5,380 research outputs found
Jordan's Inequality: Refinements, Generalizations, Applications and Related Problems
No full textThis is an expository article. Some developments on refinements,
generalizations, applications of Jordan’s inequality and related problems, including
some estimates for three classes of complete elliptic integrals and several
proofs of Wilker’s inequality, are summarized
Some New Bounds for Mathieu's Series
No full textIn the paper, an upper bound and two lower bounds for Mathieu’s
series are established, which refine to a certain extent a sharp double inequality
obtained by Alzer-Brenner-Ruehr in 1998. Moreover, the very closer lower and
upper bounds for ζ(3) are deduced
On New Proofs of Inequalities Involving Trigonometric Functions
No full textIn the note, some new proofs for inequalities invoving trigonometric functions are given
Wellesly Sh. W. to Mr. James Meredith (2 October 1962)
No full textSigned by Wellesly Sh. W.https://egrove.olemiss.edu/mercorr_pro/1531/thumbnail.jp
Mode of Action of Toxin 6-Hydroxydopamine in SH-SY5Y Using NMR Metabolomics
No full textThis study used NMR-based metabolomics to investigate the mode of action (MoA) of 6-hydroxydopamine (6-OHDA) toxicity in the SH-SY5Y neuroblastoma cell model. 6-OHDA, a structural analogue of dopamine, has been used to create a Parkinson’s disease model since 1968. Its selective uptake via catecholaminergic transporters leads to intracellular oxidative stress and mitochondrial dysfunction. SH-SY5Y cells were treated with 6-OHDA at its IC50 concentration of 60 μM, and samples of treated and untreated groups were collected after 24 h. The endo metabolome was extracted using a methanol–water mixture, while the exo metabolome was represented by the culture media. Further, endo- and exo metabolomes of treated and untreated cells were analysed for metabolic changes. Our results demonstrated significantly high levels of glutathione, acetate, propionate, and NAD+, which are oxidative stress markers, enhanced due to ROS production in the system. In addition, alteration of myoinositol, taurine, and o-phosphocholine could be due to oxidative stress-induced membrane potential disturbance. Mitochondrial complex I inhibition causes electron transport chain (ETC) dysfunction. Changes in key metabolites of glycolysis and energy metabolism, such as glucose, pyruvate, lactate, creatine, creatine phosphate, glycine, and methionine, respectively, demonstrated ETC dysfunction. We also identified changes in amino acids such as glutamine, glutamate, and proline, followed by nucleotide metabolism such as uridine and uridine monophosphate levels, which were decreased in the treated group.Full Tex
Fig. 1 in Phenolics from Archidendron clypearia (Jack) I.C.Nielsen protect SH-SY5Y cells against H O -induced oxidative stress
No full textFig. 1. The structures of compounds 1–18.Published as part of Wang, Yu-Xi, Han, Feng-Ying, Duan, Zhi-Kang, Chang, Ye, Lin, Bin, Wang, Xiao-Bo, Huang, Xiao-Xiao, Yao, Guo-Dong & Song, Shao-Jiang, 2020, Phenolics from Archidendron clypearia (Jack) I.C.Nielsen protect SH-SY5Y cells against H O -induced oxidative stress, pp. 1-8 in Phytochemistry (112414) 176 on page 2, DOI: 10.1016/j.phytochem.2020.112414, http://zenodo.org/record/829568
SMA-SH: Modified styrene maleic acid copolymer for functionalization of lipid nanodiscs
No full textChallenges in purification and subsequent functionalization of membrane proteins often complicate their biochemical and biophysical characterization. Purification of membrane proteins generally involves replacing the lipids surrounding the protein with detergent molecules, which can affect protein structure and function. Recently, it was shown that styrene–maleic acid copolymers (SMA) can dissolve integral membrane proteins from biological membranes into nanosized discs. Within these nanoparticles, proteins are embedded in a patch of their native lipid bilayer that is stabilized in solution by the amphipathic polymer that wraps the disc like a bracelet. This approach for detergent-free purification of membrane proteins has the potential