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  • Articles  (98)
  • Springer  (98)
  • Public Library of Science (PLoS)
  • Chemistry and Pharmacology  (98)
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  • Articles  (98)
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  • 1
    ISSN: 1432-1424
    Keywords: plasma membrane ; lung ; histamine receptors ; 5′ nucleotidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A simple and rapid method of isolating plasma membranes from human peripheral lung tissue is described. The method involves homogenization of tissue in 0.25m sucrose-buffered medium followed by differential and sucrose density gradient centrifugation. Enzymatic and morphological characterization of the plasma membrane fraction revealed minimal contamination by nonplasma membrane fragments. The isolated plasma membranes showed an 18-fold purification of 5′-nucleotidase activity compared to the original homogenate. Electronmicroscopic studies of the plasma membrane fraction revealed the presence of small membrane vesicles having a trilaminar membrane structure. To further examine the purity of the plasma membrane preparation, the binding of the H1 receptor antagonist,3H pyrilamine, to the plasma membrane-enriched fraction was compared to the binding to crude membrane preparations. Both the plasma membrane-enriched fraction and the crude membrane preparation had similar Kd's for the histamine antagonist, but the plasma membrane-enriched fraction had a threefold greater binding capacity, reflecting the relative enrichment of plasma membranes of the preparation. Thus, a method has been developed for the isolation of plasma membranes from human peripheral lung which should provide material for a variety of biochemical and pharmacological studies.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 503-504 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Starting with the high functionalized trisilane SiClMe(SiCl2Me)2 and tetrasilane SiMe(SiCl2Me)3 several octa- and decasilane dendrimers containing directly neighboured branchings were prepared. In these compounds the 29Si NMR chemical shifts of the different silyl groups are shifted towards lower field compared with those of analogous groups in tetra- or hexasilanes. This observation is a helpful tool for the characterization of further dendritic oligomers by 29Si NMR.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 117 (1992), S. 63-70 
    ISSN: 1573-4919
    Keywords: glycogen phosphorylase ; alloxan-diabetes ; cardiomyocytes ; G-protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The basis for the hypersensitive response of glycogen phosphorylase to epinephrine stimulation was investigated in adult rat cardiomyocytes isolated from normal and alloxan-diabetic animals. To assess potential G-protein involvement in the response, normal and diabetic derived myocytes were incubated with either cholera or pertussis toxin prior to hormonal stimulation. Pretreatment of cardiomyocytes with cholera toxin resulted in a potentiated response to epinephrine stimulation whereas pertussis toxin did not affect the activation of this signaling pathway. To determine if the enhanced response of phosphorylase activation resulted from an alteration in adenylate cyclase activation, the cells were challenged with forskolin. After 3 hr in primary culture, diabetic cardiomyocytes exhibited a hypersensitive response to forskolin stimulation relative to normal cells. However, after 24 hr in culture, both normal and diabetic myocytes responded identically to forskolin challenge. The present data suggest that a cholera toxin sensitive G-protein mediates the hypersensitive response of glycogen phosphorylase to catecholamine stimulation in diabetic cardiomyocytes and this response which is present in alloxan-diabetic cells and is induced in vitro in normal cardiomyocytes is primarily due to a defect at a post-receptor site.
