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81.
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J C Marvizón J Vázquez M García Calvo F Mayor A Ruíz Gómez F Valdivieso J Benavides 《Molecular pharmacology》1986,30(6):590-597
The displacement by glycine of 3H-strychnine binding to rat spinal cord membranes cannot be explained by a simple competitive interaction. Indeed, protein-modifying reagents can completely abolish the inhibition of 3H-strychnine binding by glycine and other agonists, whereas the interaction of strychnine itself and other related compounds with the binding site is unimpaired. Moreover, glycine cannot inhibit completely saturable 3H-strychnine binding, the extent of its maximum inhibitory effect depending on the ionic composition of the medium. Hill coefficients less than 1 (whose magnitude also depends on the assay medium) were obtained from glycine displacement curves. These properties are consistent with a mathematical model of two different, but mutually interacting, binding sites for strychnine and glycine on the glycine receptor. The effect of ions and protein-modifying reagents might be explained in this model as modifications of the mechanisms that mediate the allosteric interaction, and/or the affinity of glycine for the receptor. The agonists beta-alanine and taurine and the new antagonists, THAZ, iso-THAZ, and 4,5-TAZA, also seem to interact with a site different from the strychnine-binding site, probably the glycine-binding site. 相似文献
84.
85.
R. Nickel S. Lau B. Niggemann C. Sommerfeld U. Wahn the German Multicenter Allergy Study Group 《Clinical and experimental allergy》2002,32(9):1274-1277
BACKGROUND: Bronchial responsiveness (BR) to histamine or methacholin is a common finding in adult non-asthmatic patients with allergic rhinitis. OBJECTIVE: We tested whether BR is also present in children with a comparatively short history of allergic rhinitis in a paediatric cohort. METHODS: We performed pulmonary function tests and histamine challenges in a total of 654 children (age 7 years, participants of the German Multicenter Allergy Study) and compared PC20 FEV1 values in children with asthma, allergic rhinitis, asymptomatic allergic sensitization and non-atopic controls. RESULTS: Most pronounced BR to histamine was observed in allergic asthmatics (n = 28), irrespective of the presence or absence of allergic rhinitis. Furthermore, PC(20)FEV(1) values in non-asthmatic children with allergic rhinitis (n = 24) were not significantly different from those seen in asymptomatic atopic (n = 54) or non-atopic controls (n = 92). CONCLUSIONS: In contrast to adult study populations, 7-year-old non-asthmatic children with allergic rhinitis do not show a higher degree of BR than asymptomatic atopic or non-atopic controls. Therefore, secondary preventive measures in non-asthmatic children with allergic rhinitis (such as regular local anti-inflammatory therapy or specific immunotherapy) should be studied and applied more intensely to prevent bronchial hyper-responsiveness (BHR) and asthma in this high-risk group. 相似文献
86.
E. Baldo Corrêa J. M. T. Cunha M. M. Bunn-Moreno E. D. Madeira 《Parasitology research》1992,78(2):154-160
We observed histopathological and ultrastructural hepatic changes following the intracardiac inoculation ofLeishmania donovani amastigotes into inbred LHC hamsters (group I). Since granuloma formation is known to be T-cell-dependent, we also examined infected hamsters under cyclophosphamide immunosuppressive treatment (group ICy) and evaluated the production of interleukin-2 (IL-2) by their cells. Group I showed more intense hepatocyte and endothelial cell clasmatosis as well as hepatocyte degeneration and necrosis, deposits of connective tissue fibers, granulomas with multinucleated giant cells (MGCs) of foreign-body and Langhans' types and reduced production of IL-2 by spleen cells. In contrast, group ICy hamsters exhibited larger eosinophil and lymphocyte populations within sinusoids and peri-sinusoidal areas but showed no MGCs in granulomas. A striking decline in IL-2 production was noted. These results suggest that cyclophosphamide induces a delay in the natural evolution ofL. donovani-induced granulomatous hepatic inflammation. 相似文献
87.
Coppo R; Cirina P; Amore A; Sinico R; Radice A; Rollino C; the Italian Group of Renal Immunopathology Collaborative Study on Henoch-Schonlein purpura in adults f; children i 《Nephrology, dialysis, transplantation》1997,12(11):2269-2276
Background: The presence and the pathogenetic role of
circulating IgA reacting with neutrophil cytoplasmic antigens (IgA-ANCA) in
patients with Henoch-Schonlein purpura (HSP) is still debated. This study
was aimed to investigate some characteristics of serum IgA and
macromolecular IgA in HSP patients, focusing on IgA-ANCA.
