A Comparison of Alternative Methods to Viable Count for Indicating Growth of Mycoplasma gallisepticum in Liquid Culture

In an attempt to find a more rapid method than a viable count for estimating growth of Mycoplasma gallisepticum in broth culture, seven alternative methods were each examined for their correlation with viable counts, reproducibility and time taken to obtain results. Opacity measurement was the quickest and showed closest correlation with viable count and also high reproducibility. The other methods examined showed either lack of sensitivity or reproducibility or poorer correlation with viable count.     

天然活性成分作用靶点识别及确证方法的研究进展

药物靶标的发现和验证是新药研发的关键环节,对新药创制具有源头创新意义。天然产物是新药创制的重要来源,识别其作用靶点不仅为临床预防治疗提供可能新策略,也为进一步阐释中草药及其复方的作用特点及分子机制提供参考依据。随着生命科学和信息学的发展,药物靶点的识别及确证方法不断涌现,生物信息学、网络药理学、蛋白质组学、亲和色谱、药物亲和稳定性、芯片技术、基因敲除技术、RNA干扰等技术的广泛应用,越来越多的天然活性成分的靶点得以识别和验证。因此,本文对近五年来天然活性成分作用靶点识别及确证方法做一简要综述,以供参考。     

A Comparison of Two Ultrasonic Methods for Detaching Biofilms from Natural Substrata

Two types of ultrasound applications are commonly used in order to remove bacteria from sediment for subsequent direct enumeration: ultrasonic baths and narrow tip ultrasonic generators. By measuring four parameters (total number of bacteria, number of ETS‐active bacteria, amount of proteins and weight of fine sediment obtained in sonicated juices), we compared the biofilm removal of the optimal ultrasound exposure time previously obtained using the ultrasonic bath with the removal by a method using a narrow tip ultrasonic generator. To obtain comparable removal efficiencies estimated by protein contents in sonicated juices, the ultrasonic bath method required an ultrasound exposure time more than 10 times that with a narrow tip ultrasonic generator. Furthermore, the two methods provided significantly different bacterial counts because of an alteration of the sediment with the ultrasonic bath. Thus, a narrow tip ultrasonic generator is more suitable than an ultrasonic bath for the analysis of biofilms developed on sand.     

Adulteration of Ginkgo biloba products and a simple method to improve its detection

Extracts of ginkgo (Ginkgo biloba) leaf are widely available worldwide in herbal medicinal products, dietary supplements, botanicals and complementary medicines, and several pharmacopoeias contain monographs for ginkgo leaf, leaf extract and finished products. Being a high-value botanical commodity, ginkgo extracts may be the subject of economically motivated adulteration. We analysed eight ginkgo leaf retail products purchased in Australia and Denmark and found compelling evidence of adulteration with flavonol aglycones in three of these. The same three products also contained genistein, an isoflavone that does not occur in ginkgo leaf.Although the United States Pharmacopeia – National Formulary (USP-NF) and the British and European Pharmacopoeias stipulate a required range for flavonol glycosides in ginkgo extract, the prescribed assays quantify flavonol aglycones. This means that these pharmacopoeial methods are not capable of detecting adulteration of ginkgo extract with free flavonol aglycones.We propose a simple modification of the USP-NF method that addresses this problem: by assaying for flavonol aglycones pre and post hydrolysis the content of flavonol glycosides can be accurately estimated via a simple calculation. We also recommend a maximum limit be set for free flavonol aglycones in ginkgo extract.     

A Comparison of Methods to Measure Fitness in Escherichia coli

In order to characterize the dynamics of adaptation, it is important to be able to quantify how a population’s mean fitness changes over time. Such measurements are especially important in experimental studies of evolution using microbes. The Long-Term Evolution Experiment (LTEE) with Escherichia coli provides one such system in which mean fitness has been measured by competing derived and ancestral populations. The traditional method used to measure fitness in the LTEE and many similar experiments, though, is subject to a potential limitation. As the relative fitness of the two competitors diverges, the measurement error increases because the less-fit population becomes increasingly small and cannot be enumerated as precisely. Here, we present and employ two alternatives to the traditional method. One is based on reducing the fitness differential between the competitors by using a common reference competitor from an intermediate generation that has intermediate fitness; the other alternative increases the initial population size of the less-fit, ancestral competitor. We performed a total of 480 competitions to compare the statistical properties of estimates obtained using these alternative methods with those obtained using the traditional method for samples taken over 50,000 generations from one of the LTEE populations. On balance, neither alternative method yielded measurements that were more precise than the traditional method.     

