Cardiac anisotropy: is it negligible regarding noninvasive activation time imaging?

The aim of this study was to quantify the effect of cardiac anisotropy in the activation-based inverse problem of electrocardiography. Differences of the patterns of simulated body surface potential maps for isotropic and anisotropic conditions were investigated with regard to activation time (AT) imaging of ventricular depolarization. AT maps were estimated by solving the nonlinear inverse ill-posed problem employing spatio-temporal regularization. Four different reference AT maps (sinus rhythm, right-ventricular and septal pacing, accessory pathway) were calculated with a bidomain theory based anisotropic finite-element heart model in combination with a cellular automaton. In this heart model a realistic fiber architecture and conduction system was implemented. Although the anisotropy has some effects on forward solutions, effects on inverse solutions are small indicating that cardiac anisotropy might be negligible for some clinical applications (e.g., imaging of focal events) of our AT imaging approach. The main characteristic events of the AT maps were estimated despite neglected electrical anisotropy in the inverse formulation. The worst correlation coefficient of the estimated AT maps was 0.810 in case of sinus rhythm. However, all characteristic events of the activation pattern were found. The results of this study confirm our clinical validation studies of noninvasive AT imaging in which cardiac anisotropy was neglected.     

Anwendung der Festphasenextraktion zur raschen Probenvorbereitung bei der Bestimmung von Lebensmittelinhaltsstoffen I. Chinin in Getr?nken

Zusammenfassung Zur Bestimmung von Chinin in Trinkbranntweinen und alkoholfreien Erfrischungsgetränken wurde eine Methode für die Routineanalytik erarbeitet. Chinin wurde dabei durch HPLC unter Verwendung der Ionenpaarchromatographie an RP 18 als stationäre Phase von interferierenden Stoffen abgetrennt und mit Hilfe von UV- bzw. Fluorescenzdetektion nachgewiesen. Eine zusätzliche Absicherung der Ergebnisse erfolgte durch Einsatz eines Photodiodenarray-Detektors. Im Gegensatz zur Analyse von alkoholfreien Erfrischungsgetränken war für Trinkbranntweine eine Probenvorbereitung nötig. Hierzu eignete sich die Festphasenextraktion an Phenylsorbens als schnelle, spezifische und einfache Methode.

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Use of solid-phase extraction for rapid sample preparation in the determination of food constituents. I. Quinine in beverages

Summary A routine method was developed for the determination of quinine in spirits and alcohol-free beverages. Using ion pair chromatography quinine was separated from interfering substances by high-performance liquid chromatography on a RP 18 phase and analysed by UV and fluorescence detection. In contrast to the analysis of alcohol-free beverages, sample preparation was necessary in the study of alcoholic beverages. Solid-phase extraction on phenyl sorbens was found to be a rapid, specific and simple technique.

     

Synthese eines Pentapeptidderivates der Insulinsequenz A17-A21

Synthesis of a Pentapeptide Derivative of the Insulin Sequence A₁₇–A₂₁ The synthesis of the protected pentapeptide derivative N-2-(p-biphenylyl) isopropyloxycarbonyl-γ-t-butyl-L -glutamyl-L -asparaginyl-O-t-butyl-L-tyrosyl-S-diphenylmethyl-L -cysteinyl-L-asparagine t-butyl ester is described. Its amino acid sequence corresponds to the sequence 17–21 of the insulin A-chain.     

Optimized implementations of rational approximations—a case study on the Voigt and complex error function

Rational functions are frequently used as efficient yet accurate numerical approximations for real and complex valued special functions. For the complex error function w(x+iy), whose real part is the Voigt function K(x,y), the rational approximation developed by Hui, Armstrong, and Wray [Rapid computation of the Voigt and complex error functions, J. Quant. Spectrosc. Radiat. Transfer 19 (1978) 509-516] is investigated. Various optimizations for the algorithm are discussed. In many applications, where these functions have to be calculated for a large x grid with constant y, an implementation using real arithmetic and factorization of invariant terms is especially efficient.     

