Evaluation of the Sensitivity and Specificity of Polymerase Chain Reaction Test Kit,AMPLICOR Chlamydia trachomatis

The sensitivity and specificity of the polymerase chain reaction (PCR) test kit, AMPLICOR Chlamydia trachomatis, were examined by the use of purified elementary bodies (EBs), cells having inclusions containing reticulate bodies alone and 20 clinical isolates. The numbers of EB and inclusion of C. trachomatis at the detection limit were determined to be approximately 2 to 4 EBs and one inclusion per assay, respectively. No reaction occurred for C. psittaci and C. pneumoniae. All clinical isolates were positively reacted in the PCR assay.     

双价外壳蛋白基因植物表达载体的构建及马铃薯转基因植株的鉴定

在克隆了马铃薯Ｘ病毒（ＰＶＸ）、马铃薯Ｙ 病毒（ＰＶＹ）和马铃薯卷叶病毒（ＰＬＲＶ）的外壳蛋白基因的基础上,构建同时包含ＰＶＸ和ＰＶＹ 与ＰＶＹ 和ＰＬＲＶ 两个外壳蛋白基因植物表达框架的表达载体,通过农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍ ｔｕｍｅｆａｃｉｅｎｓ）介导转化烟草（Ｎｉｃｏｔｉａｎａｔａｂａｃｕｍ ）和生产上常用的几个马铃薯（Ｓｏｌａｎｕｍ ｔｕｂｅｒｏｓｕｍ ）优良品种：“Ｆａｖｏｒｉｔａ”、“虎头”、“克４”。经ＰＣＲ检测证明外源基因已整合到植物的染色体上,得到批量转基因植株。在转ＰＶＸ＋ＰＶＹ 外壳蛋白基因的烟草上接种ＰＶＸ （５ μｇ／ｍ Ｌ）、ＰＶＹ（２０ μｇ／ｍ Ｌ）病毒,得到有一定抗性的植株     

Gene technology-based antimetabolite design: the use of an in vitro protein expression system to facilitate antimetabolite design for virally-induced human diseases and malignant conditions

A precondition for the chemotherapeutic treatment of a variety of virally-induced human diseases and malignant conditions is a highly selective interaction of the drug molecule to be used with it's biological target. To ensure the development of novel, effective drugs, it is essential that the biological target is well characterised with regard to it's structure and activity. Such characterisation relies upon adequate amounts of pure target being available. One of the most important enzymatic importers for antimetabolites is the enzyme thymidine kinase. In this article an in vitro protein expression system is described which facilitates the production of milligram amounts of pure and biologically active thymidine kinase, from a number of important biological sources. Results have shown that the in vitro produced enzyme has the exact biochemical propeties of the in vivo enzyme. Thus the in vitro protein expression system is an ideal vechicle to facilitate an in depth investigation of the enzyme's biological properties.     

Collective motions in proteins investigated by X-ray diffuse scattering

We have developed theoretical models for analysis of X-ray diffuse scattering from protein crystals. A series of models are proposed to be used for experimental data with different degrees of precision. First, we propose the normal mode model, where conformational dynamics of a protein is assumed to occur mostly in a limited conformational subspace spanned by a small number of low-frequency normal modes in the protein. When high precision data are available, variances and covariances of the normal mode variables can be determined from experimental data using this model. For experimental data with lower degrees of precision, we introduce a series of simpler models. These models express the covariance matrix using relatively simple empirical correlation functions by assuming the correlation between a pair of atoms to be isotropic. As an application of these simpler models, we calculate diffuse-scattering patterns from a human lysozyme crystal to examine how each adjustable parameter in the models affects general features of the resulting patterns. The results of the calculation are summarized as follows. (1) The higher order scattering makes a significant contribution at high resolutions. (2) The resulting simulated patterns are sensitive to changes in correlation lengths of about 1 Å, as well as to changes of the functional form of the correlation function. (3) But only the “average” value of the intra- and intermolecular correlation lengths seems to determine the gross features of the pattern. (4) The effect of the atom-dependent amplitude of fluctuations is difficult to observe. © 1994 John Wiley & Sons, Inc.     

