大鼠侧脑室注射精氨酸加压素对针刺镇痛的影响

以钾离子透入法引起大鼠甩尾反应为指标,测定动物的痛阈。由侧脑室注射精氮酸加压素(AVP)后,大鼠痛阈升高33.6％～68.5％,针刺镇痛效应明显加强,痛阈提高202.4％～302.7％。脑室注射抗精氨酸加压素血清,动物痛阈虽无明显变化,但针刺镇痛效应明显削弱,痛阈仅增加41.6％～71.0％。注射抗β-内啡肽血清和抗强啡肽A血清并不阻断AVP增强针刺镇痛效应。本工作的结果提示,脑内AVP参与针刺镇痛,这种作用与脑内内源性β-内啡肽和强啡肽的关系不甚密切。     

棉花耐害补偿临界指标及其应用的探讨

棉花耐害补偿反应可归纳为三种动态类型：1)不足补偿动态反应型;2)完全——不足补偿动态反应型;3)超越——完全——不足补偿动态反应型。其临界指标的建立及其应用可优化棉花病虫害综防决策．以研究害虫防治决策为例,剖析了利用害虫自然种群,人为改变害虫自然种群、人为地接放一定虫量与人工损害模拟等不同测定棉花耐害补偿能力方法的利弊。并探讨改进措施．分析论述了不同量化棉花耐害补偿能力的方法,并就棉花耐害补偿临界指标的建立及其意义作了探讨．棉花耐害补偿临界描标在棉田生态系统有害生物综合治理中可用于指导防治决策或直接用于防治决策,有着十分广阔的应用前景．最后就棉花耐害补偿临界指标及其应用的研究方向及有关问题作了讨论。     

豆突眼长蝽发育起点温度和有效积温的研究

在恒温条件下 ,观察了不同温度对豆突眼长蝽ChauliopsfallaxScott生长发育的影响 ,用直接最优法和直线回归法分析数据 ,结果表明直接最优法能较好地反应实际情况。卵、1～ 5龄若虫和整个若虫期的发育起点温度分别为 7 98℃ ,7 1 6℃ ,6 5 3℃ ,8 81℃ ,6 75℃ ,8 2 7℃和 7 5 0℃ ,有效积温分别为85 8,60 8,5 2 0 ,71 4,1 0 1 5 ,66 3和 3 5 3 0日·度 ,发育速率最大时的温度分别为 3 4 84℃ ,3 4 48℃ ,3 4 1 6℃ ,3 4 1 2℃ ,3 4 75℃ ,3 5 1 1℃和 3 3 65℃。     

Infection, reinfection, and vaccination under suboptimal immune protection: epidemiological perspectives

The SIR (susceptible-infectious-resistant) and SIS (susceptible-infectious-susceptible) frameworks for infectious disease have been extensively studied and successfully applied. They implicitly assume the upper and lower limits of the range of possibilities for host immune response. However, the majority of infections do not fall into either of these extreme categories. We combine two general avenues that straddle this range: temporary immune protection (immunity wanes over time since infection), and partial immune protection (immunity is not fully protective but reduces the risk of reinfection). We present a systematic analysis of the dynamics and equilibrium properties of these models in comparison to SIR and SIS, and analyse the outcome of vaccination programmes. We describe how the waning of immunity shortens inter-epidemic periods, and poses major difficulties to disease eradication. We identify a "reinfection threshold" in transmission when partial immunity is included. Below the reinfection threshold primary infection dominates, levels of infection are low, and vaccination is highly effective (approximately an SIR model). Above the reinfection threshold reinfection dominates, levels of infection are high, and vaccination fails to protect (approximately an SIS situation). This association between high prevalence of infection and vaccine failure emphasizes the problems of controlling recurrent infections in high-burden regions. However, vaccines that induce a better protection than natural infection have the potential to increase the reinfection threshold, and therefore constitute interventions with a surprisingly high capacity to reduce infection where reduction is most needed.     

优雅蝈螽与暗褐蝈螽精子束的显微观察

本文应用微分干涉相衬法对优雅蝈螽Ｇampsocleis gratiosa Brunner von Wattenwyl和暗褐蝈螽G. sedakovii （Fischer von Waldheim） 雄性精巢管基部、输精管、贮精囊和精包,及雌性受精囊中精子束的形态变化进行了观察,对探讨螽斯近缘种的生殖隔离机制和生殖生物学具有重要意义.结果表明：这两种蝈螽的精子束通过精包转移到雌性受精囊后,精子束的形态发生了显著变化.精巢管基部的精子为游离的单个精子;输精管、贮精囊和精包中精子成束排列形成较分散的精子束,精子束头部包裹有粘液帽;雌性受精囊中的精子束的精子呈羽状排列,精子的头部汇集在中央轴上.两种蝈螽精子束形态差异不显著.     

Genetic variation underlying the expression of a polyphenism

Polyphenic traits are widespread and represent a conditional strategy sensitive to environmental cues. The environmentally cued threshold (ET) model considers the switchpoint between alternative phenotypes as a polygenic quantitative trait with normally distributed variation. However, the genetic variation for switchpoints has rarely been explored empirically. Here, we used inbred lines to investigate the genetic variation for the switchpoint in the mite Rhizoglyphus echinopus, in which males are either fighters or scramblers. The conditionality of male dimorphism varied among inbred lines, indicating that there was genetic variation for switchpoints in the base population, as predicted by the ET model. Our results also suggest a mixture between canalized and conditional strategists in R. echinopus. We propose that major genes that canalize morph expression and affect the extent to which a trait can be conditionally expressed could be a feature of the genetic architecture of threshold traits in other taxa.     

