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  1. Article ; Online: Characterization of coagulopathy and outcomes in cancer patients with severe COVID -19 illness: Longitudinal changes in hospitalized cancer patients.

    Madani, Mahsa / Goldstein, Drew / Stefanescu, Roxana / Woodman, Scott E / Rojas-Hernandez, Cristhiam M

    Cancer medicine

    2022  Volume 11, Issue 20, Page(s) 3771–3785

    Abstract: There is a lack of data focused on the specific coagulopathic derangements in COVID-19 versus non-COVID-19 acutely ill cancer patients. Our objective was to characterize features of coagulopathy in cancer patients with active COVID-19 illness who ... ...

    Abstract There is a lack of data focused on the specific coagulopathic derangements in COVID-19 versus non-COVID-19 acutely ill cancer patients. Our objective was to characterize features of coagulopathy in cancer patients with active COVID-19 illness who required hospitalization at MD Anderson in the Texas Medical Center and to correlate those features with thrombotic complications, critical illness, and mortality within the first 30 days after hospital admission for COVID-19 illness. COVID-19 and non-COVID-19 hospitalized cancer patients, with at least five consecutive measures of PT, PTT, d-dimer, and CBC during the same period, were matched 1:1 to perform a retrospective analysis. We reviewed complete blood cell counts with differential, PT, PTT, fibrinogen, D-Dimer, serum ferritin, IL-6, CRP, and peripheral blood smears. Clinical outcomes were thrombosis, mechanical ventilation, critical illness, and death. Compared with matched hospitalized cancer patients without COVID-19, we found elevated neutrophil and lower lymphocyte counts in those with critical illness ( p =  0.00) or death ( p =  0.00); only neutrophils correlated with thrombosis. COVID-19 cancer patients with a platelet count decline during the hospital stay had more frequent critical illness ( p =  0.00) and fatal outcomes ( p =  0.00). Of the inflammatory markers, interleukin-6 showed consistently higher levels in the COVID-19 patients with poor outcomes. The findings of unique platelet changes and coagulopathy during severe COVID-19 illness in the cancer population are of interest to explore disease mechanisms and future risk stratification strategies to help with the management of cancer patients with COVID-19.
    MeSH term(s) Humans ; COVID-19/complications ; Interleukin-6 ; SARS-CoV-2 ; Critical Illness ; Retrospective Studies ; Biomarkers ; Neoplasms/complications ; Ferritins
    Chemical Substances Interleukin-6 ; Biomarkers ; Ferritins (9007-73-2)
    Language English
    Publishing date 2022-04-26
    Publishing country United States
    Document type Review ; Journal Article
    ZDB-ID 2659751-2
    ISSN 2045-7634 ; 2045-7634
    ISSN (online) 2045-7634
    ISSN 2045-7634
    DOI 10.1002/cam4.4753
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  2. Article ; Online: Muscarinic acetylcholine receptors control baseline activity and Hebbian stimulus timing-dependent plasticity in fusiform cells of the dorsal cochlear nucleus.

    Stefanescu, Roxana A / Shore, Susan E

    Journal of neurophysiology

    2016  Volume 117, Issue 3, Page(s) 1229–1238

    Abstract: Cholinergic modulation contributes to adaptive sensory processing by controlling spontaneous and stimulus-evoked neural activity and long-term synaptic plasticity. In the dorsal cochlear nucleus (DCN), in vitro activation of muscarinic acetylcholine ... ...

    Abstract Cholinergic modulation contributes to adaptive sensory processing by controlling spontaneous and stimulus-evoked neural activity and long-term synaptic plasticity. In the dorsal cochlear nucleus (DCN), in vitro activation of muscarinic acetylcholine receptors (mAChRs) alters the spontaneous activity of DCN neurons and interacts with
    MeSH term(s) Acoustic Stimulation ; Action Potentials/physiology ; Analysis of Variance ; Animals ; Atropine/pharmacology ; Cochlear Nerve/physiology ; Cochlear Nucleus/cytology ; Drug Delivery Systems ; Electric Stimulation ; Evoked Potentials, Auditory, Brain Stem/physiology ; Face/physiology ; Guinea Pigs ; Muscarinic Antagonists/pharmacology ; Neuronal Plasticity/drug effects ; Neuronal Plasticity/physiology ; Neurons/drug effects ; Neurons/physiology ; Receptors, Muscarinic/metabolism ; Time Factors
    Chemical Substances Muscarinic Antagonists ; Receptors, Muscarinic ; Atropine (7C0697DR9I)
    Language English
    Publishing date 2016-12-21
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    DOI 10.1152/jn.00270.2016
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  3. Article ; Online: NMDA Receptors Mediate Stimulus-Timing-Dependent Plasticity and Neural Synchrony in the Dorsal Cochlear Nucleus.