Studies on flavonol degradation by peroxidase (donor: H2O2-oxidoreductase,EC 1.11.1.7): Part 2—Quercetin

The peroxidatic transformation of quercetin was studied at pH 5·5 under UV-spectrophotometric control. The reaction products obtained after 3 minutes' incubation of quercetin (dissolved in ethylene glycol monomethyl ether) with peroxidase (Boehringer, Mannheim)/H₂O₂ were fractionated on preparative scale by Sephadex LH-20 liquid chromatography using methanol as solvent. More than twenty compounds could be detected by analytical HPLC, from which the following substances were characterized by their spectroscopic data (UV; IR; ¹H- and, in part, ¹³C-NMR; EI- and, in part, FAB- and FD-MS): 2,4,6-trihydroxybenzoic acid (Q1); 3,4-dihydroxybenzoic acid (Q2); methyl 2,4,6-trihydroxyphenyl-glyoxylate (Q3); 2-(3,4-dihydroxyphenyl)-2-hydro-3,5,7-trihydroxy-3-methoxy-4H-1-benzopyran-4-one (‘quercetinchinone’) (Q5); 2,3-epoxy-2-(3,4-dihydroxyphenyl)-3-[4O-[2-(3-hydroxyphenyl)-3,5,7-]trihydroxy-4H-1-benzopyran-4-onyl]-5,7-dihydroxy-4H-1-benzopyran-4-one (2 isomers) (Q7) and a trimer (Q8) structurally related to Q7.     

Isoxazolylthioamides as potential immunosuppressants a combinatorial chemistry approach

A library of thioamide derivatives of leflunomide 1a and of its bioactive metabolite 1b has been synthesised on solid phase. Thus, para-substituted phenylacetic acids were coupled to TentaGel and were subsequently reacted with aromatic isothiocyanates. Treatment of the resulting enaminothioamides with hydroxylamine led to their simultaneous cyclisation and cleavage from the resin affording 2-25. Their in vitro profiling demonstrated that the amide-thioamide isologous substitution was detrimental of the biological activity.     

Comparison of the phagocytosis of two types of cyclosporin (SDZ OXL 400 and SDZ IMM 125) by alveolar macrophages from hamsters

The aim of this study was to compare two types of cyclosporin (Cs) particles, SDZ OXL 400 and SDZ IMM 125, the latter being more hydrophilic, to understand their uptake by airway macrophages. Alveolar macrophages (AM), harvested by bronchoalveolar lavage (BAL) of hamster lungs, were cultured with two different doses (0.1 mg and 0.5 mg) for 1 h, 6 h, and 24 h. Control incubations without Cs particles or with latex particles were carried out simultaneously. Cell viability, cell activation (i.e., respiratory burst, interleukin-6 (IL-6) synthesis) and mean volume of particles phagocytosed per macrophage were measured. Both types of Cs particles did not modify the AM viability, and failed to induce IL-6 synthesis during phagocytosis but slightly decreased the cell oxidative respiratory burst. The comparison between SDZ OXL 400 and SDZ IMM 125 showed that for the lower dose the mean volume of both Cs types phagocytosed was similar at 1 h and 6 h. At 24 h an increase of the mean volume phagocytosed was seen for SDZ IMM 125 but not for SDZ OXL 400. For the higher dose the mean volume of SDZ IMM 125 phagocytosed was higher than SDZ OXL 400 at 1 h and 6 h and comparable for both types at 24 h. SDZ IMM 125 particles were phagocytosed more rapidly than SDZ OXL 400. The mean volume of phagocytosed latex particles increased with time and dose and was higher than for both Cs particle types. In conclusion, AM were seen to phagocytose particles of different physical properties (i.e., form, size, and shape), chemical properties (i.e., inert or peptidic) and degrees of hydrophilicity in a different manner.