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Sample records for helix-based fibrils driven

  1. High-Pressure-Driven Reversible Dissociation of α-Synuclein Fibrils Reveals Structural Hierarchy.

    Science.gov (United States)

    Piccirilli, Federica; Plotegher, Nicoletta; Ortore, Maria Grazia; Tessari, Isabella; Brucale, Marco; Spinozzi, Francesco; Beltramini, Mariano; Mariani, Paolo; Militello, Valeria; Lupi, Stefano; Perucchi, Andrea; Bubacco, Luigi

    2017-10-17

    The analysis of the α-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils. High pressure (in the kbar range) and alkaline pH were used to disassemble fibrils to collect information on the hierarchic pathway by which distinct β-sheets sequentially unfold using the unique possibility offered by high-pressure Fourier transform infrared spectroscopy. The results point toward the formation of kinetic traps in the energy landscape of aS fibril disassembly and the presence of transient partially folded species during the process. Since we found that the dissociation of wild-type aS fibrils by high pressure is reversible upon pressure release, the disassembled molecules likely retain structural information that favors fibril reformation. To deconstruct the role of the different regions of aS sequence in this process, we measured the high-pressure dissociation of amyloids formed by covalent chimeric dimers of aS (syn-syn) and by the aS deletion mutant that lacks the C-terminus, i.e., aS (1-99). The results allowed us to single out the role of dimerization and that of the C-terminus in the complete maturation of fibrillar aS. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  2. Atrial fibrillation driven by micro-anatomic intramural re-entry revealed by simultaneous sub-epicardial and sub-endocardial optical mapping in explanted human hearts.

    Science.gov (United States)

    Hansen, Brian J; Zhao, Jichao; Csepe, Thomas A; Moore, Brandon T; Li, Ning; Jayne, Laura A; Kalyanasundaram, Anuradha; Lim, Praise; Bratasz, Anna; Powell, Kimerly A; Simonetti, Orlando P; Higgins, Robert S D; Kilic, Ahmet; Mohler, Peter J; Janssen, Paul M L; Weiss, Raul; Hummel, John D; Fedorov, Vadim V

    2015-09-14

    The complex architecture of the human atria may create physical substrates for sustained re-entry to drive atrial fibrillation (AF). The existence of sustained, anatomically defined AF drivers in humans has been challenged partly due to the lack of simultaneous endocardial-epicardial (Endo-Epi) mapping coupled with high-resolution 3D structural imaging. Coronary-perfused human right atria from explanted diseased hearts (n = 8, 43-72 years old) were optically mapped simultaneously by three high-resolution CMOS cameras (two aligned Endo-Epi views (330 µm2 resolution) and one panoramic view). 3D gadolinium-enhanced magnetic resonance imaging (GE-MRI, 80 µm3 resolution) revealed the atrial wall structure varied in thickness (1.0 ± 0.7-6.8 ± 2.4 mm), transmural fiber angle differences, and interstitial fibrosis causing transmural activation delay from 23 ± 11 to 43 ± 22 ms at increased pacing rates. Sustained AF (>90 min) was induced by burst pacing during pinacidil (30-100 µM) perfusion. Dual-sided sub-Endo-sub-Epi optical mapping revealed that AF was driven by spatially and temporally stable intramural re-entry with 107 ± 50 ms cycle length and transmural activation delay of 67 ± 31 ms. Intramural re-entrant drivers were captured primarily by sub-Endo mapping, while sub-Epi mapping visualized re-entry or 'breakthrough' patterns. Re-entrant drivers were anchored on 3D micro-anatomic tracks (15.4 ± 2.2 × 6.0 ± 2.3 mm2, 2.9 ± 0.9 mm depth) formed by atrial musculature characterized by increased transmural fiber angle differences and interstitial fibrosis. Targeted radiofrequency ablation of the tracks verified these re-entries as drivers of AF. Integrated 3D structural-functional mapping of diseased human right atria ex vivo revealed that the complex atrial microstructure caused significant differences between Endo vs. Epi activation during pacing and sustained AF driven by intramural re-entry anchored to fibrosis-insulated atrial bundles. Published on

  3. Atrial fibrillation

    African Journals Online (AJOL)

    ABEOLUGBENGAS

    Mean blood pressures were 126.03± ... optimal. Keywords: Atrial fibrillation, thrombosis, CHADS2 Score, stroke risk, hypertensive heart disease, ... general population and the average age group ... Appendix 1) to stratify the stroke risk and we.

  4. Atrial Fibrillation: Diagnosis

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Diagnosis Past Issues / Winter 2015 Table of Contents ... of your body's cells and organs. Read More "Atrial Fibrillation" Articles Atrial Fibrillation / Who Is at Risk for ...

  5. Atrial fibrillation

    DEFF Research Database (Denmark)

    Olesen, Morten S; Nielsen, Morten W; Haunsø, Stig

    2014-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting 1-2% of the general population. A number of studies have demonstrated that AF, and in particular lone AF, has a substantial genetic component. Monogenic mutations in lone and familial AF, although rare, have been recognized...

  6. [Atrial fibrillation].

    Science.gov (United States)

    Spinar, J; Vítovec, J

    2003-09-01

    Atrial fibrilation is the most frequent arrhythmia, the occurrence increasing with age and associated diseases. The incidence at the age below 60 years is markedly lower than one per cent, whereas in persons above 80 years of age it exceeds six per cent. The occurrence in patients with heart failure is from 10% (NYHA II) up to 50% (NYHA IV). Atrial fibrillation is classified into that observed for the first time and permanent, respectively, while transient forms include paroxyzmal and persistent atrial fibrillation. The diagnosis is based on ECG recording, while echocardiography is most significant. The therapy includes two basic questions--anticoagulant or anti-aggregation treatment and the control of rhythm or frequency. The anticoagulant therapy should be introduced in all patients, where contraindications are not present, being necessary before every cardioversion, provided atrial fibrillation lasts more than two days. In patients without any heart disease and with a physiological echocardiogram it is possible to administer only anti-aggregation treatment. Cardioversion (the control of rhythm) is recommended to all symptomatic patients, in other cases and especially in older persons the control of frequency is safer and of more advantage. Electrical cardioversion is more effective that a pharmacological treatment, the sinus rhythm is preferably controlled by dofetilid, ibutilid, propafenon and amiodaron. For the control of heart rate beta-blockers, diltiazem, verapamil and digitalis are recommended.

  7. Atrial Fibrillation: Treatment

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    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Treatment Past Issues / Winter 2015 Table of Contents Treatment for atrial fibrillation depends on how often you have symptoms, how ...

  8. Atrial Fibrillation

    DEFF Research Database (Denmark)

    Staerk, Laila; Sherer, Jason A; Ko, Darae

    2017-01-01

    The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a vulnerable atrial substrate and that the formation and composition of this substrate may vary depending...... on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established...

  9. Atrial fibrillation or flutter

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000184.htm Atrial fibrillation or flutter To use the sharing features on this page, please enable JavaScript. Atrial fibrillation or flutter is a common type of abnormal ...

  10. Atrial fibrillation - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000237.htm Atrial fibrillation - discharge To use the sharing features on this ... have been in the hospital because you have atrial fibrillation . This condition occurs when your heart beats faster ...

  11. Atrial Fibrillation - Multiple Languages

    Science.gov (United States)

    ... Are Here: Home → Multiple Languages → All Health Topics → Atrial Fibrillation URL of this page: https://medlineplus.gov/languages/ ... V W XYZ List of All Topics All Atrial Fibrillation - Multiple Languages To use the sharing features on ...

  12. Atrial Fibrillation: Complications

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Complications Past Issues / Winter 2015 Table of Contents ... has two major complications—stroke and heart failure. Atrial Fibrillation and Stroke Click to enlarge image This illustration ...

  13. Atrial fibrillation.

    Science.gov (United States)

    Bang, Casper N

    2013-10-01

    Atrial fibrillation (AF) is a common complication after myocardial infarction (MI) and new-onset AF has been demonstrated to be associated with adverse outcome and a large excess risk of death in both MI and aortic stenosis (AS) patients. Prevention of new-onset AF is therefore a potential therapeutic target in AS and MI patients. Lipid-lowering drugs, particularly statins, have anti-inflammatory and antioxidant properties that may prevent AF. Accordingly, statins are recommended as a class IIa recommendation for prevention of new-onset AF after coronary artery bypass grafting (CABG). However, this preventive effect has not been investigated on new-onset AF in asymptomatic patients with AS or a large scale first-time MI patient sample and data in patients not undergoing invasive cardiac interventions are limited. This PhD thesis was conducted at the Heart Centre, Rigshospitalet, Denmark, with the aim to investigate the three aforementioned questions and to add to the existing evidence of AF prevention with statins. This was done using three different settings: 1) a randomized patients sample of 1,873 from the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study, 2) a register patient sample of 97,499 with first-time MI, and 3) all published studies until beginning of June 2011 examining statin treatment on new-onset and recurrent AF in patients not undergoing cardiac surgery. This thesis revealed that statins did not lower the incidence or the time to new-onset AF in patients with asymptomatic AS. However, statin treatment showed an independently preventive effect on new-onset AF, including type-dependent effect and a trend to dosage-dependent effect. In addition, this thesis showed that good compliance to statin treatment was important to prevent new-onset AF. Finally, the meta-analysis in this PhD thesis showed a preventive effect in the observational studies although this effect was absent in the randomized controlled trials. Based on this PhD thesis

  14. What Is Atrial Fibrillation?

    Science.gov (United States)

    ANSWERS by heart Cardiovascular Conditions What Is Atrial Fibrillation? Your heart has a natural pacemaker, called the “sinus node,” that makes electrical signals. These signals cause the heart to contract and pump ...

  15. Toward understanding insulin fibrillation.

    Science.gov (United States)

    Brange, J; Andersen, L; Laursen, E D; Meyn, G; Rasmussen, E

    1997-05-01

    Formation of insulin fibrils is a physical process by which partially unfolded insulin molecules interact with each other to form linear aggregates. Shielding of hydrophobic domains is the main driving force for this process, but formation of intermolecular beta-sheet may further stabilize the fibrillar structure. Conformational displacement of the B-chain C-terminal with exposure of nonpolar, aliphatic core residues, including A2, A3, B11, and B15, plays a crucial role in the fibrillation process. Recent crystal analyses and molecular modeling studies have suggested that when insulin fibrillates this exposed domain interacts with a hydrophobic surface domain formed by the aliphatic residues A13, B6, B14, B17, and B18, normally buried when three insulin dimers form a hexamer. In rabbit immunization experiments, insulin fibrils did not elicit an increased immune response with respect to formation of IgG insulin antibodies when compared with native insulin. In contrast, the IgE response increased with increasing content of insulin in fibrillar form. Strategies and practical approaches to prevent insulin from forming fibrils are reviewed. Stabilization of the insulin hexameric structure and blockage of hydrophobic interfaces by addition of surfactants are the most effective means of counteracting insulin fibrillation.

  16. Surgery for atrial fibrillation.

    Science.gov (United States)

    Viganò, M; Graffigna, A; Ressia, L; Minzioni, G; Pagani, F; Aiello, M; Gazzoli, F

    1996-01-01

    The mechanisms of atrial fibrillation arc multiple reentry circuits spinning around the atrial surface, and these baffle any attempt to direct surgical interruption. The purpose of this article is to report the surgical experience in the treatment of isolated and concomitant atrial fibrillation at the Cardiac Surgical Institute of the University of Pavia. In cases of atrial fibrillation secondary to mitral/valve disease, surgical isolation of the left atrium at the time of mitral valve surgery can prevent atrial fibrillation from involving the right atrium, which can exert its diastolic pump function on the right ventricle. Left atrial isolation was performed on 205 patients at the time of mitral valve surgery. Atrial partitioning ("maze operation") creates straight and blind atrial alleys so that non-recentry circuits can take place. Five patients underwent this procedure. In eight-cases of atrial fibrillation secondary to atrial septal defect, the adult patients with atrial septal defect and chronic or paroxysmal atrial fibrillation underwent surgical isolation of the right atrium associated which surgical correction of the defect, in order to let sinus rhythm govern the left atrium and the ventricles. "Lone" atrial fibrillation occurs in hearts with no detectable organic disease. Bi-atrial isolation with creation of an atrial septal internodal "corridor" was performed on 14 patients. In cases of atrial fibrillation secondary to mitral valve disease, left atrial isolation was performed on 205 patients at the time of mitral valve surgery with an overall sinus rhythm recovery of 44%. In the same period, sinus rhythm was recovered and persisted in only 19% of 252 patients who underwent mitral valve replacement along (P < 0.001). Sinus rhythm was less likely to recover in patients with right atriomegaly requiring tricuspid valve annuloplasty: 59% vs 84% (P < 0.001). Restoration of the right atrial function raised the cardiac index from 2.25 +/- 0.55 1/min per m2

  17. Atrial Fibrillation and Hyperthyroidism

    Directory of Open Access Journals (Sweden)

    Jayaprasad N

    2005-10-01

    Full Text Available Atrial fibrillation occurs in 10 – 15% of patients with hyperthyroidism. Low serum thyrotropin concentration is an independent risk factor for atrial fibrillation. Thyroid hormone contributes to arrythmogenic activity by altering the electrophysiological characteristics of atrial myocytes by shortening the action potential duration, enhancing automaticity and triggered activity in the pulmonary vein cardio myocytes. Hyperthyroidism results in excess mortality from increased incidence of circulatory diseases and dysrhythmias. Incidence of cerebral embolism is more in hyperthyroid patients with atrial fibrillation, especially in the elderly and anti-coagulation is indicated in them. Treatment of hyperthyroidism results in conversion to sinus rhythm in up to two-third of patients. Beta-blockers reduce left ventricular hypertrophy and atrial and ventricular arrhythmias in patients with hyperthyroidism. Treatment of sub clinical hyperthyroidism is controversial. Optimizing dose of thyroxine treatment in those with replacement therapy and beta-blockers is useful in exogenous subclinical hyperthyroidism.

  18. Atrial fibrillation: To map or not to map?

    NARCIS (Netherlands)

    A. Yaksh (Ameeta); C. Kik (Charles); S.P. Knops (Simon); J.W. Roos-Hesselink (Jolien); A.J.J.C. Bogers (Ad); F. Zijlstra (Felix); M.A. Allessie (Maurits); N.M.S. de Groot (Natasja)

    2014-01-01

    textabstractIsolation of the pulmonary veins may be an effective treatment modality for eliminating atrial fibrillation (AF) episodes but unfortunately not for all patients. When ablative therapy fails, it is assumed that AF has progressed from a trigger-driven to a substrate-mediated arrhythmia.

  19. Thyrotoxic atrial fibrillation.

    Science.gov (United States)

    Parmar, Malvinder S

    2005-01-04

    Atrial fibrillation is the most common cardiac complication of hyperthyroidism and occurs in 15% of patients with hyperthyroidism. It is associated with a higher risk of thromboembolism that often involves the central nervous system. Oral anticoagulation is important in the majority of these patients to prevent thromboembolic complications. These patients require adjustment in the dose of various rate-controlling agents because of increased clearance associated with hyperthyroidism and a decrease in warfarin dosage because of increased clearance of vitamin K-dependent clotting factors. The management of thyrotoxic atrial fibrillation is summarized in this clinical review.

  20. Modulation of atrial fibrillation

    NARCIS (Netherlands)

    Geuzebroek, G.S.C.

    2013-01-01

    In this thesis we investigate the results of various surgical procedures for atrial fibrillation which have been performed in the last 2 decades in the Sint Antonius Hospital, Nieuwegein, The Netherlands. In the 1990s the classical Maze III procedure was the main surgical technique for

  1. Screening for Atrial Fibrillation

    DEFF Research Database (Denmark)

    Freedman, Ben; Camm, John; Calkins, Hugh

    2017-01-01

    Approximately 10% of ischemic strokes are associated with atrial fibrillation (AF) first diagnosed at the time of stroke. Detecting asymptomatic AF would provide an opportunity to prevent these strokes by instituting appropriate anticoagulation. The AF-SCREEN international collaboration was formed...

  2. HYPERTHYROIDISM AND ATRIAL FIBRILLATION

    Directory of Open Access Journals (Sweden)

    I. M. Marusenko

    2017-01-01

    Full Text Available Review on a problem of the development of atrial fibrillation in patients with thyrotoxicosis is presented. Thyrotoxicosis is one of the most frequent endocrine diseases, conceding only to a diabetes mellitus. The most frequent reasons of hyperthyroidism are Graves’ disease and functional thyroid autonomy. The authors give an analysis of data on the cardiac effects of thyrotoxicosis, features of heart remodeling under the influence of thyroid hyperfunction, prevalence of atrial fibrillation in thyrotoxicosis, depending on age, as well as the possibility of restoring sinus rhythm in the combination of these diseases. Particular attention is paid to the effect on the heart of subclinical thyrotoxicosis, which is defined as a dysfunction of the thyroid gland, characterized by low serum concentration of thyrotropin, normal values of free thyroxine and free triiodothyronine. Subclinical hyperthyroidism is also capable of causing heart remodeling and diastolic dysfunction.Prevalence of thyrotoxicosis in elderly people is higher in areas of iodine deficiency; it is relevant for our country due to the large territory of iodine deficiency. In elderly patients, the cardiac effects of thyrotoxicosis prevail in the clinical picture, that makes it difficult to diagnose endocrine disorders, and correction of thyrotoxicosis is critically important for the successful control of the heart rhythm. The article also discusses the problem of thyrotoxic cardiomyopathy, caused by the toxic effect of excess thyroid hormones: features of this heart disorder, factors affecting its formation, clinical significance and contribution to the development of rhythm disturbances. The greatest significance is the development of atrial fibrillation as a result of thyrotox-icosis in older patients who already have various cardiovascular diseases.Atrial fibrillation is the most frequent heart rhythm disorder in thyrotoxicosis. The main cause of arrhythmia in hyperthyroidism is the

  3. Genetics Home Reference: familial atrial fibrillation

    Science.gov (United States)

    ... Twitter Home Health Conditions Familial atrial fibrillation Familial atrial fibrillation Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Familial atrial fibrillation is an inherited abnormality of the heart's normal ...

  4. [Atrial fibrillation in elderly].

    Science.gov (United States)

    Arquizan, Caroline

    2012-11-01

    Atrial fibrilation (AF) is frequent and a strong risk factor for ischemic stroke in elderly. Ischemic stroke in patients with AF are more severe. Vitamine K antagonist therapy is highly effective for stroke prevention but is associated with hemorrhagic risk. The new oral anticoagulants (direct thrombin inhibitor [dabigatran], and direct factor Xa inhibitors [rivaroxaban and apixaban]) have all shown non inferiority or superiority, with better safety, considering the risk of intracranial haemorrhage. On this basis, it is justified to give them in priority in the vast majority of patients with AF, the choice of the drug and the dose is individual.

  5. Atrial fibrillation in the elderly

    Science.gov (United States)

    Franken, Roberto A.; Rosa, Ronaldo F.; Santos, Silvio CM

    2012-01-01

    This review discusses atrial fibrillation according to the guidelines of Brazilian Society of Cardiac Arrhythmias and the Brazilian Cardiogeriatrics Guidelines. We stress the thromboembolic burden of atrial fibrillation and discuss how to prevent it as well as the best way to conduct cases of atrial fibrillatios in the elderly, reverting the arrhythmia to sinus rhythm, or the option of heart rate control. The new methods to treat atrial fibrillation, such as radiofrequency ablation, new oral direct thrombin inhibitors and Xa factor inhibitors, as well as new antiarrhythmic drugs, are depicted. PMID:22916053

  6. Pharmacological Treatment for Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Kaoru Sugi, MD PhD

    2005-01-01

    Full Text Available Pharmacological treatment for atrial fibrillation has a variety of purposes, such as pharmacological defibrillation, maintenance of sinus rhythm, heart rate control to prevent congestive heart failure and prevention of both cerebral infarction and atrial remodeling. Sodium channel blockers are superior to potassium channel blockers for atrial defibrillation, while both sodium and potassium channel blockers are effective in the maintenance of sinus rhythm. In general, digitalis or Ca antagonists are used to control heart rate during atrial fibrillation to prevent congestive heart failure, while amiodarone or bepridil also reduce heart rates during atrial fibrillation. Anticoagulant therapy with warfarin is recommended to prevent cerebral infarction and angiotensin converting enzyme antagonists or angiotensin II receptor blockers are also used to prevent atrial remodeling. One should select appropriate drugs for treatment of atrial fibrillation according to the patient's condition.

  7. Fracture mechanics of collagen fibrils

    DEFF Research Database (Denmark)

    Svensson, Rene B; Mulder, Hindrik; Kovanen, Vuokko

    2013-01-01

    Tendons are important load-bearing structures, which are frequently injured in both sports and work. Type I collagen fibrils are the primary components of tendons and carry most of the mechanical loads experienced by the tissue, however, knowledge of how load is transmitted between and within...... fibrils is limited. The presence of covalent enzymatic cross-links between collagen molecules is an important factor that has been shown to influence mechanical behavior of the tendons. To improve our understanding of how molecular bonds translate into tendon mechanics, we used an atomic force microscopy...... technique to measure the mechanical behavior of individual collagen fibrils loaded to failure. Fibrils from human patellar tendons, rat-tail tendons (RTTs), NaBH₄ reduced RTTs, and tail tendons of Zucker diabetic fat rats were tested. We found a characteristic three-phase stress-strain behavior in the human...

  8. Atrial fibrillation and hyperthyroidism: A literature review.

    Science.gov (United States)

    Reddy, Vivek; Taha, Wael; Kundumadam, Shanker; Khan, Mazhar

    Atrial fibrillation is the most common arrhythmia worldwide with increasing frequency noted with age. Hyperthyroidism is a well-known cause of atrial fibrillation with a 16%-60% prevalence of atrial fibrillation in patients with known hyperthyroidism Ross et al. (2016). While hyperthyroidism as a causative factor of atrial fibrillation is well established, this literature review aims to answer several questions on this topic including: 1. The relationship of atrial fibrillation to hyperthyroidism 2. Atrial fibrillation as a predictor of hyperthyroidism 3. The pathophysiology of thyrotoxic atrial fibrillation 4. Subclinical hyperthyroidism and the relationship with atrial fibrillation 5. Cardioversion and Catheter ablation of hyperthyroid patients with atrial fibrillation 6. Thrombotic risk of hyperthyroid patients with atrial fibrillation 7. Management of Thyrotoxic Atrial fibrillation 8. Pharmacological rhythm control in patients with hyperthyroidism and atrial fibrillation 9. Treatment of Hyperthyroidism to prevent atrial fibrillation 10. Clinical Implications of Hyperthyroidism and Atrial Fibrillation. Copyright © 2017 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

  9. Transmission electron microscopy of amyloid fibrils.

    Science.gov (United States)

    Gras, Sally L; Waddington, Lynne J; Goldie, Kenneth N

    2011-01-01

    Transmission Electron Microscopy of negatively stained and cryo-prepared specimens allows amyloid fibrils to be visualised at high resolution in a dried or a hydrated state, and is an essential method for characterising the morphology of fibrils and pre-fibrillar species. We outline the key steps involved in the preparation and observation of samples using negative staining and cryo-electron preservation. We also discuss methods to measure fibril characteristics, such as fibril width, from electron micrographs.

  10. Cryoballoon Ablation for Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Jason G. Andrade, MD

    2012-03-01

    Full Text Available Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1 the rationale for adjunctive imaging, 2 selection of an appropriate cryoballoon size, 3 predictors of efficacy, 4 advanced trouble-shooting techniques, and 5 strategies to reduce procedural complications, such as phrenic nerve palsy.

  11. Personalized management of atrial fibrillation

    DEFF Research Database (Denmark)

    Kirchhof, Paulus; Breithardt, Günter; Aliot, Etienne

    2013-01-01

    The management of atrial fibrillation (AF) has seen marked changes in past years, with the introduction of new oral anticoagulants, new antiarrhythmic drugs, and the emergence of catheter ablation as a common intervention for rhythm control. Furthermore, new technologies enhance our ability......, and hospitalizations. During the fourth Atrial Fibrillation competence NETwork/European Heart Rhythm Association (AFNET/EHRA) consensus conference, we identified the following opportunities to personalize management of AF in a better manner with a view to improve outcomes by integrating atrial morphology and damage...

  12. Atrial fibrillation and delayed gastric emptying.

    Directory of Open Access Journals (Sweden)

    Isadora C Botwinick

    Full Text Available BACKGROUND: Atrial fibrillation and delayed gastric emptying (DGE are common after pancreaticoduodenectomy. Our aim was to investigate a potential relationship between atrial fibrillation and DGE, which we defined as failure to tolerate a regular diet by the 7(th postoperative day. METHODS: We performed a retrospective chart review of 249 patients who underwent pancreaticoduodenectomy at our institution between 2000 and 2009. Data was analyzed with Fisher exact test for categorical variables and Mann-Whitney U or unpaired T-test for continuous variables. RESULTS: Approximately 5% of the 249 patients included in the analysis experienced at least one episode of postoperative atrial fibrillation. Median age of patients with atrial fibrillation was 74 years, compared with 66 years in patients without atrial fibrillation (p = 0.0005. Patients with atrial fibrillation were more likely to have a history of atrial fibrillation (p = 0.03. 92% of the patients with atrial fibrillation suffered from DGE, compared to 46% of patients without atrial fibrillation (p = 0.0007. This association held true when controlling for age. CONCLUSION: Patients with postoperative atrial fibrillation are more likely to experience delayed gastric emptying. Interventions to manage delayed gastric function might be prudent in patients at high risk for postoperative atrial fibrillation.

  13. Nanomechanical properties of single amyloid fibrils

    International Nuclear Information System (INIS)

    Sweers, K K M; Bennink, M L; Subramaniam, V

    2012-01-01

    Amyloid fibrils are traditionally associated with neurodegenerative diseases like Alzheimer’s disease, Parkinson’s disease or Creutzfeldt-Jakob disease. However, the ability to form amyloid fibrils appears to be a more generic property of proteins. While disease-related, or pathological, amyloid fibrils are relevant for understanding the pathology and course of the disease, functional amyloids are involved, for example, in the exceptionally strong adhesive properties of natural adhesives. Amyloid fibrils are thus becoming increasingly interesting as versatile nanobiomaterials for applications in biotechnology. In the last decade a number of studies have reported on the intriguing mechanical characteristics of amyloid fibrils. In most of these studies atomic force microscopy (AFM) and atomic force spectroscopy play a central role. AFM techniques make it possible to probe, at nanometer length scales, and with exquisite control over the applied forces, biological samples in different environmental conditions. In this review we describe the different AFM techniques used for probing mechanical properties of single amyloid fibrils on the nanoscale. An overview is given of the existing mechanical studies on amyloid. We discuss the difficulties encountered with respect to the small fibril sizes and polymorphic behavior of amyloid fibrils. In particular, the different conformational packing of monomers within the fibrils leads to a heterogeneity in mechanical properties. We conclude with a brief outlook on how our knowledge of these mechanical properties of the amyloid fibrils can be exploited in the construction of nanomaterials from amyloid fibrils. (topical review)

  14. Stroke prevention in atrial fibrillation

    DEFF Research Database (Denmark)

    Fanaroff, Alexander C; Steffel, Jan; Alexander, John H

    2018-01-01

    of anticoagulation for atrial fibrillation (AF). Observational studies employing RWD are useful for describing how oral anticoagulants are used in clinical practice, but generally cannot be used to make claims regarding comparative treatment effects. Questions regarding treatment effect generally are best answered...

  15. Risk Factors for Atrial Fibrillation

    NARCIS (Netherlands)

    B.P. Krijthe (Bouwe)

    2013-01-01

    textabstractAtrial fibrillation is a common cardiac arrhythmia that is characterized by rapid disorganized atrial electrical activity resulting in absence of atrial contractions. It is diagnosed on the basis of typical findings on an electrocardiogram (ECG). The characteristic ECG findings are

  16. Genetic basis of atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Oscar Campuzano

    2016-12-01

    Full Text Available Atrial fibrillation is the most common sustained arrhythmia and remains as one of main challenges in current clinical practice. The disease may be induced secondary to other diseases such as hypertension, valvular heart disease, and heart failure, conferring an increased risk of stroke and sudden death. Epidemiological studies have provided evidence that genetic factors play an important role and up to 30% of clinically diagnosed patients may have a family history of atrial fibrillation. To date, several rare variants have been identified in a wide range of genes associated with ionic channels, calcium handling protein, fibrosis, conduction and inflammation. Important advances in clinical, genetic and molecular basis have been performed over the last decade, improving diagnosis and treatment. However, the genetics of atrial fibrillation is complex and pathophysiological data remains still unraveling. A better understanding of the genetic basis will induce accurate risk stratification and personalized clinical treatment. In this review, we have focused on current genetics basis of atrial fibrillation.

  17. Signal analysis of ventricular fibrillation

    NARCIS (Netherlands)

    Herbschleb, J.N.; Heethaar, R.M.; Tweel, L.H. van der; Zimmerman, A.N.E.; Meijler, F.L.

    Signal analysis of electro(cardio)grams during ventricular fibrillation (VF) in dogs and human patients indicates more organization and regularity than the official WHO definition suggests. The majority of the signal is characterized by a power spectrum with narrow, equidistant peaks. In a further

  18. Risk of atrial fibrillation in diabetes mellitus

    DEFF Research Database (Denmark)

    Pallisgaard, Jannik L; Schjerning, Anne-Marie; Lindhardt, Tommi B

    2016-01-01

    AIM: Diabetes has been associated with atrial fibrillation but the current evidence is conflicting. In particular knowledge regarding young diabetes patients and the risk of developing atrial fibrillation is sparse. The aim of our study was to investigate the risk of atrial fibrillation in patients...... with diabetes compared to the background population in Denmark. METHODS AND RESULTS: Through Danish nationwide registries we included persons above 18 years of age and without prior atrial fibrillation and/or diabetes from 1996 to 2012. The study cohort was divided into a background population without diabetes...... and a diabetes group. The absolute risk of developing atrial fibrillation was calculated and Poisson regression models adjusted for sex, age and comorbidities were used to calculate incidence rate ratios of atrial fibrillation. The total study cohort included 5,081,087 persons, 4,827,713 (95%) in the background...

  19. Chondroitin Sulfate Perlecan Enhances Collagen Fibril Formation

    DEFF Research Database (Denmark)

    Kvist, A. J.; Johnson, A. E.; Mörgelin, M.

    2006-01-01

    in collagen type II fibril assembly by perlecan-null chondrocytes. Cartilage perlecan is a heparin sulfate or a mixed heparan sulfate/chondroitin sulfate proteoglycan. The latter form binds collagen and accelerates fibril formation in vitro, with more defined fibril morphology and increased fibril diameters...... produced in the presence of perlecan. Interestingly, the enhancement of collagen fibril formation is independent on the core protein and is mimicked by chondroitin sulfate E but neither by chondroitin sulfate D nor dextran sulfate. Furthermore, perlecan chondroitin sulfate contains the 4,6-disulfated...... disaccharides typical for chondroitin sulfate E. Indeed, purified glycosaminoglycans from perlecan-enriched fractions of cartilage extracts contain elevated levels of 4,6-disulfated chondroitin sulfate disaccharides and enhance collagen fibril formation. The effect on collagen assembly is proportional...

  20. [Panic disorder and atrial fibrillation].

    Science.gov (United States)

    Olazabal Eizaguirre, N; Chavez, R; González-Torres, M A; Gaviria, M

    2013-10-01

    This paper studies the relationship between atrial fibrillation and panic disorder. There are often doubts on the differential diagnosis in emergency services and general medical settings. Panic disorder prevalence rates have been found to be high in patients suffering from atrial fibrillation. Various studies have observed that patients diagnosed with anxiety disorders frequently have higher cardiovascular disease rates compared to the general population. Usually, patients suffering from panic disorder exhibit somatic complaints suggesting coronary disease, such as chest pain or palpitations. The aim is to make the correct diagnosis and treatment for these different illnesses, and to decrease the costs due to misdiagnosis. Copyright © 2012 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España. All rights reserved.

  1. Alginate-Collagen Fibril Composite Hydrogel

    Directory of Open Access Journals (Sweden)

    Mahmoud Baniasadi

    2015-02-01

    Full Text Available We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  2. Confinement-induced liquid crystalline transitions in amyloid fibril cholesteric tactoids

    Science.gov (United States)

    Nyström, Gustav; Arcari, Mario; Mezzenga, Raffaele

    2018-04-01

    Chirality is ubiquitous in nature and plays crucial roles in biology, medicine, physics and materials science. Understanding and controlling chirality is therefore an important research challenge with broad implications. Unlike other chiral colloids, such as nanocellulose or filamentous viruses, amyloid fibrils form nematic phases but appear to miss their twisted form, the cholesteric or chiral nematic phases, despite a well-defined chirality at the single fibril level. Here we report the discovery of cholesteric phases in amyloids, using β-lactoglobulin fibrils shortened by shear stresses. The physical behaviour of these new cholesteric materials exhibits unprecedented structural complexity, with confinement-driven ordering transitions between at least three types of nematic and cholesteric tactoids. We use energy functional theory to rationalize these results and observe a chirality inversion from the left-handed amyloids to right-handed cholesteric droplets. These findings deepen our understanding of cholesteric phases, advancing their use in soft nanotechnology, nanomaterial templating and self-assembly.

  3. Contemporary approach to stroke prevention in atrial fibrillation: Risks, benefits, and new options.

    Science.gov (United States)

    Stock, Jonathan; Malm, Brian J

    2018-04-04

    Atrial fibrillation is a common diagnosis affecting nearly 3 million adults in the United States. Morbidity and mortality in these patients is driven largely by the associated increased risk of thromboembolic complications, especially stroke. Atrial fibrillation is a stronger risk factor than hypertension, coronary disease, or heart failure and is associated with an approximately five-fold increased risk. Mitigating stroke risk can be challenging and requires accurate assessment of stroke risk factors and careful selection of appropriate therapy. Anticoagulation, including the more recently introduced direct oral anticoagulants, is the standard of care for most patients. In addition, emerging non-pharmacologic mechanical interventions are playing an expanding role in reducing stroke risk in select patients. In this review we highlight the current approach to stroke risk stratification in atrial fibrillation and discuss in detail the mechanism, risks, and benefits of current and evolving therapies. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. The role of protonation in protein fibrillation

    DEFF Research Database (Denmark)

    Jeppesen, Martin D; Westh, Peter; Otzen, Daniel E

    2010-01-01

    Many proteins fibrillate at low pH despite a high population of charged side chains. Therefore exchange of protons between the fibrillating peptide and its surroundings may play an important role in fibrillation. Here, we use isothermal titration calorimetry to measure exchange of protons between...... buffer and the peptide hormone glucagon during fibrillation. Glucagon absorbs or releases protons to an extent which allows it to attain a net charge of zero in the fibrillar state, both at acidic and basic pH. Similar results are obtained for lysozyme. This suggests that side chain pKa values change...

  5. Stop-and-go kinetics in amyloid fibrillation

    DEFF Research Database (Denmark)

    Ferkinghoff-Borg, Jesper; Fonslet, Jesper; Andersen, Christian Beyschau

    2010-01-01

    Many human diseases are associated with protein aggregation and fibrillation. We present experiments on in vitro glucagon fibrillation using total internal reflection fluorescence microscopy, providing real-time measurements of single-fibril growth. We find that amyloid fibrils grow in an intermi......Many human diseases are associated with protein aggregation and fibrillation. We present experiments on in vitro glucagon fibrillation using total internal reflection fluorescence microscopy, providing real-time measurements of single-fibril growth. We find that amyloid fibrils grow...

  6. Aspects epidemiologiques et etiologiques de la fibrillation ...

    African Journals Online (AJOL)

    Conclusion : La fibrillation auriculaire est fréquente chez l'adulte noir togolais. Ses étiologies sont dominées par l'hypertension artérielle et les cardiomyopathies dilatées. complications and stoke. Aim: Our aim was to study epidemiologic and etiologic aspects of atrial fibrillation in black togolese in hospital circle. Material ...

  7. Viscoelastic behavior of discrete human collagen fibrils

    DEFF Research Database (Denmark)

    Svensson, Rene; Hassenkam, Tue; P, Hansen

    2010-01-01

    Whole tendon and fibril bundles display viscoelastic behavior, but to the best of our knowledge this property has not been directly measured in single human tendon fibrils. In the present work an atomic force microscopy (AFM) approach was used for tensile testing of two human patellar tendon fibr...

  8. Fibril assembly in whey protein mixtures

    NARCIS (Netherlands)

    Bolder, S.G.

    2007-01-01

    The objective of this thesis was to study fibril assembly in mixtures of whey proteins. The effect of the composition of the protein mixture on the structures and the resulting phase behaviour was investigated. The current work has shown that beta-lactoglobulin is responsible for the fibril assembly

  9. Cetirizine-Induced atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Altuğ Osken

    2016-01-01

    Full Text Available Atrial fibrillation (AF is the most common observed arrhythmia in clinical practice. In the literature, AF events associated with drug induction are available. Cetirizine is a second-generation histamine antagonist used in the treatment of allergies, angioedema, and urticaria. We wish to present an atypical case who took cetirizine medication for relieving symptoms of upper tract respiratory system infection, experienced rapid ventricular response AF and treated successfully. To best of our knowledge, this is the first case of cetirizine-induced AF.

  10. Atrial fibrillation after cardiac surgery

    Directory of Open Access Journals (Sweden)

    Nair Suresh

    2010-01-01

    Full Text Available Once considered as nothing more than a nuisance after cardiac surgery, the importance of postoperative atrial fibrillation (POAF has been realized in the last decade, primarily because of the morbidity associated with the condition. Numerous causative factors have been described without any single factor being singled out as the cause of this complication. POAF has been associated with stroke, renal failure and congestive heart failure, although it is difficult to state whether POAF is directly responsible for these complications. Guidelines have been formulated for prevention of POAF. However, very few cardiothoracic centers follow any form of protocol to prevent POAF. Routine use of prophylaxis would subject all patients to the side effects of anti-arrhythmic drugs, while only a minority of the patients do actually develop this problem postoperatively. Withdrawal of beta blockers in the postoperative period has been implicated as one of the major causes of POAF. Amiodarone, calcium channel blockers and a variety of other pharmacological agents have been used for the prevention of POAF. Atrial pacing is a non-pharmacological measure which has gained popularity in the prevention of POAF. There is considerable controversy regarding whether rate control is superior to rhythm control in the treatment of established atrial fibrillation (AF. Amiodarone plays a central role in both rate control and rhythm control in postoperative AF. Newer drugs like dronedarone and ranazoline are likely to come into the market in the coming years.

  11. Atrial fibrillation and survival in colorectal cancer

    Directory of Open Access Journals (Sweden)

    Justin Timothy A

    2004-11-01

    Full Text Available Abstract Background Survival in colorectal cancer may correlate with the degree of systemic inflammatory response to the tumour. Atrial fibrillation may be regarded as an inflammatory complication. We aimed to determine if atrial fibrillation is a prognostic factor in colorectal cancer. Patients and methods A prospective colorectal cancer patient database was cross-referenced with the hospital clinical-coding database to identify patients who had underwent colorectal cancer surgery and were in atrial fibrillation pre- or postoperatively. Results A total of 175 patients underwent surgery for colorectal cancer over a two-year period. Of these, 13 patients had atrial fibrillation pre- or postoperatively. Atrial fibrillation correlated with worse two-year survival (p = 0.04; log-rank test. However, in a Cox regression analysis, atrial fibrillation was not significantly associated with survival. Conclusion The presence or development of atrial fibrillation in patients undergoing surgery for colorectal cancer is associated with worse overall survival, however it was not found to be an independent factor in multivariate analysis.

  12. Sucrose modulates insulin amyloid-like fibril formation: effect on the aggregation mechanism and fibril morphology

    DEFF Research Database (Denmark)

    Marasini, Carlotta; Foderà, Vito; Vestergaard, Bente

    2017-01-01

    the protein self-assembly pathways. Using a combination of fluorescence spectroscopy, synchrotron radiation circular dichroism and transmission electron microscopy, we study the kinetics of formation and structural properties of human insulin fibrils in the presence of sucrose. The presence of sucrose results...... in a delay of the onset of fibrillation. Moreover, it leads to a dramatic change in both the morphology and overall amount of fibrils. Our results emphasize that the detailed composition of protein surroundings likely influences not only the fibrillation kinetics but also the balance between different...

  13. Psychosomatic correlations in atrial fibrillations

    Directory of Open Access Journals (Sweden)

    Vladimir Ernstovich Medvedev

    2011-01-01

    Full Text Available Patients with atrial fibrillations (AF and comorbid mental disorders were examined. Two patient groups differing in the structure of psychosomatic ratios were identified. Group 1 comprised patients with AF and signs of reactivity lability that manifested itself as psychopathological reactions to the primary manifestations of AF; Group 2 included those who had developed mental disorders mainly in end-stage cardiovascular disease (predominantly a permanent form of AF in the presence of such events as chronic heart failure (CHF. The results of the study suggest that the patients with AF have frequently anxiety and hypochondriacal disorders, which agrees with the data available in the literature. In addition, end-stage AF is marked by depressive syndromes caused by the severe course of cardiovascular diseases resulting in CHF.

  14. Idiopathic ventricular tachycardia and fibrillation.

    Science.gov (United States)

    Belhassen, B; Viskin, S

    1993-06-01

    Important data have recently been added to our understanding of sustained ventricular tachyarrhythmias occurring in the absence of demonstrable heart disease. Idiopathic ventricular tachycardia (VT) is usually of monomorphic configuration and can be classified according to its site of origin as either right monomorphic (70% of all idiopathic VTs) or left monomorphic VT. Several physiopathological types of monomorphic VT can be presently individualized, according to their mode of presentation, their relationship to adrenergic stress, or their response to various drugs. The long-term prognosis is usually good. Idiopathic polymorphic VT is a much rarer type of arrhythmia with a less favorable prognosis. Idiopathic ventricular fibrillation may represent an underestimated cause of sudden cardiac death in ostensibly healty patients. A high incidence of inducibility of sustained polymorphic VT with programmed ventricular stimulation has been found by our group, but not by others. Long-term prognosis on Class IA antiarrhythmic medications that are highly effective at electrophysiologic study appears excellent.

  15. Atrial Fibrillation During an Exploration Class Mission

    Science.gov (United States)

    Lipsett, Mark; Hamilton, Douglas; Lemery, Jay; Polk, James

    2011-01-01

    This slide presentation reviews a possible scenario of an astronaut having Atrial Fibrillation during a Mars Mission. In the case review the presentation asks several questions about the alternatives for treatment, medications and the ramifications of the decisions.

  16. [Relations between FANS, PPI and atrial fibrillation].

    Science.gov (United States)

    Ricci, Fabrizio; De Caterina, Raffaele

    2013-05-01

    Recent evidence supports the existence of an association between the use of non-steroidal anti-inflammatory drugs and the risk of atrial fibrillation. Anti-inflammatory drugs are widely used for the treatment of systemic inflammatory disorders, and chronic inflammation is a well-known risk factor for the development of myocardial fibrosis. The latter accounts for atrial inhomogeneities of conduction, thus triggering and perpetuating atrial fibrillation. Atrial inflammatory remodeling may therefore be responsible for the higher incidence of atrial fibrillation among patients assuming steroidal and non-steroidal anti-inflammatory drugs because of an underlying inflammatory disorders. Alternative theories contemplate gastroesophageal reflux, which is extremely common during the use of non-steroidal anti-inflammatory drugs and may trigger atrial fibrillation, as mediating the above-mentioned association.

  17. Salbutamol Abuse is Associated with Ventricular Fibrillation

    Directory of Open Access Journals (Sweden)

    Emin UYSAL

    2015-06-01

    Full Text Available SUMMARY: Salbutamol-induced cardiac complications are well-established. Herein, we describe a case of a 24-year female who was admitted to the emergency department because of a suicide attempt with salbutamol (76 mg. Salbutamol abuse induced the development of supraventricular tachycardia and ventricular fibrillation. Regular sinus rhythm was restored with defibrillation. The hypokalemic patient who stayed in the intensive care unit was discharged after 48 hours of hospitalization. Key words: Salbutamol, suicide, ventricular fibrillation

  18. Chirality and chiroptical properties of amyloid fibrils.

    Science.gov (United States)

    Dzwolak, Wojciech

    2014-09-01

    Chirality of amyloid fibrils-linear beta-sheet-rich aggregates of misfolded protein chains-often manifests in morphological traits such as helical twist visible in atomic force microscopy and in chiroptical properties accessible to vibrational circular dichroism (VCD). According to recent studies the relationship between molecular chirality of polypeptide building blocks and superstructural chirality of amyloid fibrils may be more intricate and less deterministic than previously assumed. Several puzzling experimental findings have put into question earlier intuitive ideas on: 1) the bottom-up chirality transfer upon amyloidogenic self-assembly, and 2) the structural origins of chiroptical properties of protein aggregates. For example, removal of a single amino acid residue from an amyloidogenic all-L peptide was shown to reverse handedness of fibrils. On the other hand, certain types of amyloid aggregates revealed surprisingly strong VCD spectra with the sign and shape dependent on the conditions of fibrillation. Hence, microscopic and chiroptical studies have highlighted chirality as one more aspect of polymorphism of amyloid fibrils. This brief review is intended to outline the current state of research on amyloid-like fibrils from the perspective of their structural and superstructural chirality and chiroptical properties. © 2014 Wiley Periodicals, Inc.

  19. How Glycosaminoglycans Promote Fibrillation of Salmon Calcitonin*

    Science.gov (United States)

    Malmos, Kirsten Gade; Bjerring, Morten; Jessen, Christian Moestrup; Nielsen, Erik Holm Toustrup; Poulsen, Ebbe T.; Christiansen, Gunna; Vosegaard, Thomas; Skrydstrup, Troels; Enghild, Jan J.; Pedersen, Jan Skov; Otzen, Daniel E.

    2016-01-01

    Glycosaminoglycans (GAGs) bind all known amyloid plaques and help store protein hormones in (acidic) granular vesicles, but the molecular mechanisms underlying these important effects are unclear. Here we investigate GAG interactions with the peptide hormone salmon calcitonin (sCT). GAGs induce fast sCT fibrillation at acidic pH and only bind monomeric sCT at acidic pH, inducing sCT helicity. Increasing GAG sulfation expands the pH range for binding. Heparin, the most highly sulfated GAG, binds sCT in the pH interval 3–7. Small angle x-ray scattering indicates that sCT monomers densely decorate and pack single heparin chains, possibly via hydrophobic patches on helical sCT. sCT fibrillates without GAGs, but heparin binding accelerates the process by decreasing the otherwise long fibrillation lag times at low pH and accelerates fibril growth rates at neutral pH. sCT·heparin complexes form β-sheet-rich heparin-covered fibrils. Solid-state NMR reveals that heparin does not alter the sCT fibrillary core around Lys11 but makes changes to Val8 on the exterior side of the β-strand, possibly through contacts to Lys18. Thus GAGs significantly modulate sCT fibrillation in a pH-dependent manner by interacting with both monomeric and aggregated sCT. PMID:27281819

  20. Collagen Fibrils: Nature's Highly Tunable Nonlinear Springs.

    Science.gov (United States)

    Andriotis, Orestis G; Desissaire, Sylvia; Thurner, Philipp J

    2018-03-21

    Tissue hydration is well known to influence tissue mechanics and can be tuned via osmotic pressure. Collagen fibrils are nature's nanoscale building blocks to achieve biomechanical function in a broad range of biological tissues and across many species. Intrafibrillar covalent cross-links have long been thought to play a pivotal role in collagen fibril elasticity, but predominantly at large, far from physiological, strains. Performing nanotensile experiments of collagen fibrils at varying hydration levels by adjusting osmotic pressure in situ during atomic force microscopy experiments, we show the power the intrafibrillar noncovalent interactions have for defining collagen fibril tensile elasticity at low fibril strains. Nanomechanical tensile tests reveal that osmotic pressure increases collagen fibril stiffness up to 24-fold in transverse (nanoindentation) and up to 6-fold in the longitudinal direction (tension), compared to physiological saline in a reversible fashion. We attribute the stiffening to the density and strength of weak intermolecular forces tuned by hydration and hence collagen packing density. This reversible mechanism may be employed by cells to alter their mechanical microenvironment in a reversible manner. The mechanism could also be translated to tissue engineering approaches for customizing scaffold mechanics in spatially resolved fashion, and it may help explain local mechanical changes during development of diseases and inflammation.

  1. Modeling generic aspects of ideal fibril formation

    Energy Technology Data Exchange (ETDEWEB)

    Michel, D., E-mail: denis.michel@live.fr [Universite de Rennes1-IRSET, Campus de Beaulieu Bat. 13, 35042 Rennes (France)

    2016-01-21

    Many different proteins self-aggregate into insoluble fibrils growing apically by reversible addition of elementary building blocks. But beyond this common principle, the modalities of fibril formation are very disparate, with various intermediate forms which can be reshuffled by minor modifications of physico-chemical conditions or amino-acid sequences. To bypass this complexity, the multifaceted phenomenon of fibril formation is reduced here to its most elementary principles defined for a linear prototype of fibril. Selected generic features, including nucleation, elongation, and conformational recruitment, are modeled using minimalist hypotheses and tools, by separating equilibrium from kinetic aspects and in vitro from in vivo conditions. These reductionist approaches allow to bring out known and new rudiments, including the kinetic and equilibrium effects of nucleation, the dual influence of elongation on nucleation, the kinetic limitations on nucleation and fibril numbers, and the accumulation of complexes in vivo by rescue from degradation. Overlooked aspects of these processes are also pointed: the exponential distribution of fibril lengths can be recovered using various models because it is attributable to randomness only. It is also suggested that the same term “critical concentration” is used for different things, involved in either nucleation or elongation.

  2. RR-Interval variance of electrocardiogram for atrial fibrillation detection

    Science.gov (United States)

    Nuryani, N.; Solikhah, M.; Nugoho, A. S.; Afdala, A.; Anzihory, E.

    2016-11-01

    Atrial fibrillation is a serious heart problem originated from the upper chamber of the heart. The common indication of atrial fibrillation is irregularity of R peak-to-R-peak time interval, which is shortly called RR interval. The irregularity could be represented using variance or spread of RR interval. This article presents a system to detect atrial fibrillation using variances. Using clinical data of patients with atrial fibrillation attack, it is shown that the variance of electrocardiographic RR interval are higher during atrial fibrillation, compared to the normal one. Utilizing a simple detection technique and variances of RR intervals, we find a good performance of atrial fibrillation detection.

  3. On the role of fibril mechanics in the work of separation of fibrillating interfaces

    NARCIS (Netherlands)

    Vossen, B.G.; Sluis, van der O.; Schreurs, P.J.G.; Geers, M.G.D.; Neggers, J.; Hoefnagels, J.P.M.

    2015-01-01

    High values for the work of separation have been reported in peel tests on fibrillating interfacial systems. The exact origin of these high values is not properly understood, since it remains unclear which dissipative mechanisms related to fibrillation cause a significant increase in the work of

  4. Curcumin Protects β-Lactoglobulin Fibril Formation and Fibril-Induced Neurotoxicity in PC12 Cells.

    Directory of Open Access Journals (Sweden)

    Mansooreh Mazaheri

    Full Text Available In this study the β-lactoglobulin fibrillation, in the presence or absence of lead ions, aflatoxin M1 and curcumin, was evaluated using ThT fluorescence, Circular dichroism spectroscopy and atomic force microscopy. To investigate the toxicity of the different form of β-Lg fibrils, in the presence or absence of above toxins and curcumin, we monitored changes in the level of reactive oxygen species and morphology of the differentiated neuron-like PC12 cells. The cell viability, cell body area, average neurite length, neurite width, number of primary neurites, percent of bipolar cells and node/primary neurite ratios were used to assess the growth and complexity of PC12 cells exposed to different form of β-Lg fibrils. Incubation of β-Lg with curcumin resulted in a significant decrease in ROS levels even in the presence of lead ions and aflatoxin M1. The β-Lg fibrils formed in the presence of lead ions and aflatoxin M1 attenuated the growth and complexity of PC12 cells compared with other form of β-Lg fibrils. However, the adverse effects of these toxins and protein fibrils were negated in the presence of curcumin. Furthermore, the antioxidant and inhibitory effects of curcumin protected PC12 cells against fibril neurotoxicity and enhanced their survival. Thus, curcumin may provide a protective effect toward β-Lg, and perhaps other protein, fibrils mediated neurotoxicity.

  5. Persistent atrial fibrillation vs paroxysmal atrial fibrillation: differences in management.

    Science.gov (United States)

    Margulescu, Andrei D; Mont, Lluis

    2017-08-01

    Atrial fibrillation (AF) is the most common human arrhythmia. AF is a progressive disease, initially being nonsustained and induced by trigger activity, and progressing towards persistent AF through alteration of the atrial myocardial substrate. Treatment of AF aims to decrease the risk of stroke and improve the quality of life, by preventing recurrences (rhythm control) or controlling the heart rate during AF (rate control). In the last 20 years, catheter-based and, less frequently, surgical and hybrid ablation techniques have proven more successful compared with drug therapy in achieving rhythm control in patients with AF. However, the efficiency of ablation techniques varies greatly, being highest in paroxysmal and lowest in long-term persistent AF. Areas covered: In this review, we discuss the fundamental differences between paroxysmal and persistent AF and the potential impact of those differences on patient management, emphasizing the available therapeutic strategies to achieve rhythm control. Expert commentary: Treatment to prevent AF recurrences is suboptimal, particularly in patients with persistent AF. Emerging technologies, such as documentation of atrial fibrosis using magnetic resonance imaging and documentation of electrical substrate using advanced electrocardiographic imaging techniques are likely to provide valuable insights about patient-specific tailoring of treatments.

  6. Effect of age on stroke prevention therapy in patients with atrial fibrillation: the atrial fibrillation investigators

    DEFF Research Database (Denmark)

    van Walraven, Carl; Hart, Robert G; Connolly, Stuart

    2009-01-01

    contains patient level-data from randomized trials of stroke prevention in atrial fibrillation. We used Cox regression models with age as a continuous variable that controlled for sex, year of randomization, and history of cerebrovascular disease, diabetes, hypertension, and congestive heart failure......BACKGROUND AND PURPOSE: Stroke risk increases with age in patients who have nonvalvular atrial fibrillation. It is uncertain whether the efficacy of stroke prevention therapies in atrial fibrillation changes as patients age. The objective of this study was to determine the effect of age...... on the relative efficacy of oral anticoagulants (OAC) and antiplatelet (AP) therapy (including acetylsalicylic acid and triflusal) on ischemic stroke, serious bleeding, and vascular events in patients with atrial fibrillation. METHODS: This is an analysis of the Atrial Fibrillation Investigators database, which...

  7. Interaction of magnetic nanoparticles with lysozyme amyloid fibrils

    Energy Technology Data Exchange (ETDEWEB)

    Gdovinová, Veronika [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia); Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Tomašovičová, Natália, E-mail: nhudak@saske.sk [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia); Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Batko, Ivan; Batková, Marianna; Balejčíková, Lucia [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia); Garamus, Vasyl M. [Helmholtz-Zentrum Geesthacht: Zentrum fr Material, und Kstenforschung GmbH, Max-Plank-Strae 1, Geesthacht 216502 (Germany); Petrenko, Viktor I. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Physics Department, Taras Shevchenko Kyiv National University, Volodymyrska Street 64, 01601 Kyiv (Ukraine); Avdeev, Mikhail V. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Kopčanský, Peter [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia)

    2017-06-01

    This work is devoted to the structural study of complex solutions of magnetic nanoparticles with lysozyme amyloid fibrils due to possible ordering of such system by applying the external magnetic field. The interaction of magnetic nanoparticles with amyloid fibrils has been followed by atomic force microscopy and small-angle X-ray scattering. It has been observed that magnetic nanoparticles (MNPs) adsorb to lysozyme amyloid fibrils. It was found that MNPs alter amyloids structures, namely the diameter of lysozyme amyloid fibrils is increased whereas the length of fibrils is decreased. In the same time MNPs do not change the helical pitch significantly. - Highlights: • Solution of MNPs with lysozyme amyloid fibrils was characterized by AFM and SAXS. • MNPs adsorb to lysozyme amyloid fibrils. • Diameter and size of lysozyme amyloid fibrils change due to doping with MNPs.

  8. Spectral of electrocardiographic RR intervals to indicate atrial fibrillation

    Science.gov (United States)

    Nuryani, Nuryani; Satrio Nugroho, Anto

    2017-11-01

    Atrial fibrillation is a serious heart diseases, which is associated on the risk of death, and thus an early detection of atrial fibrillation is necessary. We have investigated spectral pattern of electrocardiogram in relation to atrial fibrillation. The utilized feature of electrocardiogram is RR interval. RR interval is the time interval between a two-consecutive R peaks. A series of RR intervals in a time segment is converted to a signal with a frequency domain. The frequency components are investigated to find the components which significantly associate to atrial fibrillation. A segment is defined as atrial fibrillation or normal segments by considering a defined number of atrial fibrillation RR in the segment. Using clinical data of 23 patients with atrial fibrillation, we find that the frequency components could be used to indicate atrial fibrillation.

  9. Risk of atrial fibrillation and stroke in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Lindhardsen, Jesper; Ahlehoff, Ole; Gislason, Gunnar Hilmar

    2012-01-01

    To determine if patients with rheumatoid arthritis have increased risk of atrial fibrillation and stroke.......To determine if patients with rheumatoid arthritis have increased risk of atrial fibrillation and stroke....

  10. Treatment Guidelines of Atrial Fibrillation (AFib or AF)

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Treatment Guidelines of Atrial Fibrillation (AFib or AF) Updated:Jun 28,2017 What are the treatment guidelines for atrial fibrillation? Medical guidelines are written by ...

  11. Management of atrial fibrillation in the setting of heart failure

    NARCIS (Netherlands)

    Crijns, HJGM; VandenBerg, MP; VanGelder, IC; VanVeldhuisen, DJ

    Heart failure is often complicated by atrial fibrillation. Once atrial fibrillation has started it further enhances heart failure due to uncontrolled rate with shortened filling time and provocation of tachycardiomyopathy. Absent atrial kick and irregularity of the ventricular rhythm also

  12. Rising rates of hospital admissions for atrial fibrillation

    DEFF Research Database (Denmark)

    Friberg, Jens; Buch, Nina Pernille Gardshodn; Scharling, Henrik

    2003-01-01

    Atrial fibrillation is a common arrhythmia associated with excess morbidity and mortality. We studied temporal changes in hospital admission rates for atrial fibrillation using data from a prospective population-based cohort study spanning 2 decades (the Copenhagen City Heart Study).......Atrial fibrillation is a common arrhythmia associated with excess morbidity and mortality. We studied temporal changes in hospital admission rates for atrial fibrillation using data from a prospective population-based cohort study spanning 2 decades (the Copenhagen City Heart Study)....

  13. Artificial atrial fibrillation in the dog. An artifact?

    NARCIS (Netherlands)

    Strackee, J.; Hoelen, A.J.; Zimmerman, A.N.E.; Meijler, F.L.

    R-R interval sequences during artificial atrial fibrillation in dogs were studied in the same way as in patients in a previous study and compared with results obtained in dogs with spontaneous atrial fibrillation. Artificial atrial fibrillation was effected by right atrial stimulation in three

  14. Alcohol consumption and risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Tolstrup, Janne Schurmann; Wium-Andersen, Marie Kim; Ørsted, David Dynnes

    2016-01-01

    BACKGROUND: The aim of this study was to test the hypothesis that alcohol consumption, both observational (self-reported) and estimated by genetic instruments, is associated with a risk of atrial fibrillation and to determine whether people with high cardiovascular risk are more sensitive towards...... alcohol than people with low risk. METHODS: We used data for a total of 88,782 men and women from the Copenhagen City Heart Study 1991-1994 and 2001-2003 and the Copenhagen General Population Study 2003-2010. Information on incident cases of atrial fibrillation was obtained from a validated nationwide...... register. As a measure of alcohol exposure, both self-reported consumption and genetic variations in alcohol metabolizing genes (ADH1B/ADH1C) were used as instrumental variables. The endpoint was admission to hospital for atrial fibrillation as recorded in a validated hospital register. RESULTS: A total...

  15. The atrial fibrillation ablation pilot study

    DEFF Research Database (Denmark)

    Arbelo, Elena; Brugada, Josep; Hindricks, Gerhard

    2014-01-01

    AIMS: The Atrial Fibrillation Ablation Pilot Study is a prospective registry designed to describe the clinical epidemiology of patients undergoing an atrial fibrillation (AFib) ablation, and the diagnostic/therapeutic processes applied across Europe. The aims of the 1-year follow-up were to analyse...... was achieved in 40.7% of patients (43.7% in paroxysmal AF; 30.2% in persistent AF; 36.7% in long-lasting persistent AF). A second ablation was required in 18% of the cases and 43.4% were under antiarrhythmic treatment. Thirty-three patients (2.5%) suffered an adverse event, 272 (21%) experienced a left atrial...... tachycardia, and 4 patients died (1 haemorrhagic stroke, 1 ventricular fibrillation in a patient with ischaemic heart disease, 1 cancer, and 1 of unknown cause). CONCLUSION: The AFib Ablation Pilot Study provided crucial information on the epidemiology, management, and outcomes of catheter ablation of AFib...

  16. Antihypertensive treatment and risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Marott, Sarah C W; Nielsen, Sune F; Benn, Marianne

    2014-01-01

    AIMS: To examine the associations between antihypertensive treatment with angiotensin-converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs), β-blockers, diuretics, or calcium-antagonists, and risk of atrial fibrillation. We examined these associations using the entire Danish...... population from 1995 through 2010. METHODS AND RESULTS: Excluding medication used in atrial fibrillation, we matched individuals on ACEi monotherapy 1:1 with individuals on β-blocker (n = 48 658), diuretic (n = 69 630), calcium-antagonist (n = 57 646), and ARB monotherapy (n = 20 158). Likewise, individuals...... on ARB monotherapy were matched 1:1 with individuals on β-blocker (n = 20 566), diuretic (n = 20 832), calcium-antagonist (n = 20 232), and ACEi monotherapy (n = 20 158). All were free of atrial fibrillation and of predisposing diseases like heart failure, ischaemic heart disease, diabetes mellitus...

  17. Digoxin for atrial fibrillation and atrial flutter

    DEFF Research Database (Denmark)

    Sethi, Naqash J; Nielsen, Emil E; Safi, Sanam

    2018-01-01

    BACKGROUND: During recent years, systematic reviews of observational studies have compared digoxin to no digoxin in patients with atrial fibrillation or atrial flutter, and the results of these reviews suggested that digoxin seems to increase the risk of all-cause mortality regardless...... of concomitant heart failure. Our objective was to assess the benefits and harms of digoxin for atrial fibrillation and atrial flutter based on randomized clinical trials. METHODS: We searched CENTRAL, MEDLINE, Embase, LILACS, SCI-Expanded, BIOSIS for eligible trials comparing digoxin versus placebo......, no intervention, or other medical interventions in patients with atrial fibrillation or atrial flutter in October 2016. Our primary outcomes were all-cause mortality, serious adverse events, and quality of life. Our secondary outcomes were heart failure, stroke, heart rate control, and conversion to sinus rhythm...

  18. Atrial natriuretic peptide in patients with heart failure and chronic atrial fibrillation : Role of duration of at atrial fibrillation

    NARCIS (Netherlands)

    Van Den Berg, MP; Crijns, HJGM; Van Veldhuisen, DJ; Van Gelder, IC; De Kam, PJ; Lie, KI

    The purpose of this study was to analyze the determinants of atrial natriuretic peptide level in patients with congestive heart failure and atrial fibrillation. In particular, the duration of atrial fibrillation was analyzed because atrial fibrillation per se might have a specific effect on atrial

  19. Uniform spatial distribution of collagen fibril radii within tendon implies local activation of pC-collagen at individual fibrils

    Science.gov (United States)

    Rutenberg, Andrew D.; Brown, Aidan I.; Kreplak, Laurent

    2016-08-01

    Collagen fibril cross-sectional radii show no systematic variation between the interior and the periphery of fibril bundles, indicating an effectively constant rate of collagen incorporation into fibrils throughout the bundle. Such spatially homogeneous incorporation constrains the extracellular diffusion of collagen precursors from sources at the bundle boundary to sinks at the growing fibrils. With a coarse-grained diffusion equation we determine stringent bounds, using parameters extracted from published experimental measurements of tendon development. From the lack of new fibril formation after birth, we further require that the concentration of diffusing precursors stays below the critical concentration for fibril nucleation. We find that the combination of the diffusive bound, which requires larger concentrations to ensure homogeneous fibril radii, and lack of nucleation, which requires lower concentrations, is only marginally consistent with fully processed collagen using conservative bounds. More realistic bounds may leave no consistent concentrations. Therefore, we propose that unprocessed pC-collagen diffuses from the bundle periphery followed by local C-proteinase activity and subsequent collagen incorporation at each fibril. We suggest that C-proteinase is localized within bundles, at fibril surfaces, during radial fibrillar growth. The much greater critical concentration of pC-collagen, as compared to fully processed collagen, then provides broad consistency between homogeneous fibril radii and the lack of fibril nucleation during fibril growth.

  20. Patients with atrial fibrillation and permanent pacemaker

    DEFF Research Database (Denmark)

    Dalgaard, Frederik; Ruwald, Martin H; Lindhardt, Tommi Bo

    2018-01-01

    BACKGROUND: The management of patients with non-valvular atrial fibrillation (NVAF) with rate-lowering or anti-arrhythmic drugs has markedly changed over the last decade, but it is unknown how these changes have affected patients with NVAF with a permanent pacemaker (PPM). METHODS: Through Danish......,261. Thus, the proportional amount of NVAF patients with a PPM decreased from 1.3% to 1.1% (p = 0.015). Overall 45.9% had atrial fibrillation (AF) duration less than one year and the proportion declined from 55.5% to 42.4% (p

  1. Atrial fibrillation and risk of stroke

    DEFF Research Database (Denmark)

    Christiansen, Christine Benn; Gerds, Thomas A.; Olesen, Jonas Bjerring

    2016-01-01

    AIM: Although the relation between stroke risk factors and stroke in patients with atrial fibrillation (AF) has been extensively examined, only few studies have explored the association of AF and the risk of ischaemic stroke/systemic thromboembolism/transient ischaemic attack (stroke.......5-10.6), and 15.4% (14.5-16.4), respectively. CONCLUSIONS: Stroke/TE/TIA risk was particularly increased when prior stroke/TE/TIA was present. Atrial fibrillation is associated with an increase in risk of stroke/TE/TIA in the absence of other risk factors but only a moderate increase in risk when other risk...

  2. Integrating new approaches to atrial fibrillation management

    DEFF Research Database (Denmark)

    Kotecha, Dipak; Breithardt, Günter; Camm, A John

    2018-01-01

    There are major challenges ahead for clinicians treating patients with atrial fibrillation (AF). The population with AF is expected to expand considerably and yet, apart from anticoagulation, therapies used in AF have not been shown to consistently impact on mortality or reduce adverse...... of the Atrial Fibrillation Network (AFNET) and the European Heart Rhythm Association (EHRA), held at the European Society of Cardiology Heart House in Sophia Antipolis, France, 17-19 January 2017. Sixty-two global specialists in AF and 13 industry partners met to develop innovative solutions based on new...

