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Find video protocols related to scientific articles indexed in Pubmed.
PEG-PLA nanoparticles modified with APTEDB peptide for enhanced anti-angiogenic and anti-glioma therapy.
Biomaterials
PUBLISHED: 05-23-2014
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Tumor neovasculature and tumor cells dual-targeting chemotherapy can not only destroy the tumor neovasculature, cut off the supply of nutrition and starve the tumor cells, but also directly kill tumor cells, holding great potential in overcoming the drawbacks of anti-angiogenic therapy only and improving the anti-glioma efficacy. In the present study, by taking advantage of the specific expression of fibronectin extra domain B (EDB) on both glioma neovasculature endothelial cells and glioma cells, we constructed EDB-targeted peptide APTEDB-modified PEG-PLA nanoparticles (APT-NP) for paclitaxel (PTX) loading to enable tumor neovasculature and tumor cells dual-targeting chemotherapy. PTX-loaded APT-NP showed satisfactory encapsulated efficiency, loading capacity and size distribution. In human umbilical vein endothelial cells, APT-NP exhibited significantly elevated cellular accumulation via energy-dependent, caveolae and lipid raft-involved endocytosis, and improved PTX-induced apoptosis therein. Both in vitro tube formation assay and in vivo matrigel angiogenesis analysis confirmed that APT-NP significantly improved the antiangiogenic ability of PTX. In U87MG cells, APT-NP showed elevated cellular internalization and also enhanced the cytotoxicity of the loaded PTX. Following intravenous administration, as shown by both in vivo live animal imaging and tissue distribution analysis, APT-NP achieved a much higher and specific accumulation within the glioma. As a result, APT-NP-PTX exhibited improved anti-glioma efficacy over unmodified nanoparticles and Taxol(®) in both subcutaneous and intracranial U87MG xenograft models. These findings collectively indicated that APTEDB-modified nanoparticles might serve as a promising nanocarrier for tumor cells and neovasculature dual-targeting chemotherapy and hold great potential in improving the efficacy anti-glioma therapy.
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Determination of a novel carbamate AChE inhibitor meserine in mouse plasma, brain and rat plasma by LC-MS/MS: application to pharmacokinetic study after intravenous and subcutaneous administration.
J Pharm Biomed Anal
PUBLISHED: 03-12-2014
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In this paper a simple and sensitive method for determination of a novel phenylcarbamate AChE inhibitor, meserine, in mouse plasma, brain and rat plasma was evaluated using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Separation was achieved on an Alltech Alltima-C18 column (150mm×2.1mm, 3?m, Deerfield, IL, USA) with isocratic elution at a flow rate of 0.35ml/min. Detection was performed under the multiple reaction monitoring (MRM) mode using an electrospray ionization (ESI) in the positive ion mode. The protein precipitation and liquid-liquid extraction methods were used for the pretreatment of plasma and brain homogenates, respectively. The calibration curves of meserine showed good linearity over the concentration range of 0.5-1000ng/ml for mouse and rat plasma and 0.5-500ng/ml for mouse brain. The intra- and inter-day precision were less than 9.34% and the accuracy was from 95.34% to 107.78% for QC samples. The validated method was successfully applied to a preclinical pharmacokinetic study of meserine in mice and rats after intravenous and subcutaneous administration. The results showed that this novel drug could easily cross the blood-brain barrier to reach the site of drug action. Meserine was rapidly absorbed with a high subcutaneous absolute bioavailability (>90%).
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Effects of acidic oligosaccharide sugar chain on amyloid oligomer-induced impairment of synaptic plasticity in rats.
Metab Brain Dis
PUBLISHED: 02-26-2014
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Soluble amyloid-? protein (A?) oligomers have been recognized to be early and key intermediates in Alzheimer's disease-related synaptic dysfunction. In this study, using in vitro electrophysiology, we investigated interactions of the acidic oligosaccharide sugar chain (AOSC), a marine-derived acidic oligosaccharide, with oligomeric A?. We found that the inhibition of long-term potentiation (LTP) induced by A? oligomers can be dose dependently reversed by the application of AOSC, whereas AOSC alone did not alter normal LTP induction. Interestingly, treatment with A? monomers with or without AOSC did not affect LTP induction. Additionally, when fresh-made A? was co-incubated with AOSC before in vitro testing, there was no impairment of LTP induction. The results from Western blots demonstrated that AOSC prevent the aggregation of A? oligomers. These findings indicate that AOSC may reverse A? oligomer-mediated cytotoxicity by directly disrupting the amyloid oligomer aggregation, and this action is concentration dependent. Thus, we propose that AOSC might be a potential therapeutic drug for Alzheimer's disease due to its protection against oligomeric A?-induced dysfunction of synaptic plasticity.
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Lipoprotein-based nanoparticles rescue the memory loss of mice with Alzheimer's disease by accelerating the clearance of amyloid-beta.
ACS Nano
PUBLISHED: 02-21-2014
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Amyloid-beta (A?) accumulation in the brain is believed to play a central role in Alzheimer's disease (AD) pathogenesis, and the common late-onset form of AD is characterized by an overall impairment in A? clearance. Therefore, development of nanomedicine that can facilitate A? clearance represents a promising strategy for AD intervention. However, previous work of this kind was concentrated at the molecular level, and the disease-modifying effectiveness of such nanomedicine has not been investigated in clinically relevant biological systems. Here, we hypothesized that a biologically inspired nanostructure, apolipoprotein E3-reconstituted high density lipoprotein (ApoE3-rHDL), which presents high binding affinity to A?, might serve as a novel nanomedicine for disease modification in AD by accelerating A? clearance. Surface plasmon resonance, transmission electron microscopy, and co-immunoprecipitation analysis showed that ApoE3-rHDL demonstrated high binding affinity to both A? monomer and oligomer. It also accelerated the microglial, astroglial, and liver cell degradation of A? by facilitating the lysosomal transport. One hour after intravenous administration, about 0.4% ID/g of ApoE3-rHDL gained access to the brain. Four-week daily treatment with ApoE3-rHDL decreased A? deposition, attenuated microgliosis, ameliorated neurologic changes, and rescued memory deficits in an AD animal model. The findings here provided the direct evidence of a biomimetic nanostructure crossing the blood-brain barrier, capturing A? and facilitating its degradation by glial cells, indicating that ApoE3-rHDL might serve as a novel nanomedicine for disease modification in AD by accelerating A? clearance, which also justified the concept that nanostructures with A?-binding affinity might provide a novel nanoplatform for AD therapy.
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Targeted inhibition of KCa3.1 attenuates TGF-?-induced reactive astrogliosis through the Smad2/3 signaling pathway.