Methods: Eighty-seven HSP patients with biopsy proved
renal involvement (51 adults and 36 children) enrolled in a multicentre
study of the Italian Group of Immunopathology were investigated.
Results: Significantly high levels of IgA immune
complexes were found in both adults (P <0.05) and children (P
<0.01), while the binding of IgA to jacalin, was significantly low
in children with HSP (P <0.01) only. Two series of ELISA were done
for IgA-ANCA, in two different laboratories. Increased binding to PMN crude
extracts (P <0.01) without any modification in IgA binding to
proteinase 3 was found by either specific ELISA. Conversely, the binding of
IgA to myeloperoxidase (MPO) was found to be significantly (P <0.05)
increased with positive values in 25% of patients by one assay only. Three
of four sera with positive IgA-MPO ANCA exhibited binding in Western-blot
studies with the MPO preparation used in ELISA to a 28-kDa species.
D-galactose and N-acetyl-glucosamine decreased the binding of serum IgA to
MPO more in HSP than in controls (P <0.05).
Conclusions: The conflicting reports on IgA-ANCA may
reflect some atypical characteristics of the reaction which can be detected
only by some ELISAs. We suggest that not an antigen-antibody reaction but a
lectinic interaction due to abnormal composition of IgA carbohydrate side
chains may account for the IgA-ANCA reaction in patients with HSP
nephritis. 相似文献
88.
María de Gracia García-Martín María Violante de Paz Juan Antonio Galbis 《Macromolecular chemistry and physics.》1997,198(1):219-227
A chiral poly(3-substituted isobutyl D -aspartate) 12 was synthesized by polymerization of the chiral β-lactam 11 derived from D -glyceraldehyde. The new polyamide was characterized by elemental analyses, and infrared, 1H- and 13C nuclear magnetic resonance spectroscopies. The molecular weight was estimated as 543 000 and 230 000 on the basis of viscosimetric measurements and gel-permeation chromatography, respectively. Polyamide 12 is soluble in a variety of organic solvents including chloroform. 相似文献
89.
Emília P. Duarte Graça Baltazar Arsélio P. Carvalho 《The European journal of neuroscience》1994,6(7):1128-1135
We compared the effectiveness of Ca2+ entering by Na+/Ca2+ exchange with that of Ca2+ entering by channels produced by membrane depolarization with K+ in inducing catecholamine release from bovine adrenal chromaffin cells. The Ca2+ influx through the Na+/Ca2+ exchanger was promoted by reversing the normal inward gradient of Na+ by preincubating the cells with ouabain to increase the intracellular Na+ and then removing Na+ from the external medium. In this way we were able to increase the cytosolic free Ca2+ concentration ([Ca2+]c) by Na+/Ca2+ exchange to 325 ± 14 nM, which was similar to the rise in [Ca2+]c observed upon depolarization with 35 mM K+ of cells not treated with ouabain. After incubating the cells with ouabain, K+ depolarization raised the [Ca2+]c to 398 ± 31 nM, and the recovery of [Ca2+]c to resting levels was significantly slower. Reversal of the Na+ gradient caused an −6-fold increase in the release of noradrenaline or adrenaline, whereas K+ depolarization induced a 12-fold increase in noradrenaline release but only a 9-fold increase in adrenaline release. The ratio of noradrenaline to adrenaline release was 1.24 ± 0.23 upon reversal of the Na+/Ca2+ exchange, whereas it was 1.83 ± 0.19 for K+ depolarization. Reversal of the Na+/Ca2+ exchange appeared to be as efficient as membrane depolarization in inducing adrenaline release, in that the relation of [Ca2+]c to adrenaline release was the same in both cases. In contrast, we found that for the same average [Ca2+]c, the Ca2+ influx through voltage-gated channels was much more efficient than the Ca2+ entering through the Na+/Ca2+ exchanger in inducing noradrenaline release from chromaffin ceils. This greater effectiveness of membrane depolarization in stimulating noradrenaline release suggests that there is a pool of noradrenaline vesicles which is more accessible to Ca2+ entering through voltage-gated Ca2+ channels than to Ca2+ entering through the Na+/Ca2+ exchanger, whereas the adrenaline vesicles do not distinguish between the source of Ca2+. 相似文献
90.