不健全资料的参数关联分析法

首先建立相关变量取值随时序变化的数学模型,而后,利用模型中能够反映变量几何形状的适宜参数,提出了参数关联度的概念．从而解决了观测值非一一对应、且不齐的相关变量关联分析问题．同时给出一种较高拟合精度的非等间隔序列的灰色建模方法．     

Evidence for a role of protein phosphorylation in the maintenance of the cnidarian–algal symbiosis

The endosymbiotic relationship between cnidarians and photosynthetic dinoflagellate algae provides the foundation of coral reef ecosystems. This essential interaction is globally threatened by anthropogenic disturbance. As such, it is important to understand the molecular mechanisms underpinning the cnidarian–algal association. Here we investigated phosphorylation‐mediated protein signalling as a mechanism of regulation of the cnidarian–algal interaction, and we report on the generation of the first phosphoproteome for the coral model system Aiptasia. Mass spectrometry‐based phosphoproteomics using data‐independent acquisition allowed consistent quantification of over 3,000 phosphopeptides totalling more than 1,600 phosphoproteins across aposymbiotic (symbiont‐free) and symbiotic anemones. Comparison of the symbiotic states showed distinct phosphoproteomic profiles attributable to the differential phosphorylation of 539 proteins that cover a broad range of functions, from receptors to structural and signal transduction proteins. A subsequent pathway enrichment analysis identified the processes of “protein digestion and absorption,” “carbohydrate metabolism,” and “protein folding, sorting and degradation,” and highlighted differential phosphorylation of the “phospholipase D signalling pathway” and “protein processing in the endoplasmic reticulum.” Targeted phosphorylation of the phospholipase D signalling pathway suggests control of glutamate vesicle trafficking across symbiotic compartments, and phosphorylation of the endoplasmic reticulum machinery suggests recycling of symbiosome‐associated proteins. Our study shows for the first time that changes in the phosphorylation status of proteins between aposymbiotic and symbiotic Aiptasia anemones may play a role in the regulation of the cnidarian–algal symbiosis. This is the first phosphoproteomic study of a cnidarian–algal symbiotic association as well as the first application of quantification by data‐independent acquisition in the coral field.     

Whole‐brain microcirculation detection after ischemic stroke based on swept‐source optical coherence tomography

The occurrence and development of ischemic stroke are closely related to cerebral blood flow. Real‐time monitoring of cerebral perfusion level is very useful for understanding the mechanisms of the disease. A wide field of view (FOV) is conducive to capturing lesions and observing the progression of the disease. In this paper, we attempt to monitor the whole‐brain microcirculation in middle cerebral artery occlusion (MCAO) rats over time using a wide FOV swept‐source OCT (SS‐OCT) system. A constrained image registration algorithm is used to remove motion artifacts that are prone to occur in a wide FOV angiography. During ischemia, cerebral perfusion levels in the left and right hemispheres, as well as in the whole brain were quantified and compared. Changes in the shape and location of blood vessels were also recorded. The results showed that the trend in cerebral perfusion levels of both hemispheres was highly consistent during MCAO, and the position of the blood vessels varied over time. This work will provide new insights of ischemic stroke and is helpful to assess the effectiveness of potential treatment strategies.      

Performance of the marginal structural models under various scenarios of incomplete marker's values: A simulation study

Marginal structural models (MSMs) have been proposed for estimating a treatment's effect, in the presence of time‐dependent confounding. We aimed to evaluate the performance of the Cox MSM in the presence of missing data and to explore methods to adjust for missingness. We simulated data with a continuous time‐dependent confounder and a binary treatment. We explored two classes of missing data: (i) missed visits, which resemble clinical cohort studies; (ii) missing confounder's values, which correspond to interval cohort studies. Missing data were generated under various mechanisms. In the first class, the source of the bias was the extreme treatment weights. Truncation or normalization improved estimation. Therefore, particular attention must be paid to the distribution of weights, and truncation or normalization should be applied if extreme weights are noticed. In the second case, bias was due to the misspecification of the treatment model. Last observation carried forward (LOCF), multiple imputation (MI), and inverse probability of missingness weighting (IPMW) were used to correct for the missingness. We found that alternatives, especially the IPMW method, perform better than the classic LOCF method. Nevertheless, in situations with high marker's variance and rarely recorded measurements none of the examined method adequately corrected the bias.     

Effects of gestational exposure to 1.95‐GHz W‐CDMA signals for IMT‐2000 cellular phones: Lack of embryotoxicity and teratogenicity in rats

The present study was designed to evaluate whether gestational exposure to an EMF targeting the head region, similar to that from cellular phones, might affect embryogenesis in rats. A 1.95‐GHz wide‐band code division multiple access (W‐CDMA) signal, which is one applied for the International Mobile Telecommunication 2000 (IMT‐2000) system and used for the freedom of mobile multimedia access (FOMA), was employed for exposure to the heads of four groups of pregnant CD(SD) IGS rats (20 per group) for gestational days 7–17. The exposure was performed for 90 min/day in the morning. The spatial average specific absorption rate (SAR) for individual brains was designed to be 0.67 and 2.0 W/kg with peak brain SARs of 3.1 and 7.0 W/kg for low (group 3) and high (group 4) exposures, respectively, and a whole‐body average SAR less than 0.4 W/kg so as not to cause thermal effects due to temperature elevation. Control and sham exposure groups were also included. At gestational day 20, all dams were killed and fetuses were taken out by cesarean section. There were no differences in maternal body weight gain. No adverse effects of EMF exposure were observed on any reproductive and embryotoxic parameters such as number of live (243–271 fetuses), dead or resorbed embryos, placental weights, sex ratios, weights or external, visceral or skeletal abnormalities of live fetuses. Bioelectromagnetics 30:205–212, 2009. © 2008 Wiley‐Liss, Inc.     

