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Fortney JC, Rajan S, Reisinger HS, Moeckli J, Nolan JP, Wong ES, Rise P, Petrova VV, Sayre GG, Pyne JM, Grubaugh A, Simsek-Duran F, Grubbs KM, Morland LA, Felker B, Schnurr PP. Deploying a telemedicine collaborative care intervention for posttraumatic stress disorder in the U.S. Department of Veterans Affairs: A stepped wedge evaluation of an adaptive implementation strategy. Gen Hosp Psychiatry 2022; 77:109-117. [PMID: 35596963 DOI: 10.1016/j.genhosppsych.2022.03.009] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 03/08/2022] [Accepted: 03/23/2022] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To address barriers to trauma-focused psychotherapy for veterans with posttraumatic stress disorder (PTSD), we compared two implementation strategies to promote the deployment of telemedicine collaborative care. METHOD We conducted a Hybrid Type III Effectiveness Implementation trial at six VA medical centers and their 12 affiliated Community Based Outpatient Clinics. The trial used a stepped wedge design and an adaptive implementation strategy that started with standard implementation, followed by enhanced implementation for VA medical centers that did not achieve the performance benchmark. Implementation outcomes for the 544 veterans sampled from the larger population targeted by the intervention were assessed from chart review (care management enrollment and receipt of trauma-focused psychotherapy) and telephone survey (perceived access and PTSD symptoms) after each implementation phase. The primary outcome was enrollment in care management. RESULTS There was no significant difference between standard implementation and enhanced implementation on any of the implementation outcomes. 41.6% of sampled veterans had a care manager encounter, but only 6.0% engaged in trauma-focused psychotherapy. CONCLUSIONS While telemedicine collaborative care was shown to be effective at engaging veterans in trauma-focused psychotherapy in a randomized controlled trial, neither standard nor enhanced implementation strategies were sufficient to support successful deployment into routine care. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02737098.
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Affiliation(s)
- John C Fortney
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States of America.
| | - Suparna Rajan
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America
| | - Heather S Reisinger
- VA HSR&D Center for Access & Delivery Research and Evaluation, Iowa City VA Health Care System, IA, United States of America; Department of Internal Medicine, University of Iowa, Iowa City, IA, United States of America
| | - Jane Moeckli
- VA HSR&D Center for Access & Delivery Research and Evaluation, Iowa City VA Health Care System, IA, United States of America
| | | | - Edwin S Wong
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America; Department of Health and Systems and Population Health, University of Washington, Seattle, WA, United States of America
| | - Peter Rise
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America
| | - Valentina V Petrova
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America
| | - George G Sayre
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America
| | - Jeffrey M Pyne
- VA HSR&D Center for Mental Health and Outcomes Research, Central Arkansas Veterans Healthcare System, Little Rock, AR, United States of America; Department of Psychiatry, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Anouk Grubaugh
- VA HSR&D Charleston Health Equity and Rural Outreach Innovation Center, Charleston, SC, United States of America; Department of Psychiatry, Medical University of South Carolina, Charleston, SC, United States of America
| | - Fatma Simsek-Duran
- Iowa City VA Health Care System, IA, United States of America; Department of Psychiatry, University of Iowa, Iowa City, IA, United States of America
| | - Kathleen M Grubbs
- VA San Diego Healthcare System, San Diego, CA, United States of America; Department of Psychiatry, University of California-San Diego, San Diego, CA, United States of America
| | - Leslie A Morland
- VA San Diego Healthcare System, San Diego, CA, United States of America; Department of Psychiatry, University of California-San Diego, San Diego, CA, United States of America
| | - Bradford Felker
- VA HSR&D Center for Innovation for Veteran-Centered and Value-Driven Care, VA Puget Sound Health Care System, Seattle, WA, United States of America; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States of America
| | - Paula P Schnurr
- National Center for PTSD, VA Medical Center, White River Junction, VT, United States of America; Geisel School of Medicine at Dartmouth, Hanover, NH, United States of America
