创伤后应激障碍的组蛋白修饰机制

创伤后应激障碍是一种具有复杂病因学的精神疾病,多发生于个体受到重大创伤事件后。创伤后应激障碍的发生发展过程受到环境和遗传易感性的共同作用,存在着较大的个体差异;而表观遗传学作为一门研究多变环境因素调控基因表达的可遗传变化的学科,近年来在创伤后应激障碍的研究中受到越来越多的重视。表观遗传机制之一——组蛋白修饰机制在创伤后应激障碍的发生中起着重要作用,并且由于组蛋白修饰可以受到多种酶的调控,其灵活的可逆化和精细调控为相应的药物研发提供了可能性和便利。因此,深入探讨创伤后应激障碍的组蛋白修饰机制,对于相关疾病的临床治疗及药物研发具有十分重要的意义。当前创伤后应激障碍的组蛋白修饰研究主要使用动物模型,临床研究较少;组蛋白的类型则主要关注组蛋白H3和H4乙酰化;此外,同以往的研究结果一致,组蛋白修饰水平的变化主要发生在前额叶、海马体和杏仁核区域,参与免疫系统、血清素系统和神经肽Y能系统等相关通路的调节。当前PTSD组蛋白修饰的研究结果间还存在较大的异质性,未来的研究应采用更加一致和实用的分析和报道方法,以最大限度地发挥研究的影响。     

A zero-bounded model of operant demand

Contemporary approaches for evaluating the demand for reinforcers use either the Exponential or the Exponentiated model of operant demand, both derived from the framework of Hursh and Silberberg (2008). This report summarizes the strengths and complications of this framework and proposes a novel implementation. This novel implementation incorporates earlier strengths and resolves existing shortcomings that are due to the use of a logarithmic scale for consumption. The Inverse Hyperbolic Sine (IHS) transformation is reviewed and evaluated as a replacement for the logarithmic scale in models of operant demand. Modeling consumption in the “log₁₀-like” IHS scale reflects relative changes in consumption (as with a log scale) and accommodates a true zero bound (i.e., zero consumption values). The presence of a zero bound obviates the need for a separate span parameter (i.e., k) and the span of the model may be more simply defined by maximum demand at zero price (i.e., Q₀). Further, this reformulated model serves to decouple the exponential rate constant (i.e., α) from variations in span, thus normalizing the rate constant to the span of consumption in IHS units and permitting comparisons when spans vary. This model, called the Zero-bounded Exponential (ZBE), is evaluated using simulated and real-world data. The direct reinstatement ZBE model showed strong correspondence with empirical indicators of demand and with a normalization of α (ZBEn) across empirical data that varied in reinforcing efficacy (dose, time to onset of peak effects). Future directions in demand curve analysis are discussed with recommendations for additional replication and exploration of scales beyond the logarithm when accommodating zero consumption data.     

Understanding the link between work engagement and affective organisational commitment: The moderating effect of role stress

This study aimed to explore the moderating effect of role ambiguity and role conflict on the relationship between work engagement and affective organisational commitment. Using convenience sampling, a final sample of 179 IT-specialists of services companies in southern Spain was obtained. Moderation analyses were performed using the hierarchical regressions and bootstrapping method (Bias-Corrected confidence intervals). Results showed that work engagement was positively related to affective commitment while role ambiguity and role conflict were negatively related to it. However, only role conflict moderated the relationship between work engagement and affective commitment. That is, at high levels of role conflict, IT-specialists perceiving higher levels of work engagement reported lower levels of affective commitment. This study highlights the hindrance effect of role conflict on one of the most important consequences of work engagement: affective commitment with the organisation. An adequate definition of role and positions could help to reduce the levels of role conflict, increasing the emotional bond to the organisation.