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Affiliation(s)
- Jaclyn Carberry
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
- Cardiology, Golden Jubilee National Hospital, Clydebank, UK
| | - Daniel Ang
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
- Cardiology, Golden Jubilee National Hospital, Clydebank, UK
| | - Colin Berry
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
- Cardiology, Golden Jubilee National Hospital, Clydebank, UK
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Suda A, Takahashi J, Schwidder M, Ong P, Ang D, Berry C, Camici PG, Crea F, Carlos Kaski J, Pepine C, Rimoldi O, Sechtem U, Yasuda S, Beltrame JF, Noel Bairey Merz C, Shimokawa H. Prognostic association of plasma NT-proBNP levels in patients with microvascular angina -A report from the international cohort study by COVADIS. Int J Cardiol Heart Vasc 2022; 43:101139. [PMID: 36338319 PMCID: PMC9626381 DOI: 10.1016/j.ijcha.2022.101139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/27/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022]
Abstract
BackgroudThe aim of this study was to assess the prognostic association of plasma levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) with clinical outcomes of patients with microvascular angina (MVA). Methods In this international prospective cohort study of MVA by the Coronary Vasomotor Disorders International Study (COVADIS) group, we examined the association between plasma NT-proBNP levels and the incidence of major adverse cardiovascular events (MACE), including cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization due to heart failure or unstable angina. Results We examined a total of 226 MVA patients (M/F 66/160, 61.9 ± 10.2 [SD] yrs.) with both plasma NT-proBNP levels and echocardiography data available at the time of enrolment. The median level of NT-proBNP level was 94 pg/ml, while mean left ventricular ejection fraction was 69.2 ± 10.9 % and E/e' 10.7 ± 5.2. During follow-up period of a median of 365 days (IQR 365-482), 29 MACEs occurred. Receiver-operating characteristics curve analysis identified plasma NT-proBNP level of 78 pg/ml as the optimal cut-off value. Multivariable logistic regression analysis revealed that plasma NT-proBNP level ≥ 78 pg/ml significantly correlated with the incidence of MACE (odds ratio (OR) [95 % confidence interval (CI)] 3.11[1.14-8.49], P = 0.001). Accordingly, Kaplan-Meier survival analysis showed a significantly worse prognosis in the group with NT-proBNP ≥ 78 (log-rank test, P < 0.03). Finally, a significant positive correlation was observed between plasma NT-proBNP levels and E/e' (R = 0.445, P < 0.0001). Conclusions These results indicate that plasma NT-proBNP levels may represent a novel prognostic biomarker for MVA patients.
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Affiliation(s)
- Akira Suda
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Jun Takahashi
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Maike Schwidder
- Department of Cardiology and Angiology, Robert-Bosch-Krankenhaus, Stuttgart, Germany
| | - Peter Ong
- Department of Cardiology and Angiology, Robert-Bosch-Krankenhaus, Stuttgart, Germany
| | - Daniel Ang
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Colin Berry
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Paolo G. Camici
- Vita Salute University and San Raffaele Hospital, Milan, Italy
| | - Filippo Crea
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Juan Carlos Kaski
- Cardiovascular and Cell Sciences Res Institute, St George’s, University of London, UK
| | - Carl Pepine
- Division of Cardiovascular Medicine, University of Florida, College of Medicine, Gainesville, FL, USA
| | - Ornella Rimoldi
- Institute of Molecular Bioimaging and Physiology, Consiglio Nazionale delle Ricerche, Segrate, Italy
| | - Udo Sechtem
- Department of Cardiology and Angiology, Robert-Bosch-Krankenhaus, Stuttgart, Germany
| | - Satoshi Yasuda
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - John F. Beltrame
- The Discipline of Medicine, University of Adelaide, Basil Hetzel Institute, Central Adelaide Local Health Network, Adelaide, South Australia, Australia
| | - C. Noel Bairey Merz
- Barbra Streisand Women's Heart Center, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Hiroaki Shimokawa
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
- International University of Health and Welfare, Narita, Japan
| | - on behalf of the Coronary Vasomotor Disorders International Study COVADIS Group
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
- Department of Cardiology and Angiology, Robert-Bosch-Krankenhaus, Stuttgart, Germany
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
- Vita Salute University and San Raffaele Hospital, Milan, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy
- Cardiovascular and Cell Sciences Res Institute, St George’s, University of London, UK
- Division of Cardiovascular Medicine, University of Florida, College of Medicine, Gainesville, FL, USA
- Institute of Molecular Bioimaging and Physiology, Consiglio Nazionale delle Ricerche, Segrate, Italy
- The Discipline of Medicine, University of Adelaide, Basil Hetzel Institute, Central Adelaide Local Health Network, Adelaide, South Australia, Australia
- Barbra Streisand Women's Heart Center, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- International University of Health and Welfare, Narita, Japan
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Shimokawa H, Suda A, Takahashi J, Ong P, Ang D, Berry C, Camici P, Crea F, Kaski J, Pepine C, Rimoldi O, Sechtem U, Yasuda S, Beltrame J, Merz C. Prognostic impact of plasma level of NT-pro BNP in patients with microvascular angina – a report from the international cohort study by COVADIS. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.1131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Aims
Although the importance of microvascular angina (MVA) has been emerging, prognostic biomarkers for MVA remain to be developed. We thus aimed to examine whether plasma level of N-terminal prohormone of brain natriuretic peptide (NT-pro BNP) could predict the prognosis of MVA patients.
Methods
In the international prospective cohort study of MVA patients by the Coronary Vasomotor Disorders International Study (COVADIS) group, we evaluated the association between plasma level of NT-pro BNP and the incidence of major adverse cardiovascular events (MACE), including cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization due to heart failure or unstable angina.
Results
We examined a total of 226 MVA patients (M/F 66/160, 61.9±10.2 [SD] years) with both plasma NT-pro BNP levels and echocardiographic data in the COVADIS study. Plasma NT-pro BNP level was elevated (median 94 pg/ml, IQR 45–190) while mean LVEF (69.2±10.9%) and E/e' (10.7±5.2) were almost normal. During follow-up period of a median of 365 days (IQR 365–482), 29 MACEs occurred. ROC curve analysis identified plasma NT-pro BNP level of 78 pg/ml as the optimal cut-off value. Multivariable logistic regression analysis revealed that plasma NT-pro BNP level ≥78 pg/ml significantly correlated with the incidence of MACE (odds ratio (OR) [95% confidence interval (CI)] 3.11 [1.14–8.49], P=0.03). When divided into 2 groups by NT-pro BNP 78 pg/ml, the Kaplan-Meier survival analysis showed a significantly worse prognosis in the group with NT-pro BNP ≥78 (log lank, P=0.03) (Figure).
Conclusions
These results indicate that plasma NT-pro BNP level is a novel prognostic biomarker for MVA patients.
Funding Acknowledgement
Type of funding sources: Foundation. Main funding source(s): Japan Heart Foundation
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Affiliation(s)
- H Shimokawa
- Tohoku University Graduate School of Medicine , Sendai , Japan
| | - A Suda
- Tohoku University Graduate School of Medicine , Sendai , Japan
| | - J Takahashi
- Tohoku University Graduate School of Medicine , Sendai , Japan
| | - P Ong
- Robert Bosch Hospital , Stuttgart , Germany
| | - D Ang
- University of Glasgow , Glasgow , United Kingdom
| | - C Berry
- University of Glasgow , Glasgow , United Kingdom
| | - P Camici
- University Vita-Salute San Raffaele , Milan , Italy
| | - F Crea
- Fondazione Policlinico Universitario Gemelli IRCCS, Catholic University , Rome , Italy
| | - J Kaski
- St George's University of London , London , United Kingdom
| | - C Pepine
- University of Florida , Gainesville , United States of America
| | - O Rimoldi
- University Vita-Salute San Raffaele , Milan , Italy
| | - U Sechtem
- Robert Bosch Hospital , Stuttgart , Germany
| | - S Yasuda
- Tohoku University Graduate School of Medicine , Sendai , Japan
| | - J Beltrame
- University of Adelaide , Adelaide , Australia
| | - C Merz
- Cedars-Sinai Medical Center , Los Angeles , United States of America
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Affiliation(s)
- Daniel Ang
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow G12 8TA, UK.,Department of Cardiology, Golden Jubilee National Hospital, Clydebank G81 4DY, UK
| | - Colin Berry
- British Heart Foundation Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow G12 8TA, UK.,Department of Cardiology, Golden Jubilee National Hospital, Clydebank G81 4DY, UK
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McCartney P, Ang D, Mangion K, Maznyczka A, McEntegart M, Eteiba H, Greenwood J, Muir D, Chowdhary S, Appleby C, Cotton J, Wragg A, Curzen N, Oldroyd K, Good R, Robertson K, Ford T, Collison D, Gillespie L, Petrie M, Weir R, Macfarlane P, Ford I, McConnachie A, Berry C. TCT-189 Effect of Low-Dose Intracoronary Alteplase on Global Circumferential Strain: Myocardial Strain Cardiovascular Magnetic Resonance Substudy of the T-TIME Trial. J Am Coll Cardiol 2021. [DOI: 10.1016/j.jacc.2021.09.1042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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McCartney P, Ang D, Mangion K, McEntegart M, Greenwood JP, Muir D, Chowdhary S, Appleby C, Cotton JM, Eteiba H, Oldroyd KG, Maznyczka A, Radjenovic A, McConnachie A, Berry C. Effect of low dose intracoronary alteplase on global circumferential strain (myocardial strain CMR substudy from the T-TIME trial). Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.1426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Microvascular obstruction affects half of patients with ST-segment elevation myocardial infarction (STEMI) and confers an adverse prognosis. Feature-tracking (FT) cardiac magnetic resonance (CMR) allows myocardial strain assessment from standard cine images without the need for specialist sequences. Myocardial strain reflects both systolic and diastolic function allowing the assessment of both global and regional myocardial deformation. Strain recovery is impaired in patients with microvascular obstruction. There is growing evidence to suggest that global circumferential strain may offer incremental value beyond traditional CMR endpoints.
