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Giangrasso DM, Veros KM, Timm MM, West PJ, Wilcox KS, Keefe KA. Glutamate dynamics in the dorsolateral striatum of rats with goal-directed and habitual cocaine-seeking behavior. Front Mol Neurosci 2023; 16:1160157. [PMID: 37251646 PMCID: PMC10213946 DOI: 10.3389/fnmol.2023.1160157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/17/2023] [Indexed: 05/31/2023] Open
Abstract
The shift from drug abuse to addiction is considered to arise from the transition between goal-directed and habitual control over drug behavior. Habitual responding for appetitive and skill-based behaviors is mediated by potentiated glutamate signaling in the dorsolateral striatum (DLS), but the state of the DLS glutamate system in the context of habitual drug-behavior remains undefined. Evidence from the nucleus accumbens of cocaine-experienced rats suggests that decreased transporter-mediated glutamate clearance and enhanced synaptic glutamate release contribute to the potentiated glutamate signaling that underlies the enduring vulnerability to relapse. Preliminary evidence from the dorsal striatum of cocaine-experienced rats suggests that this region exhibits similar alterations to glutamate clearance and release, but it is not known whether these glutamate dynamics are associated with goal-directed or habitual control over cocaine-seeking behavior. Therefore, we trained rats to self-administer cocaine in a chained cocaine-seeking and -taking paradigm, which yielded goal-directed, intermediate, and habitual cocaine-seeking rats. We then assessed glutamate clearance and release dynamics in the DLS of these rats using two different methods: synaptic transporter current (STC) recordings of patch-clamped astrocytes and the intensity-based glutamate sensing fluorescent reporter (iGluSnFr). While we observed a decreased rate of glutamate clearance in STCs evoked with single-pulse stimulation in cocaine-experienced rats, we did not observe any cocaine-induced differences in glutamate clearance rates from STCs evoked with high frequency stimulation (HFS) or iGluSnFr responses evoked with either double-pulse stimulation or HFS. Furthermore, GLT-1 protein expression in the DLS was unchanged in cocaine-experienced rats, regardless of their mode of control over cocaine-seeking behavior. Lastly, there were no differences in metrics of glutamate release between cocaine-experienced rats and yoked-saline controls in either assay. Together, these results suggest that glutamate clearance and release dynamics in the DLS are largely unaltered by a history of cocaine self-administration on this established cocaine seeking-taking paradigm, regardless of whether the control over the cocaine seeking behavior was habitual or goal directed.
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Affiliation(s)
- Danielle M. Giangrasso
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, United States
| | - Kaliana M. Veros
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, United States
| | - Maureen M. Timm
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Peter J. West
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, United States
- Anticonvulsant Drug Development Program, Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Karen S. Wilcox
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, United States
- Anticonvulsant Drug Development Program, Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Kristen A. Keefe
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, United States
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, United States
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Heruye SH, Warren TJ, Kostansek IV JA, Draves SB, Matthews SA, West PJ, Simeone KA, Simeone TA. Ascorbic Acid Reduces Neurotransmission, Synaptic Plasticity, and Spontaneous Hippocampal Rhythms in In Vitro Slices. Nutrients 2022; 14:nu14030613. [PMID: 35276972 PMCID: PMC8839482 DOI: 10.3390/nu14030613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 12/26/2022] Open
Abstract
Ascorbic acid (AA; a.k.a. vitamin C) is well known for its cellular protection in environments of high oxidative stress. Even though physiological concentrations of AA in the brain are significant (0.2–10 mM), surprisingly little is known concerning the role of AA in synaptic neurotransmission under normal, non-disease state conditions. Here, we examined AA effects on neurotransmission, plasticity and spontaneous network activity (i.e., sharp waves and high frequency oscillations; SPW-HFOs), at the synapse between area 3 and 1 of the hippocampal cornu ammonis region (CA3 and CA1) using an extracellular multi-electrode array in in vitro mouse hippocampal slices. We found that AA decreased evoked field potentials (fEPSPs, IC50 = 0.64 mM) without affecting V50s or paired pulse facilitation indicating normal neurotransmitter release mechanisms. AA decreased presynaptic fiber volleys but did not change fiber volley-to-fEPSP coupling, suggesting reduced fEPSPs resulted from decreased fiber volleys. Inhibitory effects were also observed in CA1 stratum pyramidale where greater fEPSPs were required for population spikes in the presence of AA suggesting an impact on the intrinsic excitability of neurons. Other forms of synaptic plasticity and correlates of memory (i.e., short- and long-term potentiation) were also significantly reduced by AA as was the incidence of spontaneous SPW-HFOs. AA decreased SPW amplitude with a similar IC50 as fEPSPs (0.65 mM). Overall, these results indicate that under normal conditions AA significantly regulates neurotransmission, plasticity, and network activity by limiting excitability. Thus, AA may participate in refinement of signal processing and memory formation, as well as protecting against pathologic excitability.
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Affiliation(s)
- Segewkal H. Heruye
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
| | - Ted J. Warren
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
| | - Joseph A. Kostansek IV
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
| | - Samantha B. Draves
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
| | - Stephanie A. Matthews
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
| | - Peter J. West
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA;
| | - Kristina A. Simeone
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
| | - Timothy A. Simeone
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, Omaha, NE 68174, USA; (S.H.H.); (T.J.W.); (J.A.K.IV); (S.B.D.); (S.A.M.); (K.A.S.)
- Correspondence:
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Gibson AS, West PJ, Keefe KA. Effects of methamphetamine-induced neurotoxicity on striatal long-term potentiation. Psychopharmacology (Berl) 2022; 239:93-104. [PMID: 34985532 PMCID: PMC8728478 DOI: 10.1007/s00213-021-06055-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 12/27/2021] [Indexed: 11/28/2022]
Abstract
RATIONALE Methamphetamine (METH) exposure is associated with damage to central monoamine systems, particularly dopamine signaling. Rodent models of such damage have revealed a decrease in the amplitude of phasic dopamine signals and significant striatal dysfunction, including changes in the molecular, system, and behavioral functions of the striatum. Dopamine signaling through D1 receptors promotes corticostriatal long-term potentiation (LTP), a critical substrate of these striatal functions. OBJECTIVES Therefore, the purpose of this study was to determine if METH-induced dopamine neurotoxicity would impair D1 receptor-dependent striatal LTP in mice. METHODS Mice were treated with a METH binge regimen (4 × 10 mg/kg d,l-methamphetamine, s.c.) that recapitulates all of the known METH-induced neurotoxic effects observed in humans, including dopamine toxicity. Three weeks later, acute brain slices containing either the dorsomedial striatum (DMS) or dorsolateral striatum (DLS) were prepared, and plasticity was assessed using white matter, high-frequency stimulation (HFS), and striatal extracellular electrophysiology. RESULTS Under these conditions, LTP was induced in brain slices containing the DMS from saline-pretreated mice, but not mice with METH-induced neurotoxicity. Furthermore, the LTP observed in DMS slices from saline-pretreated mice was blocked by the dopamine D1 receptor antagonist SCH23390, indicating that this LTP is dopamine D1 receptor-dependent. Finally, acute in vivo treatment of METH-pretreated mice with bupropion (50 mg/kg, i.p.) promoted LTP in DMS slices. CONCLUSIONS Together, these studies demonstrate that METH-induced neurotoxicity impairs dopamine D1 receptor-dependent LTP within the DMS and that the FDA-approved drug bupropion restores induction of striatal LTP in mice with METH-induced dopamine neurotoxicity.