  3. Initiation of anticoagulation in atrial fibrillation

    DEFF Research Database (Denmark)

    Gundlund, A.; Staerk, L.; Fosbøl, E. L.

    2017-01-01

    Background: The use of non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prophylaxis in atrial fibrillation (AF) is increasing rapidly. We compared characteristics of AF patients initiated on NOACs versus vitamin K antagonists (VKAs). Methods: Using Danish nationwide registry data, we...... compared with a VKA [odds ratio (OR) 1.35, 95% confidence interval (CI) 1.28–1.43]. By contrast, patients with a history of myocardial infarction were less likely to be initiated on a NOAC compared with a VKA (OR 0.72, 95% CI 0.67–0.77). Conclusions: Atrial fibrillation patients who were initiated...

  4. Cryoballoon Catheter Ablation in Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Cevher Ozcan

    2011-01-01

    Full Text Available Pulmonary vein isolation with catheter ablation is an effective treatment in patients with symptomatic atrial fibrillation refractory or intolerant to antiarrhythmic medications. The cryoballoon catheter was recently approved for this procedure. In this paper, the basics of cryothermal energy ablation are reviewed including its ability of creating homogenous lesion formation, minimal destruction to surrounding vasculature, preserved tissue integrity, and lower risk of thrombus formation. Also summarized here are the publications describing the clinical experience with the cryoballoon catheter ablation in both paroxysmal and persistent atrial fibrillation, its safety and efficacy, and discussions on the technical aspect of the cryoballoon ablation procedure.

  5. Atrial fibrillation and the 4P medicine.

    Science.gov (United States)

    Censi, Federica; Cianfrocca, Cinzia; Purificato, Ivana

    2013-01-01

    Although the paradigm of the 4P medicine - Predictive, Personalized, Preemptive, and Participatory - has been suggested several years ago, its application to atrial fibrillation is still far away. Given the increasing prevalence and incidence of this pathology it is the time to promote preventive strategies, by identifying the risk factors associated to life style and by incentivizing innovative diagnostic technologies. The promotion of the correct life style and of the use of diagnostic devices based on innovative and reliable technologies, represent a first step towards the full realization of the revolution of 4P medicine in atrial fibrillation.

  6. Atrial fibrillation and the 4P medicine

    Directory of Open Access Journals (Sweden)

    Federica Censi

    2013-09-01

    Full Text Available Although the paradigm of the 4P medicine - Predictive, Personalized, Preemptive, and Participatory - has been suggested several years ago, its application to atrial fibrillation is still far away. Given the increasing prevalence and incidence of this pathology it is the time to promote preventive strategies, by identifying the risk factors associated to life style and by incentivizing innovative diagnostic technologies. The promotion of the correct life style and of the use of diagnostic devices based on innovative and reliable technologies, represent a first step towards the full realization of the revolution of 4P medicine in atrial fibrillation.

  7. Viscoelastic behavior of discrete human collagen fibrils

    DEFF Research Database (Denmark)

    Svensson, René; Hassenkam, Tue; Hansen, Philip

    2010-01-01

    Whole tendon and fibril bundles display viscoelastic behavior, but to the best of our knowledge this property has not been directly measured in single human tendon fibrils. In the present work an atomic force microscopy (AFM) approach was used for tensile testing of two human patellar tendon...... saline, cyclic testing was performed in the pre-yield region at different strain rates, and the elastic response was determined by a stepwise stress relaxation test. The elastic stress-strain response corresponded to a second-order polynomial fit, while the viscous response showed a linear dependence...

  8. New risk factors for atrial fibrillation : causes of 'not-so-lone atrial fibrillation'

    NARCIS (Netherlands)

    Schoonderwoerd, Bas A.; Smit, Marcelle D.; Pen, Lucas; Van Gelder, Isabelle C.

    Atrial fibrillation (AF) is a prevalent arrhythmia in patients with cardiovascular disease. The classical risk factors for developing AF include hypertension, valvular disease, (ischaemic) cardiomyopathy, diabetes mellitus, and thyroid disease. In some patients with AF, no underlying

  9. Protein Polymerization into Fibrils from the Viewpoint of Nucleation Theory.

    Science.gov (United States)

    Kashchiev, Dimo

    2015-11-17

    The assembly of various proteins into fibrillar aggregates is an important phenomenon with wide implications ranging from human disease to nanoscience. Using general kinetic results of nucleation theory, we analyze the polymerization of protein into linear or helical fibrils in the framework of the Oosawa-Kasai (OK) model. We show that while within the original OK model of linear polymerization the process does not involve nucleation, within a modified OK model it is nucleation-mediated. Expressions are derived for the size of the fibril nucleus, the work for fibril formation, the nucleation barrier, the equilibrium and stationary fibril size distributions, and the stationary fibril nucleation rate. Under otherwise equal conditions, this rate decreases considerably when the short (subnucleus) fibrils lose monomers much more frequently than the long (supernucleus) fibrils, a feature that should be born in mind when designing a strategy for stymying or stimulating fibril nucleation. The obtained dependence of the nucleation rate on the concentration of monomeric protein is convenient for experimental verification and for use in rate equations accounting for nucleation-mediated fibril formation. The analysis and the results obtained for linear fibrils are fully applicable to helical fibrils whose formation is describable by a simplified OK model. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Metastable Amyloid Phases and their Conversion to Mature Fibrils

    Science.gov (United States)

    Muschol, Martin; Miti, Tatiana; Mulaj, Mentor; Schmit, Jeremy

    Self-assembly of proteins into amyloid fibrils plays a key role in both functional biological responses and pathogenic disorders which include Alzheimer's disease and type II diabetes. Amyloid fibril assembly frequently generates compact oligomeric and curvilinear polymeric intermediates which are implicated to be toxic to cells. Yet, the relation between these early-stage oligomeric aggregates and late-stage rigid fibrils, which are the hallmark structure of amyloid plaques, has remained unclear. Our measurements indicate that lysozyme amyloid oligomers and their curvilinear fibrils only form after crossing a salt and protein concentration dependent threshold. These oligomeric aggregates are structurally distinct from rigid fibrils and are metastable against nucleation and growth of rigid fibrils. Our experimental transition boundaries match well with colloidal model predictions accounting for salt-modulated charge repulsion. We also report our preliminary findings on the mechanism by which these metastable oligomeric phases are converted into stable amyloid fibrils.

  11. Embolic Risk in Atrial Fibrillation that Arises from Hyperthyroidism

    Science.gov (United States)

    Traube, Elie; Coplan, Neil L.

    2011-01-01

    Atrial fibrillation, the most common cardiac complication of hyperthyroidism, occurs in an estimated 10% to 25% of overtly hyperthyroid patients. The prevalence of atrial fibrillation increases with age in the general population and in thyrotoxic patients. Other risk factors for atrial fibrillation in thyrotoxic patients include male sex, ischemic or valvular heart disease, and congestive heart failure. The incidence of arterial embolism or stroke in thyrotoxic atrial fibrillation is less clear. There are many reports of arterial thromboembolism associated with hyperthyroidism, including cases of young adults without coexisting risk factors other than thyrotoxic atrial fibrillation. The use of anticoagulative agents to prevent thromboembolic sequelae of thyrotoxic atrial fibrillation is controversial: national organizations provide conflicting recommendations in their practice guidelines. Herein, we review the medical literature and examine the evidence behind the recommendations in order to determine the best approach to thromboembolic prophylaxis in patients who have atrial fibrillation that is associated with hyperthyroidism. PMID:21720457

  12. Spontaneous conversion of first onset atrial fibrillation

    DEFF Research Database (Denmark)

    Lindberg, Søren Østergaard; Hansen, Sidsel; Nielsen, Tonny

    2011-01-01

    Background  We studied all patients admitted to hospital with first onset atrial fibrillation (AF) to determine the probability of spontaneous conversion to sinus rhythm and to identify factors predictive of such a conversion. Methods and Results  We retrospectively reviewed charts of 438...

  13. Genetic aspects of lone atrial fibrillation

    DEFF Research Database (Denmark)

    Andreasen, Laura; Nielsen, Jonas B; Olesen, Morten S

    2015-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia. A subgroup of patients presents with AF without traditional risk factors and is diagnosed before the age of 60 years. Such patients are commonly referred as having "lone AF" and comprise 10-20% of all cases. A number of studies have...

  14. Atrial fibrillation in the Middle East

    DEFF Research Database (Denmark)

    Al-Shamkhani, Warkaa; Ayetey, Harold; Lip, Gregory Y H

    2018-01-01

    INTRODUCTION: Atrial fibrillation (AF) is the commonest persistent cardiac arrhythmia with an estimated incidence rate of between 1.5-2% and an important cause of strokes. Few epidemiological studies and clinical trials on the management of AF have been conducted outside Europe and North America...

  15. An "account" of digitalis and atrial fibrillation

    NARCIS (Netherlands)

    Meijler, F.L.

    This review deals with the mechanisms by which digitalis exerts its "opium-Iike" action on the ventricular rate in patients with atrial fibrillation. To understand the effect of digitalis on ventricular rate and rhythm, it is essential to learn more about the basic electrophysiologic

  16. SAS-Based Studies of Protein Fibrillation

    DEFF Research Database (Denmark)

    Marasini, Carlotta; Vestergaard, Bente

    2017-01-01

    Protein fibrillation is associated with a number of fatal amyloid diseases (e.g. Alzheimer's and Parkinson's diseases). From a structural point of view, the aggregation process starts from an ensemble of native states that convert into transiently formed oligomers, higher order assemblies and pro...... and highlight existing reports, exemplifying the wealth of information that can be derived from the method....

  17. Aggregation and fibrillation of bovine serum albumin

    DEFF Research Database (Denmark)

    Holm, NK; Jespersen, SK; Thomassen, LV

    2007-01-01

    The all-alpha helix multi-domain protein bovine serum albumin (BSA) aggregates at elevated temperatures. Here we show that these thermal aggregates have amyloid properties. They bind the fibril-specific dyes Thioflavin T and Congo Red, show elongated although somewhat worm-like morphology...

  18. Kinetics and mechanical stability of the fibril state control fibril formation time of polypeptide chains: A computational study

    Science.gov (United States)

    Kouza, Maksim; Co, Nguyen Truong; Li, Mai Suan; Kmiecik, Sebastian; Kolinski, Andrzej; Kloczkowski, Andrzej; Buhimschi, Irina Alexandra

    2018-06-01

    Fibril formation resulting from protein misfolding and aggregation is a hallmark of several neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Despite much progress in the understanding of the protein aggregation process, the factors governing fibril formation rates and fibril stability have not been fully understood. Using lattice models, we have shown that the fibril formation time is controlled by the kinetic stability of the fibril state but not by its energy. Having performed all-atom explicit solvent molecular dynamics simulations with the GROMOS43a1 force field for full-length amyloid beta peptides Aβ40 and Aβ42 and truncated peptides, we demonstrated that kinetic stability can be accessed via mechanical stability in such a way that the higher the mechanical stability or the kinetic stability, the faster the fibril formation. This result opens up a new way for predicting fibril formation rates based on mechanical stability that may be easily estimated by steered molecular dynamics.

  19. Kinetically controlled thermal response of beta2-microglobulin amyloid fibrils.

    Science.gov (United States)

    Sasahara, Kenji; Naiki, Hironobu; Goto, Yuji

    2005-09-23

    Calorimetric measurements were carried out using a differential scanning calorimeter in the temperature range from 10 to 120 degrees C for characterizing the thermal response of beta2-microglobulin amyloid fibrils. The thermograms of amyloid fibril solution showed a remarkably large decrease in heat capacity that was essentially released upon the thermal unfolding of the fibrils, in which the magnitude of negative heat capacity change was not explicable in terms of the current accessible surface area model of protein structural thermodynamics. The heat capacity-temperature curve of amyloid fibrils prior to the fibril unfolding exhibited an unusual dependence on the fibril concentration and the heating rate. Particularly, the heat needed to induce the thermal response was found to be linearly dependent on the heating rate, indicating that its thermal response is under a kinetic control and precluding the interpretation in terms of equilibrium thermodynamics. Furthermore, amyloid fibrils of amyloid beta peptides also exhibited a heating rate-dependent exothermic process before the fibril unfolding, indicating that the kinetically controlled thermal response may be a common phenomenon to amyloid fibrils. We suggest that the heating rate-dependent negative change in heat capacity is coupled to the association of amyloid fibrils with characteristic hydration pattern.

  20. Atrial fibrillation and vascular disease-a bad combination

    DEFF Research Database (Denmark)

    Bjerring Olesen, Jonas; Gislason, Gunnar Hilmar; Torp-Pedersen, Christian

    2012-01-01

    This article provides an overview of (i) the risk of stroke associated with vascular disease (acute coronary syndromes and peripheral artery disease) in patients with atrial fibrillation, (ii) the frequent coexistence of vascular disease in patients with atrial fibrillation and, (iii...... fibrillation. Indeed, patients with atrial fibrillation often had coexisting vascular disease (around 18%), and the combination of the two diseases substantially increases the risk of future cardiovascular events. The increased risk associated with peripheral artery disease in atrial fibrillation is even more...... pronounced. Patients with atrial fibrillation and stable vascular disease should be treated with oral anticoagulation only, although when these patients present with acute coronary syndrome and/or undergo coronary stenting, concomitant treatment with antiplatelet drugs is indicated. To guide antithrombotic...

  1. Evidence of structurally continuous collagen fibrils in tendon

    DEFF Research Database (Denmark)

    Svensson, Rene B; Herchenhan, Andreas; Starborg, Tobias

    2017-01-01

    favor continuity. This study initially set out to trace the full length of individual fibrils in adult human tendons, using serial block face-scanning electron microscopy. But even with this advanced technique the required length could not be covered. Instead a statistical approach was used on a large...... volume of fibrils in shorter image stacks. Only a single end was observed after tracking 67.5 mm of combined fibril lengths, in support of fibril continuity. To shed more light on this observation, the full length of a short tendon (mouse stapedius, 125 μm) was investigated and continuity of individual...... fibrils was confirmed. In light of these results, possible mechanisms that could reconcile the opposing findings on fibril continuity are discussed. STATEMENT OF SIGNIFICANCE: Connective tissues hold all parts of the body together and are mostly constructed from thin threads of the protein collagen...

  2. Preparation of Amyloid Fibrils Seeded from Brain and Meninges.

    Science.gov (United States)

    Scherpelz, Kathryn P; Lu, Jun-Xia; Tycko, Robert; Meredith, Stephen C

    2016-01-01

    Seeding of amyloid fibrils into fresh solutions of the same peptide or protein in disaggregated form leads to the formation of replicate fibrils, with close structural similarity or identity to the original fibrillar seeds. Here we describe procedures for isolating fibrils composed mainly of β-amyloid (Aβ) from human brain and from leptomeninges, a source of cerebral blood vessels, for investigating Alzheimer's disease and cerebral amyloid angiopathy. We also describe methods for seeding isotopically labeled, disaggregated Aβ peptide solutions for study using solid-state NMR and other techniques. These methods should be applicable to other types of amyloid fibrils, to Aβ fibrils from mice or other species, tissues other than brain, and to some non-fibrillar aggregates. These procedures allow for the examination of authentic amyloid fibrils and other protein aggregates from biological tissues without the need for labeling the tissue.

  3. Endurance Sport Practice and Atrial Fibrillation

    OpenAIRE

    Calvo, Naiara; Mont, Lluis

    2010-01-01

    Atrial fibrillation (AF) is the most common cardiac rhythm disorder in clinical practice, with an estimated prevalence of 0.4% to 1% in the general population, increasing with age to 8% in those older than 80 years. The recognized risk factors for developing AF include age, hypertension, structural heart disease, diabetes mellitus, and hyperthyroidism. However, the etiology remains unclear in a significant number of patients younger than age 60 in whom no cardiovascular disease or any other k...

  4. Red Wine, Resveratrol and Atrial Fibrillation

    OpenAIRE

    Stephan, Laura Siga; Almeida, Eduardo Dytz; Markoski, Melissa Medeiros; Garavaglia, Juliano; Marcadenti, Aline

    2017-01-01

    Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with increased risk for cardiovascular disease and overall mortality. Excessive alcohol intake is a well-known risk factor for AF, but this correlation is less clear with light and moderate drinking. Besides, low doses of red wine may acutely prolong repolarization and slow cardiac conduction. Resveratrol, a bioactive polyphenol found in grapes and red wine, has been linked to antiarrhythmic properties and may act as a...

  5. Acute atrial fibrillation during dengue hemorrhagic fever

    Directory of Open Access Journals (Sweden)

    Henrique Horta Veloso

    Full Text Available Dengue fever is a viral infection transmitted by the mosquito, Aedes aegypti. Cardiac rhythm disorders, such as atrioventricular blocks and ventricular ectopic beats, appear during infection and are attributed to viral myocarditis. However, supraventricular arrhythmias have not been reported. We present a case of acute atrial fibrillation, with a rapid ventricular rate, successfully treated with intravenous amiodarone, in a 62-year-old man with dengue hemorrhagic fever, who had no structural heart disease.

  6. Acute atrial fibrillation during dengue hemorrhagic fever

    Directory of Open Access Journals (Sweden)

    Veloso Henrique Horta

    2003-01-01

    Full Text Available Dengue fever is a viral infection transmitted by the mosquito, Aedes aegypti. Cardiac rhythm disorders, such as atrioventricular blocks and ventricular ectopic beats, appear during infection and are attributed to viral myocarditis. However, supraventricular arrhythmias have not been reported. We present a case of acute atrial fibrillation, with a rapid ventricular rate, successfully treated with intravenous amiodarone, in a 62-year-old man with dengue hemorrhagic fever, who had no structural heart disease.

  7. Atrial Fibrillation in Eight New World Camelids.

    Science.gov (United States)

    Bozorgmanesh, R; Magdesian, K G; Estell, K E; Stern, J A; Swain, E A; Griffiths, L G

    2016-01-01

    There is limited information on the incidence of clinical signs, concurrent illness and treatment options for atrial fibrillation (AF) in New World Camelids (NWC). Describe clinical signs and outcome of AF in NWC. Eight New World Camelids admitted with AF. A retrospective observational study of camelids diagnosed with AF based on characteristic findings on electrocardiogram (ECG). All animals had an irregularly irregular heart rhythm detected on physical examination and 4 cases had obtunded mentation on admission. Three camelids were diagnosed with AF secondary to oleander intoxication, 3 animals had underlying cardiovascular disease, 1 was diagnosed with lone AF and 1 had AF diagnosed on examination for a urethral obstruction. Five of eight animals survived to discharge and nonsurvivors consisted of animals which died or were euthanized as a result of cardiovascular disease (2/8) or extra-cardiac disease unrelated to the AF (1/8). Atrial fibrillation occurs in NWC in association with cardiovascular disease, extra-cardiac disease or as lone AF. Amiodarone and transthoracic cardioversion were attempted in one llama with lone AF, but were unsuccessful. Atrial fibrillation was recorded in 0.1% of admissions. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  8. Atrial fibrillation pearls and perils of management.

    Science.gov (United States)

    Kudenchuk, P J

    1996-01-01

    Atrial fibrillation, a common arrhythmia, is responsible for considerable cardiovascular morbidity. Its management demands more than antiarrhythmic therapy alone, but must address the causes and consequences of the arrhythmia. Although remediable causes are infrequently found, a thorough search for associated heart disease or its risk factors results in better-informed patient management. Controlling the ventricular response and protecting from thromboembolic complications are important initial goals of therapy and may include the administration of aspirin in younger, low-risk patients. Older patients and those with risk factors for systemic embolism are not adequately protected from stroke complications by aspirin therapy alone. It remains controversial whether all high-risk patients should receive warfarin and at what intensity. Whether and how sinus rhythm should be restored and maintained poses the greatest therapeutic controversy for atrial fibrillation. The mortal risk of antiarrhythmic therapy is substantially greater in patients with evidence of heart failure. In such persons, the risks and benefits of maintaining normal sinus rhythm with antiarrhythmic medications should be weighted carefully. A definitive cure for atrial fibrillation remains elusive, but promising surgical and catheter ablation therapies are being developed. PMID:8686300

  9. Electromechanical vortex filaments during cardiac fibrillation

    Science.gov (United States)

    Christoph, J.; Chebbok, M.; Richter, C.; Schröder-Schetelig, J.; Bittihn, P.; Stein, S.; Uzelac, I.; Fenton, F. H.; Hasenfuß, G.; Gilmour, R. F., Jr.; Luther, S.

    2018-03-01

    The self-organized dynamics of vortex-like rotating waves, which are also known as scroll waves, are the basis of the formation of complex spatiotemporal patterns in many excitable chemical and biological systems. In the heart, filament-like phase singularities that are associated with three-dimensional scroll waves are considered to be the organizing centres of life-threatening cardiac arrhythmias. The mechanisms that underlie the onset, maintenance and control of electromechanical turbulence in the heart are inherently three-dimensional phenomena. However, it has not previously been possible to visualize the three-dimensional spatiotemporal dynamics of scroll waves inside cardiac tissues. Here we show that three-dimensional mechanical scroll waves and filament-like phase singularities can be observed deep inside the contracting heart wall using high-resolution four-dimensional ultrasound-based strain imaging. We found that mechanical phase singularities co-exist with electrical phase singularities during cardiac fibrillation. We investigated the dynamics of electrical and mechanical phase singularities by simultaneously measuring the membrane potential, intracellular calcium concentration and mechanical contractions of the heart. We show that cardiac fibrillation can be characterized using the three-dimensional spatiotemporal dynamics of mechanical phase singularities, which arise inside the fibrillating contracting ventricular wall. We demonstrate that electrical and mechanical phase singularities show complex interactions and we characterize their dynamics in terms of trajectories, topological charge and lifetime. We anticipate that our findings will provide novel perspectives for non-invasive diagnostic imaging and therapeutic applications.

  10. Exercise-based cardiac rehabilitation for adults with atrial fibrillation

    DEFF Research Database (Denmark)

    Risom, Signe Stelling; Zwisler, Ann-Dorthe; Johansen, Pernille Palm

    2017-01-01

    BACKGROUND: Exercise-based cardiac rehabilitation may benefit adults with atrial fibrillation or those who had been treated for atrial fibrillation. Atrial fibrillation is caused by multiple micro re-entry circuits within the atrial tissue, which result in chaotic rapid activity in the atria....... OBJECTIVES: To assess the benefits and harms of exercise-based rehabilitation programmes, alone or with another intervention, compared with no-exercise training controls in adults who currently have AF, or have been treated for AF. SEARCH METHODS: We searched the following electronic databases; CENTRAL...... the benefits and harms of exercise-based cardiac rehabilitation for adults with atrial fibrillation on patient-relevant outcomes....

  11. Does Myocardial Infarction Beget Atrial Fibrillation and Atrial Fibrillation Beget Myocardial Infarction?

    NARCIS (Netherlands)

    Vermond, Rob A.; Van Gelder, Isabelle C.; Crijns, Harry J.; Rienstra, Michiel

    2015-01-01

    Atrial fibrillation (AF) affects millions of people worldwide.(1) It is already known several decades that AF is not a benign condition, and it's associated with a 5-fold increased risk of stroke, 3-fold increased risk of heart failure, and doubling of risk of dementia and death.(2-4) Myocardial

  12. Family history of atrial fibrillation is associated with earlier-onset and more symptomatic atrial fibrillation

    DEFF Research Database (Denmark)

    Gundlund, Anna; Fosbøl, Emil Loldrup; Kim, Sunghee

    2016-01-01

    BACKGROUND: We addressed whether patients with a family history of atrial fibrillation (AF) were diagnosed as having AF earlier in life, were more symptomatic, and had worse outcomes compared with those without a family history of AF. METHODS: Using the ORBIT-AF, we compared symptoms and disease...

  13. From Fibril Formation to Fibril Properties and Rheology of Food Materials

    NARCIS (Netherlands)

    Linden, van der E.; Venema, P.

    2013-01-01

    For control and design of food properties it is important to understand how molecules and their interactions give rise to formation of microstructures and resulting rheological properties. This will be illustrated by discussing the formation and properties of fibrils in aqueous and non-aqueous

  14. La fibrillation auriculaire chez le noir Africain: Aspects ...

    African Journals Online (AJOL)

    In this retrospective work realized during two years (1st january 2002 to 31 december 2003), relative to 300 cases hospitalized at the Cardiology Institute of Abidjan, the authors have studied the epidemiologic, etiologic and prognosis factors of black african atrial fibrillation in hospital cercle. The atrial fibrillation was the most ...

  15. Dronedarone in high-risk permanent atrial fibrillation

    DEFF Research Database (Denmark)

    Connolly, Stuart J; Camm, A John; Halperin, Jonathan L

    2011-01-01

    Dronedarone restores sinus rhythm and reduces hospitalization or death in intermittent atrial fibrillation. It also lowers heart rate and blood pressure and has antiadrenergic and potential ventricular antiarrhythmic effects. We hypothesized that dronedarone would reduce major vascular events...... in high-risk permanent atrial fibrillation....

  16. Relevance of Electrical Remodeling in Human Atrial Fibrillation Results of the Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial Mechanisms of Atrial Fibrillation Study

    NARCIS (Netherlands)

    Healey, Jeff S.; Israel, Carsten W.; Connolly, Stuart J.; Hohnloser, Stefan H.; Nair, Girish M.; Divakaramenon, Syamkumar; Capucci, Alessandro; Van Gelder, Isabelle C.; Lau, Chu-Pak; Gold, Michael R.; Carlson, Mark; Themeles, Ellison; Morillo, Carlos A.

    Background-In animal models of atrial fibrillation (AF), changes in atrial electrophysiological properties are associated with the development of AF. Their relevance to human AF is unclear. Methods and Results-The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the

  17. The safety of flecainide treatment of atrial fibrillation

    DEFF Research Database (Denmark)

    Almroth, H; Andersson, Torben Bech; Fengsrud, E

    2011-01-01

    To assess the safety of long-term treatment with flecainide in patients with atrial fibrillation (AF), particularly with regard to sudden cardiac death (SCD) and proarrhythmic events.......To assess the safety of long-term treatment with flecainide in patients with atrial fibrillation (AF), particularly with regard to sudden cardiac death (SCD) and proarrhythmic events....

  18. Light Chain Amyloid Fibrils Cause Metabolic Dysfunction in Human Cardiomyocytes.

    Directory of Open Access Journals (Sweden)

    Helen P McWilliams-Koeppen

    Full Text Available Light chain (AL amyloidosis is the most common form of systemic amyloid disease, and cardiomyopathy is a dire consequence, resulting in an extremely poor prognosis. AL is characterized by the production of monoclonal free light chains that deposit as amyloid fibrils principally in the heart, liver, and kidneys causing organ dysfunction. We have studied the effects of amyloid fibrils, produced from recombinant λ6 light chain variable domains, on metabolic activity of human cardiomyocytes. The data indicate that fibrils at 0.1 μM, but not monomer, significantly decrease the enzymatic activity of cellular NAD(PH-dependent oxidoreductase, without causing significant cell death. The presence of amyloid fibrils did not affect ATP levels; however, oxygen consumption was increased and reactive oxygen species were detected. Confocal fluorescence microscopy showed that fibrils bound to and remained at the cell surface with little fibril internalization. These data indicate that AL amyloid fibrils severely impair cardiomyocyte metabolism in a dose dependent manner. These data suggest that effective therapeutic intervention for these patients should include methods for removing potentially toxic amyloid fibrils.

  19. Atrial fibrillation and bleeding complication - risk factors and risk marker

    NARCIS (Netherlands)

    Breithardt, G.; Ravens, U.; Kirchhof, P.; van Gelder, I. C.

    2012-01-01

    The development of atrial fibrillation (AF) is closely linked to risk factors like hypertension and heart failure, diabetes mellitus, myocardial infarction and valvular heart disease. These factors partly overlap with those which determine the progression of atrial fibrillation and the incidence of

  20. Effect of Stirring and Seeding on Whey Protein Fibril Formation

    NARCIS (Netherlands)

    Bolder, S.G.; Sagis, L.M.C.; Venema, P.; Linden, van der E.

    2007-01-01

    The effect of stirring and seeding on the formation of fibrils in whey protein isolate (WPI) solutions was studied. More fibrils of a similar length are formed when WPI is stirred during heating at pH 2 and 80 C compared to samples that were heated at rest. Addition of seeds did not show an

  1. Aggregation properties of a short peptide that mediates amyloid fibril ...

    Indian Academy of Sciences (India)

    Short peptides have been identified from amyloidogenic proteins that form amyloid fibrils in isolation. The ... proteins. These peptide fibrils have the conformational features of β-structure that .... water and immediately deposited on freshly cleaved surface of mica .... with the peptide via electrostatic interactions. NaCl would.

  2. Polymorphism complexity and handedness inversion in serum albumin amyloid fibrils.

    Science.gov (United States)

    Usov, Ivan; Adamcik, Jozef; Mezzenga, Raffaele

    2013-12-23

    Protein-based amyloid fibrils can show a great variety of polymorphic structures within the same protein precursor, although the origins of these structural homologues remain poorly understood. In this work we investigate the fibrillation of bovine serum albumin--a model globular protein--and we follow the polymorphic evolution by a statistical analysis of high-resolution atomic force microscopy images, complemented, at larger length scales, by concepts based on polymer physics formalism. We identify six distinct classes of coexisting amyloid fibrils, including flexible left-handed twisted ribbons, rigid right-handed helical ribbons and nanotubes. We show that the rigid fibrils originate from flexible fibrils through two diverse polymorphic transitions, first, via a single-fibril transformation when the flexible left-handed twisted ribbons turn into the helical left-handed ribbons, to finally evolve into nanotube-like structures, and second, via a double-fibril transformation when two flexible left-handed twisted ribbons wind together resulting in a right-handed twisted ribbon, followed by a rigid right-handed helical ribbon polymorphic conformation. Hence, the change in handedness occurs with an increase in the level of the fibril's structural organization.

  3. Genetics of Atrial Fibrillation and Possible Implications for Ischemic Stroke

    Directory of Open Access Journals (Sweden)

    Robin Lemmens

    2011-01-01

    Full Text Available Atrial fibrillation is the most common cardiac arrhythmia mainly caused by valvular, ischemic, hypertensive, and myopathic heart disease. Atrial fibrillation can occur in families suggesting a genetic background especially in younger subjects. Additionally recent studies have identified common genetic variants to be associated with atrial fibrillation in the general population. This cardiac arrhythmia has important public health implications because of its main complications: congestive heart failure and ischemic stroke. Since atrial fibrillation can result in ischemic stroke, one might assume that genetic determinants of this cardiac arrhythmia are also implicated in cerebrovascular disease. Ischemic stroke is a multifactorial, complex disease where multiple environmental and genetic factors interact. Whether genetic variants associated with a risk factor for ischemic stroke also increase the risk of a particular vascular endpoint still needs to be confirmed in many cases. Here we review the current knowledge on the genetic background of atrial fibrillation and the consequences for cerebrovascular disease.

  4. NASA's First Atrial Fibrillation Case - Deke Slayton

    Science.gov (United States)

    Tarver, William J.

    2010-01-01

    Concerns about heart dysrhythmia have been present since the earliest days of the US manned space program. While information about an astronaut's health is general kept private, one of the original seven American astronaut's health status was played out in a very public forum. Donald "Deke" Slayton was removed from the second manned space flight when it was discovered he had idiopathic atrial fibrillation. Referencing the original medical documents, details of how this was discovered and managed from the medical perspective will be reviewed. This is NASA's first heart dysrhythmia case in an astronaut and it proves quite interesting when placed in historic perspective.

  5. Current approaches in atrial fibrillation treatment

    Directory of Open Access Journals (Sweden)

    Cenk Sarı

    2014-09-01

    Full Text Available Atrial fibrillation (AF is the most common sustained arrhythmia encountered in clinical practice. Its incidence increases with age. AF is classified into subtypes according to the duration and/or able to provide sinus rhytym. İnitially, patients should be evaluated for rhythm or rate control for appropriate treatment. Second stage of strategy aimed to investigate the feasibility of anticoagulation therapy. Recently, due to the progress made in treatment with rhythm control and anticoagulation therapy, either American or European guidelines have been renovated. These developments have taken place in the newly published guide. In this article, the current change in the management of AF is discussed.

  6. The contrasting effect of macromolecular crowding on amyloid fibril formation.

    Directory of Open Access Journals (Sweden)

    Qian Ma

    Full Text Available Amyloid fibrils associated with neurodegenerative diseases can be considered biologically relevant failures of cellular quality control mechanisms. It is known that in vivo human Tau protein, human prion protein, and human copper, zinc superoxide dismutase (SOD1 have the tendency to form fibril deposits in a variety of tissues and they are associated with different neurodegenerative diseases, while rabbit prion protein and hen egg white lysozyme do not readily form fibrils and are unlikely to cause neurodegenerative diseases. In this study, we have investigated the contrasting effect of macromolecular crowding on fibril formation of different proteins.As revealed by assays based on thioflavin T binding and turbidity, human Tau fragments, when phosphorylated by glycogen synthase kinase-3β, do not form filaments in the absence of a crowding agent but do form fibrils in the presence of a crowding agent, and the presence of a strong crowding agent dramatically promotes amyloid fibril formation of human prion protein and its two pathogenic mutants E196K and D178N. Such an enhancing effect of macromolecular crowding on fibril formation is also observed for a pathological human SOD1 mutant A4V. On the other hand, rabbit prion protein and hen lysozyme do not form amyloid fibrils when a crowding agent at 300 g/l is used but do form fibrils in the absence of a crowding agent. Furthermore, aggregation of these two proteins is remarkably inhibited by Ficoll 70 and dextran 70 at 200 g/l.We suggest that proteins associated with neurodegenerative diseases are more likely to form amyloid fibrils under crowded conditions than in dilute solutions. By contrast, some of the proteins that are not neurodegenerative disease-associated are unlikely to misfold in crowded physiological environments. A possible explanation for the contrasting effect of macromolecular crowding on these two sets of proteins (amyloidogenic proteins and non-amyloidogenic proteins has been

  7. Increased amount of atrial fibrosis in patients with atrial fibrillation secondary to mitral valve disease

    NARCIS (Netherlands)

    Geuzebroek, Guillaume S. C.; van Amersfoorth, Shirley C. M.; Hoogendijk, Mark G.; Kelder, Johannes C.; van Hemel, Norbert M.; de Bakker, Jacques M. T.; Coronel, Ruben

    2012-01-01

    Objective: Atrial fibrosis is related to atrial fibrillation but may differ in patients with mitral valve disease or lone atrial fibrillation. Therefore, we studied atrial fibrosis in patients with atrial fibrillation + mitral valve disease or with lone atrial fibrillation and compared it with

  8. Atrial Fibrillation: When the heart is not in rhythm | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: When the heart is not in rhythm Past ... show, Deal With It . Photo: TBS/Deal Understanding Atrial Fibrillation Atrial fibrillation (AFib) is the most common type ...

  9. Organized Atrial Tachycardias after Atrial Fibrillation Ablation

    Science.gov (United States)

    Castrejón-Castrejón, Sergio; Ortega, Marta; Pérez-Silva, Armando; Doiny, David; Estrada, Alejandro; Filgueiras, David; López-Sendón, José L.; Merino, José L.

    2011-01-01

    The efficacy of catheter-based ablation techniques to treat atrial fibrillation is limited not only by recurrences of this arrhythmia but also, and not less importantly, by new-onset organized atrial tachycardias. The incidence of such tachycardias depends on the type and duration of the baseline atrial fibrillation and specially on the ablation technique which was used during the index procedure. It has been repeatedly reported that the more extensive the left atrial surface ablated, the higher the incidence of organized atrial tachycardias. The exact origin of the pathologic substrate of these trachycardias is not fully understood and may result from the interaction between preexistent regions with abnormal electrical properties and the new ones resultant from radiofrequency delivery. From a clinical point of view these atrial tachycardias tend to remit after a variable time but in some cases are responsible for significant symptoms. A precise knowledge of the most frequent types of these arrhythmias, of their mechanisms and components is necessary for a thorough electrophysiologic characterization if a new ablation procedure is required. PMID:21941669

  10. Fibril formation from pea protein and subsequent gel formation.

    Science.gov (United States)

    Munialo, Claire Darizu; Martin, Anneke H; van der Linden, Erik; de Jongh, Harmen H J

    2014-03-19

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20 h at pH 2.0. Following heating of pea proteins, it was observed that all of the proteins were hydrolyzed into peptides and that 50% of these peptides were assembled into fibrils. Changes on a structural level in pea proteins were studied using circular dichroism, transmission electron microscopy, and particle size analysis. During the fibril assembly process, an increase in aggregate size was observed, which coincided with an increase in thioflavin T binding, indicating the presence of β-sheet aggregates. Fibrils made using pea proteins were more branched and curly. Gel formation of preformed fibrils was induced by slow acidification from pH 7.0 to a final pH of around pH 5.0. The ability of pea protein-based fibrillar gels to fracture during an amplitude sweep was comparable to those of soy protein and whey protein-based fibrillar gels, although gels prepared from fibrils made using pea protein and soy protein were weaker than those of whey protein. The findings show that fibrils can be prepared from pea protein, which can be incorporated into protein-based fibrillar gels.

  11. Sequence dependent aggregation of peptides and fibril formation

    Science.gov (United States)

    Hung, Nguyen Ba; Le, Duy-Manh; Hoang, Trinh X.

    2017-09-01

    Deciphering the links between amino acid sequence and amyloid fibril formation is key for understanding protein misfolding diseases. Here we use Monte Carlo simulations to study the aggregation of short peptides in a coarse-grained model with hydrophobic-polar (HP) amino acid sequences and correlated side chain orientations for hydrophobic contacts. A significant heterogeneity is observed in the aggregate structures and in the thermodynamics of aggregation for systems of different HP sequences and different numbers of peptides. Fibril-like ordered aggregates are found for several sequences that contain the common HPH pattern, while other sequences may form helix bundles or disordered aggregates. A wide variation of the aggregation transition temperatures among sequences, even among those of the same hydrophobic fraction, indicates that not all sequences undergo aggregation at a presumable physiological temperature. The transition is found to be the most cooperative for sequences forming fibril-like structures. For a fibril-prone sequence, it is shown that fibril formation follows the nucleation and growth mechanism. Interestingly, a binary mixture of peptides of an aggregation-prone and a non-aggregation-prone sequence shows the association and conversion of the latter to the fibrillar structure. Our study highlights the role of a sequence in selecting fibril-like aggregates and also the impact of a structural template on fibril formation by peptides of unrelated sequences.

  12. Replica Exchange Simulations of the Thermodynamics of Aβ Fibril Growth

    Science.gov (United States)

    Takeda, Takako; Klimov, Dmitri K.

    2009-01-01

    Abstract Replica exchange molecular dynamics and an all-atom implicit solvent model are used to probe the thermodynamics of deposition of Alzheimer's Aβ monomers on preformed amyloid fibrils. Consistent with the experiments, two deposition stages have been identified. The docking stage occurs over a wide temperature range, starting with the formation of the first peptide-fibril interactions at 500 K. Docking is completed when a peptide fully adsorbs on the fibril edge at the temperature of 380 K. The docking transition appears to be continuous, and occurs without free energy barriers or intermediates. During docking, incoming Aβ monomer adopts a disordered structure on the fibril edge. The locking stage occurs at the temperature of ≈360 K and is characterized by the rugged free energy landscape. Locking takes place when incoming Aβ peptide forms a parallel β-sheet structure on the fibril edge. Because the β-sheets formed by locked Aβ peptides are typically off-registry, the structure of the locked phase differs from the structure of the fibril interior. The study also reports that binding affinities of two distinct fibril edges with respect to incoming Aβ peptides are different. The peptides bound to the concave edge have significantly lower free energy compared to those bound on the convex edge. Comparison with the available experimental data is discussed. PMID:19167295

  13. Proinsulin C-peptide interferes with insulin fibril formation

    International Nuclear Information System (INIS)

    Landreh, Michael; Stukenborg, Jan-Bernd; Willander, Hanna; Söder, Olle; Johansson, Jan; Jörnvall, Hans

    2012-01-01

    Highlights: ► Insulin and C-peptide can interact under insulin fibril forming conditions. ► C-peptide is incorporated into insulin aggregates and alters aggregation lag time. ► C-peptide changes insulin fibril morphology and affects backbone accessibility. ► C-peptide may be a regulator of fibril formation by β-cell granule proteins. -- Abstract: Insulin aggregation can prevent rapid insulin uptake and cause localized amyloidosis in the treatment of type-1 diabetes. In this study, we investigated the effect of C-peptide, the 31-residue peptide cleaved from proinsulin, on insulin fibrillation at optimal conditions for fibrillation. This is at low pH and high concentration, when the fibrils formed are regular and extended. We report that C-peptide then modulates the insulin aggregation lag time and profoundly changes the fibril appearance, to rounded clumps of short fibrils, which, however, still are Thioflavine T-positive. Electrospray ionization mass spectrometry also indicates that C-peptide interacts with aggregating insulin and is incorporated into the aggregates. Hydrogen/deuterium exchange mass spectrometry further reveals reduced backbone accessibility in insulin aggregates formed in the presence of C-peptide. Combined, these effects are similar to those of C-peptide on islet amyloid polypeptide fibrillation and suggest that C-peptide has a general ability to interact with amyloidogenic proteins from pancreatic β-cell granules. Considering the concentrations, these peptide interactions should be relevant also during physiological secretion, and even so at special sites post-secretory or under insulin treatment conditions in vivo.

  14. Proinsulin C-peptide interferes with insulin fibril formation

    Energy Technology Data Exchange (ETDEWEB)

    Landreh, Michael [Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm (Sweden); Stukenborg, Jan-Bernd [Department of Women' s and Children' s Health, Astrid Lindgren Children' s Hospital, Pediatric Endocrinology Unit, Karolinska Institutet and University Hospital, S-17176 Stockholm (Sweden); Willander, Hanna [KI-Alzheimer' s Disease Research Center, NVS Department, Karolinska Institutet, S-141 86 Stockholm (Sweden); Soeder, Olle [Department of Women' s and Children' s Health, Astrid Lindgren Children' s Hospital, Pediatric Endocrinology Unit, Karolinska Institutet and University Hospital, S-17176 Stockholm (Sweden); Johansson, Jan [KI-Alzheimer' s Disease Research Center, NVS Department, Karolinska Institutet, S-141 86 Stockholm (Sweden); Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, S-751 23 Uppsala (Sweden); Joernvall, Hans, E-mail: Hans.Jornvall@ki.se [Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm (Sweden)

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer Insulin and C-peptide can interact under insulin fibril forming conditions. Black-Right-Pointing-Pointer C-peptide is incorporated into insulin aggregates and alters aggregation lag time. Black-Right-Pointing-Pointer C-peptide changes insulin fibril morphology and affects backbone accessibility. Black-Right-Pointing-Pointer C-peptide may be a regulator of fibril formation by {beta}-cell granule proteins. -- Abstract: Insulin aggregation can prevent rapid insulin uptake and cause localized amyloidosis in the treatment of type-1 diabetes. In this study, we investigated the effect of C-peptide, the 31-residue peptide cleaved from proinsulin, on insulin fibrillation at optimal conditions for fibrillation. This is at low pH and high concentration, when the fibrils formed are regular and extended. We report that C-peptide then modulates the insulin aggregation lag time and profoundly changes the fibril appearance, to rounded clumps of short fibrils, which, however, still are Thioflavine T-positive. Electrospray ionization mass spectrometry also indicates that C-peptide interacts with aggregating insulin and is incorporated into the aggregates. Hydrogen/deuterium exchange mass spectrometry further reveals reduced backbone accessibility in insulin aggregates formed in the presence of C-peptide. Combined, these effects are similar to those of C-peptide on islet amyloid polypeptide fibrillation and suggest that C-peptide has a general ability to interact with amyloidogenic proteins from pancreatic {beta}-cell granules. Considering the concentrations, these peptide interactions should be relevant also during physiological secretion, and even so at special sites post-secretory or under insulin treatment conditions in vivo.

  15. Probing the mechanism of insulin fibril formation with insulin mutants.

    Science.gov (United States)

    Nielsen, L; Frokjaer, S; Brange, J; Uversky, V N; Fink, A L

    2001-07-27

    The molecular basis of insulin fibril formation was investigated by studying the structural properties and kinetics of fibril formation of 20 different human insulin mutants at both low pH (conditions favoring monomer/dimer) and at pH 7.4 (conditions favoring tetramer/hexamer). Small-angle X-ray scattering showed insulin to be monomeric in 20% acetic acid, 0.1 M NaCl, pH 2. The secondary structure of the mutants was assessed using far-UV circular dichroism, and the tertiary structure was determined using near-UV circular dichroism, quenching of intrinsic fluorescence by acrylamide and interactions with the hydrophobic probe 1-anilino-8-naphthalene-sulfonic acid (ANS). The kinetics of fibril formation were monitored with the fluorescent dye, Thioflavin T. The results indicate that the monomer is the state from which fibrils arise, thus under some conditions dissociation of hexamers may be rate limiting or partially rate limiting. The insulin mutants were found to retain substantial nativelike secondary and tertiary structure under all conditions studied. The results suggest that fibril formation of the insulin mutants is controlled by specific molecular interactions that are sensitive to variations in the primary structure. The observed effects of several mutations on the rate of fibril formation are inconsistent with a previously suggested model for fibrillation [Brange, J., Whittingham, J., Edwards, D., Youshang, Z., Wollmer, A., Brandenburg, D., Dodson, G., and Finch, J. (1997) Curr. Sci. 72, 470-476]. Two surfaces on the insulin monomer are identified as potential interacting sites in insulin fibrils, one consisting of the residues B10, B16, and B17 and the other consisting of at least the residues A8 and B25. The marked increase in the lag time for fibril formation with mutations to more polar residues, as well as mutations to charged residues, demonstrates the importance of both hydrophobic and electrostatic interactions in the initial stages of fibrillation

  16. Normal and reversed supramolecular chirality of insulin fibrils probed by vibrational circular dichroism at the protofilament level of fibril structure.

    Science.gov (United States)

    Kurouski, Dmitry; Dukor, Rina K; Lu, Xuefang; Nafie, Laurence A; Lednev, Igor K

    2012-08-08

    Fibrils are β-sheet-rich aggregates that are generally composed of several protofibrils and may adopt variable morphologies, such as twisted ribbons or flat-like sheets. This polymorphism is observed for many different amyloid associated proteins and polypeptides. In a previous study we proposed the existence of another level of amyloid polymorphism, namely, that associated with fibril supramolecular chirality. Two chiral polymorphs of insulin, which can be controllably grown by means of small pH variations, exhibit opposite signs of vibrational circular dichroism (VCD) spectra. Herein, using atomic force microscopy (AFM) and scanning electron microscopy (SEM), we demonstrate that indeed VCD supramolecular chirality is correlated not only by the apparent fibril handedness but also by the sense of supramolecular chirality from a deeper level of chiral organization at the protofilament level of fibril structure. Our microscopic examination indicates that normal VCD fibrils have a left-handed twist, whereas reversed VCD fibrils are flat-like aggregates with no obvious helical twist as imaged by atomic force microscopy or scanning electron microscopy. A scheme is proposed consistent with observed data that features a dynamic equilibrium controlled by pH at the protofilament level between left- and right-twist fibril structures with distinctly different aggregation pathways for left- and right-twisted protofilaments. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  17. Clinical characteristics, management, and control of permanent vs. nonpermanent atrial fibrillation: insights from the RealiseAF survey.

    LENUS (Irish Health Repository)

    Murin, Jan

    2014-01-01

    Atrial fibrillation can be categorized into nonpermanent and permanent atrial fibrillation. There is less information on permanent than on nonpermanent atrial fibrillation patients. This analysis aimed to describe the characteristics and current management, including the proportion of patients with successful atrial fibrillation control, of these atrial fibrillation subsets in a large, geographically diverse contemporary sample.

  18. Attitudes Towards Catheter Ablation for Atrial Fibrillation

    DEFF Research Database (Denmark)

    Vadmann, Henrik; Pedersen, Susanne S; Nielsen, Jens Cosedis

    2015-01-01

    BACKGROUND: Catheter ablation for atrial fibrillation (AF) is an important but expensive procedure that is the subject of some debate. Physicians´ attitudes towards catheter ablation may influence promotion and patient acceptance. This is the first study to examine the attitudes of Danish...... cardiologists towards catheter ablation for AF, using a nationwide survey. METHODS AND RESULTS: We developed a purpose-designed questionnaire to evaluate attitudes towards catheter ablation for AF that was sent to all Danish cardiologists (n = 401; response n = 272 (67.8%)). There was no association between...... attitudes towards ablation and the experience or age of the cardiologist with respect to patients with recurrent AF episodes with a duration of 7 days and/or need for cardioversion. The majority (69%) expected a recurrence of AF after catheter ablation in more than 30% of the cases...

  19. Pathogenic Mechanisms of Atrial Fibrillation in Obesity

    Directory of Open Access Journals (Sweden)

    O. M. Drapkina

    2016-01-01

    Full Text Available Atrial fibrillation (AF is one of the most common arrhythmias. It reduces quality of life and its duration due to thromboembolic complications. Obesity contributes to the structural and electrical remodeling of atrial myocardium. This leads to occurrence of ectopic foci in the mouths of the pulmonary veins and the disruption of normal electrical conduction in the atria. Systemic inflammation, myocardial fibrosis, cardiomyocyte overload by Na+ and Ca2+ ions, accumulation in the cells of unoxidized metabolic products, imbalance of the autonomic regulation are considered as the main mechanisms of arrhythmogenic substrate formation. Hypertension, insulin resistance, and obstructive sleep apnea, associated with obesity, increase the risk of development and progression of the arrhythmia. Study of pathogenetic mechanisms of AF in obesity is necessary to develop new strategies for its prevention and the creation of more effective methods of treatment of these patients.

  20. Advances in Imaging for Atrial Fibrillation Ablation

    International Nuclear Information System (INIS)

    D'Silva, A.; Wright, M.; Wright, M.

    2011-01-01

    Over the last fifteen years, our understanding of the pathophysiology of atrial fibrillation (AF) has paved the way for ablation to be utilized as an effective treatment option. With the aim of gaining more detailed anatomical representation, advances have been made using various imaging modalities, both before and during the ablation procedure, in planning and execution. Options have flourished from procedural fluoroscopy, electro anatomic mapping systems, pre procedural computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and combinations of these technologies. Exciting work is underway in an effort to allow the electro physiologist to assess scar formation in real time. One advantage would be to lessen the learning curve for what are very complex procedures. The hope of these developments is to improve the likelihood of a successful ablation procedure and to allow more patients access to this treatment

  1. Alcohol and Atrial Fibrillation: A Sobering Review.

    Science.gov (United States)

    Voskoboinik, Aleksandr; Prabhu, Sandeep; Ling, Liang-Han; Kalman, Jonathan M; Kistler, Peter M

    2016-12-13

    Alcohol is popular in Western culture, supported by a perception that modest intake is cardioprotective. However, excessive drinking has detrimental implications for cardiovascular disease. Atrial fibrillation (AF) following an alcohol binge or the "holiday heart syndrome" is well characterized. However, more modest levels of alcohol intake on a regular basis may also increase the risk of AF. The pathophysiological mechanisms responsible for the relationship between alcohol and AF may include direct toxicity and alcohol's contribution to obesity, sleep-disordered breathing, and hypertension. We aim to provide a comprehensive review of the epidemiology and pathophysiology by which alcohol may be responsible for AF and determine whether alcohol abstinence is required for patients with AF. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  2. [Atrial fibrillation concomitant with valvular heart disease].

    Science.gov (United States)

    Ishii, Yosuke

    2013-01-01

    Patients with valvular heart disease frequently have atrial fibrillation(AF) due to elevated pressure and dilatation of the left and right atria and pulmonary veins. Guidelines for valvular heart disease and AF recommend that surgical treatment for the valvular heart disease should be performed concomitantly with AF surgery. The Full-Maze procedure has evolved into the gold standard of treatment for medically refractory AF. In addition to the pulmonary vein isolation, the right and left atrial incisions of the Full-Maze procedure are designed to block potential macroreentrant pathways. According to the mechanisms of AF with valvular heart disease, the Full-Maze procedure is more effective for the patients than the pulmonary vein isolation alone.

  3. Prognosis of ventricular fibrillation in hospital

    DEFF Research Database (Denmark)

    Jensen, G V; Torp-Pedersen, C; Køber, L

    1992-01-01

    In a retrospective study of 520 patients with in-hospital ventricular fibrillation 421 (81%) had acute myocardial infarction (MI), 66 (13%) had ischaemic heart disease (IHD) without MI, 33 (6%) had no signs of IHD. The in-hospital mortality of these three groups was 51%, 52%, and 27%, respectively...... (P = 0.01). Logistic regression analysis demonstrated that heart failure and cardiogenic shock were significant risk factors for in-hospital death among patients with IHD. Among discharged patients 1 and 5 years survival was 78% and 51% for patients with MI, 63% and 25% for patients with IHD, 67...... with known IHD suffering in-hospital VF without AMI have a very poor short- and long-term prognosis. These patients need extensive cardiac examination....

  4. Visualisation of collagen fibrils in joint cartilage using STIM

    International Nuclear Information System (INIS)

    Reinert, T.; Reibetanz, U.; Vogt, J.; Butz, T.; Werner, A.; Gruender, W.

    2001-01-01

    The scanning transmission ion microscopy (STIM) method was used to investigate the collagen network structure of the articular cartilage from a pig's knee in comparison with high resolution nuclear magnetic resonance imaging (microscopic NMR-tomography) and polarised light microscopy (PLM). Single collagen fibrils down to 200 nm in diameter were visualised. It was proved that the cartilage collagen network consists partly of zones of oriented fibrils as suggested by NMR measurements. Radially oriented fibrils were found in the zone near the calcified zone (hypertrophic zone) of both tibia and femur, and in the tibial radial zone. Tangentially oriented fibrils were found in the femoral and tibial superficial zone and in a second zone of the femoral cartilage. Polarisation light microscopy reveals broader zones of orientation than it was found with STIM

  5. Dabigatran use in Danish atrial fibrillation patients in 2011

    DEFF Research Database (Denmark)

    Sørensen, Rikke; Gislason, Gunnar; Torp-Pedersen, Christian Tobias

    2013-01-01

    Objective: Dabigatran was recently approved for anticoagulation in patients with atrial fibrillation (AF); data regarding real-world use, comparative effectiveness and safety are sparse. Design: Pharmacoepidemiological cohort study. Methods/settings: From nationwide registers, we identified...

  6. Analysis of XFEL serial diffraction data from individual crystalline fibrils

    Directory of Open Access Journals (Sweden)

    David H. Wojtas

    2017-11-01

    Full Text Available Serial diffraction data collected at the Linac Coherent Light Source from crystalline amyloid fibrils delivered in a liquid jet show that the fibrils are well oriented in the jet. At low fibril concentrations, diffraction patterns are recorded from single fibrils; these patterns are weak and contain only a few reflections. Methods are developed for determining the orientation of patterns in reciprocal space and merging them in three dimensions. This allows the individual structure amplitudes to be calculated, thus overcoming the limitations of orientation and cylindrical averaging in conventional fibre diffraction analysis. The advantages of this technique should allow structural studies of fibrous systems in biology that are inaccessible using existing techniques.

  7. Women Sex Importance in Stroke Patients with Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Cemile Handan Mısırlı

    2014-08-01

    Full Text Available OBJECTIVE: It was shown the differences in age, risk factors and treatment between women and men in stroke patients with atrial fibrillation METHODS: The stroke patients with atrial fibrillation who were hospitalized in our department at the last 2 years were seperated into 2 groups of aged above 75 and below 75, investigated with CHADS2 and CHA2DS2VASc scores and looked at the sex differences of women and men. RESULTS: Stroke ratio according to sex was statistically meaningful especially in women above the age of 75. Risc factors also were founded in elderly women and CHA2DS2VASc scores were higher in women than men so more anticoagulan treatment were begun. No differences were shown between sexes at lone atrial fibrillation and no treatment were begun. CONCLUSION: Women with atrial fibrillation had more risk factors, higher stroke rate and higher anticoagulation treatment.

  8. Atrial fibrillation in the dog: a review of eight cases

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. E. [Vet. Hospital, 34 New Dover Rd, Canterbury, Kent (United Kingdom)

    1984-07-01

    Eight cases of canine atrial fibrillation encountered in small animal practice are reported. Details are included of age, sex and breed, history and clinical signs, thoracic radiography, electrocardiography, clinical pathology, treatment and survival periods.

  9. Atrial fibrillation in the dog: a review of eight cases

    International Nuclear Information System (INIS)

    Thomas, R.E.

    1984-01-01

    Eight cases of canine atrial fibrillation encountered in small animal practice are reported. Details are included of age, sex and breed, history and clinical signs, thoracic radiography, electrocardiography, clinical pathology, treatment and survival periods

  10. Inflammation in the genesis and perpetuation of atrial fibrillation

    DEFF Research Database (Denmark)

    Engelmann, Mads D M; Svendsen, Jesper Hastrup

    2005-01-01

    The prevalence and persistence of atrial fibrillation (AF) and the relative inefficacy of the currently available pharmacotherapy requires development of new treatment strategies. Recent findings have suggested a mechanistic link between inflammatory processes and the development of AF...

  11. How curcumin affords effective protection against amyloid fibrillation in insulin?

    DEFF Research Database (Denmark)

    Rabiee, Atefeh; Ebrahim Habibi, Azadeh; Ghasemi, Atiyeh Ghasemi

    2013-01-01

    Since the formation of amyloid structures from proteins was recognized in numerous diseases, many efforts have been devoted to the task of finding effective anti-amyloidogenic compounds. In a number of these investigations, the existence of “generic” compounds is implicitly acknowledged. Curcumin...... been shown effectively influenced by micro molar concentrations of curcumin. Under amyloidogenic conditions (pH 2.5 and 37°C), the compound was observed to inhibit fibril formation of insulin in a dose-dependent manner. Moreover, addition of curcumin to the protein incubated in such conditions...... at different time points resulted in reduced amounts of final fibrils. Disaggregation of pre-formed fibrils was also observed upon addition of curcumin, as well as reduction in final fibril amounts after seeding. Overall, this compound appears to be able to interact with native, intermediate and fibrillar...

  12. Ventricular fibrillation after accidental injection of bupivacaine into the pericardium

    NARCIS (Netherlands)

    Even, B. J.; de Jongh, R. F.; de Hert, S. G.

    1992-01-01

    A postoperative cardiac surgical patient developed ventricular fibrillation immediately after accidental pericardial injection of bupivacaine at room temperature. The possible causes, which include systemic toxicity, local vasoconstriction with myocardial ischaemia, local toxic effect of bupivacaine

  13. Long working hours as a risk factor for atrial fibrillation

    DEFF Research Database (Denmark)

    Kivimäki, Mika; Nyberg, Solja T.; Batty, G. David

    2017-01-01

    long hours (≤55 per week) and those working standard 35-40 h/week. Methods and results In this prospective multi-cohort study from the Individual-Participant-Data Meta-Analysis in Working Populations (IPD-Work) Consortium, the study population was 85 494 working men and women (mean age 43.4 years...... of atrial fibrillation (10-year cumulative incidence 12.4 per 1000). After adjustment for age, sex and socioeconomic status, individuals working long hours had a 1.4-fold increased risk of atrial fibrillation compared with those working standard hours (hazard ratio = 1.42, 95% CI= 1.13-1.80, P= 0......Aims Studies suggest that people who work long hours are at increased risk of stroke, but the association of long working hours with atrial fibrillation, the most common cardiac arrhythmia and a risk factor for stroke, is unknown. We examined the risk of atrial fibrillation in individuals working...

  14. Analysis of amyloid fibrils in the cheetah (Acinonyx jubatus).

    Science.gov (United States)

    Bergström, Joakim; Ueda, Mitsuharu; Une, Yumi; Sun, Xuguo; Misumi, Shogo; Shoji, Shozo; Ando, Yukio

    2006-06-01

    Recently, a high prevalence of amyloid A (AA) amyloidosis has been documented among captive cheetahs worldwide. Biochemical analysis of amyloid fibrils extracted from the liver of a Japanese captive cheetah unequivocally showed that protein AA was the main fibril constituent. Further characterization of the AA fibril components by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis revealed three main protein AA bands with approximate molecular weights of 8, 10 and 12 kDa. Mass spectrometry analysis of the 12-kDa component observed in SDS-PAGE and Western blotting confirmed the molecular weight of a 12,381-Da peak. Our finding of a 12-kDa protein AA component provides evidence that the cheetah SAA sequence is longer than the previously reported 90 amino acid residues (approximately 10 kDa), and hence SAA is part of the amyloid fibril.

  15. Dronedarone in high-risk permanent atrial fibrillation

    DEFF Research Database (Denmark)

    Connolly, Stuart J; Camm, A John; Halperin, Jonathan L

    2011-01-01

    Dronedarone restores sinus rhythm and reduces hospitalization or death in intermittent atrial fibrillation. It also lowers heart rate and blood pressure and has antiadrenergic and potential ventricular antiarrhythmic effects. We hypothesized that dronedarone would reduce major vascular events in ...

  16. Insulin fibrillation: The influence and coordination of Zn2+

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Sønderby, Pernille; Bang, Maria Blanner

    2017-01-01

    fibrils has been debated for some years. We have therefore investigated the influence and binding geometry of zinc in fibrillated insulin using extended X-ray absorption fine-structure and X-ray absorption near-edge structure spectroscopy. The results were validated with fibre diffraction, Transmission...... Electron Microscopy and Thioflavin T fluorescence measurements. It is well-known that Zn2+ ions coordinate and stabilize the hexameric forms of insulin. However, this study is the first to show that zinc indeed binds to the insulin fibrils. Furthermore, zinc influences the kinetics and the morphology...... of the fibrils. It also shows that zinc coordinates to histidine residues in an environment, which is similar to the coordination seen in the insulin R6 hexamers, where three histidine residues and a chloride ion is coordinating the zinc....

  17. Ultrafast Hydrogen-Bonding Dynamics in Amyloid Fibrils.

    Science.gov (United States)

    Pazos, Ileana M; Ma, Jianqiang; Mukherjee, Debopreeti; Gai, Feng

    2018-06-08

    While there are many studies on the subject of hydrogen bonding dynamics in biological systems, few, if any, have investigated this fundamental process in amyloid fibrils. Herein, we seek to add insight into this topic by assessing the dynamics of a hydrogen bond buried in the dry interface of amyloid fibrils. To prepare a suitable model peptide system for this purpose, we introduce two mutations into the amyloid-forming Aβ(16-22) peptide. The first one is a lysine analog at position 19, which is used to help form structurally homogeneous fibrils, and the second one is an aspartic acid derivative (DM) at position 17, which is intended (1) to be used as a site-specific infrared probe and (2) to serve as a hydrogen-bond acceptor to lysine so that an inter-β-sheet hydrogen bond can be formed in the fibrils. Using both infrared spectroscopy and atomic force microscopy, we show that (1) this mutant peptide indeed forms well defined fibrils, (2) when bulk solvent is removed, there is no detectable water present in the fibrils, (3) infrared results obtained with the DM probe are consistent with a protofibril structure that is composed of two antiparallel β-sheets stacked in a parallel fashion, leading to formation of the expected hydrogen bond. Using two-dimensional infrared spectroscopy, we further show that the dynamics of this hydrogen bond occur on a timescale of ~2.3 ps, which is attributed to the rapid rotation of the -NH3+ group of lysine around its Cε-Nζ bond. Taken together, these results suggest that (1) DM is a useful infrared marker in facilitating structure determination of amyloid fibrils and (2) even in the tightly packed core of amyloid fibrils certain amino acid sidechains can undergo ultrafast motions, hence contributing to the thermodynamic stability of the system.

  18. Stroke and bleeding in atrial fibrillation with chronic kidney disease

    DEFF Research Database (Denmark)

    Olesen, Jonas Bjerring; Lip, Gregory Y.H.; Kamper, Anne-Lise

    2012-01-01

    Both atrial fibrillation and chronic kidney disease increase the risk of stroke and systemic thromboembolism. However, these risks, and the effects of antithrombotic treatment, have not been thoroughly investigated in patients with both conditions.......Both atrial fibrillation and chronic kidney disease increase the risk of stroke and systemic thromboembolism. However, these risks, and the effects of antithrombotic treatment, have not been thoroughly investigated in patients with both conditions....

  19. Nanomechanical mapping of hydrated rat tail tendon collagen I fibrils.

    Science.gov (United States)

    Baldwin, Samuel J; Quigley, Andrew S; Clegg, Charlotte; Kreplak, Laurent

    2014-10-21

    Collagen fibrils play an important role in the human body, providing tensile strength to connective tissues. These fibrils are characterized by a banding pattern with a D-period of 67 nm. The proposed origin of the D-period is the internal staggering of tropocollagen molecules within the fibril, leading to gap and overlap regions and a corresponding periodic density fluctuation. Using an atomic force microscope high-resolution modulus maps of collagen fibril segments, up to 80 μm in length, were acquired at indentation speeds around 10(5) nm/s. The maps revealed a periodic modulation corresponding to the D-period as well as previously undocumented micrometer scale fluctuations. Further analysis revealed a 4/5, gap/overlap, ratio in the measured modulus providing further support for the quarter-staggered model of collagen fibril axial structure. The modulus values obtained at indentation speeds around 10(5) nm/s are significantly larger than those previously reported. Probing the effect of indentation speed over four decades reveals two distinct logarithmic regimes of the measured modulus and point to the existence of a characteristic molecular relaxation time around 0.1 ms. Furthermore, collagen fibrils exposed to temperatures between 50 and 62°C and cooled back to room temperature show a sharp decrease in modulus and a sharp increase in fibril diameter. This is also associated with a disappearance of the D-period and the appearance of twisted subfibrils with a pitch in the micrometer range. Based on all these data and a similar behavior observed for cross-linked polymer networks below the glass transition temperature, we propose that collagen I fibrils may be in a glassy state while hydrated.

  20. Fibrillization kinetics of insulin solution in an interfacial shearing flow

    Science.gov (United States)

    Balaraj, Vignesh; McBride, Samantha; Hirsa, Amir; Lopez, Juan

    2015-11-01

    Although the association of fibril plaques with neurodegenerative diseases like Alzheimer's and Parkinson's is well established, in-depth understanding of the roles played by various physical factors in seeding and growth of fibrils is far from well known. Of the numerous factors affecting this complex phenomenon, the effect of fluid flow and shear at interfaces is paramount as it is ubiquitous and the most varying factor in vivo. Many amyloidogenic proteins have been found to denature upon contact at hydrophobic interfaces due to the self-assembling nature of protein in its monomeric state. Here, fibrillization kinetics of insulin solution is studied in an interfacial shearing flow. The transient surface rheological response of the insulin solution to the flow and its effect on the bulk fibrillization process has been quantified. Minute differences in hydrophobic characteristics between two variants of insulin- Human recombinant and Bovine insulin are found to result in very different responses. Results presented will be in the form of fibrillization assays, images of fibril plaques formed, and changes in surface rheological properties of the insulin solution. The interfacial velocity field, measured from images (via Brewster Angle Microscopy), is compared with computations. Supported by NNX13AQ22G, National Aeronautics and Space Administration.

