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12 results on '"Richards, Douglas A."'

1. Contributors

Author

Aagaard, Kjersti, primary, Adams, Kristina M., additional, Altemus, Margaret, additional, Annas, George J., additional, Antony, Kathleen M., additional, Bailit, Jennifer L., additional, Baschat, Ahmet Alexander, additional, Berghella, Vincenzo, additional, Bernstein, Helene B., additional, Bhide, Amar, additional, Birsner, Meredith, additional, Bogen, Debra L., additional, Branch, D. Ware, additional, Briggs, Gerald G., additional, Brown, Haywood L., additional, Bucklin, Brenda A., additional, Burton, Graham J., additional, Cappell, Mitchell S., additional, Carpenter, Jeanette R., additional, Catalano, Patrick M., additional, Chandrasekaran, Suchitra, additional, Colombo, David F., additional, Copeland, Larry J., additional, Deen, Jason, additional, Deering, COL Shad H., additional, Desai, Mina, additional, Dildy, Gary A., additional, Dombrowski, Mitchell P., additional, Driscoll, Deborah A., additional, Druzin, Maurice L., additional, Duff, Patrick, additional, Easterling, Thomas, additional, Elias, Sherman, additional, Ervin, M. Gore, additional, Foley, Michael R., additional, Francois, Karrie E., additional, Gabbe, Steven G., additional, Galan, Henry L., additional, Garrison, Etoi, additional, Gerard, Elizabeth E., additional, Gherman, Robert, additional, Gilbert, William M., additional, Goetzl, Laura, additional, Gonik, Bernard, additional, Greenberg, Mara B., additional, Gregory, Kimberly D., additional, Grobman, William A., additional, Hark, Lisa, additional, Hawkins, Joy L., additional, Holzgreve, Wolfgang, additional, Iams, Jay D., additional, Isley, Michelle M., additional, Jauniaux, Eric R.M., additional, Katz, Vern L., additional, Kilpatrick, Sarah, additional, Kroumpouzos, George, additional, Landers, Daniel V., additional, Landon, Mark B., additional, Lanni, Susan M., additional, Lewis, Gwyneth, additional, Lockwood, Charles J., additional, Ludmir, Jack, additional, Mackeen, A. Dhanya, additional, Macones, George A., additional, Mercer, Brian M., additional, Mestman, Jorge H., additional, Miller, David Arthur, additional, Miller, Emily S., additional, Misra, Dawn, additional, Moise, Kenneth J., additional, Molitch, Mark E., additional, Morroni, Chelsea, additional, Newman, Roger B., additional, Newton, Edward R., additional, Niebyl, Jennifer R., additional, Nielsen, COL Peter E., additional, Nyholm, Jessica L., additional, Otaño, Lucas, additional, Owen, John, additional, Pearlstein, Teri B., additional, Pettker, Christian M., additional, Racusin, Diana A., additional, Ramin, Kirk D., additional, Ramos, Diana E., additional, Rampersad, Roxane, additional, Regan, Leslie, additional, Richards, Douglas S., additional, Romero, Roberto, additional, Rosenberg, Adam A., additional, Ross, Michael G., additional, Rozance, Paul J., additional, Salani, Ritu, additional, Samuels, Philip, additional, Schwartz, Nadav, additional, Sheibani, Lili, additional, Sibai, Baha M., additional, Sibley, Colin P., additional, Simhan, Hyagriv N., additional, Simpson, Joe Leigh, additional, Sit, Dorothy K.Y., additional, Stout, Karen, additional, Svikis, Dace S., additional, Unal, Elizabeth Ramsey, additional, Wang, Annie R., additional, Weber, Robert J., additional, West, Elizabeth Horvitz, additional, Whitty, Janice E., additional, Wing, Deborah A., additional, Wisner, Katherine L., additional, and Wright, Jason D., additional

Published
2017
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4. Contributors

