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N Noviski JP Brewer WA Skornik SJ Galli JM Drazen TR Martin 《Canadian Metallurgical Quarterly》1999,86(1):202-210
Exposure to ambient ozone (O3) is associated with increased exacerbations of asthma. We sought to determine whether mast cell degranulation is induced by in vivo exposure to O3 in mice and whether mast cells play an essential role in the development of pulmonary pathophysiological alterations induced by O3. For this we exposed mast cell-deficient WBB6F1-kitW/kitW-v (kitW/kitW-v) mice and the congenic normal WBB6F1 (+/+) mice to air or to 1 or 3 parts/million O3 for 4 h and studied them at different intervals from 4 to 72 h later. We found evidence of O3-induced cutaneous, as well as bronchial, mast cell degranulation. Polymorphonuclear cell influx into the pulmonary parenchyma was observed after exposure to 1 part/milllion O3 only in mice that possessed mast cells. Airway hyperresponsiveness to intravenous methacholine measured in vivo under pentobarbital anesthesia was observed in both kitW/kitW-v and +/+ mice after exposure to O3. Thus, although mast cells are activated in vivo by O3 and participate in O3-induced polymorphonuclear cell infiltration into the pulmonary parenchyma, they do not participate detectably in the development of O3-induced airway hyperresponsiveness in mice. 相似文献
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Hierarchical organization of cognitive memory 总被引:1,自引:0,他引:1
M Mishkin WA Suzuki DG Gadian F Vargha-Khadem 《Canadian Metallurgical Quarterly》1997,352(1360):1461-1467
This paper addresses the question of the organization of memory processes within the medial temporal lobe. Evidence obtained in patients with late-onset amnesia resulting from medial temporal pathology has given rise to two opposing interpretations of the effects of such damage on long-term cognitive memory. One view is that cognitive memory, including memory for both facts and events, is served in a unitary manner by the hippocampus and its surrounding cortices; the other is that the basic function affected in amnesia is event memory, the memory for factual material often showing substantial preservation. Recent findings in patients with amnesia resulting from relatively selective hippocampal damage sustained early in life suggest a possible reconciliation of the two views. The new findings suggest that the hippocampus may be especially important for event as opposed to fact memory, with the surrounding cortical areas contributing to both. Evidence from neuroanatomical and neurobehavioural studies in monkeys is presented in support of this proposal. 相似文献
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The effect of glucocorticoid (GC) treatment on expression and release of the monocyte cell surface LPS receptor Ag CD14 was studied in vivo and in vitro. In patients with acute inflammatory diseases receiving GC pulse therapy serum concentrations of soluble CD14 and CD14 expression by peripheral blood monocytes decreased significantly. The LPS-binding capacity correlated positively with the amount of cell surface CD14 by human blood monocytes. In vitro, a time- and dose-dependent effect of GC preparations on monocyte membrane and soluble CD14 by cultured peripheral blood monocytes was found. Incubation with 2 x 10(-8) M prednisolone down-regulated cell surface CD14 after 72 h, and 2 x 10(-7) M suppressed CD14 expression even after 24 h. Prednisolone also decreased release of the soluble CD14 Ag, where a 10-fold higher GC concentration was required for a significant suppression compared with membrane CD14 during culture. Expression of other monocyte membrane Ags were either unchanged (CD33, CD35), diminished (CD13, CD89), or increased (CD32) by GC, indicating no general down-modulation of cell surface Ag expression. Preincubation with glucocorticoids for 24 h significantly down-regulated CD14 expression during subsequent steroid-free culture for at least 7 days. In cultured monocytes, the LPS-induced increase of membrane and soluble CD14 was markedly but not completely inhibited by prednisolone. Therefore, GC treatment suppresses the up-regulation of the LPS receptor during endotoxin challenge, and likewise, the IL-1 secretion after LPS stimulus was significantly diminished. Taken together, the suppression of the monocytic cell surface and soluble endotoxin receptor CD14 by GC may contribute to the increased risk of infections in patients undergoing steroid therapy. 相似文献
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Both glucagon and glucagon-like peptide-1 (GLP-1) play an important role in the regulation of nutrient homeostasis. In this study, the tissue distributions of the expression of receptor genes for glucagon and GLP-1 were examined. Expression of glucagon receptor gene was detected in liver, kidney, ileum and pancreatic islets but not in brain. In contrast, expression of GLP-1 receptor gene was detected in brain, pancreas and pancreatic islets but not in liver, kidney, or ileum. To investigate the existence and characteristics of glucagon and GLP-1 receptors on pancreatic beta cells, expression of the receptor genes and translational regulation of the expression of the receptor genes by glucose were analyzed in a mouse pancreatic beta cell line, MIN6 cells. In the cDNA pool of MIN6 cells, both glucagon and GLP-1 receptor genes were identified and showed higher expression level in MIN6 cells cultured under high glucose condition than in those cultured under low glucose condition. These results suggest that glucagon and GLP-1 receptor genes are expressed in pancreatic beta cells and their expression is upregulated by glucose. 相似文献