Large-Scale Analysis of Defects in Atomically Thin Semiconductors using Hyperspectral Line Imaging.

Point defects play a crucial role in determining the properties of atomically thin semiconductors. This work demonstrates the controlled formation of different types of defects and their comprehensive optical characterization using hyperspectral line imaging (HSLI). Distinct optical responses are observed in monolayer semiconductors grown under different stoichiometries using metal-organic chemical vapor deposition. HSLI enables the simultaneous measurement of 400 spectra, allowing for statistical analysis of optical signatures at close to a centimeter scale. The study discovers that chalcogen-rich samples exhibit remarkable optical uniformity due to reduced precursor accumulation compared to the metal-rich case. The utilization of HSLI as a facile and reliable characterization tool pushes the boundaries of potential applications for atomically thin semiconductors in future devices.

Di-n-butyl phthalate disrupts neuron maturation in primary rat embryo neurons and male C57BL/6 mice.

Di-n-butyl phthalate (DBP) is commonly used as a plasticizer and its usage continues to increase in conjunction with plastic consumption. DBP is readily released into air, drinking water, and soil, and unfortunately, is a potent endocrine disrupter that impairs central nervous system functions. Previously DBP was found to (1) arrest the cell cycle of C17.2 neural progenitor cells (NPCs) at the G1 phase, (2) reduce numbers of newly generated neural stem cells in the mouse hippocampus, and (3) adversely affect learning and memory. Other investigators also noted DBP-mediated neurotoxic effects, but as yet, no study has addressed the adverse effects of DBP on neuronal differentiation. Data demonstrated that at 200 µM DBP induced apoptosis in rat embryo primary neurons by increasing reactive oxygen species levels and inducing mitochondrial dysfunction. However, no significant effect was detected on neurons at concentrations of ≤100 µM. In contrast, doublecortin/microtubule associated protein-2 (DCX/MAP2) immunocytochemistry showed that DBP at 100 µM delayed neuronal maturation by increasing protein levels of DCX (an immature neuronal marker), without markedly affecting cell viability. Further in vivo studies confirmed that DCX+ cell numbers were significantly elevated in the hippocampus of DBP-treated mice, indicating that DBP delayed neuronal maturation, which is known to be associated with impaired memory retention. Data demonstrated that DBP might disrupt neuronal maturation, which is correlated with reduced neurocognitive functions.

Anti-Inflammatory Effect of IKK-Activated GSK-3ß Inhibitory Peptide Prevented Nigrostriatal Neurodegeneration in the Rodent Model of Parkinson's Disease.

Parkinson's disease (PD) is a progressive movement disorder caused by nigrostriatal neurodegeneration. Since chronically activated neuroinflammation accelerates neurodegeneration in PD, we considered that modulating chronic neuroinflammatory response might provide a novel therapeutic approach. Glycogen synthase kinase 3 (GSK-3) is a multifunctional serine/threonine protein kinase with two isoforms, GSK-3α and GSK-3ß, and GSK-3ß plays crucial roles in inflammatory response, which include microglial migration and peripheral immune cell activation. GSK-3ß inhibitory peptide (IAGIP) is specifically activated by activated inhibitory kappa B kinase (IKK), and its therapeutic effects have been demonstrated in a mouse model of colitis. Here, we investigated whether the anti-inflammatory effects of IAGIP prevent neurodegeneration in the rodent model of PD. IAGIP significantly reduced MPP+-induced astrocyte activation and inflammatory response in primary astrocytes without affecting the phosphorylations of ERK or JNK. In addition, IAGIP inhibited LPS-induced cell migration and p65 activation in BV-2 microglial cells. In vivo study using an MPTP-induced mouse model of PD revealed that intravenous IAGIP effectively prevented motor dysfunction and nigrostriatal neurodegeneration. Our findings suggest that IAGIP has a curative potential in PD models and could offer new therapeutic possibilities for targeting PD.

Anti-Inflammatory and Neuroprotective Effects of Morin in an MPTP-Induced Parkinson's Disease Model.

