Vanadyl‐TrBR4‐Catalyzed Oxidative Polymerization of Diphenyl Disulfide

A newly established catalyst system for oxygen‐oxidative polymerization of diphenyl disulfide is reported. Combination of vanadyl compounds (e.g., VO(acac)₂) and triphenylmethylium tetrakis(pentafluorophenyl)borate (TrB(C₆F₅)₄) proceeds the polymerization to give poly(1,4‐phenylene sulfide) (PPS) at 100 °C. When triphenylmethylium tetrafluoroborate (TrBF₄) is applied with vanadyl tetraphenylporphyrin (VO(TPP)) or N,N′‐(ethylenebis(salicylideneaminato))oxovanadium (VO(salen)), PPS is also given via polymerization under conditions near 160 °C. Combination of the vanadyl complex and the borate affords the first protic‐acid‐free catalytic system for the polymerization of the disulfide, suggesting the overall reaction to produce PPS and H₂O from O₂ and protons that are eliminated from the monomer.

     

Gaseous mediators in resolution of inflammation

There are numerous gaseous substances that can act as signaling molecules, but the best characterized of these are nitric oxide, hydrogen sulfide and carbon monoxide. Each has been shown to play important roles in many physiological and pathophysiological processes. This article is focused on the effects of these gasotransmitters in the context of inflammation. There is considerable overlap in the actions of nitric oxide, hydrogen sulfide and carbon monoxide with respect to inflammation, and these mediators appear to act primarily as anti-inflammatory substances, promoting resolution of inflammatory processes. They also have protective and pro-healing effects in some tissues, such as the gastrointestinal tract and lung. Over the past two decades, significant progress has been made in the development of novel anti-inflammatory and cytoprotective drugs that release of one or more of these gaseous mediators.     

Toxic trace elements at gastrointestinal level

Many trace elements are considered essential [iron (Fe), zinc (Zn), copper (Cu)], whereas others may be harmful [lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As)], depending on their concentration and chemical form. In most cases, the diet is the main pathway by which they enter our organism. The presence of toxic trace elements in food has been known for a long time, and many of the food matrices that carry them have been identified. This has led to the appearance of legislation and recommendations concerning consumption. Given that the main route of exposure is oral, passage through the gastrointestinal tract plays a fundamental role in their entry into the organism, where they exert their toxic effect. Although the digestive system can be considered to be of crucial importance in their toxicity, in most cases we do not know the events that occur during the passage of these elements through the gastrointestinal tract and of ascertaining whether they may have some kind of toxic effect on it. The aim of this review is to summarize available information on this subject, concentrating on the toxic trace elements that are of greatest interest for organizations concerned with food safety and health: Pb, Cd, Hg and As.     

气体信使硫化氢在大鼠肾血管性高血压中的调节作用

目的探讨硫化氢体系在肾血管性高血压形成及发展中的变化和作用。方法成年的雄性Wistar大鼠28只,随机分为对照组7只、双肾一夹组(two-kidney,one-clip,2KIC组)7只、2KIC+硫氢化钠(硫氢化钠为外源性硫化氢供者)组8只、假手术组6只,其中2KIC+硫氢化钠组每天腹腔注射硫氢化钠(56μmol/kg),对照组、2KIC组及假手术组注射相同剂量的生理盐水。相同条件饲养4周,4周后处死,检测血浆硫化氢水平,双肾硫化氢合酶的活性,血管紧张素Ⅱ,左心与全心重量比,光学显微镜下观察肾的显微结构变化。结果术后4周,2KIC组尾动脉压显著高于假手术组及2KIC+硫氢化钠组;2KIC组的血管紧张素Ⅱ显著高于假手术组和对照组;左心室与全心重量比值2KIC组高于对照组和假手术组;肾内硫化氢合酶的活性及血浆中硫化氢的含量2KIC组显著低于假手术组及对照组,2KIC+硫氢化钠组高于2KIC组。结论肾血管性高血压大鼠硫化氢体系受到严重抑制,可能是肾性高血压形成的重要因素,外源性的给予硫化氢供者有助于缓解高血压的形成。     

硫化氢对低氧性肺动脉高压大鼠细胞因子的调节作用

目的探讨硫化氢对低氧性肺动脉高压大鼠细胞因子的调节作用。方法将Wistar大鼠22只随机分为3组。对照组(8只),低氧组(7只),低氧+硫氢化钠(NaHS)组(7只),测定3组大鼠肺动脉平均压(mPAP),观测肺血管结构变化,并用免疫组织化学方法研究α-平滑肌肌动蛋白(-αSM-actin)、弹力蛋白、转化生长因子β(TGF-β)和结缔组织生长因子(CTGF)在肺动脉平滑肌细胞的表达含量。结果低氧组的mPAP明显高于对照组和低氧+NaHS组;低氧组肌型动脉、部分肌型动脉百分比明显高于对照组和低氧+NaHS组,非肌型动脉百分比明显低于对照组和低氧+NaHS组;低氧组肺中、小型肺动脉平滑肌细胞-αSM-actin、弹力蛋白和TGF-β表达含量分别明显高于对照组和低氧+NaHS组;对照组、低氧+NaHS组以及低氧组肺中、小型肺动脉平滑肌细胞CTGF表达含量依次增高,但3组之间无显著差异。结论硫化氢可能通过调节低氧性肺动脉高压大鼠肺小血管肌性动脉TGF-β的表达,进而抑制细胞外基质成分之一的弹力蛋白合成,参与低氧性肺动脉高压的形成。     

