Changes in the T-wave vector loop of the three-dimensional vectorcardiogram during exposure to cold pressor stress

Three-dimensional vectorcardiography was used to characterize changes in the T-wave vector loop during exposure to cold pressor stress. Data were collected from 8 subjects during baseline, cold pressor, and recovery periods. Maximum vector length, polar angle of the longest vector, azimuth angle of the longest vector, sum of all vectors, polar angle of the vector sum, azimuth angle of the vector sum, surface area of the loop, and maximum distance between adjacent vectors were computed from the T-wave vector loop. The amplitude of the one-dimensional T-wave (TWA) was also computed. Interbeat interval and TWA decreased during hand immersion and increased during recovery. Of the vectorcardiographic measures, only maximum vector length and vector sum showed statistically significant change; both decreased during the task and returned to baseline during recovery. TWA accounted for 46% of the task related variance compared to 53% and 47% respectively, for vector sum and maximum vector length. Changes in TWA probably reflect a true change in cardiac electrical potential rather than a change in T-wave vector loop shape or orientation.     

Effective speed and agility conditioning methodology for random intermittent dynamic type sports

Different coaching methods are often used to improve performance. This study compared the effectiveness of 2 methodologies for speed and agility conditioning for random, intermittent, and dynamic activity sports (e.g., soccer, tennis, hockey, basketball, rugby, and netball) and the necessity for specialized coaching equipment. Two groups were delivered either a programmed method (PC) or a random method (RC) of conditioning with a third group receiving no conditioning (NC). PC participants used the speed, agility, quickness (SAQ) conditioning method, and RC participants played supervised small-sided soccer games. PC was also subdivided into 2 groups where participants either used specialized SAQ equipment or no equipment. A total of 46 (25 males and 21 females) untrained participants received (mean +/- SD) 12.2 +/- 2.1 hours of physical conditioning over 6 weeks between a battery of speed and agility parameter field tests. Two-way analysis of variance results indicated that both conditioning groups showed a significant decrease in body mass and body mass index, although PC achieved significantly greater improvements on acceleration, deceleration, leg power, dynamic balance, and the overall summation of % increases when compared to RC and NC (p < 0.05). PC in the form of SAQ exercises appears to be a superior method for improving speed and agility parameters; however, this study found that specialized SAQ equipment was not a requirement to observe significant improvements. Further research is required to establish whether these benefits transfer to sport-specific tasks as well as to the underlying mechanisms resulting in improved performance.     

Machine learning of large‐scale spatial distributions of wild turkeys with high‐dimensional environmental data

Species distribution modeling often involves high‐dimensional environmental data. Large amounts of data and multicollinearity among covariates impose challenges to statistical models in variable selection for reliable inferences of the effects of environmental factors on the spatial distribution of species. Few studies have evaluated and compared the performance of multiple machine learning (ML) models in handling multicollinearity. Here, we assessed the effectiveness of removal of correlated covariates and regularization to cope with multicollinearity in ML models for habitat suitability. Three machine learning algorithms maximum entropy (MaxEnt), random forests (RFs), and support vector machines (SVMs) were applied to the original data (OD) of 27 landscape variables, reduced data (RD) with 14 highly correlated covariates being removed, and 15 principal components (PC) of the OD accounting for 90% of the original variability. The performance of the three ML models was measured with the area under the curve and continuous Boyce index. We collected 663 nonduplicated presence locations of Eastern wild turkeys (Meleagris gallopavo silvestris) across the state of Mississippi, United States. Of the total locations, 453 locations separated by a distance of ≥2 km were used to train the three ML algorithms on the OD, RD, and PC data, respectively. The remaining 210 locations were used to validate the trained ML models to measure ML performance. Three ML models had excellent performance on the RD and PC data. MaxEnt and SVMs had good performance on the OD data, indicating the adequacy of regularization of the default setting for multicollinearity. Weak learning of RFs through bagging appeared to alleviate multicollinearity and resulted in excellent performance on the OD data. Regularization of ML algorithms may help exploratory studies of the effects of environmental factors on the spatial distribution and habitat suitability of wildlife.     