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Wong ES, Rajan S, Liu CF, Morland LA, Pyne JM, Simsek-Duran F, Reisinger HS, Moeckli J, Fortney JC. Economic costs of implementing evidence-based telemedicine outreach for posttraumatic stress disorder in VA. Implementation Research and Practice 2022; 3:26334895221116771. [PMID: 37091111 PMCID: PMC9924252 DOI: 10.1177/26334895221116771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background Telemedicine outreach for posttraumatic stress disorder (TOP) is a virtual evidence-based practice (EBP) involving telephone care management and telepsychology that engages rural patients in trauma-focused psychotherapy. This evaluation examined implementation and intervention costs attributable to deploying TOP from a health system perspective. Methods Costs were ascertained as part of a stepped wedge cluster randomized trial at five sites within the Veterans Affairs (VA) Healthcare System. All sites initially received a standard implementation strategy, which included internal facilitation, dissemination of an internal facilitators operational guide, funded care manager, care managing training, and technical support. A subset of clinics that failed to meet performance metrics were subsequently randomized to enhanced implementation, which added external facilitation that focused on incorporating TOP clinical processes into existing clinic workflow. We measured site-level implementation activities using project records and structured activity logs tracking personnel-level time devoted to all implementation activities. We monetized time devoted to implementation activities by applying an opportunity cost approach. Intervention costs were measured as accounting-based costs for telepsychiatry/telepsychology and care manager visits, ascertained using VA administrative data. We conducted descriptive analyses of strategy-specific implementation costs across five sites. Descriptive analyses were conducted instead of population-level cost-effectiveness analysis because previous research found enhanced implementation was not more successful than the standard implementation in improving uptake of TOP. Results Over the 40-month study period, four of five sites received enhanced implementation. Mean site-level implementation cost per month was $919 (SD = $238) during standard implementation and increased to $1,651 (SD = $460) during enhanced implementation. Mean site-level intervention cost per patient-month was $46 (SD = $28) during standard implementation and $31 (SD = $21) during enhanced implementation. Conclusions Project findings inform the expected cost of implementing TOP, which represents one factor health systems should consider in the decision to broadly adopt this EBP. Plain Language Summary: What is already known about the topic: Trauma-focused psychotherapy delivered through telemedicine has been demonstrated as an effective approach for the treatment of post-traumatic stress disorder (PTSD). However, uptake of this evidence-based approach by integrated health systems such as the Veterans Affairs (VA) Health Care System is low. What does this paper add: This paper presents new findings on the costs of two implementation approaches designed to increase adoption telemedicine outreach for PTSD from a health system perspective. What are the implications for practice, research, and policy: Cost estimates from this paper can be used by health systems to inform the relative value of candidate implementation strategies to increase adoption of evidence-based treatments for PTSD or other mental health conditions.
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Affiliation(s)
- Edwin S. Wong
- Center for Innovation for Veteran-Centered and Value-Driven Care, Puget Sound Health Care System, Seattle, WA
- Department of Health Systems and Population Health, University of Washington, Seattle, WA
| | - Suparna Rajan
- Center for Innovation for Veteran-Centered and Value-Driven Care, Puget Sound Health Care System, Seattle, WA
| | - Chuan-Fen Liu
- Center for Innovation for Veteran-Centered and Value-Driven Care, Puget Sound Health Care System, Seattle, WA
- Department of Health Systems and Population Health, University of Washington, Seattle, WA
| | - Leslie A. Morland
- VA San Diego Healthcare System, San Diego, CA
- Department of Psychiatry, University of California-San Diego, San Diego, CA
| | - Jeffrey M. Pyne
- Center for Mental Health and Outcomes Research, Central Arkansas Veterans Healthcare System, Little Rock, AR
- Department of Psychiatry, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Fatma Simsek-Duran
- Iowa City VA Health Care System, Iowa City, IA
- Department of Psychiatry, University of Iowa, Iowa City, IA
| | - Heather S. Reisinger
- Center for Access & Delivery Research and Evaluation, Iowa City VA Health Care System, Iowa City, IA
