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Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Distributed dysconnectivity within both the default-mode network (DMN) and the salience network (SN) has been observed in ADHD. L-cystine may serve as a neuroprotective molecule and signaling pathway, as well as a biomarker of ADHD. The purpose of this study was to explore whether differential brain network connectivity is associated with peripheral L-cystine levels in ADHD patients. Tathion We recruited a total of 31 drug-naïve patients with ADHD (mean age 10.4 years) and 29 healthy controls (mean age 10.3 years) that underwent resting state functional magnetic resonance imaging scans. Functional connectomes were generated for each subject, and we examined the cross-sectional group difference in functional connectivity (FC) within and between DMN and SN. L-cystine plasma levels were determined using high-performance chemical isotope labeling (CIL)-based liquid chromatography-mass spectrometry (LC-MS). Compared to the control group, the ADHD group showed decreased FC of dorsal DMN (p = 0.031), as well as decreased FC of precuneus-post SN (p = 0.006) and ventral DMN-post SN (p = 0.001). The plasma L-cystine levels of the ADHD group were significantly higher than in the control group (p = 0.002). Furthermore, L-cystine levels were negatively correlated with FC of precuneus-post SN (r = -0.404, p = 0.045) and ventral DMN-post SN (r = -0.540, p = 0.007). The findings suggest that decreased synergies of DMN and SN may serve as neurobiomarkers for ADHD, while L-cystine may be involved in the pathophysiology of network dysconnectivity. Future studies on the molecular mechanism of the cystine-glutamate system in brain network connectivity are warranted.Dietary proanthocyanidins (PAC) consumption is associated with a decreased risk for colorectal cancer (CRC). Dysregulation of the epidermal growth factor (EGF) receptor (EGFR) signaling pathway is frequent in human cancers, including CRC. We previously showed that hexameric PAC (Hex) exert anti-proliferative and pro-apoptotic actions in human CRC cells. This work investigated if Hex could exert anti-CRC effects through its capacity to regulate the EGFR pathway. In proliferating Caco-2 cells, Hex acted attenuating EGF-induced EGFR dimerization and NADPH oxidase-dependent phosphorylation at Tyr 1068, decreasing EGFR location at lipid rafts, and inhibiting the downstream activation of pro-proliferative and anti-apoptotic pathways, i.e. Raf/MEK/ERK1/2 and PI3K/Akt. Hex also promoted EGFR internalization both in the absence and presence of EGF. While Hex decreased EGFR phosphorylation at Tyr 1068, it increased EGFR Tyr 1045 phosphorylation. The latter provides a docking site for the ubiquitin ligase c-Cbl and promotes EGFR degradation by lysosomes. Importantly, Hex acted synergistically with the EGFR-targeted chemotherapeutic drug Erlotinib, both in their capacity to decrease EGFR phosphorylation and inhibit cell growth. Thus, dietary PAC could exert anti-CRC actions by modulating, through both redox- and non-redox-regulated mechanisms, the EGFR pro-oncogenic signaling pathway. Additionally, Hex could also potentiate the actions of EGFR-targeted drugs.Disulfide bonds play a key function in determining the structure of proteins, and are the most strongly conserved compositional feature across proteomes. They are particularly common in extracellular environments, such as the extracellular matrix and plasma, and in proteins that have structural (e.g. matrix) or binding functions (e.g. receptors). Recent data indicate that disulfides vary markedly with regard to their rate of reaction with two-electron oxidants (e.g. HOCl, ONOOH), with some species being rapidly and readily oxidized. These reactions yielding thiosulfinates that can react further with a thiol to give thiolated products (e.g. glutathionylated proteins with glutathione, GSH). Here we show that these 'oxidant-mediated thiol-disulfide exchange reactions' also occur during photo-oxidation reactions involving singlet oxygen (1O2). Reaction of protein disulfides with 1O2 (generated by multiple sensitizers in the presence of visible light and O2), yields reactive intermediates, probably zwitterionic peroxyl adducts or thiosulfinates. Subsequent exposure to GSH, at concentrations down to 2 μM, yields thiolated adducts which have been characterized by both immunoblotting and mass spectrometry. The yield of GSH adducts is enhanced in D2O buffers, and requires the presence of the disulfide bond. This glutathionylation can be diminished by non-enzymatic (e.g. tris-(2-carboxyethyl)phosphine) and enzymatic (glutaredoxin) reducing systems. Photo-oxidation of human plasma and subsequent incubation with GSH yields similar glutathionylated products with these formed primarily on serum albumin and immunoglobulin chains, demonstrating potential in vivo relevance. These reactions provide a novel pathway to the formation of glutathionylated proteins, which are widely recognized as key signaling molecules, via photo-oxidation reactions.Vascular calcification is a common pathological feature of atherosclerosis, chronic kidney disease, vascular injury, and aging. Liver kinase B1 (LKB1) plays pivotal roles in cellular processes such as apoptosis, metabolism, and cell cycle regulation. In addition, growing evidence has indicated that LKB1 functions as a tumor suppressor gene. However, its role in vascular calcification has not been reported. LKB1flox/flox mice were hybridized with SM22-CreERT2 transgenic mice and adult mice received tamoxifen to obtain smooth muscle-specific LKB1-knockout (LKB1SMKO) mice. LKB1 expression was decreased under calcifying conditions, and LKB1 overexpression had a protective effect on vascular calcification. However, high mobility group box 1 (HMGB1) overexpression partially counteracted the promotion of vascular calcification induced by LKB1 overexpression. Mechanically, LKB1 could bind to HMGB1 to promote HMGB1 degradation. Furthermore, LKB1SMKO mice showed intensified vascular calcification, which was alleviated by treatment with the HMGB1 inhibitor glycyrrhizic acid. Based on our results, LKB1 may inhibit vascular calcification via inhibiting HMGB1 expression.
Read More: https://www.selleckchem.com/products/glutathione.html
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