显示细胞有丝分裂的一种理想方法

本文介绍一种显示植物细胞有丝分裂各个时期的方法,该方法效果明显,易于掌握,是一种较理想的实验教学方法。     

群落谱系结构研究方法及其在昆虫学上的应用

群落谱系结构的研究是近年来才兴起的一种方法,其最大的特点是可以结合进化因素和环境因素来共同分析群落中物种的组成和动态变化,群落谱系方法已经得到了广泛的应用,然而把这一方法应用到昆虫学这一领域还极少。本文主要介绍这一方法的理论知识、群落谱系结构的计算方法以及群落谱系研究方法在昆虫领域的应用前景。     

用单个细胞转移技术进行杂交瘤的克隆化

<正>本文所报导的克隆杂交瘤的方法,是用一根毛细管连接一套抽吸装置,进行单个细胞的转移。这一方法可以有效地从培养的亲本杂交瘤中重新获得数量比例不同的抗体产生克隆。4个细胞株用这一方法再克隆获的了100％阳性。     

磁疗法的研究与应用进展

应用磁场作用于穴位或病变局部,达到治疗或促进健康目的的方法,称为磁疗法。磁疗法已成为一种常用的治疗方法,很多医院均设有磁疗室。磁场不仅作为一种治疗方法,而且也作为一种促进健康的手段,通过磁场的作用,提高健康水平。     

用模式识别方法预测蛋白质的二级结构

本文建立了用模式识别理论和技术在计算机上预测蛋白质二级结构的方法.特征的抽取和样本的选择是使用该方法的关键.这一方法与其他方法相比各有特色,预测精度也比较高,鉴于目前国内外将此方法用于蛋白结构预测的研究的还不多,我们拟进一步发展、完善这一方法.     

用塑料薄膜悬浮培养鸡胚

用塑料薄膜进行鸡胚的无壳悬浮培养是最简便、最经济的方法。这一方法最早由Dunn(1974)发明,本文作者曾将这一方法改进后在课堂上使用多年,用来研究胚胎发育。实验材料在这里采用的培养室是改进了Dunn等(1981)的方法。培养室由四部分组成(如图1所示):一根直径和长度为7.62厘米的塑料排水管,作为托座,托住一张塑料薄膜。用一个开     

烟草花粉管生长信号转导研究中一种简单的RNA提取方法(简报)

液氮研磨是一种从具有坚韧细胞壁的植物细胞中提取RNA的常规方法.然而,对于那种不易得到的少量的植物材料如花粉,这种方法的操作显得尤为困难.针对这一问题.本论文描述了一种不涉及液氮研磨的一种简单的RNA提取方法:改变萌发花粉管的渗透压使其破裂而释放RNA.这一方法减少了RNA抽提材料的用量并且提高了RNA的抽提效率,用于RNA抽提的花粉的量可以少至一个花药.后续的RNA分析需要的花粉可以少至1O毫克,这一用量相当于从50个烟草花药中得到的量.这一RNA提取方法的可靠性和可操作性为研究花粉管生长过程中对细胞外信号响应的基因时空表达提供了有益的参考.     

用模式识别方法预测蛋白质的二级结构

本文建立了用模式识别理论和技术在计算机上预测蛋白质二级结构的方法.特征的抽取和样本的选择是使用该方法的关键.这一方法与其他方法相比各有特色,预测精度也比较高,鉴于目前国内外将此方法用于蛋白结构预测的研究的还不多,我们拟进一步发展、完善这一方法.     

Cell Chem Biol:科学家成功利用模拟进化的方法来治疗癌症

正最近,一项刊登于国际杂志Cell Chemical Biology上的研究报告中,来自维多利亚大学等机构的研究人员通过研究开发了一种新型的化疗方法来专门靶向作用癌细胞。这种化疗方法是一种具有高度靶向性的方法,其能够对癌症患者进行有效治疗,同时副作用还较小。研究者David Ackerley教授表示,我们通过对一种酶类进行工程化操作,使其能够将一种相对安全且无毒性的化合物(前体药物,pro-drug)     

类黄酮的毛细管电泳和高效液相色谱分离比较研究

类黄酮的高效液相分析是一种传统上认可的方法,而毛细管电泳是一种新兴的却强有力的分析方法。但是,关于这两种方法在类黄酮分析上的比较的文献却很少。本文的目的即是用此两种方法比较一组类黄酮的分离效果。     