Changes in theT-wave vector loop of the three-dimensional vectorcardiogram during exposure to cold pressor stress

Three-dimensional vectorcardiography was used to characterize changes in the T-wave vector loop during exposure to cold pressor stress. Data were collected from 8 subjects during baseline, cold pressor, and recovery periods. Maximum vector length, polar angle of the longest vector, azimuth angle of the longest vector, sum of all vectors, polar angle of the vector sum, azimuth angle of the vector sum, surface area of the loop, and maximum distance between adjacent vectors were computed from the T-wave vector loop. The amplitude of the one-dimensional T-wave (TWA) was also computed. Interbeat interval and TWA decreased during hand immersion and increased during recovery. Of the vectorcardiographic measures, only maximum vector length and vector sum showed statistically significant change; both decreased during the task and returned to baseline during recovery. TWA accounted for 46% of the task related variance compared to 53% and 47% respectively, for vector sum and maximum vector length. Changes in TWA probably reflect a true change in cardiac electrical potential rather than a change in T-wave vector loop shape or orientation.This material was presented in part at the annual meeting of the Association for Applied Psychophysiology and Biofeedback, Washington, D.C., March 1990.We are indebted to Lawrence E. Widman, M.D., Ph.D. for his invaluable advice throughout this study.     

HSP27 特异性shRNA 表达载体的构建及在耐吉西他滨人胰腺癌细胞株 SW1990/Gem 中的表达

目的:构建HSP27基因的短发夹RNA(short hairpin RNA,shRNA)真核表达载体及观察其在耐吉西他滨人胰腺癌细胞株SW1990/Gem中的表达,为进一步探索肿瘤的基因治疗打下前期基础。方法:参考文献及shRNA设计原则,设计并合成2条能转录shRNA的DNA序列,退火连接后,插入含绿色荧光蛋白(green fluorescence protein,GFP)基因和U6启动子的真核表达载体pRNAT-U6.3中,构建重组载体pRNAT-shHSP27。重组载体经鉴定后转染SW1990/Gem,倒置荧光显微镜观察转染情况,RT-PCR、Western Blot从mRNA及蛋白水平探讨转染对耐吉西他滨人胰腺癌细胞株SW1990/Gem的影响。结果:成功构建了针对HSP27基因的shRNA表达载体。倒置荧光显微镜下显示转染48h后SW1990/Gem细胞内存在GFP表达。RT-PCR、WesternBlot结果提示转染后HSP27的mRNA及蛋白表达水平较对照组有明显抑制(P<0.05)。结论:成功构建针对HSP27基因的特异性shRNA真核表达载体,转染细胞后可抑制HSP27表达,为进一步研究HSP27与胰腺癌生物学行为及化疗耐药等相关性奠定了基础。     

Cloning of a new LEA1 gene promoter from soybean and functional analysis in transgenic tobacco

LEA1 gene from Glycine max can be expressed in late-embryo stage of plants, and respond to salinity and dehydration stress. To elucidate the mechanism for stress tolerance and high expression in seeds, we isolated and characterized the promoter of LEA1 gene (EQ, 1997 bp) starting the 5′LEA1 coding region. A deletion mutant of EQ promoter (ED) and the full length promoter (EQ) were fused to GUS reporter gene and transformed into the tobacco leaf discs. The results indicated that expression of the reporter gene (GUS) could be regulated by EQ promoter, and was stronger than the mutant under the stress conditions. Also, the expression level of GUS gene driven by EQ promoter in transgenic tobacco seeds was significantly higher than that by the mutant promoter, which meant that it had a better tissue-specificity. Therefore, the active domain for the promoter was located between ?1997 and ?1000 bp. Additionally, the activity of EQ promoter was 2.1-, 3.3- and 0.4- times stronger than the activity of promoter CaMV35S under salt (24 h), drought (10 h) or ABA (24 h), respectively. Meanwhile, the GUS activity of EQ promoter in seeds was 1.8-fold stronger compared to the promoter CaMV35S. In summary, the new promoter (EQ) is bi-functional, stress-inducible and seed-specific. These findings provide a further understanding for the regulation of LEA1gene expression, and suggest a new way for improving seed quality under saline and alkaline land.     