    Stefanescu, Roxana A / Shore, Susan E

    Frontiers in neural circuits

    2015  Volume 9, Page(s) 75

    Abstract: Auditory information relayed by auditory nerve fibers and somatosensory information relayed by granule cell parallel fibers converge on the fusiform cells (FCs) of the dorsal cochlear nucleus, the first brain station of the auditory pathway. In vitro, ... ...

    Abstract Auditory information relayed by auditory nerve fibers and somatosensory information relayed by granule cell parallel fibers converge on the fusiform cells (FCs) of the dorsal cochlear nucleus, the first brain station of the auditory pathway. In vitro, parallel fiber synapses on FCs exhibit spike-timing-dependent plasticity with Hebbian learning rules, partially mediated by the NMDA receptor (NMDAr). Well-timed bimodal auditory-somatosensory stimulation, in vivo equivalent of spike-timing-dependent plasticity, can induce stimulus-timing-dependent plasticity (StTDP) of the FCs spontaneous and tone-evoked firing rates. In healthy guinea pigs, the resulting distribution of StTDP learning rules across a FC neural population is dominated by a Hebbian profile while anti-Hebbian, suppressive and enhancing LRs are less frequent. In this study, we investigate in vivo, the NMDAr contribution to FC baseline activity and long term plasticity. We find that blocking the NMDAr decreases the synchronization of FC- spontaneous activity and mediates differential modulation of FC rate-level functions such that low, and high threshold units are more likely to increase, and decrease, respectively, their maximum amplitudes. Three significant alterations in mean learning-rule profiles were identified: transitions from an initial Hebbian profile towards (1) an anti-Hebbian; (2) a suppressive profile; and (3) transitions from an anti-Hebbian to a Hebbian profile. FC units preserving their learning rules showed instead, NMDAr-dependent plasticity to unimodal acoustic stimulation, with persistent depression of tone-evoked responses changing to persistent enhancement following the NMDAr antagonist. These results reveal a crucial role of the NMDAr in mediating FC baseline activity and long-term plasticity which have important implications for signal processing and auditory pathologies related to maladaptive plasticity of dorsal cochlear nucleus circuitry.
    MeSH term(s) Animals ; Auditory Pathways/physiology ; Cochlear Nucleus/physiology ; Electrophysiological Phenomena/physiology ; Evoked Potentials, Auditory, Brain Stem/physiology ; Guinea Pigs ; Neuronal Plasticity/physiology ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors ; Receptors, N-Methyl-D-Aspartate/physiology
    Chemical Substances Receptors, N-Methyl-D-Aspartate
    Language English
    Publishing date 2015
    Publishing country Switzerland
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2452968-0
    ISSN 1662-5110 ; 1662-5110
    ISSN (online) 1662-5110
    ISSN 1662-5110
    DOI 10.3389/fncir.2015.00075
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  4. Article ; Online: Stimulus-timing-dependent modifications of rate-level functions in animals with and without tinnitus.

    Stefanescu, Roxana A / Koehler, Seth D / Shore, Susan E

    Journal of neurophysiology

    2015  Volume 113, Issue 3, Page(s) 956–970

    Abstract: Tinnitus has been associated with enhanced central gain manifested by increased spontaneous activity and sound-evoked firing rates of principal neurons at various stations of the auditory pathway. Yet, the mechanisms leading to these modifications are ... ...

