Synaptic transmission of chaotic spike trains between primary afferent fiber and spinal dorsal horn neuron in the rat

Primary sensory neurons can generate irregular burst firings in which the existence of significant deterministic behaviors of chaotic dynamics has been proved with nonlinear time series analysis. But how well the deterministic characteristics and neural information of presynaptic chaotic spike trains were transmitted into postsynaptic spike trains is still an open question. Here we investigated the synaptic transmission of chaotic spike trains between primary Adelta afferent fiber and spinal dorsal horn neuron. Two kinds of basic stimulus unit, brief burst and single pulse, were employed by us to comprise chaotic stimulus trains. For time series analysis, we defined "events" as the longest sequences of spikes with all interspike intervals less than or equal to a certain threshold and extracted the interevent intervals (IEIs) from spike trains. Return map analysis of the IEI series showed that the main temporal structure of chaotic input trains could be detected in postsynaptic output trains, especially under brief-burst stimulation. Using correlation dimension and nonlinear prediction methods, we found that synaptic transmission could influence the nonlinear characteristics of chaotic trains, such as fractal dimension and short-term predictability, with greater influence made under single-pulse stimulation. By calculating the mutual information between input and output trains, we found the information carried by presynaptic spike trains could not be completely transmitted at primary afferent synapses, and that brief bursts could more reliably transmit the information carried by chaotic input trains across synapses. These results indicate that although unreliability exists during synaptic transmission, the main deterministic characteristics of chaotic burst trains can be transmitted across primary afferent synapses. Moreover, brief bursts that come from the periphery can more reliably transmit neural information between primary afferent fibers and spinal dorsal horn neurons.     

Update on Pneumocystis carinii f. sp. hominis Typing Based on Nucleotide Sequence Variations in Internal Transcribed Spacer Regions of rRNA Genes

Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study.     

cis-Acting packaging motifs of porcine adenovirus type 3

The cis-acting packaging domain is required for selective encapsidation of adenovirus DNA into preformed empty capsids late in the viral life cycle. Earlier, it was demonstrated that the cis-acting packaging domain of porcine adenovirus type (PAdV)-3 is located between nucleotide position (nt) 212 and 531 at the left end genome which contains six AT/GC rich motifs. Removal of packaging domain from left end to the right end of the genome produced a viable mutant virus suggesting that the identified cis-acting packaging domain represents the DNA sequences required for selective packaging of PAdV-3 DNA, whose position and orientation appear to be flexible. Here, by constructing and analyzing a panel of virus mutants carrying deletions or linker scanning mutations in AT/GC rich sequences, we examined the significance of the continuous A/T or G/C sequences individually in the viral packaging process. In contrast to consensus bipartite structure (5'-TTTGN8CG-3') described for most of packaging motifs of human adenovirus type 5 (HAdV-5), the packaging motifs I, II, III, and IV of PAdV-3 displayed a tripartite structure in which the continuous A/T nucleotides were flanked by G/C-rich sequences. Mutations in both continuous A/T nucleotides and its flanking GC-rich sequences reduced the packaging efficiency of mutants to varying degrees. In addition, although the continuous A/T sequences were present in all of the packaging motifs, their significance in the packaging process appears to vary within each packaging motif.     

大鼠脑干神经元型一氧化氮合酶免疫阳性神经元的分布

目的　观察大鼠脑干神经元型一氧化氮合酶 (nNOS)免疫阳性神经元的分布 ,为探讨nNOS的作用提供形态学资料。方法　用ABC免疫细胞化学方法显示脑干nNOS免疫阳性神经元。结果　大鼠脑干nNOS免疫阳性神经元以中脑和脑桥分布丰富 ,延髓较稀少 ;在中脑 ,nNOS免疫阳性神经元主要分布于中脑水管周围灰质的背侧部、被盖背外侧核、中缝背核、上下丘灰质等部位 ;在脑桥 ,主要分布于被盖背外侧核、脑桥中缝核、被盖脚桥核、蓝斑、臂旁核、斜方体核 ,以及脑桥网状结构 ;与中脑和脑桥相比 ,延髓nNOS免疫阳性神经元较少 ,主要分布于延髓网状结构、三叉神经脊束核和孤束核等核团。结论　分布于脑干内丰富的nNOS免疫阳性神经元可能通过其生成的NO调节其他神经递质的分泌 ,共同参与内脏活动、感觉和运动的传导 ,以及睡眠和觉醒等脑的高级整合功能的调节。     