J. Neurochem.
PUBLISHED: 02-04-2014
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Reactive astrogliosis, characterized by cellular hypertrophy and various alterations in gene expression and proliferative phenotypes, is considered to contribute to brain injuries and diseases as diverse as trauma, neurodegeneration, and ischemia. KCa3.1 (intermediate-conductance calcium-activated potassium channel), a potassium channel protein, has been reported to be up-regulated in reactive astrocytes after spinal cord injury in vivo. However, little is known regarding the exact role of KCa3.1 in reactive astrogliosis. To elucidate the role of KCa3.1 in regulating reactive astrogliosis, we investigated the effects of either blocking or knockout of KCa3.1 channels on the production of astrogliosis and astrocytic proliferation in response to transforming growth factor (TGF)-? in primary cultures of mouse astrocytes. We found that TGF-? increased KCa3.1 protein expression in astrocytes, with a concomitant marked increase in the expression of reactive astrogliosis, including glial fibrillary acidic protein and chondroitin sulfate proteoglycans. These changes were significantly attenuated by the KCa3.1 inhibitor 1-((2-chlorophenyl) (diphenyl)methyl)-1H-pyrazole (TRAM-34). Similarly, the increase in glial fibrillary acidic protein and chondroitin sulfate proteoglycans in response to TGF-? was attenuated in KCa3.1(-/-) astrocytes. TRAM-34 also suppressed astrocytic proliferation. In addition, the TGF-?-induced phosphorylation of Smad2 and Smad3 proteins was reduced with either inhibition of KCa3.1 with TRAM-34 or in KCa3.1(-/-) astrocytes. These findings highlight a novel role for the KCa3.1 channel in reactive astrogliosis phenotypic modulation and provide a potential target for therapeutic intervention for brain injuries. Reactive astrogliosis is characterized by the expression of glial fibrillary acidic protein and chondroitin sulfate proteoglycans. We demonstrate that either pharmacological blockade or knockout of KCa3.1 channels reduces reactive gliosis in cultured astrocytes caused by TGF-?, and also reduces TGF-?-induced phosphorylation of Smad2/3.
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iNGR-modified PEG-PLGA nanoparticles that recognize tumor vasculature and penetrate gliomas.
Biomaterials
PUBLISHED: 01-31-2014
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A major cross-cutting problem for glioma therapy is the poor extravasation and penetration of the payload drug in target glioma parenchyma. Here, to overcome these obstacles, a tumor vessel recognizing and tumor penetrating system is developed by functionalizating the poly (ethyleneglycol)-poly (L-lactic-co-glycolic acid) nanoparticles with an iNGR moiety (iNGR-NP). The nanoparticulate formulation is expected to achieve specific deep penetration in the tumor tissue by initially binding to aminopeptidase N, with iNGR proteolytically cleaved to CRNGR, and then bind with neuropilin-1 to mediate deep penetration in the tumor parenchyma. iNGR-NP exhibits significantly enhanced cellular uptake in human umbilical vein endothelial cells, improves the anti-proliferation and anti-tube formation abilities of paclitaxel in vitro. Following intravenous administration, iNGR-NP present favorable pharmacokinetic and tumor homing profiles. Glioma distribution and penetration assays confirm that iNGR-NP achieve the highest accumulation and deepest penetration at the glioma sites. The anti-glioma efficacy of paclitaxel-loaded iNGR-NP is verified by its improved anti-angiogenesis activity and the significantly prolonged survival time in mice bearing intracranial glioma. These evidences highlight the potential of iNGR-decorated nanoparticles in overcoming the leading edge problem in anti-glioma drug delivery.
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Subneurotoxic copper(II)-induced NF-?B-dependent microglial activation is associated with mitochondrial ROS.
Toxicol. Appl. Pharmacol.
PUBLISHED: 01-23-2014
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Microglia-mediated neuroinflammation and the associated neuronal damage play critical roles in the pathogenesis of neurodegenerative disorders. Evidence shows an elevated concentration of extracellular copper(II) in the brains of these disorders, which may contribute to neuronal death through direct neurotoxicity. Here we explored whether extracellular copper(II) triggers microglial activation. Primary rat microglia and murine microglial cell line BV-2 cells were cultured and treated with copper(II). The content of tumor necrosis factor-? (TNF-?) and nitric oxide in the medium was determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was measured by MitoSOX oxidation. At subneurotoxic concentrations, copper(II) treatment induced a dose- and time-dependent release of TNF-? and nitric oxide from microglial cells, and caused an indirect, microglia-mediated neurotoxicity that was blocked by inhibition of TNF-? and nitric oxide production. Copper(II)-initiated microglial activation was accompanied with reduced I?B-? expression as well as phosphorylation and translocation of nuclear factor-?B (NF-?B) p65 and was blocked by NF-?B inhibitors (BAY11-7082 and SC-514). Moreover, copper(II) treatment evoked a rapid release of hydrogen peroxide from microglial cells, an effect that was not affected by NADPH oxidase inhibitors. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), abrogated copper(II)-elicited microglial release of TNF-? and nitric oxide and subsequent neurotoxicity. Importantly, mitochondrial production of superoxide, paralleled to extracellular release of hydrogen peroxide, was induced after copper(II) stimulation. Our findings suggest that extracellular copper(II) at subneurotoxic concentrations could trigger NF-?B-dependent microglial activation and subsequent neurotoxicity. NADPH oxidase-independent, mitochondria-derived ROS may be involved in this activation.
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Determination of Meserine, a new candidate for Alzheimer's disease in mice brain by liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic and tissue distribution study.
Anal Bioanal Chem
PUBLISHED: 01-21-2014
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A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of Meserine ((-)-meptazinol phenylcarbamate), a novel potent inhibitor of acetylcholinesterase (AChE), was developed, validated, and applied to a pharmacokinetic study in mice brain. The lower limit of quantification (LLOQ) was 1 ng mL(-1) and the linear range was 1-1,000 ng mL(-1). The analyte was eluted on a Zorbax SB-Aq column (2.1?×?100 mm, 3.5 ?m) with the mobile phase composed of methanol and water (70:30, v/v, aqueous phase contained 10 mM ammonium formate and 0.3% formic acid) using isocratic elution, and monitored by positive electrospray ionization in multiple reaction monitoring (MRM) mode. The flow rate was 0.25 mL min(-1). The injection volume was 5 ?L and total run time was 4 min. The relative standard deviation (RSD) of intraday and interday variation was 2.49-7.81 and 3.01-7.67%, respectively. All analytes were stable after 4 h at room temperature and 6 h in autosampler. The extraction recoveries of Meserine in brain homogenate were over 90%. The main brain pharmacokinetic parameters obtained after intranasal administration were T max?=?0.05 h, C max?=?462.0?±?39.7 ng g(-1), T 1/2?=?0.4 h, and AUC(0-?)?=?283.1?±?9.1 ng h g(-1). Moreover, Meserine was distributed rapidly and widely into brain, heart, liver, spleen, lung, and kidney tissue. The method is validated and could be applied to the pharmacokinetic and tissue distribution study of Meserine in mice.
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Facilitated brain delivery of poly (ethylene glycol)-poly (lactic acid) nanoparticles by microbubble-enhanced unfocused ultrasound.