to greatly simplify purification but does not facilitate conjugation of functional compounds to the membrane proteins. Often, such functionalization involves laborious preparation of protein variants and optimization of labeling procedures to ensure only minimal perturbation of the protein. Here, we present a strategy that circumvents several of these complications through modifying SMA by grafting the polymer with cysteamine. The reaction results in SMA that has solvent-exposed sulfhydrils (SMA-SH) and allows tuning of the coverage with SH groups. Size exclusion chromatography, dynamic light scattering, and transmission electron microscopy demonstrate that SMA-SH dissolves lipid bilayer membranes into lipid nanodiscs, just like SMA. In addition, we demonstrate that, just like SMA, SMA-SH solubilizes proteoliposomes into protein-loaded nanodiscs. We covalently modify SMA-SH-lipid nanodiscs using thiol-reactive derivatives of Alexa Fluor 488 and biotin. Thus, SMA-SH promises to simultaneously tackle challenges in purification and functionalization of membrane proteins.BN/Marie-Eve Aubin-Tam LabBN/Andreas Engel La
Omega-3 fatty acid eicospentaenoic acid attenuates MPP+-induced neurodegeneration in fully differentiated human SH- SY5Y and primary mesencephalic cells
No full textEicosapentaenoic acid ( EPA), a neuroactive omega-3 fatty acid, has been demonstrated to exert neuroprotective effects in experimental models of Parkinson's disease ( PD), but the cellular mechanisms of protection are unknown. Here, we studied the effects of EPA in fully differentiated human SH-SY5Y cells and primary mesencephalic neurons treated with MPP+. In both in-vitro models of PD, EPA attenuated an MPP+-induced reduction in cell viability. EPA also prevented the presence of electron-dense cytoplasmic inclusions in SH-SY5Y cells. Then, possible mechanisms of the neuroprotection were studied. In primary neurons, EPA attenuated an MPP+-induced increase in Tyrosine-related kinase B (TrkB) receptors. In SH-SY5Y cells, EPA down-regulated reactive oxygen species and nitric oxide. This antioxidant effect of EPA may have been mediated by its inhibition of neuronal NADPH oxidase and cyclo-oxygenase-2 ( COX-2), as MPP+ increased the expression of these enzymes. Furthermore, EPA prevented an increase in cytosolic phospholipase A2 ( cPLA2), an enzyme linked with COX-2 in the potentially pro-inflammatory arachidonic acid cascade. Lastly, EPA attenuated an increase in the bax:bcl-2 ratio, and cytochrome c release. However, EPA did not prevent mitochondrial enlargement or a decrease in mitochondrial membrane potential. This study demonstrated cellular mechanisms by which EPA provided neuroprotective effects in experimental P
A shrunken edge algorithm for contact detection between convex polyhedral blocks
No full textThe detection of contacts between interacting blocks is an important but time-consuming calculation in discontinuity-based numerical methods. This paper presents a new algorithm for the detection of contacts between arbitrary convex polyhedra with planar boundaries. In this algorithm, a pair of contacting blocks is identified as a main block and a target block. The concept of a shrunken edge is introduced in this paper. First, each vertex of the main block is shrunk toward the centre of the neighbouring faces. The shrinkage is infinitesimal yet useful for contact detection. Shrunken edges parallel to the original edges on the main block are established by connecting the shrunken points. Contact detection is then performed by determining the geometric relationship between a shrunken edge and its approaching face on the target block. From the three possible geometric relationships, all six contact types in three dimensions can be identified precisely, which allows for an easy and efficient detection process. Finally, the accuracy and effectiveness of the new contact algorithm are demonstrated through several examples in which two or more blocks collide in a three-dimensional domain. (C) 2014 Elsevier Ltd. All rights reserved
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