- Department of Internal Medicine, University of Iowa, Iowa
City, IA
| | - Jane Moeckli
- Center for Access & Delivery Research and Evaluation, Iowa City VA Health Care System, Iowa City, IA
| | - John C. Fortney
- Center for Innovation for Veteran-Centered and Value-Driven Care, Puget Sound Health Care System, Seattle, WA
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA
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Castora FJ, Conyers BL, Gershon BS, Kerns KA, Campbell R, Simsek-Duran F. The T9861C Mutation in the mtDNA-Encoded Cytochrome C Oxidase Subunit III Gene Occurs in High Frequency but with Unequal Distribution in the Alzheimer's Disease Brain. J Alzheimers Dis 2020; 72:257-269. [PMID: 31561357 DOI: 10.3233/jad-190176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mitochondrial dysfunction is recognized as a critical component in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). Deficits in oxidative capacity and, specifically, cytochrome c oxidase (CO) activity have been reported in AD brains and platelets. We previously identified a point mutation at np 9861 in AD brain mitochondrial DNA (mtDNA) that alters amino acid 219 of subunit III of CO from phenylalanine to leucine. We rapidly screened and quantitated levels of T9861C in samples using mismatched PCR-RFLP and nucleotide extension assays. Six of 40 AD brains possessed the T9861C mutation (designated AD+) compared to zero of 40 age-matched control brains. The 15% frequency of T9861C in AD brain is 115-fold higher than the frequency (0.13%) reported in 9,986 human mtDNA samples queried in world-wide databases. T9861C is heteroplasmic, with mutant load varying from 11% to >95%. Detected initially in parietal cortex, T9861C is not localized to that region but is also found in temporal cortex and caudate but not in hippocampus. The mutant load is unequally distributed throughout these brain regions with the highest load occurring in the parietal or temporal cortex. CO activity normalized to citrate synthase (CS) is reduced an average of 48.5% in AD+ brains. CO/CS ratios amongst controls and the two AD populations (AD and AD+) were significantly different (p = 0.001). Post hoc differences were also significant between controls and AD+ (p = 0.001) and controls and AD (p = 0.019). There was no significant difference between AD and AD+ (p = 0.317).
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Affiliation(s)
- Frank J Castora
- Department of Physiological Sciences, Division of Biochemistry, Eastern Virginia Medical School, Norfolk, VA, USA.,Department of Neurology, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Barbara L Conyers
- Department of Physiological Sciences, Division of Biochemistry, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Blake S Gershon
- Department of Physiological Sciences, Division of Biochemistry, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Kimberly A Kerns
- Department of Physiological Sciences, Division of Biochemistry, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Robert Campbell
- School of Health Professions, MPH Program, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Fatma Simsek-Duran
- Department of Physiological Sciences, Division of Biochemistry, Eastern Virginia Medical School, Norfolk, VA, USA
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Black DW, Simsek-Duran F, Blum N, McCormick B, Allen J. Do people with borderline personality disorder complicated by antisocial personality disorder benefit from the STEPPS treatment program? Personal Ment Health 2016; 10:205-15. [PMID: 26671625 PMCID: PMC4911327 DOI: 10.1002/pmh.1326] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/11/2015] [Accepted: 11/12/2015] [Indexed: 11/10/2022]
Abstract
Systems Training for Emotional Predictability and Problem Solving (STEPPS) is a group treatment for persons with borderline personality disorder (BPD). We describe results from two data sets on outcome in persons who participated in STEPPS with BPD alone or BPD plus antisocial personality disorder (ASPD). In Study 1, we examined the effect of comorbid ASPD on outcome in 65 persons with BPD who participated in a randomized controlled trial at an academic medical centre. In Study 2, we examined the effect of comorbid ASPD on outcome in 64 offenders with BPD who participated in STEPPS in correctional settings. All subjects were assessed for the presence of BPD and ASPD. In Study 1, subjects with ASPD experienced greater improvement in BPD symptoms, impulsiveness and global symptoms. In Study 2, offenders with ASPD experienced greater improvement in positive and negative behaviours and positive affectivity. We conclude that persons with BPD plus ASPD benefit from STEPPS in community and correctional settings. The findings suggest that persons with BPD plus ASPD show greater improvement in some domains than persons with BPD only. People with ASPD should not be automatically excluded from participation in the program. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Donald W Black