Neurodegenerative diseases such as Parkinson's disease (PD) are known to be related to oxidative stress and neuroinflammation, and thus, modulating neuroinflammation offers a possible means of treating PD-associated pathologies. Morin (2',3,4',5,7-pentahydroxy flavone) is a flavonol with anti-oxidative and anti-inflammatory effects found in wines, herbs, and fruits. The present study was undertaken to determine whether a morin-containing diet has protective effects in an MPTP-induced mouse model of PD. Mice were fed a control or morin diet for 34 days, and then MPTP (30 mg/kg, i.p.) was administered daily for 5 days to induce a PD-like pathology. We found that dietary morin prevented MPTP-induced motor dysfunction and ameliorated dopaminergic neuronal damage in striatum (STR) and substantia nigra (SN) in our mouse model. Furthermore, MPTP-induced neuroinflammation was significantly reduced in mice fed morin. In vitro studies showed that morin effectively suppressed glial activations in primary microglia and astrocytes, and biochemical analysis and a docking simulation indicated that the anti-inflammatory effects of morin were mediated by blocking the extracellular signal-regulated kinase (ERK)-p65 pathway. These findings suggest that morin effectively inhibits glial activations and has potential use as a functional food ingredient with therapeutic potential for the treatment of PD and other neurodegenerative diseases associated with neuroinflammation.

Neuroprotective and Anti-Inflammatory Effects of Evernic Acid in an MPTP-Induced Parkinson's Disease Model.

Oxidative stress, mitochondrial dysfunction, and neuroinflammation are strongly associated with the pathogenesis of Parkinson's disease (PD), which suggests that anti-oxidative and anti-inflammatory compounds might provide an alternative treatment for PD. Here, we evaluated the neuroprotective effects of evernic aid (EA), which was screened from a lichen library provided by the Korean Lichen Research Institute at Sunchon National University. EA is a secondary metabolite generated by lichens, including Ramalina, Evernia, and Hypogymnia, and several studies have described its anticancer, antifungal, and antimicrobial effects. However, the neuroprotective effects of EA have not been studied. We found that EA protected primary cultured neurons against 1-methyl-4-phenylpyridium (MPP+)-induced cell death, mitochondrial dysfunction, and oxidative stress, and effectively reduced MPP+-induced astroglial activation by inhibiting the NF-κB pathway. In vivo, EA ameliorated MPTP-induced motor dysfunction, dopaminergic neuronal loss, and neuroinflammation in the nigrostriatal pathway in C57BL/6 mice. Taken together, our findings demonstrate that EA has neuroprotective and anti-inflammatory effects in PD models and suggest that EA is a potential therapeutic candidate for PD.

Glutamate oxidase sheets-Prussian blue grafted amperometric biosensor for the real time monitoring of glutamate release from primary cortical neurons.

Glutamate (GLU) is a primary excitatory neurotransmitter, and its dysregulation is associated with several neurodegenerative disorders. A major challenge in GLU estimation is the existence of other biomolecules in the brain that could directly get oxidized at the electrode. Hence, highly selective electroenzymatic biosensors that enable rapid estimation of GLU are needed. Initially, a copolymer, poly(2-dimethylaminoethyl methacrylate- styrene) was synthesized through reversible addition-fragmentation chain transfer polymerization to noncovalently functionalize reduced graphene oxide (rGO), named DS-rGO. Glutamate oxidase macromolecule immobilized DS-rGO formed enzyme nanosheets, which was drop-coated over Prussian blue electrodeposited disposable electrodes to fabricate the GLU biosensor. The interconnectivity between the enzyme nanosheets and the Prussian blue endows the biosensor with enhanced conductivity and electrochemical activity. The biosensor exhibited a linearity: 3.25-250 µM; sensitivity: 3.96 µA mM-1 cm-2, and a limit of detection: 0.96 µM for GLU in the Neurobasal Medium. The biosensor was applied to an in vitro primary rat cortical model to discriminate GLU levels in Neurobasal Medium, before and after KCl mediated depolarization, which provides new insights for elucidating neuronal functioning in the brain.