Directional Coordination of Thumb and Finger Forces during Precision Pinch

The human opposable thumb enables the hand to perform dexterous manipulation of objects, which requires well-coordinated digit force vectors. This study investigated the directional coordination of force vectors generated by the thumb and index finger during precision pinch. Fourteen right-handed, healthy subjects were instructed to exert pinch force on an externally stabilized apparatus with the pulps of the thumb and index finger. Subjects applied forces to follow a force-ramp profile that linearly increased from 0 to 12 N and then decreased to 0 N, at a rate of ±3 N/s. Directional relationships between the thumb and index finger force vectors were quantified using the coordination angle (CA) between the force vectors. Individual force vectors were further analyzed according to their projection angles (PAs) with respect to the pinch surface planes and the shear angles (SAs) within those planes. Results demonstrated that fingertip force directions were dependent on pinch force magnitude, especially at forces below 2 N. Hysteresis was observed in the force-CA relationship for increasing and decreasing forces and fitted with exponential models. The fitted asymptotic values were 156.0±6.6° and 150.8±9.3° for increasing and decreasing force ramps, respectively. The PA of the thumb force vector deviated further from the direction perpendicular to the pinching surface planes than that of the index finger. The SA showed that the index finger force vector deviated in the ulnar-proximal direction, whereas the thumb switched its force between the ulnar-proximal and radial-proximal directions. The findings shed light on the effects of anatomical composition, biomechanical function, and neuromuscular control in coordinating digit forces during precision pinch, and provided insight into the magnitude-dependent force directional control which potentially affects a range of dexterous manipulations.     

基于NLPCA-GSO可持续发展评价——以环渤海区域为例

区域可持续发展水平、发展的持续性和系统的协调性是区域可持续发展定量评价研究的三角构架,而在传统上基于各子系统主成分分析结果直接进行形色各异的加权计算对可持续发展评价而言是有待商榷的。提出了非线性主成分分析和施密特正交化(NLPCA-GSO)相耦合的方法评价区域的可持续发展水平来弥补传统方法的不足,并由此建立区域发展持续性模型和可持续发展系统协调度模型,再以环渤海区域为实证分析其2001—2010年的可持续发展状况。结果表明:基于NLPCA-GSO的可持续发展水平模型可以很好地弥补传统主成分分析及对各子系统结果的综合评价的不足;区域发展持续性模型、协调性模型和区域可持续系统变化的滤波分析形象地揭示区域可持续发展的实质和内涵;实证研究表明环渤海区域在研究时段内可持续发展水平有所上升,而环境子系统持续性的下降是引起区域发展持续性和系统协调度的变化的主要原因。研究结果可丰富区域可持续发展评价的方法学,也可为环渤海区域的可持续发展研究奠定基础。     

Estimation in the Cox survival regression model with covariate measurement error and a changepoint

The Cox regression model is a popular model for analyzing the relationship between a covariate vector and a survival endpoint. The standard Cox model assumes a constant covariate effect across the entire covariate domain. However, in many epidemiological and other applications, the covariate of main interest is subject to a threshold effect: a change in the slope at a certain point within the covariate domain. Often, the covariate of interest is subject to some degree of measurement error. In this paper, we study measurement error correction in the case where the threshold is known. Several bias correction methods are examined: two versions of regression calibration (RC1 and RC2, the latter of which is new), two methods based on the induced relative risk under a rare event assumption (RR1 and RR2, the latter of which is new), a maximum pseudo-partial likelihood estimator (MPPLE), and simulation-extrapolation (SIMEX). We develop the theory, present simulations comparing the methods, and illustrate their use on data concerning the relationship between chronic air pollution exposure to particulate matter PM₁₀ and fatal myocardial infarction (Nurses Health Study (NHS)), and on data concerning the effect of a subject's long-term underlying systolic blood pressure level on the risk of cardiovascular disease death (Framingham Heart Study (FHS)). The simulations indicate that the best methods are RR2 and MPPLE.     

A mathematical consideration of the word-composition vector method in comparison of biological sequences

To measure the similarity or dissimilarity between two given biological sequences, several papers proposed metrics based on the "word-composition vector". The essence of these metrics is as follows. First, we count the appearance frequencies of all the K-tuple words throughout each of two given sequences. Then, the two given sequences are transformed into their respective word-composition vectors. Next, the distance metrics, for example the angle between the two vectors, are calculated. A significant issue is to determine the optimal word size K. With a mathematical model of mutational events (including substitutions, insertions, deletions and duplications) that occur in sequences, we analyzed how the angle between the composition vectors depends on the mutational events. We also considered the optimal word size (=resolution) from our original approach. Our results were verified by computational experiments using artificially generated sequences, amino acid sequences of hemoglobin and nucleotide sequences of 16S ribosomal RNA.     

