Influence of Cyclodextrins on the Kinetics of Oxidation of Amino Acids and BSA by Hydrazyl Radicals

The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin.     

The microscopic investigation of structures of moving flux lines by neutron and muon techniques

We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, when the flux lines in low T _c type II superconductors are caused to move by a transport current. Using small-angle neutron scattering by the flux line lattice (FLL), we are able to demonstrate directly the alignment by motion of the nearest-neighbor FLL direction. This tends to be parallel to the direction of flux line motion, as had been suspected from two-dimensional simulations. We also see the destruction of the ordered FLL by plastic flow and the bending of flux lines. Another technique that our collaboration has employed is the direct measurement of flux line motion, using the ultra-high-resolution spectroscopy of the neutron spin-echo technique to observe the energy change of neutrons diffracted by moving flux lines. The muon spin rotation (μSR) technique gives the distribution of values of magnetic field within the FLL. We have recently succeeded in performing μSR measurements while the FLL is moving. Such measurements give complementary information about the local speed and orientation of the FLL motion. We conclude by discussing the possible application of this technique to thin film superconductors.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

Determination of peptides and proteins in human urine with capillary electrophoresis-mass spectrometry, a suitable tool for the establishment of new diagnostic markers

The on-line coupling of capillary electrophoresis (CE) with electrospray-time-of-flight mass spectrometry (MS) has been used to obtain patterns of peptides and proteins present in the urine of healthy human individuals. This led to the establishment of a "normal urine polypeptide pattern", consisting of 247 polypeptides, each of which was found in more than 50% of healthy individuals. Applying CE-MS to the analysis of urine of patients with kidney disease revealed differences in polypeptide pattern. Twenty-seven polypeptides were exclusively found in samples of patients. Another 13, present in controls, were missing. These data indicate that CE-MS can be applied as powerful tool in clinical diagnostics.     

Capillary electrophoresis coupled to mass spectrometry to establish polypeptide patterns in dialysis fluids

Combination of capillary electrophoresis with mass spectrometry (CE-MS) allows generation of polypeptide patterns of body fluids. In a single CE-MS (45 min) run more than 600 polypeptides were analyzed in hemodialysis fluids obtained with different membranes (high-flux/low-flux). Larger polypeptides (M(r) > 10 000) were almost exclusively present in high-flux dialysates only, while in low-flux dialysates additional small polypeptides were detected. Comparison to the normal urine pattern yielded a surprisingly low consensus: a number of polypeptides present in urine were missing. We established a fast and sensitive technique, easily applicable to the monitoring of different modalities of dialyzers.     

Theorie des Tragflügelprofils in exponentieller Scherströmung

Übersicht Das zweidimensionale Umströmungsproblem bei nichtgleichförmiger Anströmungsgeschwindigkeit der Form U(y) = ae ^cy +be ^–cy wird für elliptische Profile exakt durch Reihenentwicklungen und für beliebige Profile mäßiger Dicke und Wölbung näherungsweise durch ein Analogon zum Verfahren von Riegels gelöst. Zahlenbeispiele zeigen die Güte der Näherung und den Einfluß des Scherparameters auf die aerodynamisch interessierenden Größen.

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Summary A theory of two-dimensional non-uniform flow U(y) = ae ^cy +be ^–cy past profiles is developed. For elliptical profiles exact solutions by series expansions are given. For profiles with small camber and thickness, an analogue to the Riegels method is derived. Numerical examples show the accuracy of this approximation and the influence of the shear-parameter on the interesting aerodynamic quantities.

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Die vorliegende Arbeit ist eine gekürzte Fassung dreier Berichte [11, 12, 13], die während eines Aufenthalts am MATHEMATICS RESEARCH CENTER, UNITED STATES ARMY, THE UNIVERSITY OF WISCONSIN unter Contract No. DA-11-022-ORD-2059 verfaßt wurden. Ich danke dem Center für die mir gewährte großzügige Unterstützung und Herrn J. Al-Abdulla für die gewissenhafte Programmierung und Durchführung der umfangreichen numerischen Rechnungen.     

Capillary electrophoresis coupled to mass spectrometer for automated and robust polypeptide determination in body fluids for clinical use

We describe the application of capillary electrophoresis (CE) coupled on-line to an electrospray ionization-time of flight-mass spectrometer (ESI-TOF-MS) to the analysis of human urine and serum for the identification of biomarkers for clinical diagnostics. CE-MS led to display > 1000 polypeptides present in complex biological samples within 45-60 min in a single analysis run. To extract the information of the CE-MS spectra in a timely fashion, a software was designed to automatically deconvolute and normalize the spectra. Both urine and serum contain several hundred polypeptides in samples from healthy individuals. Hence, it is possible to establish typical "normal urine" or "normal serum" polypeptide patterns. Samples from patients with different diseases display polypeptide patterns that differ significantly from those obtained from healthy individuals. Examining series of patients with the same disease allowed the establishment of polypeptide patterns typical for specific diseases. This permits the search for marker peptides specific for diseases. The data indicate that a single polypeptide present in all patients with the same disease, but absent in all healthy control individuals does not exist. The combination of several polypeptides found in either urine or serum or both are forming a specific pattern, which is indicative not only for the particular disease, but also for the stage of disease. CE-MS detects many polypeptides in single samples and the application of the software to the search of identical polypeptides excreted in urine allows the unbiased diagnosis based on a pattern and does not rely on single disease markers.