重组乙型肝炎疫苗(CHO细胞)鉴别试验的方法研究

目的：建立重组乙型肝炎疫苗(CHO细胞)鉴别试验的方法。方法：取重组乙型肝炎疫苗(CHO细胞)以1：10比例加入lmol/L盐酸调节pH值,采用ELISA双抗体夹心法检测,同时设以氢氧化铝、未处理的重组乙型肝炎疫苗、狂犬疫苗、出血热疫苗,以及试剂盒的阴、阳性作为对照。结果：狂犬疫苗、出血热疫苗及氢氧化铝对照为阴性,直接检测重组乙型肝炎疫苗(CHO细胞)呈弱阳性,加入盐酸调节pH值后原倍样品呈弱阳性,10倍稀释后呈强阳性。采用该方法检测5批疫苗均呈强阳性。组内平行试验,组间重复试验。结论：将重组乙型肝炎疫苗(CHO细胞)调节pH值后10倍稀释,用ELISA双抗体夹心法检测呈阳性,而且稳定可靠,该方法可用于该疫苗的鉴别试验。     

MODELING BRAIN EVOLUTION FROM BEHAVIOR: A PERMUTATIONAL REGRESSION APPROACH

This paper has two complementary purposes: first, to present a method to perform multiple regression on distance matrices, with permutation testing appropriate for path-length matrices representing evolutionary trees, and then, to apply this method to study the joint evolution of brain, behavior and other characteristics in marsupials. To understand the computation method, consider that the dependent matrix is unfolded as a vector y; similarly, consider X to be a table containing the independent matrices, also unfolded as vectors. A multiple regression is computed to express y as a function of X. The parameters of this regression (R² and partial regression coefficients) are tested by permutations, as follows. When the dependent matrix variable y represents a simple distance or similarity matrix, permutations are performed in the same manner as the Mantel permutational test. When it is an ultrametric matrix representing a dendrogram, we use the double-permutation method (Lapointe and Legendre 1990, 1991). When it is a path-length matrix representing an additive tree (cladogram), we use the triple-permutation method (Lapointe and Legendre 1992). The independent matrix variables in X are kept fixed with respect to one another during the permutations. Selection of predictors can be accomplished by forward selection, backward elimination, or a stepwise procedure. A phylogenetic tree, derived from marsupial brain morphology data (28 species), is compared to trees depicting the evolution of diet, sociability, locomotion, and habitat in these animals, as well as their taxonomy and geographical relationships. A model is derived in which brain evolution can be predicted from taxonomy, diet, sociability and locomotion (R² = 0.75). A new tree, derived from the “predicted” data, shows a lot of similarity to the brain evolution tree. The meaning of the taxonomy, diet, sociability, and locomotion predictors are discussed and conclusions are drawn about the evolution of brain and behavior in marsupials.     

一种简单快捷的改良V-P、MR试验方法

在白瓷板上进行V-P试验,结果表明,用白瓷板法只需加几滴培养液后静置等待结果出现即可,与传统的试管法比较更为简单方便,试验结果更为直观和科学。而且,进行V-P试验时可以方便地同时在白瓷板上做MR试验。     

On the use of historical control data for trend test in carcinogenicity studies

Historical control data are often available in carcinogenicity studies and are included for testing dose effects in current studies. A new method is developed for incorporating the historical control information into a dose effect test. The method generalizes the test procedures proposed by Tarone (1982, Biometrics 38, 215-220) and Ibrahim and Ryan (1996, Biometrics 52, 1478-1485) by taking into account the variation resulting from parameter estimation based on historical data. Two examples are discussed for illustrating the proposed method.     

Note on a binomial test against sectoral preference of circular observations

A binomial test is proposed to test the nullhypothesis of uniform distribution of circular observations against the alternative of sectoral preference where the sector in which the observations are expected to cluster must be chosen prior to sampling. This binomial test against sectoral preference is illustrated by an example from psychopharmacology. The method is modified for comparing the sectoral proportions of two independent as well as two paired samples of circular observations.     

