Fast Contraction Research Articles

Modeling Cedrus atlantica potential distribution in North Africa across time: new putative glacial refugia and future range shifts under climate change

In recent years, species distribution models have been used to gain a better understanding of past and future range dynamics of species. Here, we focus on a keystone species of the North African forest ecosystem (Cedrus atlantica) by calculating a consensus model of the species current geographic potential distribution in North Africa, based on a weighted average method aiming to decrease uncertainty. The consensus model is obtained using seven species distribution model algorithms taking into account 24 environmental variables. The model is then applied to several past and future time slices. Past projections refer to the Middle-Holocene and the Last Glacial Maximum, whereas those of future are related to expect conditions around 2050 and 2070. We found that the current potential distribution of Cedrus atlantica is larger than its actual geographical distribution. For some explanatory variables, the analysis revealed their importance for the species current distribution. Among all obtained models, that for the Middle-Holocene showed the maximum expansion of the species potential distribution. The Last Glacial Maximum model provided new putative glacial refugia of Cedrus atlantica, not shown by other mechanistic models and palaeorecord localities. Future projections revealed a significant and fast contraction with shifting in altitude of the species range, showing more fragmented areas and even species disappearance in many North African localities. These findings can help to restore cedar forests and conserve them by ex situ strategies according to the future defined refugia in North Africa. Attention should be paid to the resolution of related output maps, the current biotic interactions, and those that may arise under climate change.

Artificial Smooth Muscle Model Composed of Hierarchically Ordered Microtubule Asters Mediated by DNA Origami Nanostructures.

DNA has been well-known for its applications in programmable self-assembly of materials. Nonetheless, utility of DNA origami, which offers more opportunity to realize complicated operations, has been very limited. Here we report self-assembly of a biomolecular motor system, microtubule-kinesin mediated by DNA origami nanostructures. We demonstrate that a rodlike DNA origami motif facilitates self-assembly of microtubules into asters. A smooth-muscle like molecular contraction system has also been realized using the DNA origami in which self-assembled microtubules exhibited fast and dynamic contraction in the presence of kinesins through an energy dissipative process. This work provides potential nanotechnological applications of DNA and biomolecular motor proteins.

Evolution of the human cold/menthol receptor, TRPM8

Genes showing versatile functions or subjected to fast expansion and contraction during the adaptation of species to specific ecological conditions, like sensory receptors for odors, pheromones and tastes, are characterized by a great plasticity through evolution. One of the most fascinating sensory receptors in the family of TRP channels, the cold and menthol receptor TRPM8, has received significant attention in the literature. Recent studies have reported the existence of TRPM8 channel isoforms encoded by alternative mRNAs transcribed from alternative promoters and processed by alternative splicing. Since the first draft of the human genome was accomplished in 2000, alternative transcription, alternative splicing and alternative translation have appeared as major sources of gene product diversity and are thought to participate in the generation of complexity in higher organisms. In this study, we investigate whether alternative transcription has been a driving force in the evolution of the human forms of the cold receptor TRPM8.We identified 33 TRPM8 alternative mRNAs (24 new sequences) and their associated protein isoforms in human tissues. Using comparative genomics, we described the evolution of the human TRPM8 sequences in eight ancestors since the origin of Amniota, and estimated in which ancestors the new TRPM8 variants originated. In order to validate the estimated origins of this receptor, we performed experimental validations of predicted exons in mouse tissues. Our results suggest a first diversification event of the cold receptor in the Boreoeutheria ancestor, and a subsequent divergence at the origin of Simiiformes.

Reliability and validity of pelvic floor muscle displacement measurements during voluntary contractions.

