彩色多普勒超声测量椎动脉血流量对后循环缺血的诊断价值

目的：探讨彩色多普勒超声技术测量椎动脉血流量对后循环缺血（PCI）的诊断价值。方法：选取2012年1月至2013年1月在本院神经内科住院并接受治疗的PCI患者58例作为观察组,另选取同期住院并确诊为非后循环缺血症的患者50例作为对照组。所有患者均接受颈部血管超声检查,测量椎动脉内径及血流量,观察组患者需行头颅CTA检查,比较两组患者的椎动脉内径、血流量及颈动脉硬化斑块发生率等。结果：观察组患者的椎动脉内径及血流量明显低于对照组,两组比较差异有统计学意义（P〈0．01）;观察组颈动脉硬化斑块的发生率为77．5％（44例）,对照组颈动脉硬化斑块的发生率为42％（21例）,两组比较差异有统计学意义（P〈0．05）。无狭窄、轻度狭窄、重度狭窄及闭塞的椎动脉血流量的变化（此处所指的血流量是指小于200mL/min那部分患者）有明显差异（P〈0．05）。结论：与头颅CTA对比检查,彩色多普勒具有直接、准确、方便及可重复性等优点,可有效的诊断后循环缺血症状。     

Cohesin结构及功能研究进展

Cohesin是一类在真核生物进化过程中保守的蛋白复合体,由4个重要亚基相互作用形成环状结构,在细胞分裂过程中参与维持染色体的有序排布。在动物中研究发现cohesin还可以作为分子间的连结器介导绝缘子/增强子–启动子间长距离交互,导致基因表达增强或者抑制,但在植物中关于cohesin在调控基因表达和维持染色体构象方面的研究却相对滞后。本文介绍了cohesin的结构特点和主要组成亚基,对调控cohesin在染色质上动态变化的相关因子进行了总结,并结合近年来植物中cohesin的功能研究和动物中cohesin在三维基因组及转录调控中的重要作用,展望了植物中cohesin在转录调控中的潜在功能。     

Zoo soundscape: Daily variation of low-to-high-frequency sounds

Most studies assessing the impact of noises on zoo animal welfare did not measure sound frequencies outside of the human-hearing range (infrasounds and ultrasounds). Many nonhuman mammals can hear these frequencies, and because loud and variable soundscapes are potentially detrimental for animal welfare, this overlooked aspect of their acoustic environment could have important consequences. This study evaluated the soundscape of an urban zoo in a large frequency range (17.5–90,510 Hz) by measuring its average sound levels (L_eq) and variability (the difference between highest and lowest peaks). Sound data were collected for 24 hr in 25 locations (e.g., indoor, outdoor, near the amusement park). The soundscape was not considered problematic for animal welfare when looking at the average sound levels in most locations (<77-dB sound pressure level [SPL]), except for a few indoor areas and near the water park. Ultrasounds were rare, had low average sound levels, and were less variable in time. Infrasounds were always present and were the loudest and most variable sound frequencies. The soundscape was louder and more variable during the day and when visitors were present, suggesting that human-related activities were the sources of these augmentations. Indoor environments were generally louder than outdoor environments and touristic features; however, the water park was near 85-dB SPL during the day. On the basis of results, we suggest a series of mitigation actions to minimize noise-related stress in captive animals.     

Two Alternative Conformations of a Voltage-Gated Sodium Channel

Activation and inactivation of voltage-gated sodium channels (Navs) are well studied, yet the molecular mechanisms governing channel gating in the membrane remain unknown. We present two conformations of a Nav from Caldalkalibacillus thermarum reconstituted into lipid bilayers in one crystal at 9 Å resolution based on electron crystallography. Despite a voltage sensor arrangement identical with that in the activated form, we observed two distinct pore domain structures: a prominent form with a relatively open inner gate and a closed inner-gate conformation similar to the first prokaryotic Nav structure. Structural differences, together with mutational and electrophysiological analyses, indicated that widening of the inner gate was dependent on interactions among the S4–S5 linker, the N-terminal part of S5 and its adjoining part in S6, and on interhelical repulsion by a negatively charged C-terminal region subsequent to S6. Our findings suggest that these specific interactions result in two conformational structures.     

