Risk Assessment of Nongenotoxic Carcinogens Based upon Cell Proliferation/Death Rates in Rodents

Increased cell proliferation increases the opportunity for transformations of normal cells to malignant cells via intermediate cells. Nongenotoxic cytotoxic carcinogens that increase cell proliferation rates to replace necrotic cells are likely to have a threshold dose for cytotoxicity below which necrosis and hence, carcinogenesis do not occur. Thus, low dose cancer risk estimates based upon nonthreshold, linear extrapolation are inappropriate for this situation. However, a threshold dose is questionable if a nongenotoxic carcinogen acts via a cell receptor. Also, a nongenotoxic carcinogen that increases the cell proliferation rate, via the cell division rate and/or cell removal rate by apoptosis, by augmenting an existing endogenous mechanism is not likely to have a threshold dose. Whether or not a threshold dose exists for nongenotoxic carcinogens, it is of interest to study the relationship between lifetime tumor incidence and the cell proliferation rate. The Moolgavkar–Venzon–Knudson biologically based stochastic two-stage clonal expansion model is used to describe a carcinogenic process. Because the variability in cell proliferation rates among animals often makes it impossible to detect changes of less than 20% in the rate, it is shown that small changes in the cell proliferation rate, that may be obscured by the background noise in rates, can produce large changes in the lifetime tumor incidence as calculated from the Moolgavkar–Venzon–Knudson model. That is, dose response curves for cell proliferation and tumor incidence do not necessarily mimic each other. This makes the use of no observed effect levels (NOELs) for cell proliferation rates often inadmissible for establishing acceptable daily intakes (ADIs) of nongenotoxic carcinogens. In those cases where low dose linearity is not likely, a potential alternative to a NOEL is a benchmark dose corresponding to a small increase in the cell proliferation rate, e. g., 1%, to which appropriate safety (uncertainty) factors can be applied to arrive at an ADI.     

植物原生质体培养及应用

综述了原生质体培养的研究进展,原生质体培养在理论上和品种改良中的应用。在理论研究中的应用有三个方面：1、细胞生理现象的研究;2、细胞核与细胞质相互关系的研究;3、病毒侵染与复制机理的研究。在品种改良中的应用采用的方法包括二个方面：1、遗传操作;2、突变体的筛选。     

Carcinogenicity Studies on MTBE: Critical Review and Interpretation

Chronic inhalation of toxic concentrations of MTBE caused renal tubular cell neoplasms in male Fischer 344 rats and hepatocellular adenomas in female CD-1 mice. In Sprague-Dawley rats the oral administration of MTBE was associated with increased incidences of Leydig cell tumors and of lymphomas and leukemias (combined) in males and females, respectively. Neither lymphomas nor leukemias were individually increased in treated females. Leydig cell tumors are common in rats and do not predict human responses to drugs and chemicals. Neither MTBE nor its metabolite, t -butyl alcohol, possess mutagenic potential and a second metabolite, formaldehyde, is mutagenic in vitro but in vivo results are equivocal. MTBE-induced neoplasms are most likely produced through a nongenetic mechanism which requires chronic exposure to toxic doses. Because of the intense odor (and taste) of MTBE, humans will not tolerate either air or water concentrations sufficient to produce the cytotoxic precursors required to promote cellular proliferation.     

红色文化与铸牢中华民族共同体意识的耦合协调度：基于百色市的实证分析

选取红色文化旅游、红色文化宣讲、红色文化教育作为评估指标构建红色文化子系统,选取“五个认同”作为评估指标构建铸牢中华民族共同体意识子系统,运用耦合协调度模型分析百色市红色文化与铸牢中华民族共同体意识的耦合协调度。实证研究表明,百色市红色文化与铸牢中华民族共同体意识内部要素之间相互促进作用显著,具有高度耦合;2019-2021年百色市红色文化与铸牢中华民族共同体意识分别处于勉强协调、初步协调、良好协调阶段,二者的良性互动已显现成效,但协调发展水平有待进一步提高。最后,从推动红色文化进产业、进社区、进学校,夯实铸牢中华民族共同体意识的经济基础、群众基础、社会基础方面提出提升红色文化与铸牢中华民族共同体意识耦合协调度水平的实践路径。     

浅议安徽省红色旅游发展的意义和存在问题

红色旅游是我国新兴的专项旅游产品,它的出现为安徽省原本较为单调的以观光型旅游产品为主的旅游产业注入了一股新鲜血液。红色旅游为安徽省旅游发挥了巨大的热量,带来其特有的社会和经济效益,但相应的问题也逐渐显露,亟待有关部门去解决。     

当代红色经典中的风景书写与政治认同

“十七年”时期的红色经典小说在风景书写中通过划定阶级观看权与所有权、添加时间和空间的伦理内涵、建构崇高审美范式,确立了人们的政治归属感,并教育人们依托广大人民群众的质朴品性,发扬崇高热烈的意志和英雄主义奋斗精神,运用现代科学与理性来建设新中国的美好未来,从而塑造了对新生人民政权的政治认同。     

河北省红色旅游发展对策研究

从2004年下半年开始,红色旅游热席卷全国,河北省红色旅游得到了快速发展。同时,也表现出了河北省红色旅游在产品开发和景区管理方面还跟不上形势发展的要求。本文在对河北省红色旅游发展现状进行分析的基础上,总结了目前河北省红色旅游的经验做法和存在的问题,从提高认识、产品开发、区域合作、宣传促销、理顺体制等方面,提出了河北省红色旅游发展的若干对策,对红色旅游业的可持续发展进行了理论性探讨。     

新时代思想政治理论课创新之路

习近平总书记于2019年3月18日主持召开学校思想政治理论课教师座谈会并发表重要讲话,对人才培养目标、思想政治理论的任务,思想政治理论课教师等提出了新时代的新要求。马克思主义学院教师作为高校思想政治理论课的主要承担者,应该牢记习近平总书记的嘱托,根据学校和学生特点,不断探索更加符合实际的思想政治理论课教学新路径。     

基于游客和居民感知的红色旅游发展研究

红色旅游的持续发展对促进旅游和红色文化的有机融合、优化区域经济结构、转变发展方式提供了新途径。基于安徽六安红色旅游景区的实证调查结果表明,游客感知方面存在旅游项目与产品体系欠丰富、旅游基础设施有待改善、旅游商品开发落后等问题;社区居民方面认为红色旅游的发展对社区经济发展存在积极影响,但目前存在受益不均衡、参与有限、生态与人居环境受到负面影响等问题。从拓宽产品谱系、创新产品类型、塑造景区品牌、保障社区利益、实施生态环境保护等方面完善管理行为,将有益于红色旅游的持续发展。     

手机铃声下载的著作权问题

手机铃声下载作为一种新型网络服务方式引发了一系列相关的著作权问题。通过对一起典型案例的分析,指出未经许可使用音乐作品作为手机铃声供人下载侵犯了作者的信息网络传播权,但是应当由网络内容提供商而非网络服务商承当由此产生的赔偿责任。此外,应当以合理方式确定著作权集体管理组织的相关收费标准,以促进作者利益与社会公共利益之间的平衡。