Inhibition of cAMP/PKA Pathway Protects Optic Nerve Head Astrocytes against Oxidative Stress by Akt/Bax Phosphorylation-Mediated Mfn1/2 Oligomerization.

Glaucoma is characterized by a progressive optic nerve degeneration and retinal ganglion cell loss, but the underlying biological basis for the accompanying neurodegeneration is not known. Accumulating evidence indicates that structural and functional abnormalities of astrocytes within the optic nerve head (ONH) have a role in glaucomatous neurodegeneration. Here, we investigate the impact of activation of cyclic adenosine 3',5'-monophosphate (cAMP)/protein kinase A (PKA) pathway on mitochondrial dynamics of ONH astrocytes exposed to oxidative stress. ONH astrocytes showed a significant loss of astrocytic processes in the glial lamina of glaucomatous DBA/2J mice, accompanied by basement membrane thickening and collagen deposition in blood vessels and axonal degeneration. Serial block-face scanning electron microscopy data analysis demonstrated that numbers of total and branched mitochondria were significantly increased in ONH astrocytes, while mitochondrial length and volume density were significantly decreased. We found that hydrogen peroxide- (H2O2-) induced oxidative stress compromised not only mitochondrial bioenergetics by reducing the basal and maximal respiration but also balance of mitochondrial dynamics by decreasing dynamin-related protein 1 (Drp1) protein expression in rat ONH astrocytes. In contrast, elevated cAMP by dibutyryl-cAMP (dbcAMP) or isobutylmethylxanthine treatment significantly increased Drp1 protein expression in ONH astrocytes. Elevated cAMP exacerbated the impairment of mitochondrial dynamics and reduction of cell viability to oxidative stress in ONH astrocytes by decreasing optic atrophy type 1 (OPA1), and mitofusin (Mfn)1/2 protein expression. Following combined treatment with H2O2 and dbcAMP, PKA inhibition restored mitochondrial dynamics by increasing mitochondrial length and decreasing mitochondrial number, and this promoted cell viability in ONH astrocytes. Also, PKA inhibition significantly promoted Akt/Bax phosphorylation and Mfn1/2 oligomerization in ONH astrocytes. These results suggest that modulation of the cAMP/PKA signaling pathway may have therapeutic potential by activating Akt/Bax phosphorylation and promoting Mfn1/2 oligomerization in glaucomatous ONH astrocytes

Gut microbiota, its role in induction of Alzheimer’s disease pathology, and possible therapeutic interventions: Special focus on anthocyanins

The human gut is a safe environment for several microbes that are symbiotic and important for the wellbeing of human health. However, studies on gut microbiota in different animals have suggested that changes in the composition and structure of these microbes may promote gut inflammation by releasing inflammatory cytokines and lipopolysaccharides, gut-wall leakage, and may affect systemic inflammatory and immune mechanisms that are important for the normal functioning of the body. There are many factors that aid in the gut’s dysbiosis and neuroinflammation, including high stress levels, lack of sleep, fatty and processed foods, and the prolonged use of antibiotics. These neurotoxic mechanisms of dysbiosis may increase susceptibility to Alzheimer’s disease (AD) and other neurodegenerative conditions. Therefore, studies have recently been conducted to tackle AD-like conditions by specifically targeting gut microbes that need further elucidation. It was suggested that gut dyshomeostasis may be regulated by using available options, including the use of flavonoids such as anthocyanins, and restriction of the use of high-fatty-acid-containing food. In this review, we summarize the gut microbiota, factors promoting it, and possible therapeutic interventions especially focused on the therapeutic potential of natural dietary polyflavonoid anthocyanins. Our study strongly suggests that gut dysbiosis and systemic inflammation are critically involved in the development of neurodegenerative disorders, and the natural intake of these flavonoids may provide new therapeutic opportunities for preclinical or clinical studies

Multi-Color Luminescence Transition of Upconversion Nanocrystals via Crystal Phase Control with SiO2 for High Temperature Thermal Labels

Upconversion nanocrystals (UCNs)-embedded microarchitectures with luminescence color transition capability and enhanced luminescence intensity under extreme conditions are suitable for developing a robust labeling system in a high-temperature thermal industrial process. However, most UCNs based labeling systems are limited by the loss of luminescence owing to the destruction of the crystalline phase or by a predetermined luminescence color without color transition capability. Herein, an unusual crystal phase transition of UCNs to a hexagonal apatite phase in the presence of SiO2 nanoparticles is reported with the enhancements of 130-fold green luminescence and 52-fold luminance as compared to that of the SiO2-free counterpart. By rationally combining this strategy with an additive color mixing method using a mask-less flow lithography technique, single to multiple luminescence color transition, scalable labeling systems with hidden letters-, and multi-luminescence colored microparticles are demonstrated for a UCNs luminescence color change-based high temperature labeling system

Enhancement of phase separation in the InGaN layer for self-assembled In-rich quantum dots

The enhancement of phase separation in the InGaN layer grown on a GaN layer with a rough surface was investigated for the formation of self-assembled In-rich quantum dots(QDs) in the InGaN layer. Transmission electron microscopy images showed that In-rich QDs with a size of 2–5 nm were formed even in an InGaN layer with a low indium content, and a layer thickness less than the critical thickness. The room-temperature photoluminescence(PL) spectrum of this layer showed emission peaks corresponding to In-rich QDs. The temperature-dependent PL spectra showed dominant peak shifts to the lower energy side, indicating that the self-assembled In-rich QDs are formed in the InGaN layer grown on a rough GaNsurface and that the carriers are localized in In-rich QDs