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Akhtar Z, Gallagher MM, Kontogiannis C, Leung LWM, Spartalis M, Jouhra F, Sohal M, Shanmugam N. Progress in Cardiac Resynchronisation Therapy and Optimisation. J Cardiovasc Dev Dis 2023; 10:428. [PMID: 37887875 PMCID: PMC10607614 DOI: 10.3390/jcdd10100428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/06/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Cardiac resynchronisation therapy (CRT) has become the cornerstone of heart failure (HF) treatment. Despite the obvious benefit from this therapy, an estimated 30% of CRT patients do not respond ("non-responders"). The cause of "non-response" is multi-factorial and includes suboptimal device settings. To optimise CRT settings, echocardiography has been considered the gold standard but has limitations: it is user dependent and consumes time and resources. CRT proprietary algorithms have been developed to perform device optimisation efficiently and with limited resources. In this review, we discuss CRT optimisation including the various adopted proprietary algorithms and conduction system pacing.
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Affiliation(s)
- Zaki Akhtar
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Mark M. Gallagher
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Christos Kontogiannis
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Lisa W. M. Leung
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Michael Spartalis
- Department of Cardiology, National and Kapodistrian University of Athens, 10679 Athens, Greece
| | - Fadi Jouhra
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Manav Sohal
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Nesan Shanmugam
- Department of Cardiology, St George’s University Hospital, Blackshaw Road, London SW17 0QT, UK
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Edwards J, Shanmugam N, Ray R, Jouhra F, Mancio J, Wiles J, Marciniak A, Sharma R, O’Driscoll J. Exercise Mode in Heart Failure: A Systematic Review and Meta-Analysis. Sports Med Open 2023; 9:3. [PMID: 36622511 PMCID: PMC9829948 DOI: 10.1186/s40798-022-00549-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 12/20/2022] [Indexed: 01/10/2023]
Abstract
BACKGROUND Optimising exercise prescription in heart failure (HF) with a preserved (HFpEF) or reduced (HFrEF) ejection fraction is clinically important. As such, the aim of this meta-analysis was to compare traditional moderate intensity training (MIT) against combined aerobic and resistance training (CT) and high-intensity interval training (HIIT) for improving aerobic capacity (VO2), as well as other clinically relevant parameters. METHODS A comprehensive systematic search was performed to identify randomised controlled trials published between 1990 and May 2021. Research trials reporting the effects of MIT against CT or HIIT on peak VO2 in HFpEF or HFrEF were considered. Left-ventricular ejection fraction (LVEF) and various markers of diastolic function were also analysed. RESULTS Seventeen studies were included in the final analysis, 4 of which compared MIT against CT and 13 compared MIT against HIIT. There were no significant differences between MIT and CT for peak VO2 (weighted mean difference [WMD]: 0.521 ml min-1 kg-1, [95% CI] = - 0.7 to 1.8, Pfixed = 0.412) or LVEF (WMD: - 1.129%, [95% CI] = - 3.8 to 1.5, Pfixed = 0.408). However, HIIT was significantly more effective than MIT at improving peak VO2 (WMD: 1.62 ml min-1 kg-1, [95% CI] = 0.6-2.6, Prandom = 0.002) and LVEF (WMD: 3.24%, [95% CI] = 1.7-4.8, Prandom < 0.001) in HF patients. When dichotomized by HF phenotype, HIIT remained significantly more effective than MIT in all analyses except for peak VO2 in HFpEF. CONCLUSIONS HIIT is significantly more effective than MIT for improving peak VO2 and LVEF in HF patients. With the exception of peak VO2 in HFpEF, these findings remain consistent in both phenotypes. Separately, there is no difference in peak VO2 and LVEF change following MIT or CT, suggesting that the addition of resistance exercise does not inhibit aerobic adaptations in HF.
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Affiliation(s)
- Jamie Edwards
- grid.127050.10000 0001 0249 951XSchool of Psychology and Life Sciences, Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1 QU UK
| | - Nesan Shanmugam
- grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
| | - Robin Ray
- grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
| | - Fadi Jouhra
- grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
| | - Jennifer Mancio
- grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
| | - Jonathan Wiles
- grid.127050.10000 0001 0249 951XSchool of Psychology and Life Sciences, Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1 QU UK
| | - Anna Marciniak
- grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
| | - Rajan Sharma
- grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
| | - Jamie O’Driscoll
- grid.127050.10000 0001 0249 951XSchool of Psychology and Life Sciences, Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1 QU UK ,grid.451349.eDepartment of Cardiology, St George’s Healthcare NHS Trust, Blackshaw Road, Tooting, London, SW17 0QT UK
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Kalbande P, Mahindrakar Jain B, Singh A, Shanmugam N, Kale P, Mathi Z, Borikar B, Tayde A, Datta N. PO-1082 CECT vs. MRI: Impact of concordance index for gross target volume in IMRT of head and neck cancers. Radiother Oncol 2022. [DOI: 10.1016/s0167-8140(22)03046-8] [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: 10/18/2022]
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Shanmugam N. The 2021 European Heart Failure Guidelines: The Case for Personalised Therapeutics. Eur Cardiol 2022; 17:e01. [PMID: 35154391 PMCID: PMC8819603 DOI: 10.15420/ecr.2021.57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 11/04/2022] Open
Affiliation(s)
- Nesan Shanmugam
- St George’s University Hospitals NHS Foundation Trust, St George’s University of London Cardiology Clinical Academic Group, London, UK
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Mukherjee RK, Sohal M, Shanmugam N, Pearse S, Jouhra F. Successful Identification of and Discrimination Between Atrial and Ventricular Arrhythmia with the Aid of Pacing and Defibrillator Devices. Arrhythm Electrophysiol Rev 2021; 10:235-240. [PMID: 35106174 PMCID: PMC8785083 DOI: 10.15420/aer.2021.54] [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] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/25/2021] [Indexed: 11/15/2022] Open
Abstract
The presence of supraventricular tachycardia is the leading cause of inappropriate shock in ICD recipients, and it can be a significant cause of morbidity, psychological distress and worsened clinical outcome. Modern pacing and ICD systems offer a number of discriminators that are integrated into algorithms to differentiate sustained ventricular tachycardia from supraventricular tachycardia. These algorithms can be adapted and optimised for each individual patient to ensure that only those arrhythmias that need treatment through the use of an ICD, are actually treated. This review summarises the single- and dual-chamber discriminators that can be used in the detection and classification of tachyarrhythmias.
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Affiliation(s)
- Rahul K. Mukherjee
- Department of Cardiology, St George’s University Hospital NHS Foundation Trust, London, UK
- Division of Imaging Sciences and Biomedical Engineering, St Thomas’ Hospital, King’s College London, UK
| | - Manav Sohal
- Department of Cardiology, St George’s University Hospital NHS Foundation Trust, London, UK
| | - Nesan Shanmugam
- Department of Cardiology, St George’s University Hospital NHS Foundation Trust, London, UK
| | - Simon Pearse
- Department of Cardiology, Kingston Hospital, London, UK
| | - Fadi Jouhra
- Department of Cardiology, St George’s University Hospital NHS Foundation Trust, London, UK
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Rammohan A, Rela M, Kumar GV, Scott JX, Shanmugam N, Reddy MS, Ramachandran P. Outcomes for high-risk hepatoblastoma in a resource-challenged setting. BJS Open 2020; 4:630-636. [PMID: 32379933 PMCID: PMC7397353 DOI: 10.1002/bjs5.50297] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 04/09/2020] [Indexed: 11/30/2022] Open
Abstract
Background Outcomes of high‐risk hepatoblastoma have been dismal, especially in resource‐challenged countries where access to chemotherapy and paediatric liver transplantation is limited for the underprivileged. This study aimed to assess the results of treatment of high‐risk hepatoblastoma in a tertiary centre, including patients who had non‐transplant surgical procedures in the form of extended resection. Methods A review of patients with high‐risk hepatoblastoma treated between January 2012 and May 2018 was carried out. Perioperative data and long‐term outcomes were analysed. Results Of 52 children with hepatoblastoma, 22 were considered to have high‐risk hepatoblastoma (8 girls and 14 boys). The mean(s.d.) age at diagnosis was 35(20) months. Of these 22 children, five died without surgery. Of the remaining 17 who underwent surgery, six had a resection (4 right and 2 left trisectionectomies) and 11 underwent living‐donor liver transplantation. Median follow‐up was 48 (range 12–90) months. Thirteen of the 17 children were alive at last follow‐up and four developed disseminated disease (3 had undergone liver transplantation and 1 liver resection). The overall survival rate at 1, 3 and 5 years was 77, 64 and 62 per cent for the whole cohort with high‐risk hepatoblastoma. In children who had surgery, 1‐, 3‐ and 5‐year survival rates were 91, 82 and 73 per cent for transplantation and 100, 83 and 83 per cent for resection. There was no difference in survival between the two surgical groups. Conclusion Excellent results in the treatment of high‐risk hepatoblastoma are possible, even in resource‐challenged countries.
