52 results on '"Evans WR"'
Search Results
2. Regional Salt Balances and Implications for Dryland Salinity Management
- Author
-
International Association of Hydrogeologists. Congress (25th : 1994 : Adelaide, S. Aust.) and Evans, WR
- Published
- 1994
3. Darling Basin Hydrogeological Map Land and Water Management Issues
- Author
-
International Association of Hydrogeologists. Congress (25th : 1994 : Adelaide, S. Aust.), Williams, RM, Woolley, DR, Abell, RS, Please, P, and Evans, WR
- Published
- 1994
4. Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling.
- Author
-
Chang NP, DaPrano EM, Lindman M, Estevez I, Chou TW, Evans WR, Nissenbaum M, McCourt M, Alzate D, Atkins C, Kusnecov AW, Huda R, and Daniels BP
- Subjects
- Animals, Mice, Humans, Dopaminergic Neurons metabolism, Dopaminergic Neurons pathology, Male, Disease Models, Animal, Neuroinflammatory Diseases pathology, Neuroinflammatory Diseases metabolism, Cell Death, Neurons metabolism, Neurons pathology, Mice, Inbred C57BL, Parkinson Disease metabolism, Parkinson Disease pathology, Parkinson Disease genetics, Neurodegenerative Diseases metabolism, Neurodegenerative Diseases pathology, Astrocytes metabolism, Astrocytes pathology, Receptor-Interacting Protein Serine-Threonine Kinases metabolism, Receptor-Interacting Protein Serine-Threonine Kinases genetics, Signal Transduction
- Abstract
Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. Receptor interacting protein kinase-3 (RIPK3) signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of damage-associated molecular pattern signaling. In mechanistic experiments, we showed that factors released from dying neurons signaled through receptor for advanced glycation endproducts to induce astrocytic RIPK3 signaling, which conferred inflammatory and neurotoxic functional activity. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.
- Published
- 2024
- Full Text
- View/download PDF
5. Functional activation of dorsal striatum astrocytes improves movement deficits in hemi-parkinsonian mice.
- Author
-
Evans WR, Baskar SS, Costa ARCE, Ravoori S, Arigbe A, and Huda R
- Abstract
Parkinson's disease (PD) is characterized by the degeneration of dopaminergic nigrostriatal inputs, which causes striatal network dysfunction and leads to pronounced motor deficits. Recent evidence highlights astrocytes as a potential local source of striatal network modulation. However, it remains unknown how dopamine loss affects striatal astrocyte activity and whether astrocyte activity regulates behavioral deficits in PD. We addressed these questions by performing astrocyte-specific calcium recordings and manipulations using in vivo fiber photometry and chemogenetics. We find that locomotion elicits astrocyte calcium activity over a slower timescale than neurons. Unilateral dopamine depletion reduced locomotion-related astrocyte responses. Chemogenetic activation facilitated astrocyte activity, and improved asymmetrical motor deficits and open field exploratory behavior in dopamine lesioned mice. Together, our results establish a novel role for functional striatal astrocyte signaling in modulating motor function in PD and highlight non-neuronal targets for potential PD therapeutics., Competing Interests: Competing interests The authors report no competing interests.
- Published
- 2024
- Full Text
- View/download PDF
6. Enhancing resiliency and optimizing readiness in military personnel through psychological flexibility training: design and methodology of a randomized controlled trial.
- Author
-
Peterson AL, Moore BA, Evans WR, Young-McCaughan S, Blankenship AE, Straud CL, McLean CS, Miller TL, and Meyer EC
- Abstract
Background: Enhancing resiliency and optimizing readiness in military personnel is a high priority for the U.S. Department of Defense. Most military resiliency-enhancement programs are evidence-informed interventions. However, few randomized studies have demonstrated efficacy of any intervention or training program to enhance resiliency and prevent the development of psychological health symptoms in military personnel when exposed to operational stressors. This manuscript provides an overview of the theoretical foundation, research design, and research methods of a preventive intervention trial designed to evaluate the efficacy of a training program to enhance resiliency and prevent psychological health symptoms in military personnel. The resiliency training intervention is based on Acceptance and Commitment Therapy (ACT), an evidence-based intervention with broad empirical support for improving functioning in those living with psychological and medical conditions., Method/design: This study will evaluate the efficacy of a two-day training program based on ACT for fostering psychological flexibility, the central target in ACT, for enhancing resiliency, and for preventing the development of psychological health symptoms. The research participants will be a non-clinical population of active duty military personnel ( N = 600). The ACT-based training program ( n = 300) will be compared to a military resiliency training as usual, known as Master Resilience Training ( n = 300). Assessment measures will be administered at the baseline assessment, after training, prior to a military deployment, and after returning from a deployment. Qualitative interviews will be conducted to provide feedback on the training program. Clinical Trial Registration: NCT05094115., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Peterson, Moore, Evans, Young-McCaughan, Blankenship, Straud, McLean, Miller and Meyer.)
- Published
- 2024
- Full Text
- View/download PDF
7. Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling.
- Author
-
Chang NP, DaPrano EM, Evans WR, Nissenbaum M, McCourt M, Alzate D, Lindman M, Chou TW, Atkins C, Kusnecov AW, Huda R, and Daniels BP
- Abstract
Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. RIPK3 signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the MPTP model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of DAMP signaling. Using human cell culture systems, we show that factors released from dying neurons signal through RAGE to induce RIPK3-dependent astrocyte activation. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3., Competing Interests: Competing Interests The authors declare no competing interests.
- Published
- 2023
- Full Text
- View/download PDF
8. Coworker abuse in healthcare: voices of mistreated workers.
- Author
-
Evans WR, Mullen DM, and Burke-Smalley L
- Subjects
- Humans, Workplace, Hospitals, Health Personnel, Delivery of Health Care, Occupational Stress
- Abstract
Purpose: The appalling abuse healthcare workers have endured from patients is long documented in the popular press and social media. Less explored in the healthcare management literature is workplace abuse that professional nurses experience from their coworkers., Design/methodology/approach: The authors use text-based first-hand accounts from nurses posting on Reddit ( N = 75) to better understand the types and context of abusive acts endured by their coworkers in the contemporary healthcare setting. Each account is content analyzed using two raters, and thematic analysis is utilized to summarize findings., Findings: Findings indicate that nurse workplace abuse frequently targets new entrants to a work unit (e.g. recent grads), typically is ongoing, takes verbal and nonverbal forms, mainly stems from coworkers (i.e. lateral mistreatment), and frequently takes place in front of other coworkers, mainly in hospital settings., Practical Implications: By applying the lens of mindfulness, healthcare organizations can transform these harmful interactions within the nursing profession. The authors offer administrators and frontline workers practical implications for mitigating workplace abuse, including reshaping the culture, bystander interventions and explicit leadership support., Originality/value: First-hand accounts from nurses in the frontlines of healthcare provide a rich voice that reveals the reality of ongoing verbal and nonverbal peer abuse in hospitals and healthcare settings., (© Emerald Publishing Limited.)
- Published
- 2023
- Full Text
- View/download PDF
9. Massed vs Intensive Outpatient Prolonged Exposure for Combat-Related Posttraumatic Stress Disorder: A Randomized Clinical Trial.
