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  • 1995-1999  (5)
  • 1
    ISSN: 1432-1084
    Keywords: Key words: MR imaging ; Contrast agents ; Gd-DTPA ; Gd-DTPA BMA ; Relaxivity ; Relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We report in vitro T1 and T2 relaxation studies for the open-chain complexes Gd-DTPA and Gd-DTPA BMA. Measurements were performed on phantoms containing aqueous and plasma solutions of different concentrations by MR imaging in a 1.5T superconducting whole-body scanner. Longitudinal relaxation times T1 were evaluated from serial turbo-FLASH experiments for concentrations less than 1 mM, whereas for larger concentrations the values were obtained from a standard inversion recovery (IR) sequence. Transverse relaxation times T2 were determined using multi-echo spin-echo MRI protocols. The T1 and T2 relaxivities of the nonionic Gd-DTPA BMA are similar to those of the Gd-DTPA. The temperature dependencies of the relaxivities were determined over a temperature interval ranging from 21 to 50 °C and were found to be slightly different for the two contrast agents. In the case of Gd-DTPA BMA a larger deviation of the expected temperature behavior of the relaxivities was observed as compared with Gd-DTPA. Deviations from a strictly linear dependence of relaxation times on temperature were found at lower concentrations in aqueous solutions. In plasma solutions a high T1/T2 ratio was observed for low concentrations, which decreased monotonically with increasing concentrations.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatsschrift Kinderheilkunde 147 (1999), S. 940-941 
    ISSN: 1433-0474
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 68 (1999), S. 343-347 
    ISSN: 1432-0649
    Keywords: PACS: 42.30; 07.79; 42.65.k
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: We present an analysis of these effects and demonstrate a simple, yet powerful technique to eliminate these coherence artifacts. The technique relies on a superposition of the signal field with a coherent auxiliary SH-field of controllable phase and amplitude and allows a direct observation of the true χ(2)-morphology of the interface.
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  • 4
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Atopic dermatitis (AD) is a chronic skin disease associated with increased IgE synthesis and colonization with Staphyiococcus aureus secreting exotoxins, such as Toxic Shock Syndrome Toxin-1 (TSST-1). Objectives In this study, we were interested in determining the in vitro effects of TSST-1 on IgE synthesis in peripheral blood mononuclear cells from patients with AD. Methods We stimulated peripheral blood mononuclear cells (PBMC) from AD patients with a wide range of TSST-1 concentrations and measured IgE synthesis by enzyme-linked immunosorbent assay (ELISA) after 14 days. Results We show herein that TSST-1 produced antagonistic effects on IgE synthesis by PBMC from AD patients, depending on the concentration used: IgE synthesis was inhibited at 1000 pg/mL (P〈0.05) and enhanced at 0.01 pg/mL (P〈0.01) of toxin. TSST-1 was found to induce the production of much higher amounts of interferon-gamma (IFNγ) at 1000 pg/mL than at 0.01pg/mL of toxin (P= 0.0001). More importantly, immunoglobulin E (IgE) synthesis was enhanced by TSST-1 at 1 pg/mL in the presence of antibodies blocking IFN-γ activity. The other immunoglobulin (Ig) isotypes were also increased after TSST-1 stimulation suggesting that the enhanced IgE synthesis was secondary to a polyclonal B cell activation rather than an isotype switch. TSST-1-stimulated IgE synthesis was T cell-dependent because purified tonsil B cells were only able to synthesize increased amounts of IgE when small numbers of T cells were added to the cultures. Anti-HLA-DR and anti-LFA-1 monoclonal antibodies (MoAb) inhibited TSST-1-enhanced IgE synthesis, suggesting that the bridging of the T cell receptor (TCR) and major histocompalibilily complex (MHC) class II on B cells was necessary for activation of B cell differentiation. Conclusion These data indicate that staphylococcal superantigens are able, at concentrations inducing low amounts of IFNγ, to stimulate IgE synthesis by PBMC from AD patients, and suggest that staphylococcal toxins may contribute to elevated IgE synthesis in AD.
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  • 5
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Persons with immune deficiency may present with atypical results in serological tests for hepatitis B virus (HBV). Frozen serum specimens that were sequentially obtained over time from a cohort of 57 HIV-infected patients, all of whom tested positive only for antibody to hepatitis B core antigen (anti-HBcAg), were therefore restested for HBV markers, including HBV DNA. The results were assessed for their time course and correlated with clinical data and alanine aminotransferase (ALT) values. Forty-eight patients were male; intravenous drug users constituted the principal risk group (n=30), followed by homosexual men (n=22). Thirty-three persons tested positive for antibody to hepatitis C virus (anti-HCV). During a median of 31 months from the first to the last serum, anti-HBcAg remained the sole marker of HBV infection in 98.2% of the patients. Polymerase chain reaction (PCR) to detect DNA for HBV core and HBV surface gene was positive in 126 (62.4%) and 121 (59.9%) of all 202 serum samples, respectively. Over time, HBV DNA was detected at least once in 51 (89.5%) patients. In contrast, decomplexed hepatitis B surface antigen (HBsAg) was detected at least once in 14 (24.6%) patients. Among patients positive for HBV DNA and negative for anti-HCV, eight (36.4%) of 22 had chronic hepatitis (ALT elevation ≥6 months) that was attributable only to persisting HBV infection. Similarly, 12 (41.4%) of 29 patients positive for both HBV DNA andanti-HCV had chronic viral hepatitis, but their ALT values were significantly higher. In HIV-infected patients, anti-HBcAg as the sole serological HBV marker detected must be considered indicative of chronic HBV infection and is in part associated with chronic hepatitis and ALT elevation.
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