Human carcinogenic risk evaluation: an alternative approach to the two-year rodent bioassay.

An approach to the evaluation of carcinogenic risk resulting from exposure to a given chemical is presented in place of a reliance on two-year rodent bioassays. An emphasis is placed on evaluation of the potential DNA reactivity or increased cell proliferation that can be produced by a chemical. The special cases of immunosuppressive and estrogenic chemicals are considered. These evaluations are proposed to involve a combination of in vitro assays, computerized models, and short-term (up to 13 weeks) bioassays in rodents. The emphasis is on mechanistic understanding and evaluation of the dose response and relevance to humans.     

经济转型期公立医院管理者的激励与约束机制研究概述

目的 探索在市场经济条件下对公立医院管理者有效的激励与约束机制,建立医院管理岗位的创新机制。方法 通过现场调查访问,结合文献综述、座谈法,收集数据;通过描述性统计方法、主成分分析等统计分析方法进行数据分析。结果 通过对现在公立医院管理者的激励与约束措施和意向调查分析,找出了现在公立医院管理者激励机制和约束机制中的问题,提出了在实行医院产权制度改革的基础上建立新的分配机制,建立公立医院管理者任用竞争机制,对医院管理岗位实行人力资本管理的创新机制,加强法律法规和卫生政策对医院管理者权力的约束。结论 提出了建立适应市场经济条件下医院管理者的有效激励与约束机制的运作模式。     

流感病毒感染中炎症小体的激活和调控机制

炎症反应是宿主抗流感病毒感染的一个重要过程,它可以诱导产生抗病毒的炎症微环境以减少病毒的复制和扩散,同时参与对流感病毒的适应性免疫反应,在机体抗流感病毒感染过程中至关重要.然而,过度的炎症反应同时也是流感病毒重症感染、甚至死亡的主要因素.研究表明,炎症小体作为炎症反应的重要启动和调节分子,介导IL-1β和IL-18的成...     

护理风险预警机制在慢性乙型病毒性肝炎肝衰竭病人护理中的应用效果

目的:探讨护理风险预警机制在慢性乙型肝炎肝衰竭病人护理中的应用效果。方法:选取2018年1月—2019年12月我院收治的104例慢性乙型肝炎肝衰竭病人,按照病人入院顺序,并采用单双号抽签方式分为对照组和观察组,各52例。对照组给予常规护理干预,观察组临床护理中引入护理风险预警机制,对比两组肝功能指标、并发症发生情况、护理满意度、护理质量评分、护理缺陷评分及住院时间。结果:干预后,两组肝功能指标均有所改善,且观察组下降幅度较对照组大(P<0.001);观察组与对照组并发症发生率分别为7.69%、25.00%,观察组与对照组总满意度分别为96.15%、76.92%,观察组病人护理质量评分高于对照组,护理缺陷评分及住院时间低于对照组,差异均有统计学意义(P<0.05)。结论:将护理风险预警机制用于慢性乙型肝炎肝衰竭病人的临床护理中,有利于改善病人肝功能指标,减少并发症及护理缺陷,提高护理满意度,提升护理质量,缩短病人住院时间。     

心肌炎的免疫学作用机制

病毒感染引起的心肌炎临床最为常见,其中半数以上由柯萨奇B组病毒所致。然而,迄今为止,其发病机制尚未完全明了,病毒感染对心肌细胞的直接损伤作用及病毒介导的免疫损伤作用是目前认为最有可能的机制,因此,了解心肌炎的免疫学机制具有重要的理论和实践意义。     

糖皮质激素性高眼压小梁网病理改变及相关分子机制进展

糖皮质激素性高眼压(GIOH)是一种由糖皮质激素引起的高眼压。长期处于GIOH状态,可能会导致视神经损害和视野缺损,最终发展成糖皮质激素性青光眼(GIG),可能致盲。糖皮质激素主要通过介导糖皮质激素受体(GR)发挥生物学作用,同时还涉及到转化生长因子(TGF)-β、Wnt、Rho等因素在GIOH的形成中的作用。深入探讨GIOH小梁网的病理改变及相关分子机制对于理解GIOH的发病机制和治疗提供了重要的理论依据。因此文章就GIOH小梁网的病理改变及相关分子机制进行综述,旨在为进一步研究GIOH的病理机制及治疗提供理论依据。     

Study on Autolytic Mechanism and Self-Healing Properties of Autolytic Clinker Microsphere in Alkaline Environment

In this study, the autolytic clinker microsphere with clinker as core and polyvinyl pyrrolidone (PVP) as coating film was prepared. Pretreatment of clinker with silane coupling agent was firstly processed during the preparation. To investigate the autolytic mechanism, the microstructures of the autolytic clinker microsphere at different curing ages were observed using environmental scanning electron microscopy (ESEM), equipped with an energy dispersive spectrometer (EDS). The autolytic stages were also identified based on the microstructural evolution. The influence of pretreatment degree on autolytic behavior was also studied by measurements of micro-morphology and isothermal calorimetry. Experimental results indicated that the compressive strength recovery of specimens was increased by 15–19% due to the addition of autolytic clinker microspheres. The recovery of compressive strength was also improved with the increase of pH value. The improvements in compressive strength recovery of specimens with microspheres were in the range of 15–19%, 15–31%, 25–36%, and 29–50% with the pH value of 7, 8, 10, and 12, respectively. It was also found that inner damage of cement-based matrix had greater recovery when pre-cracked specimens were cured in alkaline environments.     

A First-Principles Study on the Hydration Behavior of (MgO)n Clusters and the Effect Mechanism of Anti-Hydration Agents

Magnesia-based refractory is widely used in high-temperature industries; its easy hydration is, however, a key concern in refractory processing. Understanding the hydration mechanism of MgO will help in solving its hydration problem. Herein, the hydration behavior of (MgO)_n (n = 1–6) at the molecular level and the effect mechanisms of several anti-hydration agents on the hydration of (MgO)₄ were investigated with first-principles calculations. The results indicated that the following: (1) The smaller the (MgO)_n cluster size, the more favorable the hydration of MgO and the tendency to convert into Mg(OH)₂ crystal; (2) Anti-hydration agents can coordinate with the unsaturated Mg atom of (MgO)₄ to form a bond, increasing the coordination number of Mg, thus reducing its activity when reacting with H₂O; (3) The greater the number of −COOH groups and the longer the chain length in the anti-hydration agents, the better its effect of inhibiting the hydration of MgO. These findings could enhance the understanding of the mechanism of hydration of MgO and provide theoretical guidance for the design of novel anti-hydration agents.     

水凝胶的生物力学研究进展

水凝胶是生物医用领域的重要生物材料,也是近年来的研究热点。但人体内的细胞与组织的微环境和调控机制非常复杂,水凝胶应用于再生修复领域仍存在一些待解决的科学问题。随着生物力学的发展,越来越多的研究者发现除了关注水凝胶的材料学及生物学特性以外,其生物力学特性也是调控细胞功能、影响组织再生修复的关键因素之一。因此,本文总结了水凝胶材料的生物力学研究进展,并对未来的研究工作进行了展望。     

基于胰腺纤维化微环境探讨中医药防治慢性胰腺炎的机制

从胰腺纤维化的微环境出发,综述了多种细胞在慢性胰腺炎发病中的作用,以及中医药防治慢性胰腺炎的相关机制.中医药可通过调节细胞外基质的过度产生和降解,抑制胰腺星状细胞的活化、腺泡细胞的凋亡、炎症细胞的浸润和炎性因子的释放来减缓胰腺纤维化,从而达到防治慢性胰腺炎的目的,为慢性胰腺炎的临床治疗提供参考.