Autotomy and Regeneration of Appendages in Crustaceans:A Review

Autotomy of appendages is a self-protection mechanism in crustaceans,which is defined as the reflexive loss of a limb in response to predation,competition,or other environmental factors.Single-limb injuries were the most common among the species surveyed in the present study,and the chelicerae were the most frequently lost appendages.After autotomy,hormones and signaling pathways are altered.Loss of limbs can affect foraging efficiency,although cheliped loss may be compensated by shifting to alternative prey or using both motor and oral appendages.In heterogeneous species,the loss of the major chelae may affect the selectivity of feeding.Autotomy can affect crustacean growth by reducing size increases at molting and altering the timing of ecdysis.In commercial production,removing chelicerae is an effective strategy to reduce cannibalism,and production of soft-shell crabs can be increased via autotomy.After autotomy,a new limb will regrow through regeneration and molting.This process involves the regulation of hormones,regrowth of nerves,and a number of signaling pathways that include the Wnt/β-catenin signaling pathway and transforming growth factorβsignaling pathway.Crustaceans are somewhat different from vertebrates in terms of regeneration.This review provides theoretical guidance about autotomy and regeneration applied in artificial aquaculture,and we offer several suggestions for future research on autotomy and regeneration in crustaceans.

Left atrial appendage occluder detachment treated with transthoracic ultrasound combined with digital subtraction angiography guided catcher:A case report

BACKGROUND There are very few cases of cardiac occluder detachment,and it is rare to completely remove the occluder using interventional methods without undergoing thoracotomy surgery after detachment.This case innovatively used ultrasound guidance combined with digital subtraction angiography(DSA)to completely remove the occluder,accumulating some experience.CASE SUMMARY The patient underwent left atrial appendage occlusion surgery in our hospital due to atrial fibrillation.After the surgery,the occluder fell off and became free in the left ventricle,which is very dangerous.We innovatively used ultrasound guidance,combined with DSA,and interventional surgery to successfully capture the free occluder using a catcher,completely remove it,and then re implant a new left atrial appendage occluder.After the surgery,the patient recovered very well.CONCLUSION The size selection of the occluder is slightly conservative,and the shape of the left atrial appendage opening is irregular.

Relationship of inflammatory indices with left atrial appendage thrombus or spontaneous echo contrast in patients with atrial fibrillation

BACKGROUND Inflammatory indices derived from complete blood tests have been reported to be associated with poor outcomes in patients with atrial fibrillation(AF).The data about the relationship between inflammatory indices and left atrial appendage thrombus(LAAT)or dense spontaneous echo contrast(SEC)are limited.AIM To explore the value of inflammatory indices for predicting the presence of LAAT or dense SEC in nonvalvular AF patients.METHODS A total of 406 patients with nonvalvular AF who underwent transesophageal echocardiography were included and divided into two groups based on the presence(study group)or absence(control group)of LAAT or dense SEC.Inflammatory indices,including the neutrophil-to-lymphocyte ratio(NLR),platelet–tolymphocyte ratio(PLR),and lymphocyte-to-monocyte ratio(LMR),were calculated from complete blood analysis.The associations of inflammatory indices RESULTS LAAT and dense SEC were detected in 11(2.7%)and 42(10.3%)patients,respectively.The PLR only showed an association with LAAT/dense SEC in the univariate model.Elevated NLR(odds ratio[OR]=1.48,95%confidence interval[CI]:1.11-1.98,P=0.007)and reduced LMR(OR=0.59,95%CI:0.41-0.83,P=0.003)were found to be independent risk factors for the presence of LAAT/dense SEC.The areas under the NLR and LMR curves for predicting LAAT/dense SEC were 0.73(95%CI:0.66-0.80,P<0.001)and 0.73(95%CI:0.65-0.81,P<0.001),respectively,while the cutoff values were 2.8(sensitivity:69.8%;specificity:64.0%)and 2.4(sensitivity:71.7%;specificity:60.6%),respectively.CONCLUSION Increased NLR and decreased LMR may predict LAAT/dense SEC in patients with nonvalvular AF.

