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  • 1995-1999  (3)
  • Analytical Chemistry and Spectroscopy  (2)
  • Cell & Developmental Biology
  • 1
    Electronic Resource
    Electronic Resource
    Application of the fast-evaporation sample preparation method for improving quantification of angiotensin II by matrix-assisted laser desorption/ionization (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1164-1171 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The fast-evaporation method of sample preparation has been applied for quantitative analysis using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. An instrumental protocol focusing on improvement of shot-to-shot repeatability and compensation for signal degradation has been developed for quantification of angiotensin II using the fast-evaporation technique and an internal standard. The fast-evaporation method was compared to the standard method of sample preparation (using a multicomponent matrix) in the quantitative analysis of angiotensin II, and found to be superior in several respects. Improvement in sample homogeneity using the fast-evaporation method enhanced both point-to-point repeatibility and sample-to-sample reproducibility. The relative standard deviations of the analyte/internal standard ratios (point RSD) were decreased by a factor of three compared to those obtained using the multicomponent matrix method. The average point RSD was found to be ca. 5% for the fast-evaporation technique. Two internal standards were evaluated for quantification of angiotensin II. The better one, 1-SAR-8-Ile angiotensin II, yielded a relative standard deviation of the standard curve slope of ca. 2.2% over two orders of magnitude of concentration (45 nM to 3000 nM), an improvement by a factor of two over the standard preparation method. Renal microdialysate samples, spiked with angiotensin II and the internal standard 1-SAR-8-Ile angiotensin II, were also analyzed using the fast-evaporation technique. The detection limit was calculated to be in the high attomole range (675amol). Furthermore, the accuracy for a single determination of angiotensin II concentration in these samples was found to be 13.9% with a relative error of 8.19%.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091216
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Keratinocyte growth arrest is associated with activation of a transcriptional repressor element in the human cdk1 promoter (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 177 (1998), S. 474-482 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this study we examined the regulation of cdk1 expression in normal human epidermal keratinocytes (HEKs) and neoplastic keratinocytes. Keratinocytes were growth-arrested by allowing the cells to grow to confluence or by treating them with interferon-gamma (IFNγ) or 12-O-tetradecanoyl phorbol-13-acetate (TPA). RT-PCR and Western blot analysis demonstrated that cdk1 was profoundly reduced in growth-arrested HEKs when compared with dividing HEKs. In contrast, a squamous carcinoma cell line, SCC25, did not growth-arrest in response to growth inhibitors and did not downregulate cdk1 expression. Transfection of HEKs with a reporter gene driven off a 2.5-kb fragment of the human cdk1 promoter indicated that the downregulation of cdk1 upon growth arrest was transcriptional. Deletion mapping of the cdk1 promoter indicated that a repressor region was located between -949--722 bp. This repressor region was not operative in the SCC25 cells. Examination of DNA:protein binding complexes by gel-shift analysis indicated that nuclear factors from both proliferative and growth-arrested cells bound to the DNA fragment spanning -949--722 bp. Further analysis revealed that this binding could be resolved into a constitutive and growth arrest-specific complex that bound in a similar fashion to regions spanning -892--831 bp and -831--774 bp, respectively. The putative growth arrest-specific complex was not found in contact-inhibited fibroblasts and was found at very low levels in SCC25 cells, indicating that the putative repressor binding was growth arrest-specific and possibly keratinocyte-specific. The binding complexes bound to these two fragments were localized, by competition analysis, to regions -874--853 bp and -830--800 bp. This is the first report of a transcriptional repressor being operative during keratinocyte growth arrest. J. Cell. Physiol. 177:474-482, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    One- and two-dimensional NMR study of resol phenol - formaldehyde prepolymer resins (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 717-723 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 1H NMR ; 13C NMR ; Phenol - formaldehyde resins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A one- and two-dimensional NMR study was performed on three commercial resol phenol - formaldehyde (PF) prepolymer resins. 1H, 13C, CSCM and DQF COSY NMR spectral data, in acetone-d6, were obtained on each resin and on PF model compounds: phenol, five methylolphenols, four diphenylmethanes, two formals, two dibenzyl ethers and two dibenzylamines. Gated-decoupled 13C experiments, using 2,4,6-trimethylphenol as internal standard, were used to quantitate the major components present in each of the three resins. The major chemical differences of the three resins were noted. A DQF COSY method was developed that allowed the qualitative identification of most of the major phenolic components present in each of the PF resins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330905
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    Paper (German National Licenses)
    Fulltext
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