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11
result(s) for
"Sharma, Shaunik"
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Seizure-Induced Oxidative Stress in Temporal Lobe Epilepsy
by
Stark, Sara
,
Puttachary, Sreekanth
,
Thippeswamy, Thimmasettappa
in
Animals
,
Antioxidants
,
Complications and side effects
2015
An insult to the brain (such as the first seizure) causes excitotoxicity, neuroinflammation, and production of reactive oxygen/nitrogen species (ROS/RNS). ROS and RNS produced during status epilepticus (SE) overwhelm the mitochondrial natural antioxidant defense mechanism. This leads to mitochondrial dysfunction and damage to the mitochondrial DNA. This in turn affects synthesis of various enzyme complexes that are involved in electron transport chain. Resultant effects that occur during epileptogenesis include lipid peroxidation, reactive gliosis, hippocampal neurodegeneration, reorganization of neural networks, and hypersynchronicity. These factors predispose the brain to spontaneous recurrent seizures (SRS), which ultimately establish into temporal lobe epilepsy (TLE). This review discusses some of these issues. Though antiepileptic drugs (AEDs) are beneficial to control/suppress seizures, their long term usage has been shown to increase ROS/RNS in animal models and human patients. In established TLE, ROS/RNS are shown to be harmful as they can increase the susceptibility to SRS. Further, in this paper, we review briefly the data from animal models and human TLE patients on the adverse effects of antiepileptic medications and the plausible ameliorating effects of antioxidants as an adjunct therapy.
Journal Article
Immediate Epileptogenesis after Kainate-Induced Status Epilepticus in C57BL/6J Mice: Evidence from Long Term Continuous Video-EEG Telemetry
2015
The C57BL/6J mouse as a model of seizure/epilepsy is challenging due to high mortality and huge variability in response to kainate. We have recently demonstrated that repeated administration of a low dose of kainate by intraperitoneal route can induce severe status epilepticus (SE) with 94% survival rate. In the present study, based on continuous video-EEG recording for 4-18 weeks from epidurally implanted electrodes on the cortex, we demonstrate that this method also induces immediate epileptogenesis (<1-5 days post-SE). This finding was based on identification of two types of spontaneous recurrent seizures; behavioral convulsive seizures (CS) and electrographic nonconvulsive seizures (NCS). The identification of the spontaneous CS, stage 3-5 types, was based on the behaviors (video) that were associated with the EEG characteristics (stage 3-5 epileptiform spikes), the power spectrum, and the activity counts. The electrographic NCS identification was based on the stage 1-2 epileptiform spike clusters on the EEG and their associated power spectrum. Severe SE induced immediate epileptogenesis in all the mice. The maximum numbers of spontaneous CS were observed during the first 4-6 weeks of the SE and they decreased thereafter. Mild SE also induced immediate epileptogenesis in some mice but the CS were less frequent. In both the severe and the mild SE groups, the spontaneous electrographic NCS persisted throughout the 18 weeks observation period, and therefore this could serve as a chronic model for complex seizures. However, unlike rat kainate models, the C57BL/6J mouse kainate model is a unique regressive CS model of epilepsy. Further studies are required to understand the mechanism of recovery from spontaneous CS in this model, which could reveal novel therapeutic targets for epilepsy.
Journal Article
Neuropathophysiological Mechanisms and Treatment Strategies for Post-traumatic Epilepsy
by
Bassuk, Alexander G.
,
Tiarks, Grant
,
Haight, Joseph
in
Alzheimer's disease
,
Anxiety disorders
,
Apoptosis
2021
Traumatic brain injury (TBI) is a leading cause of death in young adults and a risk factor for acquired epilepsy. Severe TBI, after a period of time, causes numerous neuropsychiatric and neurodegenerative problems with varying comorbidities; and brain homeostasis may never be restored. As a consequence of disrupted equilibrium, neuropathological changes such as circuit remodeling, reorganization of neural networks, changes in structural and functional plasticity, predisposition to synchronized activity, and post-translational modification of synaptic proteins may begin to dominate the brain. These pathological changes, over the course of time, contribute to conditions like Alzheimer disease, dementia, anxiety disorders, and post-traumatic epilepsy (PTE). PTE is one of the most common, devastating complications of TBI; and of those affected by a severe TBI, more than 50% develop PTE. The etiopathology and mechanisms of PTE are either unknown or poorly understood, which makes treatment challenging. Although anti-epileptic drugs (AEDs) are used as preventive strategies to manage TBI, control acute seizures and prevent development of PTE, their efficacy in PTE remains controversial. In this review, we discuss novel mechanisms and risk factors underlying PTE. We also discuss dysfunctions of neurovascular unit, cell-specific neuroinflammatory mediators and immune response factors that are vital for epileptogenesis after TBI. Finally, we describe current and novel treatments and management strategies for preventing PTE.
