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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 33 (2003), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Consideration of the evolutionary significance of IgE might provide insight into the immunological interactions occurring in utero and during early post-natal life that regulate later atopic disease.Objective We postulated that the fetal gut is exposed to intact amniotic fluid IgE that might interact with local IgE receptors.Methods IgE levels in matched maternal blood and amniotic fluid (n = 47) or breast milk (n = 15) collected from pregnant women in the UK (Southampton) and Brazil (Sao Paulo) were studied. Expression of IgE receptors, FcɛRI and FcɛRII (CD23), in fetal gastrointestinal tract (n = 19) and skin (n = 11) was examined immunohistochemically.Results Human amniotic fluid at 16–18 weeks' gestation contained intact IgE at levels that increased as maternal circulating levels increased (Spearman's ρ = 0.897; P 〈 0.001). Circulating IgE levels from women in Sao Paulo, Brazil, associated positively not only with term (〉 37 weeks' gestation) amniotic fluid (ρ = 0.993; P 〈 0.001) but also breast milk IgE levels (ρ = 0.785; P = 0.001). Maternal levels of IgE did not change significantly over pregnancy and fetal circulating levels of IgE were very low (〈 0.6 IU/mL). Low-affinity IgE receptors (CD23) were expressed in lymphoid follicles of the fetal gut from 16 weeks of gestation (6/8), but not from 11 to 16 weeks (0/11) or in the skin.Conclusion Amniotic fluid contains intact IgE that might bind to CD23+ cells within the lymphoid follicles of the fetal gastrointestinal tract. The evolutionary significance of these interactions might be to prepare the immune system for helminthic parasite exposure at birth via IgE-mediated antigen focusing, or ‘education’ of the developing immune system about the prevailing extrauterine environment. However, at present in societies where helminthosis is not a significant health issue, this pathway may still be operational and associated with the development of atopic disease.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Alveolar macrophages and their precursors, the monocytes are involved in airway inflammation in asthma. An increase in intraceliular cAMP by PDE inhibitors is known to suppress macrophage and monocyte functions. A comparison of the PDE-isoenzyine profiles of human alveolar macrophages from normal and atopic donors and of human peripheral blood monocytes might form a basis to differentially affect functions of these cells by PDE inhibitors.Objective The study compares the PDE isoenzyme activity profiles of human alveolar macrophages from normal and atopic asthmatic donors and human peripheral blood monocytes. In addition, the effect of in vitro maturation of monocytes on their PDE isoenzyme profile is studied.Methods Macrophages were purified (95-97%) by adherence to plastic, and blood monocytes were purified (88%) by counter-current elutriation. PDE isoenzyme activity profiles were investigated using isoenzyme selective inhibitors and activators.Results In macrophages substantial PDE I activity, which was significantly higher than PDE IIF-V activity was detected and PDE II was absent. PDE III was membrane-bound whereas PDE I, IV and V were soluble. No difference was found between alveolar macrophages of normal donors and atopic asthmatics. Monocytes exclusively contained PDE IV but their in vitro maturation led to a PDE isoenzyme profile similar to that of alveolar macrophages.Conclusion These results indicate that human monocytes and alveolar macrophages are distinct targets for the effects of selective PDE inhibitors while alveolar macrophages from normal and atopic individuals appear to be equally sensitive.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 25 (1995), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background CD4+ and CD8+ T-lymphocytes are suggested to differentially affect airway inflammation in asthma. Agents which increase intracellular cAMP levels, such as PDE inhibitors, have been shown to diminish lymphocyte growth and differentiation, and to affect cytokine expression. Differences in the PDE isoenzyme profile between CD4+ and CD8+ cells might form a basis to differentially modify their functions by PDE inhibitors.Objective The study investigates and compares the PDE isoenzyme activity profiles of human peripheral blood CD4+ and CD8+ T-lymphocytes.Methods CD4+ and CD8+ T-lymphocytes were purified (〉98%) from peripheral blood mononuclear cells by negative selection. PDE isoenzyme activity profiles were investigated using PDE isoenzyme selective inhibitors and activators.Results In CD4+ and CD8+ T-lymphocyte homogenates, PDE IV and PDE III activities were the predominant PDE isoenzyme activities