外源性的电磁干预对神经病理性疼痛大鼠的镇痛效果研究

目的:探讨外源性的电磁干预方法对神经病理性疼痛大鼠的镇痛效果。方法:将30只成熟的雄性SD大鼠随机等分成3组:空白对照组(Control),坐骨神经慢性压迫损伤(CCI)组以及坐骨神经慢性压迫损伤协同电磁刺激组(CCI+EMF)。CCI组和CCI+EMF组的20只大鼠建立坐骨神经慢性压迫损伤模型,CCI+EMF组大鼠行外源性的全身性电磁刺激干预(脉冲波形,频率15 Hz,强度30 Gs),每天刺激6小时。在CCI模型构建的第0、3、6、9、12及15天对大鼠测试和比较足底机械痛阈值、足底热痛阈值、运动功能评分和神经传导速率。结果:CCI组大鼠的足底机械痛阈值、足底热痛阈值及感觉神经传导速率从CCI手术后的第3天即出现显著性降低,其6、9、12、15天足底机械痛阈值、足底热痛阈值及感觉神经传导速率均显著低于Control组(P0.01),而运动功能评分均显著高于Control组(P0.05)。CCI+EMF组大鼠的足底机械痛阈值、足底热痛阈值及感觉神经传导速率在第9、12、15天显著高于CCI组大鼠(P0.05),而运动功能评分均显著高于CCI l组。结论:外源性的电磁刺激对于神经病理性疼痛大鼠具有良好的镇痛效果,有望成为一种临床治疗神经病理性疼痛的新的物理治疗手段。     

Error threshold in RNA quasispecies models with complementation

A general assumption of quasispecies models of replicons dynamics is that the fitness of a genotype is entirely determined by its sequence. However, a more biologically plausible situation is that fitness depends on the proteins that catalyze metabolic reactions, including replication. In a stirred population of replicons, such as viruses replicating and accumulating within the same cell, the association between a given genome and the proteins it encodes is not tight as it can be replicated by proteins translated from other genomes. We have investigated how this complementation phenomenon affects the error threshold in simple quasispecies mean field models. We first studied a model in which the master and the mutant genomes code for wild-type and mutant replicases, respectively. We assume that the mutant replicase has a reduced activity and that the wild-type replicase does not have increased affinity for the master genome. The whole pool of replicases can bind and replicate both genomes. We then analyze a different model considering a more extreme case of mutant genomes, the defective interfering particles (DIPs) described in many cases of viral infection. DIPs, with a higher replication rate owed to their shorter genomes, do not code for replicase, but they are able of using the replicase translated from the master genome. Our models allow to study how the probability of interaction between the genomes and the whole pool of replicases affects the error threshold. In both systems we characterize the scenario of coexistence between master and mutant genomes, providing the critical values of mutation rate, μ_c, and the critical interaction rate between master genomes and replicases, γ_c, at which the quasispecies enters into error catastrophe, a situation in which the mutant genomes dominate the population. In both cases, we showed that the error-threshold transition is given by transcritical-like bifurcations, suggesting a continuous phase transition. We have also found that the region in the parameter space (μ,γ) in which the master sequence survives is reduced when DIPs are introduced into the system.     

Epidemics with partial immunity to reinfection

We obtain analytical results about epidemics generated by the partial immunity model of Gomes et al. [3], in which infection confers partial immunity to reinfection. When the demographic process is excluded, the behavior switches from epidemic to endemic as the basic reproduction number R₀ crosses the reinfection threshold . We derive formulas for two quantities characterizing the size of the epidemic below the reinfection threshold: the attack rate A, which is the fraction of the population infected at least once, and the final size Z, which is the average number of infections per individual. We also derive a system of differential equations which can be used to obtain more detailed information, such as the fraction of the population infected n times throughout the epidemic, for every n.     

Electromyographic correlates of the transition from aerobic to anaerobic metabolism in treadmill running

This study analysed the changes in electromyographic (EMG) activity of the vastus lateralis, biceps femoris and gastrocnemius muscles during incremental treadmill running. The changes in EMG were related to the lactate and ventilatory thresholds. Ten trained subjects participated in the study. Minute ventilation, oxygen consumption, carbon dioxide expired and the fraction of oxygen in the expired gas were recorded continuously. Venous blood samples were collected at each exercise intensity and analysed for lactate concentration. The EMG were recorded at the end of each exercise intensity using surface electrodes. The EMG were quantified through integration (iEMG) and by calculating the mean power frequency (MPF). The iEMG measurements were characterized by a breakpoint in the vastus lateralis and/or gastrocnemius muscles in eight of the subjects tested. However, the results indicated that blood lactate concentrations had already begun to increase in a nonlinear fashion before the iEMG breakpoint had been surpassed. Consequently, the occurence of the lactate threshold cannot be attributed solely to the change in motor unit recruitment or rate coding patterns demonstrated by the iEMG breakpoint. The ventilatory threshold was shown to be a far more reliable and convenient noninvasive predictor of the lactate threshold in comparison with EMG techniques. In conclusion, the EMG measurements used in this study (i.e. iEMG and MPF) were not considered to be viable noninvasive determinants of the aerobic-anaerobic transition phase in treadmill running.