The aim of this paper is to report the optical properties of
normalK2SinormalF6:normalMn4+
phosphor prepared by wet chemical etching of Si wafers in a
HF∕KMnnormalO4
mixed solution. The luminescence centers of sharp red emission at
∼630nm
are ascribed to the
Mn4+
ions in the octahedral site of
normalK2SinormalF6
gained by the activation of local vibration modes
(normalA24→normalE2)
. All the expected electronic and vibronic origins of the
normalE2→normalA24
,
normalA24→normalT24
, and
normalA24→normalT14
transitions of the
Mn4+
ions are identified and depicted in the Tanabe–Sugano diagram of a
3normald3
transition-metal system. The temperature-dependent photoluminescence properties suggest that the anti-Stokes/Stokes intensity ratio can be explained by the Maxwell–Boltzmann factor but only at low temperatures and low-excitation power intensities.
Carbon monoxide (CO), a byproduct of heme catabolism by heme oxygenase (HO), confers potent antiinflammatory effects. Here we demonstrate that CO derived from HO-1 inhibited Toll-like receptor (TLR) 2, 4, 5, and 9 signaling, but not TLR3-dependent signaling, in macrophages. Ligand-mediated receptor trafficking to lipid rafts represents an early event in signal initiation of immune cells. Trafficking of TLR4 to lipid rafts in response to LPS was reactive oxygen species (ROS) dependent because it was inhibited by diphenylene iodonium, an inhibitor of NADPH oxidase, and in gp91phox-deficient macrophages. CO selectively inhibited ligand-induced recruitment of TLR4 to lipid rafts, which was also associated with the inhibition of ligand-induced ROS production in macrophages. TLR3 did not translocate to lipid rafts by polyinosine-polycytidylic acid (poly(I:C)). CO had no effect on poly(I:C)-induced ROS production and TLR3 signaling. The inhibitory effect of CO on TLR-induced cytokine production was abolished in gp91phox-deficient macrophages, also indicating a role for NADPH oxidase. CO attenuated LPS-induced NADPH oxidase activity in vitro, potentially by binding to gp91phox. Thus, CO negatively controlled TLR signaling pathways by inhibiting translocation of TLR to lipid rafts through suppression of NADPH oxidase–dependent ROS generation.
These findings indicate that the expression of HO-1 in the ischemic kidney may be critical in the recovery of renal cell function in this animal model. These findings also suggest that H0-1 induction may play an important role in conferring protection on renal cells from oxidative damage caused by heme.
lung injury is a major concern in critically ill patients who receive high concentrations of oxygen to treat lung diseases. Successful abrogation of hyperoxic lung injury would have a huge impact on respiratory and critical care medicine. Hydrogen can be administered as a therapeutic medical gas. We recently demonstrated that inhaled hydrogen reduced transplant-induced lung injury and induced heme oxygenase (HO)-1. To determine whether hydrogen could reduce hyperoxic lung injury and investigate the underlying mechanisms, we randomly assigned rats to four experimental groups and administered the following gas mixtures for 60 h: 98% oxygen (hyperoxia), 2% nitrogen; 98% oxygen (hyperoxia), 2% hydrogen; 98% balanced air (normoxia), 2% nitrogen; and 98% balanced air (normoxia), 2% hydrogen. We examined lung function by blood gas analysis, extent of lung injury, and expression of HO-1. We also investigated the role of NF-E2-related factor (Nrf) 2, which regulates HO-1 expression, by examining the expression of Nrf2-dependent genes and the ability of hydrogen to reduce hyperoxic lung injury in Nrf2-deficient mice. Hydrogen treatment during exposure to hyperoxia significantly improved blood oxygenation, reduced inflammatory events, and induced HO-1 expression. Hydrogen did not mitigate hyperoxic lung injury or induce HO-1 in Nrf2-deficient mice. These findings indicate that hydrogen gas can ameliorate hyperoxic lung injury through induction of Nrf2-dependent genes, such as HO-1. The findings suggest a potentially novel and applicable solution to hyperoxic lung injury and provide new insight into the molecular mechanisms and actions of hydrogen.
Oxidative stresses such as oxidant stimuli, inflammation, exposure to xenobiotics, or ionizing irradiation provoke cellular protective responses, principally involving transcriptional activation of genes encoding proteins which participate in the defense against oxidative tissue injuries. Excess of free heme, which is released from hemeproteins under such conditions, may constitute a major threat because it can catalyze the formation of reactive oxygen species (ROS). Exposure of mammalian cells to oxidative stimuli induces heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, as well as a 33-kDa heat shock protein. In various model systems, HO-1 induction confers protection on tissues from further injuries, while the abrogation of its induction accelerates cellular injuries. In this article, we review recent advances in the regulatory mechanism of ho-1 gene expression and the role of HO-1 in various models of experimental oxidative tissue injuries, and its potential therapeutic implications.
This overview was directed towards understanding the relationship of brain functions with dietary choices mainly by older humans. This included food color, flavor, and aroma, as they relate to dietary sufficiency or the association of antioxidants with neurodegenerative diseases such as dementia and Alzheimer’s disease. Impairment of olfactory and gustatory function in relation to these diseases was also explored. The role of functional foods was considered as a potential treatment of dementia and Alzheimer’s disease through inhibition of acetylcholinesterase as well as similar treatments based on herbs, spices and antioxidants therein. The importance of antioxidants for maintaining the physiological functions of liver, kidney, digestive system, and prevention of cardiovascular diseases and cancer has also been highlighted. Detailed discussion was focused on health promotion of the older person through the frequency and patterns of dietary intake, and a human ecology framework to estimate adverse risk factors for health. Finally, the role of the food industry, mass media, and apps were explored for today’s new older person generation.
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