Effects of Crosswise Appendage Plate Flexibility on the Drag Reduction Characteristics of Cylinder

In engineering applications (Like an ocean riser), fluid flow around bluff bodies generates substantial resistance, which can jeopardize structural integrity, lifespan, and escalate resource consumption. Therefore, employing drag reduction measures becomes particularly crucial. This paper employs the immersed boundary method to investigate the impact of transversely oriented appendage plate flexibility on the drag of cylinders under different Reynolds numbers and distances. The results indicate that flexible appendage plate exerts drag reduction effects on the downstream cylinder, with this effect gradually diminishing as Reynolds numbers increase. At identical Reynolds numbers, the drag reduction effect initially increases and then decreases with distance, with the optimal drag reduction distance observed at D = 2.5. Compared to cylinders without appendage plate, the maximum drag reduction achieved is 30.551%. Addressing the drag reduction issue in cylinders holds significant importance for ensuring engineering structural integrity, enhancing engineering efficiency, and developing novel underwater towing systems.

Progress in the study and treatment of peri-device leak after left atrial appendage closure

For patients with atrial fibrillation with an increased risk of stroke and contraindications to long-term anticoagulation,percutaneous left atrial appendage closure(LAAC)has become an important alternative to long-term oral anticoagulation.Incomplete closure of the LAAC during the procedure leads to faster blood flow in the interstitial space around the device,resulting in peri-device leak(PDL),which is not uncommon.Studies are still inconclusive in determining the incidence,long-term safety,and management of PDL.Therefore,this article reviewed the progress made in the research and treatment of PDL after LAAC.

Surgical left atrial appendage occlusion during cardiac surgery： A systematic review and meta-analysis

AIM To evaluate the safety and efficacy of surgical left atrial appendage occlusion(s-LAAO) during concomitant cardiac surgery.METHODS We performed a comprehensive literature search through May 31 st 2018 for all eligible studies comparing s-LAAO vs no occlusion in patients undergoing cardiac surgery. Clinical outcomes during follow-up included: embolic events, stroke, all-cause mortality, atrial fibrillation(AF), reoperation for bleeding and postoperative complications. We further stratified the analysis based on propensity matched studies and AF predominance.RESULTS Twelve studies(n = 40107) met the inclusion criteria.s-LAAO was associated with lower risk of embolic events(OR: 0.63, 95%CI: 0.53-0.76; P < 0.001) and stroke(OR: 0.68, 95%CI: 0.57-0.82; P < 0.0001).Stratified analysis demonstrated this association was more prominent in the AF predominant strata. There was no significant difference in the incidence risk of allcause mortality, AF, and reoperation for bleeding and postoperative complications.CONCLUSION Concomitant s-LAAO during cardiac surgery was associated with lower risk of follow-up thromboembolic events and stroke, especially in those with AF without significant increase in adverse events. Further randomized trials to evaluate long-term benefits of s-LAAO are warranted.

Attitude maneuver of liquid-filled spacecraft with a flexible appendage by momentum wheel

Attitude maneuver of liquid-filled spacecraft with an appendage as a cantilever beam by momentum wheel is studied. The dynamic equations are derived by conserva- tion of angular momentum and force equilibrium principle. A feedback control strategy of the momentum wheel is ap- plied for the attitude maneuver. The residual nutation of the spacecraft in maneuver process changes with some chosen parameters, such as steady state time, locations of the liq- uid container and the appendage, and appendage parame- ters. The results indicate that locations in the second and fourth quadrants of the body-fixed coordinate system and the second quadrant of the wall of the main body are better choices for.placing the liquid containers and the appendage than other locations if they can be placed randomly. Higher density and thicker cross section are better for lowering the residual nutation if they can be changed. Light appendage can be modeled as a rigid body, which results in a larger residual nutation than a flexible model though. The resid- ual nutation decreases with increasing absolute value of the initial sloshing angular height.