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Affiliation(s)
- Anne S. Gibson
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT USA ,Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, 30 S 2000 E Rm 201, Salt Lake City, UT 84112 USA
| | - Peter J. West
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT USA ,Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, 30 S 2000 E Rm 201, Salt Lake City, UT 84112 USA ,Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT USA
| | - Kristen A. Keefe
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT USA ,Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, 30 S 2000 E Rm 201, Salt Lake City, UT 84112 USA
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West PJ, Thomson K, Billingsley P, Pruess T, Rueda C, Saunders GW, Smith MD, Metcalf CS, Wilcox KS. Spontaneous recurrent seizures in an intra-amygdala kainate microinjection model of temporal lobe epilepsy are differentially sensitive to antiseizure drugs. Exp Neurol 2021; 349:113954. [PMID: 34922908 PMCID: PMC8815304 DOI: 10.1016/j.expneurol.2021.113954] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 10/14/2021] [Accepted: 12/13/2021] [Indexed: 12/15/2022]
Abstract
The discovery and development of novel antiseizure drugs (ASDs) that are effective in controlling pharmacoresistant spontaneous recurrent seizures (SRSs) continues to represent a significant unmet clinical need. The Epilepsy Therapy Screening Program (ETSP) has undertaken efforts to address this need by adopting animal models that represent the salient features of human pharmacoresistant epilepsy and employing these models for preclinical testing of investigational ASDs. One such model that has garnered increased interest in recent years is the mouse variant of the Intra-Amygdala Kainate (IAK) microinjection model of mesial temporal lobe epilepsy (MTLE). In establishing a version of this model, several methodological variables were evaluated for their effect(s) on pertinent quantitative endpoints. Although administration of a benzodiazepine 40 min after kainate (KA) induced status epilepticus (SE) is commonly used to improve survival, data presented here demonstrates similar outcomes (mortality, hippocampal damage, latency periods, and 90-day SRS natural history) between mice given midazolam and those that were not. Using a version of this model that did not interrupt SE with a benzodiazepine, a 90-day natural history study was performed and survival, latency periods, SRS frequencies and durations, and SRS clustering data were quantified. Finally, an important step towards model adoption is to assess the sensitivities or resistances of SRSs to a panel of approved and clinically used ASDs. Accordingly, the following ASDs were evaluated for their effects on SRSs in these mice: phenytoin (20 mg/kg, b.i.d.), carbamazepine (30 mg/kg, t.i.d.), valproate (240 mg/kg, t.i.d.), diazepam (4 mg/kg, b.i.d.), and phenobarbital (25 and 50 mg/kg, b. i.d.). Valproate, diazepam, and phenobarbital significantly attenuated SRS frequency relative to vehicle controls at doses devoid of observable adverse behavioral effects. Only diazepam significantly increased seizure freedom. Neither phenytoin nor carbamazepine significantly altered SRS frequency or freedom under these experimental conditions. These data demonstrate that SRSs in this IAK model of MTLE are pharmacoresistant to two representative sodium channel-inhibiting ASDs (phenytoin and carbamazepine) and partially sensitive to GABA receptor modulating ASDs (diazepam and phenobarbital) or a mixed-mechanism ASD (valproate). Accordingly, this model is being incorporated into the NINDS-funded ETSP testing platform for treatment resistant epilepsy.
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Affiliation(s)
- Peter J West
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA; Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA; Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108, USA.
| | - Kyle Thomson
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA; Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA
| | - Peggy Billingsley
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA
| | - Timothy Pruess
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA
| | - Carlos Rueda
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA
| | - Gerald W Saunders
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA
| | - Misty D Smith
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA; Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA; School of Dentistry, University of Utah, Salt Lake City, UT 84108, USA
| | - Cameron S Metcalf
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA; Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA
| | - Karen S Wilcox
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA; Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT 84112, USA; Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108, USA
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Metcalf CS, Vanegas F, Underwood T, Johnson K, West PJ, Smith MD, Wilcox KS. Screening of prototype antiseizure and anti-inflammatory compounds in the Theiler's murine encephalomyelitis virus model of epilepsy. Epilepsia Open 2021; 7:46-58. [PMID: 34668659 PMCID: PMC8886069 DOI: 10.1002/epi4.12550] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/10/2021] [Accepted: 10/12/2021] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVE Infection with Theiler's murine encephalomyelitis virus (TMEV) in C57Bl/6J mice results in handling-induced seizures and is useful for evaluating compounds effective against infection-induced seizures. However, to date only a few compounds have been evaluated in this model, and a comprehensive study of antiseizure medications (ASMs) has not yet been performed. Furthermore, as the TMEV infection produces marked neuroinflammation, an evaluation of prototype anti-inflammatory compounds is needed as well. METHODS Male C57Bl/6J mice were inoculated with TMEV (day 0) followed by daily administrations of test compounds (day 3-7) and subsequent handling sessions (day 3-7). Doses of ASMs, comprising several mechanistic classes, were selected based on previously published data demonstrating the effect of these compounds in reducing seizures in the 6 Hz model of pharmacoresistant seizures. Doses of anti-inflammatory compounds, comprising several mechanistic classes, were selected based on published evidence of reduction of inflammation or inflammation-related endpoints. RESULTS Several prototype ASMs reduced acute seizures following TMEV infection: lacosamide, phenytoin, ezogabine, phenobarbital, tiagabine, gabapentin, levetiracetam, topiramate, and sodium valproate. Of these, phenobarbital and sodium valproate had the greatest effect (>95% seizure burden reduction). Prototype anti-inflammatory drugs celecoxib, dexamethasone, and prednisone also moderately reduced seizure burden. SIGNIFICANCE The TMEV model is utilized by the Epilepsy Therapy Screening Program (ETSP) as a tool for evaluation of novel compounds. Compounds reducing seizures in the TMEV comprise distinct mechanistic classes, some with mechanisms of action that extend beyond traditional ASMs.
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Affiliation(s)
- Cameron S Metcalf
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Fabiola Vanegas
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Tristan Underwood
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Kristina Johnson
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Peter J West
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Misty D Smith
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,School of Dentistry, University of Utah, Salt Lake City, Utah, USA
| | - Karen S Wilcox
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
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Pernici CD, Mensah JA, Dahle EJ, Johnson KJ, Handy L, Buxton L, Smith MD, West PJ, Metcalf CS, Wilcox KS. Development of an antiseizure drug screening platform for Dravet syndrome at the NINDS contract site for the Epilepsy Therapy Screening Program. Epilepsia 2021; 62:1665-1676. [PMID: 34002394 PMCID: PMC8360068 DOI: 10.1111/epi.16925] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/25/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023]
Abstract
Objective Dravet syndrome (DS) is a rare but catastrophic genetic epilepsy, with 80% of patients carrying a mutation in the SCN1A gene. Currently, no antiseizure drug (ASD) exists that adequately controls seizures. In the clinic, individuals with DS often present first with a febrile seizure and, subsequently, generalized tonic‐clonic seizures that can continue throughout life. To facilitate the development of ASDs for DS, the contract site of the National Institute of Neurological Disorders and Stroke (NINDS) Epilepsy Therapy Screening Program (ETSP) has evaluated a mouse model of DS using the conditional knock‐in Scn1aA1783V/WT mouse. Methods Survival rates and temperature thresholds for Scn1aA1783V/WT were determined. Prototype ASDs were administered via intraperitoneal injections at the time‐to‐peak effect, which was previously determined, prior to the induction of hyperthermia‐induced seizures. ASDs were considered effective if they significantly increased the temperature at which Scn1aA1783V/WT mice had seizures. Results Approximately 50% of Scn1aA1783V/WT survive to adulthood and all have hyperthermia‐induced seizures. The results suggest that hyperthermia‐induced seizures in this model of DS are highly refractory to a battery of ASDs. Exceptions were clobazam, tiagabine, levetiracetam, and the combination of clobazam and valproic acid with add‐on stiripentol, which elevated seizure thresholds. Significance Overall, the data demonstrate that the proposed model for DS is suitable for screening novel compounds for the ability to block hyperthermia‐induced seizures and that heterozygous mice can be evaluated repeatedly over the course of several weeks, allowing for higher throughput screening.