Biomaterials
PUBLISHED: 01-18-2014
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Nanotechnology plays a unique instrumental role in the revolutionary development of brain-specific drug delivery, imaging, and diagnosis, but is highly limited by the existence of blood-brain barrier (BBB). In this study, microbubble-enhanced unfocused ultrasound (MEUUS) was developed as an approach to mediate an extensive brain delivery of poly (ethylene glycol) - poly (lactic acid) (PEG-PLA) nanoparticles. Following the MEUUS treatment, the nanoparticles signals were found to penetrate through the vascular walls and distributed deeply into the parenchyma at a significantly higher level (more than 250%) than those of the non-MEUUS treated control. Such effect was reversible and dependent on nanoparticles injection timing, sonication mode and mechanical index. Together with the transmission electron microscopy analysis, the increased brain accumulation of nanoparticles was claimed to be largely mediated by an ultrasound-induced stable cavitation of the microbubble which resulted in mechanical stretching of the vessel wall and consequently induced cellular transcytosis of the nanoparticles. The MEUUS technique was also used to facilitate the brain delivery of PEG-PLA nanoparticles functionalized with amyloid beta-specific antibody 6E10 for enabling the recognition of the hallmarks of Alzheimer's disease that widely distributed in the brain. No erythrocytes extravasation and other visible damages in the brain were detected following the MEUUS treatment. These findings together indicated that unfocused ultrasound with the aid of microbubble could effectively improve the brain delivery of nanoparticles, and this approach might serve as a safe and flexible platform for the potential application of nanoparticles in the diagnosis and therapy of brain diseases.
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CGKRK-modified nanoparticles for dual-targeting drug delivery to tumor cells and angiogenic blood vessels.
Biomaterials
PUBLISHED: 08-08-2013
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Antiangiogenic therapy shows great advantages in clinical cancer treatment while no overall survival has been achieved. The compromised results were mainly contributed by intrinsic/acquired antiangiogenic drug resistance and increased local invasion or distant metastasis after antiangiogenic therapy. Here we constructed a CGKRK peptide-modified PEG-co-PCL nanoparticulate drug delivery system (DDS), aiming at targeting both tumor angiogenic blood vessels and tumor cells to achieve enhanced anti-tumor activity as well as holding a great potential to overcome the drawbacks of antiangiogenic therapy alone. The obtained CGKRK-functionalized PEG-co-PCL nanoparticles (CGKRK-NP) with a particle size of 117.28 ± 10.42 nm and zeta potential of -15.7 ± 3.32 mV, exhibited an enhanced accumulation via an energy-dependent, lipid raft/caveolae-mediated endocytosis with the involvement of microtubules in human umbilical vein endothelial cells (HUVEC) and an energy-dependent, lipid raft/caveolae-mediated endocytosis with the participation of Golgi apparatus in human U87MG cells. Using coumarin-6 as the fluorescence probe, in vitro U87MG tumor spheroids assays showed that CGKRK-NP effectively penetrated into the tumor spheroids. Selective accumulation and extensive bio-distribution of CGKRK-NP at tumor site was confirmed by in vivo imaging and tumor section analysis. After drug loading, CGKRK-NP enhanced cytotoxicity and apoptosis induction activity of the loaded PTX on both HUVEC cells and U87MG cells and improved its inhibition effect on the growth of U87MG tumor spheroids. The smallest tumor volume was achieved by those mice bearing subcutaneous U87MG tumor following the treatment of PTX-loaded CGKRK-NP. The findings here indicated that CGKRK peptide-functionalized nanoparticulate DDS could be used as an effective tumor angiogenic blood vessels and tumor cells dual-targeting DDS and might provide a great promising approach for reducing the disadvantages of antiangiogenic therapy alone.
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B6 peptide-modified PEG-PLA nanoparticles for enhanced brain delivery of neuroprotective peptide.
Bioconjug. Chem.
PUBLISHED: 06-10-2013
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The blood-brain barrier (BBB), which is formed by the brain capillary wall, greatly hinders the development of new drugs for the brain. Over the past decades, among the various receptor-mediated endogenous BBB transport systems, the strategy of using transferrin or anti-transferrin receptor antibodies to facilitate brain drug delivery system is of particular interest. However, the application of large proteins still suffers from the drawbacks including synthesis procedure, stability, and immunological response. Here, we explored a B6 peptide discovered by phase display as a substitute for transferrin, and conjugated it to PEG-PLA nanoparticles (NP) with the aim of enhancing the delivery of neuroprotective drug across the BBB for the treatment of Alzheimers disease. B6-modified NP (B6-NP) exhibited significantly higher accumulation in brain capillary endothelial cells via lipid raft-mediated and clathrin-mediated endocytosis. In vivo, fluorescently labeled B6-NP exhibited much higher brain accumulation when compared with NP. Administration of B6-NP encapsulated neuroprotective peptide-NAPVSIPQ (NAP)-to Alzheimers disease mouse models showed excellent amelioration in learning impairments, cholinergic disruption, and loss of hippocampal neurons even at lower dose. These findings together suggested that B6-NP might serve as a promising DDS for facilitating the brain delivery of neuropeptides.
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Determination of the stress biomarker corticosterone in serum of tumor-bearing mice by surrogate-based liquid chromatography-tandem mass spectrometry.
Biomed. Chromatogr.
PUBLISHED: 04-07-2013
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A simple, robust and specific liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine the concentration of corticosterone (Cort) which is usually regarded as a stress biomarker in mouse serum. Since Cort is an endogenous hormone, a surrogate analyte strategy was adopted using the stable isotope-deuterated corticosterone as a surrogate of the authentic analyte to generate the calibration curve. With telmisartan as the internal standard, the analytes were extracted with methanol, ethanol and acetone (1:1:1, v/v/v) and separated on a XTerra C18 (2.1?×?50 mm, 3.5 µm) column using a mobile phase consisting of 0.2% formic acid in water-methanol (30:70, v/v). Detection was performed in multiple reaction monitoring mode with an electrospray ionization source operated in positive ion mode. The standard curves were linear (r(2) ?>?0.999) over the dynamic range of 8.60-430 ng/mL, with a lower limit of quantification of 8.60 ng/mL. The intra- and inter-assay precisions were less than 15.0% of the relative standard deviation. This method was further used for analysis of serum samples from C57B/L tumor-bearing mice before and after the treatment of fluoxetine. Validation of the assay and its application to the analysis demonstrated that the method was applicable to determine meaningful changes in Cort concentrations in serum samples of the tumor-bearing mice for the stress status evaluation. Copyright © 2013 John Wiley & Sons, Ltd.
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Glioma therapy using tumor homing and penetrating peptide-functionalized PEG-PLA nanoparticles loaded with paclitaxel.
Biomaterials
PUBLISHED: 03-21-2013
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By taking advantage of the excessively upregulated expression of neuropilin (NRP) on the surface of both glioma cells and endothelial cells of angiogenic blood vessels, the ligand of NRP with high affinity - tLyp-1 peptide, which also contains a CendR motif ((R/K)XX(R/K)), was functionalized to the surface of PEG-PLA nanoparticles (tLyp-1-NP) to mediate its tumor homing, vascular extravasation and deep penetration into the glioma parenchyma. The tLyp-1-NP was prepared via a maleimide-thiol coupling reaction with uniformly spherical shape under TEM and particle size of 111.30 ± 15.64 nm. tLyp-1-NP exhibited enhanced cellular uptake in both human umbilical vein endothelial cells and Rat C6 glioma cells, increased cytotoxicity of the loaded PTX, and improved penetration and growth inhibition in avascular C6 glioma spheroids. Selective accumulation and deep penetration of tLyp-1-NP at the glioma site was confirmed by in vivo imaging and glioma distribution analysis. The longest survival was achieved by those mice bearing intracranial C6 glioma treated with PTX-loaded tLyp-1-NP. The findings here strongly indicate that tLyp-1 peptide-functionalized nanoparticulate DDS could significantly improve the efficacy of paclitaxel glioma therapy.
