The Experts below are selected from a list of 1452 Experts worldwide ranked by ideXlab platform
Bradley T Hyman - One of the best experts on this subject based on the ideXlab platform.
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In Vivo Multiphoton Imaging of a Transgenic Mouse Model of Alzheimer Disease Reveals Marked Thioflavine-S-Associated Alterations in Neurite Trajectories
Journal of neuropathology and experimental neurology, 2003Co-Authors: J. D. D'amore, Stephen T Kajdasz, Brian J Bacskai, Megan E. Mclellan, Edward A. Stern, Bradley T HymanAbstract:Postmortem analyses of senile plaques reveal numerous dystrophic processes in their vicinity. We used in vivo multiphoton microscopy of a transgenic model of Alzheimer disease (AD) to simultaneously image senile plaques and nearby neuronal processes. Plaques were labeled by immunofluorescent staining or Thioflavine-S and neuronal processes were labeled with a fluorescent dextran conjugate. Imaging of 3-dimensional volumes in the vicinity of plaques revealed subtle changes in neurite geometry in or near diffuse plaques. By contrast, disruptions in neurite morphology, including dystrophic neurites immediately surrounding plaques as well as major alterations in neurite trajectories, were seen in association with Thioflavine-S-positive plaques. Nearly half of all labeled processes that came within 50 m mo f a Thioflavine-S-positive plaque were altered, suggesting a fairly large ''halo'' of neuropil alterations that extend beyond the discrete border of a Thioflavine-S plaque. These results support the hypothesis that compact Thioflavine-S-positive plaques disrupt the neuropil in AD.
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Plaque-induced abnormalities in neurite geometry in transgenic models of Alzheimer disease: implications for neural system disruption.
Journal of neuropathology and experimental neurology, 2001Co-Authors: Luis Cruz, Brigita Urbanc, Roger B. Knowles, Karen K. Hsiao-ashe, Karen Duff, Michael C. Irizarry, H. Eugene Stanley, Bradley T HymanAbstract:Neurites that pass through amyloid-s deposits in Alzheimer disease (AD) undergo 3 changes: they develop phosphorylated tau immunoreactivity; the density of SMI-32-positive dendrites diminishes; and they also develop a marked alteration in their geometric features, changing from being nearly straight to being quite curvy. The extent to which the latter 2 phenomena are related to phosphorylated tau is unknown. We have now examined whether amyloid-s deposits in APP695Sw transgenic mice, which have only rare phosphorylated tau containing neurites, develop these changes. We found that dendritic density is diminished within the boundaries of amyloid-s plaques, with the greatest loss (about 80%, p , 0.001) within the boundaries of Thioflavine S cores. Remaining dendrites within plaques develop substantial morphological alterations quanti- tatively similar to those seen in AD. A statistically significant but smaller degree of change in geometry was seen in the immediate vicinity around plaques, suggesting a propagation of cytoskeletal disruption from the center of the plaque outward. We examined the possible physiological consequences of this change in dendritic geometry using a standard cable-theory model. We found a predicted delay of several milliseconds in about one quarter of the dendrites passing through a Thioflavine S plaque. These results are consistent with previous observations in AD, and suggest that Thioflavine S-positive amyloid-s deposits have a marked effect on dendritic microarchitecture in the cortex, even in the relative absence of phosphorylated tau alterations.
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growth arrest of individual senile plaques in a model of alzheimer s disease observed by in vivo multiphoton microscopy
The Journal of Neuroscience, 2001Co-Authors: Richard H Christie, Stephen T Kajdasz, Rebecca M. Williams, Warren R. Zipfel, Brian J Bacskai, Watt W. Webb, Bradley T HymanAbstract:In Alzheimer's disease, amyloid-β peptide aggregates in the extracellular space to form senile plaques. The process of plaque deposition and growth has been modeled on the basis of in vitro experiments in ways that lead to divergent predictions: either a diffusion-limited growth model in which plaques grow by first-order kinetics, or a dynamic model of continual deposition and asymmetrical clearance in which plaques reach a stable size and stop growing but evolve morphologically over time. The models have not been tested in vivo because plaques are too small (by several orders of magnitude) for conventional imaging modalities. We now report in vivo multiphoton laser scanning imaging of Thioflavine S-stained senile plaques in the Tg2576 transgenic mouse model of Alzheimer's disease to test these biophysical models and show that there is no detectable change in plaque size over extended periods of time. Qualitatively, geometric features remain unchanged over time in the vast majority of the 349 plaques imaged and re-imaged. Intervals as long as 5 months were obtained. Nonetheless, rare examples of growth or shrinkage of individual plaques do occur, and new plaques appear between imaging sessions. These results indicate that Thioflavine S-positive plaques appear and then are stable, supporting a dynamic feedback model of plaque growth.
