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51.
Trace analysis of rapamycin in human blood by micellar electrokinetic chromatography 总被引:1,自引:0,他引:1
A capillary electrophoretic method with UV detection at 278 nm has been developed for analysis of the immunosuppressant rapamycin (sirolimus) in human blood at low microgram per liter levels. Separation has been achieved in an acidic carrier electrolyte containing sodium dodecylsulfate and 30% (v/v) acetonitrile. For sample clean-up and preconcentration, an off-line solid-phase extraction step using a silica-based reversed-phase material and an on-capillary focussing technique were employed. The latter allows the injection of increased sample volumes without excessive band broadening. Although this new method is less sensitive than existing liquid chromatographic procedures combined with mass spectrometry, it is fully suited to routine analysis of rapamycin in blood from patients treated with this drug. Last but not least the low costs make it an attractive alternative to established methods. 相似文献
52.
53.
Òscar Rubio-Pons Boris Minaev Oleksandr Loboda Hans Ågren 《Theoretical chemistry accounts》2005,113(1):15-27
The phosphorescence spectrum of p-dichlorobenzene has been calculated using multiconfiguration self-consistent-field wave functions and the quadratic response technique. Attention has been paid to the intensity distribution of the singlet–triplet (3B1u1Ag) transition through a number of vibronic subbands. The second order spin–orbit coupling (SOC) contribution to the spin splitting of the 3B1u (3*) state is found to be almost negligible, and the calculations therefore provide a good estimate for the zero-field splitting (ZFS) parameters based only on the electron spin–spin coupling expectation values. Nuclear quadrupole resonance constants for the different Cl isotopes are also calculated to accomplish the ZFS assignment. The electric dipole activity of the spin sublevels in the triplet–singlet transitions to the ground-state vibrational levels is estimated by calculations of derivatives using distorted geometries which are shifted from the equilibrium position along different vibrational modes. A vibrational analysis of the phosphorescence spectrum, based on the SOC-induced mixing of the singlet and triplet states calculated along different vibrational modes, provides reasonable agreement with experimental data.Acknowledgment O. R.-P. would like to thank the European MOLPROP network for support. The authors thank Alexander Baev for fruitful discussions. This work was supported by the Swedish Royal Academy of Science (KVA). 相似文献
54.
The enzymatic elongation of acyl-CoA esters by malonyl-CoA, respectively de novo synthesis of fatty acids from malonyl-CoA by liver microsomes and non particulate fraction of α-tocopherol deficient rats is diminished versus controls. However, liver microsomes of vitamin E deficient rats synthesize more eicosatetraenic acid from γ-linolenic acid and more γ-linolenic acid from linolic acid than do those of tocopherol supplemented animals. It has often been shown that the liver phosphatides of tocopherol deficient rats contain more arachidonic acid than those of controls, a fact which can be explained now by increased activity of the enzymes involved in the biosynthesis of arachidonic acid. Certain polyenic fatty acids are more rapidly synthesized in the absence of naturally occuring antioxidants. Some enzymes of the respiratory chain have also been examined. No vitamin E deficiency effect has been found on enzymes such as gluconate-6-P-dehydrogenase, isocitrate-dehydrogenase, malate-dehydrogenase and lactate dehydrogenase contained in the non particulate fraction. Sonicated mitochondria of tocopherol deficient rats show a greater activity towards cytochrome, oxydase and β-hydroxy-acetyl-CoA-dehydrogenase than controls, possibly due to ultrastractural alteration of this particle. 相似文献
55.
José Fernández Bertrán Boris La Serna Klaus Doerffel Klaus Dathe Gunther Kabish 《Journal of Molecular Structure》1982
The Fermi doublet V2?V3 + V4 of CH3CN in basic, inert and acidic solvents has been studied by IR and Raman spectroscopy. The values of W, the Fermi coupling coefficient, obtained from IR spectra varies with the nature of the solvent while W evaluated from Raman data remains constant at 12.5 ± 0.5 cm?1. The similar effects of Bronsted and Lewis acids on the band frequencies and intensities is evidence that the CN group complexes with acids via the N atom “n” electron pair and not the π bond. 相似文献
56.
(±)-Muscone (5) has been synthesized from methyl 13-(chloroformyl)tridecanoate (6) in nine steps in an overall yield of 24%. The key steps involve an efficient transformation of the readily accessible 14-hydroxy-15-methyl-15-hexadecenoic acid (9) into the tetradecanolide 1 and a subsequent Ireland-Claisen rearrangement of its triethylsilyl enolate 2 to a 8:1-mixture of the stereoisomeric 15-membered carbocycles 4 and 10 (Scheme 4). 相似文献
57.
