69 results on '"Duncan KR"'
Search Results
2. Reaction of winter wheat and barley cultivars to Fusarium pseudograminearum‐inoculated fields in the dryland Pacific Northwest, USA
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Christina H. Hagerty, Larry Lutcher, Katherine McLaughlin, Patrick Hayes, Kim Garland‐Campbell, Timothy Paulitz, Ryan C. Graebner, and Duncan Kroese
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Agriculture ,Environmental sciences ,GE1-350 - Abstract
Abstract Fusarium crown rot (FCR) of winter wheat (Triticum aestivum L.), caused by Fusarium pseudograminearm and Fusarium culmorum, is a yield‐limiting disease in arid wheat‐producing areas of the inland Pacific Northwest. Foliar fungicide applications and currently available seed treatments do not control FCR. Alternative crops that provide a rotational benefit to reduce disease are not economically feasible. Major‐gene resistance is unavailable, but there is preliminary evidence that some wheat and barley (Hordeum vulgare L.) cultivars are more resistant than others. We followed up on preliminary work by growing 14 varieties of winter wheat, planted with in‐furrow FCR inoculum, in 2018 and 2019 in Morrow County, Oregon—one of the world's driest wheat producing regions. Two barley cultivars were added to the experiment during the second year of research. Evaluations of cultivar resistance were made by conducting aboveground visual assessments by counting whiteheads, prematurely senesced wheat heads that are indicative of FCR infection. Whitehead count information was correlated with yield and grain volume weight data. Maximum whitehead counts were measured in plots of the FCR‐susceptible check cultivar ‘Stephens’. There was no evidence of a cultivar‐specific relationship between whitehead count and corresponding values for yield and grain volume weight. There was limited evidence that some cultivars have the capacity to compensate for effects of disease.
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- 2021
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3. Smoking in pregnancy
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Duncan, KR, primary and Johnson, P, additional
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- 2001
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4. The Demonstration of Fetal Lung and Placental Maturation by Measurement of Echo-Planar Magnetic Resonance Relaxation Parameters
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Duncan, KR, primary, Moore, R, additional, Gowland, PA, additional, Johnson, IR, additional, and Baker, PN, additional
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- 1997
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5. Echoplanar Magnetic Resonance Imaging: A New Method for Demonstrating Fetal Hepatic Physiology
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Duncan, KR, primary, Baker, PN, additional, Gowland, PA, additional, Issa, B, additional, Moore, R, additional, and Johnson, IR, additional
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- 1996
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6. A comparison of the HINT and Quick SIN Tests.
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Duncan KR and Aarts NL
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- 2006
7. Twin-to-twin transfusion: update on management options and outcomes.
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Duncan KR and Duncan, Keith R
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- 2005
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8. ActinoBase: tools and protocols for researchers working on Streptomyces and other filamentous actinomycetes
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Feeney, MA, Newitt, JT, Addington, E, Algora-Gallardo, L, Allan, C, Ballis, L, Birke, AS, Castaño-Espriu, L, Charkoudian, LK, Devine, R, Gayrard, D, Hamilton, J, Hennrich, O, Hoskisson, PA, Keith-Baker, M, Klein, JG, Kruasuwan, W, Mark, DR, Mast, Y, McHugh, RE, McLean, TC, Mohit, E, Munnoch, JT, Murray, J, Noble, K, Otani, H, Parra, J, Pereira, CF, Perry, L, Pintor-Escobar, L, Pritchard, L, Prudence, SMM, Russell, AH, Schniete, JK, Seipke, R, Sélem-Mojica, N, Undabarrena, A, Vind, K, van Weze, GP, Wilkinson, B, Worsley, SF, Duncan, KR, Fernández-Martínez, LT, and Hutchings, MI
9. Association of Reperfusion and Procedural Characteristics with Endovascular Thrombectomy Outcomes in Large Core Stroke: Sub-Analysis from the SELECT2 Trial.
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Hassan AE, Abraham MG, Blackburn S, Hussain MS, Ortega-Gutierrez S, Chen M, Hu YC, Pujara DK, Herial NA, Tsai JP, Budzik RF, Manning NW, Kozak O, Hanel RA, Aghaebrahim AN, Gandhi CD, Al-Mufti F, Cheung A, Yan B, Mitchell P, Blasco J, Manzanera LSR, Vora N, Gibson D, Wallace A, Sahlein D, Elijovich L, Arenillas JF, Wu TY, Portela PC, de la Ossa NP, Schaafsma JD, Hicks WJ, Cordato DJ, Sangha N, Warach S, Kleinig TJ, Shaker F, Johns H, Tekle W, Dannenbaum MJ, Ebersole K, Toth G, Gooch M, Alhajeri A, Amuluru K, Ray A, Burkhardt JK, Abdulrazzak MA, Rosenbaum-Halevi DP, Kamal H, Duncan KR, Sitton CW, Churilov L, Pereira VM, Sunshine J, Nguyen TN, Fifi JT, Samaniego EA, Arthur A, Tjoumakaris S, Jabbour P, Davis SM, Wechsler L, Bambakidis N, Kasner SE, Grotta JC, Hill MD, Campbell BC, Ribo M, and Sarraj A
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Endovascular thrombectomy (EVT) was shown to be safe and efficacious in patients with large core stroke in multiple randomized controlled trials. However, the impact of reperfusion and other procedural metrics on EVT outcomes in this population has not been well-characterized., Methods: From the SELECT2 trial, we evaluated the association between reperfusion status, first-pass effect (near-complete or complete reperfusion [extended thrombolysis in cerebral infarction (eTICI) 2c-3] in 1 pass), procedure time and primary technique (aspiration vs stent-retriever) with functional outcomes in patients receiving EVT across ASPECTS (3 vs 4 vs 5) and core estimate strata (<70 vs ≥70ml, <100 vs ≥100ml, and <150 vs ≥150ml)., Results: Of 180 patients who received thrombectomy, 144 (80%) achieved successful reperfusion (eTICI 2b-3) and demonstrated better clinical outcomes (adjusted generalized odds ratios [aGenOR]: 1.48, 95% confidence interval [CI]: 1.01-2.15), compared with unsuccessful reperfusion. Results were consistent across ASPECTS and core estimate strata. Additionally, complete or near-complete reperfusion (eTICI 2c-3) was associated with better functional outcome (aGenOR: 1.99, 95% CI: 1.33-2.97) in patients achieving successful reperfusion. Functional outcome point estimates favored those with first-pass-effect (42 of 167 (25%), aGenOR: 1.46, 95% CI: 0.96-2.24). Longer procedure time was associated with worse modified Rankin scale (mRS) distribution (aGenOR: 0.92, 95% CI: 0.87-0.96, p-value = 0.001 for 10 minutes increment). Aspiration-first technique was used in 43 of 154 (25%) patients and was not associated with higher reperfusion (88% vs 78%, p = 0.18) or better functional outcome (aGenOR: 0.74, 95% CI: 0.50-1.10) as compared with stent-retriever first., Interpretation: Successful reperfusion resulted in improved clinical outcomes in large core patients across baseline ischemic core strata. Near complete or complete reperfusion was further associated with better outcomes, whereas prolonged procedures were associated with worse outcomes. Results were consistent regardless of the technique used. ANN NEUROL 2024., (© 2024 American Neurological Association.)
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- 2024
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10. Anticoagulation Use and Endovascular Thrombectomy in Patients with Large Core Stroke: A Secondary Analysis of the SELECT2 Trial.
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Pujara DK, Hussain MS, Abraham MG, Ortega-Gutierrez S, Chen M, Kasner SE, Churilov L, Sitton CW, Blackburn S, Sundararajan S, Hu YC, Herial NA, Budzik RF, Hicks WJ, Arenillas JF, Tsai JP, Kozak O, Cordato DJ, Manning NW, Hanel RA, Aghaebrahim AN, Wu TY, Cardona Portela P, Pérez de la Ossa N, Schaafsma JD, Blasco J, Sangha N, Warach S, Gandhi CD, Al-Mufti F, Kleinig TJ, Al-Shaibi F, Duncan KR, Shaker F, Johns H, Xiong W, DeGeorgia M, Opaskar A, Sunshine J, Ray A, Jabbour P, Bambakidis N, Sila C, Nguyen TN, Grotta JC, Hassan AE, Ribo M, Hill MD, Campbell BC, and Sarraj A
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- Humans, Aged, Female, Male, Middle Aged, Aged, 80 and over, Ischemic Stroke surgery, Stroke surgery, Treatment Outcome, Thrombectomy methods, Endovascular Procedures methods, Anticoagulants therapeutic use, Anticoagulants administration & dosage, Anticoagulants adverse effects
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Endovascular thrombectomy (EVT) safety and efficacy in patients with large core infarcts receiving oral anticoagulants (OAC) are unknown. In the SELECT2 trial (NCT03876457), 29 of 180 (16%; vitamin K antagonists 15, direct OACs 14) EVT, and 18 of 172 (10%; vitamin K antagonists 3, direct OACs 15) medical management (MM) patients reported OAC use at baseline. EVT was not associated with better clinical outcomes in the OAC group (EVT 6 [4-6] vs MM 5 [4-6], adjusted generalized odds ratio 0.89 [0.53-1.50]), but demonstrated significantly better outcomes in patients without OAC (EVT 4 [3-6] vs MM 5 [4-6], adjusted generalized odds ratio 1.87 [1.45-2.40], p = 0.02). The OAC group had higher comorbidities, including atrial fibrillation (70% vs 17%), congestive heart failure (28% vs 10%), and hypertension (87% vs 72%), suggesting increased frailty. However, the results were consistent after adjustment for these comorbidities, and was similar regardless of the type of OACs used. Whereas any hemorrhage rates were higher in the OAC group receiving EVT (86% in OAC vs 70% in no OAC), no parenchymal hemorrhage or symptomatic intracranial hemorrhage were observed with OAC use in both the EVT and MM arms. Although we did not find evidence that the effect was due to excess hemorrhage or confounded by underlying cardiac disease or older age, OAC use alone should not exclude patients from receiving EVT. Baseline comorbidities and ischemic injury extent should be considered while making individualized treatment decisions. ANN NEUROL 2024;96:887-894., (© 2024 American Neurological Association.)
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- 2024
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11. Microbe Profile: Pseudonocardia : antibiotics for every niche.
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Whatmough B, Holmes NA, Wilkinson B, Hutchings MI, Parra J, and Duncan KR
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- Animals, Symbiosis, Actinomycetales metabolism, Actinomycetales genetics, Actinomycetales classification, Genome, Bacterial, Ants microbiology, Insecta microbiology, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents metabolism, Anti-Bacterial Agents biosynthesis
- Abstract
Pseudonocardia species comprise a genus of filamentous, sporulating bacteria belonging to the phylum Actinomycetota, formerly Actinobacteria. They are found in marine and freshwater sediments and soils and associated with marine animals, insects, and plants. To date, they have mostly been studied because of their mutually beneficial symbiosis with fungus-growing ants in the tribe Attini . They have also attracted interest due to their biosynthetic capabilities, including the production of variably glycosylated polyenes and other novel antifungal compounds, and for their capacity to grow on a variety of hydrocarbons. The majority of clinically used antibiotics are derived from the specialised metabolites of filamentous actinomycete bacteria and most of these come from the genus Streptomyces . However, in the quest for novel chemistry there is increasing interest in studying other filamentous actinomycete genera, including Pseudonocardia . Here we outline the biological properties, genome size and structure and key features of the genus Pseudonocardia , namely their specialised metabolites and ecological roles.