Purpose
We aimed to determine whether a therapeutic strategy involving low-dose intracoronary alteplase improves global circumferential strain in STEMI.
Methods
Between March 17, 2016, and December 21, 2017, 440 patients presenting at 11 hospitals in the United Kingdom within 6 hours of STEMI were randomised in a 1:1:1 dose-ranging trial design. Participants were randomly assigned to treatment with placebo (n=151), alteplase 10mg (n=144), or alteplase 20mg (n=145). The primary outcome was the amount of microvascular obstruction (%left ventricular mass) quantified by CMR at 2–7 days. Global circumferential strain was a prespecified secondary endpoint measured at 2–7 days and 3 months. Troponin T AUC was measured at 0, 2, and 24 hours post reperfusion. Patients were followed up to 1 year with all events adjudicated by an independent committee.
Results
Among the 440 patients who were randomised (mean age 60.5 years; 85% male), the primary endpoint was achieved in 396 (90%), all patients were followed up to 1 year for clinical events. The amount (mean, standard deviation) of microvascular obstruction was not different between the groups (2.3% vs. 2.6% vs. 3.5% left ventricular mass); p=0.28. Global circumferential strain was worse in patients receiving alteplase. −23.1% (placebo) vs −20.6 (10mg alteplase) vs −22.0% (20mg alteplase); mean difference for both doses combined vs placebo: 1.8% (95% CI 0.5, 3.2), p=0.009. There were no differences between groups in the other CMR endpoints including LV ejection fraction (LVEF). The area-under-the-curve for troponin T measured in 317 (72%) patients was increased in both treatment groups compared to placebo, mean difference 1.53 (95% CI: 1.16, 2.01), p=0.002. There were no differences in MACE at 1 year; placebo n=16 (10.6%), 10mg alteplase n=22 (15.3%), 20mg alteplase group n=15 (10.3%).
Conclusion
In patients presenting within 6 hours of STEMI, low-dose intracoronary alteplase compared with placebo did not reduce microvascular obstruction. There was a reduction in global circumferential strain and an increase in Troponin T AUC supporting an increase in myocardial injury early after reperfusion in patients receiving alteplase. There was no differences in MACE at one year suggesting no long-term clinical sequelae.
Funding Acknowledgement
Type of funding sources: Other. Main funding source(s): T-TIME was supported by grant 12/170/4 from the Efficacy and Mechanism Evaluation (EME) programme of the National Institute for Health Research (NIHR-EME). Boehringer-Ingelheim U.K. Ltd. provided the study drugs (alteplase 10mg, 20mg), matched placebo, and sterile water for injection. Study recruitment flowchartTable- Study endpoints
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Affiliation(s)
- P McCartney
- Golden Jubilee national hospital, Glasgow, United Kingdom
| | - D Ang
- Golden Jubilee national hospital, Glasgow, United Kingdom
| | - K Mangion
- University of Glasgow, ICAMS, Glasgow, United Kingdom
| | - M McEntegart
- Golden Jubilee national hospital, Glasgow, United Kingdom
| | | | - D Muir
- James Cook University Hospital, Middlesbrough, United Kingdom
| | - S Chowdhary
- Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - C Appleby
- Cardiothoracic Centre Trust of Liverpool, Liverpool, United Kingdom
| | - J M Cotton
- New Cross Hospital, Wolverhampton, United Kingdom
| | - H Eteiba
- Golden Jubilee national hospital, Glasgow, United Kingdom
| | - K G Oldroyd
- Golden Jubilee national hospital, Glasgow, United Kingdom
| | - A Maznyczka
- Golden Jubilee national hospital, Glasgow, United Kingdom
| | - A Radjenovic
- University of Glasgow, ICAMS, Glasgow, United Kingdom
| | - A McConnachie
- Cardiovascular Research Centre of Glasgow, Glasgow, United Kingdom
| | - C Berry
- University of Glasgow, ICAMS, Glasgow, United Kingdom
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Ang D, Pannemans J, Vanuytsel T, Tack J. A single-center audit of the indications and clinical impact of prolonged ambulatory small intestinal manometry. Neurogastroenterol Motil 2018; 30:e13357. [PMID: 29717525 DOI: 10.1111/nmo.13357] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/23/2018] [Indexed: 02/08/2023]
Abstract
BACKGROUND Small bowel manometry is a diagnostic test available only in a few specialized referral centers. Its exact place in the management of refractory symptoms is controversial. METHODS The records of all patients who underwent 24-hour ambulatory duodenojejunal manometry over a 6-year period were retrospectively reviewed. We studied the clinical indications for small bowel manometry, and reviewed the impact of manometric findings on the clinical outcome. One hundred and forty-six studies were performed in 137 patients (46M, 91F) with a mean age of 44.9 ± 15.7 years. Mean follow-up duration was 15.1 ± 22.6 months. Appropriate endoscopic, radiological and gastric scintigraphy studies were performed in all patients prior to small bowel manometry. Criteria for abnormal motor activity were based on Bharucha's classification. KEY RESULTS The indications for small bowel manometry were chronic abdominal pain (n = 43), slow-transit constipation (n = 17), refractory gastroparesis (n = 16), chronic diarrhea (n = 7), recurrent episodes of subocclusion (n = 16), postsurgical evaluation (n = 36), suspicion of gut involvement in systemic disease (n = 9), and unexplained nausea (n = 2). The most common finding was a normal 24-hour ambulatory small bowel manometry (n = 113). Thirty-three studies yielded abnormal findings which included extrinsic neuropathy (n = 6), intrinsic neuropathy (n = 18), intestinal myopathy (n = 2), and subocclusion (n = 7). Ambulatory small bowel manometry excluded a generalized motility disorder in 77% and had a significant impact on the subsequent clinical course in 23%. CONCLUSIONS & INFERENCES Ambulatory small bowel manometry is a useful and safe diagnostic tool to complement traditional investigative modalities in patients with severe unexplained abdominal symptoms.
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Affiliation(s)
- D Ang
- Translational Research Center for Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Aging, KU Leuven, Leuven, Belgium.,Division of Gastroenterology, University Hospitals, Leuven, Belgium
| | - J Pannemans
- Translational Research Center for Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Aging, KU Leuven, Leuven, Belgium.,Division of Gastroenterology, University Hospitals, Leuven, Belgium
| | - T Vanuytsel
- Translational Research Center for Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Aging, KU Leuven, Leuven, Belgium.,Division of Gastroenterology, University Hospitals, Leuven, Belgium
| | - J Tack
- Translational Research Center for Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Aging, KU Leuven, Leuven, Belgium.,Division of Gastroenterology, University Hospitals, Leuven, Belgium
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Ang D, Hollenstein M, Misselwitz B, Knowles K, Wright J, Tucker E, Sweis R, Fox M. Rapid Drink Challenge in high-resolution manometry: an adjunctive test for detection of esophageal motility disorders. Neurogastroenterol Motil 2017; 29. [PMID: 27420913 DOI: 10.1111/nmo.12902] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 06/12/2016] [Indexed: 01/18/2023]
Abstract
BACKGROUND/AIMS The Chicago Classification for diagnosis of esophageal motility disorders by high-resolution manometry (HRM) is based on single water swallows (SWS). Emerging data suggest that a "Rapid Drink Challenge" (RDC) increases sensitivity for motility disorders. This study establishes normal values and diagnostic thresholds for RDC in clinical practice. METHODS Two cohort studies were performed in patients with dysphagia or reflux symptoms (development and validation sets). Healthy subjects and patient controls provided reference values. Ten SWS and two 200-mL RDC were performed. Primary diagnosis for SWS was established by the Chicago Classification. Abnormal RDC was defined by impaired esophagogastric junction (EGJ) function (elevated integrated relaxation pressure during RDC [IRP-RDC]); incomplete inhibition of contractility during and ineffective contraction after RDC. Diagnostic thresholds identified in the development set were prospectively tested in the validation set. RESULTS Normal values were determined in healthy (n=95; age 37.8 ± 12) and patient controls (n=44; age 46.4 ± 15). Development and validation sets included 178 (54 ± 17 years) and 226 (53 ± 16 years) patients, respectively. Integrated relaxation pressure during RDC was higher for SWS than RDC in all groups (overall P<.001), except achalasia. Rapid Drink Challenge suppressed contractility, except in achalasia type III, spasm, and hypercontractile motility disorders (P<.001). An effective after-contraction was present more often in health than disease (P<.001). Optimal diagnostic thresholds identified in the development set (IRP-RDC ≥12 mmHg achalasia, IRP-RDC ≥ 8mmHg "all cause" EGJ dysfunction), were confirmed in the validation set (both, sensitivity ~85%, specificity >95%). CONCLUSIONS Rapid Drink Challenge contributes clinically relevant information to routine HRM studies, especially in patients with EGJ dysfunction.