Author

Adamczak, Joanna, primary, Waldorf, Kristina M. Adams, additional, Altemus, Margaret, additional, Annas, George J., additional, Bailit, Jennifer L., additional, Baschat, Ahmet Alexander, additional, Berghella, Vincenzo, additional, Bernstein, Helene B., additional, Bogen, Debra L., additional, Branch, D. Ware, additional, Bucklin, Brenda A., additional, Burton, Graham J., additional, Cappell, Mitchell S., additional, Catalano, Patrick M., additional, Chin, Jeanette R., additional, Colombo, David F., additional, Copeland, Larry J., additional, Desai, Mina, additional, Dombrowski, Mitchell P., additional, Driscoll, Deborah A., additional, Druzin, Maurice L., additional, Duff, Patrick, additional, Easterling, Thomas R., additional, Eisenhauer, Eric L., additional, Elias, Sherman, additional, Ervin, M. Gore, additional, Famy, Christopher S., additional, Farinelli, Christine K., additional, Foley, Michael R., additional, Francois, Karrie E., additional, Gabbe, Steven G., additional, Galan, Henry L., additional, Gammill, Hilary S., additional, Garite, Thomas J., additional, Garrison, Etoi, additional, Gilbert, William M., additional, Goetzl, Laura, additional, Gordon, Michael C., additional, Greenberg, Mara B., additional, Gregory, Kimberly D., additional, Grobman, William A., additional, Hark, Lisa, additional, Hawkins, Joy L., additional, Holzgreve, Wolfgang, additional, Iams, Jay D., additional, Jauniaux, Eric R.M., additional, Johnson, Timothy R.B., additional, Katz, Vern L., additional, Kilpatrick, Sarah, additional, Kroumpouzos, George, additional, Landers, Daniel V., additional, Landon, Mark B., additional, Lanni, Susan M., additional, Lockwood, Charles J., additional, Ludmir, Jack, additional, Macones, George A., additional, Mercer, Brian M., additional, Mestman, Jorge H., additional, Misra, Dawn P., additional, Moise, Kenneth J., additional, Molitch, Mark E., additional, Mozurkewich, Ellen L., additional, Newman, Roger, additional, Newton, Edward R., additional, Niebyl, Jennifer R., additional, Nielsen, Peter E., additional, Novak, Donald, additional, Otaño, Lucas, additional, Owen, John, additional, Pearlman, Mark D., additional, Pearlstein, Teri B., additional, Perel, James M., additional, Pettker, Christian M., additional, Ramin, Kirk D., additional, Rampersad, Roxane, additional, Reynolds, Sarah K., additional, Richards, Douglas S., additional, Romero, Roberto, additional, Rosenberg, Adam A., additional, Ross, Michael G., additional, Rozance, Paul J., additional, Salani, Ritu, additional, Samuels, Philip, additional, Schwartz, Nadav, additional, Seeds, John W., additional, Shields, Laurence E., additional, Sibai, Baha M., additional, Sibley, Colin P., additional, Simhan, Hyagriv N., additional, Simpson, Joe Leigh, additional, Sit, Dorothy K.Y., additional, Stout, Karen, additional, Unal, E. Ramsey, additional, Whitty, Janice E., additional, Wing, Deborah A., additional, and Wisner, Katherine L., additional

Published
2012
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7. Contributors

Author

Adams, Kristina M., primary, Altemus, Margaret, additional, Annas, George J., additional, Baschat, Ahmet Alexander, additional, Battista, Leah R., additional, Berkowitz, Richard L., additional, Bernstein, Helene, additional, Bogen, Debra L., additional, Branch, D. Ware, additional, Burton, Graham J., additional, Cappell, Mitchell S., additional, Catalano, Patrick M., additional, Chestnut, David H., additional, Chitkara, Usha, additional, Cleary-Goldman, Jane, additional, Colombo, David F., additional, Copeland, Larry J., additional, Curet, Myriam J., additional, Deprest, Jan, additional, Divon, Michael Y., additional, Dombrowski, Mitchell P., additional, Druzin, Maurice L., additional, Duff, Patrick, additional, Easterling, Thomas R., additional, Elias, Sherman, additional, Ervin, M. Gore, additional, Evans, Mark I., additional, Flake, Alan W., additional, Foley, Michael R., additional, Francois, Karrie E., additional, Gabbe, Steven G., additional, Galan, Henry, additional, Garite, Thomas J., additional, Garrison, Etoi, additional, Gilbert, William M., additional, Goetzl, Laura, additional, Gordon, Michael C., additional, Gregory, Kimberly D., additional, Harrison, Michael R., additional, Hawkins, Joy L., additional, Holmgren, Calla, additional, Holzgreve, Wolfgang, additional, Iams, Jay D., additional, Jauniaux, Eric R.M., additional, Johnson, Timothy R.B., additional, Katz, Vern L., additional, Kilpatrick, Sarah, additional, Kleinman, Charles, additional, Kroumpouzos, George, additional, Landers, Daniel V., additional, Landon, Mark B., additional, Lanni, Susan M., additional, Lockwood, Charles J., additional, Lu, Erika J., additional, Ludmir, Jack, additional, Malee, Maureen P., additional, Mercer, Brian M., additional, Mestman, Jorge H., additional, Misra, Dawn, additional, Moise, Kenneth J., additional, Newton, Edward R., additional, Niebyl, Jennifer R., additional, Nielsen, Peter E., additional, Novak, Donald, additional, OtaÑo, Lucas, additional, Owen, John, additional, Papoutsis, John, additional, Perel, James M., additional, Pettker, Christian M., additional, Ramin, Kirk D., additional, Reed, Kathryn L., additional, Reynolds, Sarah K., additional, Richards, Douglas S., additional, Romero, Roberto, additional, Rosenberg, Adam A., additional, Ross, Michael G., additional, Samuels, Philip, additional, Seeds, John W., additional, Shields, Laurence E., additional, Sibai, Baha M., additional, Sibley, Colin P., additional, Simpson, Joe Leigh, additional, Sit, Dorothy K.Y., additional, Smith, James F., additional, Stout, Karen, additional, Sunder, Keerthy R., additional, Whitty, Janice E., additional, Wing, Deborah A., additional, Wisner, Katherine L., additional, and Yaron, Yuval, additional