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Affiliation(s)
- A Rammohan
- Institute of Liver Disease and Transplantation, Sree Balaji Medical College Hospital, Bharat Institute of Higher Education and Research, Chennai, India
| | - M Rela
- Ray of Light Foundation, Kanchi Kamakoti Children's Health Institute Laboratory and Diagnostic Services (CHILDS) Trust Hospital, CHILDS Trust Medical Research Foundation, Chennai, India
| | - G V Kumar
- Institute of Liver Disease and Transplantation, Sree Balaji Medical College Hospital, Bharat Institute of Higher Education and Research, Chennai, India
| | - J X Scott
- Institute of Liver Disease and Transplantation, Sree Balaji Medical College Hospital, Bharat Institute of Higher Education and Research, Chennai, India
| | - N Shanmugam
- Institute of Liver Disease and Transplantation, Sree Balaji Medical College Hospital, Bharat Institute of Higher Education and Research, Chennai, India
| | - M S Reddy
- Institute of Liver Disease and Transplantation, Sree Balaji Medical College Hospital, Bharat Institute of Higher Education and Research, Chennai, India
| | - P Ramachandran
- Institute of Liver Disease and Transplantation, Sree Balaji Medical College Hospital, Bharat Institute of Higher Education and Research, Chennai, India.,Ray of Light Foundation, Kanchi Kamakoti Children's Health Institute Laboratory and Diagnostic Services (CHILDS) Trust Hospital, CHILDS Trust Medical Research Foundation, Chennai, India
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Akhtar Z, Dargan J, Gaze D, Firoozi S, Collinson P, Shanmugam N. False-positive troponin elevation due to an immunoglobulin-G-cardiac troponin T complex: a case report. Eur Heart J Case Rep 2020; 4:1-5. [PMID: 32617489 PMCID: PMC7319834 DOI: 10.1093/ehjcr/ytaa082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/12/2019] [Accepted: 03/17/2020] [Indexed: 11/22/2022]
Abstract
Background Troponin is a crucial biomarker for the diagnosis of an acute coronary syndrome (ACS). It rises in response to myocardial injury from significant acute myocardial ischaemia caused by obstructive coronary artery disease [‘classical’ myocardial infarction (MI)]. However, raised levels have also been noted in conditions not recognized as classical ACS. This may include MI with non-obstructed coronary arteries such as takotsubo cardiomyopathy and other acute or chronic conditions such as pulmonary embolus or chronic kidney disease. This is commonly labelled as a ‘falsely elevated’ troponin although there is some myocardial strain to explain the rise, such as an increase in cardiac oxygen demand. True ‘falsely elevated’ troponin, characterized by a persistent elevation in the absence of cardiac injury does occur and thought to be secondary to an immunoglobulin-troponin complex (macrotroponin). Case summary A 53-year-old gentleman with a background of diabetes, hypertension, hypercholesterolaemia, and hepatitis B was admitted with chest pain and persistently elevated cardiac troponin T (cTnT) levels. Investigations revealed unobstructed coronary arteries and a structurally normal, well-functioning heart. Subsequent biochemical analysis found the persistently elevated cTnT secondary to macrotroponin T. Discussion Macrotroponin, an immunoglobulin-troponin bound complex should be considered as a differential diagnosis when the biochemistry is not reflective of the clinical picture. Early recognition requires effective collaboration with the biochemistry laboratory for accurate diagnosis.
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Affiliation(s)
- Zaki Akhtar
- Department of Cardiology, St George's University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - James Dargan
- Department of Cardiology, St George's University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - David Gaze
- Department of Cardiology, St George's University Hospital, Blackshaw Road, London SW17 0QT, UK.,School of Life Sciences, University of Westminster, Cavendish Street, London W1W 6UW, UK
| | - Sami Firoozi
- Department of Cardiology, St George's University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Paul Collinson
- Department of Cardiology, St George's University Hospital, Blackshaw Road, London SW17 0QT, UK
| | - Nesan Shanmugam
- Department of Cardiology, St George's University Hospital, Blackshaw Road, London SW17 0QT, UK
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Shanmugam N, Valamparampil J, Vij M, Reddy M, Rela M. Ischemic Cholangiopathy: Insight From an Explant Liver Allograft Affected by Severe Post-transplant Hypoxemia Due to Hepatopulmonary Syndrome: A Case Report. Transplant Proc 2019; 51:1002-1005. [PMID: 30979439 DOI: 10.1016/j.transproceed.2018.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/15/2018] [Indexed: 02/07/2023]
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Prasannalakshmi P, Shanmugam N, Senthil Kumar A. Electrochemistry of TiO2/CdS composite electrodes for supercapacitor applications. J APPL ELECTROCHEM 2017. [DOI: 10.1007/s10800-017-1092-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Adazabra AN, Viruthagiri G, Shanmugam N. Management of spent shea waste: An instrumental characterization and valorization in clay bricks construction. Waste Manag 2017; 64:286-304. [PMID: 28336335 DOI: 10.1016/j.wasman.2017.03.006] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 01/28/2017] [Accepted: 03/05/2017] [Indexed: 06/06/2023]
Abstract
This work studies the reuse of spent shea waste as an economic construction material in improving fired clay bricks manufacture aside providing a novel approach to ecofriendly managing its excessive generated from the shea agroindustry. For this purpose, the influence of spent shea waste addition on the chemical, mineralogical, molecular bonding and technological properties (i.e. compressive strength and water absorption) of the fired clay bricks were extensively investigated. The results indicated that the chemical, mineralogical, phase transformations, molecular bonding and thermal behavior of the produced bricks were practically unaffected by the addition of spent shea waste. However, spent shea waste addition increased the compressive strengths and water absorptions of the brick products. Potential performance benefits of reusing spent shea waste was improved fluxing agents, energy-contribution reaction, excellent porosifying effect, reduced thermal conductivity and enhanced compressive strengths of the brick products. This research has therefore provided compelling evidence that could create newfound route for the synergistic ecofriendly reuse of spent shea waste to enhance clay brick construction aside being a potential mainstream disposal option.
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Affiliation(s)
- A N Adazabra
- Department of Physics, Faculty of Science, Annamalai University, Annamalai Nagar 608002, Chidambaram, Tamil Nadu, India
| | - G Viruthagiri
- Department of Physics, Faculty of Science, Annamalai University, Annamalai Nagar 608002, Chidambaram, Tamil Nadu, India.
| | - N Shanmugam
- Department of Physics, Faculty of Science, Annamalai University, Annamalai Nagar 608002, Chidambaram, Tamil Nadu, India
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Patel HC, Hayward C, Dungu JN, Papadopoulou S, Saidmeerasah A, Ray R, Di Mario C, Shanmugam N, Cowie MR, Anderson LJ. Assessing the Eligibility Criteria in Phase III Randomized Controlled Trials of Drug Therapy in Heart Failure With Preserved Ejection Fraction: The Critical Play-Off Between a "Pure" Patient Phenotype and the Generalizability of Trial Findings. J Card Fail 2017; 23:517-524. [PMID: 28434933 DOI: 10.1016/j.cardfail.2017.04.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/09/2017] [Accepted: 04/13/2017] [Indexed: 11/29/2022]
Abstract
AIMS To investigate the effect of the different eligibility criteria used by phase III clinical studies in heart failure with preserved ejection fraction (HFpEF) on patient selection, phenotype, and survival. METHODS AND RESULTS We applied the key eligibility criteria of 7 phase III HFpEF studies (Digitalis Investigation Group Ancillary, Candesartan in Patients With Chronic Heart Failure and Preserved Left-Ventricular Ejection Fraction, Perindopril in Elderly People With Chronic Heart Failure, Irbesartan in Heart Failure With Preserved Systolic Function, Japanese Diastolic Heart Failure, Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist, and Efficacy and Safety of LCZ696 Compared to Valsartan, on Morbidity and Mortality in Heart Failure Patients With Preserved Ejection Fraction [PARAGON-HF; ongoing]) to a typical and well-characterized HFpEF population (n = 557) seen in modern European cardiological practice. Follow-up was available for a minimum of 24 months in each patient. Increasing the number of study eligibility criteria identifies a progressively smaller group of patients from real-life practice suitable for recruitment into clinical trials; using the J-DHF criteria, 81% of our clinic patients would have been eligible, whereas the PARAGON-HF criteria significantly reduced this proportion to 32%. The patients identified from our clinical population had similar mortality rates using the different criteria, which were consistently higher than those reported in the actual clinic trials. CONCLUSIONS Trial eligibility criteria have become stricter with time, which reduces the number of eligible patients, affecting both generalizability of any findings and feasibility of completing an adequately powered trial. We could not find evidence that the additional criteria used in more recent randomized trials in HFpEF have identified patients at higher risk of all-cause mortality.
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Affiliation(s)
- Hitesh C Patel
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, UK; Heart Failure Research Group, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.
| | - Carl Hayward
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, UK
| | - Jason N Dungu
- Basildon and Thurrock University Hospitals NHS Foundation Trust, Basildon, UK
| | | | | | | | - Carlo Di Mario
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Imperial College, London, UK
| | | | - Martin R Cowie
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, Imperial College, London, UK
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Adazabra AN, Viruthagiri G, Shanmugam N. Infrared analysis of clay bricks incorporated with spent shea waste from the shea butter industry. J Environ Manage 2017; 191:66-74. [PMID: 28088059 DOI: 10.1016/j.jenvman.2017.01.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 06/06/2023]
Abstract
The peculiar challenge of effective disposing abundant spent shea waste and the excellent compositional variation tolerance of clay material offered an impetus to examine the incorporation of spent shea waste into clay material as an eco-friendly disposal route in making clay bricks. For this purpose, the chemical constituent, mineralogical compositions and thermal behavior of both clay material and spent shea waste were initially characterized from which modelled brick specimens incorporating 5-20 wt% of the waste into the clay material were prepared. The clay material showed high proportions of SiO2 (52.97 wt%) and Al2O3 (27.10 wt%) indicating their rich kaolinitic content: whereas, the inert nature of spent shea waste was exhibited by their low oxide content. The striking similarities in infrared absorption bands of pristine clay material and clay materials incorporated with 15 wt% of spent shea waste showed that the waste incorporation had no impact on bond formation of the clay bricks. Potential performance benefits of developing bricks from clay material incorporated with spent shea waste included improved fluxing agents, economic sintering and making of sustainable bricks. Consequently, the analytical results authenticate the incorporation of spent shea waste into clay materials for various desired benefits aside being an environmental correct route of its disposal.
