Zur Bestimmung der Amylaseaktivit?t im Harn

Ohne Zusammenfassung     

Determination of "net carbohydrates" using high-performance anion exchange chromatography

For labeling purposes, the carbohydrate content of foods has traditionally been determined by difference. This value includes sugars, starches, fiber, dextrins, sugar alcohols, polydextrose, and various other organic compounds. In some cases, the current method may lack sufficient specificity, precision, and accuracy. These are subsequently quantitated by high performance anion exchange chromatography with pulsed amperometric detection and expressed as total nonfiber saccharides or percent "net carbohydrates." In this research, a new method was developed to address this need. The method consists of enzyme digestions to convert starches, dextrins, sugars, and polysaccharides to their respective monosaccharide components. These are subsequently quantified by high-performance anion exchange chromatography with pulsed amperometric detector and expressed as total nonfiber saccharides or percent "net carbohydrates." Hydrolyzed end products of various novel fibers and similar carbohydrates have been evaluated to ensure that they do not register as false positives in the new test method. The data generated using the "net carbohydrate" method were, in many cases, significantly different than the values produced using the traditional methodology. The recoveries obtained in a fortified drink matrix ranged from 94.9 to 105%. The coefficient of variation was 3.3%.     

Palladium catalysed aryl amination reactions in supercritical carbon dioxide

Palladium catalysed C-N bond formation in supercritical carbon dioxide has been accomplished. Carbamic acid formation is avoided in part through the use of an N-silylamine as the coupling partner. Employing a catalyst system of Pd2dba3(1 mol%) and 2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl (X-Phos)(2 mol%) enabled the catalytic amination of aryl bromides and chlorides with N-silylanilines to be realised in excellent yield. Extension of the methodology to the N-arylation of N-silyldiarylamines, N-silylazoles and N-silylsulfonamides is reported.     

The impact of the resolution of the identity approximate integral method on modern ab initio algorithm development

The computation of the two-electron four-center integrals over gaussian basis functions is a significant component of the overall work of many ab initio methods used today. Improvements in the computational efficiency of the base algorithms have provided significant impact. Somewhat overlooked are methods that provide approximations to these integrals and their implementation in application software. A partial review of approximate integral techniques focused on the resolution of the identity (RI) four-center, two-electron integral approximation is given. The past and current uses of the RI algorithms are presented along with possibilities for further exploitation of the technology. Received: 14 January 1997 / Accepted: 11 March 1997     

Impact of filter paper on fluorescence measurements of buffered saline filtrates

Fluorescent contaminants have been observed when stock solutions of phosphate buffered saline solutions at each of three pH values (2.2, 7.5, and 12.5) are analyzed after passing through commercially available filter paper. The filtrate's fluorescence was observed to exhibit a maximum signal at 440.0 nm when excited at 365 nm. Detection of trace components could have significant implications in the design and implementation of sample processing protocols when using fluorescence.     

Clinical application of a rapid method using agarose gel electrophoresis and Western blotting to evaluate von Willebrand factor protease activity

A method for evaluating the activity of the von Willebrand factor (vWF) protease is described, and a clinical application is illustrated. The procedure utilizes gel electrophoresis, Western blotting, and luminographic detection methods to evaluate the distribution of vWF multimers before and after incubation of clinical samples under conditions that favor proteolysis by this enzyme. Physiologically, the high-molecular-weight multimers of vWF are cleaved by the vWF protease under conditions of high shear stress in parts of the arterial circulation; cleavage of vWF multimers is also observed after exposure of vWF to denaturing agents in vitro and thus can serve as a laboratory test for the activity of the protease. vWF protease activity is decreased or absent in patients with thrombotic thrombocytopenic purpura due to an inhibiting autoantibody, and this leads to high levels of noncleaved vWF and to life-threatening thrombosis, thrombocytopenia and anemia. The assay evaluates the activity of the protease by assessing the cleavage of vWF multimers after patient plasmas are incubated in vitro under denaturing conditions. With the use of these electrophoresis and Western blotting techniques, patient plasmas can be rapidly assessed for the activity of the vWF protease which may aid in the treatment strategy for these patients.     

Active-site mobility inhibits reductive dehalogenation of 1,1,1-trichloroethane by cytochrome P450cam

Summary Recent studies by Wackett and co-workers have shown that cytochrome P450cam is capable of reductively dehalogenating hexachloroethane at a significant rate, but that no appreciable dehalogenation of 1,1,1-trichloroethane is observed. A growing body of evidence indicates that differences in intrinsic reactivity can not completely explain this observation. We therefore explored the possible role of differences in preferred binding orientation and in active-site mobility. A detailed analysis of molecular dynamics trajectories with each of these substrates bound at the active site of P450cam is presented. While the dynamics and overall time-average structure calculated for the protein are similar in the two trajectories, the two substrates behave quite differently. The smaller substrate, 1,1,1-trichloroethane, is significantly more mobile than hexachloroethane and has a preferred orientation in which the substituted carbon is generally far from the heme iron. In contrast, for hexachloroethane, one of the chlorine atoms is nearly always in van der Waals contact with the heme iron, which should favor the initial electron transfer step.     

IMINIUM SALT BENZOCHLORINS: STRUCTURE-ACTIVITY RELATIONSHIP STUDIES

An iminium salt of copper(II) octaethylbenzochlorin (CDS1) is an effective new photosensitizer despite the fact that it does not produce singlet oxygen, does not fluoresce and the triplet state lifetime can only be less than 20 ns. A number of octaethylbenzochlorin derivatives were synthesized in order to determine the structural component(s) that is(are) responsible for the photodynamic action of these new photosensitizers. Studies utilizing the N -(4-[5-nitro-2-furyl]-2-thiazolyl)formamide-induced urothelial tumor revealed that the coexistence of the copper inside the aromatic ring and the iminium group at the meso position are required for the photodynamic effect.     

Projective degenerations of K3 surfaces,Gaussian maps,and Fano threefolds

Summary In this article we exhibit certain projective degenerations of smoothK3 surfaces of degree 2g–2 in ^g (whose Picard group is generated by the hyperplane class), to a union of two rational normal scrolls, and also to a union of planes. As a consequence we prove that the general hyperplane section of suchK3 surfaces has a corank one Gaussian map, ifg=11 org13. We also prove that the general such hyperplane section lies on a uniqueK3 surface, up to projectivities. Finally we present a new approach to the classification of prime Fano threefolds of index one, which does not rely on the existence of a line.Oblatum 1-II-1993 & 24-V-1993Research supported in part by NSF grant DMS-9104058     

CCR1 antagonists

CCR1 (CC Chemokine receptor 1) is a widely studied G protein-coupled receptor target expressed on multiple types of leukocytes. It is implicated in initiating and exacerbating inflammatory conditions and thus is viewed as a good target for autoimmune and inflammatory therapeutic applications. Numerous CCR1 antagonists have been reported. Although some early CCR1 antagonists lacked the species cross reactivity that made in vivo animal model study difficult, efforts have been made to improve the compound potency in rodents. Recent identification of new and improved CCR1 antagonists has resulted in promising, in vivo efficacy in a variety of animal models of disease. While several early compounds have been withdrawn from clinical trials due to lack of efficacy, work continues to evaluate CCR1 antagonists in preclinical and clinical settings.