Understanding the functioning of pelvic floor muscles (PFM) is crucial in female PFM rehabilitation. The aim of this study was to determine the intra-session retest reliability and validity to evaluate the quantity of PFM displacement. This cross-sectional observational study examined the PFM displacement of 17 young healthy nulliparous women in the midsagittal plane. Three maximal voluntary contractions (MVCs) and five fast voluntary contractions (FVCs) were simultaneously examined with an electromagnetic tracking system (ETS) and transabdominal ultrasound (TAUS) and expressed in millimeters (mean, SD). To evaluate reliability and validity, the analysis of variance, intraclass coefficient (2,1), standard error of measurement (SEM), and minimal detectable difference (MDD) were calculated. Maximal voluntary contractions and FVCs in supine position measured by an ETS (TAUS) showed a displacement of MVC: 3.5 ± 1.9mm (7.8 ± 4.5mm), FVC: 3.5 ± 2.4mm (7.6 ± 5.3mm), and during standing of MVC: 5.2 ± 1.6mm (9.4 ± 3.8mm) and FVC: 4.8 ± 2.5mm (9.7 ± 4.1mm). Intraclass correlation for the ETS (TAUS) measurement varied between 0.79 and 0.89 (0.61 and 0.74), SEM 0.52 and 1.03mm (1.54 and 3.2mm), and MDD 1.54 and 3.2mm (6.64 and 7.53mm). The correlation between an ETS and TAUS varied between 0.53 and 0.67. For MVC and FVC, ETS measurements are highly reliable and TAUS measurements are moderately reliable for both contraction types. The correlation between the TAUS and ETS measurements is moderate. An ETS seems to be a reliable and valid measurement tool for evaluating PFM displacement during voluntary contractions. In future studies, the reproducibility and validity of ETS measurements need to be investigated in impact activities.

Formulation and evaluation of wound healing activity of sophorolipid-sericin gel in wistar rats

Sericin is a useful by-product of silk processing and is resistant to oxidation and ultraviolet and can absorb and release moisture easily. Sericin has biological activities such as antibacterial, antioxidant, and tyrosinase inhibition. Sophorolipids are microbial extracellular glycolipids produced by resting cells of Candida bombicola. Sophorolipids show excellent skin compatibility and also have antibacterial property. In this study, we have developed a novel formulation consisting of sericin and sophorolipid with calcium alginate as a binding agent. Since both the ingredients are biocompatible and biodegradable, the formulation was tested for wound healing in Wistar rats. A commercial ointment povidone was used as control. The animal group, treated with sericin and sophorolipid cream, showed fast contraction, rapid closure, and healing when compared with control and commercial ointment. These observations were validated with histopathological studies where more fibroblast proliferation, angiogenesis, and keratinization were observed. This is a green, cost-effective formulation for fast wound healing.

U.S. monetary policy and emerging market credit cycles

Foreign banks’ lending to firms in emerging market economies (EMEs) is large and denominated predominantly in U.S. dollars. This creates a direct connection between U.S. monetary policy and EME credit cycles. We estimate that over a typical U.S. monetary easing cycle, EME borrowers experience a 32-percentage-point greater increase in the volume of loans issued by foreign banks than do borrowers from developed markets, followed by a fast credit contraction of a similar magnitude upon reversal of the cycle. Consistent with a risk-driven credit-supply adjustment, we show that the spillover is stronger for riskier EMEs, and, within countries, for higher-risk firms.

Molecular Dynamics Studies of Myosin Structure with 2-Deoxy-ADP

Myosin uses ATP catalysis to drive muscle contraction by facilitating cross-bridge cycling. During the cross-bridge powerstroke, coordinated release of the byproducts of nucleotide catalysis (Pi, ADP) triggers a series of conformational changes in myosin that alter its interactions with actin and ultimately generate force. In addition to ATP, myosins can utilize other nucleotides, such as the naturally occurring 2-deoxy-ATP (dATP), to catalyze the powerstroke. We have reported that dATP enhances cross-bridge binding and cycling dynamics, resulting in stronger, faster contraction especially in cardiac muscle. In a recent study (Nowakowski 2017, Protein Sci 26:749-62) our simulations of myosin in the pre-powerstroke state showed that dADP induces conformational changes that expose polar residues and enhance its affinity for actin. In a current study using x-ray structural analysis, we found that dATP increases the rate of myosin detachment following tetanic contraction. To understand the molecular basis for the enhanced rate of detachment in the presence of elevated dATP, we performed molecular dynamics simulations of the myosin motor domain modeled in the post-powerstroke conformation in the presence of Mg2+ and either ADP or dADP. We found that dADP was more flexible than ADP, more mobile within the nucleotide binding pocket and had different interactions with myosin relative to ADP. Furthermore, changes in the interactions between dADP and myosin were transmitted to the actin binding surface. Additionally, we observed partial release of the nucleotides from the binding pocket and have delineated the molecular mechanisms by which regulatory loops in myosin control nucleotide release. Our results have revealed molecular mechanisms underlying dATP-enhanced cross-bridge cycling dynamics. More generally they have yielded insights for the development of novel myosin-targeted therapies for cardiomyopathies based the structural advantages produced by dATP in resting and contracting muscle.