- Author
-
Peterson AL, Blount TH, Foa EB, Brown LA, McLean CP, Mintz J, Schobitz RP, DeBeer BR, Mignogna J, Fina BA, Evans WR, Synett S, Hall-Clark BN, Rentz TO, Schrader C, Yarvis JS, Dondanville KA, Hansen H, Jacoby VM, Lara-Ruiz J, Straud CL, Hale WJ, Shah D, Koch LM, Gerwell KM, Young-McCaughan S, Litz BT, Meyer EC, Blankenship AE, Williamson DE, Roache JD, Javors MA, Sharrieff AM, Niles BL, and Keane TM
- Subjects
- Humans, Male, Adult, Female, Outpatients, Treatment Outcome, Stress Disorders, Post-Traumatic therapy, Military Personnel, Veterans
- Abstract
Importance: Improved, efficient, and acceptable treatments are needed for combat-related posttraumatic stress disorder (PTSD)., Objective: To determine the efficacy of 2 compressed prolonged exposure (PE) therapy outpatient treatments for combat-related PTSD., Design, Setting, and Participants: This randomized clinical trial was conducted among military personnel and veterans at 4 sites in Texas from 2017 to 2019. Assessors were blinded to conditions. Data were analyzed from November 2020 to October 2022., Interventions: The interventions were massed-PE, which included 15 therapy sessions of 90 minutes each over 3 weeks, vs intensive outpatient program PE (IOP-PE), which included 15 full-day therapy sessions over 3 weeks with 8 treatment augmentations. The IOP-PE intervention was hypothesized to be superior to massed-PE., Main Outcomes and Measures: Coprimary outcomes included the Clinician-Administered PTSD Scale for Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) (CAPS-5) and the PTSD Checklist for DSM-5 (PCL-5) administered at baseline and posttreatment follow-ups. Measures ranged from 0 to 80, with higher scores indicating greater severity. Diagnostic remission and reliable change were secondary outcomes., Results: Among 319 military personnel and veterans screened, 234 were randomized (mean [SD] age, 39.20 [7.72] years; 182 [78%] male participants), with 117 participants randomized to IOP-PE and 117 participants randomized to massed-PE. A total of 61 participants (26%) were African American, 58 participants (25%) were Hispanic, and 102 participants (44%) were White; 151 participants (65%) were married. Linear mixed-effects models found that CAPS-5 scores decreased in both treatment groups at the 1-month follow-up (IOP-PE: mean difference, -13.85 [95% CI, -16.47 to -11.23]; P < .001; massed-PE: mean difference, -14.13 [95% CI, -16.63 to -11.62]; P < .001). CAPS-5 change scores differed from 1- to 6-month follow-ups (mean difference, 4.44 [95% CI, 0.89 to 8.01]; P = .02). PTSD symptoms increased in massed-PE participants during follow-up (mean difference, 3.21 [95% CI, 0.65 to 5.77]; P = .01), whereas IOP-PE participants maintained treatment gains (mean difference, 1.23 [95% CI, -3.72 to 1.27]; P = .33). PCL-5 scores decreased in both groups from baseline to 1-month follow-up (IOP-PE: mean difference, -21.81 [95% CI, -25.57 to -18.04]; P < .001; massed-PE: mean difference, -19.96 [95% CI, -23.56 to -16.35]; P < .001) and were maintained at 6 months (IOP-PE: mean change, -0.21 [95% CI, -3.47 to 3.06]; P = .90; massed-PE: mean change, 3.02 [95% CI, -0.36 to 6.40]; P = .08). Both groups had notable PTSD diagnostic remission at posttreatment (IOP-PE: 48% [95% CI, 36% to 61%] of participants; massed-PE: 62% [95% CI, 51% to 73%] of participants), which was maintained at 6 months (IOP-PE: 53% [95% CI, 40% to 66%] of participants; massed-PE: 52% [95% CI, 38% to 66%] of participants). Most participants demonstrated reliable change on the CAPS-5 (61% [95% CI, 52% to 69%] of participants) and the PCL-5 (74% [95% CI, 66% to 81%] of participants) at the 1-month follow-up., Conclusions and Relevance: These findings suggest that PE can be adapted into compressed treatment formats that effectively reduce PTSD symptoms., Trial Registration: ClinicalTrials.gov Identifier: NCT03529435.
- Published
- 2023
- Full Text
- View/download PDF
10. Aging related impairment of brain microvascular bioenergetics involves oxidative phosphorylation and glycolytic pathways.
- Author
-
Sakamuri SS, Sure VN, Kolli L, Evans WR, Sperling JA, Bix GJ, Wang X, Atochin DN, Murfee WL, Mostany R, and Katakam PV
- Subjects
- Adenosine Triphosphate metabolism, Aging, Animals, Brain metabolism, Glycolysis physiology, Male, Mice, Oxygen Consumption, Energy Metabolism, Oxidative Phosphorylation
- Abstract
Mitochondrial and glycolytic energy pathways regulate the vascular functions. Aging impairs the cerebrovascular function and increases the risk of stroke and cognitive dysfunction. The goal of our study is to characterize the impact of aging on brain microvascular energetics. We measured the oxygen consumption and extracellular acidification rates of freshly isolated brain microvessels (BMVs) from young (2-4 months) and aged (20-22 months) C57Bl/6 male mice. Cellular ATP production in BMVs was predominantly dependent on oxidative phosphorylation (OXPHOS) with glucose as the preferred energy substrate. Aged BMVs exhibit lower ATP production rate with diminished OXPHOS and glycolytic rate accompanied by increased utilization of glutamine. Impairments of glycolysis displayed by aged BMVs included reduced compensatory glycolysis whereas impairments of mitochondrial respiration involved reduction of spare respiratory capacity and proton leak. Aged BMVs showed reduced levels of key glycolysis proteins including glucose transporter 1 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 but normal lactate dehydrogenase activity. Mitochondrial protein levels were mostly unchanged whereas citrate synthase activity was reduced, and glutamate dehydrogenase was increased in aged BMVs. Thus, for the first time, we identified the dominant role of mitochondria in bioenergetics of BMVs and the alterations of the energy pathways that make the aged BMVs vulnerable to injury.
- Published
- 2022
- Full Text
- View/download PDF
11. Glycolytic and Oxidative Phosphorylation Defects Precede the Development of Senescence in Primary Human Brain Microvascular Endothelial Cells.
- Author
-
Sakamuri SSVP, Sure VN, Kolli L, Liu N, Evans WR, Sperling JA, Busija DW, Wang X, Lindsey SH, Murfee WL, Mostany R, and Katakam PVG
- Subjects
- Humans, Glutamine metabolism, Glycolysis, Brain metabolism, Adenosine Triphosphate metabolism, Oxidative Phosphorylation, Endothelial Cells
- Abstract
Alterations of mitochondrial and glycolytic energy pathways related to aging could contribute to cerebrovascular dysfunction. We studied the impact of aging on energetics of primary human brain microvascular endothelial cells (HBMECs) by comparing the young (passages 7-9), pre-senescent (passages 13-15), and senescent (passages 20-21) cells. Pre-senescent HBMECs displayed decreased telomere length and undetectable telomerase activity although markers of senescence were unaffected. Bioenergetics in HBMECs were determined by measuring the oxygen consumption (OCR) and extracellular acidification (ECAR) rates. Cellular ATP production in young HBMECs was predominantly dependent on glycolysis with glutamine as the preferred fuel for mitochondrial oxidative phosphorylation (OXPHOS). In contrast, pre-senescent HBMECs displayed equal contribution to ATP production rate from glycolysis and OXPHOS with equal utilization of glutamine, glucose, and fatty acids as mitofuels. Compared to young, pre-senescent HBMECs showed a lower overall ATP production rate that was characterized by diminished contribution from glycolysis. Impairments of glycolysis displayed by pre-senescent cells included reduced basal glycolysis, compensatory glycolysis, and non-glycolytic acidification. Furthermore, impairments of mitochondrial respiration in pre-senescent cells involved the reduction of maximal respiration and spare respiratory capacity but intact basal and ATP production-related OCR. Proton leak and non-mitochondrial respiration, however, were unchanged in the pre-senescent HBMECs. HBMECS at passages 20-21 displayed expression of senescence markers and continued similar defects in glycolysis and worsened OXPHOS. Thus, for the first time, we characterized the bioenergetics of pre-senescent HBMECs comprehensively to identify the alterations of the energy pathways that could contribute to aging., (© 2022. The Author(s), under exclusive licence to American Aging Association.)
- Published
- 2022
- Full Text
- View/download PDF
12. Temporary PTSD symptom increases among individuals receiving CPT in a hybrid effectiveness-implementation trial: Potential predictors and association with overall symptom change trajectory.
- Author
-
Larsen SE, Mackintosh MA, La Bash H, Evans WR, Suvak MK, Shields N, Lane JEM, Sijercic I, Monson CM, and Wiltsey Stirman S
- Subjects
- Anxiety, Humans, Symptom Flare Up, Treatment Outcome, Cognitive Behavioral Therapy methods, Stress Disorders, Post-Traumatic psychology, Stress Disorders, Post-Traumatic therapy, Veterans psychology
- Abstract
Objective: Concern about symptom worsening with trauma-focused treatment may be one factor hindering the implementation of evidence-based treatments for PTSD, like cognitive processing therapy (CPT), despite evidence for their efficacy. Previous studies have examined the frequency and effect of symptom exacerbation, or temporary symptom increases, on outcomes, but primarily in randomized clinical trials., Method: We examined this issue in a community sample of participants receiving CPT from front-line clinicians learning to deliver CPT in a randomized controlled implementation trial of training strategies. Patient participants ( n = 183) completed self-report measures of PTSD symptoms at each session., Results: Most participants (67.3%) experienced at least one temporary symptom increase during CPT (only 1.6% continued to have higher symptoms by the end of treatment). Demographic variables, comorbid conditions (i.e., depression, anxiety, substance use), and baseline PTSD symptom levels did not predict symptom increases. Importantly, symptom increases did not predict treatment noncompletion, posttreatment PTSD symptom levels, or loss of probable PTSD diagnosis. Moreover, growth curve modeling revealed that temporary symptom increases did not predict the trajectory of PTSD symptoms over the course of treatment., Conclusions: The rates of symptom increases, which were higher than in previous studies, may be attributed to a routine care sample or to the differences in session timing and measurement. These results add to a nascent literature documenting that symptom increases may be a normal, transient part of treatment that do not impact a patient's ability to have symptom improvement during a course of CPT. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
- Published
- 2022
- Full Text
- View/download PDF
13. Cultivating psychological flexibility to address religious and spiritual suffering in moral injury.
- Author
-
Borges LM, Barnes SM, Farnsworth JK, Evans WR, Moon Z, Drescher KD, and Walser RD
- Subjects
- Anxiety, Clergy, Humans, Spirituality, Acceptance and Commitment Therapy, Stress Disorders, Post-Traumatic
- Abstract
In the current paper, we aim to expand the dialogue about applying psychological flexibility processes to moral injury-related spiritual suffering using Acceptance and Commitment Therapy (ACT). Psychological flexibility is the process of practicing present moment awareness and openness to experiences of emotions and thoughts, while also choosing to engage in actions that are consistent with one's values. This open, aware, and engaged approach to life fits well with spiritual endeavors. We provide a framework and a case example illustrating how spiritual care providers and Chaplains can use psychological flexibility processes to target spiritual suffering in the context of moral injury.