我国农业系统可持续发展协调度分析

农业系统可持续协调发展作为一种发展理念已成为共识,受到我国政府高度重视。采用2004—2015年我国农业生产面板数据,运用熵值法、探索性空间数据分析等方法分析我国农业系统可持续发展协调度情况。研究结果表明:(1)2004—2015年我国各省(市、自治区)农业各子系统可持续能力之间协调度处于不稳定变动态势,且其协调度值较低。(2)从协调度分布来看,协调度处于"比较协调"和"协调"的省(市、自治区)主要分布在我国的东部和东南部地区,其余大多数省(市、自治区)农业各子系统可持续能力之间的协调度处于"不协调"。(3)从空间自相关性来看,各省(市、自治区)农业各子系统可持续能力之间协调度呈正的全局自相关性且相关程度逐渐增大,而大多数省(市、自治区)农业各子系统可持续能力之间协调度的局部自相关性不显著,且其农业各子系统可持续能力之间协调度空间极化不明显,处于较低水平均衡状态。从时空维度、空间相关性方面分析农业各子系统可持续能力之间协调度,为提高我国农业系统可持续发展水平提供政策建议。     

The Use of Epstein–Barr Virus-Based Shuttle Vectors in Rat PC12 Cells

1. The rat pheochromocytoma PC12 cell line has been a commonly used model for studies of neuronal development, function, and death. Thus the abilityto transfect PC12 cells in an efficient manner and to manipulate their gene expression would enhance the usefulness of these cells.2. We demonstrate that EBV-based vectors provide a useful expression system for gene manipulation in rat PC12 cells.3. The EBV-based vectors replicate episomally in PC12 cells for at least 2months, as evidence by their recovery from the transfected cells and by the digestion of the episomal plasmid with the isoschizomer MboI and DpnI restriction enzymes.3. PC12 cells are efficiently transfected by EBV-based vectors both transiently and stably.4. Transfection of PC12 cells with an EBV-based vector containing tau cDNA in the antisense orientation resulted in a decrease in the level of tau protein in the transfected cells.5. The results demonstrate that EBV-based vectors can be a useful expression system for gene manipulation in PC12 cells.     

The Effectiveness of Acupuncture in Prevention and Treatment of Postoperative Nausea and Vomiting - A Systematic Review and Meta-Analysis

Background

Acupuncture therapy for preventive and treatment of postoperative nausea and vomiting(PONV), a condition which commonly present after anaesthesia and surgery is a subject of growing interest.

Objective

This paper included a systematic review and meta-analysis on the effect of different type of acupuncture and acupoint selection in PONV prevention and treatment.

Methods

Randomised controlled trials(RCTs) comparing acupuncture with non-acupuncture treatment were identified from databases PubMed, Cochrane, EBSCO, Ovid, CNKI and Wanfangdata. Meta-analysis on eligible studies was performed using fixed-effects model with RevMan 5.2. Results were expressed as RR for dichotomous data, with 95%CI.

Results

Thirty RCTs, 1276 patients (intervention) and 1258 patients (control) were identified. Meta-analysis showed that PC6 acupuncture significantly reduced the number of cases of early vomiting (postoperative 0-6h) (RR=0.36, 95%CI 0.19,0.71; P=0.003) and nausea (postoperative 0-24h) (RR=0.25, 95%CI 0.10,0.61; P=0.002), but not early nausea (postoperative 0-6h) (RR=0.64, 95%CI 0.34,1.19; P=0.150) and vomiting (postoperative 0-24h) (RR=0.82, 95%CI 0.48,1.38; P=0.450). PC6 acupressure significantly reduced the number of cases of nausea (RR=0.71, 95%CI 0.57,0.87; P=0.001) and vomiting (RR=0.62, 95%CI 0.49,0.80; P=0.000) at postoperative 0-24h. PC6 electro-acupoint stimulation significantly reduced the number of cases of nausea (RR=0.49, 95%CI 0.38,0.63; P<0.000) and vomiting (RR=0.50, 95%CI 0.36,0.70; P<0.000) at postoperative 0-24h. Stimulation of PC6 with other acupoint(s) significantly reduced the number of cases of nausea and vomiting (RR=0.29, 95%CI 0.17,0.49; P<0.000) at postoperative 0-24h. Stimulation of other acupoint(s)(non PC6) also significantly reduced the number of cases of nausea and vomiting (RR=0.63, 95%CI 0.49,0.81; P=0.000) at postoperative 0-24h. However, the quality of study was generally low in studies of PC6 combined with other acupoint(s) and other acupoint(s). Details of blinding were not reported in most reports.