Published
2007
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9. Ordinal pattern based similarity analysis for EEG recordings.

Author

Ouyang G, Dang C, Richards DA, and Li X

Subjects
Animals, Computer Simulation, Entropy, Epilepsy, Absence diagnosis, Epilepsy, Absence genetics, Models, Neurological, Nonlinear Dynamics, Rats, Rats, Mutant Strains, Brain physiopathology, Electroencephalography methods, Epilepsy, Absence physiopathology, Signal Processing, Computer-Assisted
Abstract

Objective: Ordinal patterns analysis such as permutation entropy of the EEG series has been found to usefully track brain dynamics and has been applied to detect changes in the dynamics of EEG data. In order to further investigate hidden nonlinear dynamical characteristics in EEG data for differentiating brain states, this paper proposes a novel dissimilarity measure based on the ordinal pattern distributions of EEG series., Methods: Given a segment of EEG series, we first map this series into a phase space, then calculate the ordinal sequences and the distribution of these ordinal patterns. Finally, the dissimilarity between two EEG series can be qualified via a simple distance measure. A neural mass model was proposed to simulate EEG data and test the performance of the dissimilarity measure based on the ordinal patterns distribution. Furthermore, this measure was then applied to analyze EEG data from 24 Genetic Absence Epilepsy Rats from Strasbourg (GAERS), with the aim of distinguishing between interictal, preictal and ictal states., Results: The dissimilarity measure of a pair of EEG signals within the same group and across different groups was calculated, respectively. As expected, the dissimilarity measures during different brain states were higher than internal dissimilarity measures. When applied to the preictal detection of absence seizures, the proposed dissimilarity measure successfully detected the preictal state prior to their onset in 109 out of 168 seizures (64.9%)., Conclusions: Our results showed that dissimilarity measures between EEG segments during the same brain state were significant smaller that those during different states. This suggested that the dissimilarity measure, based on the ordinal patterns in the time series, could be used to detect changes in the dynamics of EEG data. Moreover, our results suggested that ordinal patterns in the EEG might be a potential characteristic of brain dynamics., Significance: This dissimilarity measure is a promising method to reveal dynamic changes in EEG, for example as occur in the transition of epileptic seizures. This method is simple and fast, so might be applied in designing an automated closed-loop seizure prevention system for absence epilepsy., (Copyright 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

Published
2010
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10. Using recurrence plot for determinism analysis of EEG recordings in genetic absence epilepsy rats.

