scholarly journals A Comparison of Regional Classification Strategies Implemented for the Population Based Approach to Modelling Atrial Fibrillation

Mathematics ◽  
2021 ◽  
Vol 9 (14) ◽  
pp. 1686
Author(s):  
Jordan Elliott ◽  
Maria Kristina Belen ◽  
Luca Mainardi ◽  
Josè Felix Rodriguez Matas
Keyword(s):  
Experimental Data ◽  
Atrial Fibrillation ◽  
Action Potentials ◽  
Population Based ◽  
Channel Conductance ◽  
Cellular Models ◽  
Linear Relationships ◽  
Non Linear ◽  
Conductance Changes ◽  
In Silico Models

(1) Background: in silico models are increasingly relied upon to study the mechanisms of atrial fibrillation. Due to the complexity associated with atrial models, cellular variability is often ignored. Recent studies have shown that cellular variability may have a larger impact on electrophysiological behaviour than previously expected. This paper compares two methods for AF remodelling using regional populations. (2) Methods: using 200,000 action potentials, experimental data was used to calibrate healthy atrial regional populations with two cellular models. AF remodelling was applied by directly adjusting maximum channel conductances. AF remodelling was also applied through adjusting biomarkers. The methods were compared upon replication of experimental data. (3) Results: compared to the percentage method, the biomarker approach resulted in smaller changes. RMP, APD20, APD50, and APD90 were changed in the percentage method by up to 11%, 500%, 50%, and 60%, respectively. In the biomarker approach, RMP, APD20, APD50, and APD90 were changed by up to 4.5%, 132%, 50%, and 35%, respectively. (4) Conclusion: applying AF remodelling through biomarker-based clustering resulted in channel conductance changes that were consistent with experimental data, while maintaining the highly non-linear relationships between channel conductances and biomarkers. Directly changing conductances in the healthy regional populations impacted the non-linear relationships and resulted in non-physiological APD20 and APD50 values.

scholarly journals Biomarkers of iron metabolism are independently associated with impaired glucose metabolism and type 2 diabetes: the KORA F4 study

2015 ◽  
Vol 173 (5) ◽  
pp. 643-653 ◽  
Author(s):  
Cornelia Huth ◽  
Simon Beuerle ◽  
Astrid Zierer ◽  
Margit Heier ◽  
Christian Herder ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Glucose Metabolism ◽  
Iron Metabolism ◽  
Transferrin Saturation ◽  
Population Based ◽  
Impaired Glucose Metabolism ◽  
Linear Relationships ◽  
Non Linear ◽  
Design And Methods

ObjectiveIron has been suggested to play a role in the etiology of type 2 diabetes mellitus (T2DM). Except for ferritin, evidence is sparse for other markers of iron metabolism that are regulated differently and might act through independent pathways. We therefore investigated the associations of serum ferritin, transferrin, soluble transferrin receptor (sTfR), transferrin saturation (TSAT), sTfR-to-log10ferritin (sTfR-F) index, and iron with impaired glucose metabolism (IGM/‘prediabetes’), T2DM, and four continuous glucose and insulin traits.Design and methodsData from 2893 participants of the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4 study (Germany) was investigated through regression analysis. The results were adjusted for socio-demographic, life-style, and obesity measures as well as metabolic, inflammatory, and other iron biomarkers following a step-wise approach. Non-linearity was tested by adding a non-linear spline component to the model.ResultsFerritin and transferrin were positively associated with IGM (fourth vs first sex-specific quartile: ferritin odds ratio (OR)=2.08 (95% CI 1.43–3.04) and transferrin OR=1.89 (95% CI 1.32–2.70)), T2DM (ferritin OR=1.98 (95% CI 1.22–3.22) and transferrin OR=2.42 (95% CI 1.54–3.81)), and fasting as well as 2-h glucose. TSAT (OR=0.55 (95% CI 0.34–0.88)) and iron (OR=0.61 (95% CI 0.38–0.97)) were inversely associated with T2DM, sTfR-F-index was inversely associated with IGM (OR=0.67 (95% CI 0.48–0.95)). There was no strong evidence for non-linear relationships.ConclusionsThe observed associations of several markers of iron metabolism with hyperglycemia and insulin resistance suggest that iron stores as well as iron-related metabolic pathways contribute to the pathogenesis of IGM and T2DM. Moreover, TSAT levels are decreased in T2DM patients.

