Tracheal smooth muscle mechanics in vivo

We applied the technique of sonomicrometry to directly measure length changes of the trachealis muscle in vivo. Pairs of small 1-mm piezoelectric transducers were placed in parallel with the muscle fibers in the posterior tracheal wall in seven anesthetized dogs. Length changes were recorded during mechanical ventilation and during complete pressure-volume curves of the lung. The trachealis muscle showed spontaneous fluctuations in base-line length that disappeared after vagotomy. Before vagotomy passive pressure-length curves showed marked hysteresis and length changed by 18.5 +/- 13.2% (SD) resting length at functional residual capacity (LFRC) from FRC to total lung capacity (TLC) and by 28.2 +/- 16.2% LFRC from FRC to residual volume (RV). After vagotomy hysteresis decreased considerably and length now changed by 10.4 +/- 3.7% LFRC from FRC to TLC and by 32.5 +/- 14.6% LFRC from FRC to RV. Bilateral supramaximal vagal stimulation produced a mean maximal active shortening of 28.8 +/- 14.2% resting length at any lung volume (LR) and shortening decreased at lengths above FRC. The mean maximal velocity of shortening was 4.2 +/- 3.9% LR.S-1. We conclude that sonomicrometry may be used to record smooth muscle length in vivo. Vagal tone strongly influences passive length change. In vivo active shortening and velocity of shortening are less than in vitro, implying that there are significant loads impeding shortening in vivo.     

Canine trachealis muscle shortening and cartilage mechanics.

Canine trachealis muscle will shorten by 70% of resting length when maximally stimulated in vitro. In contrast, trachealis muscle will shorten by only 30-40% when stimulated in vivo. To examine the possibility that an elastic load applied by the tracheal cartilage contributes to the in vivo limitation of shortening, single pairs of sonomicrometry crystals were inserted into the trachealis muscle at the level of the fifth cartilage ring in five dogs. The segment containing the crystals was then excised and mounted on a tension-testing apparatus. Points on the active length-tension curve and the passive length-tension relation of the cartilage only were determined. The preload applied to the muscle before contraction varied from 10 to 40 g (mean 21 +/- 4 g). The afterload applied by the cartilage during trachealis contraction ranged from 13 to 56 g (30 +/- 6 g). The calculated elastic afterloads were substantial and appeared to be sufficient to explain the degree of shortening observed in four of the seven rings; in the remaining three rings, the limitation of shortening was greater than would be expected from the elastic load provided by the cartilage. Additional sources of loading and/or additional mechanisms may contribute to limited in situ shortening. In summary, tracheal cartilage applies a preload and an elastic afterload to the trachealis that are substantial and contribute to the limitation of trachealis muscle shortening in vivo.     

自然杀伤细胞在肿瘤免疫治疗中的作用

自然杀伤(NK)细胞是人体先天免疫的核心组成部分,是肿瘤细胞免疫治疗和抗体免疫治疗的基础.NK细胞通过直接杀伤作用和释放细胞因子来共同控制肿瘤的生长和转移.目前,已开发出多种利用激活的NK细胞治疗肿瘤的方案.然而,癌症患者的NK细胞功能受损,抗癌能力下降,均限制了NK 细胞的临床疗效 .新的方案通过提高NK细胞的数量和杀伤功能来改善治疗效果. 利用体外长期激活、大规模培养临床使用的NK细胞是达成上述效果的最佳方法之一. 本综述讨论了NK细胞研究背景,NK细胞治疗的现状,尤其是体外培养扩增具有较强功能NK细胞的新方案.     

Upland rice and lowland rice exhibited different P/P expression under water deficit and ABA treatment

Aquaporins play a significant role in plant water relations.To further understand the aquaporin function in plants underwater stress,the expression of a subgroup of aquaporins,plasma membrane intrinsic proteins(PIPs),was studied at boththe protein and mRNA level in upland rice(Oryza sativa L.cv.Zhonghan 3)and lowland rice(Oryza sativa L.cv.Xiushui63)when they were water stressed by treatment with 20% polyethylene glycol(PEG).Plants responded differently to20% PEG treatment.Leaf water content of upland rice leaves was reduced rapidly.PIP protein level increased markedlyin roots of both types,but only in leaves of upland rice after 10h of PEG treatment.At the mRNA level,OsPIP1;2,Os-PIP1;3,OsPIP2;1 and OsPIP2;5 in roots as well as OsPIP1;2 and OsPIP1;3 in leaves were significantly up-regulatedin upland rice,whereas the corresponding genes remained unchanged or down-regulated in lowland rice.Meanwhile,weobserved a significant increase in the endogenous abscisic acid(ABA)level in upland rice but not in lowland rice underwater deficit.Treatment with 60μM ABA enhanced the expression of OsPIP1;2,OsPIP2;5 and OsPIP2;6 in roots andOsPIP1;2,OsPIP2;4 and OsPIP2;6 in leaves of upland rice.The responsiveness of PIP genes to water stress and ABAwere different,implying that the regulation of PIP genes involves both ABA-dependent and ABA-independent signalingpathways during water deficit.     

