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  • 1
    ISSN: 1432-0533
    Keywords: Key words Fas ; Fas ligand ; Rat ; Spinal cord ; Trauma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This immunohistochemical study evaluated Fas and Fas ligand (FasL) in the rat nervous system and their changes in the spinal cord subjected to compression. Normal spinal cord showed a low level of Fas and FasL immunoreactivity in the white matter except in the corticospinal tracts. Fas and FasL immunoreactivity seemed to be located in axons and their myelin sheaths. Other regions of the nervous system did not show immunoreactivity to Fas and FasL. Moderate and severe compression injury of the spinal cord resulted in a reduction of Fas and FasL immunoreactivity in the white matter of injured T8–9 segments at 4 h and a complete loss at 1 day after trauma. This was seen even in the remaining white matter. In contrast, increased immunoreactivity to Fas and FasL was present in the cranial T7, caudal T10 (moderate injury) and T12 (severe injury) segments at day 4 with most intense staining were seen at day 9 after trauma. Increased Fas and FasL immunoreactivity may have pathophysiological implications for the development of secondary injuries after trauma to the spinal cord. Fas-FasL interactions may for instance be involved in apoptosis of oligodendrocytes which occurs as a delayed phenomenon after trauma to the spinal cord. The integrity of myelin sheaths may in this way be jeopardized by apoptosis of oligodendrocytes.
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  • 2
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Background Epidemiological evidence indicates that exposure to ultraviolet (UV) radiation is directly linked to the increase of both incidence and mortality of melanoma. However, the genetic changes caused by UV radiation that lead to melanoma formation remain poorly understood. Recently, a potential tumour suppressor gene ING1 (inhibitor of growth 1) was shown to inhibit cell growth and induce apoptosis in the presence of p53. We have demonstrated that the expression of ING1 is induced after UV irradiation and that ING1 enhances the repair of UV-damaged DNA. Objectives To investigate if ING1 plays a role in melanoma formation. Methods We examined p33ING1 expression levels in 14 melanoma cell lines. Results We found that p33ING1 is overexpressed at both mRNA and protein levels in melanoma cell lines compared with normal melanocytes. Single-strand conformation polymorphism (SSCP) analysis showed band shifting in two melanoma cell lines. DNA sequencing confirmed that there were nucleotide alterations in the ING1 gene in Sk-mel-24 and Sk-mel-110 cell lines. Two silent nucleotide alterations in exon 1a were detected in Sk-mel-110. In Sk-mel-24, the A→G nucleotide alteration at codon 260 resulted in an amino acid change from Asn to Ser, while seven other nucleotide alterations were silent. To determine if the silent nucleotide alterations in these two melanoma cell lines were due to polymorphism, SSCP analysis of ING1 gene was performed in 25 healthy volunteers. No band shift was observed in the SSCP analysis, suggesting that the nucleotide alterations in the melanoma cell lines are unlikely to be due to polymorphism. Conclusions Taken together, our data demonstrate that ING1 is overexpressed, but infrequently mutated, in melanoma cell lines.
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  • 3
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Bullous pemphigoid (BP) is an autoimmune disease mediated by autoantibodies against hemidesmosome components. This study used PCR–sequence-specific primers to genotype polymorphisms in HLA-DR and DQ in 25 BP patients and 57 normal controls from northern China. We found lower frequencies of DRB1*08 (DR8) and DRB1*08/DQB1*06 (DR8/DQ6) haplotypes in BP patients than in controls (4.08% vs. 15.19% and 1.54% vs. 13.82%, respectively; P 〈 0.05), suggesting a protective role for DR8 and DR8/DQ6 haplotypes in BP patients from northern China; there were no statistical differences among other alleles tested. This result is strikingly different from previous reports that DQB1*0301 is associated with BP in Caucasian patients and DRB1*1101, DQB1*0302, DRB1*04/DQA1*0301/DQB1*0302 and DRB1*1101/ DQA1*0505/DQB1*0302 with Japanese BP patients. Ethnic differences in the polymorphic composition of the HLA-DR and DQ genes may influence genetic susceptibility to BP.
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  • 4
    ISSN: 1434-6036
    Keywords: PACS. 75.30.Vn Colossal magnetoresistance – 71.30.+h Metal-insulator transitions and other electronic transitions – 76.30.-v Electron paramagnetic resonance and relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The magnetic transport properties have been measured for La0.67-xYxCa0.33MnO3 ( 0 ⩽ x ⩽ 0.14) system. It was found that the transition temperature T p almost linearly moves to higher temperature as H increases. Electron spin resonance confirms that above T p , there exist ferromagnetic clusters. From the magnetic polaron point of view, the shift of T p vs. H was understood, and it was estimated that the size of the magnetic polaron is of 9.7 ∼ 15.4 Å which is consistent with the magnetic correlation length revealed by the small-angle neutron-scattering technique. The transport properties at temperatures higher than T p conform to the variable-range hopping mechanism.