Amelioration of Astrocyte-Mediated Neuroinflammation by EI-16004 Confers Neuroprotection in an MPTP-induced Parkinson's Disease Model.

Parkinson's disease (PD) is a neurodegenerative disorder that results in motor impairment due to dopaminergic neuronal loss. The pathology of PD is closely associated with neuroinflammation, which can be characterized by astrocyte activation. Thus, targeting the inflammatory response in astrocytes might provide a novel therapeutic approach. We conducted a luciferase assay on an in-house chemical library to identify compounds with anti-inflammatory effects capable of reducing MPP+-induced NF-κB activity in astrocytes. Among the compounds identified, EI-16004, a novel 3-benzyl-N-phenyl-1H-pyrazole-5-carboxamides, exhibited a significant anti-inflammatory effect by significantly reducing MPP+-induced astrocyte activation. Biochemical analysis and docking simulation indicated that EI-16004 inhibited the MPP+-induced phosphorylation of p65 by attenuating ERK phosphorylation, and EI-16004 reduced pro-inflammatory cytokine and chemokine levels in astrocytes. In vivo studies on the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model in male C57BL/6 mice showed that EI-16004 ameliorated motor impairment and protected against dopaminergic neuronal loss, and EI-16004 effectively mitigated the MPTP-induced astrocyte activation in striatum (STR) and substantia nigra (SN). These results indicate EI-16004 is a potential neuroprotective agent for the prevention and treatment of astrocyte-mediated neuroinflammatory conditions in PD.

Low-dose curcumin enhances hippocampal neurogenesis and memory retention in young mice.

Adult neurogenesis generates new functional neurons from adult neural stem cells in various regions, including the subventricular zone (SVZ) of the lateral ventricles and subgranular zone (SGZ) of hippocampal dentate gyrus (DG). Available evidence shows hippocampal neurogenesis can be negatively or positively regulated by dietary components. In a previous study, we reported that curcumin (diferuloylmethane; a polyphenolic found in curry spice) stimulates the proliferation of embryonic neural stem cells (NSCs) by activating adaptive cellular stress responses. Here, we investigated whether subchronic administration of curcumin (once daily at 0.4, 2, or 10 mg/kg for 14 days) promotes hippocampal neurogenesis and neurocognitive function in young (5-week-old) mice. Oral administration of low-dose curcumin (0.4 mg/kg) increased the proliferation and survival of newly generated cells in hippocampus, but surprisingly, high-dose curcumin (10 mg/kg) did not effectively upregulate the proliferation or survival of newborn cells. Furthermore, hippocampal BDNF levels and phosphorylated CREB activity were elevated in only low-dose curcumin-treated mice. Passive avoidance testing revealed that low-dose curcumin increased cross-over latency times, indicating enhanced memory retention, and an in vitro study showed that low-concentration curcumin increased the proliferative activity of neural progenitor cells (NPCs) by upregulating NF1X levels. Collectively, our findings suggest that low-dose curcumin has neurogenic effects and that it may prevent age and neurodegenerative disease-related cognitive deficits.

Glucocorticoid Receptor Down-Regulation Affects Neural Stem Cell Proliferation and Hippocampal Neurogenesis.

Dysregulation of the hypothalamic-pituitary-adrenal axis and abnormalities in the glucocorticoid receptor (GR) have been linked to major depressive disorder. Given the critical role of GR in stress response regulation, we investigated the impact of GR changes on neural stem cells (NSCs) proliferation and hippocampal neurogenesis. Stress response was induced using dexamethasone (DEX), a GR agonist, which led to reduced proliferation of neural stem cells and neural progenitor cells, as well as decreased expression of GR. Additionally, a reduction of serum concentration within the culture media resulted in suppressed cell proliferation, accompanied by decreased GR expression. The association between GR expression and cell proliferation was further confirmed through GR siRNA knockdown and overexpression experiments. Furthermore, in vivo studies utilizing young male C57BL/6 mice demonstrated that corticosterone (CORT) (35 µg/ml) administered through drinking water for four weeks induced depression-like behavior, as indicated by increased immobility times in forced swimming and tail suspension tests. CORT exposure led to reduced GR and nestin expression levels, along with diminished numbers of BrdU-positive cells in the hippocampi, indicating impaired hippocampal neurogenesis. Taken together, our findings provide the first evidence that stress-induced downregulation of GR negatively affects neurogenesis by inhibiting NSCs proliferation.