不受欢迎的生物多样性：香港的外来植物物种

香港早在19世纪中叶开始就有外来植物入侵的记录,迄今为止,已发现多达238种已归化的外来或怀疑为外来的植物,其中又以薇甘菊（Mikania micrantha)、五爪金龙（Ipomoea cairica)、假臭草（Eupatorium catarium)、大黍（Panicum maximum)等最常见,外来植物最常见于受人为干扰的生境,例如荒废农田及路旁等,而较少在天然林地生境及贫瘠的灌草丛中发现,外来植物的对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少了生境及贫瘠的灌草丛中发现,外来植物对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少少了生境及动植物的多样性,外来动物对香港原生植物影响最大的是于20世纪70年代入侵的松树线虫（Bur-saphelenchus xylophilus)。外来的脊椎动物也有可能对香港的植物被演替产生影响,目前香港的外来植物当中,有些在大陆较少分布或没有记录,作为华南最大的港口,香港对外来物种的引入扮演着重要的角色,因此制定控制外来种在香港及华南地区的引入及传播的政策及措施非常重要。     

In vivo and in vitro correlation of trachealis muscle contraction in dogs.

Maximal trachealis muscle shortening in vivo was compared with that in vitro in seven anesthetized dogs. In addition, the effect of graded elastic loads on the muscle was evaluated in vitro. In vivo trachealis muscle shortening, as measured using sonomicrometry, revealed maximal active shortening to be 28.8 +/- 11.7% (SD) of initial length. Trachealis muscle preparations from the same animals were studied in vitro to evaluate isometric force generation, isotonic shortening, and the effect of applying linear elastic loads to the trachealis muscle during contraction from optimal length. Maximal isotonic shortening was 66.8 +/- 8.4% of optimal length in vitro. Increasing elastic loads decreased active shortening and velocity of shortening in vitro in a hyperbolic manner. The elastic load required to decrease in vitro shortening to the extent of the shortening observed in vivo was similar to the estimated load provided by the tracheal cartilage. We conclude that decreased active shortening in vivo is primarily due to the elastic afterload provided by cartilage.     

Inspiratory and expiratory muscle function during continuous positive airway pressure in dogs

Continuous positive airway pressure (CPAP) is known to produce activation of the expiratory muscles. Several factors may determine whether this activation can assist inspiration. In this study we asked how and to what extent expiratory muscle contraction can assist inspiration during CPAP. Respiratory muscle response to CPAP was studied in eight supine anesthetized dogs. Lung volume and diaphragmatic initial length were defended by recruitment of the expiratory muscles. At the maximum CPAP of 18 cmH2O, diaphragmatic initial lengths were longer than predicted by the passive relationship by 52 and 46% in the costal and crural diaphragmatic segments, respectively. During tidal breathing after cessation of expiratory muscle activity, a component of passive inspiration occurred before the onset of inspiratory diaphragmatic electromyogram (EMG). At CPAP of 18 cmH2O, passive inspiration represented 24% of the tidal volume (VT) and tidal breathing was within the relaxation characteristic. Diaphragmatic EMG decreased at CPAP of 18 cmH2O; however, VT and tidal shortening were unchanged. We identified passive and active components of inspiration. Passive inspiration was limited by the time between the cessation of expiratory activity and the onset of inspiratory activity. We conclude that increased expiratory activity during CPAP defends diaphragmatic initial length, assists inspiration, and preserves VT. Even though breathing appeared to be an expiratory act, there remained a significant component of active inspiratory diaphragmatic shortening, and the major portion of VT was produced during active inspiration.     

新疆石炭系杜内-韦宪阶界线层的牙形类POLYGNATHUS COM MUNIS GANCAOHUENSIS(新亚种)和POLYGNA-THUS COMMUNIS BRANSON ET MEHL 1934的种系发生(英文)

本文提出和描述了产自我国西北新疆南部喀拉塔克剖面的一个牙形类新亚种 Polygnathus communis gan-caohuensis,并根据以前出版的信息 ,命名了另一个新亚种 Polygnathus communis carmanae。种系发生研究揭示了Polygnathus communis Branson et Mehl的亚种对于法门阶最上部至韦宪阶地层的划分是至关重要的。此种的 cari-na→ gancaohuensis谱系 ,连同发现于喀拉塔克剖面的菊石、有孔虫和腕足动物 ,被认为是划分杜内 -韦宪阶界线的潜在的标志化石。因此 ,喀拉塔克剖面有可能成为全球杜内 -韦宪阶界线的一个候选层型剖面。