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Affiliation(s)
- Chelsea D Pernici
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Jeffrey A Mensah
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - E Jill Dahle
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Kristina J Johnson
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA
| | - Laura Handy
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA
| | - Lauren Buxton
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Misty D Smith
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Peter J West
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Cameron S Metcalf
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Karen S Wilcox
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, UT, USA.,Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
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Thomson KE, West PJ, Metcalf CS, Wilcox KS. Response: Usefulness of the post-kainate spontaneous recurrent seizure model for screening for antiseizure and for neuroprotective effects. Epilepsia 2021; 62:1290. [PMID: 33778946 DOI: 10.1111/epi.16884] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 03/05/2021] [Indexed: 12/26/2022]
Affiliation(s)
- Kyle E Thomson
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Peter J West
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Cameron S Metcalf
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
| | - Karen S Wilcox
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA
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Li X, Himes RA, Prosser LC, Christie CF, Watt E, Edwards SF, Metcalf CS, West PJ, Wilcox KS, Chan SS, Chou CJ. Discovery of the First Vitamin K Analogue as a Potential Treatment of Pharmacoresistant Seizures. J Med Chem 2020; 63:5865-5878. [PMID: 32390424 PMCID: PMC7684765 DOI: 10.1021/acs.jmedchem.0c00168] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite the availability of more than 25 antiseizure drugs on the market, approximately 30% of patients with epilepsy still suffer from seizures. Thus, the epilepsy therapy market has a great need for a breakthrough drug that will aid pharmacoresistant patients. In our previous study, we discovered a vitamin K analogue, 2h, which displayed modest antiseizure activity in zebrafish and mouse seizure models. However, there are limitations to this compound due to its pharmacokinetic profile. In this study, we develop a new series of vitamin K analogues by modifying the structure of 2h. Among these, compound 3d shows full protection in a rodent pharmacoresistant seizure model with limited rotarod motor toxicity and favorable pharmacokinetic properties. Furthermore, the brain/plasma concentration ratio of 3d indicates its excellent permeability into the brain. The resulting data shows that 3d can be further developed as a potential antiseizure drug in the clinic.
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Affiliation(s)
- Xiaoyang Li
- Ocean University of China, School of Medicine and Pharmacy, Qingdao, Shandong, 266071, China
| | - Richard A. Himes
- Department of Chemistry and Biochemistry, College of Charleston, 66 George Street,Charleston, South Carolina29424, USA
| | - Lyndsey C. Prosser
- Department of Chemistry and Biochemistry, College of Charleston, 66 George Street,Charleston, South Carolina29424, USA
| | | | - Emma Watt
- Department of Chemistry and Biochemistry, College of Charleston, 66 George Street,Charleston, South Carolina29424, USA
| | - Sharon F. Edwards
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, 84112, USA
| | - Cameron S. Metcalf
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, 84112, USA
| | - Peter J. West
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, 84112, USA
| | - Karen S. Wilcox
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, 84112, USA
| | - Sherine S.L. Chan
- Neuroene Therapeutics, Mount Pleasant, South Carolina 29464, USA
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - C. James Chou
- Neuroene Therapeutics, Mount Pleasant, South Carolina 29464, USA
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Thomson KE, Metcalf CS, Newell TG, Huff J, Edwards SF, West PJ, Wilcox KS. Evaluation of subchronic administration of antiseizure drugs in spontaneously seizing rats. Epilepsia 2020; 61:1301-1311. [PMID: 32420627 PMCID: PMC7383749 DOI: 10.1111/epi.16531] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 01/04/2023]
Abstract
Objective Approximately 30% of patients with epilepsy do not experience full seizure control on their antiseizure drug (ASD) regimen. Historically, screening for novel ASDs has relied on evaluating efficacy following a single administration of a test compound in either acute electrical or chemical seizure induction. However, the use of animal models of spontaneous seizures and repeated administration of test compounds may better differentiate novel compounds. Therefore, this approach has been instituted as part of the National Institute of Neurological Disorders and Stroke Epilepsy Therapy Screening Program screening paradigm for pharmacoresistant epilepsy. Methods Rats were treated with intraperitoneal kainic acid to induce status epilepticus and subsequent spontaneous recurrent seizures. After 12 weeks, rats were enrolled in drug screening studies. Using a 2‐week crossover design, selected ASDs were evaluated for their ability to protect against spontaneous seizures, using a video‐electroencephalographic monitoring system and automated seizure detection. Sixteen clinically available compounds were administered at maximally tolerated doses in this model. Dose intervals (1‐3 treatments/d) were selected based on known half‐lives for each compound. Results Carbamazepine (90 mg/kg/d), phenobarbital (30 mg/kg/d), and ezogabine (15 mg/kg/d) significantly reduced seizure burden at the doses evaluated. In addition, a dose‐response study of topiramate (20‐600 mg/kg/d) demonstrated that this compound reduced seizure burden at both therapeutic and supratherapeutic doses. However, none of the 16 ASDs conferred complete seizure freedom during the testing period at the doses tested. Significance Despite reductions in seizure burden, the lack of full seizure freedom for any ASD tested suggests that this screening paradigm may be useful for testing novel compounds with potential utility in pharmacoresistant epilepsy.
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Affiliation(s)
- Kyle E Thomson
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
| | - Cameron S Metcalf
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
| | - Thomas G Newell
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
| | - Jennifer Huff
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
| | - Sharon F Edwards
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
| | - Peter J West
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
| | - Karen S Wilcox
- Department, of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.,Epilepsy Therapy Screening Program, University of Utah, Salt Lake City, Utah, USA
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10
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Wilcox KS, West PJ, Metcalf CS. The current approach of the Epilepsy Therapy Screening Program contract site for identifying improved therapies for the treatment of pharmacoresistant seizures in epilepsy. Neuropharmacology 2020; 166:107811. [PMID: 31790717 PMCID: PMC7054975 DOI: 10.1016/j.neuropharm.2019.107811] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/05/2019] [Accepted: 10/08/2019] [Indexed: 12/12/2022]
Abstract
The Epilepsy Therapy Screening Program (ETSP), formerly known as the Anticonvulsant Screening Program (ASP), has played an important role in the preclinical evaluation of many of the antiseizure drugs (ASDs) that have been approved by the FDA and thus made available for the treatment of seizures. Recent changes to the animal models used at the contract site of the ETSP at the University of Utah have been implemented in an attempt to better model the unmet clinical needs of people with pharmacoresistant epilepsy and thus identify improved therapies. In this review, we describe the changes that have occurred over the last several years in the screening approach used at the contract site and, in particular, detail the pharmacology associated with several of the animal models and assays that are either new to the program or have been recently characterized in more depth. There is optimism that the refined approach used by the ETSP contract site, wherein etiologically relevant models that include those with spontaneous seizures are used, will identify novel, potentially disease modifying therapies for people with pharmacoresistant epilepsy and those at risk for developing epilepsy. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
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Affiliation(s)
- Karen S Wilcox
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, USA.
| | - Peter J West
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, USA.
| | - Cameron S Metcalf
- Anticonvulsant Drug Development (ADD) Program, Department of Pharmacology & Toxicology, University of Utah, USA.
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11
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West PJ, Saunders GW, Billingsley P, Smith MD, White HS, Metcalf CS, Wilcox KS. Recurrent epileptiform discharges in the medial entorhinal cortex of kainate-treated rats are differentially sensitive to antiseizure drugs. Epilepsia 2018; 59:2035-2048. [PMID: 30328622 DOI: 10.1111/epi.14563] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/17/2018] [Accepted: 08/17/2018] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Approximately 30% of patients with epilepsy are refractory to existing antiseizure drugs (ASDs). Given that the properties of the central nervous systems of these patients are likely to be altered due to their epilepsy, tissues from rodents that have undergone epileptogenesis might provide a therapeutically relevant disease substrate for identifying compounds capable of attenuating pharmacoresistant seizures. To facilitate the development of such a model, this study describes the effects of classical glutamate receptor antagonists and 20 ASDs on recurrent epileptiform discharges (REDs) in brain slices derived from the kainate-induced status epilepticus model of temporal lobe epilepsy (KA-rats). METHODS Horizontal brain slices containing the medial entorhinal cortex (mEC) were prepared from KA-rats, and REDs were recorded from the superficial layers. 6-cyano-7-nitroquinoxaline-2,3-dione, (2R)-amino-5-phosphonovaleric acid, tetrodotoxin, or ASDs were bath applied for 20 minutes. Concentration-dependent effects and half maximal effective concentration values were determined for RED duration, frequency, and amplitude. RESULTS ASDs targeting sodium and potassium channels (carbamazepine, eslicarbazepine, ezogabine, lamotrigine, lacosamide, phenytoin, and rufinamide) attenuated REDs at concentrations near their average therapeutic plasma concentrations. γ-aminobutyric acid (GABA)ergic synaptic transmission-modulating ASDs (clobazam, midazolam, phenobarbital, stiripentol, tiagabine, and vigabatrin) attenuated REDs only at higher concentrations and, in some cases, prolonged RED durations. ASDs with other/mixed mechanisms of action (bumetanide, ethosuximide, felbamate, gabapentin, levetiracetam, topiramate, and valproate) and glutamate receptor antagonists weakly or incompletely inhibited RED frequency, increased RED duration, or had no significant effects. SIGNIFICANCE Taken together, these data suggest that epileptiform activity recorded from the superficial layers of the mEC in slices obtained from KA-rats is differentially sensitive to existing ASDs. The different sensitivities of REDs to these ASDs may reflect persistent molecular, cellular, and/or network-level changes resulting from disease. These data are expected to serve as a foundation upon which future therapeutics may be differentiated and assessed for potentially translatable efficacy in patients with refractory epilepsy.
