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  • 1
    Electronic Resource
    Electronic Resource
    Improving cellular function through modulation of energy metabolism (2004)
    Oxford, UK : Blackwell Science Ltd
    International journal of cosmetic science 26 (2004), S. 0 
    Details
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The ambivalent consequences of mitochondrial stimulation on cellular activity have been well established. Mitochondria supply the cell with energy through a process of oxidative phosphorylation but thereby generate free radicals, resulting in the accumulation of hydrogen peroxide in the cytoplasm. We have investigated the impact of cellular senescence as well as UV irradiation, on the balance between these two activities.The adenosine triphosphate (ATP) level, DNA and protein synthesis in fibroblasts obtained from donors between 30 and 90 years of age appeared to be significantly influenced by the aging process. Both DNA and protein synthesis could be stimulated by increasing intracellular ATP levels. In-vitro senescent fibroblasts showed a reduction in the level of ATP as well as a shift in mitochondrial membrane potential. At the same time, there was an increase in intracellular hydrogen peroxide with increasing population doubling, indicating a clear dysfunction of the metabolic machinery in the mitochondria of senescent cells. To counteract this degradation of the energy pool, we treated cells with creatine, which is known to restore the pool of phosphocreatine in the mitochondria. Creatine treatment significantly increased cell survival after UV exposure, stimulated the repair of UVB-induced DNA damage in keratinocytes and caused a significant reduction in the number of sunburn cells in a UVB-exposed reconstituted skin model. These results clearly indicate that restoration of the energy pool in mitochondria increased cellular self-defense mechanism. These data show the important role played by the mitochondrial energy metabolism on the aging process, and indicate a possible therapy that can be used to counteract this negative effect. Treatment with creatine seems to provide the necessary boost to the cellular metabolism, which leads to an induction of a significant amount of protection and repair to human skin cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-2494.2004.00230_4.x
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  • 2
    Electronic Resource
    Electronic Resource
    STEM studies of biological structure
    Amsterdam : Elsevier
    Ultramicroscopy 8 (1982), S. 207-218 
    Details
    ISSN: 0304-3991
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0304-3991(82)90289-3
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  • 3
    Electronic Resource
    Electronic Resource
    Protection against cigarette smoke-induced damage to intact transformed rabbit corneal cells by N-acetyl-L-cysteine (1998)
    Springer
    Cell biology and toxicology 14 (1998), S. 253-259 
    Details
    ISSN: 1573-6822
    Keywords: N-acetyl-L-cysteine ; cells ; cigarette ; protection ; smoke
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In order to assess cigarette smoke-induced oxidative damage to intact cells, an assay was developed to measure cell detachment and protection. Due to the complex nature of cigarette smoke, which contains molecules that can interfere with conventional spectrophotometric and fluorometric biochemical assays, transformed rabbit corneal cells were radiolabeled with tritiated thymidine and then subjected to direct stream smoke. As a result, cell damage in response to the smoke from only two cigarettes could be measured in a time-dependent manner. When cells were prelabeled with N-acetyl-L-cysteine (NAC), a substrate for glutathione synthesis, a significant reduction in damage was measured. Additionally, when buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, was incubated with cells, a reduction in the effectiveness of NAC was observed, although NAC still retained some activity. Furthermore, vitamin E conferred no protection to cells in this system nor was NAC active in a separate assay that appears to favor peroxyl radical generation. From these results we conclude that cigarette smoke damage can easily be determined at the cellular level with this technique and that NAC acted to prevent this damage in two ways: first, as glutathione precursor and, secondly, as an antioxidant capable of scavenging non-peroxyl radicals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007478823798
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  • 4
    Electronic Resource
    Electronic Resource
    Successful separation of apoptosis and necrosis pathways in HaCaT keratinocyte cells induced by UVB irradiation (2000)
    Springer
    Cell biology and toxicology 16 (2000), S. 293-302 
    Details
    ISSN: 1573-6822
    Keywords: apoptosis ; differentiation ; keratinocytes ; UVB radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract UVB irradiation can induce apoptotic, necrotic, and differentiation pathways in normal human keratinocytes. The present study was undertaken to determine at what dose of UVB each of these pathways is induced and whether these pathways are distinct or overlapping. We have observed that UVB induces fragmentation of DNA in human HaCaT keratinocytes, in a bimodal manner. Low doses of UVB, 5–20 mJ/cm2, increase the levels of apoptosis as shown by increased levels of fragmented DNA, Fas, PARP, and FasL protein, and the number of apoptotic cells as assessed by FACS analysis. At higher doses of UVB (20 and 30 mJ/cm2) the number of apoptotic cells becomes reduced, as does the amount of Fas, PARP, and FasL protein. At these higher doses, cell viability is decreased as measured by DNA synthesis (BrdU labeling) neutral red uptake, which represents an increasing necrotic phenotype. Expression of markers of keratinocyte differentiation, involucrin, keratin K1, and keratin K10, are also observed to decrease with increasing UVB dose. These changes are accompanied by a further increase in DNA fragmentation. We conclude that low doses of UVB (5–20 mJ/cm2) induced an apoptotic pathway, whereas increasing doses (greater than 20 mJ/cm2) of UVB produce a direct necrotic effect and inhibit terminal differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026746330146
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