Left atrial appendage occluder implantation for stroke prevention in elderly patients with atrial fibrillation： acute and long-term results

Atrial fibrillation （AF） is the most common cardiac ar-rhythmia in clinical practice with an increasing incidenceand prevalence. With ageing, the risk of thromboembolicand hemorrhagic events increases dramatically. As it hasbeen reported previously, 3-year survival rate among pa-tients with AF over 75 years of age after stroke is less than50%, and almost 90% of those patients will remain dis-abled.

Percutaneous devices for left atrial appendage occlusion: A contemporary review

Patient with atrial fibrillation(AF) are at risk of developing stroke with the left atrial appendage(LAA) being the most common site for thrombus formation. If left untreated, AF is associated with 4 to 5 folds increase in the risk of ischemic stroke in all age groups. About 5% to 15% of AF patients have atrial thrombi on transesophageal echocardiography, and 91% of those thrombi are located in the LAA in patient with nonrheumatic AF. Although oral anticoagulants are the gold-standard treatment for stroke prevention in patients with non-valvular AF,some patients are at high risk of bleeding and deemed not candidates for anticoagulation. Therefore, LAA occlusion(LAAO) has emerged as alternative approach for stroke prevention in those patients. Surgical LAAO is associated with high rate of unsuccessful closure and recommended only in patients with AF and undergoing cardiac surgery. Percutaneous LAAO uses transvenous access with trans-septal puncture and was first tested using the PLAATO device.Watchman is the most common and only Food and Drug Administration(FDA)approved device for LAAO. LAAO using Watchman device is non-inferior to warfarin therapy in preventing ischemic stroke/systemic thromboembolism.However, it is associated with lower rates of hemorrhagic stroke, bleeding and death. Amplatzer is another successful LAAO device that has CE mark and is waiting for FDA approval. Optimal antithrombotic therapy post LAAO is still under debate and highly patient-specific. The aim of this paper is to systematically review the current literature to evaluate the efficacy and safety of different LAAO devices.

Percutaneous left atrial appendage closure:Technical aspects and prevention of periprocedural complications with the watchman device

Transcatheter closure of the left atrial appendage has been developed as an alternative to chronic oral anticoagulation for stroke prevention in patients with atrial fibrillation, and as a primary therapy for patients with contraindications to chronic oral anticoagulation. The promise of this new intervention compared with warfarin has been supported by several, small studies and two pivotal randomized trial with the Watchman Device. The results regarding risk reduction for stroke have been favourable although acute complications were not infrequent. Procedural complications, which are mainly related to transseptal puncture and device implantation, include air embolism, pericardial effusions/tamponade and device embolization. Knowledge of nature, management and prevention of complications should minimize the risk of complications and allow transcatheter left atrial appendage closure to emerge as a therapeutic option for patients with atrial fibrillation at risk for cardioembolic stroke.

Device-related thrombosis on atrial septal defect occluder after simultaneous closure of left atrial appendage and atrial septal defect: a case report

An atrial septal defect (ASD) may cause right heart dysfunction, pulmonary hypertension and atrial fibrillation (AF), and atrial septal defect occlusion (ASDO) is the first choice for treating secundum defects when the morphology permits. ASD and AF frequently coexist, and the risk of AF and stroke persists after ASDO.[1] In recent years, left atrial appendage occlusion (LAAO) has been recognized as an effective treatment for stroke prevention in nonvalvular AF patients with a high risk of stroke, systemic embolism and bleeding who are unwilling to take oral anticoagulants or cannot tolerate them.

