氨基酸显色剂茚三酮试剂的研究（二）：不同浓度显色剂对氨基…

氨基酸显色剂是氨基酸分析的的重要试剂之一,主要成份是茚三酮、二甲亚砜、还原剂、氢氧化锂等有机试剂氨基酸显色剂（以下称显色剂）。目前这种显色剂依赖从国外进口,由于受价格、进口周期及有效期限等诸多因素的影响,使之远远不能满足国内用户的需要,为适应国内用户的需要,进一步认自制显色剂的可行性和可靠性,确定显色剂的最佳配方,本项目对自制显色剂的存放时间、不同浓度显色剂、以及显色剂光学试验等项指标进行了全面系     

贝克曼6300型氨基酸仪蛋白质水解氨基酸分析用试剂的研究

<正> 近十年来,我国进口了多种类型的氨基酸分析仪。与其它厂家的比较,贝克曼6300型氨基酸分析仪在分析灵敏度、分析速度、准确度等方面具有一定优点。但用户也感到有困难之处,那就是试剂需要从美国进口,不但价格较贵,外汇困难,而且千里迢迢,运来的试剂有变质品。为了满足本单位和国内其他用户的需要,我们开展了试剂国产化的研制。经过两年的努力,已取得较好的结果。经最近鉴定,蛋白质水解氨基酸分析所需试剂的主要性能指标已达到进口试剂水平。     

上海市超市预包装零食营养标签现况

目的：了解《食品安全国家标准预包装食品营养标签通则》（以下简称《通则》）实施情况及存在的问题,对比国内与进口零食的标识情况。方法：采用预包装食品营养标签调查法在上海市8所不同的大型超市获取食品营养标签初始信息,利用 SPSS 20.0进行数据分析。结果：国内与进口零食标识率和规范率,与前几年相比显著提高。进口零食可选择的营养素和致敏原标识率均高于国内零食,但两者均存在致敏原标识含糊的现象。结论：《通则》实施两年后,我国食品营养标签标识率显著提高。对比进口食品,国内零食在可选择的营养素和致敏原标识率方面有待完善。     

氨基酸显色剂茚三酮试剂的研究（二）──不同浓度显色剂对氨基酸含量的影响

氨基酸显色剂是氨基酸分析的重要试剂之一。主要成份是茚三酮、二甲亚砜、还原剂、氢氧化锂等有机试剂合成的氨基酸显色剂（以下称显色剂）。目前这种显色剂依赖从国外进口,由于受价格、进口周期及有效期限等诸多因素的影响,使之远远不能满足国内用户的需要,为适应国内用户的需要,进一步论证自制显色剂的可行性和可靠性,确定显色剂的最佳配方,本项目对自制显色剂的存放时间［１］、不同浓度显色剂、以及显色剂光学试验等项指标进行了全面系统地分析比较,本研究观察了１００ｍｌ溶液中显色剂含量分别为５ｍｇ、１０ｍｇ、１５ｍｇ、２０ｍｇ、２５ｍｇ等不同浓度的自制和进口显色剂对氨基酸含量的影响,结果表明,当显色剂的浓度为１５ｍｇ／１００ｍｌ时,氨基酸可出现最大峰值、测定所得氨基酸浓度显著高于２０、２５ｍｇ／１００ｍｌ和５、１０ｍｇ／１００ｍｌ所得的结果。提示氨基酸显色剂不但与存放时间有关,而且与其浓度关系密切的有关理论：     

胡芦巴多糖胶开发现状及发展对策

胡芦巴胶是我国自主研制开发的新一代半乳甘露聚糖胶.胡芦巴胶性能优良,资源丰富,在半乳甘露聚糖胶的一些应用领域完全可以替代进口瓜尔胶使用.但是近年来在进口瓜尔胶较低价格的形势下,国内胡芦巴胶产业走向发展的低谷.针对目前现状,对胡芦巴胶应用前景和产业发展的制约因素进行了讨论.     