- Published
- 2022
- Full Text
- View/download PDF
14. Launching a Competency-Based Training Program in Evidence-Based Treatments for PTSD: Supporting Veteran-Serving Mental Health Providers in Texas.
- Author
-
Dondanville KA, Fina BA, Straud CL, Finley EP, Tyler H, Jacoby V, Blount TH, Moring JC, Pruiksma KE, Blankenship AE, Evans WR, and Zaturenskaya M
- Subjects
- Humans, Mental Health, Texas, United States, United States Department of Veterans Affairs, Stress Disorders, Post-Traumatic therapy, Veterans
- Abstract
Community mental health providers play an essential role in delivering services to veterans who either have limited access to U.S. Department of Veterans Affairs (VA) facilities or who prefer to seek care outside of the VA. However, there are limited training opportunities in evidence-based treatments for posttraumatic stress disorder (PTSD) outside of the VA. In 2017, the STRONG STAR Training Initiative was established to develop competency-based training in two evidence-based therapies for PTSD and to provide that training for mental health providers serving veterans and their families in community settings in Texas. This article describes the program's development and implementation, baseline characteristics of participating clinicians, and lessons learned toward the scale-up and extension of this competency-based training effort to include other interventions and locations.
- Published
- 2021
- Full Text
- View/download PDF
15. Peroxynitrite decomposition catalyst enhances respiratory function in isolated brain mitochondria.
- Author
-
Albuck AL, Sakamuri SSVP, Sperling JA, Evans WR, Kolli L, Sure VN, Mostany R, and Katakam PVG
- Subjects
- Animals, Brain drug effects, Catalysis, Cell Respiration, Membrane Potential, Mitochondrial, Metalloporphyrins pharmacology, Mice, Inbred C57BL, Mice, Knockout, Mitochondria drug effects, Molsidomine analogs & derivatives, Molsidomine pharmacology, Nitric Oxide Synthase Type I metabolism, Nitric Oxide Synthase Type III deficiency, Nitric Oxide Synthase Type III genetics, Peroxynitrous Acid pharmacology, Reactive Oxygen Species metabolism, Mice, Brain metabolism, Mitochondria metabolism, Nitric Oxide metabolism, Peroxynitrous Acid metabolism, Superoxides metabolism
- Abstract
Peroxynitrite (PN), generated from the reaction of nitric oxide (NO) and superoxide, is implicated in the pathogenesis of ischemic and neurodegenerative brain injuries. Mitochondria produce NO from mitochondrial NO synthases and superoxide by the electron transport chain. Our objective was to detect the generation of PN of mitochondrial origin and characterize its effects on mitochondrial respiratory function. Freshly isolated brain nonsynaptosomal mitochondria from C57Bl/6 (wild type, WT) and endothelial NO synthase knockout (eNOS-KO) mice were treated with exogenous PN (0.1, 1, 5 µmol/L) or a PN donor (SIN-1; 50 µmol/L) or a PN scavenger (FeTMPyP; 2.5 µmol/L). Oxygen consumption rate (OCR) was measured using Agilent Seahorse XFe24 analyzer and mitochondrial respiratory parameters were calculated. Mitochondrial membrane potential, superoxide, and PN were determined from rhodamine 123, dihydroethidium, and DAX-J2 PON green fluorescence measurements, respectively. Mitochondrial protein nitrotyrosination was determined by Western blots. Both exogenous PN and SIN-1 decreased respiratory function in WT isolated brain mitochondria. FeTMPyP enhanced state III and state IVo mitochondrial respiration in both WT and eNOS-KO mitochondria. FeTMPyP also elevated state IIIu respiration in eNOS-KO mitochondria. Unlike PN, neither SIN-1 nor FeTMPyP depolarized the mitochondria. Although mitochondrial protein nitrotyrosination was unaffected by SIN-1 or FeTMPyP, FeTMPyP reduced mitochondrial PN levels. Mitochondrial superoxide levels were increased by FeTMPyP but were unaffected by PN or SIN-1. Thus, we present the evidence of functionally significant PN generation in isolated brain mitochondria. Mitochondrial PN activity was physiologically relevant in WT mice and pathologically significant under conditions with eNOS deficiency. NEW & NOTEWORTHY Mitochondria generate superoxide and nitric oxide that could potentially react with each other to produce PN. We observed eNOS and nNOS immunoreactivity in isolated brain and heart mitochondria with pharmacological inhibition of nNOS found to modulate the mitochondrial respiratory function. This study provides evidence of generation of functionally significant PN in isolated brain mitochondria that affects respiratory function under physiological conditions. Importantly, the mitochondrial PN levels and activity were exaggerated in the eNOS-deficient mice, suggesting its pathological significance.
- Published
- 2021
- Full Text
- View/download PDF
16. Chronic imaging of mitochondria in the murine cerebral vasculature using in vivo two-photon microscopy.
- Author
-
Rutkai I, Evans WR, Bess N, Salter-Cid T, Čikić S, Chandra PK, Katakam PVG, Mostany R, and Busija DW
- Subjects
- Animals, Cells, Cultured, Endothelial Cells metabolism, Female, Male, Mice, Mice, Transgenic, Microscopy, Fluorescence, Multiphoton, Cerebrovascular Circulation physiology, Endothelium, Vascular metabolism, Mitochondria metabolism
- Abstract
Mitochondria are important regulators of cerebral vascular function in health and disease, but progress in understanding their roles has been hindered by methodological limitations. We report the first in vivo imaging of mitochondria specific to the cerebral endothelium in real time in the same mouse for extended periods. Mice expressing Dendra2 fluorescent protein in mitochondria (mito-Dendra2) in the cerebral vascular endothelium were generated by breeding PhAM-floxed and Tie2-Cre mice. We used mito-Dendra2 expression, cranial window implantation, and two-photon microscopy to visualize mitochondria in the cerebral vascular endothelium of mice. Immunohistochemistry and mitochondrial staining were used to confirm the localization of the mitochondrial signal to endothelial cells and the specificity of mito-Dendra2 to mitochondria. Mito-Dendra2 and Rhodamine B-conjugated dextran allowed simultaneous determinations of mitochondrial density, vessel diameters, area, and mitochondria-to-vessel ratio in vivo, repeatedly, in the same mouse. Endothelial expression of mito-Dendra2 was confirmed in vitro on brain slices and aorta. In addition, we observed an overlapping mito-Dendra2 and Chromeo mitochondrial staining of cultured brain microvascular endothelial cells. Repeated imaging of the same location in the cerebral microcirculation in the same mouse demonstrated stability of mito-Dendra2. While the overall mitochondrial signal was stable over time, mitochondria within the same endothelial cell were mobile. In conclusion, our results indicate that the mito-Dendra2 signal and vascular parameters are suitable for real-time and longitudinal examination of mitochondria in vivo in the cerebral vasculature of mice. NEW & NOTEWORTHY We introduce an innovative in vivo approach to study mitochondria in the cerebral circulation in their physiological environment by demonstrating the feasibility of long-term imaging and three-dimensional reconstruction. We postulate that the appropriate combination of Cre/Lox system and two-photon microscopy will contribute to a better understanding of the role of mitochondria in not only endothelium but also the different cell types of the cerebral circulation.