Enantiomerization of 2,2′-diisopropylbiphenyl during chiral inclusion gas chromatography: Determination of the rotational energy barrier by computer simulation of dynamic chromatographic elution profiles

By computer simulation of experimental dynamic gas chromatographic elution profiles, the rotational energy barrier ΔG⁼ of racemic 2,2′-diisopropylbiphenyl has been determined as 114.6–115.0 kJ/mol (75–100°C). These data are in good agreement with a value that was determined previously by measuring the racemization kinetics of an enriched sample. This indicates that there is no measurable catalytic or inhibitory effect of the stationary phase. © 1994 Wiley-Liss, Inc.     

Investigation of the enantioselectivity and enantiomeric elution order of some piperidine-2,6-dione drugs on chiralcel OD column

The enantioselectivity and enantiomeric separation of five racemic piperidine-2,6-dione compounds, on the cellulose tris(3,5-dimethylphenyl carbamate) chiral stationary phase Chiralcel OD-CSP were investigated under the same chromatographic conditions. This class of drugs includes glutethimide, aminoglutethimide, cyclohexylaminoglutethimide, pyridoglutethimide, and phenglutarimide. The results revealed that chiral recognition and the binding sites of these drugs on the Chiralcel OD column are similar, regardless of the absolute configuration of the individual enantiomers. A possible chiral recognition mechanism(s) for this class of drugs and the CSP is presented. © 1994 Wiley-Liss, Inc.     

Maximization of recombinant protein yield in the insect cell/baculovirus system by one-time addition of nutrients to high-density batch cultures

Suspension cultures of Sf-9 cells at different stages of growth were infected with a recombinant baculovirus expressing -galactosidase, using a range of multiplicities of infection (MOI) of 0.05 to 50. Following infection, the cells were resuspended either in the medium in which they had been grown or in fresh medium. Specific -galactosidase yields were not markedly affected by either MOI or medium change in cultures infected in early exponential phase (3×10⁶ cells mL^–1). In cultures infected at later growth stages, -galactosidase yields could only be maintained by medium replacement. The possibility that this requirement for medium replacement is due either to the accumulation of an inhibitory byproduct or nutrient limitation was examined. Alanine, a major byproduct of cultured insect cell metabolism, did not significantly reduce recombinant protein yield when added to infected cultures in concentrations of up to 40 mM. Following a factorial design, various nutrient concentrates were added alone or in combination to cultures infected in late exponential phase. Additions that included both yeastolate ultrafiltrate and an amino acid mixture restored specific -galactosidase yields to levels observed at earlier growth stages or in late stages with medium replacement; the addition of these concentrates, by permitting production at higher cell density, led to increases in the volumetric yield of recombinant protein. Together or separately, the concentrates when added to uninfected late exponential phase cultures, lead to a doubling of the maximum total cell protein level normally supported by unamended medium.     

Conservation,protected areas and the global economic system: how debt,trade, exchange rates,inflation and macroeconomic policy affect biological diversity

The main characteristics of the dominant economic system, including the increasing use of markets and money are described. The global system has expanded trade, including international trade, and production tremendously. While this system has the potential to favour nature conservation, in practice the opposite has occurred. Difficulties raised for conservation of biodiversity by short-term economic crises such as deficits in a country's international payments, the adoption of policies for structural economic adjustment, international capital flows, international loans and foreign aid as well as debt-for-nature swaps are discussed. As explained, it is politically difficult in market economies to support nature conservation at the expense of economic growth and as more economies develop and become market economies this problem spreads. Given global interdependence of nations, an important issue is the distribution of net benefits from biodiversity conservation between developed and less developed countries. Possible distributions of benefits and related issues are discussed. In conclusion, the importance of political lobbying by nature conservation groups in developed market economies is emphasised as a means of ensuring correction of market failures. Unfortunately, no economic system is likely to prove satisfactory in itself in conserving biodiversity so political action by conservationists is always required.