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Affiliation(s)
- D Ang
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.,Department of Gastroenterology, Changi General Hospital, Singapore City, Singapore
| | - M Hollenstein
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - B Misselwitz
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - K Knowles
- NIHR Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals, Nottingham, UK
| | - J Wright
- NIHR Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals, Nottingham, UK
| | - E Tucker
- NIHR Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals, Nottingham, UK
| | - R Sweis
- Upper GI Physiology, University College London Hospital, London, UK
| | - M Fox
- Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.,NIHR Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals, Nottingham, UK
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Tack J, Deloose E, Ang D, Scarpellini E, Vanuytsel T, Van Oudenhove L, Depoortere I. Motilin-induced gastric contractions signal hunger in man. Gut 2016; 65:214-24. [PMID: 25539673 DOI: 10.1136/gutjnl-2014-308472] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 11/24/2014] [Indexed: 12/12/2022]
Abstract
RATIONALE Hunger is controlled by the brain, which receives input from signals of the GI tract (GIT). During fasting, GIT displays a cyclical motor pattern, the migrating motor complex (MMC), regulated by motilin. OBJECTIVES To study the relationship between hunger and MMC phases (I-III), focusing on spontaneous and pharmacologically induced phase III and the correlation with plasma motilin and ghrelin levels. The role of phase III was also studied in the return of hunger after a meal in healthy individuals and in patients with loss of appetite. FINDINGS In fasting healthy volunteers, mean hunger ratings during a gastric (62.5±7.5) but not a duodenal (40.4±5.4) phase III were higher (p<0.0005) than during phase I (27.4±4.7) and phase II (37±4.5). The motilin agonist erythromycin, but not the cholinesterase inhibitor neostigmine, induced a premature gastric phase III, which coincided with an increase in hunger scores from 29.2±7 to 61.7±8. The somatostatin analogue octreotide induced a premature intestinal phase III without a rise in hunger scores. Hunger ratings significantly correlated (β=0.05; p=0.01) with motilin plasma levels, and this relationship was lost after erythromycin administration. Motilin, but not ghrelin administration, induced a premature gastric phase III and a rise in hunger scores. In contrast to octreotide, postprandial administration of erythromycin induced a premature gastric phase III accompanied by an early rise in hunger ratings. In patients with unexplained loss of appetite, gastric phase III was absent and hunger ratings were lower. CONCLUSIONS Motilin-induced gastric phase III is a hunger signal from GIT in man.
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Affiliation(s)
- J Tack
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - E Deloose
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - D Ang
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - E Scarpellini
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - T Vanuytsel
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - L Van Oudenhove
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - I Depoortere
- Translational Research Centre for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
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Wong AKF, Symon R, ADZjali M, Ang D, Choy AM, Petrie JR, Struthers AD, Lang CC. 067 Metformin in insulin resistant LV dysfunction, a double-blind, placebo controlled trial (Tayside trial). Heart 2015. [DOI: 10.1136/hrt.2010.195966.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Ang D. Author’s reply: Current status of functional gastrointestinal evaluation in clinical practice. Singapore Med J 2015; 56:176. [DOI: 10.11622/smedj.2015047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ang D, Pauwels A, Akyuz F, Vos R, Tack J. Influence of a neurokinin-1 receptor antagonist (aprepitant) on gastric sensorimotor function in healthy volunteers. Neurogastroenterol Motil 2013; 25:e830-8. [PMID: 23991829 DOI: 10.1111/nmo.12210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 07/20/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND Substance P (SP) is a member of the neurokinin (NK) family and is one of the established neurotransmitters in the mammalian central and enteric nervous system. It is unclear whether NK1 receptors are involved in the control of gastric sensorimotor function in man. METHODS We studied the effects of aprepitant, an NK1 receptor antagonist used in the treatment of chemotherapy-induced emesis, on gastric sensorimotor function in healthy volunteers. Sixteen healthy volunteers (six males, 32.4 ± 2.7 years) were studied on three separate occasions after placebo, aprepitant 80 or 125 mg in randomized double-blind study to assess gastric compliance, perception to isobaric distensions, and gastric accommodation with a gastric barostat. KEY RESULTS Compared to placebo, both doses of aprepitant did not influence gastric compliance or sensitivity to gastric distension. Aprepitant 80 and 125 mg did not have any significant effects on gastric accommodation compared with placebo (mean postprandial gastric volume increase, respectively, 83.4 ± 28.4 vs 35.3 ± 16.2 vs 83.9 ± 30.4 mL, NS). Postprandial gastric compliance and sensitivity to distention were also not altered. CONCLUSIONS & INFERENCES In health, NK1 receptors do not appear to be involved in the control of gastric compliance, accommodation or sensitivity to distention in man.
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Affiliation(s)
- D Ang
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
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Abstract
Many particle-physics models that extend the standard model predict the existence of long-range spin-spin interactions. We propose an approach that uses the Earth as a polarized spin source to investigate these interactions. Using recent deep-Earth geophysics and geochemistry results, we create a comprehensive map of electron polarization within the Earth induced by the geomagnetic field. We examine possible long-range interactions between these spin-polarized geoelectrons and the spin-polarized electrons and nucleons in three laboratory experiments. By combining our model and the results from these experiments, we establish bounds on torsion gravity and possible long-range spin-spin forces associated with the virtual exchange of either spin-one axial bosons or unparticles.
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Affiliation(s)
- Larry Hunter
- Physics Department, Amherst College, Amherst, MA 01002, USA.
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Gentile L, Cuenca A, Lopez M, Liu H, Xiao W, Mindrinos M, Ang D, Efron P, Cuschieri J, Warren H, Tompkins R, Maier R, Baker H, Moldawer L. Development of a Genomic Metric that can be Rapidly Used to Predict Clinical Outcome in Severely Injured Trauma Patients. J Surg Res 2013. [DOI: 10.1016/j.jss.2012.10.530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Troxell ML, Ang D, Warrick A, Beadling C, Corless CL. Abstract P2-08-03: Phosphatidylinositol-3-kinase mutations are common in lobular neoplasia. Cancer Res 2012. [DOI: 10.1158/0008-5472.sabcs12-p2-08-03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The phosphatidylinositol-3-kinase pathway is one of the most commonly mutated in invasive breast carcinoma, with PIK3CA mutations present in ∼25% of invasive carcinomas, and several studies demonstrating an even higher prevalence of PIK3CA mutations in invasive lobular carcinomas. Lobular neoplasia (LN), including lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH), are controversial lesions that may represent non-obligate precursor of invasive lobular carcinoma. However, lobular neoplasia has not yet been systematically studied for activating point mutations.
Twenty-six breast resection specimens containing LN and/or invasive lobular carcinoma (ILC) were identified from the files of Oregon Health & Science University. Adjacent lesions including columnar cell change (CCC), usual ductal hyperplasia (UDH), invasive or in-situ ductal carcinoma, and lymph node metastases were separately isolated where available. DNA was prepared from punches of formalin-fixed paraffin-embedded tissue blocks using standard methods. DNA extracts were screened for a panel of point mutations using a multiplex PCR panel with a mass-spectroscopy readout (Sequenom MassArray). The panel covers 643 point mutations in 53 genes including AKT1/2/3, ALK, BRAF, CDK4, CSF1R, CTNNB1, EGFR, ERBB2, ERCC6, FBX4, FBXW7, FES, FGFR1/2/3/4, FOXL2, GNA11, GNAQ, GNAS, HRAS, IDH1/2, IGF1R, KDR, KIT, KRAS, MAPK2K1/2/7, MET, MYC, NEK9, NRAS, NTRK1/2/3, PDGFRA, PIK3CA, PIK3R1/4/5, PKHD1, PRKCB1, RAF1, RET, SMO, SOS1, STAT1, TEC, and TP53; covering 41 substitutions in 23 codons of the PIK3CA gene.