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Affiliation(s)
- A N Adazabra
- Department of Physics, Faculty of Science, Annamalai University, Annamalai Nagar, 608002, Chidambaram, Tamilnadu, India
| | - G Viruthagiri
- Department of Physics, Faculty of Science, Annamalai University, Annamalai Nagar, 608002, Chidambaram, Tamilnadu, India.
| | - N Shanmugam
- Department of Physics, Faculty of Science, Annamalai University, Annamalai Nagar, 608002, Chidambaram, Tamilnadu, India
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Prasannalakshmi P, Shanmugam N. Fabrication of TiO 2/ZnS nanocomposites for solar energy mediated photocatalytic application. Spectrochim Acta A Mol Biomol Spectrosc 2017; 175:1-10. [PMID: 28038372 DOI: 10.1016/j.saa.2016.12.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 12/02/2016] [Accepted: 12/13/2016] [Indexed: 06/06/2023]
Abstract
In the present work, we demonstrate the photocatalytic properties of nanosized TiO2, and different levels of ZnS-loaded TiO2/ZnS composites, for the degradation of the organic dyes brilliant green (BG), and methylene blue (MB) under solar light irradiation. For this process, TiO2 and the composites were synthesized by a sol-gel method. Further, the prepared products were subjected to structural, optical, and morphological characterizations. The results of the photocatalytic activity imply that for the samples studied, TiO2 loaded with an optimum level of zinc (0.25M), and sulfur (0.5M) is better able to actively degrade both BG and MB, due to its enhanced BET surface area, reduced band gap, and low charge transfer resistance.
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Affiliation(s)
- P Prasannalakshmi
- Department of Physics, Annamalai University, 608 002 Tamil Nadu, India
| | - N Shanmugam
- Department of Physics, Annamalai University, 608 002 Tamil Nadu, India.
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Prasannalakshmi P, Shanmugam N. Photocatalytic decolourization of brilliant green and methylene blue by TiO2/CdS nanorods. J Solid State Electrochem 2017. [DOI: 10.1007/s10008-017-3522-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Chen Z, Niederer S, Shanmugam N, Sermesant M, Rinaldi CA. Cardiac computational modeling of ventricular tachycardia and cardiac resynchronization therapy: a clinical perspective. Minerva Cardioangiol 2017; 65:380-397. [PMID: 28215064 DOI: 10.23736/s0026-4725.17.04362-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Computational modeling has contributed to the understanding of the normal cardiac electrophysiology and the mechanisms underlying arrhythmogenesis and arrhythmia maintenance. Our improved understanding of cardiac physiology and access to faster computational power have allowed us to integrate many layers of biological systems, gain further insight into the mechanism of cardiac pathology and moved from small scale molecular and cellular models to integrated three-dimensional models representing the anatomy, electrophysiology and hemodynamic parameters on an organ scale. The ultimate goal of cardiac modeling is to create personalized patient-specific models that would allow clinicians to better understand the disease pathology, aid diagnosis and plan treatment strategy on a case-by-case basis. Pioneers in the field have demonstrated that such approach have already impacted on the diagnosis and therapeutic treatment for ventricular arrhythmia and heart failure. This review demonstrates the feasibility to integrate computational modeling with clinical investigations in a clinical environment and to guide therapeutic treatment of cardiac arrhythmia and heart failure in real time for individual patients.
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Affiliation(s)
- Zhong Chen
- Division of Imaging Science and Biomedical Engineering, King's College London, London, UK - .,Department of Cardiology, Guy's and St Thomas' NHS Trust, London, UK - .,Department of Cardiology, St George's NHS Trust, London, UK -
| | - Steve Niederer
- Division of Imaging Science and Biomedical Engineering, King's College London, London, UK
| | | | | | - Christopher A Rinaldi
- Division of Imaging Science and Biomedical Engineering, King's College London, London, UK.,Department of Cardiology, Guy's and St Thomas' NHS Trust, London, UK
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Shanmugam N. Impact on Patient Care: The 2016 European Heart Failure Guidelines. Eur Cardiol 2017; 12:78-79. [PMID: 30416557 DOI: 10.15420/ecr.2017.12.1.ge2] [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: 11/04/2022] Open
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Shanmugam N, Dhanaraj K, Viruthagiri G, Balamurugan K, Deivam K. Synthesis and characterization of surfactant assisted Mn2+ doped ZnO nanocrystals. ARAB J CHEM 2016. [DOI: 10.1016/j.arabjc.2011.08.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Prasannalakshmi P, Shanmugam N, kumar AS, Kannadasan N. Phase-dependent electrochemistry of TiO2 nanocrystals for supercapacitor applications. J Electroanal Chem (Lausanne) 2016. [DOI: 10.1016/j.jelechem.2016.06.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Viruthagiri G, Sathiya priya S, Shanmugam N, Balaji A, Balamurugan K, Gopinathan E. Spectroscopic investigation on the production of clay bricks with SCBA waste. Spectrochim Acta A Mol Biomol Spectrosc 2015; 149:468-475. [PMID: 25978014 DOI: 10.1016/j.saa.2015.05.006] [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] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 04/24/2015] [Accepted: 05/04/2015] [Indexed: 06/04/2023]
Abstract
In this paper, the effect of sugarcane bagasse ash (SCBA) addition to the brick making clay has been analyzed using spectroscopic techniques. For that, mixtures of brick making clay (BMC) with sugarcane bagasse ash (SCBA) in proportions of 0-20 wt.% were hydraulic uniaxially pressed and sintered at temperatures of 800-1100 °C. The partial replacement of the brick making clay with SCBA was studied with chemical and mineralogical analyzes (XRF and X-ray diffraction). The quantitative estimation of minerals was made by FTIR analysis. The results of FT-IR reveal that kaolinite, quartz, and lignin are predominant, whereas, cellulose and calcite are in moderate levels. In addition, magnetite and hematite are found in trace level. The overall results reveal that the brick making clay substituted with 15 wt.% of SCBA can open up a new path for the fabrication of quality bricks at low cost.
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Affiliation(s)
- G Viruthagiri
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India.
| | - S Sathiya priya
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
| | - A Balaji
- Department of Mechanical Engineering, A.V.C. College of Engineering, Mayiladuthurai, Mannampandal, Tamilnadu, India
| | - K Balamurugan
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
| | - E Gopinathan
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
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Shanmugam N, Suthakaran S, Kannadasan N, Sathish kumar K. Synthesis and Characterization of Te Doped ZnO Nanosheets For Photocatalytic Application. ACTA ACUST UNITED AC 2015. [DOI: 10.33805/2639-6734.105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this paper, we report the synthesis of tellurium (Te) doped ZnO nanocrystals for photocatalytic applications. X-ray diffraction, Fourier transforms infrared, photoluminescence and field emission scanning electron microscope are the techniques employed to characterize the properties of the prepared products. The photocatalytic activities of the undoped and doped ZnO are analyzed by the degradation of brilliant green (BG). The results of the degradation reveal that ZnO doped with Te has higher photocatalytic performance than undoped ZnO.
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Affiliation(s)
- N Shanmugam
- Department of Physics, Annamalai University, Chidambaram 608 002, Tamilnadu, India
| | - S Suthakaran
- Department of Physics, Annamalai University, Chidambaram 608 002, Tamilnadu, India
| | - N Kannadasan
- Department of Physics, Annamalai University, Chidambaram 608 002, Tamilnadu, India
| | - K Sathish kumar
- Department of Physics, Annamalai University, Chidambaram 608 002, Tamilnadu, India
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Kannadasan N, Shanmugam N, Sathishkumar K, Cholan S, Ponnguzhali R, Viruthagiri G. Optical behavior and sensor activity of Pb ions incorporated ZnO nanocrystals. Spectrochim Acta A Mol Biomol Spectrosc 2015; 143:179-186. [PMID: 25727294 DOI: 10.1016/j.saa.2015.01.113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 01/23/2015] [Accepted: 01/31/2015] [Indexed: 06/04/2023]
Abstract
We present the synthesis and characterization of nanocrystalline ZnO doped with Pb in different concentrations. The structural and chemical compositions of the products are characterized by XRD, XPS, EDS and FT-IR spectroscopy. The observed results suggest that Pb ions (Pb(2+) and Pb(4+)) are successfully incorporated into the lattice position of Zn(2+) ions in ZnO. The optical properties of the products are studied by UV-Vis and room temperature PL measurements. The PL emission spectra of ZnO:Pb, show the intensity quenching for both the UV and visible emissions. The influence of Pb on controlling the size and morphology of ZnO is studied by FESEM and confirmed by HRTEM. Amperometric response shows that ZnO incorporated with 0.075M of Pb ions has enhanced sensor activity for H2O2 than the undoped product.