长链二元酸工业化前景及展望

1 汽车工业是特种尼龙树脂的最大应用领域。1998年以前国内的消费量约为3000吨/年,使用的主要品种是尼龙11和尼龙12。进口价格为14万元/吨（人民币）,共4.2亿元; 2 我国每年进口服装用高档尼龙热溶胶1500吨,8万元/吨,共1.2亿元; 3 我国每年进口汽车、纺织、航空工业用的高级尼龙粉末涂料约1000吨,12万     

关于苏北地区某三甲医院进口与国产医疗设备和耗材使用情况及反馈的研究．

目的：初步了解了进口与国产医疗设备与耗材的发展状况和使用反馈情况,并对国内医疗设备与耗材行业的发展提供合理化建议。方法：通过对苏北地区某三级甲等医院设备科工作人员、医生、护士长、患者及患者家属进行调研或访谈,并以调研和访谈的统计结果为依据得出结论并提出建议。结果：技术成熟的中小型医疗设备或耗材,从质量、价格等因素综合考虑,国内产品优于进口产品,一定程度上得到了医务人员和消费者的认可。在高端大中型医疗设备与耗材方面,进口产品具有较大的技术优势。结论：国内医疗设备生产企业应当积极开展研发工作,提高产品的技术含量与质量,巩固自身在中小型医疗设备与耗材方面的优势,并努力在高端大中型医疗设备与耗材方面取得突破。     

关于苏北地区某三甲医院进口与国产医疗设备和耗材使用情况

目的:初步了解了进口与国产医疗设备与耗材的发展状况和使用反馈情况,并对国内医疗设备与耗材行业的发展提供合理化建议。方法:通过对苏北地区某三级甲等医院设备科工作人员、医生、护士长、患者及患者家属进行调研或访谈,并以调研和访谈的统计结果为依据得出结论并提出建议。结果:技术成熟的中小型医疗设备或耗材,从质量、价格等因素综合考虑,国内产品优于进口产品,一定程度上得到了医务人员和消费者的认可。在高端大中型医疗设备与耗材方面,进口产品具有较大的技术优势。结论:国内医疗设备生产企业应当积极开展研发工作,提高产品的技术含量与质量,巩固自身在中小型医疗设备与耗材方面的优势,并努力在高端大中型医疗设备与耗材方面取得突破。     

基于CMS模型的我国玉米贸易逆差影响因素分析

根据1992—2012年我国玉米贸易数据,利用恒定市场份额模型对我国玉米进出口贸易进行双向分解,分析其增长源泉,得出导致我国玉米出现贸易逆差的主要原因：在进口方面,我国玉米国内消费增长、产能不足等导致进口引力效应刺激了进口增长,这是引起我国进口快速增长的主要因素;在出口方面,我国玉米出口竞争力薄弱、出口市场结构效应未能充分发挥作用等,均在一定程度上抑制了出口的增长。应当优化我国玉米出口市场结构,提高玉米的综合品质以提高出口竞争力。     

进口血竭与国内血竭的研究对比

血竭是我国传统名贵中药,在世界各地广泛使用.本文对进口血竭与国产血竭在植物基源及生物学特征进行了比较,我们又把国内血竭称为“龙血竭”,并对血竭真伪的鉴别提供了几种简单的方法.进口与国产的血竭虽然在化学成分上有很大不同,但是药理作用很相似,所以我国的龙血竭完全可以替代进口血竭在临床上使用,市场上出现了很多不同的血竭剂型.针对现在国内外血竭资源的处于濒危的状况,我们需要增强血竭资源保护意识,使血竭资源能可持续利用.     

Comprehensive evaluation of protein structure alignment methods: scoring by geometric measures