    Abstract Tinnitus has been associated with enhanced central gain manifested by increased spontaneous activity and sound-evoked firing rates of principal neurons at various stations of the auditory pathway. Yet, the mechanisms leading to these modifications are not well understood. In a recent in vivo study, we demonstrated that stimulus-timing-dependent bimodal plasticity mediates modifications of spontaneous and tone-evoked responses of fusiform cells in the dorsal cochlear nucleus (DCN) of the guinea pig. Fusiform cells from sham animals showed primarily Hebbian learning rules while noise-exposed animals showed primarily anti-Hebbian rules, with broadened profiles for the animals with behaviorally verified tinnitus (Koehler SD, Shore SE. J Neurosci 33: 19647-19656, 2013a). In the present study we show that well-timed bimodal stimulation induces alterations in the rate-level functions (RLFs) of fusiform cells. The RLF gains and maximum amplitudes show Hebbian modifications in sham and no-tinnitus animals but anti-Hebbian modifications in noise-exposed animals with evidence for tinnitus. These findings suggest that stimulus-timing bimodal plasticity produced by the DCN circuitry is a contributing mechanism to enhanced central gain associated with tinnitus.
    MeSH term(s) Animals ; Cochlear Nucleus/cytology ; Cochlear Nucleus/physiology ; Cochlear Nucleus/physiopathology ; Evoked Potentials, Auditory ; Female ; Guinea Pigs ; Neuronal Plasticity ; Neurons/physiology ; Noise ; Tinnitus/physiopathology
    Language English
    Publishing date 2015-02-01
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    DOI 10.1152/jn.00457.2014
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  5. Article ; Online: Reduced representations of heterogeneous mixed neural networks with synaptic coupling.

    Stefanescu, Roxana A / Jirsa, Viktor K

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2011  Volume 83, Issue 2 Pt 2, Page(s) 26204

    Abstract: In the human brain, large-scale neural networks are considered to instantiate the integrative mechanisms underlying higher cognitive, motor, and sensory functions. Computational models of such large-scale networks typically lump thousands of neurons into ...

    Abstract In the human brain, large-scale neural networks are considered to instantiate the integrative mechanisms underlying higher cognitive, motor, and sensory functions. Computational models of such large-scale networks typically lump thousands of neurons into a functional unit, which serves as the "atom" for the network integration. These atoms display a low dimensional dynamics corresponding to the only type of behavior available for the neurons within the unit, namely, the synchronized regime. Other dynamical features are not part of the unit's repertoire. With this limitation in mind, here we have studied the dynamical behavior of a neural network comprising "all-to-all" synaptically connected excitatory and inhibitory nonidentical neurons. We found that the network exhibits various dynamical characteristics, synchronization being only a particular case. Then we construct a low-dimensional representation of the network dynamics, and we show that this reduced system captures well the main dynamical features of the entire population. Our approach provides an alternate model for a neurocomputational unit of a large-scale network that can account for rich dynamical features of the network at low computational costs.
    MeSH term(s) Models, Biological ; Nerve Net/cytology ; Nerve Net/physiology ; Neurons/cytology ; Synapses/physiology
    Language English
    Publishing date 2011-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1550-2376
    ISSN (online) 1550-2376
    DOI 10.1103/PhysRevE.83.026204
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  6. Article ; Online: Neural population modes capture biologically realistic large scale network dynamics.

    Jirsa, Viktor K / Stefanescu, Roxana A

    Bulletin of mathematical biology

    2011  Volume 73, Issue 2, Page(s) 325–343

    Abstract: Large scale brain networks are understood nowadays to underlie the emergence of cognitive functions, though the detailed mechanisms are hitherto unknown. The challenges in the study of large scale brain networks are amongst others their high ... ...