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Affiliation(s)
- Peter J West
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah.,Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, Utah.,Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, Utah
| | - Gerald W Saunders
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, Utah
| | - Peggy Billingsley
- Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, Utah
| | - Misty D Smith
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah.,Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, Utah.,School of Dentistry, University of Utah, Salt Lake City, Utah
| | - H Steve White
- Department of Pharmacy, University of Washington, Seattle, Washington
| | - Cameron S Metcalf
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah.,Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, Utah
| | - Karen S Wilcox
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah.,Epilepsy Therapy Screening Program (ETSP) Contract Site, University of Utah, Salt Lake City, Utah.,Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, Utah
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12
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Basu R, Duan X, Taylor MR, Martin EA, Muralidhar S, Wang Y, Gangi-Wellman L, Das SC, Yamagata M, West PJ, Sanes JR, Williams ME. Heterophilic Type II Cadherins Are Required for High-Magnitude Synaptic Potentiation in the Hippocampus. Neuron 2018; 98:658-668. [PMID: 29723502 DOI: 10.1016/j.neuron.2018.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Abstract
This corrects the article DOI: 10.1038/mp.2017.180.
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14
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Basu R, Duan X, Taylor MR, Martin EA, Muralidhar S, Wang Y, Gangi-Wellman L, Das SC, Yamagata M, West PJ, Sanes JR, Williams ME. Heterophilic Type II Cadherins Are Required for High-Magnitude Synaptic Potentiation in the Hippocampus. Neuron 2017; 96:160-176.e8. [PMID: 28957665 DOI: 10.1016/j.neuron.2017.09.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 08/03/2017] [Accepted: 09/11/2017] [Indexed: 11/26/2022]
Abstract
Hippocampal CA3 neurons form synapses with CA1 neurons in two layers, stratum oriens (SO) and stratum radiatum (SR). Each layer develops unique synaptic properties but molecular mechanisms that mediate these differences are unknown. Here, we show that SO synapses normally have significantly more mushroom spines and higher-magnitude long-term potentiation (LTP) than SR synapses. Further, we discovered that these differences require the Type II classic cadherins, cadherins-6, -9, and -10. Though cadherins typically function via trans-cellular homophilic interactions, our results suggest presynaptic cadherin-9 binds postsynaptic cadherins-6 and -10 to regulate mushroom spine density and high-magnitude LTP in the SO layer. Loss of these cadherins has no effect on the lower-magnitude LTP typically observed in the SR layer, demonstrating that cadherins-6, -9, and -10 are gatekeepers for high-magnitude LTP. Thus, Type II cadherins may uniquely contribute to the specificity and strength of synaptic changes associated with learning and memory.
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Affiliation(s)
- Raunak Basu
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Xin Duan
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA 94117, USA
| | - Matthew R Taylor
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - E Anne Martin
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Shruti Muralidhar
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Yueqi Wang
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Luke Gangi-Wellman
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Sujan C Das
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Masahito Yamagata
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Peter J West
- Department of Pharmacology and Toxicology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Megan E Williams
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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Remigio GJ, Loewen JL, Heuston S, Helgeson C, White HS, Wilcox KS, West PJ. Corneal kindled C57BL/6 mice exhibit saturated dentate gyrus long-term potentiation and associated memory deficits in the absence of overt neuron loss. Neurobiol Dis 2017. [PMID: 28624414 DOI: 10.1016/j.nbd.2017.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Memory deficits have a significant impact on the quality of life of patients with epilepsy and currently no effective treatments exist to mitigate this comorbidity. While these cognitive comorbidities can be associated with varying degrees of hippocampal cell death and hippocampal sclerosis, more subtle changes in hippocampal physiology independent of cell loss may underlie memory dysfunction in many epilepsy patients. Accordingly, animal models of epilepsy or epileptic processes exhibiting memory deficits in the absence of cell loss could facilitate novel therapy discovery. Mouse corneal kindling is a cost-effective and non-invasive model of focal to bilateral tonic-clonic seizures that may exhibit memory deficits in the absence of cell loss. Therefore, we tested the hypothesis that corneal kindled C57BL/6 mice exhibit spatial pattern processing and memory deficits in a task reliant on DG function and that these impairments would be concurrent with physiological remodeling of the DG as opposed to overt neuron loss. Following corneal kindling, C57BL/6 mice exhibited deficits in a DG-associated spatial memory test - the metric task. Compatible with this finding, we also discovered saturated, and subsequently impaired, LTP of excitatory synaptic transmission at the perforant path to DGC synapse. This saturation of LTP was consistent with evidence suggesting that perforant path to DGC synapses in kindled mice had previously experienced LTP-like changes to their synaptic weights: increased postsynaptic depolarizations in response to equivalent presynaptic input and significantly larger amplitude AMPA receptor mediated spontaneous EPSCs. Additionally, there was evidence for kindling-induced changes in the intrinsic excitability of DGCs: reduced threshold to population spikes under extracellular recording conditions and significantly increased membrane resistances observed in DGCs. Importantly, quantitative immunohistochemical analysis revealed hippocampal astrogliosis in the absence of overt neuron loss. These changes in spatial pattern processing and memory deficits in corneal kindled mice represent a novel model of seizure-induced cognitive dysfunction associated with pathophysiological remodeling of excitatory synaptic transmission and granule cell excitability in the absence of overt cell loss.
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Affiliation(s)
- Gregory J Remigio
- Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108-1210, USA; Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84108-1210, USA
| | - Jaycie L Loewen
- Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108-1210, USA; Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84108-1210, USA
| | | | - Colin Helgeson
- Juan Diego Catholic High School, Draper, UT 84020-9035, USA
| | - H Steve White
- Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108-1210, USA; Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84108-1210, USA; Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT 84108-1210, USA
| | - Karen S Wilcox
- Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108-1210, USA; Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84108-1210, USA; Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT 84108-1210, USA
| | - Peter J West
- Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, UT 84108-1210, USA; Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84108-1210, USA; Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT 84108-1210, USA.
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Metcalf CS, West PJ, Thomson KE, Edwards SF, Smith MD, White HS, Wilcox KS. Development and pharmacologic characterization of the rat 6 Hz model of partial seizures. Epilepsia 2017; 58:1073-1084. [PMID: 28449218 DOI: 10.1111/epi.13764] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2017] [Indexed: 01/14/2023]
Abstract
OBJECTIVE The mouse 6 Hz model of psychomotor seizures is a well-established and commonly used preclinical model for antiseizure drug (ASD) discovery. Despite its widespread use both in the identification and differentiation of novel ASDs in mice, a corresponding assay in rats has not been developed. We established a method for 6 Hz seizure induction in rats, with seizure behaviors similar to those observed in mice including head nod, jaw clonus, and forelimb clonus. METHODS A convulsive current that elicits these seizure behaviors in 97% of rats (CC97 ) was determined using a Probit analysis. Numerous prototype ASDs were evaluated in this model using stimulus intensities of 1.5× and 2× the CC97 , which is comparable to the approach used in the mouse 6 Hz seizure model (e.g., 32 and 44 mA stimulus intensities). The ASDs evaluated include carbamazepine, clobazam, clonazepam, eslicarbazepine, ethosuximide, ezogabine, gabapentin, lacosamide, lamotrigine, levetiracetam, phenobarbital, phenytoin, rufinamide, tiagabine, topiramate, and sodium valproate. Median effective dose (ED50 ) and median toxic (motor impairment) dose (TD50 ) values were obtained for each compound. RESULTS Compounds that were effective at the 1.5 × CC97 stimulus intensity at protective index (PI) values >1 included clobazam, ethosuximide, ezogabine, levetiracetam, phenobarbital, and sodium valproate. Compounds that were effective at the 2 × CC97 stimulus intensity at PI values >1 included ezogabine, phenobarbital, and sodium valproate. SIGNIFICANCE In a manner similar to the use of the mouse 6 Hz model, development of a rat 6 Hz test will aid in the differentiation of ASDs, as well as in study design and dose selection for chronic rat models of pharmacoresistant epilepsy. The limited number of established ASDs with demonstrable efficacy at the higher stimulus intensity suggests that, like the mouse 6 Hz 44 mA model, the rat 6 Hz seizure model may be a useful screening tool for pharmacoresistant seizures.