PIK3CA mutations were identified in 8/22 LN (36%; PIK3CA exon 4 N345K-1; exon 9 E542K-1; E545K-3; exon 20 H1047R-3), and in 11/16 ILC (68%; PIK3CA exon 4 N345K-2; exon 9 E542K-1, E545K-2, Q546R-1; exon 20 H1047L-1, H1047R-4, one with concomitant HRAS G12D mutation). LN and coincident ILC were tested in 11 patients; 4 patients had the same point mutations in LN and ILC (concordant mutant); 4 patients were wildtype for all codons tested in LN and ILC (concordant wildtype); 3 patients had discordant mutation status (LCIS-E545K/ILC-H1047R; LCIS-E542K/ILC-H1047R; ALH-WT/ILC-H1047R & HRAS G12V). Four patients had LN and invasive ductal carcinoma (IDC); of these, 2 were discordant (LCIS-H1047R/IDC-wildtype; ALH-wildtype/IDC-E545K) and 2 concordant wildtype. Two additional patients had discrete IDC and ILC tumors; in both the IDC was wildtype, but the ILC harbored a PIK3CA mutation. Concurrent CCC and UDH were also screened, yielding 10/22 (45%) lesions with PIK3CA point mutations; in 3 instances the UDH mutation was concordant with LN/ILC, whereas CCC from the same specimen has discordant mutational status.
Our study confirms the high prevalence of PIK3CA hotspot point mutations in ILC (68%). Importantly, we screened LCIS and ALH for a large panel of point mutations, and found only PIK3CA mutations (36% of lesions). Although a small cohort, the mutation status of concurrent LN and ILC was frequently concordant (8/11=72%), and in fact, quite similar to the degree of mutational concordance between paired DCIS and IDC in the literature and in our own experience (66–77%). This provides some support to the notion of LN as a precursor to ILC.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-08-03.
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Affiliation(s)
- ML Troxell
- Oregon Health & Science University, Portland, OR
| | - D Ang
- Oregon Health & Science University, Portland, OR
| | - A Warrick
- Oregon Health & Science University, Portland, OR
| | - C Beadling
- Oregon Health & Science University, Portland, OR
| | - CL Corless
- Oregon Health & Science University, Portland, OR
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Ang D, Tay C, Tan L, Preiser P, Ramanujan R. In vitro studies of magnetically enhanced transfection in COS-7 cells. Materials Science and Engineering: C 2011. [DOI: 10.1016/j.msec.2011.05.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Impaired gastric accommodation is an important cause of functional dyspepsia. Currently available tests that evaluate gastric accommodation provide relevant physiological information, but they pose technical difficulties and their clinical impact remains controversial. Gastric barostat remains the gold standard, but it is an invasive procedure. In recent years, emerging modalities including single photon emission computed tomography (SPECT), three-dimensional ultrasound and magnetic resonance imaging have been developed to measure gastric volumes and hold promise as alternative methods of assessing gastric accommodation non-invasively. Studies are underway to validate these techniques with recent data proving the performance characteristics of SPECT. The non-invasive nutrient drink test measures satiety scores as a surrogate marker of gastric accommodation and remains controversial. More recently, intragastric monitoring has been proposed as yet another non-invasive modality to assess gastric accommodation. Each of these different modalities brings its associated advantages and disadvantages, as is discussed in this review. Ongoing studies to validate these new techniques are in progress and are likely to lead to further progress in neurogastroenterology.
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Affiliation(s)
- D Ang
- Division of Gastroenterology, Department of Medicine, Changi General Hospital, Singapore.
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Ang D, Nguyen Q, Kayal S, Preiser P, Rawat R, Ramanujan R. Insights into the mechanism of magnetic particle assisted gene delivery. Acta Biomater 2011; 7:1319-26. [PMID: 20920614 DOI: 10.1016/j.actbio.2010.09.037] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 09/20/2010] [Accepted: 09/28/2010] [Indexed: 11/26/2022]
Abstract
In magnetic particle assisted gene delivery DNA is complexed with polymer-coated aggregated magnetic nanoparticles (AMNPs) to effect transfection. In vitro studies based on COS-7 cells were carried out using pEGFP-N1 and pMIR-REPORT-complexed, polyethylenimine (PEI)-coated iron oxide magnetic nanoparticles (MNPs). PEI-coated AMNPs (PEI-AMNPs) with average individual particle diameters of 8, 16 and 30 nm were synthesized. Normal, reverse and retention magnetic transfection experiments and cell wounding assays were performed. Our results show that the optimum magnetic field yields maximum transfection efficiency with good viability. The results of the normal, reverse and retention magnetic transfection experiments show that the highest transfection efficiency was achieved in normal magnetic transfection mode due to clustering of the PEI-AMNPs on the cells. Cell wounding assay results suggest that the mechanism of magnetic transfection is endocytosis rather than cell wounding.
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Abstract
BACKGROUND The measurement of patient-reported outcomes (PRO) in treatment trials for functional gastrointestinal disorders is a matter of controversy. AIM To focus on instruments and endpoints that have been used to evaluate the efficacy of therapeutic agents in functional dyspepsia (FD) trials, also considering the newly defined Rome III FD criteria. METHODS A Medline search was conducted to identify relevant studies pertaining to FD treatment, with particular emphasis on the studies to date which have used validated outcome measures. RESULTS Currently available outcome measures are heterogeneous across studies. They include global binary endpoints, analogue or categorical scoring scales, uni- or multi-dimensional disease specific questionnaires, global outcome evaluations and quality of life questionnaires. Across the available outcome measures, substantial heterogeneity is found, not only in the type of endpoint measure, but also in the number and types of symptoms that are considered to be part of the FD symptom complex. Especially based on content validity, none of the existing questionnaires or endpoints can be considered sufficiently validated to be recommended unequivocally as the primary outcome measure for FD trials according to the Rome III criteria. On the other hand, existing well-validated multi-dimensional questionnaires that include many non-FD symptoms can be narrowed down to evaluate only the cardinal symptoms according to Rome III. CONCLUSIONS There is an urgent need to develop Rome III-based patient-reported outcomes for functional dyspepsia. Well-validated multi-dimensional questionnaires may serve as a guidance for this purpose, and could also be considered for use in ongoing clinical trials.
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Affiliation(s)
- D Ang
- Center for Gastroenterological Research, Department of Pathophysiology, Division of Gastroenterology, University Hospital Gasthuisberg, Herestraat 49, Leuven, Belgium
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Abstract
OBJECTIVE To evaluate the cost effectiveness of duloxetine when considered as an alternative treatment for patients in the United States (US) being treated for fibromyalgia pain. RESEARCH DESIGN AND METHODS A Markov model was used to evaluate the economic and clinical advantages of duloxetine in controlling fibromyalgia pain symptoms over a 2-year time horizon. A base-case treatment sequence was adopted from clinical guidelines, based on tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, anticonvulsants, and opioids. Treatment response was modeled using changes from baseline in pain severity, and response thresholds: full response (at least a 50% change), response (30-49% change), and no response (less than a 30% change). Clinical efficacy and discontinuation data were taken from placebo- and active-controlled trials identified in a systematic literature review and mixed-treatment comparison. Utility data were based on EQ-5D data. MAIN OUTCOME MEASURES Additional symptom-control months (SCMs), defined as the amount of time at a response level of 30% or less, and quality-adjusted life-years (QALYs) over a 2-year time horizon. RESULTS For every 1000 patients, first-line duloxetine resulted in an additional 665 SCMs and 12.3 QALYs, at a cost of $582,911 (equivalent to incremental cost-effectiveness ratios [ICERs] of $877 per SCM and $47,560 per QALY). Second-line duloxetine resulted in an additional 460 SCMs and 8.7 QALYs, at a cost of $143,752 (equivalent to ICERs of $312 per SMC and $16,565 per QALY). LIMITATIONS Response data for TCAs are limited to 30% improvement levels, reported trials are small, and have low placebo response rates. The model necessarily assumes that response rates are independent of placement in the treatment sequence. CONCLUSIONS The results suggest that the introduction of duloxetine into the standard treatment sequence for fibromyalgia not only provides additional patient benefits, reflected by time spent in pain control, but also is cost effective when compared with commonly adopted thresholds.
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Affiliation(s)
- S M Beard
- RTI Health Solutions, Manchester, UK.
