Regulation of connexin43 function by activated tyrosine protein kinases

Gap junctions are specialized membrane structures that are involved in the normal functioning of numerous mammalian tissues and implicated in several human disease processes. This mini-review focuses on the regulation of gap junctions through phosphorylation of connexin43 induced by the v-Src or epidermal growth factor receptor tyrosine kinases. These tyrosine kinases markedly disrupt gap junctional communication in mammalian cells. here, we describe work correlating the alteration of connexin43 function with the ability of the v-Src tyrosine kinase to phosphorylate connexin43 directly on two distinct tyrosine sites in mammalian cells (Y247 and Y265). We also present evidence that proline-rich regions and phosphotyrosine sites of connexin43 may mediate interactions with the SH3 and SH2 domains of v-Src. In contrast to v-Src, the activated epidermal growth factor receptor acts indirectly through activated MAP kinase which may stimulate phosphorylation of connexin43 exclusively on serine. This phosphorylation event is complex because MAP kinase phosphorylates three serine sites in connexin43 (S255, S279, and S282). These findings suggest novel interactions between connexin43, the v-Src tyrosine kinase, and activated MAP kinase that set the stage for future investigations into the regulation of gap junctions by protein phosphorylation.     

使现有普通电视机系统具备HDTV功能

今天的高清晰电视(HDTV)比以往更加具有生命力.由于它的图像质量相对传统的NTSC视频有非常明显的飞跃,有理由相信HDTV出色的图像会得到电视发烧友和普通消费者的一致推崇.现在,全球越来越多的电视运营商加快了提供高清晰电视节目的步伐,广播电视行业对HDTV的采纳程度也随之不断提高.近年来,甚至连电视游戏机制造商也加入到高清晰影像的运动中.     

Killing of Chlamydia trachomatis by novel antimicrobial lipids adapted from compounds in human breast milk

The development of new methods for prevention of sexually transmitted Chlamydia trachomatis infection is a top public health priority. Topical self-administered vaginal microbicides represent one such approach in which the organism is eradicated at the time of initial exposure. To this end, we examined the activity of five synthetic lipids adapted from naturally occurring compounds found in human breast milk. C. trachomatis serovar D or F elementary bodies were added to serial dilutions of the lipids and incubated for various times. Aliquots were then cultured in monolayers of McCoy cells, and inclusions were counted. A 7.5 mM concentration of 2-O-octyl-sn-glycerol completely prevented growth of C. trachomatis after 120 min of contact with the organism. The remaining lipids, 1-O-octyl-, 1-O-heptyl-, 2-O-hexyl-, and 1-O-hexyl-sn-glycerol, showed less activity. On electron microscopic examination, the lipids were shown to have disrupted the chlamydial inner membrane, allowing leakage of the cytoplasmic contents from the cell. Lipid activity was unaffected by the presence of 10% human blood or alterations in pH from 4.0 to 8.0, conditions reflecting those sometimes found in the vagina. Our results suggest that these lipids, especially 2-O-octyl-sn-glycerol, may be effective as topical microbicides in preventing the transmission of C. trachomatis. Further efficacy and toxicity studies with these lipids and assessment of their activity against other sexually transmitted disease pathogens are in progress.     

Reliable component analysis through maximizing composite reliability.

Reliable component analysis (RCA) provides (a) the weights that construct the most reliable linear composite of a battery's variables, (b) additional sets of weights that give the most reliable composites, uncorrelated with the first and each other, and (c) the reliabilities of each composite. The composites can be used to give factor loadings for the variables on the corresponding components. RCA is a promising method for exploratory factor analysis, because the components' reliabilities can provide a rational basis for the number of factors to rotate. The similarities and differences of component and common factor models are sketched. Artificial and real data are analyzed to illustrate RCA and suggest how its results may differ from those of other methods. Appropriate use of RCA rests on having good reliability estimates. Computations of RCA in a macro computer language are described. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential modulation diversity

In this paper, differential modulation diversity (DMD) is introduced. This diversity scheme is based on diagonal signal constellations which have been previously proposed for differential space-time modulation (DSTM). DMD can exploit both space and time diversity and DSTM, which is a pure space-diversity scheme, results as a special case. Low-complexity noncoherent receivers originally designed for DSTM are adapted to DMD and the power efficiency of DMD for Ricean fading with spatial correlation and imperfect interleaving is investigated. Based on analytical expressions for the pairwise error probability it is shown that space diversity increases the effective fading bandwidth, which has a negative influence on performance. Time diversity does not have this disadvantage and is preferable especially for fast fading channels. If space and time diversity are combined, a robust receiver results that yields high performance for a wide range of fading velocities.     

An efficient method for joint hypocenter determination for large groups of earthquakes

The number of seismic events that can be located simultaneously by the Joint Hypocenter Determination method is limited generally by the amount of computer time and computer memory available. To find directly the hypocenters of M earthquatkes and the station corrections to N stations requires solving a system of 4M + N equations in 4M + N unknowns. This paper presents a method of solving this system of equations which is considerably more efficient than Guassian elimination.     

Neurturin and GDNF promote proliferation and survival of enteric neuron and glial progenitors in vitro

Signaling through the c-Ret tyrosine kinase and the endothelin B receptor pathways is known to be critical for development of the enteric nervous system. To clarify the role of these receptors in enteric nervous system development, the effect of ligands for these receptors was examined on rat enteric neuron precursors in fully defined medium in primary culture. In this culture system, dividing Ret-positive cells differentiate, cluster into ganglia containing neurons and enteric glia, and create extensive networks reminiscent of the enteric plexus established in vivo. Glial cell-line-derived neurotrophic factor (GDNF) and neurturin both potently support survival and proliferation of enteric neuron precursors in this system. Addition of either neurturin or GDNF to these cultures increased the number of both neurons and enteric glia. Persephin, a third GDNF family member, shares many properties with neurturin and GDNF in the central nervous system and in kidney development. By contrast, persephin does not promote enteric neuron precursor proliferation or survival in these cultures. Endothelin-3 also does not increase the number of enteric neurons or glia in these cultures.