Mechanism of human immunodeficiency virus type 1 localization in CD4-negative thymocytes: differentiation from a CD4-positive precursor allows productive infection

Human immunodeficiency virus (HIV) infection of the thymus could have profound effects on development of the immune response, particularly in children. We and others have established that in addition to infecting and depleting CD4-bearing thymocytes, functional HIV proviruses are found in thymocytes lacking surface CD4 expression. Using in vitro thymocyte cultures, we show that neither HIV-mediated down regulation of CD4 nor CD4-independent infection contributes to the localization of HIV in cells lacking the primary virus receptor. Rather, infection of a CD4-positive precursor cell (CD4 positive/CD8 positive) with subsequent differentiation into a mature CD4-negative phenotype results in productively infected CD4-negative cells. This novel mechanism may contribute to pathogenesis by distributing viral sequences into functional subsets of T cells typically refractory to HIV infection and could account for the presence of viral DNA in CD8-positive lymphocytes recently observed in patients.     

I/O虚拟化将重新定义PCI Express的功能

过去几年,PCI Express(以下简称PCIe)总线逐渐成为一种适用于网络应用、具有高效率和成本效益的平台。PCIe的发展是为了克服过去并行计算机总线架构在性能、可扩展性以及配置等方面的限制,这种通用的串行I/O互连技术已被企业型、桌上型、移动、通信及嵌入式等各种应用广泛采用。尽管普及度已相当广泛,业界却普遍认为:PCIe总线的功能还是无法满足高性能存储和网络独特的I/O需求。     

Developing feasible and optimal schedules of jobs on one machine

The paper considers the properties of feasible and optimal scheduling of jobs on one machine under constraints on the terms of the beginning and completion of jobs and on partial sequences of job performance. The established properties and the lower-bound estimates of the length of the optimal schedule are used to develop methods for the exact and approximate solutions of the formulated problem by sequential optimization algorithms. The proposed algorithms are illustrated by numerical examples and can be successfully applied to solve these problems in the absence of constraints.     

Background music as a risk factor for distraction among young-novice drivers

There are countless beliefs about the power of music during driving. The last thing one would think about is: how safe is it to listen or sing to music? Unfortunately, collisions linked to music devices have been known for some time; adjusting the radio controls, swapping tape-cassettes and compact-discs, or searching through MP3 files, are all forms of distraction that can result in a near-crash or crash. While the decrement of vehicular performance can also occur from capacity interference to central attention, whether or not music listening is a contributing factor to distraction is relatively unknown. The current study explored the effects of driver-preferred music on driver behavior. 85 young-novice drivers completed six trips in an instrumented Learners Vehicle. The study found that all participants committed at-least 3 driver deficiencies; 27 needed a verbal warning/command and 17 required a steering or braking intervention to prevent an accident. While there were elevated positive moods and enjoyment for trips with driver-preferred music, this background also produced the most frequent severe driver miscalculations and inaccuracies, violations, and aggressive driving. However, trips with music structurally designed to generate moderate levels of perceptual complexity, improved driver behavior and increased driver safety. The study is the first within-subjects on-road high-dose double-exposure clinical-trial investigation of musical stimuli on driver behavior.     

如何让硬件发挥最大功效？

对于我们而言，绝大多数人都想从身边的硬件设备，或其他应用中获得最大功效，例如，台式电脑、手机、无线网络和其他设备。而在我们接下来的这篇文章中，我们将手把手教大家如何让科技设备运行得更快，变得更具功效，变得更加通用。     

The impact of the Internet on the social lives of users: A representative sample from 13 countries

One of the most vociferous criticisms of the Internet has always been that it contributes to loneliness among its users. This study analyses results from the World Internet Project, comprised of representative samples from 13 countries (22,002 participants). Thus creating an exceptional international representative sample. In analyzing those results, we argue that in order to achieve a comprehensive understanding of the Internet’s influence over individuals’ social lives; it is essential to consider the different types of social connections that might be influenced by the Internet. We assess the influence of Internet use over social interactions in separate life domains (e.g. with family members; friends; colleagues). Our analysis confirms that Internet usage can actually enhance the social lives of its users. Qualifications to the research are discussed while highlighting the different life domains in which we found significant correlations between Internet usage and increased social interactions.     