Journal Article
Neuroprotective effects of naltrexone in a mouse model of post-traumatic seizures
by
Bassuk, Alexander G.
,
Wong, Angela
,
Glykys, Joseph
in
631/378/1689/178
,
692/420/256
,
692/699/375/1345
2024
Traumatic Brain Injury (TBI) induces neuroinflammatory response that can initiate epileptogenesis, which develops into epilepsy. Recently, we identified anti-convulsive effects of naltrexone, a mu-opioid receptor (MOR) antagonist, used to treat drug addiction. While blocking opioid receptors can reduce inflammation, it is unclear if post-TBI seizures can be prevented by blocking MORs. Here, we tested if naltrexone prevents neuroinflammation and/or seizures post-TBI. TBI was induced by a modified Marmarou Weight-Drop (WD) method on 4-week-old C57BL/6J male mice. Mice were placed in two groups: non-telemetry assessing the acute effects or in telemetry monitoring for interictal events and spontaneous seizures both following TBI and naltrexone. Molecular, histological and neuroimaging techniques were used to evaluate neuroinflammation, neurodegeneration and fiber track integrity at 8 days and 3 months post-TBI. Peripheral immune responses were assessed through serum chemokine/cytokine measurements. Our results show an increase in MOR expression, nitro-oxidative stress, mRNA expression of inflammatory cytokines, microgliosis, neurodegeneration, and white matter damage in the neocortex of TBI mice. Video-EEG revealed increased interictal events in TBI mice, with 71% mice developing post-traumatic seizures (PTS). Naltrexone treatment ameliorated neuroinflammation, neurodegeneration, reduced interictal events and prevented seizures in all TBI mice, which makes naltrexone a promising candidate against PTS, TBI-associated neuroinflammation and epileptogenesis in a WD model of TBI.
Journal Article
The role of the master cancer regulator Pin1 in the development and treatment of cancer
2024
This review examines the complex role of Pin1 in the development and treatment of cancer. Pin1 is the only peptidyl–prolyl isomerase (PPIase) that can recognize and isomerize phosphorylated Ser/Thr-Pro peptide bonds. Pin1 catalyzes a structural change in phosphorylated Ser/Thr-Pro motifs that can modulate protein function and thereby impact cell cycle regulation and tumorigenesis. The molecular mechanisms by which Pin1 contributes to oncogenesis are reviewed, including Pin1 overexpression and its correlation with poor cancer prognosis, and the contribution of Pin1 to aggressive tumor phenotypes involved in therapeutic resistance is discussed, with an emphasis on cancer stem cells, the epithelial-to-mesenchymal transition (EMT), and immunosuppression. The therapeutic potential of Pin1 inhibition in cancer is discussed, along with the promise and the difficulties in identifying potent, drug-like, small-molecule Pin1 inhibitors. The available evidence supports the efficacy of targeting Pin1 as a novel cancer therapeutic by analyzing the role of Pin1 in a complex network of cancer-driving pathways and illustrating the potential of synergistic drug combinations with Pin1 inhibitors for treating aggressive and drug-resistant tumors.
Journal Article
The opioid antagonist naltrexone decreases seizure‐like activity in genetic and chemically induced epilepsy models
by
Bassuk, Alexander G.
,
Sturgeon, Morgan L.
,
Glykys, Joseph
in
Animals
,
Convulsions & seizures
,
Drug dosages
2021
Objective
A significant number of epileptic patients fail to respond to available anticonvulsive medications. To find new anticonvulsive medications, we evaluated FDA‐approved drugs not known to be anticonvulsants. Using zebrafish larvae as an initial model system, we found that the opioid antagonist naltrexone exhibited an anticonvulsant effect. We validated this effect in three other epilepsy models and present naltrexone as a promising anticonvulsive candidate.