颈椎前路椎体间微创融合器的生物力学实验研究

目的评价植入镍钛记忆合金微创融合器(NiTi-TFC/C)的颈椎节段的稳定性及压缩力学性能。方法采集24只羊颈椎标本随机分为4组,每组6份,四组处理分别为:单取髓核组、自体髂骨植骨组、微创融合器组和钛制融合器组(InterFix)。所有标本进行前路减压,并对后3组进行椎间融合术。分别对各组标本进行生物力学测试并进行比较。结果微创融合器组与钛制融合器组在强度、刚度及扭转力学等方面无显著性差异(P>0.05)。而微创融合器组与自体髂骨植骨组具有显著性差异(P<0.05)。最大承载力为12050N。结论该微创融合器强度大、刚度高、抗扭转能力强,具有良好的抗压能力,为颈椎融合提供新型的融合装置。     

基于电刺激的外层型人工视网膜的研究进展

外层型视网膜假体采用了MEMS技术,通过植入到视网膜相应部位的电极来刺激神经节细胞,并且能够在大脑皮层视觉区域引起对应的特征电位反应,最终部分恢复生物体的视觉.这种外层型视网膜植入装置可分为眼外和眼内部分.后者功能相对重要,设计也较为复杂.它是由包含MPDA和微电极的刺激芯片及附属装置组成.本篇文章主体包括四部分:首先是视网膜假体的概况;其次是视网膜生理基础和视网膜假体理论的简介;在第三部分,为设计理念和MPDA的制造过程;最后,是对难题的讨论和未来发展的展望.     

Intra-articular IL-10 gene transfer regulates the expression of collagen-induced arthritis (CIA) in the knee and ipsilateral paw

We studied the effects of local IL-10 application, introduced by a recombinant human type 5 adenovirus vector, in the mouse knee joint during the early phase of CIA. One intra-articular injection with the IL-10-expressing virus (Ad5E1mIL-10) caused substantial over-expression of IL-10 in the mouse knee joint, using virus dosages which did not induce distracting inflammation. High expression of IL-10 was noted for a few days, being maximal at day 1. One intra-articular injection of Ad5E1mIL-10 in the knee joints of collagen type II (CII)-immunized mice, before onset of CIA was noted, reduced the incidence of collagen arthritis in that knee. Of high interest, the protective effect of local IL-10 expression by Ad5E1mIL-10 was not restricted to the knee joint alone. The arthritis incidence in the ipsilateral paw was highly suppressed. In contrast, local IL-10 over-expression was not effective when treatment was started after onset of CIA. Further analysis in the acute streptococcal cell wall-induced arthritis model revealed that local IL-10 over-expression markedly suppressed the production of tumour necrosis factor-alpha (TNF-alpha) and IL-1alpha, but had no significant effect on IL-1beta and IL-12 production in the inflamed synovium. These data indicate that local over-expression of IL-10 in the knee joint of mice regulates the expression of collagen arthritis, probably through down-regulation of TNF-alpha.     

Determination of Copy Number of rRNA Genes in Pneumocystis carinii f. sp. hominis

Differential PCR was performed to determine the copy number of rRNA genes in Pneumocystis carinii f. sp. hominis. Two different reference genes, thymidylate synthase (TS) and beta-tubulin (BTU) genes, were used. Primers for the internal transcribed spacer (ITS) region of nuclear rRNA genes and either the TS or BTU gene were mixed together to perform PCR on seven different bronchoalveolar lavage specimens from patients with P. carinii pneumonia. The radioactivity derived from the incorporated radioactive nucleotides of each PCR product band was then used to calculate the copy number of the ITS relative to that of the TS or BTU gene. The copy number ratio between the ITS and the TS gene was determined to be 0.8, and that between the ITS and the BTU gene was also 0.8. These results suggest that the ITS has the same copy number as the TS or BTU gene. Since the copy number of the TS or BTU gene is presumed to be 1, the results also suggest that P. carinii f. sp. hominis has only one copy of the ITS and thus one copy of the nuclear rRNA genes. Therefore, two types of ITS sequences derived from a specimen would indicate that the patient is infected by two types of P. carinii f. sp. hominis.