- Department of Psychiatry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Fatma Simsek-Duran
- Department of Psychiatry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Nancee Blum
- Department of Psychiatry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Brett McCormick
- Department of Psychiatry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Jeff Allen
- Department of Psychiatry, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, 52242, USA
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Simsek-Duran F, Li F, Ford W, Swanson RJ, Jones HW, Castora FJ. Age-associated metabolic and morphologic changes in mitochondria of individual mouse and hamster oocytes. PLoS One 2013; 8:e64955. [PMID: 23741435 PMCID: PMC3669215 DOI: 10.1371/journal.pone.0064955] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 04/23/2013] [Indexed: 11/26/2022] Open
Abstract
Background In human oocytes, as in other mammalian ova, there is a significant variation in the pregnancy potential, with approximately 20% of oocyte-sperm meetings resulting in pregnancies. This frequency of successful fertilization decreases as the oocytes age. This low proportion of fruitful couplings appears to be influenced by changes in mitochondrial structure and function. In this study, we have examined mitochondrial biogenesis in both hamster (Mesocricetus auratus) and mouse (Mus musculus) ova as models for understanding the effects of aging on mitochondrial structure and energy production within the mammalian oocyte. Methodology/Principal Findings Individual metaphase II oocytes from a total of 25 young and old mice and hamsters were collected from ovarian follicles after hormone stimulation and prepared for biochemical or structural analysis. Adenosine triphosphate levels and mitochondrial DNA number were determined within individual oocytes from young and old animals. In aged hamsters, oocyte adenosine triphosphate levels and mitochondrial DNA molecules were reduced 35.4% and 51.8%, respectively. Reductions of 38.4% and 44% in adenosine triphosphate and mitochondrial genomes, respectively, were also seen in aged mouse oocytes. Transmission electron microscopic (TEM) analysis showed that aged rodent oocytes had significant alterations in mitochondrial and cytoplasmic lamellae structure. Conclusions/Significance In both mice and hamsters, decreased adenosine triphosphate in aged oocytes is correlated with a similar decrease in mtDNA molecules and number of mitochondria. Mitochondria in mice and hamsters undergo significant morphological change with aging including mitochondrial vacuolization, cristae alterations, and changes in cytoplasmic lamellae.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia, United States of America
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Duran HE, Simsek-Duran F, Oehninger SC, Jones HW, Castora FJ. The association of reproductive senescence with mitochondrial quantity, function, and DNA integrity in human oocytes at different stages of maturation. Fertil Steril 2011; 96:384-8. [PMID: 21683351 DOI: 10.1016/j.fertnstert.2011.05.056] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 05/11/2011] [Accepted: 05/17/2011] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To determine the impact of reproductive aging on oocyte mitochondrial quantity, function, and DNA (mtDNA) integrity. DESIGN Prospective observational study. SETTING IVF clinic in a tertiary academic care center. PATIENT(S) One hundred two oocytes from 32 women undergoing IVF. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Adenosine triphosphate (ATP) levels, mtDNA number, and mtDNA deletion occurrence in individual oocytes. RESULT(S) Oocyte ATP content increases with maturation (786 ± 87 fmol, 1,037 ± 57 fmol, and 1,201 ± 59 fmol for prophase 1 [P1], metaphase 1 [M1], and metaphase 2 [M2] oocytes, respectively), whereas mtDNA copy numbers do not change (64,500 ± 20,440, 180,000 ± 44,040, and 143,000 ± 31,210 for P1, M1, and M2 oocytes, respectively). Stepwise multiple regression analysis identified developmental stage as a determinant of oocyte ATP, whereas number of oocytes retrieved and cycle day 3 FSH level were determinants of mtDNA copy number. Of the 15 oocytes found to possess the 5-kb mtDNA deletion, 10 were arrested or degenerated oocytes. CONCLUSION(S) Although no direct association was found between female age and oocyte mitochondrial quantity and function, the number of mitochondria was predicted by ovarian reserve indicators. As the oocyte matures, ATP content increases.
