1985 — 2006 |
Dudek, F. Edward |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Local Interactions Between Hippocampal Neurons @ Colorado State University-Fort Collins
DESCRIPTION (provided by applicant): Many studies have analyzed axonal sprouting and synaptic reorganization of local excitatory circuits in animal models of temporal lobe epilepsy, but relatively little electrophysiological research at the single-neuron level has been conducted on reorganization of local inhibitory circuits during epileptogenesis. Furthermore, the dynamic properties of these reorganized circuits during repetitive synaptic activation, as expected during the onset of hippocampal seizures, are relatively unknown The general questions to be addressed in the proposed experiments are what are the short- and long-term alterations in local inhibitory circuits after status epilepticus, and does synaptic depression during repetitive activation of these circuits contribute to seizure propagation during chronic epileptogenesis? The proposed experiments will use hippocampal slices from rats with kainate-induced epilepsy to determine how loss of synaptic input and subsequent synaptic reorganization after status epilepticus leads to changes in local inhibitory circuits in the dentate gyrus and the CA1 area Inhibitory circuits in these two hippocampal areas appear to be different after SE The experiments will address the following specific questions (1) Does axonal sprouting of principal neurons in the hippocampus (e g, dentate granule cells and CA1 pyramidal cells) lead to formation of functional excitatory synapses on inhibitory interneurons? (2) Do interneurons sprout axon collaterals, and form new inhibitory synapses with principal neurons? (3) How does repetitive activation of local inhibitory circuits alter transmission through this network, and are these areas of the hippocampus abnormally sensitive to repetitive activation at periods after status epilepticus when recurrent spontaneous seizures occur? Aim 3 will utilize frequencies of repetitive stimulation that simulate the patterns of synaptic activation observed at the onset of chronically recorded electrographic seizures in rats with kainate-induced epilepsy These experiments aim to provide increased understanding about the reorganization of inhibitory circuits that may contribute to temporal lobe epilepsy, and how activity-dependent depression of local inhibitory circuits may promote the spread of epileptic seizures The systems to be investigated are prime targets for therapeutic intervention to prevent seizures in people with intractable temporal lobe epilepsy.
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1.009 |
1988 — 1990 |
Dudek, F. Edward |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Opiates, Tolerance and Hypothalamic Electrophysiology @ University of California Los Angeles
The proposed research will determine the electrophysiological effects of opiates and opioid peptides on hypothalamic neuroendocrine cells that secrete the peptide hormones, vasopressin and oxytocin. Endogenous opioid peptides regulate secretion of these hormones, and opiates have dramatic effects on this model neuroendocrine system. These hormones control several reproductive and homeostatic mechanisms (e.g., opiates depress lactation and parturition through actions in the hypothalamus). Parvocellular neurons and magnocellular neuropeptidergic cell. (MNCs) of the paraventricular and supraoptic nuclei (PVN and SON) will be studied with intracellular recording and staining; many of the recorded neurons will be immunocytochemically identified as oxytocinergic or vasopressinergic. The experimental system will be the in vitro hypothalamic slice preparation from adult rats and guinea pigs. Agonists and antagonists will be bath-perfused or microapplied with pressure through multibarrel micropipettes onto the slice, and effects on electrical properties will be determined. Based on previous studies, the main hypothesis to be tested is that opioid peptides and opiates act directly through a mu receptor to inhibit oxytocinergic neurons. This hypothetical mechanism of action is an increase in K+ conductance. One question to be examined is whether these agents have the same or different effect(s) on all PVN and SON neurons (i.e., neurons in different subnuclei and of different peptidergic content). We will determine whether opiates decrease the duration of action potentials, reduce responsiveness to other synaptic inputs, depress burst discharges and augment post-burst afterhyperpolarizations. The hypothesis that chronic morphine treatment leads to tolerance, dependence and withdrawal in the oxytocin system through direct alterations in membrane properties of oxytocinergic MNCs will also be tested. These electrophysiological hypotheses will be examined with intracellular recording (current-clamp and single-electrode voltage clamp). The proposed studies will provide fundamental information concerning opiate actions on the electrophysiology of identified cells in the magnocellular neuroendocrine system, a model regulatory site in the mammalian hypothalamus.
