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  • 2000-2004  (6)
  • 1985-1989  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Telomerase and cell senescence: modulation by telomerase of cellular responses to damage in normal human primary skin keratinocytes and fibroblasts (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: Telomeres protect the ends of chromosomes, which contain the DNA that comprises the genetic information. Without telomeres and their special way of replicating, chromosome ends dwindle away and also are easily damaged. Loss of telomere function promotes cancer and may occur in human aging. Most enzymes – the catalysts that carry out life's chemical reactions – are made of protein. In contrast, the enzyme telomerase, which replenishes the DNA at telomeres and protects them, is a ribonucleoprotein complex consisting of core components – a protein reverse transcriptase and the telomerase RNA moiety – as well as additional protein factors that regulate the action of telomerase on telomeres.A major known function of telomerase is to elongate telomeric DNA. This function is achieved by the enzyme copying a short template sequence within the inbuilt telomerase RNA, into telomeric DNA repeat sequences. The mechanism of telomerase has been analyzed and telomerase has been shown to be a dimeric enzyme. Functional dimerization of human telomerase requires a novel RNA–RNA interaction between two telomerase RNA molecules in the same enzyme complex. Telomeric repeats are added to the end of the chromosomal DNA by telomerase, elongating the chromosome and thus compensating for losses of terminal DNA that occur upon nuclease action and incomplete DNA replication of the ends of the chromosomal DNA.However, telomerase is largely repressed in proliferating cultured human fibroblasts or after a few passages of culturing of primary human keratinocytes. The normal senescence of such fibroblasts and other human cell types in culture can be overcome by forced expression of telomerase in these cells. The lifespan of the cells is extended and they grow healthily, generally without evidence of impairment to DNA checkpoint pathways.We analyzed the effects of forced expression of telomerase on the growth characteristics and sensitivity to ultraviolet (UV) irradiation of primary human cells in culture. Normal primary human foreskin epithelial keratinocytes and fibroblasts were stably infected with retroviral vector expressing various versions of hTERT (the reverse transcriptase protein component of telomerase), or the control empty retroviral vector pBABEpuro. Cells selected for the puromycin drug resistance marker were continuously passaged in puromycin-containing media, and their telomeres, cell growth and cell viability analyzed. The responses of such cells expressing telomerase to different challenges, including UV exposure were analyzed and found to differ from those of control cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-2494.2004.213_2.x
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  • 2
    Electronic Resource
    Electronic Resource
    Tribocharging phenomena in hard disk amorphous carbon coatings with and without perfluoropolyether lubricants (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3993-3998 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scanning polarization force microscopy was used to study changes in surface potential (tribocharging) caused by the contact between a tungsten carbide tip and the amorphous carbon coating of a hard disk, both when bare and when covered with Zdol-TX lubricant. The surface potential change produced by tip contact decays with time at a rate that is strongly dependent on lubricant coverage and on the presence of oxygen and water vapor in the environment. Two different charging mechanisms are proposed. One involves chemical modification of the surface by removal of oxygen bound to the surface. This gives rise to a potential change that decays with time. Another mechanism involves trapping of charge in states within the energy gap of the insulating carbon film. The potential change due to this trapped charge does not decay over periods much greater than 1 h. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1351001
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  • 3
    Electronic Resource
    Electronic Resource
    Flexible, real-time, data-collection and analysis system and its utilization in a basic plasma physics experiment (invited) (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1851-1855 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A CAMAC-based LSI microcomputer coupled to a VAX minicomputer with a high (200 kbyte/s) transfer rate network make possible real-time data processing and control of a data-intensive plasma physics experiment. The system is constructed out of reliable, commercially available components. Most of the network software is written in fortran and is easy to maintain and modify. A description of its four software layers and illustrations of the type of experiments it has been used on are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139152