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- 2024
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12. Multi-omics analysis of antagonistic interactions among free-living Pseudonocardia from diverse ecosystems.
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Parra J, Jarmusch SA, and Duncan KR
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- Antibiosis, Genomics, Geologic Sediments microbiology, Multigene Family, Multiomics, Ecosystem, Metabolomics, Phylogeny, Pseudonocardia genetics
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Actinomycetes are a phylogenetically diverse bacterial group which are widely distributed across terrestrial and aquatic ecosystems. Within this order, the genus Pseudonocardia and their specialised metabolites have been the focus of previous ecological studies due to their antagonistic interactions with other microorganisms and their mutualistic interactions with insects. However, the chemical ecology of free-living Pseudonocardia remains understudied. This study applies a multi-omics approach to investigate the chemical ecology of free-living actinomycetes from the genus Pseudonocardia. In a comparative genomics analysis, it was observed that the biosynthetic gene cluster family distribution was influenced mainly by phylogenetic distance rather than the geographic or ecological origin of strains. This finding was also observed in the mass spectrometry-based metabolomic profiles of nine Pseudonocardia species isolated from marine sediments and two terrestrial species. Antagonist interactions between these 11 species were examined, and matrix-assisted laser desorption/ionisation-mass spectrometry imaging was used to examine in situ chemical interactions between the Southern Ocean strains and their phylogenetically close relatives. Overall, it was demonstrated that phylogeny was the main predictor of antagonistic interactions among free-living Pseudonocardia. Moreover, two features at m/z 441.15 and m/z 332.20 were identified as metabolites related to these interspecies interactions., (© 2024 The Author(s). Environmental Microbiology published by John Wiley & Sons Ltd.)
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- 2024
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13. Clinical relevance of intracranial hemorrhage after thrombectomy versus medical management for large core infarct: a secondary analysis of the SELECT2 randomized trial.
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Chen M, Joshi KC, Kolb B, Sitton CW, Pujara DK, Abraham MG, Ortega-Gutierrez S, Kasner SE, Hussain SM, Churilov L, Blackburn S, Sundararajan S, Hu YC, Herial N, Arenillas JF, Tsai JP, Budzik RF, Hicks W, Kozak O, Yan B, Cordato D, Manning NW, Parsons M, Hanel RA, Aghaebrahim A, Wu T, Cardona Portela P, Gandhi CD, Al-Mufti F, Perez de la Ossa N, Schaafsma J, Blasco J, Sangha N, Warach S, Kleinig TJ, Johns H, Shaker F, Abdulrazzak MA, Ray A, Sunshine J, Opaskar A, Duncan KR, Xiong W, Al-Shaibi FK, Samaniego EA, Nguyen TN, Fifi JT, Tjoumakaris SI, Jabbour P, Mendes Pereira V, Lansberg MG, Sila C, Bambakidis NC, Davis S, Wechsler L, Albers GW, Grotta JC, Ribo M, Hassan AE, Campbell B, Hill MD, and Sarraj A
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Background: The incidence of intracerebral hemorrhage (ICH) and its effect on the outcomes after endovascular thrombectomy (EVT) for patients with large core infarcts have not been well-characterized., Methods: SELECT2 trial follow-up imaging was evaluated using the Heidelberg Bleeding Classification (HBC) to define hemorrhage grade. The association of ICH with clinical outcomes and treatment effect was examined., Results: Of 351 included patients, 194 (55%) and 189 (54%) demonstrated intracranial and intracerebral hemorrhage, respectively, with a higher incidence in EVT (134 (75%) and 130 (73%)) versus medical management (MM) (60 (35%) and 59 (34%), both P<0.001). Hemorrhagic infarction type 1 (HBC=1a) and type 2 (HBC=1b) accounted for 93% of all hemorrhages. Parenchymal hematoma (PH) type 1 (HBC=1c) and type 2 (HBC=2) were observed in 1 (0.6%) EVT-treated and 4 (2.2%) MM patients. Symptomatic ICH (sICH) (SITS-MOST definition) was seen in 0.6% EVT patients and 1.2% MM patients. No trend for ICH with core volumes (P=0.10) or Alberta Stroke Program Early CT Score (ASPECTS) (P=0.74) was observed. Among EVT patients, the presence of any ICH did not worsen clinical outcome (modified Rankin Scale (mRS) at 90 days: 4 (3-6) vs 4 (3-6); adjusted generalized OR 1.00, 95% CI 0.68 to 1.47, P>0.99) or modify EVT treatment effect (P
interaction =0.77)., Conclusions: ICH was present in 75% of the EVT population, but PH or sICH were infrequent. The presence of any ICH did not worsen functional outcomes or modify EVT treatment effect at 90-day follow-up. The high rate of hemorrhages overall still represents an opportunity for adjunctive therapies in EVT patients with a large ischemic core., Competing Interests: Competing interests: MC has received consulting fees from Medtronic and Microvention. AH has received grants from RESCUE - ICAD – Medtronic. He has also reported consulting fees from Medtronic, Microvention, Stryker, and Cerenovus. SO-G has received grants from Stryker Neurovascular and Microvention. He has also received modest consulting fees from Medtronic, Stryker Neurovascular, and Microvention. JB is a member of the speakers’ bureau for Stryker Neurovascular and Microvention, and holds leadership roles in Inspire S and A registries (Medtronics). TNN is a DSMB member for the SELECT2 trial and has received grants from Medtronic. SD is a DSMB member for the SELECT2 trial and on the advisory board for Medtronic. JF and LW are DSMB members for the SELECT2 trial. GA reports compensation from iSchemaView for consultant services; and stock holdings in iSchemaView. AS has received grant support from Stryker Neurovascular for the SELECT2 trial. He is also a member of the speaker’s bureau and advisory board for Stryker Neurovascular. The other authors have no competing interest relevant to this study., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)- Published
- 2024
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14. Endovascular Thrombectomy for Large Ischemic Stroke Across Ischemic Injury and Penumbra Profiles.
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Sarraj A, Hassan AE, Abraham MG, Ortega-Gutierrez S, Kasner SE, Hussain MS, Chen M, Churilov L, Johns H, Sitton CW, Yogendrakumar V, Ng FC, Pujara DK, Blackburn S, Sundararajan S, Hu YC, Herial NA, Arenillas JF, Tsai JP, Budzik RF, Hicks WJ, Kozak O, Yan B, Cordato DJ, Manning NW, Parsons MW, Cheung A, Hanel RA, Aghaebrahim AN, Wu TY, Portela PC, Gandhi CD, Al-Mufti F, Pérez de la Ossa N, Schaafsma JD, Blasco J, Sangha N, Warach S, Kleinig TJ, Shaker F, Al Shaibi F, Toth G, Abdulrazzak MA, Sharma G, Ray A, Sunshine J, Opaskar A, Duncan KR, Xiong W, Samaniego EA, Maali L, Lechtenberg CG, Renú A, Vora N, Nguyen T, Fifi JT, Tjoumakaris SI, Jabbour P, Tsivgoulis G, Pereira VM, Lansberg MG, DeGeorgia M, Sila CA, Bambakidis N, Hill MD, Davis SM, Wechsler L, Grotta JC, Ribo M, Albers GW, and Campbell BC
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- Adult, Humans, Female, Aged, Male, Thrombectomy adverse effects, Thrombectomy methods, Brain diagnostic imaging, Stroke diagnostic imaging, Stroke surgery, Ischemic Stroke diagnostic imaging, Ischemic Stroke surgery, Brain Ischemia diagnostic imaging, Brain Ischemia surgery
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Importance: Whether endovascular thrombectomy (EVT) efficacy for patients with acute ischemic stroke and large cores varies depending on the extent of ischemic injury is uncertain., Objective: To describe the relationship between imaging estimates of irreversibly injured brain (core) and at-risk regions (mismatch) and clinical outcomes and EVT treatment effect., Design, Setting, and Participants: An exploratory analysis of the SELECT2 trial, which randomized 352 adults (18-85 years) with acute ischemic stroke due to occlusion of the internal carotid or middle cerebral artery (M1 segment) and large ischemic core to EVT vs medical management (MM), across 31 global centers between October 2019 and September 2022., Intervention: EVT vs MM., Main Outcomes and Measures: Primary outcome was functional outcome-90-day mRS score (0, no symptoms, to 6, death) assessed by adjusted generalized OR (aGenOR; values >1 represent more favorable outcomes). Benefit of EVT vs MM was assessed across levels of ischemic injury defined by noncontrast CT using ASPECTS score and by the volume of brain with severely reduced blood flow on CT perfusion or restricted diffusion on MRI., Results: Among 352 patients randomized, 336 were analyzed (median age, 67 years; 139 [41.4%] female); of these, 168 (50%) were randomized to EVT, and 2 additional crossover MM patients received EVT. In an ordinal analysis of mRS at 90 days, EVT improved functional outcomes compared with MM within ASPECTS categories of 3 (aGenOR, 1.71 [95% CI, 1.04-2.81]), 4 (aGenOR, 2.01 [95% CI, 1.19-3.40]), and 5 (aGenOR, 1.85 [95% CI, 1.22-2.79]). Across strata for CT perfusion/MRI ischemic core volumes, aGenOR for EVT vs MM was 1.63 (95% CI, 1.23-2.16) for volumes ≥70 mL, 1.41 (95% CI, 0.99-2.02) for ≥100 mL, and 1.47 (95% CI, 0.84-2.56) for ≥150 mL. In the EVT group, outcomes worsened as ASPECTS decreased (aGenOR, 0.91 [95% CI, 0.82-1.00] per 1-point decrease) and as CT perfusion/MRI ischemic core volume increased (aGenOR, 0.92 [95% CI, 0.89-0.95] per 10-mL increase). No heterogeneity of EVT treatment effect was observed with or without mismatch, although few patients without mismatch were enrolled., Conclusion and Relevance: In this exploratory analysis of a randomized clinical trial of patients with extensive ischemic stroke, EVT improved clinical outcomes across a wide spectrum of infarct volumes, although enrollment of patients with minimal penumbra volume was low. In EVT-treated patients, clinical outcomes worsened as presenting ischemic injury estimates increased., Trial Registration: ClinicalTrials.gov Identifier: NCT03876457.
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- 2024
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15. Endovascular Thrombectomy Treatment Effect in Direct vs Transferred Patients With Large Ischemic Strokes: A Prespecified Analysis of the SELECT2 Trial.
