Neurokinins enhance excitability in capsaicin-responsive DRG neurons

Neurokinins released by capsaicin-responsive (C-R) dorsal root ganglia neurons (DRG) may control firing in these neurons by an autofeedback mechanism. Here we used patch clamp techniques to examine the effects of neurokinins on firing properties of dissociated DRG neurons of male rats. In C-R neurons that generated only a few action potentials (APs, termed phasic) in response to long depolarizing current pulses (600 ms), substance P (SP, 0.5 microM) lowered the AP threshold by 11.0+/-0.3 mV and increased firing from 1.1+/-0.7 APs to 5.2+/-0.6 APs. In C-R tonic neurons that fire multiple APs, SP elicited smaller changes in AP threshold (6.0+/-0.1 mV reduction) and the number of APs (11+/-1 vs. 9+/-1 in control). The effects of SP were similar to the effect of heteropodatoxin II (0.05 microM) or low concentrations of 4-aminopyridine (50 microM) that block A-type K(+) currents. A selective NK(2) agonist, [betaAla(8)]-neurokinin A (4-10) (0.5 microM), mimicked the effects of SP. The effects of SP in C-R phasic neurons were fully reversed by an NK(2) receptor antagonist (MEN10376, 0.5 microM) but only partially by a protein kinase C (PKC) inhibitor (bisindolylmaleimide, 0.5 microM). An NK(3)-selective agonist ([MePhe(7)]-neurokinin B, 0.5 microM), an NK(1)-selective agonist ([Sar(9), Met(11)]-substance P, 0.5 microM) or activation of PKC with phorbol 12,13-dibutyrate (0.5 microM) did not change firing. Our data suggest that the excitability of C-R phasic afferent neurons is increased by activation of NK(2) receptors and intracellular signaling mediated only in part by PKC.     

The myelin-associated glycoprotein inhibitor BENZ induces outgrowth and survival of rat dorsal root ganglion cell cultures

The novel myelin-associated glycoprotein (MAG) inhibitor BENZ binds to the N-acetylneuraminic acid (Neu5Ac) portion of the N-terminal Ig-like domain of MAG. Treatment of rat dorsal root ganglion (DRG) cell cultures with BENZ-induced outgrowth of neurofilament 200-positive neurites improved survival of neurons and increased the number of GFAP-positive cells, as determined by fluorescence and confocal laser microscopy and by Western immunoblotting. Furthermore, treatment of DRG cell cultures with BENZ repressed gene and protein expression of the small GTPase RhoA but induced expression of Rho GTP-activating proteins 5 and 24, likely to counteract protein kinase A activity. Specifically, expression of inhibitors of neurite outgrowth, for example, Rock2 and PAK4, was repressed, but cofilin 1, a promoter of axonal growth, was induced. We propose that the MAG inhibitor BENZ abrogates the RhoA-ROCK-cofilin pathway to promote neurite outgrowth. Our findings require confirmation by in vivo animal studies.     

小鼠背根神经节中三个不同的钙激活氯离子通道基因家族的表达

目的在背根神经节（dorsalrootganglion,DRG）中等大小感觉神经元中可以观察到钙激活氯离子流（ICl（Ca））。在坐骨神经损伤模型中,在大多数大中神经元上诱导出类似的氯离子流。本文旨在探讨引起这个离子流的分子基础。方法使用常规的定量RT-PCR方法检测在DRG中三个基因家族的表达,这三个基因家族都具有诱导,ICl（Ca）的特点。结果在成年小鼠的DRG中,分别显示了在正常状态和坐骨神经损伤3天后CLCA,Bestrophin和Tweety基因家族成员的转录产物。结论mBestl和Tweety2可能在损伤诱导的DRG神经元,ICl（Ca）中发挥作用。     

酪氨酸激酶受体EphA5及其配体ephrin-A5在小鼠脊髓发育过程中的表达

目的研究两个Eph家族分子,EphA5受体及其配体ephrin—A5,在脊髓发育过程中的表达方式。方法β-半乳糖苷酶基因敲入小鼠和配体亲和探针分析受体的表达,两种不同的亲和探针分析配体的表达,基因敲除小鼠作为对照。结果在发育过程中,EphA5表达于脊髓腹侧,而ephrin—A5表达于脊髓背侧。结论EphA5和ephrin—A5在多个脊髓发育阶段都有表达,他们可能在脊髓背腹侧组织结构的建立过程中发挥重要作用。     

Oxygenation failure during cardiopulmonary bypass prompts new safety algorithm and training initiative

Developing new strategies to improve patient safety and risk reduction is fundamental to hospital and patient success. Currently, there is a tendency in hospital safety management to focus solely on human error rather than organizational and educational causes that contribute to medical accidents. Although health care providers are the primary safety systems in medical facilities, there must be a more global, perhaps automated, approach using modern technology to prevent or reduce medical mishaps. Herein, we present an oxygenation failure with root cause analysis that prompted a new oxygenation safety algorithm and multi-service training initiative.     

