The Experts below are selected from a list of 10299 Experts worldwide ranked by ideXlab platform
Pamela Maher - One of the best experts on this subject based on the ideXlab platform.
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a comparison of the neurotrophic activities of the flavonoid fisetin and some of its derivatives
Free Radical Research, 2006Co-Authors: Pamela MaherAbstract:Neurotrophic factors promote the development, maintenance and regeneration of Nerve Cells. Classical neurotrophic factors are proteins and thus not well-suited for therapeutic purposes. Recently, we showed that specific flavonoids such as fisetin (3, 7, 3', 4' tetrahydroxyflavone) promote the Differentiation of Nerve Cells in culture through the activation of extraCellular signal-regulated kinase (ERK) suggesting that flavonoids could substitute for neurotrophic factors. It has also been shown that fisetin promotes Nerve Cell survival following exposure to toxic oxidative insults. To determine whether or not this is unique to fisetin, a series of related compounds were assayed for neurotrophic activities. Many of these related compounds also promote Nerve Cell Differentiation and are neuroprotective against toxic oxidative insults. However, the mechanisms underlying these neurotrophic effects differ among the compounds.
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induction of pc12 Cell Differentiation by flavonoids is dependent upon extraCellular signal regulated kinase activation
Journal of Neurochemistry, 2004Co-Authors: Yutaka Sagara, Julie Vanhnasy, Pamela MaherAbstract:Many of the physiological benefits attributed to flavonoids are thought to stem from their potent antioxidant and free radical scavenging properties. Recently, it was shown that flavonoids protect Nerve Cells from oxidative stress by multiple mechanisms, only one of which is directly related to their antioxidant activity, suggesting that specific flavonoids may have other properties that could make them useful in the treatment of conditions that lead to Nerve Cell death. In particular, it was asked if any flavonoid could mimic neurotrophic proteins. To examine this possibility, we looked at the ability of flavonoids to induce Nerve Cell Differentiation using PC12 Cells. PC12 Cells were treated with a variety of flavonoids to determine if there was a correlation between their neuroprotective activity and their neurite outgrowth-promoting activity. In addition, the signaling pathways required for flavonoid-induced Differentiation were examined. We found that only a small subset of the flavonoids that were neuroprotective could induce neurite outgrowth by an extraCellular signal-regulated kinase-dependent process. There was a strong correlation between the concentrations of the flavonoids that were neuroprotective and the concentrations that induced Differentiation. These results suggest that the consumption of specific flavonoids could have further beneficial effects on Nerve Cells following injury, in pathological conditions or in normal aging.
Gordon G Wallace - One of the best experts on this subject based on the ideXlab platform.
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guidance of neurite outgrowth on aligned electrospun polypyrrole poly styrene β isobutylene β styrene fiber platforms
Journal of Biomedical Materials Research Part A, 2010Co-Authors: Xiao Liu, Kerry J Gilmore, Jun Chen, Michael J Higgins, Yong Liu, Gordon G WallaceAbstract:The purpose of this work was to investigate the potential biomedical application of novel aligned electrospun polypyrrole (PPy)/poly(styrene-β-isobutylene-β-styrene) (SIBS) fibers. After successfully aligning the electroactive PPy/SIBS fibers based on our modified electrospinning method, we demonstrated that neurite outgrowth from PC12 Cells could be highly orientated parallel to the aligned PPy/SIBS fibers. Physical interactions between the Nerve Cells and PPy/SIBS fibers through filopodia “sensing” were observed using atomic force microscopy. These observations indicate a role of contact guidance as a mechanism for the observed alignment. This work highlights the capacity for electroactive PPy/SIBS fibers to support and guide Nerve Cell Differentiation through topographic cues, which is a highly desirable characteristic in medical implants for neurological applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.