Transcriptional regulation of cellular retinaldehyde-binding protein in the retinal pigment epithelium. A role for the photoreceptor consensus element

Cellular retinaldehyde-binding protein (CRALBP) is abundantly expressed in the retinal pigment epithelium (RPE) and Muller cells of the retina, where it is thought to function in retinoid metabolism and visual pigment regeneration. Mutations in human CRALBP that destroy retinoid binding have been linked to autosomal recessive retinitis pigmentosa. To identify the DNA elements that regulate expression of the human CRALBP gene in the RPE, transient transfection studies were carried out with three CRALBP-expressing human RPE cell culture systems. The regions from -2089 to -1539 base pairs and from -243 to +80 base pairs demonstrated positive regulatory activity. Similar activity was not observed with cultured human breast, liver, or skin cells. Since sequence analysis of the -243 to +80 region identified the presence of two photoreceptor consensus element-1 (PCE-1) sites, elements that have been implicated in photoreceptor gene regulation, the role of these sequences in RPE expression was examined. Mutation of either PCE-1 site significantly reduced reporter activity, and mutation or deletion of both sites dramatically reduced activity. Electrophoretic mobility shift analysis with RPE nuclear extracts revealed two complexes that required intact PCE-1 sites. These studies also identified two identical sequences (GCAGGA) flanking PCE-1, termed the binding CRALBP element (BCE), that are also important for complex formation. Southwestern analysis with PCE-1/BCEcontaining probes identified species with apparent masses near 90-100 and 31 kDa. These results begin to identify the regulatory regions required for RPE expression of CRALBP and suggest that PCE-1-binding factor(s) may play a role in regulating RPE as well as photoreceptor gene expression.     

Basic fibroblast growth factor is neither necessary nor sufficient for the development of retinal neovascularization

Basic fibroblast growth factor (FGF2) is constitutively expressed in the retina and its expression is increased by a number of insults, but its role in the retina is still uncertain. This study was designed to test the hypothesis that altered expression of FGF2 in the retina affects the development of retinal neovascularization. Mice with targeted disruption of the Fgf2 gene had no detectable expression of FGF2 in the retina by Western blot, but retinal vessels were not different in appearance or total area from wild-type mice. When FGF2-deficient mice were compared with wild-type mice in a murine model of oxygen-induced ischemic retinopathy, they developed the same amount of retinal neovascularization. Transgenic mice with a rhodopsin promoter/Fgf2 gene fusion expressed high levels of FGF2 in retinal photoreceptors but developed no retinal neovascularization or other abnormalities of retinal vessels; in the ischemic retinopathy model, they showed no significant difference in the amount of retinal neovascularization compared with wild-type mice. These data indicate that FGF2 expression is not necessary nor sufficient for the development of retinal neovascularization. This suggests that agents that specifically antagonize FGF2 are not likely to be useful adjuncts in the treatment of retinal neovascularization and therapies designed to increase FGF2 expression are not likely to be complicated by retinal neovascularization.     

Behavioral tolerance and sensitization to alcohol in humans: The contribution of learning.

This experiment tested the hypothesis that tolerance or sensitization to repeated alcohol doses is predicted by the particular response (diminished or augmented impairment) that is reinforced under drug. Twelve male social drinkers were assigned to a tolerance (T) or sensitization (S) group (n?=?6) and performed a psychomotor task under 0.62 g/kg of alcohol on 5 separate sessions. The 1st session preceded training and determined that the groups' drugged performance did not differ. On 3 subsequent sessions verbal feedback reinforced diminished impairment in Group T and augmented impairment in Group S. During these sessions, Groups T and S displayed tolerance and sensitization, respectively. The final session showed that training effects were retained without reinforcement. The results extend the evidence on the effect of reinforcement to show that it can enhance sensitization as well as tolerance. The findings demonstrate that behavioral variables modulate the response to alcohol and imply that tolerance and sensitization may be affected by a common learning process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)