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Affiliation(s)
- N Kannadasan
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram, 608 002 Tamil Nadu, India
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram, 608 002 Tamil Nadu, India.
| | - K Sathishkumar
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram, 608 002 Tamil Nadu, India
| | - S Cholan
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram, 608 002 Tamil Nadu, India
| | - R Ponnguzhali
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram, 608 002 Tamil Nadu, India
| | - G Viruthagiri
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram, 608 002 Tamil Nadu, India
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Anbuvannan M, Ramesh M, Viruthagiri G, Shanmugam N, Kannadasan N. Synthesis, characterization and photocatalytic activity of ZnO nanoparticles prepared by biological method. Spectrochim Acta A Mol Biomol Spectrosc 2015; 143:304-308. [PMID: 25756552 DOI: 10.1016/j.saa.2015.01.124] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 01/17/2015] [Accepted: 01/29/2015] [Indexed: 06/04/2023]
Abstract
Zinc oxide have been produced via a simple green method from zinc nitrate and leaf extract aqueous solutions. Prepared ZnO nanoparticles (NPs) were investigated by employing through UV-Visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission-scanning electron microscope (FE-SEM), and transmission electron microscope (TEM), respectively. The present investigation, confirmed the estimated band gap 3.51eV and the PL intensity at 402nm in visible region are dependent upon the geometrical shape and size of the ZnO NPs. The TEM micrograph and XRD pattern confirmed the hexagonal wurtzite structure of ZnO NPs. The presence of functional groups and the chemical bonding are confirmed by FTIR spectra. EDS shows that the highly pure ZnO nanostructures. Moreover, the catalytic activity of synthesized ZnO in the reduction of methylene blue was studied by UV-Vis spectroscopy. The effects of process conditions on the morphology and size of ZnO have been found from FE-SEM and TEM analyses, respectively.
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Affiliation(s)
- M Anbuvannan
- Department of Physics, Annamalai University, Annamalainagar 608002, Tamil Nadu, India
| | - M Ramesh
- Department of Physics, Physics Wing (DDE), Annamalai University, Annamalainagar 608002, Tamil Nadu, India.
| | - G Viruthagiri
- Department of Physics, Annamalai University, Annamalainagar 608002, Tamil Nadu, India
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalainagar 608002, Tamil Nadu, India
| | - N Kannadasan
- Department of Physics, Annamalai University, Annamalainagar 608002, Tamil Nadu, India
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Premanand G, Shanmugam N, Kannadasan N, Sathishkumar K, Viruthagiri G. Nelumbo nucifera leaf extract mediated synthesis of silver nanoparticles and their antimicrobial properties against some human pathogens. Appl Nanosci 2015. [DOI: 10.1007/s13204-015-0442-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Poonguzhali R, Shanmugam N, Gobi R, Senthilkumar A, Shanmugam R, Sathishkumar K. Influence of Zn doping on the electrochemical capacitor behavior of MnO2 nanocrystals. RSC Adv 2015. [DOI: 10.1039/c5ra01326g] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Herein, we suggest a simple chemical precipitation method for the preparation of bare and different levels of Zn doped MnO2 nanoparticles as electrodes for supercapacitors.
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Affiliation(s)
- R. Poonguzhali
- Department of Physics
- Annamalai University
- Chidambaram 608 002
- India
| | - N. Shanmugam
- Department of Physics
- Annamalai University
- Chidambaram 608 002
- India
| | - R. Gobi
- Department of Physics
- Annamalai University
- Chidambaram 608 002
- India
| | - A. Senthilkumar
- Environmental & Analytical Chemistry Division
- School of Advanced Sciences
- VIT University
- Vellore
- India
| | - R. Shanmugam
- Environmental & Analytical Chemistry Division
- School of Advanced Sciences
- VIT University
- Vellore
- India
| | - K. Sathishkumar
- Department of Physics
- Annamalai University
- Chidambaram 608 002
- India
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Dhamodharan P, Gobi R, Shanmugam N, Kannadasan N, Poonguzhali R, Ramya S. Synthesis and characterization of surfactants assisted Cu(2+) doped ZnO nanocrystals. Spectrochim Acta A Mol Biomol Spectrosc 2014; 131:125-131. [PMID: 24825665 DOI: 10.1016/j.saa.2014.04.083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/10/2014] [Accepted: 04/17/2014] [Indexed: 06/03/2023]
Abstract
In the present work, we report a simple chemical precipitation method to synthesize precursors of different levels of Cu(2+) ions doped crystalline zinc oxide (ZnO) nanoparticles in the presence of capping agents namely cetyltrimethyl ammonium bromide (CTAB) and sodium hexametaphosphate (SHMP). Thermal analysis result suggests that 300°C could be the optimum level of annealing for the harvest of pure phase of ZnO from the as prepared particles. The structural, optical and chemical features of undoped and surfactants assisted ZnO: Cu(2+) nanoparticles were studied by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-Visible (UV-Vis) absorption spectroscopy and photoluminescence (PL) measurements. Among the two surfactants used SHMP is an effective one in controlling the size and morphology of the particles.
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Affiliation(s)
- P Dhamodharan
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamil Nadu, India
| | - R Gobi
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamil Nadu, India.
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamil Nadu, India
| | - N Kannadasan
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamil Nadu, India
| | - R Poonguzhali
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamil Nadu, India
| | - S Ramya
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamil Nadu, India
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Viruthagiri G, Gopinathan E, Shanmugam N, Gobi R. Synthesis and characterization of ZrO2-CuO co-doped ceria nanoparticles via chemical precipitation method. Spectrochim Acta A Mol Biomol Spectrosc 2014; 131:556-563. [PMID: 24845731 DOI: 10.1016/j.saa.2014.04.117] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/11/2014] [Accepted: 04/22/2014] [Indexed: 06/03/2023]
Abstract
In the present study, the fluorite cubic phase of bare and ZrO2-CuO co-doped ceria (CeO2) nanoparticles have been synthesized through a simple chemical precipitation method. X-ray diffraction results revealed that average grain sizes of the samples are within 5-6nm range. The functional groups present in the samples were identified by Fourier Transform Infrared Spectroscopy (FTIR) study. Surface area measurement was carried out for the ceria nanoparticles to characterize the surface properties of the synthesized samples. The direct optical cutoff wavelength from DRS analysis was blue-shifted evidently with respect to the bulk material and indicated quantum-size confinement effect in the nanocrystallites. PL spectra revealed the strong and sharp UV emission at 401nm. The surface morphology and the element constitution of the pure and doped nanoparticles were studied by scanning electron microscope fitted with energy dispersive X-ray spectrometer arrangement. The thermal decomposition course was followed using thermo gravimetric and differential thermal analyses (TG-DTA).
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Affiliation(s)
- G Viruthagiri
- Department of Physics, Annamalai University, Annamalai Nagar, 608 002 Tamil Nadu, India.
| | - E Gopinathan
- Department of Physics, Annamalai University, Annamalai Nagar, 608 002 Tamil Nadu, India
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalai Nagar, 608 002 Tamil Nadu, India
| | - R Gobi
- Department of Physics, Annamalai University, Annamalai Nagar, 608 002 Tamil Nadu, India
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Mugundan S, Rajamannan B, Viruthagiri G, Shanmugam N, Gobi R, Praveen P. Synthesis and characterization of undoped and cobalt-doped TiO2 nanoparticles via sol–gel technique. Appl Nanosci 2014. [DOI: 10.1007/s13204-014-0337-y] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Rajamannan B, Mugundan S, Viruthagiri G, Shanmugam N, Gobi R, Praveen P. Preparation, structural and morphological studies of Ni doped titania nanoparticles. Spectrochim Acta A Mol Biomol Spectrosc 2014; 128:218-224. [PMID: 24667428 DOI: 10.1016/j.saa.2014.02.116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 02/04/2014] [Accepted: 02/19/2014] [Indexed: 06/03/2023]
Abstract
TiO2 nanoparticles doped with different weight percentages (4%, 8%, 12% and 16%) of nickel contents were prepared by a modified sol-gel method using Titanium tetra iso propoxide and nickel nitrate as precursors and 2-propanol as a solvent. X-ray diffraction studies show that the as prepared and annealed products show anatase structure with average particle sizes running between of 8 and 16 nm. FTIR results demonstrate the presence of strong chemical bonding at the interface of TiO2 nanoparticles. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the nickel doped TiO2 nanoparticles were studied by scanning electron microscope attached with energy dispersive X-ray spectrometer arrangement. The non linear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).
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Affiliation(s)
- B Rajamannan
- Department of Engineering Physics (FEAT), Annamalai University, Annamalainagar 608002, India.
| | - S Mugundan
- Department of Physics, Annamalai University, Annamalainagar 608002, India
| | - G Viruthagiri
- Department of Physics, Annamalai University, Annamalainagar 608002, India
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalainagar 608002, India
| | - R Gobi
- Department of Physics, Annamalai University, Annamalainagar 608002, India
| | - P Praveen
- Department of Physics, Annamalai University, Annamalainagar 608002, India
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Shanmugam N, Campos AG, Prada-Delgado O, Bizrah M, Valencia O, Jones S, Collinson P, Anderson L. Effect of atrioventricular optimization on circulating N-terminal pro brain natriuretic peptide following cardiac resynchronization therapy. Eur J Heart Fail 2014; 15:534-42. [DOI: 10.1093/eurjhf/hft012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Nesan Shanmugam
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Ana Garcia Campos
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Oscar Prada-Delgado
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Mukhtar Bizrah
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Oswaldo Valencia
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Sue Jones
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Paul Collinson
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
| | - Lisa Anderson
- Department of Cardiology; St George's Healthcare NHS Trust; Blackshaw Road London SW17 0QT UK
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Rajamannan B, Mugundan S, Viruthagiri G, Praveen P, Shanmugam N. Linear and nonlinear optical studies of bare and copper doped TiO2 nanoparticles via sol gel technique. Spectrochim Acta A Mol Biomol Spectrosc 2014; 118:651-656. [PMID: 24096060 DOI: 10.1016/j.saa.2013.09.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/31/2013] [Accepted: 09/07/2013] [Indexed: 06/02/2023]
Abstract
In general, the nanoparticles of TiO2 may exist in the phases of anatase, rutile and brookite. In the present work, we used titanium terta iso propoxide and 2-propanol as a common starting material to prepare the precursors of bare and copper doped nanosized TiO2. Then the synthesized products were calcinated at 500°C and after calcination the pure TiO2 nanoparticles in anatase phase were harvested. The crystallite sizes of bare and copper doped TiO2 nanoparticles were calculated from X-ray diffraction analysis. The existence of functional groups of the samples was identified by Fourier transform infrared spectroscopy. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the copper doped TiO2 nanoparticles were studied by scanning electron microscope fitted with energy dispersive X-ray spectrometer arrangement. The nonlinear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).