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Affiliation(s)
- Cameron S Metcalf
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
| | - Peter J West
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
| | - Kyle E Thomson
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
| | - Sharon F Edwards
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
| | - Misty D Smith
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A.,School of Dentistry, University of Utah, Salt Lake City, Utah, U.S.A
| | - H Steve White
- Department of Pharmacy, University of Washington, Seattle, Washington, U.S.A
| | - Karen S Wilcox
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
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Barker-Haliski ML, Johnson K, Billingsley P, Huff J, Handy LJ, Khaleel R, Lu Z, Mau MJ, Pruess TH, Rueda C, Saunders G, Underwood TK, Vanegas F, Smith MD, West PJ, Wilcox KS. Validation of a Preclinical Drug Screening Platform for Pharmacoresistant Epilepsy. Neurochem Res 2017; 42:1904-1918. [PMID: 28303498 DOI: 10.1007/s11064-017-2227-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/07/2017] [Accepted: 03/09/2017] [Indexed: 12/11/2022]
Abstract
The successful identification of promising investigational therapies for the treatment of epilepsy can be credited to the use of numerous animal models of seizure and epilepsy for over 80 years. In this time, the maximal electroshock test in mice and rats, the subcutaneous pentylenetetrazol test in mice and rats, and more recently the 6 Hz assay in mice, have been utilized as primary models of electrically or chemically-evoked seizures in neurologically intact rodents. In addition, rodent kindling models, in which chronic network hyperexcitability has developed, have been used to identify new agents. It is clear that this traditional screening approach has greatly expanded the number of marketed drugs available to manage the symptomatic seizures associated with epilepsy. In spite of the numerous antiseizure drugs (ASDs) on the market today, the fact remains that nearly 30% of patients are resistant to these currently available medications. To address this unmet medical need, the National Institute of Neurological Disorders and Stroke (NINDS) Epilepsy Therapy Screening Program (ETSP) revised its approach to the early evaluation of investigational agents for the treatment of epilepsy in 2015 to include a focus on preclinical approaches to model pharmacoresistant seizures. This present report highlights the in vivo and in vitro findings associated with the initial pharmacological validation of this testing approach using a number of mechanistically diverse, commercially available antiseizure drugs, as well as several probe compounds that are of potential mechanistic interest to the clinical management of epilepsy.
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Affiliation(s)
| | - Kristina Johnson
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Peggy Billingsley
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Jennifer Huff
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Laura J Handy
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Rizvana Khaleel
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Zhenmei Lu
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Matthew J Mau
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Timothy H Pruess
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Carlos Rueda
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Gerald Saunders
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Tristan K Underwood
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Fabiola Vanegas
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Misty D Smith
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Peter J West
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Karen S Wilcox
- Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT, 84112, USA
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18
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Gee JM, Smith NA, Fernandez FR, Economo MN, Brunert D, Rothermel M, Morris SC, Talbot A, Palumbos S, Ichida JM, Shepherd JD, West PJ, Wachowiak M, Capecchi MR, Wilcox KS, White JA, Tvrdik P. Imaging activity in neurons and glia with a Polr2a-based and cre-dependent GCaMP5G-IRES-tdTomato reporter mouse. Neuron 2014; 83:1058-72. [PMID: 25155958 DOI: 10.1016/j.neuron.2014.07.024] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2014] [Indexed: 11/27/2022]
Abstract
UNLABELLED New strategies for introducing genetically encoded activity indicators into animal models facilitate the investigation of nervous system function. We have developed the PC::G5-tdT mouse line that expresses the GCaMP5G calcium indicator in a Cre-dependent fashion. Instead of targeting the ROSA26 locus, we inserted the reporter cassette nearby the ubiquitously expressed Polr2a gene without disrupting locus integrity. The indicator was tagged with IRES-tdTomato to aid detection of positive cells. This reporter system is effective in a wide range of developmental and cellular contexts. We recorded spontaneous cortical calcium waves in intact awake newborns and evaluated concentration-dependent responses to odorants in the adult olfactory bulb. Moreover, PC::G5-tdT effectively reports intracellular calcium dynamics in somas and fine processes of astrocytes and microglial cells. Through electrophysiological and behavioral analyses, we determined that GCaMP5G expression had no major impact on nervous system performance. PC::G5-tdT will be instrumental for a variety of brain mapping experiments. VIDEO ABSTRACT
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Affiliation(s)
- J Michael Gee
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112; MD-PhD Program, University of Utah, Salt Lake City, UT 84112
| | - Nathan A Smith
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112; Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112
| | - Fernando R Fernandez
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112
| | - Michael N Economo
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112
| | - Daniela Brunert
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112
| | - Markus Rothermel
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112
| | - S Craig Morris
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112
| | - Amy Talbot
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112
| | - Sierra Palumbos
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112
| | - Jennifer M Ichida
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112
| | - Jason D Shepherd
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112
| | - Peter J West
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112
| | - Matt Wachowiak
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112
| | - Mario R Capecchi
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112; Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112
| | - Karen S Wilcox
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112
| | - John A White
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112; Brain Institute, University of Utah, Salt Lake City, UT 84112.
| | - Petr Tvrdik
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112.
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West PJ, Saunders GW, Remigio GJ, Wilcox KS, White HS. Antiseizure drugs differentially modulate θ-burst induced long-term potentiation in C57BL/6 mice. Epilepsia 2014; 55:214-23. [PMID: 24447124 DOI: 10.1111/epi.12524] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2013] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Cognitive comorbidities are increasingly recognized as an equal (or even more disabling) aspect of epilepsy. In addition, the actions of some antiseizure drugs (ASDs) can impact learning and memory. Accordingly, the National Institute of Neurological Disorders and Stroke (NINDS) epilepsy research benchmarks call for the implementation of standardized protocols for screening ASDs for their amelioration or exacerbation of cognitive comorbidities. Long-term potentiation (LTP) is a widely used model for investigating synaptic plasticity and its relationship to learning and memory. Although the effects of some ASDs on LTP have been examined, none of these studies employed physiologically relevant induction stimuli such as theta-burst stimulation (TBS). To systematically evaluate the effects of multiple ASDs in the same preparation using physiologically relevant stimulation protocols, we examined the effects of a broad panel of existing ASDs on TBS-induced LTP in area CA1 of in vitro brain slices, prepared in either normal or sucrose-based artificial cerebrospinal fluid (ACSF), from C57BL/6 mice. METHODS Coronal brain slices containing the dorsal hippocampus were made using either standard or sucrose-based ACSF. Recordings were obtained from four slices at a time using the Scientifica Slicemaster high throughput recording system. Slices exposed to ASDs were paired with slices from the opposite hemisphere that served as controls. Field excitatory postsynaptic potentials (fEPSPs) were recorded, and all ASDs were applied to slices by bath perfusion for 20 min prior to the induction stimulus. LTP was induced by TBS or by high-frequency stimulation (HFS). The following ASDs were examined: 100 μM phenobarbital (PB), 80 μM phenytoin (PHT), 50 μM carbamazepine (CBZ), 600 μM valproate (VPA), 60 μM topiramate (TPM), 60 μM lamotrigine (LTG), 100 μM levetiracetam (LEV), 10 μM ezogabine (EZG), and 30 μM tiagabine (TGB). RESULTS Among voltage-gated sodium channel inhibitors, CBZ significantly attenuated TBS-induced LTP, PHT attenuated both TBS-induced LTP and post-tetanic potentiation (PTP), and LTG failed to affect LTP but did attenuate PTP. ASDs that modulate γ-aminobutyric acid (GABA)ergic synaptic transmission, such as PB and TGB, significantly attenuated LTP in brain slices prepared in sucrose-based ACSF but not standard ACSF. Third generation ASDs, such as LEV and TPM, did not affect LTP in ACSF- or sucrose-prepared brain slices. Although EZG failed to affect LTP, it did significantly attenuate PTP under both slicing conditions. VPA failed to affect LTP in area CA1, both in C57BL/6 mice and Sprague-Dawley rats, using TBS or HFS. However, VPA did attenuate TBS-induced LTP in the dentate gyrus (DG). SIGNIFICANCE The results of experiments describe herein provide a comprehensive summary of the effects of many commonly used ASDs on short- and long-term synaptic plasticity while, for the first time, using physiologically relevant LTP induction protocols and slice preparations from mice. Furthermore, methodologic variables, such as brain slice preparation protocols, were explored. These results provide comparative knowledge of ASD effects on synaptic plasticity in the mouse hippocampus and may ultimately contribute to an understanding of the differences in the cognitive side effect profiles of ASDs and the prediction of cognitive dysfunction associated with novel investigational ASDs.
