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M K S Leow 《Hormones et métabolisme》2005,37(1):1-3
The short ACTH stimulation test (SST) is commonly used by clinicians to determine the integrity of the hypothalamic-pituitary-adrenal (HPA) axis in cases of suspected adrenal insufficiency. Concern has arisen for under-diagnosis of central hypocortisolism using the standard dose (250 mcg) SST with the recent introduction of low-dose (1 mcg) SST as a potentially more sensitive test for central hypocortisolism. Amidst this uncertainty, I will present a novel index hypothesized to extend the sensitivity of the standard dose SST as an adjunctive diagnostic tool for any level of hypocortisolism. 相似文献
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Effect of Redox Balance Alterations on Cellular Localization of LAT and Downstream T-Cell Receptor Signaling Pathways
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Sonja I. Gringhuis Ellen A. M. Papendrecht-van der Voort Angela Leow E. W. Nivine Levarht Ferdinand C. Breedveld Cornelis L. Verweij 《Molecular and cellular biology》2002,22(2):400-411
The integral membrane protein linker for activation of T cells (LAT) is a central adapter protein in the T-cell receptor (TCR)-mediated signaling pathways. The cellular localization of LAT is extremely sensitive to intracellular redox balance alterations. Reduced intracellular levels of the antioxidant glutathione (GSH), a hallmark of chronic oxidative stress, resulted in the membrane displacement of LAT, abrogated TCR-mediated signaling and consequently hyporesponsiveness of T lymphocytes. The membrane displacement of LAT is accompanied by a considerable difference in the mobility of LAT upon native and nonreducing denaturing polyacrylamide gel electrophoresis analysis, a finding indicative of a conformational change. Targeted mutation of redox-sensitive cysteine residues within LAT created LAT mutants which remain membrane anchored under conditions of chronic oxidative stress. The expression of redox-insensitive LAT mutants allows for restoration of TCR-mediated signal transduction, whereas CD28-mediated signaling pathways remained impaired. These results are indicative that the membrane displacement of LAT as a result of redox balance alterations is a consequence of a conformational change interfering with the insertion of LAT into the plasma membrane. Conclusively, the data suggest a role for LAT as a crucial intermediate in the sensitivity of TCR signaling and hence T lymphocytes toward chronic oxidative stress. 相似文献