Methods
Candidate anticonvulsant drugs, determined by our prior transcriptomics analysis of hippocampal tissue, were evaluated in a larval zebrafish model of human Dravet syndrome (scn1Lab mutants), in wild‐type zebrafish larvae treated with the pro‐convulsant drug pentylenetetrazole (PTZ), in wild‐type C57bl/6J acute brain slices exposed to PTZ, and in wild‐type mice treated with PTZ in vivo. Abnormal locomotion was determined behaviorally in zebrafish and mice and by field potential in neocortex layer IV/V and CA1 stratum pyramidale in the hippocampus.
Results
The opioid antagonist naltrexone decreased abnormal locomotion in the larval zebrafish model of human Dravet syndrome (scn1Lab mutants) and wild‐type larvae treated with the pro‐convulsant drug PTZ. Naltrexone also decreased seizure‐like events in acute brain slices of wild‐type mice, and the duration and number of seizures in adult mice injected with PTZ.
Significance
Our data reveal that naltrexone has anticonvulsive properties and is a candidate drug for seizure treatment.
Journal Article
Structure-based phylogeny identifies avoralstat as a TMPRSS2 inhibitor that prevents SARS-CoV-2 infection in mice
by
Sun, Young Joo
,
Bassuk, Alexander G.
,
Li, Kun
in
Amino acid sequence
,
Animals
,
Antiviral agents
2021
Drugs targeting host proteins can act prophylactically to reduce viral burden early in disease and limit morbidity, even with antivirals and vaccination. Transmembrane serine protease 2 (TMPRSS2) is a human protease required for SARS coronavirus 2 (SARS-CoV-2) viral entry and may represent such a target. We hypothesized that drugs selected from proteins related by their tertiary structure, rather than their primary structure, were likely to interact with TMPRSS2. We created a structure-based phylogenetic computational tool named 3DPhyloFold to systematically identify structurally similar serine proteases with known therapeutic inhibitors and demonstrated effective inhibition of SARS-CoV-2 infection in vitro and in vivo. Several candidate compounds, avoralstat, PCI-27483, antipain, and soybean trypsin inhibitor, inhibited TMPRSS2 in biochemical and cell infection assays. Avoralstat, a clinically tested kallikrein-related B1 inhibitor, inhibited SARS-CoV-2 entry and replication in human airway epithelial cells. In an in vivo proof of principle, avoralstat significantly reduced lung tissue titers and mitigated weight loss when administered prophylactically to mice susceptible to SARS-CoV-2, indicating its potential to be repositioned for coronavirus disease 2019 (COVID-19) prophylaxis in humans.
Journal Article
Investigating the Neuroprotective and Anti-Epileptogenic Mechanisms of Inducible Nitric Oxide Synthase and Src Family Kinase/Fyn Inhibitors in Experimental Models of Temporal Lobe Epilepsy
by
Sharma, Shaunik
in
Neurosciences
2019
Epilepsy is a neurological disorder characterized by spontaneous recurrent seizures (SRS) that affects over 65 million people worldwide, making it one of the most common neurological disorder globally. Etiology for epilepsy is unknown, however, gene mutation and exposure to neurotoxins or head trauma can cause seizures predisposing brain to epilepsy. In an acquired experimental models of temporal lobe epilepsy (TLE), epileptogenesis occurs soon after the induction of status epilepticus. We show herein, through the characterization of a mouse kainate model, the classical features of epileptogenesis such as development of SRS and epileptiform spiking patterns to understand neuronal hyper-excitability, and immunohistochemistry (IHC) on brain sections to investigate the mechanisms of neuroinflammation caused by reactive gliosis, synaptic reorganization, and neurodegeneration. These parameters served as a readout for interventional studies in the rat KA model of TLE. An inducible nitric oxide synthase (iNOS) and Src family kinase (SFK) mutually regulate each other’s expression and promote neuroinflammation and neurodegeneration. Therefore, we tested the disease modifying properties of 1400W, an iNOS inhibitor, and Saracatinib (SAR), SFK inhibitor, in our rat model. The results conclusively demonstrated that both 1400W and SAR significantly reduced spike frequency and SRS in 4-6 month of continuous EEG studies when compared to the vehicle-treated group. IHC on brain sections and Western blot results revealed reduced gliosis, serum albumin and neurodegeneration and enhanced Kir4.1 channel levels after 1400W treatment. In addition, SAR decreased translocation of Fyn and PKCδ into the nucleus with diminished expression of TNFα, IL-1β and iNOS mRNA; serum IL-6, IL-12, TNFα, IL-1β levels; and nitro-oxidative stress markers 4-HNE, gp91phox, 3-NT and iNOS in the hippocampus suggesting the role of Fyn as an upstream mediator of neuroinflammation in epileptogenesis. IHC results further revealed a significant reduction in Fyn and PKCδ immunopositive reactive glia and neurons and neurodegeneration in the brain after SAR treatment. In the vehicle treated group, Fyn and PKCδ levels were persistently upregulated during post-SE suggesting that Fyn-PKCδ drives neuroinflammation during epileptogenesis. Collectively, these findings reveal that iNOS and SFK/Fyn are principal mediators of neuroinflammation during epileptogenesis, and are potential therapeutic targets to prevent/treat epilepsy.