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Kris MG, Lau CY, Ang D, Brzostowski E, Riely GJ, Rusch VW, Jhanwar S, Lash A, Zakowski MF, Ladanyi M. Initial results of LC-MAP: An institutional program to routinely profile tumor specimens for the presence of mutations in targetable pathways in all patients with lung adenocarcinoma. J Clin Oncol 2010. [DOI: 10.1200/jco.2010.28.15_suppl.7009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
Barrett's esophagus has traditionally been regarded as the most severe end of the spectrum of gastroesophageal reflux disease and is of great clinical importance in view of the association with esophageal adenocarcinoma. Studies have documented high levels of esophageal acid exposure in Barrett's esophagus. Various pathogenetic mechanisms underlie this phenomenon. These include abnormalities in esophageal peristalsis, defective lower esophageal sphincter pressures, gastric dysmotility and bile reflux. Whilst these factors provide evidence for an acquired cause of Barrett's esophagus, an underlying genetic predisposition cannot be ruled out. Although the past decade has brought about many new discoveries in the pathogenesis of Barrett's esophagus, it has also added further controversy to this complex disorder. A detailed analysis of the gastrointestinal motor abnormalities occurring in Barrett's esophagus follows, with a review of the currently available literature and an update on this condition that continues to be of interest to the gastroenterologist.
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Affiliation(s)
- D Ang
- Department of Gastroenterology, University Hospital Gasthuisberg, Katholieke Universiteit Leuven, Leuven, Belgium
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Ang D, Nicolai H, Vos R, Mimidis K, Akyuz F, Kindt S, Vanden Berghe P, Sifrim D, Depoortere I, Peeters T, Tack J. Influence of ghrelin on the gastric accommodation reflex and on meal-induced satiety in man. Neurogastroenterol Motil 2009; 21:528-33, e8-9. [PMID: 19210631 DOI: 10.1111/j.1365-2982.2008.01239.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ghrelin increases gastric tone in the fasting state and enhances gastric emptying in gastroparesis. The aims of the study were to evaluate the effect of ghrelin on postprandial gastric tone and on meal-induced satiety in health. Ten healthy volunteers underwent a barostat study on two occasions. After determination of intra-abdominal pressure (minimal distending pressure, MDP), isobaric volume measurement was performed for 90 min at MDP + 2 mmHg. After 20 min, ghrelin (40 microg) or saline was administered i.v. over 30 min in a double-blind-randomized cross-over design, followed 10 min later by a liquid meal (200 mL, 300 kcal). Stepwise isobaric distentions (+2 mmHg per 2 min) were performed 60 min after the meal. Data (mean +/- SEM) were compared using paired Student's t-test and ANOVA. Separately, a satiety drinking test (15 mL min(-1) until satiety score 5) was performed on 10 subjects twice, after treatment with placebo or ghrelin. Ghrelin infusion significantly inhibited gastric accommodation (mean volume increase adjusted means 108.0 +/- 50 vs 23.0 +/- 49 mL, P = 0.03, ANCOVA with the premeal postinfusion volume as covariate) and reduced postprandial gastric volumes (197.2 +/- 24.6 vs 353.5 +/- 50.0 mL, P = 0.01). Pressures inducing perception or discomfort during postprandial gastric distentions were not altered. During satiety testing, ghrelin did not alter nutrient volume ingested till maximal satiety (637.5 +/- 70.9 vs 637.5 +/- 56.2 mL, ns). Ghrelin administered during the meal significantly inhibits gastric accommodation in health, but this is not associated with early satiation.
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Affiliation(s)
- D Ang
- Division of Gastroenterology, Department of Pathophysiology, University of Leuven, Leuven, Belgium
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Ang D, Luman W, Ooi CJ. Early experience with double balloon enteroscopy: a leap forward for the gastroenterologist. Singapore Med J 2007; 48:50-60. [PMID: 17245517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
INTRODUCTION Double balloon enteroscopy (DBE) is a novel procedure that allows complete visualisation, biopsy and treatment of small intestinal disorders. We describe our early experience with the use of DBE, evaluating the indications, diagnostic rates and complications. A secondary aim of the study was to compare the findings from DBE with wireless capsule endoscopy (WCE). METHODS Retrospective study of patients referred to the Department of Gastroenterology and Hepathology at the Singapore General Hospital for evaluation of suspected small bowel diseases between February 2005 and May 2006 was done. A total of 34 procedures were conducted on 30 patients. A standardised data collection form was used. RESULTS DBE was carried out via the oral approach (19 patients), anal approach (eight patients), and both approaches (three patients). Mean age was 53 (range 16-79) years. 12 procedures (35.3 percent) had one endoscopist and 22 (64.7 percent) procedures had two. The overall diagnostic input from DBE was 73.3 percent (22 of 30 patients). A positive diagnosis was achieved in 19 patients: jejunal gastrointestinal stromal tumour (GIST) (one), jejunal sarcoma (one), jejunal adenocarcinoma (one), duodenal adenocarcinoma (one), malignant lymphangioma (one), eosinophilic enteritis (one), pseudomembranous ileitis (one), tuberculous ileitis (one), jejunitis/ileitis (seven), lymphangiectasia attributed to relapsed Non-Hodgkins lymphoma (one), combination of angiodysplastic lesions and apthous jejunal/ileal lesions (one), and focal villous atrophy (two). Small intestinal pathology was excluded in three patients with abnormal computed tomography (CT) findings. Endoscopy time for antegrade DBE was 46.1 (+/- 20.1) minutes and for retrograde DBE was 70.8 (+/- 11.0) minutes. The findings of WCE correlated with DBE findings in nine of 12 (75 percent) patients. Apart from the first three DBE procedures, all subsequent cases were performed without fluoroscopy. When stratified into antegrade and retrograde DBEs respectively, procedural duration, sedative use and diagnostic yield were comparable for one and two endoscopist DBEs. No complications were recorded. CONCLUSION Our early experience with DBE shows it to be safe and effective in imaging the small intestine, and it may soon become a standard mode of investigation for the gastroenterologist.
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Affiliation(s)
- D Ang
- Department of Gastroenterology and Hepatology, Singapore General Hospital, Outram Road, Singapore 169608
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Ang D, Hsu AAL, Tan BH. Fluoroquinolones may delay the diagnosis of tuberculosis. Singapore Med J 2006; 47:747-51. [PMID: 16924354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
INTRODUCTION Fluoroquinolones (FQs), frequently used for many common infections such as community-acquired pneumonia and urinary tract infection, are also effective against Mycobacterium tuberculosis. This study describes a series of patients in whom the empirical use of FQs for what appeared to be common community-acquired infections led to a delay in the diagnosis of tuberculosis (TB). METHODS We reviewed the records of five patients with TB in whom the early use of FQs led to partial symptom resolution and a prolonged relapsing and remitting course. RESULTS Of the five patients described, four presented with community-acquired pneumonia and one with urinary tract infection. All were given FQs and improved, though not completely. Their illnesses took a relapsing and remitting course. TB was eventually diagnosed, in four of them by culture and in one by characteristic histopathology (this patient required surgical resection of a lung abscess). CONCLUSION FQs may lead to partial symptom resolution in TB. We highlight the problem of a delayed diagnosis, and voice our concern about inadvertent monotherapy of TB in such cases.
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Affiliation(s)
- D Ang
- Department of Internal Medicine, Singapore General Hospital, Outram Road, Singapore 169608
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Ang D, Richardson A, Mayer MP, Keppel F, Krisch H, Georgopoulos C. Pseudo-T-even bacteriophage RB49 encodes CocO, a cochaperonin for GroEL, which can substitute for Escherichia coli's GroES and bacteriophage T4's Gp31. J Biol Chem 2001; 276:8720-6. [PMID: 11104767 DOI: 10.1074/jbc.m008477200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacteriophage T4-encoded Gp31 is a functional ortholog of the Escherichia coli GroES cochaperonin protein. Both of these proteins form transient, productive complexes with the GroEL chaperonin, required for protein folding and other related functions in the cell. However, Gp31 is specifically required, in conjunction with GroEL, for the correct folding of Gp23, the major capsid protein of T4. To better understand the interaction between GroEL and its cochaperonin cognates, we determined whether the so-called "pseudo-T-even bacteriophages" are dependent on host GroEL function and whether they also encode their own cochaperonin. Here, we report the isolation of an allele-specific mutation of bacteriophage RB49, called epsilon22, which permits growth on the E. coli groEL44 mutant but not on the isogenic wild type host. RB49 epsilon22 was used in marker rescue experiments to identify the corresponding wild type gene, which we have named cocO (cochaperonin cognate). CocO has extremely limited identity to GroES but is 34% identical and 55% similar at the protein sequence level to T4 Gp31, sharing all of the structural features of Gp31 that distinguish it from GroES. CocO can substitute for Gp31 in T4 growth and also suppresses the temperature-sensitive phenotype of the E. coli groES42 mutant. CocO's predicted mobile loop is one residue longer than that of Gp31, with the epsilon22 mutation resulting in a Q36R substitution in this extra residue. Both the CocO wild type and epsilon22 proteins have been purified and shown in vitro to assist GroEL in the refolding of denatured citrate synthase.
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Affiliation(s)
- D Ang
- Département de Biochimie Médicale, Centre Médical Universitaire, 1 rue Michel-Servet, CH-1211 Genève 4, Switzerland.