Haitham Ahmed Shaban - One of the best experts on this subject based on the ideXlab platform.
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polarized super resolution structural imaging inside amyloid fibrils using Thioflavine t
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Julien Savatier, Cesar Augusto Valadescruz, Sophie BrasseletAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils.
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Polarized super-resolution structural imaging inside amyloid fibrils using Thioflavine T
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Cesar Valades Cruz, Sophie Brasselet, Julien SavatierAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils. Amyloid aggregates, which originate from protein misfolding as a starting point for aggregation and plaque formations , are known to be at the origin of crucial processes responsible for neurodegenerative diseases. Thioflavin T (ThT), a small benzothiazole fluorescent compound, is commonly used for imaging amyloid fibrils by exploiting its capacity to generate high fluorescence emission when bound to amyloid in specific sites 1. Fluorescence-based optical imaging techniques have used ThT to study the formation and growth processes of amyloid fibrils 2,3 , as well as for the diagnosis of plaque formation in diseases related to protein disorder 4,5. Moreover, fluorescence ani-sotropy and fluorescence polarized microscopy have evidenced the high orientational order of ThT in amyloids and its ability to report indirectly the organization and structure of fibrils in vitro 6–8. Although fluorescence optical imaging is a powerful tool to gain insight into the formation and the aggrega-tion of amyloids, it is still limited to spatial scales of the order of the optical diffraction limit, e.g. about 200 nm. This resolution scale is however inappropriate for monitoring the supra-molecular architecture of the amyloid aggregates, which size is around 10–100 nm from electron and atomic force microscopies 9,10. Individual filaments made of repeated β-sheets are known in particular to arrange into protofilaments that twist around each other in a helical ribbon, which pitch size varies depending on the number of filaments involved 8. Accessing such scales in non-invasive and ideally in-vivo conditions is essential for understanding the molecular mechanisms responsible for the formation of amyloids and their functional consequences in neurodegenerative diseases. Super resolution imaging based on single molecule localization has recently brought a determining step to overcome this limitation, using the stochastic nature of emission from isolated molecules localized with nano-metric accuracy 11,12. Direct Stochastic Optical Reconstruction Microscopy (dSTORM) uses in particular the capacity of fluorophores to photoswitch from dark to bright fluorescence states, at a rate accessible in imaging conditions 13. This method has been used to study the high resolution morphology and aggregates formation of different types of amyloids such as amyloid beta (Aβ) 14,15 ,α-synuclein 16–18 and Huntingtin protein 19–21 , in both in vivo conditions and in fixed cells, with a resolution down to 20 nm. These approaches however have so far relied on either immunolabeling of the amyloid fibrils or the covalent binding of monomeric proteins by fluorescent organic dye. Immunolabeling reports only apparent fibrils organization due to the non-negligible size of the
Julien Savatier - One of the best experts on this subject based on the ideXlab platform.
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polarized super resolution structural imaging inside amyloid fibrils using Thioflavine t
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Julien Savatier, Cesar Augusto Valadescruz, Sophie BrasseletAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils.
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Polarized super-resolution structural imaging inside amyloid fibrils using Thioflavine T
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Cesar Valades Cruz, Sophie Brasselet, Julien SavatierAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils. Amyloid aggregates, which originate from protein misfolding as a starting point for aggregation and plaque formations , are known to be at the origin of crucial processes responsible for neurodegenerative diseases. Thioflavin T (ThT), a small benzothiazole fluorescent compound, is commonly used for imaging amyloid fibrils by exploiting its capacity to generate high fluorescence emission when bound to amyloid in specific sites 1. Fluorescence-based optical imaging techniques have used ThT to study the formation and growth processes of amyloid fibrils 2,3 , as well as for the diagnosis of plaque formation in diseases related to protein disorder 4,5. Moreover, fluorescence ani-sotropy and fluorescence polarized microscopy have evidenced the high orientational order of ThT in amyloids and its ability to report indirectly the organization and structure of fibrils in vitro 6–8. Although fluorescence optical imaging is a powerful tool to gain insight into the formation and the aggrega-tion of amyloids, it is still limited to spatial scales of the order of the optical diffraction limit, e.g. about 200 nm. This resolution scale is however inappropriate for monitoring the supra-molecular architecture of the amyloid aggregates, which size is around 10–100 nm from electron and atomic force microscopies 9,10. Individual filaments made of repeated β-sheets are known in particular to arrange into protofilaments that twist around each other in a helical ribbon, which pitch size varies depending on the number of filaments involved 8. Accessing such scales in non-invasive and ideally in-vivo conditions is essential for understanding the molecular mechanisms responsible for the formation of amyloids and their functional consequences in neurodegenerative diseases. Super resolution imaging based on single molecule localization has recently brought a determining step to overcome this limitation, using the stochastic nature of emission from isolated molecules localized with nano-metric accuracy 11,12. Direct Stochastic Optical Reconstruction Microscopy (dSTORM) uses in particular the capacity of fluorophores to photoswitch from dark to bright fluorescence states, at a rate accessible in imaging conditions 13. This method has been used to study the high resolution morphology and aggregates formation of different types of amyloids such as amyloid beta (Aβ) 14,15 ,α-synuclein 16–18 and Huntingtin protein 19–21 , in both in vivo conditions and in fixed cells, with a resolution down to 20 nm. These approaches however have so far relied on either immunolabeling of the amyloid fibrils or the covalent binding of monomeric proteins by fluorescent organic dye. Immunolabeling reports only apparent fibrils organization due to the non-negligible size of the
Sophie Brasselet - One of the best experts on this subject based on the ideXlab platform.