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Sarraj A, Hill MD, Hussain MS, Abraham MG, Ortega-Gutierrez S, Chen M, Kasner SE, Churilov L, Pujara DK, Johns H, Blackburn S, Sundararajan S, Hu YC, Herial NA, Budzik RF, Hicks WJ, Arenillas JF, Tsai JP, Kozak O, Cordato DJ, Hanel RA, Wu TY, Portela PC, Gandhi CD, Al-Mufti F, Maali L, Gibson D, Pérez de la Ossa N, Schaafsma JD, Blasco J, Sangha N, Warach S, Kleinig TJ, Shaker F, Sitton CW, Nguyen T, Fifi JT, Jabbour P, Furlan A, Lansberg MG, Tsivgoulis G, Sila C, Bambakidis N, Davis S, Wechsler L, Albers GW, Grotta JC, Ribo M, Campbell BC, Hassan AE, Vora N, Manning NW, Cheung A, Aghaebrahim AN, Paipa Merchán AJ, Sahlein D, Requena Ruiz M, Elijovich L, Arthur A, Al-Shaibi F, Samaniego EA, Duncan KR, Opaskar A, Ray A, Xiong W, Sunshine J, DeGeorgia M, Tjoumakaris S, and Mendes Pereira V
- Abstract
Importance: Patients with large ischemic core stroke have poor clinical outcomes and are frequently not considered for interfacility transfer for endovascular thrombectomy (EVT)., Objective: To assess EVT treatment effects in transferred vs directly presenting patients and to evaluate the association between transfer times and neuroimaging changes with EVT clinical outcomes., Design, Setting, and Participants: This prespecified secondary analysis of the SELECT2 trial, which evaluated EVT vs medical management (MM) in patients with large ischemic stroke, evaluated adults aged 18 to 85 years with acute ischemic stroke due to occlusion of the internal carotid or middle cerebral artery (M1 segment) as well as an Alberta Stroke Program Early CT Score (ASPECTS) of 3 to 5, core of 50 mL or greater on imaging, or both. Patients were enrolled between October 2019 and September 2022 from 31 EVT-capable centers in the US, Canada, Europe, Australia, and New Zealand. Data were analyzed from August 2023 to January 2024., Interventions: EVT vs MM., Main Outcomes and Measures: Functional outcome, defined as modified Rankin Scale (mRS) score at 90 days with blinded adjudication., Results: A total of 958 patients were screened and 606 patients were excluded. Of 352 enrolled patients, 145 (41.2%) were female, and the median (IQR) age was 66.5 (58-75) years. A total of 211 patients (59.9%) were transfers, while 141 (40.1%) presented directly. The median (IQR) transfer time was 178 (136-230) minutes. The median (IQR) ASPECTS decreased from the referring hospital (5 [4-7]) to an EVT-capable center (4 [3-5]). Thrombectomy treatment effect was observed in both directly presenting patients (adjusted generalized odds ratio [OR], 2.01; 95% CI, 1.42-2.86) and transferred patients (adjusted generalized OR, 1.50; 95% CI, 1.11-2.03) without heterogeneity (P for interaction = .14). Treatment effect point estimates favored EVT among 82 transferred patients with a referral hospital ASPECTS of 5 or less (44 received EVT; adjusted generalized OR, 1.52; 95% CI, 0.89-2.58). ASPECTS loss was associated with numerically worse EVT outcomes (adjusted generalized OR per 1-ASPECTS point loss, 0.89; 95% CI, 0.77-1.02). EVT treatment effect estimates were lower in patients with transfer times of 3 hours or more (adjusted generalized OR, 1.15; 95% CI, 0.73-1.80)., Conclusions and Relevance: Both directly presenting and transferred patients with large ischemic stroke in the SELECT2 trial benefited from EVT, including those with low ASPECTS at referring hospitals. However, the association of EVT with better functional outcomes was numerically better in patients presenting directly to EVT-capable centers. Prolonged transfer times and evolution of ischemic change were associated with worse EVT outcomes. These findings emphasize the need for rapid identification of patients suitable for transfer and expedited transport., Trial Registration: ClinicalTrials.gov Identifier: NCT03876457.
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- 2024
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16. Antibiotics from rare actinomycetes, beyond the genus Streptomyces.
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Parra J, Beaton A, Seipke RF, Wilkinson B, Hutchings MI, and Duncan KR
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- Actinomyces, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents metabolism, Biodiversity, Actinobacteria genetics, Actinobacteria metabolism, Streptomyces genetics
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Throughout the golden age of antibiotic discovery, Streptomyces have been unsurpassed for their ability to produce bioactive metabolites. Yet, this success has been hampered by rediscovery. As we enter a new stage of biodiscovery, omics data and existing scientific repositories can enable informed choices on the biodiversity that may yield novel antibiotics. Here, we focus on the chemical potential of rare actinomycetes, defined as bacteria within the order Actinomycetales, but not belonging to the genus Streptomyces. They are named as such due to their less-frequent isolation under standard laboratory practices, yet there is increasing evidence to suggest these biologically diverse genera harbour considerable biosynthetic and chemical diversity. In this review, we focus on examples of successful isolation and genera that have been the focus of more concentrated biodiscovery efforts, we survey the representation of rare actinomycete taxa, compared with Streptomyces, across natural product data repositories in addition to its biosynthetic potential. This is followed by an overview of clinically useful drugs produced by rare actinomycetes and considerations for future biodiscovery efforts. There is much to learn about these underexplored taxa, and mounting evidence suggests that they are a fruitful avenue for the discovery of novel antimicrobials., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships that may be considered as potential competing interests: K DUNCAN reports financial support was provided by Biotechnology and Biological Sciences Research Council., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)
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- 2023
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17. Artificial intelligence for natural product drug discovery.
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Mullowney MW, Duncan KR, Elsayed SS, Garg N, van der Hooft JJJ, Martin NI, Meijer D, Terlouw BR, Biermann F, Blin K, Durairaj J, Gorostiola González M, Helfrich EJN, Huber F, Leopold-Messer S, Rajan K, de Rond T, van Santen JA, Sorokina M, Balunas MJ, Beniddir MA, van Bergeijk DA, Carroll LM, Clark CM, Clevert DA, Dejong CA, Du C, Ferrinho S, Grisoni F, Hofstetter A, Jespers W, Kalinina OV, Kautsar SA, Kim H, Leao TF, Masschelein J, Rees ER, Reher R, Reker D, Schwaller P, Segler M, Skinnider MA, Walker AS, Willighagen EL, Zdrazil B, Ziemert N, Goss RJM, Guyomard P, Volkamer A, Gerwick WH, Kim HU, Müller R, van Wezel GP, van Westen GJP, Hirsch AKH, Linington RG, Robinson SL, and Medema MH
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- Humans, Algorithms, Machine Learning, Drug Discovery, Drug Design, Artificial Intelligence, Biological Products pharmacology
- Abstract
Developments in computational omics technologies have provided new means to access the hidden diversity of natural products, unearthing new potential for drug discovery. In parallel, artificial intelligence approaches such as machine learning have led to exciting developments in the computational drug design field, facilitating biological activity prediction and de novo drug design for molecular targets of interest. Here, we describe current and future synergies between these developments to effectively identify drug candidates from the plethora of molecules produced by nature. We also discuss how to address key challenges in realizing the potential of these synergies, such as the need for high-quality datasets to train deep learning algorithms and appropriate strategies for algorithm validation., (© 2023. Springer Nature Limited.)
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- 2023
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18. Blood pressure management in ischemic stroke patients undergoing mechanical thrombectomy.
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De Georgia M, Bowen T, Duncan KR, and Chebl AB
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The relationship between presenting blood pressure in acute ischemic stroke patients and outcome is complex. Several studies have demonstrated a U-shaped curve with worse outcomes when blood pressure is high or low. The American Heart Association/American Stroke Association guidelines recommend values of blood pressure < 185/110 mmHg in patients treated with intravenous t-PA and "permissive hypertension" up to 220/120 mmHg in those not treated with intravenous t-PA. The optimal blood pressure target is less clear in patients undergoing mechanical thrombectomy. Before thrombectomy, the guidelines recommend a blood pressure < 185/110 mmHg though patients with even lower systolic blood pressures may have better outcomes. During and after thrombectomy, the guidelines recommend a blood pressure < 180/105 mmHg. However, several studies have suggested that during thrombectomy the primary goal should be to prevent significant low blood pressure (e.g., target systolic blood pressure > 140 mmHg or MAP > 70 mmHg). After thrombectomy, the primary goal should be to prevent high blood pressure (e.g., target systolic blood pressure < 160 mmHg or MAP < 90 mmHg). To make more specific recommendations, large, randomized-control studies are needed that address factors such as the baseline blood pressure, timing and degree of revascularization, status of collaterals, and estimated risk of reperfusion injury., (© 2023. The Author(s).)
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- 2023
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19. Association of Endovascular Thrombectomy vs Medical Management With Functional and Safety Outcomes in Patients Treated Beyond 24 Hours of Last Known Well: The SELECT Late Study.
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Sarraj A, Kleinig TJ, Hassan AE, Portela PC, Ortega-Gutierrez S, Abraham MG, Manning NW, Siegler JE, Goyal N, Maali L, Blackburn S, Wu TY, Blasco J, Renú A, Sangha NS, Arenillas JF, McCullough-Hicks ME, Wallace A, Gibson D, Pujara DK, Shaker F, de Lera Alfonso M, Olivé-Gadea M, Farooqui M, Vivanco Suarez JS, Iezzi Z, Khalife J, Lechtenberg CG, Qadri SK, Moussa RB, Abdulrazzak MA, Almaghrabi TS, Mir O, Beharry J, Krishnaiah B, Miller M, Khalil N, Sharma GJ, Katsanos AH, Fadhil A, Duncan KR, Hu Y, Martin-Schild SB, Tsivgoulis GK, Cordato D, Furlan A, Churilov L, Mitchell PJ, Arthur AS, Parsons MW, Grotta JC, Sitton CW, Ribo M, Albers GW, and Campbell BCV
- Subjects
- Humans, Female, Aged, Retrospective Studies, Thrombectomy methods, Intracranial Hemorrhages etiology, Treatment Outcome, Endovascular Procedures methods, Stroke surgery, Stroke etiology, Brain Ischemia therapy
- Abstract
Importance: The role of endovascular thrombectomy is uncertain for patients presenting beyond 24 hours of the time they were last known well., Objective: To evaluate functional and safety outcomes for endovascular thrombectomy (EVT) vs medical management in patients with large-vessel occlusion beyond 24 hours of last known well., Design, Setting, and Participants: This retrospective observational cohort study enrolled patients between July 2012 and December 2021 at 17 centers across the United States, Spain, Australia, and New Zealand. Eligible patients had occlusions in the internal carotid artery or middle cerebral artery (M1 or M2 segment) and were treated with EVT or medical management beyond 24 hours of last known well., Interventions: Endovascular thrombectomy or medical management (control)., Main Outcomes and Measures: Primary outcome was functional independence (modified Rankin Scale score 0-2). Mortality and symptomatic intracranial hemorrhage (sICH) were safety outcomes. Propensity score (PS)-weighted multivariable logistic regression analyses were adjusted for prespecified clinical characteristics, perfusion parameters, and/or Alberta Stroke Program Early CT Score (ASPECTS) and were repeated in subsequent 1:1 PS-matched cohorts., Results: Of 301 patients (median [IQR] age, 69 years [59-81]; 149 female), 185 patients (61%) received EVT and 116 (39%) received medical management. In adjusted analyses, EVT was associated with better functional independence (38% vs control, 10%; inverse probability treatment weighting adjusted odds ratio [IPTW aOR], 4.56; 95% CI, 2.28-9.09; P < .001) despite increased odds of sICH (10.1% for EVT vs 1.7% for control; IPTW aOR, 10.65; 95% CI, 2.19-51.69; P = .003). This association persisted after PS-based matching on (1) clinical characteristics and ASPECTS (EVT, 35%, vs control, 19%; aOR, 3.14; 95% CI, 1.02-9.72; P = .047); (2) clinical characteristics and perfusion parameters (EVT, 35%, vs control, 17%; aOR, 4.17; 95% CI, 1.15-15.17; P = .03); and (3) clinical characteristics, ASPECTS, and perfusion parameters (EVT, 45%, vs control, 21%; aOR, 4.39; 95% CI, 1.04-18.53; P = .04). Patients receiving EVT had lower odds of mortality (26%) compared with those in the control group (41%; IPTW aOR, 0.49; 95% CI, 0.27-0.89; P = .02)., Conclusions and Relevance: In this study of treatment beyond 24 hours of last known well, EVT was associated with higher odds of functional independence compared with medical management, with consistent results obtained in PS-matched subpopulations and patients with presence of mismatch, despite increased odds of sICH. Our findings support EVT feasibility in selected patients beyond 24 hours. Prospective studies are warranted for confirmation.