  1. Viologen-Phosphorus Dendrimers Inhibit α-Synuclein Fibrillation.

    Science.gov (United States)

    Milowska, Katarzyna; Grochowina, Justyna; Katir, Nadia; El Kadib, Abdelkrim; Majoral, Jean-Pierre; Bryszewska, Maria; Gabryelak, Teresa

    2013-03-04

    Inhibition of α-synuclein (ASN) fibril formation is a potential therapeutic strategy in Parkinson's disease and other synucleinopathies. The aim of this study was to examine the role of viologen-phosphorus dendrimers in the α-synuclein fibrillation process and to assess the structural changes in α-synuclein under the influence of dendrimers. ASN interactions with phosphonate and pegylated surface-reactive viologen-phosphorus dendrimers were examined by measuring the zeta potential, which allowed determining the number of dendrimer molecules that bind to the ASN molecule. The fibrillation kinetics and the structural changes were examined using ThT fluorescence and CD spectroscopy. Depending on the concentration of the used dendrimer and the nature of the reactive groups located on the surface, ASN fibrillation kinetics can be significantly reduced, and even, in the specific case of phosphonate dendrimers, the fibrillation can be totally inhibited at low concentrations. The presented results indicate that viologen-phosphorus dendrimers are able to inhibit ASN fibril formation and may be used as fibrillar regulating agents in neurodegenerative disorders.

  2. Stabilization and anomalous hydration of collagen fibril under heating.

    Directory of Open Access Journals (Sweden)

    Sasun G Gevorkian

    Full Text Available BACKGROUND: Type I collagen is the most common protein among higher vertebrates. It forms the basis of fibrous connective tissues (tendon, chord, skin, bones and ensures mechanical stability and strength of these tissues. It is known, however, that separate triple-helical collagen macromolecules are unstable at physiological temperatures. We want to understand the mechanism of collagen stability at the intermolecular level. To this end, we study the collagen fibril, an intermediate level in the collagen hierarchy between triple-helical macromolecule and tendon. METHODOLOGY/PRINCIPAL FINDING: When heating a native fibril sample, its Young's modulus decreases in temperature range 20-58°C due to partial denaturation of triple-helices, but it is approximately constant at 58-75°C, because of stabilization by inter-molecular interactions. The stabilization temperature range 58-75°C has two further important features: here the fibril absorbs water under heating and the internal friction displays a peak. We relate these experimental findings to restructuring of collagen triple-helices in fibril. A theoretical description of the experimental results is provided via a generalization of the standard Zimm-Bragg model for the helix-coil transition. It takes into account intermolecular interactions of collagen triple-helices in fibril and describes water adsorption via the Langmuir mechanism. CONCLUSION/SIGNIFICANCE: We uncovered an inter-molecular mechanism that stabilizes the fibril made of unstable collagen macromolecules. This mechanism can be relevant for explaining stability of collagen.

  3. The architecture of amyloid-like peptide fibrils revealed by X-ray scattering, diffraction and electron microscopy

    DEFF Research Database (Denmark)

    Langkilde, Annette Eva; Morris, Kyle L; Serpell, Louise C

    2015-01-01

    Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril of the G......Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril...

  4. Recurrence of pulmonary vein conduction and atrial fibrillation after pulmonary vein isolation for atrial fibrillation

    DEFF Research Database (Denmark)

    Nilsson, Brian; Chen, Xu; Pehrson, Steen

    2006-01-01

    BACKGROUND: Both segmental ostial and circumferential extraostial pulmonary vein (PV) isolation have been proven effective in the treatment of atrial fibrillation (AF). However, the recurrence of AF and PV conduction after the 2 ablation strategies has never been compared in a randomized study...... isolation. Extraostial PV isolation was performed by encircling the paired left and right PVs, respectively, guided by an electroanatomic mapping system. RESULTS: A total of 84% of the patients had recurrent AF after the first PV isolation procedure, showing 72% with AF and 12% with organized left atrial...

  5. The inhalation toxicology of p-aramid fibrils.

    Science.gov (United States)

    Donaldson, Ken

    2009-01-01

    The pandemic of lung disease caused by asbestos has cast suspicion on any industrial fibrous material that can become airborne in respirable form in workplaces, such that the respirable fibres might be inhaled. Fibre toxicology arose as a sub-specialty of particle toxicology to address the specialised nature of fibre effects and has evolved substantially in the last 25 years. It has yielded valuable information on the dosimetry, structure-activity relationships, and mechanism involved in toxicological effects of a range of fibrous materials, including asbestos, other naturally occurring fibrous materials, and synthetic vitreous fibres. A robust structure/activity paradigm has emerged from this research that highlights fibre length, thinness, and biopersistence as major factors in determining the pathogenicity of a fibre. p-Aramid is a manufactured fibre composed of synthetic polyamide (poly paraphenylene terephthalamide) manufactured on a commercial scale since 1970 by polymerisation and spinning steps. It is used as an advanced composite and in fabrics, body armour, friction materials, etc. Respirable fibrils of p-aramid can be released from the fibres during working and can become airborne. A considerable body of research has been carried out into the hazard posed by inhaled p-aramid fibrils, and this review considers this body of literature and summarises the state-of-the-science in the toxicology of p-aramid fibrils in the light of the existing overarching fibre toxicology paradigm. The peer-reviewed studies demonstrate that p-aramid fibrils can be long and thin but that the fibrils are not biopersistent. Residence in the milieu of the lungs leads to fibre shortening, allowing efficient and complete phagocytosis and effective clearance. Subsequently the p-aramid hazard is low, and this is confirmed in animal studies. The mechanism of shortening of p-aramid fibrils is not well-understood, but may involve the action of macrophages on the fibrils following

  6. Wool fibril sponges with perspective biomedical applications

    International Nuclear Information System (INIS)

    Patrucco, A.; Cristofaro, F.; Simionati, M.; Zoccola, M.; Bruni, G.; Fassina, L.; Visai, L.; Magenes, G.

    2016-01-01

    Sheep's wool was used as a natural source to prepare keratin microfibril sponges for scaffolding, by disruption of the histological structure of the fibres through mild alkali treatment, followed by ultrasonication, casting and salt-leaching. The wool sponges showed highly interconnected porosity (93%) and contain intrinsic sites of cellular recognition that mimic the extracellular matrix (ECM). They displayed good thermal and water stability due to the conversion of disulphide cystine bonds into shorter monosulphide lanthionine intermolecular bonds, but significantly swelled in water, because of the high hydrophilicity and porosity, with a volume increasing up to 38%. Nevertheless, sponges were stable in water without structural changes, with a neutral pH in aqueous media, and showed excellent resilience to repeated compression stresses. According to in vitro biocompatibility assays, wool fibril sponges showed a good cell adhesion and proliferation as proved by MTT, FDA assays and SEM observations. The unique structure of the cortical cell network made by wool keratin proteins with controlled-size macro-porosity suitable for cell guesting, and nutrient feeding, provides an excellent scaffold for future tissue engineering applications. - Highlights: • Scaffolds were prepared from wool exploiting the fibres' histology structure. • The scaffold showed high interconnected micro- and macro-porosity. • The microscopic structure is very similar to the extracellular bone matrix. • Scaffolds reversibly swell in water with high resilience to repeated compression. • Composites were cytocompatible and supported the growth of SAOS-2 cell line.

  7. Red Wine, Resveratrol and Atrial Fibrillation

    Science.gov (United States)

    Garavaglia, Juliano; Marcadenti, Aline

    2017-01-01

    Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with increased risk for cardiovascular disease and overall mortality. Excessive alcohol intake is a well-known risk factor for AF, but this correlation is less clear with light and moderate drinking. Besides, low doses of red wine may acutely prolong repolarization and slow cardiac conduction. Resveratrol, a bioactive polyphenol found in grapes and red wine, has been linked to antiarrhythmic properties and may act as an inhibitor of both intracellular calcium release and pathological signaling cascades in AF, eliminating calcium overload and preserving the cardiomyocyte contractile function. However, there are still no clinical trials at all that prove that resveratrol supplementation leads to improved outcomes. Besides, no observational study supports a beneficial effect of light or moderate alcohol intake and a lower risk of AF. The purpose of this review is to briefly describe possible beneficial effects of red wine and resveratrol in AF, and also present studies conducted in humans regarding chronic red wine consumption, resveratrol, and AF. PMID:29084143

  8. Red Wine, Resveratrol and Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Laura Siga Stephan

    2017-10-01

    Full Text Available Atrial fibrillation (AF is a common cardiac arrhythmia that is associated with increased risk for cardiovascular disease and overall mortality. Excessive alcohol intake is a well-known risk factor for AF, but this correlation is less clear with light and moderate drinking. Besides, low doses of red wine may acutely prolong repolarization and slow cardiac conduction. Resveratrol, a bioactive polyphenol found in grapes and red wine, has been linked to antiarrhythmic properties and may act as an inhibitor of both intracellular calcium release and pathological signaling cascades in AF, eliminating calcium overload and preserving the cardiomyocyte contractile function. However, there are still no clinical trials at all that prove that resveratrol supplementation leads to improved outcomes. Besides, no observational study supports a beneficial effect of light or moderate alcohol intake and a lower risk of AF. The purpose of this review is to briefly describe possible beneficial effects of red wine and resveratrol in AF, and also present studies conducted in humans regarding chronic red wine consumption, resveratrol, and AF.

  9. Red Wine, Resveratrol and Atrial Fibrillation.

    Science.gov (United States)

    Stephan, Laura Siga; Almeida, Eduardo Dytz; Markoski, Melissa Medeiros; Garavaglia, Juliano; Marcadenti, Aline

    2017-10-30

    Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with increased risk for cardiovascular disease and overall mortality. Excessive alcohol intake is a well-known risk factor for AF, but this correlation is less clear with light and moderate drinking. Besides, low doses of red wine may acutely prolong repolarization and slow cardiac conduction. Resveratrol, a bioactive polyphenol found in grapes and red wine, has been linked to antiarrhythmic properties and may act as an inhibitor of both intracellular calcium release and pathological signaling cascades in AF, eliminating calcium overload and preserving the cardiomyocyte contractile function. However, there are still no clinical trials at all that prove that resveratrol supplementation leads to improved outcomes. Besides, no observational study supports a beneficial effect of light or moderate alcohol intake and a lower risk of AF. The purpose of this review is to briefly describe possible beneficial effects of red wine and resveratrol in AF, and also present studies conducted in humans regarding chronic red wine consumption, resveratrol, and AF.

  10. Imaging in percutaneous ablation for atrial fibrillation

    Energy Technology Data Exchange (ETDEWEB)

    Maksimovic, Ruzica [Erasmus Medical Center, Department of Radiology, GD Rotterdam (Netherlands); Institute for Cardiovascular Diseases of the University Medical Center, Belgrade (Czechoslovakia); Dill, Thorsten [Kerckhoff-Heart Center, Department of Cardiology, Bad Nauheim (Germany); Ristic, Arsen D.; Seferovic, Petar M. [Institute for Cardiovascular Diseases of the University Medical Center, Belgrade (Czechoslovakia)

    2006-11-15

    Percutaneous ablation for electrical disconnection of the arrhythmogenic foci using various forms of energy has become a well-established technique for treating atrial fibrillation (AF). Success rate in preventing recurrence of AF episodes is high although associated with a significant incidence of pulmonary vein (PV) stenosis and other rare complications. Clinical workup of AF patients includes imaging before and after ablative treatment using different noninvasive and invasive techniques such as conventional angiography, transoesophageal and intracardiac echocardiography, computed tomography (CT) and magnetic resonance imaging (MRI), which offer different information with variable diagnostic accuracy. Evaluation before percutaneous ablation involves assessment of PVs (PV pattern, branching pattern, orientation and ostial size) to facilitate position and size of catheters and reduce procedure time as well as examining the left atrium (presence of thrombi, dimensions and volumes). Imaging after the percutaneous ablation is important for assessment of overall success of the procedure and revealing potential complications. Therefore, imaging methods enable depiction of PVs and the anatomy of surrounding structures essential for preprocedural management and early detection of PV stenosis and other ablation-related procedures, as well as long-term follow-up of these patients. (orig.)

  11. Atrial fibrillation: effects beyond the atrium?

    Science.gov (United States)

    Wijesurendra, Rohan S; Casadei, Barbara

    2015-03-01

    Atrial fibrillation (AF) is the most common sustained clinical arrhythmia and is associated with significant morbidity, mostly secondary to heart failure and stroke, and an estimated two-fold increase in premature death. Efforts to increase our understanding of AF and its complications have focused on unravelling the mechanisms of electrical and structural remodelling of the atrial myocardium. Yet, it is increasingly recognized that AF is more than an atrial disease, being associated with systemic inflammation, endothelial dysfunction, and adverse effects on the structure and function of the left ventricular myocardium that may be prognostically important. Here, we review the molecular and in vivo evidence that underpins current knowledge regarding the effects of human or experimental AF on the ventricular myocardium. Potential mechanisms are explored including diffuse ventricular fibrosis, focal myocardial scarring, and impaired myocardial perfusion and perfusion reserve. The complex relationship between AF, systemic inflammation, as well as endothelial/microvascular dysfunction and the effects of AF on ventricular calcium handling and oxidative stress are also addressed. Finally, consideration is given to the clinical implications of these observations and concepts, with particular reference to rate vs. rhythm control. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

  12. Imaging in percutaneous ablation for atrial fibrillation

    International Nuclear Information System (INIS)

    Maksimovic, Ruzica; Dill, Thorsten; Ristic, Arsen D.; Seferovic, Petar M.

    2006-01-01

    Percutaneous ablation for electrical disconnection of the arrhythmogenic foci using various forms of energy has become a well-established technique for treating atrial fibrillation (AF). Success rate in preventing recurrence of AF episodes is high although associated with a significant incidence of pulmonary vein (PV) stenosis and other rare complications. Clinical workup of AF patients includes imaging before and after ablative treatment using different noninvasive and invasive techniques such as conventional angiography, transoesophageal and intracardiac echocardiography, computed tomography (CT) and magnetic resonance imaging (MRI), which offer different information with variable diagnostic accuracy. Evaluation before percutaneous ablation involves assessment of PVs (PV pattern, branching pattern, orientation and ostial size) to facilitate position and size of catheters and reduce procedure time as well as examining the left atrium (presence of thrombi, dimensions and volumes). Imaging after the percutaneous ablation is important for assessment of overall success of the procedure and revealing potential complications. Therefore, imaging methods enable depiction of PVs and the anatomy of surrounding structures essential for preprocedural management and early detection of PV stenosis and other ablation-related procedures, as well as long-term follow-up of these patients. (orig.)

  13. Wool fibril sponges with perspective biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Patrucco, A., E-mail: a.patrucco@bi.ismac.cnr.it [CNR-ISMAC, Italian National Research Council, Institute for Macromolecular Studies, Corso G. Pella 16, 13900, Biella (Italy); Cristofaro, F., E-mail: francesco.cristofaro01@universitadipavia.it [Department of Molecular Medicine, INSTM UdR of Pavia, University of Pavia, Viale Taramelli 3/B, 27100, Pavia (Italy); Centre for Health Technologies (CHT), University of Pavia, Via Ferrata 1, 27100, Pavia (Italy); Simionati, M., E-mail: m.simionati@bi.ismac.cnr.it [CNR-ISMAC, Italian National Research Council, Institute for Macromolecular Studies, Corso G. Pella 16, 13900, Biella (Italy); Zoccola, M., E-mail: m.zoccola@bi.ismac.cnr.it [CNR-ISMAC, Italian National Research Council, Institute for Macromolecular Studies, Corso G. Pella 16, 13900, Biella (Italy); Bruni, G., E-mail: giovanna.bruni@unipv.it [Department of Chemistry, — Physical-Chemistry Section, University of Pavia, Viale Taramelli 16, 27100, Pavia (Italy); Fassina, L., E-mail: lorenzo.fassina@unipv.it [Centre for Health Technologies (CHT), University of Pavia, Via Ferrata 1, 27100, Pavia (Italy); Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 1, 27100, Pavia (Italy); Visai, L., E-mail: livia.visai@unipv.it [Department of Molecular Medicine, INSTM UdR of Pavia, University of Pavia, Viale Taramelli 3/B, 27100, Pavia (Italy); Centre for Health Technologies (CHT), University of Pavia, Via Ferrata 1, 27100, Pavia (Italy); Department of Occupational Medicine, Toxicology and Environmental Risks, S. Maugeri Foundation, IRCCS, Via S. Boezio, 28, 27100, Pavia (Italy); Magenes, G., E-mail: giovanni.magenes@unipv.it [Centre for Health Technologies (CHT), University of Pavia, Via Ferrata 1, 27100, Pavia (Italy); Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 1, 27100, Pavia (Italy); and others

    2016-04-01

    Sheep's wool was used as a natural source to prepare keratin microfibril sponges for scaffolding, by disruption of the histological structure of the fibres through mild alkali treatment, followed by ultrasonication, casting and salt-leaching. The wool sponges showed highly interconnected porosity (93%) and contain intrinsic sites of cellular recognition that mimic the extracellular matrix (ECM). They displayed good thermal and water stability due to the conversion of disulphide cystine bonds into shorter monosulphide lanthionine intermolecular bonds, but significantly swelled in water, because of the high hydrophilicity and porosity, with a volume increasing up to 38%. Nevertheless, sponges were stable in water without structural changes, with a neutral pH in aqueous media, and showed excellent resilience to repeated compression stresses. According to in vitro biocompatibility assays, wool fibril sponges showed a good cell adhesion and proliferation as proved by MTT, FDA assays and SEM observations. The unique structure of the cortical cell network made by wool keratin proteins with controlled-size macro-porosity suitable for cell guesting, and nutrient feeding, provides an excellent scaffold for future tissue engineering applications. - Highlights: • Scaffolds were prepared from wool exploiting the fibres' histology structure. • The scaffold showed high interconnected micro- and macro-porosity. • The microscopic structure is very similar to the extracellular bone matrix. • Scaffolds reversibly swell in water with high resilience to repeated compression. • Composites were cytocompatible and supported the growth of SAOS-2 cell line.

  14. Ventricular fibrillation time constant for swine

    International Nuclear Information System (INIS)

    Wu, Jiun-Yan; Sun, Hongyu; Nimunkar, Amit J; Webster, John G; O'Rourke, Ann; Huebner, Shane; Will, James A

    2008-01-01

    The strength–duration curve for cardiac excitation can be modeled by a parallel resistor–capacitor circuit that has a time constant. Experiments on six pigs were performed by delivering current from the X26 Taser dart at a distance from the heart to cause ventricular fibrillation (VF). The X26 Taser is an electromuscular incapacitation device (EMD), which generates about 50 kV and delivers a pulse train of about 15–19 pulses s −1 with a pulse duration of about 150 µs and peak current about 2 A. Similarly a continuous 60 Hz alternating current of the amplitude required to cause VF was delivered from the same distance. The average current and duration of the current pulse were estimated in both sets of experiments. The strength–duration equation was solved to yield an average time constant of 2.87 ms ± 1.90 (SD). Results obtained may help in the development of safety standards for future electromuscular incapacitation devices (EMDs) without requiring additional animal tests

  15. The mechanisms of atrial fibrillation in hyperthyroidism

    Directory of Open Access Journals (Sweden)

    Bielecka-Dabrowa Agata

    2009-04-01

    Full Text Available Abstract Atrial fibrillation (AF is a complex condition with several possible contributing factors. The rapid and irregular heartbeat produced by AF increases the risk of blood clot formation inside the heart. These clots may eventually become dislodged, causing embolism, stroke and other disorders. AF occurs in up to 15% of patients with hyperthyroidism compared to 4% of people in the general population and is more common in men and in patients with triiodothyronine (T3 toxicosis. The incidence of AF increases with advancing age. Also, subclinical hyperthyroidism is a risk factor associated with a 3-fold increase in development of AF. Thyrotoxicosis exerts marked influences on electrical impulse generation (chronotropic effect and conduction (dromotropic effect. Several potential mechanisms could be invoked for the effect of thyroid hormones on AF risk, including elevation of left atrial pressure secondary to increased left ventricular mass and impaired ventricular relaxation, ischemia resulting from increased resting heart rate, and increased atrial eopic activity. Reentry has been postulated as one of the main mechanisms leading to AF. AF is more likely if effective refractory periods are short and conduction is slow. Hyperthyroidism is associated with shortening of action potential duration which may also contribute to AF.

  16. Atrial Fibrillation Predictors: Importance of the Electrocardiogram.

    Science.gov (United States)

    German, David M; Kabir, Muammar M; Dewland, Thomas A; Henrikson, Charles A; Tereshchenko, Larisa G

    2016-01-01

    Atrial fibrillation (AF) is the most common arrhythmia in adults and is associated with significant morbidity and mortality. Substantial interest has developed in the primary prevention of AF, and thus the identification of individuals at risk for developing AF. The electrocardiogram (ECG) provides a wealth of information, which is of value in predicting incident AF. The PR interval and P wave indices (including P wave duration, P wave terminal force, P wave axis, and other measures of P wave morphology) are discussed with regard to their ability to predict and characterize AF risk in the general population. The predictive value of the QT interval, ECG criteria for left ventricular hypertrophy, and findings of atrial and ventricular ectopy are also discussed. Efforts are underway to develop models that predict AF incidence in the general population; however, at present, little information from the ECG is included in these models. The ECG provides a great deal of information on AF risk and has the potential to contribute substantially to AF risk estimation, but more research is needed. © 2015 Wiley Periodicals, Inc.

  17. Michler’s Hydrol Blue: A Sensitive Probe for Amyloid Fibril Detection

    KAUST Repository

    Kitts, Catherine C.; Beke-Somfai, Tamás; Nordén, Bengt

    2011-01-01

    amyloid probe, can differentiate between insulin and lysozyme fibrils by a more red-shifted excitation spectrum for insulin fibrils. To support the experimental observations, time-dependent density functional theory (TDDFT) calculations were performed

  18. Risk of atrial fibrillation as a function of the electrocardiographic PR interval

    DEFF Research Database (Denmark)

    Nielsen, Jonas Bille; Pietersen, Adrian; Graff, Claus

    2013-01-01

    Prolongation of the PR interval has been associated with an increased risk of incident atrial fibrillation (AF).......Prolongation of the PR interval has been associated with an increased risk of incident atrial fibrillation (AF)....

  19. A randomized study of the effects of exercise training on patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Osbak, Philip Samuel; Mourier, Malene; Kjaer, Andreas

    2011-01-01

    Exercise training is beneficial in ischemic and congestive heart disease. However, the effect on atrial fibrillation (AF) is unknown.......Exercise training is beneficial in ischemic and congestive heart disease. However, the effect on atrial fibrillation (AF) is unknown....

  20. Determination of collagen fibril structure and orientation in connective tissues by X-ray diffraction

    Science.gov (United States)

    Wilkinson, S. J.; Hukins, D. W. L.

    1999-08-01

    Elastic scattering of X-rays can provide the following information on the fibrous protein collagen: its molecular structure, the axial arrangement of rod-like collagen molecules in a fibril, the lateral arrangement of molecules within a fibril, and the orientation of fibrils within a biological tissue. The first part of the paper reviews the principles involved in deducing this information. The second part describes a new computer program for measuring the equatorial intensity distribution, that provides information on the lateral arrangement of molecules within a fibril, and the angular distribution of the equatorial peaks that provides information on the orientation of fibrils. Orientation of fibrils within a tissue is quantified by the orientation distribution function, g( φ), which represents the probability of finding a fibril oriented between φ and φ+ δφ. The application of the program is illustrated by measurement of g( φ) for the collagen fibrils in demineralised cortical bone from cow tibia.

  1. Long-Term Exposure to Traffic-Related Air Pollution and Risk of Incident Atrial Fibrillation

    DEFF Research Database (Denmark)

    Monrad, Maria; Sajadieh, Ahmad; Christensen, Jeppe Schultz

    2017-01-01

    BACKGROUND: Atrial fibrillation is the most common sustained arrhythmia and associated with cardiovascular morbidity and mortality. The few studies conducted on short-term effects of air pollution on episodes of atrial fibrillation indicates a positive association, though not consistently...

  2. Newer Anticoagulants for Non-Valvular Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Joseph M. Harburger

    2012-05-01

    Full Text Available Non-valvular atrial fibrillation is a recognized risk factor for stroke and systemic embolism. It has been clearly established that warfarin reduces the risk of stroke and systemic embolism in persons with atrial fibrillation and additional risk factors for stroke. The use of warfarin, however, requires frequent monitoring, and there is great variability in patient response to warfarin. Warfarin interacts with several medications and foods. In addition, warfarin use portends a significant risk of bleeding. For these reasons, warfarin is frequently not prescribed to persons for whom the drug would provide a clear benefit. Over the past decade, attempts have been made to develop drugs that are at least as safe and effective as warfarin for the treatment of atrial fibrillation that do not require monitoring nor have as many interactions. Initial studies of compounds in this regard ultimately failed due to safety concerns, but over the past two years two novel agents have been approved by the United States Food and Drug Association for anticoagulation in non-valvular atrial fibrillation, another drug is under review, and additional compounds are being studied. This article will review the use of warfarin and these new agents in the treatment of non-valvular atrial fibrillation.

  3. Heart failure and atrial fibrillation: current concepts and controversies.

    Science.gov (United States)

    Van den Berg, M. P.; Tuinenburg, A. E.; Crijns, H. J.; Van Gelder, I. C.; Gosselink, A. T.; Lie, K. I.

    1997-01-01

    Heart failure and atrial fibrillation are very common, particularly in the elderly. Owing to common risk factors both disorders are often present in the same patient. In addition, there is increasing evidence of a complex, reciprocal relation between heart failure and atrial fibrillation. Thus heart failure may cause atrial fibrillation, with electromechanical feedback and neurohumoral activation playing an important mediating role. In addition, atrial fibrillation may promote heart failure; in particular, when there is an uncontrolled ventricular rate, tachycardiomyopathy may develop and thereby heart failure. Eventually, a vicious circle between heart failure and atrial fibrillation may form, in which neurohumoral activation and subtle derangement of rate control are involved. Treatment should aim at unloading of the heart, adequate control of ventricular rate, and correction of neurohumoral activation. Angiotensin converting enzyme inhibitors may help to achieve these goals. Treatment should also include an attempt to restore sinus rhythm through electrical cardioversion, though appropriate timing of cardioversion is difficult. His bundle ablation may be used to achieve adequate rate control in drug refractory cases. PMID:9155607

  4. Elasticity in Physically Cross-Linked Amyloid Fibril Networks

    Science.gov (United States)

    Cao, Yiping; Bolisetty, Sreenath; Adamcik, Jozef; Mezzenga, Raffaele

    2018-04-01

    We provide a constitutive model of semiflexible and rigid amyloid fibril networks by combining the affine thermal model of network elasticity with the Derjaguin-Landau-Vervey-Overbeek (DLVO) theory of electrostatically charged colloids. When compared to rheological experiments on β -lactoglobulin and lysozyme amyloid networks, this approach provides the correct scaling of elasticity versus both concentration (G ˜c2.2 and G ˜c2.5 for semiflexible and rigid fibrils, respectively) and ionic strength (G ˜I4.4 and G ˜I3.8 for β -lactoglobulin and lysozyme, independent from fibril flexibility). The pivotal role played by the screening salt is to reduce the electrostatic barrier among amyloid fibrils, converting labile physical entanglements into long-lived cross-links. This gives a power-law behavior of G with I having exponents significantly larger than in other semiflexible polymer networks (e.g., actin) and carrying DLVO traits specific to the individual amyloid fibrils.

  5. Observation of the efficacy of radiofrequency catheter ablation on patients with different forms of atrial fibrillation.

    Science.gov (United States)

    Zhao, R-C; Han, W; Han, J; Yu, J; Guo, J; Fu, J-L; Li, Z; Zhao, R-Z

    2016-10-01

    To study the efficacy and safety of radiofrequency catheter ablation (RFCA) in patients with different forms of atrial fibrillation. By retrospective analysis, we summarize 720 cases, where patients diagnosed with atrial fibrillation in our hospital were treated with RFCA from February 2010 to October 2014. Among the cases, 425 were diagnosed with paroxysmal atrial fibrillation and 295 with non-paroxysmal atrial fibrillation (including persistent atrial fibrillation and permanent atrial fibrillation). All patients were followed up until June 2015 to compare and analyze the differences in operation success rates, complications and recurrence rates. 395 cases (92.9%) of paroxysmal atrial fibrillation and 253 cases (85.8%) with non-paroxysmal atrial fibrillation were subject to surgery and followed up. The age of onset, disease course, underlying diseases, left atrial diameter and combined anti-arrhythmics of patients with paroxysmal atrial fibrillation were lower than those of patients with non-paroxysmal atrial fibrillation, and the differences were statistically significant (p success rate of the first ablation was higher than that of non-paroxysmal atrial fibrillation. Procedure time, procedure method, complications and recurrence rate of patients with paroxysmal atrial fibrillation were lower than those of non-paroxysmal atrial fibrillation group, and the differences were statistically significant (p failure caused by atrial fibrillation in the two groups, the difference was not statistically significant (Apoplexy: p = 0.186; Heart failure: p = 0.170). The individual ablation success rate was higher for paroxysmal atrial fibrillation, and long-term follow-up showed that the occurrence of apoplexy and heart failure was not different from the non-paroxysmal atrial fibrillation group.

  6. 77 FR 11121 - Scientific Information Request on Treatment of Atrial Fibrillation

    Science.gov (United States)

    2012-02-24

    ... Information Request on Treatment of Atrial Fibrillation AGENCY: Agency for Healthcare Research and Quality... Review of the Treatment of Atrial Fibrillation, which is currently being conducted by the Evidence-based... the treatment of atrial fibrillation. The EHC Program is dedicated to identifying as many studies as...

  7. 78 FR 11207 - Clinical Study Designs for Surgical Ablation Devices for Treatment of Atrial Fibrillation...

    Science.gov (United States)

    2013-02-15

    ...] Clinical Study Designs for Surgical Ablation Devices for Treatment of Atrial Fibrillation; Guidance for... devices intended for the treatment of atrial fibrillation. DATES: Submit either electronic or written... Study Designs for Surgical Ablation Devices for Treatment of Atrial Fibrillation'' to the Division of...

  8. SAFETY OF AMIODARONE USAGE IN PATIENTS WITH WOLFF-PARKINSON-WHITE SYNDROME AND ATRIAL FIBRILLATION

    Directory of Open Access Journals (Sweden)

    D. A. Kuzhel

    2010-01-01

    Full Text Available Amiodarone is one of the basic antiarrhytmic drugs for atrial fibrillation treatment. However application of amiodarone in patients with atrial fibrillation and Wolff-Parkinson-White syndrome can induce ventricular fibrillation. Amiodarone usage in these patients should be accompanied by readiness for performance of resuscitation. This is confirmed by clinical case presentation.

  9. Meta-analysis identifies six new susceptibility loci for atrial fibrillation

    NARCIS (Netherlands)

    Ellinor, Patrick T; Lunetta, Kathryn L; Albert, Christine M; Glazer, Nicole L; Ritchie, Marylyn D; Smith, Albert V; Arking, Dan E; Müller-Nurasyid, Martina; Krijthe, Bouwe P; Lubitz, Steven A; Bis, Joshua C; Chung, Mina K; Dörr, Marcus; Ozaki, Kouichi; Roberts, Jason D; Smith, J Gustav; Pfeufer, Arne; Sinner, Moritz F; Lohman, Kurt; Ding, Jingzhong; Smith, Nicholas L; Smith, Jonathan D; Rienstra, Michiel; Rice, Kenneth M; Van Wagoner, David R; Magnani, Jared W; Wakili, Reza; Clauss, Sebastian; Rotter, Jerome I; Steinbeck, Gerhard; Launer, Lenore J; Davies, Robert W; Borkovich, Matthew; Harris, Tamara B; Lin, Honghuang; Völker, Uwe; Völzke, Henry; Milan, David J; Hofman, Albert; Boerwinkle, Eric; Chen, Lin Y; Soliman, Elsayed Z; Voight, Benjamin F; Li, Guo; Chakravarti, Aravinda; Kubo, Michiaki; Tedrow, Usha B; Rose, Lynda M; Ridker, Paul M; Conen, David; Tsunoda, Tatsuhiko; Furukawa, Tetsushi; Sotoodehnia, Nona; Xu, Siyan; Kamatani, Naoyuki; Levy, Daniel; Nakamura, Yusuke; Parvez, Babar; Mahida, Saagar; Furie, Karen L; Rosand, Jonathan; Muhammad, Raafia; Psaty, Bruce M; Meitinger, Thomas; Perz, Siegfried; Wichmann, H-Erich; Witteman, Jacqueline C M; Kao, W H Linda; Kathiresan, Sekar; Roden, Dan M; Uitterlinden, Andre G; Rivadeneira, Fernando; McKnight, Barbara; Sjögren, Marketa; Newman, Anne B; Liu, Yongmei; Gollob, Michael H; Melander, Olle; Tanaka, Toshihiro; Stricker, Bruno H Ch; Felix, Stephan B; Alonso, Alvaro; Darbar, Dawood; Barnard, John; Chasman, Daniel I; Heckbert, Susan R; Benjamin, Emelia J; Gudnason, Vilmundur; Kääb, Stefan

    Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death. We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation

  10. Optimizing cellulose fibrillation for the production of cellulose nanofibrils by a disk grinder

    Science.gov (United States)

    Chuanshuang Hu; Yu Zhao; Kecheng Li; J.Y. Zhu; Roland Gleisner

    2015-01-01

    The fibrillation of a bleached kraft eucalyptus pulp was investigated by means of a laboratory-scale disk grinder for the production of cellulose nanofibrils (CNF), while the parameters disk rotating speed, solid loading, and fibrillation duration were varied. The cumulative energy consumption was monitored during fibrillation. The degree of polymerization (DP) and...

  11. Disease management: atrial fibrillation and home monitoring.

    Science.gov (United States)

    Ricci, Renato Pietro

    2013-06-01

    Device-detected atrial fibrillation (AF) episodes predict poor clinical outcome regardless of symptoms. Potential benefits of remote monitoring are early arrhythmia detection and patient continuous monitoring. Several studies of device remote monitoring consistently demonstrated that AF represents the most common clinical alert and that detailed information on arrhythmia onset, duration, and burden as well as on the ventricular rate may be early available for clinical evaluation. Reaction time to AF alerts was very short in all series involving either pacemakers or defibrillators and action ability of AF alerts was very high. In the Home Guide Registry, in which 1650 patients were enrolled, AF was detected in 16.3% of patients and represented 36% of all cardiovascular events during the follow-up. Timely anticoagulation introduction in asymptomatic patients may impact on the stroke rate. According to the results of repeated Monte Carlo simulations based on a real population of 166 patients, daily monitoring may reduce the 2-year stroke risk by 9-18% with an absolute reduction of 0.2-0.6%, compared with conventional inter-visit intervals of 6-12 months. In the COMPAS trial, the incidence of hospitalizations for atrial arrhythmias and related stroke was significantly higher in the control group than in the remote monitoring group. Major questions will be addressed by the ongoing IMPACT trial in which a remote monitoring guided anticoagulation strategy based on AF detection will be compared with a physician-directed standard strategy. In patients with heart failure, AF early detection combined with other indexes may help prevent hospitalizations.

  12. Calcium signalling silencing in atrial fibrillation.

    Science.gov (United States)

    Greiser, Maura

    2017-06-15

    Subcellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca 2+ signalling instability and Ca 2+ -based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca 2+ ] i signal to the myocyte centre both in patients with AF and in a rabbit model. This adaptive mechanism leads to a substantial reduction in the expression levels of calcium release channels (ryanodine receptors, RyR2) in the sarcoplasmic reticulum, and the frequency of Ca 2+ sparks and arrhythmogenic Ca 2+ waves remains low. Less Ca 2+ release per [Ca 2+ ] i transient, increased fast Ca 2+ buffering strength, shortened action potentials and reduced L-type Ca 2+ current contribute to a substantial reduction of intracellular [Na + ]. These features of Ca 2+ signalling silencing are distinct and in contrast to the changes attributed to Ca 2+ -based arrhythmogenicity. Some features of Ca 2+ signalling silencing prevail in human AF suggesting that the Ca 2+ signalling 'phenotype' in AF is a sum of Ca 2+ stabilizing (Ca 2+ signalling silencing) and Ca 2+ destabilizing (arrhythmogenic unstable Ca 2+ signalling) factors. Calcium signalling silencing is a part of the mechanisms that contribute to the natural progression of AF and may limit the role of Ca 2+ -based arrhythmogenicity after the onset of AF. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

  13. Clinical application of low energy intracardiac cardioversion of atrial fibrillation

    International Nuclear Information System (INIS)

    Wu Liqun; Gu Gang; Su Kan; Su Renying; Shen Yongchu; Shen Weifeng

    2002-01-01

    Objective: To evaluate the efficacy and safety of low energy intracardiac cardioversion in persistent atria fibrillation. Methods: Low energy intracardiac cardioversion was performed by delivering R wave-synchronized biphasic shocks in 7 patients (4 men, 3 women) with persistent atrial fibrillation. Prior to the procedure, all patients underwent transesophageal echocardiographic examinations to rule out the presence of intracardiac thrombus and received subcutaneous injection of low molecular weight heparin for 3-5 days. Two custom-made 6 Fr catheters (Rhythm Technologies of Getz, USA) were used for de-fibrillation shock delivery. One catheter was positioned in the lower right atrium so that the majority of the catheter electrodes had firm contact with the right atrial free wall. The second catheter was placed randomly either in coronary sinus through right internal jugular vein or in the left pulmonary artery through femoral vein. In addition, a standard diagnostic 6-F quadrupolar catheter was placed at the right ventricular apex for ventricular synchronization and postshock ventricular pacing. Shocks were delivered by Implant Support Device (Model 4510, Teleceronics). After conversion, all patients were treated with intravenous amiodarone in the first 24 hours followed by oral administration. Results: In all 7 patients cardioversion of atrial fibrillation to sinus rhythm was successfully obtained. A mean of 2 ± 1 shocks per patient has been delivered with a total amount of 13 shocks. The average delivered energy was 7.8 ± 2.2 Joules. No complication occurred. At a mean follow-up of 18 ± 9 months, 4 of the 7 patients treated successfully showed sinus rhythm there after. Atrial fibrillation recurred in 3 patients at the second, fifth day and eighth month after cardioversion. Conclusions: Low energy intracardiac cardioversion is effective and safe, and can be easily performed in patients without general anesthesia. It offers a new option for restoring sinus

  14. Failure of antiarrhythmic drugs to prevent experimental reperfusion ventricular fibrillation.

    Science.gov (United States)

    Naito, M; Michelson, E L; Kmetzo, J J; Kaplinsky, E; Dreifus, L S

    1981-01-01

    Ninety-nine adult mongrel dogs underwent acute ligation of the proximal left anterior descending coronary artery. Thirty minutes later, the occlusion was released to evaluate the effectiveness of five antiarrhythmic protocols in eliminating reperfusion ventricular fibrillation. The five protocols included: protocol 1 --i.v. lidocaine, preligation and prerelease (n = 19); protocol 2 -- i.v. lidocaine, prereperfusion only (n = 22); protocol 3 -- chronic, oral, daily amiodarone for 2 weeks preligation (n = 19); protocol 4 -- i.v. procainamide, preligation and prereperfusion (n = 21); and protocol 5 -- i.v. verapamil, prereperfusion (n = 18). Each regimen was evaluated with respect to the incidence of reperfusion ventricular fibrillation in dogs that survived to reperfusion, and the results were compared to 77 control dogs that underwent identical coronary artery occlusion and release procedures without drug therapy. The incidence of reperfusion ventricular fibrillation was as follows: protocol 1 -- seven of 15 dogs (47%); protocol 2 -- six of 18 (33%); protocol 3 -- 11 of 16 dogs (69%); protocol 4 -- eight of 17 dogs (47%); and protocol 5 -- 10 of 17 dogs (59%), compared with 36 of 60 (60%) in control dogs. Using chi-square analysis, protocol 2 was beneficial (p antecedent coronary artery ligation periods, and predictive risk indexes for the occurrence of reperfusion ventricular fibrillation were developed. the Mantel-Haenszel method of statistical analysis revealed that none of these protocols resulted in a statistically significant reduction in the incidence of reperfusion ventricular fibrillation. Thus, use of these predictive indexes plus appropriate statistical methods has revealed, unexpectedly, limitations in the efficacy of a spectrum of antiarrhythmic agents in preventing reperfusion ventricular fibrillation.

  15. Exposure-Based Therapy for Symptom Preoccupation in Atrial Fibrillation

    DEFF Research Database (Denmark)

    Särnholm, Josefin; Skúladóttir, Helga; Rück, Christian

    2017-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia. Patients often experience a range of symptoms resulting in a markedly reduced quality of life, and commonly show symptom preoccupation in terms of avoidance and control behaviors. Cognitive behavior therapy (CBT) has been shown...... with symptomatic paroxysmal (intermittent) atrial fibrillation who were assessed pre- and posttreatment and at 6-month follow-up. The CBT lasted 10 weeks and included exposure to physical sensations similar to AF symptoms, exposure to avoided situations or activities, and behavioral activation. We observed large...

  16. SDS-Induced Fibrillation of α-Synuclein

    DEFF Research Database (Denmark)

    Giehm, L.; Oliveira, Cristiano Luis Pinto De; Pedersen, J.S.

    2010-01-01

    . In this fibrillogenic complex, 4 αSN molecules initially associate with 40-50 SDS molecules to form a shared micelle that gradually grows in size. The complex initially exhibits a mixture of random coil and α-helix, but incubation results in a structural conversion into β-sheet structure and concomitant formation......-stabilized micelles. Thus, fibrillation in this case occurs by a process of continuous accretion rather than by the rate-limiting accumulation of a distinct nucleus. The morphology of the SDS-induced fibrils does not exhibit the classical rod-like structures formed by αSN when aggregated by agitation in the absence...

  17. Gender Differences in Antithrombotic Treatment for Newly Diagnosed Atrial Fibrillation

    DEFF Research Database (Denmark)

    Mazurek, Michał; Huisman, Menno V; Rothman, Kenneth J

    2018-01-01

    was -0.5% (95% CI, -1.8%, 0.8%). VKAs were prescribed to 32.8% and 31.9% (NOACs 46.8% and 48.3%) of women and men, respectively. No confounder for the association between gender and anticoagulant prescription was identified. Between-gender differences in anticoagulant use (lower use in women compared......AIMS: Data on gender differences in oral anticoagulation for stroke prevention in patients with atrial fibrillation are conflicting, largely limited to regional reports and Vitamin K antagonist (VKA) use. We aimed to analyze gender-specific anticoagulant prescription patterns early following...... atrial fibrillation (difference in prevalence of anticoagulant use...

  18. New fluorescent probes for detection and characterization of amyloid fibrils

    Science.gov (United States)

    Gorbenko, Galyna; Trusova, Valeriya; Kirilova, Elena; Kirilov, Georgiy; Kalnina, Inta; Vasilev, Aleksey; Kaloyanova, Stefka; Deligeorgiev, Todor

    2010-08-01

    The applicability of the novel fluorescent probes, aminoderivative of benzanthrone ABM, squaraine dye SQ-1 and polymethine dye V2 to identification and structural analysis of amyloid fibrils has been evaluated using the lysozyme model system in which fibrillar aggregates have been formed in concentrated ethanol solution. The association constant, binding stoichiometry and molar fluorescence of the bound dye have been determined. ABM was found to surpass classical amyloid marker ThT in the sensitivity to the presence of fibrillar aggregates. Resonance energy transfer measurements involving ABM-SQ-1 and SQ-1-V2 donor-acceptor pairs yielded the limits for fractal-like dimension of lysozyme fibrils.

  19. Nearly reversible conformational change of amyloid fibrils as revealed by pH-jump experiments.

    Science.gov (United States)

    Yamaguchi, Kei-ichi; Kamatari, Yuji O; Fukuoka, Mayuko; Miyaji, Reiji; Kuwata, Kazuo

    2013-10-01

    pH-jump induced conformational transitions between substates of preformed amyloid fibrils made by a fragmented peptide of helix 2 (H2 peptide) of MoPrP were detected, and their kinetics were analyzed using a novel pH-jump apparatus specially designed for observing amyloids. Previously, we reported that H2 peptide formed ordered fibrils with a minimum at 207 nm on CD spectra at pH 2.9 (named pH 2.9 fibrils), but formed aggregate-like fibrils with a minimum at 220 nm at pH 7.5 (named pH 7.5 fibrils). When pH-jump from 2.9 to 7.5 was performed, the CD spectrum changed instantly, but the finally observed ellipticities were clearly distinct from those of pH 7.5 fibrils. Thus, the finally observed state is termed 'pH 7.5-like fibrils'. However, pH 7.5-like fibrils reverted to the conformation very similar to that of the pH 2.9 fibrils when the pH of the solution was restored to 2.9. Then, we examined the kinetics of the nearly reversible conformational changes between pH 2.9 fibrils and pH 7.5-like fibrils using ANS fluorescence stopped-flow, and we observed relatively fast phases (0.7-18 s(-1)). In contrast, the conversion between pH 7.5-like fibrils and pH 7.5 fibrils never occurred (<0.2 day(-1)). Thus, H2 fibrils can be switched readily between distinct conformations separated by a low energy barrier, while a large energy barrier clearly separated the different conformations. These conformational varieties of amyloid fibrils may explain the physical basis of the diversity in prion.

  20. Binding and Inhibitory Effect of the Dyes Amaranth and Tartrazine on Amyloid Fibrillation in Lysozyme.

    Science.gov (United States)

    Basu, Anirban; Suresh Kumar, Gopinatha

    2017-02-16

    Interaction of two food colorant dyes, amaranth and tartrazine, with lysozyme was studied employing multiple biophysical techniques. The dyes exhibited hypochromic changes in the presence of lysozyme. The intrinsic fluorescence of lysozyme was quenched by both dyes; amaranth was a more efficient quencher than tartrazine. The equilibrium constant of amaranth was higher than that of tartarzine. From FRET analysis, the binding distances for amaranth and tartrazine were calculated to be 4.51 and 3.93 nm, respectively. The binding was found to be dominated by non-polyelectrolytic forces. Both dyes induced alterations in the microenvironment surrounding the tryptophan and tyrosine residues of the protein, with the alterations being comparatively higher for the tryptophans than the tyrosines. The interaction caused significant loss in the helicity of lysozyme, the change being higher with amaranth. The binding of both dyes was exothermic. The binding of amaranth was enthalpy driven, while that of tartrazine was predominantly entropy driven. Amaranth delayed lysozyme fibrillation at 25 μM, while tartrazine had no effect even at 100 μM. Nevertheless, both dyes had a significant inhibitory effect on fibrillogenesis. The present study explores the potential antiamyloidogenic property of these azo dyes used as food colorants.

  1. Circadian variation in dominant atrial fibrillation frequency in persistent atrial fibrillation

    International Nuclear Information System (INIS)

    Sandberg, Frida; Stridh, Martin; Sörnmo, Leif; Bollmann, Andreas; Husser, Daniela

    2010-01-01

    Circadian variation in atrial fibrillation (AF) frequency is explored in this paper by employing recent advances in signal processing. Once the AF frequency has been estimated and tracked by a hidden Markov model approach, the resulting trend is analyzed for the purpose of detecting and characterizing the presence of circadian variation. With cosinor analysis, the results show that the short-term variations in the AF frequency exceed the variation that may be attributed to circadian. Using the autocorrelation method, circadian variation was found in 13 of 18 ambulatory ECG recordings (Holter) acquired from patients with long-standing persistent AF. Using the ensemble correlation method, the highest AF frequency usually occurred during the afternoon, whereas the lowest usually occurred during late night. It is concluded that circadian variation is present in most patients with long-standing persistent AF though the short-term variation in the AF frequency is considerable and should be taken into account

  2. Analysis of brain natriuretic peptide in 30 patients with atrial fibrillation

    International Nuclear Information System (INIS)

    Jin Qiang; Lu Jianghui; Li Weipeng; Yuan Yuan; Sun Weili

    2009-01-01

    To investigate the relationship between atrial fibrillation and brain natriuretic peptide (BNP), plasma levels of BNP in 30 patients with atrial fibrillation and 30 health controls were assayed and compared. The results showed that plasma levels of BNP in patients with atrial fibrillation were significantly higher than those of health controls (P<0.05). When the patients with atrial fibrillation were restored sinus rhythm, the concentration of BNP decreased significantly (P<0.05). BNP was a sensitive marker of cardiac dysfunction, and BNP was positively correlated with atrial fibrillation. (authors)

  3. Ventricular fibrillation development following atrial fibrillation after the ingestion of sildenaphil in a patient with Wolff-Parkinson-White syndrome.

    Science.gov (United States)

    Inci, Sinan; Izgu, Ibrahim; Aktas, Halil; Dogan, Pinar; Dogan, Ali

    2015-08-01

    Complications in the accessory pathway in Wolff-Parkinson-White (WPW) syndrome could cause different clinical conditions by inducing different arrhythmias. Atrial fibrillation (AF) is one of these arrhythmias and is important as it causes life-threatening arrhythmias. It is known that some drugs, underlying cardiac diseases, and the number of accessory pathways, cause a predisposition to this condition. In the current report, we presented a patient with WPW who was admitted to the emergency department with AF, wide QRS and a rapid ventricular response that progressed to ventricular fibrillation.

  4. Light-Driven Alignment

    CERN Document Server

    Antonyuk, Boris P

    2009-01-01

    This book deals with influencing the properties of solids by light-driven electron transport. The theoretical basis of these effects, light-driven ordering and self-organisation, as well as optical motors are presented. With light as a tool, new ways to produce materials are opened.

  5. Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training

    DEFF Research Database (Denmark)

    Kongsgaard, Mads; Qvortrup, Klaus; Larsen, Jytte Overgaard

    2010-01-01

    BACKGROUND: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive. PURPOSE: To investigate fibril morphology and mechanical properties...... assessed symptoms/function and maximal tendon pain during activity. Tendon biopsy samples were analyzed for fibril density, volume fraction, and mean fibril area. Tendon mechanical properties were assessed using force and ultrasonography samplings. RESULTS: Patients improved in symptoms/function (P = .02...... area decreased (-26% +/- 21%, P = .04) in tendinopathic tendons after HSR. CONCLUSION: Fibril morphology is abnormal in tendinopathy, but tendon mechanical properties are not. Clinical improvements after HSR were associated with changes in fibril morphology toward normal fibril density and mean fibril...

  6. Embolic risk in atrial fibrillation that arises from hyperthyroidism: review of the medical literature.

    Science.gov (United States)

    Traube, Elie; Coplan, Neil L

    2011-01-01

    Atrial fibrillation, the most common cardiac complication of hyperthyroidism, occurs in an estimated 10% to 25% of overtly hyperthyroid patients. The prevalence of atrial fibrillation increases with age in the general population and in thyrotoxic patients. Other risk factors for atrial fibrillation in thyrotoxic patients include male sex, ischemic or valvular heart disease, and congestive heart failure. The incidence of arterial embolism or stroke in thyrotoxic atrial fibrillation is less clear. There are many reports of arterial thromboembolism associated with hyperthyroidism, including cases of young adults without coexisting risk factors other than thyrotoxic atrial fibrillation. The use of anticoagulative agents to prevent thromboembolic sequelae of thyrotoxic atrial fibrillation is controversial: National organizations provide conflicting recommendations in their practice guidelines. Herein, we review the medical literature and examine the evidence behind the recommendations in order to determine the best approach to thromboembolic prophylaxis in patients who have atrial fibrillation that is associated with hyperthyroidism.

  7. Postoperative atrial fibrillation in patients on statins undergoing ...

    African Journals Online (AJOL)

    Introduction: The efficacy of perioperative statin therapy in decreasing postoperative morbidity in patients undergoing valve replacements and repairs is unknown. The aim of our study was to determine whether or not the literature supports the hypothesis that statins decrease postoperative atrial fibrillation (AF), and hence ...

  8. Atrial Fibrillation in Embolic Stroke: Anticoagulant Therapy at UNTH ...

    African Journals Online (AJOL)

    Objective: The decision to commence anticoagulation in a patient with embolic stroke and atrial fibrillation (AF) is often a difficult one for many clinicians. The result can have significant impact on the patient. This study was therefore undertaken to review the use of anticoagulation in embolic stroke in the setting of atrial ...

  9. Frequency analysis of the ECG before and during ventricular fibrillation

    NARCIS (Netherlands)

    Herbschleb, J.N.; Heethaar, R.M.; Tweel, I. van der; Meijler, F.L.

    1980-01-01

    Frequency analysis of cardiac electrograms of dogs with ventricular fibrillation (VF) during complete cardiopulmonary bypass and coronary perfusion showed a power spectrum with a peak around 12 Hz and its higher harmonics, suggesting more organization than generally assumed. As a next step to see

  10. Occlusion of left atrial appendage in patients with atrial fibrillation

    Directory of Open Access Journals (Sweden)

    О. Н. Ганеева

    2015-10-01

    Full Text Available The article reviews a new method of prophylaxis of thromboembolitic complications, specifically occlusion of left atrial appendage, in patients with atrial fibrillation. Indications and contraindications for the procedure, as well as a step-by-step process of the intervention itself are described. Special emphasis is placed on the up-to-date evidence and the review of clinical trials.

  11. Abnormal atrial activation in young patients with lone atrial fibrillation

    DEFF Research Database (Denmark)

    Holmqvist, Fredrik; Olesen, Morten S; Tveit, Arnljot

    2011-01-01

    Patients with a history of atrial fibrillation (AF) have previously been shown to have altered atrial conduction, as seen non-invasively using signal-averaged P-wave analysis. However, little is known about the P-wave morphology in patients in the early phases of AF with structurally normal hearts....

  12. Cancer antigen-125 and risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Cheung, Angel; Gong, Mengqi; Bellanti, Roberto

    2018-01-01

    Background: Cancer antigen-125 (Ca-125) is traditionally recognised as a tumour marker and its role in cardiovascular diseases has been studied only in recent years. Whether Ca-125 is elevated in patients with atrial fibrillation (AF) and its levels predict the risk of AF remains controversial. T...

  13. Fibril Formation from Pea Protein and Sesequent Gel Formation

    NARCIS (Netherlands)

    Munialo, C.D.; Martin, A.H.; Linden, van der E.; Jongh, de H.H.J.

    2014-01-01

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20

  14. Fibril Formation from Pea Protein and Subsequent Gel Formation

    NARCIS (Netherlands)

    Munialo, XC.D.; Martin, A.H.; Linden, E. van der; Jongh, H.H.J de

    2014-01-01

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20

  15. P-wave duration and the risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Nielsen, Jonas B; Kühl, Jørgen T; Pietersen, Adrian

    2015-01-01

    BACKGROUND: Results on the association between P-wave duration and the risk of atrial fibrillation (AF) are conflicting. OBJECTIVE: The purpose of this study was to obtain a detailed description of the relationship between P-wave duration and the risk of AF. METHODS: Using computerized analysis o...

  16. Paroxysmal Atrial Fibrillation in a Mission-Assigned Astronaut

    Science.gov (United States)

    Bauer, Peter A.; Polk, J. D.

    2010-01-01

    This presentation will explore the clinical and administrative conundrums faced by the flight surgeon upon discovering asymptomatic paroxysmal atrial fibrillation seven months prior to scheduled long duration spaceflight. The presenter will discuss the decision-making process as well as the clinical and operational outcomes.

  17. Molecular Mechanisms and New Treatment Paradigm for Atrial Fibrillation.

    Science.gov (United States)

    Sirish, Padmini; Li, Ning; Timofeyev, Valeriy; Zhang, Xiao-Dong; Wang, Lianguo; Yang, Jun; Lee, Kin Sing Stephen; Bettaieb, Ahmed; Ma, Sin Mei; Lee, Jeong Han; Su, Demetria; Lau, Victor C; Myers, Richard E; Lieu, Deborah K; López, Javier E; Young, J Nilas; Yamoah, Ebenezer N; Haj, Fawaz; Ripplinger, Crystal M; Hammock, Bruce D; Chiamvimonvat, Nipavan

    2016-05-01

    Atrial fibrillation represents the most common arrhythmia leading to increased morbidity and mortality, yet, current treatment strategies have proven inadequate. Conventional treatment with antiarrhythmic drugs carries a high risk for proarrhythmias. The soluble epoxide hydrolase enzyme catalyzes the hydrolysis of anti-inflammatory epoxy fatty acids, including epoxyeicosatrienoic acids from arachidonic acid to the corresponding proinflammatory diols. Therefore, the goal of the study is to directly test the hypotheses that inhibition of the soluble epoxide hydrolase enzyme can result in an increase in the levels of epoxyeicosatrienoic acids, leading to the attenuation of atrial structural and electric remodeling and the prevention of atrial fibrillation. For the first time, we report findings that inhibition of soluble epoxide hydrolase reduces inflammation, oxidative stress, atrial structural, and electric remodeling. Treatment with soluble epoxide hydrolase inhibitor significantly reduces the activation of key inflammatory signaling molecules, including the transcription factor nuclear factor κ-light-chain-enhancer, mitogen-activated protein kinase, and transforming growth factor-β. This study provides insights into the underlying molecular mechanisms leading to atrial fibrillation by inflammation and represents a paradigm shift from conventional antiarrhythmic drugs, which block downstream events to a novel upstream therapeutic target by counteracting the inflammatory processes in atrial fibrillation. © 2016 American Heart Association, Inc.

  18. Atrial fibrillation: Therapeutic potential of atrial K+ channel blockers.

    Science.gov (United States)

    Ravens, Ursula; Odening, Katja E

    2017-08-01

    Despite the epidemiological scale of atrial fibrillation, current treatment strategies are of limited efficacy and safety. Ideally, novel drugs should specifically correct the pathophysiological mechanisms responsible for atrial fibrillation with no other cardiac or extracardiac actions. Atrial-selective drugs are directed toward cellular targets with sufficiently different characteristics in atria and ventricles to modify only atrial function. Several potassium (K + ) channels with either predominant expression in atria or distinct electrophysiological properties in atria and ventricles can serve as atrial-selective drug targets. These channels include the ultra-rapidly activating, delayed outward-rectifying Kv1.5 channel conducting I Kur , the acetylcholine-activated inward-rectifying Kir3.1/Kir3.4 channel conducting I K,ACh , the Ca 2+ -activated K + channels of small conductance (SK) conducting I SK , and the two pore domain K + (K2P) channels TWIK-1, TASK-1 and TASK-3 that are responsible for voltage-independent background currents I TWIK-1 , I TASK-1 , and I TASK-3 . Here, we briefly review the characteristics of these K + channels and their roles in atrial fibrillation. The antiarrhythmic potential of drugs targeting the described channels is discussed as well as their putative value in treatment of atrial fibrillation. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Posibilities of cardiac pacemaker use in paroxsysmal atrial fibrilation

    Directory of Open Access Journals (Sweden)

    Borut Kamenik

    2005-12-01

    Full Text Available Background: Prevention of atrial fibrillation is a big therapeutic challenge because of all known negative consequences of this the most frequent cardiac arrhythmia. Numerous of clinical studies showed bad control or ineffectiveness of antiarhythmic drugs. Nonfarmakological therapies like surgical treatment, radiofrequency ablation and atrial pacing are being tested. Effectiveness of atrial pacing in prevention of paroxysmal artial fibrillation has been documented in numerous prospective studies and is effective for a long time interval, but only for patients with bradicardic underlying cardiac rhythm. In Normocardic rhythm or normal AV conduction the effective Atrial fibrillation prevention was not proven. The mechanism of action is based on premature atrial complex suppression, reduction of dispersion of refractoriness after short-long cycles and reduction of interatrial conduction delay. The atrial stimulation site or multi-site atrial pacing could be effective in AF prevention when interatrial conduction delay is present; otherwise the difference is not significant.Conclusions: In bradicardic patient who has frequent paroxysms of atrial fibrillation, regardless if bradycardia is due to ineffective antiarrhythmic drug treathement, implantation of DDDR pacemaker with atrial prevention algorhythm is indicated. If the P-wave duration is >120 milliseconds multi-site atrial pacing or septal atrial pacing should be considered. Pacemaker diagnostic tools could be used for adequate start of anticoagulant therapy and control of effectiveness of anthyarhythmic drug therapy.

  20. Pattern of atrial fibrillation and risk of outcomes

    DEFF Research Database (Denmark)

    Banerjee, Amitava; Taillandier, Sophie; Olesen, Jonas Bjerring

    2012-01-01

    BACKGROUND: Risk of stroke and thromboembolism (TE) in patients with non-valvular atrial fibrillation (NVAF) is categorised in stroke risk stratification scores. The role of pattern of NVAF in risk prediction is unclear in contemporary 'real world' cohorts. METHODS AND RESULTS: Patients with NVAF...

  1. Effect of Mechanical Stretching of the Skin on Collagen Fibril ...

    African Journals Online (AJOL)

    Dell

    MATERIALS AND METHODS. In vitro Skin Incubation. Samples of tissue were .... experimentally obtained melting curves. Calculation of the entropy of denaturation was ... Temperature (TD), enthalpy (ΔH) and entropy (ΔS) of denaturation of fibrils formed from type I collagen synthesized in the skin in the absence of tensile ...

  2. Outcomes Associated With Familial Versus Nonfamilial Atrial Fibrillation

    DEFF Research Database (Denmark)

    Gundlund, Anna; Olesen, Jonas Bjerring; Staerk, Laila

    2016-01-01

    BACKGROUND: We examined all-cause mortality and long-term thromboembolic risk (ischemic stroke, transient ischemic attack, systemic thromboembolism) in patients with and without familial atrial fibrillation (AF). METHODS AND RESULTS: Using Danish nationwide registry data, we identified all patients...

  3. Ebstein's anomaly as a cause of paroxysmal atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Damjanović Miodrag R.

    2008-01-01

    Full Text Available Background. Ebstein's anomaly is characterized by a displacement of the tricuspid valve toward apex, because of anomalous attachment of the tricuspid leaflets. There are type B of Wolff-Parkinson-White (WPW syndrome and paroxysmal arrhythmias in more than a half of all patients. Case report. We presented a female, 32-year old, with frequent paroxysms of atrial fibrillation. After conversion of rhythm an ECG showed WPW syndrome. Echocardiographic examination discovered normal size of the left cardiac chambers with paradoxical ventricular septal motion. The right ventricle was very small because of its atrialization. The origin of the tricuspid valve was 20 mm closer to apex of the right ventricle than the origin of the mitral valve. Electrophysiological examination showed a posterolateral right accesorial pathway. Atrial fibrillation was induced very easily in electrophysiological laboratory and a successful ablation of accessorial pathway was made. There were no WPW syndrome and paroxysms of atrial fibrillation after that. Conclusion. Ebstein's anomaly is one of the reasons of paroxysmal atrial fibrillation, especially in young persons with WPW syndrome.

  4. Apixaban versus warfarin in patients with atrial fibrillation

    NARCIS (Netherlands)

    Granger, C.B.; Alexander, J.H.; McMurray, J.J.; Lopes, R.D.; Hylek, E.M.; Hanna, M.; Al-Khalidi, H.R.; Ansell, J.; Atar, D.; Avezum, A.; Bahit, M.C.; Diaz, R.; Easton, J.D.; Ezekowitz, J.A.; Flaker, G.; Garcia, D.; Geraldes, M.; Gersh, B.J.; Golitsyn, S.; Goto, S.; Hermosillo, A.G.; Hohnloser, S.H.; Horowitz, J.; Mohan, P.; Jansky, P.; Lewis, B.S.; Lopez-Sendon, J.L.; Pais, P.; Parkhomenko, A.; Verheugt, F.W.A.; Zhu, J.; Wallentin, L.

    2011-01-01

    BACKGROUND: Vitamin K antagonists are highly effective in preventing stroke in patients with atrial fibrillation but have several limitations. Apixaban is a novel oral direct factor Xa inhibitor that has been shown to reduce the risk of stroke in a similar population in comparison with aspirin.

  5. Hospitalisation patterns change over time in patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Fristrup Qvist, Janne; Høgh Sørensen, Pernille; Dixen, Ulrik

    2014-01-01

    INTRODUCTION: Atrial fibrillation (AF) is a cardiac epidemic. In this study, we aimed to describe the causes of hospital-isation in an AF population over time and to study how different AF treatment strategies affected hospitalization. MATERIAL AND METHODS: This was an observational study in which...

  6. Ganglion Plexus Ablation in Advanced Atrial Fibrillation: The AFACT Study

    NARCIS (Netherlands)

    Driessen, Antoine H. G.; Berger, Wouter R.; Krul, Sébastien P. J.; van den Berg, Nicoline W. E.; Neefs, Jolien; Piersma, Femke R.; Chan Pin Yin, Dean R. P. P.; de Jong, Jonas S. S. G.; van Boven, WimJan P.; de Groot, Joris R.

    2016-01-01

    Patients with long duration of atrial fibrillation (AF), enlarged atria, or failed catheter ablation have advanced AF and may require more extensive treatment than pulmonary vein isolation. The aim of this study was to investigate the efficacy and safety of additional ganglion plexus (GP) ablation

  7. Evalutating Inward Rectifier Current Inhibiton for Treatment of Atrial Fibrillation

    NARCIS (Netherlands)

    Ji, Yuan

    2017-01-01

    Atrial Fibrillation (AF) is one of the most common forms of cardiac arrhythmia and affects a large percentage of the human population, especially in the elderly. Currently, more than 6 million Europeans suffer from AF, and due to ageing this number will at least double in the next 50 years.