- Published
- 2020
- Full Text
- View/download PDF
17. Nitric oxide synthase inhibitors negatively regulate respiration in isolated rodent cardiac and brain mitochondria.
- Author
-
Sakamuri SSVP, Sperling JA, Evans WR, Dholakia MH, Albuck AL, Sure VN, Satou R, Mostany R, and Katakam PVG
- Subjects
- Amidines pharmacology, Animals, Brain drug effects, Brain metabolism, Mice, Mice, Inbred C57BL, Nitric Oxide Synthase Type I antagonists & inhibitors, Nitric Oxide Synthase Type III antagonists & inhibitors, Ornithine analogs & derivatives, Ornithine pharmacology, Enzyme Inhibitors pharmacology, Mitochondria drug effects, Mitochondria metabolism, Mitochondria, Heart drug effects, Mitochondria, Heart metabolism, Nitric Oxide Synthase antagonists & inhibitors, Oxygen Consumption drug effects
- Abstract
Nitric oxide (NO) is known to exert inhibitory control on mitochondrial respiration in the heart and brain. Evidence supports the presence of NO synthase (NOS) in the mitochondria (mtNOS) of cells; however, the functional role of mtNOS in the regulation of mitochondrial respiration is unclear. Our objective was to examine the effect of NOS inhibitors on mitochondrial respiration and protein S -nitrosylation. Freshly isolated cardiac and brain nonsynaptosomal mitochondria were incubated with selective inhibitors of neuronal (nNOS; ARL-17477, 1 µmol/L) or endothelial [eNOS; N
5 -(1-iminoethyl)-l-ornithine, NIO, 1 µmol/L] NOS isoforms. Mitochondrial respiratory parameters were calculated from the oxygen consumption rates measured using Agilent Seahorse XFe24 analyzer. Expression of NOS isoforms in the mitochondria was confirmed by immunoprecipitation and Western blot analysis. In addition, we determined the protein S -nitrosylation by biotin-switch method followed by immunoblotting. nNOS inhibitor decreased the state IIIu respiration in cardiac mitochondria and both state III and state IIIu respiration in brain mitochondria. In contrast, eNOS inhibitor had no effect on the respiration in the mitochondria from both heart and brain. Interestingly, NOS inhibitors reduced the levels of protein S -nitrosylation only in brain mitochondria, but nNOS and eNOS immunoreactivity was observed in the cardiac and brain mitochondrial lysates. Thus, the effects of NOS inhibitors on S -nitrosylation of mitochondrial proteins and mitochondrial respiration confirm the existence of functionally active NOS isoforms in the mitochondria. Notably, our study presents first evidence of the positive regulation of mitochondrial respiration by mitochondrial nNOS contrary to the current dogma representing the inhibitory role attributed to NOS isoforms. NEW & NOTEWORTHY Existence and the role of nitric oxide synthases in the mitochondria are controversial. We report for the first time that mitochondrial nNOS positively regulates respiration in isolated heart and brain mitochondria, thus challenging the existing dogma that NO is inhibitory to mitochondrial respiration. We have also demonstrated reduced protein S -nitrosylation by NOS inhibition in isolated mitochondria, supporting the presence of functional mitochondrial NOS.- Published
- 2020
- Full Text
- View/download PDF
18. Measuring Respiration in Isolated Murine Brain Mitochondria: Implications for Mechanistic Stroke Studies.
- Author
-
Sperling JA, Sakamuri SSVP, Albuck AL, Sure VN, Evans WR, Peterson NR, Rutkai I, Mostany R, Satou R, and Katakam PVG
- Subjects
- Adenosine Diphosphate pharmacology, Animals, Brain ultrastructure, Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone pharmacology, Electron Transport Complex I metabolism, Electron Transport Complex II metabolism, Fluorometry instrumentation, High-Throughput Screening Assays instrumentation, Hydrogen-Ion Concentration, Male, Mice, Mice, Inbred C57BL, Microchemistry instrumentation, Mitochondria drug effects, Mitochondrial Membranes drug effects, Mitochondrial Membranes metabolism, Mitochondrial Proteins analysis, Mitochondrial Proton-Translocating ATPases antagonists & inhibitors, Oligomycins pharmacology, Oxidative Phosphorylation, Oximetry instrumentation, Oxygen analysis, Protons, Brain metabolism, Fluorometry methods, High-Throughput Screening Assays methods, Microchemistry methods, Mitochondria metabolism, Oximetry methods, Oxygen Consumption drug effects
- Abstract
Measuring mitochondrial respiration in brain tissue is very critical in understanding the physiology and pathology of the central nervous system. Particularly, measurement of respiration in isolated mitochondria provides the advantage over the whole cells or tissues as the changes in respiratory function are intrinsic to mitochondrial structures rather than the cellular signaling that regulates mitochondria. Moreover, a high-throughput technique for measuring mitochondrial respiration minimizes the experimental time and the sample-to-sample variation. Here, we provide a detailed protocol for measuring respiration in isolated brain non-synaptosomal mitochondria using Agilent Seahorse XFe24 Analyzer. We optimized the protocol for the amount of mitochondria and concentrations of ADP, oligomycin, and trifluoromethoxy carbonylcyanide phenylhydrazone (FCCP) for measuring respiratory parameters for complex I-mediated respiration. In addition, we measured complex II-mediated respiratory parameters. We observed that 10 µg of mitochondrial protein per well, ADP concentrations ranging between 2.5 and 10 mmol/L along with 5 µmol/L of oligomycin, and 5 µmol/L of FCCP are ideal for measuring the complex I-mediated respiration in isolated mouse brain mitochondria. Furthermore, we determined that 2.5 µg of mitochondrial protein per well is ideal for measuring complex II-mediated respiration. Notably, we provide a discussion of logical analysis of data and how the assay could be utilized to design mechanistic studies for experimental stroke. In conclusion, we provide detailed experimental design for measurement of various respiratory parameters in isolated brain mitochondria utilizing a novel high-throughput technique along with interpretation and analysis of data.
- Published
- 2019
- Full Text
- View/download PDF
19. Genetic cancer risk assessment in general practice: systematic review of tools available, clinician attitudes, and patient outcomes.
- Author
-
Evans WR
- Subjects
- Attitude, Family Practice, Humans, Risk Assessment, General Practice, Neoplasms
- Published
- 2019
- Full Text
- View/download PDF
20. Intensive prolonged exposure therapy for combat-related posttraumatic stress disorder: Design and methodology of a randomized clinical trial.
- Author
-
Peterson AL, Foa EB, Blount TH, McLean CP, Shah DV, Young-McCaughan S, Litz BT, Schobitz RP, Castillo DT, Rentz TO, Yarvis JS, Dondanville KA, Fina BA, Hall-Clark BN, Brown LA, DeBeer BR, Jacoby VM, Hancock AK, Williamson DE, Evans WR, Synett S, Straud C, Hansen HR, Meyer EC, Javors MA, Sharrieff AM, Lara-Ruiz J, Koch LM, Roache JD, Mintz J, and Keane TM
- Subjects
- Humans, Ambulatory Care, Cognitive Behavioral Therapy methods, Randomized Controlled Trials as Topic, Combat Disorders therapy, Implosive Therapy methods, Military Personnel, Stress Disorders, Post-Traumatic therapy, Veterans
- Abstract
Combat-related posttraumatic stress disorder (PTSD) is the most common psychological health condition in military service members and veterans who have deployed to the combat theater since September 11, 2001. One of the highest research priorities for the Department of Defense and the Department of Veterans Affairs is to develop and evaluate the most efficient and efficacious treatments possible for combat-related PTSD. However, the treatment of combat-related PTSD in military service members and veterans has been significantly more challenging than the treatment of PTSD in civilians. Randomized clinical trials have demonstrated large posttreatment effect sizes for PTSD in civilian populations. However, recent randomized clinical trials of service members and veterans have achieved lesser reductions in PTSD symptoms. These results suggest that combat-related PTSD is unique. Innovative approaches are needed to augment established evidence-based treatments with targeted interventions that address the distinctive elements of combat-related traumas. This paper describes the design, methodology, and protocol of a randomized clinical trial to compare two intensive prolonged exposure therapy treatments for combat-related PTSD in active duty military service members and veterans and that can be administered in an acceptable, efficient manner in this population. Both interventions include intensive daily treatment over a 3-week period and a number of treatment enhancements hypothesized to result in greater reductions in combat-related PTSD symptoms. The study is designed to advance the delivery of care for combat-related PTSD by developing and evaluating the most potent treatments possible to reduce PTSD symptomatology and improve psychological, social, and occupational functioning., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
21. A novel high-throughput assay for respiration in isolated brain microvessels reveals impaired mitochondrial function in the aged mice.
- Author
-
Sure VN, Sakamuri SSVP, Sperling JA, Evans WR, Merdzo I, Mostany R, Murfee WL, Busija DW, and Katakam PVG
- Subjects
- Adenosine Triphosphate metabolism, Animals, Cell Respiration, Cerebral Arteries metabolism, In Vitro Techniques, Male, Mice, Mice, Inbred C57BL, Mitochondria metabolism, Models, Animal, Reference Values, Sensitivity and Specificity, Aging metabolism, Cerebrovascular Circulation physiology, High-Throughput Screening Assays methods, Microvessels metabolism, Oxygen Consumption physiology
- Abstract
Cerebral blood flow (CBF) is uniquely regulated by the anatomical design of the cerebral vasculature as well as through neurovascular coupling. The process of directing the CBF to meet the energy demands of neuronal activity is referred to as neurovascular coupling. Microvasculature in the brain constitutes the critical component of the neurovascular coupling. Mitochondria provide the majority of ATP to meet the high-energy demand of the brain. Impairment of mitochondrial function plays a central role in several age-related diseases such as hypertension, ischemic brain injury, Alzheimer's disease, and Parkinson disease. Interestingly, microvessels and small arteries of the brain have been the focus of the studies implicating the vascular mechanisms in several age-related neurological diseases. However, the role of microvascular mitochondrial dysfunction in age-related diseases remains unexplored. To date, high-throughput assay for measuring mitochondrial respiration in microvessels is lacking. The current study presents a novel method to measure mitochondrial respiratory parameters in freshly isolated microvessels from mouse brain ex vivo using Seahorse XFe24 Analyzer. We validated the method by demonstrating impairments of mitochondrial respiration in cerebral microvessels isolated from old mice compared to the young mice. Thus, application of mitochondrial respiration studies in microvessels will help identify novel vascular mechanisms underlying a variety of age-related neurological diseases.