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- 2023
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20. MIBiG 3.0: a community-driven effort to annotate experimentally validated biosynthetic gene clusters.
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Terlouw BR, Blin K, Navarro-Muñoz JC, Avalon NE, Chevrette MG, Egbert S, Lee S, Meijer D, Recchia MJJ, Reitz ZL, van Santen JA, Selem-Mojica N, Tørring T, Zaroubi L, Alanjary M, Aleti G, Aguilar C, Al-Salihi SAA, Augustijn HE, Avelar-Rivas JA, Avitia-Domínguez LA, Barona-Gómez F, Bernaldo-Agüero J, Bielinski VA, Biermann F, Booth TJ, Carrion Bravo VJ, Castelo-Branco R, Chagas FO, Cruz-Morales P, Du C, Duncan KR, Gavriilidou A, Gayrard D, Gutiérrez-García K, Haslinger K, Helfrich EJN, van der Hooft JJJ, Jati AP, Kalkreuter E, Kalyvas N, Kang KB, Kautsar S, Kim W, Kunjapur AM, Li YX, Lin GM, Loureiro C, Louwen JJR, Louwen NLL, Lund G, Parra J, Philmus B, Pourmohsenin B, Pronk LJU, Rego A, Rex DAB, Robinson S, Rosas-Becerra LR, Roxborough ET, Schorn MA, Scobie DJ, Singh KS, Sokolova N, Tang X, Udwary D, Vigneshwari A, Vind K, Vromans SPJM, Waschulin V, Williams SE, Winter JM, Witte TE, Xie H, Yang D, Yu J, Zdouc M, Zhong Z, Collemare J, Linington RG, Weber T, and Medema MH
- Subjects
- Multigene Family, Biosynthetic Pathways genetics, Genomics, Genome
- Abstract
With an ever-increasing amount of (meta)genomic data being deposited in sequence databases, (meta)genome mining for natural product biosynthetic pathways occupies a critical role in the discovery of novel pharmaceutical drugs, crop protection agents and biomaterials. The genes that encode these pathways are often organised into biosynthetic gene clusters (BGCs). In 2015, we defined the Minimum Information about a Biosynthetic Gene cluster (MIBiG): a standardised data format that describes the minimally required information to uniquely characterise a BGC. We simultaneously constructed an accompanying online database of BGCs, which has since been widely used by the community as a reference dataset for BGCs and was expanded to 2021 entries in 2019 (MIBiG 2.0). Here, we describe MIBiG 3.0, a database update comprising large-scale validation and re-annotation of existing entries and 661 new entries. Particular attention was paid to the annotation of compound structures and biological activities, as well as protein domain selectivities. Together, these new features keep the database up-to-date, and will provide new opportunities for the scientific community to use its freely available data, e.g. for the training of new machine learning models to predict sequence-structure-function relationships for diverse natural products. MIBiG 3.0 is accessible online at https://mibig.secondarymetabolites.org/., (© The Author(s) 2022. Published by Oxford University Press on behalf of Nucleic Acids Research.)
- Published
- 2023
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21. ActinoBase: tools and protocols for researchers working on Streptomyces and other filamentous actinobacteria.
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Feeney MA, Newitt JT, Addington E, Algora-Gallardo L, Allan C, Balis L, Birke AS, Castaño-Espriu L, Charkoudian LK, Devine R, Gayrard D, Hamilton J, Hennrich O, Hoskisson PA, Keith-Baker M, Klein JG, Kruasuwan W, Mark DR, Mast Y, McHugh RE, McLean TC, Mohit E, Munnoch JT, Murray J, Noble K, Otani H, Parra J, Pereira CF, Perry L, Pintor-Escobar L, Pritchard L, Prudence SMM, Russell AH, Schniete JK, Seipke RF, Sélem-Mojica N, Undabarrena A, Vind K, van Wezel GP, Wilkinson B, Worsley SF, Duncan KR, Fernández-Martínez LT, and Hutchings MI
- Subjects
- Anti-Bacterial Agents, Actinobacteria genetics, Streptomyces genetics
- Abstract
Actinobacteria is an ancient phylum of Gram-positive bacteria with a characteristic high GC content to their DNA. The ActinoBase Wiki is focused on the filamentous actinobacteria, such as Streptomyces species, and the techniques and growth conditions used to study them. These organisms are studied because of their complex developmental life cycles and diverse specialised metabolism which produces many of the antibiotics currently used in the clinic. ActinoBase is a community effort that provides valuable and freely accessible resources, including protocols and practical information about filamentous actinobacteria. It is aimed at enabling knowledge exchange between members of the international research community working with these fascinating bacteria. ActinoBase is an anchor platform that underpins worldwide efforts to understand the ecology, biology and metabolic potential of these organisms. There are two key differences that set ActinoBase apart from other Wiki-based platforms: [1] ActinoBase is specifically aimed at researchers working on filamentous actinobacteria and is tailored to help users overcome challenges working with these bacteria and [2] it provides a freely accessible resource with global networking opportunities for researchers with a broad range of experience in this field.
- Published
- 2022
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22. Stance Phase Gait Training Post Stroke Using Simultaneous Transcranial Direct Current Stimulation and Motor Learning-Based Virtual Reality-Assisted Therapy: Protocol Development and Initial Testing.
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Salameh A, McCabe J, Skelly M, Duncan KR, Chen Z, Tatsuoka C, Bikson M, Hardin EC, Daly JJ, and Pundik S
- Abstract
Gait deficits are often persistent after stroke, and current rehabilitation methods do not restore normal gait for everyone. Targeted methods of focused gait therapy that meet the individual needs of each stroke survivor are needed. Our objective was to develop and test a combination protocol of simultaneous brain stimulation and focused stance phase training for people with chronic stroke (>6 months). We combined Transcranial Direct Current Stimulation (tDCS) with targeted stance phase therapy using Virtual Reality (VR)-assisted treadmill training and overground practice. The training was guided by motor learning principles. Five users (>6 months post-stroke with stance phase gait deficits) completed 10 treatment sessions. Each session began with 30 min of VR-assisted treadmill training designed to apply motor learning (ML)-based stance phase targeted practice. During the first 15 min of the treadmill training, bihemispheric tDCS was simultaneously delivered. Immediately after, users completed 30 min of overground (ML)-based gait training. The outcomes included the feasibility of protocol administration, gait speed, Timed Up and Go (TUG), Functional Gait Assessment (FGA), paretic limb stance phase control capability, and the Fugl−Meyer for lower extremity coordination (FMLE). The changes in the outcome measures (except the assessments of stance phase control capability) were calculated as the difference from baseline. Statistically and clinically significant improvements were observed after 10 treatment sessions in gait speed (0.25 ± 0.11 m/s) and FGA (4.55 ± 3.08 points). Statistically significant improvements were observed in TUG (2.36 ± 3.81 s) and FMLE (4.08 ± 1.82 points). A 10-session intervention combining tDCS and ML-based task-specific gait rehabilitation was feasible and produced clinically meaningful improvements in lower limb function in people with chronic gait deficits after stroke. Because only five users tested the new protocol, the results cannot be generalized to the whole population. As a contribution to the field, we developed and tested a protocol combining brain stimulation and ML-based stance phase training for individuals with chronic stance phase deficits after stroke. The protocol was feasible to administer; statistically and/or clinically significant improvements in gait function across an array of gait performance measures were observed with this relatively short treatment protocol.
- Published
- 2022
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23. Overcoming drug resistance, the natural way.
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Hutchings MI and Duncan KR
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- Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents therapeutic use, Drug Resistance, Humans, Colistin pharmacology, Colistin therapeutic use, Gram-Negative Bacterial Infections drug therapy
- Abstract
Colistin is an antibiotic of last resort for treating Gram-negative bacterial infections, but resistance is spreading rapidly. In a recent issue of Nature, Wang et al. use genome mining to identify and synthesize a natural variant that bypasses colistin resistance and offers new hope for tackling antimicrobial resistance., Competing Interests: Declaration of interests The authors declare no competing interests., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)
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- 2022
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24. The Natural Products Atlas 2.0: a database of microbially-derived natural products.
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van Santen JA, Poynton EF, Iskakova D, McMann E, Alsup TA, Clark TN, Fergusson CH, Fewer DP, Hughes AH, McCadden CA, Parra J, Soldatou S, Rudolf JD, Janssen EM, Duncan KR, and Linington RG
- Subjects
- Bacteria classification, Classification, Fungi classification, Humans, User-Computer Interface, Biological Products classification, Databases, Factual, Host Microbial Interactions genetics, Software
- Abstract
Within the natural products field there is an increasing emphasis on the study of compounds from microbial sources. This has been fuelled by interest in the central role that microorganisms play in mediating both interspecies interactions and host-microbe relationships. To support the study of natural products chemistry produced by microorganisms we released the Natural Products Atlas, a database of known microbial natural products structures, in 2019. This paper reports the release of a new version of the database which includes a full RESTful application programming interface (API), a new website framework, and an expanded database that includes 8128 new compounds, bringing the total to 32 552. In addition to these structural and content changes we have added full taxonomic descriptions for all microbial taxa and have added chemical ontology terms from both NP Classifier and ClassyFire. We have also performed manual curation to review all entries with incomplete configurational assignments and have integrated data from external resources, including CyanoMetDB. Finally, we have improved the user experience by updating the Overview dashboard and creating a dashboard for taxonomic origin. The database can be accessed via the new interactive website at https://www.npatlas.org., (© The Author(s) 2021. Published by Oxford University Press on behalf of Nucleic Acids Research.)
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- 2022
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25. Pseudonocardia abyssalis sp. nov. and Pseudonocardia oceani sp. nov., two novel actinomycetes isolated from the deep Southern Ocean.