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0.985 |
1999 — 2003 |
Dudek, F. Edward |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Local Neuronal Circuits of the Suprachiasmatic Nucleus @ Colorado State University-Fort Collins |
0.965 |
2003 — 2007 |
Dudek, F. Edward |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Progression of Temporal Lobe Epilepsy @ Colorado State University-Fort Collins |
1.009 |
2004 — 2005 |
Dudek, F. Edward |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Pharmacoresistance in Rats With Kainate-Induced Epilepsy
DESCRIPTION (provided by applicant): Approximately 30-40% of people with epilepsy continue to have seizures during treatment with antiepileptic drugs (AED). These individuals are considered to be intractable or "pharmacoresistant" if they do not become seizure-free after treatment with two AED, and often they continue to have seizures during polytherapy protocols that may include three or more AED. A recent consensus report from an NIH-supported workshop has suggested that animal models of chronic epilepsy with spontaneous recurrent seizures, following a latent period from electrically or chemically induced status epilepticus, may be useful for identifying new AED for the pharmacoresistant population. We have developed a repeated-measures crossover protocol to test potential AED in rats with kainate-induced epilepsy. In an initial study, these rats showed a dose-dependent decrease in seizures after single intraperitoneal injections of topiramate, but continued to have seizures after the highest dose (i.e., 100 mg/kg). The proposed experiments will use behavioral analysis of videotaped motor seizures (with blind procedures) during variations of this repeated-measures cross-over design to address the following issues: Are rats with kainate-induced epilepsy pharmacoresistant to high doses of topiramate lasting several days? Are they resistant to similar treatments of carbamazepine, which is probably the most widely used AED? Are these rats pharmacoresistant to topiramate when it is used as an "add-on" during continuous treatment with carbamazepine? Finally, some of these same experimental protocols will be used to study the effects of AED on spontaneous electrographic seizures in experiments on rats that have been implanted with intracranial hippocampal and subdural screw electrodes, which will allow direct assessment of AED on non-convulsive seizures. One long-term goal of this research is to test the hypothesis that these AED are effective early in the epileptogenic process, but not at later time points when seizures are more frequent and severe. The experiments in this proposal aim to determine whether rats with kainate-induced epilepsy show pharmacoresistance, and whether this animal model of spontaneous recurrent seizures is suitable for testing new AED designed against pharmacoresistant epilepsy.
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1.009 |
2009 — 2010 |
Dudek, F. Edward Lehmkuhle, Mark J. |
R43Activity Code Description: To support projects, limited in time and amount, to establish the technical merit and feasibility of R&D ideas which may ultimately lead to a commercial product(s) or service(s). |
Miniature Eeg Telemetry Device For Translational Epilepsy Research
DESCRIPTION (provided by applicant): Long-term continuous recording of electrical events from animal models of neurological disease is a critical component of translational research aimed at developing new therapies for debilitating disorders, such as epilepsy. Recordings of the electroencephalogram (EEG) can be obtained for weeks or months at a time from adult rats with either tethered (i.e., "wired") or telemetric (i.e., "wireless") recording systems;however, both of these systems have problems. The proposed studies will further develop and validate a miniature telemetry system (i.e., the EpiTel device) that will be optimized to record continuous (i.e., virtually uninterrupted) electrographic activity from rodent models of neurological disorders, such as intractable epilepsy. The fundamental principle of the EpiTel device is that a small self-contained telemetry unit with easily replaceable and inexpensive batteries is secured to the rodent's head. If this unit is damaged, it can be readily replaced. A provisional patent for the EpiTel device has been submitted. The proposed experiments will use animal models of acquired epilepsy, and will aim to obtain stable long-term continuous recordings from adult rats and mice with convulsive seizures. The long-term goal is for researchers to be able to use the EpiTel device in translational research to develop new therapies for different types of animal models of acquired epilepsy. We have preliminary "proof-of-principle" data, but aim to test the newly-developed EpiTel device in rat and mouse models of epilepsy. The goal in Phase I is to show that it is feasible to obtain long-term continuous recordings (i.e., for many months at a time). Ultimately, the EpiTel device could also be adapted to immature rats in order to allow studies of pediatric epilepsy. These experiments will allow better validation of animal models of epilepsy and other neurological disorders. The ability to obtain long-term continuous recordings should facilitate the development of new therapies to suppress epileptic seizures and potentially to block the development of chronic epilepsy after brain injury. PUBLIC HEALTH RELEVANCE: This grant proposal aims to develop and validate a new miniature telemetry system for rats and mice that should facilitate translational research on animal models of epilepsy.