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Activatable cell penetrating peptide-conjugated nanoparticles with enhanced permeability for site-specific targeting delivery of anticancer drug.
Bioconjug. Chem.
PUBLISHED: 02-11-2013
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Based on the powerful cell-penetrating ability of low molecular weight protamine (LMWP) and the overexpression of matrix metalloproteinases in the tumor sites, we constructed an activatable low molecular weight protamine (ALMWP) and modified it onto the surface of poly(ethylene glycol)-poly(lactic acid) nanoparticles to develop a "smart" drug delivery system with enhanced permeability for facilitating site-specific targeting delivery of anticancer drug. The obtained ALMWP-functionalized nanoparticles (ALMWP-NP) with a particle size of 134.0 ± 4.59 nm and a zeta potential of -34.4 ± 2.7 mV, exhibited an enhanced MMP-dependent accumulation in HT-1080 cells via both energy-independent direct translocation and clathrin-mediated, cytoskeleton-dependent endocytosis. Pharmacokinetic and biodistribution study in HT-1080 tumor-bearing mice showed that ALMWP-NP significantly increased the accumulation of paclitaxel (PTX) in the tumor site but not the nontarget tissues. In addition, intratumor distribution analysis demonstrated that more ALMWP-NP penetrated deeply into the tumor parenchyma. As a result, PTX loaded by ALMWP-NP exhibited improved antitumor efficacy over that by unmodified nanoparticles and LMWP-functionalized nanoparticles. The findings suggested that ALMWP-NP could be used as a safe and effective tumor-targeting drug delivery system and opened a new gateway to the application of cell-penetrating peptides for targeted antitumor therapy.
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Lactoferrin-modified PEG-co-PCL nanoparticles for enhanced brain delivery of NAP peptide following intranasal administration.
Biomaterials
PUBLISHED: 02-01-2013
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Development of effective non-invasive drug delivery systems is of great importance to the treatment of Alzheimers diseases and has made great progress in recent years. In this work, lactoferrin (Lf), a natural iron binding protein, whose receptor is highly expressed in both respiratory epithelial cells and neurons is here utilized to facilitate the nose-to-brain drug delivery of neuroprotection peptides. The Lf-conjugated PEG-PCL nanoparticle (Lf-NP) was constructed via a maleimide-thiol reaction with the Lf conjugation confirmed by CBQCA Protein Quantitation and XPS analysis. Other important parameters such as particle size distribution, zeta potential and in vitro release of fluorescent probes were also characterized. Compared with unmodified nanoparticles (NP), Lf-NP exhibited a significantly enhanced cellular accumulation in 16HBE14o-cells through both caveolae-/clathrin-mediated endocytosis and direct translocation. Following intranasal administration, Lf-NP facilitated the brain distribution of the coumarin-6 incorporated with the AUC0-8h in rat cerebrum (with hippocampus removed), cerebellum, olfactory tract, olfactory bulb and hippocampus 1.36, 1.53, 1.70, 1.57 and 1.23 times higher than that of coumarin-6 carried by NP, respectively. Using a neuroprotective peptide - NAPVSIPQ (NAP) as the model drug, the neuroprotective and memory improvement effect of Lf-NP was observed even at lower dose than that of NP in a Morris water maze experiment, which was also confirmed by the evaluation of acetylcholinesterase, choline acetyltransferase activity and neuronal degeneration in the mice hippocampus. In conclusion, Lf-NP may serve as a promising nose-to-brain drug delivery carrier especially for peptides and proteins.
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Cellular internalization pathway and transcellular transport of pegylated polyester nanoparticles in Caco-2 cells.
Int J Pharm
PUBLISHED: 01-24-2013
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Biodegradable polyester nanoparticles have now attracted growing interest as promising drug delivery system. However, a fundamental understanding about its cellular transport as well as the influence by the polymeric architecture is still lack, which remains a significant obstacle to optimal nanocarrier design. In this work, using Caco-2 cell model, we characterized the cellular transport pathway of pegylated polyester nanoparticles and determined the effect of polymer architecture including PEG chain length and core material on its cellular interaction and transcellular transport. The nanoparticles were found to undergo an energy-dependent, lipid raft-mediated, but caveolae-independent endocytosis. PEG chain length (from 2000 to 5000 Da) and core material (PLA/PLGA) hardly affected the cellular interaction and the intracellular itinerary of the nanoparticles. However, in the case of transcellular transport, the maximal transcellular transport efficiency for its payload was achieved by the PEG5000-PLA40000 nanoparticles which present higher drug loading capacity and slower drug release. The findings here revealed the cellular interaction mechanism of pegylated polyester nanoparticles and provided evidence for the role of polymer architectures in modulating the transcellular permeability of the agents loaded by the nanoparticles, and would be helpful in improving carrier design to enhance drug delivery.
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Synthesis and activity evaluation of tilorone analogs as potential anticancer agents.
Eur J Med Chem
PUBLISHED: 01-23-2013
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Tilorone is an interferon inducer with anticancer activity. Twenty-two novel tilorone analogs were synthesized by improvements of fluorenone skeleton, side chains and amino groups to screen new anticancer agents. In vitro evaluation showed that ten new compounds had better anticancer activities than tilorone. Among them, 2c (IC50 < 7 ?M against cancer cell lines and IC50 > 35 ?M against non-cancer cell lines) and 5d (IC50 < 10 ?M against cancer cell lines and IC50 > 53 ?M against non-cancer cell lines) exhibited the best anticancer activities and selectivities. Pharmacophore modeling of highly active compounds was carried out by Molecular Operating Environment (MOE) to generate a visualized model for compound design in future study.
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The influence of the penetrating peptide iRGD on the effect of paclitaxel-loaded MT1-AF7p-conjugated nanoparticles on glioma cells.
Biomaterials
PUBLISHED: 01-17-2013
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Low permeability across the blood-brain tumor barrier (BTB) and poor penetration into the glioma parenchyma represent key obstacles for anti-glioblastoma drug delivery. In this study, MT1-AF7p peptide, which presents high binding affinity to membrane type-1 matrix metalloproteinase (MT1-MMP) that over-expressed on both angiogenic blood vessels and glioma cells, was employed to decorate the paclitaxel-loaded PEG-PLA nanoparticles (MT1-NP-PTX) to mediate glioblastoma targeting. Tumor-homing and penetrating peptide iRGD was co-administrated to further facilitate nanoparticles extravasation from the tumor vessels and penetration into the glioma parenchyma. MT1-NP-PTX showed satisfactory encapsulated efficiency, loading capacity and size distribution. In C6 glioma cells, MT1-NP was found to exhibit significantly enhanced cellular accumulation than that of unmodified NP via both energy-dependent macropinocytosis and lipid raft-mediated endocytosis. The anti-proliferative and apoptosis-induction activity of PTX was significantly enhanced following its encapsulation in MT1-NP. In vivo imaging and glioma distribution together confirmed that MT1-AF7p functionalization and iRGD co-administration significantly improved the nanoparticles extravasation across BTB and accumulation in glioma parenchyma. Furthermore, in vitro C6 glioma spheroid assays evidenced that MT1-NP effectively penetrated into the glioma spheroids and significantly improved the growth inhibitory effects of loaded PTX on glioma spheroids. More importantly, the median survival time of those nude mice bearing intracranial C6 glioma received MT1-NP-PTX and iRGD combination regimen was 60 days, significantly longer than that of other groups. The findings suggested that the BTB/glioma cells dual-targeting DDS co-administrated with iRGD peptide might provide a both practical and feasible solution to highly efficient anti-glioblastoma drug delivery.