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  • 5
    ISSN: 1434-6036
    Keywords: PACS. 72.20.Ht High-field and nonlinear effects – 72.60.+g Mixed conductivity and conductivity transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The transport properties of the La1-xCaxMnO3 ( 0.5 ? x 〈 1) system in magnetic fields up to 14 T were studied. We found that the relationship between the charge ordering temperature T CO and Mn4+ content n Mn4 + obeys the formula T CO / T max = 1 - a ( n Mn4 + - n 0 ) 2 , here n0 and a are constants and T max is the maximum of T CO . For x = 0.65, T CO arrives at the maximum value of 249.5 K in zero magnetic field, while the charge ordered (CO) state is most stable around x = 0.75. For x = 0.5 when H 〈 6 T the resistivity displays Mott's variable-range hopping (VRH) behavior, when 6 〈 H 〈 12 T it is suggested that two kinds of conduction mechanism, i.e., VRH and magnetic polarons, coexist in the material, and when H 〉 12 T the resistivity shows metallic-like behavior and the transport mechanism is attributed to coexistence of magnetic polarons and free carriers. For x = 0.95, the conduction mechanism accords with the coexistence of VRH and magnetic polarons.
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  • 6
    ISSN: 1615-6102
    Keywords: Locomotory cytoskeleton ; Ginkgo biloba ; Spermatid ; Flagellar apparatus ; Multilayered structure ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the locomotory cytoskeletal system of sperm is carefully coordinated with the development of the sperm inGinkgo biloba. Here we report further ultrastructural characterization of the locomotory cytoskeletal system in the developing spermatid and mature spermatozoid, particularly with respect to the initiation and early development of the flagellar apparatus. A multilayered structure (MLS) assembles from an electron-dense matrix that self-organizes after blepharoplast breakup and then further elongates. At the tail of the assembling MLS, the spline microtubules connect to an anterior beak of the nuclear envelope. Nuclear-pore complexes are found on the nuclear envelope close to this beak. The mitochondria which elongate and line up one behind the other are tightly associated with the MLS. The MLS ofG. biloba is composed of an upper layer of parallel spline microtubules and a lower layer consisting of a fibrous lamellar strip composed of paralled fibers about 9 nm in diameter. Higher-magnification images show that the fully assembled fibers of the lamellar strip consist of subunits which suggest that protofilaments are involved in the assembly processes. A unique cytoskeletal system of the spermatozoid inG. biloba is given by the anterior bundle of microtubules. This bundle, in which microtubules are arranged parallel to each other, forms between the plasmalemma and the MLS and is about 214–392 nm in cross section. These microtubules expand spirally along the MLS band. Other details of cellular fine structure of the mature spermatozoid are described.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8716-8720 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new physical model for a humidity-sensitive metal–insulator–semiconductor (MIS) capacitor with porous thin film is proposed. The model is used to determine water adsorption isotherm and calculate pore-size distribution of the film. The relative-humidity dependences of the capacitance and resistance of the film were measured. The effects of frequency on the dielectric constant of the film and the current of the MIS structure under various relative humidities were investigated. © 2000 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 408 (2000), S. 50-51 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Here we describe the smallest carbon nanotubes possible, prepared by the pyrolysis of tripropylamine molecules in the channels of porous zeolite AlPO4-5 (AFI) single crystals. These uniformly sized carbon nanotubes have a diameter of 0.4 nm and are the best example of ...
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly ordered TiO2 nanowire (TN) arrays were prepared in anodic alumina membranes (AAMs) by a sol-gel method. The TNs are single crystalline anatase phase with uniform diameters around 60 nm. At room temperature, photoluminescence (PL) measurements of the TN arrays show a visible broadband with three peaks, which are located at about 425, 465, and 525 nm that are attributed to self-trapped excitons, F, and F+ centers, respectively. A model is also presented to explain the PL intensity drop-down of the TN arrays embedded in AAMs: the blue PL band of AAMs arises from the F+ centers on the pore walls, and the TNs first form in the center area of the pores and then extend to the pore walls. © 2001 American Institute of Physics.
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  • 10
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the photoluminescence (PL) of self-assembled In0.55Al0.45As/Al0.5Ga0.5As quantum dots (QDs) grown on (311)A GaAs substrate. The PL peak at 10 K shifts to lower energy by about 30 meV when the excitation power decreases by two orders of magnitude. It has a red-shift under pressure, that is the character of X-like transition. Moreover, its peak energy is smaller than the indirect gap of bulk Al0.5Ga0.5As and In0.55Al0.45As. We then attribute that peak to the type-II transition between electrons in X valley of Al0.5Ga0.5As and heavy holes in In0.55Al0.45As QDs. A new peak appears at the higher energy when temperature is increased above 70 K. It shifts to higher energy with increasing pressure, corresponding to the transition from conduction Γ band to valence band in QDs. The measurements demonstrate that our In0.55Al0.45As/Al0.5Ga0.5As quantum dots are type-II QDs with X-like conduction-band minimum. To interpret the second X-related peak emerged under pressure, we discuss the X-valley split in QDs briefly. © 2000 American Institute of Physics.
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