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polarized super resolution structural imaging inside amyloid fibrils using Thioflavine t
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Julien Savatier, Cesar Augusto Valadescruz, Sophie BrasseletAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils.
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Polarized super-resolution structural imaging inside amyloid fibrils using Thioflavine T
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Cesar Valades Cruz, Sophie Brasselet, Julien SavatierAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils. Amyloid aggregates, which originate from protein misfolding as a starting point for aggregation and plaque formations , are known to be at the origin of crucial processes responsible for neurodegenerative diseases. Thioflavin T (ThT), a small benzothiazole fluorescent compound, is commonly used for imaging amyloid fibrils by exploiting its capacity to generate high fluorescence emission when bound to amyloid in specific sites 1. Fluorescence-based optical imaging techniques have used ThT to study the formation and growth processes of amyloid fibrils 2,3 , as well as for the diagnosis of plaque formation in diseases related to protein disorder 4,5. Moreover, fluorescence ani-sotropy and fluorescence polarized microscopy have evidenced the high orientational order of ThT in amyloids and its ability to report indirectly the organization and structure of fibrils in vitro 6–8. Although fluorescence optical imaging is a powerful tool to gain insight into the formation and the aggrega-tion of amyloids, it is still limited to spatial scales of the order of the optical diffraction limit, e.g. about 200 nm. This resolution scale is however inappropriate for monitoring the supra-molecular architecture of the amyloid aggregates, which size is around 10–100 nm from electron and atomic force microscopies 9,10. Individual filaments made of repeated β-sheets are known in particular to arrange into protofilaments that twist around each other in a helical ribbon, which pitch size varies depending on the number of filaments involved 8. Accessing such scales in non-invasive and ideally in-vivo conditions is essential for understanding the molecular mechanisms responsible for the formation of amyloids and their functional consequences in neurodegenerative diseases. Super resolution imaging based on single molecule localization has recently brought a determining step to overcome this limitation, using the stochastic nature of emission from isolated molecules localized with nano-metric accuracy 11,12. Direct Stochastic Optical Reconstruction Microscopy (dSTORM) uses in particular the capacity of fluorophores to photoswitch from dark to bright fluorescence states, at a rate accessible in imaging conditions 13. This method has been used to study the high resolution morphology and aggregates formation of different types of amyloids such as amyloid beta (Aβ) 14,15 ,α-synuclein 16–18 and Huntingtin protein 19–21 , in both in vivo conditions and in fixed cells, with a resolution down to 20 nm. These approaches however have so far relied on either immunolabeling of the amyloid fibrils or the covalent binding of monomeric proteins by fluorescent organic dye. Immunolabeling reports only apparent fibrils organization due to the non-negligible size of the
Cesar Augusto Valadescruz - One of the best experts on this subject based on the ideXlab platform.
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polarized super resolution structural imaging inside amyloid fibrils using Thioflavine t
Scientific Reports, 2017Co-Authors: Haitham Ahmed Shaban, Julien Savatier, Cesar Augusto Valadescruz, Sophie BrasseletAbstract:Thioflavin T (ThT) is standardly used as a fluorescent marker to detect aggregation of amyloid fibrils by conventional fluorescence microscopy, including polarization resolved imaging that brings information on the orientational order of the fibrils. These techniques are however diffraction limited and cannot provide fine structural details at the fibrils scales of 10–100 nm, which lie beyond the diffraction limit. In this work, we evaluate the capacity of ThT to photoswitch when bound to insulin amyloids by adjusting the redox properties of its environment. We demonstrate that on-off duty cycles, intensity and photostability of the ThT fluorescence emission under adequate buffer conditions permit stochastic super-resolution imaging with a localization precision close to 20 nm. We show moreover that signal to noise conditions allow polarized orientational imaging of single ThT molecules, which reveals ultra-structure signatures related to protofilaments twisting within amyloid fibrils.