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Affiliation(s)
- Peter J West
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A; Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, Utah, U.S.A; Interdepartmental Neuroscience Program, University of Utah, Salt Lake City, Utah, U.S.A
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Umpierre AD, Remigio GJ, Dahle EJ, Bradford K, Alex AB, Smith MD, West PJ, White HS, Wilcox KS. Impaired cognitive ability and anxiety-like behavior following acute seizures in the Theiler's virus model of temporal lobe epilepsy. Neurobiol Dis 2014; 64:98-106. [PMID: 24412221 DOI: 10.1016/j.nbd.2013.12.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/13/2013] [Accepted: 12/31/2013] [Indexed: 11/28/2022] Open
Abstract
Viral infection of the CNS can result in encephalitis and acute seizures, increasing the risk for later-life epilepsy. We have previously characterized a novel animal model of temporal lobe epilepsy that recapitulates key sequela in the development of epilepsy following viral infection. C57BL/6J mice inoculated with the Daniel's strain of Theiler's Murine Encephalomyelitis Virus (TMEV; 3×10(5) PFU, i.c.) display acute limbic seizures that secondarily generalize. A majority of acutely seized animals develop spontaneous seizures weeks to months later. As part of our investigation, we sought to assess behavioral comorbidity following TMEV inoculation. Anxiety, depression, cognitive impairment, and certain psychoses are diagnosed in persons with epilepsy at rates far more frequent than in the general population. We used a battery of behavioral tests to assess anxiety, depression, cognitive impairment, and general health in acutely seized animals inoculated with TMEV and compared behavioral outcomes against age-matched controls receiving a sham injection. We determined that TMEV-seized animals are less likely to move through the exposed center of an open field and are less likely to enter into the lighted half of a light/dark box; both behaviors may be indicative of anxiety-like behavior. TMEV-seized animals also display early and persistent reductions in novel object exploration during novel object place tasks and do not improve in their ability to find a hidden escape platform in Morris water maze testing, indicative of impairment in episodic and spatial memory, respectively. Cresyl violet staining at 35 and 250 days after injection reveals bilateral reductions in hippocampal area, with extensive sclerosis of CA1 evident bilaterally along the rostral-caudal axis. Early and persistent behavioral changes in the TMEV model provide surrogate markers for assessing disease progression as well as endpoints in screening for the efficacy of novel compounds to manage both seizure burden and comorbid conditions.
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Affiliation(s)
- Anthony D Umpierre
- Interdepartmental Program in Neuroscience, University of Utah, 1401 MREB, 20 North 1900 East, Salt Lake City, UT 84132
| | - Gregory J Remigio
- Interdepartmental Program in Neuroscience, University of Utah, 1401 MREB, 20 North 1900 East, Salt Lake City, UT 84132
| | - E Jill Dahle
- Department of Pharmacology and Toxicology, University of Utah
| | - Kate Bradford
- Department of Pharmacology and Toxicology, University of Utah
| | - Anitha B Alex
- Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA
| | - Misty D Smith
- Department of Pharmacology and Toxicology, University of Utah; Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA
| | - Peter J West
- Interdepartmental Program in Neuroscience, University of Utah, 1401 MREB, 20 North 1900 East, Salt Lake City, UT 84132; Department of Pharmacology and Toxicology, University of Utah; Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA
| | - H Steve White
- Interdepartmental Program in Neuroscience, University of Utah, 1401 MREB, 20 North 1900 East, Salt Lake City, UT 84132; Department of Pharmacology and Toxicology, University of Utah; Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA
| | - Karen S Wilcox
- Interdepartmental Program in Neuroscience, University of Utah, 1401 MREB, 20 North 1900 East, Salt Lake City, UT 84132; Department of Pharmacology and Toxicology, University of Utah; Anticonvulsant Drug Development Program, University of Utah, 417 Wakara Way, Suite 3211, Salt Lake City, UT 84108, USA.
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Wilson DJ, Chenery DH, Bowring HK, Wilson K, Turner R, Maughan J, West PJ, Ansell CWG. Physical and biological properties of a novel siloxane adhesive for soft tissue applications. Journal of Biomaterials Science, Polymer Edition 2012; 16:449-72. [PMID: 15887653 DOI: 10.1163/1568562053700200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The aim of this study was to investigate the adhesive properties of an in-house aminopropyltrimethoxysilane-methylenebisacrylamide (APTMS-MBA) siloxane system and compare them with a commercially available adhesive, n-butyl cyanoacrylate (nBCA). The ability of the material to perform as a soft tissue adhesive was established by measuring the physical (bond strength, curing time) and biological (cytotoxicity) properties of the adhesives on cartilage. Complementary physical techniques, X-ray photoelectron spectroscopy, Raman and infrared imaging, enabled the mode of action of the adhesive to the cartilage surface to be determined. Adhesion strength to cartilage was measured using a simple butt joint test after storage in phosphate-buffered saline solution at 37 degrees C for periods up to 1 month. The adhesives were also characterised using two in vitro biological techniques. A live/dead stain assay enabled a measure of the viability of chondrocytes attached to the two adhesives to be made. A water-soluble tetrazolium assay was carried out using two different cell types, human dermal fibroblasts and ovine meniscal chondrocytes, in order to measure material cytotoxicity as a function of both supernatant concentration and time. IR imaging of the surface of cartilage treated with APTMS-MBA siloxane adhesive indicated that the adhesive penetrated the tissue surface marginally compared to nBCA which showed a greater depth of penetration. The curing time and adhesion strength values for APTMS-MBA siloxane and nBCA adhesives were measured to be 60 s/0.23 MPa and 38 min/0.62 MPa, respectively. These materials were found to be significantly stronger than either commercially available fibrin (0.02 MPa) or gelatin resorcinol formaldehyde (GRF) adhesives (0.1 MPa) (P < 0.01). Cell culture experiments revealed that APTMS-MBA siloxane adhesive induced 2% cell death compared to 95% for the nBCA adhesive, which extended to a depth of approximately 100-150 microm into the cartilage surface. The WST-1 assay demonstrated that APTMS-MBA siloxane was significantly less cytotoxic than nBCA adhesive as an undiluted conditioned supernatant (P < 0.001). These results suggest that the APTMS-MBA siloxane may be a useful adhesive for medical applications.
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Affiliation(s)
- D J Wilson
- Smith & Nephew Research Centre, York Science Park, Heslington, York YO10 5DF, UK.