Improving Walking Ability in People With Neurologic Conditions: A Theoretical Framework for Biomechanics-Driven Exercise Prescription

The purpose of this paper is to discuss how knowledge of the biomechanics of walking can be used to inform the prescription of resistance exercises for people with mobility limitations. Muscle weakness is a key physical impairment that limits walking in commonly occurring neurologic conditions such as cerebral palsy, traumatic brain injury, and stroke. Few randomized trials to date have shown conclusively that strength training improves walking in people living with these conditions. This appears to be because (1) the most important muscle groups for forward propulsion when walking have not been targeted for strengthening, and (2) strength training protocols have focused on slow and heavy resistance exercises, which do not improve the fast muscle contractions required for walking. We propose a theoretical framework to improve exercise prescription by integrating the biomechanics of walking with the principles of strength training outlined by the American College of Sports Medicine to prescribe exercises that are specific to improving the task of walking. The high angular velocities that occur in the lower limb joints during walking indicate that resistance exercises targeting power generation would be most appropriate. Therefore, we propose the prescription of plyometric and ballistic resistance exercise, applied using the American College of Sports Medicine guidelines for task specificity, once people with neurologic conditions are ambulating, to improve walking outcomes. This new theoretical framework for resistance training ensures that exercise prescription matches how the muscles work during walking.

Pelvic floor muscle activity during fast voluntary contractions in continent and incontinent women.

Stress urinary incontinence (SUI) has also been attributed to a lower speed of contraction of the pelvic floor muscles (PFM). Therefore, PFM assessment and training implement fast voluntary contractions (FVC). The purpose of the study was to explore FVC regarding feasibility, on-/offset and rate of activity determination, as well as differences between continent (CON) and stress urinary incontinent (SUI) women. Fifty women were included and examined by means of PFM EMG during rest, maximum voluntary contractions (MVC), and five FVC. MVC-peak activity was used to normalize EMG-data. On-/offset of muscle activity was determined as mean of rectified rest activity plus 1 standard deviation. Linear regression was calculated for rate of activity from onset to peak, peak to offset, and within 200 ms after both onset and peak. Peak activity and time variables related to onset, peak, and offset were calculated. On-/offsets were evaluable for 234/222 of 250 FVC by a computer-based algorithm, 16/28 on-/offsets had to be determined manually. There was no significant difference between groups (CON/SUI) regarding FVC peak (92.1/99.3 %MVC), time to peak (514.2/525.6 ms), and increase of activity (182.8/182.1 %MVC/s). The SUI group showed a significantly slower activity decrease (-120.7/-74.4 %MVC/s). FVC analyses were shown to be feasible. The significant difference observed between the groups did not refer to activity increase but instead to a prolonged relaxation phase in the SUI group. This prompts to reconsider the interpretation of FVC in PFM testing and training.

Muscle structure governs joint function: linking natural variation in medial gastrocnemius structure with isokinetic plantar flexor function.

ABSTRACTDespite the robust findings linking plantar flexor muscle structure to gross function within athletes, the elderly and patients following Achilles tendon ruptures, the link between natural variation in plantar flexor structure and function in healthy adults is unclear. In this study, we determined the relationship between medial gastrocnemius structure and peak torque and total work about the ankle during maximal effort contractions. We measured resting fascicle length and pennation angle using ultrasound in healthy adults (N=12). Subjects performed maximal effort isometric and isokinetic contractions on a dynamometer. We found that longer fascicles were positively correlated with higher peak torque and total work (R2>0.41, P<0.013) across all isokinetic velocities, ranging from slow (30°/s) to fast (210°/s) contractions. Higher pennation angles were negatively correlated with peak torque and total work (R2>0.296, P<0.067). These correlations were not significant in isometric conditions. We further explored this relationship using a simple computational model to simulate isokinetic contractions. These simulations confirmed that longer fascicle lengths generate more joint torque and work throughout a greater range of motion. This study provides evidence that ankle function is strongly influenced by muscle structure in healthy adults.

3D ultrastructural organisation of calcium release units in the avian sarcoplasmic reticulum.

