线性相关性,相关系数为0.9990,相对标准偏差小于3%,本方法的检出限为0.30 mg/g,定量限为1.00 mg/g,开展了4家实验室对5个不同比表面积的样品测试,数据结果的重复性限(r)小于2.5%,再现性限(R)小于6.5%。该方法结合自动化技术,顶空反应操作简单,样品量和试剂用量少,准确性高,重复性好,优于酸碱滴定法,适用于快速检测气相二氧化硅表面硅羟基的含量,解决了硅羟基利用传统方法难以准确测定的难题。该方法的建立对我国二氧化硅产业硅羟基检测标准的制定和产业技术优化,均具有重要的理论和现实意义。     

Implications of Nitrogen Doping on Geometrical and Electronic Structure of the Fullerene Dimers

Because of its unsaturated bonds, C₆₀ is susceptible to polymerize into dimers. The implications of nitrogen doping on the geometrical and electronic structure of C₆₀ dimers have been ambiguous for years. A quarter‐century after the discovery of azafullerene dimer (C₅₉N)₂, we reported its single crystallographic structure in 2019. Herein, the unambiguous crystal structure information of (C₅₉N)₂ is elucidated specifically, revealing that the inter‐cage C—C single bond length of (C₅₉N)₂ is comparable with that of an ordinary C(sp³)‐C(sp³) single bond, and that the most stable conformer of (C₅₉N)₂ is gauche‐conformer with a dihedral angle of 66°. To amend the structural deviations, geometrical structure of (C₅₉N)₂ is optimized by a B3LYP‐D3BJ function, which is proved to be more consistent with its single crystal structure than those by the commonly used B3LYP function. Moreover, the calculation method is also suitable for other representative fullerene dimers, such as (C₆₀)₂ and its divalent anion. Additionally, the dissociation of (C₅₉N)₂ at 473 K under mass spectrometric conditions suggests the inter‐cage C—C bond is relatively weaker than an ordinary C—C single bond, which can be explained by the interaction energies of inter‐cages.     

低浓度含铅细颗粒物暴露大鼠体内生物转运研究

食品接触性塑料制品、可再生资源、汽车尾气中含有低浓度铅。铅等重金属体内蓄积严重影响机体健康,但机体长期暴露于铅环境的代谢依然未知。以低剂量含铅细颗粒物暴露为场景,探讨其在大鼠体内的生物转运及体内分布。通过比较每日吸入染毒(7.05±0.83)μg/m~3及经口染毒0.42μg/d,连续染毒28d。结果显示含铅细颗粒物入血的速度比经口途径快,在肺内蓄积浓度达(4.2±0.67)μg/g,与经口染毒组比较有显著统计学差异(P0.01);排泄方面,吸入含铅细颗粒物以粪便、尿液形式排出为主,与经口染毒组比较具有体内蓄积量大、排泄慢、在股骨和肋骨内蓄积量大的特点。因此,吸入含铅细颗粒物暴露体内蓄积量大,代谢速度慢,暴露危害比经口途径更大。     

Garcinielliptone G from Garcinia subelliptica Induces Apoptosis in Acute Leukemia Cells

Cytotoxicity and apoptosis-inducing properties of compounds isolated from Garcinia subelliptica leaves were investigated. The hexane-soluble portion of MeOH extracts of G. subelliptica leaves that showed cytotoxic activity was separated to yield seven compounds 1–7. Chemical structure analysis using NMR spectroscopy and mass spectrometry confirmed that compound 1 was canophyllol, and compounds 2–7 were garcinielliptones N, O, J, G, F, and garcinielliptin oxide, respectively. Among them, garcinielliptone G (5) showed growth inhibition by causing apoptosis in THP-1 and Jurkat cells derived from human acute monocytic leukemia and T lymphocyte cells, respectively. Apoptosis induced by garcinielliptone G (5) was demonstrated by the detection of early apoptotic cells with fluorescein-labeled Annexin V and increases in cleaved caspase-3 and cleaved PARP protein levels. However, the addition of caspase inhibitor Z-VAD-FMK did not affect growth arrest or apoptosis induction. These results suggest that garcinielliptone G (5) can induce both caspase-3 activation and caspase-independent apoptosis. Therefore, garcinielliptone G (5) may be a potential candidate for acute leukemia treatment.     