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  • 4
    Electronic Resource
    Electronic Resource
    Raman spectroscopic investigation of superconducting YBa2Cu3O7−x, semiconducting YBa2Cu3O6+x, and possible impurity phases (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 242-243 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Raman spectroscopic investigation of specimens of superconducting YBa2Cu3O7−x and of the possible impurity phases YBa2Cu3O6+x (semiconductor), Y2BaCuO5, Y2Cu2O5, BaCuO2, CuO, Y2O3, and BaCO3 indicates that in the range 100–700 cm−1, there are six characteristic lines belonging to the superconductor. At 13 K, these lines are at 150, 338, 441, 507, 590, and 644 cm−1. Comparison of the Raman spectra of the superconductor and the semiconductor indicates a mode stiffening of the pair at 338 and 441 cm−1, but a mode softening of the pair at 507 and 590 cm−1. A factor group analysis leads to a tentative assignment of the Raman and infrared allowed modes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99651
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  • 5
    Electronic Resource
    Electronic Resource
    A novel mutation of keratin 9 in a large Chinese family with epidermolytic palmoplantar keratoderma (2004)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 150 (2004), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant inherited skin disorder characterized by diffuse yellow thickening of the skin of the palms and soles, sharply bordered with erythematous margins. Histologically and ultrastructurally, EPPK presents cytolysis of keratinocytes and abnormal aggregation of tonofilaments in the suprabasal layers of the epidermis. To date, 15 different mutations of the keratin 9 gene (KRT9) have been demonstrated to cause most cases of EPPK.Objectives  To identify the KRT9 mutation in a large Chinese family with EPPK.Methods  Denaturing high-performance liquid chromatography (DHPLC), DNA sequencing and allele-specific polymerase chain reaction (AS-PCR) were used to screen exon 1 of the KRT9 gene for sequence variations.Results  The DHPLC elution profiles of the DNA fragments amplified from the affected samples differed from those obtained from unaffected individuals, indicating that a sequence variation existed within the analysed fragment of KRT9. DNA sequencing revealed a novel insertion–deletion mutation in the exon 1 of KRT9, 497delAinsGGCT, resulting in the change of tyrosine166 to tryptophan and leucine (Y166delinsWL). AS-PCR confirmed the mutation was not a common polymorphism.Conclusions  The results suggest the molecular basis of EPPK in this Chinese family and provide further evidence that mutations in the helix initiation motif of keratin 9 underlie Chinese EPPK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0007-0963.2004.05865.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of smoking and periodontal treatment on the subgingival microflora (2003)
    Oxford, UK : Munksgaard International Publishers
    Journal of clinical periodontology 30 (2003), S. 0 
    Details
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The effect of smoking on the prevalence of periodontal pathogens after periodontal treatment is still not clear. Some studies found no effect of the smoking status on the prevalence of periodontal pathogens after therapy, whereas others did. The aim of this retrospective study was to investigate the influence of smoking on the treatment of periodontitis and the composition of the subgingival microflora.Method: The study included 59 periodontitis patients (mean age 41.5 years): 30 smokers and 29 nonsmokers. The treatment consisted of initial periodontal therapy and, if necessary, surgery and/or antibiotics. Clinical and microbiological data were obtained before and after treatment at the deepest site in each quadrant. A pooled sample was analysed for the presence of Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotalla intermedia (Pi), Bacteroides forsythus (Bf), Fusobacterium nucleatum (Fn) and Peptostreptococcus micros (Pm).Results: For smokers and nonsmokers a significant improvement of the clinical condition was found after treatment. A decrease could be assessed for bleeding on probing (smokers: 0.46; nonsmokers: 0.52) and probing pocket depth (PPD) (smokers: 1.64 mm; nonsmokers: 2.09 mm). Furthermore, both groups showed gain of attachment (smokers: 0.68 mm; nonsmokers: 1.46 mm). No significant difference