Excitation-contraction coupling in vertebrate hearts is underpinned by calcium (Ca2+) release from Ca2+ release units (CRUs). CRUs are formed by clusters of channels called ryanodine receptors on the sarcoplasmic reticulum (SR) within the cardiomyocyte. Distances between CRUs influence the diffusion of Ca2+, thus influencing the rate and strength of excitation-contraction coupling. Avian myocytes lack T-tubules, so Ca2+ from surface CRUs (peripheral couplings, PCs) must diffuse to internal CRU sites of the corbular SR (cSR) during centripetal propagation. Despite this, avian hearts achieve higher contractile rates and develop greater contractile strength than many mammalian hearts, which have T-tubules to provide simultaneous activation of the Ca2+ signal through the myocyte. We used 3D electron tomography to test the hypothesis that the intracellular distribution of CRUs in the avian heart permits faster and stronger contractions despite the absence of T-tubules. Nearest edge-edge distances between PCs and cSR, and geometric information including surface area and volume of individual cSR, were obtained for each cardiac chamber of the white leghorn chicken. Computational modelling was then used to establish a relationship between CRU distance and cell activation time in the avian heart. Our data suggest that cSR clustered close together along the Z-line is vital for rapid propagation of the Ca2+ signal from the cell periphery to the cell centre, which would aid in the strong and fast contractions of the avian heart.

Motor Unit Identification From High-Density Surface Electromyograms in Repeated Dynamic Muscle Contractions.

We describe the method for identification of motor unit (MU) firings from high-density surface electromyograms (hdEMG), recorded during repeated dynamic muscle contractions. A new convolutive data model for dynamic hdEMG is presented, along with the pulse-to-noise ratio (PNR) metric for assessment of MU identification accuracy and analysis of the impact of MU action potential (MUAP) changes in dynamic muscle contractions on MU identification. We tested the presented methodology on signals from biceps brachii, vastus lateralis, and rectus famoris muscles, all during different speeds of dynamic contractions. In synthetic signals with excitation levels of 10%, 30% and 50%, and MUAPs experimentally recorded from biceps brachii muscle, the presented method identified 15 ± 1, 18 ± 1, and 20 ± 1 MUs per contraction, respectively, all with average sensitivity and precision >90% and PNR >30dB. In experimental signals acquired during low force contractions of vastus lateralis and rectus femoris muscle, the method identified 9.4±1.9 and 7.8±1.4 MUs with PNR values of 35.4±3.6 and 34.1±2.7 dB. In comparison with the previously introduced Convolution Kernel Compensation method, the capability of the new method to follow dynamic MUAP changes is confirmed, also in relatively fast muscle contractions.

Peripheral apelin mediates stress-induced alterations in gastrointestinal motor functions depending on the nutritional status.

Exposure to stress induces gastrointestinal (GI) dysmotility. In rodents, acute restraint stress (ARS) inhibits gastric emptying (GE) and intestinal transit (IT) via central and peripheral corticotropin-releasing factor (CRF)-mediated pathways. Peripherally administered apelin-13 was shown to inhibit GI motor functions; moreover, stress-induced upregulation of gastric apelin content was demonstrated in rats suggesting that peripheral apelin may mediate stress-induced alterations in GI motility. We investigated the role of endogenous peripheral apelin in stress-induced GI dysfunction. GE, IT and gastro-duodenal fasting motility were measured in non-stressed (NS), CRF-injected and ARS-loaded rats. CRF and apelin receptor antagonists astressin or F13A was administered before ARS or peripheral CRF injection. Apelin and APJ receptor expressions were determined using immunohistochemistry and quantified by qRT-PCR. Double immunofluorescence was performed for enteric neuronal apelin. GE and IT were delayed by CRF and ARS. ARS-induced changes were attenuated by F13A, whereas astressin was ineffective. CRF-induced alterations in GE and IT were restored completely by astressin, while they were diminished by F13A. Antral phase III-like contractions were disturbed following ARS which were preserved by preadministration of astressin, but not F13A. CRF impaired gastric and duodenal fasting contractions, while these changes were not altered by F13A. ARS increased apelin expression in stomach and duodenum. Apelin immunoreactivity was detected in mucosa, smooth muscles and myenteric plexi, whereas dense APJ receptor expression was observed within tunica muscularis. APJ receptor was downregulated in rats fasted overnight. These results suggest that enteric apelin acts as an inhibitor stress mediator in the postprandial state.

Degraded Synergistic Recruitment of sEMG Oscillations for Cerebral Palsy Infants Crawling.