- Published
- 2018
- Full Text
- View/download PDF
22. Dare to think rare: diagnostic delay and rare diseases.
- Author
-
Evans WR
- Subjects
- Delayed Diagnosis, Humans, Gatekeeping, Rare Diseases
- Published
- 2018
- Full Text
- View/download PDF
23. Morally injurious events and psychological distress among veterans: Examining the mediating role of religious and spiritual struggles.
- Author
-
Evans WR, Stanley MA, Barrera TL, Exline JJ, Pargament KI, and Teng EJ
- Subjects
- Female, Follow-Up Studies, Humans, Male, Middle Aged, Morals, Religion and Psychology, Stress, Psychological, Veterans psychology
- Abstract
Objective: Potentially morally injurious events (PMIEs)-violations (perpetrated or witnessed) of one's deeply held beliefs or values-have been associated with several forms of psychological distress. The values violated by PMIEs are often influenced by one's religion/spirituality (r/s). Struggles with one's r/s beliefs and/or practices may also contribute to elevated psychological distress. To further develop a framework for understanding and treating the sequelae of PMIE exposure, we examined the role of r/s struggles in the relation between PMIE exposure and psychological distress., Method: A diverse sample of 155 veterans at a large Veterans Affairs medical center completed questionnaires assessing PMIE exposure, r/s struggles, and psychological distress., Results: Findings revealed greater PMIE exposure predicted elevated r/s struggles as well as elevated symptoms of anxiety and posttraumatic stress disorder (PTSD). Likewise, greater r/s struggles predicted elevated anxiety, PTSD, and depression symptoms. Regression analyses revealed r/s struggles fully mediated the relation between PMIE exposure and anxiety as well as PTSD, and a significant indirect effect of PMIE exposure on depression symptoms through r/s struggles was observed. Follow-up analyses revealed that no specific domain of r/s struggles accounted for the relation between PMIE exposure and psychological distress; rather, the overarching construct of r/s struggles accounted for this relation., Conclusion: These findings advance the evolving theoretical framework of moral injury, elucidating the salience of r/s struggles in the development of distress. Implications for moral injury intervention call for attention to potential dissonance between actions (witnessed or perpetrated) and r/s underpinnings of the individual's moral framework. (PsycINFO Database Record, ((c) 2018 APA, all rights reserved).)
- Published
- 2018
- Full Text
- View/download PDF
24. Niemann-Pick type C disease - the tip of the iceberg? A review of neuropsychiatric presentation, diagnosis and treatment.
- Author
-
Evans WR and Hendriksz CJ
- Abstract
Niemann-Pick type C (NP-C) disease is a rare neurodegenerative lysosomal storage disorder. It is highly heterogeneous, and there is limited awareness of a substantial subgroup that has an attenuated adolescent/adult-onset disease. In these patients psychiatric features, often a psychosis, may dominate the initial impression, although often there is an associated ataxia and cognitive impairment. Typically, patients experience a substantial diagnostic delay. In this review we highlight the importance of early recognition and discuss the pathophysiology, neuropsychiatric presentation and recent changes in the investigation and work-up of these patients, and treatment options., Competing Interests: Declaration of interest W.R.H.E. is a trustee of NP-UK and C.J.H. is Director of FYMCA Medical and consultant for Amicus, Alexion, Actelion, BioMarin, Sanofi Genzyme and Shire.
- Published
- 2017
- Full Text
- View/download PDF
25. Rare diseases in general practice: recognising the zebras among the horses.
- Author
-
Evans WR and Rafi I
- Subjects
- Genetic Testing, Humans, Physician's Role, Physician-Patient Relations, General Practice, Rare Diseases diagnosis, Referral and Consultation organization & administration
- Published
- 2016
- Full Text
- View/download PDF
26. Refractive index measurements of solid parahydrogen.
- Author
-
Perera M, Tom BA, Miyamoto Y, Porambo MW, Moore LE, Evans WR, Momose T, and McCall BJ
- Abstract
Solid para-H2 is a promising gain medium for stimulated Raman scattering, due to its high number density and narrow Raman linewidth. In preparation for the design of a cw solid hydrogen Raman laser, we have made the first measurements, to our knowledge, of the index of refraction of a solid para-H2 crystal, in the wavelength range of 430-1100 nm. For a crystal stabilized at 4.4 K, this refractive index is measured to be n(p-H2)=1.130±0.001 at 514 nm. A slight, but significant, dependence on the final crystal-growth temperature is observed, with higher n(p-H2) at higher crystal-growth temperatures. Once a crystal is grown, it can be heated up to 10 K with no change in n(p-H2). The refractive index varies only slightly over the observed wavelength range, and no significant birefringence was observed.
- Published
- 2011
- Full Text
- View/download PDF
27. Evidence for paralytic shellfish poisons in the freshwater cyanobacterium Lyngbya wollei (Farlow ex Gomont) comb. nov.
- Author
-
Carmichael WW, Evans WR, Yin QQ, Bell P, and Moczydlowski E
- Subjects
- Amphibian Proteins, Animals, Biological Assay, Brain pathology, Carrier Proteins metabolism, Chromatography, High Pressure Liquid, Cyanobacteria isolation & purification, Lyngbya Toxins chemistry, Male, Mice, Molecular Structure, Rats, Saxitoxin isolation & purification, Sodium Channels metabolism, Southeastern United States, Water Microbiology, Cyanobacteria metabolism, Lyngbya Toxins metabolism, Lyngbya Toxins toxicity, Saxitoxin metabolism, Saxitoxin toxicity
- Abstract
Lyngbya wollei (Farlow ex Gomont) comb. nov., a perennial mat-forming filamentous cyanobacterium prevalent in lakes and reservoirs of the southeastern United States, was found to produce a potent, acutely lethal neurotoxin when tested in the mouse bioassay. Signs of poisoning were similar to those of paralytic shellfish poisoning. As part of the Tennessee Valley Authority master plan for Guntersville Reservoir, the mat-forming filamentous cyanobacterium L. wollei, a species that had recently invaded from other areas of the southern United States, was studied to determine if it could produce any of the known cyanotoxins. Of the 91 field samples collected at 10 locations at Guntersville Reservoir, Ala., on the Tennessee River, over a 3-year period, 72.5% were toxic. The minimum 100% lethal doses of the toxic samples ranged from 150 to 1,500 mg kg of lyophilized L. wollei cells-1, with the majority of samples being toxic at 500 mg kg-1. Samples bioassayed for paralytic shellfish toxins by the Association of Official Analytical Chemists method exhibited saxitoxin equivalents ranging from 0 to 58 micrograms g (dry weight)-1. Characteristics of the neurotoxic compound(s), such as the lack of adsorption by C18 solid-phase extraction columns, the short retention times on C18 high-performance liquid chromatography (HPLC) columns, the interaction of the neurotoxins with saxiphilin (a soluble saxitoxin-binding protein), and external blockage of voltage-sensitive sodium channels, led to our discovery that this neurotoxin(s) is related to the saxitoxins, the compounds responsible for paralytic shellfish poisonings. The major saxitoxin compounds thus far identified by comparison of HPLC fluorescence retention times are decarbamoyl gonyautoxins 2 and 3. There was no evidence of paralytic shellfish poison C toxins being produced by L. wollei. Fifty field samples were placed in unialgal culture and grown under defined culture conditions. Toxicity and signs of poisoning for these laboratory-grown strains of L. wollei were similar to those of the field collection samples.
- Published
- 1997
- Full Text
- View/download PDF
28. Chemical characterization and toxicity of dihydro derivatives of nodularin and microcystin-LR, potent cyanobacterial cyclic peptide hepatotoxins.
- Author
-
Namikoshi M, Choi BW, Sun F, Rinehart KL, Evans WR, and Carmichael WW
- Subjects
- Animals, Chemical and Drug Induced Liver Injury metabolism, Chromatography, Gas, Chromatography, High Pressure Liquid, Cyanobacteria immunology, Cyanobacteria metabolism, Cyanobacteria Toxins, Hydrolysis, Lethal Dose 50, Magnetic Resonance Spectroscopy, Male, Mice, Mice, Inbred ICR, Spectrometry, Mass, Fast Atom Bombardment, Spectrophotometry, Ultraviolet, Stereoisomerism, Structure-Activity Relationship, Chemical and Drug Induced Liver Injury etiology, Peptides, Cyclic chemistry, Peptides, Cyclic toxicity
- Abstract
Dihydro derivatives of nodularin (1) and microcystin-LR (4), potent cyclic peptide hepatotoxins isolated from Nodularia spumigena and Microcystis aeruginosa, respectively, were prepared by sodium borohydride reduction of the dehydroamino acid residues. The two stereoisomers of both dihydronodularin (2 and 3) and dihydromicrocystin-LR (5 and 6), isolated by reversed-phase HPLC, showed similar toxicity to each other [ip in mice, LD50 = 150 (2), 150 (3), 85 (5), and 100 (6) micrograms/kg]. The stereochemistries of the reduced amino acids obtained by acid hydrolysis of dihydronodularin and dihydromicrocystin-LR [respectively, alpha-(methylamino)butyric acid and N-methylalanine] were determined by GC on a permethylated beta-cyclodextrin capillary column as their trifluoroacetyl methyl ester derivatives. Authentic L- and DL-N-methylamino acids were prepared to compare directly with the natural amino acids. Deuterated derivatives were also prepared using sodium borodeuteride (98 atom % D), and the location (beta) and percentage (78-84%) of the deuterium incorporation were determined.