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In vivo pharmacokinetics and in vitro antifungal activity of iodiconazole, a new triazole, determined by microdialysis sampling.
Int. J. Antimicrob. Agents
PUBLISHED: 01-06-2013
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In this study, the distribution of a new triazole drug, iodiconazole, in rat dermal interstitial fluid and blood was investigated by double-site microdialysis following dermal administration. It was demonstrated that well-calibrated microdialysis sampling in rats could be used to assess the percutaneous penetration kinetics of iodiconazole cream. Iodiconazole penetrated rapidly and cleared slowly from the dermis. The ratio of area under the concentration-time curve in dermis (AUC(dermis)) to that in blood (AUC(blood)) was close to 20, which meant that the free iodiconazole concentration had a higher distribution in the target tissue. Subsequently, the in vitro antifungal activities of iodiconazole were evaluated and were compared with those of fluconazole, itraconazole, ketoconazole, miconazole and terbinafine. Iodiconazole exhibited broad spectrum and potent activity against 12 kinds of clinically pathogenic fungi. The drug concentration percentage inhibition curves versus time of iodiconazole against the tested fungi elucidated the two-dimensional relationship (concentration-effect) following drug administration, indicating that the percentage inhibition (%) of iodiconazole compared with the drug-free control in dermal dialysate were all >90% in the 900-min sampling time following dermal administration. Moreover, integration of in vivo pharmacokinetic data with the in vitro minimum inhibitory concentration (MIC) provided iodiconazole AUC/MIC ratios in rat dermis and blood of 347.7h and 18.8h, respectively, with an iodiconazole cream (2%) dosage of 0.033 g/cm² (3 cm×5 cm). These findings show a reservoir effect in the skin following topical application. Iodiconazole topical cream may be a future alternative for treatment of dermatophytosis in humans.
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Low molecular weight protamine-functionalized nanoparticles for drug delivery to the brain after intranasal administration.
Biomaterials
PUBLISHED: 08-21-2011
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The development of new strategies for enhancing drug delivery to the brain is of great importance in diagnostics and therapeutics of central nervous diseases. Low-molecular-weight protamine (LMWP) as a cell-penetrating peptide possesses distinct advantages including high cell translocation potency, absence of toxicity of peptide itself, and the feasibility as an efficient carrier for delivering therapeutics. Therefore, it was hypothesized that brain delivery of nanoparticles conjugated with LMWP should be efficiently enhanced following intranasal administration. LMWP was functionalized to the surface of PEG-PLA nanoparticles (NP) via a maleimide-mediated covalent binding procedure. Important parameters such as particle size distribution, zeta potential and surface content were determined, which confirmed the conjugation of LMWP to the surface of nanoparticle. Using 16HBE14o- cells as the cell model, LMWP-NP was found to exhibit significantly enhanced cellular accumulation than that of unmodified NP via both lipid raft-mediated endocytosis and direct translocation processes without causing observable cytotoxic effects. Following intranasal administration of coumarin-6-loaded LMWP-NP, the AUC(0-8 h) of the fluorescent probe detected in the rat cerebrum, cerebellum, olfactory tract and olfactory bulb was found to be 2.03, 2.55, 2.68 and 2.82 folds, respectively, compared to that of coumarin carried by NP. Brain distribution analysis suggested LMWP-NP after intranasal administration could be delivered to the central nervous system along both the olfactory and trigeminal nerves pathways. The findings clearly indicated that the brain delivery of nanoparticles could be greatly facilitated by LMWP and the LMWP-functionalized nanoparticles appears as a effective and safe carrier for nose-to-brain drug delivery in potential diagnostic and therapeutic applications.
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Surrogate based accurate quantification of endogenous acetylcholine in murine brain by hydrophilic interaction liquid chromatography-tandem mass spectrometry.
J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.
PUBLISHED: 07-01-2011
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Cholinergic dysfunction is known as a hallmark feature of Alzheimers disease (AD). Measurement of endogenous acetylcholine (ACh) in specific brain regions is important in understanding the pathology of AD and in designing and evaluating novel cholinomimetic agents for the treatment of AD. Since ACh is an endogenous neurotransmitter, there is no real blank matrix available to construct standard curves. It has been a challenging task to determine ACh in complex brain matrices. To overcome these difficulties, we employed a surrogate analyte strategy using ACh-d(4) instead of ACh to generate calibration curves and Ch-d(9) as internal standard (IS). The brain samples were deproteinized by acetonitrile with IS. Analytes and IS were separated by a HILIC column with the mobile phase composed of 20 mM ammonium formate in water-acetonitrile (30:70, v/v, adjusted to pH 3.0 with formic acid) and monitored in multiple reaction monitoring (MRM) mode using a positive electrospray source. The concentrations of endogenous ACh were calculated based on the peak area ratio of the analyte to the IS using a regression equation for the corresponding surrogate standard (ACh-d(4)). The lower limit of detection was 0.2 ng/mL and linearity was maintained over the range of 10-1000 ng/mL. Compared to other currently available methods, this approach offers improved accuracy and precision for efficient analysis of ACh. The proposed method was proved successfully by evaluating the action of typical acetylcholinesterase inhibitor huperzine A in senescence accelerated mouse prone 8 (SAMP8).
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The association of autophagy with polyethylenimine-induced cytotoxicity in nephritic and hepatic cell lines.
Biomaterials
PUBLISHED: 06-05-2011
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Polyethylenimine (PEI) is one of the most effective and widely used cationic macromolecules in experimental gene transfer/therapy protocols. However, the further clinical application of PEI is largely impeded by its cytotoxicity. Here we performed a fundamental investigation on the mechanism of PEI-induced cytotoxicity in both hepatic and nephritic cell lines. It was demonstrated that besides necrosis and apoptosis, autophagy was apparently associated with PEI-induced cytotoxicity and contributed to aggravated cell damage. Specifically, at the early stage (3 h) of PEI-induced cytotoxicity, autophagy was mainly correlated with lysosome damage, but in the later phase (after a 24-h recovery), autophagy was mainly related with mitochondrial injury. Modulation of Rab5, Rab7 expression and inhibition of clathrin-mediated endocytosis pathway significantly affected the formation of autophagosome, which suggested that the endolysosome transport pathway especially the clathrin-mediated endocytosis at least partly facilitated PEI-induced autophagy. As PEI-induced autophagy played a causative role in its cytotoxicity, its highly recommended to design PEI-based gene-carriers that could avoid the endolysosome transport pathway.
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A novel small Odorranalectin-bearing cubosomes: preparation, brain delivery and pharmacodynamic study on amyloid-??????-treated rats following intranasal administration.
