The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform

Alain Chédotal - One of the best experts on this subject based on the ideXlab platform.

  • Nkx2.1-derived astrocytes and neurons together with Slit2 are indispensable for anterior Commissure formation
    Nature Communications, 2015
    Co-Authors: Shilpi Minocha, Delphine Valloton, Athena R. Ypsilanti, Hubert Fiumelli, Elizabeth A. Allen, Yuchio Yanagawa, Oscar Marin, Alain Chédotal, Jean-pierre Hornung, Cécile Lebrand
    Abstract:

    Guidepost cells present at and surrounding the midline provide guidance cues that orient the growing axons through Commissures. Here we show that the transcription factor Nkx2.1 known to control the specification of GABAergic interneurons also regulates the differentiation of astroglia and polydendrocytes within the mouse anterior Commissure (AC). Nkx2.1-positive glia were found to originate from three germinal regions of the ventral telencephalon. Nkx2.1-derived glia were observed in and around the AC region by E14.5. Thereafter, a selective cell ablation strategy showed a synergistic role of Nkx2.1-derived cells, both GABAergic interneurons and astroglia, towards the proper formation of the AC. Finally, our results reveal that the Nkx2.1-regulated cells mediate AC axon guidance through the expression of the repellent cue, Slit2. These results bring forth interesting insights about the spatial and temporal origin of midline telencephalic glia, and highlight the importance of neurons and astroglia towards the formation of midline Commissures. Guidepost cells provide guidance cues that orient growing axons in the brain but little is known about the midline guidepost cells that populate the mouse anterior Commissure (AC). Here, the authors show that the transcription factor Nkx2.1 regulates the differentiation of astroglia and neurons that cooperate to guide AC axons through the expression of Slit2.

  • nkx2 1 derived astrocytes and neurons together with slit2 are indispensable for anterior Commissure formation
    Nature Communications, 2015
    Co-Authors: Shilpi Minocha, Delphine Valloton, Athena R. Ypsilanti, Hubert Fiumelli, Yuchio Yanagawa, Oscar Marin, Alain Chédotal, Elizabeth Allen
    Abstract:

    Guidepost cells present at and surrounding the midline provide guidance cues that orient the growing axons through Commissures. Here we show that the transcription factor Nkx2.1 known to control the specification of GABAergic interneurons also regulates the differentiation of astroglia and polydendrocytes within the mouse anterior Commissure (AC). Nkx2.1-positive glia were found to originate from three germinal regions of the ventral telencephalon. Nkx2.1-derived glia were observed in and around the AC region by E14.5. Thereafter, a selective cell ablation strategy showed a synergistic role of Nkx2.1-derived cells, both GABAergic interneurons and astroglia, towards the proper formation of the AC. Finally, our results reveal that the Nkx2.1-regulated cells mediate AC axon guidance through the expression of the repellent cue, Slit2. These results bring forth interesting insights about the spatial and temporal origin of midline telencephalic glia, and highlight the importance of neurons and astroglia towards the formation of midline Commissures.

Alan Peters - One of the best experts on this subject based on the ideXlab platform.

  • disrupted myelin and axon loss in the anterior Commissure of the aged rhesus monkey
    The Journal of Comparative Neurology, 2003
    Co-Authors: Julie H Sandell, Alan Peters
    Abstract:

    This study assesses the effects of age on the composition of the anterior Commissure of the rhesus monkey. The anterior Commissures of nine young (5–10 years), five middle-aged (15–20 years), and eight old (25–35 years) monkeys were examined by light and electron microscopy. In all, 90 –95% of the nerve fibers in the anterior Commissure are myelinated. With age, the structure of the myelin sheaths of some nerve fibers is altered. Some of the axons also show signs of degeneration and this leads to a loss of nerve fibers. Thus, in young and the middle-aged monkeys the mean number of myelinated nerve fibers in the anterior Commissure is 2.2 10 6 , while in the old monkeys the mean is 1.2 10 6 . Increasing age is correlated with a reduction in the number of myelinated nerve fibers in the anterior Commissure, an increase in the frequency of structural alterations in myelin sheaths, and an increase in the frequency of occurrence of degenerating axons. However, the number of myelinated nerve fibers is the only variable that correlates with cognition: in monkeys 5–20 years of age the fewer the number of nerve fibers the poorer the cognitive performance, as measured by our Cognitive Impairment Index (CII). The most common neuroglial cells in the anterior Commissure are oligodendrocytes. They account for 86% of all neuroglial cell profiles, while astrocytes account for 9%, and microglial cells for 5% of profiles. There is no apparent change with age in the total numbers of neuroglial cells, although as they age each of the neuroglial cell types acquires some inclusions in their cytoplasm. The data, together with those from previous studies, support the concept that in aging there is a ubiquitous loss of myelinated nerve fibers from the brain and that fiber loss is preceded by alterations in the structure of many of the myelin sheaths. J. Comp. Neurol. 466:14 –30, 2003. © 2003 Wiley-Liss, Inc. Indexing terms: aging; primate; astrocyte; oligodendrocyte; microglia; electron microscopy; axon; nerve fibers

Shilpi Minocha - One of the best experts on this subject based on the ideXlab platform.

  • Nkx2.1-derived astrocytes and neurons together with Slit2 are indispensable for anterior Commissure formation
    Nature Communications, 2015
    Co-Authors: Shilpi Minocha, Delphine Valloton, Athena R. Ypsilanti, Hubert Fiumelli, Elizabeth A. Allen, Yuchio Yanagawa, Oscar Marin, Alain Chédotal, Jean-pierre Hornung, Cécile Lebrand
    Abstract:

    Guidepost cells present at and surrounding the midline provide guidance cues that orient the growing axons through Commissures. Here we show that the transcription factor Nkx2.1 known to control the specification of GABAergic interneurons also regulates the differentiation of astroglia and polydendrocytes within the mouse anterior Commissure (AC). Nkx2.1-positive glia were found to originate from three germinal regions of the ventral telencephalon. Nkx2.1-derived glia were observed in and around the AC region by E14.5. Thereafter, a selective cell ablation strategy showed a synergistic role of Nkx2.1-derived cells, both GABAergic interneurons and astroglia, towards the proper formation of the AC. Finally, our results reveal that the Nkx2.1-regulated cells mediate AC axon guidance through the expression of the repellent cue, Slit2. These results bring forth interesting insights about the spatial and temporal origin of midline telencephalic glia, and highlight the importance of neurons and astroglia towards the formation of midline Commissures. Guidepost cells provide guidance cues that orient growing axons in the brain but little is known about the midline guidepost cells that populate the mouse anterior Commissure (AC). Here, the authors show that the transcription factor Nkx2.1 regulates the differentiation of astroglia and neurons that cooperate to guide AC axons through the expression of Slit2.

  • nkx2 1 derived astrocytes and neurons together with slit2 are indispensable for anterior Commissure formation
    Nature Communications, 2015
    Co-Authors: Shilpi Minocha, Delphine Valloton, Athena R. Ypsilanti, Hubert Fiumelli, Yuchio Yanagawa, Oscar Marin, Alain Chédotal, Elizabeth Allen
    Abstract:

    Guidepost cells present at and surrounding the midline provide guidance cues that orient the growing axons through Commissures. Here we show that the transcription factor Nkx2.1 known to control the specification of GABAergic interneurons also regulates the differentiation of astroglia and polydendrocytes within the mouse anterior Commissure (AC). Nkx2.1-positive glia were found to originate from three germinal regions of the ventral telencephalon. Nkx2.1-derived glia were observed in and around the AC region by E14.5. Thereafter, a selective cell ablation strategy showed a synergistic role of Nkx2.1-derived cells, both GABAergic interneurons and astroglia, towards the proper formation of the AC. Finally, our results reveal that the Nkx2.1-regulated cells mediate AC axon guidance through the expression of the repellent cue, Slit2. These results bring forth interesting insights about the spatial and temporal origin of midline telencephalic glia, and highlight the importance of neurons and astroglia towards the formation of midline Commissures.