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Affiliation(s)
- Hakan E Duran
- Department of Obstetrics and Gynecology, Jones Institute for Reproductive Medicine, Norfolk, Virginia, USA
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Simsek-Duran F, Ertunc M, Onur R. The effects of pentoxifylline on skeletal muscle contractility and neuromuscular transmission during hypoxia. Indian J Pharmacol 2010; 41:213-7. [PMID: 20177491 PMCID: PMC2812779 DOI: 10.4103/0253-7613.58509] [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] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 12/20/2008] [Accepted: 10/22/2009] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVES The objective of this study was to investigate the effects of pentoxifylline (PTX), a drug that is mainly used for indications related to tissue hypoxia, on hypoxia-induced inhibition of skeletal muscle contractility and neuromuscular transmission in mice. We hypothesized that chronic PTX treatment alters skeletal muscle contractility and hypoxia-induced dysfunction. MATERIALS AND METHODS Mice were treated with 50 mg/kg PTX or saline intraperitoneally for a week. Following ether anesthesia, diaphragm muscles were removed; isometric muscle contractions and action potentials were recorded. Time to reach neuromuscular blockade and the rate of recovery of muscle contractility were assessed during hypoxia and re-oxygenation. RESULTS The PTX group displayed 90% greater twitch amplitudes (P < 0.01). Hypoxia depressed twitch contractions and caused neuromuscular blockade in both groups. However, neuromuscular blockade occurred earlier in PTX-treated animals (P < 0.05). Muscle contractures developed during hypoxia were more pronounced in the PTX group (P < 0.05). Re-oxygenation reduced contracture and indirect muscle contractions resumed. The rate of recovery of contractions was faster (P < 0.05) and the amplitude of contractions was greater (P < 0.01) in the PTX group. PTX treatment increased amplitude (P < 0.05) and shortened action potential (P < 0.05) without altering resting membrane potential, excitation threshold, and neurotransmitter release. CONCLUSION Chronic PTX treatment increases diaphragm contractility, but amplifies hypoxia-induced contractile dysfunction in mice. These results may implicate important clinical consequences for clinical usage of PTX in hypoxia-related conditions.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Physiology, Faculty of Medicine, Hacettepe University, 06100 Sihhiye, Ankara, Turkey
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Duran H, Simsek-Duran F, Oehninger S, Swanson R, Jones H, Castora F. Mitochondrial function, quantity and DNA integrity in human oocytes at different stages of maturation. Fertil Steril 2009. [DOI: 10.1016/j.fertnstert.2009.07.1512] [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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Lonart G, Tang X, Simsek-Duran F, Machida M, Sanford L. Corrigendum to “the role of active zone protein Rab3 interacting molecule 1 alpha in the regulation of norepinephrine release, response to novelty, and sleep”. Neuroscience 2008. [DOI: 10.1016/j.neuroscience.2008.07.076] [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: 11/25/2022]
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10
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Coleman WL, Bill CA, Simsek-Duran F, Lonart G, Samigullin D, Bykhovskaia M. Synapsin II and calcium regulate vesicle docking and the cross-talk between vesicle pools at the mouse motor terminals. J Physiol 2008; 586:4649-73. [PMID: 18669537 DOI: 10.1113/jphysiol.2008.154666] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The synapsins, an abundant and highly conserved family of proteins that associate with synaptic vesicles, have been implicated in regulating the synaptic vesicle cycle. However, it has not been determined whether synapsin directly regulates the number of docked vesicles. Here we document that reducing Ca(2+) concentration [Ca(2+)](o) in the extracellular medium from 2 to 0.5 mm led to an approximately 40% decrease in both docked and undocked synaptic vesicles in wild-type nerve terminals of the mouse diaphragm. The same treatment reduced the number of undocked vesicles in nerve terminals derived from synapsin II gene deleted animals, but surprisingly it did not decrease vesicle docking, indicating that synapsin II inhibits docking of synaptic vesicles at reduced [Ca(2+)](o). In accordance with the morphological findings, at reduced [Ca(2+)](o) synapsin II (-) terminals had a higher rate of quantal neurotransmitter release. Microinjection of a recombinant synapsin II protein into synapsin II (-) terminals reduced vesicular docking and inhibited quantal release, indicating a direct and selective synapsin II effect for regulating vesicle docking and, in turn, quantal release. To understand why [Ca(2+)](o) has a prominent effect on synapsin function, we investigated the effect of [Ca(2+)](o) on the distribution of synaptic vesicles and on the concentration of intraterminal Ca(2+). We found that reduced [Ca(2+)](o) conditions produce a decrease in intracellular Ca(2+) and overall vesicle depletion. To explore why at these conditions the role of synapsin II in vesicle docking becomes more prominent, we developed a quantitative model of the vesicle cycle, with a two step synapsin action in stabilizing the vesicle store and regulating vesicle docking. The results of the modelling were in a good agreement with the observed dependence of vesicle distribution on synapsin II and calcium deficiency.