We report the largest and most comprehensive comparison of protein structural alignment methods. Specifically, we evaluate six publicly available structure alignment programs: SSAP, STRUCTAL, DALI, LSQMAN, CE and SSM by aligning all 8,581,970 protein structure pairs in a test set of 2930 protein domains specially selected from CATH v.2.4 to ensure sequence diversity. We consider an alignment good if it matches many residues, and the two substructures are geometrically similar. Even with this definition, evaluating structural alignment methods is not straightforward. At first, we compared the rates of true and false positives using receiver operating characteristic (ROC) curves with the CATH classification taken as a gold standard. This proved unsatisfactory in that the quality of the alignments is not taken into account: sometimes a method that finds less good alignments scores better than a method that finds better alignments. We correct this intrinsic limitation by using four different geometric match measures (SI, MI, SAS, and GSAS) to evaluate the quality of each structural alignment. With this improved analysis we show that there is a wide variation in the performance of different methods; the main reason for this is that it can be difficult to find a good structural alignment between two proteins even when such an alignment exists. We find that STRUCTAL and SSM perform best, followed by LSQMAN and CE. Our focus on the intrinsic quality of each alignment allows us to propose a new method, called "Best-of-All" that combines the best results of all methods. Many commonly used methods miss 10-50% of the good Best-of-All alignments. By putting existing structural alignments into proper perspective, our study allows better comparison of protein structures. By highlighting limitations of existing methods, it will spur the further development of better structural alignment methods. This will have significant biological implications now that structural comparison has come to play a central role in the analysis of experimental work on protein structure, protein function and protein evolution.     

Numerical simulation of iontophoresis in the drug delivery system

The architecture and composition of stratum corneum act as barriers and limit the diffusion of most drug molecules and ions. Much effort has been made to overcome this barrier and it can be seen that iontophoresis has shown a good effect. Iontophoresis represents the application of low electrical potential to increase the transport of drugs into and across the skin or tissue. Iontophoresis is a noninvasive drug delivery system, and therefore, it is a useful alternative to drug transportation by injection. In this study, we present a numerical model and effects of electrical potential on the drug diffusion in the buccal tissue and the stratum corneum. The initial numerical results are in good comparison with experimental observation. We demonstrate that the application of an applied voltage can greatly improve the efficacy of localized drug delivery as compared to diffusion alone.     

Studies on the recognition of specific sensitization to tumor antigens by measuring passive electrical additive effects as against the electrophoretic mobility test]

Lymphocytes from cancer patients were incubated with different tumor antigens. In the medium in which the lymphocytes were suspended, passive electrical values could be measured in the Mc region. These values correlate with a specific sensibilization of tumor carriers. By comparison with the electrophoresis-mobility test (em-test) we found in 66 out of 74 supernatants, using CEA and KCl-extracts as antigens, a good conformity of the two reaction patterns.     

Experimental prediction of the evolution of cefepime resistance from the CMY-2 AmpC beta-lactamase

Understanding of the evolutionary histories of many genes has not yet allowed us to predict the evolutionary potential of those genes. Intuition suggests that current biochemical activity of gene products should be a good predictor of the potential to evolve related activities; however, we have little evidence to support that intuition. Here we use our in vitro evolution method to evaluate biochemical activity as a predictor of future evolutionary potential. Neither the class C Citrobacter freundii CMY-2 AmpC beta-lactamase nor the class A TEM-1 beta-lactamase confer resistance to the beta-lactam antibiotic cefepime, nor do any of the naturally occurring alleles descended from them. However, the CMY-2 AmpC enzyme and some alleles descended from TEM-1 confer high-level resistance to the structurally similar ceftazidime. On the basis of the comparison of TEM-1 and CMY-2, we asked whether biochemical activity is a good predictor of the evolutionary potential of an enzyme. If it is, then CMY-2 should be more able than the TEMs to evolve the ability to confer higher levels of cefepime resistance. Although we generated CMY-2 evolvants that conferred increased cefepime resistance, we did not recover any CMY-2 evolvants that conferred resistance levels as high as the best cefepime-resistant TEM alleles.     

Deterministic model for the transport of energetic particles: Application in the electron radiotherapy

A new deterministic method for calculating the dose distribution in the electron radiotherapy field is presented. The aim of this work was to validate our model by comparing it with the Monte Carlo simulation toolkit, GEANT4. A comparison of the longitudinal and transverse dose deposition profiles and electron distributions in homogeneous water phantoms showed a good accuracy of our model for electron transport, while reducing the calculation time by a factor of 50. Although the Bremsstrahlung effect is not yet implemented in our model, we propose here a method that solves the Boltzmann kinetic equation and provides a viable and efficient alternative to the expensive Monte Carlo modeling.     