Eur J Pharm Biopharm
PUBLISHED: 05-13-2011
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Because of the immunogenicity and toxicity in vivo of large molecules such as lectins, the application of these molecules is remarkably restricted in drug delivery systems. In this study, to improve the brain drug delivery and reduce the immunogenicity of traditional lectin modified delivery system, Odorranalectin (OL, 1700 Da), a novel non-immunogenic small peptide, was selected to establish an OL-modified cubosomes (Cubs) system. The streptavidin (SA)-conjugated Cubs were prepared by incorporating maleimide-PEG-oleate and taking advantage of its thiol group binding reactivity to conjugate with 2-iminothiolane thiolated SA; mono-biotinylated OL was then coupled with the SA-modified Cubs. The OL-decorated Cubs (OL-Cubs) devised via a non-covalent SA-biotin "bridge" made it easy to conjugate OL and determine the number of ligands on the surface of the Cubs using sensitive chemiluminescent detection. Retention of the bio-recognitive activity of OL after covalent coupling was verified by hemagglutination testing. Nose-to-brain delivery characteristic of OL-Cubs was investigated by in vivo fluorescent biodistribution using coumarin-6 as a marker. The relative uptake of coumarin carried by OL-Cubs was 1.66- to 3.46-fold in brain tissues compared to that incorporated in the Cubs. Besides, Gly14-Humanin (S14G-HN) as a model peptide drug was loaded into cubosomes and evaluated for its pharmacodynamics on Alzheimers disease (AD) rats following intranasal administration by Morris water maze test and acetylcholinesterase activity determination. The results suggested that OL functionalization enhanced the therapeutic effects of S14G-HN-loaded cubosomes on AD. Thus, OL-Cubs might offer a novel effective and noninvasive system for brain drug delivery, especially for peptides and proteins.
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Aptamer-functionalized PEG-PLGA nanoparticles for enhanced anti-glioma drug delivery.
Biomaterials
PUBLISHED: 05-08-2011
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Targeted delivery of therapeutic nanoparticles in a disease-specific manner represents a potentially powerful technology especially when treating infiltrative brain tumors such as gliomas. We developed a nanoparticulate drug delivery system decorated with AS1411 (Ap), a DNA aptamer specifically binding to nucleolin which was highly expressed in the plasma membrane of both cancer cells and endothelial cells in angiogenic blood vessels, as the targeting ligand to facilitate anti-glioma delivery of paclitaxel (PTX). Ap was conjugated to the surface of PEG-PLGA nanoparticles (NP) via an EDC/NHS technique. With the conjugation confirmed by Urea PAGE and XPS, the resulting Ap-PTX-NP was uniformly round with particle size at 156.0 ± 54.8 nm and zeta potential at -32.93 ± 3.1 mV. Ap-nucleolin interaction significantly enhanced cellular association of nanoparticles in C6 glioma cells, and increased the cytotoxicity of its payload. Prolonged circulation and enhanced PTX accumulation at the tumor site was achieved for Ap-PTX-NP, which eventually obtained significantly higher tumor inhibition on mice bearing C6 glioma xenografts and prolonged animal survival on rats bearing intracranial C6 gliomas when compared with PTX-NP and Taxol(®). The results of this contribution demonstrated the potential utility of AS1411-functionalized nanoparticles for a therapeutic application in the treatment of gliomas.
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Latanoprost promotes neurite outgrowth in differentiated RGC-5 cells via the PI3K-Akt-mTOR signaling pathway.
Cell. Mol. Neurobiol.
PUBLISHED: 01-12-2011
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Latanoprost, a synthetic derivative of the natural prostaglandin F(2a) (PGF(2a)), is a powerful antiglaucoma agent with ocular hypotensive and neuroprotective effects. However, the neuroregenerative effect and signaling pathway of latanoprost in retinal ganglion cells (RGCs) are still unknown. The purpose of this study is to investigate the regenerative effect of latanoprost in differentiated RGC-5 cells and its underlying mechanisms. Cell viability was determined by Cell Counting Kit-8 (CCK-8) assay and neurite length was examined by ArrayScan HCS Reader and Neurite outgrowth BioApplication. Expressions of Akt phosphorylation (p-Akt) and mammalian target of rapamycin phosphorylation (p-mTOR) were investigated by Western blot analysis. The results indicated that 0.1 ?M latanoprost (at a clinically therapeutic concentration) significantly increased cell viability as compared with control. Meanwhile, 0.1 ?M latanoprost resulted in the obvious promotion of neurite outgrowth similar to ciliary neurotrophic factor (CNTF) and simultaneously increased the levels of p-Akt and p-mTOR expression. The effects of latanoprost were blocked by the Prostaglandin F receptor (FP receptor) inhibitor AL8810, the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 and the mTOR inhibitor rapamycin. This study presents novel in vitro evidence that latanoprost could promote neurite outgrowth through an FP receptor-mediated modulation of the PI3K-Akt-mTOR signaling pathway. This finding may provide insight into a better understanding of a new mechanism of latanoprost for glaucoma therapy and into the physiological-modulating activities of prostaglandins.
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Simultaneous determination of citalopram and its metabolite in human plasma by LC-MS/MS applied to pharmacokinetic study.
J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.
PUBLISHED: 01-07-2010
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A simple sensitive and robust method for simultaneous determination of citalopram and desmethylcitalopram was developed using liquid chromatography tandem mass spectrometry (LC-MS/MS). A 200 microL aliquot of plasma sample was employed and deproteinized with methanol and desipramine was used as the internal standard. After vortex mixing and centrifugation, the supernatant was diluted with water (1:1, v/v) and then directly injected to analysis. Analytes were separated by a Zorbax XDB C(18) column with the mobile phase composed of acetonitrile and water (30:70, v/v) with 0.25% formic acid and monitored in MRM mode using a positive electrospray source with tandem mass spectrometry detection. The total run time was 3.5 min. The dynamic range was 0.2-100 ng/mL for citalopram and 0.25-50 ng/mL for desmethylcitalopram, respectively. Compared to the best existing literatures for plasma samples, the same LOQ for CIT (0.5 ng/mL) and lower LOQ for DCIT (0.25 vs 5 ng/mL) were reached, and less sample preparation steps and runtime (3.5 vs 10 min) were taken for our method. Accuracy and precision was lower than 8% and lower than 11.5% for either target. Validation results and its application to the analysis of plasma samples after oral administration of citalopram in healthy Chinese volunteers demonstrated the method was applicable to pharmacokinetic studies.
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Pilocarpine protects cobalt chloride-induced apoptosis of RGC-5 cells: involvement of muscarinic receptors and HIF-1 alpha pathway.
Cell. Mol. Neurobiol.
PUBLISHED: 04-11-2009
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The retina is the most metabolically active tissue in the human body and hypoxia-induced retinal ganglion cell (RGC) death has been implicated in glaucomatous optic neuropathy. The aim of this study is to determine whether muscarinic receptor agonist pilocarpine, a classic antiglaucoma drug, possesses neuroprotection against cobalt chloride (CoCl(2))-mimetic hypoxia-induced apoptosis of rat retinal ganglion cells (RGC-5 cells) and its underlying mechanisms. Cell viability was determined by Cell Counting Kit-8 assay and apoptosis was examined by annexin V and mitochondrial membrane potential (MMP) assays. Expressions of hypoxia-induced factor-1 alpha (HIF-1 alpha), p53, and BNIP3 were investigated by quantitative real-time PCR and western blot analysis. After treatment of 200 microM CoCl(2) for 24 h, RGC-5 cells showed a marked decrease of cell viability by approximately 30%, increased apoptosis rate and obvious decline in MMP, which could largely be reversed by the pretreatment of 1 microM pilocarpine mainly via the activation of muscarinic receptors. Meanwhile, pretreatment of 1 microM pilocarpine could significantly prevent CoCl(2)-induced HIF-1 alpha translocation from cytoplasm to nucleus and down-regulate the expression of HIF-1 alpha, p53, and BNIP3. These studies demonstrated that pilocarpine had effective protection against hypoxia-induced apoptosis in RGCs via muscarinic receptors and HIF-1 alpha pathway. The findings suggest that HIF-1 alpha pathway as a "master switch" may be used as a therapeutic target in the cholinergic treatment of glaucoma.