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West PJ, Marcy VR, Marino MJ, Schaffhauser H. Activation of the 5-HT(6) receptor attenuates long-term potentiation and facilitates GABAergic neurotransmission in rat hippocampus. Neuroscience 2009; 164:692-701. [PMID: 19660530 DOI: 10.1016/j.neuroscience.2009.07.061] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 07/24/2009] [Accepted: 07/28/2009] [Indexed: 11/16/2022]
Abstract
The 5-HT(6) receptor is predominantly expressed in the CNS and has been implicated in the regulation of cognitive function. Antagonists of the 5-HT(6) receptor improve cognitive performance in a number of preclinical models and have recently been found to be effective in Alzheimer's disease patients. Systemic administration of 5-HT(6) antagonists increases the release of acetylcholine and glutamate in the frontal cortex and dorsal hippocampus. In contrast, the selective 5-HT(6) agonist, WAY-181187, can elicit robust increases in extracellular levels of GABA. The reported behavioral and neurochemical effects of 5-HT(6) receptor ligands raise the possibility that the 5-HT(6) receptor may modulate synaptic plasticity in the hippocampus. In the present study, selective pharmacological tools were employed to determine the effect of 5-HT(6) receptor activation on long-term potentiation (LTP) in brain slices containing area CA1 of the hippocampus. While having no effect on baseline synaptic transmission, the results demonstrate that the selective 5-HT(6) agonist, WAY-181187, attenuated LTP over a narrow dose range (100-300 nM). The increase in the slope of the field excitatory post synaptic potential (fEPSP) caused by theta burst stimulation in brain slices treated with the most efficacious dose of WAY-181187 (200 nM) was 80.1+/-4.0% of that observed in controls. This effect was dose-dependently blocked by the selective 5-HT(6) antagonist, SB-399885. WAY-181187 also increased the frequency of spontaneous GABA release in area CA1. As assessed by measuring and evaluating spontaneous inhibitory postsynaptic currents (sIPSCs), 200 nM WAY-181187 increased sIPSC frequency by 3.4+/-0.9 Hz. This increase in GABA sIPSCs was prevented by the selective 5-HT(6) antagonist SB-399885 (300 nM). Taken together, these results suggest that the 5-HT(6) receptor plays a role in the modulation of synaptic plasticity in hippocampal area CA1 and that the regulation of GABAergic interneuron activity may underlie the cognition enhancing effects of 5-HT(6) antagonists.
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Affiliation(s)
- P J West
- Worldwide Discovery Research, Cephalon, Inc., West Chester, PA 19380, USA.
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West PJ, Dalpé-Charron A, Wilcox KS. Differential contribution of kainate receptors to excitatory postsynaptic currents in superficial layer neurons of the rat medial entorhinal cortex. Neuroscience 2007; 146:1000-12. [PMID: 17395391 PMCID: PMC2921318 DOI: 10.1016/j.neuroscience.2007.02.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 02/02/2007] [Accepted: 02/19/2007] [Indexed: 02/02/2023]
Abstract
Although in situ hybridization studies have revealed the presence of kainate receptor (KAR) mRNA in neurons of the rat medial entorhinal cortex (mEC), the functional presence and roles of these receptors are only beginning to be examined. To address this deficiency, whole cell voltage clamp recordings of locally evoked excitatory postsynaptic currents (EPSCs) were made from mEC layer II and III neurons in combined entorhinal cortex-hippocampal brain slices. Three types of neurons were identified by their electroresponsive membrane properties, locations, and morphologies: stellate-like "Sag" neurons in layer II (S), pyramidal-like "No Sag" neurons in layer III (NS), and "Intermediate Sag" neurons with varied morphologies and locations (IS). Non-NMDA EPSCs in these neurons were composed of two components, and the slow decay component in NS neurons had larger amplitudes and contributed more to the combined EPSC than did those observed in S and IS neurons. This slow component was mediated by KARs and was characterized by its resistance to either 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI 52466, 100 microM) or 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[lsqb]f[rsqb]quinoxaline-7-sulfonamide (NBQX, 1 microM), relatively slow decay kinetics, and sensitivity to 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10-50 microM). KAR-mediated EPSCs in pyramidal-like NS neurons contributed significantly more to the combined non-NMDA EPSC than did those from S and IS neurons. Layer III neurons of the mEC are selectively susceptible to degeneration in human temporal lobe epilepsy (TLE) and animal models of TLE such as kainate-induced status epilepticus. Characterizing differences in the complement of postsynaptic receptors expressed in injury prone versus injury resistant mEC neurons represents an important step toward understanding the vulnerability of layer III neurons seen in TLE.
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Affiliation(s)
- P J West
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA
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Bulaj G, West PJ, Garrett JE, Watkins M, Zhang MM, Norton RS, Smith BJ, Yoshikami D, Olivera BM. Novel Conotoxins from Conus striatus and Conus kinoshitai Selectively Block TTX-Resistant Sodium Channels. Biochemistry 2006. [DOI: 10.1021/bi068001c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
δ-Conotoxins are a family of small, disulfide-rich peptides found in the venoms of predatory cone snails ( Conus). We examined in detail the effects of δ-conotoxin PVIA from the fish hunting cone snail Conus purpurascens on sodium currents in dissociated sympathetic neurons from the leopard frog Rana pipiens. We also compared this toxin’s effects with those of δ-conotoxin SVIE from Conus striatus, another piscivorous cone snail. d-PVIA slowed the time-course of inactivation of δ sodium currents and shifted the voltage-dependence of activation and steady-state inactivation to more hyperpolarized potentials. Similar, albeit more pronounced, effects were seen with d-SVIE. While the effects of d-PVIA were reversed by washing, those of d-SVIE were largely irreversible over the time-course of these experiments. The effects of d-PVIA could be suppressed by conditioning depolarizations in a voltage- and time-dependent manner, whereas the effects of d-SVIE were largely resistant to conditioning depolarizations. Last, in intact sympathetic nervous system preparations, d-PVIA inhibited evoked trains of compound action potentials. Many of these effects of d-PVIA and d-SVIE are remarkably similar to those of toxins that bind to site 3 on voltage-gated sodium channels.
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Affiliation(s)
- Peter J West
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, 84112, USA
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Bulaj G, West PJ, Garrett JE, Watkins M, Marsh M, Zhang MM, Norton RS, Smith BJ, Yoshikami D, Olivera BM. Novel Conotoxins from Conus striatus and Conus kinoshitai Selectively Block TTX-Resistant Sodium Channels. Biochemistry 2005; 44:7259-65. [PMID: 15882064 DOI: 10.1021/bi0473408] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The peptides isolated from venoms of predatory marine Conus snails ("conotoxins") are well-known to be highly potent and selective pharmacological agents for voltage-gated ion channels and receptors. We report the discovery of two novel TTX-resistant sodium channel blockers, mu-conotoxins SIIIA and KIIIA, from two species of cone snails. The two toxins were identified and characterized by combining molecular techniques and chemical synthesis. Both peptides inhibit TTX-resistant sodium currents in neurons of frog sympathetic and dorsal root ganglia but poorly block action potentials in frog skeletal muscle, which are mediated by TTX-sensitive sodium channels. The amino acid sequences in the C-terminal region of the two peptides and of the previously characterized mu-conotoxin SmIIIA (which also blocks TTX-resistant channels) are similar, but the three peptides differ in the length of their first N-terminal loop. We used molecular dynamics simulations to analyze how altering the number of residues in the first loop affects the overall structure of mu-conotoxins. Our results suggest that the naturally occurring truncations do not affect the conformation of the C-terminal loops. Taken together, structural and functional differences among mu-conotoxins SmIIIA, SIIIA, and KIIIA offer a unique insight into the "evolutionary engineering" of conotoxin activity.