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Parra J, Soldatou S, Rooney LM, and Duncan KR
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- Actinomyces, Bacterial Typing Techniques, Base Composition, DNA, Bacterial genetics, Fatty Acids chemistry, Oceans and Seas, Phylogeny, Pseudonocardia, RNA, Ribosomal, 16S genetics, Sequence Analysis, DNA, Vitamin K 2 analysis, Actinobacteria genetics
- Abstract
The actinomycetes strains KRD168
T and KRD185T were isolated from sediments collected from the deep Southern Ocean and, in this work, they are described as representing two novel species of the genus Pseudonocardia through a polyphasic approach. Despite sharing >99 % 16S rRNA gene sequence similarity with other members of the genus, comparative genomic analysis allowed species delimitation based on average nucleotide identity and digital DNA-DNA hybridization. The KRD168T genome is characterized by a size of 6.31 Mbp and a G+C content of 73.44 mol%, while the KRD185T genome has a size of 6.82 Mbp and a G+C content of 73.98 mol%. Both strains contain meso -diaminopimelic acid as the diagnostic diamino acid, glucose as the major whole-cell sugar, MK-8(H4 ) as a major menaquinone and iso -branched hexadecanoic acid as a major fatty acid. Biochemical and fatty acid analyses also revealed differences between these strains and their phylogenetic neighbours, supporting their status as distinct species. The names Pseudonocardia abyssalis sp. nov. (type strain KRD168T =DSM 111918T =NCIMB 15270T ) and Pseudonocardia oceani (type strain KRD185T =DSM 111919T =NCIMB 15269T ) are proposed.- Published
- 2021
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26. Ranking microbial metabolomic and genomic links in the NPLinker framework using complementary scoring functions.
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Hjörleifsson Eldjárn G, Ramsay A, van der Hooft JJJ, Duncan KR, Soldatou S, Rousu J, Daly R, Wandy J, and Rogers S
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- Biosynthetic Pathways genetics, Computational Biology, Data Mining, Databases, Factual, Databases, Genetic, Genome, Microbial, Microbiological Phenomena, Multigene Family, Regression Analysis, Genetics, Microbial statistics & numerical data, Genomics statistics & numerical data, Metabolomics statistics & numerical data, Software
- Abstract
Specialised metabolites from microbial sources are well-known for their wide range of biomedical applications, particularly as antibiotics. When mining paired genomic and metabolomic data sets for novel specialised metabolites, establishing links between Biosynthetic Gene Clusters (BGCs) and metabolites represents a promising way of finding such novel chemistry. However, due to the lack of detailed biosynthetic knowledge for the majority of predicted BGCs, and the large number of possible combinations, this is not a simple task. This problem is becoming ever more pressing with the increased availability of paired omics data sets. Current tools are not effective at identifying valid links automatically, and manual verification is a considerable bottleneck in natural product research. We demonstrate that using multiple link-scoring functions together makes it easier to prioritise true links relative to others. Based on standardising a commonly used score, we introduce a new, more effective score, and introduce a novel score using an Input-Output Kernel Regression approach. Finally, we present NPLinker, a software framework to link genomic and metabolomic data. Results are verified using publicly available data sets that include validated links., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2021
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27. A community resource for paired genomic and metabolomic data mining.
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Schorn MA, Verhoeven S, Ridder L, Huber F, Acharya DD, Aksenov AA, Aleti G, Moghaddam JA, Aron AT, Aziz S, Bauermeister A, Bauman KD, Baunach M, Beemelmanns C, Beman JM, Berlanga-Clavero MV, Blacutt AA, Bode HB, Boullie A, Brejnrod A, Bugni TS, Calteau A, Cao L, Carrión VJ, Castelo-Branco R, Chanana S, Chase AB, Chevrette MG, Costa-Lotufo LV, Crawford JM, Currie CR, Cuypers B, Dang T, de Rond T, Demko AM, Dittmann E, Du C, Drozd C, Dujardin JC, Dutton RJ, Edlund A, Fewer DP, Garg N, Gauglitz JM, Gentry EC, Gerwick L, Glukhov E, Gross H, Gugger M, Guillén Matus DG, Helfrich EJN, Hempel BF, Hur JS, Iorio M, Jensen PR, Kang KB, Kaysser L, Kelleher NL, Kim CS, Kim KH, Koester I, König GM, Leao T, Lee SR, Lee YY, Li X, Little JC, Maloney KN, Männle D, Martin H C, McAvoy AC, Metcalf WW, Mohimani H, Molina-Santiago C, Moore BS, Mullowney MW, Muskat M, Nothias LF, O'Neill EC, Parkinson EI, Petras D, Piel J, Pierce EC, Pires K, Reher R, Romero D, Roper MC, Rust M, Saad H, Saenz C, Sanchez LM, Sørensen SJ, Sosio M, Süssmuth RD, Sweeney D, Tahlan K, Thomson RJ, Tobias NJ, Trindade-Silva AE, van Wezel GP, Wang M, Weldon KC, Zhang F, Ziemert N, Duncan KR, Crüsemann M, Rogers S, Dorrestein PC, Medema MH, and van der Hooft JJJ
- Subjects
- Databases, Factual, Data Mining methods, Genomics methods, Metabolomics methods
- Published
- 2021
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28. Comparative Metabologenomics Analysis of Polar Actinomycetes.
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Soldatou S, Eldjárn GH, Ramsay A, van der Hooft JJJ, Hughes AH, Rogers S, and Duncan KR
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- Cold Climate, Drug Discovery, Genome, Bacterial, Actinobacteria metabolism, Genomics methods, Metabolomics methods
- Abstract
Biosynthetic and chemical datasets are the two major pillars for microbial drug discovery in the omics era. Despite the advancement of analysis tools and platforms for multi-strain metabolomics and genomics, linking these information sources remains a considerable bottleneck in strain prioritisation and natural product discovery. In this study, molecular networking of the 100 metabolite extracts derived from applying the OSMAC approach to 25 Polar bacterial strains, showed growth media specificity and potential chemical novelty was suggested. Moreover, the metabolite extracts were screened for antibacterial activity and promising selective bioactivity against drug-persistent pathogens such as Klebsiella pneumoniae and Acinetobacter baumannii was observed. Genome sequencing data were combined with metabolomics experiments in the recently developed computational approach, NPLinker, which was used to link BGC and molecular features to prioritise strains for further investigation based on biosynthetic and chemical information. Herein, we putatively identified the known metabolites ectoine and chrloramphenicol which, through NPLinker, were linked to their associated BGCs. The metabologenomics approach followed in this study can potentially be applied to any large microbial datasets for accelerating the discovery of new (bioactive) specialised metabolites.
- Published
- 2021
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29. Exploring the Chemical Space of Macro- and Micro-Algae Using Comparative Metabolomics.
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Hughes AH, Magot F, Tawfike AF, Rad-Menéndez C, Thomas N, Young LC, Stucchi L, Carettoni D, Stanley MS, Edrada-Ebel R, and Duncan KR
- Abstract
With more than 156,000 described species, eukaryotic algae (both macro- and micro-algae) are a rich source of biological diversity, however their chemical diversity remains largely unexplored. Specialised metabolites with promising biological activities have been widely reported for seaweeds, and more recently extracts from microalgae have exhibited activity in anticancer, antimicrobial, and antioxidant screens. However, we are still missing critical information on the distinction of chemical profiles between macro- and microalgae, as well as the chemical space these metabolites cover. This study has used an untargeted comparative metabolomics approach to explore the chemical diversity of seven seaweeds and 36 microalgal strains. A total of 1390 liquid chromatography-mass spectrometry (LC-MS) features were detected, representing small organic algal metabolites, with no overlap between the seaweeds and microalgae. An in-depth analysis of four Dunaliella tertiolecta strains shows that environmental factors may play a larger role than phylogeny when classifying their metabolomic profiles.
- Published
- 2021
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30. Linking genomics and metabolomics to chart specialized metabolic diversity.
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van der Hooft JJJ, Mohimani H, Bauermeister A, Dorrestein PC, Duncan KR, and Medema MH
- Subjects
- Biosynthetic Pathways, Computational Biology, Computer Simulation, Data Mining, Databases, Genetic, Drug Discovery, High-Throughput Screening Assays, Humans, Secondary Metabolism, Bacteria metabolism, Biological Products chemistry, Fungi metabolism, Genomics methods, Metabolomics methods, Plants metabolism
- Abstract
Microbial and plant specialized metabolites constitute an immense chemical diversity, and play key roles in mediating ecological interactions between organisms. Also referred to as natural products, they have been widely applied in medicine, agriculture, cosmetic and food industries. Traditionally, the main discovery strategies have centered around the use of activity-guided fractionation of metabolite extracts. Increasingly, omics data is being used to complement this, as it has the potential to reduce rediscovery rates, guide experimental work towards the most promising metabolites, and identify enzymatic pathways that enable their biosynthetic production. In recent years, genomic and metabolomic analyses of specialized metabolic diversity have been scaled up to study thousands of samples simultaneously. Here, we survey data analysis technologies that facilitate the effective exploration of large genomic and metabolomic datasets, and discuss various emerging strategies to integrate these two types of omics data in order to further accelerate discovery.
- Published
- 2020
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31. The Natural Products Atlas: An Open Access Knowledge Base for Microbial Natural Products Discovery.
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van Santen JA, Jacob G, Singh AL, Aniebok V, Balunas MJ, Bunsko D, Neto FC, Castaño-Espriu L, Chang C, Clark TN, Cleary Little JL, Delgadillo DA, Dorrestein PC, Duncan KR, Egan JM, Galey MM, Haeckl FPJ, Hua A, Hughes AH, Iskakova D, Khadilkar A, Lee JH, Lee S, LeGrow N, Liu DY, Macho JM, McCaughey CS, Medema MH, Neupane RP, O'Donnell TJ, Paula JS, Sanchez LM, Shaikh AF, Soldatou S, Terlouw BR, Tran TA, Valentine M, van der Hooft JJJ, Vo DA, Wang M, Wilson D, Zink KE, and Linington RG
- Abstract
Despite rapid evolution in the area of microbial natural products chemistry, there is currently no open access database containing all microbially produced natural product structures. Lack of availability of these data is preventing the implementation of new technologies in natural products science. Specifically, development of new computational strategies for compound characterization and identification are being hampered by the lack of a comprehensive database of known compounds against which to compare experimental data. The creation of an open access, community-maintained database of microbial natural product structures would enable the development of new technologies in natural products discovery and improve the interoperability of existing natural products data resources. However, these data are spread unevenly throughout the historical scientific literature, including both journal articles and international patents. These documents have no standard format, are often not digitized as machine readable text, and are not publicly available. Further, none of these documents have associated structure files (e.g., MOL, InChI, or SMILES), instead containing images of structures. This makes extraction and formatting of relevant natural products data a formidable challenge. Using a combination of manual curation and automated data mining approaches we have created a database of microbial natural products (The Natural Products Atlas, www.npatlas.org) that includes 24 594 compounds and contains referenced data for structure, compound names, source organisms, isolation references, total syntheses, and instances of structural reassignment. This database is accompanied by an interactive web portal that permits searching by structure, substructure, and physical properties. The Web site also provides mechanisms for visualizing natural products chemical space and dashboards for displaying author and discovery timeline data. These interactive tools offer a powerful knowledge base for natural products discovery with a central interface for structure and property-based searching and presents new viewpoints on structural diversity in natural products. The Natural Products Atlas has been developed under FAIR principles (Findable, Accessible, Interoperable, and Reusable) and is integrated with other emerging natural product databases, including the Minimum Information About a Biosynthetic Gene Cluster (MIBiG) repository, and the Global Natural Products Social Molecular Networking (GNPS) platform. It is designed as a community-supported resource to provide a central repository for known natural product structures from microorganisms and is the first comprehensive, open access resource of this type. It is expected that the Natural Products Atlas will enable the development of new natural products discovery modalities and accelerate the process of structural characterization for complex natural products libraries., Competing Interests: The authors declare the following competing financial interest(s): RGL and MW are consultants for Sirenas. PCD is on the scientific advisory board for Sirenas. MHM is a member of the Scientific Advisory Board of Hexagon Bio and co-founder of Design Pharmaceuticals. MW is a founder of Ometa Labs., (Copyright © 2019 American Chemical Society.)
