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  • 1
    Online Resource
    Online Resource
    Wiley ; 2012
    In:  International Journal for Numerical Methods in Biomedical Engineering Vol. 28, No. 10 ( 2012-10), p. 1003-1014
    In: International Journal for Numerical Methods in Biomedical Engineering, Wiley, Vol. 28, No. 10 ( 2012-10), p. 1003-1014
    Abstract: Muscle coordination may be difficult or impossible to predict accurately based on biomechanical considerations alone because of redundancy in the musculoskeletal system. Because many solutions exist for any given movement, the role of the nervous system in further constraining muscle coordination patterns for movement must be considered in both healthy and impaired motor control. On the basis of computational neuromechanical analyses of experimental data combined with modeling techniques, we have demonstrated several such neural constraints on the temporal and spatial patterns of muscle activity during both locomotion and postural responses to balance perturbations. We hypothesize that subject‐specific and trial‐by‐trial differences in muscle activation can be parameterized and understood by a hierarchical and low‐dimensional framework that reflects the neural control of task‐level goals. In postural control, we demonstrate that temporal patterns of muscle activity may be governed by feedback control of task‐level variables that represent the overall goal‐directed motion of the body. These temporal patterns then recruit spatially‐fixed patterns of muscle activity called muscle synergies that produce the desired task‐level biomechanical functions that require multijoint coordination. Moreover, these principles apply more generally to movement, and in particular to locomotor tasks in both healthy and impaired individuals. Overall, understanding the goals and organization of the neural control of movement may provide useful reduced dimension parameter sets to address the degrees‐of‐freedom problem in musculoskeletal movement control. More importantly, however, neuromechanical analyses may lend insight and provide a framework for understanding subject‐specific and trial‐by‐trial differences in movement across both healthy and motor‐impaired populations. Copyright © 2012 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 2040-7939 , 2040-7947
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2012
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  • 2
    In: Journal of Pharmacological and Toxicological Methods, Elsevier BV, Vol. 99 ( 2019-09), p. 106595-
    Type of Medium: Online Resource
    ISSN: 1056-8719
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2019
    detail.hit.zdb_id: 1105919-9
    SSG: 15,3
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  • 3
    Online Resource
    Online Resource
    American Physiological Society ; 2011
    In:  Journal of Neurophysiology Vol. 106, No. 2 ( 2011-08), p. 999-1015
    In: Journal of Neurophysiology, American Physiological Society, Vol. 106, No. 2 ( 2011-08), p. 999-1015
    Abstract: We investigated muscle activity, ground reaction forces, and center of mass (CoM) acceleration in two different postural behaviors for standing balance control in humans to determine whether common neural mechanisms are used in different postural tasks. We compared nonstepping responses, where the base of support is stationary and balance is recovered by returning CoM back to its initial position, with stepping responses, where the base of support is enlarged and balance is recovered by pushing the CoM away from the initial position. In response to perturbations of the same direction, these two postural behaviors resulted in different muscle activity and ground reaction forces. We hypothesized that a common pool of muscle synergies producing consistent task-level biomechanical functions is used to generate different postural behaviors. Two sets of support-surface translations in 12 horizontal-plane directions were presented, first to evoke stepping responses and then to evoke nonstepping responses. Electromyographs in 16 lower back and leg muscles of the stance leg were measured. Initially (∼100-ms latency), electromyographs, CoM acceleration, and forces were similar in nonstepping and stepping responses, but these diverged in later time periods (∼200 ms), when stepping occurred. We identified muscle synergies using non-negative matrix factorization and functional muscle synergies that quantified correlations between muscle synergy recruitment levels and biomechanical outputs. Functional muscle synergies that produce forces to restore CoM position in nonstepping responses were also used to displace the CoM during stepping responses. These results suggest that muscle synergies represent common neural mechanisms for CoM movement control under different dynamic conditions: stepping and nonstepping postural responses.