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Affiliation(s)
- B Rajamannan
- Department of Engineering Physics (FEAT), Annamalai University, Annamalainagar 608002, India.
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Shanmugam N, Cholan S, Kannadasan N, Sathishkumar K, Viruthagiri G. Luminance behavior of Ce3+ doped ZnS nanostructures. Spectrochim Acta A Mol Biomol Spectrosc 2014; 118:557-563. [PMID: 24084485 DOI: 10.1016/j.saa.2013.09.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/24/2013] [Accepted: 09/02/2013] [Indexed: 06/02/2023]
Abstract
We report the synthesis and characterization of undoped and various levels of Ce(3+) doped ZnS nanocrystal. The structure and size of the products were studied by X-ray diffraction (XRD). The existence of functional groups was identified by Fourier transform infrared spectrometry (FT-IR). The UV-Visible measurements reveal that the synthesized products are blue shifted when compared with bulk phase of ZnS as a result of quantum confinement effect. The PL studies show an enhancement in the intensity of emission band in the UV region on increased Ce(3+) doping. The morphology of the products was evaluated by Field emission scanning electron microscope (FESEM) and High resolution transmission electron microscopy (FESEM). The presence of Ce(3+) was confirmed by Energy dispersive spectral analysis (EDS). The thermal stability of pure and doped products was analyzed by thermo gravimetric and differential thermal analysis (TG-DTA).
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Affiliation(s)
- N Shanmugam
- Department of Physics, Annamalai University, Annamalai Nagar, Chidambaram 608 002, Tamilnadu, India.
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Praveen P, Viruthagiri G, Mugundan S, Shanmugam N. Structural, optical and morphological analyses of pristine titanium di-oxide nanoparticles--synthesized via sol-gel route. Spectrochim Acta A Mol Biomol Spectrosc 2014; 117:622-9. [PMID: 24113014 DOI: 10.1016/j.saa.2013.09.037] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 08/31/2013] [Accepted: 09/07/2013] [Indexed: 05/27/2023]
Abstract
Pure titanium di-oxide nanoparticles (TiO2) were synthesized by sol-gel technique at room temperature with appropriate reactants. The synthesis of anatase phase TiO2 nanoparticles was achieved by tetraisopropyl orthotitanate and 2-propanol as common starting materials and the product was annealed at 450 °C for 4 h. The synthesized product was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), UV-VIS-Diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy and Scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX) analysis. XRD pattern confirmed the crystalline nature and tetragonal structure of synthesized composition. Average grain size was determined from X-ray line broadening, using the Debye-Scherrer relation. The functional groups present in the sample were identified by FTIR spectroscopy. Diffuse reflectance measurement indicated an absorption band edge on UV-region. The allowed direct and indirect band gap energies, as well as the crystallite size of pure TiO2 nanoparticles are calculated from DRS analysis. The microstructure and elemental identification were done by SEM with EDX analysis.
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Affiliation(s)
- P Praveen
- Department of Physics, Annamalai University, Annamalainagar 608002, Tamilnadu, India
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Praveen P, Viruthagiri G, Mugundan S, Shanmugam N. Sol-gel synthesis and characterization of pure and manganese doped TiO2 nanoparticles--a new NLO active material. Spectrochim Acta A Mol Biomol Spectrosc 2013; 120:548-557. [PMID: 24374482 DOI: 10.1016/j.saa.2013.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 11/30/2013] [Accepted: 12/04/2013] [Indexed: 06/03/2023]
Abstract
Pure and Manganese (4%, 8%, 12% and 16%) doped titanium di-oxide (Mn-TiO2) nanoparticles were synthesized by sol-gel technique. The preparation of pure and Mn doped TiO2 nanoparticles were achieved by tetra-isopropyl orthotitanate and 2-propanol as common starting materials and the products were annealed at 450°C and 750°C to get anatase and rutile phases, respectively. The prepared materials were characterized by X-ray diffraction analysis (XRD), Fourier transform infra-red spectroscopy (FT-IR), UV-VIS-Diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy, Scanning electron microscopy (SEM) with Energy dispersive X-ray analysis (EDX) and Kurtz powder second harmonic generation (SHG) test. XRD patterns confirmed the crystalline nature and tetragonal structure of synthesized materials. The functional groups present in the samples were identified by FTIR study. The allowed direct and indirect band gap energies, as well as the crystallite sizes of obtained nanoparticles were calculated from DRS analysis. Microstructures and elemental identification were done by SEM with EDX analysis. The existence of SHG signals was observed using Nd: YAG laser with fundamental wavelength of 1064 nm. The products were found to be transparent in the entire visible region with cut-off wavelengths within the UV region confirms its suitability for device fabrications.
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Affiliation(s)
- P Praveen
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
| | - G Viruthagiri
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India.
| | - S Mugundan
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
| | - N Shanmugam
- Department of Physics, Annamalai University, Annamalai Nagar 608002, Tamilnadu, India
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Shanmugam N, Rajkamal P, Cholan S, Kannadasan N, Sathishkumar K, Viruthagiri G, Sundaramanickam A. Biosynthesis of silver nanoparticles from the marine seaweed Sargassum wightii and their antibacterial activity against some human pathogens. Appl Nanosci 2013. [DOI: 10.1007/s13204-013-0271-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Yap J, Chia SY, Go YY, Shanmugam N, Sim LL, Lim CP, Sim D, Liew R, Ching CK. Predictors of two-year mortality in Asian patients with heart failure and preserved ejection fraction. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht308.p1521] [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: 11/13/2022] Open
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Ojaghi-Haghighi Z, Mostafavi A, Moladoust H, Noohi F, Maleki M, Esmaeilzadeh M, Samiei N, Hosseini S, Jasaityte R, Teske A, Claus P, Verheyden B, Rademakers F, D'hooge J, Patrianakos A, Zacharaki A, Kalogerakis A, Nyktari E, Maniatakis P, Parthenakis F, Vardas P, Hilde JM, Skjoerten I, Humerfelt S, Hansteen V, Melsom M, Hisdal J, Steine K, Ippolito R, Gripari P, Muraru D, Esposito R, Kocabay G, Tamborini G, Galderisi M, Maffessanti F, Badano L, Pepi M, Yurdakul S, Oner F, Sahin T, Avci B, Tayyareci Y, Direskeneli H, Aytekin S, Filali T, Jedaida B, Lahidheb D, Gommidh M, Mahfoudhi H, Hajlaoui N, Dahmani R, Fehri W, Haouala H, Andova V, Georgievska-Ismail L, Srbinovska-Kostovska E, Gardinger Y, Joanna Hlebowicz J, Ola Bjorgell O, Magnus Dencker M, Liao MT, Tsai CT, Lin JL, Piestrzeniewicz K, Luczak K, Maciejewski M, Komorowski J, Jankiewicz-Wika J, Drozdz J, Ismail MF, Alasfar A, Elassal M, El-Sayed S, Ibraheim M, Dobrowolski P, Klisiewicz A, Florczak E, Prejbisz A, Szwench E, Rybicka J, Januszewicz A, Hoffman P, Santos Furtado M, Nogueira K, Arruda A, Rodrigues AC, Carvalho F, Silva M, Cardoso A, Lira-Filho E, Pinheiro J, Andrade JL, Mohammed M, Zito C, Cusma-Piccione M, Di Bella G, Taha N, Zagari D, Oteri A, Quattrone A, Boretti I, Carerj S, Obremska O, Boratynska B, Poczatek P, Zon Z, Magott M, Klinger K, Szenczi O, Szelid Z, Soos P, Bagyura Z, Edes E, Jozan P, Merkely B, Ahn J, Kim D, Jeon D, Kim I, Baeza Garzon F, Delgado M, Mesa D, Ruiz M, De Lezo JS, Pan M, Leon C, Castillo F, Morenate M, Toledano F, Zhong L, Lim E, Shanmugam N, Law S, Ong B, Katwadi K, Tan R, Chua Y, Liew R, Ding Z, Von Bibra H, Leclerque C, Schuster T, Schumm-Draeger PM, Bonios M, Kaladaridou A, Papadopoulou O, Tasoulis A, Pamboucas C, Ntalianis A, Nanas J, Toumanidis S, Silva D, Cortez-Dias N, Carrilho-Ferreira P, Placido R, Jorge C, Calisto C, Robalo Martins S, Carvalho De Sousa J, Pinto F, Nunes Diogo A, Przewlocka-Kosmala M, Orda A, Karolko