- Published
- 2019
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32. Awakening ancient polar Actinobacteria : diversity, evolution and specialized metabolite potential.
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Millán-Aguiñaga N, Soldatou S, Brozio S, Munnoch JT, Howe J, Hoskisson PA, and Duncan KR
- Subjects
- Actinobacteria classification, Actinobacteria isolation & purification, Antarctic Regions, Arctic Regions, Biodiversity, Biological Products classification, Biological Products metabolism, DNA, Bacterial genetics, Evolution, Molecular, Geologic Sediments microbiology, Metagenomics, Microbiota genetics, Phylogeny, RNA, Ribosomal, 16S chemistry, Actinobacteria genetics, Actinobacteria metabolism
- Abstract
Polar and subpolar ecosystems are highly vulnerable to global climate change with consequences for biodiversity and community composition. Bacteria are directly impacted by future environmental change and it is therefore essential to have a better understanding of microbial communities in fluctuating ecosystems. Exploration of Polar environments, specifically sediments, represents an exciting opportunity to uncover bacterial and chemical diversity and link this to ecosystem and evolutionary parameters. In terms of specialized metabolite production, the bacterial order Actinomycetales , within the phylum Actinobacteria are unsurpassed, producing 10 000 specialized metabolites accounting for over 45 % of all bioactive microbial metabolites. A selective isolation approach focused on spore-forming Actinobacteria of 12 sediment cores from the Antarctic and sub-Arctic generated a culture collection of 50 strains. This consisted of 39 strains belonging to rare A ctinomycetales genera including Microbacterium, Rhodococcus and Pseudonocardia . This study used a combination of nanopore sequencing and molecular networking to explore the community composition, culturable bacterial diversity, evolutionary relatedness and specialized metabolite potential of these strains. Metagenomic analyses using MinION sequencing was able to detect the phylum Actinobacteria across polar sediment cores at an average of 13 % of the total bacterial reads. The resulting molecular network consisted of 1652 parent ions and the lack of known metabolite identification supports the argument that Polar bacteria are likely to produce previously unreported chemistry.
- Published
- 2019
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33. Glioma incidence and survival variations by county-level socioeconomic measures.
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Cote DJ, Ostrom QT, Gittleman H, Duncan KR, CreveCoeur TS, Kruchko C, Smith TR, Stampfer MJ, and Barnholtz-Sloan JS
- Subjects
- Adult, Black or African American statistics & numerical data, Asian statistics & numerical data, Brain pathology, Brain surgery, Brain Neoplasms pathology, Brain Neoplasms therapy, Chemoradiotherapy, Adjuvant, Datasets as Topic, Female, Glioma pathology, Glioma therapy, Hispanic or Latino statistics & numerical data, Humans, Incidence, Male, Native Hawaiian or Other Pacific Islander statistics & numerical data, Rural Population statistics & numerical data, SEER Program statistics & numerical data, Survival Analysis, Time Factors, United States epidemiology, Urban Population statistics & numerical data, White People statistics & numerical data, Young Adult, Brain Neoplasms epidemiology, Glioma epidemiology, Health Status Disparities, Socioeconomic Factors
- Abstract
Background: Multiple studies have reported higher rates of glioma in areas with higher socioeconomic status (SES) but to the authors' knowledge have not stratified by other factors, including race/ethnicity or urban versus rural location., Methods: The authors identified the average annual age-adjusted incidence rates and calculated hazard ratios for death for gliomas of various subtypes, stratified by a county-level index for SES, race/ethnicity, US region, and rural versus urban status., Results: Rates of glioma were highest in counties with higher SES (rate ratio, 1.18; 95% CI, 1.15-1.22 comparing the highest with the lowest quintiles [P < .001]). Stratified by race/ethnicity, higher rates in high SES counties persisted for white non-Hispanic individuals. Stratified by rural versus urban status, differences in incidence by SES were more pronounced among urban counties. Survival was higher for residents of high SES counties after adjustment for age and extent of surgical resection (hazard ratio, 0.82; 95% CI, 0.76-0.87 comparing the highest with the lowest quintile of SES [P < .001]). Survival was higher among white Hispanic, black, and Asian/Pacific Islander individuals compared with white non-Hispanic individuals, after adjustment for age, SES, and extent of surgical resection, and when restricted to those individuals with glioblastoma who received radiation and chemotherapy., Conclusions: The incidence of glioma was higher in US counties of high compared with low SES. These differences were most pronounced among white non-Hispanic individuals and white Hispanic individuals residing in urban areas. Better survival was observed in high SES counties, even when adjusting for extent of surgical resection, and when restricted to those who received radiation and chemotherapy for glioblastoma. Differences in incidence and survival were associated with SES and race, rather than rural versus urban status., (© 2019 American Cancer Society.)
- Published
- 2019
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34. Linking biosynthetic and chemical space to accelerate microbial secondary metabolite discovery.
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Soldatou S, Eldjarn GH, Huerta-Uribe A, Rogers S, and Duncan KR
- Subjects
- Molecular Structure, Multigene Family, Structure-Activity Relationship, Genomics methods, Metabolomics methods, Secondary Metabolism, Synthetic Biology methods
- Abstract
Secondary metabolites can be viewed as a chemical language, facilitating communication between microorganisms. From an ecological point of view, this metabolite exchange is in constant flux due to evolutionary and environmental pressures. From a biomedical perspective, the chemistry is unsurpassed for its antibiotic properties. Genome sequencing of microorganisms has revealed a large reservoir of Biosynthetic Gene Clusters (BGCs); however, linking these to the secondary metabolites they encode is currently a major bottleneck to chemical discovery. This linking of genes to metabolites with experimental validation will aid the elicitation of silent or cryptic (not expressed under normal laboratory conditions) BGCs. As a result, this will accelerate chemical dereplication, our understanding of gene transcription and provide a comprehensive resource for synthetic biology. This will ultimately provide an improved understanding of both the biosynthetic and chemical space. In recent years, integrating these complex metabolomic and genomic data sets has been achieved using a spectrum of manual and automated approaches. In this review, we cover examples of these approaches, while addressing current challenges and future directions in linking these data sets., (© FEMS 2019.)
- Published
- 2019
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35. Temperature Driven Changes in Benthic Bacterial Diversity Influences Biogeochemical Cycling in Coastal Sediments.
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Hicks N, Liu X, Gregory R, Kenny J, Lucaci A, Lenzi L, Paterson DM, and Duncan KR
- Abstract
Marine sediments are important sites for global biogeochemical cycling, mediated by macrofauna and microalgae. However, it is the microorganisms that drive these key processes. There is strong evidence that coastal benthic habitats will be affected by changing environmental variables (rising temperature, elevated CO
2 ), and research has generally focused on the impact on macrofaunal biodiversity and ecosystem services. Despite their importance, there is less understanding of how microbial community assemblages will respond to environmental changes. In this study, a manipulative mesocosm experiment was employed, using next-generation sequencing to assess changes in microbial communities under future environmental change scenarios. Illumina sequencing generated over 11 million 16S rRNA gene sequences (using a primer set biased toward bacteria) and revealed Bacteroidetes and Proteobacteria dominated the total bacterial community of sediment samples. In this study, the sequencing coverage and depth revealed clear changes in species abundance within some phyla. Bacterial community composition was correlated with simulated environmental conditions, and species level community composition was significantly influenced by the mean temperature of the environmental regime ( p = 0.002), but not by variation in CO2 or diurnal temperature variation. Species level changes with increasing mean temperature corresponded with changes in NH4 concentration, suggesting there is no functional redundancy in microbial communities for nitrogen cycling. Marine coastal biogeochemical cycling under future environmental conditions is likely to be driven by changes in nutrient availability as a direct result of microbial activity.- Published
- 2018
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36. Correction: Duncan, K.R., Suzuki, Y.J. Vitamin E Nicotinate. Antioxidants 2017, 6 , 20.
- Author
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Duncan KR and Suzuki YJ
- Abstract
In the original version of our article [1], three lines were omitted from the α-tocopherol and α-tocopheryl nicotinate structures in Figure 1 during the manuscript processing[...].
- Published
- 2018
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37. Subdiaphragmatic Vagotomy With Pyloroplasty Ameliorates the Obesity Caused by Genetic Deletion of the Melanocortin 4 Receptor in the Mouse.
- Author
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Dezfuli G, Gillis RA, Tatge JE, Duncan KR, Dretchen KL, Jackson PG, Verbalis JG, and Sahibzada N
- Abstract
Background/Objectives: We tested the hypothesis that abolishing vagal nerve activity will reverse the obesity phenotype of melanocortin 4 receptor knockout mice ( Mc4r
-/- ). Subjects/Methods: In two separate studies, we examined the efficacy of bilateral subdiaphragmatic vagotomy (SDV) with pyloroplasty in the prevention and treatment of obesity in Mc4r-/- mice. Results: In the first study, SDV prevented >20% increase in body weight (BW) associated with this genotype. This was correlated with a transient reduction in overall food intake (FI) in the preventative arm of the study. Initially, SDV mice had reduced weekly FI; however, FI normalized to that of controls and baseline FI within the 8-week study period. In the second study, the severe obesity that is characteristic of the adult Mc4r-/- genotype was significantly improved by SDV with a magnitude of 30% loss in excess BW over a 4-week period. Consistent with the first preventative study, within the treatment arm, SDV mice also demonstrated a transient reduction in FI relative to control and baseline levels that normalized over subsequent weeks. In addition to the accompanying loss in weight, mice subjected to SDV showed a decrease in respiratory exchange ratio (RER), and an increase in locomotor activity (LA). Analysis of the white fat-pad deposits of these mice showed that they were significantly less than the control groups. Conclusions: Altogether, our data demonstrates that SDV both prevents gain in BW and causes weight loss in severely obese Mc4r-/- mice. Moreover, it suggests that an important aspect of weight reduction for this type of monogenic obesity involves loss of signaling in vagal motor neurons.- Published
- 2018
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38. An Integrative Approach to Decipher the Chemical Antagonism between the Competing Endophytes Paraconiothyrium variabile and Bacillus subtilis.
- Author
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Vallet M, Vanbellingen QP, Fu T, Le Caer JP, Della-Negra S, Touboul D, Duncan KR, Nay B, Brunelle A, and Prado S
- Subjects
- Lipopeptides chemistry, Molecular Structure, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Bacillus subtilis chemistry, Cephalotaxus microbiology, Endophytes physiology
- Abstract
An integrative approach combining traditional natural products chemistry, molecular networking, and mass spectrometry imaging has been undertaken to decipher the molecular dialogue between the fungus Paraconiothyrium variabile and the bacterium Bacillus subtilis, which were isolated as endophytes from the conifer Cephalotaxus harringtonia and are characterized by a strong and mutual antibiosis. From this study, we highlight that bacterial surfactins and a fungal tetronic acid are involved in such competition and that the fungus is able to hydrolyze surfactins to fight against the bacterial partner.
