The Ordinal Effects of Ostracism: A Meta-Analysis of 120 Cyberball Studies

We examined 120 Cyberball studies (N = 11,869) to determine the effect size of ostracism and conditions under which the effect may be reversed, eliminated, or small. Our analyses showed that (1) the average ostracism effect is large (d > |1.4|) and (2) generalizes across structural aspects (number of players, ostracism duration, number of tosses, type of needs scale), sampling aspects (gender, age, country), and types of dependent measure (interpersonal, intrapersonal, fundamental needs). Further, we test Williams’s (2009) proposition that the immediate impact of ostracism is resistant to moderation, but that moderation is more likely to be observed in delayed measures. Our findings suggest that (3) both first and last measures are susceptible to moderation and (4) time passed since being ostracized does not predict effect sizes of the last measure. Thus, support for this proposition is tenuous and we suggest modifications to the temporal need-threat model of ostracism.     

A Conclusive View on Charge Generation,Recombination, and Extraction in As‐Prepared and Annealed P3HT:PCBM Blends: Combined Experimental and Simulation Work

Time‐delayed collection field (TDCF) and bias‐amplified charge extraction (BACE) are applied to as‐prepared and annealed poly(3‐hexylthiophene):[6,6]‐phenyl C₇₁ butyric acid methyl ester (P3HT:PCBM) blends coated from chloroform. Despite large differences in fill factor, short‐circuit current, and power conversion efficiency, both blends exhibit a negligible dependence of photogeneration on the electric field and strictly bimolecular recombination (BMR) with a weak dependence of the BMR coefficient on charge density. Drift‐diffusion simulations are performed using the measured coefficients and mobilities, taking into account bimolecular recombination and the possible effects of surface recombination. The excellent agreement between the simulation and the experimental data for an intensity range covering two orders of magnitude indicates that a field‐independent generation rate and a density‐independent recombination coefficient describe the current–voltage characteristics of the annealed P3HT:PCBM devices, while the performance of the as‐prepared blend is shown to be limited by space charge effects due to a low hole mobility. Finally, even though the bimolecular recombination coefficient is small, surface recombination is found to be a negligible loss mechanism in these solar cells.     

Late effects of radiation on the central nervous system: role of vascular endothelial damage and glial stem cell survival

Selective irradiation of the vasculature of the rat spinal cord was used in this study, which was designed specifically to address the question as to whether it is the endothelial cell or the glial progenitor cell that is the target responsible for late white matter necrosis in the CNS. Selective irradiation of the vascular endothelium was achieved by the intraperitoneal (ip) administration of a boron compound known as BSH (Na(2)B(12)H(11)SH), followed by local irradiation with thermal neutrons. The blood-brain barrier is known to exclude BSH from the CNS parenchyma. Thirty minutes after the ip injection of BSH, the boron concentration in blood was 100 microg (10)B/ g, while that in the CNS parenchyma was below the detection limit of the boron analysis system, <1 microg (10)B/g. An ex vivo clonogenic assay of the O2A (oligodendrocyte-type 2 astrocyte) glial progenitor cell survival was performed 1 week after irradiation and at various times during the latent period before white matter necrosis in the spinal cord resulted in myelopathy. One week after 4.5 Gy of thermal neutron irradiation alone (approximately one-third of the dose required to produce a 50% incidence of radiation myelopathy), the average glial progenitor cell surviving fraction was 0.03. The surviving fraction of glial progenitor cells after a thermal neutron irradiation with BSH for a comparable effect was 0.46. The high level of glial progenitor cell survival after irradiation in the presence of BSH clearly reflects the lower dose delivered to the parenchyma due to the complete exclusion of BSH by the blood-brain barrier. The intermediate response of glial progenitor cells after irradiation with thermal neutrons in the presence of a boron compound known as BPA (p-dihydroxyboryl-phenylalanine), again for a dose that represents one-third the ED(50) for radiation-induced myelopathy, reflects the differential partition of boron-10 between blood and CNS parenchyma for this compound, which crosses the blood-brain barrier, at the time of irradiation. The large differences in glial progenitor survival seen 1 week after irradiation were also maintained during the 4-5-month latent period before the development of radiation myelopathy, due to selective white matter necrosis, after irradiation with doses that would produce a high incidence of radiation myelopathy. Glial progenitor survival was similar to control values at 100 days after irradiation with a dose of thermal neutrons in the presence of BSH, significantly greater than the ED(100), shortly before the normal time of onset of myelopathy. In contrast, glial progenitor survival was less than 1% of control levels after irradiation with 15 Gy of thermal neutrons alone. This dose of thermal neutrons represents the approximate ED(90-100) for myelopathy. The response to irradiation with an equivalent dose of X rays (ED(90): 23 Gy) was intermediate between these extremes as it was to thermal neutrons in the presence of BPA at a slightly lower dose equivalent to the approximate ED(60) for radiation myelopathy. The conclusions from these studies, performed at dose levels approximately iso-effective for radiation-induced myelopathy as a consequence of white matter necrosis, were that the large differences observed in glial progenitor survival were directly related to the dose distribution in the parenchyma. These observations clearly indicate the relative importance of the dose to the vascular endothelium as the primary event leading to white matter necrosis.     