  8. Dabigatran versus warfarin in patients with atrial fibrillation

    NARCIS (Netherlands)

    Connolly, Stuart J.; Ezekowitz, Michael D.; Yusuf, Salim; Eikelboom, John; Oldgren, Jonas; Parekh, Amit; Pogue, Janice; Reilly, Paul A.; Themeles, Ellison; Varrone, Jeanne; Wang, Susan; Alings, Marco; Xavier, Denis; Zhu, Jun; Diaz, Rafael; Lewis, Basil S.; Darius, Harald; Diener, Hans-Christoph; Joyner, Campbell D.; Wallentin, Lars; Connolly, S. J.; Ezekowitz, M. D.; Yusuf, S.; Eikelboom, J.; Oldgren, J.; Parekh, A.; Reilly, P. A.; Themeles, E.; Varrone, J.; Wang, S.; Palmcrantz-Graf, E.; Haehl, M.; Wallentin, L.; Alings, A. M. W.; Amerena, J. V.; Avezum, A.; Baumgartner, I.; Brugada, J.; Budaj, A.; Caicedo, V.; Ceremuzynski, L.; Chen, J. H.; Commerford, P. J.; Dans, A. L.; Darius, H.; Di Pasquale, G.; Diaz, R.; Erol, C.; Ferreira, J.; Flaker, G. C.; Flather, M. D.; Franzosi, M. G.; Gamboa, R.; Golitsyn, S. P.; Gonzalez Hermosillo, J. A.; Halon, D.; Heidbuchel, H.; Hohnloser, S. H.; Hori, M.; Huber, K.; Jansky, P.; Kamensky, G.; Keltai, M.; Kim, S.; Lau, C. P.; Le Heuzey, J. Y. F.; Lewis, B. S.; Liu, L. S.; Nanas, J.; Razali, O.; Pais, P. S.; Parkhomenko, A. N.; Pedersen, K. E.; Piegas, L. S.; Raev, D.; Simmers, T. A.; Smith, P. J.; Talajic, M.; Tan, R. S.; Tanomsup, S.; Toivonen, L.; Vinereanu, D.; Xavier, D.; Zhu, J.; Diener, H. C.; Joyner, C. D.; Diehl, A.; Ford, G.; Robinson, M.; Silva, J.; Sleight, P.; Wyse, D. G.; Collier, J.; de Mets, D.; Hirsh, J.; Lesaffre, E.; Ryden, L.; Sandercock, P.; Anastasiou-Nana, M. I.; Andersen, G.; Annex, B. H.; Atra, M.; Bornstein, N. M.; Boysen, G.; Brouwers, P. J. A. M.; Buerke, M.; Burrell, L. M.; Chan, Y. K.; Chen, W. H.; Cheung, R. T. F.; Divakaramenon, S.; Donnan, G. A.; Duray, G. Z.; Dvorakova, H.; Fiedler, J.; Gardinale, E.; Gates, P. C.; Goshev, E. G.; Goto, S.; Gross, B.; Guimaraes, H. P.; Gulkevych, O.; Haberl, R. L.; Hankey, G.; Hartikainen, J.; Healey, J.; Iliesiu, A. M.; Irkin, O.; Jaxa-Chamiec, T.; Jolly, S.; Kaste, K. A. M.; Kies, B.; Kostov, K. D.; Kristensen, K. S.; Labovitz, A. J.; Lassila, R. P. T.; Lee, K. L. F.; Lutay, Y. M.; Magloire, P.; Mak, K. H.; Meijer, A.; Mihov, L.; Morillo, C. A.; Morillo, L. E.; Nair, G. M.; Norrving, B.; Ntalianis, A.; Ntsekhe, M.; Olah, L.; Pasco, P. M. D.; Peeters, A.; Perovic, V.; Petrov, I.; Pizzolato, G.; Rafti, F.; Rey, N. R.; Ribas, S.; Rokoss, M.; Sarembock, I. J.; Sheth, T.; Shuaib, A.; Sitkei, E.; Sorokin, E.; Srámek, M.; Strozynska, E.; Tanne, D.; Thijs, V. N. S.; Tomek, A.; Turazza, F.; Vanhooren, G.; Vizel, S. A.; Vos, J.; Wahlgren, N.; Weachter, R.; Zaborska, B.; Zaborski, J.; Zimlichman, R.; Cong, J.; Fendt, K.; Muldoon, S.; Bajkor, S.; Grinvalds, A.; Malvaso, M.; Pogue, J.; Simek, K.; Yang, S.; Alzogaray, M. F.; Bono, J. O.; Caccavo, A.; Cartasegna, L.; Casali, W. P.; Cuello, J. L.; Cuneo, C. A.; Elizari, M. V.; Fernandez, A. A.; Ferrari, A. E.; Gabito, A. J.; Goicoechea, R. F.; Gorosito, V. M.; Hirschson, A.; Hominal, M. A.; Hrabar, A. D.; Liberman, A.; Mackinnon, I. J.; Manzano, R. D.; Muratore, C. A.; Nemi, S. A.; Rodriguez, M. A.; Sanchez, A. S.; Secchi, J.; Vogel, D. R.; Colquhoun, D. M.; Crimmins, D. S.; Dart, A. M.; Davis, S. M.; Hand, P. J.; Kubler, P. A.; Lehman, R. G.; McBain, G.; Morrison, H. C.; New, G.; Singh, B. B.; Spence, C. Z.; Waites, J. H.; Auer, J.; Doweik, L.; Freihoff, F.; Gaul, G.; Gazo, F.; Geiger, H.; Giacomini, G.; Huber, G. W.; Jukic, I.; Lamm, G.; Niessner, H.; Podczeck, A.; Schuh, J.; Siostrzonek, P.; Steger, C.; Vogel, B.; Watzak, R.; Weber, H. S.; Weihs, W.; Blankoff, I.; Boland, J. L.; Brike, C.; Carlier, M.; Cools, F.; de Meester, A.; de Raedt, H. J.; de Wolf, L.; Dhooghe, G. M.; Dilling-Boer, D.; Elshot, S. R.; Fasseaux, S.; Goethals, M.; Goethals, P.; Gurne, O.; Hellemans, S.; Ivan, B.; Jottrand, M.; Kersschot, I.; Lecoq, E.; Marcovitch, O.; Melon, D.; Miljoen, H.; Missault, L.; Pierard, L. A.; Provenier, F.; Rousseau, M. F.; Stockman, D.; Tran-Ngoc, E.; van Mieghem, W.; Vandekerckhove, Y.; Vandervoort, P.; Verrostte, J.; Vijgen, J.; Armaganijan, D.; Braga, C.; Braga, J. C. F.; Cipullo, R.; Cunha, C. L. P.; de Paola, A.; Delmonaco, M. I.; Guimaraes, F. V.; Herek, L.; Kerr Saraiva, J. F.; Maia, L. N.; Lorga, A. M.; Lorga-Filho, A. M.; Marino, R. L.; Melo, C. S.; Mouco, O. M.; Pereira, V. C.; Precoma, D. B.; Rabelo, W.; Rassi, S.; Rossi, P. R.; Rossi Neto, J. M.; Silva, F. M.; Vidotti, M. H.; Zimmermann, S. L.; Anev, E. D.; Balabanov, T. A.; Baldjiev, E. S.; Bogusheva, E. S.; Chaneva, M. A.; Filibev, I. G.; Gotcheva, N. N.; Goudev, A. R.; Gruev, I. T.; Guenova, D. T.; Kamenova, Z. A.; Manov, E. I.; Panov, I. A.; Parvanova, Z. I.; Pehlivanova, M. B.; Penchev, P. T.; Penkov, N. Y.; Radoslavov, A. L.; Ramshev, K. N.; Runev, N. M.; Sindzhielieva, M. N.; Spirova, D. A.; Tsanova, V. M.; Tzekova, M. L.; Yaramov, G. K.; Aggarwal, R.; Bakbak, A. I.; Bayly, K.; Berlingieri, J. C.; Blackburn, K.; Bobbie, C.; Booth, A. W.; Borts, D.; Bose, S.; Boucher, P.; Brown, K.; Burstein, J. M.; Butt, J. C.; Carlson, B. D.; Chetty, R.; Chiasson, J. D.; Constance, C.; Costi, P.; Coutu, B.; Deneufbourg, I.; Dion, D.; Dorian, P.; Douketis, J. D.; Farukh, S.; Filipchuk, N. G.; Fox, B. A.; Fox, H. I.; Gailey, C. B.; Gauthier, M.; Glanz, A.; Green, M. S.; Habot, J.; Hink, H.; Kearon, C.; Kouz, S.; Lai, C.; Lai, K.; Lalani, A. V.; Lam, A. S.; Lapointe, L. A.; Leather, R. A.; Ma, P. T. S.; MacKay, E.; Mangat, I.; Mansour, S.; Melton, E.; Mitchell, L. B.; Morris, A. L.; Nisker, W. A.; O'Donnell, M. J.; O'Hara, G.; Omichinski, L. M.; Pandey, A. S.; Parkash, R.; Pesant, Y.; Pilon, C.; Pistawka, K. J.; Powell, C. N.; Price, J. B.; Prieur, S.; Rebane, T. M.; Ricci, A. J.; Roberge, J.; Roy, M.; Sapp, J. L.; Savard, D.; Schulman, S.; Sehl, M. J.; Sestier, F.; Shandera, R.; Shu, D.; Sterns, L. D.; St-Hilaire, R.; Syan, G. S.; Talbot, P.; Teitelbaum, I.; Tytus, R. H.; Winkler, L.; Zadra, R.; Zidel, B. S.; Bai, X. J.; Gao, W.; Gao, X.; Guan, D. M.; He, Z. S.; Hua, Q.; Li, H.; Li, L.; Li, W. M.; Lu, G. P.; Lv, S.; Meng, K.; Niu, H. Y.; Qi, D. G.; Qi, S. Y.; Qian, F.; Sun, N. L.; Wang, H. Y.; Wang, N. F.; Yang, Y. M.; Zeng, H.; Zhang, F.; Zhang, F. R.; Zhang, L.; Bohorquez, R.; Rosas, J. F.; Saent, L.; Vacca, M.; Velasco, V. M.; Belohlavek, J.; Cernohous, M.; Choura, M.; Dedek, V.; Filipensky, B.; Hemzsky, L.; Karel, I.; Kopeckova, I.; Kovarova, K.; Labrova, R.; Madr, T.; Poklopova, Z.; Rucka, D.; Simon, J.; Skalicka, H.; Smidova, M.; Spinar, J.; Dodt, K. K.; Egstrup, K.; Friberg, J.; Haar, D.; Husted, S.; Jensen, G. V.; Joensen, A. M.; Klarlund, K. K.; Lind Rasmussen, S.; Melchior, T. M.; Olsen, M. E.; Poulsen, M. K.; Ralfkiaer, N.; Rasmussen, L. H.; Skagen, K.; Airaksinen, K. E.; Huikuri, H. V.; Hussi, E. J.; Kettunen, P.; Mänttäri, M.; Melin, J. H.; Mikkelsson, J.; Peuhkurinen, K.; Virtanen, V. K.; Ylitalo, A.; Agraou, B.; Boucher, L.; Bouvier, J. M.; Boye, A.; Boye, B.; Decoulx, E. M.; Defaye, P.; Delay, M.; Desrues, H.; Gacem, K.; Igigabel, P.; Jacon, P.; Leparree, S.; Magnani, C.; Martelet, M.; Movallem, J.; Olive, T.; Poulard, J. E.; Tiam, B.; Appel, K. F.; Appel, S.; Bansemir, L.; Borggrefe, M.; Brachmann, J.; Bulut-Streich, N.; Busch, K.; Dempfle, C. E. H.; Desaga, M.; Desaga, V.; Dormann, A.; Fechner, I.; Genth-Zotz, S.; Haberbosch, W. G.; Harenberg, J.; Haverkamp, W. L.; Henzgen, R.; Heuer, H.; Horacek, T.; Huttner, H. B.; Janssens, U.; Jantke, H. J.; Klauss, V.; Koudonas, D.; Kreuzer, J.; Kuckuck, H.; Maselli, A.; Müegge, A.; Munzel, T. F.; Nitsche, K.; Nledegjen, A.; Parwani, A.; Pluemer-Schmidt, M.; Pollock, B. W.; Salbach, B. I.; Salbach, P. B.; Schaufele, T.; Schoels, W.; Schwab, S.; Siegmund, U.; Veltkamp, R.; Von Hodenberg, E.; Weber, R.; Zechmeister, M.; Anastasopoulous, A. A.; Foulidis, V. O.; Kaldara, E.; Karamitsos, K.; Karantzis, J.; Kirpizidis, H.; Kokkinakis, C.; Krommydas, A.; Lappas, C.; Lappas, G. I.; Manolis, A.; Manolis, A. S.; Orfanidis, Z.; Papamichalis, M.; Peltekis, L.; Savvas, S.; Skoumpourdis, E. A.; Stakos, D. A.; Styliadis, I.; Triposkiadis, F.; Tsounis, D.; Tziakas, D. N.; Zafiridis, T.; Zarifis, J. H.; Chan, G. C. P.; Chan, W. K.; Chan, W. S.; Lau, C. L.; Tse, H. F.; Tsui, P. T.; Yu, C. M.; Yue, C. S.; Fugedi, K.; Garai, B.; Jánosi, A.; Kadar, A.; Karpati, P.; Keltai, K.; Kosa, I.; Kovacs, I.; Laszlo, Z.; Mezei, L.; Rapi, J.; Regos, L. I.; Szakal, I.; Szigyarto, I.; Toth, K.; Zsa'ry, A.; Agarwal, D. K.; Aggarwal, R. K.; Arulvenkatesh, R.; Bharani, A.; Bhuvaneswaran, J. S.; Byrapaneni, R. B.; Chandwani, P.; Chopra, S.; Desai, N.; Deshpande, V.; Golla, N. P.; Gupta, J. B.; Haridas, K. K.; Hiremath, J.; Jain, A. S.; Jain, M.; Jhala, D. A.; Joseph, J.; Kaila, M.; Kannaiyan, A.; Kumar, S.; Kuruvila, P.; Mahorkar, V. K.; Metha, A.; Naik, A. M.; Narayanan, S.; Panwar, R. B.; Reddy, C.; Sawhney, J. P. S.; Shah, S. M.; Sharma, S.; Shetty, G. S.; Sinha, N.; Sontakke, N. N.; Srinivas, A.; Trivedi, M. R.; Vadagenalli, P. S.; Vijayakumar, M.; Ben-Aharon, Y.; Benhorin, J.; Bogomolny, N.; Botwin-Shimko, S.; Bova, I.; Brenner, B.; Burstein, M.; Butnaru, A.; Caspi, A.; Danenberg, H. D.; Dayan, M.; Eldar, M.; Elian, D.; Elias, M.; Elis, A.; Esanu, G.; Genin, I.; Goldstein, L. H.; Grossman, E.; Hamoud, S.; Hayek, T.; Ilani, N.; Ilia, R.; Klainman, E. I.; Leibowitz, A.; Leibowitz, D.; Levin, I.; Lishner, M.; Lotan, C.; Mahagney, A.; Marmor, A.; Motro, M.; Peres, D.; Plaev, T.; Reisen, L. H.; Rogowski, O.; Schwammenthal, E.; Schwammenthal, Y.; Shechter, M.; Shochat, M.; Shotan, A.; Strasberg, B.; Sucher, E.; Telman, G.; Turgeman, Y.; Tzoran, I.; Weiss, A. T.; Weitsman, T.; Weller, B.; Wexler, D. 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G.; Pirelli, S.; Renda, G.; Santini, M.; Tavarozzi, I.; Terrosu, P.; Uneddu, F.; Viccione, M.; Zanini, R.; Zingarini, G.; Aoyagi, T.; Eguma, H.; Fujii, K.; Fukuchi, M.; Fukunami, M.; Furukawa, Y.; Furuya, J.; Haneda, K.; Hara, S.; Hiroe, M.; Iesaka, Y.; Iijima, T.; Ishibashi, Y.; Iwade, K.; Kajiya, T.; Kakinoki, S.; Kamakura, S.; Katayama, Y.; Kihara, Y.; Kimura, K.; Kobayashi, S.; Kono, K.; Koretsune, Y.; Marui, N.; Matsuyama, T.; Meno, H.; Miyamoto, N.; Morikawa, S.; Myojin, K.; Nakamura, T.; Nishi, Y.; Ogawa, T.; Onaka, H.; Sakakibara, T.; Sakurai, S.; Sasaki, Y.; Sato, H.; Sugii, M.; Sumii, K.; Suzuki, S.; Takagi, M.; Takenaka, T.; Takeuchi, K.; Tanaka, S.; Tanouchi, J.; Ueda, K.; Ueyama, Y.; Ujihira, T.; Usui, M.; Yagi, M.; Yamada, T.; Yamamoto, H.; Yokochi, M.; Zen, E.; Abd Ghaphar, A. K.; Ang, C. K.; Chee, K. H.; Fong, A. F. Y.; Ismail, O.; Jeyaindran, S.; Kaur, S.; Lee, T. C.; Sandhu, R. S.; Shah, R. 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M.; Arnesen, H.; Atar, D.; Breder, O.; Istad, H.; Radunovic, Z.; Rykke, D. E.; Sirnes, P. A.; Tveit, A.; Ulimoen, S. R.; Cabrera, W.; Duenas, R.; Heredia, J. M.; Horna, M. E.; Hurtado, Y.; Salazar, P. M.; Abola, M. T. B.; Anonuevo, J. C.; Arellano, R. S.; Dioquino, C.; Morales, D. D.; Reyes, E. B.; Rogelio, G. G.; Roxas, A. A.; Sulit, D. J. V.; Bacior, B.; Dulak, E.; Gniot, J.; Goncikowski, J.; Grodecki, J.; Kalarus, Z. F.; Kawecka-Jaszcz, K.; Miekus, P.; Monies, F.; Piepiorka, M.; Pilichowska, E.; Plizio, E.; Rekosz, J.; Rybicka-Musialik, A.; Streb, W. A.; Styczkiewicz, M.; Szpajer, M.; Trusz-Gluza, M.; Wasilewska-Piepiorka, A.; Adragao, P.; Branco, V.; Canhão, P.; Cunha, L.; Falcão, F.; Lopes, G.; Machado, C.; Martinez-Marcos, J.; Monteiro, P. F.; Parreira, L.; Pinto, A. N.; Providencia, L. A.; Salgado, A. V.; Santos, J. F.; Timoteo, A. T.; Capalneanu, R.; Cinteza, M. A.; Margulesai, A. D.; Turdeanu, D. S.; Vintila, V. D.; Baranov, V. L.; Berngardt, E. R.; Dzhordzhikiya, T. R.; Gordeev, I. G.; Grigoryev, Y. V.; Isaeva, M. U.; Ivleva, A. Y.; Kokorin, V. A.; Komarov, A. L.; Maximenko, O. K.; Maykov, E. B.; Novikova, N.; Novikova, T. N.; Panchenko, E. P.; Poltavskaya, M. G.; Popova, Y. N.; Pronina, S. A.; Revishvili, A. Sh; Shlyakhto, E. V.; Shustov, S. B.; Sidorenko, B. A.; Sinopalnikov, A. I.; Sulimov, V.; Syrkin, A. L.; Titkov, A. Y.; Titkov, Y. S.; Zateyshchikov, D. A.; Zavaritskaya, O. P.; Chia, P. L.; Foo, D.; Sim, K. L.; Bugan, V.; Buganova, I.; Dúbrava, J.; Kaliska, G.; Masarovicova, M.; Mikes, P.; Mikes, Z.; Murin, J.; Pella, D.; Rybar, R.; Sedlák, J.; Skamla, M.; Spurný, P.; Strbova, J.; Uhliar, R.; Disler, L. J.; Engelbrecht, J. M.; Jankelow, D.; King, J.; Klug, E. Q.; Munnick, M.; Okreglicki, A. M.; Routier, R. J.; Snyders, F. A.; Theron, H. D.; Wittmer, H.; Cha, T. J.; Cho, J. G.; Choi, I. S.; Choi, J. I.; Choi, K. J.; Han, K. R.; Heo, J. H.; Jang, S. W.; Kang, T. S.; Kim, H. S.; Kim, K. S.; Kim, S. J.; Kim, S. S.; Kim, Y. H.; Kim, Y. N.; Lee, M. H.; Lee, M. Y.; Nam, G. B.; Oh, D. J.; Park, H. W.; Park, J. S.; Rho, T. H.; Shin, D. G.; Shin, E. K.; Alonso, J. J.; Cano, L.; Castellano, N. P.; Criado-Millan, A. J.; Curcio, A.; Egea, P.; Escudier, J. M.; Grande, A.; Grande, J. M.; Gusi-Tragant, G.; Lozano, I. F.; Martin, A. M.; Martinez-Rubio, A.; Mont, L.; Perez-Villacastin, J.; Sosa, L.; Ali, M.; Andersson, T.; Bandh, S.; Blomstrom Lundqvist, C. M.; Cherfan, P.; Fengsrud, E.; Fluur, C.; Herlitz, J.; Hijazi, Z.; Hoglund, N.; Hojeberg, B.; Jabro, J.; Juhlin, T.; Kjellman, B.; Lonnberg, I.; Maru, F.; Morlid, L.; Nilsson, O. R.; Ronn, F.; Rosenqvist, M.; Walfridsson, H.; Engelter, S. T.; Gallino, A.; Lyrer, P. A.; Moccetti, T.; Petrova, I.; Chang, Y. J.; Chen, C. H.; Chen, M. Y. C.; Cheng, J. J.; Chiang, T. R.; Chung, W. T.; Hsia, C. H.; Hsu, C. Y.; Hu, H. H.; Jeng, J. S.; Lai, W. T.; Lien, L. M.; Lin, K. H.; Liu, C. H.; Lo, H. S.; Peng, G. S.; Po, H. L.; Ryu, S. J.; Tsai, C. D.; Tsai, L. M.; Tseng, C. D.; Wang, J. H.; Wang, S. F.; Yang, S. P.; Kiatchoosakun, S.; Krittayaphong, R.; Kuanprasert, S.; Ngarmukos, T.; Simtharakaew, T.; Sukanandachai, B.; Sukonthasam, A.; Suwanagool, A.; Tatsanavivat, P.; Atmaca, Y.; Baris, N.; Boyaci, B.; Demir, M.; Guneri, S.; Usal, A.; Yalcin, R.; Amosova, K. M.; Beregova, O. P.; Besaga, Y. E. M.; Ikorkin, M. R.; Karapetyan, K.; Karpenko, O. I.; Kononenko, L.; Kuryata, O.; Martynova, L.; Motylevska, T.; Okhryamkina, O.; Pavlyk, S. S.; Perepelytsya, M. V.; Rudenko, L. V.; Skarzhevsky, O. A.; Tkachenko, L. A.; Tseluyko, V.; Usan, N.; Voronkov, L. G.; Yshchenko, K. V.; Zharinov, O. J.; Bryson, V. G.; Butler, R.; Cargill, R. I.; Chahal, N. S.; Cleland, J. G.; Cohen, A. T.; Cruddas, E. M.; Davey, P.; Davies, J.; Ford, S. L.; Griffith, K.; Haynes, R.; Hill, S.; Javed, M.; Kadr, H. H.; Lip, G. H.; Machin, J.; McEneaney, D. J.; McInnes, G. T.; McNeill, A. J.; Moriarty, A. J.; Muir, S.; O'Callaghan, J.; Purvis, J. A.; Pye, M.; Senior, R.; Sutton, D. A.; Thomas, S. H. L.; Wilkinson, P. R.; Wilmott, R.; Wrigley, M. J.; Abadier, R.; Abbud, Z. A.; Adams, K. V.; Adler, S. W.; Agarwal, S.; Ahmed, A. M.; Ahmed, I. S.; Aiuto, M. A.; Albrittun, T. D.; Aliyar, P.; Allan, J. J.; Allen, D. P.; Allen, S. L.; Altschuller, A.; Amin, M.; Anand, I. S.; Antolick, A. B.; Arora, R.; Arouni, A. J.; Arslanian, C. L.; Asinger, R. W.; Aycock, G. R.; Bariciano, R. J.; Baron, S. B.; Barr, M. A.; Bartkowiak, A. J.; Baruch, L.; Basignani, C.; Bass, M. L.; Bean, B.; Bedwell, N. W.; Belber, A. D.; Belew, K.; Bell, Y. C.; Bellinger, R. L.; Bennett, W. T.; Bensimhon, D. R.; Benton, R.; Benton, R. E.; Ben-Yehuda, O.; Bertolet, B. D.; Betkowski, A. S.; Bilazarian, S. D.; Bissette, J. K.; Bobade, M. B.; Bolster, D. E.; Bomba, J.; Book, D. M.; Boscia, J. A.; Bouchard, A.; Bowman, L. M.; Bradley, A. J.; Brandt, H. D.; Bricker, C. R.; Brobyn, T. L.; Brock, R. I.; Broderick, T. M.; Broedlin, K.; Brown, A. M.; Browne, K. F.; Burke, S. W.; Burton, M. E.; Buser, G. A.; Capasso, M. K.; Caplan, W. E.; Cappelli, J.; Cardona, C.; Cardona, F.; Carlson, T.; Carr, K. W.; Casey, T.; Cashion, W. R.; Cass, D. T.; Chandrashekar, Y. S.; Changlani, M.; Chapla, P. G.; Chappell, J. H.; Chen, C.; Chen, Y.; Cho, N. R.; Cieszkowski, J. H.; Clark, D. M.; Clayton, R.; Clogston, C. W.; Cockrell, D. J.; Cohen, A. I.; Cohen, T. J.; Cole, J. F.; Conway, G.; Cook, V. R.; Cornish, A. L.; Cossu, S. F.; Costello, D. L.; Courtade, D. J.; Covelli, H. C.; Crenshaw, B. S.; Crews, L. A.; Crossley, G. H.; Culp, S. C.; Curtis, B. M.; Darrow, K.; de Raad, R. E.; DeGregorio, M.; DelNegro, A. A.; Denny, D. M.; Desai, V. S.; Deumite, N. J.; Dewey, L.; Dharawat, R. N.; Dobbs, B.; Donahue, S. M.; Downey, B.; Downing, J.; Drehobl, M. A.; Drewes, W. A.; Drucker, M. N.; Duff, R.; Duggal, M.; Dunlap, S. H.; Dunning, D. W.; DuThinh, V.; Dykstra, G. T.; East, C.; Eblaghie, M. C.; Edelstein, J.; Edmiston, W. A.; Eisen, H. J.; Eisenberg, S. J.; Ellis, J. R.; Ellison, H. S.; Ellsworth, S.; Elshahawy, M.; Emlein, G.; Entcheva, M.; Essandoh, L. K.; Estrada, A. Q.; Ewing, B.; Faillace, R. T.; Fanelli, A.; Farrell, P. W.; Farris, S. W.; Fattal, P. G.; Feigenblum, D. Y.; Feldman, G. J.; Fialkow, J. A.; Fiddler, K. M.; Fields, R. H.; Finkel, M. S.; Finn, C.; Fischell, T. A.; Fishbach, M.; Fishbein, G. J.; Fisher, M. M.; Fleischhauer, F. J.; Folk, T. G.; Folkerth, S. D.; Fortman, R. R.; Frais, M. A.; Friedman, D. C.; Fuchs, G.; Fuller, F.; Garibian, G.; Gee, F. H.; Gelernt, M. D.; Genovely, H. C.; Gerber, J. R.; Germano, J. J.; Giardina, J. J.; Gilbert, J. M.; Gillespie, E. L.; Gilman, E. M.; Gitler, B.; Givens, D. H.; Glover, R.; Gogia, H. S.; Gohn, D. C.; Goldberg, R. K.; Goldberger, J. J.; Goldscher, D. A.; Goldstein, M.; Goraya, T.; Gordon, D. F.; Gottlieb, D.; Grafner, H. L.; Graham, M.; Graves, M. W.; Graziano, M.; Greco, S. N.; Greenberg, M. L.; Greenspon, A. J.; Greer, G. S.; Griffin, D. D.; Grogan, E. W.; Groo, V. L.; Guarnieri, T.; Gupta, A.; Gupta, J.; Hack, T. C.; Hall, B.; Hallak, O.; Halpern, S. W.; Hamburg, C.; Hamroff, G. S.; Han, J.; Handel, F.; Hankins, S. R.; Hanovich, G. D.; Hanrahan, J. A.; Haque, I. U.; Hargrove, J. L.; Harnick, P. E.; Harris, J. L.; Hartley, P. A.; Haskel, E. J.; Hatch, D.; Haught, W. H.; Hearne, S.; Hearne, S. E.; Hemphill, J. A.; Henderson, D. A.; Henes, C. H.; Hengerer-Yates, T.; Hermany, P. R.; Herzog, W. R.; Hickey, K.; Hilton, T. C.; Hockstad, E. S.; Hodnett, P.; Hoffmeister, R.; Holland, J.; Hollenweger, L.; Honan, M. B.; Hoopes, D. A.; Hordes, A. R.; Hotchkiss, D. A.; Howard, M. A.; Howard, V. N.; Hulyalkar, A. R.; Hurst, P.; Hutchison, L. C.; Ingram, J.; Isakov, T.; Ison, R. K.; Israel, C. N.; Jackson, B. K.; Jackson, K. N.; Jacobson, A. K.; Jain, S.; Jarmukli, N. F.; Joffe, I.; Johnson, L. E.; Johnson, S. A.; Johnson, S. L.; Jones, A. A.; Joyce, D. B.; Judson, P. L.; Juk, S. S.; Kaatz, S.; Kaddaha, R. M.; Kaplan, K. J.; Karunaratne, H. B.; Kennett, J. D.; Kenton, D. M.; Kettunen, J. A.; Khan, M. A.; Khant, R. N.; Kirkwood, M. D.; Knight, B. P.; Knight, P. O.; Knutson, T. J.; Kobayashi, J. F.; Kogan, A.; Kogan, A. D.; Koren, M. J.; Kosinski, E. J.; Kosolcharoen, P.; Kostis, J. B.; Kramer, J. H.; Kramer, S. D.; Kron, J.; Kuchenrither, C. R.; Kulback, S. J.; Kumar, A.; Kushner, D.; Kutscher, A.; Lai, C. K.; Lam, J. B.; Landau, C.; Landzberg, J. S.; Lang, D. T.; Lang, J. M.; Lanzarotti, C. J.; Lascewski, D. L.; Lau, T. K.; Lee, J. K.; Lee, S.; Leimbach, W. N.; LePine, A. M.; Lesser, M. F.; Leuchak, S. H.; Levy, R. M.; Lewis, W. R.; Lincoln, T. L.; Lingerfelt, W. M.; Liston, M.; Liu, Z. G.; Lloret, R. L.; Lohrbauer, L.; Longoria, D. C.; Lott, B. M.; Louder, D. R.; Loukinen, K. L.; Lovell, J.; Lue, S.; Mackall, J. A.; Maletz, L.; Marlow, L.; Martin, R. C.; Matsumura, M.; McCartney, M. J.; McDuffie, D.; McGough, M. F.; McGrew, F. A.; McGuinn, Wm P.; McMillen, M. D.; McNeff, J.; McPherson, C. A.; Meengs, M. E.; Meengs, W. L.; Meholick, A. W.; Meisner, J. S.; Melucci, M. B.; Mercando, A.; Merlino, J. D.; Meymandi, S. K.; Miele, M. B.; Miller, R. H.; Miller, S. H.; Minor, S. T.; Mitchell, M. R.; Modi, M.; Mody, F. V.; Moeller, C. L.; Moloney, J. F.; Moran, J. E.; Morcos, N. C.; Morgan, A.; Mukherjee, S. K.; Mullinax, K.; Murphy, A. L.; Mustin, A. J.; Myers, G. I.; Naccarelli, G. V.; Nadar, V. K.; Nallasivan, M.; Navas, J. P.; Niazi, I. K.; Nsah, E. N.; Nunamaker, J. L.; Ochalek, T. B.; O'dea, D. J.; Ogilvie, P. D.; Olliff, B.; Omalley, A. K.; O'Neill, P. G.; Onufer, J. R.; Orchard, R. C.; Orihuela, L. A.; Ortiz, E. C.; O'Sullivan, M. T.; Padanilam, B. J.; Pandey, P.; Patel, D. V.; Patel, R. J.; Patel, V. B.; Patlola, R. R.; Pennock, G. D.; Perlman, R.; Peters, P. H.; Petrillo, A. V.; Pezzella, S.; Phillips, D.; Pierre-Louis, J. R.; Pilcher, G.; Pillai, C.; Pollock, S. G.; Pond, M. S.; Porterfield, J. K.; Presant, L.; Pressler, J.; Pribble, A. H.; Promisloff, S. D.; Pudi, K. K.; Putnam, D. L.; Quartner, J.; Quinn, J. C.; Quinnell, C. M.; Raad, G. L.; Rasmussen, L. A.; Ray, C.; Reiffel, J. A.; Reynertson, S.; Richardson, J. W.; Riley, C. P.; Rippy, J. S.; Rittelmeyer, J. T.; Roberts, D. M.; Robertson, R.; Robinson, V. J. B.; Rocco, T. A.; Rosenbaum, D.; Roth, E. M.; Rottman, J. N.; Rough, R. R.; Rubenstein, J. J.; Sakkal, A. M.; Saleem, T.; Salerno, D. M.; Samendinger, M. L.; Sandeno, S.; Santilli, T. M.; Santucci, P.; Sattar, P.; Saxman, K. A.; Schaefer, S.; Schmidt, J.; Schneider, R. M.; Schocken, D. D.; Schrader, M. K.; Schramm, B. A.; Schultz, R. W.; Schussheim, A. E.; Schwarz, E. F.; Seamon, M. C.; Sestero, J. D.; Shah, M. P.; Shah, R.; Shalaby, A.; Shanes, J. G.; Sheftel, G. L.; Sheikh, K. H.; Shein, A. B.; Shemonsky, N. K.; Shepler, A.; Sheridan, E.; Shipwash, T. M.; Shopnick, R. I.; Short, W. G.; Shoukfeh, M. F.; Sibia, R. S.; Siler, T. M.; Silva, J. A.; Simons, G. R.; Simpson, A. G.; Simpson, H. R.; Simpson, V. J.; Singh, B. N.; Singh, N.; Singh, V. N.; Sitz, C. J.; Skatrud, L.; Sklar, J.; Slotwiner, D. J.; Smith, P. F.; Smith, P. N.; Smith, R. H.; Smith, J. E.; Sodowick, B. C.; Solomon, A. J.; Soltero, E. A.; Sonel, A. F.; Sperling, R.; Spiller, C.; Spink, B. Z.; Sprinkle, L. W.; Spyropoulos, A. C.; Stamos, T. D.; Steljes, A. D.; Stillabower, M. E.; Stover, T.; Strain, J. E.; Strickland, T. L.; Suresh, D. P.; Takata, T. S.; Taylor, J. S.; Taylor, M.; Teague, S. M.; Teixeia, J. M.; Telfer, E. A.; Terry, P. S.; Terry, R. W.; Thai, H. M.; Thalin, M.; Thomas, V. N.; Thompson, C. A.; Thompson, M. A.; Thornton, J. W.; Tidman, R. E.; Toler, B. S.; Traina, M. I.; Trippi, J. A.; Ujiiye, D. L.; Usedom, J. E.; van de Graaff, E.; van de Wall, L. R.; Vaughn, J. W.; Ver Steeg, D.; Vicari, R. M.; Vijay, N.; Vitale, C. B.; Vlastaris, A. G.; Voda, J.; Vora, K. N.; Voyles, W. F.; Vranian, R. B.; Vrooman, P. S.; Waack, P.; Waldo, A. L.; Walker, J. L.; Wallace, M. A.; Walsh, E. A.; Walsh, R. L.; Walton, A.; Washam, M.; Wehner, P. S.; Wei, J. Y.; Weiner, S.; Weiss, R. J.; Wells, D. M.; Wera-Archakul, W.; Wertheimer, J. H.; West, S. A.; Whitaker, J. H.; White, M. L.; White, R. H.; Whitehill, J. N.; Wiegman, P. J.; Wiesel, J.; Williams, J.; Williams, L. E.; Williams, M. L.; Williamson, V. K.; Wilson, V. E.; Wilson, W. W.; Woodfield, S. L.; Wulff, C. W.; Yates, S. W.; Yousuf, K. A.; Zakhary, B. G.; Zambrano, R.; Zimetbaum, P.; Zoble, R.; Zopo, A. R.; Zwerner, P. L.

    2009-01-01

    BACKGROUND: Warfarin reduces the risk of stroke in patients with atrial fibrillation but increases the risk of hemorrhage and is difficult to use. Dabigatran is a new oral direct thrombin inhibitor. METHODS: In this noninferiority trial, we randomly assigned 18,113 patients who had atrial

  9. Comparative study of atrial fibrillation and AV conduction in mammals

    NARCIS (Netherlands)

    Meijler, F.L.; Tweel, I. van der

    1987-01-01

    Atrial fibrillation is one ofthe most common cardiac arrhythmias in humans. It a1so occurs quite frequent1y in dogs and horses. Comparative study of this arrhythmia may contribute to better understanding of the pathophysiologica1 mechanisms involved. In this study, we present a quantitative

  10. Quinidine-induced ventricular flutter and fibrillation without digitalis therapy

    NARCIS (Netherlands)

    Koster, R. W.; Wellens, H. J.

    1976-01-01

    Three cases are described with documented ventricular flutter and fibrillation during quinidine medication without concomitant digitalis therapy. In all three patients the arrhythmia developed while they were receiving moderate doses of quinidine. Although no changes in QRS width were observed after

  11. Managing atrial fibrillation in the elderly: critical appraisal of dronedarone

    Directory of Open Access Journals (Sweden)

    Trigo P

    2011-12-01

    Full Text Available Paula Trigo, Gregory W FischerDepartment of Anesthesiology, Mount Sinai School of Medicine, New York, NY, USAAbstract: Atrial fibrillation is the most commonly seen arrhythmia in the geriatric population and is associated with increased cardiovascular morbidity and mortality. Treatment of the elderly with atrial fibrillation remains challenging for physicians, because this unique subpopulation is characterized by multiple comorbidities requiring chronic use of numerous medications, which can potentially lead to severe drug interactions. Furthermore, age-related changes in the cardiovascular system as well as other physiological changes result in altered drug pharmacokinetics. Dronedarone is a new drug recently approved for the treatment of arrhythmias, such as atrial fibrillation and/or atrial flutter. Dronedarone is a benzofuran amiodarone analog which lacks the iodine moiety and contains a methane sulfonyl group that decreases its lipophilicity. These differences in chemical structure are responsible for making dronedarone less toxic than amiodarone which, in turn, results in fewer side effects. Adverse events for dronedarone include gastrointestinal side effects and rash. No dosage adjustments are required for patients with renal impairment. However, the use of dronedarone is contraindicated in the presence of severe hepatic dysfunction.Keywords: atrial fibrillation, elderly, antiarrhythmic agents, amiodarone, dronedarone

  12. Amyloid fibril systems reduce, stabilize and deliver bioavailable nanosized iron

    Science.gov (United States)

    Shen, Yi; Posavec, Lidija; Bolisetty, Sreenath; Hilty, Florentine M.; Nyström, Gustav; Kohlbrecher, Joachim; Hilbe, Monika; Rossi, Antonella; Baumgartner, Jeannine; Zimmermann, Michael B.; Mezzenga, Raffaele

    2017-07-01

    Iron-deficiency anaemia (IDA) is a major global public health problem. A sustainable and cost-effective strategy to reduce IDA is iron fortification of foods, but the most bioavailable fortificants cause adverse organoleptic changes in foods. Iron nanoparticles are a promising solution in food matrices, although their tendency to oxidize and rapidly aggregate in solution severely limits their use in fortification. Amyloid fibrils are protein aggregates initially known for their association with neurodegenerative disorders, but recently described in the context of biological functions in living organisms and emerging as unique biomaterial building blocks. Here, we show an original application for these protein fibrils as efficient carriers for iron fortification. We use biodegradable amyloid fibrils from β-lactoglobulin, an inexpensive milk protein with natural reducing effects, as anti-oxidizing nanocarriers and colloidal stabilizers for iron nanoparticles. The resulting hybrid material forms a stable protein-iron colloidal dispersion that undergoes rapid dissolution and releases iron ions during acidic and enzymatic in vitro digestion. Importantly, this hybrid shows high in vivo iron bioavailability, equivalent to ferrous sulfate in haemoglobin-repletion and stable-isotope studies in rats, but with reduced organoleptic changes in foods. Feeding the rats with these hybrid materials did not result in abnormal iron accumulation in any organs, or changes in whole blood glutathione concentrations, inferring their primary safety. Therefore, these iron-amyloid fibril hybrids emerge as novel, highly effective delivery systems for iron in both solid and liquid matrices.

  13. Antithrombotic therapy in atrial fibrillation associated with valvular heart disease

    DEFF Research Database (Denmark)

    Lip, Gregory Y H; Collet, Jean Philippe; Caterina, Raffaele de

    2017-01-01

    Atrial fibrillation (AF) is a major worldwide public health problem, and AF in association with valvular heart disease (VHD) is also common. However, management strategies for this group of patients have been less informed by randomized trials, which have largely focused on 'non-valvular AF' pati...

  14. Edoxaban versus warfarin in patients with atrial fibrillation

    NARCIS (Netherlands)

    Giugliano, R.P.; Ruff, C.T.; Braunwald, E.; Murphy, S.A.; Wiviott, S.D.; Halperin, J.L.; Waldo, A.L.; Ezekowitz, M.D.; Weitz, J.I.; Spinar, J.; Ruzyllo, W.; Ruda, M.; Koretsune, Y.; Betcher, J.; Shi, M.; Grip, L.T.; Patel, S.P.; Patel, I.; Hanyok, J.J.; Mercuri, M.; Antman, E.M.; Verheugt, F.W.A.; et al.,

    2013-01-01

    BACKGROUND: Edoxaban is a direct oral factor Xa inhibitor with proven antithrombotic effects. The long-term efficacy and safety of edoxaban as compared with warfarin in patients with atrial fibrillation is not known. METHODS: We conducted a randomized, double-blind, double-dummy trial comparing two

  15. Edoxaban versus Warfarin in Patients with Atrial Fibrillation

    NARCIS (Netherlands)

    Giugliano, Robert P.; Ruff, Christian T.; Braunwald, Eugene; Murphy, Sabina A.; Wiviott, Stephen D.; Halperin, Jonathan L.; Waldo, Albert L.; Ezekowitz, Michael D.; Weitz, Jeffrey I.; Špinar, Jindřich; Ruzyllo, Witold; Ruda, Mikhail; Koretsune, Yukihiro; Betcher, Joshua; Shi, Minggao; Grip, Laura T.; Patel, Shirali P.; Patel, Indravadan; Hanyok, James J.; Mercuri, Michele; Antman, Elliott M.; Braunwald, E.; Antman, E. M.; Giugliano, R. P.; Ruff, C. T.; Morin, S. E.; Hoffman, E. B.; Murphy, S. A.; Deenadayalu, N.; Grip, L.; Mercuri, M.; Lanz, H.; Patel, I.; Curt, V.; Duggal, A.; Hanyok, J.; Davé, J.; Morgan, D.; Choi, Y.; Shi, M.; Jin, J.; Xie, J.; Crerand, W.; Kappelhof, J.; Maxwell, W.; Zhang, X.; Zhang, Z.; de Groot, J. [=Joris R.; de Vos, R.; Hoekstra, J.

    2013-01-01

    BackgroundEdoxaban is a direct oral factor Xa inhibitor with proven antithrombotic effects. The long-term efficacy and safety of edoxaban as compared with warfarin in patients with atrial fibrillation is not known. MethodsWe conducted a randomized, double-blind, double-dummy trial comparing two

  16. Atrial fibrillation in patients with sick sinus syndrome

    DEFF Research Database (Denmark)

    Nielsen, Jens Cosedis; Thomsen, Poul Erik B; Højberg, Søren

    2012-01-01

    between minimal-paced programmed AVI = 100 and >100 ms (median value), respectively (P= 0.60).ConclusionsThe present study indicates that a longer baseline PQ-interval is associated with an increased risk of AF in patients with sick sinus syndrome. Atrial fibrillation burden is not associated...

  17. Management and prognosis of atrial fibrillation in diabetic patients

    DEFF Research Database (Denmark)

    Fumagalli, Stefano; Said, Salah A; Laroche, Cecile

    2017-01-01

    Aims: Diabetes mellitus (DM) is one of the most important cardiovascular (CV) risk factors. The aim of this study was to evaluate clinical correlates of DM, including management and outcomes, in the EURObservational Research Programme (EORP) - Atrial Fibrillation (AF) General Pilot (EORP-AF) Regi...

  18. Surgical Ablation of Atrial Fibrillation Using Energy Sources.

    Science.gov (United States)

    Brick, Alexandre Visconti; Braile, Domingo Marcolino

    2015-01-01

    Surgical ablation, concomitant with other operations, is an option for treatment in patients with chronic atrial fibrillation. The aim of this study is to present a literature review on surgical ablation of atrial fibrillation in patients undergoing cardiac surgery, considering energy sources and return to sinus rhythm. A comprehensive survey was performed in the literature on surgical ablation of atrial fibrillation considering energy sources, sample size, study type, outcome (early and late), and return to sinus rhythm. Analyzing studies with immediate results (n=5), the percentage of return to sinus rhythm ranged from 73% to 96%, while those with long-term results (n=20) (from 12 months on) ranged from 62% to 97.7%. In both of them, there was subsequent clinical improvement of patients who underwent ablation, regardless of the energy source used. Surgical ablation of atrial fibrillation is essential for the treatment of this arrhythmia. With current technology, it may be minimally invasive, making it mandatory to perform a procedure in an attempt to revert to sinus rhythm in patients requiring heart surgery.

  19. Role of the Atrioventricular Node in Atrial Fibrillation

    NARCIS (Netherlands)

    Meijler, F.L.; Wittkampf, F.H.M.

    1997-01-01

    Atrial fibrillation (AF) is probably the most cornmon cardiac arrhythmia in humans, particularly in the elderly (1-3). The irregularity and inequality of the he art beat first described by Hering in 1903 were, and continue to be, the landmark of the clinical diagnosis of AF (4,5). Sir Thomas

  20. A roadmap to improve the quality of atrial fibrillation management

    DEFF Research Database (Denmark)

    Kirchhof, Paulus; Breithardt, Günter; Bax, Jeroen

    2016-01-01

    . Hence, there are important unmet clinical and research needs in the evaluation and management of AF patients. The ensuing needs and opportunities for improving the quality of AF care were discussed during the fifth Atrial Fibrillation Network/European Heart Rhythm Association consensus conference...

  1. Effect of environmental factors on the kinetics of insulin fibril formation: elucidation of the molecular mechanism.

    Science.gov (United States)

    Nielsen, L; Khurana, R; Coats, A; Frokjaer, S; Brange, J; Vyas, S; Uversky, V N; Fink, A L

    2001-05-22

    In the search for the molecular mechanism of insulin fibrillation, the kinetics of insulin fibril formation were studied under different conditions using the fluorescent dye thioflavin T (ThT). The effect of insulin concentration, agitation, pH, ionic strength, anions, seeding, and addition of 1-anilinonaphthalene-8-sulfonic acid (ANS), urea, TMAO, sucrose, and ThT on the kinetics of fibrillation was investigated. The kinetics of the fibrillation process could be described by the lag time for formation of stable nuclei (nucleation) and the apparent rate constant for the growth of fibrils (elongation). The addition of seeds eliminated the lag phase. An increase in insulin concentration resulted in shorter lag times and faster growth of fibrils. Shorter lag times and faster growth of fibrils were seen at acidic pH versus neutral pH, whereas an increase in ionic strength resulted in shorter lag times and slower growth of fibrils. There was no clear correlation between the rate of fibril elongation and ionic strength. Agitation during fibril formation attenuated the effects of insulin concentration and ionic strength on both lag times and fibril growth. The addition of ANS increased the lag time and decreased the apparent growth rate for insulin fibril formation. The ANS-induced inhibition appears to reflect the formation of amorphous aggregates. The denaturant, urea, decreased the lag time, whereas the stabilizers, trimethylamine N-oxide dihydrate (TMAO) and sucrose, increased the lag times. The results indicated that both nucleation and fibril growth were controlled by hydrophobic and electrostatic interactions. A kinetic model, involving the association of monomeric partially folded intermediates, whose concentration is stimulated by the air-water interface, leading to formation of the critical nucleus and thence fibrils, is proposed.

  2. Albumin fibrillization induces apoptosis via integrin/FAK/Akt pathway

    Directory of Open Access Journals (Sweden)

    Liang Chi-Ming

    2009-01-01

    Full Text Available Abstract Background Numerous proteins can be converted to amyloid-like fibrils to increase cytotoxicity and induce apoptosis, but the methods generally require a high concentration of protein, vigorous shaking, or fibril seed. As well, the detailed mechanism of the cytotoxic effects is not well characterized. In this study, we have developed a novel process to convert native proteins into the fibrillar form. We used globular bovine serum albumin (BSA as a model protein to verify the properties of the fibrillar protein, investigated its cellular effects and studied the signaling cascade induced by the fibrillar protein. Results We induced BSA, a non-cytotoxic globular protein, to become fibril by a novel process involving Superdex-200 column chromatography in the presence of anionic or zwittergenic detergent(s. The column pore size was more important than column matrix composite in fibril formation. The fibrillar BSA induced apoptosis in BHK-21 cell as well as breast cancer cell line T47D. Pre-treating cells with anti-integrin antibodies blocked the apoptotic effect. Fibrillar BSA, but not globular BSA, bound to integrin, dephosphorylated focal adhesion kinase (FAK, Akt and glycogen synthase kinase-3β (GSK-3β. Conclusion We report on a novel process for converting globular proteins into fibrillar form to cause apoptosis by modulating the integrin/FAK/Akt/GSK-3β/caspase-3 signaling pathway. Our findings may be useful for understanding the pathogenesis of amyloid-like fibrils and applicable for the development of better therapeutic agents that target the underlying mechanism(s of the etiologic agents.

  3. Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers

    Directory of Open Access Journals (Sweden)

    Rasool Suhail

    2007-09-01

    Full Text Available Abstract Background Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD, amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Aβ and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. Results We immunized rabbits with a morphologically homogeneous population of Aβ42 fibrils. The resulting immune serum (OC specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 × G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type

  4. Familial clustering of atrial fibrillation and comparative longitudinal outcomes of familial and non-familial atrial fibrillation

    DEFF Research Database (Denmark)

    Gundlund, Anna; Olesen, Jonas B.; Peterson, Eric D.

    2017-01-01

    Several studies have suggested that family history of atrial fibrillation (AF) is an important risk factor for AF, with several specific genetic regions now implicated through Genome Wide Association Studies. In addition, familial AF is associated with earlier age of onset and affects patients...

  5. Cost-effectiveness of a specialized atrial fibrillation clinic vs. usual care in patients with atrial fibrillation

    NARCIS (Netherlands)

    Hendriks, Jeroen; Tomini, Florian; van Asselt, Thea; Crijns, Harry; Vrijhoef, Hubertus

    AIMS: A recent randomized controlled trial demonstrated significant reductions in cardiovascular hospitalizations and deaths with a nurse-led integrated chronic care approach in patients with atrial fibrillation (AF) compared with usual care. The aim of the present study is to assess

  6. Cost-effectiveness of a specialized atrial fibrillation clinic vs. usual care in patients with atrial fibrillation

    NARCIS (Netherlands)

    Hendriks, J.M.L.; Tomini, F.; van Asselt, A.D.I.; Crijns, H.J.G.M.; Vrijhoef, H.J.M.

    2013-01-01

    Aims A recent randomized controlled trial demonstrated significant reductions in cardiovascular hospitalizations and deaths with a nurse-led integrated chronic care approach in patients with atrial fibrillation (AF) compared with usual care. The aim of the present study is to assess

  7. Early recurrences of atrial fibrillation after electrical cardioversion : A result of fibrillation-induced electrical remodeling of the atria?

    NARCIS (Netherlands)

    Tieleman, RG; Van Gelder, IC; Crijns, HJGM; De Kam, PJ; Van den Berg, MP; Haaksma, J; Van der Woude, HJ; Allessie, MA

    Objectives, We sought to investigate whether, in humans, the timing and incidence of a relapse of atrial fibrillation (AF) during the first month after cardioversion indicates the presence of electrical remodeling and whether this could be influenced by prevention of intracellular calcium overload

  8. Model Driven Engineering

    Science.gov (United States)

    Gaševic, Dragan; Djuric, Dragan; Devedžic, Vladan

    A relevant initiative from the software engineering community called Model Driven Engineering (MDE) is being developed in parallel with the Semantic Web (Mellor et al. 2003a). The MDE approach to software development suggests that one should first develop a model of the system under study, which is then transformed into the real thing (i.e., an executable software entity). The most important research initiative in this area is the Model Driven Architecture (MDA), which is Model Driven Architecture being developed under the umbrella of the Object Management Group (OMG). This chapter describes the basic concepts of this software engineering effort.

  9. Structural and functional characteristics of myocard in patients with different forms of atrial fibrillation

    Directory of Open Access Journals (Sweden)

    L. I. Vasilyeva

    2015-02-01

    Full Text Available Aim. To study structural and functional characteristics of myocard in patients with different forms of atrial fibrillation. Atrial fibrillation is the most prevalent arrhythmia in clinical practice. Atrial fibrillation is a progressive disease: the duration of paroxysms increases over time and paroxysmal atrial fibrillation transforms to persistent, the last one becomes refractory to pharmacological and electrical cardioversion in time and transforms to permanent. So assessment of myocardial remodeling in patients with persistent and permanent atrial fibrillation is very actual. Methods and results. According to the aim of the study 133 patients with persistent atrial fibrillation and 100 patients with permanent atrial fibrillation were included into the study. Echocardiographic parameters of left and right atria function were studied. Conclusion. It was found that patients with persistent and permanent atrial fibrillation are characterized with both left and right atrias remodeling. Remodeling of the atrias is less pronounced in patients with permanent atrial fibrillation in comparison with persistent atrial fibrillation patients and arrhythmia recurrence.

  10. Structural evaluation of an amyloid fibril model using small-angle x-ray scattering

    Science.gov (United States)

    Dahal, Eshan; Choi, Mina; Alam, Nadia; Bhirde, Ashwinkumar A.; Beaucage, Serge L.; Badano, Aldo

    2017-08-01

    Amyloid fibrils are highly structured protein aggregates associated with a wide range of diseases including Alzheimer’s and Parkinson’s. We report a structural investigation of an amyloid fibril model prepared from a commonly used plasma protein (bovine serum albumin (BSA)) using small-angle x-ray scattering (SAXS) technique. As a reference, the size estimates from SAXS are compared to dynamic light scattering (DLS) data and the presence of amyloid-like fibrils is confirmed using Congo red absorbance assay. Our SAXS results consistently show the structural transformation of BSA from spheroid to rod-like elongated structures during the fibril formation process. We observe the elongation of fibrils over two months with fibril length growing from 35.9  ±  3.0 nm to 51.5  ±  2.1 nm. Structurally metastable fibrils with distinct SAXS profiles have been identified. As proof of concept, we demonstrate the use of such distinct SAXS profiles to detect fibrils in the mixture solutions of two species by estimating their volume fractions. This easily detectable and well-characterized amyloid fibril model from BSA can be readily used as a control or standard reference to further investigate SAXS applications in the detection of structurally diverse amyloid fibrils associated with protein aggregation diseases.

  11. Phosphate and HEPES buffers potently affect the fibrillation and oligomerization mechanism of Alzheimer's Aβ peptide

    International Nuclear Information System (INIS)

    Garvey, Megan; Tepper, Katharina; Haupt, Caroline; Knuepfer, Uwe; Klement, Karolin; Meinhardt, Jessica; Horn, Uwe; Balbach, Jochen; Faendrich, Marcus

    2011-01-01

    Highlights: → Sodium phosphate buffer accelerated Aβ(1-40) nucleation relative to HEPES. → Aβ(1-40) fibrils formed in the two buffers show only minor structural differences. → NMR revealed that Aβ(1-40) histidine residues mediate buffer dependent changes. -- Abstract: The oligomerization of Aβ peptide into amyloid fibrils is a hallmark of Alzheimer's disease. Due to its biological relevance, phosphate is the most commonly used buffer system for studying the formation of Aβ and other amyloid fibrils. Investigation into the characteristics and formation of amyloid fibrils frequently relies upon material formed in vitro, predominantly in phosphate buffers. Herein, we examine the effects on the fibrillation and oligomerization mechanism of Aβ peptide that occur due solely to the influence of phosphate buffer. We reveal that significant differences in amyloid fibrillation are observed due to fibrillation being initiated in phosphate or HEPES buffer (at physiological pH and temperature). Except for the differing buffer ions, all experimental parameters were kept constant. Fibril formation was assessed using fluorescently monitored kinetic studies, microscopy, X-ray fiber diffraction and infrared and nuclear magnetic resonance spectroscopies. Based on this set up, we herein reveal profound effects on the mechanism and speed of Aβ fibrillation. The three histidine residues at positions 6, 13 and 14 of Aβ(1-40) are instrumental in these mechanistic changes. We conclude that buffer plays a more significant role in fibril formation than has been generally acknowledged.

  12. Discovery Driven Growth

    DEFF Research Database (Denmark)

    Bukh, Per Nikolaj

    2009-01-01

    Anmeldelse af Discovery Driven Growh : A breakthrough process to reduce risk and seize opportunity, af Rita G. McGrath & Ian C. MacMillan, Boston: Harvard Business Press. Udgivelsesdato: 14 august......Anmeldelse af Discovery Driven Growh : A breakthrough process to reduce risk and seize opportunity, af Rita G. McGrath & Ian C. MacMillan, Boston: Harvard Business Press. Udgivelsesdato: 14 august...

  13. Changes in plasma atrial natriuretic factor in patients with idiopathic atrial fibrillation

    International Nuclear Information System (INIS)

    Du Tongxin; Xia Xiaojie; Qu Wei; Wang Shukui; Sun Junjiang

    2002-01-01

    To observe the changes in plasma atrial natriuretic factor (AFN) in patients with idiopathic atrial fibrillation and investigate its mechanism, plasma ANF, platelet count and hematocrit were detected in 21 cases with transient idiopathic atrial fibrillation (group A, A1 representing attack, while A2 termination), 28 with persistent idiopathic atrial fibrillation (group B), 27 suffered from rheumatic heart disease with mitral stenosis and persistent atrial fibrillation (group C), 32 with transient supraventricular tachycardia (group D) and 20 normal controls (group E). It was found that the level of ANF was significantly higher in patients with attacking transient idiopathic atrial fibrillation than that in group A2, D and E (P 0.05), while there was significant difference in hematocrit in group A1 compared with group A2, D, E (P < 0.01). It suggested that ANF and hematocrit play an important role in the attack of idiopathic atrial fibrillation

  14. Synergistic Inhibition of Protein Fibrillation by Proline and Sorbitol: Biophysical Investigations.

    Directory of Open Access Journals (Sweden)

    Sinjan Choudhary

    Full Text Available We report here interesting synergistic effects of proline and sorbitol, two well-known chemical chaperones, in the inhibition of fibrillation of two proteins, insulin and lysozyme. A combination of many biophysical techniques has been used to understand the structural morphology and modes of interaction of the chaperones with the proteins during fibrillation. Both the chaperones establish stronger polar interactions in the elongation and saturation stages of fibrillation compared to that in the native stage. However, when presented as a mixture, we also see contribution of hydrophobic interactions. Thus, a co-operative adjustment of polar and hydrophobic interactions between the chaperones and the protein surface seems to drive the synergistic effects in the fibrillation process. In insulin, this synergy is quantitatively similar in all the stages of the fibrillation process. These observations would have significant implications for understanding protein folding concepts, in general, and for designing combination therapies against protein fibrillation, in particular.

  15. Synergistic Inhibition of Protein Fibrillation by Proline and Sorbitol: Biophysical Investigations.

    Science.gov (United States)

    Choudhary, Sinjan; Save, Shreyada N; Kishore, Nand; Hosur, Ramakrishna V

    2016-01-01

    We report here interesting synergistic effects of proline and sorbitol, two well-known chemical chaperones, in the inhibition of fibrillation of two proteins, insulin and lysozyme. A combination of many biophysical techniques has been used to understand the structural morphology and modes of interaction of the chaperones with the proteins during fibrillation. Both the chaperones establish stronger polar interactions in the elongation and saturation stages of fibrillation compared to that in the native stage. However, when presented as a mixture, we also see contribution of hydrophobic interactions. Thus, a co-operative adjustment of polar and hydrophobic interactions between the chaperones and the protein surface seems to drive the synergistic effects in the fibrillation process. In insulin, this synergy is quantitatively similar in all the stages of the fibrillation process. These observations would have significant implications for understanding protein folding concepts, in general, and for designing combination therapies against protein fibrillation, in particular.

  16. Does in-hospital ventricular fibrillation affect prognosis after myocardial infarction?

    DEFF Research Database (Denmark)

    Jensen, G V; Torp-Pedersen, C; Hildebrandt, P

    1997-01-01

    with ventricular fibrillation in time intervals, indicated that the importance of ventricular fibrillation for risk of death was exhausted during the initial 60 days after infarction. CONCLUSION: Ventricular fibrillation is associated with an independent increased risk of death within 0-60 days after infarction......AIM: The aim of this study was to estimate the prognostic information to be gained from ventricular fibrillation in patients with myocardial infarction. METHODS AND RESULTS: We studied 4259 consecutive patients with myocardial infarction admitted to one centre in 1977-1988. Five hundred and twenty......-eight (12.4%) of the patients had ventricular fibrillation in hospital. The following risk factors were included in multivariate models to estimate their importance for 30-day and long-term (median 7 year) prognosis: age, gender, ventricular fibrillation, congestive heart failure, pulmonary oedema...

  17. Decision-making interventions to stop the global atrial fibrillation-related stroke tsunami.

    Science.gov (United States)

    Cerasuolo, Joshua O; Montero-Odasso, Manuel; Ibañez, Agustin; Doocy, Shannon; Lip, Gregory Yh; Sposato, Luciano A

    2017-04-01

    Atrial fibrillation affects 33.5 million people worldwide and its prevalence is expected to double by 2050 because of the aging population. Atrial fibrillation confers a 5-fold higher risk of ischemic stroke compared to sinus rhythm. We present our view of the role of shared medical decision-making to combat global underutilization of oral anticoagulation for stroke prevention in atrial fibrillation patients. Oral anticoagulation underuse is widespread as it is present within atrial fibrillation patients of all risk strata and in countries across all income levels. Reasons for oral anticoagulation underuse include but are probably not limited to poor risk stratification, over-interpretation of contraindications, and discordance between physician prescription preferences and actual administration. By comparing a catastrophic event to the consequences of atrial fibrillation related strokes, it may help physicians and patients understand the negative outcomes associated with oral anticoagulation under-utilization and the magnitude to which oral anticoagulations neutralize atrial fibrillation burden.

  18. Novel squarylium dyes for detection of amyloid fibrils in vitro

    Directory of Open Access Journals (Sweden)

    K. O. Vus

    2015-04-01

    Full Text Available A series of novel symmetrical and asymmetrical squarylium dyes with the different substituents in the donor moieties have been tested for their ability to detect and characterize insulin and lysozyme amyloid fibrils prepared in acidic buffer at elevated temperature. The dye-protein binding parameters were estimated in terms of the one-site Langmuir adsorption model using the data of direct and reverse fluorimetric titrations. By comparing the dye quantum yields, binding affinities, and extents of the fluorescence enhancement in the protein-bound state, G6 and G7 were selected as the most prospective amyloid tracers. Furthermore, these probes provided evidence for the lower polarity of the lysozyme fibrillar grooves compared to insulin aggregates. The novel dyes G6 and G7 were recommended for amyloid fibril detection and characterization in the near-infrared region.

  19. Dynamical mechanism of atrial fibrillation: A topological approach

    Science.gov (United States)

    Marcotte, Christopher D.; Grigoriev, Roman O.

    2017-09-01

    While spiral wave breakup has been implicated in the emergence of atrial fibrillation, its role in maintaining this complex type of cardiac arrhythmia is less clear. We used the Karma model of cardiac excitation to investigate the dynamical mechanisms that sustain atrial fibrillation once it has been established. The results of our numerical study show that spatiotemporally chaotic dynamics in this regime can be described as a dynamical equilibrium between topologically distinct types of transitions that increase or decrease the number of wavelets, in general agreement with the multiple wavelets' hypothesis. Surprisingly, we found that the process of continuous excitation waves breaking up into discontinuous pieces plays no role whatsoever in maintaining spatiotemporal complexity. Instead, this complexity is maintained as a dynamical balance between wave coalescence—a unique, previously unidentified, topological process that increases the number of wavelets—and wave collapse—a different topological process that decreases their number.

  20. Unexpected guest: Atrial fibrillation due to electrical shock

    Directory of Open Access Journals (Sweden)

    Mehmet Zihni Bilik

    2016-03-01

    Full Text Available Cardiac arrhythmias due to electrical injuries are rare among emergency service admittances. A 35 year-old female patient was admitted to emergency service with palpitation after electrical injury as a result of contact with a domestic low-voltage source. Electrocardiography (ECG showed atrial fibrillation with rapid ventricular response. Transthoracic echocardiography findings were normal. Atrial fibrillation spontaneously converted to normal sinus rhythm after rate limiting treatment with beta-blocker. The patient was discharged without any complication on the third day of hospitalization. Although cardiac arrhythmias rarely occur after electrical injury, cardiac monitoring is recommended for all patients with documented rhythm disorder, loss of consciousness, or abnormal ECG at admission.

  1. Atrial fibrillation in fracture patients treated with oral bisphosphonates

    DEFF Research Database (Denmark)

    Abrahamsen, B; Eiken, P; Brixen, K

    2009-01-01

    OBJECTIVES: To determine if patients receiving oral bisphosphonates are at excess risk of atrial fibrillation (AF), stroke and myocardial infarction. DESIGN: Register-based restricted cohort study. SETTING: National Hospital Discharge Register and National Prescriptions Database (1995-2005). SUBJ......OBJECTIVES: To determine if patients receiving oral bisphosphonates are at excess risk of atrial fibrillation (AF), stroke and myocardial infarction. DESIGN: Register-based restricted cohort study. SETTING: National Hospital Discharge Register and National Prescriptions Database (1995...... to adherence. There was no increased risk of ischaemic stroke and an increased risk of myocardial infarction was not significant after adjustment for comorbidity. CONCLUSIONS: The increased occurrence of AF in fracture patients who are users of oral bisphosphonates should be attributed to targeting...

  2. Paroxysmal atrial fibrillation occurs often in cryptogenic ischaemic stroke

    DEFF Research Database (Denmark)

    Christensen, L M; Krieger, D W; Højberg, S

    2014-01-01

    BACKGROUND AND PURPOSE: Atrial fibrillation (AF) increases the risk of stroke fourfold and is associated with a poor clinical outcome. Despite work-up in compliance with guidelines, up to one-third of patients have cryptogenic stroke (CS). The prevalence of asymptomatic paroxysmal atrial fibrilla......BACKGROUND AND PURPOSE: Atrial fibrillation (AF) increases the risk of stroke fourfold and is associated with a poor clinical outcome. Despite work-up in compliance with guidelines, up to one-third of patients have cryptogenic stroke (CS). The prevalence of asymptomatic paroxysmal atrial...... lasting predominantly between 1 and 4 h. Four recurrent strokes were observed, three in patients with PAF; all three patients were on oral anticoagulation (OAC). CONCLUSIONS: One in five patients with CS had PAF, which occurred at low burden and long after stroke. Future studies should determine the role...

  3. [Atrial fibrillation as consequence and cause of structural changes of atria].

    Science.gov (United States)

    Aparina, O P; Chikhireva, L N; Stukalova, O V; Mironova, N A; Kashtanova, S Iu; Ternovoĭ, S K; Golitsyn, S P

    2014-01-01

    Changes of atrial structure and function are the contributors of atrial fibrillation clinical course, complications and treatment effectiveness. Effects of inflammation and mechanical stretch on atrial structural remodeling leading to atrial fibrillation are reviewed in the article. Contemporary invasive and non-invasive methods of evaluation (including late gadolinium enhancement magnetic resonance imaging) of patients with atrial structural remodeling in atrial fibrillation are also described.

