不同时间高压氧治疗对颅脑损伤患者认知功能障碍的影响

目的:探讨不同时间高压氧治疗对颅脑损伤患者认知功能障碍的影响。方法:选择了2006年5月-2015年5月在我院接受高压氧治疗的500例颅脑损伤手术或非手术患者,根据患者开始采取高压氧治疗时间的不同分为A(入院后7d内)、B(7-30 d)、C(30 d后)三组,通过相应的治疗比较三组患者认知功能评分、FIM评分及治疗效果。结果:高压氧治疗后,三组患者较治疗前都有了不同程度上的改善,但A组在定向能力、专注能力、理解能力、复述能力、结构组织能力、记忆能力、计算能力以及自我照顾、转移、行走、交流、社会认知较B组、C组改善显著(P0.05),而B组与C组间认知功能各项评分、FIM评分比较差异无统计学意义(P0.05);A组患者治疗后总有效率为90.63%,显著优于B组73.89%的总有效率及C组70.00%的总有效率(P0.05),而B组与C组比较差异无统计学意义(P0.05)。结论:颅脑伤患者尽早的接受高压氧治疗其认知功能改善越明显,治疗效果越好。     

四川大头茶若干生态问题的研究

四川大头茶(Gordonia acumenata)是我国亚热带西南地区常绿阔叶林优势种之一,材质好,生长快而又未被人注意的一种优良树种。由于它是喜阳的常绿阔叶顶极先锋种(pioneer climax species)其幼苗耐阴,所以在针阔叶混交林中排挤了先锋树种(pioneer species)马尾松,而本身又在常绿阔叶林演替阶段,被更耐阴的顶极种(climax species)所代替,这是由于顶极种有较高的生态位重叠(niche overiap)和最大的生态位宽度(niche breadth)值。四川大头茶Pn日变化具有双峰曲线型和单峰曲线型两种模式,而年变化有明显的季节现象。光照强度和温度是决定Pn的两个主要生态因子,并具有较高的饱和净光合速率和降低暗呼吸能力使其成为喜阳速生的特性。由于速生,其生物量可达176.62t·ha-1;生产量达10.86t·ha-1。四川大头茶幼苗的蒸腾强度与大气湿度、叶温、光强、相对湿度、叶含水量等参数的变化有密切关系。干旱胁迫使光合速率明显下降,从而影响地上部分的生物生产力,但根／冠比却增加18.18%,这可能是植株对干旱胁迫的一种生态适应对策。四川大头茶各器官的营养元素分配与季节有密切关系,同时与土壤中相应的元素含量也有关。     

Savanna trees in Namibia—Factors controlling their distribution at the arid end of the spectrum

This study reviewed the distribution of ten common savanna trees in Namibia. Tree distributions were investigated in relation to bioclimatic, topographic and edaphic variables at a national scale. The factors of importance at these broad geographic scales appeared to be rainfall, substrate and, likely, the incidence of frost. Baikiaea plurijuga, Burkea africana, Guibourtia coleosperma and Pterocarpus angolensis seem to reach their bioclimatic limits in Namibia.At the local level, plant traits become important and contribute to explaining distribution patterns. High water and/or nitrogen use efficiency (Acacia erioloba, Colophospermum mopane), dual water obtaining strategies (Faidherbia albida), fire tolerance (e.g. Acacia species, Burkea africana and Pterocarpus angolensis) and drought tolerance (Boscia albitrunca) are some key attributes providing additional explanations for current distributions.Amongst the selected trees and at broad geographic scales, below-ground adaptations are governed by rainfall regime in combination with coarse-textured soils, whereby shallow-rooted trees prevail in the Kalahari sandveld. Deep-rooted species are found largely on non-sandy soils. Physiological performance of many trees appears to be directly linked to rainfall regime and trees may hence show varying performance throughout their distribution range. Insight into plant functional attributes of trees in Namibia is required to develop appropriate management strategies in the light of climate change. Modelling climate change impacts should consider the relative contribution of bioclimatic versus local environmental factors that explain the current distribution patterns of the selected trees.     

Acute metal stress in Populus tremula×P. alba (717‐1B4 genotype): Leaf and cambial proteome changes induced by cadmium2+

The comprehension of metal homeostasis in plants requires the identification of molecular markers linked to stress tolerance. Proteomic changes in leaves and cambial zone of Populus tremula×P. alba (717‐1B4 genotype) were analyzed after 61 days of exposure to cadmium (Cd) 360 mg/kg soil dry weight in pot‐soil cultures. The treatment led to an acute Cd stress with a reduction of growth and photosynthesis. Cd stress induced changes in the display of 120 spots for leaf tissue and 153 spots for the cambial zone. It involved a reduced photosynthesis, resulting in a profound reorganisation of carbon and carbohydrate metabolisms in both tissues. Cambial cells underwent stress from the Cd actually present inside the tissue but also a deprivation of photosynthates caused by leaf stress. An important tissue specificity of the response was observed, according to the differences in cell structures and functions.     