不同根管预备器械对弯曲根管预备效果的影响

目的:研究不同根管预备器械对弯曲根管预备效果的影响。方法:96例牙髓炎或根尖牙周炎患者作为研究对象,共148颗患牙,按照抽签法,分为观察A组、观察B组和对照组,各32例。观察A组Protaper机,观察B组Mtwo机,对照组不锈钢K锉,比较根管预备时间、弯曲度、疼痛反应、根管锥度、流畅度及充填效果。结果:观察A组、观察B组预备时间显著少于对照组（P<0.05）。观察A组、B组比较无显著差异（P>0.05）。预备后3组根管弯曲度均显著降低（P<0.05）。3组组间比较无显著差异（P>0.05）。观察A组、B组疼痛反应显著优于对照组（P<0.05）;观察A组、观察B组前磨牙、后磨牙的锥度和流畅度显著优于对照组（P<0.05）。观察A组（90.63%）、B组（88.89%）适充充填显著优于对照组（80.00%）（P<0.05）。结论:镍钛预备器械的弯曲根管预备快速,能够保持根管形态,提高充填效果。     

Magnetic Polymer/Nickel Hybrid Nanoparticles Via Miniemulsion Polymerization

This work shows a method to synthesize and encapsulate magnetic nickel nanocrystals into polymeric colloidal particles through miniemulsion polymerization. The nickel nanoparticles are produced by a thermal decomposition method in the presence of oleylamine and triphenylphosphine, which results in a hydrophobic surface. However, being compatible with the monomer does not ensure a successful encapsulation by miniemulsion polymerization, as the nickel nanoparticles are expelled from the polymer particles with increasing styrene conversion due to the poor adhesion interaction between the organic shells of the nickel nanoparticles and the polystyrene. Changing the hydrophobic polystyrene to a polymer with higher polarity such as poly(methyl methacrylate) proves to be efficient for encapsulation of nickel nanoparticles when employing a hydrophilic initiator. After encapsulation, these nanoparticles show magnetic response.

     

Resveratrol protects human bronchial epithelial cells against nickel‐induced toxicity via suppressing p38 MAPK,NF‐κB signaling,and NLRP3 inflammasome activation

Nickel is a common environmental pollutant that can impair the lung, but the underlying mechanisms have not yet been fully elucidated. Furthermore, natural products are generally used to inhibit cell damage induced by heavy metal. Resveratrol possesses wide biological activities, including anti‐inflammation and antioxidative stress. This study was conducted to explore the toxicity of nickel on human bronchial epithelial (BEAS‐2B) cells and evaluate the protective effect of resveratrol. The results showed that nickel could induce cell apoptosis, increase oxidative stress, and promote the expression of pro‐inflammatory cytokines, including tumor necrosis factor‐α, interleukin (IL)‐1β, IL‐6, IL‐8, C‐reaction protein. Western blot analysis showed that nickel activated p38 mitogen‐activated protein kinase (MAPK), nuclear factor‐kappa B, and nucleotide‐binding oligomerization domain‐like receptor pyrin‐domain‐containing protein 3 pathways, while resveratrol could reverse these effects. Our results suggested that resveratrol could protect BEAS‐2B cells from nickel‐induced cytotoxicity. Therefore, resveratrol is a potential chemopreventive agent against nickel‐induced lung disease.     

Comparison of cyclic fatigue resistance of novel nickel‐titanium rotary instruments

New files (ProTaper Next/HyFlex/OneShape) are made from novel nickel‐titanium (NiTi) alloys/treatments. The purpose of this study was to compare the cyclic fatigue resistance of these new instruments with that of Revo‐S instruments. Four groups of 20 NiTi endodontic instruments were tested in steel canals with a 3 mm radius and a 60° angle of curvature. The cyclic fatigue of the following NiTi instruments with a tip size 25 and 0.06 taper that were manufactured with different alloys was tested: ProTaper Next X2 (M‐Wire), OneShape (conventional NiTi), Revo‐S Shaping Universal (conventional NiTi) and HyFlex 25/0.6 (controlled memory NiTi wire). A one‐way anova and post‐hoc Tukey's test (α = 0.05) revealed that the HyFlex files had the highest fatigue resistance and the Revo‐S had the least fatigue resistance among the groups (P < 0.001).