- Published
- 1993
- Full Text
- View/download PDF
29. Two methyl ester derivatives of microcystins, cyclic heptapeptide hepatotoxins, isolated from Anabaena flos-aquae strain CYA 83/1.
- Author
-
Sivonen K, Skulberg OM, Namikoshi M, Evans WR, Carmichael WW, and Rinehart KL
- Subjects
- Amino Acid Sequence, Animals, Chemical and Drug Induced Liver Injury etiology, Chromatography, High Pressure Liquid, Female, Marine Toxins, Mice, Microcystins, Molecular Sequence Data, Peptides, Cyclic toxicity, Spectrometry, Mass, Fast Atom Bombardment, Anabaena chemistry, Peptides, Cyclic analysis
- Abstract
Cultured cells of Anabaena flos-aquae strain CYA 83/1, isolated from Lake Edlandsvatn, Norway, produced two microcystin mono-methyl ester derivatives (1 and 2) at the D-Glu unit in addition to microcystin-LR (3), [D-Asp3]microcystin-LR (4), microcystin-RR (5), and [D-Asp3]microcystin-RR (6). Structures of these compounds were assigned based on their amino acid analysis with a Waters Pico Tag HPLC system plus fast atom bombardment mass spectrometry (FABMS), including tandem FABMS, analysis on the two new microcystins, [D-Glu(OCH3)6]microcystin-LR (1) and [D-Asp3, D-Glu(OCH3)6]microcystin-LR (2). Toxicity data were not obtained for 1 and 2 because of the small amounts isolated from the cells.
- Published
- 1992
- Full Text
- View/download PDF
30. Isolation and structures of microcystins from a cyanobacterial water bloom (Finland).
- Author
-
Namikoshi M, Sivonen K, Evans WR, Sun F, Carmichael WW, and Rinehart KL
- Subjects
- Amino Acids analysis, Animals, Chromatography, Gas, Chromatography, High Pressure Liquid, Hydrolysis, Male, Marine Toxins, Mice, Mice, Inbred ICR, Microcystins, Peptides, Cyclic analysis, Spectrometry, Mass, Fast Atom Bombardment, Cyanobacteria chemistry, Peptides, Cyclic isolation & purification
- Abstract
A hepatotoxic cyanobacterial (blue-green algal) water bloom was collected from a constructed water reservoir in Finland. The water bloom contained two cyanobacterial species, Microcystis aeruginosa and Aphanizomenon flos-aquae. Two hepatotoxins, 1 and 2, were isolated from extracts of lyophilized cells. The structures of 1 and 2 were assigned based upon their amino acid analyses on a Waters Pico Tag HPLC system and a chiral GC capillary column (Chirasil Val III), fast atom bombardment mass spectrometry (FABMS), high resolution FABMS, and tandem FABMS data. Toxin 1 was identical to a previously reported compound, [D-Asp3]microcystin-RR. Toxin 2 was new and was assigned the structure [D-Asp3]microcystin-YR.
- Published
- 1992
- Full Text
- View/download PDF
31. Two new L-serine variants of microcystins-LR and -RR from Anabaena sp. strains 202 A1 and 202 A2.
- Author
-
Namikoshi M, Sivonen K, Evans WR, Carmichael WW, Sun F, Rouhiainen L, Luukkainen R, and Rinehart KL
- Subjects
- Amino Acid Sequence, Animals, Chemical and Drug Induced Liver Injury etiology, Chromatography, Gas, Female, Hydrolysis, Marine Toxins, Mice, Microcystins, Molecular Sequence Data, Molecular Weight, Peptides, Cyclic analysis, Spectrometry, Mass, Fast Atom Bombardment, Anabaena chemistry, Peptides, Cyclic isolation & purification, Serine analysis
- Abstract
Two new microcystins, [L-Ser7]microcystin-LR (1) and [L-Ser7]microcystin-RR (2), were isolated from a filamentous fresh water cyanobacterium (blue-green alga), Anabaena sp. strain 202 A1, along with the two major toxins, [Dha7]microcystin-LR (3) and [Dha7]microcystin-RR (4) and their minor components the D-Asp variants [D-Asp3,Dha7]microcystin-LR (5) and [D-Asp3,Dha7]microcystin-RR (6). Anabaena sp. strain 202 A1 also produced another new toxin, whose structure is tentatively proposed as [D-Asp3,L-Ser7]microcystin-XR (7), where X is a leucine homologue. Anabaena sp. strain 202 A2 produced one new microcystin, 1, and three known microcystins, 3, 4, and 5. The structures of the toxins were assigned based on their amino acid analyses, and fast atom bombardment mass spectrometry data.
- Published
- 1992
- Full Text
- View/download PDF
32. Isolation and structures of five microcystins from a Russian Microcystis aeruginosa strain CALU 972.
- Author
-
Sivonen K, Namikoshi M, Evans WR, Gromov BV, Carmichael WW, and Rinehart KL
- Subjects
- Amino Acid Sequence, Amino Acids analysis, Marine Toxins, Microcystins, Molecular Sequence Data, Peptides, Cyclic analysis, Russia, Microcystis chemistry, Peptides, Cyclic isolation & purification
- Abstract
Five microcystins were obtained from Microcystis aeruginosa strain CALU 972 isolated from a hepatotoxic water bloom collected in Lake Kroshnosero (Russia). The structure of a new toxin (1) was determined as [Dha7]microcystin-YR by amino acid analyses and fast atom bombardment mass spectrometry, and the toxins 2, 3, 4, and 5 were assigned the structures as [Dha7]microcystin-LR, [D-Asp3,Dha7]microcystin-LR, [Dha7]microcystin-RR, and [D-Asp3,Dha7]microcystin-RR, respectively, by direct comparison with authentic samples.
- Published
- 1992
- Full Text
- View/download PDF
33. Structures of three new homotyrosine-containing microcystins and a new homophenylalanine variant from Anabaena sp. strain 66.
- Author
-
Namikoshi M, Sivonen K, Evans WR, Carmichael WW, Rouhiainen L, Luukkainen R, and Rinehart KL
- Subjects
- Amino Acid Sequence, Amino Acids analysis, Animals, Bacterial Toxins isolation & purification, Bacterial Toxins toxicity, Chromatography, High Pressure Liquid, Liver drug effects, Magnetic Resonance Spectroscopy, Mice, Molecular Sequence Data, Molecular Weight, Peptides, Cyclic isolation & purification, Peptides, Cyclic toxicity, Spectrometry, Mass, Fast Atom Bombardment, Tyrosine analysis, Valine analysis, Water Microbiology, Anabaena chemistry, Bacterial Toxins chemistry, Peptides, Cyclic chemistry
- Abstract
A hepatotoxic strain of cyanobacterium Anabaena sp. 66 was isolated from a hepatotoxic water bloom sample in Lake Kiikkara, Finland. Four cyclic heptapeptide hepatotoxins were isolated and purified by HPLC from cultured cells of this organism. The structures of three new homotyrosine (Hty) containing toxins, [Dha7]microcystin-HtyR (Dha = dehydroalanine) (1), [D-Asp3,Dha7]microcystin-HtyR (2), and [L-Ser7]microcystin-HtyR (3), were assigned, based upon amino acid analyses using both a Waters Pico Tag HPLC system and chiral capillary GC, 1H NMR, fast atom bombardment mass spectrometry (FABMS), and collisionally induced tandem FABMS. A new homophenylalanine (Hph) variant of 1, [Dha7]microcystin-HphR (4), was also obtained as a minor component. Compound 3 is most likely a biosynthetic precursor of 1. The four new toxins did not have an N-methyl group at the dehydroamino acid or its precursor unit.