    Type of Medium: Online Resource
    ISSN: 0022-3077 , 1522-1598
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2011
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  • 4
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2019-08-15)
    Abstract: The cardiac action potential (AP) is vital for understanding healthy and diseased cardiac biology and drug safety testing. However, techniques for high throughput cardiac AP measurements have been limited. Here, we introduce a novel technique for reliably increasing the coupling of cardiomyocyte syncytium to planar multiwell microelectrode arrays, resulting in a stable, label-free local extracellular action potential (LEAP). We characterized the reliability and stability of LEAP, its relationship to the field potential, and its efficacy for quantifying AP morphology of human induced pluripotent stem cell derived and primary rodent cardiomyocytes. Rise time, action potential duration, beat period, and triangulation were used to quantify compound responses and AP morphology changes induced by genetic modification. LEAP is the first high throughput, non-invasive, label-free, stable method to capture AP morphology from an intact cardiomyocyte syncytium. LEAP can accelerate our understanding of stem cell models, while improving the automation and accuracy of drug testing.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
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  • 5
    In: Cell Reports, Elsevier BV, Vol. 36, No. 5 ( 2021-08), p. 109479-
    Type of Medium: Online Resource
    ISSN: 2211-1247
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
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  • 6
    In: Clinical Neurophysiology, Elsevier BV, Vol. 125, No. 10 ( 2014-10), p. 2024-2035
    Type of Medium: Online Resource
    ISSN: 1388-2457
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
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  • 7
    In: Journal of Pharmacological and Toxicological Methods, Elsevier BV, Vol. 93 ( 2018-09), p. 117-
    Type of Medium: Online Resource
    ISSN: 1056-8719
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2018
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    SSG: 15,3
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  • 8
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2021
    In:  Cancer Research Vol. 81, No. 13_Supplement ( 2021-07-01), p. 1552-1552
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 81, No. 13_Supplement ( 2021-07-01), p. 1552-1552
    Abstract: Glioblastoma (GBM) is an aggressive form of brain cancer that has no effective treatments and a prognosis of only 12-18 months. Immune effector T cells are a promising therapy due to their innate cytotoxicity. In addition, engineering chimeric antigen receptors (CAR) to target tumor-associated or neo-antigens can lend high specificity. The ability to assess the efficacy and potency of such T cell therapies in vitro at high throughputs is vital for the preclinical development of these promising therapies. Cellular impedance assays offer a sensitive, non-destructive, and label-free method to continuously monitor cancer cell proliferation and immune cell-mediated cytotoxicity in real-time, revealing not only the potency but also the kinetics of T cell killing. Here, we used co-culture to compare the cytolytic potency and kinetics of naïve activated T Cells and targeted GD2 CAR-T cells against glioma stem cells (GSC), a subpopulation of glioblastoma cells. Patient-derived N08 GSCs were plated at 50k cells per well on a PEI and laminin-coated CytoView-Z 96-well plates, and their impedance was continuously monitored on the Maestro Z impedance platform (Axion BioSystems). After 48 hours, human naïve activated T Cells (ImmunoCult CD3/CD28 activation media) or GD2 CAR-T cells were added at varying effector:target ratios ranging from 0.1:1 to 10:1. Impedance and cytolysis were subsequently monitored for up to 7 days. The addition of activated T Cells or GD2 CAR-T Cells resulted in cell swelling, followed by a decrease in impedance consistent with T cell-mediated lysis of GSCs. GD-2 CAR-T Cells resulted in a significantly higher percent cytolysis of GSCs compared to naïve activated T Cells after 7 days of exposure. In addition, the kill time 50, defined as the time to reach 50% cytolysis of target cells, was shorter for GD-2 CAR-T Cells compared to naïve activated T Cells. Cytotoxic function was validated with subsequent flow cytometry and cytokine analysis. After 7 days in co-culture, GD2 CAR-T cells exhibited markers of chronic activation, including greater CD8 expression than CD4, upregulation of CD69 (33% of cells), and induction of GrB (70%). Initial exhaustion was suggested by expression of PD1 (80% cells) and LAG3 (35%), but not TIM3. Overall, both naïve activated T-Cells and GD2 CAR-T Cells were effective for cytolysis of GSCs, with CAR-T exhibiting more efficient killing. CAR-T Cells engineered to target the GD2 antigen exhibited stronger potency and faster kinetics, suggesting greater clinical potential against glioblastoma. Citation Format: Heather Brant Hayes, Meghan T. Logun, Stacie A. Chvatal, Katie Mueller, Nicole Piscopo, Amritava Das, Krishanu Saha, Daniel C. Millard, Lohitash Karumbaiah. Kinetics and potency of T cell and CAR-T cell mediated cytolysis of glioma stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1552.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2021