scholarly journals Influence of the Porosity of Polymer Foams on the Performances of Capacitive Flexible Pressure Sensors

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 1968 ◽  
Author(s):  
Sylvie Bilent ◽  
Thi Hong Nhung Dinh ◽  
Emile Martincic ◽  
Pierre-Yves Joubert
Keyword(s):  
Experimental Data ◽  
Linear Model ◽  
Dielectric Material ◽  
Pressure Sensors ◽  
Volume Ratio ◽  
Measurement Range ◽  
Polymer Foams ◽  
First Order ◽  
Non Linear ◽  
Flexible Pressure Sensors

This paper reports on the study of microporous polydimethylsiloxane (PDMS) foams as a highly deformable dielectric material used in the composition of flexible capacitive pressure sensors dedicated to wearable use. A fabrication process allowing the porosity of the foams to be adjusted was proposed and the fabricated foams were characterized. Then, elementary capacitive pressure sensors (15 × 15 mm2 square shaped electrodes) were elaborated with fabricated foams (5 mm or 10 mm thick) and were electromechanically characterized. Since the sensor responses under load are strongly non-linear, a behavioral non-linear model (first order exponential) was proposed, adjusted to the experimental data, and used to objectively estimate the sensor performances in terms of sensitivity and measurement range. The main conclusions of this study are that the porosity of the PDMS foams can be adjusted through the sugar:PDMS volume ratio and the size of sugar crystals used to fabricate the foams. Additionally, the porosity of the foams significantly modified the sensor performances. Indeed, compared to bulk PDMS sensors of the same size, the sensitivity of porous PDMS sensors could be multiplied by a factor up to 100 (the sensitivity is 0.14 %.kPa−1 for a bulk PDMS sensor and up to 13.7 %.kPa−1 for a porous PDMS sensor of the same dimensions), while the measurement range was reduced from a factor of 2 to 3 (from 594 kPa for a bulk PDMS sensor down to between 255 and 177 kPa for a PDMS foam sensor of the same dimensions, according to the porosity). This study opens the way to the design and fabrication of wearable flexible pressure sensors with adjustable performances through the control of the porosity of the fabricated PDMS foams.

scholarly journals Exercise and the Risk of Dementia in Patients with Newly Diagnosed Atrial Fibrillation: A Nationwide Population-Based Study

2021 ◽  
Vol 10 (14) ◽  
pp. 3126
Author(s):  
Jaehyun Lim ◽  
So-Ryoung Lee ◽  
Eue-Keun Choi ◽  
Kyung-Do Han ◽  
Jin-Hyung Jung ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Risk Reduction ◽  
Lower Risk ◽  
Population Based ◽  
Newly Diagnosed ◽  
Incident Dementia ◽  
Before And After ◽  
Korean National Health Insurance ◽  
New Diagnosis ◽  
New Onset

Background: It is unclear whether exercise would reduce dementia in patients with a new diagnosis of atrial fibrillation (AF). Therefore, we aimed to evaluate the association between the change in physical activity (PA) before and after new-onset AF and the risk of incident dementia. Methods: Using the Korean National Health Insurance Service database, we enrolled a total of 126,555 patients with newly diagnosed AF between 2010 and 2016, who underwent health examinations within two years before and after their diagnosis of AF. The patients were divided into four groups: persistent non-exercisers, exercise starters, exercise quitters, and exercise maintainers. Results: Based on a total of 396,503 person-years of follow-up, 5943 patients were diagnosed with dementia. Compared to persistent non-exercisers, exercise starters (adjusted hazard ratio (aHR) 0.87; 95% confidence interval (CI) 0.81–0.94), and exercise maintainers (aHR 0.66; 95% CI 0.61–0.72) showed a lower risk of incident dementia; however, the risk was similar in exercise quitters (aHR 0.98; 95% CI 0.92–1.05) (p-trend < 0.001). There was a J-shaped relationship between the dose of exercise and the risk of dementia, with the risk reduction maximized at 5–6 times per week of moderate-to-vigorous PA among exercise starters. Conclusion: Patients who initiated or continued regular exercise after diagnosis of AF were associated with a lower risk of dementia than persistent non-exercisers, with no risk reduction associated with exercise cessation. Our findings may provide evidence for the benefit of exercise prescription to patients with new-onset AF to prevent incident dementia regardless of their current exercise status.