Analyzing Incomplete Data Subject to a Threshold using Empirical Likelihood Methods: An Application to a Pneumonia Risk Study in an ICU Setting

Summary .  The initial detection of ventilator-associated pneumonia (VAP) for inpatients at an intensive care unit needs composite symptom evaluation using clinical criteria such as the clinical pulmonary infection score (CPIS). When CPIS is above a threshold value, bronchoalveolar lavage (BAL) is performed to confirm the diagnosis by counting actual bacterial pathogens. Thus, CPIS and BAL results are closely related and both are important indicators of pneumonia whereas BAL data are incomplete. To compare the pneumonia risks among treatment groups for such incomplete data, we derive a method that combines nonparametric empirical likelihood ratio techniques with classical testing for parametric models. This technique augments the study power by enabling us to use any observed data. The asymptotic property of the proposed method is investigated theoretically. Monte Carlo simulations confirm both the asymptotic results and good power properties of the proposed method. The method is applied to the actual data obtained in clinical practice settings and compares VAP risks among treatment groups.     

Valid inference in random effects meta-analysis

The standard approach to inference for random effects meta-analysis relies on approximating the null distribution of a test statistic by a standard normal distribution. This approximation is asymptotic on k, the number of studies, and can be substantially in error in medical meta-analyses, which often have only a few studies. This paper proposes permutation and ad hoc methods for testing with the random effects model. Under the group permutation method, we randomly switch the treatment and control group labels in each trial. This idea is similar to using a permutation distribution for a community intervention trial where communities are randomized in pairs. The permutation method theoretically controls the type I error rate for typical meta-analyses scenarios. We also suggest two ad hoc procedures. Our first suggestion is to use a t-reference distribution with k-1 degrees of freedom rather than a standard normal distribution for the usual random effects test statistic. We also investigate the use of a simple t-statistic on the reported treatment effects.     

Application of new enhanced medium in indirect antiglobulin test by gel method

The objective of this study was to explore the efficacy of a new enhanced medium in indirect antiglobulin test by optimized gel method. Anti-IgG+ C3d and anti-IgG antiglobulin gel cards, and samples from three blood group systems: Rh, Kidd and MNSs were used. The new enhanced medium was incubated at 37°C for 5 minutes, low ionic strength solution (LISS) for 15 minutes, saline solution for 30 minutes, respectively. The sensitivity and specificity of blood group antibodies were then compared. The results showed that the specificity and sensitivity of the new enhanced medium incubated for 5 minutes were consistent with those of LISS and saline solution for 15 minutes and 30 minutes, respectively. The results suggest that the new enhanced medium be able to accelerate the binding of erythrocyte antibodies with antigens, reduce incubation time and optimize the detection process of indirect antiglobulin test by gel method.     

Sensitivity analysis for m-estimates, tests, and confidence intervals in matched observational studies

Huber's m-estimates use an estimating equation in which observations are permitted a controlled level of influence. The family of m-estimates includes least squares and maximum likelihood, but typical applications give extreme observations limited weight. Maritz proposed methods of exact and approximate permutation inference for m-tests, confidence intervals, and estimators, which can be derived from random assignment of paired subjects to treatment or control. In contrast, in observational studies, where treatments are not randomly assigned, subjects matched for observed covariates may differ in terms of unobserved covariates, so differing outcomes may not be treatment effects. In observational studies, a method of sensitivity analysis is developed for m-tests, m-intervals, and m-estimates: it shows the extent to which inferences would be altered by biases of various magnitudes due to nonrandom treatment assignment. The method is developed for both matched pairs, with one treated subject matched to one control, and for matched sets, with one treated subject matched to one or more controls. The method is illustrated using two studies: (i) a paired study of damage to DNA from exposure to chromium and nickel and (ii) a study with one or two matched controls comparing side effects of two drug regimes to treat tuberculosis. The approach yields sensitivity analyses for: (i) m-tests with Huber's weight function and other robust weight functions, (ii) the permutational t-test which uses the observations directly, and (iii) various other procedures such as the sign test, Noether's test, and the permutation distribution of the efficient score test for a location family of distributions. Permutation inference with covariance adjustment is briefly discussed.     

The Statistical Significance of Mutation Frequencies

TRAUT has proposed a method for determining the statistical significance between a mutation frequency observed after treatment with a potential mutagen and a control frequency. The method is developed further by us for an easier practical use. A table for the minimal sample size in the region of interest for the sex-linked recessive lethal test in Drosophila melanogaster has been calculated. TRACT'S test is compared with FISHER'S exact test and the KASTENBAUM -BOWMAN test. TRAUT'S test turns out to be more sensitive than the other tests. This observation strongly supports TRAUT'S conclusion that his test should only be used if very accurate determinations of the spontaneous frequencies are available.