Boisguerin P Leben R Ay B Radziwill G Moelling K Dong L Volkmer-Engert R 《Chemistry & biology》2004,11(4):449-459
SPOT synthesis permits parallel synthesis and screening of thousands of cellulose membrane-bound peptides to study protein-protein interactions in a proteomic context. Recognition of C-terminal residues is one of the most common binding features of PDZ domains. Unfortunately, most solid support-bound peptide libraries lack a free C terminus due to C-terminal fixation on the solid support. To overcome this restriction, we developed a robust methodology based on our previous strategy for generating peptides with authentic C termini. To validate this improved method, we screened a human peptide library of 6223 C termini with the syntrophin PDZ domain. Furthermore, using the same library, new peptide ligands derived from membrane proteins and receptors were found for the ERBIN PDZ domain. Finally, we identified the protein kinase breakpoint cluster region, which is known as a negative regulator of cell proliferation and oncogenic transformation, as an ERBIN ligand. 相似文献
58.
Rudolf Wagner 《Fresenius' Journal of Analytical Chemistry》1976,282(4):315-321
Summary Problems, techniques and means of water sampling are reviewed. Applicability and performance are discussed with regard to individual and composite samples, and also to automatic sampling. Storage and preservation of samples are dealt with.
Probenahme und Behandlung von ProbenWasser
Zusammenfassung Probleme, Verfahren und Hilfsmittel bei der Probenahme von Wasser werden behandelt. Ausführung und Anwendbarkeit von Einzel und Mischproben sowie der automatischen Probenahme werden diskutiert, ebenso die Aufbewahrung und Konservierung von Proben.
Start of discussion held at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria. 相似文献
59.
Andreas Hofer Eva Brosche und Rudolf Heidinger 《Fresenius' Journal of Analytical Chemistry》1971,253(2):117-119
Zusammenfassung Eine rasche und selektive Methode zur Bestimmung von wasserlöslichem Bor in Mischdüngern wird beschrieben. Bor wird aus der Probelösung, die etwa 0,1 N an Salzsäure sein soll, durch zweimaliges Schütteln mit 20%iger Lösung von 2-Äthyl-1,3-hexandiol in Methylisobutylketon isoliert. Anschließend wird es mit 0,5 N Natronlauge in die wäßrige Phase zurückgeschüttelt und mit, Azomethin H spektralphotometrisch bei 415 nm bestimmt.
Der Direktion der Österreichischen Stickstoffwerke A.G. danken wir für die Erlaubnis zur Veröffentlichung. 相似文献
Spectrophotometric determination of water-soluble boron in complex fertilizers using azomethine h following a separation by extraction with 2-ethyl-1,3-hexanediol
A rapid and selective method for the determination of water-soluble boron in complex fertilizers is described. Boron is separated from the sample solution, which should be approximately 0.1 N in hydrochloric acid, by shaking twice with 20% solution of 2-ethyl-1,3-hexanediol in hexone. Following this extraction boron is back-extracted into the aqueous phase with 0.5 N sodium hydroxide. It is finally determined spectrophotometrically at 415 nm using azomethine H as reagent.
Der Direktion der Österreichischen Stickstoffwerke A.G. danken wir für die Erlaubnis zur Veröffentlichung. 相似文献
60.
Boris U. Stambuk Mary Ann Franden Arjun Singh Min Zhang 《Applied biochemistry and biotechnology》2003,106(1-3):255-263
The kinetics and regulation of d-xylose uptake were investigated in the efficient pentose fermentor Candida succiphila, and in Kluyveromyces marxianus, which assimilate but do not ferment pentose sugars. Active high-affinity (K
m
∼ 3.8 mM; V
max ∼ 15 nmol/[mg·min]) and putative facilitated diffusion low-affinity (K
m
∼ 140 mM; V
max ∼ 130 nmol/[mg·min]) transport activities were found in C. succiphila grown, respectively, on xylose or glucose. K. marxianus showed facilitated diffusion low-affinity (K
m
∼ 103 mM; V
max ∼ 190 nmol/[mg·min]) transport activity when grown on xylose under microaerobic conditions, and both a low-affinity and an
active high-affinity (K
m
∼ 0.2 mM; V
max ∼ 10 nmol/[mg·min]) transport activity when grown on xylose under fully aerobic conditions. 相似文献