Quantifying the randomness of extinctions

Extinctions occur either randomly or in a more deterministic and predictable manner, with certain characteristics making some species more vulnerable to (local) extinction than others. Although the quantification of extinction randomness would better our understanding of the extinction causes and increase the predictability of future species losses, few quantification methods are currently available. To this purpose, we propose two indices based on a comparison of an a priori (expected) extinction series with an observed one. Whereas the first index requires data on the order of extinctions, the second index is only concerned with which species went extinct and which did not. Using a model for generating extinction data, we tested both indices successfully for accordance with the robustness prerequisites. Index outputs were furthermore unaffected by species richness, apart from decreased variation with rising species numbers. Because of its independence of non-extinct species and its focus on extinction sequences, the first randomness index seems especially useful for use in paleontological and paleo-ecological research. The second index is likely a good tool to study shorter term extinctions, for which the extinction order is often not known and for which the comparison with species that did persist is of greater interest. We use a real dataset to illustrate this. Finally, we discuss how it is possible to expand the use of this index toward identifying previously unknown extinction-promoting species characteristics, and toward a credible assessment of the extinction risk posed by global change.     

A Simple Extension to the CMASA Method for the Prediction of Catalytic Residues in the Presence of Single Point Mutations

The automatic identification of catalytic residues still remains an important challenge in structural bioinformatics. Sequence-based methods are good alternatives when the query shares a high percentage of identity with a well-annotated enzyme. However, when the homology is not apparent, which occurs with many structures from the structural genome initiative, structural information should be exploited. A local structural comparison is preferred to a global structural comparison when predicting functional residues. CMASA is a recently proposed method for predicting catalytic residues based on a local structure comparison. The method achieves high accuracy and a high value for the Matthews correlation coefficient. However, point substitutions or a lack of relevant data strongly affect the performance of the method. In the present study, we propose a simple extension to the CMASA method to overcome this difficulty. Extensive computational experiments are shown as proof of concept instances, as well as for a few real cases. The results show that the extension performs well when the catalytic site contains mutated residues or when some residues are missing. The proposed modification could correctly predict the catalytic residues of a mutant thymidylate synthase, 1EVF. It also successfully predicted the catalytic residues for 3HRC despite the lack of information for a relevant side chain atom in the PDB file.     

Interactions of urocanic acid with bovine serum albumin and the influence of pH on binding affinities: a docking simulation study

In the present study, the interactions of urocanic acid (UA) with bovine serum albumins (BSA) at pH 5.0 and 7.4 were investigated by means of docking simulations. The binding modes of trans- and cis-UA to BSA at pH 5.0 and 7.4 were analysed. In addition, the theoretically predicted binding abilities of zwitterion and anion of UA with BSA are in good agreement with the experimental results. Through comparison with the binding patterns, we revealed that the stronger interactions of UA anion with BSA relative to the zwitterion primarily result from: (1) the increased number of hydrogen bonds between UA anion and BSA; (2) the attractive electrostatic interaction between the deprotoned carboxyl group in UA anion and Arg433 in comparison with the repulsion between the imidazole moiety in zwitterion and the same residue in BSA. This provides a rational explanation for the experimental finding that the binding of UA to BSA at pH 7.4 is much stronger than at pH 5.0.     

Do ants make direct comparisons?

Many individual decisions are informed by direct comparison of the alternatives. In collective decisions, however, only certain group members may have the opportunity to compare options. Emigrating ant colonies (Temnothorax albipennis) show sophisticated nest-site choice, selecting superior sites even when they are nine times further away than the alternative. How do they do this? We used radio-frequency identification-tagged ants to monitor individual behaviour. Here we show for the first time that switching between nests during the decision process can influence nest choice without requiring direct comparison of nests. Ants finding the poor nest were likely to switch and find the good nest, whereas ants finding the good nest were more likely to stay committed to that nest. When ants switched quickly between the two nests, colonies chose the good nest. Switching by ants that had the opportunity to compare nests had little effect on nest choice. We suggest a new mechanism of collective nest choice: individuals respond to nest quality by the decision either to commit or to seek alternatives. Previously proposed mechanisms, recruitment latency and nest comparison, can be explained as side effects of this simple rule. Colony-level comparison and choice can emerge, without direct comparison by individuals.