B, Mysiak A, Kosmala W, Moral Torres S, Rodriguez-Palomares J, Pineda V, Gruosso D, Evangelista A, Garcia-Dorado D, Figueras J, Cambronero E, Corbi MJ, Valle A, Cordoba J, Llanos C, Fernandez M, Lopez I, Hidalgo V, Barambio M, Jimenez J, D'andrea A, Riegler L, Cocchia R, Russo M, Bossone E, Calabro R, Iniesta Manjavacas A, Valbuena Lopez S, Lopez Fernandez T, Garcia-Blas S, De Torres Alba F, De Diego JG, Ramirez Valdiris U, Mesa Garcia J, Moreno Yanguela M, Lopez-Sendon J, Logstrup B, Andersen H, Thuesen L, Christiansen E, Terp K, Klaaborg K, Poulsen S, Cacicedo A, Velasco S, Aguirre U, Onaindia J, Rodriguez I, Oria G, Subinas A, Zugazabeitia G, Romero A, Laraudogoitia Zaldumbide E, Weisz S, Magne J, Dulgheru R, Rosca M, Pierard L, Lancellotti P, Auffret V, Donal E, Bedossa M, Boulmier D, Laurent M, Verhoye J, Le Breton H, Van Hall S, Herbrand T, Ketterer U, Keymel S, Boering Y, Rassaf T, Meyer C, Zeus T, Kelm M, Balzer J, Floria M, Seldrum S, Mariciuc M, Laurence G, Buche M, Eucher P, Louagie Y, Jamart J, Marchandise B, Schroeder E, Venkatesh A, Sahlen A, Johnson J, Brodin L, Winter R, Shahgaldi K, Manouras A, Maffessanti F, Tamborini G, Fusini L, Gripari P, Muratori M, Alamanni F, Bartorelli A, Ferrari C, Caiani E, Pepi M, Yaroslavskaya E, Kuznetsov V, Pushkarev G, Krinochkin D, Zyrianov I, Ciobotaru C, Kobayashi Y, Yamamoto K, Kobayashi Y, Hirose E, Hirohata A, Ohe T, Jhund P, Cunningham T, Murday V, Findlay I, Sonecki P, Rangel I, Sousa C, Goncalves A, Correia A, Vigario A, Martins E, Silva-Cardoso J, Macedo F, Maciel M, Lovric D, Samardzic J, Milicic D, Reskovic V, Baricevic Z, Ivanac I, Separovic Hanzevacki J, Kim K, Song J, Jeong H, Yoon H, Ahn Y, Jeong M, Cho J, Park J, Kang J, Iorio A, Pinamonti B, Bobbo M, Merlo M, Barbati G, Massa L, Faganello G, Di Lenarda A, Sinagra G, Heggemann F, Hamm K, Streitner F, Sueselbeck T, Papavassiliu T, Borggrefe M, Haghi D, Ferreira F, Galrinho A, Soares R, Branco L, Abreu J, Feliciano J, Papoila A, Alves M, Leal A, Ferreira R, Reynaud A, Donal E, Lund LH, Oger E, Drouet E, Hage C, Bauer F, Linde C, Daubert J, Schnell F, Donal E, Lentz P, Kervio G, Leurent G, Mabo P, Carre F, Rodrigues A, Roque M, Arruda A, Becker D, Barros S, Kay F, Emerick T, Pinheiro J, Sampaio-Barros P, Andrade J, Yamada S, Okada K, Iwano H, Nishino H, Nakabachi M, Yokoyama S, Kaga S, Mikami T, Tsutsui H, Mincu R, Magda S, Dumitrache Rujinski S, Constantinescu T, Mihaila S, Ciobanu A, Florescu M, Vinereanu D, Ashcheulova T, Kovalyova O, Ardeleanu E, Gurgus D, Gruici A, Suciu R, Ana I, Bergenzaun L, Ohlin H, Gudmundsson P, Willenheimer R, Chew M, Charalampopoulos A, Howard L, Davies R, Gin-Sing W, Tzoulaki I, Grapsa I, Gibbs S, Caiani E, Massabuau P, Weinert L, Lairez O, Berry M, Sotaquira M, Vaida P, Lang R, Khan I, Waterhouse D, Asegdom S, Alqaseer M, Foley D, Mcadam B, Colonna P, Michelotto E, Genco W, Rubino M, Pugliese S, Belfiore A, Sorino M, Trisorio Liuzzi M, Antonelli G, Palasciano G, Duszanska A, Skoczylas I, Streb W, Kukulski T, Polonski L, Kalarus Z, Fleig A, Seitz K, Secades S, Martin M, Corros C, Rodriguez M, De La Hera J, Garcia A, Velasco E, Fernandez E, Barriales V, Lambert J, Zwas DR, Hoss S, Leibowitz D, Beeri R, Lotan C, Gilon D, Wierzbowska-Drabik K, Roszczyk N, Sobczak M, Plewka M, Chrzanowski L, Lipiec P, Kasprzak J, Wita K, Mizia-Stec K, Wrobel W, Plonska-Gosciniak E, Goncalves A, Sousa C, Rangel I, Pinho T, Wang Y, Houle H, Madureira AJ, Macedo F, Zamorano J, Maciel MJ, Ancona R, Comenale Pinto S, Caso P, Coppola M, Rapisarda O, Calabro' R, Cadenas Chamorro R, Lopez T, Gomez J, Moreno M, Salinas P, Jimenez Rubio C, Valbuena S, Manjavacas A, De Torres F, Lopez-Sendon J, Vaugrenard T, Huttin O, Rouge A, Schwartz J, Zinzius P, Popovic B, Sellal J, Aliot E, Juilliere Y, Selton-Suty C, Looi J, Lee A, Hsiung M, Song W, Wong R, Underwood MJ, Fang F, Lin Q, Lam Y, Yu C, Vitarelli A, Nguyen B, Capotosto L, D-Alessandro G, D-Ascanio M, Rafique A, Gang E, Barilla F, Siegel R, Kydd A, Khan F, Watson W, Mccormick L, Virdee M, Dutka D, Ranjbar S, Karvandi M, Hassantash S, Grapsa J, Efthimiadis I, Pakrashi T, Dawson D, Punjabi P, Nihoyannopoulos P, Jasaityte R, D'hooge J, Rademakers F, Claus P, Henein M, Soderberg S, Tossavainen E, Henein M, Lindqvist P, Bellsham-Revell H, Bell A, Miller O, Simpson J, Altekin E, Kucuk M, Yanikoglu A, Karakas S, Er A, Ozel D, Ermis C, Demir I, Henein M, Soderberg S, Henein M, Lindqvist P, Bajraktari G, Di Salvo G, Baldini L, Del Gaizo F, Rea A, Pergola V, Caso P, Pacileo G, Fadel B, Calabro R, Russo M, Seo JS, Choi GN, Jin HY, Seol SH, Jang JS, Yang TH, Kim DK, Kim DS, Papadopoulou E, Kaladaridou A, Hatzidou S, Agrios J, Pamboukas C, Antoniou A, Toumanidis S, Gargiulo P, Dellegrottaglie S, Bruzzese D, Scala O, D'amore C, Ruggiero D, Marciano C, Vassallo E, Pirozzi E, Perrone Filardi P, Mor-Avi V, Kachenoura N, Lodato J, Port S, Chandra S, Freed B, Bhave N, Newby B, Lang R, Patel A, Dwivedi G, Alam M, Boczar K, Chow B, Staskiewicz G, Czekajska-Chehab E, Uhlig S, Tomaszewski A, Przegalinski J, Maciejewski R, Drop A, Di Giammarco G, Canosa C, Foschi M, Liberti G, Bedir M, Marinelli D, Masuyama S, Rabozzi R, Vijayan S, Miller H, Muthusamy R, Smith S, Gargani L, Pang P, Davis E, Schumacher A, Sicari R, Picano E, Mizia-Stec K, Chmiel A, Mizia M, Haberka M, Gieszczyk K, Sikora - Puz A, Lasota B, Trojnarska O, Grajek S, Gasior Z, Koumoulidis A, Vlasseros I, Tousoulis D, Katsi V, Avgeropoulou A, Divani M, Stefanadis C, Kallikazaros I. Poster session Thursday 6 December - AM: Other myocardial diseases. Eur Heart J Cardiovasc Imaging 2012. [DOI: 10.1093/ehjci/jes255] [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: 11/14/2022] Open
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Shanmugam N, Prada-Delgado O, Campos AG, Grimster A, Valencia O, Baltabaeva A, Jones S, Anderson L. Rate-adaptive AV delay and exercise performance following cardiac resynchronization therapy. Heart Rhythm 2012; 9:1815-21. [PMID: 22772135 DOI: 10.1016/j.hrthm.2012.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Indexed: 11/30/2022]
Affiliation(s)
- Nesan Shanmugam
- Department of Cardiology, St George's Healthcare NHS Trust, London, United Kingdom.
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Shanmugam N, Liew R. The Implantable Loop Recorder—An Important Addition to the Armentarium in the Management of Unexplained Syncope. Ann Acad Med Singap 2012. [DOI: 10.47102/annals-acadmedsg.v41n3p115] [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] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Introduction: Unexplained syncope is a common condition with a significant impact both on the patient and on healthcare expenditure. Often, the diagnosis is hampered due to the temporary sporadic nature of the symptoms. Conventional monitoring methods have a low yield for identifying an abnormality during a spontaneous event. The implantable loop recorder (ILR), often underutilised, is an important diagnostic device that may fill this void in the early assessment of patients presenting with syncope. Materials and Methods: This article begins with 2 case vignettes which highlight the clinical utility of ILRs in making a definitive diagnosis and guiding subsequent management. This is followed by a review of the existing evidence for ILRs, including the recent international guidelines, underpinning the role of ILRs in the present management algorithm of patients presenting with unexplained syncope. The technical aspects and cost implications will also be reviewed. Results: Present evidence-based international guidelines have recommended the early use of ILRs in the management of patients with unexplained syncope. Furthermore, there may also be an important role for ILR use in patients with presumed epilepsy refractory to treatment and in the neurally mediated syncope cohort with recurrent symptoms. Cost benefit analysis also demonstrates advantages with early ILR use. Conclusion: The early use of ILR in selected patients remains an accurate, cost-effective, high yield tool for diagnosis and management of patients with unexplained syncope. However, its use should not detract from the importance of taking a detailed medical history and physical examination in the initial assessment to facilitate identification of the aetiology and risk stratification of patients.