Coupling dynamic analysis of spacecraft with multiple cylindrical tanks and flexible appendages

This paper is mainly concerned with the coupling dynamic analysis of a complex spacecraft consisting of one main rigid platform, multiple liquid-filled cylindrical tanks, and a number of flexible appendages. Firstly, the carrier potential function equations of liquid in the tanks are deduced according to the wall boundary conditions. Through employ- ing the Fourier-Bessel series expansion method, the dynamic boundaries conditions on a curved free-surface under a low-gravity environment are transformed to general simple differential equations and the rigid-liquid coupled sloshing dynamic state equations of liquid in tanks are obtained. The state vectors of rigid-liquid coupled equations are composed with the modal coordinates of the relative potential func- tion and the modal coordinates of wave height. Based on the B ernoulli-Euler beam theory and the D＇Alembert＇s prin- ciple, the rigid-flexible coupled dynamic state equations of flexible appendages are directly derived, and the coordi- nate transform matrixes of maneuvering flexible appendages are precisely computed as time-varying. Then, the cou- pling dynamics state equations of the overall system of the spacecraft are modularly built by means of the Lagrange＇s equations in terms of quasi-coordinates. Lastly, the cou-piing dynamic performances of a typical complex spacecraft are studied. The availability and reliability of the presented method are also confirmed.

Percutaneous interventions in elderly patients with atrial fibrillation： leftatrial ablation and left atrial appendage occlusion

Heart rhythm disturbances become of special importancewhen patients reach a senior age. Atrial fibrillation （AF） isthe most prevalent arrhythmia among the old age groups,and its impact on morbidity and mortality becomes of para-mount significance. In this population, AF is responsible forsignificant amount of thromboembolic cerebrovascularevents, especially for disabling and fatal strokes, Follow-ing announcement of the special issue of the Journal of Geri-atric Cardiology devoted to heart rhythm disorders in theelderly, a number of submissions have been received withAF as the major topic of authors＇ researches.

Left atrial appendage occlusion: A better alternative to anticoagulation?

Non-valvular atrial fibrillation is associated with a significantly increased risk of embolic stroke due to blood clot forming predominantly in the left atrial appendage(LAA). Preventive measures to avoid embolic events are permanent administration of anticoagulants or surgical closure of the LAA. Various clinical trials provide evidence about safety, effectiveness and therapeutic success of LAA occlusion using various cardiac occluder devices. The use of such implants for interventional closure of the LAA is likely to become a valuable alternative for stroke prevention, especially in patients with contraindication for oral anticoagulation as safety, clinical benefit and cost-effectiveness of LAA occlusion has recently been demonstrated.

Left atrial appendage aneurysm: A case report

BACKGROUND An aneurysm of the left atrial appendage is one of the rare but potentially hazardous heart defects.The risk of lethal complications grows with its size.To date,about 150 cases of this defect have been described in the literature.We present a case of left atrial appendage aneurysm with the deformation of the mitral valve and the left main coronary and circumflex artery,which required mitral valve annuloplasty and bifurcation stenting.CASE SUMMARY A 58-year-old man presented to our hospital complaining of shortness of breath,general weakness,dizziness during physical exertion,and fatigue.Based on the results of echocardiography,an aneurysm of the left atrium was suspected.A free-breathing real-time cine magnetic resonance imaging with electrocardiograph synchronization confirmed the diagnosis of left atrial appendage aneurysm.The patient underwent an aneurysmectomy via a median sternotomy with cardiopulmonary bypass.Intraoperative transesophageal echocardiography revealed relative mitral insufficiency that was corrected with an annuloplasty ring.Intraoperative coronary angiogram showed impaired blood flow in the left main coronary and circumflex artery and 60%stenosis.For this reason,bifurcation stenting was performed.The patient had an uneventful postoperative clinical course and was discharged from the hospital on the 10th day in a satisfactory condition.CONCLUSION Left atrial appendage aneurysm is a rare and dangerous heart pathology that requires surgery to prevent related complications.

Dynamic response of liquid-filled rectangular tank with elastic appendages under pitching excitation

Nonlinear dynamics of liquid-filled rectangular tank with elastic appendages are studied. Based on the assumption of ideal fluid, the coupling dynamic equations of rigid tank, elastic appendages and liquid fuel are derived using H-O principle. In the case of pitch excitation, the modified potential function and wave height function are introduced to describe the moving boundary of fluid, then Galerkin＇s method is used to discretize the dynamic equations into ordinary differential equations. The natural frequencics of the coupling system are formulated in liquid depth, the length of the tank, etc. The formulae are confirmed by numerical simulations, which also show that the effects of liquid and elastic appendages on the attitude angular of rigid.