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Affiliation(s)
- William L Coleman
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA.
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Simsek-Duran F, Lonart G. The role of RIM1alpha in BDNF-enhanced glutamate release. Neuropharmacology 2008; 55:27-34. [PMID: 18499195 DOI: 10.1016/j.neuropharm.2008.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 03/14/2008] [Accepted: 04/11/2008] [Indexed: 11/30/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is known to activate proline-directed Ser/Thr protein kinases and to enhance glutamatergic transmission via a Rab3a-dependent molecular pathway. The identity of molecular targets in BDNF's action on Rab3a pathway, a synaptic vesicle protein involved in vesicle trafficking and synaptic plasticity, is not fully known. Here we demonstrate that BDNF enhances depolarization-evoked efflux of [(3)H]-glutamate from nerve terminals isolated from the CA1 region of the hippocampus. BDNF also potentiated hyperosmotic shock-evoked [(3)H]-glutamate efflux, indicating an effect on the size of the readily releasable pool. This effect of BDNF was completely abolished in nerve terminals derived from Rim1alphaKO (Rab3 interacting molecule 1alpha null mutant) mice. Using in vitro phosphorylation assays we identified two novel phosphorylation sites, Ser447 and Ser745 that were substrates for ERK2, a proline-directed kinase known to be activated by BDNF. The pSer447 site was phosphorylated under resting conditions in hippocampal CA1 nerve terminals and its phosphorylation was enhanced by BDNF treatment, as indicated by the use of a pSer447-RIM1alpha antibody we have developed. Together these findings identify RIM1alpha, a component of the Rab3a molecular pathway in mediating presynaptic plasticity, as a necessary factor in BDNF's enhancement of [(3)H]-glutamate efflux from hippocampal CA1 nerve terminals and indicate a possible role for RIM1alpha phosphorylation in BDNF-dependent presynaptic plasticity.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Pathology and Anatomy, Eastern Virginia Medical School, 700 W. Olney Road Norfolk, VA 23507, USA
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Lonart G, Tang X, Simsek-Duran F, Machida M, Sanford LD. The role of active zone protein Rab3 interacting molecule 1 alpha in the regulation of norepinephrine release, response to novelty, and sleep. Neuroscience 2008; 154:821-31. [PMID: 18495360 DOI: 10.1016/j.neuroscience.2008.03.047] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [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] [Received: 02/20/2008] [Revised: 03/15/2008] [Accepted: 03/18/2008] [Indexed: 11/15/2022]
Abstract
Sleep mechanisms and synaptic plasticity are thought to interact to regulate homeostasis and memory formation. However, the influences of molecules that mediate synaptic plasticity on sleep are not well understood. In this study we demonstrate that mice lacking Rab3 interacting molecule 1 alpha (RIM1 alpha) (Rim1 alpha KO), a protein of the synaptic active zone required for certain types of synaptic plasticity and learning, had 53+/-5% less baseline rapid eye movement (REM) sleep compared with their wild type littermates. Also, compared with wild type littermates, exposure of the mice to an open field or to a novel object induced more robust and longer lasting locomotion suggesting altered habituation. This difference in exploratory behavior correlated with genotype specific changes in REM and deregulated release of norepinephrine in the cortex and basal amygdala of the Rim1 alpha KO mice. Also, moderate sleep deprivation (4 h), a test of the homeostatic sleep response, induced REM sleep rebound with different time course in Rim1 alpha KO and their wild type littermates. As norepinephrine plays an important role in regulating arousal and REM sleep, our data suggest that noradrenergic deficiency in Rim1 alpha KO animals impacts exploratory behavior and sleep regulation and contributes to impairments in learning.