Conclusions

Besides PC6, PC6 combined with other acupoint(s) and other alternative acupoint(s) might be beneficial in prevention and treatment of PONV, the evidence justifies future high-quality studies.     

Distance effect of matrix attachment regions on transgene expression in stably transfected Chinese hamster ovary cells

The β-globin matrix attachment regions (MARs) were inserted into the 5′-site of the eukaryotic expression vector cassette and DNA fragments 350 and 750 bp in length were inserted into the site to generate expression vectors with varying distances between the expression cassette and MAR. The vectors containing MARs increased chloramphenicol acetyltransferase (CAT) expression levels compared to the negative control vector lacking the MAR; the highest expression increase was 3.8-fold. A greater MAR-transgene distance (750 bp) correlated with a greater increase in transgene expression when compared to the control vector that lacked separation between the MAR and transgene. CAT gene copy numbers were higher in cells transformed with the vector possessing a smaller MAR-transgene distance (350 bp) than in cells belonging to the other three groups. However, MAR-induced transgene expression levels did not exhibit a direct relationship with gene copy number.     

Transformation of Sexually Transmitted Infection-Causing Serovars of Chlamydia trachomatis Using Blasticidin for Selection

Plasmid-free Chlamydia trachomatis serovar L2 organisms have been transformed with chlamydial plasmid-based shuttle vectors pGFP::SW2 and pBRCT using β-lactamase as a selectable marker. However, the recommendation of amoxicillin, a β-lactam antibiotics, as one of the choices for treating pregnant women with cervicitis due to C. trachomatis infection has made the existing shuttle vectors unsuitable for transforming sexually transmitted infection (STI)-causing serovars of C. trachomatis. Thus, in the current study, we modified the pGFP::SW2 plasmid by fusing a blasticidin S deaminase gene to the GFP gene to establish blasticidin resistance as a selectable marker and replacing the β-lactamase gene with the Sh ble gene to eliminate the penicillin resistance. The new vector termed pGFPBSD/Z::SW2 was used for transforming plasmid-free C. trachomatis serovar D organisms. Using blasticidin for selection, stable transformants were obtained. The GFP-BSD fusion protein was detected in cultures infected with the pGFPBSD/Z::SW2-trasnformed serovar D organisms. The transformation restored the plasmid property to the plasmid-free serovar D organisms. Thus, we have successfully modified the pGFP::SW2 transformation system for studying the biology and pathogenesis of other STI-causing serovars of C. trachomatis.     

RNA干扰技术对PC12细胞CaMKⅡβ基因表达的影响

观察RNA干扰表达载体对PC12细胞中CaMKIIβ基因的抑制作用。构建针对CaMKIIβ基因的RNAi质粒表达载体,脂质体法转染大鼠肾上腺嗜铬细胞瘤PC12细胞株,应用逆转录-聚合酶链反应(RT-PCR)、Western blot 检测其对CaMKIIβ mRNA及蛋白质水平的影响。构建的质粒表达载体在PC12细胞中抑制了CaMKIIβ mRNA及蛋白质的表达。与阴性对照组相比,表达质粒产生的siRNA对CaMKIIβ mRNA的抑制率48h、72h分别为46.40％、64.69％,蛋白抑制率72h约为74.77％。RNAi表达载体可以有效地抑制PC12细胞CaMKIIβ基因的表达。     

The Method of Random Skewers

Ecological and evolutionary studies are often concerned with the properties of covariance matrices. The method of random skewers (RS method) has been used compare a matrix to an a priori vector or to compare two matrices. The method involves multiplying a matrix by many random vectors drawn from a uniform distribution over all possible vector directions. The comparisons are usually made using the average angle (or cosine) of the response vectors to an a priori vector or to the response vectors corresponding from another matrix. Angles are usually constrained to the interval 0°–90° because the distribution of response vectors is bipolar bimodal. The size of the average angle or cosine depends strongly on the relative sizes of the eigenvalues (especially the first). The distribution of angles between pairs of response vectors from two covariance matrices is more complicated because it depends on the differences in orientation of the eigenvectors and the relative sizes of the eigenvalues of the both matrices. The average absolute value of the angles between these pairs of response vectors depends on the relative sizes of the eigenvalues of the matrices making it difficult to interpret its meaning without knowledge of the eigenvalues and eigenvectors of the two matrices. Thus, it is simpler to just directly compare matrices in terms of these quantities.