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electrical stimulation promotes Nerve Cell Differentiation on polypyrrole poly 2 methoxy 5 aniline sulfonic acid composites
Journal of Neural Engineering, 2009Co-Authors: Xiao Liu, Kerry J Gilmore, Simon E Moulton, Gordon G WallaceAbstract:The purpose of this work was to investigate for the first time the potential biomedical applications of novel polypyrrole (PPy) composites incorporating a large polyelectrolyte dopant, poly (2-methoxy-5 aniline sulfonic acid) (PMAS). The physical and electrochemical properties were characterized. The PPy/PMAS composites were found to be smooth and hydrophilic and have low electrical impedance. We demonstrate that PPy/PMAS supports Nerve Cell (PC12) Differentiation, and that clinically relevant 250 Hz biphasic current pulses delivered via PPy/PMAS films significantly promote Nerve Cell Differentiation in the presence of Nerve growth factor (NGF). The capacity of PPy/PMAS composites to support and enhance Nerve Cell Differentiation via electrical stimulation renders them valuable for medical implants for neurological applications.
Xiao Liu - One of the best experts on this subject based on the ideXlab platform.
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guidance of neurite outgrowth on aligned electrospun polypyrrole poly styrene β isobutylene β styrene fiber platforms
Journal of Biomedical Materials Research Part A, 2010Co-Authors: Xiao Liu, Kerry J Gilmore, Jun Chen, Michael J Higgins, Yong Liu, Gordon G WallaceAbstract:The purpose of this work was to investigate the potential biomedical application of novel aligned electrospun polypyrrole (PPy)/poly(styrene-β-isobutylene-β-styrene) (SIBS) fibers. After successfully aligning the electroactive PPy/SIBS fibers based on our modified electrospinning method, we demonstrated that neurite outgrowth from PC12 Cells could be highly orientated parallel to the aligned PPy/SIBS fibers. Physical interactions between the Nerve Cells and PPy/SIBS fibers through filopodia “sensing” were observed using atomic force microscopy. These observations indicate a role of contact guidance as a mechanism for the observed alignment. This work highlights the capacity for electroactive PPy/SIBS fibers to support and guide Nerve Cell Differentiation through topographic cues, which is a highly desirable characteristic in medical implants for neurological applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.
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electrical stimulation promotes Nerve Cell Differentiation on polypyrrole poly 2 methoxy 5 aniline sulfonic acid composites
Journal of Neural Engineering, 2009Co-Authors: Xiao Liu, Kerry J Gilmore, Simon E Moulton, Gordon G WallaceAbstract:The purpose of this work was to investigate for the first time the potential biomedical applications of novel polypyrrole (PPy) composites incorporating a large polyelectrolyte dopant, poly (2-methoxy-5 aniline sulfonic acid) (PMAS). The physical and electrochemical properties were characterized. The PPy/PMAS composites were found to be smooth and hydrophilic and have low electrical impedance. We demonstrate that PPy/PMAS supports Nerve Cell (PC12) Differentiation, and that clinically relevant 250 Hz biphasic current pulses delivered via PPy/PMAS films significantly promote Nerve Cell Differentiation in the presence of Nerve growth factor (NGF). The capacity of PPy/PMAS composites to support and enhance Nerve Cell Differentiation via electrical stimulation renders them valuable for medical implants for neurological applications.
Meldolesi J. - One of the best experts on this subject based on the ideXlab platform.