in bleeding on probing and PPD reduction was found between smokers and nonsmokers. In contrast, nonsmokers showed significantly more gain of attachment than smokers. The microbiological results revealed no differences in the prevalence of the various bacteria between smokers and nonsmokers before treatment. After treatment in nonsmokers, a significant decrease was found in the prevalence of Aa (11–3), Pg (17–7), Pi (27–11), Bf (27–11), Fn (28–20) and Pm (27–17). In smokers, a significant decrease could be shown only for the prevalence of Pg (15–5).Conclusions: Nonsmokers showed more gain of attachment and a greater decrease in the prevalence of periodontal bacteria as compared to smokers. The phenomenon that among smokers, more patients remain culture positive for periodontal pathogens after therapy, may contribute to the often observed unfavourable treatment results in smoker periodontitis patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-051X.2003.00080.x
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  • 7
    Electronic Resource
    Electronic Resource
    A spontaneously arising porcine model of bullous pemphigoid (2000)
    Springer
    Archives of dermatological research 292 (2000), S. 37-45 
    Details
    ISSN: 1432-069X
    Keywords: Key words Basement membrane zone ; Bullous ¶pemphigoid ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bullous pemphigoid (BP) is an IgG-mediated autoimmune blistering disease targeting the hemidesmosomal proteins bullous pemphigoid antigens 1 and 2. Currently, there is no active animal model in which to dissect the immunopathogenic mechanism. We noticed that cutaneous blistering arose spontaneously in 12 adult Yucatan minipigs. Skin lesions consisted of turgid, isolated or clustered vesicles that occasionally evolved from erythematous and pruritic patches. Histopathological examination revealed subepidermal vesicles rich in intact and degranulated eosinophils. Antigen mapping and transmission electron microscopy confirmed that dermoepidermal separation took place in the lamina lucida of the epidermal basement membrane zone. Direct immunofluorescence revealed the presence of IgG deposited linearly at the dermoepidermal junction in seven of nine skin specimens examined. Indirect immunofluorescence testing confirmed the presence, in the serum from eight of eight affected pigs, of circulating basement membrane-specific IgG autoantibodies (titers 1 : 50 to 1 : 250). Using uncleaved and salt-split lip substrates, the autoantibodies were shown to target antigens situated not only at the basal, but also at the lateral and apical aspects of stratum basale keratinocytes. Immunoelectron microscopy confirmed that circulating IgG autoantibodies recognized hemidesmosomal antigen(s). ELISA, immunoblotting and immunoadsorption demonstrated that five of eight serum samples exhibited high immunoreactivity against BPAG2-NC16A peptides. This novel porcine acquired blistering dermatosis could be proposed as a valuable model to conduct immunomechanistic studies on the natural progression of BP, correlation of autoreactive T cells or autoantibodies with disease activity, and the role of eosinophils in the blistering process, as these diseases cannot be modeled easily in human patients or in murine passive transfer models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007459
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  • 8
    Electronic Resource
    Electronic Resource
    Spin Gap Characteristic of Y(Ba1−xGdx)2Cu3O7−δ (2000)
    Springer
    Journal of superconductivity 13 (2000), S. 393-400 
    Details
    ISSN: 1572-9605
    Keywords: spin gap ; ion size ; magnetic doping ; resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Y(Ba1−x Gd x )2Cu3O7−δ compounds with x = 0 ∼ 0.15 are prepared using the solid reaction technique. With structure analysis by Rietveld refinement of x-ray diffraction, we find that Gd3+ ions prefer to occupy Y sites within lighter doping x ≤ 0.08 due to ion size effects, then begin partially to occupy Ba sites with doping content increasing, which gives vital influence on superconductivity and spin-gap properties. The magnetic doping effects of Gd3+ ions on spin-gap properties are investigated in detail by contrast of the distinguished behaviors between T* and T c, indicating that spin-gap temperature is not completely determined by the carrier density, but strongly dependent on the strength of interplane antiferromagnetic coupling. Finally, we propose an expression of in-plane resistivity dependent on the maximal width of spin-gap Δ0 to derive their values for different samples, which almost keep constant with the increase of Gd doping contents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007746824022
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