  4. Is Supramolecular Filament Chirality the Underlying Cause of Major Morphology Differences in Amyloid Fibrils?

    Science.gov (United States)

    2015-01-01

    The unique enhanced sensitivity of vibrational circular dichroism (VCD) to the formation and development of amyloid fibrils in solution is extended to four additional fibril-forming proteins or peptides where it is shown that the sign of the fibril VCD pattern correlates with the sense of supramolecular filament chirality and, without exception, to the dominant fibril morphology as observed in AFM or SEM images. Previously for insulin, it has been demonstrated that the sign of the VCD band pattern from filament chirality can be controlled by adjusting the pH of the incubating solution, above pH 2 for “normal” left-hand-helical filaments and below pH 2 for “reversed” right-hand-helical filaments. From AFM or SEM images, left-helical filaments form multifilament braids of left-twisted fibrils while the right-helical filaments form parallel filament rows of fibrils with a flat tape-like morphology, the two major classes of fibril morphology that from deep UV resonance Raman scattering exhibit the same cross-β-core secondary structure. Here we investigate whether fibril supramolecular chirality is the underlying cause of the major morphology differences in all amyloid fibrils by showing that the morphology (twisted versus flat) of fibrils of lysozyme, apo-α-lactalbumin, HET-s (218–289) prion, and a short polypeptide fragment of transthyretin, TTR (105–115), directly correlates to their supramolecular chirality as revealed by VCD. The result is strong evidence that the chiral supramolecular organization of filaments is the principal underlying cause of the morphological heterogeneity of amyloid fibrils. Because fibril morphology is linked to cell toxicity, the chirality of amyloid aggregates should be explored in the widely used in vitro models of amyloid-associated diseases. PMID:24484302

  5. Is supramolecular filament chirality the underlying cause of major morphology differences in amyloid fibrils?

    Science.gov (United States)

    Kurouski, Dmitry; Lu, Xuefang; Popova, Ludmila; Wan, William; Shanmugasundaram, Maruda; Stubbs, Gerald; Dukor, Rina K; Lednev, Igor K; Nafie, Laurence A

    2014-02-12

    The unique enhanced sensitivity of vibrational circular dichroism (VCD) to the formation and development of amyloid fibrils in solution is extended to four additional fibril-forming proteins or peptides where it is shown that the sign of the fibril VCD pattern correlates with the sense of supramolecular filament chirality and, without exception, to the dominant fibril morphology as observed in AFM or SEM images. Previously for insulin, it has been demonstrated that the sign of the VCD band pattern from filament chirality can be controlled by adjusting the pH of the incubating solution, above pH 2 for "normal" left-hand-helical filaments and below pH 2 for "reversed" right-hand-helical filaments. From AFM or SEM images, left-helical filaments form multifilament braids of left-twisted fibrils while the right-helical filaments form parallel filament rows of fibrils with a flat tape-like morphology, the two major classes of fibril morphology that from deep UV resonance Raman scattering exhibit the same cross-β-core secondary structure. Here we investigate whether fibril supramolecular chirality is the underlying cause of the major morphology differences in all amyloid fibrils by showing that the morphology (twisted versus flat) of fibrils of lysozyme, apo-α-lactalbumin, HET-s (218-289) prion, and a short polypeptide fragment of transthyretin, TTR (105-115), directly correlates to their supramolecular chirality as revealed by VCD. The result is strong evidence that the chiral supramolecular organization of filaments is the principal underlying cause of the morphological heterogeneity of amyloid fibrils. Because fibril morphology is linked to cell toxicity, the chirality of amyloid aggregates should be explored in the widely used in vitro models of amyloid-associated diseases.

  6. Cardiac ion channels and mechanisms for protection against atrial fibrillation

    DEFF Research Database (Denmark)

    Grunnet, Morten; Bentzen, Bo Hjorth; Sørensen, Ulrik S

    2011-01-01

    Atrial fibrillation (AF) is recognised as the most common sustained cardiac arrhythmia in clinical practice. Ongoing drug development is aiming at obtaining atrial specific effects in order to prevent pro-arrhythmic, devastating ventricular effects. In principle, this is possible due to a differe...... to the recent discovery that Ca(2+)-activated small conductance K(+) channels (SK channels) are important for the repolarisation of atrial action potentials. Finally, an overview of current pharmacological treatment of AF is included....

  7. Slow ventricular response atrial fibrillation related to mad honey poisoning

    Science.gov (United States)

    Osken, A.; Yaylacı, S.; Aydın, E.; Kocayigit, İ; Cakar, M.A.; Tamer, A.; Gündüz, H.

    2012-01-01

    Mad honey poisoning which is induced by Grayanotoxin (Andromedotoxin), is also known to have adverse effects in the cardiovascular system leading to different clinical entities. This toxin is produced by a member of the Rhododendron genus of plants of two R. Luteum and R. Panticum. In this article, we presented a case of slow ventricular response atrial fibrillation complaints with nausea, vomiting, dizziness and chest pain about an hour after eating honey produced in the Black Sea Region. PMID:22923947

  8. Slow ventricular response atrial fibrillation related to mad honey poisoning

    OpenAIRE

    Osken, A.; Yaylacı, S.; Aydın, E.; Kocayigit, İ; Cakar, M.A.; Tamer, A.; Gündüz, H.

    2012-01-01

    Mad honey poisoning which is induced by Grayanotoxin (Andromedotoxin), is also known to have adverse effects in the cardiovascular system leading to different clinical entities. This toxin is produced by a member of the Rhododendron genus of plants of two R. Luteum and R. Panticum. In this article, we presented a case of slow ventricular response atrial fibrillation complaints with nausea, vomiting, dizziness and chest pain about an hour after eating honey produced in the Black Sea Region.

  9. The Nucleation of Protein Aggregates - From Crystals to Amyloid Fibrils.

    Science.gov (United States)

    Buell, Alexander K

    2017-01-01

    The condensation and aggregation of individual protein molecules into dense insoluble phases is of relevance in such diverse fields as materials science, medicine, structural biology and pharmacology. A common feature of these condensation phenomena is that they usually are nucleated processes, i.e. the first piece of the condensed phase is energetically costly to create and hence forms slowly compared to its subsequent growth. Here we give a compact overview of the differences and similarities of various protein nucleation phenomena, their theoretical description in the framework of colloid and polymer science and their experimental study. Particular emphasis is put on the nucleation of a specific type of filamentous protein aggregates, amyloid fibrils. The current experimentally derived knowledge on amyloid fibril nucleation is critically assessed, and we argue that it is less advanced than is generally believed. This is due to (I) the lack of emphasis that has been put on the distinction between homogeneous and heterogeneous nucleation in experimental studies (II) the use of oversimplifying and/or inappropriate theoretical frameworks for the analysis of kinetic data of amyloid fibril nucleation. A strategy is outlined and advocated of how our understanding of this important class of processes can be improved in the future. © 2017 Elsevier Inc. All rights reserved.

  10. Imaging and quantification of amyloid fibrillation in the cell nucleus.

    Science.gov (United States)

    Arnhold, Florian; Scharf, Andrea; von Mikecz, Anna

    2015-01-01

    Xenobiotics, as well as intrinsic processes such as cellular aging, contribute to an environment that constantly challenges nuclear organization and function. While it becomes increasingly clear that proteasome-dependent proteolysis is a major player, the topology and molecular mechanisms of nuclear protein homeostasis remain largely unknown. We have shown previously that (1) proteasome-dependent protein degradation is organized in focal microenvironments throughout the nucleoplasm and (2) heavy metals as well as nanoparticles induce nuclear protein fibrillation with amyloid characteristics. Here, we describe methods to characterize the landscape of intranuclear amyloid on the global and local level in different systems such as cultures of mammalian cells and the soil nematode Caenorhabditis elegans. Application of discrete mathematics to imaging data is introduced as a tool to develop pattern recognition of intracellular protein fibrillation. Since stepwise fibrillation of otherwise soluble proteins to insoluble amyloid-like protein aggregates is a hallmark of neurodegenerative protein-misfolding disorders including Alzheimer's disease, CAG repeat diseases, and the prion encephalopathies, investigation of intracellular amyloid may likewise aid to a better understanding of the pathomechanisms involved. We consider aggregate profiling as an important experimental approach to determine if nuclear amyloid has toxic or protective roles in various disease processes.

  11. Artificial Intelligence Methods Applied to Parameter Detection of Atrial Fibrillation

    Science.gov (United States)

    Arotaritei, D.; Rotariu, C.

    2015-09-01

    In this paper we present a novel method to develop an atrial fibrillation (AF) based on statistical descriptors and hybrid neuro-fuzzy and crisp system. The inference of system produce rules of type if-then-else that care extracted to construct a binary decision system: normal of atrial fibrillation. We use TPR (Turning Point Ratio), SE (Shannon Entropy) and RMSSD (Root Mean Square of Successive Differences) along with a new descriptor, Teager- Kaiser energy, in order to improve the accuracy of detection. The descriptors are calculated over a sliding window that produce very large number of vectors (massive dataset) used by classifier. The length of window is a crisp descriptor meanwhile the rest of descriptors are interval-valued type. The parameters of hybrid system are adapted using Genetic Algorithm (GA) algorithm with fitness single objective target: highest values for sensibility and sensitivity. The rules are extracted and they are part of the decision system. The proposed method was tested using the Physionet MIT-BIH Atrial Fibrillation Database and the experimental results revealed a good accuracy of AF detection in terms of sensitivity and specificity (above 90%).

  12. Artificially modified collagen fibril orientation affects leather tear strength.

    Science.gov (United States)

    Kelly, Susyn J; Wells, Hannah C; Sizeland, Katie H; Kirby, Nigel; Edmonds, Richard L; Ryan, Tim; Hawley, Adrian; Mudie, Stephen; Haverkamp, Richard G

    2018-07-01

    Ovine leather has around half the tear strength of bovine leather and is therefore not suitable for high-value applications such as shoes. Tear strength has been correlated with the natural collagen fibril alignment (orientation index, OI). It is hypothesized that it could be possible to artificially increase the OI of the collagen fibrils and that an artificial increase in OI could increase tear strength. Ovine skins, after pickling and bating, were strained biaxially during chrome tanning. The strain ranged from 2 to 15% of the initial sample length, either uniformly in both directions by 10% or with 3% in one direction and 15% in the other. Once tanned, the leather tear strengths were measured and the collagen fibril orientation was measured using synchrotron-based small-angle X-ray scattering. The OI increased as a result of strain during tanning from 0.48 to 0.79 (P = 0.001) measured edge-on and the thickness-normalized tear strength increased from 27 to 43 N mm -1 (P leather was strained 10% in two orthogonal directions. This is evidence to support a causal relationship between high OI (measured edge-on), highly influenced by thickness, and tear strength. It also provides a method to produce stronger leather. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  13. Potent inhibition of tau fibrillization with a multivalent ligand

    International Nuclear Information System (INIS)

    Honson, Nicolette S.; Jensen, Jordan R.; Darby, Michael V.; Kuret, Jeff

    2007-01-01

    Small-molecule inhibitors of tau fibrillization are under investigation as tools for interrogating the tau aggregation pathway and as potential therapeutic agents for Alzheimer's disease. Established inhibitors include thiacarbocyanine dyes, which can inhibit recombinant tau fibrillization in the presence of anionic surfactant aggregation inducers. In an effort to increase inhibitory potency, a cyclic bis-thiacarbocyanine molecule containing two thiacarbocyanine moieties was synthesized and characterized with respect to tau fibrillization inhibitory activity by electron microscopy and ligand aggregation state by absorbance spectroscopy. Results showed that the inhibitory activity of the bis-thiacarbocyanine was qualitatively similar to a monomeric cyanine dye, but was more potent with 50% inhibition achieved at ∼80 nM concentration. At all concentrations tested in aqueous solution, the bis-thiacarbocyanine collapsed to form a closed clamshell structure. However, the presence of tau protein selectively stabilized the open conformation. These results suggest that the inhibitory activity of bis-thiacarbocyanine results from multivalency, and reveal a route to more potent tau aggregation inhibitors

  14. Maze Procedures for Atrial Fibrillation, From History to Practice.

    Science.gov (United States)

    Kik, Charles; Bogers, Ad J J C

    2011-10-01

    Atrial fibrillation may result in significant symptoms, (systemic) thrombo-embolism, as well as tachycardia-induced cardiomyopathy with cardiac failure, and consequently be associated with significant morbidity and mortality. Nowadays symptomatic atrial fibrillation can be treated with catheter-based ablation, surgical ablation or hybrid approaches. In this setting a fairly large number of surgical approaches and procedures are described and being practised. It should be clear that the Cox-maze procedure resulted from building up evidence and experience in different steps, while some of the present surgical approaches and techniques are being based only on technical feasibility with limited experience, rather than on a process of consequent methodology. Some of the issues still under debate are whether or not the maze procedure can be limited to the left atrium or even to isolation of the pulmonary veins or that bi-atrial procedures are indicated, whether or not cardiopulmonary bypass is to be applied and which route of exposure facilitates an optimal result. In addition, maze procedures are not procedures guide by electrophysiological mapping. At least in theory not in all patients all lesions of the maze procedures are necessary. A history and aspects of current practise in surgical treatment of atrial fibrillation is presented.

  15. Managing atrial fibrillation in the elderly: critical appraisal of dronedarone.

    Science.gov (United States)

    Trigo, Paula; Fischer, Gregory W

    2012-01-01

    Atrial fibrillation is the most commonly seen arrhythmia in the geriatric population and is associated with increased cardiovascular morbidity and mortality. Treatment of the elderly with atrial fibrillation remains challenging for physicians, because this unique subpopulation is characterized by multiple comorbidities requiring chronic use of numerous medications, which can potentially lead to severe drug interactions. Furthermore, age-related changes in the cardiovascular system as well as other physiological changes result in altered drug pharmacokinetics. Dronedarone is a new drug recently approved for the treatment of arrhythmias, such as atrial fibrillation and/or atrial flutter. Dronedarone is a benzofuran amiodarone analog which lacks the iodine moiety and contains a methane sulfonyl group that decreases its lipophilicity. These differences in chemical structure are responsible for making dronedarone less toxic than amiodarone which, in turn, results in fewer side effects. Adverse events for dronedarone include gastrointestinal side effects and rash. No dosage adjustments are required for patients with renal impairment. However, the use of dronedarone is contraindicated in the presence of severe hepatic dysfunction.

  16. Cost of illness of atrial fibrillation: a nationwide study of societal impact.

    Science.gov (United States)

    Johnsen, Søren Paaske; Dalby, Lene Worsaae; Täckström, Tomas; Olsen, Jens; Fraschke, Anina

    2017-11-10

    The prevalence of atrial fibrillation is increasing rapidly; however, to date, population-based data are lacking on the attributable cost of illness of atrial fibrillation from a societal perspective, including both direct and indirect costs. The study was an incidence-based cost-of-illness study based on national registries covering the entire population of Denmark. We identified all patients with a first-time hospital diagnosis of atrial fibrillation between 2001 and 2012. For every atrial fibrillation patient, we identified three age- and sex-matched controls from the general population. Both the total and the attributable costs of atrial fibrillation were estimated based on individual level information on hospital care (in- and out-patient contacts), primary sector care, use of prescription drugs and productivity loss. Average 3-year societal costs per patient attributable to atrial fibrillation were estimated to be €20,403-26,544 during the study period. The costs were highest during the first year after diagnosis of atrial fibrillation. Admission costs constituted the largest cost component, whereas primary sector costs and medicine costs only constituted minor components. The attributable costs were more than two-fold higher among patients experiencing a stroke. The total 3-year cost attributable to atrial fibrillation in Denmark was estimated to be €219-295 million. The societal costs attributable to atrial fibrillation are significant. Reducing the need for hospitalizations, in particular from stroke, is a key factor in controlling the costs.

  17. Iowa Mutant Apolipoprotein A-I (ApoA-IIowa) Fibrils Target Lysosomes.

    Science.gov (United States)

    Kameyama, Hirokazu; Nakajima, Hiroyuki; Nishitsuji, Kazuchika; Mikawa, Shiho; Uchimura, Kenji; Kobayashi, Norihiro; Okuhira, Keiichiro; Saito, Hiroyuki; Sakashita, Naomi

    2016-07-28

    The single amino acid mutation G26R in human apolipoprotein A-I (apoA-IIowa) is the first mutation that was associated with familial AApoA1 amyloidosis. The N-terminal fragments (amino acid residues 1-83) of apoA-I containing this mutation deposit as amyloid fibrils in patients' tissues and organs, but the mechanisms of cellular degradation and cytotoxicity have not yet been clarified. In this study, we demonstrated degradation of apoA-IIowa fibrils via the autophagy-lysosomal pathway in human embryonic kidney 293 cells. ApoA-IIowa fibrils induced an increase in lysosomal pH and the cytosolic release of the toxic lysosomal protease cathepsin B. The mitochondrial dysfunction caused by apoA-IIowa fibrils depended on cathepsin B and was ameliorated by increasing the degradation of apoA-IIowa fibrils. Thus, although apoA-IIowa fibril transport to lysosomes and fibril degradation in lysosomes may have occurred, the presence of an excess number of apoA-IIowa fibrils, more than the lysosomes could degrade, may be detrimental to cells. Our results thus provide evidence that the target of apoA-IIowa fibrils is lysosomes, and we thereby gained a novel insight into the mechanism of AApoA1 amyloidosis.

  18. Intraoperative Inducibility of Atrial Fibrillation Does Not Predict Early Postoperative Atrial Fibrillation.

    Science.gov (United States)

    Lanters, Eva A H; Teuwen, Christophe P; Yaksh, Ameeta; Kik, Charles; van der Does, Lisette J M E; Mouws, Elisabeth M J P; Knops, Paul; van Groningen, Nicole J; Hokken, Thijmen; Bogers, Ad J J C; de Groot, Natasja M S

    2018-03-10

    Early postoperative atrial fibrillation (EPoAF) is associated with thromboembolic events, prolonged hospitalization, and development of late PoAF (LPoAF). It is, however, unknown if EPoAF can be predicted by intraoperative AF inducibility. The aims of this study are therefore to explore (1) the value of intraoperative inducibility of AF for development of both EPoAF and LPoAF and (2) the predictive value of de novo EPoAF for recurrence of LPoAF. Patients (N=496, 75% male) undergoing cardiothoracic surgery for coronary and/or valvular heart disease were included. AF induction was attempted by atrial pacing, before extracorporeal circulation. All patients were on continuous rhythm monitoring until discharge to detect EPoAF. During a follow-up period of 2 years, LPoAF was detected by ECGs and Holter recordings. Sustained AF was inducible in 56% of patients. There was no difference in patients with or without AF before surgery ( P =0.159), or between different types of surgery ( P =0.687). In patients without a history of AF, incidence of EPoAF and LPoAF was 37% and 2%, respectively. EPoAF recurred in 58% patients with preoperative AF, 53% developed LPoAF. There were no correlations between intraoperative inducibility and EPoAF or LPoAF ( P >0.05). EPoAF was not correlated with LPoAF in patients without a history of AF ( P =0.116), in contrast to patients with AF before surgery ( P <0.001). Intraoperative AF inducibility does not predict development of either EPoAF or LPoAF. In patients with AF before surgery, EPoAF is correlated with LPoAF recurrences. This correlation is absent in patients without AF before surgery. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  19. Imaging β-amyloid fibrils in Alzheimer's disease: a critical analysis through simulation of amyloid fibril polymerization

    International Nuclear Information System (INIS)

    Shoghi-Jadid, Kooresh; Barrio, Jorge R.; Kepe, Vladimir; Wu, H.-M.; Small, Gary W.; Phelps, Michael E.; Huang, S.-C.

    2005-01-01

    The polymerization of β-amyloid (Aβ) peptides into fibrillary plaques is implicated, in part, in the pathogenesis of Alzheimer's disease. Aβ molecular imaging probes (Aβ-MIPs) have been introduced in an effort to quantify amyloid burden or load, in subjects afflicted with AD by invoking the classic PET receptor model for the quantitation of neuronal receptor density. In this communication, we explore conceptual differences between imaging the density of amyloid fibril polymers and neuronal receptors. We formulate a mathematical model for the polymerization of Aβ with parameters that are mapped to biological modulators of fibrillogenesis and introduce a universal measure for amyloid load to accommodate various interactions of Aβ-MIPs with fibrils. Subsequently, we hypothesize four Aβ-MIPs and utilize the fibrillogenesis model to simulate PET tissue time activity curves (TACs). Given the unique nature of polymer growth and resulting PET TAC, the four probes report differing amyloid burdens for a given brain pathology, thus complicating the interpretation of PET images. In addition, we introduce the notion of an MIP's resolution, apparent maximal binding site concentration, optimal kinetic topology and its resolving power in characterizing the pathological progression of AD and the effectiveness of drug therapy. The concepts introduced in this work call for a new paradigm that goes beyond the classic parameters B max and K D to include binding characteristics to polymeric peptide aggregates such as amyloid fibrils, neurofibrillary tangles and prions

  20. Core sequence of PAPf39 amyloid fibrils and mechanism of pH-dependent fibril formation: the role of monomer conformation.

    Science.gov (United States)

    French, Kinsley C; Makhatadze, George I

    2012-12-21

    PAPf39, a 39-residue peptide fragment from human prostatic acidic phosphatase, has been shown to form amyloid fibrils in semen (SEVI), which increase HIV infectivity by up to 5 orders of magnitude. The sequence of the PAPf39 fibrillar core was identified using hydrogen-deuterium exchange (HDX) mass spectrometry and protease protection assays. The central and C-terminal regions are highly protected from HDX and proteolytic cleavage and, thus, are part of the fibrillar core. Conversely, the N-terminal region is unprotected from HDX and proteolytic cleavage, suggesting that it is exposed and not part of the fibrillar core. This finding was tested using two N-terminal truncated variants, PAPf39Δ1-8 and PAPf39Δ1-13. Both variants formed amyloid fibrils at neutral pH. However, these variants showed a markedly different pH dependence of fibril formation versus that of PAPf39. PAPf39 fibrils can form at pH 7.7, but not at pH 5.5 or 2.5, while both N-terminally truncated variants can form fibrils at these pH values. Thus, the N-terminal region is not necessary for fibril formation but modulates the pH dependence of PAPf39 fibril formation. PAPf39Δ1-8 and PAPf39Δ1-13 are capable of seeding PAPf39 fibril formation at neutral pH, suggesting that these variants are structurally compatible with PAPf39, yet no mixed fibril formation occurs between the truncated variants and PAPf39 at low pH. This suggests that pH affects the PAPf39 monomer conformational ensemble, which is supported by far-UV circular dichroism spectroscopy. A conceptual model describing the pH dependence of PAPf39 aggregation is proposed and provides potential biological implications.

  1. Data-driven storytelling

    CERN Document Server

    Hurter, Christophe; Diakopoulos, Nicholas ed.; Carpendale, Sheelagh

    2018-01-01

    This book is an accessible introduction to data-driven storytelling, resulting from discussions between data visualization researchers and data journalists. This book will be the first to define the topic, present compelling examples and existing resources, as well as identify challenges and new opportunities for research.

  2. Pressure Driven Poiseuille Flow

    DEFF Research Database (Denmark)

    Stotz, Ingo Leonardo; Iaffaldano, Giampiero; Davies, D. Rhodri

    2018-01-01

    The Pacific plate is thought to be driven mainly by slab pull, associated with subduction along the Aleutians–Japan, Marianas–Izu–Bonin and Tonga–Kermadec trenches. This implies that viscous flow within the sub–Pacific asthenosphere is mainly generated by overlying plate motion (i.e. Couette flow...

  3. Role of sequence and structural polymorphism on the mechanical properties of amyloid fibrils.

    Directory of Open Access Journals (Sweden)

    Gwonchan Yoon

    Full Text Available Amyloid fibrils playing a critical role in disease expression, have recently been found to exhibit the excellent mechanical properties such as elastic modulus in the order of 10 GPa, which is comparable to that of other mechanical proteins such as microtubule, actin filament, and spider silk. These remarkable mechanical properties of amyloid fibrils are correlated with their functional role in disease expression. This suggests the importance in understanding how these excellent mechanical properties are originated through self-assembly process that may depend on the amino acid sequence. However, the sequence-structure-property relationship of amyloid fibrils has not been fully understood yet. In this work, we characterize the mechanical properties of human islet amyloid polypeptide (hIAPP fibrils with respect to their molecular structures as well as their amino acid sequence by using all-atom explicit water molecular dynamics (MD simulation. The simulation result suggests that the remarkable bending rigidity of amyloid fibrils can be achieved through a specific self-aggregation pattern such as antiparallel stacking of β strands (peptide chain. Moreover, we have shown that a single point mutation of hIAPP chain constituting a hIAPP fibril significantly affects the thermodynamic stability of hIAPP fibril formed by parallel stacking of peptide chain, and that a single point mutation results in a significant change in the bending rigidity of hIAPP fibrils formed by antiparallel stacking of β strands. This clearly elucidates the role of amino acid sequence on not only the equilibrium conformations of amyloid fibrils but also their mechanical properties. Our study sheds light on sequence-structure-property relationships of amyloid fibrils, which suggests that the mechanical properties of amyloid fibrils are encoded in their sequence-dependent molecular architecture.

  4. Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients

    Directory of Open Access Journals (Sweden)

    Eduardo Dytz Almeida

    2015-01-01

    Full Text Available Introduction: Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce. Objective: To investigate the arrhythmia subtype of atrial fibrillation and flutter patients in the emergency setting and compare the clinical profile, thromboembolic risk and anticoagulants use. Methods: Cross-sectional retrospective study, with data collection from medical records of every patient treated for atrial fibrillation and flutter in the emergency department of Instituto de Cardiologia do Rio Grande do Sul during the first trimester of 2012. Results: We included 407 patients (356 had atrial fibrillation and 51 had flutter. Patients with paroxysmal atrial fibrillation were in average 5 years younger than those with persistent atrial fibrillation. Compared to paroxysmal atrial fibrillation patients, those with persistent atrial fibrillation and flutter had larger atrial diameter (48.6 ± 7.2 vs. 47.2 ± 6.2 vs. 42.3 ± 6.4; p < 0.01 and lower left ventricular ejection fraction (66.8 ± 11 vs. 53.9 ± 17 vs. 57.4 ± 16; p < 0.01. The prevalence of stroke and heart failure was higher in persistent atrial fibrillation and flutter patients. Those with paroxysmal atrial fibrillation and flutter had higher prevalence of CHADS2 score of zero when compared to those with persistent atrial fibrillation (27.8% vs. 18% vs. 4.9%; p < 0.01. The prevalence of anticoagulation in patients with CHA2DS2-Vasc ≤ 2 was 40%. Conclusions: The population in our registry was similar in its comorbidities and demographic profile to those of North American and European registries. Despite the high thromboembolic risk, the use of anticoagulants was low, revealing difficulties for incorporating guideline recommendations. Public health strategies should be adopted in order to improve these rates.

  5. Human Islet Amyloid Polypeptide Fibril Binding to Catalase: A Transmission Electron Microscopy and Microplate Study

    Directory of Open Access Journals (Sweden)

    Nathaniel G. N. Milton

    2010-01-01

    Full Text Available The diabetes-associated human islet amyloid polypeptide (IAPP is a 37-amino-acid peptide that forms fibrils in vitro and in vivo. Human IAPP fibrils are toxic in a similar manner to Alzheimer's amyloid-β (Aβ and prion protein (PrP fibrils. Previous studies have shown that catalase binds to Aβ fibrils and appears to recognize a region containing the Gly-Ala-Ile-Ile sequence that is similar to the Gly-Ala-Ile-Leu sequence found in human IAPP residues 24-27. This study presents a transmission electron microscopy (TEM—based analysis of fibril formation and the binding of human erythrocyte catalase to IAPP fibrils. The results show that human IAPP 1-37, 8-37, and 20-29 peptides form fibrils with diverse and polymorphic structures. All three forms of IAPP bound catalase, and complexes of IAPP 1-37 or 8-37 with catalase were identified by immunoassay. The binding of biotinylated IAPP to catalase was high affinity with a KD of 0.77nM, and could be inhibited by either human or rat IAPP 1-37 and 8-37 forms. Fibrils formed by the PrP 118-135 peptide with a Gly-Ala-Val-Val sequence also bound catalase. These results suggest that catalase recognizes a Gly-Ala-Ile-Leu—like sequence in amyloid fibril-forming peptides. For IAPP 1-37 and 8-37, the catalase binding was primarily directed towards fibrillar rather than ribbon-like structures, suggesting differences in the accessibility of the human IAPP 24-27 Gly-Ala-Ile-Leu region. This suggests that catalase may be able to discriminate between different structural forms of IAPP fibrils. The ability of catalase to bind IAPP, Aβ, and PrP fibrils demonstrates the presence of similar accessible structural motifs that may be targets for antiamyloid therapeutic development.

  6. Studies of the structure of insulin fibrils by Fourier transform infrared (FTIR) spectroscopy and electron microscopy.

    Science.gov (United States)

    Nielsen, L; Frokjaer, S; Carpenter, J F; Brange, J

    2001-01-01

    Fibril formation (aggregation) of insulin was investigated in acid media by visual inspection, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. Insulin fibrillated faster in hydrochloric acid than in acetic acid at elevated temperatures, whereas the fibrillation tendencies were reversed at ambient temperatures. Electron micrographs showed that bovine insulin fibrils consisted of long fibers with a diameter of 5 to 10 nm and lengths of several microns. The fibrils appeared either as helical filaments (in hydrochloric acid) or arranged laterally in bundles (in acetic acid, NaCl). Freeze-thawing cycles broke the fibrils into shorter segments. FTIR spectroscopy showed that the native secondary structure of insulin was identical in hydrochloric acid and acetic acid, whereas the secondary structure of fibrils formed in hydrochloric acid was different from that formed in acetic acid. Fibrils of bovine insulin prepared by heating or agitating an acid solution of insulin showed an increased content of beta-sheet (mostly intermolecular) and a decrease in the intensity of the alpha-helix band. In hydrochloric acid, the frequencies of the beta-sheet bands depended on whether the fibrillation was induced by heating or agitation. This difference was not seen in acetic acid. Freeze-thawing cycles of the fibrils in hydrochloric acid caused an increase in the intensity of the band at 1635 cm(-1) concomitant with reduction of the band at 1622 cm(-1). The results showed that the structure of insulin fibrils is highly dependent on the composition of the acid media and on the treatment. Copyright 2001 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 90: 29-37, 2001

  7. Mid-Term Results of Surgical Treatment of Atrial Fibrillation in Valvular Heart Disease Assesed by Speckle Tracking Echocardiography.

    Science.gov (United States)

    Lorenzo, Natalia; Mendez, Irene; Taibo, Mikel; Martinis, Gianfranco; Badia, Sara; Reyes, Guillermo; Aguilar, Rio

    2018-03-19

    Atrial fibrillation frequently affects patients with valvular heart disease. Ablation of atrial fibrillation during valvular surgery is an alternative for restoring sinus rhythm. This study aimed to evaluate mid-term results of successful atrial fibrillation surgical ablation during valvular heart disease surgery, to explore left atrium post-ablation mechanics and to identify predictors of recurrence. Fifty-three consecutive candidates were included. Eligibility criteria for ablation included persistent atrial fibrillation valvular heart disease surgery.

  8. Assembly of α-synuclein fibrils in nanoscale studied by peptide truncation and AFM

    International Nuclear Information System (INIS)

    Zhang Feng; Lin Xiaojing; Ji Lina; Du Haining; Tang Lin; He Jianhua; Hu Jun; Hu Hongyu

    2008-01-01

    α-Synuclein (α-Syn) fibrils are the major component of Lewy bodies that are closely associated with the pathogenesis of Parkinson's disease, but the mechanism for the fibril assembly remains poorly understood. Here we report using a combination of peptide truncation and atomic force microscopy (AFM) to elucidate the self-assembly and morphology of the α-Syn fibrils. The results show that protease K significantly slims the fibrils from the mean height of ∼6.6 to ∼4.7 nm, whereas chaotropic denaturant urea completely breaks down the fibrils into small particles. The in situ enzymatic digestion also results in thinning of the fibrils, giving rise to some nicks on the fibrils. Moreover, N- or C-terminally truncated α-Syn fragments assemble into thinner filaments with the heights depending on the peptide lengths. A nine-residue peptide corresponding to the homologous GAV-motif sequence can form very thin (∼2.2 nm) but long (>1 μm) filaments. Thus, the central sequence of α-Syn forms a fibrillar core by cross-β-structure that is flanked by two flexible termini, and the orientation of the fibril growth is perpendicular to the β-sheet structures

  9. Use of Vitamins K antagonists in non-valvular atrial fibrillation ...

    African Journals Online (AJOL)

    Introduction: atrial fibrillation is the commonest cardiac rythm disorder. Thromboembolic accidents are common complications that should be prevented by anticoagulant treatment. The aim of our study is to assess the use of vitamins K antagonists in the prevention of thromboembolic risk in atrial fibrillation. Methods: it was a ...

  10. Mechanistic study of the inhibitory activity of Geum urbanum extract against α-Synuclein fibrillation

    DEFF Research Database (Denmark)

    Lobbens, Eva Stephanie; Breydo, Leonid; Pedersen, Thomas Skamris

    2016-01-01

    microscopy. Since the extract is a complex mixture, structure-function relationships could not be determined. Under the experimental conditions investigated, Geum urbanum was found to inhibit α-Synuclein fibrillation in a concentration dependent way, and to partly disintegrate preformed α-Synuclein fibrils...

  11. The changing face of glucagon fibrillation: Structural polymorphism and conformational imprinting

    DEFF Research Database (Denmark)

    Pedersen, J.S.; Dikov, D.; Flink, J.L.

    2006-01-01

    concentration) appear less thermostable than those formed under more challenging conditions (high temperatures, low glucagon or low salt concentrations). Properties of preformed fibrils used for seeding are inherited in a prion-like manner. Thus, we conclude that the structure of fibrils formed by glucagon...

  12. Mouse senile amyloid fibrils deposited in skeletal muscle exhibit amyloidosis-enhancing activity.

    Directory of Open Access Journals (Sweden)

    Jinze Qian

    2010-05-01

    Full Text Available Amyloidosis describes a group of protein folding diseases in which amyloid proteins are abnormally deposited in organs and/or tissues as fine fibrils. Mouse senile amyloidosis is a disorder in which apolipoprotein A-II (apoA-II deposits as amyloid fibrils (AApoAII and can be transmitted from one animal to another both by the feces and milk excreted by mice with amyloidosis. Thus, mouse AApoAII amyloidosis has been demonstrated to be a "transmissible disease". In this study, to further characterize the transmissibility of amyloidosis, AApoAII amyloid fibrils were injected into transgenic Apoa2(cTg(+/- and normal R1.P1-Apoa2(c mice to induce AApoAII systemic amyloidosis. Two months later, AApoAII amyloid deposits were found in the skeletal muscles of amyloid-affected mice, primarily in the blood vessels and in the interstitial tissues surrounding muscle fibers. When amyloid fibrils extracted from the skeletal muscles were subjected to Western blot analysis, apoA-II was detected. Amyloid fibril fractions isolated from the muscles not only demonstrated the structure of amyloid fibrils but could also induce amyloidosis in young mice depending on its fibril conformation. These findings present a possible pathogenesis of amyloidosis: transmission of amyloid fibril conformation through muscle, and shed new light on the etiology involved in amyloid disorders.

  13. Alcohol consumption and risk of atrial fibrillation in men and women: the Copenhagen City Heart Study

    DEFF Research Database (Denmark)

    Mukamal, Kenneth J; Tolstrup, Janne S; Friberg, Jens

    2005-01-01

    and incident atrial fibrillation among 16,415 women and men enrolled in the Copenhagen City Heart Study. We ascertained use of beer, wine, and spirits individually at up to 3 study visits with a structured questionnaire. We identified cases of atrial fibrillation by routine study ECGs and a validated...

  14. Identification of a Common Binding Mode for Imaging Agents to Amyloid Fibrils from Molecular Dynamics Simulations

    DEFF Research Database (Denmark)

    Skeby, Katrine Kirkeby; Sørensen, Jesper; Schiøtt, Birgit

    2013-01-01

    experimentally due to the insoluble nature of amyloid fibrils. This study uses molecular dynamics simulations to investigate the interactions between 13 aromatic amyloid imaging agents, entailing 4 different organic scaffolds, and a model of an amyloid fibril. Clustering analysis combined with free energy...

  15. Prednisone prevents atrial fibrillation promotion by atrial tachycardia remodeling in dogs

    NARCIS (Netherlands)

    Shiroshita-Takeshita, A; Brundel, BJJM; Lavoie, J; Nattel, S

    2006-01-01

    Background: There is evidence suggesting involvement of oxidative stress, inflammation, and calcineurin/nuclear factor of activated T cell pathways in atrial fibrillation. This study evaluated the efficacy of anti-inflammatory and calcineurin-inhibitory drugs on promotion of atrial fibrillation by

  16. Amyloid Fibril-Induced Structural and Spectral Modifications in the Thioflavin-T Optical Probe

    DEFF Research Database (Denmark)

    Murugan, N. Arul; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob

    2013-01-01

    Motivated by future possibilities to design target molecules for fibrils with diagnostic or therapeutic capability related to amyloidosis diseases, we investigate in this work the dielectric nature of amyloid fibril microenvironments in different binding sites using an optical probe, thioflavin-T...

  17. Influence of Aluminium and EGCG on Fibrillation and Aggregation of Human Islet Amyloid Polypeptide

    Directory of Open Access Journals (Sweden)

    Zhi-Xue Xu

    2016-01-01

    Full Text Available The abnormal fibrillation of human islet amyloid polypeptide (hIAPP has been implicated in the development of type II diabetes. Aluminum is known to trigger the structural transformation of many amyloid proteins and induce the formation of toxic aggregate species. The (−-epigallocatechin gallate (EGCG is considered capable of binding both metal ions and amyloid proteins with inhibitory effect on the fibrillation of amyloid proteins. However, the effect of Al(III/EGCG complex on hIAPP fibrillation is unclear. In the present work, we sought to view insight into the structures and properties of Al(III and EGCG complex by using spectroscopic experiments and quantum chemical calculations and also investigated the influence of Al(III and EGCG on hIAPP fibrillation and aggregation as well as their combined interference on this process. Our studies demonstrated that Al(III could promote fibrillation and aggregation of hIAPP, while EGCG could inhibit the fibrillation of hIAPP and lead to the formation of hIAPP amorphous aggregates instead of the ordered fibrils. Furthermore, we proved that the Al(III/EGCG complex in molar ratio of 1 : 1 as Al(EGCG(H2O2 could inhibit the hIAPP fibrillation more effectively than EGCG alone. The results provide the invaluable reference for the new drug development to treat type II diabetes.

  18. Risk of atrial fibrillation among bisphosphonate users: a multicenter, population-based, Italian study

    NARCIS (Netherlands)

    L. Herrera (Lizbeth); I. Leal (Ingrid); F. Lapi (Francesco); M.J. Schuemie (Martijn); V. Arcoraci (Vincenzo); F. Cipriani (Francesco); E. Sessa (E.); A. Vaccheri (Alberto); C. Piccinni (C.); T. Staniscia (Tommaso); A. Vestri (Annarita); M. Di Bari (M.); G. Corrao (Giovanni); A. Zambon (A.); D Gregori (Dario); F. Carle (F.); M.C.J.M. Sturkenboom (Miriam); G. Mazzaglia (Giampiero); G. Trifirò (Gianluca)

    2015-01-01

    textabstractSummary: Bisphosphonate treatment is used to prevent bone fractures. A controversial association of bisphosphonate use and risk of atrial fibrillation has been reported. In our study, current alendronate users were associated with a higher risk of atrial fibrillation as compared with

  19. Apixaban in patients at risk of stroke undergoing atrial fibrillation ablation

    DEFF Research Database (Denmark)

    Kirchhof, Paulus; Haeusler, Karl Georg; Blank, Benjamin

    2018-01-01

    Aims: It is recommended to perform atrial fibrillation ablation with continuous anticoagulation. Continuous apixaban has not been tested. Methods and results: We compared continuous apixaban (5 mg b.i.d.) to vitamin K antagonists (VKA, international normalized ratio 2-3) in atrial fibrillation pa...

  20. Time to implement fitness and reduction of fatness in atrial fibrillation therapy

    NARCIS (Netherlands)

    Van Gelder, Isabelle C.; Hobbelt, Anne H.; Brugemann, Johan; Rienstra, Michiel

    This editorial refers to ‘Self-reported physical activity and major adverse events in patients with atrial fibrillation: a report from the EURObservational Research Programme Pilot Survey on Atrial Fibrillation (EORP-AF) General Registry’ by M. Proietti et al. , doi:10.1093/europace/euw150. Atrial

  1. Warfarin for the prevention of systemic embolism in patients with non-valvular atrial fibrillation

    DEFF Research Database (Denmark)

    Andersen, L V; Vestergaard, P; Deichgraeber, P

    2008-01-01

    Warfarin for stroke prevention in patients with atrial fibrillation (AF) is well documented. However, it has not been examined in the prevention of systemic embolism.......Warfarin for stroke prevention in patients with atrial fibrillation (AF) is well documented. However, it has not been examined in the prevention of systemic embolism....

  2. Heat-induced whey protein isolate fibrils: Conversion, hydrolysis, and disulphide bond formation

    NARCIS (Netherlands)

    Bolder, S.G.; Vasbinder, A.; Sagis, L.M.C.; Linden, van der E.

    2007-01-01

    Fibril formation of individual pure whey proteins and whey protein isolate (WPI) was studied. The heat-induced conversion of WPI monomers into fibrils at pH 2 and low ionic strength increased with heating time and protein concentration. Previous studies, using a precipitation method, size-exclusion

  3. J-shaped association between QTc interval duration and the risk of atrial fibrillation

    DEFF Research Database (Denmark)

    Nielsen, Jonas Bille; Graff, Claus; Pietersen, Adrian

    2013-01-01

    The aim of this study was to investigate whether the heart rate-corrected QT (QTc) interval on the electrocardiogram (ECG) is associated with the onset of atrial fibrillation (AF).......The aim of this study was to investigate whether the heart rate-corrected QT (QTc) interval on the electrocardiogram (ECG) is associated with the onset of atrial fibrillation (AF)....

  4. Lessons from comparative studies of atrial fibrillation in dog, man and horse

    NARCIS (Netherlands)

    Meijler, F.L.; Tweel, I. van der; Herbschleb, J.N.; Heethaar, R.M.; Borst, C.

    1985-01-01

    Since its first description in 1903 by Hering, the irregularity of the heart beat has been the most striking characteristic of atrial fibrillation and has been subject of many studies. To quote Selzer, "Atrial fibrillation is the grandfather of cardiac arrhythmias." It is an arrhythmia that 1)

  5. Systolic and Diastolic Function by Tissue Doppler Imaging Predicts Mortality in Patients with Atrial Fibrillation

    DEFF Research Database (Denmark)

    Dons, Maria; BieringSørensen, Tor; Jensen, Jan Skov

    2015-01-01

    AIM: Tissue Doppler Imaging (TDI) detects early signs of left ventricular dysfunction. The prognostic potential of TDI in patients with atrial fibrillation (AF) has, however, not yet been clarified. This study evaluates the prognostic value of TDI in patients with atrial fibrillation. METHODS...

  6. Cardiovascular exercise and burden of arrhythmia in patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Skielboe, Ane Katrine; Bandholm, Thomas Quaade; Hakmann, Stine

    2017-01-01

    BACKGROUND: Physical activity at moderate-high intensity is recommended to prevent lifestyle diseases. Patients with atrial fibrillation are at risk of a sedentary lifestyle due to fear of exercise-induced episodes of atrial fibrillation. The burden of arrhythmia can be reduced by physical exercise...

  7. The spectrum of thyroid disease and risk of new onset atrial fibrillation

    DEFF Research Database (Denmark)

    Selmer, Christian; Olesen, Jonas Bjerring; Hansen, Morten Lock

    2012-01-01

    To examine the risk of atrial fibrillation in relation to the whole spectrum of thyroid function in a large cohort of patients.......To examine the risk of atrial fibrillation in relation to the whole spectrum of thyroid function in a large cohort of patients....

  8. Essential Oils May Lead α-Synuclein towards Toxic Fibrils Formation

    Directory of Open Access Journals (Sweden)

    Dina Morshedi

    2016-01-01

    Full Text Available α-Synuclein (α-Syn fibrillation links with Parkinson’s disease (PD and several related syndromes. It is believed that exposure to the factors which promote fibrillation may induce and progress such neurodegenerative diseases (NDs. Herein, the effects of some wildly used essential oils including Myrtus communis (M. communis on α-Syn fibrillation were examined. M. communis particularly increased α-Syn fibrillation in a concentration dependent manner. Given that applications of M. communis are very extensive in Asian societies, especially Zoroastrians, this study was extended towards its role on α-Syn fibrillation/cytotoxicity. By using a unilamellar vesicle, it was shown that the aggregated species with tendency to perturb membrane were increased in the presence of M. communis. In this regard, the cytotoxicity of α-Syn on SH-SH5Y cells was also increased significantly. Inappropriately, the effects of fibrillation inhibitors, baicalein and cuminaldehyde, were modulated in the presence of M. communis. However, major components of M. communis did not induce fibrillation and also the effect of M. communis was limited on other fibrinogenic proteins. Assuming that essential oils have the ability to pass through the blood brain barrier (BBB along with the popular attention on aromatherapy for the incurable ND, these findings suggest an implementation of fibrillation tests for essential oils.

  9. Insulin fibrillation: The influence and coordination of Zn2+

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Sønderby, Pernille; Bang, Maria Blanner

    2017-01-01

    fibrils has been debated for some years. We have therefore investigated the influence and binding geometry of zinc in fibrillated insulin using extended X-ray absorption fine-structure and X-ray absorption near-edge structure spectroscopy. The results were validated with fibre diffraction, Transmission...

  10. Double-stranded DNA Stimulates the Fibrillation of alpha-Synuclein in vitro and is Associated with the Mature Fibrils: An Electron Microscopy Study

    NARCIS (Netherlands)

    Cherny, Dmitry; Hoyer, Wolfgang; Subramaniam, Vinod; Jovin, Thomas M.

    2004-01-01

    Filamentous aggregates formed by α-synuclein are a prominent and presumably key etiological factor in Parkinson's and other neurodegenerative diseases characterized by motor disorders. Numerous studies have demonstrated that various environmental and intracellular factors affect the fibrillation

  11. Psoriasis is associated with subsequent atrial fibrillation in hypertensive patients with left ventricular hypertrophy

    DEFF Research Database (Denmark)

    Bang, Casper N; Okin, Peter M; Køber, Lars

    2014-01-01

    BACKGROUND: Inflammation contributes to the pathogenesis of psoriasis as well as atrial fibrillation. The impact of psoriasis and its association with new-onset atrial fibrillation was assessed in hypertensive patients with left ventricular hypertrophy (LVH). METHODS: The predictive value...... or developed psoriasis and new-onset atrial fibrillation occurred in 506 patients (7.1%) during a mean follow-up of 4.7 ± 1.1 years. At baseline, the psoriasis patients were younger (65 ± 7 vs. 67 ± 7 years) and had less left ventricle hypertrophy by ECG Sokolow-Lyon voltage (27.6 ± 9.7 vs. 30.1 ± 10.4 mm...... of baseline or incident psoriasis for new-onset atrial fibrillation was evaluated in 7099 hypertensive patients with electrocardiographic LVH with no history of atrial fibrillation or other cardiovascular disease, in sinus rhythm on their baseline electrocardiogram. RESULTS: A total of 154 patients (2.2%) had...

  12. Direct visualization of HIV-enhancing endogenous amyloid fibrils in human semen

    Science.gov (United States)

    Usmani, Shariq M.; Zirafi, Onofrio; Müller, Janis; Sandi-Monroy, Nathallie; Yadav, Jay K.; Meier, Christoph; Weil, Tanja; Roan, Nadia R.; Greene, Warner C.; Walther, Paul; Nilsson, K. Peter R.; Hammarström, Per; Wetzel, Ronald; Pilcher, Christopher D.; Gagsteiger, Friedrich; Fändrich, Marcus; Kirchhoff, Frank; Münch, Jan

    2014-01-01

    Naturally occurring fragments of the abundant semen proteins prostatic acid phosphatase (PAP) and semenogelins form amyloid fibrils in vitro. These fibrils boost HIV infection and may play a key role in the spread of the AIDS pandemic. However, the presence of amyloid fibrils in semen remained to be demonstrated. Here, we use state of the art confocal and electron microscopy techniques for direct imaging of amyloid fibrils in human ejaculates. We detect amyloid aggregates in all semen samples and find that they partially consist of PAP fragments, interact with HIV particles and increase viral infectivity. Our results establish semen as a body fluid that naturally contains amyloid fibrils that are exploited by HIV to promote its sexual transmission. PMID:24691351

  13. NONPOTENTIALITY OF CHROMOSPHERIC FIBRILS IN NOAA ACTIVE REGIONS 11092 AND 9661

    International Nuclear Information System (INIS)

    Jing Ju; Yuan Yuan; Xu Yan; Wang Haimin; Reardon, Kevin; Wiegelmann, Thomas

    2011-01-01

    In this paper, we present a method to automatically segment chromospheric fibrils from Hα observations and further identify their orientation. We assume that chromospheric fibrils are aligned with the magnetic field. By comparing the orientation of the fibrils with the azimuth of the embedding chromospheric magnetic field extrapolated from a potential field model, the shear angle, a measure of nonpotentiality, along the fibrils is readily deduced. Following this approach, we make a quantitative assessment of the nonpotentiality of fibrils in two NOAA active regions (ARs): (1) the relatively simple AR 11092, observed with very high resolution by Interferometric Bidimensional Spectrometer, and (2) a β-γ-δ AR 9661, observed with median resolution by Big Bear Solar Observatory before and after an X1.6 flare.

  14. Polymorphism, metastable species and interconversion: the many states of glucagon fibrils

    DEFF Research Database (Denmark)

    Ghodke, Shirin D; Jensen, Grethe Vestergaard; Svane, Anna Sigrid P.

    2014-01-01

    physicochemical conditions such as high temperature, pressure, mechanical and chemical stress. Factors such as peptide concentration, accessible surface area, surface hydration of the glucagon molecular state, contact surface, temperature and ionic strength all contribute to fibrillar structure and stability...... fibril upon incubation at elevated temperatures (but not vice versa), indicating that fibrils are fundamentally malleable if they have not attained the most stable fibrillar state. While the effect of pressure on glucagon is complex (accelerating fibrillation at intermediate pressures and decelerating...... it at higher pressures), the thermal expansion coefficients obtained from these studies agree well with our previous calorimetric studies to reveal reduced or increased hydration of fibrils (leading to reduced or increased stability) depending on fibrillation conditions. Finally, we report...

  15. Conjugated Quantum Dots Inhibit the Amyloid β (1–42 Fibrillation Process

    Directory of Open Access Journals (Sweden)

    Garima Thakur

    2011-01-01

    Full Text Available Nanoparticles have enormous potential in diagnostic and therapeutic studies. We have demonstrated that the amyloid beta mixed with and conjugated to dihydrolipoic acid- (DHLA capped CdSe/ZnS quantum dots (QDs of size approximately 2.5 nm can be used to reduce the fibrillation process. Transmission electron microscopy (TEM and atomic force microscopy (AFM were used as tools for analysis of fibrillation. There is a significant change in morphology of fibrils when amyloid β (1–42 (Aβ (1–42 is mixed or conjugated to the QDs. The length and the width of the fibrils vary under modified conditions. Thioflavin T (ThT fluorescence supports the decrease in fibril formation in presence of DHLA-capped QDs.

  16. Angiotensinogen and ACE gene polymorphisms and risk of atrial fibrillation in the general population

    DEFF Research Database (Denmark)

    Ravn, Lasse S; Benn, Marianne; Nordestgaard, Børge G

    2008-01-01

    OBJECTIVES: The renin-angiotensin system may play a role in the pathogenesis of atrial fibrillation, and renin-angiotensin system blockers reduce the risk of atrial fibrillation. We hypothesized that polymorphisms in the angiotensinogen and angiotensin-converting enzyme (ACE) genes encoding...... in the ACE gene; rare allele frequencies were 0.16, 0.40, 0.12, 0.41, and 0.49, respectively. Participants had sinus rhythm at inclusion. During 26 years of follow-up, 968 individuals developed atrial fibrillation. Multifactorially adjusted hazard ratios for atrial fibrillation for a-20c ac and cc versus aa...... proteins in this system predict risk of atrial fibrillation. METHODS AND RESULTS: We genotyped 9235 individuals from the Danish general population, The Copenhagen City Heart Study, for the a-20c, g-6a, T174M, and M235T polymorphisms in the angiotensinogen gene and the insertion/deletion (I/D) polymorphism...

  17. Simultaneous measurement of amyloid fibril formation by dynamic light scattering and fluorescence reveals complex aggregation kinetics.

    Directory of Open Access Journals (Sweden)

    Aaron M Streets

    Full Text Available An apparatus that combines dynamic light scattering and Thioflavin T fluorescence detection is used to simultaneously probe fibril formation in polyglutamine peptides, the aggregating subunit associated with Huntington's disease, in vitro. Huntington's disease is a neurodegenerative disorder in a class of human pathologies that includes Alzheimer's and Parkinson's disease. These pathologies are all related by the propensity of their associated protein or polypeptide to form insoluble, β-sheet rich, amyloid fibrils. Despite the wide range of amino acid sequence in the aggregation prone polypeptides associated with these diseases, the resulting amyloids display strikingly similar physical structure, an observation which suggests a physical basis for amyloid fibril formation. Thioflavin T fluorescence reports β-sheet fibril content while dynamic light scattering measures particle size distributions. The combined techniques allow elucidation of complex aggregation kinetics and are used to reveal multiple stages of amyloid fibril formation.

  18. Probability of atrial fibrillation after ablation: Using a parametric nonlinear temporal decomposition mixed effects model.

    Science.gov (United States)

    Rajeswaran, Jeevanantham; Blackstone, Eugene H; Ehrlinger, John; Li, Liang; Ishwaran, Hemant; Parides, Michael K

    2018-01-01

    Atrial fibrillation is an arrhythmic disorder where the electrical signals of the heart become irregular. The probability of atrial fibrillation (binary response) is often time varying in a structured fashion, as is the influence of associated risk factors. A generalized nonlinear mixed effects model is presented to estimate the time-related probability of atrial fibrillation using a temporal decomposition approach to reveal the pattern of the probability of atrial fibrillation and their determinants. This methodology generalizes to patient-specific analysis of longitudinal binary data with possibly time-varying effects of covariates and with different patient-specific random effects influencing different temporal phases. The motivation and application of this model is illustrated using longitudinally measured atrial fibrillation data obtained through weekly trans-telephonic monitoring from an NIH sponsored clinical trial being conducted by the Cardiothoracic Surgery Clinical Trials Network.

  19. Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Hoang Viet, Man; Roland, Christopher, E-mail: cmroland@ncsu.edu; Sagui, Celeste, E-mail: sagui@ncsu.edu [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States); Derreumaux, Philippe; Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City (Viet Nam)

    2015-10-21

    Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.

  20. Intracellular Calcium Dynamics and Autonomic Stimulation in Atrial Fibrillation: Mechanisms and Implications

    Directory of Open Access Journals (Sweden)

    Chung-Chuan Chou, MD

    2008-01-01

    Full Text Available While atrial fibrillation is characterized by the co-existence of multiple activation waves within the atria, rapid activations in the pulmonary veins play an important role for the initiation and maintenance of atrial fibrillation. In addition to reentry, non-reentrant mechanisms resulting from abnormal intracellular calcium handling and intracellular calcium overload can also be responsible for these rapid activations in the pulmonary veins. Meanwhile, alterations of autonomic tone, involving both the sympathetic and parasympathetic nervous system, have been implicated in initiating paroxysmal atrial fibrillation. But the effectiveness of autonomic modulation as an adjunctive therapeutic strategy to catheter ablation of atrial fibrillation has been inconsistent. The interactions between the autonomic nervous system and atrial fibrillation are more complex than currently understood and further mechanistic and clinical studies are warranted.

  1. Atrial Fibrillation and Coronary Bypass Surgery – What Can Be Risk Factors for its' Appearance?

    Directory of Open Access Journals (Sweden)

    Slavenka Štraus

    2010-02-01

    Full Text Available The main goal of our study was to evalúate possible perioperative risk factors for occurrence of atrial fibrillation in the postoperative period in patients after CABG operations. The study included 140 patients after CABG, divided into two groups - Group I - 64 patients with new onset of POAF and Group II - 76 patients without postoperative atrial fibrillation occurrence. In both groups possible risk factors for atrial fibrillation onset (preoperative and postoperative were analyzed.Results showed that we can predict new onset of atrial fibrillation after CABG if the following preoperative factors are present - low ejection fraction (less than 40%, LAd > 40mm, higher body mass index (BMI over 30, presence of COPD and older age. Important perioperative factors for onset of atrial fibrillation in our study were longer extracorporeal circulation, increased dose/number of inotropic drugs, blood transfusion and elevated WBC count postoperatively.

  2. Atrial and ventricular function after cardioversion of atrial fibrillation.

    Science.gov (United States)

    Xiong, C.; Sonnhag, C.; Nylander, E.; Wranne, B.

    1995-01-01

    OBJECTIVE--Previous studies on atrial recovery after cardioversion of atrial fibrillation have not taken into account new knowledge about the pathophysiology of transmitral and transtricuspid flow velocity patterns. It is possible to shed further light on this problem if atrioventricular inflow velocity, venous filling pattern, and atrioventricular annulus motion are recorded and interpreted together. DESIGN--Prospective examinations of mitral and tricuspid transvalvar flow velocities, superior caval and pulmonary venous filling, and mitral and tricuspid annulus motion were recorded using Doppler echocardiography. Examinations were performed before and 24 hours, 1 month, and 20 months after cardioversion. SETTING--Tertiary referral centre for cardiac disease with facilities for invasive and non-invasive investigation. PATIENTS--16 patients undergoing cardioversion of atrial fibrillation in whom sinus rhythm had persisted for 24 hours or more. RESULTS--Before conversion there was no identifiable A wave in transvalvar flow recordings. The total motion of the tricuspid and mitral annulus was subnormal and there was no identifiable atrial component. Venous flow patterns in general showed a low systolic velocity. After conversion, A waves and atrial components were seen in all patients and increased significantly (P atrial components, an increased systolic component of venous inflow, an increased A wave velocity, and a decreased E/A ratio of the transvalvar velocity curves. The ventricular component of annulus motion was unchanged. Changes in general occurred earlier on the right side than the left. CONCLUSIONS--This study indicates that, in addition to the previously known electromechanical dissociation of atrial recovery that exists after cardioversion of atrial fibrillation, there may also be a transient deterioration of ventricular function modulating the transvalvar inflow velocity recordings. Function on the right side generally becomes normal earlier than on the

  3. Therapeutical considerations in associated atrial fibrillation and heart failure.

    Science.gov (United States)

    Mitu, O; Mitu, F; Constantin, S; Cojocaru, Elena; Leon, Maria-Magdalena

    2014-01-01

    Atrial fibrillation is a supraventricular tachyarrhythmia very common in medical practice, often associated with heart failure. Pathophysiological relationship between atrial fibrillation and heart failure is in the attention of numerous case studies, being incomplete elucidated. We made a retrospective study on patients with both diseases, hospitalized in Cardiovascular Rehabilitation Hospital, Iasi, during 01.01.2013 - 31.12.2013. The obtained data allowed the classification of patients according to gender distribution, age groups, area of origin, clinical aspects, and association with other diseases, instituted treatment and appreciation of CHADS2 score. Data interpretation was performed with appropriate statistical methods. We found a higher frequency of the disease among male patients, male: female ratio being 2:1; the most of the patients lived in urban area. The pick of diseases incidence was in patients over 65 years with a total percentage of 70.84% of cases. We noted that the most common symptoms were exertional dyspnea (in all patients), palpitations, dizziness, headache, fatigue, asthenia, dyspnea at rest and pain/chest pressure. In our study, the majority of patients received the beta-blocker--digoxin combination (46 patients, 40 patients respectively). The coexistence of the two disorders could be explained by identifying common risk factors. Beta blockers should be the first therapeutic option in patients with chronic heart failure and atrial fibrillation because they have the effect of controlling heart rate and improve survival in patients with these disorders. Meanwhile, digoxin is a drug, only certain conditions of high accuracy monitoring; whose major clinical indications are heart failure and atrial rhythm disturbances.

  4. A new therapeutic strategy for electrical cardioversion of atrial fibrillation.

    Science.gov (United States)

    de Luca, I; Sorino, M; Del Salvatore, B; de Luca, L

    2001-11-01

    The conventional approach to cardioversion of atrial fibrillation includes a period of anticoagulation with oral anticoagulant therapy (OAT) extending from 3 weeks precardioversion to 4 weeks postcardioversion. The protocol of rapid anticoagulation (such as that of the ACUTE study) consists of a precardioversion transesophageal echocardiography (TEE) followed by OAT for 4 weeks. In the last few years low-molecular-weight heparins have established themselves as a safe and efficacious alternative to traditional antithrombotic therapies. The aim of this study was to demonstrate that the exclusion of thrombi by precardioversion TEE together with the exclusion of atrial stunning by a second TEE performed after 1 week, to date not suggested in the literature, could reduce to 7 days the period of pericardioversion anticoagulation. This therapy would be carried out using low-molecular-weight heparins with no need for biological monitoring and with the possibility of self-administration. We have studied 57 consecutive patients who had atrial fibrillation or flutter with a history of atrial fibrillation lasting > 48 hours. All patients received enoxaparin at a dosage of 100 IU antiXa/kg twice daily before undergoing multiplane TEE. Previous informed consent and ethical committee authorization had been obtained. Twenty-four hours following TEE, in the absence of thrombi and/or spontaneous moderate/severe echocontrast in the atrial chambers, the patients underwent electrical cardioversion and were discharged within 24 hours of sinus rhythm restoration. These patients were prescribed enoxaparin at the indicated dosage twice daily until TEE, performed in an outpatients setting 7 days following cardioversion. In the absence of thrombi and/or atrial and/or left atrial appendage stunning, OAT was terminated. Enoxaparin was associated with OAT for the following 3 weeks if any of the following signs of stunning were present: A wave inferior to the normal value for age at transmitral

  5. Privacy driven internet ecosystem

    OpenAIRE

    Trinh, Tuan Anh; Gyarmati, Laszlo

    2012-01-01

    The dominant business model of today's Internet is built upon advertisements; users can access Internet services while the providers show ads to them. Although significant efforts have been made to model and analyze the economic aspects of this ecosystem, the heart of the current status quo, namely privacy, has not received the attention of the research community yet. Accordingly, we propose an economic model of the privacy driven Internet ecosystem where privacy is handled as an asset that c...

  6. The immediate future for the medical treatment of atrial fibrillation

    DEFF Research Database (Denmark)

    Pedersen, Ole Dyg; Brendorp, Bente; Køber, Lars

    2002-01-01

    ) the rhythm causes loss of atrioventricular synchrony, which reduces diastolic filling and may lead to heart failure; and iii) atrial contraction is lost leading to stagnant blood that again may lead to atrial thrombi and peripheral embolism. Thus, the treatment of atrial fibrillation is focused...... on the maintenance of sinus rhythm, rate control and prevention of embolism. For the maintenance of sinus rhythm, all drugs under current development are potassium channel blockers; the so-called class III anti-arrhythmic drugs. Those which have been further investigated appear to be valuable for maintenance...

  7. Entropy measurements in paroxysmal and persistent atrial fibrillation

    International Nuclear Information System (INIS)

    Cervigón, R; Moreno, J; Pérez-Villacastín, J; Reilly, R B; Millet, J; Castells, F

    2010-01-01

    Recent studies on atrial fibrillation (AF) have identified different activation patterns in paroxysmal and persistent AF. In this study, bipolar intra-atrial registers from 28 patients (14 paroxysmal AF and 14 persistent AF) were analyzed in order to find out regional differences in the organization in both types of arrhythmias. The organization of atrial electrical activity was assessed in terms of nonlinear parameters, such as entropy measurements. Results showed differences between the atrial chambers with a higher disorganization in the left atrium in paroxysmal AF patients and a more homogenous behavior along the atria in persistent AF patients

  8. Cardioversion for atrial fibrillation in current European practice

    DEFF Research Database (Denmark)

    Hernández-Madrid, Antonio; Svendsen, Jesper Hastrup; Lip, Gregory Y.H.

    2013-01-01

    This survey was conducted to provide an insight into the current clinical practice regarding the use of cardioversion for atrial fibrillation (AF) in Europe. Responses were received from 57 centres across Europe, 71.9% of which were university hospitals. For electrical cardioversion, general...... anaesthesia was managed by an anaesthesiologist in 73.9% of centres and by a cardiologist in 37%. In the majority of centres, electrical cardioversion was performed using a biphasic defibrillator (85.1%). Antiarrhythmic drugs were routinely prescribed prior to electrical cardioversion by 54.3% of hospitals...

  9. Plasma YKL-40, a new biomarker for atrial fibrillation?

    DEFF Research Database (Denmark)

    Henningsen, Kristoffer Mads; Therkelsen, Susette Krohn; Johansen, Julia Sidenius

    2009-01-01

    AIMS: The aim of this study was to determine changes in a new potential biomarker plasma YKL-40 in patients with atrial fibrillation (AF) before and after electrical cardioversion (CV). METHODS AND RESULTS: Plasma concentrations of YKL-40 were measured in 56 patients (mean age 65 years, range 34......-84) with persistent AF (lasting mean 128 days, range 14-960), in 19 age-matched patients with permanent AF, and in 19 healthy subjects. The patients with persistent AF underwent CV. Plasma YKL-40 was measured prior to CV, and at follow-up after 24 h, 30 and 180 days. Patients with persistent AF had lower plasma YKL...

  10. Mass Determination of Entire Amyloid Fibrils by Using Mass Spectrometry.

    Science.gov (United States)

    Doussineau, Tristan; Mathevon, Carole; Altamura, Lucie; Vendrely, Charlotte; Dugourd, Philippe; Forge, Vincent; Antoine, Rodolphe

    2016-02-12

    Amyloid fibrils are self-assembled protein structures with important roles in biology (either pathogenic or physiological), and are attracting increasing interest in nanotechnology. However, because of their high aspect ratio and the presence of some polymorphism, that is, the possibility to adopt various structures, their characterization is challenging and basic information such as their mass is unknown. Here we show that charge-detection mass spectrometry, recently developed for large self-assembled systems such as viruses, provides such information in a straightforward manner. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Exercise-Induced Ventricular Fibrillation: Seven Years Follow-Up

    Directory of Open Access Journals (Sweden)

    Gökmen Gemici

    2011-11-01

    Full Text Available We present a 7-year follow-up of a 55-year-old male who experienced ventricular fibrillation during the recovery period of exercise testing and refused implantation of an ICD. Normal left ventricular systolic function was found on echocardiographic examination, and coronary angiography revealed only a side branch disease with a vessel diameter of less than 2 millimeters. The patient was discharged on metoprolol and ASA in addition to his previous treatment with lisinopril and simvastatin. Outpatient cardiac evaluation by repeated 24-hour ECG monitorizations (Holter revealed normal findings. On follow up visits every six months for the past seven years, the patient was found to be asymptomatic.

