To explore the direct role of -amyloid (A) and carboxyl-terminal fragments of amyloid precursor protein in the inflammatory processes possibly linked to neurodegeneration associated with Alzheimer's disease, the effects of the 105-amino acid carboxyl-terminal fragment (CT 105 ) of amyloid precursor protein on the production of tumor necrosis factor-␣ (TNF-␣) and matrix metalloproteinase-9 (MMP-9) were examined in a human monocytic THP-1 cell line and compared with that of A. CT 105 elicited a marked increase in TNF-␣ and MMP-9 production in the presence of interferon-␥ in a dose-and time-dependent manner. Similar patterns were obtained with A despite its low magnitude of induction. Autocrine TNF-␣ is likely to be a main mediator of the induction of MMP-9 because the neutralizing antibody to TNF-␣ inhibits MMP-9 production. Genistein, a specific inhibitor of tyrosine kinase, dramatically diminished both TNF-␣ secretion and subsequent MMP-9 release in response to CT 105 or A. Furthermore, PD98059 and SB202190, specific inhibitors of ERK or p38 MAPK respectively, efficiently suppressed CT 105 -induced effects whereas only PD98059 was effective at reducing A-induced effects. Our results suggest that CT 105 in combination with interferon-␥ might serve as a more potent activator than A in triggering inflammatory processes and that both tyrosine kinase and MAPK signaling pathways may represent potential therapeutic targets for the control of Alzheimer's disease progression.
Austenitic stainless steel has good weldability but is sensitive to hot cracking such as solidification and liquation cracking. In the present study, specimens of dissimilar metals made from austenitic stainless steel and Al brass were welded by the GTAW process using four different filler metals. Cracks were detected in the heat affected zone of the stainless steel when welded with CuAl, CuSn and NiCu filler metals, but no cracks were detected when a Ni filler metal was used. The cracks propagated along the grain boundary in the heat affected zone near the fusion line to the base metal of 316L stainless steel. The cracks were located inside the weld bead with very fine hairline cracking. All cracks initiated at the fusion line and moved forward in the base metal. From energy dispersion spectroscopy (EDS), the Cu peak was detected only in the crack-opening area.
Reversed austenite transformation and existence of retained austenite during tempering of the super martensitic stainless steel of Fe-14Cr-7Ni-0.3Nb-0.7Mo-0.03C were studied by means of experiments on microstructure and X-ray diffraction, and tensile and hardness tests. Acicular type retained austenite at the lath boundary of martensite with the interior appeared after solution annealing. This retained austenite still existed, and reversed austenite was not formed, with tempering up to 24 h at 450 °C. The reversed austenite began to form above 550 °C, and the volume fraction of reversed austenite decreased with increasing tempering temperature after showing a maximum value of 19.2 % at 650 °C. This maximum volume fraction of reversed austenite was responsible for the lowest value of strength and hardness. The Ni contents of plate type reversed austenite and the surrounding matrix increased and decreased respectively, implying that the reversed austenite was formed as a result of nickel diffusion. The orientation relationships between reversed austenite and the surrounding matrix showed a K-S relationship of (111)
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