28 research outputs found
Regulation of intracellular free arachidonic acid in Aplysia nervous system
We have studied the regulation of arachidonic acid (AA) uptake, metabolism, and release in Aplysia nervous system. Following uptake of [ 3 H]AA, the distribution of radioactivity in intracellular and extracellular lipid pools was measured as a function of time in the presence or absence of exogenous AA. The greatest amount of AA was esterified into phosphatidylinositol (relative to pool size). We found that the intracellular free AA pool underwent rapid turnover, and that radioactive free AA and eicosanoids were released at a rapid rate into the extracellular medium, both in the presence and absence of exogenous AA. Most of the released radioactivity originated from phosphatidylinositol.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48020/1/232_2005_Article_BF01868464.pd
Modeling Progressive Damage Using Local Displacement Discontinuities within the FEAMAC Multiscale Modeling Framework
Abnormal plasma polyunsaturated fatty acid pattern in non-active inflammatory bowel disease
An abnormal plasma polyunsaturated fatty acid pattern (PUFA) (increased n3 and decreased n6 PUFA) has been reported in active inflammatory bowel disease (IBD). The possibility of a primary defect in the PUFA metabolism in IBD was hypothesised. The aim of this study was to assess plasma PUFA pattern in inactive inflammatory bowel disease and to ascertain whether patients who had had a colectomy and who were suffering from ulcerative colitis have a similar PUFA pattern than those patients with non-active ulcerative colitis and who had not had a colectomy. Plasma fatty acids were analysed by semi-capillary column gas-liquid chromatography in three groups of patients with inactive IBD (24 patients with inactive ulcerative colitis who had not had a colectomy, 15 patients with ulcerative colitis who had had a colectomy, and 27 patients with Crohn's disease). Plasma concentration and percentage of C22:6n3 and unsaturation index were significantly higher in patients with inactive ulcerative colitis without a colectomy and the Crohn's disease group (p < 0.0001) than in controls. Plasma concentration and percentage of C22:6n3 and the unsaturation index remained significantly higher, in both the operated and non-operated ulcerative colitis patients when compared with controls (p < 0.0001). These results suggest that in inactive IBD, an increased PUFA biosynthesis might be the cause of the high values of n3 compounds. These findings although seen in active disease, are more noticeable in remission because of the lack of artefactual factors (malnutrition, steroids, inflammation). In addition, persistence of high values in both groups of ulcerative colitis patients--that is, those who had had a colectomy and those who had not suggests the existence of a primary abnormality in the PUFA metabolism in IBD
Assessment of void growth models from porosity measurements in cold-drawn copper bars
This work investigates void growth in cold-drawn copper bars containing a fine dispersion of small inclusions at which voids nucleate. Using the Rice and Tracey (RT), the Gurson-Tvergaard (GT), and the Gurson-Leblond-Perrin (GLP) void growth models, a procedure is proposed for deriving the porosity distribution from density measurements on specimens sectioned from the neck of a tensile bar. This procedure allows identification of the parameters of the models. The effect of strain hardening on porosity evolution is analyzed by comparing the behavior of the material in the cold-drawn state (n approximate to 0.1) and in the recrystallized state (n approximate to 0.4). Inclusion dimensions and distributions were found to be identical in these two states. The parameter ct of the RT model is found to depend on n, whereas the parameter q of the Gurson-type models does not vary with n. Numerical modeling of porosity variations in notched, round copper bars shows that both the parameter cu and the parameter q in the GT model depend on the stress triaxiality in the recrystallized material, whereas the parameter q remains a constant in the GLP model. Accounting for the ellipsoidal void shapes and for the presence of the inclusion significantly affects the prediction of porosity variations