  12. Atrial Fibrillation - A Common Ground for Neurology and Cardiology.

    Science.gov (United States)

    Abukhalil, Fawzi; Bodhit, Aakash; Cai, Peter Y; Ansari, Saeed; Thenkabail, Spandana; Ganji, Sarah; Saravanapavan, Pradeepan; Chandra Shekhar, Chandana; Waters, Michael F; Beaver, Thomas M; Shushrutha Hedna, Vishnumurthy

    2013-01-01

    Atrial fibrillation (AF) has a huge impact on clinical stroke because it is the primary cause of cardio-embolism, which constitutes ~20% of all strokes. As a result, there is a great need to explore safer and more effective primary and secondary prophylactic agents. In this article, we discuss the overlapping issues pertaining to AF from both a neurology and cardiology standpoint. We focus on the dynamic interplay of neurovascular and cardiovascular diseases in relation to AF, traditional and novel risk factors for AF leading to stroke, impact of AF on cognitive decline, and current upstream medical and surgical options for embolism prophylaxis.

  13. CT imaging of complications of catheter ablation for atrial fibrillation

    International Nuclear Information System (INIS)

    Shroff, G.S.; Guirguis, M.S.; Ferguson, E.C.; Oldham, S.A.A.; Kantharia, B.K.

    2014-01-01

    The complication rate following radiofrequency catheter ablation for atrial fibrillation is low (<5%). Complications include pericardial effusion, cardiac tamponade, pulmonary vein stenosis, oesophageal ulceration or perforation, atrio-oesophageal fistula formation, stroke/transient ischaemic attack, phrenic nerve injury, haematoma at the puncture site, and femoral arteriovenous fistula. Among available imaging tools, computed tomography (CT) can be very useful in diagnosing complications of the procedure, particularly in the subacute and delayed stages after ablation. This review illustrates CT imaging of several of the common and uncommon complications of radiofrequency catheter ablation

  14. Strain-induced internal fibrillation in looped aramid filaments

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell

    2010-01-01

    in the scattering pattern is observed. One model capable of describing the intensity is a model of stacked cylinders. These cylinders could be part of the fibrillar structure present in the PPTA fibres, which consist of cylinder- to tape-like objects, the presence of which is supported by SEM images. One...... hypothetical physical interpretation presented here for the appearance of a regular internal structure is the occurrence of fibrillar separation in regions undergoing axially compressive strain, and the appearance of strain relief/slip planes between packs of fibrils in regions undergoing tensile strain...

  15. Water-driven micromotors.

    Science.gov (United States)

    Gao, Wei; Pei, Allen; Wang, Joseph

    2012-09-25

    We demonstrate the first example of a water-driven bubble-propelled micromotor that eliminates the requirement for the common hydrogen peroxide fuel. The new water-driven Janus micromotor is composed of a partially coated Al-Ga binary alloy microsphere prepared via microcontact mixing of aluminum microparticles and liquid gallium. The ejection of hydrogen bubbles from the exposed Al-Ga alloy hemisphere side, upon its contact with water, provides a powerful directional propulsion thrust. Such spontaneous generation of hydrogen bubbles reflects the rapid reaction between the aluminum alloy and water. The resulting water-driven spherical motors can move at remarkable speeds of 3 mm s(-1) (i.e., 150 body length s(-1)), while exerting large forces exceeding 500 pN. Factors influencing the efficiency of the aluminum-water reaction and the resulting propulsion behavior and motor lifetime, including the ionic strength and environmental pH, are investigated. The resulting water-propelled Al-Ga/Ti motors move efficiently in different biological media (e.g., human serum) and hold considerable promise for diverse biomedical or industrial applications.

  16. Fibril deformation under load of the rabbit Achilles tendon and medial collateral ligament femoral entheses.

    Science.gov (United States)

    Sevick, Johnathan L; Abusara, Ziad; Andrews, Stephen H; Xu, Minjia; Khurshid, Saad; Chatha, Jansher; Hart, David A; Shrive, Nigel G

    2018-04-10

    Microscopic visualization under load of the region connecting ligaments/tendons to bone, the enthesis, has been performed previously; however, specific investigation of individual fibril deformation may add insight to such studies. Detailed visualization of fibril deformation would inform on the mechanical strategies employed by this tissue in connecting two mechanically disparate materials. Clinically, an improved understanding of enthesis mechanics may help guide future restorative efforts for torn or injured ligaments/tendons, where the enthesis is often a point of weakness. In this study, a custom ligament/tendon enthesis loading device was designed and built, a unique method of sample preparation was devised, and second harmonic and two-photon fluorescence microscopy were used to capture the fibril-level load response of the rabbit Achilles tendon and medial collateral ligament femoral entheses. A focus was given to investigation of the mechanical problem of fibril embedment. Resultant images indicate a rapid (occurring over approximately 60 μm) change in fibril orientation at the interface of ligament/tendon and calcified fibrocartilage early in the loading regime, before becoming relatively constant. Such a change in fibril angle helps confirm the materially graded region demonstrated by others, while, in this case, providing additional insight into fibril bending. We speculate that the scale of the mechanical problem (i.e., fibril diameters being on the order of 250 nm) allows fibrils to bend over the small (relative to the imaging field of view, but large relative to fibril diameter) distances observed; thus, potentially lessening required embedment lengths. Nevertheless, this behavior merits further investigation to be confirmed. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  17. Surface characterization of insulin protofilaments and fibril polymorphs using tip-enhanced Raman spectroscopy (TERS).

    Science.gov (United States)

    Kurouski, Dmitry; Deckert-Gaudig, Tanja; Deckert, Volker; Lednev, Igor K

    2014-01-07

    Amyloid fibrils are β-sheet-rich protein aggregates that are strongly associated with a variety of neurodegenerative maladies, such as Alzheimer's and Parkinson's diseases. Even if the secondary structure of such fibrils is well characterized, a thorough understanding of their surface organization still remains elusive. Tip-enhanced Raman spectroscopy (TERS) is one of a few techniques that allow the direct characterization of the amino acid composition and the protein secondary structure of the amyloid fibril surface. Herein, we investigated the surfaces of two insulin fibril polymorphs with flat (flat) and left-twisted (twisted) morphology. It was found that the two differ substantially in both amino acid composition and protein secondary structure. For example, the amounts of Tyr, Pro, and His differ, as does the number of carboxyl groups on the respective surfaces, whereas the amounts of Phe and of positively charged amino and imino groups remain similar. In addition, the surface of protofilaments, the precursors of the mature flat and twisted fibrils, was investigated using TERS. The results show substantial differences with respect to the mature fibrils. A correlation of amino acid frequencies and protein secondary structures on the surface of protofilaments and on flat and twisted fibrils allowed us to propose a hypothetical mechanism for the propagation to specific fibril polymorphs. This knowledge can shed a light on the toxicity of amyloids and define the key factors responsible for fibril polymorphism. Finally, this work demonstrates the potential of TERS for the surface characterization of amyloid fibril polymorphs. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  18. Dynamic behavior of small heat shock protein inhibition on amyloid fibrillization of a small peptide (SSTSAA) from RNase A

    International Nuclear Information System (INIS)

    Xi, Dong; Dong, Xiao; Deng, Wei; Lai, Luhua

    2011-01-01

    Highlights: ► Mechanism of small heat shock protein inhibition on fibril formation was studied. ► Peptide SSTSAA with modified ends was used for amyloid fibril formation. ► FRET signal was followed during the fibril formation. ► Mj HSP16.5 inhibits fibril formation when introduced in the lag phase. ► Mj HSP16.5 slows down fibril formation when introduced after the lag phase. -- Abstract: Small heat shock proteins, a class of molecular chaperones, are reported to inhibit amyloid fibril formation in vitro, while the mechanism of inhibition remains unknown. In the present study, we investigated the mechanism by which Mj HSP16.5 inhibits amyloid fibril formation of a small peptide (SSTSAA) from RNase A. A model peptide (dansyl-SSTSAA-W) was designed by introducing a pair of fluorescence resonance energy transfer (FRET) probes into the peptide, allowing for the monitoring of fibril formation by this experimental model. Mj HSP16.5 completely inhibited fibril formation of the model peptide at a molar ratio of 1:120. The dynamic process of fibril formation, revealed by FRET, circular dichroism, and electron microscopy, showed a lag phase of about 2 h followed by a fast growth period. The effect of Mj HSP16.5 on amyloid fibril formation was investigated by adding it into the incubation solution during different growth phases. Adding Mj HSP16.5 to the incubating peptide before or during the lag phase completely inhibited fibril formation. However, introducing Mj HSP16.5 after the lag phase only slowed down the fibril formation process by adhering to the already formed fibrils. These findings provide insight into the inhibitory roles of small heat shock proteins on amyloid fibril formation at the molecular level.

  19. Dynamic behavior of small heat shock protein inhibition on amyloid fibrillization of a small peptide (SSTSAA) from RNase A

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Dong [BNLMS, State Key Laboratory of Structural Chemistry for Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Center for Theoretical Biology, Peking University, Beijing 100871 (China); Dong, Xiao; Deng, Wei [BNLMS, State Key Laboratory of Structural Chemistry for Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Lai, Luhua, E-mail: lhlai@pku.edu.cn [BNLMS, State Key Laboratory of Structural Chemistry for Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Center for Theoretical Biology, Peking University, Beijing 100871 (China)

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Mechanism of small heat shock protein inhibition on fibril formation was studied. Black-Right-Pointing-Pointer Peptide SSTSAA with modified ends was used for amyloid fibril formation. Black-Right-Pointing-Pointer FRET signal was followed during the fibril formation. Black-Right-Pointing-Pointer Mj HSP16.5 inhibits fibril formation when introduced in the lag phase. Black-Right-Pointing-Pointer Mj HSP16.5 slows down fibril formation when introduced after the lag phase. -- Abstract: Small heat shock proteins, a class of molecular chaperones, are reported to inhibit amyloid fibril formation in vitro, while the mechanism of inhibition remains unknown. In the present study, we investigated the mechanism by which Mj HSP16.5 inhibits amyloid fibril formation of a small peptide (SSTSAA) from RNase A. A model peptide (dansyl-SSTSAA-W) was designed by introducing a pair of fluorescence resonance energy transfer (FRET) probes into the peptide, allowing for the monitoring of fibril formation by this experimental model. Mj HSP16.5 completely inhibited fibril formation of the model peptide at a molar ratio of 1:120. The dynamic process of fibril formation, revealed by FRET, circular dichroism, and electron microscopy, showed a lag phase of about 2 h followed by a fast growth period. The effect of Mj HSP16.5 on amyloid fibril formation was investigated by adding it into the incubation solution during different growth phases. Adding Mj HSP16.5 to the incubating peptide before or during the lag phase completely inhibited fibril formation. However, introducing Mj HSP16.5 after the lag phase only slowed down the fibril formation process by adhering to the already formed fibrils. These findings provide insight into the inhibitory roles of small heat shock proteins on amyloid fibril formation at the molecular level.

  20. A model of insulin fibrils derived from the x-ray crystal structure of a monomeric insulin (despentapeptide insulin).

    Science.gov (United States)

    Brange, J; Dodson, G G; Edwards, D J; Holden, P H; Whittingham, J L

    1997-04-01

    The crystal structure of despentapeptide insulin, a monomeric insulin, has been refined at 1.3 A spacing and subsequently used to predict and model the organization in the insulin fibril. The model makes use of the contacts in the densely packed despentapeptide insulin crystal, and takes into account other experimental evidence, including binding studies with Congo red. The dimensions of this model fibril correspond well with those measured experimentally, and the monomer-monomer contacts within the fibril are in accordance with the known physical chemistry of insulin fibrils. Using this model, it may be possible to predict mutations in insulin that might alleviate problems associated with fibril formation during insulin therapy.

  1. Modulation of human IAPP fibrillation: cosolutes, crowders and chaperones.

    Science.gov (United States)

    Gao, Mimi; Estel, Kathrin; Seeliger, Janine; Friedrich, Ralf P; Dogan, Susanne; Wanker, Erich E; Winter, Roland; Ebbinghaus, Simon

    2015-04-07

    The cellular environment determines the structure and function of proteins. Marginal changes of the environment can severely affect the energy landscape of protein folding. However, despite the important role of chaperones on protein folding, less is known about chaperonal modulation of protein aggregation and fibrillation considering different classes of chaperones. We find that the pharmacological chaperone O4, the chemical chaperone proline as well as the protein chaperone serum amyloid P component (SAP) are inhibitors of the type 2 diabetes mellitus-related aggregation process of islet amyloid polypeptide (IAPP). By applying biophysical methods such as thioflavin T fluorescence spectroscopy, fluorescence anisotropy, total reflection Fourier-transform infrared spectroscopy, circular dichroism spectroscopy and atomic force microscopy we analyse and compare their inhibition mechanism. We demonstrate that the fibrillation reaction of human IAPP is strongly inhibited by formation of globular, amorphous assemblies by both, the pharmacological and the protein chaperones. We studied the inhibition mechanism under cell-like conditions by using the artificial crowding agents Ficoll 70 and sucrose. Under such conditions the suppressive effect of proline was decreased, whereas the pharmacological chaperone remains active.

  2. Fibril orientation redistribution induced by stretching of cellulose nanofibril hydrogels

    International Nuclear Information System (INIS)

    Josefsson, Gabriella; Gamstedt, E. Kristofer; Ahvenainen, Patrik; Mushi, Ngesa Ezekiel

    2015-01-01

    The mechanical performance of materials reinforced by cellulose nanofibrils is highly affected by the orientation of these fibrils. This paper investigates the nanofibril orientation distribution of films of partly oriented cellulose nanofibrils. Stripes of hydrogel films were subjected to different amount of strain and, after drying, examined with X-ray diffraction to obtain the orientation of the nanofibrils in the films, caused by the stretching. The cellulose nanofibrils had initially a random in-plane orientation in the hydrogel films and the strain was applied to the films before the nanofibrils bond tightly together, which occurs during drying. The stretching resulted in a reorientation of the nanofibrils in the films, with monotonically increasing orientation towards the load direction with increasing strain. Estimation of nanofibril reorientation by X-ray diffraction enables quantitative comparison of the stretch-induced orientation ability of different cellulose nanofibril systems. The reorientation of nanofibrils as a consequence of an applied strain is also predicted by a geometrical model of deformation of nanofibril hydrogels. Conversely, in high-strain cold-drawing of wet cellulose nanofibril materials, the enhanced orientation is promoted by slipping of the effectively stiff fibrils

  3. Automatic detection of atrial fibrillation in cardiac vibration signals.

    Science.gov (United States)

    Brueser, C; Diesel, J; Zink, M D H; Winter, S; Schauerte, P; Leonhardt, S

    2013-01-01

    We present a study on the feasibility of the automatic detection of atrial fibrillation (AF) from cardiac vibration signals (ballistocardiograms/BCGs) recorded by unobtrusive bedmounted sensors. The proposed system is intended as a screening and monitoring tool in home-healthcare applications and not as a replacement for ECG-based methods used in clinical environments. Based on BCG data recorded in a study with 10 AF patients, we evaluate and rank seven popular machine learning algorithms (naive Bayes, linear and quadratic discriminant analysis, support vector machines, random forests as well as bagged and boosted trees) for their performance in separating 30 s long BCG epochs into one of three classes: sinus rhythm, atrial fibrillation, and artifact. For each algorithm, feature subsets of a set of statistical time-frequency-domain and time-domain features were selected based on the mutual information between features and class labels as well as first- and second-order interactions among features. The classifiers were evaluated on a set of 856 epochs by means of 10-fold cross-validation. The best algorithm (random forests) achieved a Matthews correlation coefficient, mean sensitivity, and mean specificity of 0.921, 0.938, and 0.982, respectively.

  4. Biophysical aspects and novel treatments of atrial fibrillation.

    Science.gov (United States)

    Gigli, Lorenzo; Rosa, Gian M; Tagliasacchi, Maria I; Bonaventura, Aldo; Liberale, Luca; Montecucco, Fabrizio; Carbone, Federico; Bertero, Giovanni; Brunelli, Claudio

    2017-04-01

    Atrial fibrillation (AF) is a cardiac arrhythmia caused by various mechanisms, such as multiple re-entering wavelets, high frequency activity, and rotor sources. This narrative review was based on papers found on PubMed and MEDLINE up to May 2016. The search terms were "atrial fibrillation" in combination with "catheter ablation, pathophysiology, antiarrhythmic drugs". Antiarrhythmic drugs are the cornerstone of therapy in AF, but their efficacy and safety might have to be improved. In case of failure of pharmacologic therapies, other treatments can be considered. A better understanding of the important role of the pulmonary veins has led to new approaches, such as ablation procedures, which were initially only surgical, while percutaneous options were later added. However, these strategies may present various technical complications also when performed by skilled operators. A promising field of investigation is the genetics of AF, as highlighted by studies on the role of micro-RNA. Relevant improvement on the knowledge of the electrophysiological basis of genesis and maintenance of AF has been done in order to treat a very common arrhythmia, but further studies, as those in the genetics field, can open new challenging therapeutic horizons.

  5. Iodine replition, thyrotoxicosis and fibrillation in Isfahan, Iran

    International Nuclear Information System (INIS)

    Aminorroaya, Ashraf; Rohani, Sina; Sattari, Goshtasb; Haghighi, Sasan; Amini, Masoud

    2004-01-01

    Iodized salt was reintroduced in Iran in 1989. Just before distribution of iodized salt, thyrotoxicosis was observed in 3.7% of the patients with atrial fibrillation (AF) in university teaching hospitals in Isfahan, a centrally located city in Iran. As repletion of iodine may increase the rate of autoimmune thyroid diseases and toxic multinodular goiter, this study was designed to evaluate the rate of thyrotoxicosis in patients with AF in the same hospitals after about a decade of iodide salt consumption. In a case- control study with convenience sampling, 100 patients with AF and an equal number of age and sex matched subjects taking the same medications were selected as case and control groups, respectively in university hospitals in 1997. 8% of patients with atrial fibrillation had overt thyrotoxicosis versus one percent in the control group (odds ratio =8.6, 95% CI =6.5 to 10.7, p<0.02). Thyrotoxicosis in patients with AF was 8 times higher than in control group without AF. In comparison with the period before use of iodized salt, AF more than doubled (8%vs. 3.7%). Thyroid function should be evaluated in all patients older than 40 years of age with AF. The benefits of iodine supplementation are great, but more attention should be paid to the complications of iodine repletion, including thyrotoxicosis and its frequent accompaniment, AF. (author)

  6. What patients want and need to know about atrial fibrillation

    Directory of Open Access Journals (Sweden)

    McCabe PJ

    2011-11-01

    Full Text Available Pamela J McCabe Saint Mary's Hospital, Mayo Clinic, Rochester, MN, USA Abstract: Clinicians in a variety of settings are called upon to care for patients diagnosed with atrial fibrillation (AF, a common chronic condition that affects up to 3 million people in the USA. Evidence-based guidelines provide clinicians with direction for treatment of AF, but recommended content for educating patients and counseling about self-management of AF is not included in published guidelines. When patients believe they have a good understanding of AF they report fewer symptoms, perceive greater control over AF, and attribute less emotional distress to AF. Thus, providing patients with information about AF and how to manage it is important for promoting positive outcomes. The purpose of this article is to offer evidence-based recommendations for content to include in self-management education and counseling for patients with AF. Approaches for educating and counseling patients related to AF pathophysiology, the nature of AF (its cause, consequences, and trajectory, treatments, action plans, and symptom management, and managing the psychosocial challenges of living with AF, are discussed. Keywords: atrial fibrillation, patient education, self-management education, counseling

  7. Morphology and mechanical properties of multi-stranded amyloid fibrils probed by atomistic and coarse-grained simulations

    International Nuclear Information System (INIS)

    Yoon, Gwonchan; Lee, Myeongsang; Kim, Kyungwoo; In Kim, Jae; Joon Chang, Hyun; Baek, Inchul; Na, Sungsoo; Eom, Kilho

    2015-01-01

    Amyloid fibrils are responsible for pathogenesis of various diseases and exhibit the structural feature of an ordered, hierarchical structure such as multi-stranded helical structure. As the multi-strandedness of amyloid fibrils has recently been found to be highly correlated with their toxicity and infectivity, it is necessary to study how the hierarchical (i.e. multi-stranded) structure of amyloid fibril is formed. Moreover, although it has recently been reported that the nanomechanics of amyloid proteins plays a key role on the amyloid-induced pathogenesis, a critical role that the multi-stranded helical structure of the fibrils plays in their nanomechanical properties has not fully characterized. In this work, we characterize the morphology and mechanical properties of multi-stranded amyloid fibrils by using equilibrium molecular dynamics simulation and elastic network model. It is shown that the helical pitch of multi-stranded amyloid fibril is linearly proportional to the number of filaments comprising the amyloid fibril, and that multi-strandedness gives rise to improving the bending rigidity of the fibril. Moreover, we have also studied the morphology and mechanical properties of a single protofilament (filament) in order to understand the effect of cross-β structure and mutation on the structures and mechanical properties of amyloid fibrils. Our study sheds light on the underlying design principles showing how the multi-stranded amyloid fibril is formed and how the structure of amyloid fibrils governs their nanomechanical properties. (paper)

  8. The effect of point mutations on structure and mechanical properties of collagen-like fibril: A molecular dynamics study

    International Nuclear Information System (INIS)

    Marlowe, Ashley E.; Singh, Abhishek; Yingling, Yaroslava G.

    2012-01-01

    Understanding sequence dependent mechanical and structural properties of collagen fibrils is important for the development of artificial biomaterials for medical and nanotechnological applications. Moreover, point mutations are behind many collagen associated diseases, including Osteogenesis Imperfecta (OI). We conducted a combination of classical and steered atomistic molecular dynamics simulations to examine the effect of point mutations on structure and mechanical properties of short collagen fibrils which include mutations of glycine to alanine, aspartic acid, cysteine, and serine or mutations of hydroxyproline to arginine, asparagine, glutamine, and lysine. We found that all mutations disrupt structure and reduce strength of the collagen fibrils, which may affect the hierarchical packing of the fibrils. The glycine mutations were more detrimental to mechanical strength of the fibrils (WT > Ala > Ser > Cys > Asp) than that of hydroxyproline (WT > Arg > Gln > Asn > Lys). The clinical outcome for glycine mutations agrees well with the trend in reduction of fibril's tensile strength predicted by our simulations. Overall, our results suggest that the reduction in mechanical properties of collagen fibrils may be used to predict the clinical outcome of mutations. Highlights: ► All mutations disrupt structure and bonding pattern and reduce strength of the collagen fibrils. ► Gly based mutations are worst to mechanical integrity of fibrils than that of Hyp. ► Lys and Arg mutations most dramatically destabilize collagen fibril properties. ► Clinical outcome of mutations may be related to the reduced mechanical properties of fibrils.

  9. The effect of point mutations on structure and mechanical properties of collagen-like fibril: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Marlowe, Ashley E.; Singh, Abhishek; Yingling, Yaroslava G., E-mail: yara_yingling@ncsu.edu

    2012-12-01

    Understanding sequence dependent mechanical and structural properties of collagen fibrils is important for the development of artificial biomaterials for medical and nanotechnological applications. Moreover, point mutations are behind many collagen associated diseases, including Osteogenesis Imperfecta (OI). We conducted a combination of classical and steered atomistic molecular dynamics simulations to examine the effect of point mutations on structure and mechanical properties of short collagen fibrils which include mutations of glycine to alanine, aspartic acid, cysteine, and serine or mutations of hydroxyproline to arginine, asparagine, glutamine, and lysine. We found that all mutations disrupt structure and reduce strength of the collagen fibrils, which may affect the hierarchical packing of the fibrils. The glycine mutations were more detrimental to mechanical strength of the fibrils (WT > Ala > Ser > Cys > Asp) than that of hydroxyproline (WT > Arg > Gln > Asn > Lys). The clinical outcome for glycine mutations agrees well with the trend in reduction of fibril's tensile strength predicted by our simulations. Overall, our results suggest that the reduction in mechanical properties of collagen fibrils may be used to predict the clinical outcome of mutations. Highlights: Black-Right-Pointing-Pointer All mutations disrupt structure and bonding pattern and reduce strength of the collagen fibrils. Black-Right-Pointing-Pointer Gly based mutations are worst to mechanical integrity of fibrils than that of Hyp. Black-Right-Pointing-Pointer Lys and Arg mutations most dramatically destabilize collagen fibril properties. Black-Right-Pointing-Pointer Clinical outcome of mutations may be related to the reduced mechanical properties of fibrils.

  10. Functional Domain Driven Design

    OpenAIRE

    Herrera Guzmán, Sergio

    2016-01-01

    Las tecnologías están en constante expansión y evolución, diseñando nuevas técnicas para cumplir con su fin. En el desarrollo de software, las herramientas y pautas para la elaboración de productos software constituyen una pieza en constante evolución, necesarias para la toma de decisiones sobre los proyectos a realizar. Uno de los arquetipos para el desarrollo de software es el denominado Domain Driven Design, donde es importante conocer ampliamente el negocio que se desea modelar en form...

  11. Constellations-driven innovation

    DEFF Research Database (Denmark)

    Hansbøl, Mikala

    2011-01-01

    The paper presents a science and technology studies and actor-network-theory inspired approach to understanding the development and ongoing re-didactication and re-design of a Danish developed presentation tool called the Theme Board (Tematavlen.dk). It is argued that this approach provides a par...... a particularly useful point of departure for engaging in researching innovation and didactic design of digital teaching and learning instruments such as the Theme Board that are programmed and serviced 'in the sky'. I call this approach: constellation-driven innovations....

  12. Information-Driven Inspections

    International Nuclear Information System (INIS)

    Laughter, Mark D.; Whitaker, J. Michael; Lockwood, Dunbar

    2010-01-01

    New uranium enrichment capacity is being built worldwide in response to perceived shortfalls in future supply. To meet increasing safeguards responsibilities with limited resources, the nonproliferation community is exploring next-generation concepts to increase the effectiveness and efficiency of safeguards, such as advanced technologies to enable unattended monitoring of nuclear material. These include attribute measurement technologies, data authentication tools, and transmission and security methods. However, there are several conceptual issues with how such data would be used to improve the ability of a safeguards inspectorate such as the International Atomic Energy Agency (IAEA) to reach better safeguards conclusions regarding the activities of a State. The IAEA is pursuing the implementation of information-driven safeguards, whereby all available sources of information are used to make the application of safeguards more effective and efficient. Data from continuous, unattended monitoring systems can be used to optimize on-site inspection scheduling and activities at declared facilities, resulting in fewer, better inspections. Such information-driven inspections are the logical evolution of inspection planning - making use of all available information to enhance scheduled and randomized inspections. Data collection and analysis approaches for unattended monitoring systems can be designed to protect sensitive information while enabling information-driven inspections. A number of such inspections within a predetermined range could reduce inspection frequency while providing an equal or greater level of deterrence against illicit activity, all while meeting operator and technology holder requirements and reducing inspector and operator burden. Three options for using unattended monitoring data to determine an information-driven inspection schedule are to (1) send all unattended monitoring data off-site, which will require advances in data analysis techniques to

  13. Electrostatically Driven Nanoballoon Actuator.

    Science.gov (United States)

    Barzegar, Hamid Reza; Yan, Aiming; Coh, Sinisa; Gracia-Espino, Eduardo; Dunn, Gabriel; Wågberg, Thomas; Louie, Steven G; Cohen, Marvin L; Zettl, Alex

    2016-11-09

    We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.

  14. Advanced age and incidence of atrial fibrillation in the postoperative period of aortic valve replacement

    Science.gov (United States)

    Pivatto Júnior, Fernando; Teixeira Filho, Guaracy Fernandes; Sant'anna, João Ricardo Michelin; Py, Pablo Mondim; Prates, Paulo Roberto; Nesralla, Ivo Abrahão; Kalil, Renato Abdala Karam

    2014-01-01

    Objective This study aims to describe the correlation between age and occurrence of atrial fibrillation after aortic stenosis surgery in the elderly as well as evaluate the influence of atrial fibrillation on the incidence of strokes, hospital length of stay, and hospital mortality. Methods Cross-sectional retrospective study of > 70 year-old patients who underwent isolated aortic valve replacement. Results 348 patients were included in the study (mean age 76.8±4.6 years). Overall, post-operative atrial fibrillation was 32.8% (n=114), but it was higher in patients aged 80 years and older (42.9% versus 28.8% in patients aged 70-79 years, P=0.017). There was borderline significance for linear correlation between age and atrial fibrillation (P=0.055). Intensive Care Unit and hospital lengths of stay were significantly increased in atrial fibrillation (Patrial fibrillation. Conclusion Post-operative atrial fibrillation incidence in aortic valve replacement is high and correlates with age in patients aged 70 years and older and significantly more pronounced in patients aged 80 years. There was increased length of stay at Intensive Care Unit and hospital, but there was no increase in mortality or stroke. These data are important for planning prophylaxis and early treatment for this subgroup. PMID:24896162

  15. Longitudinal and concurrent dimensional changes of cellulose aggregate fibrils during sorption stages

    International Nuclear Information System (INIS)

    Lee, Jung Myoung; Pawlak, Joel J.; Heitmann, John A.

    2010-01-01

    Atomic force microscopy (AFM) studies of the dimensional changes of cellulose microfibril materials, called cellulose aggregate fibrils (approx. 100 μm x 3 μm x 300 nm), exposed to two distinct relative humidities of 80% and 23% for 24 h and then suddenly subjected to 50% RH and 23 deg. C show that the fibrils are responsive to the surrounding environments in a nonspecific fashion. AFM images (10 μm x 10 μm) of the individual straight cellulose aggregate fibrils were taken as a function of elapsed time during both desorption and adsorption of moisture. The longitudinal distance between discrete natural defects observed on the cellulose aggregate fibrils as well as the width, cross-sectional area, and height of the cellulose aggregate fibril were measured from the AFM images. The length of the cellulose aggregate fibrils was found to have reduced after exposure to either high or low relative humidity, and then placement in ambient conditions. Over time in ambient conditions, the cellulose aggregate fibrils progressively relaxed to their original length during both desorption and adsorption of moisture. However, the relaxation rate during adsorption was faster than that during desorption. The possible explanations for this phenomenon are discussed including the sample preparation method, volume conservation, entropy elasticity, and free volume theory. The changes in the width, height, and cross-sectional area are also discussed.

  16. Ionic Strength Modulation of the Free Energy Landscape of Aβ40 Peptide Fibril Formation.

    Science.gov (United States)

    Abelein, Axel; Jarvet, Jüri; Barth, Andreas; Gräslund, Astrid; Danielsson, Jens

    2016-06-01

    Protein misfolding and formation of cross-β structured amyloid fibrils are linked to many neurodegenerative disorders. Although recently developed quantitative approaches have started to reveal the molecular nature of self-assembly and fibril formation of proteins and peptides, it is yet unclear how these self-organization events are precisely modulated by microenvironmental factors, which are known to strongly affect the macroscopic aggregation properties. Here, we characterize the explicit effect of ionic strength on the microscopic aggregation rates of amyloid β peptide (Aβ40) self-association, implicated in Alzheimer's disease. We found that physiological ionic strength accelerates Aβ40 aggregation kinetics by promoting surface-catalyzed secondary nucleation reactions. This promoted catalytic effect can be assigned to shielding of electrostatic repulsion between monomers on the fibril surface or between the fibril surface itself and monomeric peptides. Furthermore, we observe the formation of two different β-structured states with similar but distinct spectroscopic features, which can be assigned to an off-pathway immature state (Fβ*) and a mature stable state (Fβ), where salt favors formation of the Fβ fibril morphology. Addition of salt to preformed Fβ* accelerates transition to Fβ, underlining the dynamic nature of Aβ40 fibrils in solution. On the basis of these results we suggest a model where salt decreases the free-energy barrier for Aβ40 folding to the Fβ state, favoring the buildup of the mature fibril morphology while omitting competing, energetically less favorable structural states.

  17. In vitro fibrillization of Alzheimer’s amyloid-β peptide (1-42)

    Energy Technology Data Exchange (ETDEWEB)

    Tiiman, Ann [Department of Gene Technology, Tallinn University of Technology, Tallinn 12618 (Estonia); Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, Stockholm, 106 91 (Sweden); Krishtal, Jekaterina; Palumaa, Peep; Tõugu, Vello, E-mail: vello.tougu@ttu.ee [Department of Gene Technology, Tallinn University of Technology, Tallinn 12618 (Estonia)

    2015-09-15

    The amyloid deposition in the form of extracellular fibrillar aggregates of amyloid-β (Aβ) peptide is a critical pathological event in Alzheimer’s disease. Here, we report a systematic investigation of the effects of environmental factors on the kinetics of Aβ fibrillization in vitro. The effects of Aβ42 peptide concentration, temperature, pH, added solvents and the ratio of Aβ40 and Aβ42 on the peptide fibrillization under agitated conditions was studied. The analysis show that the rate of fibril growth by monomer addition is not limited by diffusion but by rearrangement in the monomer structure, which is enhanced by low concentrations of fluorinated alcohols and characterized by the activation energy of 12 kcal/mol. Fibrillization rate decreases at pH values below 7.0 where simultaneous protonation of His 13 and 14 inhibits fibril formation. The lag period for Aβ42 was only twofold shorter and the fibril growth rate twofold faster than those of Aβ40. Lag period was shortened and the fibrillization rate was increased only at 90% content of Aβ42.

  18. MAK33 antibody light chain amyloid fibrils are similar to oligomeric precursors.

    Directory of Open Access Journals (Sweden)

    Manuel Hora

    Full Text Available Little structural information is available so far on amyloid fibrils consisting of immunoglobulin light chains. It is not understood which features of the primary sequence of the protein result in fibril formation. We report here MAS solid-state NMR studies to identify the structured core of κ-type variable domain light chain fibrils. The core contains residues of the CDR2 and the β-strands D, E, F and G of the native immunoglobulin fold. The assigned core region of the fibril is distinct in comparison to the core identified in a previous solid-state NMR study on AL-09 by Piehl at. al, suggesting that VL fibrils can adopt different topologies. In addition, we investigated a soluble oligomeric intermediate state, previously termed the alternatively folded state (AFS, using NMR and FTIR spectroscopy. The NMR oligomer spectra display a high degree of similarity when compared to the fibril spectra, indicating a high structural similarity of the two aggregation states. Based on comparison to the native state NMR chemical shifts, we suggest that fibril formation via domain-swapping seems unlikely. Moreover, we used our results to test the quality of different amyloid prediction algorithms.

  19. Structure–mechanics relationships of collagen fibrils in the osteogenesis imperfecta mouse model

    Science.gov (United States)

    Andriotis, O. G.; Chang, S. W.; Vanleene, M.; Howarth, P. H.; Davies, D. E.; Shefelbine, S. J.; Buehler, M. J.; Thurner, P. J.

    2015-01-01

    The collagen molecule, which is the building block of collagen fibrils, is a triple helix of two α1(I) chains and one α2(I) chain. However, in the severe mouse model of osteogenesis imperfecta (OIM), deletion of the COL1A2 gene results in the substitution of the α2(I) chain by one α1(I) chain. As this substitution severely impairs the structure and mechanics of collagen-rich tissues at the tissue and organ level, the main aim of this study was to investigate how the structure and mechanics are altered in OIM collagen fibrils. Comparing results from atomic force microscopy imaging and cantilever-based nanoindentation on collagen fibrils from OIM and wild-type (WT) animals, we found a 33% lower indentation modulus in OIM when air-dried (bound water present) and an almost fivefold higher indentation modulus in OIM collagen fibrils when fully hydrated (bound and unbound water present) in phosphate-buffered saline solution (PBS) compared with WT collagen fibrils. These mechanical changes were accompanied by an impaired swelling upon hydration within PBS. Our experimental and atomistic simulation results show how the structure and mechanics are altered at the individual collagen fibril level as a result of collagen gene mutation in OIM. We envisage that the combination of experimental and modelling approaches could allow mechanical phenotyping at the collagen fibril level of virtually any alteration of collagen structure or chemistry. PMID:26468064

  20. A biomechanical model for fibril recruitment: Evaluation in tendons and arteries.

    Science.gov (United States)

    Bevan, Tim; Merabet, Nadege; Hornsby, Jack; Watton, Paul N; Thompson, Mark S

    2018-06-06

    Simulations of soft tissue mechanobiological behaviour are increasingly important for clinical prediction of aneurysm, tendinopathy and other disorders. Mechanical behaviour at low stretches is governed by fibril straightening, transitioning into load-bearing at recruitment stretch, resulting in a tissue stiffening effect. Previous investigations have suggested theoretical relationships between stress-stretch measurements and recruitment probability density function (PDF) but not derived these rigorously nor evaluated these experimentally. Other work has proposed image-based methods for measurement of recruitment but made use of arbitrary fibril critical straightness parameters. The aim of this work was to provide a sound theoretical basis for estimating recruitment PDF from stress-stretch measurements and to evaluate this relationship using image-based methods, clearly motivating the choice of fibril critical straightness parameter in rat tail tendon and porcine artery. Rigorous derivation showed that the recruitment PDF may be estimated from the second stretch derivative of the first Piola-Kirchoff tissue stress. Image-based fibril recruitment identified the fibril straightness parameter that maximised Pearson correlation coefficients (PCC) with estimated PDFs. Using these critical straightness parameters the new method for estimating recruitment PDF showed a PCC with image-based measures of 0.915 and 0.933 for tendons and arteries respectively. This method may be used for accurate estimation of fibril recruitment PDF in mechanobiological simulation where fibril-level mechanical parameters are important for predicting cell behaviour. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Lysosomal enzyme cathepsin B enhances the aggregate forming activity of exogenous α-synuclein fibrils.

    Science.gov (United States)

    Tsujimura, Atsushi; Taguchi, Katsutoshi; Watanabe, Yoshihisa; Tatebe, Harutsugu; Tokuda, Takahiko; Mizuno, Toshiki; Tanaka, Masaki

    2015-01-01

    The formation of intracellular aggregates containing α-synuclein (α-Syn) is one of the key steps in the progression of Parkinson's disease and dementia with Lewy bodies. Recently, it was reported that pathological α-Syn fibrils can undergo cell-to-cell transmission and form Lewy body-like aggregates. However, little is known about how they form α-Syn aggregates from fibril seeds. Here, we developed an assay to study the process of aggregate formation using fluorescent protein-tagged α-Syn-expressing cells and examined the aggregate forming activity of exogenous α-Syn fibrils. α-Syn fibril-induced formation of intracellular aggregates was suppressed by a cathepsin B specific inhibitor, but not by a cathepsin D inhibitor. α-Syn fibrils pretreated with cathepsin B in vitro enhanced seeding activity in cells. Knockdown of cathepsin B also reduced fibril-induced aggregate formation. Moreover, using LAMP-1 immunocytochemistry and live-cell imaging, we observed that these aggregates initially occurred in the lysosome. They then rapidly grew larger and moved outside the boundary of the lysosome within one day. These results suggest that the lysosomal protease cathepsin B is involved in triggering intracellular aggregate formation by α-Syn fibrils. Copyright © 2015. Published by Elsevier Inc.

  2. Stroke prevention in hospitalized patients with atrial fibrillation: a population-based study.

    Science.gov (United States)

    Nagpal, Seema; Anderson, David; Putnam, Wayne; Flowerdew, Gordon; Gardner, Martin; Cox, Jafna

    2003-01-01

    Oral anticoagulants reduce the incidence of stroke by 68%, yet suboptimal use has been documented in surveys of patients with atrial fibrillation. The present study examined current patterns of anticoagulant use for patients hospitalized with atrial fibrillation across an entire health care system. Improving Cardiovascular Outcomes in Nova Scotia (ICONS) is a prospective cohort study involving all patients hospitalized in Nova Scotia with atrial fibrillation, among other conditions. Consecutive inpatients with atrial fibrillation from October 15, 1997 to October 14, 1998 were studied. Detailed demographic and clinical data were collected and the proportion of patients using antithrombotic therapy was tabulated by risk category. Multivariate logistic regression was used to assess the relationship of various demographic and clinical factors with the use of antithrombotic agents. There were 2202 patients hospitalized with atrial fibrillation; 644 admitted specifically for this condition. Only 21% of patients admitted with atrial fibrillation were on warfarin sodium at admission and this increased by time of discharge. Diabetes was negatively correlated with warfarin sodium use. Histories of prosthetic valve replacement, stroke/transient ischemic attack, and heart failure were positively associated with anticoagulant use on admission. Patients with prosthetic valve replacement, heart failure, or hyperlipidemia were most likely to receive anticoagulants at discharge. Antithrombotic agents remain underused by patients with atrial fibrillation. While higher risk patients are generally targeted, this is not invariably the case; thus, diabetics remain under treated. Further work is needed to explain such anomalous practice and promote optimal antithrombotic therapy use.

  3. Cardiac monitoring for detection of atrial fibrillation after TIA: A systematic review and meta-analysis.

    Science.gov (United States)

    Korompoki, Eleni; Del Giudice, Angela; Hillmann, Steffi; Malzahn, Uwe; Gladstone, David J; Heuschmann, Peter; Veltkamp, Roland

    2017-01-01

    Background and purpose The detection rate of atrial fibrillation has not been studied specifically in transient ischemic attack (TIA) patients although extrapolation from ischemic stroke may be inadequate. We conducted a systematic review and meta-analysis to determine the rate of newly diagnosed atrial fibrillation using different methods of ECG monitoring in TIA. Methods A comprehensive literature search was performed following a pre-specified protocol the PRISMA statement. Prospective observational studies and randomized controlled trials were considered that included TIA patients who underwent cardiac monitoring for >12 h. Primary outcome was frequency of detection of atrial fibrillation ≥30 s. Analyses of subgroups and of duration and type of monitoring were performed. Results Seventeen studies enrolling 1163 patients were included. The pooled atrial fibrillation detection rate for all methods was 4% (95% CI: 2-7%). Yield of monitoring was higher in selected (higher age, more extensive testing for arrhythmias before enrolment, or presumed cardioembolic/cryptogenic cause) than in unselected cohorts (7% vs 3%). Pooled mean atrial fibrillation detection rates rose with duration of monitoring: 4% (24 h), 5% (24 h to 7 days) and 6% (>7 days), respectively. Yield of non-invasive was significantly lower than that of invasive monitoring (4% vs. 11%). Significant heterogeneity was observed among studies (I 2 =60.61%). Conclusion This first meta-analysis of atrial fibrillation detection in TIA patients finds a lower atrial fibrillation detection rate in TIA than reported for IS and TIA cohorts in previous meta-analyses. Prospective studies are needed to determine actual prevalence of atrial fibrillation and optimal diagnostic procedure for atrial fibrillation detection in TIA.

  4. Atrial fibrillation screening in pharmacies using an iPhone ECG: a qualitative review of implementation.

    Science.gov (United States)

    Lowres, Nicole; Krass, Ines; Neubeck, Lis; Redfern, Julie; McLachlan, Andrew J; Bennett, Alexandra A; Freedman, S Ben

    2015-12-01

    Atrial fibrillation guidelines advocate screening to identify undiagnosed atrial fibrillation. Community pharmacies may provide an opportunistic venue for such screening. To explore the experience of implementing an atrial fibrillation screening service from the pharmacist's perspective including: the process of study implementation; the perceived benefits; the barriers and enablers; and the challenges for future sustainability of atrial fibrillation screening within pharmacies. Setting Interviews were conducted face-to-face in the pharmacy or via telephone, according to pharmacist preference. The 'SEARCH-AF study' screened 1000 pharmacy customers aged ≥65 years using an iPhone electrocardiogram, identifying 1.5 % with undiagnosed atrial fibrillation. Nine pharmacists took part in semi-structured interviews. Interviews were transcribed in full and thematically analysed. Qualitative analysis of the experience of implementing an AF screening service from the pharmacist's perspective. Four broad themes relating to service provision were identified: (1) interest and engagement in atrial fibrillation screening by pharmacists, customers, and doctors with the novel, easy-to-use electrocardiogram technology serving as an incentive to undergo screening and an education tool for pharmacists to use with customers; (2) perceived benefits to the pharmacist including increased job satisfaction, improvement in customer relations and pharmacy profile by fostering enhanced customer care and the educational role of pharmacists; (3) implementation barriers including managing workflow, and enablers such as personal approaches for recruitment, and allocating time to discuss screening process and fears; and, (4) potential for sustainable future implementation including remuneration linked to government or pharmacy incentives, combined cardiovascular screening, and automating sections of risk-assessments using touch-screen technology. Atrial fibrillation screening in pharmacies is well

  5. The Effect of Milk Constituents and Crowding Agents on Amyloid Fibril Formation by κ-Casein.

    Science.gov (United States)

    Liu, Jihua; Dehle, Francis C; Liu, Yanqin; Bahraminejad, Elmira; Ecroyd, Heath; Thorn, David C; Carver, John A

    2016-02-17

    When not incorporated into the casein micelle, κ-casein, a major milk protein, rapidly forms amyloid fibrils at physiological pH and temperature. In this study, the effects of milk components (calcium, lactose, lipids, and heparan sulfate) and crowding agents on reduced and carboxymethylated (RCM) κ-casein fibril formation was investigated using far-UV circular dichroism spectroscopy, thioflavin T binding assays, and transmission electron microscopy. Longer-chain phosphatidylcholine lipids, which form the lining of milk ducts and milk fat globules, enhanced RCM κ-casein fibril formation irrespective of whether the lipids were in a monomeric or micellar state, whereas shorter-chain phospholipids and triglycerides had little effect. Heparan sulfate, a component of the milk fat globule membrane and catalyst of amyloid deposition in extracellular tissue, had little effect on the kinetics of RCM κ-casein fibril formation. Major nutritional components such as calcium and lactose also had no significant effect. Macromolecular crowding enhances protein-protein interactions, but in contrast to other fibril-forming species, the extent of RCM κ-casein fibril formation was reduced by the presence of a variety of crowding agents. These data are consistent with a mechanism of κ-casein fibril formation in which the rate-determining step is dissociation from the oligomer to give the highly amyloidogenic monomer. We conclude that the interaction of κ-casein with membrane-associated phospholipids along its secretory pathway may contribute to the development of amyloid deposits in mammary tissue. However, the formation of spherical oligomers such as casein micelles is favored over amyloid fibrils in the crowded environment of milk, within which the occurrence of amyloid fibrils is low.

  6. Evidence for novel beta-sheet structures in Iowa mutant beta-amyloid fibrils.

    Science.gov (United States)

    Tycko, Robert; Sciarretta, Kimberly L; Orgel, Joseph P R O; Meredith, Stephen C

    2009-07-07

    Asp23-to-Asn mutation within the coding sequence of beta-amyloid, called the Iowa mutation, is associated with early onset, familial Alzheimer's disease and cerebral amyloid angiopathy, in which patients develop neuritic plaques and massive vascular deposition predominantly of the mutant peptide. We examined the mutant peptide, D23N-Abeta40, by electron microscopy, X-ray diffraction, and solid-state NMR spectroscopy. D23N-Abeta40 forms fibrils considerably faster than the wild-type peptide (k = 3.77 x 10(-3) min(-1) and 1.07 x 10(-4) min(-1) for D23N-Abeta40 and the wild-type peptide WT-Abeta40, respectively) and without a lag phase. Electron microscopy shows that D23N-Abeta40 forms fibrils with multiple morphologies. X-ray fiber diffraction shows a cross-beta pattern, with a sharp reflection at 4.7 A and a broad reflection at 9.4 A, which is notably smaller than the value for WT-Abeta40 fibrils (10.4 A). Solid-state NMR measurements indicate molecular level polymorphism of the fibrils, with only a minority of D23N-Abeta40 fibrils containing the in-register, parallel beta-sheet structure commonly found in WT-Abeta40 fibrils and most other amyloid fibrils. Antiparallel beta-sheet structures in the majority of fibrils are indicated by measurements of intermolecular distances through (13)C-(13)C and (15)N-(13)C dipole-dipole couplings. An intriguing possibility exists that there is a relationship between the aberrant structure of D23N-Abeta40 fibrils and the unusual vasculotropic clinical picture in these patients.

  7. Heat driven pulse pump

    Science.gov (United States)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  8. Plasma-driven liners

    International Nuclear Information System (INIS)

    Kilic, H.; Linhart, J.G.; Bortolotti, A.; Nardi, V.

    1992-01-01

    The deposition of thermal energy by laser or ion beams in an ablator is capable of producing a very large acceleration of the adjacent pusher - for power densities of 100 Terrawatts/cm 2 , ablator pressure in the range of 10 Mbar is attainable. In the case of a plasma drive such driving pressures and accelerations are not directly possible. When a snowplough (SP) is used to accelerate a thin liner, the driving pressure is that of the magnetic piston pushing the SP, i.e. at most 0.1 Mbar. However, the initial radius r 0 of the liner can be a few centimeters, instead of 1 (mm) as in the case in direct pellet implosions. In order to compete with the performance of the beam-driven liners, the plasma drive must demonstrate that a) thin liner retains a high density during the implosion (lasting a fraction of a μsec); b) radial compression ratio r 0 /r min of the order of 100 can be attained. It is also attractive to consider the staging of two or more liners in order to get sharpening and amplifications of the pressure and/or radiation pulse. If a) and b) are verified then the final pressures produced will be comparable with those of the beam-driven implosions. (author) 5 refs., 3 figs

  9. Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

    International Nuclear Information System (INIS)

    Papi, M.; Paoletti, P.; Geraghty, B.; Akhtar, R.

    2014-01-01

    We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions of the sclera. The mean fibril diameter, elastic modulus and dissipation increased from the posterior to the anterior region. Collagen fibril diameter correlated linearly with elastic modulus. Our data matches the known macroscopic mechanical behavior of the sclera. We propose that PFQNM has significant potential in ocular biomechanics and biophysics research

  10. How does domain replacement affect fibril formation of the rabbit/human prion proteins.

    Directory of Open Access Journals (Sweden)

    Xu Yan

    Full Text Available It is known that in vivo human prion protein (PrP have the tendency to form fibril deposits and are associated with infectious fatal prion diseases, while the rabbit PrP does not readily form fibrils and is unlikely to cause prion diseases. Although we have previously demonstrated that amyloid fibrils formed by the rabbit PrP and the human PrP have different secondary structures and macromolecular crowding has different effects on fibril formation of the rabbit/human PrPs, we do not know which domains of PrPs cause such differences. In this study, we have constructed two PrP chimeras, rabbit chimera and human chimera, and investigated how domain replacement affects fibril formation of the rabbit/human PrPs.As revealed by thioflavin T binding assays and Sarkosyl-soluble SDS-PAGE, the presence of a strong crowding agent dramatically promotes fibril formation of both chimeras. As evidenced by circular dichroism, Fourier transform infrared spectroscopy, and proteinase K digestion assays, amyloid fibrils formed by human chimera have secondary structures and proteinase K-resistant features similar to those formed by the human PrP. However, amyloid fibrils formed by rabbit chimera have proteinase K-resistant features and secondary structures in crowded physiological environments different from those formed by the rabbit PrP, and secondary structures in dilute solutions similar to the rabbit PrP. The results from transmission electron microscopy show that macromolecular crowding caused human chimera but not rabbit chimera to form short fibrils and non-fibrillar particles.We demonstrate for the first time that the domains beyond PrP-H2H3 (β-strand 1, α-helix 1, and β-strand 2 have a remarkable effect on fibrillization of the rabbit PrP but almost no effect on the human PrP. Our findings can help to explain why amyloid fibrils formed by the rabbit PrP and the human PrP have different secondary structures and why macromolecular crowding has different

  11. Tensile properties of human collagen fibrils and fascicles are insensitive to environmental salts

    DEFF Research Database (Denmark)

    Svensson, René B; Hassenkam, Tue; Grant, Colin A

    2010-01-01

    loading direction of tendon is along its longitudinal axis. Thus, in this study, we focus on the tensile mechanical properties of two hierarchical levels from human patellar tendon, namely: individual collagen fibrils and fascicles. Investigations on collagen fibrils and fascicles were made at pH 7...... was observed at the highest phosphate-buffered saline concentration for both the fibrils and fascicles, indicating a stabilizing effect of ionic screening, but changes were much less than reported for radial compression. Due to the small magnitude of the effects, the tensile mechanical properties of collagen...

  12. Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

    Energy Technology Data Exchange (ETDEWEB)

    Papi, M. [Institute of Physics, Università Cattolica del Sacro Cuore, Largo F.Vito 1, 00168 Rome (Italy); Paoletti, P. [Centre for Engineering Dynamics, School of Engineering, Brownlow Hill, Liverpool, L69 3GH (United Kingdom); Geraghty, B.; Akhtar, R. [Centre for Materials and Structures, School of Engineering, Brownlow Hill, Liverpool, L69 3GH (United Kingdom)

    2014-03-10

    We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions of the sclera. The mean fibril diameter, elastic modulus and dissipation increased from the posterior to the anterior region. Collagen fibril diameter correlated linearly with elastic modulus. Our data matches the known macroscopic mechanical behavior of the sclera. We propose that PFQNM has significant potential in ocular biomechanics and biophysics research.

  13. Angiotensinogen and ACE gene polymorphisms and risk of atrial fibrillation in the general population

    DEFF Research Database (Denmark)

    Ravn, Lasse Steen; Benn, Marianne; Nordestgaard, Børge

    2008-01-01

    Objectives The renin-angiotensin system may play a role in the pathogenesis of atrial fibrillation, and renin-angiotensin system blockers reduce the risk of atrial fibrillation. We hypothesized that polymorphisms in the angiotensinogen and angiotensin-converting enzyme (ACE) genes encoding proteins...... in this system predict risk of atrial fibrillation. Methods and results We genotyped 9235 individuals from the Danish general population, The Copenhagen City Heart Study, for the a-20c, g-6a, T174M, and M235T polymorphisms in the angiotensinogen gene and the insertion/deletion (I/D) polymorphism in the ACE gene...

  14. Apixaban versus warfarin in patients with atrial fibrillation.

    Science.gov (United States)

    Granger, Christopher B; Alexander, John H; McMurray, John J V; Lopes, Renato D; Hylek, Elaine M; Hanna, Michael; Al-Khalidi, Hussein R; Ansell, Jack; Atar, Dan; Avezum, Alvaro; Bahit, M Cecilia; Diaz, Rafael; Easton, J Donald; Ezekowitz, Justin A; Flaker, Greg; Garcia, David; Geraldes, Margarida; Gersh, Bernard J; Golitsyn, Sergey; Goto, Shinya; Hermosillo, Antonio G; Hohnloser, Stefan H; Horowitz, John; Mohan, Puneet; Jansky, Petr; Lewis, Basil S; Lopez-Sendon, Jose Luis; Pais, Prem; Parkhomenko, Alexander; Verheugt, Freek W A; Zhu, Jun; Wallentin, Lars

    2011-09-15

    Vitamin K antagonists are highly effective in preventing stroke in patients with atrial fibrillation but have several limitations. Apixaban is a novel oral direct factor Xa inhibitor that has been shown to reduce the risk of stroke in a similar population in comparison with aspirin. In this randomized, double-blind trial, we compared apixaban (at a dose of 5 mg twice daily) with warfarin (target international normalized ratio, 2.0 to 3.0) in 18,201 patients with atrial fibrillation and at least one additional risk factor for stroke. The primary outcome was ischemic or hemorrhagic stroke or systemic embolism. The trial was designed to test for noninferiority, with key secondary objectives of testing for superiority with respect to the primary outcome and to the rates of major bleeding and death from any cause. The median duration of follow-up was 1.8 years. The rate of the primary outcome was 1.27% per year in the apixaban group, as compared with 1.60% per year in the warfarin group (hazard ratio with apixaban, 0.79; 95% confidence interval [CI], 0.66 to 0.95; P<0.001 for noninferiority; P=0.01 for superiority). The rate of major bleeding was 2.13% per year in the apixaban group, as compared with 3.09% per year in the warfarin group (hazard ratio, 0.69; 95% CI, 0.60 to 0.80; P<0.001), and the rates of death from any cause were 3.52% and 3.94%, respectively (hazard ratio, 0.89; 95% CI, 0.80 to 0.99; P=0.047). The rate of hemorrhagic stroke was 0.24% per year in the apixaban group, as compared with 0.47% per year in the warfarin group (hazard ratio, 0.51; 95% CI, 0.35 to 0.75; P<0.001), and the rate of ischemic or uncertain type of stroke was 0.97% per year in the apixaban group and 1.05% per year in the warfarin group (hazard ratio, 0.92; 95% CI, 0.74 to 1.13; P=0.42). In patients with atrial fibrillation, apixaban was superior to warfarin in preventing stroke or systemic embolism, caused less bleeding, and resulted in lower mortality. (Funded by Bristol-Myers Squibb

  15. Dual Antithrombotic Therapy with Dabigatran after PCI in Atrial Fibrillation.

    Science.gov (United States)

    Cannon, Christopher P; Bhatt, Deepak L; Oldgren, Jonas; Lip, Gregory Y H; Ellis, Stephen G; Kimura, Takeshi; Maeng, Michael; Merkely, Bela; Zeymer, Uwe; Gropper, Savion; Nordaby, Matias; Kleine, Eva; Harper, Ruth; Manassie, Jenny; Januzzi, James L; Ten Berg, Jurrien M; Steg, P Gabriel; Hohnloser, Stefan H

    2017-10-19

    Triple antithrombotic therapy with warfarin plus two antiplatelet agents is the standard of care after percutaneous coronary intervention (PCI) for patients with atrial fibrillation, but this therapy is associated with a high risk of bleeding. In this multicenter trial, we randomly assigned 2725 patients with atrial fibrillation who had undergone PCI to triple therapy with warfarin plus a P2Y 12 inhibitor (clopidogrel or ticagrelor) and aspirin (for 1 to 3 months) (triple-therapy group) or dual therapy with dabigatran (110 mg or 150 mg twice daily) plus a P2Y 12 inhibitor (clopidogrel or ticagrelor) and no aspirin (110-mg and 150-mg dual-therapy groups). Outside the United States, elderly patients (≥80 years of age; ≥70 years of age in Japan) were randomly assigned to the 110-mg dual-therapy group or the triple-therapy group. The primary end point was a major or clinically relevant nonmajor bleeding event during follow-up (mean follow-up, 14 months). The trial also tested for the noninferiority of dual therapy with dabigatran (both doses combined) to triple therapy with warfarin with respect to the incidence of a composite efficacy end point of thromboembolic events (myocardial infarction, stroke, or systemic embolism), death, or unplanned revascularization. The incidence of the primary end point was 15.4% in the 110-mg dual-therapy group as compared with 26.9% in the triple-therapy group (hazard ratio, 0.52; 95% confidence interval [CI], 0.42 to 0.63; Pdual-therapy group as compared with 25.7% in the corresponding triple-therapy group, which did not include elderly patients outside the United States (hazard ratio, 0.72; 95% CI, 0.58 to 0.88; Pdual-therapy groups combined as compared with 13.4% in the triple-therapy group (hazard ratio, 1.04; 95% CI, 0.84 to 1.29; P=0.005 for noninferiority). The rate of serious adverse events did not differ significantly among the groups. Among patients with atrial fibrillation who had undergone PCI, the risk of bleeding was

  16. Deposition, clearance, and shortening of Kevlar para-aramid fibrils in acute, subchronic, and chronic inhalation studies in rats.

    Science.gov (United States)

    Kelly, D P; Merriman, E A; Kennedy, G L; Lee, K P

    1993-10-01

    The deposition and clearance of lung-deposited Kevlar para-aramid fibrils (subfibers) have been investigated as part of a subchronic and chronic inhalation toxicity testing program. Fibrils recovered from lung tissue in para-aramid-exposed Sprague-Dawley rats were microscopically counted and measured after exposures to airborne fibrils which were about 12 microns median length (ML) and < 0.3 micron median diameter. In each of three studies lung-recovered fibrils were progressively shorter with increasing residence time in the lungs. Twenty-eight days after a single 6-hr exposure at 400 respirable fibrils per cubic centimeter (f/cm3) the ML of recovered fibrils decreased to about 5 microns. Twenty-four months after a 3-week exposure to 25 or 400 f/cm3, fibrils reached about 2 microns ML. After 2 years of continuous exposure at 2.5, 25, or 100 f/cm3 or 1 year exposure plus 1 year recovery at 400 f/cm3, fibril ML approached 4 microns. In the 2-year study, the lung-fiber accumulation rate/exposure concentration was similar for the three highest concentrations and was about 3 x greater than that seen at 2.5 f/cm3, indicating that concentrations of about 25 f/cm3 or more may overwhelm clearance mechanisms. Time required for fibrils to be reduced to < 5 microns in the lung was markedly less at lower exposure concentration and shorter exposure time. The primary shortening mechanism is proposed to be long fibril cutting by enzymatic attack at fibril defects. However, length-selective fibril deposition and clearance may contribute to shortening in the first few days after exposure. The enzymatic cutting hypothesis is supported by measured increases in numbers of short fibers following cessation of exposures, continued shortening of the fibril length distribution up to 2 years following exposure, and in vitro fibril shortening after 3 months in a proteolytic enzyme preparation. The conclusion is that para-aramid fibrils are less durable in the lungs of rats than expected from

  17. Consistent model driven architecture

    Science.gov (United States)

    Niepostyn, Stanisław J.

    2015-09-01

    The goal of the MDA is to produce software systems from abstract models in a way where human interaction is restricted to a minimum. These abstract models are based on the UML language. However, the semantics of UML models is defined in a natural language. Subsequently the verification of consistency of these diagrams is needed in order to identify errors in requirements at the early stage of the development process. The verification of consistency is difficult due to a semi-formal nature of UML diagrams. We propose automatic verification of consistency of the series of UML diagrams originating from abstract models implemented with our consistency rules. This Consistent Model Driven Architecture approach enables us to generate automatically complete workflow applications from consistent and complete models developed from abstract models (e.g. Business Context Diagram). Therefore, our method can be used to check practicability (feasibility) of software architecture models.

  18. Employee-driven innovation

    DEFF Research Database (Denmark)

    Kesting, Peter; Ulhøi, John Parm

    2015-01-01

    Purpose – The purpose of this paper is to outline the “grand structure” of the phenomenon in order to identify both the underlying processes and core drivers of employee-driven innovation (EDI). Design/methodology/approach – This is a conceptual paper. It particularly applies the insights...... of contemporary research on routine and organizational decision making to the specific case of EDI. Findings – The main result of the paper is that, from a theoretical point of view, it makes perfect sense to involve ordinary employees in innovation decisions. However, it is also outlined that naıve or ungoverned...... participation is counterproductive, and that it is quite difficult to realize the hidden potential in a supportive way. Research limitations/implications – The main implication is that basic mechanisms for employee participation also apply to innovation decisions, although often in a different way. However...

  19. Temperature-Driven Convection

    Science.gov (United States)

    Bohan, Richard J.; Vandegrift, Guy

    2003-02-01

    Warm air aloft is stable. This explains the lack of strong winds in a warm front and how nighttime radiative cooling can lead to motionless air that can trap smog. The stability of stratospheric air can be attributed to the fact that it is heated from above as ultraviolet radiation strikes the ozone layer. On the other hand, fluid heated from below is unstable and can lead to Bernard convection cells. This explains the generally turbulent nature of the troposphere, which receives a significant fraction of its heat directly from the Earth's warmer surface. The instability of cold fluid aloft explains the violent nature of a cold front, as well as the motion of Earth's magma, which is driven by radioactive heating deep within the Earth's mantle. This paper describes how both effects can be demonstrated using four standard beakers, ice, and a bit of food coloring.

  20. Emotion-driven level generation

    OpenAIRE

    Togelius, Julian; Yannakakis, Georgios N.

    2016-01-01

    This chapter examines the relationship between emotions and level generation. Grounded in the experience-driven procedural content generation framework we focus on levels and introduce a taxonomy of approaches for emotion-driven level generation. We then review four characteristic level generators of our earlier work that exemplify each one of the approaches introduced. We conclude the chapter with our vision on the future of emotion-driven level generation.

  1. Overweight and obesity in patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Boriani, Giuseppe; Laroche, Cécile; Diemberger, Igor

    2018-01-01

    BACKGROUND: The impact of overweight and obesity on outcomes in "real world" patients with atrial fibrillation (AF) is not fully defined. Second, sex differences in AF outcomes may also exist. METHODS AND RESULTS: The aim was to investigate outcomes at 1-year follow-up for AF patients enrolled...... a normal BMI, 1084(42.7%) were overweight and 736(29.0%) were obese. Obese patients were younger and with more prevalent diabetes mellitus and hypertension (p ... in the EORP-AF Registry, according to BMI (kg/m2 ), comparing patients with normal BMI (18.5 to obesity (≥30 kg/m2 ), in relation to sex differences. Among 2,540 EORP AF patients (38.9% female; median age 69) with 1 year follow-up data available, 720(28.3%) had...

  2. Antithrombotic treatment in elderly patients with atrial fibrillation.

    Science.gov (United States)

    Suárez Fernández, C; Camafort, M; Cepeda Rodrigo, J M; Díez-Manglano, J; Formiga, F; Pose Reino, A; Tiberio, G; Mostaza, J M

    2015-04-01

    Atrial fibrillation (AF) in the elderly is a complex condition due to the high number of frequently associated comorbidities, such as cardiovascular and kidney disease, cognitive disorders, falls and polypharmacy. Except when contraindicated, anticoagulation is necessary for preventing thromboembolic events in this population. Both vitamin K antagonists and direct oral anticoagulants (dabigatran, rivaroxaban and apixaban) are indicated in this context. Renal function should be closely monitored for this age group when these drugs are used. In recent years, various clinical practice guidelines have been published on patients with AF. The majority of these guidelines make specific recommendations on the clinical characteristics and treatment of elderly patients. In this update, we review the specific comments on the recommendations concerning antithrombotic treatment in elderly patients with nonvalvular AF. Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Medicina Interna (SEMI). All rights reserved.

  3. CT findings of cerebrovascular diseases in patients with atrial fibrillation

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, Hideki; Iwamoto, Toshihiko; Kanaya, Kiyoshi; Hanyu, Haruo; Yamaguchi, Katsuhiko; Katsunuma, Hideyo

    1988-02-01

    CT findings of cerebrovascular diseases were studied in 111 patients with atrial fibrillation (Af). One of these patients had cerebral hemorrhage, and another, subarachnoid hemorrhage, while the others all had cerebral infarctions. CT revealed 122 lesions with a low-density area (LDA) in 105 patients. Based on the cerebral artery territory, the 122 CT lesions were classified into the following 8 types: 10 hemispheric, 43 superficial, 23 deep, 28 superficial+deep, 1 anterior cerebral artery, 6 posterior cerebral artery, 10 watershed, and 1 vertebrobasilar. Therefore, infarctions of the internal carotid artery (ICA) system, including 94 infarctions of the middle cerebral artery territory, were most frequent, accounting for 94% of all lesions. The ratio of the left to the right infarctions of the ICA system was 1.1:1. However, it should be noted that non-embolic infarctions can occur even patients with Af.

  4. Clinical course of acute atrial fibrillation treated with rapid digitalization.

    Science.gov (United States)

    Weiner, P; Bassan, M M; Jarchovsky, J; Iusim, S; Plavnick, L

    1983-02-01

    Forty-seven episodes of acute atrial fibrillation (AF) in 45 patients were examined prospectively to determine the course of the disorder treated with rapid digitalization. Patients received 1.5 mg of digoxin intravenously over 12 hours. In 40 of the 47 attacks, reversion to sinus rhythm occurred with no additional therapy at 1 to 96 hours (median 4 hours) after beginning digoxin. In thirty-two patients, conversion occurred within 8 hours; only one patient showed important ventricular slowing before conversion. Thus, if digoxin facilitates conversion, it does not do so by slowing the ventricular response. Of the 11 patients still in AF at 16 hours, conversion subsequently occurred in only four who were receiving digoxin alone. We conclude that the prognosis for quick reversion to sinus rhythm in patients with acute AF treated with rapid digitalization alone is excellent. If reversion does not occur by 16 to 24 hours, additional measures to restore sinus rhythm are indicated.