Key words: Electrophysiological study, Epilepsy, External loop recorder, Holter, Tilt testing
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Shanmugam N, Liew R. The implantable loop recorder-an important addition to the armentarium in the management of unexplained syncope. Ann Acad Med Singap 2012; 41:115-124. [PMID: 22538738] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Unexplained syncope is a common condition with a significant impact both on the patient and on healthcare expenditure. Often, the diagnosis is hampered due to the temporary sporadic nature of the symptoms. Conventional monitoring methods have a low yield for identifying an abnormality during a spontaneous event. The implantable loop recorder (ILR), often underutilised, is an important diagnostic device that may fi ll this void in the early assessment of patients presenting with syncope. MATERIALS AND METHODS This article begins with 2 case vignettes which highlight the clinical utility of ILRs in making a definitive diagnosis and guiding subsequent management. This is followed by a review of the existing evidence for ILRs, including the recent international guidelines, underpinning the role of ILRs in the present management algorithm of patients presenting with unexplained syncope. The technical aspects and cost implications will also be reviewed. RESULTS Present evidence-based international guidelines have recommended the early use of ILRs in the management of patients with unexplained syncope. Furthermore, there may also be an important role for ILR use in patients with presumed epilepsy refractory to treatment and in the neurally mediated syncope cohort with recurrent symptoms. Cost benefit analysis also demonstrates advantages with early ILR use. CONCLUSION The early use of ILR in selected patients remains an accurate, cost-effective, high yield tool for diagnosis and management of patients with unexplained syncope. However, its use should not detract from the importance of taking a detailed medical history and physical examination in the initial assessment to facilitate identification of the aetiology and risk stratification of patients.
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Shanmugam N, Boerdlein A, Proff J, Ong P, Valencia O, Maier SKG, Bauer WR, Paul V, Sack S. Detection of atrial high-rate events by continuous home monitoring: clinical significance in the heart failure-cardiac resynchronization therapy population. Europace 2011; 14:230-7. [PMID: 21933802 PMCID: PMC3262405 DOI: 10.1093/europace/eur293] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIMS Uncertainty exists over the importance of device-detected short-duration atrial arrhythmias. Continuous atrial diagnostics, through home monitoring (HM) technology (BIOTRONIK, Berlin, Germany), provides a unique opportunity to assess frequency and quantity of atrial fibrillation (AF) episodes defined as atrial high-rate events (AHRE). METHODS AND RESULTS Prospective data from 560 heart failure (HF) patients (age 67 ± 10 years, median ejection fraction 27%) patients with a cardiac resynchronization therapy (CRT) device capable of HM from two multi-centre studies were analysed. Atrial high-rate events burden was defined as the duration of mode switch in a 24-h period with atrial rates of >180 beats for at least 1% or total of 14 min per day. The primary endpoint was incidence of a thromboembolic (TE) event. Secondary endpoints were cardiovascular death, hospitalization because of AF, or worsening HF. Over a median 370-day follow-up AHRE occurred in 40% of patients with 11 (2%) patients developing TE complications and mortality rate of 4.3% (24 deaths, 16 with cardiovascular aetiology). Compared with patients without detected AHRE, patients with detected AHRE>3.8 h over a day were nine times more likely to develop TE complications (P= 0.006). The majority of patients (73%) did not show a temporal association with the detected atrial episode and their adverse event, with a mean interval of 46.7 ± 71.9 days (range 0-194) before the TE complication. CONCLUSION In a high-risk cohort of HF patients, device-detected atrial arrhythmias are associated with an increased incidence of TE events. A cut-off point of 3.8 h over 24 h was associated with significant increase in the event rate. Routine assessment of AHRE should be considered with other data when assessing stroke risk and considering anti-coagulation initiation and should also prompt the optimization of cardioprotective HF therapy in CRT patients.
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Affiliation(s)
- Nesan Shanmugam
- Department of Cardiology, St George's Healthcare NHS Trust, London, UK
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Ignacimuthu S, Shanmugam N. Antimycobacterial activity of two natural alkaloids, vasicine acetate and 2-acetyl benzylamine, isolated from Indian shrub Adhatoda vasica Ness. leaves. J Biosci 2011; 35:565-70. [PMID: 21289439 DOI: 10.1007/s12038-010-0065-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In folk medicine, Adhatoda vasica Ness. (Acanthaceae) is used to treat asthma and cough. The leaves of A. vasica were powdered and extracted with hexane, ethyl acetate and methanol. The hexane extract showed 97 percent reduction in colony-forming units (CFU) at 100 microg/ml. The hexane extract was subjected to column chromatography. Two natural compounds, vasicine acetate and 2-acetyl benzylamine, were isolated from it. They were bioassayed against Mycobacterium tuberculosis. The two compounds showed strong antimycobacterial activity. Vasicine acetate and 2-acetyl benzylamine isolated from hexane extract of A. vasica leaves, significantly inhibited M. tuberculosis and one multi-drug-resistant (MDR) strain and one sensitive strain at 200 and 50 microg/ml, respectively. Our study demonstrated that both the compounds, vasicine acetate and 2-acetyl benzylamine, could be evaluated further for developing a drug to control M. tuberculosis.
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Affiliation(s)
- S Ignacimuthu
- Division of Ethnopharmacology, Entomology Research Institute, Loyola College, Chennai 600 034, India.
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Govindan M, Batchvarov VN, Raju H, Shanmugam N, Bizrah M, Bastiaenen R, Kiotsekoglou A, Camm J, Behr ER. Utility of high and standard right precordial leads during ajmaline testing for the diagnosis of Brugada syndrome. Heart 2010; 96:1904-8. [PMID: 20962343 DOI: 10.1136/hrt.2010.201244] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [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: 11/04/2022] Open
Abstract
AIMS The authors sought to assess the value of the high right precordial leads (RPL) to detect the Type I Brugada ECG pattern in patients suspected of carrying Brugada syndrome (BrS). METHODS Ajmaline testing using 15-lead ECGs was performed in 183 patients suspected of carrying BrS. Standard 12-lead ECG with V1-V3 recorded from the fourth intercostal space and an additional three leads placed over V1-V3 recorded from the third intercostal space were analysed. ECGs were analysed for a Type I ECG pattern in either the standard or high RPLs. RESULTS Of the 183 tests, 31 (17%) were positive, and 152 were negative. In all positive studies, at least one high RPL became positive. In 13/31 (42%) cases, the Type I ECG pattern could be observed only in the high RPLs. Standard or high V3 were never positive before standard or high V1-V2. In seven patients, a Type I pattern was seen in one standard and one high RPL (vertical relationship). CONCLUSIONS The high RPLs are more sensitive than the conventional 12-lead ECG alone and initial observations suggest that they remain specific for BrS, while standard and high lead V3 offer redundant data. A vertical relationship of type 1 patterns may have a similar diagnostic value to that of a horizontal pair.
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Affiliation(s)
- Malini Govindan
- Division of Cardiac and Vascular Sciences, St George's University of London, Cranmer Terrace, London, UK.
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Figarola JL, Loera S, Weng Y, Shanmugam N, Natarajan R, Rahbar S. LR-90 prevents dyslipidaemia and diabetic nephropathy in the Zucker diabetic fatty rat. Diabetologia 2008; 51:882-91. [PMID: 18317729 DOI: 10.1007/s00125-008-0935-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 01/08/2008] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS Previous studies have shown that LR-90, a new inhibitor of AGE formation, prevented the development of experimental type 1 diabetic nephropathy. In this study, we examined the effects of LR-90 in the Zucker diabetic fatty (ZDF) rat, a model of type 2 diabetes and metabolic syndrome, and investigated the mechanisms by which it may protect against renal injury. METHODS Male ZDF rats were treated without or with LR-90 from age 13 to 40 weeks. Metabolic and kidney functions and renal histology were evaluated. AGE accumulation and the production of the receptor for AGE (AGER) were measured. Profibrotic growth factors, extracellular matrix proteins and intracellular signalling pathways associated with glomerular and tubular damage were also analysed. RESULTS LR-90 dramatically reduced plasma lipids in ZDF rats, with only modest effects on hyperglycaemia. Renal AGE, AGER and lipid peroxidation were all attenuated by LR-90. LR-90 significantly retarded the increase in albuminuria and proteinuria. This was associated with reduction in glomerulosclerosis and tubulointerstitial fibrosis, concomitant with marked inhibition of renal overproduction of TGF-beta1, connective tissue growth factor, fibronectin and collagen IV. Additionally, LR-90 downregulated the activation of key mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kappaB) in the renal cortex. CONCLUSIONS/INTERPRETATION These results support our earlier studies on the renoprotective effects of LR-90 on type 1 diabetic nephropathy and provide further evidence that LR-90, an AGE inhibitor with pleiotrophic effects, may also be beneficial for the prevention of type 2 diabetic nephropathy, where multiple risk factors, such as hyperglycaemia, dyslipidaemia, obesity, insulin resistance and hypertension, contribute to renal injury.