- Published
- 1992
- Full Text
- View/download PDF
34. Structure determination and toxicity of a new microcystin from Microcystis aeruginosa strain 205.
- Author
-
Kiviranta J, Namikoshi M, Sivonen K, Evans WR, Carmichael WW, and Rinehart KL
- Subjects
- Aedes, Amino Acid Sequence, Amino Acids analysis, Animals, Chemical and Drug Induced Liver Injury physiopathology, Chromatography, High Pressure Liquid, Larva, Lethal Dose 50, Magnetic Resonance Spectroscopy, Mass Spectrometry, Microcystins, Molecular Sequence Data, Peptides, Cyclic toxicity, Microcystis chemistry, Peptides, Cyclic chemistry
- Abstract
A new hepatotoxic microcystin was isolated from the cyanobacterium Microcystis aeruginosa strain 205. Its structure was found to be [Dha7]microcystin-RR as determined by amino acid analysis, mass spectrometry and 1H NMR spectroscopy. LD50 value (i.p. mouse) of this toxin was 180 micrograms/kg. The 48 hr lethal concentration (48-hr-LC50) of the toxin for larvae of the yellow fever mosquito, Aedes aegypti, was 14.9 micrograms/ml.
- Published
- 1992
- Full Text
- View/download PDF
35. Isolation and characterization of a variety of microcystins from seven strains of the cyanobacterial genus Anabaena.
- Author
-
Sivonen K, Namikoshi M, Evans WR, Carmichael WW, Sun F, Rouhiainen L, Luukkainen R, and Rinehart KL
- Subjects
- Amino Acid Sequence, Anabaena isolation & purification, Animals, Fresh Water, Liver drug effects, Mice, Molecular Sequence Data, Peptides, Cyclic chemistry, Peptides, Cyclic toxicity, Species Specificity, Water Microbiology, Anabaena chemistry, Peptides, Cyclic isolation & purification
- Abstract
Hepatotoxins (microcystins) from seven freshwater Anabaena strains originating from three different Finnish lakes and one lake in Norway were isolated by high-performance liquid chromatography and characterized by amino acid analysis and fast atom bombardment mass spectrometry. All strains produced three to seven different microcystins. A total of 17 different compounds were isolated, of which 8 were known microcystins. The known compounds identified from six strains were MCYST (microcystin)-LR, [D-Asp3]MCYST-LR, [Dha7]MCYST-LR, [D-Asp3,Dha7]MCYST-LR, MCYST-RR, [D-Asp3]MCYST-RR, [Dha7]MCYST-RR, and [D-Asp3,Dha7]MCYST-RR. With the exception of MCYST-LR and [D-Asp3]MCYST-LR, this is the first time that isolation of these toxins from Anabaena strains has been reported. Three of the strains produced one to three toxins as minor components which could not be identified. Anabaena sp. strain 66 produced four unidentified toxins. The other Anabaena strains always contained both MCYST-LR and MCYST-RR and/or their demethyl variants. Quantitative differences between toxins within and between strains were detected; at times MCYST-LR and at other times MCYST-RR or demethyl derivatives thereof were the most abundant toxins found in a strain.
- Published
- 1992
- Full Text
- View/download PDF
36. Three new microcystins, cyclic heptapeptide hepatotoxins, from Nostoc sp. strain 152.
- Author
-
Sivonen K, Namikoshi M, Evans WR, Färdig M, Carmichael WW, and Rinehart KL
- Subjects
- Amino Acids analysis, Bacterial Toxins isolation & purification, Chromatography, Gas, Chromatography, High Pressure Liquid, Chromatography, Thin Layer, Hydrolysis, Microcystins, Molecular Structure, Molecular Weight, Peptides, Cyclic isolation & purification, Spectrometry, Mass, Fast Atom Bombardment, Bacterial Toxins chemistry, Cyanobacteria chemistry, Liver drug effects, Peptides, Cyclic chemistry
- Abstract
Three new cyclic heptapeptide hepatotoxins, [D-Ser1,ADMAdda5]microcystin-LR (1), [D-Asp3,-ADMAdda5]microcystin-LHar (2), and [ADMAdda5,Mser7]microcystin-LR (3), were isolated from the cyanobacterium (blue-green alga) Nostoc sp. strain 152, together with four known microcystins, [ADMAdda5]microcystin-LR (4), [ADMAdda5]microcystin-LHar (5), [D-Asp3,-ADMAdda5]microcystin-LR (6), and [DMAdda5]microcystin-LR (7). The structures of new microcystins were assigned on the basis of high-resolution fast atom bombardment mass spectrometry (HR FABMS), collisionally induced tandem FABMS (FABMS/MS), amino acid analysis, and gas chromatography (GC) on a chiral capillary column. All three new toxins contained 9-acetoxy-3-amino-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (ADMAdda) instead of the corresponding 9-methoxyl derivative (Adda), while 7 contains the corresponding 9-hydroxy analog (DMAdda). Compound 1 is the first microcystin reported that contains D-serine (D-Ser) in lieu of the D-alanine (D-Ala) unit which was thought to be an invariable amino acid component of the microcystins. Compound 2 has L-homoarginine (Har) instead of L-arginine (L-Arg) in 6 and D-aspartic acid (D-Asp) instead of D-erythro-beta-methylaspartic acid (D-MeAsp) in 5. Compound 3, the N-methylserine (Mser) variant of the N-methyldehydroalanine unit in 4, would be a biosynthetic precursor of 4.
- Published
- 1992
- Full Text
- View/download PDF
37. Microcystins from Anabaena flos-aquae NRC 525-17.
- Author
-
Harada K, Ogawa K, Kimura Y, Murata H, Suzuki M, Thorn PM, Evans WR, and Carmichael WW
- Subjects
- Amino Acids analysis, Animals, Bacterial Toxins isolation & purification, Bacterial Toxins toxicity, Chemical and Drug Induced Liver Injury etiology, Chemical and Drug Induced Liver Injury metabolism, Chromatography, High Pressure Liquid, Freeze Drying, Gas Chromatography-Mass Spectrometry, Lethal Dose 50, Magnetic Resonance Spectroscopy, Male, Mice, Mice, Inbred ICR, Organ Size drug effects, Anabaena metabolism, Bacterial Toxins analysis
- Abstract
Anabaena flos-aquae NRC 525-17 produces a very potent neurotoxin, anatoxin-a(s). During isolation of the neurotoxin, we found that the strain contains four other toxic compounds which show strong hepatotoxicity. The four toxins, toxins 1, 1', 2, and 3, were successfully purified. Toxin 2, one of major toxins, was identified as 3-desmethylmicrocystin LR (1) by comparison of spectral data of the known compound. Since the three other toxins contain an unknown amino acid, GC/MS was applied and it revealed the presence of homotyrosine in toxins 1 (2) and 1' (3). Only a partial structure was obtained for toxin 3 due to the small amount present in the cells.
- Published
- 1991
- Full Text
- View/download PDF
38. Bacteriochlorophyll and Photosynthetic Reaction Centers in Rhizobium Strain BTAi 1.
- Author
-
Evans WR, Fleischman DE, Calvert HE, Pyati PV, Alter GM, and Rao NS
- Abstract
Rhizobium strain BTAi 1, which nodulates both stems and roots of Aeschynomene indica L., formed bacteriochlorophyll and photosynthetic reaction centers resembling those of purple photosynthetic bacteria when grown aerobically ex planta under a light-dark cycle. Bacteriochlorophyll formation was not observed under continuous dark or light growth conditions. The amount of pigment formed was similar to that previously found in aerobic photosynthetic bacteria. Stem nodules appear to fix nitrogen photosynthetically, as illumination of A. indica stem nodules with near-infrared light resulted in an enhanced rate of acetylene reduction. Near-infrared light did not enhance acetylene reduction when either A. indica or soybean root nodules were illuminated. The BTAi 1 isolate can be differentiated from members of the family Rhodospirillaceae by several criteria.
- Published
- 1990
- Full Text
- View/download PDF
39. Controlling cost with self-funding.
- Author
-
Evans WR
- Subjects
- Societies, United States, Cost Control methods, Health Benefit Plans, Employee organization & administration, Insurance, Health organization & administration
- Published
- 1985
40. Azolla-Anabaena azollae Relationship: IV. Photosynthetically Driven, Nitrogenase-catalyzed H(2) Production.
- Author
-
Peters GA, Evans WR, and Toia RE
- Abstract
The water fern, Azolla caroliniana Willd., containing the symbiotic, heterocystous blue-green alga, Anabaena azollae, has been studied under various growth conditions to characterize its light-dependent production of H(2). The response of H(2) production to N(2) and C(2)H(2) and the absence of a differential effect of m-chlorocarbonyl cyanide phenylhydrazone on H(2) production and C(2)H(2) reduction, coupled with the parallel inhibition of both processes by DCMU imply that the production of H(2) is nitrogenase-catalyzed and ATP-dependent.H(2) was produced by fronds grown under air-CO(2) in the presence or absence of combined nitrogen. When cultured under argon-O(2)-CO(2), only those fronds provided with combined nitrogen remained viable and produced H(2). Fronds grown on nitrate under air plus 2% CO also produced H(2). In comparison to fronds grown on N(2) alone, fronds grown on nitrate had an increased rate of H(2) production relative to C(2)H(2) reduction, and the inhibition of H(2) production by air was less.CO in argon +/- CO(2) resulted in a partial inhibition of H(2) production, whereas CO in argon-CO(2)-C(2)H(2) enhanced H(2) production in fronds grown without combined nitrogen. Our studies strongly indicate that H(2) production is nitrogenase-catalyzed but the possibility that the symbiont contains a hydrogenase cannot be totally excluded.