  5. Ventricular rhythm in atrial fibrillation under anaesthetic infusion with propofol

    International Nuclear Information System (INIS)

    Cervigón, R; Moreno, J; Pérez-Villacastín, J; Reilly, R B; Castells, F

    2009-01-01

    Changes in patients' autonomic tone and specific pharmacologic interventions may modify the ventricular response (actual heart rate) during atrial fibrillation (AF). Hypnotic agents such as propofol may modify autonomic balance as they promote a sedative state. It has been shown that propofol slightly slows atrial fibrillatory activity, but the net global effect on the ventricular response remains unknown. We aimed to evaluate in patients in AF the effect of a propofol bolus on the ventricular rate and regularity at ECG. We analysed the possible relation with local atrial fibrillatory activities, as ratios between atrial and ventricular rates (AVRs), analysing atrial activity from intracardiac electrograms at the free wall of the right and left atria and at the interatrial septum. We compared data at the baseline and after complete hypnosis. Propofol was associated with a more homogeneous ventricular response and lower AVR values at the interatrial septum

  6. CT findings of cerebrovascular diseases in patients with atrial fibrillation

    International Nuclear Information System (INIS)

    Kubo, Hideki; Iwamoto, Toshihiko; Kanaya, Kiyoshi; Hanyu, Haruo; Yamaguchi, Katsuhiko; Katsunuma, Hideyo

    1988-01-01

    CT findings of cerebrovascular diseases were studied in 111 patients with atrial fibrillation (Af). One of these patients had cerebral hemorrhage, and another, subarachnoid hemorrhage, while the others all had cerebral infarctions. CT revealed 122 lesions with a low-density area (LDA) in 105 patients. Based on the cerebral artery territory, the 122 CT lesions were classified into the following 8 types: 10 hemispheric, 43 superficial, 23 deep, 28 superficial+deep, 1 anterior cerebral artery, 6 posterior cerebral artery, 10 watershed, and 1 vertebrobasilar. Therefore, infarctions of the internal carotid artery (ICA) system, including 94 infarctions of the middle cerebral artery territory, were most frequent, accounting for 94% of all lesions. The ratio of the left to the right infarctions of the ICA system was 1.1:1. However, it should be noted that non-embolic infarctions can occur even patients with Af. (author)

  7. Current practice for diagnosis and management of silent atrial fibrillation

    DEFF Research Database (Denmark)

    Dobreanu, Dan; Svendsen, Jesper Hastrup; Lewalter, Thorsten

    2013-01-01

    for the diagnosis and management of silent AF. This survey is based on an electronic questionnaire sent to the European Heart Rhythm Association Research Network partners. Responses were received from 33 centres in 16 countries. The preferred screening methods for silent AF in patients with rhythm control...... for such patients. Most responders preferred rate control over rhythm control in patients with silent AF, although some favoured pulmonary vein isolation in young patients. However, oral anticoagulant therapy in patients at high thromboembolic risk was considered mandatory by most, provided that at least one......Although it is well known that silent atrial fibrillation (AF) is associated with morbidity and mortality rates similar to those of symptomatic AF, no specific strategy for screening and management of this form of AF has been advocated. The purpose of this survey was to identify current practices...

  8. Strategies in the Surgical Management of Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Leanne Harling

    2011-01-01

    Full Text Available Atrial fibrillation (AF is associated with substantial morbidity, mortality, and economic burden and confers a lifetime risk of up to 25%. Current medical management involves thromboembolism prevention, rate, and rhythm control. An increased understanding of AF pathophysiology has led to enhanced pharmacological and medical therapies; however this is often limited by toxicity, variable symptom control, and inability to modulate the atrial substrate. Surgical AF ablation has been available since the original description of the Cox Maze procedure, either as a standalone or concomitant intervention. Advances in novel energy delivery systems have allowed the development of less technically demanding procedures potentially eliminating the need for median sternotomy and cardiopulmonary bypass. Variations in the definition, duration, and reporting of AF have produced methodological limitations impacting on the validity of interstudy comparisons. Standardization of these parameters may, in future, allow us to further evaluate clinical endpoints and establish the efficacy of these techniques.

  9. Atrial Fibrillation in a Diarrheic Holstein Dairy Calf

    Directory of Open Access Journals (Sweden)

    Aliasghar CHALMEH

    2015-01-01

    Full Text Available Cardiac auscultation of a 10-day-old diarrheic female Holstein dairy calf revealed irregularities in rhythm and absence of 4th heart sound. Electrocardiogram (ECG and blood sample were obtained before and after the treatment. Based on ECG and cardiac auscultation findings, atrial fibrillation (AF was diagnosed. Serum sodium, calcium and magnesium before treatment were significantly lower than their reference ranges and potassium was significantly higher. One day after treating this patient, serum electrolytes were reached to reference ranges and AF was changed to normal sinus rhythm. Based on resolving the AF after treating the patient and correcting the electrolyte imbalances, it can be suggested that electrolyte imbalances were the main cause of the occurrence of AF in the present case.

  10. Epidemiology and genetics of ventricular fibrillation during acute myocardial infarction

    DEFF Research Database (Denmark)

    Glinge, Charlotte; Sattler, Stefan; Jabbari, Reza

    2016-01-01

    of a family member is a risk factor for SCD and VF during acute myocardial infarction (MI), independent of traditional risk factors including family history of MI, suggesting a genetic component in the susceptibility to VF. To prevent SCD and VF due to MI, we need a better understanding of the genetic...... and molecular mechanisms causing VF in this apparently healthy population. Even though new insights and technologies have become available, the genetic predisposition to VF during MI remains poorly understood. Findings from a variety of different genetic studies have failed to reach reproducibility, although...... several genetic variants, both common and rare variants, have been associated to either VF or SCD. For this review, we searched PubMed for potentially relevant articles, using the following MeSH-terms: "sudden cardiac death", "ventricular fibrillation", "out-of-hospital cardiac arrest", "myocardial...

  11. Stroke Prevention in Atrial Fibrillation: Current Strategies and Recommendations

    Directory of Open Access Journals (Sweden)

    Gerald V. Naccarelli, MD

    2016-02-01

    Full Text Available Stroke is the most common complication of atrial fibrillation (AF. Guidelines recommend anticoagulant treatment in patients with CHA2DS2VASc scores of >2. Registry data suggests that almost half of patients who should be on therapeutic anticoagulation for stroke prevention in AF (SPAF are not. Warfarin and more recently developed agents, the “novel anticoagulants” (NOACs reduce the risk of embolic strokes. In addition, the NOACs also reduce intracranial hemorrhage (ICH by over 50% compared to warfarin. Anticoagulation and bridging strategies involving cardioversion, catheter ablation, and invasive/surgical procedures are reviewed. The development of reversal agents for NOACs and the introduction of left atrial appendage occluding devices will evolve the use of newer strategies for preventing stroke in high risk AF patients.

  12. Familial aggregation of atrial fibrillation: a study in Danish twins

    DEFF Research Database (Denmark)

    Christophersen, Ingrid Elisabeth; Ravn, Lasse Steen; Budtz-Joergensen, Esben

    2009-01-01

    BACKGROUND: Heritability may play a role in nonfamilial atrial fibrillation (AF). We hypothesized that a monozygotic (MZ) twin whose co-twin was diagnosed with AF would have an increased risk of the disease compared with a dizygotic (DZ) twin in the same situation. METHODS AND RESULTS: A sample......-free survival times, we compared the time span between occurrences of disease in MZ and DZ twins. The unaffected twin was included when his or her twin-sibling (the index twin) was diagnosed with AF. After adjustment for age at entry, MZ twins had a significantly shorter event-free survival time (hazard ratio......, 2.0; 95% CI, 1.3 to 3.0), thereby indicating a genetic component. Using biometric models, we estimated the heritability of AF to be 62% (55% to 68%), due to additive genetics. There were no significant differences across sexes. CONCLUSIONS: All the analyses of twin similarities in the present study...

  13. Oral anticoagulants for stroke prevention in atrial fibrillation.

    Science.gov (United States)

    Senoo, Keitaro; Lane, Deirdre A; Lip, Gregory Y H

    2014-09-01

    The availability of 4 non-vitamin K oral anticoagulants (NOACs), that is, dabigatran, rivaroxaban, apixaban, and edoxaban, has changed the landscape of stroke prevention in patients with atrial fibrillation. This review article provides an overview of the 4 phase III studies that have compared these NOACs, examining major outcomes of efficacy and safety. A range of practical questions relating to the NOACs have emerged, including topics such as patient selection, treating patients with renal impairment, treating elderly patients, and combining anticoagulant therapy with antiplatelet drugs. We also address the interaction of various patient characteristics with the treatments and suggest the features can assist the physician in the choice of a particular NOAC for a particular patient(s). Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Service provision and use of anticoagulants in atrial fibrillation.

    Science.gov (United States)

    Sudlow, C. M.; Rodgers, H.; Kenny, R. A.; Thomson, R. G.

    1995-01-01

    Several large trials have shown that the risk of stroke in patients with non-valvar atrial fibrillation is reduced by treatment with warfarin. Implementing this research evidence requires not only an understanding of the trials' results and of the changes that they imply for clinicians' treatment decisions but also an appreciation of the organisation, quantity, and quality of services required to support these changes. Understanding of these implications is crucial for developing services that allow changes in practice to produce reductions in stroke incidence while minimising the risks of treatment. This article considers the developments in service provision that will probably be required to support the changes in clinical practice suggested by the trials' results. These services will be provided largely by doctors, and their development has implications for doctors in both primary and secondary care. Images FIG 1 PMID:7663216

  15. Are Amyloid Fibrils RNA-Traps? A Molecular Dynamics Perspective

    Directory of Open Access Journals (Sweden)

    Massimiliano Meli

    2018-06-01

    Full Text Available The self-assembly of proteins and peptides into amyloids is a key feature of an increasing number of diseases. Amyloid fibrils display a unique surface reactivity endowing the sequestration of molecules such as MicroRNAs, which can be the active moiety of the toxic action. To test this hypothesis we studied the recognition between a model RNA and two different steric zipper spines using molecular dynamics simulations. We found that the interaction occurs and displays peptide-sequence dependence. Interestingly, interactions with polar zipper surfaces such as the formed by SNQNNF are more stable and favor the formation of β-barrel like complexes resembling the structures of toxic oligomers. These sequence-structure-recognition relationships of the two different assemblies may be exploited for the design of compounds targeting the fibers or competing with RNA-amyloid attachment

  16. Clinical Implications of Technological Advances in Screening for Atrial Fibrillation.

    Science.gov (United States)

    Singh, Nikhil; Chun, Sung; Hadley, David; Froelicher, Victor

    The incidence of atrial fibrillation (AF) continues to increase worldwide as people live longer. AF is the leading cause of stroke among patients older than 75 years and is responsible for at least 15% of all strokes. Industry has responded to this problem with a plethora of monitoring devices. These include single lead ECG adhesive sensors, implantable loop recorders, smartphone attachments and wearables. This review will concentrate on clinical studies using these technologies. There are wearables including watches and watch-like devices that will be mentioned but these have not been validated for clinical use. This review will begin with a background regarding screening for AF and at the end present findings from Cardiac Implantable devices that could influence use of the new mobile health technologies. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Anticoagulant treatment in patients with atrial fibrillation and ischemic stroke

    DEFF Research Database (Denmark)

    Brunner-Frandsen, Nicole; Dammann Andersen, Andreas; Ashournia, Hamoun

    2015-01-01

    BACKGROUND: Atrial fibrillation (AF) is the most common cardiac dysrhythmia, with a lifetime risk of 25%, and it is a well-known independent risk factor for ischemic stroke. Over the last 15 years, efforts have been made to initiate relevant treatment in patients with AF. A retrospective study...... was set up to clarify whether this effort has resulted in a decreased proportion of patients with known AF experiencing an ischemic stroke. METHODS: Patients admitted to the Department of Neurology, Vejle Hospital, Denmark, with ischemic stroke from January 1997 to December 2012 were included in the study....... RESULTS: A total of 4134 patients were included in the study. Overall, the yearly proportion of patients with known AF varied between 9% and 18%. No significant change was observed (P = .511). The proportion of patients with known AF treated with anticoagulants at the time of the stroke and the proportion...

  18. The architecture of amyloid-like peptide fibrils revealed by X-ray scattering, diffraction and electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Langkilde, Annette E., E-mail: annette.langkilde@sund.ku.dk [University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen (Denmark); Morris, Kyle L.; Serpell, Louise C. [University of Sussex, Falmer, Brighton (United Kingdom); Svergun, Dmitri I. [European Molecular Biology Laboratory, Hamburg Outstation, 22607 Hamburg (Germany); Vestergaard, Bente [University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen (Denmark)

    2015-04-01

    The aggregation process and the fibril state of an amyloidogenic peptide suggest monomer addition to be the prevailing mechanism of elongation and a model of the peptide packing in the fibrils has been obtained. Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril of the GNNQQNY peptide fragment of a yeast prion protein. Data from small-angle X-ray solution scattering, fibre diffraction and electron microscopy are combined with existing high-resolution X-ray crystallographic structures to investigate the fibrillation process and the hierarchical fibril structure of the peptide fragment. The elongation of these fibrils proceeds without the accumulation of any detectable amount of intermediate oligomeric species, as is otherwise reported for, for example, glucagon, insulin and α-synuclein. Ribbons constituted of linearly arranged protofilaments are formed. An additional hierarchical layer is generated via the pairing of ribbons during fibril maturation. Based on the complementary data, a quasi-atomic resolution model of the protofilament peptide arrangement is suggested. The peptide structure appears in a β-sheet arrangement reminiscent of the β-zipper structures evident from high-resolution crystal structures, with specific differences in the relative peptide orientation. The complexity of protein fibrillation and structure emphasizes the need to use multiple complementary methods.

  19. Effects-Driven IT Development

    DEFF Research Database (Denmark)

    Hertzum, Morten; Simonsen, Jesper

    2010-01-01

    We present effects-driven IT development as an instrument for pursuing and reinforcing Participatory Design (PD) when it is applied in commercial information technology (IT) projects. Effects-driven IT development supports the management of a sustained PD process throughout design and organizatio......We present effects-driven IT development as an instrument for pursuing and reinforcing Participatory Design (PD) when it is applied in commercial information technology (IT) projects. Effects-driven IT development supports the management of a sustained PD process throughout design...

  20. Obesity and Outcomes among Patients with Established Atrial Fibrillation

    Science.gov (United States)

    Ardestani, Afrooz; Hoffman, Heather J.; Cooper, Howard A.

    2010-01-01

    Atrial fibrillation (AF) and obesity have both reached epidemic proportions. The impact of obesity on clinical outcomes in patients with established AF is unknown. We analyzed 2492 patients in the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study. Body mass index (BMI) was evaluated as a categorical variable (normal: 18.5 to <25; overweight: 25 to <30; obese: ≥ 30). The rate of death from any cause was higher in the normal BMI group (5.8 per 100 patient-years) than in the overweight and obese groups (3.9 and 3.7, respectively). The cardiovascular death rate was highest in the normal BMI group (3.1 per 100 patient-years), lowest in the overweight group (1.5 per 100 patient-years), and intermediate in the obese group (2.1 per 100 patient-years). After adjustment for baseline factors, differences in the risk of death from any cause were no longer significant. However, overweight remained associated with a reduced risk of cardiovascular death (Hazard ratio 0.47, p=0.002). Obese patients were more likely to have an uncontrolled resting heart rate, but rhythm control strategy success was similar across BMI categories. In each of the BMI categories, the risk of death from any cause was similar for patients randomized to a rhythm or a rate control strategy. In conclusion, among patients with established AF, overweight and obesity do not adversely affect overall survival. Obesity does not appear to impact the relative benefit of a rate or rhythm control strategy. PMID:20643247

  1. Pulmonary vein isolation in the treatment of atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Kumar S

    2016-05-01

    Full Text Available Saurabh Kumar, Gregory F Michaud Cardiac Arrhythmia Service, Cardiovascular Division, Brigham and Women's Hospital, Boston, MA, USA Abstract: Atrial fibrillation (AF is the commonest arrhythmia in humans and is associated with marked reduction in quality of life and an elevated thromboembolic risk. Paroxysmal, persistent, and permanent forms of AF have been recognized. Whilst antiarrhythmic drugs are considered as first-line therapy, the role of catheter ablation is increasing due to its superior efficacy in terms of quality of life and reduction in AF burden. The central paradigm for catheter ablation of AF is that triggers for AF are located near and within the pulmonary veins (PVs, and electrical isolation of the PVs from the left atrium forms the cornerstone of most catheter ablation strategies. Whilst paroxysmal form is generally trigger dependent, persistent and permanent forms are associated with variable interaction between triggers and "substrate" comprised of atrial and PV electrical and structural remodeling. Nevertheless, isolation of the PVs still forms a critical component of catheter ablation strategies, regardless of AF type. Procedural efficacy, however, is limited by PV conduction recovery. This is likely due to deficiencies in ablation tools or limitations of intraprocedural assessment of lesion efficacy. Careful attention to surrogates of tissue heating, such as impedance decrease and electrogram morphology changes, along with advances in catheter technology like contact force catheters may improve rates of durable PV isolation and single-procedural success. This review discusses the mechanism of paroxysmal AF with particular focus on the role of the PVs in AF initiation and PV isolation in the management of AF. Keywords: contact force, lesion transmurality, radiofrequency catheter ablation, paroxysmal atrial fibrillation, electrophysiology, AF

  2. Characterization of fibrillation process of α-synuclein at the initial stage

    International Nuclear Information System (INIS)

    Tashiro, Mitsuru; Kojima, Masaki; Kihara, Hiroshi; Kasai, Kouki; Kamiyoshihara, Tomoaki; Ueda, Kenji; Shimotakahara, Sakurako

    2008-01-01

    α-Synuclein is the major component of the filamentous Lewy bodies and Lewy-related neurites, neuropathological hallmarks of Parkinson's disease. Although numerous studies on α-synuclein fibrillation have been reported, the molecular mechanisms of aggregation and fibrillation at the initial stage are still unclear. In the present study, structural properties and propensities to form fibrils of α-synuclein at the initial stage were investigated using 2D 1 H- 15 N NMR spectroscopy, electron microscope, and small angle X-ray scattering (SAXS). Observation of the 2D 1 H- 15 N HSQC spectra indicated significant attenuation of many cross peak intensities in the regions of KTKEGV-type repeats and the non-Aβ component of Alzheimer's disease amyloid (NAC), suggesting that these regions contributed fibril formation. Oligomerization comprising heptamer was successfully monitored at the initial stage using the time-dependent SAXS measurements

  3. Sex-related differences in atrial fibrillation: Data from the RACE study

    NARCIS (Netherlands)

    Rienstra, M.; Van Gelder, I.C.

    2006-01-01

    We evaluated the effects of rate control treatment versus sinus rhythm restoration and maintenance in patients with persistent atrial fibrillation in a substudy of the Rate Control Versus Electrical Cardioversion (RACE) trial. Rhythm control treatment was associated with greater cardiovascular

  4. Atrial Fibrillation and Gastro-Oesophageal Reflux Disease - Controversies and Challenges.

    Science.gov (United States)

    Floria, Mariana; Barboi, Oana; Rezus, Ciprian; Ambarus, Valentin; Cijevschi-Prelipcean, Cristina; Balan, Gheorghe; Drug, Vasile Liviu

    2015-01-01

    Atrial fibrillation and gastro-oesophageal reflux are common manifestations in daily practice. The atria and the oesophagus are closely located and have similar nerve innervations. Over the last years, it has been observed that atrial fibrillation development and reflux disease could be related. Atrial fibrillation occurrence could be due to vagal nerve overstimulation. This, in association with vagal nerve-mediated parasympathetic stimulation, has also been observed in patients with gastro-oesophageal reflux. These mechanisms, in addition to inflammation, seem to be implicated in the pathophysiology of both diseases. Despite these associations supported by clinical and experimental studies, this relationship is still considered controversial. This review summarizes critical data regarding the association of gastro-oesophageal reflux and atrial fibrillation as well as their clinical implications.

  5. Quantification of anaesthetic effects on atrial fibrillation rate by partial least-squares

    International Nuclear Information System (INIS)

    Cervigón, R; Moreno, J; Pérez-Villacastín, J; Reilly, R B; Castells, F

    2012-01-01

    The mechanism underlying atrial fibrillation (AF) remains poorly understood. Multiple wandering propagation wavelets drifting through both atria under hierarchical models are not understood. Some pharmacological drugs, known as antiarrhythmics, modify the cardiac ionic currents supporting the fibrillation process within the atria and may modify the AF propagation dynamics terminating the fibrillation process. Other medications, theoretically non-antiarrhythmic, may slightly affect the fibrillation process in non-defined mechanisms. We evaluated whether the most commonly used anaesthetic agent, propofol, affects AF patterns. Partial least-squares (PLS) analysis was performed to reduce significant noise into the main latent variables to find the differences between groups. The final results showed an excellent discrimination between groups with slow atrial activity during the propofol infusion. (paper)

  6. Nonequilibrium and generalized-ensemble molecular dynamics simulations for amyloid fibril

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, Hisashi [Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan); Department of Structural Molecular Science, The Graduate University for Advanced Studies, Okazaki, Aichi 444-8585 (Japan)

    2015-12-31

    Amyloids are insoluble and misfolded fibrous protein aggregates and associated with more than 20 serious human diseases. We perform all-atom molecular dynamics simulations of amyloid fibril assembly and disassembly.

  7. Influence of dendrimer's structure on its activity against amyloid fibril formation

    International Nuclear Information System (INIS)

    Klajnert, B.; Cortijo-Arellano, M.; Cladera, J.; Bryszewska, M.

    2006-01-01

    Inhibition of fibril assembly is a potential therapeutic strategy in neurodegenerative disorders such as prion and Alzheimer's diseases. Highly branched, globular polymers-dendrimers-are novel promising inhibitors of fibril formation. In this study, the effect of polyamidoamine (PAMAM) dendrimers (generations 3rd, 4th, and 5th) on amyloid aggregation of the prion peptide PrP 185-208 and the Alzheimer's peptide Aβ 1-28 was examined. Amyloid fibrils were produced in vitro and their formation was monitored using the dye thioflavin T (ThT). Fluorescence studies were complemented with electron microscopy. The results show that the higher the dendrimer generation, the larger the degree of inhibition of the amyloid aggregation process and the more effective are dendrimers in disrupting the already existing fibrils. A hypothesis on dendrimer-peptide interaction mechanism is presented based on the dendrimers' molecular structure

  8. Digoxin use and risk of mortality in hypertensive patients with atrial fibrillation

    DEFF Research Database (Denmark)

    Okin, Peter M; Hille, Darcy A; Wachtell, Kristian

    2015-01-01

    , diabetes, history of ischemic heart disease, stroke, or heart failure, baseline Cornell product, QRS duration, heart rate, serum glucose, creatinine and high-density lipoprotein cholesterol, and a propensity score for digoxin use entered as standard covariates, and for in-treatment heart rate, pulse...... patients with atrial fibrillation has not been examined. METHODS AND RESULTS: All-cause mortality was examined in relation to in-treatment digoxin use in 937 hypertensive patients with ECG left ventricular hypertrophy in atrial fibrillation at baseline (n = 134) or who developed atrial fibrillation during...... fibrillation, digoxin use is not associated with a significantly increased risk of all-cause mortality after adjusting for other independent predictors of death and for the factors associated with the propensity to use digoxin in this population. These findings suggest that factors other than digoxin use may...

  9. Work related physical activity and risk of a hospital discharge diagnosis of atrial fibrillation or flutter

    DEFF Research Database (Denmark)

    Frost, L; Frost, P; Vestergaard, P

    2005-01-01

    of atrial fibrillation or flutter associated with sedentary work in a standing position, light workload, or heavy workload in men or women. CONCLUSION: No evidence was found of an association between physical activities during working hours and risk of a hospital discharge diagnosis of atrial fibrillation......, Cancer, and Health Study. The physical strain during working hours was categorised as sedentary, light, or heavy, and analysed using proportional hazard models. Subjects were followed up in the Danish National Registry of Patients and in the Danish Civil Registration System. RESULTS: During follow up...... (mean 5.7 years) a hospital discharge diagnosis of atrial fibrillation or flutter occurred in 305 men and 113 women. When using the risk of atrial fibrillation or flutter associated with sedentary work at a sitting position as a reference, no excess risk (unadjusted as well as adjusted) was found...

  10. Temporal changes in patient characteristics and prior pharmacotherapy in patients undergoing radiofrequency ablation of atrial fibrillation

    DEFF Research Database (Denmark)

    Karasoy, Deniz; Gislason, Gunnar Hilmar; Hansen, Jim

    2013-01-01

    Trends in patient selection and pharmacotherapy before radiofrequency ablation (RFA) of atrial fibrillation are not well studied. We examined temporal trends in RFA utilization on a nationwide scale in Denmark....

  11. Atrial fibrillation in a healthy adolescent after heavy smoking of contraband cigarettes.

    Science.gov (United States)

    Ozyilmaz, Isa; Ozyilmaz, Sinem; Tosun, Oyku; Tola, Hasan Tahsin; Saygi, Murat; Ergul, Yakup

    2015-08-01

    The use of contraband cigarettes is a serious public health problem. We present a case of atrial fibrillation in a healthy adolescent suspected to be caused by smoking contraband cigarettes. A 15-year-old man was admitted to our emergency department experiencing syncope and palpitations. He was a cigarette smoker, but he had never smoked any illicit tobacco products before. He had finished a pack of counterfeit cigarettes (20 pieces) in 1.5 h. His electrocardiogram showed atrial fibrillation with a rapid ventricular response and irregular RR intervals. The patient had no history of alcohol use, surgery, palpitations, hypertension, chronic bronchitis, or any infectious diseases. His atrial fibrillation was converted to a normal sinus rhythm after the cardioversion treatment. Our patient was discharged from the pediatric cardiology service and advised to quit smoking cigarettes, strictly warning against illicit tobacco products. In conclusion, intensive smoking of counterfeit cigarettes may lead to occurrences of atrial fibrillation.

  12. Improved late survival and disability after stroke with therapeutic anticoagulation for atrial fibrillation: a population study.

    LENUS (Irish Health Repository)

    Hannon, Niamh

    2011-09-01

    Although therapeutic anticoagulation improves early (within 1 month) outcomes after ischemic stroke in hospital-admitted patients with atrial fibrillation, no information exists on late outcomes in unselected population-based studies, including patients with all stroke (ischemic and hemorrhagic).

  13. Management of Newly Diagnosed Atrial Fibrillation in an Outpatient Clinic Setting

    DEFF Research Database (Denmark)

    Thrysoee, Lars; Strömberg, Anna; Brandes, Axel

    2018-01-01

    fibrillation is not a fatal disease in itself was very important for patients. At the same time, visiting the clinic was overwhelming, information was difficult to understand, and patients found it difficult to be involved in decision-making. CONCLUSIONS: This study indicates that patients were uncertain......AIMS: To gain in-depth knowledge of patients' experiences of the consultation processes at a multidisciplinary atrial fibrillation outpatient clinic in a university hospital in Denmark. BACKGROUND: Atrial fibrillation is the most common cardiac arrhythmia associated with morbidity and mortality...... if not diagnosed and treated as recommended. Patients with newly diagnosed atrial fibrillation preferably should be managed in an outpatient setting which includes medical examination, patient education and decision making on medical therapy. DESIGN: This is a qualitative study of 14 patients newly diagnosed...

  14. Fibrillation of Aspen by Alkaline Cold Pre-treatment and Vibration Milling

    Directory of Open Access Journals (Sweden)

    Kärt KÄRNER

    2016-09-01

    Full Text Available In this article an attempt to fibrillate aspen bleached chemi-thermo mechanical pulp (BCTMP fibre in an environmentally friendly way is reported. The effects of various NaOH, KOH, urea and ethanol aqueous solutions at lowered temperature were tested for pre-treatment. The pre-treatment was followed by vibration milling aiming to peel off outer cell wall layers and to fibrillate S2 layer of the aspen wood fibre. The effects of the treatments were evaluated by scanning electron microscopy (SEM. The results show that it is possible to fibrillate BCTMP aspen fibres by using alkaline aqueous solutions at low temperatures followed by a mechanical treatment. A strong dependence on fibrillation of cellulose on temperature, time and alkali concentration was established.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7412

  15. Vernakalant hydrochloride for the rapid conversion of atrial fibrillation after cardiac surgery

    DEFF Research Database (Denmark)

    Kowey, Peter R; Dorian, Paul; Mitchell, L Brent

    2009-01-01

    Postoperative atrial arrhythmias are common and are associated with considerable morbidity. This study was designed to evaluate the efficacy and safety of vernakalant for the conversion of atrial fibrillation (AF) or atrial flutter (AFL) after cardiac surgery....

  16. AFM-based force spectroscopy measurements of mature amyloid fibrils of the peptide glucagon

    DEFF Research Database (Denmark)

    Dong, M. D.; Hovgaard, M. B.; Mamdouh, W.

    2008-01-01

    We report on the mechanical characterization of individual mature amyloid fibrils by atomic force microscopy (AFM) and AFM-based single-molecule force spectroscopy (SMFS). These self-assembling materials, formed from the 29-residue amphiphatic peptide hormone glucagon, were found to display...... a reversible elastic behaviour. Based on AFM morphology and SMFS studies, we suggest that the observed elasticity is due to a force-induced conformational transition which is reversible due to the beta-helical conformation of protofibrils, allowing a high degree of extension. The elastic properties...... of such mature fibrils contribute to their high stability, suggesting that the internal hydrophobic interactions of amyloid fibrils are likely to be of fundamental importance in the assembly of amyloid fibrils and therefore for the understanding of the progression of their associated pathogenic disorders...

  17. A NORMAL BRADYSYSTOLIC FORM OF ATRIAL FIBRILLATION (FREDERICQ’S SYNDROME: LATE DIAGNOSIS AND TREATMENT

    Directory of Open Access Journals (Sweden)

    N. Ye. Trekina

    2014-11-01

    Full Text Available It is presented a case of delayed diagnosis brad systole against permanent atrial fibrillation (syndrome Frederick which became to syncope patient and to the later implanting of pacemaker.

  18. Risk of atrial fibrillation in diabetes mellitus: A nationwide cohort study.

    Science.gov (United States)

    Pallisgaard, Jannik L; Schjerning, Anne-Marie; Lindhardt, Tommi B; Procida, Kristina; Hansen, Morten L; Torp-Pedersen, Christian; Gislason, Gunnar H

    2016-04-01

    Diabetes has been associated with atrial fibrillation but the current evidence is conflicting. In particular knowledge regarding young diabetes patients and the risk of developing atrial fibrillation is sparse. The aim of our study was to investigate the risk of atrial fibrillation in patients with diabetes compared to the background population in Denmark. Through Danish nationwide registries we included persons above 18 years of age and without prior atrial fibrillation and/or diabetes from 1996 to 2012. The study cohort was divided into a background population without diabetes and a diabetes group. The absolute risk of developing atrial fibrillation was calculated and Poisson regression models adjusted for sex, age and comorbidities were used to calculate incidence rate ratios of atrial fibrillation. The total study cohort included 5,081,087 persons, 4,827,713 (95%) in the background population and 253,374 (5%) in the diabetes group. Incidence rates of atrial fibrillation per 1000 person years were stratified in four age groups from 18 to 39, 40 to 64, 65 to 74 and 75 to 100 years giving incidence rates (95% confidence intervals) of 0.02 (0.02-0.02), 0.99 (0.98-1.01), 8.89 (8.81-8.98) and 20.0 (19.9-20.2) in the background population and 0.13 (0.09-0.20), 2.10 (2.00-2.20), 8.41 (8.10-8.74) and 20.1 (19.4-20.8) in the diabetes group, respectively. The adjusted incidence rate ratios in the diabetes group with the background population as reference were 2.34 (1.52-3.60), 1.52 (1.47-1.56), 1.20 (1.18-1.23) and 0.99 (0.97-1.01) in the four age groups, respectively. Diabetes is an independent risk factor for developing atrial fibrillation/flutter, most pronounced in young diabetes patients. Routine screening for atrial fibrillation/flutter in diabetes patients might be beneficial and have therapeutic implications, especially in younger diabetes patients. Diabetes increases the risk of developing atrial fibrillation and especially young diabetes patients have a high

  19. Lumbar Discectomy of a Patient of Mitral Stenosis with Chronic Atrial Fibrillation Under Epidural Anaesthesia

    Directory of Open Access Journals (Sweden)

    Vinaya R Kulkarni

    2008-01-01

    Full Text Available A 60-year-old female patient posted for discectomy of lumbar region L 3 -L 4 was accidently diagnosed to have chronic atrial fibrillation of rheumatic aetiology.This is a case report of this patient of critical mitral stenosis with mild mitral regurgitation with chronic atrial fibrillation managed successfully under lower thoracic epidural anaesthesia,in prone position without any compli-cation.

  20. SECONDARY PREVENTION OF STROKE IN PATIENTS WITH NON-VALVULAR ATRIAL FIBRILLATION: THE CLINICIANS’ VIEWPOINT

    Directory of Open Access Journals (Sweden)

    E. A. Drozdova

    2015-09-01

    Full Text Available Atrial fibrillation is one of the main risk factor of ischemic stroke. Current problems of the management of patients with stroke due to non-valvular atrial fibrillation and secondary stroke prevention in these patients are considered. Data of own author’s observation for patients of this type during 6 months after discharge from the hospital are presented. The problems which patients faced with are analyzed. Comparative assessment of warfarin and dabigatran therapies is given.

  1. Inflammatory single nucleotide polymorphisms and the risk of atrial fibrillation: a case control study

    DEFF Research Database (Denmark)

    Henningsen, Kristoffer M; Olesen, Morten S; Ravn, Lasse S

    2011-01-01

    Systemic inflammation is associated with atrial fibrillation (AF) and inflammatory processes are involved in the pathophysiology of AF. We hypothesized that genetic polymorphisms, which determine the rate of inflammatory cytokines, are associated with increased risk of AF.......Systemic inflammation is associated with atrial fibrillation (AF) and inflammatory processes are involved in the pathophysiology of AF. We hypothesized that genetic polymorphisms, which determine the rate of inflammatory cytokines, are associated with increased risk of AF....

  2. Prevention of atrial fibrillation by Renin-Angiotensin system inhibition a meta-analysis

    DEFF Research Database (Denmark)

    Schneider, Markus; Hua, Tsushung A; Böhm, Michael

    2010-01-01

    The authors reviewed published clinical trial data on the effects of renin-angiotensin system (RAS) inhibition for the prevention of atrial fibrillation (AF), aiming to define when RAS inhibition is most effective.......The authors reviewed published clinical trial data on the effects of renin-angiotensin system (RAS) inhibition for the prevention of atrial fibrillation (AF), aiming to define when RAS inhibition is most effective....

  3. Smartphone electrographic monitoring for atrial fibrillation in acute ischemic stroke and transient ischemic attack.

    Science.gov (United States)

    Tu, Hans T; Chen, Ziyuan; Swift, Corey; Churilov, Leonid; Guo, Ruibing; Liu, Xinfeng; Jannes, Jim; Mok, Vincent; Freedman, Ben; Davis, Stephen M; Yan, Bernard

    2017-10-01

    Rationale Paroxysmal atrial fibrillation is a common and preventable cause of devastating strokes. However, currently available monitoring methods, including Holter monitoring, cardiac telemetry and event loop recorders, have drawbacks that restrict their application in the general stroke population. AliveCor™ heart monitor, a novel device that embeds miniaturized electrocardiography (ECG) in a smartphone case coupled with an application to record and diagnose the ECG, has recently been shown to provide an accurate and sensitive single lead ECG diagnosis of atrial fibrillation. This device could be used by nurses to record a 30-s ECG instead of manual pulse taking and automatically provide a diagnosis of atrial fibrillation. Aims To compare the proportion of patients with paroxysmal atrial fibrillation detected by AliveCor™ ECG monitoring with current standard practice. Sample size 296 Patients. Design Consecutive ischemic stroke and transient ischemic attack patients presenting to participating stroke units without known atrial fibrillation will undergo intermittent AliveCor™ ECG monitoring administered by nursing staff at the same frequency as the vital observations of pulse and blood pressure until discharge, in addition to the standard testing paradigm of each participating stroke unit to detect paroxysmal atrial fibrillation. Study outcome Proportion of patients with paroxysmal atrial fibrillation detected by AliveCor™ ECG monitoring compared to 12-lead ECG, 24-h Holter monitoring and cardiac telemetry. Discussion Use of AliveCor™ heart monitor as part of routine stroke unit nursing observation has the potential to be an inexpensive non-invasive method to increase paroxysmal atrial fibrillation detection, leading to improvement in stroke secondary prevention.

  4. SPECIAL CONSIDERATIONS REGARDING WARFARIN DOSE TITRATION IN PATIENTS WITH ATRIAL FIBRILLATION DEPENDING ON CLINICAL FACTORS

    OpenAIRE

    E. L. Artanova; E. V. Saleeva; I. M. Sokolov; Y. G. Shvarts

    2011-01-01

    Aim. To study the relations of clinical characteristics and individual warfarin dose titration in patients with atrial fibrillation. Material and methods. Period of warfarin dose titration was analyzed in 68 patients with atrial fibrillation due to ischemic heart disease. Adjusted warfarin dose in milligram, duration of dose titration in days and maximal international normalized ratio (INR) were taken into account. Sex, age, history of myocardial infarction and stroke, concomitant diseases, a...

  5. Atrial Fibrillation, Atrioventricular Blocks and Bundle Branch Blocks in Hemodialysis Patients

    OpenAIRE

    Mandic, Ante; Tomic, Monika; Petrov, Bozo; Romic, Zeljko

    2012-01-01

    Atrial fibrillation is one of the most frequent arrhythmias diagnosed in clinical practice and it is also relatively common in dialysis patients. Atrioventricular and intraventricular conduction disturbances are less investigated in hemodialysis patients and data about their prevalence are insufficient. The objective of this study was to determine the prevalence of atrial fibrillation, atrioventricular blocks and bundle branch blocks in hemodialysis patients and to analyze different clinical ...

  6. Fall risk and anticoagulation for atrial fibrillation in the elderly: A delicate balance.

    Science.gov (United States)

    Hagerty, Tracy; Rich, Michael W

    2017-01-01

    Guidelines for managing atrial fibrillation recommend systemic anticoagulation for almost all patients age 65 and older, but in practice up to 50% of older patients do not receive maintenance anticoagulation therapy. The most common reason physicians cite for withholding anticoagulation in older patients with atrial fibrillation is a perception of a high risk of falling and associated bleeding, especially intracranial hemorrhage. Copyright © 2017 Cleveland Clinic.

  7. Effect of lipid lowering on new-onset atrial fibrillation in patients with asymptomatic aortic stenosis

    DEFF Research Database (Denmark)

    Bang, Casper N; Greve, Anders; Boman, Kurt

    2012-01-01

    Lipid-lowering drugs, particularly statins, have anti-inflammatory and antioxidant properties that may prevent atrial fibrillation (AF). This effect has not been investigated on new-onset AF in asymptomatic patients with aortic stenosis (AS).......Lipid-lowering drugs, particularly statins, have anti-inflammatory and antioxidant properties that may prevent atrial fibrillation (AF). This effect has not been investigated on new-onset AF in asymptomatic patients with aortic stenosis (AS)....

  8. Benzofuranone derivatives as effective small molecules related to insulin amyloid fibrillation: a structure-function study

    DEFF Research Database (Denmark)

    Rabiee, Atefeh; Ebrahim-Habibi, Azadeh; Navidpour, Latifeh

    2011-01-01

    amyloid fibrils under slightly destabilizing conditions in vitro and may form amyloid structures when subcutaneously injected into patients with diabetes. There is a great deal of interest in developing novel small molecule inhibitors of amyloidogenic processes, as potential therapeutic compounds...... of the five tested compounds was observed to enhance amyloid fibrillation, while the others inhibited the process when used at micromolar concentrations, which could make them interesting potential lead compounds for the design of therapeutic antiamyloidogenic compounds....

  9. Lung response to ultrafine Kevlar aramid synthetic fibrils following 2-year inhalation exposure in rats.

    Science.gov (United States)

    Lee, K P; Kelly, D P; O'Neal, F O; Stadler, J C; Kennedy, G L

    1988-07-01

    Four groups of 100 male and 100 female rats were exposed to ultrafine Kevlar fibrils at concentrations of 0, 2.5, 25, and 100 fibrils/cc for 6 hr/day, 5 days/week for 2 years. One group was exposed to 400 fibrils/cc for 1 year and allowed to recover for 1 year. At 2.5 fibrils/cc, the lungs had normal alveolar architecture with a few dust-laden macrophages (dust cell response) in the alveolar airspaces. At 25 fibrils/cc, the lungs showed a dust cell response, slight Type II pneumocyte hyperplasia, alveolar bronchiolarization, and a negligible amount of collagenized fibrosis in the alveolar duct region. At 100 fibrils/cc, the same pulmonary responses were seen as at 25 fibrils/cc. In addition, cystic keratinizing squamous cell carcinoma (CKSCC) was found in 4 female rats, but not in male rats. Female rats had more prominent foamy alveolar macrophages, cholesterol granulomas, and alveolar bronchiolarization. These pulmonary lesions were related to the development of CKSCC. The lung tumors were derived from metaplastic squamous cells in areas of alveolar bronchiolarization. At 400 fibrils/cc following 1 year of recovery, the lung dust content, average fiber length, and the pulmonary lesions were markedly reduced, but slight centriacinar emphysema and minimal collagenized fibrosis were found in the alveolar duct region. One male and 6 female rats developed CKSCC. The lung tumors were a unique type of experimentally induced tumors in the rats and have not been seen as spontaneous tumors in man or animals. Therefore, the relevance of this type of lung tumor to the human situation is minimal.

  10. Disintegration of collagen fibrils by Glucono-δ-lactone: An implied lead for disintegration of fibrosis.

    Science.gov (United States)

    Jayamani, Jayaraman; Ravikanth Reddy, R; Madhan, Balaraman; Shanmugam, Ganesh

    2018-02-01

    Excess accumulation of collagen (fibrosis) undergoes self-aggregation, which leads to fibrillar collagen, on the extracellular matrix is the hallmark of a number of diseases such as keloids, hypertrophic scars, and systemic scleroderma. Direct inhibition or disintegration of collagen fibrils by small molecules offer a therapeutic approach to prevent or treat the diseases related to fibrosis. Herein, the anti-fibrotic property of Glucono-δ-lactone (GdL), known as acidifier, on the fibrillation and its disintegration of collagen was investigated. As collagen fibrillation is pH dependent, the pH modulation property of GdL is attractive to inhibit self-association of collagen. Optical density and microscopic data indicate that GdL elicits concentration-dependent fibril inhibition and also disintegrates pre-formed collagen fibrils. The simultaneous pH analysis showed that the modulation(lowering) of pH by GdL is the primary cause for its anti-fibrotic activity. The intact triple helical structure of collagen upon treatment of GdL suggests that collagen fibril disintegration can be achieved without affecting the native structure of collagen which is essential for any anti-fibrotic agents. Saturation transfer difference (STD) NMR result reveals that GdL is in proximity to collagen. The present results thus suggest that GdL provides a lead to design novel anti-fibrotic agents for the pathologies related to collagen deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Susceptibility tensor imaging and tractography of collagen fibrils in the articular cartilage.

    Science.gov (United States)

    Wei, Hongjiang; Gibbs, Eric; Zhao, Peida; Wang, Nian; Cofer, Gary P; Zhang, Yuyao; Johnson, G Allan; Liu, Chunlei

    2017-11-01

    To investigate the B 0 orientation-dependent magnetic susceptibility of collagen fibrils within the articular cartilage and to determine whether susceptibility tensor imaging (STI) can detect the 3D collagen network within cartilage. Multiecho gradient echo datasets (100-μm isotropic resolution) were acquired from fixed porcine articular cartilage specimens at 9.4 T. The susceptibility tensor was calculated using phase images acquired at 12 or 15 different orientations relative to B 0 . The susceptibility anisotropy of the collagen fibril was quantified and diffusion tensor imaging (DTI) was compared against STI. 3D tractography was performed to visualize and track the collagen fibrils with DTI and STI. STI experiments showed the distinct and significant anisotropic magnetic susceptibility of collagen fibrils within the articular cartilage. STI can be used to measure and quantify susceptibility anisotropy maps. Furthermore, STI provides orientation information of the underlying collagen network via 3D tractography. The findings of this study demonstrate that STI can characterize the orientation variation of collagen fibrils where diffusion anisotropy fails. We believe that STI could serve as a sensitive and noninvasive marker to study the collagen fibrils microstructure. Magn Reson Med 78:1683-1690, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  12. New Procedure for Treatment of Atrial Fibrillation in Patients with Valvular Heart Disease

    Directory of Open Access Journals (Sweden)

    Naser Safaie

    2010-10-01

    Full Text Available Patients with valvular heart disease suffer from atrial fibrillation for more than 12 months after valve surgery and have a low probability of remaining in sinus rhythm. We performed an intra-operative procedure similar to surgical maze ІІІ procedure for conversion of this arrhythmia to sinus rhythm. We did this study to evaluate the efficacy of this procedure to restore the sinus rhythm in patients with valvular heart disease. 28 patients with valvular heart disease and chronic persistent atrial fibrillation underwent different combinations of valve surgery and concomitant reduction of left and right atrial size and resection of both atrial auricles in Shahid Madani cardiothoracic center from September 2004 to October 2008. The procedure for atrial fibrillation treatment was performed with cardiopulmonary bypass and after mitral valve replacement. There was one in-hospital death postoperatively because of respiratory failure, but no other complication till 6 months after the operation. Out of 28 patients, 23 were in sinus rhythm one week after the operation, one patient had junctional rhythm after the operation that restored to sinus rhythm and 4 patients had persistent atrial fibrillation. During the 12-month follow up, atrial fibrillation was corrected in 82.14%. Doppler echocardiography in these patients with sinus rhythm demonstrated good atrial contractility. This procedure on both atria is effective and less invasive than the original maze procedure to eliminate the atrial fibrillation, and can be performed in patients with valvular heart disease without increasing the risk of operation.

  13. Contribution of Electrostatics in the Fibril Stability of a Model Ionic-Complementary Peptide.

    Science.gov (United States)

    Owczarz, Marta; Casalini, Tommaso; Motta, Anna C; Morbidelli, Massimo; Arosio, Paolo

    2015-12-14

    In this work we quantified the role of electrostatic interactions in the self-assembly of a model amphiphilic peptide (RADA 16-I) into fibrillar structures by a combination of size exclusion chromatography and molecular simulations. For the peptide under investigation, it is found that a net charge of +0.75 represents the ideal condition to promote the formation of regular amyloid fibrils. Lower net charges favor the formation of amorphous precipitates, while larger net charges destabilize the fibrillar aggregates and promote a reversible dissociation of monomers from the ends of the fibrils. By quantifying the dependence of the equilibrium constant of this reversible reaction on the pH value and the peptide net charge, we show that electrostatic interactions contribute largely to the free energy of fibril formation. The addition of both salt and a charged destabilizer (guanidinium hydrochloride) at moderate concentration (0.3-1 M) shifts the monomer-fibril equilibrium toward the fibrillar state. Whereas the first effect can be explained by charge screening of electrostatic repulsion only, the promotion of fibril formation in the presence of guanidinium hydrochloride is also attributed to modifications of the peptide conformation. The results of this work indicate that the global peptide net charge is a key property that correlates well with the fibril stability, although the peptide conformation and the surface charge distribution also contribute to the aggregation propensity.

  14. Atrial fibrillation associated with chocolate intake abuse and chronic salbutamol inhalation abuse.

    Science.gov (United States)

    Patanè, Salvatore; Marte, Filippo; La Rosa, Felice Carmelo; Rocca, Roberto La

    2010-11-19

    The use of substances as the substrate for atrial fibrillation is not frequently recognized. Chocolate is derived from the roasted seeds of the plant theobroma cacao and its components are the methylxanthine alkaloids theobromine and caffeine. Caffeine is a methylxanthine whose primary biological effect is the competitive antagonism of the adenosine receptor. Normal consumption of caffeine was not associated with risk of atrial fibrillation or flutter. Sympathomimetic effects, due to circulating catecholamines cause the cardiac manifestations of caffeine overdose toxicity, produce tachyarrhythmias such as supraventricular tachycardia, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.The commonly used doses of inhaled or nebulized salbutamol induced no acute myocardial ischaemia, arrhythmias or changes in heart rate variability in patients with coronary artery disease and clinically stable asthma or chronic obstructive pulmonary disease. Two-week salbutamol treatment shifts the cardiovascular autonomic regulation to a new level characterized by greater sympathetic responsiveness and slight beta2-receptor tolerance. We present a case of atrial fibrillation associated with chocolate intake abuse in a 19-year-old Italian woman with chronic salbutamol inhalation abuse. This case focuses attention on chocolate intake abuse associated with chronic salbutamol abuse as the substrate for atrial fibrillation. Copyright © 2008 Elsevier Ireland Ltd. All rights reserved.

  15. Collagen fibril architecture, domain organization, and triple-helical conformation govern its proteolysis.

    Science.gov (United States)

    Perumal, Shiamalee; Antipova, Olga; Orgel, Joseph P R O

    2008-02-26

    We describe the molecular structure of the collagen fibril and how it affects collagen proteolysis or "collagenolysis." The fibril-forming collagens are major components of all mammalian connective tissues, providing the structural and organizational framework for skin, blood vessels, bone, tendon, and other tissues. The triple helix of the collagen molecule is resistant to most proteinases, and the matrix metalloproteinases that do proteolyze collagen are affected by the architecture of collagen fibrils, which are notably more resistant to collagenolysis than lone collagen monomers. Until now, there has been no molecular explanation for this. Full or limited proteolysis of the collagen fibril is known to be a key process in normal growth, development, repair, and cell differentiation, and in cancerous tumor progression and heart disease. Peptide fragments generated by collagenolysis, and the conformation of exposed sites on the fibril as a result of limited proteolysis, regulate these processes and that of cellular attachment, but it is not known how or why. Using computational and molecular visualization methods, we found that the arrangement of collagen monomers in the fibril (its architecture) protects areas vulnerable to collagenolysis and strictly governs the process. This in turn affects the accessibility of a cell interaction site located near the cleavage region. Our observations suggest that the C-terminal telopeptide must be proteolyzed before collagenase can gain access to the cleavage site. Collagenase then binds to the substrate's "interaction domain," which facilitates the triple-helix unwinding/dissociation function of the enzyme before collagenolysis.

  16. Michler’s Hydrol Blue: A Sensitive Probe for Amyloid Fibril Detection

    KAUST Repository

    Kitts, Catherine C.

    2011-05-03

    Michler\\'s hydrol blue (MHB) is investigated with respect to photophysical properties in varied solvent environment and when bound to insulin and lysozyme fibrils. The MHB chromophore is shown to act like a molecular rotor and bind well to amyloid fibrils, where it exhibits a characteristic red-shift in its excitation spectrum and an increase in the emission quantum yield upon binding. MHB is more sensitive to environmental changes than Thioflavin T (ThT) and furthermore, in contrast to the latter amyloid probe, can differentiate between insulin and lysozyme fibrils by a more red-shifted excitation spectrum for insulin fibrils. To support the experimental observations, time-dependent density functional theory (TDDFT) calculations were performed on MHB at several levels of theory. The predicted changes of spectral properties as a function of the environment are in good agreement with the experimental results. Linear dichroism (LD) is used to determine the orientation of the MHB within the fibrils. It was shown through LD and molecular modeling that MHB aligns itself preferentially parallel with the amyloid fiber at an angle of 14°-22° to the fibril axis and along the grooves of the β-sheet. © 2011 American Chemical Society.

  17. Prevalence of thyroid dysfunction in patients with acute atrial fibrillation attended at a cardiology emergency room

    Directory of Open Access Journals (Sweden)

    Juarez Neuhaus Barbisan

    Full Text Available CONTEXT: Atrial fibrillation occurs frequently in patients with thyrotoxicosis, while it has low prevalence in adults of the general population. The prevalence of thyroid dysfunction in subjects with atrial fibrillation is 0 to 24%, a wide variation that is attributed to the different methodologies applied. However, continuous use of amiodarone in patients with previous atrial fibrillation may interfere with these prevalence rates. OBJECTIVE: In this study, we present the prevalence of thyroid dysfunction in adult patients who presented at a cardiac emergency room with acute atrial fibrillation, using a sensitive thyroid-stimulating hormone (TSH assay and triiodothyronine (T3 and thyroxine (T4 determination. TYPE OF STUDY: Cross-sectional study SETTING: Emergency room of a tertiary care facility. PARTICIPANTS: A total of 72 patients with atrial fibrillation who presented at the emergency room not more than 48 hours after its onset. PROCEDURES: A standardized questionnaire and 12-lead electrocardiogram were applied, and T3, T4 and TSH were determined. MAIN MEASUREMENTS: TSH, T3 and T4 determination. RESULTS: Among these patients, 16.6% had altered thyroid function tests: 6.9% had hyperthyroidism, 5.6% hypothyroidism and 4.2% had increased T4 levels, by means of amiodarone use. CONCLUSION: The high prevalence of thyroid dysfunction in our study, especially hyperthyroidism, suggests that routine thyroid testing with sensitivethyroid-stimulating hormone assay is required in patients with acute atrial fibrillation.

  18. New Procedure for Treatment of Atrial Fibrillation in Patients with Valvular Heart Disease

    Directory of Open Access Journals (Sweden)

    Naser Safaie

    2010-09-01

    Full Text Available "nPatients with valvular heart disease suffer from atrial fibrillation for more than 12 months after valve surgery and have a low probability of remaining in sinus rhythm. We performed an intra-operative procedure similar to surgical maze ІІІ procedure for conversion of this arrhythmia to sinus rhythm. We did this study to evaluate the efficacy of this procedure to restore the sinus rhythm in patients with valvular heart disease. 28 patients with valvular heart disease and chronic persistent atrial fibrillation underwent different combinations of valve surgery and concomitant reduction of left and right atrial size and resection of both atrial auricles in Shahid Madani cardiothoracic center from September 2004 to October 2008. The procedure for atrial fibrillation treatment was performed with cardiopulmonary bypass and after mitral valve replacement. There was one in-hospital death postoperatively because of respiratory failure, but no other complication till 6 months after the operation. Out of 28 patients, 23 were in sinus rhythm one week after the operation, one patient had junctional rhythm after the operation that restored to sinus rhythm and 4 patients had persistent atrial fibrillation. During the 12-month follow up, atrial fibrillation was corrected in 82.14%. Doppler echocardiography in these patients with sinus rhythm demonstrated good atrial contractility. This procedure on both atria is effective and less invasive than the original maze procedure to eliminate the atrial fibrillation, and can be performed in patients with valvular heart disease without increasing the risk of operation.

  19. Glycosaminoglycans enhance the fibrillation propensity of the ß2-microglobulin cleavage variant--¿K58-ß2m

    DEFF Research Database (Denmark)

    Corlin, Dorthe B; Johnsen, Christina K; Nissen, Mogens H

    2010-01-01

    when heparan sulfate is present have increased length and diameter, and possess enhanced stability and seeding properties. However, when copper ions are present the fibrils are short, thin and less stable, and form at a slower rate. We suggest that heparan sulfate stabilizes the cleaved monomers...... in the early aggregates, hereby promoting the assembly of these into fibrils, whereas the copper ions appear to have a destabilizing effect on the monomers. This keeps them in a structure forming amorphous aggregates for a longer period of time, leading to the formation of spherical bodies followed...... by the assembly of fibrils. Hence, the in vivo formation of amyloid fibrils in DRA could be initiated by the generation of ¿K58-ß2m which spontaneously aggregate and form fibrils. The fibrillogenesis is enhanced by the involvement of GAGs and/or metal ions, and results in amyloid-like fibrils able to promote...

  20. Mechanical properties of amyloid-like fibrils defined by secondary structures

    Science.gov (United States)

    Bortolini, C.; Jones, N. C.; Hoffmann, S. V.; Wang, C.; Besenbacher, F.; Dong, M.

    2015-04-01

    Amyloid and amyloid-like fibrils represent a generic class of highly ordered nanostructures that are implicated in some of the most fatal neurodegenerative diseases. On the other hand, amyloids, by possessing outstanding mechanical robustness, have also been successfully employed as functional biomaterials. For these reasons, physical and chemical factors driving fibril self-assembly and morphology are extensively studied - among these parameters, the secondary structures and the pH have been revealed to be crucial, since a variation in pH changes the fibril morphology and net chirality during protein aggregation. It is important to quantify the mechanical properties of these fibrils in order to help the design of effective strategies for treating diseases related to the presence of amyloid fibrils. In this work, we show that by changing pH the mechanical properties of amyloid-like fibrils vary as well. In particular, we reveal that these mechanical properties are strongly related to the content of secondary structures. We analysed and estimated the Young's modulus (E) by comparing the persistence length (Lp) - measured from the observation of TEM images by using statistical mechanics arguments - with the mechanical information provided by peak force quantitative nanomechanical property mapping (PF-QNM). The secondary structure content and the chirality are investigated by means of synchrotron radiation circular dichroism (SR-CD). Results arising from this study could be fruitfully used as a protocol to investigate other medical or engineering relevant peptide fibrils.Amyloid and amyloid-like fibrils represent a generic class of highly ordered nanostructures that are implicated in some of the most fatal neurodegenerative diseases. On the other hand, amyloids, by possessing outstanding mechanical robustness, have also been successfully employed as functional biomaterials. For these reasons, physical and chemical factors driving fibril self-assembly and morphology

  1. Sex-related differences in risk factors, type of treatment received and outcomes in patients with atrial fibrillation and acute stroke: Results from the RAF-study (Early Recurrence and Cerebral Bleeding in Patients with Acute Ischemic Stroke and Atrial Fibrillation)

    OpenAIRE

    Antonenko, Kateryna; Paciaroni, Maurizio; Agnelli, Giancarlo; Falocci, Nicola; Becattini, Cecilia; Marcheselli, Simona; Rueckert, Christina; Pezzini, Alessandro; Poli, Loris; Padovani, Alessandro; Csiba, Laszló; Szabó, Lilla; Sohn, Sung-Il; Tassinari, Tiziana; Abdul-Rahim, Azmil H

    2016-01-01

    Introduction: Atrial fibrillation is an independent risk factor of thromboembolism. Women with atrial fibrillation are at a higher overall risk for stroke compared to men with atrial fibrillation. The aim of this study was to evaluate for sex differences in patients with acute stroke and atrial fibrillation, regarding risk factors, treatments received and outcomes.\\ud Methods Data were analyzed from the “Recurrence and Cerebral Bleeding in Patients with Acute Ischemic Stroke and Atrial Fibril...

  2. Current driven wiggler

    Science.gov (United States)

    Tournes, C.; Aucouturier, J.; Arnaud, B.; Brasile, J. P.; Convert, G.; Simon, M.

    1992-07-01

    A current-driven wiggler is the cornerstone of an innovative, compact, high-efficiency, transportable tunable free-electron laser (FEL), the feasibility of which is currently being evaluated by Thomson-CSF. The salient advantages are: compactness of the FEL, along with the possibility to accelerate the beam through several successive passes through the accelerating section (the number of passes being defined by the final wavelength of the radiation; i.e. visible, MWIR, LWIR); the wiggler can be turned off and be transparent to the beam until the last pass. Wiggler periodicities as small as 5 mm can be achieved, hence contributing to FEL compactness. To achieve overall efficiencies in the range of 10% at visible wavelengths, not only the wiggler periodicity must be variable, but the strength of the magnetic field of each period can be adjusted separately and fine-tuned versus time during the macropulse, so as to take into account the growing contribution of the wave energy in the cavity to the total ponderomotive force. The salient theoretical point of this design is the optimization of the parameters defining each period of the wiggler for each micropacket of the macropulse. The salient technology point is the mechanical and thermal design of the wiggler which allows the required high currents to achieve magnetic fields up to 2T.

  3. Customer-driven competition

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, R. [Ontario Hydro, Toronto, ON (Canada)

    1996-12-31

    Ontario Hydro`s customer-driven strategy, recently approved by Hydro`s Executive Board, was described. The strategy is founded on the following components: (1) the dissolution of the Ontario power pool, i.e., the loss of Hydro`s franchise monopoly on generation, leaving only power transmission in the hands of the Corporation, (2) divestment of Ontario Hydro`s system operations and market operations functions to a new, independent Crown corporation called the Central Market Operator, (3) functional and organizational unbundling of Ontario Hydro into three signature businesses, Genco, Transco, and Retailco, and in the latter two, the functional unbundling of wires from sales and services, (4) a fully commercial Ontario Hydro with normal corporate powers, and (5) a corporate strategy for Ontario Hydro to grow in businesses in an open, symmetrical North American energy market. According to Ontario Hydro management this will allow competition and choice to all customers, have a disciplining effect on prices, and give rise to a retail market of new products and services, while at the same time preserve and enhance the value of public investment in the Corporation.

  4. Digitally-Driven Architecture

    Directory of Open Access Journals (Sweden)

    Henriette Bier

    2014-07-01

    Full Text Available The shift from mechanical to digital forces architects to reposition themselves: Architects generate digital information, which can be used not only in designing and fabricating building components but also in embedding behaviours into buildings. This implies that, similar to the way that industrial design and fabrication with its concepts of standardisation and serial production influenced modernist architecture, digital design and fabrication influences contemporary architecture. While standardisation focused on processes of rationalisation of form, mass-customisation as a new paradigm that replaces mass-production, addresses non-standard, complex, and flexible designs. Furthermore, knowledge about the designed object can be encoded in digital data pertaining not just to the geometry of a design but also to its physical or other behaviours within an environment. Digitally-driven architecture implies, therefore, not only digitally-designed and fabricated architecture, it also implies architecture – built form – that can be controlled, actuated, and animated by digital means.In this context, this sixth Footprint issue examines the influence of digital means as pragmatic and conceptual instruments for actuating architecture. The focus is not so much on computer-based systems for the development of architectural designs, but on architecture incorporating digital control, sens­ing, actuating, or other mechanisms that enable buildings to inter­act with their users and surroundings in real time in the real world through physical or sensory change and variation.

  5. Digitally-Driven Architecture

    Directory of Open Access Journals (Sweden)

    Henriette Bier

    2010-06-01

    Full Text Available The shift from mechanical to digital forces architects to reposition themselves: Architects generate digital information, which can be used not only in designing and fabricating building components but also in embedding behaviours into buildings. This implies that, similar to the way that industrial design and fabrication with its concepts of standardisation and serial production influenced modernist architecture, digital design and fabrication influences contemporary architecture. While standardisa­tion focused on processes of rationalisation of form, mass-customisation as a new paradigm that replaces mass-production, addresses non-standard, complex, and flexible designs. Furthermore, knowledge about the designed object can be encoded in digital data pertaining not just to the geometry of a design but also to its physical or other behaviours within an environment. Digitally-driven architecture implies, therefore, not only digitally-designed and fabricated architecture, it also implies architecture – built form – that can be controlled, actuated, and animated by digital means. In this context, this sixth Footprint issue examines the influence of digital means as prag­matic and conceptual instruments for actuating architecture. The focus is not so much on computer-based systems for the development of architectural designs, but on architecture incorporating digital control, sens­ing, actuating, or other mechanisms that enable buildings to inter­act with their users and surroundings in real time in the real world through physical or sensory change and variation.

  6. Customer-driven competition

    International Nuclear Information System (INIS)

    Taylor, R.

    1996-01-01

    Ontario Hydro's customer-driven strategy, recently approved by Hydro's Executive Board, was described. The strategy is founded on the following components: (1) the dissolution of the Ontario power pool, i.e., the loss of Hydro's franchise monopoly on generation, leaving only power transmission in the hands of the Corporation, (2) divestment of Ontario Hydro's system operations and market operations functions to a new, independent Crown corporation called the Central Market Operator, (3) functional and organizational unbundling of Ontario Hydro into three signature businesses, Genco, Transco, and Retailco, and in the latter two, the functional unbundling of wires from sales and services, (4) a fully commercial Ontario Hydro with normal corporate powers, and (5) a corporate strategy for Ontario Hydro to grow in businesses in an open, symmetrical North American energy market. According to Ontario Hydro management this will allow competition and choice to all customers, have a disciplining effect on prices, and give rise to a retail market of new products and services, while at the same time preserve and enhance the value of public investment in the Corporation

  7. Agent-based modeling traction force mediated compaction of cell-populated collagen gels using physically realistic fibril mechanics.