- Published
- 2017
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39. Vitamin E Nicotinate.
- Author
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Duncan KR and Suzuki YJ
- Abstract
Vitamin E refers to a family of compounds that function as lipid-soluble antioxidants capable of preventing lipid peroxidation. Naturally occurring forms of vitamin E include tocopherols and tocotrienols. Vitamin E in dietary supplements and fortified foods is often an esterified form of α-tocopherol, the most common esters being acetate and succinate. The vitamin E esters are hydrolyzed and converted into free α-tocopherol prior to absorption in the intestinal tract. Because its functions are relevant to many chronic diseases, vitamin E has been extensively studied in respect to a variety of diseases as well as cosmetic applications. The forms of vitamin E most studied are natural α-tocopherol and the esters α-tocopheryl acetate and α-tocopheryl succinate. A small number of studies include or focus on another ester form, α-tocopheryl nicotinate, an ester of vitamin E and niacin. Some of these studies raise the possibility of differences in metabolism and in efficacy between vitamin E nicotinate and other forms of vitamin E. Recently, through metabolomics studies, we identified that α-tocopheryl nicotinate occurs endogenously in the heart and that its level is dramatically decreased in heart failure, indicating the possible biological importance of this vitamin E ester. Since knowledge about vitamin E nicotinate is not readily available in the literature, the purpose of this review is to summarize and evaluate published reports, specifically with respect to α-tocopheryl nicotinate with an emphasis on the differences from natural α-tocopherol or α-tocopheryl acetate.
- Published
- 2017
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40. Sharing and community curation of mass spectrometry data with Global Natural Products Social Molecular Networking.
- Author
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Wang M, Carver JJ, Phelan VV, Sanchez LM, Garg N, Peng Y, Nguyen DD, Watrous J, Kapono CA, Luzzatto-Knaan T, Porto C, Bouslimani A, Melnik AV, Meehan MJ, Liu WT, Crüsemann M, Boudreau PD, Esquenazi E, Sandoval-Calderón M, Kersten RD, Pace LA, Quinn RA, Duncan KR, Hsu CC, Floros DJ, Gavilan RG, Kleigrewe K, Northen T, Dutton RJ, Parrot D, Carlson EE, Aigle B, Michelsen CF, Jelsbak L, Sohlenkamp C, Pevzner P, Edlund A, McLean J, Piel J, Murphy BT, Gerwick L, Liaw CC, Yang YL, Humpf HU, Maansson M, Keyzers RA, Sims AC, Johnson AR, Sidebottom AM, Sedio BE, Klitgaard A, Larson CB, P CAB, Torres-Mendoza D, Gonzalez DJ, Silva DB, Marques LM, Demarque DP, Pociute E, O'Neill EC, Briand E, Helfrich EJN, Granatosky EA, Glukhov E, Ryffel F, Houson H, Mohimani H, Kharbush JJ, Zeng Y, Vorholt JA, Kurita KL, Charusanti P, McPhail KL, Nielsen KF, Vuong L, Elfeki M, Traxler MF, Engene N, Koyama N, Vining OB, Baric R, Silva RR, Mascuch SJ, Tomasi S, Jenkins S, Macherla V, Hoffman T, Agarwal V, Williams PG, Dai J, Neupane R, Gurr J, Rodríguez AMC, Lamsa A, Zhang C, Dorrestein K, Duggan BM, Almaliti J, Allard PM, Phapale P, Nothias LF, Alexandrov T, Litaudon M, Wolfender JL, Kyle JE, Metz TO, Peryea T, Nguyen DT, VanLeer D, Shinn P, Jadhav A, Müller R, Waters KM, Shi W, Liu X, Zhang L, Knight R, Jensen PR, Palsson BO, Pogliano K, Linington RG, Gutiérrez M, Lopes NP, Gerwick WH, Moore BS, Dorrestein PC, and Bandeira N
- Subjects
- Database Management Systems, Information Storage and Retrieval methods, Internationality, Biological Products chemistry, Biological Products classification, Data Curation methods, Databases, Chemical, Information Dissemination methods, Mass Spectrometry statistics & numerical data
- Abstract
The potential of the diverse chemistries present in natural products (NP) for biotechnology and medicine remains untapped because NP databases are not searchable with raw data and the NP community has no way to share data other than in published papers. Although mass spectrometry (MS) techniques are well-suited to high-throughput characterization of NP, there is a pressing need for an infrastructure to enable sharing and curation of data. We present Global Natural Products Social Molecular Networking (GNPS; http://gnps.ucsd.edu), an open-access knowledge base for community-wide organization and sharing of raw, processed or identified tandem mass (MS/MS) spectrometry data. In GNPS, crowdsourced curation of freely available community-wide reference MS libraries will underpin improved annotations. Data-driven social-networking should facilitate identification of spectra and foster collaborations. We also introduce the concept of 'living data' through continuous reanalysis of deposited data.
- Published
- 2016
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41. Competitive strategies differentiate closely related species of marine actinobacteria.
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Patin NV, Duncan KR, Dorrestein PC, and Jensen PR
- Subjects
- Genomics, Geologic Sediments microbiology, Micromonosporaceae classification, Micromonosporaceae genetics, Micromonosporaceae physiology, Seawater microbiology
- Abstract
Although competition, niche partitioning, and spatial isolation have been used to describe the ecology and evolution of macro-organisms, it is less clear to what extent these principles account for the extraordinary levels of bacterial diversity observed in nature. Ecological interactions among bacteria are particularly challenging to address due to methodological limitations and uncertainties over how to recognize fundamental units of diversity and link them to the functional traits and evolutionary processes that led to their divergence. Here we show that two closely related marine actinomycete species can be differentiated based on competitive strategies. Using a direct challenge assay to investigate inhibitory interactions with members of the bacterial community, we observed a temporal difference in the onset of inhibition. The majority of inhibitory activity exhibited by Salinispora arenicola occurred early in its growth cycle and was linked to antibiotic production. In contrast, most inhibition by Salinispora tropica occurred later in the growth cycle and was more commonly linked to nutrient depletion or other sources. Comparative genomics support these differences, with S. arenicola containing nearly twice the number of secondary metabolite biosynthetic gene clusters as S. tropica, indicating a greater potential for secondary metabolite production. In contrast, S. tropica is enriched in gene clusters associated with the acquisition of growth-limiting nutrients such as iron. Coupled with differences in growth rates, the results reveal that S. arenicola uses interference competition at the expense of growth, whereas S. tropica preferentially employs a strategy of exploitation competition. The results support the ecological divergence of two co-occurring and closely related species of marine bacteria by providing evidence they have evolved fundamentally different strategies to compete in marine sediments.
- Published
- 2016
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42. Using Molecular Networking for Microbial Secondary Metabolite Bioprospecting.
- Author
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Purves K, Macintyre L, Brennan D, Hreggviðsson GÓ, Kuttner E, Ásgeirsdóttir ME, Young LC, Green DH, Edrada-Ebel R, and Duncan KR
- Abstract
The oceans represent an understudied resource for the isolation of bacteria with the potential to produce novel secondary metabolites. In particular, actinomyces are well known to produce chemically diverse metabolites with a wide range of biological activities. This study characterised spore-forming bacteria from both Scottish and Antarctic sediments to assess the influence of isolation location on secondary metabolite production. Due to the selective isolation method used, all 85 isolates belonged to the phyla Firmicutes and Actinobacteria, with the majority of isolates belonging to the genera Bacillus and Streptomyces. Based on morphology, thirty-eight isolates were chosen for chemical investigation. Molecular networking based on chemical profiles (HR-MS/MS) of fermentation extracts was used to compare complex metabolite extracts. The results revealed 40% and 42% of parent ions were produced by Antarctic and Scottish isolated bacteria, respectively, and only 8% of networked metabolites were shared between these locations, implying a high degree of biogeographic influence upon secondary metabolite production. The resulting molecular network contained over 3500 parent ions with a mass range of m/z 149-2558 illustrating the wealth of metabolites produced. Furthermore, seven fermentation extracts showed bioactivity against epithelial colon adenocarcinoma cells, demonstrating the potential for the discovery of novel bioactive compounds from these understudied locations.
- Published
- 2016
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43. Molecular networking and pattern-based genome mining improves discovery of biosynthetic gene clusters and their products from Salinispora species.
- Author
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Duncan KR, Crüsemann M, Lechner A, Sarkar A, Li J, Ziemert N, Wang M, Bandeira N, Moore BS, Dorrestein PC, and Jensen PR
- Subjects
- Chromatography, High Pressure Liquid, Depsipeptides biosynthesis, Metabolome, Micromonosporaceae metabolism, Multigene Family, Peptide Synthases genetics, Peptide Synthases metabolism, Tandem Mass Spectrometry, Genome, Bacterial, Genomics, Metabolic Networks and Pathways physiology, Micromonosporaceae genetics
- Abstract
Genome sequencing has revealed that bacteria contain many more biosynthetic gene clusters than predicted based on the number of secondary metabolites discovered to date. While this biosynthetic reservoir has fostered interest in new tools for natural product discovery, there remains a gap between gene cluster detection and compound discovery. Here we apply molecular networking and the new concept of pattern-based genome mining to 35 Salinispora strains, including 30 for which draft genome sequences were either available or obtained for this study. The results provide a method to simultaneously compare large numbers of complex microbial extracts, which facilitated the identification of media components, known compounds and their derivatives, and new compounds that could be prioritized for structure elucidation. These efforts revealed considerable metabolite diversity and led to several molecular family-gene cluster pairings, of which the quinomycin-type depsipeptide retimycin A was characterized and linked to gene cluster NRPS40 using pattern-based bioinformatic approaches., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
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44. Exploring the diversity and metabolic potential of actinomycetes from temperate marine sediments from Newfoundland, Canada.
- Author
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Duncan KR, Haltli B, Gill KA, Correa H, Berrué F, and Kerr RG
- Subjects
- Actinobacteria genetics, Actinomycetales chemistry, Actinomycetales genetics, Actinomycetales isolation & purification, Anti-Infective Agents pharmacology, Antineoplastic Agents pharmacology, Cell Line, Tumor, Culture Media chemistry, DNA, Bacterial genetics, Drug Resistance, Microbial, Fermentation, Humans, Metabolomics, Newfoundland and Labrador, Peptides pharmacology, Phylogeny, RNA, Ribosomal, 16S genetics, Sequence Analysis, DNA, Streptomyces genetics, Streptomyces isolation & purification, Actinobacteria chemistry, Actinobacteria isolation & purification, Geologic Sediments microbiology, Streptomyces chemistry
- Abstract
Marine sediments from Newfoundland, Canada were explored for biotechnologically promising Actinobacteria using culture-independent and culture-dependent approaches. Culture-independent pyrosequencing analyses uncovered significant actinobacterial diversity (H'-2.45 to 3.76), although the taxonomic diversity of biotechnologically important actinomycetes could not be fully elucidated due to limited sampling depth. Assessment of culturable actinomycete diversity resulted in the isolation of 360 actinomycetes representing 59 operational taxonomic units, the majority of which (94 %) were Streptomyces. The biotechnological potential of actinomycetes from NL sediments was assessed by bioactivity and metabolomics-based screening of 32 representative isolates. Bioactivity was exhibited by 41 % of isolates, while 11 % exhibited unique chemical signatures in metabolomics screening. Chemical analysis of two isolates resulted in the isolation of the cytotoxic metabolite 1-isopentadecanoyl-3β-D-glucopyranosyl-X-glycerol from Actinoalloteichus sp. 2L868 and sungsanpin from Streptomyces sp. 8LB7. These results demonstrate the potential for the discovery of novel bioactive metabolites from actinomycetes isolated from Atlantic Canadian marine sediments.
