Reentry Activity Research Articles

Proposals for new transfer coefficient (TC) values for worker re-entry activities in grape vineyards

New transfer coefficient (TC) values were derived for vineyard workers handling treated grapevines during harvesting and crop maintenance activities. Re-entry exposure and dislodgeable foliar residue (DFR) studies were performed in Europe, covering hand harvesting, pruning/training, pruning/tying and pruning/shoot lifting. Foliar applications of fungicides (iprovalicarb, dimethomorph, dithianon, pyrimethanil and fenbuconazole) were made and 73 workers at 16 sites were monitored over one working day. Exposure was measured on inner and outer dosimeters, face/neck wipes and hand washes. In concurrent DFR studies, leaf punches were taken at each site during the time of worker re-entry. Potential exposure values correlated well with DFR values. TC values were derived for various re-entry activities for potential and actual exposure, with and without gloves. The harvesting task resulted in lower TC values than the other crop maintenance tasks. Additional TC values reflecting the use of protective gloves can be derived from the results. The TC values are much lower than current European Food Safety Authority (EFSA) default values. This project addresses a data gap identified by EFSA for specific EU TC values to permit more realistic and reliable re-entry worker exposure estimates for grapes.

PO-02-172 CONDUCTION VELOCITY AND CONDUCTION VELOCITY DYNAMICS IN THE LEFT ATRIUM ARE IMPACTED BY STRUCTURAL AND AUTONOMIC MODULATION AND SITES OF CONDUCTION VELOCITY HETEROGENEITY CORRELATE TO RE-ENTRY ACTIVITY IN ATRIAL FIBRILLATION

Structural and autonomic remodelling is proposed to drive atrial fibrillation (AF). Conduction velocity (CV) heterogeneity predisposes cardiac tissue to re-entry mechanisms. The impact of structural and autonomic remodelling on CV dynamics and re-entry formation is unclear. Evaluate the impact structural and autonomic modulation has on CV dynamics and re-entry activity in AF. Local activation times (LATs), voltage and geometry data were obtained from 20 patients undergoing catheter ablation for persistent AF. LATs were obtained at 3 pacing intervals (PI) (600, 400 and 250ms) with pacing from two pacing sites. LATs were used to determine CV dynamics and their relationship to voltage using an automated algorithm. Relationship between sites of enhanced CV heterogeneity defined as rate dependent CV slowing (RDCV) sites (sites exhibiting CV difference (CVd) between PI=600ms and PI=250ms of ≥20% of the mean CVd seen between these PIs for that voltage zone) and re-entry activity in AF was evaluated. Re-entry activity was identified using an automated algorithm and defined as ≥1.5 rotations of 360 degrees. The impact of autonomic modulation on CV dynamics both pharmacologically and with ganglionated plexi stimulation was assessed. A total of 512,082 LAT and voltage points were analysed. Voltage impacts CV (1.36±0.98 nLVZ ≥0.5mV, 1.05±1.03 LVZ 0.2-0.49mV and 0.58±0.37 vLVZ <0.2mV) (Figure 1A-B) and CV dynamics, whereby at nLVZ the curves are steeper (0.03±0.02ms CVd PI 600-400ms, 0.54±1.1ms CVd PI 400-250ms), broader at LVZ (0.16±0.09ms CVd PI 600-400ms, 0.23±1.1ms CVd PI 400-250ms) and flat at vLVZ (0.04±0.01ms CVd PI 600-400ms, 0.05±0.02ms CVd PI 400-250ms) (Figure 1C). Per patient, 5.6±1.1 RDCV sites and 3.4±1.3 sites of re-entry activity were identified. Of the RDCV sites, 72.3% (81/112) correlated to 94.1% (64/68) of re-entry activity sites which were mainly confined to LVZs (59/68, 86.8%). Autonomic modulation affected the CV dynamic curves through increasing rate dependency slowing (Figure 1D). The number of RDCV sites identified were enhanced following autonomic modulation (3.4±1.2 increase per patient). CVs and CV dynamics are impacted by structural remodelling and are influenced by autonomic modulation which enhances CV heterogeneity. CV heterogeneity sites correlate to re-entry activity in AF. Assessment of CV dynamics and heterogenity may help to determine the mechanistic importance of LVZs.

Radiofrequency catheter ablation as a treatment option in a patient with hypoplastic left heart syndrome and atrial flutter after Fontan operation-Case report.

We report a 15-year-old male with hypoplastic left heart syndrome (HLHS) after Fontan operation with recurrent, drug-resistant atrial tachycardia. With the use of electro-anatomical mapping system (EnSite) an atrial flutter (AFl) with reentry activation around the tricuspid valve was diagnosed. Successful radiofrequency catheter ablation (RFCA) was performed.