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Affiliation(s)
- Grzegorz Bulaj
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
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Price GJ, Garland L, Comina J, Davis M, Snell DJ, West PJ. Investigation of radical intermediates in polymer sonochemistry. Res Chem Intermed 2004. [DOI: 10.1163/1568567041856972] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Keizer DW, West PJ, Lee EF, Yoshikami D, Olivera BM, Bulaj G, Norton RS. Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA. J Biol Chem 2003; 278:46805-13. [PMID: 12970353 DOI: 10.1074/jbc.m309222200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SmIIIA is a new micro-conotoxin isolated recently from Conus stercusmuscarum. Although it shares several biochemical characteristics with other micro-conotoxins (the arrangement of cysteine residues and a conserved arginine believed to interact with residues near the channel pore), it has several distinctive features, including the absence of hydroxyproline, and is the first specific antagonist of tetrodotoxin-resistant voltage-gated sodium channels to be characterized. It therefore represents a potentially useful tool to investigate the functional roles of these channels. We have determined the three-dimensional structure of SmIIIA in aqueous solution. Consistent with the absence of hydroxyprolines, SmIIIA adopts a single conformation with all peptide bonds in the trans configuration. The spatial orientations of several conserved Arg and Lys side chains, including Arg14 (using a consensus numbering system), which plays a key role in sodium channel binding, are similar to those in other micro-conotoxins but the N-terminal regions differ, reflecting the trans conformation for the peptide bond preceding residue 8 in SmIIIA, as opposed to the cis conformation in micro-conotoxins GIIIA and GIIIB. Comparison of the surfaces of SmIIIA with other micro-conotoxins suggests that the affinity of SmIIIA for TTX-resistant channels is influenced by the Trp15 side chain, which is unique to SmIIIA. Arg17, which replaces Lys in the other micro-conotoxins, may also be important. Consistent with these inferences from the structure, assays of two chimeras of SmIIIA and PIIIA in which their N- and C-terminal halves were recombined, indicated that residues in the C-terminal half of SmIIIA confer affinity for tetrodotoxin-resistant sodium channels in the cell bodies of frog sympathetic neurons. SmIIIA and the chimera possessing the C-terminal half of SmIIIA also inhibit tetrodotoxin-resistant sodium channels in the postganglionic axons of sympathetic neurons, as indicated by their inhibition of C-neuron compound action potentials that persist in the presence of tetrodotoxin.
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Affiliation(s)
- David W Keizer
- The Walter & Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
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West PJ, Bulaj G, Garrett JE, Olivera BM, Yoshikami D. Mu-conotoxin SmIIIA, a potent inhibitor of tetrodotoxin-resistant sodium channels in amphibian sympathetic and sensory neurons. Biochemistry 2002; 41:15388-93. [PMID: 12484778 DOI: 10.1021/bi0265628] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mu-conotoxins are a family of peptides from the venoms of predatory cone snails. Previously characterized mu-conotoxins preferentially block skeletal muscle voltage-gated sodium channels. We report here the discovery (via cloning), synthesis, and electrophysiological characterization of a new peptide in this family, mu-conotoxin SmIIIA from Conus stercusmuscarum. Although mu-conotoxin SmIIIA shares several biochemical characteristics with other mu-conotoxins (the arrangement of cysteine residues and a conserved arginine believed to interact with residues near the channel pore), it has distinctive features such as the absence of hydroxyproline. In voltage-clamped dissociated neurons from frog sympathetic and dorsal root ganglia, the peptide inhibited the majority of tetrodotoxin-resistant sodium currents irreversibly; in contrast, tetrodotoxin-sensitive sodium currents were largely unaffected by the peptide. We believe that mu-conotoxin SmIIIA is the first specific antagonist of tetrodotoxin-resistant voltage-gated sodium channels to be discovered. Thus, the peptide provides a new and potentially useful tool to investigate the functional roles of tetrodotoxin-resistant voltage-gated sodium channels, including those that are found in sensory nerves that convey nociceptive information.
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Affiliation(s)
- Peter J West
- Interdepartmental Program in Neuroscience and Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA
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Colevas AD, West PJ, Cheson BD. Clinical trials referral resource. Current clinical trials of epothilone B analog (BMS-247550). Oncology (Williston Park) 2001; 15:1168-9, 1172-5. [PMID: 11589064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Saxman SB, West PJ, Cheson BD. Clinical trials referral resource. Current clinical trials in small-cell lung cancer. Oncology (Williston Park) 2001; 15:318-9, 323. [PMID: 11301830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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West PJ. Chemotherapy audit--a confidence builder. Can Oncol Nurs J 2000; 9:189. [PMID: 10786474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Affiliation(s)
- P J West
- Lakeridge Health, Oshawa, Ontario
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West PJ. Getting down to the bare bones.... Can Oncol Nurs J 1999; 9:51. [PMID: 10232146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- P J West
- Lakeridge Health, Oshawa, Ontario
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Craig AG, Zafaralla G, Cruz LJ, Santos AD, Hillyard DR, Dykert J, Rivier JE, Gray WR, Imperial J, DelaCruz RG, Sporning A, Terlau H, West PJ, Yoshikami D, Olivera BM. An O-glycosylated neuroexcitatory conus peptide. Biochemistry 1998; 37:16019-25. [PMID: 9819194 DOI: 10.1021/bi981690a] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We purified and characterized a novel peptide from the venom of the fish-hunting cone snail Conus striatus that inhibits voltage-gated K+ channels. The peptide, kappaA-conotoxin SIVA, causes characteristic spastic paralytic symptoms when injected into fish, and in frog nerve-muscle preparations exposed to the toxin, repetitive action potentials are seen in response to a single stimulus applied to the motor nerve. Other electrophysiological tests on diverse preparations provide evidence that is consistent with the peptide blocking K+ channels. The peptide has three disulfide bonds; the locations of Cys residues indicate that the spastic peptide may be the first and defining member of a new family of Conus peptides, the kappaA-conotoxins, which are structurally related to, but pharmacologically distinct from, the alphaA-conotoxins. This 30 AA tricyclic toxin has several characteristics not previously observed in Conus peptides. In addition to the distinctive biological and physiological activity, a novel biochemical feature is the unusually long linear N-terminal tail (11 residues) which contains one O-glycosylated serine at position 7. This is the first evidence for O-glycosylation as a posttranslational modification in a biologically active Conus peptide.
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Affiliation(s)
- A G Craig
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, San Diego, California 92186-5800, USA
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Güdde J, Klinkmüller A, West PJ, Matthias E. Second-order magnetic contributions to the hyperfine splitting of the 5snd 1D2 states in 87Sr. Phys Rev A 1993; 47:4725-4734. [PMID: 9909499 DOI: 10.1103/physreva.47.4725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Sun J, Matthias E, Heber K, West PJ, Güdde J. Impact-broadening cross sections of Rydberg levels of alkaline-earth atoms by collision with rare gases at thermal energy. Phys Rev A 1991; 43:5956-5965. [PMID: 9904924 DOI: 10.1103/physreva.43.5956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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41
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Heber K, West PJ, Matthias E. Pressure shift and broadening of Sr I Rydberg states in noble gases. Phys Rev A Gen Phys 1988; 37:1438-1448. [PMID: 9899815 DOI: 10.1103/physreva.37.1438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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42
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West PJ, Bartelt RC. Medicolegal aspects of urology. Urol Clin North Am 1980; 7:153-63. [PMID: 7376301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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43
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44
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Barton DHR, Chavis C, Kaloustian MK, Magnus PD, Poulton GA, West PJ. Photochemical transformations. Part XXXI. Photolysis of thiobenzoic acid O-esters. Part II. General methods for the preparation of thiobenzoic acid O-esters. ACTA ACUST UNITED AC 1973. [DOI: 10.1039/p19730001571] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Achmatowicz S, Barton DH, Magnus PD, Poulton GA, West PJ. Photochemical transformations. XXX. Photolysis of thiobenzoic acid O-esters. I. Photolysis of O-cholesteryl thiobenzoate. J Chem Soc Perkin 1 1973; 15:1567-70. [PMID: 4796391 DOI: 10.1039/p19730001567] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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46
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Barton DHR, Bolton M, Magnus PD, Marathe KG, Poulton GA, West PJ. Photochemical transformations. Part XXXII. Photolysis of thiobenzoic acid O-esters. Part III. Photolysis of O-phenethyl thiobenzoates and other thiobenzoates. ACTA ACUST UNITED AC 1973. [DOI: 10.1039/p19730001574] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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47
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Barton DHR, Bolton M, Magnus PD, West PJ. Photochemical transformations. Part XXXIII. Photolysis of thiobenzoic acid O-esters. Part IV. Photolysis of O-phenethyl thiobenzoate derivatives and the formation of thioketones. ACTA ACUST UNITED AC 1973. [DOI: 10.1039/p19730001580] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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48
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Walker CH, West PJ. Indirect estimation of systolic and diastolic blood pressure in the newborn: an impedance plethysmographic method using standard ECG recorders. Pediatrics 1972; 50:387-94. [PMID: 5056412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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49
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Strauss R, West PJ, Silverman FN. Unilateral proptosis in cystic fibrosis. Pediatrics 1969; 43:297-300. [PMID: 5763864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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