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  • 1
    Electronic Resource
    Electronic Resource
    Microsecond time resolution on a conventional EPR spectrometer using 200-kHz magnetic field modulation and phase-sensitive detection (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 735-741 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method is developed to detect electron paramagnetic resonance (EPR) transient signals with frequency components in the range from dc to 1 MHz and a low initial signal-to-noise ratio (e.g., 0.1 after one sweep). This method uses 200-kHz magnetic field modulation on a conventional EPR spectrometer, using a modified lock-in detector: the tuned amplifier is replaced by a broadband preamplifier with a high-pass filter and the low-pass filter of the lock-in detector is replaced by a broadband amplifier. The transients are generated incoherently from the magnetic field modulation, and subsequently averaged. The function of the (removed) low-pass filter is taken over by the averaging. An instrumental response time of less than 1 μs is obtained. This was determined by measuring the rise time of the triplet state of the photosynthetic reaction center of Rhodopseudomonas sphaeroides R-26 at 165 K. This method, direct detection, and high-frequency (1–2 MHz) modulation are discussed. The S/N ratio of the method described in this paper is similar to that of the other two methods. However, when large linewidths (〉0.5 mT) are met, it gives a superior S/N ratio as compared to high-frequency (1–2 MHz) modulation methods, due to the higher maximum modulation amplitude. When the transients of interest contain frequency components in the low-frequency noise regime (dc–50 kHz), the described method is to be preferred over direct detection because of its better S/N ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139624
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  • 2
    Electronic Resource
    Electronic Resource
    Mixed antibody and T cell responses to peanut and the peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 in an oral sensitization model (2004)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 34 (2004), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Peanut allergy is known for its severity and persistence through life. Several peanut proteins have been identified as allergenic and are indicated as Ara h 1–7. Very little is known about the mechanisms that underlie sensitization to peanut proteins.Objective The purpose of the present study was to reveal the immune responses that are induced against peanut and the peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 during sensitization, including the very early responses.Methods Humoral and T cell responses against peanut and the peanut allergens were examined in an early and later stage of sensitization in an established murine model of peanut anaphylaxis. Therefore C3H/HeJ mice were orally exposed to two different doses of peanut extract plus cholera toxin.Results Oral sensitization to peanut was characterized by an antigen-induced mixed cytokine response in the spleen (IL-4, IL-5, IL-10 and IFN-γ), which could already be observed 7 days after the onset of exposure. Additionally, polyisotypic humoral responses (IgE, IgG1 and IgG2a) against peanut were found in the serum. Moreover, we demonstrated that these T helper (Th)1/Th2 cytokine and antibody responses were also directed specifically against the major peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6.Conclusions This study implicates that both Th1 and Th2 phenomena are involved in the development of peanut allergy in the C3H/HeJ murine model. Furthermore, we show that the present oral model is suitable to examine immune responses to food allergens during different stages of sensitization upon treatment with a whole food extract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.2004.02062.x
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  • 3
    Electronic Resource
    Electronic Resource
    Population Dynamics of CD4+ T Cells Lacking Thy-1 in Murine Retrovirus-Induced Immunodeficiency Syndrome (MAIDS) (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 39 (1994), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Increased numbers of CD4+ Thy-1 cells have been described in the spleen (SP) of mice with retrovirusinduced immunodeliciency (MAIDS). Since this phenotypic abnormality might have considerable functional importance, the expansion of the CD4+ Thy-1 subset in MAIDS was characterized further. CD4+ Thy-1− and Thy-1+ T-cell is from infected mice expressed similar densities of CD3 and TCR γ/β. In contrast, the Thy-I− subset was uniformly CD44hi, even early in the disease when part of Thy-I+ cells were still CD4410. The emergence of CD4+ Thy-1−cells occurred first in SP and lymph nodes and was observed later in thymus. The important fraction ofCD4+ cells lacking Thy-1 normally present in Peyer's patches was only weakly modified. Despite the major expansion of the CD4+ Thy-1− phenotype. the proliferating fraction was not higher in this subset than in CD4+ Thy-1+ cells from infeeted miee. Persistence after hydroxyurea administration was identical in both subsets, indicating similar mean cell lifespans. Taken together, these results show that the major expansion of CD4+ Thy-I− T-cells in MAIDS is not ascribable solely to increased proliferation within this subset. Phenotypic analysis suggests that CD4+ Thy-I− cells result from the differentiation of Thy-I+ cells induced by activation signals related to retroviral infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1994.tb03363.x
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