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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 6-11 
    ISSN: 0935-6304
    Schlagwort(e): Capillary gas chromatography ; Negative ion mass spectrometry ; Plasma ; Estrone ; equilin ; Conjugated estrogens ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A procedure is described for the analysis of the estrogens equilin and estrone in human plasma following oral administration of conjugated estrogen preparations. After enzymatic hydrolysis of the sulfate conjugates, plasma proteins are precipitated with methanol and the estrogens extracted into ethyl acetate. Derivatization with the reagent flophemesylamine converts equilin and estrone into volatile pentafluorophenyldimethylsilyl ethers ideally suited to capillary gas chromatography-negative ion chemical ionization mass spectrometry. Using a 15 meter dimethyl silicone bonded phase fused silica capillary column separation of the estrone and equilin derivatives is achieved within 9 minutes. Selected ion monitoring of the intense negative molecular ions enables levels of 1 ng.ml-1 to be measured with coefficients of variation of 9.3 % and 14.2 % for estrone and equilin respectively. Plasma levels of the compounds are reported in two male volunteers up to 24 hours after dosing with 5 milligrams of Premarin™. (™ Ayerst Laboratories Inc., New York, USA.).
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 2 (1975), S. 304-306 
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The identification of 6-methoxy 8-aminoquinoline as a metabolite of Primaquine, an important antimalarial drug, is described. The metabolite is present in urine, plasma and erythrocytes following drug ingestion. It was identified by mass fragmentography of its 1H and 2H acetate and the acetate produced from authentic material. No evidence of further metabolites was obtained.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Phenacetin, paracetamol and acetanilide can be determined in a plasma or urine sample by the use of deuterium labelled analogues. These are produced by reaction of hexadeuterioacetic anhydride with the appropriate aromatic amine. The -NHCOCD3 group is stable to hydrogen exchange below pH 8. The internal standard is added to the plasma or urine after enzymatic hydrolysis of the paracetamol conjugates and an ethyl acetate extract at pH 5 is evaporated under nitrogen and the residue derivatized with N, O-bis-(trimethylsilyl)-acetamide. An aliquot of this solution is injected into a g.c.m.s. system, and one ion characteristic of the material under study and the ion from the deuterium analogue (3 mass units greater) are monitored using a voltage switching technique. In the case of phenacetin, for example, ions at 251 and 254 are monitored. Calibration curves relating different weight ratios of the hydrogen and deuterium compounds to their respective signals from the gas chromatograph mass spectrometer are used to calculate the amount of a compound in a particular sample. These methods have been developed to study the oxidation of acetanilide to paracetamol and the de-ethylation of phenacetin to paracetamol. Preliminary results from experiments with phenacetin will be discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method has been developed for single ion monitoring of diphenylhydantoin and its major metabolite 5-(p-hydroxyphenyl)-5-phenylhydantoin in plasma. A plasma extract is reacted with N, O-bis(trimethylsilyl)acetamide and single ion recording is carried out using a gas chromatograph mass spectrometer system. The mass value selected, m/e 254, is common to the TMS ethers of diphenylhydantoin and its principal metabolite 5-(p-hydroxyphenyl)-5-phenylhydantoin. The results indicate that one cause of an adverse reaction to diphenylhydantoin could be a reduced ability to hydroxylate the drug. Quantitative methods for the analysis of the drug and its major metabolite have also been developed. Diphenylhydantoin and 5-(p-hydroxyphenyl)-5-phenylhydantoin can be analysed in plasma after addition of deuterium labelled internal standards and conversion to volatile derivatives for mass fragmentographic analysis. Diphenylhydantoin and its internal standard are analysed as the N, N-dimethyl derivative, and the hydroxylated metabolite and its internal standard are converted to a pertrimetylsilyl compound by reaction with N, O-bis-(trimethylsilyl)acetamide.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 16 (1974), S. 1103-1112 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: β-Galactosidase has been purified from an ammonium sulfate precipitate of E. coli strain ML308 by biospecific adsorption on a column of agarose gel substituted with p-aminophenyl-β-D-thiogalactopyranoside. The system described using a 1.8 liter column has a useful processing capacity of 3.8 × 106 units of β-galactosidase per 2 hr cycle. This corresponds to about 5 g of pure enzyme. An electromechanical timing device operates a set of six solenoid valves and carries out a preset program consisting of sample application, washing, and elation operations.