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Abstract
Early genetic studies identified the Escherichia coli groES and groEL genes because mutations in them blocked the growth of bacteriophages lambda and T4. Subsequent genetic and biochemical analyses have shown that GroES and GroEL constitute a chaperonin machine, absolutely essential for E. coli growth, because it is needed for the correct folding of many of its proteins. In spite of very little sequence identity to GroES, the bacteriophage T4-encoded Gp31 protein and the bacteriophage RB49-encoded CocO protein are bona fide GroEL cochaperonins, even capable of substituting for GroES in E. coli growth. A major functional distinction is that only Gp31 and CocO can assist GroEL in the correct folding of Gp23, the major bacteriophage capsid protein. Conserved structural features between CocO and Gp31, which are absent from GroES, highlight their potential importance in specific cochaperonin function.
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Affiliation(s)
- D Ang
- Département de Biochimie Médicale, Centre Médical Universitaire, 1 rue Michel Servet, Genève 4, CH-1211 Switzerland.
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Teter SA, Houry WA, Ang D, Tradler T, Rockabrand D, Fischer G, Blum P, Georgopoulos C, Hartl FU. Polypeptide flux through bacterial Hsp70: DnaK cooperates with trigger factor in chaperoning nascent chains. Cell 1999; 97:755-65. [PMID: 10380927 DOI: 10.1016/s0092-8674(00)80787-4] [Citation(s) in RCA: 299] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A role for DnaK, the major E. coli Hsp70, in chaperoning de novo protein folding has remained elusive. Here we show that under nonstress conditions DnaK transiently associates with a wide variety of nascent and newly synthesized polypeptides, with a preference for chains larger than 30 kDa. Deletion of the nonessential gene encoding trigger factor, a ribosome-associated chaperone, results in a doubling of the fraction of nascent polypeptides interacting with DnaK. Combined deletion of the trigger factor and DnaK genes is lethal under normal growth conditions. These findings indicate important, partially overlapping functions of DnaK and trigger factor in de novo protein folding and explain why the loss of either chaperone can be tolerated by E. coli.
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Affiliation(s)
- S A Teter
- Max-Planck-Institut für Biochemie, Department of Cellular Biochemistry, Martinsried, Germany
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Abstract
Fibromyalgia is characterized by diffuse pain, multiple tender points, fatigue, and sleep disturbance. Its frequent concurrence with rheumatic diseases modifies the clinical picture of the "primary" disease. This article reviews new information about the etiopathogenesis and treatment of this syndrome.
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Affiliation(s)
- D Ang
- Cleveland Clinic Foundation, Department of Rheumatic and Immunologic Diseases, OH 44195, USA
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Abstract
The Escherichia coli grpE gene (along with dnaK, dnaJ, groEL, and groES) was originally identified as one of the host factors required for phage lambda growth. The classical grpE280 mutation was the only grpE mutation that resulted from the initial screen and shown to specifically block the initiation of lambda DNA replication. Here we report the isolation of several new grpE missense mutations, again using phage lambda resistance as a selection. All mutants fall into two groups based on their temperature-dependent phenotype for lambda growth. Members of the first group (I), including grpE17 and grpE280, which was obtained again, are resistant to lambda growth at both 30 and 42 degrees C. Members of the second group (II), including grpE25, grpE66, grpE103, grpE13a, grpE57b, and grpE61, are sensitive to lambda growth at 30 degrees C but resistant at 42 degrees C. All mutations are recessive, since an E. coli grpE null mutant strain carrying these mutant alleles on low-copy-number plasmids are sensitive to infection by the lambda grpE+ transducing phage. Both group I and group II mutants are temperature sensitive for E. coli growth above 42 degrees C. The nucleotide changes were identified by sequencing analyses and shown to be dispersed throughout the latter 75% of the grpE coding region. Most of the amino acid changes occur at conserved residues, as judged by sequence comparisons between E. coli and other bacterial and yeast GrpE homologs. The isolation of these new mutations is the first step toward a structure-function analysis of the GrpE protein.
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Affiliation(s)
- B Wu
- Department of Cellular, Viral and Molecular Biology, University of Utah School of Medicine, Salt Lake City 84132
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Voos W, Gambill BD, Laloraya S, Ang D, Craig EA, Pfanner N. Mitochondrial GrpE is present in a complex with hsp70 and preproteins in transit across membranes. Mol Cell Biol 1994; 14:6627-34. [PMID: 7935381 PMCID: PMC359192 DOI: 10.1128/mcb.14.10.6627-6634.1994] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We characterized a 24-kDa protein associated with matrix hsp70 (mt-hsp70) of Neurospora crassa and Saccharomyces cerevisiae mitochondria. By using specific antibodies, the protein was identified as MGE, a mitochondrial homolog of the prokaryotic heat shock protein GrpE. MGE extracted from mitochondria was quantitatively bound to hsp70. It was efficiently released from hsp70 by the addition of Mg-ATP but not by nonhydrolyzable ATP analogs or high salt. A mutant mt-hsp70, which was impaired in release of bound precursor proteins, released MGE in an ATP-dependent manner, indicating that precursor proteins and MGE bind to different sites of hsp70. A preprotein accumulated in transit across the mitochondrial membranes was specifically coprecipitated by either antibodies directed against MGE or antibodies directed against mt-hsp70. The preprotein accumulated at the outer membrane was not coprecipitated by either antibody preparation. After being imported into the matrix, the preprotein could be coprecipitated only by antibodies against mt-hsp70. We propose that mt-hsp70 and MGE cooperate in membrane translocation of preproteins.
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Affiliation(s)
- W Voos
- Biochemisches Institut, Universität Freiburg, Germany
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Wyman C, Vasilikiotis C, Ang D, Georgopoulos C, Echols H. Function of the GrpE heat shock protein in bidirectional unwinding and replication from the origin of phage lambda. J Biol Chem 1993; 268:25192-6. [PMID: 8227083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The initiation of DNA replication by phage lambda depends on a specialized nucleoprotein structure that provides for the precise localization and activity of the Escherichia coli DnaB helicase at the lambda replication origin. Previous work has shown that the DnaJ and DnaK heat shock proteins function in the initiation pathway by releasing the DnaB helicase from the initiation complex to carry out localized unwinding of origin DNA. This DnaJ.DnaK pathway results in mainly unidirectional DNA unwinding and replication, whereas replication in vivo is mainly bidirectional. Based on recent replication work indicating an important role for the GrpE heat shock protein, we have used electron microscopy to study the action of GrpE in the DNA unwinding and replication reactions. We have found that GrpE acts with DnaJ and DnaK to facilitate the unwinding reaction at low concentrations of DnaK. In the presence of GrpE, bidirectional unwinding occurs in approximately half of the unwound DNA molecules. In addition, GrpE significantly increases the frequency of replication proceeding leftward from the origin. We suggest that reactions including GrpE result in more complete disassembly of the preinitiation nucleoprotein structure, thus allowing replication to proceed in both directions from the origin.
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Affiliation(s)
- C Wyman
- Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720
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Wyman C, Vasilikiotis C, Ang D, Georgopoulos C, Echols H. Function of the GrpE heat shock protein in bidirectional unwinding and replication from the origin of phage lambda. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74587-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Wu B, Georgopoulos C, Ang D. The essential Escherichia coli msgB gene, a multicopy suppressor of a temperature-sensitive allele of the heat shock gene grpE, is identical to dapE. J Bacteriol 1992; 174:5258-64. [PMID: 1644751 PMCID: PMC206360 DOI: 10.1128/jb.174.16.5258-5264.1992] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The grpE gene product is one of three Escherichia coli heat shock proteins (DnaK, DnaJ, and GrpE) that are essential for both bacteriophage lambda DNA replication and bacterial growth at all temperatures. In an effort to determine the role of GrpE and to identify other factors that it may interact with, we isolated multicopy suppressors of the grpE280 point mutation, as judged by their ability to reverse the temperature-sensitive phenotype of grpE280. Here we report the characterization of one of them, designated msgB. The msgB gene maps at approximately 53 min on the E. coli chromosome. The minimal gene possesses an open reading frame that encodes a protein with a predicted size of 41,269 M(r). This open reading frame was confirmed the correct one by direct amino-terminal sequence analysis of the overproduced msgB gene product. Genetic experiments demonstrated that msgB is essential for E. coli growth in the temperature range of 22 to 37 degrees C. Through a sequence homology search, MsgB was shown to be identical to N-succinyl-L-diaminopimelic acid desuccinylase (the dapE gene product), which participates in the diaminopimelic acid-lysine pathway involved in cell wall biosynthesis. Consistent with this finding, the msgB null allele mutant is viable only when the growth medium is supplemented with diaminopimelic acid. These results suggest that GrpE may have a previously unsuspected function(s) in cell wall biosynthesis in E. coli.