Author

Ouyang G, Li X, Dang C, and Richards DA

Subjects
Analysis of Variance, Animals, Disease Models, Animal, Male, Nonlinear Dynamics, Rats, Rats, Mutant Strains, Recurrence, Stochastic Processes, Time Factors, Electroencephalography, Epilepsy, Absence genetics, Epilepsy, Absence physiopathology, Signal Processing, Computer-Assisted
Abstract

Objective: Understanding the transition of brain activity towards an absence seizure is a challenging task. In this paper, we use recurrence quantification analysis to indicate the deterministic dynamics of EEG series at the seizure-free, pre-seizure and seizure states in genetic absence epilepsy rats., Methods: The determinism measure, DET, based on recurrence plot, was applied to analyse these three EEG datasets, each dataset containing 300 single-channel EEG epochs of 5-s duration. Then, statistical analysis of the DET values in each dataset was carried out to determine whether their distributions over the three groups were significantly different. Furthermore, a surrogate technique was applied to calculate the significance level of determinism measures in EEG recordings., Results: The mean (+/-SD) DET of EEG was 0.177+/-0.045 in pre-seizure intervals. The DET values of pre-seizure EEG data are significantly higher than those of seizure-free intervals, 0.123+/-0.023, (P<0.01), but lower than those of seizure intervals, 0.392+/-0.110, (P<0.01). Using surrogate data methods, the significance of determinism in EEG epochs was present in 25 of 300 (8.3%), 181 of 300 (60.3%) and 289 of 300 (96.3%) in seizure-free, pre-seizure and seizure intervals, respectively., Conclusions: Results provide some first indications that EEG epochs during pre-seizure intervals exhibit a higher degree of determinism than seizure-free EEG epochs, but lower than those in seizure EEG epochs in absence epilepsy., Significance: The proposed methods have the potential of detecting the transition between normal brain activity and the absence seizure state, thus opening up the possibility of intervention, whether electrical or pharmacological, to prevent the oncoming seizure.

Published
2008
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11. Electrochemical detection of free 3-nitrotyrosine: application to microdialysis studies.

Author

Richards DA, Silva MA, and Devall AJ

Subjects
Animals, Chromatography, High Pressure Liquid, Microdialysis, Oxidation-Reduction, Rats, Reproducibility of Results, Tyrosine analysis, Electrochemistry methods, Tyrosine analogs & derivatives
Abstract

3-Nitrotyrosine (3-NT) is formed by the reaction of peroxynitrite with either free or protein-bound tyrosine residues and has been proposed as a biomarker of oxidative stress caused by reactive nitrogen species. This study describes the development of an HPLC electrochemical detection assay for free 3-NT capable of measuring this metabolite at the very low (nanomolar) levels encountered physiologically. We employed a dual-cell coulometric approach in which 3-NT is first reduced at an upstream cell to 3-aminotyrosine, which itself is then oxidized at the downstream cell. The method was shown to be linear over the range of 1-500 nM (r = 0.999), with a detection limit (signal/noise ratio of 3) of 0.5 nM (25 fmol on column). Ten consecutive injections of 2 and 20 nM 3-NT standards produced coefficients of variation of 5.88 and 1.87%, respectively. Validation of the identity of the 3-NT peak was confirmed by coelution with authentic standards and by the in vitro production of 3-NT by incubation of 3-morpholinylsydnoneimine (SIN-1, 100 microM), a molecule releasing nitric oxide and superoxide in solution at a pH of 7.0 or higher with tyrosine (10 microM). Using this method, 3-NT was detected in human liver microdialysate (levels up to 2.6 nM), although levels in rat spinal cord dialysate were below the limit of detection.

Published
2006
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12. Extracellular glutamine to glutamate ratio may predict outcome in the injured brain: a clinical microdialysis study in children.

Author

Richards DA, Tolias CM, Sgouros S, and Bowery NG

Subjects
Adolescent, Amino Acids metabolism, Child, Female, Humans, Intracranial Pressure physiology, Male, Microdialysis methods, Pilot Projects, Prognosis, Brain Injuries metabolism, Extracellular Fluid metabolism, Glutamic Acid metabolism, Glutamine metabolism
Abstract

The amino acid content of hourly microdialysis samples from nine severely head-injured children was examined. Of particular interest was the measurement of the excitatory amino acid glutamate, as high levels of this substance, which are associated with the excitotoxicity cascade, have been linked to high intracranial pressure and poor outcome in a similar study in adults. Interpretation of these data is complicated by many clinical and methodological factors and these are discussed in relation to the findings. Our findings from this pilot study in children confirm the associations between glutamate levels, intracranial pressure and outcome, but fail to corroborate the correlation between excitatory and structural amino acid levels seen in adult patients, that was interpreted as evidence of non-specific leakage of amino acids through damaged cell membranes. In addition, we have shown that the role of glutamine in glutamate homeostasis is an important consideration and that estimation of the extracellular glutamine/glutamate ratio may have some prognostic value in head trauma cases as there is evidence of links to clinical outcome.

Published
2003

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