Background: Synergistic recruitment of muscular activities is a generally accepted mechanism for motor function control, and motor dysfunction, such as cerebral palsy (CP), destroyed the synergistic electromyography activities of muscle group for limb movement. However, very little is known how motor dysfunction of CP affects the organization of the myoelectric frequency components due to the abnormal motor unit recruiting patterns.Objectives: Exploring whether the myoelectric activity can be represented with synergistic recruitment of surface electromyography (sEMG) frequency components; evaluating the effect of CP motor dysfunction on the synergistic recruitment of sEMG oscillations.Methods: Twelve CP infants and 17 typically developed (TD) infants are recruited for self-paced crawling on hands and knees. sEMG signals have been recorded from bilateral biceps brachii (BB) and triceps brachii (TB) muscles. Multi-scale oscillations are extracted via multivariate empirical mode decomposition (MEMD), and non-negative matrix factorization (NMF) method is employed to obtain synergistic pattern of these sEMG oscillations. The coefficient curve of sEMG oscillation synergies are adopted to quantify the time-varying recruitment of BB and TB myoelectric activity during infants crawling.Results: Three patterns of sEMG oscillation synergies with specific frequency ranges are extracted in BB and TB of CP or TD infants. The contribution of low-frequency oscillation synergy of BB in CP group is significantly less than that in TD group (p < 0.05) during forward swing phase for slow contraction; however, this low-frequency oscillation synergy keep higher level during the backward swing phase crawling. For the myoelectric activities of TB, there is not enough high-frequency oscillation recruitment of sEMG for the fast contraction in propulsive phase of CP infants crawling.Conclusion: Our results reveal that, the myoelectric activities of a muscle can be manifested as sEMG oscillation synergies, and motor dysfunction of CP degrade the synergistic recruitment of sEMG oscillations due to the impaired CNS regulation and destroyed MU/muscle fiber. Our preliminary work suggests that time-varying coefficient curve of sEMG oscillation synergies is a potential index to evaluate the abnormal recruitment of electromyography activities affected by CP disorders.

Rat atrial engineered heart tissue: a new in vitro model to study atrial biology.

Engineered heart tissue (EHT) from rat cells is a useful tool to study ventricular biology and cardiac drug safety. Since atrial and ventricular cells differ significantly, EHT and other 3D cell culture formats generated from ventricular cells have been of limited value to study atrial biology. To date, reliable in vitro models that reflect atrial physiology are lacking. Therefore, we established a novel EHT model using rat atrial cells (atrial EHT, aEHT) to assess atrial physiology, contractility and drug response. The tissue constructs were characterized with regard to gene expression, histology, electrophysiology, and the response to atrial-specific drugs. We observed typical functional properties of atrial tissue in our model such as more regular spontaneous beating with lower force, shorter action potential duration, and faster contraction and relaxation compared to ventricular EHT (vEHT). The expression of atrial-specific genes and proteins was high, whereas ventricle-specific transcripts were virtually absent. The atrial-selective drug carbachol had a strong negative inotropic and chronotropic effect on aEHT only. Taken together, the results demonstrate the feasibility of aEHT as a novel atrial 3D model and as a benchmark for tissue engineering with human induced pluripotent stem cell-derived atrial-like cardiomyocytes. Atrial EHT faithfully recapitulates atrial physiology and shall be useful to study atrial molecular physiology in health and disease as well as drug response.

Effect of Shear Rate on the Orientation and Relaxation of a Vanillic Acid Based Liquid Crystalline Polymer

In this study, we report on the visco-elastic response during start-up and cessation of shear of a novel bio-based liquid crystal polymer. The ensuing morphological changes are analyzed at different length scales by in-situ polarized optical microscopy and wide-angle X-ray diffraction. Upon inception of shear, the polydomain texture is initially stretched, at larger strain break up processes become increasingly important, and eventually a steady state texture is obtained. The shear stress response showed good coherence between optical and rheo-X-ray data. The evolution of the orientation parameter coincides with the evolution of the texture: the order parameter increases as the texture stretches, drops slightly in the break up regime, and reaches a constant value in the plateau regime. The relaxation of the shear stress and the polydomain texture showed two distinct processes with different timescales: The first is fast contraction of the stretched domain texture; the second is the slow coalescence of the polydomain texture. The timescale of the orientation parameter’s relaxation matched with that of the slow coalescence process. All processes were found to scale with shear rate in the tested regime. These observations can have far reaching implications for the processing of liquid crystal polymers as they indicate that increased shear rates during processing can correspond to an increased relaxation rate of the orientation parameter and, therefore, a decrease in anisotropy and material properties after cooling.