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0.902 |
2011 — 2016 |
Dudek, F. Edward Lehmkuhle, Mark J. |
R44Activity Code Description: To support in - depth development of R&D ideas whose feasibility has been established in Phase I and which are likely to result in commercial products or services. SBIR Phase II are considered 'Fast-Track' and do not require National Council Review. |
Epoch Telemetry System For Long-Term Monitoring of Biopotentials
DESCRIPTION (provided by applicant): Epoch Telemetry System for Long-Term Monitoring of Biopotentials ABSTRACT Neonatal and childhood seizures can increase an individual's susceptibility for developing epilepsy later in life. Obtaining long-term continuous recordings of electrical events, such as the electroencephalogram (EEG), from animal models of neurological disease is a critical component of translational research aimed at developing new therapies for debilitating disorders, such as epilepsy. Many immature- and adult-rodent models have recently been developed that are surrogates for human manifestations of seizures in the pediatric and adult populations. While tethered (i.e., wired) recordings of the EEG can be obtained periodically (i.e., for minutes to a few hours per session in rodent pups) these recordings have problems associated with the small size of rodent pups and their reliance upon the dam early in life up to weaning at postnatal day 21 (P21) in rats. Likewise, EEG recordings can be obtained for weeks or months at a time from adult rats with either tethered or telemetric (i.e., wireless) recording systems; however, both of these systems have problems. The younger the animal, the more difficult it is to obtain adequate recordings, and it is nearly impossible to obtain continuous, uninterrupted recordings. The fundamental principle of the Epoch recording system is that the capacitive-coupled technology combined with the small shape and low profile of the telemetry unit will allow multiple rats or mice to be recorded simultaneously, enabling continuous EEG, cranial temperature, and video recordings. In the Phase I program, Epitel, Inc., developed a small (<1 cc, <1 g) wireless device that enables uninterrupted, EEG recordings from up to four EEG channels in rats age P7 and mice age P12 through weaning and adulthood (i.e., continuously for many months at a time) that is the basis of the Epoch recording system. The long-term goal is for researchers to be able to use the Epoch system in translational research to develop new therapies for different types of animal models of acquired and genetic pediatric epilepsy and ultimately, other neonatal- and adult-rodent models of human disease. The ability to obtain long-term continuous recordings should facilitate answering the question of how and when to treat seizures in neonates, children, and adults, potentially blocking the development of chronic epilepsy after brain injury.
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0.902 |
2012 — 2015 |
Dudek, F. Edward Van Den Pol, Anthony N (co-PI) [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Ivermectin and Human Glycine Receptor Suppression of Pharmacoresistant Epilepsy
DESCRIPTION (provided by applicant): Modern drug-discovery research over the last two decades aimed at improving the pharmacological treatment of epileptic seizures has resulted in more than a dozen new anti- epileptic drugs (AEDs). Although these new AEDs may have reduced side effects and drug- drug interactions, the percentage of epileptic patients who continue to have seizures while treated with the new AEDs has remained at 30-40% for >20 years. In this proposal, we aim to develop a gene-therapy approach to treat pharmacoresistant epilepsy through the implementation of a novel designer receptor system that should not affect normal brain function, and therefore is less likely to have significant side-effects. This system will utilize adeno-associated viral (AAV) delivery of a modified human ¿1glycine receptor with reduced glycine sensitivity and enhanced sensitivity to the FDA-approved drug, ivermectin. Recombinant AAVs will be genetically optimized for expression in epileptic neurons and tested for efficacy in animal models of epilepsy. Ivermectin, which has minimal effects on the normal brain at the very low concentrations necessary to activate the modified receptor, will then act as an AED specifically at the site of generation of the epileptic seizures, thus suppressing epileptic seizures without affecting normal brain function. These studies are intended to lead directly to clinical trials. The use of a human receptor and an FDA approved drug should facilitate this advancement from bench side to clinical treatment so that by the end of the 4 year grant, we will have a gene transfer vector in hand that could be considered for clinical trials in pharmacoresistant epilepsy patients.
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1.009 |
2012 — 2013 |
Dudek, F. Edward |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Targeted Interneuron Ablation and Epileptogenesis
DESCRIPTION (provided by applicant): Loss of GABAergic interneurons is a major feature of temporal lobe epilepsy, both in human patients as well as animal models. The aim of the proposed research is to determine whether selective, focal interneuron lesions result in interictal spikes and seizures. This research will test the hypothesis that interneuron loss, independent of other local-circuit mechanisms, contributes significantly to the generation of epileptic seizures. The proposed studies will utilize a neurotoxin approach, as well as an independent genetic technique, to selectively ablate interneurons. The two approaches will initially lesion heterogeneous populations of interneurons, but subsequent studies will focus on specific sub-types of interneurons. The interneuron ablations will be followed by continuous in vivo video-LFP monitoring and in vitro assessment of the electrophysiological properties of the remaining principal cells and their networks. The results of these experiments will improve our understanding of the role that the loss of GABAergic interneurons plays in seizure generation and epileptogenesis.