Cationic nanoplastic causes mitochondrial dysfunction in neural progenitor cells and impairs hippocampal neurogenesis.

Nanoplastics (NPs) exposure to humans can occur through various routes, including the food chain, drinking water, skin contact, and respiration. NPs are plastics with a diameter of less than 100 nm and have the potential to accumulate in tissues, leading to toxic effects. This study aimed to investigate the neurotoxicity of polystyrene NPs on neural progenitor cells (NPCs) and hippocampal neurogenesis in a rodent model. Toxicity screening of polystyrene NPs based on their charge revealed that cationic amine-modified polystyrene (PS-NH3+) exhibited cytotoxicity, while anionic carboxylate-modified polystyrene (PS-COO-) and neutral NPs (PS) did not. NPCs treated with PS-NH3+ showed a significant reduction in growth rate due to G1 cell cycle arrest. PS-NH3+ increased the expression of cell cycle arrest markers p21 and p27, while decreasing cyclin D expression in NPCs. Interestingly, PS-NH3+ accumulated in mitochondria, leading to mitochondrial dysfunction and energy depletion, which caused G1 cell cycle arrest. Prolonged exposure to PS-NH3+ in C17.2 NPCs increased the expression of p16 and senescence-associated secretory phenotype factors, indicating cellular senescence. In vivo studies using C57BL/6 mice demonstrated impaired hippocampal neurogenesis and memory retention after 10 days of PS-NH3+ administration. This study suggests that NPs could deplete neural stem cell pools in the brain by mitochondrial dysfunction, thereby adversely affecting hippocampal neurogenesis and neurocognitive functions.

Anti-Inflammatory Effects of the Novel Barbiturate Derivative MHY2699 in an MPTP-Induced Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders, and is caused by the death of dopamine neurons and neuroinflammation in the striatum and substantia nigra. Furthermore, the inflammatory response in PD is closely related to glial cell activation. This study examined the neuroprotective effects of the barbiturate derivative, MHY2699 [5-(4-hydroxy 3,5-dimethoxybenzyl)-2 thioxodihydropyrimidine-4,6(1H,5H)-dione] in a mouse model of PD. MHY2699 ameliorated MPP⁺-induced astrocyte activation and ROS production in primary astrocytes and inhibited the MPP⁺-induced phosphorylation of MAPK and NF-κB. The anti-inflammatory effects of MHY2699 in protecting neurons were examined in an MPTP-induced mouse model of PD. MHY2699 inhibited MPTP-induced motor dysfunction and prevented dopaminergic neuronal death, suggesting that it attenuated neuroinflammation. Overall, MHY2699 has potential as a neuroprotective treatment for PD.

Tetrabromobisphenol A-Induced Apoptosis in Neural Stem Cells Through Oxidative Stress and Mitochondrial Dysfunction.

Tetrabromobisphenol A (TBBPA) is widely used in materials like plastics and textiles as a fire retardant. In a previous study, we reported TBBPA might disrupt hippocampal neurogenesis and neurocognitive function in mice. However, the mechanism responsible for these effects has not been established. The present study was undertaken to investigate the potential involvement of oxidative stress and mitochondrial dysfunction in TBBPA-mediated neurotoxicity in neural stem cells. We confirmed TBBPA was more cytotoxic to neural stem cells than to neurons, astrocytes, or fibroblasts, and found that TBBPA-induced neural stem cell apoptosis was accompanied by increased reactive oxygen species generation and mitochondrial dysfunction. At a molecular level, TBBPA-induced apoptosis was determined to be mediated by c-Jun N-terminal kinase-p53 pathway activation. Taken together, these findings suggest that the adverse effects of TBBPA on hippocampal neurogenesis are due to the inhibition of neural stem cell expansion.