- Published
- 2015
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45. A comparison of fetal organ measurements by echo-planar magnetic resonance imaging and ultrasound.
- Author
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Duncan KR, Issa B, Moore R, Baker PN, Johnson IR, and Gowland PA
- Subjects
- Abdomen embryology, Brain embryology, Cross-Sectional Studies, Female, Fetal Weight, Head embryology, Humans, Liver embryology, Lung embryology, Organ Size physiology, Pregnancy, Sensitivity and Specificity, Ultrasonography, Prenatal standards, Echo-Planar Imaging standards, Fetal Growth Retardation diagnosis, Prenatal Diagnosis standards
- Abstract
Objectives: To compare fetal organ size measured using echo-planar magnetic resonance imaging and 2D ultrasound. To determine the relative accuracy with which each technique can predict fetal growth restriction., Design: A cross sectional, observational study comparing two different measurement techniques against a gold standard, in a normal clinical population and an abnormal population., Setting and Population: Seventy-four pregnant women (33 who were ultimately found to be normal and 37 with fetal growth restricted fetuses) were recruited from the City Hospital Nottingham UK to be scanned once (at various gestations)., Methods: Each fetus had a standard ultrasound biometry assessment followed by magnetic resonance imaging measurement of organ volumes., Main Outcome Measures: For each measurement for both techniques, the normal population was plotted with 90% confidence intervals. Fetal growth restricted subjects were compared with the normal population using this plot; 2 x 2 tables were created for each measurement. This was used to calculate the relative sensitivities and positive predictive value of the different measurements. A Bland-Altman plot was used to compare the ultrasound and magnetic resonance imaging measurements of fetal weight., Results: Brain sparing was seen in ultrasonic head circumference measurements, but an overall reduction in fetal growth restriction brain volume was apparent using magnetic resonance imaging at late gestations. Across the whole range of gestational ages, ultrasound assessment of fetal weight was the best predictor of fetal growth restriction., Conclusion: Ultrasound fetal weight assessment appears to identify more fetuses with fetal growth restriction than abdominal circumference. The brain sparing apparent in ultrasonic head circumference measurements of fetuses with fetal growth restriction masks a reduction in brain volume observed with magnetic resonance imaging.
- Published
- 2005
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46. Older adult performance on an altered version of the SSI test.
- Author
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Aarts NL, Adams EM, and Duncan KR
- Subjects
- Aged, Analysis of Variance, Audiometry, Speech, Female, Humans, Male, Middle Aged, Severity of Illness Index, Time Factors, Aging physiology, Speech Perception physiology
- Abstract
The Synthetic Sentence Identification (SSI) test has been used extensively in investigations of reduced speech understanding skills in older adults. In this study the SSI test was altered by adding noise to the competing message and by administering practice lists and equivalent test lists, as well as versions of the test that have 4- and 12-s interstimulus intervals (ISIs), along with the standard 8-s ISI. The purpose was to determine the effect of these alterations on performance in a group of older adults with average pure-tone average 2 values less than 33 dB HL. Performance changed as a function of the ISI, with less rollover occurring for the 4-s ISI condition than the other 2 ISIs.
- Published
- 2003
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47. Serial aggressive platelet transfusion for fetal alloimmune thrombocytopenia: platelet dynamics and perinatal outcome.
- Author
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Overton TG, Duncan KR, Jolly M, Letsky E, and Fisk NM
- Subjects
- Blood Specimen Collection methods, Female, Fetal Death, Gestational Age, Hepatic Veins embryology, Humans, Platelet Count, Pregnancy, Retrospective Studies, Thrombocytopenia mortality, Umbilical Veins, Fetal Diseases therapy, Isoantibodies immunology, Platelet Transfusion, Thrombocytopenia immunology, Thrombocytopenia therapy
- Abstract
Objectives: Our purpose was to describe the fetal loss rate and platelet dynamics in fetal alloimmune thrombocytopenia managed by serial platelet transfusions., Methods: Retrospective analysis over 10 years of consecutive pregnancies affected by fetal alloimmune thrombocytopenia requiring in utero platelet transfusions., Results: There were 2 perinatal losses in 12 pregnancies managed by 84 platelet transfusions. One was obviously procedure related from exsanguination despite platelet transfusion. The attributable procedure related fetal loss rate was 1.2% per procedure but 8.3% per pregnancy. The median rate of fall in fetal platelet count per day after transfusion was lower at the placental cord insertion (n = 54) 40.5 x 10(9)/L (range, 5.4-96.1 x 10(9)/L) compared with that at the intrahepatic vein (n = 30) 50.9 x 10(9)/L,(range, 29.5-91 x 10(9)/L) (P = .0009)., Conclusion: Pooling our results with those previously published yields a cumulative risk of serial weekly transfusions of approximately 6% per pregnancy, indicating the need for development of less invasive approaches.
- Published
- 2002
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48. Multilevel modeling of fetal and placental growth using echo-planar magnetic resonance imaging.
- Author
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Duncan KR, Sahota DS, Gowland PA, Moore R, Chang A, Baker PN, and Johnson IR
- Subjects
- Adult, Brain embryology, Echo-Planar Imaging, Female, Humans, Image Processing, Computer-Assisted, Infant, Newborn, Liver embryology, Longitudinal Studies, Male, Models, Statistical, Placenta physiology, Pregnancy, Prospective Studies, Embryonic and Fetal Development physiology, Placentation
- Abstract
Objective: To quantify longitudinal increases in fetal, fetal liver, and fetal brain volume using echo-planar magnetic resonance imaging and to quantify the results using appropriate statistical modeling., Methods: Fifty-six singleton fetuses were studied using echo-planar (snap-shot) magnetic resonance imaging, between 19 weeks and term. They were assessed at a variety of different gestations and on a different number of occasions, thereby requiring multilevel statistical modeling to analyze the pattern of fetal growth., Results: Fetal volume varied according to the following equation: square root (radical) [fetal volume]=-37.71+2.17 x gestational age (GA)-0.004 x GA(2). The equation for fetal liver volume was radical[fetal liver volume]=9.47+0.56 x GA-0.02 x GA(2), for fetal brain volume was radical[fetal brain volume]=15.50+0.69 x GA-0.014 x GA(2), and for placental volume radical[placental volume]=28.54+0.95 x GA-0.039 x GA(2), where GA is the gestational age in weeks -30., Conclusion: The assessment of fetal, fetal organ, and placental volume was feasible using echo-planar magnetic resonance imaging from 20 weeks to term. Multilevel statistical modeling can be applied to analyze sets of data with different measurements on different occasions. This information is useful clinically to assess abnormal fetal growth.
- Published
- 2001
- Full Text
- View/download PDF
49. Fetal and placental volumetric and functional analysis using echo-planar imaging.
- Author
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Duncan KR
- Subjects
- Embryonic and Fetal Development physiology, Female, Humans, Pregnancy, Prenatal Diagnosis methods, Sensitivity and Specificity, Echo-Planar Imaging methods, Fetal Diseases diagnosis, Fetus anatomy & histology, Placenta anatomy & histology, Placenta pathology
- Abstract
Recent and past work using echo-planar imaging (EPI) in pregnancy has allowed important anatomic and physiological information to be obtained, giving advantages over conventional radiological methods such as ultrasound. EPI is a quick, convenient method of measuring organ volumes. The volumetric estimates throughout gestation correlate well with known fetal weight at these gestations. Relaxation time measurements also can be made in the placenta and lungs. By combining the changes in relaxation and volume with gestation in the future, it may be possible to develop an "index of maturity." This could be used to accurately reflect lung maturation. T1 and T2 parameters in the placenta decreased with gestational age and with abnormal placentation. EPI can be used to assess perfusion in the placenta and flow in the uterine arteries because of its rapid acquisition times. These techniques have been applied to assess perfusion within the fetal brain.
- Published
- 2001
- Full Text
- View/download PDF
50. Antenatal factors at diagnosis that predict outcome in twin-twin transfusion syndrome.
- Author
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Taylor MJ, Denbow ML, Duncan KR, Overton TG, and Fisk NM
- Subjects
- Arteries abnormalities, Arteries embryology, Diastole, Female, Fetofetal Transfusion complications, Fetofetal Transfusion mortality, Humans, Pregnancy, Prognosis, Pulsatile Flow, Regional Blood Flow, Retrospective Studies, Survival Analysis, Treatment Outcome, Umbilical Arteries physiopathology, Veins embryology, Fetofetal Transfusion physiopathology, Prenatal Diagnosis
- Abstract
Objective: We sought to identify clinical factors at diagnosis that predict outcome in twin-twin transfusion syndrome., Study Design: In this retrospective series 23 patients with twin-twin transfusion syndrome were seen in a tertiary referral fetal medicine center over a 3-year period. Ten antenatal factors were assessed to determine their ability to predict outcome by use of ordered logistic regression. These factors were the following: (1) absent or reversed end-diastolic flow in the umbilical artery, nonvisible bladder, anhydramnios, and estimated fetal weight of <3rd percentile in the donor; (2) pulsatile umbilical vein, either absent or reversed end-diastolic flow in the ductus venosus, or both, and tricuspid-mitral valve regurgitation in the recipient; and (3) gestational age at presentation, estimated fetal weight discordancy, absent arterioarterial anastomosis, and spontaneous rupture of the membranes or cervical change as pregnancy factors. Management comprised serial amnioreduction (n = 10), selective feticide (n = 5; 4 also had amnioreduction), septostomy (n = 4; 1 also had amnioreduction), and delivery (n = 2). Two patients miscarried before treatment., Results: The chance of survival of both twins fell and double deaths increased linearly with increasing number of adverse factors (P =.026). A low chance of survival was independently associated with absent or reversed end-diastolic flow in the donor umbilical artery (P =.02) and with a pulsatile umbilical vein or absent or reversed end-diastolic flow in the ductus venosus (P =.03) of the recipient. The probability of at least one twin surviving was only 33% if there was absent or reversed end-diastolic flow in the donor umbilical artery or 37% when abnormal venous recordings were seen in the recipient. An arterioarterial anastomosis detected at diagnosis also influenced prognosis, with all twins surviving when an arterioarterial anastomosis was identified (P =.04)., Conclusions: Three factors identified at diagnosis independently predict poor survival in twin-twin transfusion syndrome-absent or reversed end-diastolic flow in the donor umbilical artery, abnormal pulsatility of the venous system in the recipient, and absence of an arterioarterial anastomosis. These may have a role in the counseling of parents and in selecting the appropriate treatment strategy.
- Published
- 2000
- Full Text
- View/download PDF
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