The control of cellulose microfibril deposition in the cell wall of higher plants

In maize (Zea mays L.) and pine (Pinus taeda L.) seedlings, cellulose microfibril impressions are present on freeze-fractured plasma membranes. It has been proposed that impressions of newly synthesized microfibrils are a record of the movement of terminal synthesizing complexes through the plasma membrane (Mueller and Brown, 1980, J. Cell Biol. 84, 315–326). The association of terminal complexes with the ends of microfibril impressions or with the ends of microfibrils torn through the membrane indicates the orientation of microfibril tips. Unidirectionally-oriented microfibril tips (all pointing in the same direction) are associated with the organized deposition of parallel arrays of microfibrils. Multidirectionally-oriented microfibril tips were observed in a cell in which microfibril deposition was unusually disorganized. Microfibril patterns around pit fields are asymmetric and resemble flow patterns. Unidirectionally-oriented tears are associated with these microfibrils. Although microfibril orientations are deflected around pit fields, the main axis of microfibril orientation is maintained across the surface of the cell. The hypothesis is proposed that the interaction of a flowing plasma membrane with microfibril synthesizing complexes in the plane of the membrane may result in unidirectional deposition and asymmetric microfibril impressions around pit fields.Some of this work has been published in preliminary form (Brown 1979)     

Predictive Validity of Discriminant Analysis for Genetic Data

We examined the predictive validity of the results using discriminant analysis to distinguish statistically among two or more populations with a large sample of random amplified polymorphic DNA (RAPD) loci, but a small sample of genotypes from each population. We compared and contrasted results from randomized data with results from real data of three studies by 100 randomized shuffling of genotypes into various populations. We generally obtained substantial differences between results from randomized data compared to those from the real data in several characteristics of discriminant analysis. We showed that a high level of correctly classified percentage is also obtainable in the analysis of randomized data, mainly with a low number of populations. However, the correctly classified percentage obtained from the real data was generally significantly higher than the percentage obtained from the randomized data. We suggested that the high level of real differences in allele frequencies of the RAPD polymorphic loci clearly distinguished the various populations and that the populations differ significantly in their RAPD contents in accordance with ecological heterogeneity. We obtained either no or a low level of difference between the correct classification rate obtained by the leaving-one-out procedure and that obtained from the original data, attributed to a low number of loci selected by the stepwise method. The results strengthen and support our conclusion and lead us to focus on the discriminant analysis by selecting only low numbers of discriminating variables.     

黑线姬鼠两亚种(中国东北地区及俄罗斯远东地区的东北亚种和朝鲜半岛的朝鲜亚种) 的线粒体DNA 序列缺少趋异性

为了检测黑线姬鼠两亚种(来自中国东北地区、俄罗斯远东地区的东北亚种和朝鲜半岛的朝鲜亚种)线
粒体DNA 的变异水平并确定朝鲜亚种的分类地位,我们测序分析了两亚种的线粒体DNA 细胞色素b 的部分序列
(1 054 bp)和控制区的部分序列(860 bp),并与基因库中黑线姬鼠相应的单倍型序列进行了比较。可以看出东
北亚种的序列显示出某些分异,可以被分为2 或3 个亚群,所以我们提出需要更多标本的DNA 分析来确定东北
亚种的分类地位。另外,来自韩国的朝鲜亚种的序列,与来自中国东北地区龙江和哈尔滨的东北亚种的两个亚
群相似(1 个亚群是细胞色素b 的两个单倍型,另1 个是控制区的两个单倍型),表明基于线粒体DNA 序列的遗
传多样性与现今基于形态特征对这些姬鼠的分类所得结果是不一致的。因此我们认为来自韩国的朝鲜亚种是一
个只在形态特异上不同于东北亚种的地方亚种,我们建议通过其他DNA 标记来进一步验证其亚种地位。我们还
认为朝鲜半岛不是最近的冰川期黑线姬鼠残遗种的保护区。     

Electrolyte effects on the intervalence transition within discrete binuclear cyano-bridged complexes. An estimation of activation free energy from static, optical and electrochemical data

A study of the metal-to-metal charge-transfer (MMCT) transition within the binuclear cyano-bridged complexes cis-[L¹³Co^III(μ-NC)Fe^II(CN)₅]⁻ (L¹³ = 12-methyl-1,4,7,10-tetraazacyclotridecan-12-amine), trans-[L¹⁴Co^III(μ-NC)Fe^II(CN)₅]⁻ (L¹⁴ = 6-methyl-1,4,8,11-tetraazacyclotetradecan-6-amine) and trans-[L¹⁵Co^III(μ-NC)Fe^II(CN)₅]⁻ (L¹⁵ = 10-methyl-1,4,8,12-tetraazacyclopentadecan-10-amine) has been carried out in electrolyte solutions at varying concentrations. Using these data, as well as the reaction free energies obtained from electrochemical measurements, the reorganisation and activation free energies for the forward and reverse thermal electron-transfer processes have been estimated. The changes of these parameters with the electrolyte concentration, as well as those of the energy of the maximum MMCT band and the reaction free energy, are mainly due to ion-pairing effects.