Estimating aboveground herbaceous plant biomass via proxies: The confounding effects of sampling year and precipitation

Direct measurements of aboveground plant biomass are often not feasible, thus various biomass proxies are in use. To obtain biomass estimates, these proxies are calibrated against actual biomass, and the resulting proxy-biomass relationship is often used across multiple years and experimental treatments within a study. We investigated how the proxy-biomass relationship varied across years and considered interannual precipitation variability as a contributing factor.We sampled a perennial grassland for ten consecutive years (2003–2012) in central Hungary and estimated vegetation cover and Normalized Difference Vegetation Index (NDVI); two frequently used biomass proxies representing two contrasting methods. Aboveground live herbaceous plant biomass was harvested from each plot after sampling, and regression models were used to assess the relationship between biomass proxies and actual aboveground biomass.We found that cover and NDVI were equally effective at estimating biomass. However, the relationship between either biomass proxy and actual biomass varied amongst years, and this was related to the amount of precipitation. In wetter years, proxy-biomass relationships were steeper than in drier years.These results indicate that using the same proxy-biomass relationship across different years or precipitation regimes may not be valid and may introduce systematic error into biomass estimations in long-term studies or precipitation manipulation experiments.     

Divalent metal ion complexes of S100B in the absence and presence of pentamidine

As part of an effort to inhibit S100B, structures of pentamidine (Pnt) bound to Ca²⁺-loaded and Zn²⁺,Ca²⁺-loaded S100B were determined by X-ray crystallography at 2.15 Å (R_free = 0.266) and 1.85 Å (R_free = 0.243) resolution, respectively. These data were compared to X-ray structures solved in the absence of Pnt, including Ca²⁺-loaded S100B and Zn²⁺,Ca²⁺-loaded S100B determined here (1.88 Å; R_free = 0.267). In the presence and absence of Zn²⁺, electron density corresponding to two Pnt molecules per S100B subunit was mapped for both drug-bound structures. One Pnt binding site (site 1) was adjacent to a p53 peptide binding site on S100B (± Zn²⁺), and the second Pnt molecule was mapped to the dimer interface (site 2; ± Zn²⁺) and in a pocket near residues that define the Zn²⁺ binding site on S100B. In addition, a conformational change in S100B was observed upon the addition of Zn²⁺ to Ca²⁺-S100B, which changed the conformation and orientation of Pnt bound to sites 1 and 2 of Pnt-Zn²⁺,Ca²⁺-S100B when compared to Pnt-Ca²⁺-S100B. That Pnt can adapt to this Zn²⁺-dependent conformational change was unexpected and provides a new mode for S100B inhibition by this drug. These data will be useful for developing novel inhibitors of both Ca²⁺- and Ca²⁺,Zn²⁺-bound S100B.     

Osmotic stress decreases complexity underlying the electrophysiological dynamic in soybean

• Studies on plant electrophysiology are mostly focused on specific traits of single cells. Inspired by the complexity of the signalling network in plants, and by analogy with neurons in human brains, we sought evidence of high complexity in the electrical dynamics of plant signalling and a likely relationship with environmental cues.
• An EEG‐like standard protocol was adopted for high‐resolution measurements of the electrical signal in Glycine max seedlings. The signals were continuously recorded in the same plants before and after osmotic stimuli with a ?2 MPa mannitol solution. Non‐linear time series analyses methods were used as follows: auto‐correlation and cross‐correlation function, power spectra density function, and complexity of the time series estimated as Approximate Entropy (ApEn).
• Using Approximate Entropy analysis we found that the level of temporal complexity of the electrical signals was affected by the environmental conditions, decreasing when the plant was subjected to a low osmotic potential. Electrical spikes observed only after stimuli followed a power law distribution, which is indicative of scale invariance.
• Our results suggest that changes in complexity of the electrical signals could be associated with water stress conditions in plants. We hypothesised that the power law distribution of the spikes could be explained by a self‐organised critical state (SOC) after osmotic stress.

     

鸡基因组差异表达基因翻译起始密码子上下游序列的比较研究

翻译起始调控是基因表达调控的一个关键步骤之一。本文以鸡为研究材料,比较研究了鸡基因组高表达基因和低表达基因翻译起始密码子上下游的碱基序列差异,旨在寻找影响鸡基因表达水平的特异性调控位点。全部3 020个单剪接基因完整的mRNA序列及有详细注释的5＇UTRs序列从Ensembl下载。编写计算机程序,读取每个基因mRNA起始密码子上下游各位点的碱基。研究发现,起始密码子上游-3、-2位点可能是鸡基因组基因表达起始密码子正确识别的关键位点。起始密码子上下游的碱基组成分析发现,高表达基因和低表达基因起始密码子的上游均倾向使用（G＋C）,高表达基因的使用偏倚尤为强烈。序列差异比较发现,高表达基因在-9、-6、-3、＋4位点显著偏向G,在-1、-2、-4、-5位点显著偏向C。低表达基因起始密码子上游使用A、U的频率显著高于低表达基因。在-19位点强烈偏向A,在＋1、＋11、＋14位点强烈偏向U。