Dissertation
Immediate Epileptogenesis after Kainate-Induced Status Epilepticus in C57BL/6J Mice: Evidence from Long Term Continuous Video-EEG Telemetry: e0131705
2015
The C57BL/6J mouse as a model of seizure/epilepsy is challenging due to high mortality and huge variability in response to kainate. We have recently demonstrated that repeated administration of a low dose of kainate by intraperitoneal route can induce severe status epilepticus (SE) with 94% survival rate. In the present study, based on continuous video-EEG recording for 4-18 weeks from epidurally implanted electrodes on the cortex, we demonstrate that this method also induces immediate epileptogenesis (<1-5 days post-SE). This finding was based on identification of two types of spontaneous recurrent seizures; behavioral convulsive seizures (CS) and electrographic nonconvulsive seizures (NCS). The identification of the spontaneous CS, stage 3-5 types, was based on the behaviors (video) that were associated with the EEG characteristics (stage 3-5 epileptiform spikes), the power spectrum, and the activity counts. The electrographic NCS identification was based on the stage 1-2 epileptiform spike clusters on the EEG and their associated power spectrum. Severe SE induced immediate epileptogenesis in all the mice. The maximum numbers of spontaneous CS were observed during the first 4-6 weeks of the SE and they decreased thereafter. Mild SE also induced immediate epileptogenesis in some mice but the CS were less frequent. In both the severe and the mild SE groups, the spontaneous electrographic NCS persisted throughout the 18 weeks observation period, and therefore this could serve as a chronic model for complex seizures. However, unlike rat kainate models, the C57BL/6J mouse kainate model is a unique regressive CS model of epilepsy. Further studies are required to understand the mechanism of recovery from spontaneous CS in this model, which could reveal novel therapeutic targets for epilepsy.
Journal Article
Neuroprotective Effects of Naltrexone in a Mouse Model of Post-Traumatic Epilepsy
2023
Traumatic Brain Injury (TBI) induces neuroinflammatory responses that can initiate epileptogenesis, which develops into epilepsy. Recently, we identified the anti-convulsive effects of naltrexone, a mu-opioid receptor (MOR) antagonist. While blocking opioid receptors can reduce inflammation, it is unclear if post-TBI epileptogenesis can be prevented by blocking MORs. Here, we tested if naltrexone prevents neuroinflammation and epileptogenesis post-TBI. TBI was induced by a modified Marmarau Weight-Drop (WD) method applied to four-week-old C57BL/6J male mice. Mice were given the pro-convulsant pentylenetetrazol (PTZ) on day two post-injury while telemetry-monitored mice received PTZ on day five. Naltrexone/vehicle treatment started two hours after PTZ. Integrated EEG-video (vEEG) recorded interictal events and spontaneous seizures for three months. Molecular, histological and neuroimaging techniques were used to evaluate neuroinflammation and neurodegeneration both acutely and chronically. Peripheral immune responses were assessed through serum chemokine/cytokine measurements. We observed increases in MOR expression, nitro-oxidative stress, mRNA expression of inflammatory cytokines, microgliosis, neurodegeneration, and white matter damage in the neocortex of TBI mice. vEEG revealed increased interictal events in TBI mice, with 71% developing epilepsy. Naltrexone ameliorated neuroinflammation and neurodegeneration, reduced interictal events and prevented epilepsy, illustrating that naltrexone is a promising drug to prevent TBI-associated neuroinflammation and epileptogenesis in post-traumatic epilepsy.