    Science.gov (United States)

    Reinhardt, James W; Gooch, Keith J

    2014-02-01

    Agent-based modeling was used to model collagen fibrils, composed of a string of nodes serially connected by links that act as Hookean springs. Bending mechanics are implemented as torsional springs that act upon each set of three serially connected nodes as a linear function of angular deflection about the central node. These fibrils were evaluated under conditions that simulated axial extension, simple three-point bending and an end-loaded cantilever. The deformation of fibrils under axial loading varied <0.001% from the analytical solution for linearly elastic fibrils. For fibrils between 100 μm and 200 μm in length experiencing small deflections, differences between simulated deflections and their analytical solutions were <1% for fibrils experiencing three-point bending and <7% for fibrils experiencing cantilever bending. When these new rules for fibril mechanics were introduced into a model that allowed for cross-linking of fibrils to form a network and the application of cell traction force, the fibrous network underwent macroscopic compaction and aligned between cells. Further, fibril density increased between cells to a greater extent than that observed macroscopically and appeared similar to matrical tracks that have been observed experimentally in cell-populated collagen gels. This behavior is consistent with observations in previous versions of the model that did not allow for the physically realistic simulation of fibril mechanics. The significance of the torsional spring constant value was then explored to determine its impact on remodeling of the simulated fibrous network. Although a stronger torsional spring constant reduced the degree of quantitative remodeling that occurred, the inclusion of torsional springs in the model was not necessary for the model to reproduce key qualitative aspects of remodeling, indicating that the presence of Hookean springs is essential for this behavior. These results suggest that traction force mediated matrix

  8. Circulating microRNA-1a is a biomarker of Graves' disease patients with atrial fibrillation.

    Science.gov (United States)

    Wang, Fang; Zhang, Sheng-Jie; Yao, Xuan; Tian, Dong-Mei; Zhang, Ke-Qin; She, Dun-Min; Guo, Fei-Fan; Zhai, Qi-Wei; Ying, Hao; Xue, Ying

    2017-07-01

    It has been increasingly suggested that specific microRNAs expression profiles in the circulation and atrial tissue are associated with the susceptibility to atrial fibrillation. Nonetheless, the role of circulating microRNAs in Graves' disease patients with atrial fibrillation has not yet been well described. The objective of the study was to identify the role of circulating microRNAs as specific biomarkers for the diagnosis of Graves' disease with atrial fibrillation. The expression profiles of eight serum microRNAs, which are found to be critical in the pathogenesis of atrial fibrillation, were determined in patients with Graves' disease with or without atrial fibrillation. MicroRNA expression analysis was performed by real-time PCR in normal control subjects (NC; n = 17), patients with Graves' disease without atrial fibrillation (GD; n = 29), patients with Graves' disease with atrial fibrillation (GD + AF; n = 14), and euthyroid patients with atrial fibrillation (AF; n = 22). Three of the eight serum microRNAs,i.e., miR-1a, miR-26a, and miR-133, had significantly different expression profiles among the four groups. Spearman's correlation analysis showed that the relative expression level of miR-1a was positively correlated with free triiodothyronine (FT3) and free thyroxine (FT4), and negatively related to thyroid stimulating hormone. Spearman's correlations analysis also revealed that the level of miR-1a was negatively correlated with a critical echocardiographic parameter (left atrial diameter), which was dramatically increased in GD + AF group compared to GD group. Furthermore, the receiver-operating characteristic curve analysis indicated that, among the eight microRNAs, miR-1a had the largest area under the receiver-operating characteristic curves not only for discriminating between individuals with and without Graves' disease, but also for predicting the presence of atrial fibrillation in patients with Graves' disease. Our findings

  9. Useful clinical features for the selection of ideal patients with strial fibrillation for mapping and catheter ablation

    Directory of Open Access Journals (Sweden)

    Mehta Niraj

    2002-01-01

    Full Text Available OBJECTIVE: To identify useful clinical characteristics for selecting patients eligible for mapping and ablation of atrial fibrillation. METHODS: We studied 9 patients with atrial fibrillation, without structural heart disease, associated with: 1 antiarrhythmic drugs, 2 symptoms of low cardiac output, and 3 intention to treat. Seven patients had paroxysmal atrial fibrillation and 2 had recurrent atrial fibrillation. RESULTS: In the 6 patients who underwent mapping (all had paroxysmal atrial fibrillation, catheter ablation was successfully carried out in superior pulmonary veins in 5 patients (the first 3 in the left superior pulmonary vein and the last 2 in the right superior pulmonary vein. One patient experienced a recurrence of atrial fibrillation after 10 days. We observed that patients who had short episodes of atrial fibrillation on 24-hour Holter monitoring before the procedure were those in whom mapping the focus of tachycardia was possible. Tachycardia was successfully suppressed in 4 of 6 patients. The cause of failure was due to the impossibility of maintaining sinus rhythm long enough for efficient mapping. CONCLUSION: Patients experiencing short episodes of atrial fibrillation during 24-hour Holter monitoring were the most eligible for mapping and ablation, with a final success rate of 66%, versus the global success rate of 44%. Patients with persistent atrial fibrillation were not good candidates for focal ablation.

  10. The Atrial Fibrillation Health Literacy Information Technology System: Pilot Assessment.

    Science.gov (United States)

    Magnani, Jared W; Schlusser, Courtney L; Kimani, Everlyne; Rollman, Bruce L; Paasche-Orlow, Michael K; Bickmore, Timothy W

    2017-01-01

    Atrial fibrillation (AF) is a highly prevalent heart rhythm condition that has significant associated morbidity and requires chronic treatment. Mobile health (mHealth) technologies have the potential to enhance multiple aspects of AF care, including education, monitoring of symptoms, and encouraging and tracking medication adherence. We have previously implemented and tested relational agents to improve outcomes in chronic disease and sought to develop a smartphone-based relational agent for improving patient-centered outcomes in AF. The objective of this study was to pilot a smartphone-based relational agent as preparation for a randomized clinical trial, the Atrial Fibrillation Health Literacy Information Technology Trial (AF-LITT). We developed the relational agent for use by a smartphone consistent with our prior approaches. We programmed the relational agent as a computer-animated agent to simulate a face-to-face conversation and to serve as a health counselor or coach specific to AF. Relational agent's dialogue content, informed by a review of literature, focused on patient-centered domains and qualitative interviews with patients with AF, encompassed AF education, common symptoms, adherence challenges, and patient activation. We established that the content was accessible to individuals with limited health or computer literacy. Relational agent content coordinated with use of the smartphone AliveCor Kardia heart rate and rhythm monitor. Participants (N=31) were recruited as a convenience cohort from ambulatory clinical sites and instructed to use the relational agent and Kardia for 30 days. We collected demographic, social, and clinical characteristics and conducted baseline and 30-day assessments of health-related quality of life (HRQoL) with the Atrial Fibrillation Effect on Quality of life (AFEQT) measure; self-reported medication adherence with the Morisky 8-item Medication Adherence Scale (MMAS-8); and patient activation with the Patient Activation

  11. Predictors of atrial fibrillation recurrence after cryoballoon ablation

    Directory of Open Access Journals (Sweden)

    Aksu T

    2015-06-01

    Full Text Available Tolga Aksu,1 Erkan Baysal,2 Tümer Erdem Guler,1 Sukriye Ebru Golcuk,3 İsmail Erden,1 Kazim Serhan Ozcan11Department of Cardiology, Derince Education and Research Hospital, Kocaeli, 2Department of Cardiology, Diyarbakir Education and Research Hospital, Diyarbakir, 3Department of Cardiology, Faculty of Medicine, Koc University, Istanbul, TurkeyObjective: Cryoballoon ablation (CA is a safe and efficient method for pulmonary vein isolation in the treatment of paroxysmal atrial fibrillation (AF. There are conflicting results about the predictors of AF recurrence. The aim of this study is to evaluate the role of hematological indices to predict AF recurrence after CA.Methods: A total of 49 patients (mean age 58.3±12.2 years, 51.02% female with symptomatic paroxysmal AF underwent CA procedure. One hundred and sixty-eight pulmonary veins were used for pulmonary vein isolation with the second-generation cryoballoon. The hematological samples were obtained before and 24 hours after ablation.Results: At a mean follow-up of 10.2±2.4 months, the probability of being arrhythmia-free after a single procedure was 86%. Patients with AF recurrence had higher red cell distribution width levels (16.10%±1.44% vs 14.87%±0.48%, P=0.035. The neutrophil/lymphocyte ratio, erythrocyte sedimentation rate, and C-reactive protein levels were detected in the patients with or without recurrence. Left atrial diameter (46.28±4.30 mm vs 41.02±4.10 mm, P=0.002, duration of AF (6.71±4.57 years vs 3.59±1.72 years, P=0.003, and age (65.01±15.39 years vs 54.29±11.32 years, P=0.033 were the other independent predictors of clinical recurrence after CA. Multiple regression analysis revealed that left atrial diameter was the only independent predictor for AF recurrence (P=0.012.Conclusion: In this study of patients with paroxysmal AF undergoing cryoablation, increased preablation red cell distribution width levels, and not C-reactive protein or erythrocyte sedimentation rate

  12. Age-related changes in human tendo calcaneus collagen fibrils

    International Nuclear Information System (INIS)

    Sargon, Mustafa F.; Ozlu, Korhan; Oken, Fuad

    2005-01-01

    The ruptures of tendo calcaneus often occur between the age group of 30-45 years as described by several text books. It is also described that some diseases and drugs are said to be responsible in the etiology; however, there are no studies related with the detailed histological structure of collagen fibrils found in the tendon in the age groups of humans. In view there of, this study was aimed to obtain further information on the etiology and to find an answer regarding the frequency the ruptures occurring between the age of 30-45 years in human. In the study, the biopsy specimen taken from 28 patients age (1-68) years who had undergone surgery due to tendo calcaneus ruptures or acilloplasty operations were examined by transmission electron microscope. All the specimens were prepared according to routine electronic microscope tissue preparation technique. The patients were divided into 7 age groups (1-9, 10-19, 20-29, 30-39, 40-49, 50-59, >60 years) and there were 4 patients in each group. The transverse diameters of collagen fibers were measured from the ultra thin sections and statistical analysis of the results were performed. The study was carried out in the electron microscopy laboratory of the Anatomy Department of Hacettepe University, Ankara, Turkey between January 2004 and September 2004. The diameters of the collagen fibers were higher in the 20-29 year-old groups compared to other groups and it showed a statistically significant difference. In patients who were in the 30-39 year old group or older, the diameters of the collagen fibers were lesser than the 20-29 year-old group. However, an increase was observed in the collagen fibril concentration of these groups. In examination of the specimens of patients who were under 20-year old, the diameter of the collagen fibers were less than 20-29 year -old group. The electron microscopic appearance of the tissue sample of a one year-old patient had a specific organization and in this patient, both the

  13. Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth.

    Science.gov (United States)

    Foley, Joseph; Hill, Shannon E; Miti, Tatiana; Mulaj, Mentor; Ciesla, Marissa; Robeel, Rhonda; Persichilli, Christopher; Raynes, Rachel; Westerheide, Sandy; Muschol, Martin

    2013-09-28

    Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the

  14. Anatomic relationship between left coronary artery and left atrium in patients undergoing atrial fibrillation ablation.

    Science.gov (United States)

    Anselmino, Matteo; Torri, Federica; Ferraris, Federico; Calò, Leonardo; Castagno, Davide; Gili, Sebastiano; Rovera, Chiara; Giustetto, Carla; Gaita, Fiorenzo

    2017-07-01

    Atrial fibrillation transcatheter ablation (TCA) is, within available atrial fibrillation rhythm control strategies, one of the most effective. To potentially improve ablation outcome in case of recurrent atrial fibrillation after a first procedure or in presence of structural myocardial disease, isolation of the pulmonary veins may be associated with extensive lesions within the left atrium. To avoid rare, but potentially life-threatening, complications, thorough knowledge and assessment of left atrium anatomy and its relation to structures in close proximity are, therefore, mandatory. Aim of the present study is to describe, by cardiac computed tomography, the anatomic relationship between aortic root, left coronary artery and left atrium in patients undergoing atrial fibrillation TCA. The cardiac computed tomography scan of 21 patients affected by atrial fibrillation was elaborated to segment left atrium, aortic root and left coronary artery from the surrounding structures and the following distances measured: left atrium and aortic root; left atrium roof and aortic root; left main coronary artery and left atrium; circumflex artery and left atrium appendage; and circumflex artery and mitral valve annulus. Above all, the median distance between left atrium and aortic root (1.9, 1.5-2.1 mm), and between circumflex artery and left atrium appendage ostium (3.0, 2.1-3.4 mm) were minimal (≤3 mm). None of measured distances significantly varied between patients presenting paroxysmal versus persistent atrial fibrillation. The anatomic relationship between left atrium and coronary arteries is extremely relevant when performing atrial fibrillation TCA by extensive lesions. Therefore, at least in the latter case, preablation imaging should be recommended to avoid rare, but potentially life-threatening, complications with the aim of an as well tolerated as possible procedure.

  15. High beat-to-beat blood pressure variability in atrial fibrillation compared to sinus rhythm.

    Science.gov (United States)

    Olbers, Joakim; Gille, Adam; Ljungman, Petter; Rosenqvist, Mårten; Östergren, Jan; Witt, Nils

    2018-02-07

    Atrial fibrillation (AF) is associated with an increased risk for cardiovascular morbidity and mortality, not entirely explained by thromboembolism. The underlying mechanisms for this association are largely unknown. Similarly, high blood pressure (BP) increases the risk for cardiovascular events. Despite this the interplay between AF and BP is insufficiently studied. The purpose of this study was to examine and quantify the beat-to-beat blood pressure variability in patients with AF in comparison to a control group of patients with sinus rhythm. We studied 33 patients - 21 in atrial fibrillation and 12 in sinus rhythm - undergoing routine coronary angiography. Invasive blood pressure was recorded at three locations: radial artery, brachial artery and ascending aorta. Blood pressure variability, defined as average beat-to-beat blood pressure difference, was calculated for systolic and diastolic blood pressure at each site. We observed a significant difference (p blood pressure variability between the atrial fibrillation and sinus rhythm groups at all locations. Systolic blood pressure variability roughly doubled in the atrial fibrillation group compared to the sinus rhythm group (4.9 and 2.4 mmHg respectively). Diastolic beat-to-beat blood pressure variability was approximately 6 times as high in the atrial fibrillation group compared to the sinus rhythm group (7.5 and 1.2 mmHg respectively). No significant difference in blood pressure variability was seen between measurement locations. Beat-to-beat blood pressure variability in patients with atrial fibrillation was substantially higher than in patients with sinus rhythm. Hemodynamic effects of this beat-to-beat variation in blood pressure may negatively affect vascular structure and function, which may contribute to the increased cardiovascular morbidity and mortality seen in patients with atrial fibrillation.

  16. Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth

    Science.gov (United States)

    Foley, Joseph; Hill, Shannon E.; Miti, Tatiana; Mulaj, Mentor; Ciesla, Marissa; Robeel, Rhonda; Persichilli, Christopher; Raynes, Rachel; Westerheide, Sandy; Muschol, Martin

    2013-09-01

    Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the

  17. Selective inhibition of aggregation/fibrillation of bovine serum albumin by osmolytes: Mechanistic and energetics insights.

    Directory of Open Access Journals (Sweden)

    Moumita Dasgupta

    Full Text Available Bovine serum albumin (BSA is an important transport protein of the blood and its aggregation/fibrillation would adversely affect its transport ability leading to metabolic disorder. Therefore, understanding the mechanism of fibrillation/aggregation of BSA and design of suitable inhibitor molecules for stabilizing its native conformation, are of utmost importance. The qualitative and quantitative aspects of the effect of osmolytes (proline, hydroxyproline, glycine betaine, sarcosine and sorbitol on heat induced aggregation/fibrillation of BSA at physiological pH (pH 7.4 have been studied employing a combination of fluorescence spectroscopy, Rayleigh scattering, isothermal titration calorimetry (ITC, dynamic light scattering (DLS and transmission electron microscopy (TEM. Formation of fibrils by BSA under the given conditions was confirmed from increase in fluorescence emission intensities of Thioflavin T over a time period of 600 minutes and TEM images. Absence of change in fluorescence emission intensities of 8-Anilinonaphthalene-1-sulfonic acid (ANS in presence of native and aggregated BSA signify the absence of any amorphous aggregates. ITC results have provided important insights on the energetics of interaction of these osmolytes with different stages of the fibrillar aggregates of BSA, thereby suggesting the possible modes/mechanism of inhibition of BSA fibrillation by these osmolytes. The heats of interaction of the osmolytes with different stages of fibrillation of BSA do not follow a trend, suggesting that the interactions of stages of BSA aggregates are osmolyte specific. Among the osmolytes used here, we found glycine betaine to be supporting and promoting the aggregation process while hydroxyproline to be maximally efficient in suppressing the fibrillation process of BSA, followed by sorbitol, sarcosine and proline in the following order of their decreasing potency: Hydroxyproline> Sorbitol> Sarcosine> Proline> Glycine betaine.

  18. Nebivolol in preventing atrial fibrillation following coronary surgery in patients over 60 years of age

    Directory of Open Access Journals (Sweden)

    Nevzat Erdil

    2014-12-01

    Full Text Available Objective: Postoperative atrial fibrillation is a common complication after cardiac surgery, with an incidence as high as 20-50%. Increased age is associated with a significant increase in postoperative atrial fibrillation risk. This common complication is associated with higher morbidity and mortality rates. The aim of this study was to assess the efficacy of nebivolol in preventing atrial fibrillation following coronary artery bypass surgery in patients over 60 years of age. Methods: In this prospective randomized study, 200 patients who were candidates for elective coronary artery bypass surgery were divided into two groups. The first group was administered with nebivolol and the second group was administered with metoprolol. Treatment was initiated four days prior to surgery, and patients were monitored for atrial fibrillation until discharge. Forty-one patients recieved 50 mg metoprolol succinate daily, which was initiated minimum 4 days before surgery. Results: Demographic data were similar in both groups. The incidence of postoperative atrial fibrillation in both groups was similar, with no significant difference being identified [n=20 (20%; n=18 (18%, P=0.718; respectively]. There were not any mortality at both groups during study. Inotropic agent requirement at ICU was similar for both groups [n=12 (12%, n=18 (18%, P=0.32]. Conclusion: We compared the effectiveness of nebivolol and metoprolol in decreasing the incidence of postoperative atrial fibrillation, and determined that nebivolol was as effective as metoprolol in preventing postoperative atrial fibrillation at patients. Nebivolol may be the drug of choice due to its effects, especially after elective coronary artery bypass surgery.

  19. Risk factors for stroke and thromboembolism in relation to age among patients with atrial fibrillation: the loire valley atrial fibrillation project

    DEFF Research Database (Denmark)

    Olesen, Jonas Bjerring; Fauchier, Laurent; Lane, Deirdre A

    2012-01-01

    According to the latest European guidelines on the management of nonvalvular atrial fibrillation (NVAF), all patients aged ≥ 65 years should be treated with oral anticoagulation (if not contraindicated). Therefore, stroke risk factors should be investigated exclusively in patients with NVAF aged...

  20. Higher burden of supraventricular ectopic complexes early after catheter ablation for atrial fibrillation is associated with increased risk of recurrent atrial fibrillation

    DEFF Research Database (Denmark)

    Alhede, Christina; Johannessen, Arne; Dixen, Ulrik

    2018-01-01

    AIMS: Early identification of patients who could benefit from early re-intervention after catheter ablation is highly warranted. Our aim was to investigate the association between post-procedural burden of supraventricular ectopic complexes (SVEC) and the risk of long-term atrial fibrillation (AF...

  1. Atrial Fibrillation and Non-cardiovascular Diseases: A Systematic Review

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cátia, E-mail: catiaspferreira@hotmail.com; Providência, Rui; Ferreira, Maria João; Gonçalves, Lino Manuel [Faculdade de Medicina da Universidade de Coimbra, Coimbra (Portugal); Serviço de Cardiologia - Centro Hospitalar e Universitário de Coimbra, Coimbra (Portugal)

    2015-11-15

    Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an unfavorable prognosis, increasing the risk of stroke and death. Although traditionally associated with cardiovascular diseases, there is increasing evidence of high incidence of AF in patients with highly prevalent noncardiovascular diseases, such as cancer, sepsis, chronic obstructive pulmonary disease, obstructive sleep apnea and chronic kidney disease. Therefore, considerable number of patients has been affected by these comorbidities, leading to an increased risk of adverse outcomes. The authors performed a systematic review of the literature aiming to better elucidate the interaction between these conditions. Several mechanisms seem to contribute to the concomitant presence of AF and noncardiovascular diseases. Comorbidities, advanced age, autonomic dysfunction, electrolyte disturbance and inflammation are common to these conditions and may predispose to AF. The treatment of AF in these patients represents a clinical challenge, especially in terms of antithrombotic therapy, since the scores for stratification of thromboembolic risk, such as the CHADS{sub 2} and CHA{sub 2}DS{sub 2}VASc scores, and the scores for hemorrhagic risk, like the HAS-BLED score have limitations when applied in these conditions. The evidence in this area is still scarce and further investigations to elucidate aspects like epidemiology, pathogenesis, prevention and treatment of AF in noncardiovascular diseases are still needed.

  2. Atrial Fibrillation and Non-cardiovascular Diseases: A Systematic Review

    International Nuclear Information System (INIS)

    Ferreira, Cátia; Providência, Rui; Ferreira, Maria João; Gonçalves, Lino Manuel

    2015-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an unfavorable prognosis, increasing the risk of stroke and death. Although traditionally associated with cardiovascular diseases, there is increasing evidence of high incidence of AF in patients with highly prevalent noncardiovascular diseases, such as cancer, sepsis, chronic obstructive pulmonary disease, obstructive sleep apnea and chronic kidney disease. Therefore, considerable number of patients has been affected by these comorbidities, leading to an increased risk of adverse outcomes. The authors performed a systematic review of the literature aiming to better elucidate the interaction between these conditions. Several mechanisms seem to contribute to the concomitant presence of AF and noncardiovascular diseases. Comorbidities, advanced age, autonomic dysfunction, electrolyte disturbance and inflammation are common to these conditions and may predispose to AF. The treatment of AF in these patients represents a clinical challenge, especially in terms of antithrombotic therapy, since the scores for stratification of thromboembolic risk, such as the CHADS 2 and CHA 2 DS 2 VASc scores, and the scores for hemorrhagic risk, like the HAS-BLED score have limitations when applied in these conditions. The evidence in this area is still scarce and further investigations to elucidate aspects like epidemiology, pathogenesis, prevention and treatment of AF in noncardiovascular diseases are still needed

  3. Pharmacologic Therapy in the Elderly with Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Shih-Huang Lee

    2008-03-01

    Full Text Available Atrial fibrillation (AF is the most common sustained arrhythmia, and its prevalence significantly increases with age. Morphologic changes in the atrial myocardium associated with AF may result from underlying cardiovascular disease and/or physiologic aging processes. Congestive heart failure, tachycardia-induced cardiomyopathy and thromboembolic events resulting from AF are more common in elderly patients. It is important to assess any comorbidity and potential triggers of AF before considering pharmacologic therapy for AF. Proper rate control should include control in response to exercise, together with an avoidance of bradycardias and symptomatic pauses in patients with AF. Digoxin, β-blockers and calcium channel blockers can all be effective in controlling ventricular rate in elderly patients with AF. In the elderly, amiodarone is probably the safest drug for short-term administration to exert chemical cardioversion, facilitate electrical cardioversion, and prevent recurrence of AF. Warfarin has been shown to be highly effective in preventing stroke in the elderly with AF; however, many studies also have documented underuse of warfarin, may be because of the increased risk of warfarin-induced hemorrhage in such patients. These findings have raised concerns regarding quality of care, physician adherence to guidelines, and translation of clinical trial results into real-world practice in anticoagulation therapy in the elderly with AF. [International Journal of Gerontology 2008; 2(1: 1–6

  4. Pacemaker implantation after catheter ablation for atrial fibrillation.

    Science.gov (United States)

    Deshmukh, Abhishek J; Yao, Xiaoxi; Schilz, Stephanie; Van Houten, Holly; Sangaralingham, Lindsey R; Asirvatham, Samuel J; Friedman, Paul A; Packer, Douglas L; Noseworthy, Peter A

    2016-01-01

    Sinus node dysfunction requiring pacemaker implantation is commonly associated with atrial fibrillation (AF), but may not be clinically apparent until restoration of sinus rhythm with ablation or cardioversion. We sought to determine frequency, time course, and predictors for pacemaker implantation after catheter ablation, and to compare the overall rates to a matched cardioversion cohort. We conducted a retrospective analysis using a large US commercial insurance database and identified 12,158 AF patients who underwent catheter ablation between January 1, 2005 and December 31, 2012. Over an average of 2.4 years of follow-up, 5.6 % of the patients underwent pacemaker implantation. Using the Cox proportional hazards models, we found that risk of risks of pacemaker implantation was associated with older age (50-64 and ≥65 versus pacemaker implantation between ablation patients and propensity score (PS)-matched cardioversion groups (3.5 versus. 4.1 % at 1 year and 8.8 versus 8.3 % at 5 years). Overall, pacemaker implantation occurs in about 1/28 patients within 1 year of catheter ablation. The overall implantation rate decreased between 2005 and 2012. Furthermore, the risk after ablation is similar to cardioversion, suggesting that patients require pacing due to a common underlying electrophysiologic substrate, rather than the ablation itself.

  5. Anticoagulation knowledge in patients with atrial fibrillation: An Australian survey.

    Science.gov (United States)

    Obamiro, Kehinde O; Chalmers, Leanne; Lee, Kenneth; Bereznicki, Bonnie J; Bereznicki, Luke R E

    2018-03-01

    Atrial fibrillation (AF) is the most commonly diagnosed arrhythmia in clinical practice, and is associated with a significant medical and economic burden. Anticoagulants reduce the risk of stroke and systemic embolism by approximately two-thirds compared with no therapy. Knowledge regarding anticoagulant therapy can influence treatment outcomes in patients with AF. To measure the level of anticoagulation knowledge in patients with AF taking oral anticoagulants (OACs), investigate the association between patient-related factors and anticoagulation knowledge, and compare these results in patients taking warfarin and direct-acting oral anticoagulant (DOACs). Participants were recruited for an online survey via Facebook. Survey components included the Anticoagulation Knowledge Tool, the Perception of Anticoagulant Treatment Questionnaires (assessing treatment expectations, convenience and satisfaction), a modified Cancer Information Overload scale and the Morisky Medication Adherence Scale. Treatment groups were compared and predictors of OAC knowledge were identified. Participants taking warfarin had a higher knowledge score compared with those taking DOACs (n = 386, 73% ± 13% vs 66% ± 14%, Pcounselling sessions to help identify and resolve knowledge deficits. © 2018 John Wiley & Sons Ltd.

  6. Burst stimulation improves hemodynamics during resuscitation after prolonged ventricular fibrillation.

    Science.gov (United States)

    Walcott, Gregory; Melnick, Sharon; Killingsworth, Cheryl; Ideker, Raymond

    2009-02-01

    Although return of spontaneous circulation (ROSC) is frequently achieved during resuscitation for sudden cardiac arrest, systolic blood pressure can then decrease, requiring additional myocardial support. Previous studies have shown that a series of 1-ms electrical pulses delivered through the defibrillation patches during ventricular fibrillation (VF) can stimulate the autonomic nervous system to increase myocardial function following defibrillation. We hypothesized that a similar series of electrical pulses could increase myocardial function and blood pressure during the early post-resuscitation period. Six swine were studied that underwent 6-7 min. Each animal received 5, 10, 15, or 20 pulse packets consisting of 6 10 A, 1-ms pulses every 3-4 s in random order whenever systolic blood pressure became less than 50 mmHg. All four sets of pulse packets were delivered to each animal. Systolic blood pressure and cardiac function (left ventricular +dP/dt) were increased to pre-stimulation levels or above by all four sets of pulse packets. The increases were significantly greater for the longer than the shorter number of pulse packets. The mean+/-SD duration of the time that the systolic pressure remained above 50 mmHg following pulse delivery was 4.2+/-2.5 min. Electrical stimulation during regular rhythm following prolonged VF and resuscitation can increase blood pressure and cardiac function to above prestimulation levels.

  7. Simple Model for Identifying Critical Regions in Atrial Fibrillation

    Science.gov (United States)

    Christensen, Kim; Manani, Kishan A.; Peters, Nicholas S.

    2015-01-01

    Atrial fibrillation (AF) is the most common abnormal heart rhythm and the single biggest cause of stroke. Ablation, destroying regions of the atria, is applied largely empirically and can be curative but with a disappointing clinical success rate. We design a simple model of activation wave front propagation on an anisotropic structure mimicking the branching network of heart muscle cells. This integration of phenomenological dynamics and pertinent structure shows how AF emerges spontaneously when the transverse cell-to-cell coupling decreases, as occurs with age, beyond a threshold value. We identify critical regions responsible for the initiation and maintenance of AF, the ablation of which terminates AF. The simplicity of the model allows us to calculate analytically the risk of arrhythmia and express the threshold value of transversal cell-to-cell coupling as a function of the model parameters. This threshold value decreases with increasing refractory period by reducing the number of critical regions which can initiate and sustain microreentrant circuits. These biologically testable predictions might inform ablation therapies and arrhythmic risk assessment.

  8. Post-operative atrial fibrillation: a maze of mechanisms

    Science.gov (United States)

    Maesen, Bart; Nijs, Jan; Maessen, Jos; Allessie, Maurits; Schotten, Ulrich

    2012-01-01

    Post-operative atrial fibrillation (POAF) is one of the most frequent complications of cardiac surgery and an important predictor of patient morbidity as well as of prolonged hospitalization. It significantly increases costs for hospitalization. Insights into the pathophysiological factors causing POAF have been provided by both experimental and clinical investigations and show that POAF is ‘multi-factorial’. Facilitating factors in the mechanism of the arrhythmia can be classified as acute factors caused by the surgical intervention and chronic factors related to structural heart disease and ageing of the heart. Furthermore, some proarrhythmic mechanisms specifically occur in the setting of POAF. For example, inflammation and beta-adrenergic activation have been shown to play a prominent role in POAF, while these mechanisms are less important in non-surgical AF. More recently, it has been shown that atrial fibrosis and the presence of an electrophysiological substrate capable of maintaining AF also promote the arrhythmia, indicating that POAF has some proarrhythmic mechanisms in common with other forms of AF. The clinical setting of POAF offers numerous opportunities to study its mechanisms. During cardiac surgery, biopsies can be taken and detailed electrophysiological measurements can be performed. Furthermore, the specific time course of POAF, with the delayed onset and the transient character of the arrhythmia, also provides important insight into its mechanisms. This review discusses the mechanistic interaction between predisposing factors and the electrophysiological mechanisms resulting in POAF and their therapeutic implications. PMID:21821851

  9. Concomitant atrial fibrillation surgery for people undergoing cardiac surgery

    Science.gov (United States)

    Huffman, Mark D; Karmali, Kunal N; Berendsen, Mark A; Andrei, Adin-Cristian; Kruse, Jane; McCarthy, Patrick M; Malaisrie, S C

    2016-01-01

    Background People with atrial fibrillation (AF) often undergo cardiac surgery for other underlying reasons and are frequently offered concomitant AF surgery to reduce the frequency of short- and long-term AF and improve short- and long-term outcomes. Objectives To assess the effects of concomitant AF surgery among people with AF who are undergoing cardiac surgery on short-term and long-term (12 months or greater) health-related outcomes, health-related quality of life, and costs. Search methods Starting from the year when the first “maze” AF surgery was reported (1987), we searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (March 2016), MEDLINE Ovid (March 2016), Embase Ovid (March 2016), Web of Science (March 2016), the Database of Abstracts of Reviews of Effects (DARE, April 2015), and Health Technology Assessment Database (HTA, March 2016). We searched trial registers in April 2016. We used no language restrictions. Selection criteria We included randomised controlled trials evaluating the effect of any concomitant AF surgery compared with no AF surgery among adults with preoperative AF, regardless of symptoms, who were undergoing cardiac surgery for another indication. Data collection and analysis Two review authors independently selected studies and extracted data. We evaluated the risk of bias using the Cochrane ‘Risk of bias’ tool. We included outcome data on all-cause and cardiovascular-specific mortality, freedom from atrial fibrillation, flutter, or tachycardia off antiarrhythmic medications, as measured by patient electrocardiographic monitoring greater than three months after the procedure, procedural safety, 30-day rehospitalisation, need for post-discharge direct current cardioversion, health-related quality of life, and direct costs. We calculated risk ratios (RR) for dichotomous data with 95% confidence intervals (CI) using a fixed-effect model when heterogeneity was low (I2 ≤ 50%) and random

  10. Atrial fibrillation and gastroesophageal reflux disease: the cardiogastric interaction.

    Science.gov (United States)

    Linz, Dominik; Hohl, Mathias; Vollmar, Johanna; Ukena, Christian; Mahfoud, Felix; Böhm, Michael

    2017-01-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with significant morbidity and mortality. Multiple conditions like hypertension, heart failure, diabetes, sleep apnoea, and obesity play a role for the initiation and perpetuation of AF. Recently, a potential association between gastroesophageal reflux disease (GERD) and AF development has been proposed due to the close anatomic vicinity of the oesophagus and the left atrium. As an understanding of the association between acid reflux disease and AF may be important in the global multimodal treatment strategy to further improve outcomes in a subset of patients with AF, we discuss potential atrial arrhythmogenic mechanisms in patients with GERD, such as gastric and subsequent systemic inflammation, impaired autonomic stimulation, mechanical irritation due to anatomical proximity of the left atrium and the oesophagus, as well as common comorbidities like obesity and sleep-disordered breathing. Data on GERD and oesophageal lesions after AF-ablation procedures will be reviewed. Treatment of GERD to avoid AF or to reduce AF burden might represent a future treatment perspective but needs to be scrutinized in prospective trials. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  11. Hundred years of atrial fibrillation: Current knowledge and perspectives

    Directory of Open Access Journals (Sweden)

    Potpara Tatjana

    2010-01-01

    Full Text Available Atrial fibrillation (AF is the most common sustained arrhythmia in general population. AF in humans was first described in 1903. Gradually, it has been well appreciated that AF is not just an acceptable alternative for normal rhythm but rather a serious threat, related to increased mortality and cardiovascular morbidity. AF can precipitate or worsen pre-existing heart failure, may cause the development of tachycardiomyopathy and is an independent risk factor for thromboembolic events, most frequently stroke. It has long been believed that rhythm control is the best therapy for AF. Nowadays there is a clear scientific proof that rhythm control offers no benefit over frequency control, at least for older patients, even with advanced left ventricular dysfunction. However, optimal treatment for younger, highly symptomatic, otherwise healthy AF patients has not been designed. Available antiarrhythmics have considerable proarrhythmic potential or organ toxicity, and new safer drugs are under investigation. Nonpharmacological approaches, namely RF-catheter ablation, are rapidly developing. Prevention of thromboembolism is imperative, and new safer oral anticoagulants have been intensively investigated. Recent randomized studies (PIAF, RACE, STAF, AFFIRM, HOT-CAFE did not solve the issue of optimal arrhythmia treatment, but they emphasized the prevention of thromboembolism based on risk factors, and not on AF type, mainly because asymptomatic episodes of AF may not be clinically recognized.

  12. Statin and Atrial Fibrilation: When does it work?

    Science.gov (United States)

    Fauchier, Laurent; Clementy, Nicolas; Pierre, Bertrand; Babuty, Dominique

    2012-01-01

    In the recent years, some clinical and experimental studies have suggested that the use of statins may protect against atrial fibrillation (AF). A relation between inflammation and the development of AF has been described, and the potent anti-inflammatory and antioxidant properties of statins may make them effective in preventing the development of AF. A global analysis of the literature suggests that the use of statins is associated with a decreased risk of incidence or recurrence of AF in some cases. However, this beneficial effect is not seen for all types of AF in all the patients. The use of statins seems associated 1) with a lack of benefit in primary prevention of AF, 2) with a significant but heterogeneous decreased risk of recurrence of AF in secondary prevention, and 3) with a very significant and homogeneous reduction for the risk of post operative AF. An intensive lipid lowering statin regimen does not provide greater protection against AF. Patients with coronary heart disease are curr ently treated with statins in most cases, and this may not have an impact on their treatment. In contrast, it remains to determine more accurately if statins may bring a significant benefit for some AF patients without any type of established atherosclerotic disease or with a low risk of atherogenesis. Since it remains uncertain whether the suppression of AF in these patients is beyond doubt beneficial, prescribing statins for this purpose alone should not be recommended at the present time.

  13. Amiodaron in atrial fibrillation: post coronary artery bypass graft.

    Science.gov (United States)

    Habibollahi, Paria; Jam, Shahrzad Hashemi; Vahdati, Samad Shams; Baghi, Hamidreza Morteza; Amiri, Hassan

    2016-01-01

    Atrial fibrilation (AF) is the most common complication following heart surgeries; it often occurs in patients after coronary artery bypass graft (CABG). The purpose of this review is to categorize prophylaxes or treatment by administration of Amiodaron in patients with CABG. We searched google scholar, pubmed, and Cochrane Library databases (the period 1970-2010) for articles on Amiodaron in CABG and cardiac surgery. A total of 1 561 articles were identified, and 30 articles met the criteria and were enrolled in this review. Most studies supported Amiodarone for prophylaxi purpose in patients who were performed with CABG; few papers supported Amiodaron as a drug for treating CABG. The prophylaxis can decrease the incidence rate of AF in CABG, but if it uses as a treatment, the side effect of Amiodaron will decrease because all of the patients will not get Amiodarone. In the other hand use of Amiodarone as a treatment does not influence the length of hospital stay significantly but these kinds of study are so few. No appropriate therapeutic method has been defined for AF. At present, the common way of treating AF following cardiac surgery is mainly based on prophylaxis in medical books and references.

  14. Measurement of ventricular function by ECG gating during atrial fibrillation

    International Nuclear Information System (INIS)

    Bacharach, S.L.; Green, M.V.; Bonow, R.O.; Findley, S.L.; Ostrow, H.G.; Johnston, G.S.

    1981-01-01

    The assumptions necessary to perform ECG-gated cardiac studies are seemingly not valid for patients in atrial fibrillation (AF). To evaluate the effect of AF on equilibrium gated scintigraphy, beat-by-beat measurements of left-ventricular function were made on seven subjects in AF (mean heart rate 64 bpm), using a high-efficiency nonimaging detector. The parameters evaluated were ejection fraction (EF), time to end-systole (TES), peak rates of ejection and filling (PER,PFR), and their times of occurrence (TPER, TPFR). By averaging together single-beat values of EF, PER, etc., it was possible to determine the true mean values of these parameters. The single-beam mean values were compared with the corresponding parameters calculated from one ECG-gated time-activity curve (TAC) obtained by superimposing all the single-beat TACs irrespective of their length. For this population with slow heart rates, we find that the values for EF, etc., produced from ECG-gated time-activity curves, are very similar to those obtained from the single-beat data. Thus use of ECG gating at low heart rates may allow reliable estimation of average cardiac function even in subjects with AF

  15. Atrial Fibrillation and Heart Failure - Cause or Effect?

    Science.gov (United States)

    Prabhu, Sandeep; Voskoboinik, Aleksandr; Kaye, David M; Kistler, Peter M

    2017-09-01

    There are emerging epidemics of atrial fibrillation (AF) and heart failure in most developed countries, with a significant health burden. Due to many shared pathophysiological mechanisms, which facilitate the maintenance of each condition, AF and heart failure co-exist in up to 30% of patients. In the circumstance where known structural causes of heart failure (such as myocardial infarction) are absent, patients presenting with both conditions present a unique challenge, particularly as the temporal relationship of each condition can often remain elusive from the clinical history. The question of whether the AF is driving, or significantly contributing to the left ventricular (LV) dysfunction, rather than merely a consequence of heart failure, has become ever more pertinent, especially as catheter ablation now offers a significant advancement over existing rhythm control strategies. This paper will review the inter-related physiological drivers of AF and heart failure before considering the implications from the outcomes of recent clinical trials in patients with AF and heart failure. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  16. Atrial Fibrillation Detection via Accelerometer and Gyroscope of a Smartphone.

    Science.gov (United States)

    Lahdenoja, Olli; Hurnanen, Tero; Iftikhar, Zuhair; Nieminen, Sami; Knuutila, Timo; Saraste, Antti; Kiviniemi, Tuomas; Vasankari, Tuija; Airaksinen, Juhani; Pankaala, Mikko; Koivisto, Tero

    2018-01-01

    We present a smartphone-only solution for the detection of atrial fibrillation (AFib), which utilizes the built-in accelerometer and gyroscope sensors [inertial measurement unit, (IMU)] in the detection. Depending on the patient's situation, it is possible to use the developed smartphone application either regularly or occasionally for making a measurement of the subject. The smartphone is placed on the chest of the patient who is adviced to lay down and perform a noninvasive recording, while no external sensors are needed. After that, the application determines whether the patient suffers from AFib or not. The presented method has high potential to detect paroxysmal ("silent") AFib from large masses. In this paper, we present the preprocessing, feature extraction, feature analysis, and classification results of the envisioned AFib detection system based on clinical data acquired with a standard mobile phone equipped with Google Android OS. Test data was gathered from 16 AFib patients (validated against ECG), as well as a control group of 23 healthy individuals with no diagnosed heart diseases. We obtained an accuracy of 97.4% in AFib versus healthy classification (a sensitivity of 93.8% and a specificity of 100%). Due to the wide availability of smart devices/sensors with embedded IMU, the proposed methods could potentially also scale to other domains such as embedded body-sensor networks.

  17. New technologies in treatment of atrial fibrillation in cardiosurgical patients

    Science.gov (United States)

    Evtushenko, A. V.; Evtushenko, V. V.; Bykov, A. N.; Sergeev, V. S.; Syryamkin, V. I.; Kistenev, Yu. V.; Anfinogenova, Ya. D.; Smyshlyaev, K. A.; Kurlov, I. O.

    2015-11-01

    The article is devoted to the evaluation of the results of clinical application of penetrating radiofrequency ablation techniques on atrial myocardium. Total operated on 241 patients with valvular heart disease and coronary heart disease complicated with atrial fibrillation. All operations were performed under cardiopulmonary bypass and cardioplegia. The main group consists of 141 patients which were operated using penetrating technique radiofrequency exposure. The control group consisted of 100 patients who underwent surgery with the use of "classical" monopolar RF-ablation technique. Both groups were not significantly different on all counts before surgery. Patients with previous heart surgery were excluded during the selection of candidates for the procedure, due to the presence of adhesions in the pericardium, that do not allow good visualization of left atrium, sufficient to perform this procedure. Penetrating technique has significantly higher efficiency compared to the "classic" technique in the early and long-term postoperative periods. In the early postoperative period, its efficiency is 93%, and in the long term is 88%. The efficacy of "classical" monopolar procedure is below: 86% and 68% respectively.

  18. Stroke Prevention in Atrial Fibrillation and Valvular Heart Disease.

    Science.gov (United States)

    Ahmad, Saad; Wilt, Heath

    2016-01-01

    There is a clinically staggering burden of disease stemming from cerebrovascular events, of which a majority are ischemic in nature and many are precipitated by atrial fibrillation (AF). AF can occur in isolation or in association with myocardial or structural heart disease. In the latter case, and when considering health at an international level, congenital and acquired valve-related diseases are frequent contributors to the current pandemic of AF and its clinical impact. Guidelines crafted by the American Heart Association, American College of Cardiology, European Society of Cardiology and Heart Rhythm Society underscore the use of vitamin K antagonists (VKAs) among patients with valvular heart disease, particularly in the presence of concomitant AF, to reduce the risk of ischemic stroke of cardioembolic origin; however, the non-VKAs, also referred to as direct, target-specific or new oral anticoagulants (NOACs), have not been actively studied in this particular population. In fact, each of the new agents is approved in patients with AF not caused by a valve problem. The aim of our review is to carefully examine the available evidence from pivotal phase 3 clinical trials of NOACs and determine how they might perform in patients with AF and concomitant valvular heart disease.

  19. Comparing the 2010 North American and European atrial fibrillation guidelines.

    Science.gov (United States)

    Gillis, Anne M; Skanes, Allan C

    2011-01-01

    This article compares the important differences in the American College of Cardiology Foundation (ACCF)/American Heart Association (AHA)/Heart Rhythm Society (HRS), Canadian Cardiovascular Society (CCS), and European Society of Cardiology (ESC) 2010 guidelines on atrial fibrillation (AF). All guidelines recommend more lenient targets for ventricular rate control although the CCS guidelines recommend a target heart rate at rest guidelines accept a target heart rate at rest guidelines recommend that the choice of antiarrhythmic drug for maintenance of sinus rhythm be based on the underlying cardiovascular disease state. However, the CCS guidelines do not recommend that the use of Class IC drugs or sotalol be restricted in the presence of left ventricular hypertrophy alone. All the guidelines have incorporated dronedarone into their recommendations of antiarrhythmic drug therapy for maintenance of sinus rhythm. However, the CCS guidelines do not make a specific recommendation that the use of dronedarone is reasonable to decrease the risk of hospitalization for cardiovascular causes in patients with AF. The ACCF/AHA/HRS update makes a strong recommendation for catheter ablation in patients with paroxysmal AF who have failed a single anti-arrhythmic drug whereas the CCS and ESC guidelines make this a conditional recommendation. The CCS guidelines are the only guidelines at present that recommend dabigitran for prevention of stroke in high risk patients and suggest that dabigatran is preferred to warfarin for stroke prevention in most patient groups. Copyright © 2011 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  20. Acute exposure to air pollution triggers atrial fibrillation.

    Science.gov (United States)

    Link, Mark S; Luttmann-Gibson, Heike; Schwartz, Joel; Mittleman, Murray A; Wessler, Benjamin; Gold, Diane R; Dockery, Douglas W; Laden, Francine

    2013-08-27

    This study sought to evaluate the association of air pollution with the onset of atrial fibrillation (AF). Air pollution in general and more specifically particulate matter has been associated with cardiovascular events. Although ventricular arrhythmias are traditionally thought to convey the increased cardiovascular risk, AF may also contribute. Patients with dual chamber implantable cardioverter-defibrillators (ICDs) were enrolled and followed prospectively. The association of AF onset with air quality including ambient particulate matter pollution between 2 and 48 h prior to the AF were examined. Of 176 patients followed for an average of 1.9 years, 49 patients had 328 episodes of AF lasting ≥ 30 s. Positive but nonsignificant associations were found for PM2.5 in the prior 24 h, but stronger associations were found with shorter exposure windows. The odds of AF increased by 26% (95% confidence interval: 8% to 47%) for each 6.0 μg/m(3) increase in PM2.5 in the 2 h prior to the event (p = 0.004). The odds of AF were highest at the upper quartile of mean PM2.5. PM was associated with increased odds of AF onset within hours following exposure in patients with known cardiac disease. Air pollution is an acute trigger of AF, likely contributing to the pollution-associated adverse cardiac outcomes observed in epidemiological studies. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  1. Effects of isopropanol on collagen fibrils in new parchment

    Directory of Open Access Journals (Sweden)

    Gonzalez Lee G

    2012-03-01

    Full Text Available Abstract Background Isopropanol is widely used by conservators to relax the creases and folds of parchment artefacts. At present, little is known of the possible side effects of the chemical on parchments main structural component- collagen. This study uses X-ray Diffraction to investigate the effects of a range of isopropanol concentrations on the dimensions of the nanostructure of the collagen component of new parchment. Results It is found in this study that the packing features of the collagen molecules within the collagen fibril are altered by exposure to isopropanol. The results suggest that this chemical treatment can induce a loss of structural water from the collagen within parchment and thus a rearrangement of intermolecular bonding. This study also finds that the effects of isopropanol treatment are permanent to parchment artefacts and cannot be reversed with rehydration using deionised water. Conclusions This study has shown that isopropanol induces permanent changes to the packing features of collagen within parchment artefacts and has provided scientific evidence that its use to remove creases and folds on parchment artefacts will cause structural change that may contribute to long-term deterioration of parchment artefacts. This work provides valuable information that informs conservation practitioners regarding the use of isopropanol on parchment artefacts.

  2. Atrial fibrillation in the Middle East: unmapped, underdiagnosed, undertreated.

    Science.gov (United States)

    Al-Shamkhani, Warkaa; Ayetey, Harold; Lip, Gregory Y H

    2018-05-01

    Atrial fibrillation (AF) is the commonest persistent cardiac arrhythmia with an estimated incidence rate of between 1.5-2% and an important cause of strokes. Few epidemiological studies and clinical trials on the management of AF have been conducted outside Europe and North America. These gaps in our understanding of AF likely lead to sub-optimal management of patients with AF in the rest of the world. Areas covered: We discuss the epidemiology, treatment and clinical outcomes for AF in the Middle East after systematic review of published work for AF from the Middle East. We also discuss important clinical trials on AF conducted in the West in the same period to help contextualize our findings. Expert commentary: The few available Middle East studies suggest important epidemiological differences between Middle Eastern and Western AF populations. In particular, the Middle Eastern AF population is younger and have more co-morbidities than patients in the West. We find that significant numbers of moderate to high risk patients with AF are either undertreated or untreated placing them at increased risk of complications such as stroke. More studies in the Middle Eastern population are required to aid the development of region-specific clinical guidelines to improve patient care.

  3. State of the Art Review: Atrial Fibrillation in Athletes.

    Science.gov (United States)

    Flannery, M Darragh; Kalman, Jonathan M; Sanders, Prashanthan; La Gerche, André

    2017-09-01

    Exercise has substantial health benefits with pleomorphic vascular, metabolic, psychological and anti-neoplastic actions resulting in improved quality of life and longevity. Despite these many benefits, numerous studies have shown that endurance athletes are more likely to develop atrial fibrillation (AF) than non-athletes. The type, intensity and amount of sport appears to influence the risk of developing AF. Several endurance sport activities have been shown to increase the risk of developing AF but an excess in AF has not been shown in non-endurance sports. Furthermore, lifetime hours of participation appear to increase the risk of developing AF. Intriguingly, women appear relatively protected and an association between endurance sport and AF has not been clearly demonstrated amongst female endurance athletes. The mechanisms by which endurance sport promotes the development of AF are unclear. There are, however, a number of pathophysiological mechanisms which are known to increase the risk of AF in non-athletes which have correlates in athletes. These include structural remodelling of the left atrium, elevated left atrial pressure, inflammation, myocardial fibrosis, vagal tone, sinus bradycardia and genetic predisposition. In this article, we explore how some of these mechanisms may contribute to the development of AF in endurance athletes. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  4. Both hypothyroidism and hyperthyroidism increase atrial fibrillation inducibility in rats.

    Science.gov (United States)

    Zhang, Youhua; Dedkov, Eduard I; Teplitsky, Diana; Weltman, Nathan Y; Pol, Christine J; Rajagopalan, Viswanathan; Lee, Bianca; Gerdes, A Martin

    2013-10-01

    Evidence indicates that cardiac hypothyroidism may contribute to heart failure progression. It is also known that heart failure is associated with an increased risk of atrial fibrillation (AF). Although it is established that hyperthyroidism increases AF incidence, the effect of hypothyroidism on AF is unclear. This study investigated the effects of different thyroid hormone levels, ranging from hypothyroidism to hyperthyroidism on AF inducibility in thyroidectomized rats. Thyroidectomized rats with serum-confirmed hypothyroidism 1 month after surgery were randomized into hypothyroid (N=9), euthyroid (N=9), and hyperthyroid (N=9) groups. Rats received placebo, 3.3-mg l-thyroxine (T4), or 20-mg T4 pellets (60-day release form) for 2 months, respectively. At the end of treatment, hypothyroid, euthyroid, and hyperthyroid status was confirmed. Hypothyroid animals showed cardiac atrophy and reduced cardiac systolic and diastolic functions, whereas hyperthyroid rats exhibited cardiac hypertrophy and increased cardiac function. Hypothyroidism and hyperthyroidism produced opposite electrophysiological changes in heart rates and atrial effective refractory period, but both significantly increased AF susceptibility. AF incidence was 78% in hypothyroid, 67% in hyperthyroid, and the duration of induced AF was also longer, compared with 11% in the euthyroid group (all Phyperthyroidism lead to increased AF vulnerability in a rat thyroidectomy model. Our results stress that normal thyroid hormone levels are required to maintain normal cardiac electrophysiology and to prevent cardiac arrhythmias and AF.

  5. Application of Traditional Chinese Medicine in Treatment of Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Yan Dong

    2017-01-01

    Full Text Available Atrial fibrillation (AF is the most common cardiac arrhythmia, which is related to many cardiac and cerebral vascular diseases, especially stroke. It can therefore increase cardiovascular mortality and all-cause death. The current treatments of AF remain to be western drugs and radiofrequency ablation which are limited by the tolerance of patients, adverse side effects, and high recurrence rate, especially for the elderly. On the contrary, traditional Chinese medicine (TCM with long history of use involves various treatment methods, including Chinese herbal medicines (CHMs or bioactive ingredients, Chinese patent medicines, acupuncture, Qigong, and Tai Chi Chuan. With more and more researches reported, the active roles of TCM in AF management have been discovered. Then it is likely that TCM would be effective preventive means and valuable additional remedy for AF. The potential mechanisms further found by numerous experimental studies showed the distinct characteristics of TCM. Some CHMs or bioactive ingredients are atrial-selective, while others are multichannel and multifunctional. Therefore, in this review we summarized the treatment strategies reported in TCM, with the purpose of providing novel ideas and directions for AF management.

  6. Real-Time Rotational Activity Detection in Atrial Fibrillation

    Science.gov (United States)

    Ríos-Muñoz, Gonzalo R.; Arenal, Ángel; Artés-Rodríguez, Antonio

    2018-01-01

    Rotational activations, or spiral waves, are one of the proposed mechanisms for atrial fibrillation (AF) maintenance. We present a system for assessing the presence of rotational activity from intracardiac electrograms (EGMs). Our system is able to operate in real-time with multi-electrode catheters of different topologies in contact with the atrial wall, and it is based on new local activation time (LAT) estimation and rotational activity detection methods. The EGM LAT estimation method is based on the identification of the highest sustained negative slope of unipolar signals. The method is implemented as a linear filter whose output is interpolated on a regular grid to match any catheter topology. Its operation is illustrated on selected signals and compared to the classical Hilbert-Transform-based phase analysis. After the estimation of the LAT on the regular grid, the detection of rotational activity in the atrium is done by a novel method based on the optical flow of the wavefront dynamics, and a rotation pattern match. The methods have been validated using in silico and real AF signals. PMID:29593566

  7. Detecting atrial fibrillation by deep convolutional neural networks.

    Science.gov (United States)

    Xia, Yong; Wulan, Naren; Wang, Kuanquan; Zhang, Henggui

    2018-02-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia. The incidence of AF increases with age, causing high risks of stroke and increased morbidity and mortality. Efficient and accurate diagnosis of AF based on the ECG is valuable in clinical settings and remains challenging. In this paper, we proposed a novel method with high reliability and accuracy for AF detection via deep learning. The short-term Fourier transform (STFT) and stationary wavelet transform (SWT) were used to analyze ECG segments to obtain two-dimensional (2-D) matrix input suitable for deep convolutional neural networks. Then, two different deep convolutional neural network models corresponding to STFT output and SWT output were developed. Our new method did not require detection of P or R peaks, nor feature designs for classification, in contrast to existing algorithms. Finally, the performances of the two models were evaluated and compared with those of existing algorithms. Our proposed method demonstrated favorable performances on ECG segments as short as 5 s. The deep convolutional neural network using input generated by STFT, presented a sensitivity of 98.34%, specificity of 98.24% and accuracy of 98.29%. For the deep convolutional neural network using input generated by SWT, a sensitivity of 98.79%, specificity of 97.87% and accuracy of 98.63% was achieved. The proposed method using deep convolutional neural networks shows high sensitivity, specificity and accuracy, and, therefore, is a valuable tool for AF detection. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Identification of atrial fibrillation using electrocardiographic RR-interval difference

    Science.gov (United States)

    Eliana, M.; Nuryani, N.

    2017-11-01

    Automated detection of atrial fibrillation (AF) is an interesting topic. It is an account of very dangerous, not only as a trigger of embolic stroke, but it’s also related to some else chronical disease. In this study, we analyse the presence of AF by determining irregularities of RR-interval. We utilize the interval comparison to measure the degree of irregularities of RR-interval in a defined segment. The series of RR-interval is segmented with the length of 10 of them. In this study, we use interval comparison for the method. We were comparing all of the intervals there each other. Then we put the threshold to define the low difference and high difference (δ). A segment is defined as AF or Normal Sinus by the number of high δ, so we put the tolerance (β) of high δ there. We have used this method to test the 23 patients data from MIT-BIH. Using the approach and the clinical data we find accuracy, sensitivity, and specificity of 84.98%, 91.99%, and 77.85% respectively.

  9. Both Hypothyroidism and Hyperthyroidism Increase Atrial Fibrillation Inducibility in Rats

    Science.gov (United States)

    Zhang, Youhua; Dedkov, Eduard I.; Teplitsky, Diana; Weltman, Nathan Y.; Pol, Christine J.; Rajagopalan, Viswanathan; Lee, Bianca; Gerdes, A. Martin

    2014-01-01

    Background Evidence indicates that cardiac hypothyroidism may contribute to heart failure (HF) progression. It is also known that HF is associated with an increased risk of atrial fibrillation (AF). While it is established that hyperthyroidism increases AF incidence, the effect of hypothyroidism on AF is unclear. This study investigated the effects of different thyroid hormone levels, ranging from hypothyroidism to hyperthyroidism on AF inducibility in thyroidectomized rats. Methods and Results Thyroidectomized rats with serum confirmed hypothyroidism 1 month after surgery were randomized into hypothyroid (n=9), euthyroid (n=9) and hyperthyroid (n=9) groups. Rats received placebo, 3.3mg L-thyroxine (T4), or 20 mg T4 pellets (60 day release form) for 2 months, respectively. At the end of treatment, hypothyroid, euthyroid and hyperthyroid status was confirmed. Hypothyroid animals showed cardiac atrophy and reduced cardiac systolic and diastolic function, while hyperthyroid rats exhibited cardiac hypertrophy and increased cardiac function. Hypothyroidism and hyperthyroidism produced opposite electrophysiological changes in heart rates and atrial effective refractory period, but both significantly increased AF susceptibility. AF incidence was 78% in hypothyroid, 67% in hyperthyroid, and the duration of induced AF was also longer, compared with 11% in the euthyroid group (all phyperthyroidism lead to increased AF vulnerability in a rat thyroidectomy model. Our results stress that normal thyroid hormone levels are required to maintain normal cardiac electrophysiology and prevent cardiac arrhythmias and AF. PMID:24036190

  10. Atrioventricular node functional remodeling induced by atrial fibrillation.

    Science.gov (United States)

    Zhang, Youhua; Mazgalev, Todor N

    2012-09-01

    The atrioventricular node (AVN) plays a vital role in determining the ventricular rate during atrial fibrillation (AF). AF results in profound electrophysiological and structural remodeling in the atria as well as the sinus node. However, it is unknown whether AVN undergoes remodeling during AF. To determine whether AVN undergoes functional remodeling during AF. AVN conduction properties were studied in vitro in 9 rabbits with AF and 10 normal controls. A previously validated index of AVN dual-pathway electrophysiology, His-electrogram alternans, was used to monitor fast-pathway or slow-pathway (SP) AVN conduction in these experiments. AVN conduction properties were further studied in vivo in 7 dogs with chronic AF and 8 controls. Compared with the control rabbits, the rabbits with AF had a longer AVN conduction time (83 ± 16 ms vs 68 ± 7 ms; P AVN effective refractory period (141 ± 27 ms vs 100 ± 9 ms; P AVN effective refractory period and a slower ventricular rate during AF compared with the controls. Pronounced AVN functional electrophysiological remodeling occurs after long-term AF, which could lead to a spontaneous slowing of the ventricular rate. Furthermore, the SP dominance during AF underscores the effectiveness of its modification by ablation for ventricular rate control during AF. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  11. Stroke Prevention in Atrial Fibrillation: Focus on Latin America

    Directory of Open Access Journals (Sweden)

    Ayrton R. Massaro

    2016-01-01

    Full Text Available Abstract Atrial fibrillation (AF is the most common sustained cardiac arrhythmia, with an estimated prevalence of 1-2% in North America and Europe. The increased prevalence of AF in Latin America is associated with an ageing general population, along with poor control of key risk factors, including hypertension. As a result, stroke prevalence and associated mortality have increased dramatically in the region. Therefore, the need for effective anticoagulation strategies in Latin America is clear. The aim of this review is to provide a contemporary overview of anticoagulants for stroke prevention. The use of vitamin K antagonists (VKAs, eg, warfarin and aspirin in the prevention of stroke in patients with AF in Latin America remains common, although around one fifth of all AF patients receive no anticoagulation. Warfarin use is complicated by a lack of access to effective monitoring services coupled with an unpredictable pharmacokinetic profile. The overuse of aspirin is associated with significant bleeding risks and reduced efficacy for stroke prevention in this patient group. The non-VKA oral anticoagulants (NOACbs represent a potential means of overcoming many limitations associated with VKA and aspirin use, including a reduction in the need for monitoring and a reduced risk of hemorrhagic events. The ultimate decision of which anticoagulant drug to utilize in AF patients depends on a multitude of factors. More research is needed to appreciate the impact of these factors in the Latin American population and thereby reduce the burden of AF-associated stroke in this region.

  12. LEFT-VENTRICULAR BEAT-TO-BEAT PERFORMANCE IN ATRIAL-FIBRILLATION - CONTRIBUTION OF FRANK-STARLING MECHANISM AFTER SHORT RATHER THAN LONG RR INTERVALS

    NARCIS (Netherlands)

    GOSSELINK, ATM; BLANKSMA, PK; CRIJNS, HJGM; VANGELDER, IC; DEKAM, PJ; HILLEGE, HL; NIEMEIJER, MG; LIE, KI; MEIJLER, FL

    1995-01-01

    Objectives. This study sought to evaluate control mechanisms of the varying left ventricular performance in atrial fibrillation. Background. Atrial fibrillation is characterized by a randomly irregular ventricular response, resulting in continuous variation in left ventricular beat-to-beat

  13. Left ventricular beat-to-beat performance in atrial fibrillation: Contribution of Frank-Starling mechanism after short rather than long intervals

    NARCIS (Netherlands)

    Gosselink, A.T.M.; Blanksma, P.K.; Crijns, H.J.G.M.; Gelder, I.C. van; Kam, P.J. de; Hillege, H.L.; Niemeijer, M.G.; Lie, K.I.; Meijler, F.L.

    1995-01-01

    This study sought to evaluate control mechanisms of the varying left ventricular performance in atrial fibrillation. Atrial fibrillation is characterized by a randomly irregular ventricular response, resulting in continuous variation in left ventricular beat-to-beat mechanical behavior and

  14. Economics-driven software architecture

    CERN Document Server

    Mistrik, Ivan; Kazman, Rick; Zhang, Yuanyuan

    2014-01-01

    Economics-driven Software Architecture presents a guide for engineers and architects who need to understand the economic impact of architecture design decisions: the long term and strategic viability, cost-effectiveness, and sustainability of applications and systems. Economics-driven software development can increase quality, productivity, and profitability, but comprehensive knowledge is needed to understand the architectural challenges involved in dealing with the development of large, architecturally challenging systems in an economic way. This book covers how to apply economic consider

  15. BRAHMMA - accelerator driven subcritical facility

    International Nuclear Information System (INIS)

    Roy, Tushar; Shukla, Shefali; Shukla, M.; Ray, N.K.; Kashyap, Y.S.; Patel, T.; Gadkari, S.C.

    2017-01-01

    Accelerator Driven Subcritical systems are being studied worldwide for their potential in burning minor actinides and reducing long term radiotoxicity of spent nuclear fuels. In order to pursue the physics studies of Accelerator Driven Subcritical systems, a thermal subcritical assembly BRAHMMA (BeOReflectedAndHDPeModeratedMultiplying Assembly) has been developed at Purnima Labs, BARC. The facility consists of two major components: Subcritical core and Accelerator (DT/ DD Purnima Neutron Generator)

  16. Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee [POSTECH, Pohang (Korea, Republic of)

    2008-11-15

    Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an

  17. A carboxylated Zn-phthalocyanine inhibits fibril formation of Alzheimer's amyloid β peptide.

    Science.gov (United States)

    Tabassum, Shatera; Sheikh, Abdullah M; Yano, Shozo; Ikeue, Takafumi; Handa, Makoto; Nagai, Atsushi

    2015-02-01

    Amyloid β (Aβ), a 39-42 amino acid peptide derived from amyloid precursor protein, is deposited as fibrils in Alzheimer's disease brains, and is considered to play a major role in the pathogenesis of the disease. We have investigated the effects of a water-soluble Zn-phthalocyanine, ZnPc(COONa)₈, a macrocyclic compound with near-infrared optical properties, on Aβ fibril formation in vitro. A thioflavin T fluorescence assay showed that ZnPc(COONa)₈ significantly inhibited Aβ fibril formation, increasing the lag time and dose-dependently decreasing the plateau level of fibril formation. Moreover, it destabilized pre-formed Aβ fibrils, resulting in an increase in low-molecular-weight species. After fibril formation in the presence of ZnPc(COONa)₈, immunoprecipitation of Aβ₁₋₄₂ using Aβ-specific antibody followed by near-infrared scanning demonstrated binding of ZnPc(COONa)₈ to Aβ₁₋₄₂. A study using the hydrophobic fluorescent probe 8-anilino-1-naphthalenesulfonic acid showed that ZnPc(COONa)8 decreased the hydrophobicity during Aβ₁₋₄₂ fibril formation. CD spectroscopy showed an increase in the α helix structure and a decrease in the β sheet structure of Aβ₁₋₄₀ in fibril-forming buffer containing ZnPc(COONa)₈. SDS/PAGE and a dot-blot immunoassay showed that ZnPc(COONa)₈ delayed the disappearance of low-molecular-weight species and the appearance of higher-molecular-weight oligomeric species of Aβ₁₋₄₂. A cell viability assay showed that ZnPc(COONa)₈ was not toxic to a neuronal cell line (A1), but instead protected A1 cells against Aβ₁₋₄₂-induced toxicity. Overall, our results indicate that ZnPc(COONa)₈ binds to Aβ and decreases the hydrophobicity, and this change is unfavorable for Aβ oligomerization and fibril formation. © 2014 FEBS.

  18. Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

    International Nuclear Information System (INIS)

    Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee

    2008-01-01

    Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an important role in

  19. Amyloid Fibril Polymorphism: Almost Identical on the Atomic Level, Mesoscopically Very Different.

    Science.gov (United States)

    Seuring, Carolin; Verasdonck, Joeri; Ringler, Philippe; Cadalbert, Riccardo; Stahlberg, Henning; Böckmann, Anja; Meier, Beat H; Riek, Roland

    2017-03-02

    Amyloid polymorphism of twisted and straight β-endorphin fibrils was studied by negative-stain transmission electron microscopy, scanning transmission electron microscopy, and solid-state nuclear magnetic resonance spectroscopy. Whereas fibrils assembled in the presence of salt formed flat, striated ribbons, in the absence of salt they formed mainly twisted filaments. To get insights into their structural differences at the atomic level, 3D solid-state NMR spectra of both fibril types were acquired, allowing the detection of the differences in chemical shifts of 13 C and 15 N atoms in both preparations. The spectral fingerprints and therefore the chemical shifts are very similar for both fibril types. This indicates that the monomer structure and the molecular interfaces are almost the same but that these small differences do propagate to produce flat and twisted morphologies at the mesoscopic scale. This finding is in agreement with both experimental and theoretical considerations on the assembly of polymers (including amyloids) under different salt conditions, which attribute the mesoscopic difference of flat versus twisted fibrils to electrostatic intermolecular repulsions.

  20. Treatment of atrial fibrillation with radiofrequency ablation and simultaneous multipolar mapping of the pulmonary veins

    Directory of Open Access Journals (Sweden)

    Rocha Neto Almino C.

    2001-01-01

    Full Text Available OBJECTIVE: To demonstrate the feasibility and safety of simultaneous catheterization and mapping of the 4 pulmonary veins for ablation of atrial fibrillation. METHODS: Ten patients, 8 with paroxysmal atrial fibrillation and 2 with persistent atrial fibrillation, refractory to at least 2 antiarrhythmic drugs and without structural cardiopathy, were consecutively studied. Through the transseptal insertion of 2 long sheaths, 4 pulmonary veins were simultaneously catheterized with octapolar microcatheters. After identification of arrhythmogenic foci radiofrequency was applied under angiographic or ultrasonographic control. RESULTS: During 17 procedures, 40 pulmonary veins were mapped, 16 of which had local ectopic activity, related or not with the triggering of atrial fibrillation paroxysms. At the end of each procedure, suppression of arrhythmias was obtained in 8 patients, and elimination of pulmonary vein potentials was accomplished in 4. During the clinical follow-up of 9.6±3 months, 7 patients remained in sinus rhythm, 5 of whom were using antiarrhythmic drugs that had previously been ineffective. None of the patients had pulmonary hypertension or evidence of stenosis in the pulmonary veins. CONCLUSION: Selective and simultaneous catheterization of the 4 pulmonary veins with microcatheters for simultaneous recording of their electrical activity is a feasible and safe procedure that may help ablation of atrial fibrillation.