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  • 9
    Online Resource
    Online Resource
    Society for Neuroscience ; 2012
    In:  The Journal of Neuroscience Vol. 32, No. 35 ( 2012-08-29), p. 12237-12250
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 32, No. 35 ( 2012-08-29), p. 12237-12250
    Abstract: The modular control of muscles in groups, often referred to as muscle synergies, has been proposed to provide a motor repertoire of actions for the robust control of movement. However, it is not clear whether muscle synergies identified in one task are also recruited by different neural pathways subserving other motor behaviors. We tested the hypothesis that voluntary and reactive modifications to walking in humans result from the recruitment of locomotor muscle synergies. We recorded the activity of 16 muscles in the right leg as subjects walked a 7.5 m path at two different speeds. To elicit a second motor behavior, midway through the path we imposed ramp and hold translation perturbations of the support surface in each of four cardinal directions. Variations in the temporal recruitment of locomotor muscle synergies could account for cycle-by-cycle variations in muscle activity across strides. Locomotor muscle synergies were also recruited in atypical phases of gait, accounting for both anticipatory gait modifications before perturbations and reactive feedback responses to perturbations. Our findings are consistent with the idea that a common pool of spatially fixed locomotor muscle synergies can be recruited by different neural pathways, including the central pattern generator for walking, brainstem pathways for balance control, and cortical pathways mediating voluntary gait modifications. Together with electrophysiological studies, our work suggests that muscle synergies may provide a library of motor subtasks that can be flexibly recruited by parallel descending pathways to generate a variety of complex natural movements in the upper and lower limbs.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2012
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    SSG: 12
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  • 10
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 12_Supplement ( 2022-06-15), p. 2817-2817
    Abstract: Glioblastoma (GBM) is an aggressive brain cancer without effective treatments. CAR-T cells targeted to tumor-associated antigens offer promise for treating GBM. Here, we used cellular impedance assays to compare the cytolytic potency and kinetics of conventional viral vs non-viral CRISPR engineered GD2 CAR-T cells against glioma stem cells (GSC), a subpopulation of glioblastoma cells. Patient-derived N08 GSCs were plated at 50k cells/well on 96-well plates, and impedance was continuously monitored on the Maestro Z impedance platform (Axion BioSystems). GD2 CAR-T cells were engineered using either retroviral transduction (RV) or non-viral CRISPR editing (NV). At 48 hours, GD2 CAR-T cells were added at Effector:Target ratios of 0.1:1, 1:1, and 10:1. Comparisons were made to mCherry T cells (mCh) as a control. Impedance and cytolysis were monitored up to 7 days. RV and NV GD2 CAR-T cells caused decreases in impedance consistent with T cell-mediated lysis of GSCs, whereas mCh T cells induced little change. NV CAR-T cells exhibited faster killing kinetics compared to RV CAR-T cells. The time to 50% cytolysis (KT50) was significantly shorter for NV vs RV CAR-T cells at 1:1 and 10:1 E:T ratios. Cytotoxic function was validated with flow cytometry and cytokine analysis at 7 days. All T cells exhibited chronic activation measured by CD69 and CD137 upregulation. Importantly, NV CAR-T cells exhibited less exhaustion, as measured by PD1 and LAG3 expression. Both RV and NV GD2 CAR-T cells effectively cytolyzed GSCs, with NV CAR-T cells exhibiting more potent and efficient killing. The high potency, fast kinetics, and reduced exhaustion of NV CRISPR GD2 CAR-T cells offer great clinical promise for treating GBM. Citation Format: Stacie A. Chvatal, Meghan T. Logun, Denise D. Sullivan, Heather B. Hayes, Daniel Millard, Mueller P. Katie, Nicole J. Piscopo, Amritava Das, Kris Saha, Daniel J. Brat, Lohitash Karumbaiah. GD2 CAR-T cells engineered using retroviral transduction or CRISPR editing exhibit strong cytolytic potency against glioma stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2817.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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