ATRIAL FIBRILLATION, COGNITIVE DECLINE, AND DEMENTIA AMONG OLDER PEOPLE: A LONGITUDINAL POPULATION-BASED STUDY

2017 ◽  
Vol 13 (7) ◽  
pp. P238
Author(s):  
Mozhu Ding ◽  
Laura Fratiglioni ◽  
Kristina Johnell ◽  
Alessandra Marengoni ◽  
Petter Ljungman ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Older People ◽  
Cognitive Decline ◽  
Population Based ◽  
Population Based Study

458Real world persistence with direct oral anticoagulants in anticoagulation naive patients with atrial fibrillation

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
G Denas ◽  
G Costa ◽  
E Ferroni ◽  
N Gennaro ◽  
U Fedeli ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Atrial Fibrillation ◽  
Cox Regression ◽  
Anatomical Therapeutic Chemical ◽  
Oral Anticoagulants ◽  
Direct Oral Anticoagulants ◽  
Anticoagulation Therapy ◽  
Female Gender ◽  
Population Based ◽  
Real World Data

Abstract Introduction Anticoagulation therapy is central for the management of stroke in patients with non-valvular atrial fibrillation (NVAF). Persistence with oral anticoagulation is essential to prevent thromboembolic complications. Purpose To assess persistence levels of DOACs and look for possible predictors of treatment discontinuity in NVAF patients. Methods We performed a population-based retrospective cohort study in the Veneto Region (north-eastern Italy, about 5 million inhabitants) using the regional health system databases. Naïve patients initiating direct oral anticoagulants (DOACs) for stroke prevention in NVAF from July 2013 to September 2017 were included in the study. Patients were identified using Anatomical Therapeutic Chemical (ATC) codes, excluding other indications for anticoagulation therapy using ICD-9CM codes. Treatment persistence was defined as the time from initiation to discontinuation of the therapy. Baseline characteristics and comorbidities associated to the persistence of therapy with DOACs were explored by means of Kaplan-Meier curves and assessed through Cox regression. Results Overall, 17920 patients initiated anticoagulation with DOACs in the study period. Most patients were older than 74 years old, while gender was almost equally represented. Comorbidities included hypertension (72%), diabetes mellitus (17%), congestive heart failure (9%), previous stroke/TIA (20%), and prior myocardial infarction (2%). After one year, the persistence to anticoagulation treatment was 82.7%, while the persistence to DOAC treatment was 72.9% with about 10% of the discontinuations being due to switch to VKAs. On multivariate analysis, factors negatively affecting persistence were female gender, younger age (<65 years), renal disease and history of bleeding. Conversely, persistence was better in patients with hypertension, previous cerebral ischemic events, and previous acute myocardial infarction. Persistence to DOAC therapy Conclusion This real-world data show that within 12 months, one out of four anticoagulation-naïve patients stop DOACs, while one out of five patients stop anticoagulation. Efforts should be made to correct modifiable predictors and intensify patient education.

Linear and non-linear relationships between soil sorption and hydrophobicity

2012 ◽  
Vol 23 (1-2) ◽  
pp. 111-123 ◽  
Author(s):  
Y. Wen ◽  
L.M. Su ◽  
W.C. Qin ◽  
J. He ◽  
L. Fu ◽  
...  
Keyword(s):  
Soil Sorption ◽  
Linear Relationships ◽  
Non Linear
Sign in / Sign up

Export Citation Format

Share Document