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Muscarinic activation attenuates abnormal processing of beta-amyloid precursor protein induced by cobalt chloride-mimetic hypoxia in retinal ganglion cells.
Biochem. Biophys. Res. Commun.
PUBLISHED: 04-01-2009
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beta-Amyloid peptide (Abeta), the major pathological factor in Alzheimers disease, has recently been reported to be implicated in the development of glaucoma. In this study, we explored the effect of muscarinic activation on abnormal processing of beta-amyloid precursor protein (APP) induced by a risk factor hypoxia in retinal ganglion cells. Hypoxia mimetic compound cobalt chloride could increase the generation of Abeta via up-regulating the expression of APP as well as the expression of beta-secretase and gamma-secretase, whereas muscarinic receptor agonist pilocarpine could significantly attenuate this abnormal pathway, thereby resulting in a decreased amyloidogenic cleavage of APP. This finding may provide an insight into better understanding of pathophysiology for the retinal neurodegenerative disease and searching for its new modifying approach.
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Protection of PMS777, a new AChE inhibitor with PAF antagonism, against amyloid-beta-induced neuronal apoptosis and neuroinflammation.
Cell. Mol. Neurobiol.
PUBLISHED: 01-08-2009
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Amyloid-beta (Abeta) plays a central role in the neuroinflammation and cholinergic neuronal apoptosis in Alzheimers disease, and thus has been considered as a main determinant of this disease. In the previous study, we reported that PMS777, a novel bis-interacting ligand for acetylcholinesterase (AChE) inhibition and platelet-activating factor (PAF) receptor antagonism, could significantly attenuate PAF-induced neurotoxicity. Continuing our efforts, we further investigated the protective effect of PMS777 on Abeta-induced neuronal apoptosis in vitro and neuroinflammation in vivo. PMS777 (1-100 microM) was found to inhibit Abeta-induced human neuroblastoma SH-SY5Y cell apoptosis in a concentration-dependent manner. Concurrently, PMS777 increased ratio of bcl-2 to bax mRNA, and inhibited both mRNA expression and activity of caspase-3 in SH-SY5Y cells after the exposure with Abeta. In vivo experimental study demonstrated that PMS777 could attenuate Abeta-induced microglial and astrocytic activation in the rat hippocampus after systemic administration. These results suggest that PMS777 potently protects against Abeta-induced neuronal apoptosis and neuroinflammation, and warrants further investigations in connection with its potential value in the treatment of Alzheimers disease.
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Decision rules and associated sample size planning for regional approval utilizing multiregional clinical trials.
J Biopharm Stat
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Multiregional clinical trials provide the potential to make safe and effective medical products simultaneously available to patients globally. As regulatory decisions are always made in a local context, this poses huge regulatory challenges. In this article we propose two conditional decision rules that can be used for medical product approval by local regulatory agencies based on the results of a multiregional clinical trial. We also illustrate sample size planning for such trials.
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16-morpholino quaternary ammonium steroidal derivatives as neuromuscular blocking agents: synthesis, biological evaluation and in silico probe of ligand-receptor interaction.
Eur J Med Chem
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A series of steroidal 3,16-bis-quaternary ammonium salts were synthesized and screened on mouse hemi-diaphragm to explore new steroidal neuromuscular blocking agents. There were two compounds, 3?-piperidino derivate 8d (IC(50) = 3.49 ?M) and 3?-N-methylbenzylamino derivate 8g (IC(50) = 4.54 ?M), showing activity close to rocuronium (IC(50) = 2.50 ?M). The preliminary structure-activity relationship was deduced from the bioactivity results with the aid of the calculated N-N distance and log P. Meanwhile, the interactions between the ligand and binding pocket were revealed by docking 8d to the ligand binding domain of the mouse muscle nicotinic acetylcholine receptor (nAChR). This nAChR was modeled using Molecular Operating Environment (MOE) package indirectly from mollusca acetylcholine binding protein with mouse neuron ?7 nAChR as intermediary template.
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Lipid-based liquid crystalline nanoparticles as oral drug delivery vehicles for poorly water-soluble drugs: cellular interaction and in vivo absorption.
Int J Nanomedicine
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Lipid-based liquid crystalline nanoparticles (LCNPs) have attracted growing interest as novel drug-delivery systems for improving the bioavailability of both hydrophilic and hydrophobic drugs. However, their cellular interaction and in vivo behavior have not been fully developed and characterized.
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Novel bis-(-)-nor-meptazinol derivatives act as dual binding site AChE inhibitors with metal-complexing property.
Toxicol. Appl. Pharmacol.
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The strategy of dual binding site acetylcholinesterase (AChE) inhibition along with metal chelation may represent a promising direction for multi-targeted interventions in the pathophysiological processes of Alzheimers disease (AD). In the present study, two derivatives (ZLA and ZLB) of a potent dual binding site AChE inhibitor bis-(-)-nor-meptazinol (bis-MEP) were designed and synthesized by introducing metal chelating pharmacophores into the middle chain of bis-MEP. They could inhibit human AChE activity with IC(50) values of 9.63?M (for ZLA) and 8.64?M (for ZLB), and prevent AChE-induced amyloid-? (A?) aggregation with IC(50) values of 49.1?M (for ZLA) and 55.3?M (for ZLB). In parallel, molecular docking analysis showed that they are capable of interacting with both the catalytic and peripheral anionic sites of AChE. Furthermore, they exhibited abilities to complex metal ions such as Cu(II) and Zn(II), and inhibit A? aggregation triggered by these metals. Collectively, these results suggest that ZLA and ZLB may act as dual binding site AChEIs with metal-chelating potency, and may be potential leads of value for further study on disease-modifying treatment of AD.
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Penetratin-functionalized PEG-PLA nanoparticles for brain drug delivery.
Int J Pharm
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Nanoparticulate drug delivery system possesses distinct advantages for brain drug delivery. However, its amount that reach the brain is still not satisfied. Cell-penetrating peptides (CPPs), short peptides that facilitate cellular uptake of various molecular cargo, would be appropriate candidates for facilitating brain delivery of nanoparticles. However, such effect could be deprived by the rapid systemic clearance of CPPs-functionalized nanoparticles due to their positive surface charge. Penetratin (CPP with relatively low content of basic amino acids) was here functionalized to poly(ethylene glycol)-poly(lactic acid) nanoparticles (NP) to achieve desirable pharmacokinetic and biodistribution profiles for brain drug delivery. The obtained penetratin-NP showed a particle size of 100 nm and zeta potential of -4.42 mV. The surface conjugation of penetratin was confirmed by surface chemical compositions analysis via X-ray photo electron spectroscopy. In MDCK-MDR cell model, penetratin-NP presented enhanced cellular accumulation via both lipid raft-mediated endocytosis and direct translocation processes with the involvement of Golgi apparatus, lysosome and microtubules. In vivo pharmacokinetic and biodistribution studies showed that penetratin-NP exhibited a significantly enhanced brain uptake and reduced accumulation in the non-target tissues compared with low-molecular-weight protamine (CPP with high arginine content)-functionalized nanoparticles. These data strongly implicated that penetratin-NP might represent a promising brain-targeting drug delivery system. The findings also provided an important basis for the optimization of brain drug delivery systems via surface charge modulation.
