Sulfhydryls and the in vitro polymerization of tubulin

The free sulfhydryls of brain tubulin prepared by cyclic polymerization procedures both with and without glycerol have been examined. The average free sulfhydryl titer of tubulin prepared with glycerol (7.0 sulfhydryls/55,000 mol wt) is greater than that of tubulin prepared without glycerol (4.0 sulfhydryls/55,000 mol wt). Diamide, a sulfhydryl-oxidizing agent, inhibits the polymerization of tubulin. Diamide also disperses the 20S and 30S oligomers of tubulin seen in analytical ultracentrifuge patterns of tubulin solutions and, depending on the temperature at which diamide is added, converts all or part of the oligomeric material to 6S dimers. Electron microscopy demonstrates that diamide also destroys the 450-A ring structures characteristic of tubulin solutions. All diamide effects are reversible by the addition of 10 mM dithioerythreitol, a sulfhydryl-reducing agent. That diamide interacts with sulfhydryls on tubulin is directly demonstrated by a 50% decrease in the free sulfhydryl titer of tubulin measured after diamide treatment. Concentrations of CaCl2 which inhibit polymerization also decrease the free sulfhydryl titer of tubulin.     

The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase III) surfactant-based formulations

The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.     

The effects of multifocal refractive lenses on occipital extension and forward head posture during a visual task

The purpose of this study was to determine if a change in forward head posture and occipital extension occurred in participants who wore multifocal lenses vs. those persons with non-multifocal lenses while performing an 8-min visual reading task on a visual display unit (VDU). Forty-two healthy human participants were recruited for this study. Thirty-three participants completed the study. Fourteen participants wore multifocal lenses and 19 wore frames with non-multifocal lenses. To evaluate the degree of change of forward head posture and occipital extension digital photographs of cervical posture were taken at four different time intervals: prior to performing the reading task and at 3, 5 and 8 min during the reading task. The digital photographs were analysed utilizing a computer program. Two one-way ANOVA were utilized to determine the degree of change of forward head posture and occipital extension between groups. A significant difference was identified between groups for changes in degrees of forward head posture while performing a visual reading task on a VDU. However, no significant difference between groups was found for occipital extension while performing the same task. Multifocal wearers exhibit greater degrees of change in forward head posture and occipital extension than non-multifocal wearers. These postural changes may place them at a greater risk for musculoskeletal disorders and headaches.     

大型SMTP服务器的设计与实现

给出了一种大型SMTP服务器系统的分布式结构、SMTP服务器扩展的方法以及MIME格式的电子邮件解析方式,同时给出了邮件的存储方式、邮件列表的结构和邮件列表的处理方式以及系统核心模块的实现代码。在系统实现中采用了面向对象技术和多线程技术,系统完全由标准C 语言实现。该SMTP系统适于大型电子邮件系统应用,它能够同时处理大量并发邮件操作,运行在各种操作系统与硬件平台上。     

Armed conflict and children's rights

Comments on the article by V. Murphy-Berman and V. Weisz (1996) in which some of the significant challenges and issues in implementing the United Nations Convention on the Rights of the Child (CRC) are discussed. The author believes that though the article was insightful, it overlooked the impact of armed conflict, one of the most profound sources of abuse of children's human rights worldwide. Some of the points made in an article by G. Machel (1996) are restated including the number of children soldiers and the physical, emotional, and psychological abuse they endure. The author goes on to mention other issues including parentless refugees, the dangers of land mines during and after the war, and the effects of sanctions on children. The author believes that intercultural differences and political issues may also hamper the implementation of the CRC. The article concludes with ways in which psychologists can help and the need to ratify the CRC. (PsycINFO Database Record (c) 2010 APA, all rights reserved)