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Affiliation(s)
- G Lonart
- Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
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Lonart G, Simsek-Duran F. Deletion of synapsins I and II genes alters the size of vesicular pools and rabphilin phosphorylation. Brain Res 2006; 1107:42-51. [PMID: 16844103 DOI: 10.1016/j.brainres.2006.05.092] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [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] [Received: 09/21/2005] [Revised: 05/04/2006] [Accepted: 05/28/2006] [Indexed: 01/21/2023]
Abstract
Previous studies established that genetic deletion of synapsins, synaptic vesicle-associated phosphoproteins that regulate neurotransmitter release, decreases the number of synaptic vesicles in nerve terminals. To investigate whether these changes affect the release properties of the remaining synaptic vesicles, we used a radioactive labeling technique to measure release independently of the total number of synaptic vesicles. 3H-glutamate and 14C-gamma-amino-butyric-acid (GABA) release from isolated nerve terminals prepared from the neocortex of synapsins I and II double knock-out mice (DKO) was assayed and compared to wild-type preparations. Hyperosmotic shock-evoked 3H-glutamate was reduced by 20+/-3% from DKO nerve terminals and potassium depolarization-evoked glutamate release was also decreased by 28+/-2%. Surprisingly, sucrose or potassium depolarization-evoked release of 14C-GABA was increased by 32+/-4% and 29+/-5%, respectively. The basal efflux of both 3H-glutamate and 14C-GABA increased by 17+/-2% and 12+/-2% from DKO nerve terminals. As lack of synapsins I and II, major phosphoproteins of synaptic vesicles, may lead to deregulation of phosphorylation events, we compared phosphorylation state of another synaptic vesicle protein, rabphilin. In DKO nerve terminals, membrane-associated rabphilin level was reduced by approximately 0.28-fold, its phosphorylation at 234serine was increased by approximately 1.61-fold whereas cytosolic rabphilin levels showed both more dramatic reduction in abundance, approximately 16.5-fold, and increase in phosphorylation, approximately 4.8-fold. Collectively, these data suggest that deletion of major synapsin isoforms leads to (1) deregulation of basal neurotransmission causing "leaky" basal release, (2) changes in either the size or mobilization of releasable or reserve pools, and (3) a decrease in rabphilin abundance accompanied by an increase in basal phosphorylation of the remaining rabphilin.
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Affiliation(s)
- György Lonart
- Department of Pathology and Anatomy, Eastern Virginia Medical School, 700 W. Olney Rd. Norfolk, VA 23507, USA.
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Simsek-Duran F, Linden DJ, Lonart G. Adapter protein 14-3-3 is required for a presynaptic form of LTP in the cerebellum. Nat Neurosci 2004; 7:1296-8. [PMID: 15543142 DOI: 10.1038/nn1348] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [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] [Received: 07/12/2004] [Accepted: 09/14/2004] [Indexed: 11/09/2022]
Abstract
Long-term potentiation (LTP) of granule cell-Purkinje cell synapses in the mouse cerebellum requires phosphorylation by protein kinase A of the active-zone protein RIM1alpha at Ser413. Here, we show that the adapter protein 14-3-3 readily binds phosphorylated Ser413 in RIM1alpha, and that presynaptic transfection with a dominant-negative 14-3-3eta mutant, or a RIM1alpha mutant with enhanced 14-3-3 binding, inhibits LTP. Thus, RIM1alpha phosphorylation triggers presynaptic LTP in part through recruitment of 14-3-3 to phospho-Ser413-RIM1alpha.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Pathology & Anatomy, Eastern Virginia Medical School, Norfolk, Virginia 23501, USA
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