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Mechanisms of transcellular transport of wheat germ agglutinin-functionalized polymeric nanoparticles in Caco-2 cells.
Biomaterials
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Transcellular transport is essential for transmucosal and plasma-to-tissue drug delivery by nanoparticles, whereas its fundamental pathways have not been fully clarified. In this study, an in-depth investigation was conducted into the intracellular itinerary and the transcytosis pathway of wheat germ agglutinin-functionalized nanoparticles (WGA-NP) with various polymer architectures in the Caco-2 cell model. GFP-Rabs, Rab4, Rab5, Rab7, Rab11, GTPases served as key regulators of vesicular transport, and their mutants were transfected to Caco-2 cells respectively to determine the cellular itinerary of WGA-NP and the role of Rabs therein. Transcytosis inhibition experiments indicated that transcellular transport of WGA-NP (PEG(3000)-PLA(40000) formulation) happened in a cytoskeleton-dependent manner and majorly by means of clathrin-mediated mechanism. Intracellular transport, especially the endolysosome pathway was found largely contribute to the transcytosis of WGA-NP. WGA-NP with shorter surface PEG length (2000) resulted in higher cellular association and more colocalization with the clathrin-mediated transport pathway, while that with longer surface PEG length (5000) avoided the clathrin-mediated transport pathway but achieved higher transcytosis after 4 h incubation. WGA-NP with PLGA as the core materials obtained elevated lysosome escape and enhanced transcytosis after 2 h incubation. These findings provided important evidence for the role of polymer architectures in modulating cellular transport of functionalized nanocarriers, and would be helpful in improving carrier design to enhance drug delivery.
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N-acetylcysteine protects against hypoxia mimetic-induced autophagy by targeting the HIF-1? pathway in retinal ganglion cells.
Cell. Mol. Neurobiol.
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Hypoxia-induced retinal ganglion cell (RGC) death has been proposed to be the critical event in the pathophysiology of glaucoma. Therefore, delaying or halting RGC degeneration, known as neuroprotection, is a novel and promising approach with potential clinical applications for treating glaucoma. In this study, we investigate hypoxia-induced cell death of RGCs and the underlying mechanisms of N-acetylcysteine (NAC) as a neuroprotectant. To establish a model for chemical hypoxia-induced cell death, RGC-5 cells were treated with the hypoxia mimetic cobalt chloride (CoCl2). Following CoCl2 exposure, significant levels of apoptotic and autophagic cell death were observed in RGC-5 cells, evidenced by lysosome dysfunction and autophagosome formation. Pretreating RGC-5 cells with NAC significantly counteracted the autophagic cell death. NAC-mediated neuroprotection was attributed to the direct scavenging of reactive oxygen species and was mediated by targeting the hypoxia-inducible factor-1? pathway via the BNIP3 and PI3K/Akt/mTOR pathways. These results provide insights into the degeneration of RGCs and present a potential clinical application for NAC as a neuroprotectant.
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Interpreting the structural mechanism of action for MT7 and human muscarinic acetylcholine receptor 1 complex by modeling protein-protein interaction.
J. Biomol. Struct. Dyn.
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MT7 is a selective human muscarinic acetylcholine receptor 1 (hM1) allosteric binder with subnanomolar affinity. Understanding the binding mode of hM1-MT7 will give insights to discover small molecular ligand for hM1. MT7 is a peptide, and hM1 is a G-protein-coupled membrane receptor. Therefore, we have employed homology modeling, protein-protein docking, explicit membrane molecular dynamics (MD) simulations, and molecular mechanic/Poisson-Boltzmann surface area energy decomposition analysis approaches to reveal the hM1-MT7 binding mode. The binding mode is consistent with the experimental data. We have discovered that the binding mode consists of three interaction regions in five residue interaction clusters. By analyzing the cluster representative structures, the cluster residues form an interaction network, which shows a multiple-point-to-site binding mode. Hydrogen binding statistical analysis reveals that E170 (hM1) and R34 (MT7) are both locked in electrostatic cages with counter charges, respectively. This is confirmed by the dynamic distances calculation between these residues, and biological mutant experiments.
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The newly identified K+ channel blocker talatisamine attenuates beta-amyloid oligomers induced neurotoxicity in cultured cortical neurons.
Neurosci. Lett.
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Loss of cytosolic K(+) through up-regulated delayed rectifier K(+) channels play an important role in beta-amyloid (A?) induced neurotoxicity. Potent K(+) channel blocker, particular specific for I(K) channels has been suggested as an attractive candidate for the treatment of Alzheimers disease (AD). Talatisamine is a novel I(K) channel blocker discovered by virtual screening and electrophysiological characterization. In the present study, we examined the neuroprotective effect of talatisamine against A? oligomers induced cytotoxicity in primarily cultured cortical neurons. The neurotoxicity related to K(+) loss caused by A?40 oligomers included enhanced I(K) density, increased cell membrane permeability, reduced cell viability, and impaired mitochondrial transmembrane potential. Decreased Bcl-2 and increased Bax level, activation of Caspase-3 and Caspase-9 were also observed after A?40 oligomers incubation. Talatisamine (120 ?M) and TEA (5mM) inhibited the enhanced I(K) caused by A?40 oligomers, attenuated cytotoxicity of A? oligomers by restoring cell viability and suppressing K(+) loss related apoptotic response. Our results suggested that talatisamine may become a leading compound as I(K) channel blocker for neuroprotection.
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On the value of homology models for virtual screening: discovering hCXCR3 antagonists by pharmacophore-based and structure-based approaches.
J Chem Inf Model
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Human chemokine receptor CXCR3 (hCXCR3) antagonists have potential therapeutic applications as antivirus, antitumor, and anti-inflammatory agents. A novel virtual screening protocol, which combines pharmacophore-based and structure-based approaches, was proposed. A three-dimensional QSAR pharmacophore model and a structure-based docking model were built to virtually screen for hCXCR3 antagonists. The hCXCR3 antagonist binding site was constructed by homology modeling and molecular dynamics (MD) simulation. By combining the structure-based and ligand-based screenings results, 95% of the compounds satisfied either pharmacophore or docking score criteria and would be chosen as hits if the union of the two searches was taken. The false negative rates were 15% for the pharmacophore model, 14% for the homology model, and 5% for the combined model. Therefore, the consistency of the pharmacophore model and the structural binding model is 219/273 = 80%. The hit rate for the virtual screening protocol is 273/286 = 95%. This work demonstrated that the quality of both the pharmacophore model and homology model can be measured by the consistency of the two models, and the false negatives in virtual screening can be reduced by combining two virtual screening approaches.
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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.