Estimates of Inbreeding in a Natural Population: A Comparison of Sampling Properties

The average inbreeding coefficient f of a population can be estimated in several different ways based solely on the genotypic frequencies at a single locus. The means and variances of four different estimates have been compared. While the four estimates are equivalent when there are two alleles, the best estimates when there are three or more alleles are based upon total heterozygosity (see PDF) where x and y are the expected and observed number of heterozygotes) and the proportion of alleles that are homozygous (see PDF) where k = the number of alleles, a_ii = the number of A_iA_i homozygotes, and 2a_ij = the number of A_iA_j heterozygotes). Both are minimally biased estimates of f and have identical sampling variances when all alleles are equally frequent. However, when alleles have different frequencies, the choice between these two estimates depends on the gene frequencies and the true inbreeding coefficient of a population; f₂ is the best estimate when the true average inbreeding coefficient is suspected to be low or f = 0, while f₁ is best in populations with large average inbreeding coefficients. Approximate sampling variances of these two estimates are given for any f and any number of alleles with arbitrary gene frequencies; these approximations are accurate for samples as small as n = 100. The chi-square and maximum likelihood estimates of f are not as good for realistic sample sizes.     

Alternative statistical approaches to the use of data as evidence for hypotheses in human behavioral ecology

In their ambitious Evolutionary Anthropology paper, Winterhalder and Smith 1 review the history, theory, and methods of human behavioral ecology (HBE). In establishing how HBE differs from traditional approaches within sociocultural anthropology, they and others laud its hypothetical‐deductive research method. 1 - 3 Our aim is to critically examine how human behavioral ecologists conduct their research, specifically how they analyze and interpret data as evidence for scientific hypotheses. Through computer simulations and a review of empirical studies of human sex ratios, we consider some limitations of the status quo and present alternatives that could strengthen the field. In particular, we suggest that because human behavioral ecologists often consider multiple hypotheses, they should use statistical approaches that can quantify the evidence in empirical data for competing hypotheses. Although we focus on HBE, the principles of this paper apply broadly within biological anthropology.     

A multivariate generalization of the FRIEDMAN rank test with application to a problem in molecular biology

A series of experiments was recently undertaken at the National Institutes of Health to ascertain whether tRNA populations are determined by or adapted to the major proteins synthesized by tumor cells. Dissimilarity indices between chromatographic profiles of animoacyl-tRNAs from 11 mouse plasmacytomas and from normal adult mouse liver and brain were calculated and then compared using a multivariate generalization of the FRIEDMAN rank test. This test is described herein, and its use is illustrated with data from the experiments.     

Liquid chromatography determination of 10-hydroxycamptothecin in human serum by a column-switching system containing a pre-column with restricted access media and its application to a clinical pharmacokinetic study

A simple, rapid, sensitive column-switching HPLC method is described for the analysis of the 10-hydroxycamptothecin (HCPT) in human serum. A pre-column containing restricted access media (RAM) is used for the sample clean-up and trace enrichment and is combined with a C18 column for the final separation. The analytical time is 8 min. The HCPT is monitored with fluorescence detector, excitation and emission wavelengths being 385 and 539 nm, respectively. There is a linear response range of 1-1000 ng/ml with correlation coefficient of 0.998 while the limit of quantification is 0.1 ng/ml. The intra-day and inter-day variations are less than 5%. This analytic procedure has been applied to a pharmacokinetic study of HCPT in clinical patients and the pharmacokinetic parameters of one-compartment model are calculated.     

A New Approach to Natural Products Discovery Exemplified by the Identification of Sulfated Nucleosides in Spider Venom

A New Approach to Natural Products Discovery Exemplified by the Identification of Sulfated Nucleosides in Spider Venom@Andrew E. Taggi$Contribution from The Cornell Institute for Research in Chemical Ecology and The Department of Chemistry and Chemical Biology, Baker Laboratory,Cornell UniVersity, Ithaca, New York 14853 @Jerrold Meinwald$Contribution from The Cornell Institute for Research in Chemical Ecology and The Department of Chemistry and Chemical Biology, Baker Lab…     

Intraindividual Scale Comparison in Clinical Diagnostic Methods: A Review of Elementary Methods

This text tries to summarize proposals on the statistical comparison of clinical measurement methods based on bivariate normally distributed outcome. It mainly concentrates on design adequate intraindividual comparison of variances in repeated measurements and reviews univariate graphical and numerical representations of corresponding deviations. The latter will be illustrated by the comparison of two cardiac imaging procedures in 28 probands.     

A Numerical Comparison of Some BAYESian Methods of Estimating a Binomial Parameter

This note considers the optimal and suboptimal sequential and fixed sample size estimation of the unknown binomial parameter, p, for a beta prior distribution for p and under quadratic loss and constant observation cost. A numerical comparison of the methods is presented.     