    Abstract Large scale brain networks are understood nowadays to underlie the emergence of cognitive functions, though the detailed mechanisms are hitherto unknown. The challenges in the study of large scale brain networks are amongst others their high dimensionality requiring significant computational efforts, the complex connectivity across brain areas and the associated transmission delays, as well as the stochastic nature of neuronal processes. To decrease the computational effort, neurons are clustered into neural masses, which then are approximated by reduced descriptions of population dynamics. Here, we implement a neural population mode approach (Assisi et al. in Phys. Rev. Lett. 94(1):018106, 2005; Stefanescu and Jirsa in PLoS Comput. Biol. 4(11):e1000219, 2008), which parsimoniously captures various types of population behavior. We numerically demonstrate that the reduced population mode system favorably captures the high-dimensional dynamics of neuron networks with an architecture involving homogeneous local connectivity and a large-scale, fiber-like connection with time delay.
    MeSH term(s) Algorithms ; Computer Simulation ; Electrophysiological Phenomena/physiology ; Humans ; Models, Neurological ; Nerve Net/physiology ; Nerve Net/physiopathology ; Neural Inhibition/physiology ; Neural Pathways/physiology ; Neural Pathways/physiopathology ; Neurodegenerative Diseases/physiopathology ; Neurons/physiology ; Synaptic Transmission/physiology
    Language English
    Publishing date 2011-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 184905-0
    ISSN 1522-9602 ; 0007-4985 ; 0092-8240
    ISSN (online) 1522-9602
    ISSN 0007-4985 ; 0092-8240
    DOI 10.1007/s11538-010-9573-9
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  7. Article ; Online: Tinnitus: Maladaptive auditory-somatosensory plasticity.

    Wu, Calvin / Stefanescu, Roxana A / Martel, David T / Shore, Susan E

    Hearing research

    2016  Volume 334, Page(s) 20–29

    Abstract: Tinnitus, the phantom perception of sound, is physiologically characterized by an increase in spontaneous neural activity in the central auditory system. However, as tinnitus is often associated with hearing impairment, it is unclear how a decrease of ... ...

    Abstract Tinnitus, the phantom perception of sound, is physiologically characterized by an increase in spontaneous neural activity in the central auditory system. However, as tinnitus is often associated with hearing impairment, it is unclear how a decrease of afferent drive can result in central hyperactivity. In this review, we first assess methods for tinnitus induction and objective measures of the tinnitus percept in animal models. From animal studies, we discuss evidence that tinnitus originates in the cochlear nucleus (CN), and hypothesize mechanisms whereby hyperactivity may develop in the CN after peripheral auditory nerve damage. We elaborate how this process is likely mediated by plasticity of auditory-somatosensory integration in the CN: the circuitry in normal circumstances maintains a balance of auditory and somatosensory activities, and loss of auditory inputs alters the balance of auditory somatosensory integration in a stimulus timing dependent manner, which propels the circuit towards hyperactivity. Understanding the mechanisms underlying tinnitus generation is essential for its prevention and treatment. This article is part of a Special Issue entitled <Tinnitus>.
    Language English
    Publishing date 2016-04
    Publishing country Netherlands
    Document type Journal Article ; Review
    ZDB-ID 282629-x
    ISSN 1878-5891 ; 0378-5955
    ISSN (online) 1878-5891
    ISSN 0378-5955
    DOI 10.1016/j.heares.2015.06.005
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  8. Article ; Online: Recognition memory and theta-gamma interactions in the hippocampus.

    Trimper, John B / Stefanescu, Roxana A / Manns, Joseph R

    Hippocampus

    2013  Volume 24, Issue 3, Page(s) 341–353

    Abstract: Neuronal oscillations and cross-frequency interactions in the rat hippocampus relate in important ways to memory processes and serve as a model for studying oscillatory activity in cognition more broadly. We report here that hippocampal synchrony (CA3- ... ...

    Abstract Neuronal oscillations and cross-frequency interactions in the rat hippocampus relate in important ways to memory processes and serve as a model for studying oscillatory activity in cognition more broadly. We report here that hippocampal synchrony (CA3-CA1 coherence) increased markedly in the low gamma range as rats were exploring novel objects, particularly those for which the rat subsequently showed good memory. The gamma synchrony varied across phases of the theta rhythm such that coherence was highest at the falling slope and trough of the theta wave. Further, the shape of the theta wave was more asymmetric and elongated at the falling slope during exploration of objects for which the rat subsequently showed good memory as compared with objects for which the rat subsequently showed poor memory. The results showed a strong association between event-related gamma synchrony in rat hippocampus and memory encoding for novel objects. In addition, a novel potential mechanism of cross-frequency interactions was observed whereby dynamic alterations in the shape of theta wave related to memory in correspondence with the strength of gamma synchrony. These findings add to our understanding of how theta and gamma oscillations interact in the hippocampus in the service of memory.
    MeSH term(s) Animals ; Brain Waves/physiology ; CA1 Region, Hippocampal/physiology ; CA3 Region, Hippocampal/physiology ; Electrodes, Implanted ; Electroencephalography Phase Synchronization ; Exploratory Behavior/physiology ; Male ; Memory, Episodic ; Rats ; Rats, Long-Evans ; Recognition, Psychology/physiology ; Theta Rhythm/physiology
    Language English
    Publishing date 2013-11-26
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1074352-2
    ISSN 1098-1063 ; 1050-9631
    ISSN (online) 1098-1063
    ISSN 1050-9631
    DOI 10.1002/hipo.22228
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  9. Article ; Online: A low dimensional description of globally coupled heterogeneous neural networks of excitatory and inhibitory neurons.

