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  • 1
    Keywords: A431 CELLS ; BARRIER FUNCTION ; TYROSINE PHOSPHORYLATION ; EPIDERMAL-GROWTH-FACTOR ; KINASE-ACTIVITY ; CHINESE POPULATION ; QUANTITATIVE PROTEOMICS ; LARGE GENE LISTS ; STRATUM-CORNEUM HYDRATION ; HACAT KERATINOCYTES
    Abstract: Keratinocytes account for 95% of all cells of the epidermis, the stratified squamous epithelium forming the outer layer of the skin, in which a significant number of skin diseases takes root. Immortalized keratinocyte cell lines are often used as research model systems providing standardized, reproducible, and homogenous biological material. Apart from that, primary human keratinocytes are frequently used for medical studies because the skin provides an important route for drug administration and is readily accessible for biopsies. However, comparability of these cell systems is not known. Cell lines may undergo phenotypic shifts and may differ from the in vivo situation in important aspects. Primary cells, on the other hand, may vary in biological functions depending on gender and age of the donor and localization of the biopsy specimen. Here we employed metabolic labeling in combination with quantitative mass spectrometry-based proteomics to assess A431 and HaCaT cell lines for their suitability as model systems. Compared with cell lines, comprehensive profiling of the primary human keratinocyte proteome with respect to gender, age, and skin localization identified an unexpected high proteomic consistency. The data were analyzed by an improved ontology enrichment analysis workflow designed for the study of global proteomics experiments. It enables a quick, comprehensive and unbiased overview of altered biological phenomena and links experimental data to literature. We guide through our workflow, point out its advantages compared with other methods and apply it to visualize differences of cell lines compared with primary human keratinocytes.
    Type of Publication: Journal article published
    PubMed ID: 23722187
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  • 2
    ISSN: 1617-4623
    Keywords: Key words DNA mismatch repair ; MutL homologue (MLH) ; T-DNA insertion ; Microsatellite ; Reverse genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA mismatch repair systems play an essential role in the maintenance of genetic information in living organisms and are also implicated in genetic recombination and genome stability. Using degenerate primers, we have cloned the first plant homologue of the E. coli MutL gene, which we have called AtMLH1 for Arabidopsis thaliana MutL-homologue 1. AtMLH1 is present as a single-copy gene in the Arabidopsis genome and is located on the top arm of chromosome 4. Sequence analysis revealed that the product of this gene shows extensive sequence homology with other eukaryotic MLH1 proteins. As mlh1-deficient lines would be useful for studying the biological function of this gene, several populations that had been mutagenized using T-DNA and transposon insertions were screened to identify such mutants. One line that carries a T-DNA insertion in the promoter region of the AtMLH1 gene was isolated. Surprisingly, although the insertion occurred only ≈80 bp upstream of the putative transcription start site, Northern analyses revealed very low but similar amounts of AtMLH1 transcript in both the wild type and the T-DNA insertion lines. RT-PCR analyses suggest, however, that transcription is initiated further upstream in the insertion line and that the T-DNA may supply this novel initiation site. Finally, no increase in microsatellite instability – a phenotype often associated with mutations in mismatch repair genes – was observed in plants homozygous for this insertion.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3761-3763 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of carrier relaxation on the emission dynamics of a semiconductor microcavity laser is investigated using femtosecond optical excitation. For moderate excitation intensities, the dynamics of the output laser pulse becomes significantly slower when the photon energy of the pump laser is tuned from the quantum well band-gap energy towards higher energies. Theoretical calculations reproduce this trend only if the interaction-induced dephasing of the polarization driven by the pump pulse, the formation, and relaxation of the nonequilibrium carrier distribution as well as the chirp of the excitation pulse are taken into account. Additionally, band-structure effects such as excitation of light holes influence the thermalization dynamics and lead to discontinuities in the general trend. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-2275
    Keywords: Key words. Capillarity, resonance, hydrodynamics, dynamic contact angle, incompressible flow.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract. A liquid column with height H, trapped in a capillary tube of radius R, possesses a mechanical eigenfrequency. The axis of the capillary tube is oriented parallel to the gravitational force, so that the lower meniscus is fixed at the lower end of the tube, if the density $ \rho $ of the liquid is higher than that of the surrounding fluid. Basic assumptions of the linear theory are a pinned contact line, the spherical cap approximation and $ H \gg R $ . The shape of the susceptibility function, the dimensionless ratio of the mean liquid displacement to the driving pressure gradient plotted versus frequency, depends on the parameter $ X_0 = \omega_0/\omega_c $ only, where $ \omega_0 $ denotes the eigenfrequency of the undamped system and $ \omega_c = \eta /(\rho R^2) $ stands for the characteristic frequency with the viscosity $ \eta $ . For $ X_0 〉 \sqrt{24} $ the system is underdamped and resonance occurs, while for $ X_0 〈 \sqrt{24} $ the system is overdamped and resonance cannot be observed. If one interpretes capillary tubes as a model of a porous medium, the present mechanism contributes to the damping of sound waves in porous media saturated by two immiscible fluids, one of them being trapped.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 156-158 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the emission dynamics of two In0.2Ga0.8As/GaAs microcavity lasers after femtosecond optical excitation at 20 K. The pulse widths and the peak delays of λ and a 2λ cavity are compared. Pulses as short as 3.3 ps (9.5 ps) and peak delays as short as 8.2 ps (16.5 ps) are obtained with the 2λ cavity (λ cavity). The pulse widths and peak delays are well described by a model based on a rate equation analysis for carrier and photon densities; in particular, the better high speed characteristics of the 2λ cavity compared to the λ cavity are well reproduced. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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