A Comparison of Methods to Measure Operator Protection Factors in Open-fronted Microbiological Safety Cabinets

Comparative tests to measure operator protection factors in microbiological safety cabinets in accordance with British Standard 5726 have demonstrated good agreement in the results obtained by a microbiological method using a Collison nebulizer and the technique producing an aerosol of potassium iodide. Either method is suitable for testing for operator protection factors in Class I and Class II safety cabinets.
The Collison nebulizer should be considered as the standard aerosol generator for the microbiological method; alternative nebulizers meeting the general requirements of BS 5726 should be compared in performance with this nebulizer if they are to be used for containment tests.
Any microbiological safety cabinet specified for a new installation should have been 'type' tested to ensure compliance with BS 5726. However, in order to ensure adequate performance, on-site commissioning tests (and routine maintenance checks thereafter) are necessary to verify that air velocity, filtration and operator protection factor requirements are met.     

Defining Natural Categories in Acoustic Signals: Comparison of Three Methods Applied to ‘Chick-a-dee’ Call Notes

Chicks were trained to discriminate between two identical boxes on the basis of their position. Subsequently, the colour of parts of the positive (reinforced) box was changed and chicks were retrained. Results showed that chicks were more or less impaired during retraining depending on the spatial distribution of the changed stimuli. Chicks behaved as if a figure (a disc or a spot of dots) painted on a box was irrelevant to them, whereas they did respond to changes in the colour of a uniformly coloured box or of scattered dots painted on a box. Similar results were obtained in simultaneous discrimination learning tasks involving addition of cues (e.g. colour plus position). Addition of cues facilitated learning using boxes the same colour all over or with painted scattered dots, but not using boxes with a disc or a spot of dots. Furthermore, addition of shape and position information had different outcomes depending on the use of three-dimensional objects or of painted figures: learning facilitation occurred only using three-dimensional objects. Results are interpreted in terms of an “object hypothesis”, and the validity and usefulness of traditional terms such as cues is questioned.     

The benefits of being dominant: health correlates of male social rank and age in a marmot

The benefits of dominance may not come without costs, particularly for males. For example, the “immunocompetence handicap hypothesis” states that males with enhanced mating success allocate resources to enhance reproductive output at a cost to their current health, whereas the “resource quality hypothesis” predicts that high-ranking males may benefit from increased reproduction and good health. Whereas the predictions from each have been well tested in captive animals and in a variety of highly social primates, fewer studies have been carried out in free-living, facultatively social animals. Using adult male yellow-bellied marmots (Marmota flaviventer), we evaluated predictions of these hypotheses by examining the relationship between social rank and 2 health indicators—fecal glucocorticoid metabolite (FCM) levels, and neutrophil/lymphocyte (N/L) ratios—after accounting for variation explained by age, body mass, and seasonality. We found that higher-ranking males tended to have a lower N/L ratio (reflecting good health) than lower-ranking individuals, whereas FCM levels were not significantly related to rank. In addition, heavier male marmots had lower N/L ratios, whereas body mass was not associated with FCM levels. We also found that older adult males had lower FCM levels (reflecting less physiological stress) but higher N/L ratios than younger adults. Finally, we found that FCM levels decreased as the active season progressed and FCM levels were associated with the time of the day. Overall, our results suggest that socially-dominant male marmots enjoyed better, not worse health in terms of lower N/L ratios.     

美国香辛料产品质量现状

简述了美国香辛料生产现状、国内质量需求和进口香辛料存在问题以及香辛料发展战略。     

A Comparison of Two Methods to Conduct Material Flow Analysis on Waste Tires in a Small Island Developing State

The disposal of scrap tires is one of the biggest solid waste issues facing some small island developing states (SIDS) in the Caribbean. Dominica is a small Caribbean island nation that seeks to maintain its well‐founded image as the “Nature Island of the Caribbean.” The economy has seen a steadily increasing import of both tires and cars, with no mechanism for exportation of spent tires. This study used data gathered from both government and international sources to estimate the quantity of tires currently on the island and projected each year up to 2020 to determine potential reuse options. We performed a material flow analysis (MFA) using tire import, vehicle registration records, and projected per capita income to determine the expected accumulation of waste tires. Vehicle registration is expected to rise with the island's wealth, which will affect the annual flow of tires. Two methods were used to predict vehicle growth over time. Our analysis showed an average waste tire output from the economy of 47,000 to 50,000 passenger tire equivalents (PTEs) per year, or approximately 470 to 500 short tons per year of mass. Such an output does not justify large expenditures of tire shredding and processing equipment, but whole tire applications may be feasible as potential disposition options. The methods can be easily replicated to give low‐range and high‐range estimates of waste tires disposed in the environment.