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Affiliation(s)
- B Wu
- Department of Cellular, Viral and Molecular Biology, School of Medicine, Univeristy of Utah, Salt Lake City 84132
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Delaney JM, Ang D, Georgopoulos C. Isolation and characterization of the Escherichia coli htrD gene, whose product is required for growth at high temperatures. J Bacteriol 1992; 174:1240-7. [PMID: 1310500 PMCID: PMC206417 DOI: 10.1128/jb.174.4.1240-1247.1992] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Those genes in Escherichia coli defined by mutations which result in an inability to grow at high temperatures are designated htr, indicating a high temperature requirement. A new htr mutant of E. coli was isolated and characterized and is designated htrD. The htrD gene has been mapped to 19.3 min on the E. coli chromosome. Insertional inactivation of htrD with a mini-Tn10 element resulted in a pleiotropic phenotype characterized by a severe inhibition of growth at 42 degrees C and decreased survival at 50 degrees C in rich media. Furthermore, htrD cells were sensitive to H2O2. Growth rate analysis revealed that htrD cells grow very slowly in minimal media supplemented with amino acids. This inhibitory effect has been traced to the presence of cysteine in the growth medium. Further studies indicated that the rate of cysteine transport is higher in htrD cells relative to the wild type. All of these results, taken together, indicate that the htrD gene product may be required for proper regulation of intracellular cysteine levels and that an increased rate of cysteine transport greatly affects the growth characteristics of E. coli.
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Affiliation(s)
- J M Delaney
- Department of Cellular, Viral, and Molecular Biology, University of Utah School of Medicine, Salt Lake City 84132
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Ang D, Liberek K, Skowyra D, Zylicz M, Georgopoulos C. Biological role and regulation of the universally conserved heat shock proteins. J Biol Chem 1991; 266:24233-6. [PMID: 1761528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- D Ang
- Department of Cellular, Viral, and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132
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Ang D, Liberek K, Skowyra D, Zylicz M, Georgopoulos C. Biological role and regulation of the universally conserved heat shock proteins. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54216-2] [Citation(s) in RCA: 221] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Liberek K, Marszalek J, Ang D, Georgopoulos C, Zylicz M. Escherichia coli DnaJ and GrpE heat shock proteins jointly stimulate ATPase activity of DnaK. Proc Natl Acad Sci U S A 1991; 88:2874-8. [PMID: 1826368 PMCID: PMC51342 DOI: 10.1073/pnas.88.7.2874] [Citation(s) in RCA: 631] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The products of the Escherichia coli dnaK, dnaJ, and grpE heat shock genes have been previously shown to be essential for bacteriophage lambda DNA replication at all temperatures and for bacterial survival under certain conditions. DnaK, the bacterial heat shock protein hsp70 analogue and putative chaperonin, possesses a weak ATPase activity. Previous work has shown that ATP hydrolysis allows the release of various polypeptides complexed with DnaK. Here we demonstrate that the ATPase activity of DnaK can be greatly stimulated, up to 50-fold, in the simultaneous presence of the DnaJ and GrpE heat shock proteins. The presence of either DnaJ or GrpE alone results in a slight stimulation of the ATPase activity of DnaK. The action of the DnaJ and GrpE proteins may be sequential, since the presence of DnaJ alone leads to an acceleration in the rate of hydrolysis of the DnaK-bound ATP. The presence of GrpE alone increases the rate of release of bound ATP or ADP without affecting the rate of hydrolysis. The stimulation of the ATPase activity of DnaK may contribute to its more efficient recycling, and it helps explain why mutations in dnaK, dnaJ, or grpE genes often exhibit similar pleiotropic phenotypes.
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Affiliation(s)
- K Liberek
- Department of Molecular Biology, University of Gdansk, Poland
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40
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Abstract
Bacteriophage lambda requires the lambda O and P proteins for its DNA replication. The rest of the replication proteins are provided by the Escherichia coli host. Some of these host proteins, such as DnaK, DnaJ, and GrpE, are heat shock proteins. Certain mutations in the dnaK, dnaJ, or grpE gene block lambda growth at all temperatures and E. coli growth above 43 degrees C. We have isolated bacterial mutants that were shown by Southern analysis to contain a defective, mini-Tn10 transposon inserted into either of two locations and in both orientations within the dnaJ gene. We have shown that these dnaJ-insertion mutants did not grow as well as the wild type at temperatures above 30 degrees C, although they blocked lambda DNA replication at all temperatures. The dnaJ-insertion mutants formed progressively smaller colonies at higher temperatures, up to 42 degrees C, and did not form colonies at 43 degrees C. The accumulation of frequent, uncharacterized suppressor mutations allowed these insertion mutants to grow better at all temperatures and to form colonies at 43 degrees C. None of these suppressor mutations restored the ability of the host to propagate phage lambda. Radioactive labeling of proteins synthesized in vivo followed by immunoprecipitation or immunoblotting with anti-DnaJ antibodies demonstrated that no DnaJ protein could be detected in these mutants. Labeling studies at different temperatures demonstrated that these dnaJ-insertion mutations resulted in altered kinetics of heat shock protein synthesis. An additional eight dnaJ mutant isolates, selected spontaneously on the basis of blocking phage lambda growth at 42 degrees C, were shown not to synthesize DnaJ protein as well. Three of these eight spontaneous mutants had gross DNA alterations in the dnaJ gene. Our data provide evidence that the DnaJ protein is not absolutely essential for E. coli growth at temperatures up to 42 degrees C under standard laboratory conditions but is essential for growth at 43 degrees C. However, the accumulation of extragenic suppressors is necessary for rapid bacterial growth at higher temperatures.
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Affiliation(s)
- S M Sell
- Department of Cellular, Viral and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132
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Liberek K, Osipiuk J, Zylicz M, Ang D, Skorko J, Georgopoulos C. Physical interactions between bacteriophage and Escherichia coli proteins required for initiation of lambda DNA replication. J Biol Chem 1990; 265:3022-9. [PMID: 2154468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The process of initiation of lambda DNA replication requires the assembly of the proper nucleoprotein complex at the origin of replication, ori lambda. The complex is composed of both phage and host-coded proteins. The lambda O initiator protein binds specifically to ori lambda. The lambda P initiator protein binds to both lambda O and the host-coded dnaB helicase, giving rise to an ori lambda DNA.lambda O.lambda P.dnaB structure. The dnaK and dnaJ heat shock proteins have been shown capable of dissociating this complex. The thus freed dnaB helicase unwinds the duplex DNA template at the replication fork. In this report, through cross-linking, size chromatography, and protein affinity chromatography, we document some of the protein-protein interactions occurring at ori lambda. Our results show that the dnaK protein specifically interacts with both lambda O and lambda P, and that the dnaJ protein specifically interacts with the dnaB helicase.
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Affiliation(s)
- K Liberek
- Department of Molecular Biology, University of Gdansk, Poland
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Georgopoulos C, Ang D. The Escherichia coli groE chaperonins. Semin Cell Biol 1990; 1:19-25. [PMID: 1983267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The E.coli groES and groEL genes have been shown to form an operon, to be essential for E. coli viability, and to belong to the so-called heat-shock class of genes whose expression is regulated by the intracellular levels of sigma factor sigma 32. Both groE chaperonin proteins possess a seven-fold axis of symmetry, groES being composed of seven identical subunits of 97 amino acids each, and groEL of fourteen identical subunits of 548 amino acids each. The two groE chaperonins interact intimately as judged by both genetic and biochemical criteria. This interaction has been shown to be required for both bacteriophage morphogenesis and bacterial growth. The groEL chaperonin has been shown to bind to a number of incomplete or unfolded polypeptides in vitro. Such binding may prevent misfolding and promote rapid intra- or intermolecular folding of polypeptides in vivo. The proposed role of the groES chaperonin is to displace the polypeptides bound to groEL, thus effectively promoting the recycling of groEL.
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Affiliation(s)
- C Georgopoulos
- Department of Cellular, Viral and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132
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Keppel F, Lipinska B, Ang D, Georgopoulos C. Mutational analysis of the phage T4 morphogenetic 31 gene, whose product interacts with the Escherichia coli GroEL protein. Gene 1990; 86:19-25. [PMID: 2311934 DOI: 10.1016/0378-1119(90)90109-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The phage T4 morphogenetic gene 31 has been sequenced. Its deduced gene product is a polypeptide of 111 aa, with a predicted Mr of 12064 and a pI of 4.88. The proof that the assigned open reading frame (ORF) encodes Gp31 rests on the sequencing of two known gene 31 amber mutations, amN54 and NG71, demonstrating that these mutations result in translational termination within the assigned ORF. Furthermore, the sequencing of four different T4 epsilon mutations, isolated on the basis of allowing the phage to propagate on Escherichia coli groEL- hosts, showed that they are either missense mutations or 3-bp deletions in the gene 31 reading frame. The sequencing of neighboring DNA revealed the presence of five other ORFs, one of which overlaps gene 31 substantially, but in the opposite orientation.