人胚胎背根神经节雪旺氏细胞的培养

BACKGROUND： Previous studies have used many methods for in vitro Schwann cells （SCs） cultures and purification, such as single cell suspension and cytosine arabinoside. However, it has been difficult to obtain sufficient cellular density, and the procedures have been quite tedious. OBJECTIVE： To investigate the feasibility of culturing high-density SCs using fetal human dorsal root ganglion tissue explants. DESIGN, TIME AND SETTING： Cell culture and irnmunohistochernistry were performed at the Central Laboratory of Kunrning General Hospital of Chinese PLA between March 2001 and October 2008. MATERIALS： Culture media containing 10% fetal bovine serum, as well as 0.2% collagenase and 0.25% trypsin were purchased from Gibco, USA; mouse anti-human S-100 monoclonal antibody and goat anti-mouse IgG labeled with horseradish peroxidase were provided by Beijing Institute of Biological Products, China. METHODS： Primarily cultured SCs were dissociated from dorsal root ganglia of human aborted fetuses at 4 6 months pregnancy. Following removal of the dorsal root ganglion perineurium, the ganglia were dissected into tiny pieces and digested with 0.2% collagenase and 0.25% trypsin （volume ratio 1：1）, then explanted and cultured. SC purification was performed with 5 rnL 10% fetal bovine serum added to the culture media, followed by differential adhesion. MAIN OUTCOME MEASURES： SCs morphology was observed under inverted phase contrast light microscopy. SC purity was evaluated according to percentage of S-100 immunostained cells. RESULTS： SCs were primarily cultured for 5 6 days and then subcultured for 4 5 passages. The highly enriched SC population reached 〉 95% purity and presented with normal morphology. CONCLUSION： A high purity of SCs was obtained with culture methods using human fetal dorsal root ganglion tissue explants.     

Inhibition of P2X receptor-mediated inward current by protein kinase C in small-diameter dorsal root ganglion neurons of adult rats

Objective

The aim of the present study is to verify the ATP-induced varied responses in isolated dorsal root ganglion (DRG) neurons of the adult rat, and investigate the modulatory effects of specific P2X receptor agonist β, γ-me-ATP and protein kinase C (PKC) on P2X receptor-mediated inward current in DRG neurons.

Methods

Whole cell patch-clamp was employed to record the currents on acutely isolated DRG neurons in the adult rats.

Results

β, γ-me-ATP, similar as ATP, evoked 2 distinct subtypes of P2X receptor-mediated inward currents in a dose-dependent manner in DRG neurons. Activation of PKC by phorbol 12,13-dibutyrate (PDBu) significantly inhibited both subtypes of inward currents mediated by P2X receptors in a dose-dependent manner.

Conclusion

Activation of PKC negatively modulated the P2X receptor-mediated currents in rat DRG neurons, which may be of benefit to preventing the over-excitation of nociceptor under inflammatory or neuropathic conditions.     

铸造金属桩核在残根残冠保存修复中的临床研究

目的：探讨铸造金属桩核在残根残冠保存修复中的方法和疗效,为临床修复提供参考。方法：回顾性分析我科于2009年3月至2010年3月抽取的残根残冠患者共100例120颗牙随机分为两组,其中实验组48例（60颗）,行铸造金属桩核修复。对照组52例（60颗）,行螺纹金属桩核修复。随访1月-1年,比较即时修复后两组患者的疗效及随访期间并发症的发生率。结果：两组患者即时修复后疗效比较,实验组的总有效率95%（包括显效和有效）高于对照组,差异有统计学意义（P〈0.05）。两组相比,随访期间实验组患者各项并发症指标均低于对照组,差异有统计学意义（P〈0.05）。结论：铸造金属桩核是残根残冠保存修复的有效方法,其能有效提高患者修复后的即时疗效,减轻修复后长短期内各项并发症的发生,应在临床口腔修复中推广使用。