Three-Dimensional Structure of CAP-Gly Domain of Mammalian Dynactin Determined by Magic Angle Spinning NMR Spectroscopy: Conformational Plasticity and Interactions with End-Binding Protein EB1

Microtubules and their associated proteins play important roles in vesicle and organelle transport, cell motility and cell division. Perturbation of these processes by mutation typically gives rise to severe pathological conditions. In our efforts to obtain atomic information on microtubule-associated protein/microtubule interactions with the goal to understand mechanisms that might potentially assist in the development of treatments for these diseases, we have determined the three-dimensional structure of CAP-Gly (cytoskeleton-associated protein, glycine-rich) domain of mammalian dynactin by magic angle spinning NMR spectroscopy. We observe two conformations in the β2 strand encompassing residues T43-V44-A45, residues that are adjacent to the disease-associated mutation, G59S. Upon binding of CAP-Gly to microtubule plus-end tracking protein EB1, the CAP-Gly shifts to a single conformer. We find extensive chemical shift perturbations in several stretches of residues of CAP-Gly upon binding to EB1, from which we define accurately the CAP-Gly/EB1 binding interface. We also observe that the loop regions may exhibit unique flexibility, especially in the GKNDG motif, which participates in the microtubule binding. This study in conjunction with our previous reports suggests that conformational plasticity is an intrinsic property of CAP-Gly likely due to its unusually high loop content and may be required for its biological functions.     

响应面法优化超声辅助提取太子参多糖工艺研究

本文探讨超声波作用下太子参多糖提取的最佳工艺条件。在单因素试验基础上,采用响应面法对太子参多糖提取工艺参数进行优化研究。响应面试验表明提取温度、提取时间和水料比对响应值多糖提取得率均有显著影响,优化得到太子参多糖超声提取最佳工艺条件为:提取温度为74℃;提取时间为65 min;水料比为26 mL/g;超声波功率100 W。在此条件下太子参多糖的提取得率为2.48%,与模型预测值非常接近。     

IDENTIFICATION OF BRITISH BAT SPECIES BY MULTIVARIATE ANALYSIS OF ECHOLOCATION CALL PARAMETERS

ABSTRACT

Previous studies have found variability and individual distinctiveness in the echolocation calls of bats. We consider two implications of individually distinct echolocation calls: 1) whether bats may be able to use such variation to recognise familiar conspecifics, and 2) whether investigators could use such variation to identify known individuals or to census populations. We compared the discriminability of the echolocation calls of big brown bats (Eptesicus fuscus) recorded in three situations: (a) while held in the hand, (b) while perched on a platform, and (c) while flying in an anechoic chamber. Using variables describing each sonar call, we employed discriminant function analysis (DFA) to assign calls to recording situation or to bat. Discrimination of calls by recording situation was largely unsuccessful, although flying calls could be distinguished from platform calls. Assignment of calls to individual bat across recording situations yielded 72% success, and, within a given recording situation, yielded 87% success. Stepwise DFA reduced the number of variables needed to discriminate between individuals with only a slight decrease in correct classification. These results suggest that bats (or researchers) may be able to use the information contained in the echolocation calls for individual recognition. Individual distinctiveness raises the possibility of censusing bats by sound. We used cluster analysis in an attempt to determine whether, given a sample of calls from an unknown number of bats, a reasonable estimate of the number of bats could be obtained. Results were unsatisfactory, suggesting that cluster analysis probably will not permit acoustic censusing of bats in the field.     

高强度聚焦超声在药物控制释放的应用及进展

高强度聚焦超声能够以一种非侵入性的方式有效地穿透身体内部组织,聚焦在深层组织中一个很小的空间区域内,产生很强的声能,这些能量被组织吸收引起局部温度的升高。当温度到达热敏脂质体的相变温度时,磷脂烷基链构象的会发生改变,导致脂质体的通透性增强,从而能够促进药物的释放。因此,高强度聚焦超声可以被用作外源刺激控制体内特定位置热敏脂质体的药物释放。本文对高强度聚焦超声在药物控制释放领域的应用及进展进行综述。