Takahiro Shiota - One of the best experts on this subject based on the ideXlab platform.

  • geometric changes of mitral annulus assessed by real time 3 dimensional echocardiography becoming enlarged and less nonplanar in the anteroposterior direction during systole in proportion to global left ventricular systolic function
    Journal of The American Society of Echocardiography, 2004
    Co-Authors: Jun Kwan, Zoran B Popovic, Deborah A Agler, James D Thomas, Takahiro Shiota
    Abstract:

    Objective We sought to investigate the geometric changes of the mitral annulus during systole in relation to global left ventricular (LV) systolic function using real-time 3-dimensional (3D) echocardiography. Methods Real-time 3D echocardiography was performed in 23 patients with global LV systolic dysfunction with ejection fraction of 37 ± 19% and 9 control subjects with ejection fraction of 62 ± 4%. Volumetric data were divided into 9 rotational apical planes (angle increment=20 degrees) using 3D software. Nine rotational annular dimensions (ADs) were measured in all planes in early and late systole. Nonplanar angle (NPA) of the annulus between two vectors from two hinge points of the annulus in the anteroposterior plane to the center between two Commissures in the Commissure-Commissure plane was measured during early and late systole. Fractional changes of NPA and AD were defined as changes in percentage during systole. Results NPA significantly increased during systole (early, 145 ± 12 degrees; late, 160 ± 9 degrees; P R 2 = 0.87, P R 2 = 0.85, P Conclusions Real-time 3D echocardiography demonstrated that saddle shape of the mitral annulus was getting enlarged and less nonplanar mainly in the anteroposterior direction during systole. These geometric changes were proportional to the global LV systolic function.

Julie H Sandell - One of the best experts on this subject based on the ideXlab platform.

  • disrupted myelin and axon loss in the anterior Commissure of the aged rhesus monkey
    The Journal of Comparative Neurology, 2003
    Co-Authors: Julie H Sandell, Alan Peters
    Abstract:

    This study assesses the effects of age on the composition of the anterior Commissure of the rhesus monkey. The anterior Commissures of nine young (5–10 years), five middle-aged (15–20 years), and eight old (25–35 years) monkeys were examined by light and electron microscopy. In all, 90 –95% of the nerve fibers in the anterior Commissure are myelinated. With age, the structure of the myelin sheaths of some nerve fibers is altered. Some of the axons also show signs of degeneration and this leads to a loss of nerve fibers. Thus, in young and the middle-aged monkeys the mean number of myelinated nerve fibers in the anterior Commissure is 2.2 10 6 , while in the old monkeys the mean is 1.2 10 6 . Increasing age is correlated with a reduction in the number of myelinated nerve fibers in the anterior Commissure, an increase in the frequency of structural alterations in myelin sheaths, and an increase in the frequency of occurrence of degenerating axons. However, the number of myelinated nerve fibers is the only variable that correlates with cognition: in monkeys 5–20 years of age the fewer the number of nerve fibers the poorer the cognitive performance, as measured by our Cognitive Impairment Index (CII). The most common neuroglial cells in the anterior Commissure are oligodendrocytes. They account for 86% of all neuroglial cell profiles, while astrocytes account for 9%, and microglial cells for 5% of profiles. There is no apparent change with age in the total numbers of neuroglial cells, although as they age each of the neuroglial cell types acquires some inclusions in their cytoplasm. The data, together with those from previous studies, support the concept that in aging there is a ubiquitous loss of myelinated nerve fibers from the brain and that fiber loss is preceded by alterations in the structure of many of the myelin sheaths. J. Comp. Neurol. 466:14 –30, 2003. © 2003 Wiley-Liss, Inc. Indexing terms: aging; primate; astrocyte; oligodendrocyte; microglia; electron microscopy; axon; nerve fibers