at 0.5μM cyclic nucleotide substrate concentrations. PDE IV was localized in the soluble fraction whereas PDE III was membrane bound. Low PDE I, II and V activities were detected. About 20% of total eAMP hydrolysing capacity at 0.5 μM cAMP was insensitive to PDE isoenzyme selective inhibitors and activators and therefore could not be assigned to PDE I-IV. The PDE isoenzyme pattern was not different between CD4+ and CDS+ T-lymphocytes. Moreover, representative inhibitors of PDE HI and IV activity inhibited cAMP hydrolysis in soluble fractions of both T-lymphocyte subsets with similar potency. Enzyme kinetic analysis similarly did not reveal differences between CD4h and CD8+ T-lymphocytes.Conclusion Normal CD4+ and CD8+ T-lymphocytes are likely to be equally sensitive targets for the effects of PDE inhibitors.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 24 (1994), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Although neutrophils have been implicated in bronchial asthma, the mechanism(s) which bring these cells into the airways is poorly understood.Objective To investigate the presence and identity of neutrophil chemotactic factors in bronchoalveolar lavage (BAL) fluid from atopic asthmatic subjects.Method BAL fluid was obtained from 13 subjects (seven asthmatics and six normals). aged 19 to 60 yr, at bronchoscopy. Separation of neutrophil chemotactic activity (NCA) was achieved by FPLC cation exchange chromatography. Fractions were collected and assayed for chemotaxis multiwell micro-chemotaxes chambers using polycarbonate filters, for the complement peptide C5a/C5a des Arg by radioimmunoassay (RIA) and for interleukin-8 (IL-8) by ELISA.Results NCA was found in FPLC fractions of BAL samples in four out of seven asthmatics and each of these subjects had at least three similar peaks of NCA. The major peak of NCA was found to contain immunoreactive C5a/C5a des Arg and chemotaxis. In response to this NCA could be blocked by desensitization of the neutrophils with recombinant C5a. Purified serum derived C5a/C5a des Arg was found to have altered chromatographic properties when added to BAL fluid; this suggested that BAL fluid contained proteins which interacted with the C5a/C5a des Arg. Immunoreactive IL-8 (iIL-8) was also detected but its concentration or chemical form was insufficient to induce neutropbil chemotaxis.Conclusion This study demonstrates that bronchial asthmatic lavage fluid contains C5a/C5a des/Arg and iL-8, together with other as yet unidentified factors which may contribute to neutropbil recruitment in this disease.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Phosphoinositide metabolism in the plasma membrane is linked to transmembrane signal transduction. In this study we have investigated some physical properties (e.g. molecular order and dynamics) of phosphatidylinositol (PI) in various membrane preparations by time-resolved fluorescence techniques, using a synthetic PI derivate with a cis-parinaroyl chain on the sn-2 position. Phospholipid vesicles, normal and denervated rat skeletal muscle sarcolemmal membranes, and acetylcholine receptor rich membrances from Torpedo marmorata were investigated both at 4°C and 20 °C. For comparison we have also included 2-parinaroyl-phosphatidylcholine (PC) in this study. The fluorescent lipids were incorporated into the membrane preparations by way of specific phospholipid transfer proteins, to ensure an efficient and non-perturbing insertion of the lipid-probes. In the Torpedo membranes the order parameters measured for the parinaroyl derivatives of both PC and PI were higher than in phospholipid vesicles. For the Torpedo membrane preparations the acyl chain order for the PI was lower than that for PC, whereas the opposite was true for the vesicles. This inversion strongly suggests that PI has different interactions with certain membrane components as compared to PC. This is also suggested by the significantly higher rate of restricted rotation of PI as compared to PC. In contrast to the order parameters, the correlation times were almost identical for both probes and showed little difference between vesicles and the Torpedo membranes. In contrast to Torpedo membranes, the time-dependent fluorescence anisotropy of the two lipid probes in the sarcolemmal membranes showed, after an initial fast decay, a subsequent gradual increase. This phenomenon was satisfactorily analyzed by assuming two populations of probe lipids with distinct lifetimes, rotational correlation times and molecular order. The order parameter of the population with a short lifetime compared with that of phospholipid vesicles, whereas the population with a long lifetime agreed with that of the Torpedo membranes.
    Type of Medium: Electronic Resource
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