    Stefanescu, Roxana A / Jirsa, Viktor K

    PLoS computational biology

    2008  Volume 4, Issue 11, Page(s) e1000219

    Abstract: Neural networks consisting of globally coupled excitatory and inhibitory nonidentical neurons may exhibit a complex dynamic behavior including synchronization, multiclustered solutions in phase space, and oscillator death. We investigate the conditions ... ...

    Abstract Neural networks consisting of globally coupled excitatory and inhibitory nonidentical neurons may exhibit a complex dynamic behavior including synchronization, multiclustered solutions in phase space, and oscillator death. We investigate the conditions under which these behaviors occur in a multidimensional parametric space defined by the connectivity strengths and dispersion of the neuronal membrane excitability. Using mode decomposition techniques, we further derive analytically a low dimensional description of the neural population dynamics and show that the various dynamic behaviors of the entire network can be well reproduced by this reduced system. Examples of networks of FitzHugh-Nagumo and Hindmarsh-Rose neurons are discussed in detail.
    MeSH term(s) Computational Biology ; Models, Neurological ; Nerve Net ; Neurons
    Language English
    Publishing date 2008-11-14
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1000219
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  10. Article ; Online: Computational models of epilepsy.

    Stefanescu, Roxana A / Shivakeshavan, R G / Talathi, Sachin S

    Seizure

    2012  Volume 21, Issue 10, Page(s) 748–759

    Abstract: Purpose: Approximately 30% of epilepsy patients suffer from medically refractory epilepsy, in which seizures can not controlled by the use of anti-epileptic drugs (AEDs). Understanding the mechanisms underlying these forms of drug-resistant epileptic ... ...

    Abstract Purpose: Approximately 30% of epilepsy patients suffer from medically refractory epilepsy, in which seizures can not controlled by the use of anti-epileptic drugs (AEDs). Understanding the mechanisms underlying these forms of drug-resistant epileptic seizures and the development of alternative effective treatment strategies are fundamental challenges for modern epilepsy research. In this context, computational modeling has gained prominence as an important tool for tackling the complexity of the epileptic phenomenon. In this review article, we present a survey of computational models of epilepsy from the point of view that epilepsy is a dynamical brain disease that is primarily characterized by unprovoked spontaneous epileptic seizures.
    Method: We introduce key concepts from the mathematical theory of dynamical systems, such as multi-stability and bifurcations, and explain how these concepts aid in our understanding of the brain mechanisms involved in the emergence of epileptic seizures.
    Results: We present a literature survey of the different computational modeling approaches that are used in the study of epilepsy. Special emphasis is placed on highlighting the fine balance between the degree of model simplification and the extent of biological realism that modelers seek in order to address relevant questions. In this context, we discuss three specific examples from published literature, which exemplify different approaches used for developing computational models of epilepsy. We further explore the potential of recently developed optogenetics tools to provide novel avenue for seizure control.
    Conclusion: We conclude with a discussion on the utility of computational models for the development of new epilepsy treatment protocols.
    MeSH term(s) Brain/physiopathology ; Epilepsy/physiopathology ; Humans ; Models, Neurological ; Models, Theoretical
    Language English
    Publishing date 2012-12
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 1137610-7
    ISSN 1532-2688 ; 1059-1311
    ISSN (online) 1532-2688
    ISSN 1059-1311
    DOI 10.1016/j.seizure.2012.08.012
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