Stable, soluble T-cell receptor molecules for crystallization and therapeutics

Antibody and T-cell receptors (TCRs) are the primary recognitionmolecules of the adaptive immune system. Antibodies have beenextensively characterized and are being developed for a largenumber of therapeutic applications. This has been possible becauseof the ability to manufacture stable, soluble, monoclonal antibodieswhich retain the antigen specificity of B cells. Unlike antibodies,TCRs are not expressed in a soluble form, but are anchored tothe T-cell surface by an insoluble trans-membrane domain. Characterizationand development of TCRs has been hampered by the lack of suitablemethods for producing them as soluble and stable proteins. Herewe report the engineering of soluble human TCRs suitable forcrystallization studies and potentially for in vivo therapeuticuse. Received March 11, 2003; revised July 1, 2003; accepted July 30, 2003.     

Amino acid analyses of germinating seeds of some members of the leguminosae

The free and bound amino acid contents of soaked seeds and 7- and 14-day old seedlings of Pisum sativum, Phaseolus vulgaris and Canavalia eniformis were determined. It was found that on germination the free amino acid content of the plants increased, while the total amount of amino acid decreased. Most of the essential amino acids were shown to be present in the plants.     

A real-time self-tuning web tension regulation scheme

A self-tuning control scheme is proposed for tension regulation in a web transport system. A computationally efficient self-tuning method is first described. The frequency domain model of the plant is then described. Simulations of the on-line tuning are presented. The paper closes with a discussion of cognizant real-time implementation issues.     

Crude protein and sulphur amino acid contents of some commercial varieties of peas and beans

Spring field bean varieties contain more protein than peas, but fluctuating yields often confuse results. Peas have a higher sulphur amino acid content than beans, but potential sulphur amino acid yield ha^?1 is greater in the latter. The biological value in rat feeding trials closely reflected the sulphur amino acid content. A negative correlation was found between protein sulphur amino acid content and percentage seed protein.     

Selecting the right drive

This article provides guidelines for the useful interpretation of AC/DC torque/current performance specifications, from a drive system's application perspective. The objective of this article is to bring those performance specifications that apply to torque/current regulation into technical focus and provide the reader with a basis for correctly interpreting them from a systems/application perspective. Future articles will address performance issues associated with "cascaded" and "parallel", position- and tension-regulation schemes. Speed-regulation issues are also addressed in this article.     

Improving bridle low-speed regulation using cascaded currentfollowers

The torque or current references to the current loops of drives providing power to helper rolls in bridles are usually slaved directly from the current reference of the master speed-regulated roll. At low line speeds the current required to overcome losses in the master speed-regulated roll will differ significantly from the current required to overcome losses in the helper rolls, resulting in overall erratic speed regulation in the bridle. A scheme based on cascaded current major loops is described and shown to provide a substantial improvement in low-speed regulation. An additional benefit is that higher speed-loop bandwidths are made possible by the decoupling effect provided by the cascaded current major loop     

Biochemical basis of insect resistance in Vigna unguiculata

The bruchid beetle Callosobruchus maculatus (F.) causes extensive damage to seeds of the cowpea, Vigna unguiculata (L.) (Walp.), when this important tropical foodstuff is stored. A variety of cowpea resistant to attack by this pest has been described. In the present work seeds of a number of cowpea varieties, including the resistant one, were tested for the presence of a physical resistance to C. maculatus, in terms of repulsion of oviposition or of failure of larvae to enter the seeds. No evidence to suggest the presence of a physical resistance was found. When seeds of cowpea varieties were tested for the presence of various antimetabolic secondary compounds, only inhibitory activity against trypsin and, to a much lesser extent, chymotrypsin, could be detected. The resistant variety of cowpea contained a significantly higher level of inhibitors, about twice as much as any other variety. A proteinase inhibitor active against trypsin was purified from cowpea varieties by affinity chromatography on trypsin-Sepharose. The purified inhibitor was shown to inhibit chyraotrypsin also, in such proportions as to account for chymotrypsin inhibition by seed extracts. The inhibitor was shown to consist of a number of isoinhibitors by gel electrophoresis and isoelectric focusing, but no qualitative differences in the inhibitor between varieties could be detected. The antimetabolic nature of the cowpea trypsin inhibitor was confirmed by insect feeding trials in which various protein fractions were added to a basic meal and the effect on larval survival noted. The albumin proteins of cowpea (containing the trypsin inhibitors) at a level of 10% were toxic to larvae of C. maculatus whereas the globulin fractions were not. Further, if cowpea trypsin inhibitor was removed from the albumin proteins they ceased to be toxic. When purified cowpea trypsin inhibitor was added to the basic meal it was shown that a level slightly less than that found in the resistant variety of cowpea caused complete mortality of larvae, whereas lower levels had lesser or no effect. It is concluded that this example of insect resistance in the cowpea is due to an elevated level of trypsin inhibitor.     

Design and Performance of a Pumped Counterflow Virtual Impactor

Counterflow virtual impaction uses a flow of gas in a direction opposite the motion of the particles to separate them from gas and smaller particles. In the past such devices have used aircraft flight or wind tunnel flow to impart momentum to the particles. Here we describe the design and performance of an apparatus, termed a pumped counterflow virtual impactor (PCVI), which uses a vacuum pump to provide the flow. We show that this device is capable of inertial separation with a sub-micrometer cutoff diameter, particle enhancement approaching the ratio of the output to the input flow, and replacement of the ambient gas in the output flow with another gas that may be more suitable for downstream analysis techniques. Rejection of input gas and particles smaller than the cutoff diameter can exceed 99.9%.