- Published
- 1976
- Full Text
- View/download PDF
41. Effects of culture age on symbiotic infectivity of Rhizobium japonicum.
- Author
-
Bhuvaneswari TV, Mills KK, Crist DK, Evans WR, and Bauer WD
- Subjects
- Anti-Bacterial Agents pharmacology, Drug Resistance, Microbial, Lectins, Mutation, Plant Lectins, Rhizobium metabolism, Time Factors, Rhizobium growth & development, Soybean Proteins, Glycine max microbiology, Symbiosis
- Abstract
The infectivity of the soybean symbiont Rhizobium japonicum changed two- to fivefold with culture age for strains 110 ARS, 138 Str Spc, and 123 Spc, whereas culture age had relatively little effect on the infectivity of strains 83 Str and 61A76 Str. Infectivity was measured by determining the number of nodules which developed on soybean primary roots in the zone which contained developing and preemergent root hairs at the time of inoculation. Root cells in this region of the host root are susceptible to Rhizobium infection, but this susceptibility is lost during acropetal development and maturation of the root cells within a period of 4 to 6 h (T. V. Bhuvaneswari, B. G. Turgeon, and W. D. Bauer, Plant Physiol. 66:1027-1031, 1980). Profiles of nodulation frequency at different locations on the root were not affected by the age of the R. japonicum cultures, indicating that culture age affected the efficiency of Rhizobium infection rather than how soon infections were initiated after inoculation. Inoculum dose-response experiments also indicated that culture age affected the efficiency of infection. Two strains, 61A76 Str and 83 Str, were relatively inefficient at all culture ages, particularly at low inoculum doses. Changes in infectivity with culture age were reasonably well correlated with changes in the proportion of cells in a culture capable of binding soybean lectin. Suspensions of R. japonicum in water were found to retain their viability and infectivity.
- Published
- 1983
- Full Text
- View/download PDF
42. Preservation of Rhizobium viability and symbiotic infectivity by suspension in water.
- Author
-
Crist DK, Wyza RE, Mills KK, Bauer WD, and Evans WR
- Subjects
- Microscopy, Electron, Scanning, Plant Diseases, Preservation, Biological methods, Rhizobium cytology, Glycine max microbiology, Symbiosis, Temperature, Time Factors, Water Microbiology, Bacteriological Techniques, Fabaceae microbiology, Plants, Medicinal, Rhizobium physiology
- Abstract
Three Rhizobium japonicum strains and two slow-growing cowpea-type Rhizobium strains were found to remain viable and able to rapidly modulate their respective hosts after being stored in purified water at ambient temperatures for periods of 1 year and longer. Three fast-growing Rhizobium species did not remain viable under the same water storage conditions. After dilution of slow-growing Rhizobium strains with water to 10(3) to 10(5) cells ml-1, the bacteria multiplied until the viable cell count reached levels of between 10(6) and 10(7) cells ml-1. The viable cell count subsequently remained fairly constant. When the rhizobia were diluted to 10(7) cells ml-1, they did not multiply, but full viability was maintained. If the rhizobia were washed and suspended at 10(9) cells ml-1, viability slowly declined to 10(7) cells ml-1 during 9 months of storage. Scanning electron microscopy showed that no major morphological changes took place during storage. Preservation of slow-growing rhizobia in water suspensions could provide a simple and inexpensive alternative to current methods for the preservation of rhizobia for legume inoculation.
- Published
- 1984
- Full Text
- View/download PDF
43. Reduction of acetylene by stationary cultures of free-living Rhizobium sp. under atmospheric oxygen levels.
- Author
-
Evans WR and Keister DL
- Subjects
- Ammonium Chloride metabolism, Atmospheric Pressure, Bacterial Proteins biosynthesis, Ethylenes metabolism, Oxidation-Reduction, Acetylene metabolism, Oxygen, Rhizobium metabolism
- Abstract
The reduction of acetylene to ethylene by stationary (non-shaking) cultures of free-living rhizobia under atmospheric oxygen levels has been demonstrated. Under these conditions the development of the activity is inhibited by 10 mM NH4Cl and about 20% of oxygen is required for maximal activity. When the stationary cultures were shaken, oxygen concentrations of 1% and higher were found to be inhibitory. Specific activities of 20 and 40 nmol of acetylene reduced h-1 mg-1 protein were observed.
- Published
- 1976
- Full Text
- View/download PDF
44. Oxygen requirement for acetylene reduction by pure cultures of rhizobia.
- Author
-
Keister DL and Evans WR
- Subjects
- Ammonium Chloride pharmacology, Enzyme Repression, Nitrogenase biosynthesis, Oxidation-Reduction, Rhizobium enzymology, Rhizobium growth & development, Acetylene metabolism, Oxygen Consumption, Rhizobium metabolism
- Abstract
The oxygen and nutritional requirements for acetylene reduction by Rhizobium japonicum and Rhizobium sp. in liquid culture are described. The optimal oxygen concentration was about 0.1% in the gas phase, which is lower than that of any other known aerobic nitrogen-fixing microorganism. these organisms are also unique in that nitrogenase synthesis is not repressed in the presence of ammonium chloride under certain cultural conditions, in contrast to other wild-type bacteria.
- Published
- 1976
- Full Text
- View/download PDF
45. Origin of beta-aminoisobutvric acid in iris.
- Author
-
EVANS WR, TSAI CS, and AXELROD B
- Subjects
- Amino Acids chemistry, Iris, Plants chemistry
- Published
- 1961
- Full Text
- View/download PDF
46. Hybrid ribosome formation from Escherichia coli and chloroplast ribosome subunits.
- Author
-
Lee SG and Evans WR
- Subjects
- Cell Fractionation, Centrifugation, Density Gradient, Euglena, In Vitro Techniques, Phenylalanine biosynthesis, Polymers biosynthesis, Uracil Nucleotides physiology, Chloroplasts, Escherichia coli, Hybridization, Genetic, Ribosomes analysis
- Abstract
A 70S ribosome was prepared from a 30S ribosome subunit from Euglena gracilis chloroplasts and a 50S ribosome subunit from Escherichia coli. This hybrid ribosome was active in polyuridylic acid-directed polyphenylalanine synthesis.
- Published
- 1971
- Full Text
- View/download PDF
47. Quantitative determination of the carotenoids in yeasts of the genus Rhodotorula.
- Author
-
PETERSON WJ, EVANS WR, LECCE E, BELL TA, and ETCHELLS JL
- Subjects
- Biological Products, Carotenoids, Pigments, Biological analysis, Rhodotorula, Yeasts metabolism
- Published
- 1958
- Full Text
- View/download PDF
48. The fine structure of the pellicle of Euglena gracilis as revealed by freeze-etching.
- Author
-
Schwelitz FD, Evans WR, Mollenhauer HH, and Dilley RA
- Subjects
- Freeze Etching, Euglena cytology, Freezing, Histological Techniques, Microscopy, Electron
- Published
- 1970
- Full Text
- View/download PDF
49. The effect of cycloheximide on membrane transport in Euglena. A comparative study with nigericin.
- Author
-
Evans WR
- Subjects
- Carbon Isotopes, Cell Membrane Permeability drug effects, Centrifugation, Density Gradient, Chloroplasts drug effects, Depression, Chemical, Dinitrophenols antagonists & inhibitors, Dinitrophenols metabolism, Drug Antagonism, Euglena gracilis cytology, Euglena gracilis drug effects, Euglena gracilis growth & development, Glucose metabolism, Hydrogen-Ion Concentration, Kinetics, Nitriles antagonists & inhibitors, Nitriles pharmacology, Phenylalanine metabolism, Phenylhydrazines antagonists & inhibitors, Phenylhydrazines pharmacology, Potassium metabolism, Protein Biosynthesis, Ribosomes metabolism, Spectrum Analysis, Time Factors, Uncoupling Agents antagonists & inhibitors, Uncoupling Agents pharmacology, Anti-Bacterial Agents pharmacology, Biological Transport drug effects, Cycloheximide pharmacology, Euglena gracilis metabolism
- Published
- 1971
50. METABOLIC EVENTS DURING THE FORMATION OF A PHOTOSYNTHETIC FROM A NONPHOTOSYNTHETIC CELL.
- Author
-
SMILLIE RM, EVANS WR, and LYMAN H
- Subjects
- Arsenicals, Azides, Beryllium, Chloramphenicol, Chlorophyll, Chloroplasts, Cyanides, Dihydrolipoamide Dehydrogenase, Dinitrophenols, Euglena, Fluorides, Fluorouracil, Fructose-Bisphosphate Aldolase, Malonates, NADP, Nucleoproteins, Pharmacology, Photosynthesis, Proteins metabolism, RNA, Research, Ribonucleases, Ribosomes
- Published
- 1964
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.