Prediction of African Swine Fever Virus Inhibitors by Molecular Docking-Driven Machine Learning Models

African swine fever virus (ASFV) causes a highly contagious and severe hemorrhagic viral disease with high mortality in domestic pigs of all ages. Although the virus is harmless to humans, the ongoing ASFV epidemic could have severe economic consequences for global food security. Recent studies have found a few antiviral agents that can inhibit ASFV infections. However, currently, there are no vaccines or antiviral drugs. Hence, there is an urgent need to identify new drugs to treat ASFV. Based on the structural information data on the targets of ASFV, we used molecular docking and machine learning models to identify novel antiviral agents. We confirmed that compounds with high affinity present in the region of interest belonged to subsets in the chemical space using principal component analysis and k-means clustering in molecular docking studies of FDA-approved drugs. These methods predicted pentagastrin as a potential antiviral drug against ASFVs. Finally, it was also observed that the compound had an inhibitory effect on AsfvPolX activity. Results from the present study suggest that molecular docking and machine learning models can play an important role in identifying potential antiviral drugs against ASFVs.     

Saffron Pre-Treatment Promotes Reduction in Tissue Inflammatory Profiles and Alters Microbiome Composition in Experimental Colitis Mice

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract with an incompletely understood pathogenesis. Long-standing colitis is associated with increased risk of colon cancer. Despite the availability of various anti-inflammatory and immunomodulatory drugs, many patients fail to respond to pharmacologic therapy and some experience drug-induced adverse events. Dietary supplements, particularly saffron (Crocus sativus), have recently gained an appreciable attention in alleviating some symptoms of digestive diseases. In our study, we investigated whether saffron may have a prophylactic effect in a murine colitis model. Saffron pre-treatment improved the gross and histopathological characteristics of the colonic mucosa in murine experimental colitis. Treatment with saffron showed a significant amelioration of colitis when compared to the vehicle-treated mice group. Saffron treatment significantly decreased secretion of serotonin and pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, in the colon tissues by suppressing the nuclear translocation of NF-κB. The gut microbiome analysis revealed distinct clusters in the saffron-treated and untreated mice in dextran sulfate sodium (DSS)-induced colitis by visualization of the Bray–Curtis diversity by principal coordinates analysis (PCoA). Furthermore, we observed that, at the operational taxonomic unit (OTU) level, Cyanobacteria were depleted, while short-chain fatty acids (SCFAs), such as isobutyric acid, acetic acid, and propionic acid, were increased in saffron-treated mice. Our data suggest that pre-treatment with saffron inhibits DSS-induced pro-inflammatory cytokine secretion, modulates gut microbiota composition, prevents the depletion of SCFAs, and reduces the susceptibility to colitis.     

Novel sponge-like molecularly imprinted mesoporous silica material for selective isolation of bisphenol A and its analogues from sediment extracts

Bisphenol A (BPA) imprinted sponge mesoporous silica was synthesized using a combination of semi-covalent molecular imprinting and simple self-assembly process. The molecularly imprinted sponge mesoporous silica (MISMS) material obtained was characterized by FT-IR, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption measurements. The results show that the MISMS possessed a large specific surface area (850.55 m² g⁻¹) and a highly interconnected 3-D porous network. As a result, the MISMS demonstrated a superior specific adsorption capacity of 169.22 μmol g⁻¹ and fast adsorption kinetics (reaching equilibrium within 3 min) for BPA. Good class selectivity for BPA and its analogues (bisphenol F, bisphenol B, bisphenol E and bisphenol AF) was also demonstrated by the sorption experiment. The MISMS as solid-phase extraction (SPE) material was then evaluated for isolation and clean-up of these bisphenols (BPs) from sediment samples. An accurate and sensitive analytical method based on the MISMS–SPE coupled with HPLC–DAD has been successfully established for simultaneous determination of five BPs in river sediments with detection limits of 0.43–0.71 ng g⁻¹ dry weight (dw). The recoveries of BPs for lyophilizated sediment samples at two spiking levels (50 and 500 ng g⁻¹ dw for each BP) were in the range of 75.5–105.5% with RSD values below 7.5%.