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  • 4
    ISSN: 1573-4919
    Keywords: cardiomyocytes ; SV40 large T antigen ; retroviral infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Freshly isolated ventricular myocytes have been used extensively as an adult cardiac model system. Due to their inability to undergo cytokinesisin vitro and their dedifferentiated properties in long-term culture, they can not be used for extended studies. Recent reports tell of the establishment of fetal and neonatal cardiac cell lines and the development of adult cardiomyocytes from transgenic animals. A recent report by Kirshenbaum [1], is the first to demonstrate insertion of genes in to adult ventricular myocytes using viral infection. This paper discusses the infection of primary adult differentiated cardiomyocytes with the SV40 large T antigen and subsequent proliferation under temperature sensitive control. Upon further characterization, the cells could be used as a model to study muscle differentiation and repair as well as adult cardiac cell physiology.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 358 (1997), S. 240-241 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica modified with benzene was investigated by infrared and solid state 13C cross-polarization magic angle spinning nuclear magnetic resonance spectroscopy (13C CP MAS NMR). Whereas infrared spectroscopy did not allow to distinguish between phenyl and polyphenyl groups, this was possible by solid state nuclear magnetic resonance spectroscopy.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 363 (1999), S. 185-188 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 15N solid state NMR without enrichment is rarely used because of the low sensitivity and low natural abundance of this nucleus. As demonstrated on different nitrogen-containing polysilanes and polysilazanes, it can be shown that with the CP/MAS technique spectra can be obtained in good quality and within acceptable measuring time. Three main different nitrogen sites – NSi3, NSi2H and NSiH2– can be observed as well as changes in the intensities of these sites with reaction and tempering conditions. Thus the spectra give valuable additional information for a better understanding of the structures and their changes within the investigated systems.
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  • 7
    ISSN: 1573-904X
    Keywords: gelatin ; crosslinking ; formaldehyde ; dissolution ; near-infrared spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To predict the degree of crosslinking from formaldehyde-stressed hard gelatin capsules (HGCs) using near-infrared spectrophotometry (NIR). Methods. HGCs were exposed to a 150 ppb atmosphere of formaldehyde for 2.25,4.60,9.42, 16.0 and 24.0 hours. The capsules were filled with fresh amoxicillin, placed in a 90° conical reflector cone, and scanned in a NIR spectrophotometer. Principal component regression (PCR) was employed to analyze the spectra of the intact capsules. Dissolution profiles were then obtained for each experimental group. Results. The dissolution of amoxicillin from the capsules at pH 1.2 was found to decrease with increasing time of exposure to the formaldehyde atmosphere. A set of principal components (PCs) was formed by a linear combination of the absorbance values at each wavelength scanned. A good correlation was established (r2 = 0.963) when PC values from the NIR spectra of the HGCs were regressed against percentage of amoxicillin dissolved at 45 minutes, at pH 1.2. Water content of the capsules was found to be the largest determinant in the variation between HGC spectra at each exposure time. Conclusions. NIR spectrophotometry, combined with PCR, was successful at not only predicting dissolution of HGCs exposed to formaldehyde, but also at determining which wavelengths contributed most to spectral variation of these stressed HGCs.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-904X
    Keywords: etintidine ; high-performance liquid chromatography (HPLC) ; solid extraction ; determination of etintidine in plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper describes a new, rapid solid extraction method for the determination of etintidine in plasma. The method employs a semiautomatic sample preparation system. Plasma samples and the internal standard (cimetidine) were applied onto octyl-bonded silica extraction columns. The extraction columns were then subjected to Tris buffer and water wash and were subsequently loaded onto an automatic sample injection system. The contents of the extraction columns were eluted on-line with a mobile phase of acetonitrile:methanol:0.1% ammonium hydroxide (85:10:5, by volume) onto a silica analytical column and detected by UV absorption at 229 nm. The chromatographic condition separates etintidine from some of its metabolites and other endogenous components in plasma. The detection limit for etintidine was 0.02–0.05 µg/ml when 0.2 ml of plasma was used. This method has been used for the determination of plasma etintidine levels in humans and mice after oral administration of etintidine and was found to be suitable for pharmacokinetic/bioavailability studies of etintidine in humans and animals. The method can also be used for the quantitative determination of cimetidine and certain metabolites of etintidine.
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  • 9
    ISSN: 1573-904X
    Keywords: gelatin capsules ; moisture content ; near-infrared spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Reviews of physiology, biochemistry and pharmacology 10 (1910), S. 47-215 
    ISSN: 1617-5786
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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