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REST/NRSF governs the expression of dense-core vesicle gliosecretion in astrocytes
2011Co-Authors: Marchaland J, Podini P, Magrassi L, D'alessandro R, Bezzi P, Meldolesi J.Abstract:Astrocytes are the brain nonNerve Cells that are competent for gliosecretion, i.e., for expression and regulated exocytosis of clear and dense-core vesicles (DCVs). We investigated whether expression of astrocyte DCVs is governed by RE-1-silencing transcription factor (REST)/neuron-restrictive silencer factor (NRSF), the transcription repressor that orchestrates Nerve Cell Differentiation. Rat astrocyte cultures exhibited high levels of REST and expressed neither DCVs nor their markers (granins, peptides, and membrane proteins). Transfection of a dominant-negative construct of REST induced the appearance of DCVs filled with secretogranin 2 and neuropeptide Y (NPY) and distinct from other organelles. Total internal reflection fluorescence analysis revealed NPY-monomeric red fluorescent protein-labeled DCVs to undergo Ca(2+)-dependent exocytosis, which was largely prevented by botulinum toxin B. In the I-II layers of the human temporal brain cortex, all neurons and microglia exhibited the expected inappreciable and high levels of REST, respectively. In contrast, astrocyte REST was variable, going from inappreciable to high, and accompanied by a variable expression of DCVs. In conclusion, astrocyte DCV expression and gliosecretion are governed by REST. The variable in situ REST levels may contribute to the well-known structural/functional heterogeneity of astrocytes
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Astrocyte dense-core vesicle gliosecretion is governed by rest/nrsf
2011Co-Authors: Prada J., Marchaland J, Podini P, Magrassi L, D'alessandro R, Bezzi P, Meldolesi J.Abstract:Astrocytes are the brain non-Nerve Cells competent for the expression of clear and dense-core vesicles (DCVs) and for their regulated exocytosis. This process, called gliosecretion, nearly resembles the neurosecretion occurring in neurons and neurosecretory Cells. REST/NRSF is a transcription repressor known to orchestrate Nerve-Cell Differentiation, governing the expression of hundreds of neuron-specific genes through their repression in the non-Nerve and their fine modulation in the Nerve Cells. Our previous studies in neurosecretory rat PC12 Cells identified REST as the critical factor for the expression not only of individual genes, but also of the whole neurosecretory process via multiple, direct and indirect mechanisms (D'Alessandro et al., J. Neurochem., 2008; Klajn et al., J. Neurosci., 2009). Therefore we wondered whether gliosecretion was governed by REST. We investigated rat astrocyte primary cultures: they exhibited high REST, which directly represses the transcription of at least one target gene, and expressed neither DCVs nor their markers (granins, peptides, membrane proteins). Transfection of a dominant-negative construct of REST (REST/ DBD-GFP) induced the appearance of DCVs filled with secretogranin2 and NPY that are distinct from other intraCellular organelles. TIRF analysis of astrocytes co-transfected with REST/DBD-GFP and NPY-mRFP constructs revealed NPY-mRFP-positive DCVs undergoing Ca2þ-dependent exocytosis, largely prevented by BoNT/B. Immunohistochemistry of the I-II layers of the human temporal brain cortex showed all neurons and microglia exhibiting the expected inappreciable and high levels of REST, respectively. In contrast astrocyte RESTwas variable, going from inappreciable to high, accompanied by variable expression of DCVs. In this work it has been demonstrated that astrocyte DCV expression and gliosecretion are governed by REST (Prada et al., 2011 in press). The variable in situ REST levels may contribute to the well known structural/functional heterogeneity of astrocytes and this new observation might be of great interest for the understanding of both astrocyte physiology and pathology
Andre Terzic - One of the best experts on this subject based on the ideXlab platform.
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Functionalized Carbon Nanotube and Graphene Oxide Embedded Electrically Conductive Hydrogel Synergistically Stimulates Nerve Cell Differentiation
ACS applied materials & interfaces, 2017Co-Authors: Xifeng Liu, A. Lee Miller, Sungjo Park, Brian E. Waletzki, Zifei Zhou, Andre TerzicAbstract:Nerve regeneration after injury is a critical medical issue. In previous work, we have developed an oligo(poly(ethylene glycol) fumarate) (OPF) hydrogel incorporated with positive charges as a promising Nerve conduit. In this study, we introduced cross-linkable bonds to graphene oxide and carbon nanotube to obtain the functionalized graphene oxide acrylate (GOa) and carbon nanotube poly(ethylene glycol) acrylate (CNTpega). An electrically conductive hydrogel was then fabricated by covalently embedding GOa and CNTpega within OPF hydrogel through chemical cross-linking followed by in situ reduction of GOa in l-ascorbic acid solution. Positive charges were incorporated by 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTAC) to obtain rGOaCNTpega-OPF-MTAC composite hydrogel with both surface charge and electrical conductivity. The distribution of CNTpega and GOa in the hydrogels was substantiated by transmission electron microscopy (TEM), and strengthened electrical conductivities were determined. ExCell...