The choice of reference gene set for assessing gene expression in barley (Hordeum vulgare L.) under low temperature and drought stress

Drought and low temperature are the two most significant causes of abiotic stress in agricultural crops and, therefore, they pose considerable challenges in plant science. Hence, it is crucial to study response mechanisms and to select genes for identification signaling pathways that lead from stimulus to response. The assessment of gene expression is often attempted using real-time RT-PCR (qRT-PCR), a technique which requires a careful choice of reference gene(s) for normalization purpose. Here, we report a comparison of 13 potential reference genes for studying gene expression in the leaf and crown of barley seedlings subjected to low temperature or drought stress. All three currently available software packages designed to identify reference genes from qRT-PCR data (GeNorm, NormFinder and BestKeeper) were used to identify informative sets of up to three reference genes. Interestingly, the data obtained from the separate treatment of leaf and crown have led to the recommendations that HSP70 and S-AMD (and possibly HSP90) to be used as the reference genes for low-temperature stressed leaves, HSP90 and EF1α for low-temperature stressed crowns, cyclophilin and ADP-RF (and possibly ACT) for drought-stressed leaves, and EF1α and S-AMD for drought-stressed crowns. Our results have demonstrated that the gene expression can be highly tissue- or organ-specific in barley and have confirmed that reference gene choice is essential in qRT-PCR. The findings can also serve as guidelines for the selection of reference genes under different stress conditions and lay foundation for more accurate and widespread use of qRT-PCR in barley gene analysis.     

DNA-repair in mild cognitive impairment and Alzheimer's disease

While the pathogenesis of the sporadic form of Alzheimer disease (late onset Alzheimer disease, LOAD) is not fully understood, it seems to be clear that a combination of genetic and environmental factors are involved and influence the course of the disease. Among these factors, elevated levels of oxidative stress have been recognized and individual differences in the capacity to deal with DNA damage caused by its effects have been the subject of numerous studies. This review summarizes the research on DNA repair proteins and genes in the context of LOAD pathogenesis and its possible prodromal stage, mild cognitive impairment (MCI). The current status of the research in this field is discussed with respect to methodological issues which might have compromised the outcome of some studies and future directions of investigation on this subject are depicted.     

Resistance of human immunodeficiency virus type 1 to a third-generation fusion inhibitor requires multiple mutations in gp41 and is accompanied by a dramatic loss of gp41 function

HIV-1 entry into target cells requires the fusion of viral and cellular membranes. This process is an attractive target for therapeutic intervention, and a first-generation fusion inhibitor, T20 (Enfuvirtide; Fuzeon), was approved for clinical use in 2003. Second-generation (T1249) and third-generation (T2635) fusion inhibitors with improved stability and potency were developed. Resistance to T20 and T1249 usually requires one or two amino acid changes within the binding site. We studied the in vitro evolution of resistance against T2635. After 6 months of culturing, a multitude of resistance mutations was identified in all gp41 subdomains, but no single mutation provided meaningful T2635 resistance. In contrast, multiple mutations within gp41 were required for resistance, and this was accompanied by a dramatic loss of viral infectivity. Because most of the escape mutations were situated outside the T2635 binding site, a decrease in drug target affinity cannot account for most of the resistance. T2635 resistance is likely to depend on altered kinetics of six-helix bundle formation, thus limiting the time window for T2635 to interfere with membrane fusion. Interestingly, the loss of virus infectivity caused by T2635 resistance mutations in gp41 was partially compensated for by a mutation at the base of the V3 domain in gp120. Thus, escape from the third-generation HIV-1 fusion inhibitor T2635 is mechanistically distinct from resistance against its predecessors T20 and T1249. It requires the accumulation of multiple mutations in gp41, is accompanied with a dramatic loss of gp41 function, and induces compensatory mutations in gp120.