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1.009 |
2013 — 2017 |
Dudek, F. Edward Staley, Kevin J. [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Biomarkers For Epileptogenesis After Brain Injury @ Massachusetts General Hospital
DESCRIPTION (provided by applicant): The latent period between brain injury and subsequent epilepsy is months to years in duration, providing a unique window for antiepileptogenic therapy. Recent reports of promising experimental disease-modifying therapies can't advance to clinical trials until three hurdles are overcome: First, quantification f epilepsy is necessary to assess efficacy of interventions, but epilepsy after brain injury is very difficult to quantify: the latency to first seizure is long and variable, and early seizures are ofen subtle, infrequent, and clustered between long inter-cluster intervals. Second, because of the long latency between injury and epilepsy, clinical trials need to be quite prolonged and therefore prohibitively expensive. Third, because ~ 20% of moderately brain-injured patients develop epilepsy, most of the treated patients could not benefit from long-term antiepileptogenic therapy, despite exposure to the risks and side effects. These three hurdles could be overcome with sufficiently accurate biomarkers. We recently demonstrated that early electrographic epileptiform activity is a promising predictor of epilepsy after brain injury induced by kainic aci. Here we propose to address critical knowledge gaps regarding electrographic biomarkers of epileptogenesis. The predictive power of electrographic biomarkers has not been assessed after more clinically relevant injuries such as trauma and hypoxic-ischemic injury. The predictive power of electrographic biomarkers has not been systematically compared to the predictive power of traditional physical descriptors of injury, such as lesion size and location. Furthermore, it has not been determined whether combining electrographic and physical-injury parameters would improve their predictive power. We will employ well-established models of clinical injuries, the lateral fluid percussion (LFP) trauma model and the Rice- Vannucci model of focal hypoxia-ischemia in P30 rats. The incidence of epilepsy in these models is close to the human experience, and thus provides a more rigorous test of the predictive power of these biomarkers than the kainate model. Further, the latency to seizures is sufficiently long in these models to enable testing as to whether the appearance of early electrographic biomarkers is more closely related to the time elapsed since the injury, or to the time remaining prior to the first seizure; he nature of these relationships will significantly impact the design of clinical studies of these biomarkers. In Aim 1, we will use a novel miniature telemetry device for continuous recording of video-EEG together with validated, unbiased computer detection algorithms to quantify early epileptiform activity and seizures in these brain injury models. We will optimize EEG sampling and develop the best predictive model based on epileptiform electrographic activity and injury descriptors, and then prospectively test this model in a second group of animals. In Aim 2, we will use the same approach to test whether early electrographic epileptiform activity and injury descriptors predict the severity of epilepsy, including latency to first seizure and seizure frequency, once epilepsy is fully developed.
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0.916 |
2017 — 2018 |
Berdichevsky, Yevgeny (co-PI) [⬀] Dudek, F. Edward Dulla, Chris G Staley, Kevin J. [⬀] |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Anticonvulsant Screening Using Chronic Epilepsy Models @ Massachusetts General Hospital
Abstract The NINDS Anticonvulsant Screening Program (ASP) has identified most of the anticonvulsants in clinical use today. However, one third of epileptic patients do not respond to these drugs. The ASP protocols are based on seizures induced by subjecting normal animals to acute convulsant conditions. We have developed a complimentary system of novel in vitro and in vivo assays of spontaneous seizures in chronically epileptic preparations. This two-stage screening system provides a unique focus on recurrent spontaneous seizures in chronic epilepsy models. The first stage is an in vitro assay comprised of the organotypic hippocampal slice culture, which develops electrographic seizure activity and corresponding biochemical biomarkers over the first week in vitro. The second stage is an in vivo assay comprised of the kainate model of epilepsy in which spontaneous seizures are monitored using continuous telemetry and supervised, blinded, computerized seizure detection. We used the rapid in vitro assay to screen over 400 compound-concentration combinations from the NINDS Custom Compound Collection. We found a lead compound, celecoxib, and then verified this lead by the second-stage testing in a randomized double blind in vivo crossover trial. Celecoxib had no effect on seizures induced by acute application of convulsants to normal brain tissue, suggesting that its anticonvulsant properties are unique to chronic epilepsy, and raising the possibility that its spectrum of action will be distinct from anticonvulsants discovered by the ASP protocols. The next step in development is medicinal chemistry to optimize celecoxib?s anticonvulsant efficacy. This is most feasibly accomplished through the UH2 / UH3 Blueprint Neurotherapeutics Network. As our discussions with BPN program officers clarified, to efficiently utilize the BPN medicinal chemistry program we must further develop the in vitro and in vivo assays and acquire additional data on our lead compound. The UH2/3 mechanism was considered the most appropriate funding mechanism by the NINDS program officer. In the R21 phase of this proposal, we will extend the in vitro assay?s concentration-response for celecoxib and 2,5 dimethyl celecoxib, a derivative that does not inhibit COX2 but has equal anticonvulsant efficacy in vitro. We will then characterize the assay?s reproducibility and Z factor. We will also establish the dose-response of the in vivo assays for celecoxib, and increase the number of in vitro and in vivo sites to two each in order to improve robustness and throughput, as well as engage outstanding younger investigators in this effort. In the R33 phase of the proposal, we will further characterize the lead compound by determining whether COX2 inhibition is necessary for anticonvulsant activity in the in vitro and in vivo assays.
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0.916 |