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Affiliation(s)
- F Keppel
- Department of Molecular Biology, University of Geneva, Switzerland
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Zylicz M, Ang D, Liberek K, Georgopoulos C. Initiation of lambda DNA replication with purified host- and bacteriophage-encoded proteins: the role of the dnaK, dnaJ and grpE heat shock proteins. EMBO J 1989; 8:1601-8. [PMID: 2527744 PMCID: PMC400992 DOI: 10.1002/j.1460-2075.1989.tb03544.x] [Citation(s) in RCA: 222] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Based on previous in vivo genetic analysis of bacteriophage lambda growth, we have developed two in vitro lambda DNA replication systems composed entirely of purified proteins. One is termed 'grpE-independent' and consists of supercoiled lambda dv plasmid DNA, the lambda O and lambda P proteins, as well as the Escherichia coli dnaK, dnaJ, dnaB, dnaG, ssb, DNA gyrase and DNA polymerase III holoenzyme proteins. The second system includes the E.coli grpE protein and is termed 'grpE-dependent'. Both systems are specific for plasmid molecules carrying the ori lambda DNA initiation site. The major difference in the two systems is that the 'grpE-independent' system requires at least a 10-fold higher level of dnaK protein compared with the grpE-dependent one. The lambda DNA replication process may be divided into several discernible steps, some of which are defined by the isolation of stable intermediates. The first is the formation of a stable ori lambda-lambda O structure. The second is the assembly of a stable ori lambda-lambda O-lambda P-dnaB complex. The addition of dnaJ to this complex also results in an isolatable intermediate. The dnaK, dnaJ and grpE proteins destabilize the lambda P-dnaB interaction, thus liberating dnaB's helicase activity, resulting in unwinding of the DNA template. At this stage, a stable DNA replication intermediate can be isolated, provided that the grpE protein has acted and/or is present. Following this, the dnaG primase enzyme recognizes the single-stranded DNA-dnaB complex and synthesizes RNA primers. Subsequently, the RNA primers are extended into DNA by DNA polymerase III holoenzyme. The proposed model of the molecular series of events taking place at ori lambda is substantiated by the many demonstrable protein-protein interactions among the various participants.
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Affiliation(s)
- M Zylicz
- Department of Molecular Biology, University of Gdansk, Poland
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Ang D, Georgopoulos C. The heat-shock-regulated grpE gene of Escherichia coli is required for bacterial growth at all temperatures but is dispensable in certain mutant backgrounds. J Bacteriol 1989; 171:2748-55. [PMID: 2651417 PMCID: PMC209960 DOI: 10.1128/jb.171.5.2748-2755.1989] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Previous work has established that the grpE+ gene product is a heat shock protein that is essential for bacteriophage lambda growth at all temperatures and for Escherichia coli growth at temperatures above 43 degrees C. Here it is shown that the grpE+ gene product is essential for bacterial viability at all temperatures. The strategy required constructing a grpE deletion derivative carrying a selectable chloramphenicol drug resistance marker provided by an omega insertion and showing that this deletion construct can be crossed into the bacterial chromosome if and only if a functional grpE+ gene is present elsewhere in the same cell. As a control, the same omega insertion could be placed immediately downstream of the grpE+ coding sequence without any observable effects on host growth. This result demonstrates that the inability to construct a grpE-deleted E. coli strain is not simply due to a lethal polar effect on neighboring gene expression. Unexpectedly, it was found that the grpE deletion derivative could be crossed into the bacterial chromosome in a strain that was defective in DnaK function. Further analysis showed that it was not the lack of DnaK function per se that allowed E. coli to tolerate a deletion in the grpE+ gene. Rather, it was the presence of unknown extragenic suppressors of a dnaK mutation that somehow compensated for the deficiency in both DnaK and GrpE function.
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Affiliation(s)
- D Ang
- Department of Cellular, Viral and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132
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Zylicz M, Ang D, Liberek K, Yamamoto T, Georgopoulos C. Initiation of lambda DNA replication reconstituted with purified lambda and Escherichia coli replication proteins. Biochim Biophys Acta 1988; 951:344-50. [PMID: 2850011 DOI: 10.1016/0167-4781(88)90105-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using highly purified bacteriophage lambda and E. coli replication proteins, we were able to reconstitute an in vitro system capable of replication ori lambda-containing plasmid DNA. The addition of a new E. coli factor, the grpE gene product, to this replication system reduced the level of dnaK protein required for efficient DNA synthesis by at least 10-fold, and also allowed the isolation of a stable DNA replication intermediate. Based on all available information, we propose a molecular mechanism for the action of the dnaK and grpE proteins during the prepriming reaction leading to lambda DNA synthesis.
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Affiliation(s)
- M Zylicz
- Department of Molecular Biology, University of Gdansk, Kladki, Poland
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47
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Lipinska B, King J, Ang D, Georgopoulos C. Sequence analysis and transcriptional regulation of the Escherichia coli grpE gene, encoding a heat shock protein. Nucleic Acids Res 1988; 16:7545-62. [PMID: 3045760 PMCID: PMC338426 DOI: 10.1093/nar/16.15.7545] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We have sequenced the Escherichia coli grpE gene and shown that it encodes a 197-amino acid residue protein of 21,668-Mr. The predicted N-terminal amino acid sequence, as well as the overall amino acid composition agree well with that of the purified protein. From Northern analysis, we have shown that transcription of the grpE gene is under heat shock regulation, i.e., there is a rapid and transient increase in the rate of synthesis of grpE mRNA upon a shift-up in temperature. Forty-six bases upstream of the structural gene is a sequence closely related to the consensus heat shock promoter identified by Cowing et al. [Proc. Natl. Acad. Sci. U.S.A, 82, 2679-2683]. We have shown by S1 mapping and RNA sequencing that this is indeed the promoter for the grpE mRNA. It appears that all discernable transcription initiates only from this promoter, even under non-heat shock conditions.
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Affiliation(s)
- B Lipinska
- Department of Cellular, Viral and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132
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Zylicz M, Ang D, Georgopoulos C. The grpE protein of Escherichia coli. Purification and properties. J Biol Chem 1987; 262:17437-42. [PMID: 2826421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The grpE gene of Escherichia coli was first identified because a mutation in it, grpE280, prevented bacteriophage lambda DNA replication in vivo. Subsequent work resulted in the identification of the grpE protein in two-dimensional gels and its classification as a heat shock protein. Here we report the purification of the grpE protein. We show that overproduction of grpE occurs in dnaK 103 bacteria which do not produce a functional Mr 72,000 dnaK protein. The grpE protein was purified from this strain primarily by its specific retention on a dnaK affinity column. The interaction between these two proteins, which is stable in the presence of 2 M KCl, allowed other proteins to be washed from this column. grpE was then eluted by ATP, which disrupts the interaction. During purification, grpE activity was monitored by its ability to complement an in vitro lambda dv DNA replication system dependent on the lambda O and lambda P proteins. The effect of ATP on the dnaK-grpE complex was also observed during sedimentation of the two proteins in glycerol gradients. Purified grpE protein has a Mr of approximately 23,000 under both denaturing and native conditions, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sedimentation, respectively. However, in the presence of dnaK under native conditions, grpE cosediments with dnaK. When ATP is added to the gradient, the complex is disrupted, and the two proteins sediment independently as monomers.
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Affiliation(s)
- M Zylicz
- Department of Cellular, Viral, and Molecular Biology, University of Utah, Salt Lake City 84132
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Ang D, Chandrasekhar GN, Zylicz M, Georgopoulos C. Escherichia coli grpE gene codes for heat shock protein B25.3, essential for both lambda DNA replication at all temperatures and host growth at high temperature. J Bacteriol 1986; 167:25-9. [PMID: 2424889 PMCID: PMC212835 DOI: 10.1128/jb.167.1.25-29.1986] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have identified the grpE gene product as the B25.3 heat shock protein of Escherichia coli on the following evidence: (i) a protein similar in size and isoelectric point to B25.3 was induced after infection of UV-irradiated bacteria by lambda grpE+ transducing phage, (ii) mutant phage lambda grpE40, isolated by its inability to propagate on grpE280 bacteria, failed to induce the synthesis of the B25.3 protein, and (iii) lambda grpE+ revertants, derived from phage grpE40 as able to propagate on grpE280 bacteria, simultaneously recovered the ability to induce synthesis of the B25.3 protein. In addition, we show that E. coli bacteria carrying the grpE280 mutation are temperature sensitive for bacterial growth at 43.5 degrees C. Through transductional analysis and temperature reversion experiments, it was demonstrated that the grpE280 mutation is responsible for both the inability of lambda to replicate at any temperature tested and the lack of colony formation at high temperature. At the nonpermissive temperature the rates of synthesis of DNA and RNA were reduced in grpE280 bacteria.
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