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Affiliation(s)
- J L Figarola
- Department of Diabetes, Endocrinology and Metabolism, Gonda Building, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010, USA
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Xu ZG, Li SL, Lanting L, Kim YS, Shanmugam N, Reddy MA, Natarajan R. Relationship between 12/15-lipoxygenase and COX-2 in mesangial cells: potential role in diabetic nephropathy. Kidney Int 2006; 69:512-9. [PMID: 16514433 DOI: 10.1038/sj.ki.5000137] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [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: 01/11/2023]
Abstract
The 12/15-lipoxygenase (12/15-LO) and cyclooxygenase-2 (COX-2) pathways of arachidonate metabolism have been implicated in the pathogenesis of diabetic nephropathy (DN). In this study, we evaluated whether there is an interplay between 12/15-LO and COX-2 pathways in mesangial cells (MC). We utilized MC, microdissected glomeruli and renal cortical tissues. Transfections with cDNAs or short hairpin RNAs (shRNAs) were performed to overexpress or knockdown 12/15-LO and COX-2, respectively. Reverse transcription-polymerase chain reactions and Western blotting were used for evaluating mRNA and protein expression, respectively. We observed that the expression of both 12/15-LO and COX-2 were increased in high glucose stimulated rat MC relative to normal glucose, and also in cortical tissues from diabetic db/db and streptozotocin-injected mice relative to corresponding control mice. Treatment of rat MC with the 12/15-LO product, 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), significantly increased COX-2 expression as well as levels of the COX-2 product, prostaglandin E(2) (PGE(2)). Interestingly, treatment of rat MC with PGE(2) led to a reciprocal increase in 12/15-LO expression as well as levels of 12(S)-HETE. The 12/15-LO shRNA could significantly attenuate COX-2 protein expression and vice versa. Furthermore, COX-2 expression levels were lower in MC and glomeruli from 12/15-LO knockout mice relative to control. Conversely, mouse MC stably overexpressing 12/15-LO had greater levels of COX-2 expression relative to mock-transfected cells. These new results indicate for the first time that 12/15-LO and COX-2 pathways can cross-talk and activate each other in MC. These novel interactions may amplify their effects on the progression of DN.
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MESH Headings
- 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/pharmacology
- Animals
- Arachidonate 12-Lipoxygenase/genetics
- Arachidonate 12-Lipoxygenase/metabolism
- Arachidonate 15-Lipoxygenase/genetics
- Arachidonate 15-Lipoxygenase/metabolism
- Cells, Cultured
- Cyclooxygenase 2/analysis
- Cyclooxygenase 2/genetics
- Cyclooxygenase 2/physiology
- Diabetes Mellitus, Experimental/enzymology
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Experimental/physiopathology
- Diabetic Nephropathies/enzymology
- Diabetic Nephropathies/etiology
- Diabetic Nephropathies/physiopathology
- Dinoprostone/pharmacology
- Enzyme Activation/drug effects
- Enzyme Activation/physiology
- Gene Expression Regulation, Enzymologic/drug effects
- Glucose/pharmacology
- Kidney Cortex/enzymology
- Kidney Cortex/pathology
- Kidney Cortex/physiology
- Male
- Mesangial Cells/enzymology
- Mesangial Cells/pathology
- Mesangial Cells/physiology
- Mice
- Mice, Inbred C57BL
- Mitogen-Activated Protein Kinase Kinases/analysis
- Mitogen-Activated Protein Kinase Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinase Kinases/physiology
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/physiology
- Transfection
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Affiliation(s)
- Z-G Xu
- Gonda Diabetes Research Center, Beckman Research Institute of the City of Hope, Duarte, California, USA
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Shanmugam N, Chua TP, Ward D. 'Frequent' ventricular bigeminy--a reversible cause of dilated cardiomyopathy. How frequent is 'frequent'? Eur J Heart Fail 2006; 8:869-73. [PMID: 16714145 DOI: 10.1016/j.ejheart.2006.02.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2005] [Revised: 01/30/2006] [Accepted: 02/09/2006] [Indexed: 11/29/2022] Open
Abstract
An interesting development in the field of heart failure has been the link between frequent premature ventricular contractions and cardiomyopathy. We report a patient whose frequent ventricular bigeminy resulted in left ventricular impairment that resolved after the use of non-contact mapping during radiofrequency ablation. A review of the literature regarding possible mechanisms is discussed. For the practicing clinician, the question of 'frequent' should be taken in context of symptoms and LV function. A single 24-h Holter monitor may not truly reflect the ectopic load. We recommend that if there is associated LV dysfunction and a causal link to frequent PVCs then suppression with radiofrequency ablation is a safe and effective treatment strategy.
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Affiliation(s)
- N Shanmugam
- Royal Surrey County Hospital, Guildford, United Kingdom.
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Shanmugam N, Todorov IT, Nair I, Omori K, Reddy MA, Natarajan R. Increased expression of cyclooxygenase-2 in human pancreatic islets treated with high glucose or ligands of the advanced glycation endproduct-specific receptor (AGER), and in islets from diabetic mice. Diabetologia 2006; 49:100-7. [PMID: 16341840 DOI: 10.1007/s00125-005-0065-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Accepted: 08/30/2005] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS The cyclooxygenase-2 (PTGS2, previously known as COX2) enzyme and its products, such as prostaglandin E(2) (PGE(2)), have been implicated in the pathogenesis of several inflammatory diseases including islet dysfunction under diabetic conditions. In this study we evaluated whether diabetic conditions in vitro, such as high-glucose (HG) culture or AGE, or in vivo in animal models of diabetes can induce PTGS2 expression and activity in pancreatic islets. MATERIALS AND METHODS Isolated human pancreatic islets were treated for 24 h with HG (25 mmol/l) or with S100b (5 mg/l), a specific ligand for the AGE-specific receptor. PTGS2 and cyclooxygenase-1 (PTGS1, previously known as COX1) mRNA, protein expression and product PGE(2) were analysed by RT-PCR, Western blots and specific enzyme immunoassay respectively. Islet PTGS2 production in animal models was assessed by immunofluorescence. RESULTS Treatment of human pancreatic islets with HG and S100b led to a three-five-fold induction of PTGS2 mRNA (p<0.001). PTGS2 protein and its product PGE(2) (351.4+/-13.05 fg/ml vs control 39.4+/-0.11 fg/ml) were also increased (p<0.001). Pretreatment with specific inhibitors demonstrated the involvement of protein kinase C and oxidant stress in S100b- and HG-induced PTGS2 expression. However, insulin secretion was not significantly altered by S100b. Double immunofluorescent staining showed increased PTGS2 production in pancreatic islets from diabetic mice relative to corresponding controls. CONCLUSION/INTERPRETATION These results show for the first time that diabetes as well as diabetic conditions such as AGE and HG in vitro can directly upregulate the expression of the inflammatory PTGS2 gene in pancreatic islets. This might contribute to the pathogenesis of islet dysfunction in diabetes.
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Affiliation(s)
- N Shanmugam
- Gonda Diabetes Centre, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
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Griewe GL, Dean RC, Zhang W, Young D, Sesterhenn IA, Shanmugam N, McLeod DG, Moul JW, Srivastava S. p53 Immunostaining guided laser capture microdissection (p53-LCM) defines the presence of p53 gene mutations in focal regions of primary prostate cancer positive for p53 protein. Prostate Cancer Prostatic Dis 2004; 6:281-5. [PMID: 14663467 DOI: 10.1038/sj.pcan.4500665] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [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: 11/09/2022]
Abstract
OBJECTIVES A wide range of p53 mutations (5-65%), detected by various methods, has been reported in primary prostate cancers (CaP). IHC staining of radical prostatectomy specimens shows marked heterogeneity of focally distributed p53-positive cells. However, a significant relationship between the focal staining of p53 and cancer recurrence after radical prostatectomy has been noted. Increased frequency of p53 mutations has been generally observed in advanced stage CaP and metastatic prostate cancer cell lines. The significance of focal p53 immunostaining in primary CaP remains uncertain with respect to the p53 gene mutation or tumor progression. The goal of this study was to evaluate p53 gene mutations in focal regions of primary prostate cancers positive by p53 immunostaining. METHODS Whole-mount prostates from men with clinically organ-confined prostate cancer were immunostained for p53 protein. Laser capture microdissection (LCM) was used to harvest p53 positive cells from areas of tumor and prostatic intraepithelial neoplasia and benign gland. DNA from microdissected cells were amplified for p53 exons 5-8 by polymerase chain reaction (PCR) and analyzed for mutations by single strand conformation polymorphism and DNA sequencing. Mutation analysis of the p53 gene exons 5-8 was performed in the p53 immunostaining positive focal regions (1+ to 4+) of whole-mount prostate sections from 16 patients. RESULTS Of 16 patients with p53 IHC positive tumors, 11 (69%) had p53 gene mutations as determined by DNA sequence analysis. However, randomly microdissected tumor cells from 4 of 18 patients (22%) negative for p53 IHC also demonstrated mutations in the p53 gene. A significant fraction of prostate tumors with focally positive immunostaining for p53 have been confirmed to contain mutations in the p53 gene. CONCLUSIONS p53 immunostaining guided LCM combined with DNA-based analyses emphasizes the presence of focal p53 mutations in primary prostate cancers and underscores the significance of previous observations showing a correlation between focal p53 immunostaining in primary CaP and cancer recurrence after radical prostatectomy.
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Affiliation(s)
- G L Griewe
- Urology Service, Department of Surgery, Walter Reed Army Medical Center, 6825 Georgia Ave, NW, Washington, District of Columbia, USA
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