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 603-606 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 210-216 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Investigations were carried out using immobilized Chlorella cells to determine the diameter, compressibility, tolerance to phosphate chelation, and ability to retain algal cells during incubation of various alginate beads. These physical bead characteristics were found to be affected by a variety of interactive factors, including multivalent cation type (hardening agent) and cell, cation, and alginate concentration, the latter exhibiting a predominant influence. The susceptibility of alginate beads to phosphate chelation was found to involve a complex interaction of cation type, concentration, and pH of phosphate solution. A scale of response ranging from gel swelling to gel shrinking was observed for a range of conditions. However, stable calcium alginate beads were maintained in incubation media with a pH of 5.5 and a phosphate concentration of 5μM. A preliminary investigation into cell leakage from the beads illustrated the importance of maintaining a stable gel structure and limiting cell growth to reduce leakage.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The aim of this study was to evaluate short-term peripheral nerve regeneration across a 10-mm gap, using a biodegradable poly(DL,-lactide-ε-caprolacton) nerve guide, with an internal diameter of 1.5 mm and a wall thickness of 0.30 mm. To do so, we evaluated regenerating nerves using light microscopy, transmission electron microscopy and morphometric analysis after implantation of 12-mm nerve guides in the sciatic nerve of the rat. Evaluation times ranged from 3-10 weeks. Three weeks after reconstruction, myelinated nerve fibers could be observed in the distal nerve stump. Ten weeks after reconstruction, the regenerating nerves already resembled normal nerves. In conclusion, we show that poly(DL,-lactide-ε-caprolacton) nerve guides can be successfully applied in the reconstruction of severed nerves in the rat model. Furthermore, we have observed the fastest nerve regeneration described thus far, after reconstruction using a biodegradable nerve guide. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 757-766 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: One of the ways to reconstruct a nerve defect is to use a biodegradable nerve guide. The aim of this study was to establish a nerve guide constructed of an amorphous copolymer of lactic acid-caprolactone. A pilot study was set up to elucidate the effect of the tube dimensions on nerve regeneration. Four types of nerve guides, with internal diameters ranging from 1.12-1.23 mm and wall thicknesses ranging from 0.34-0.68, were tested for this purpose. We evaluated the biodegradation, foreign body reaction and nerve regeneration by light microscopy, after three different implantation times (1, 2, and 3 months). After 2 months, we observed that all types of nerve guides had changed from a transparent to an opaque and swollen state, and that they had lost their strength. The foreign body reaction was characterized by the presence of giant cells and fibroblasts surrounding the degrading nerve guide. From this pilot study, we conclude that nerve guide type 1, with an internal diameter of 1.23 mm and a wall thickness of 0.34 mm, can ensure nerve regeneration in the case of a 1-cm gap in the sciatic nerve of the rat. Nerve guides types 3 and 4, with relatively small lumens, show nerve compression due to a more pronounced swelling of the degrading tube. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    ISSN: 0021-9304
    Schlagwort(e): poly(DL-lactide-ε-caprolactone) ; degradation ; foreign body reaction ; subcutaneous implant ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The aim of this study was to evaluate the degradation and foreign-body reaction of poly(DL-lactide-ε-caprolactone) (PLA85CL50) bars. This specific biomaterial is used for the construction of nerve guides, which can be used in the reconstruction of short nerve gaps. Subcutaneously implanted PLA85CL50 bars were harvested after implantation periods ranging from 3 to 12 months and evaluated for the rate of degradation and the degree of foreign-body reaction. It was observed that this copolymer degraded completely within 12 months and that no lactide or ε-caprolactone crystals were formed. Furthermore, we conclude that the foreign-body reaction of PLA85CL50 is very mild. These properties make the amorphous copolymer of DL-lactide and ε-caprolactone (50:50) suitable for the construction of nerve guides. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 337-346, 1997.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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