Purification of monoclonal antibodies from ascitic fluid using preparative electrophoresis

Anthranilic acid (AA) has attracted considerable attention as one of the L-tryptophan-kynurenine pathway metabolites in the central nervous system. In this study, a highly sensitive and accurate method for the quantification of AA has been developed using reversed-phase high-performance liquid chromatography with electrochemical detection. Serum and cerebrospinal fluid (CSF) AA concentrations in different animal species were measured. CSF AA concentrations in rabbits were 1.1 +/- 0.1 nmol/liter, which were 5. 7-33.0 times lower than those in other species studied. Serum AA concentrations, however, were slightly higher in rabbits than in other species. In contrast, the concentrations of L-kynurenine (L-KYN) in both serum and CSF were substantially higher in rabbits than in other species. Tissue kynurenine pathway enzymes, indoleamine 2,3-dioxygenase (IDO), tryptophan 2,3-dioxygenase, kynurenine 3-hydroxylase, and kynureninase were determined in rabbits, rats, gerbils, and mice. These enzymes varied among species, especially lung IDO activities in rabbits were 146-516 times higher than those found in other species, but rabbit liver kynurenine 3-hydroxylase activities were lower by one order of magnitude than those of the other species tested. Furthermore, brain kynurenine 3-hydroxylasae activities were 12.3-23.2 times higher in gerbils than those in the other species tested. In addition, AA concentrations in serum following intravenous administration of L-KYN (5 mg/kg) were also measured in rabbits. AA levels peaked sharply within 5 min after administration and decreased in a time-dependent manner. At 5 min after administration, CSF L-KYN and AA concentrations were also increased by 1.76- and 2.56-fold, respectively, compared with basal levels. Increased AA concentrations in CSF following L-KYN administration may reflect the entry of AA into the CSF after conversion to AA in systemic tissue and/or the local synthesis of AA from L-KYN in the CNS.     

Influence of Turbulators in Blade Cooling Passages on Film Hole Discharge Coefficients

This paper details the results of a joint project between Rolls-Royce Deutschland (RRD) and the Northwestern Polytechnical University of China (NWPU). The objective of the project was the determination of the influence of tabulators in turbine blade cooling passages on film hole discharge coefficients (Cd coefficients). A large-scale plexiglas model was used by the NWPU to measure the turbulator influence on Cd coefficients for a wide range of different geometrical parameters, Reynolds numbers and cooling flow off take ratios. RRD specified the comprehensive test matrix and analysed the test data. The CFD code FLUENT was used by RRD for numerical simulation of the test cases with the main objective to support the interpretation of observed trends. Both, experimental and numerical results will be presented in this paper for a selection of test configurations.     

Earthworm gene as indicator of bioefficacious cadmium

The expression of a novel Cd-inducible gene encoding a 25 kDa non-metallothionein cysteine-rich protein (CRP) in the earthworm Enchytraeus buchholzi is investigated with respect to Cd-specificity and Cd-sensitivity. The amount of CRP-mRNA correlates with the environmental as well as with the intra-worm Cd-concentration. Even the subtoxic concentration of 100 microgram Cd/1 induces CRP-gene expression. CRP-mRNA is expressed already 2 h after the worms were exposed to Cd. Other heavy metals or stress conditions can induce only little or even no CRP-mRNA. The CRP-gene is switched on long before Cd becomes toxic to worms and can be therefore taken as a warning signal of prospective irreversible Cd-damages at an early, still reversible stage.     

Design of a high-sensitivity classifier based on a genetic algorithm: application to computer-aided diagnosis

A genetic algorithm (GA) based feature selection method was developed for the design of high-sensitivity classifiers, which were tailored to yield high sensitivity with high specificity. The fitness function of the GA was based on the receiver operating characteristic (ROC) partial area index, which is defined as the average specificity above a given sensitivity threshold. The designed GA evolved towards the selection of feature combinations which yielded high specificity in the high-sensitivity region of the ROC curve, regardless of the performance at low sensitivity. This is a desirable quality of a classifier used for breast lesion characterization, since the focus in breast lesion characterization is to diagnose correctly as many benign lesions as possible without missing malignancies. The high-sensitivity classifier, formulated as the Fisher's linear discriminant using GA-selected feature variables, was employed to classify 255 biopsy-proven mammographic masses as malignant or benign. The mammograms were digitized at a pixel size of 0.1 mm x 0.1 mm, and regions of interest (ROIs) containing the biopsied masses were extracted by an experienced radiologist. A recently developed image transformation technique, referred to as the rubber-band straightening transform, was applied to the ROIs. Texture features extracted from the spatial grey-level dependence and run-length statistics matrices of the transformed ROIs were used to distinguish malignant and benign masses. The classification accuracy of the high-sensitivity classifier was compared with that of linear discriminant analysis with stepwise feature selection (LDAsfs). With proper GA training, the ROC partial area of the high-sensitivity classifier above a true-positive fraction of 0.95 was significantly larger than that of LDAsfs, although the latter provided a higher total area (Az) under the ROC curve. By setting an appropriate decision threshold, the high-sensitivity classifier and LDAsfs correctly identified 61% and 34% of the benign masses respectively without missing any malignant masses. Our results show that the choice of the feature selection technique is important in computer-aided diagnosis, and that the GA may be a useful tool for designing classifiers for lesion characterization.     

A solenoidal spectrometer for reactions in inverse kinematics

A new type of spectrometer for the study of reactions in inverse kinematics is proposed, in which the target and detector are placed inside a uniform magnetic field. This device has significant advantages over more conventional approaches to measurements of key reactions, and should prove useful in the study of short-lived nuclei. The technique is directly applicable to existing research programs at present accelerators with secondary beams, and the technique is likely to be important at future radioactive beam facilities.