Delayed cardiac tamponade after simultaneous transcatheter atrial septal defect closure and left atrial appendage closure device implantation: a particular case report

Percutaneous left atrial appendage(LAA)occlusion evolved as an alternative treatment to the patients who are contraindicated or cannot tolerate oral anticoagulants with nonvalvular atrial fibrillation(AF)at risk of stroke or systemic embolism.[1]Abnormal hemodynamic changes in elder atrial septal defect(ASD)patients cause remodeling of the left atrium,which eventually leads to right heart failure.[2]As the ASDs elderly are associated with a higher incidence of AF,simultaneous transcatheter ASD and LAA closure has become a new effective therapeutic strategy.However,only a limited number of articles involving cardiac tamponade complications have been published in the literature.What’s more,previous studies involving early hemodynamically irrelevant pericardial effusion after the procedure attribute to multiple repositioning attempts of LAA occluder or delivery sheath injured the atrial wall.

Simultaneous Transcatheter Closure of the Left Atrial Appendage and Congenital Interatrial Communication Closure

Background:Left atrial appendage closure(LAAC)with simultaneous interventional occlusion therapy for congenital interatrial communication has become a new focus of patients with nonvalvular atrial fibrillation.Little is known about the results of mid-and long-term results.Objective:The aim of this study was to evaluate the midand long-term safety and effectiveness of simultaneous transcatheter closure of the left atrial appendage(LAA)and congenital interatrial communication closure in atrial fibrillation(AF)patients.Methods:From Jan 2016 to June 2017,27 patients with AF were treated with simultaneous transcatheter closure of the LAA and atrial septal defect(ASD,n=22),patent foramen ovale(PFO,n=5).Results:The perioperative closure success rate was 96.3%,except for cardiac tamponade occurred in one ASD patient.During the median 37.6-month follow-up period,no cases of cerebrovascular or peripheral vascular embolism,bleeding,infective endocarditis or thrombosis along the occluders were observed.Of the 21 patients with NYHA Class III,nineteen had significant improvements to NYHA Classes I or II,and 81.5%of patients were free from major or minor adverse events during midand long-term follow-up.Conclusions:Simultaneous closure of the LAA and congenital interatrial communication closure is a viable option for patients with nonvalvular atrial fibrillation who are at risk of stroke or systemic embolism,and it is effective and yields excellent mid-and long-term results.

Left atrial appendage occlusion in a mirror-image dextrocardia:A case report and review of literature

BACKGROUND In mirror-image dextrocardia,the anterior-posterior position of the cardiac chambers and great vessels is maintained,but the left-right orientation of the abdominal organs is reversed.The abnormal anatomy of the heart poses surgical challenges and problems in dealing with surgical risk and monitoring complications.There are few reports on closure of the left atrial appendage(LAA)in dextrocardia and no reports on the application of enhanced recovery after surgery(ERAS)following LAA occlusion(LAAO)procedures.CASE SUMMARY The objective for this case was to ensure perioperative safety and accelerate postoperative recovery from LAAO in a patient with mirror-image dextrocardia.ERAS was guided by the theory and practice of nursing care.Atrial fibrillation was diagnosed in a 77-year-old male patient,in whom LAAO was performed.The 2019 guidelines for perioperative care after cardiac surgery recommend that the clinical nursing procedures for patients with LAAO should be optimized to reduce the incidence of perioperative complications and ensure patient safety.Music therapy can be used throughout perioperative treatment and nursing to improve the anxiety symptoms of patients.CONCLUSION The procedure was uneventful and proceeded without complications.Anxiety symptoms were improved.

Evaluation of left atrial remodelling following percutaneous left atrial appendage closure

Atrial fibrillation prevalence is increasing with age, reaching up to 5% of patients older than 65 years, and is associated with 20%-30% of stroke episodes in that population.