Fair free-form surfaces that are almost everywhere parametrically C 2.

Compared to G k continuity, C k continuity simplifies the construction of functions on surfaces and their refinement, e.g. to solve differential equations on the surface. The new class of almost everywhere parametrically C 2 free-form surfaces provide such a parameterization. For example, a new bi-6 construction combines a fast-contracting C 2 guided subdivision surface with a tiny multi-sided G 1 cap. The cap is chosen to be smaller than any refinement anticipated for geometric modeling or computing on surfaces. Fast contraction means that one subdivision step shrinks the remaining hole more than three steps of Catmull-Clark subdivision. This yields smooth surfaces consisting of a finite number of pieces that are suitable for engineering practice. Both the subdivision construction and the cap are guided by a reference surface. This guide conveys the basic shape, but has a different structure and lower smoothness.

Structural Determinants of Muscle Gearing During Dynamic Contractions.

In skeletal muscle, interactions between contractile and connective tissue elements at multiple scales result in emergent properties that determine mechanical performance. One of these phenomena is architectural gearing, which is quantified as the ratio of muscle velocity to muscle fiber velocity. Many pennate muscles operate with a gear ratio greater than one because muscles shorten through a combination of muscle fiber shortening and fiber rotation. Within a muscle, gearing is variable across contractions. During low force contractions, muscles operate at high gear while muscles operate at low gear during high force contractions. This variable gearing has a significant impact on muscle performance as muscle architectural changes favor muscle speed during fast contractions and muscle force during slow, high force contractions. We hypothesize that gearing in any given contraction is determined by the dynamic interaction of fiber-generated forces, fluid force transmission, and the elastic behavior of intramuscular connective tissues. Because muscle is isovolumetric, muscle fibers must bulge radially when they shorten. Radial bulging and fiber-generated forces off-axis from the muscle line of action exert forces that load connective tissues that ensheath fibers, fascicles, and the whole muscle. The way in which fluid pressures and fiber forces interact to load connective tissues in three-dimensions remains poorly understood because of the complex and multiscale nature of these interactions. Here we review evidence for variable gearing in pennate muscles, present a conceptual model that describes the fundamental interactions that determine gearing, and discuss where gaps remain in our understanding of the determinants and consequences of muscle shape change and variable gearing.

Training induced changes in quadriceps activation during maximal eccentric contractions

Despite full voluntary effort, neuromuscular activation of the quadriceps group of muscles appears inhibited during eccentric contractions. A nerve stimulation protocol during dynamic contractions of the quadriceps was developed that employed triplets of supramaximal pulses to assess suppressed eccentric activation. Subsequently the effects of a short training intervention, performed on a dynamometer, on eccentric strength output and neural inhibition were examined. Torque-angular velocity (T-ω) and experimental voluntary neural drive-angular velocity (%VA-ω; %VA, obtained via the interpolated twitch technique) datasets, were obtained from pre- and post-training testing sessions. Non-linear regression fits of a seven parameter torque function and of a 3rd degree polynomial were performed on the pre- and post-training T-ω and %VA-ω datasets respectively. T-test showed a significant (p < 0.05) increase in the overall torque output post-training for the group, with three out of the six subjects demonstrating a significant (p < 0.05) increase in the torque output across the range of angular velocities as shown by the extra-sum-of-squares F-test. A significant increase (p < 0.05) in the %VA post-training was also observed as well as a reduction in the plateauing of the torque output during fast eccentric contractions.

Inflammatory and Imaging-based Predictors of Atrial Fibrillation Recurrence after Pulmonary Vein Isolation Using Electroanatomical Mapping – the INFLAMAP Study

Abstract Atrial fibrillation (AF) is the most frequent form of supraventricular arrhythmia in medical practice. It is characterized by chaotic electrical activity in the atria, which often leads to irregular and fast ventricular contractions. Pulmonary veins (PV) play an essential part in the genesis of AF. There are a series of risk factors that trigger the development and recurrence of AF after PV isolation. Despite advanced medical technology, the success rate of AF ablation is not satisfactory. The purpose of this study is to assess the preprocedural imaging and serum biomarkers linked to an increased recurrence of AF after PV isolation. The primary endpoint is represented by AF recurrence after PV isolation. In addition, the rate of cardiovascular death and the rate of major adverse cardiovascular events will be assessed in relation to the enlargement of the left atrium and the volume of epicardial adipose tissue surrounding the heart.