Nanoscale structural and mechanical characterization of the shell of a red abalone has been carried out. Cobble-like polygonal nanograins are
basic building blocks that are used to construct individual aragonite platelets into a mother-of-pearl configuration known as nacre. The nanograin-structured aragonite platelets are not brittle in nature, but somewhat ductile. The deformability of the aragonite platelets together with the
crack deflection, aragonite platelet slip, and organic adhesive interlayer contribute to the nacre's fracture toughness. Cracks formed in the
outer prismatic layer of the shell do not show the crack diversion mechanism.
The multifunctional cytokine interleukin-6 (IL-6) regulates growth and differentiation of many cell types and induces production of acute-phase proteins in hepatocytes. Here we report that IL-6 protects hepatoma cells from apoptosis induced by transforming growth factor- (TGF-), a well known apoptotic inducer in liver cells. Addition of IL-6 blocked TGF--induced activation of caspase-3 while showing no effect on the induction of plasminogen activator inhibitor-1 and p15INK4B genes, indicating that IL-6 interferes with only a subset of TGF- activities. To further elucidate the mechanism of this anti-apoptotic effect of IL-6, we investigated which signaling pathway transduced by IL-6 is responsible for this effect. IL-6 stimulation of hepatoma cells induced a rapid tyrosine phosphorylation of the p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase) and its kinase activity followed by the activation of Akt. Inhibition of PI 3-kinase by wortmannin or LY294002 abolished the protection of IL-6 against TGF--induced apoptosis. A dominant-negative Akt also abrogated this anti-apoptotic effect. Dominant-negative inhibition of STAT3, however, only weakly attenuated the IL-6-induced protection. Finally, inhibition of both STAT3 and PI 3-kinase by treating cells overexpressing the dominant-negative STAT3 with LY294002 completely blocked IL-6-induced survival signal. Thus, concomitant activation of the PI 3-kinase/Akt and the STAT3 pathways mediates the anti-apoptotic effect of IL-6 against TGF-, with the former likely playing a major role in this anti-apoptosis.
The primary objective of this paper is to evaluate the impact of Taiwan's National Health Insurance program (NHI), established in 1995, on improving elderly access to care and health status. Further, we estimate the extent to which NHI reduces gaps in access and health across income groups. Using data from a longitudinal survey, we adopt a difference-in-difference methodology to estimate the causal effect of Taiwan's NHI. Our results show that Taiwan's NHI has significantly increased utilization of both outpatient and inpatient care among the elderly, and such effects were more salient for people in the low- or middle-income groups. Our findings also reveal that although Taiwan's NHI greatly increased the utilization of both outpatient and inpatient services, this increased utilization of health services did not reduce mortality or lead to better self-perceived general health status for Taiwanese elderly. Measures more sensitive than mortality and self-perceived general health may be necessary for discerning the health effects of NHI. Alternatively, the lack of NHI effects on health may reflect other quality and efficiency problems inherent in the system not yet addressed by NHI.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.