Rapid initiation of cell cycle reentry processes protects neurons from amyloid-β toxicity

Neurons are postmitotic cells. Reactivation of the cell cycle by neurons has been reported in Alzheimer's disease (AD) brains and models. This gave rise to the hypothesis that reentering the cell cycle renders neurons vulnerable and thus contributes to AD pathogenesis. Here, we use the fluorescent ubiquitination-based cell cycle indicator (FUCCI) technology to monitor the cell cycle in live neurons. We found transient, self-limited cell cycle reentry activity in naive neurons, suggesting that their postmitotic state is a dynamic process. Furthermore, we observed a diverse response to oligomeric amyloid-β (oAβ) challenge; neurons without cell cycle reentry activity would undergo cell death without activating the FUCCI reporter, while neurons undergoing cell cycle reentry activity at the time of the oAβ challenge could maintain and increase FUCCI reporter signal and evade cell death. Accordingly, we observed marked neuronal FUCCI positivity in the brains of human mutant Aβ precursor protein transgenic (APP23) mice together with increased neuronal expression of the endogenous cell cycle control protein geminin in the brains of 3-mo-old APP23 mice and human AD brains. Taken together, our data challenge the current view on cell cycle in neurons and AD, suggesting that pathways active during early cell cycle reentry in neurons protect from Aβ toxicity.

Dose Setting for Dermal Absorption Studies on Dried Foliar Residues.

Currently, the standard approach to estimate systemic exposure of workers after contact with dried pesticide residues on crops during re-entry activities relies on using the highest identified dermal absorption value for aqueous spray dilutions. However, recent dermal absorption studies with dried residues and their respective in-use dilutions have shown that this is likely to significantly overestimate their dermal penetration potential and, thus, predicted systemic exposure. The choice of appropriate dose levels for these dermal absorption studies has not been defined. Moreover, actual skin loading during re-entry tasks may differ significantly from that achieved by applying a fixed volume of an aqueous dilution, which is the standard practice in generic dermal absorption studies. To address this, we propose an approach to dose setting for dried residue studies within the current European risk assessment framework. Skin loading for studies can be calculated from the existing exposure algorithms and by taking appropriate body surface areas into account. Thus, skin loading in studies will vary depending on the exact nature and duration of the task and the region of the body exposed, reflecting actual exposure scenarios.

Learning within Hierarchies: Corporate Proximity and Business Unit Response to Adverse Events

This paper examines how a business unit’s proximity to its corporate office influences its learning from and response to experience of adverse events, or market failure. We argue that corporate proximity provides attention and knowledge to the business unit which, in general can be detrimental to overall responsiveness to market failure, but is helpful in the presence of adverse events because it focuses corporate attention and knowledge on particular problems and solutions. We examine three types of proximity – hierarchical, geographic, and cognitive – and also examine the conditioning impact of product novelty. Empirical analysis of business unit’s product market reentry activities in the U.S. medical device industry from 1984 to 1996 provides support for our hypotheses. Our paper contributes to theories of organizational learning, organizational design, and product market entry.

A comparison between different Purkinje network generation methods

Heart diseases are the major cause of deaths worldwide and within this context, the most common disease is cardiac arrhythmia. There is some evidence that the generation and maintenance of those arrhythmias might be related to the properties of the Purkinje system. Mostly because of its complex structure, which is thought to be the source of reentry activity, one of the precursors of dangerous arrhythmias. The objective of this work is to investigate how the morphology and properties of the Purkinje fibers of the heart may affect the electrical activation of the tissue. In order to build the Purkinje networks of this project, three different algorithms were used and their responses in activating the ventricular walls were compared. The monodomain equation was used to mathematically model the electrical activation and a parallel solver was used to speed up the numerical solution of the problem. The results of this work show that together with the geometry of the Purkinje network, properties of the coupling between the terminals of the network and the ventricular tissue also affect the electrical activation by leading to conduction blocks.

Empowering Children Through School Re-Entry Activities After the COVID-19 Pandemic.

The isolation related to the COVID-19 pandemic is causing both physical and mental health concerns for children worldwide. When the pandemic is over, schools and kindergartens represent a crucial context that can play an important role in promoting young people's well-being. This paper presents a school re-entry program aimed at creating an arena where children can process emotions, rediscover interpersonal connections, and develop an awareness of effective coping strategies. For all kindergarten, primary and middle school students, suggestions for evaluating the effectiveness of the program based on its educational and psycho-social components are given. School is an ideal setting to deliver these activities to children as it represents return to their daily routine. Schools also provide equal access to resources and reach children belonging to at-risk socio-economic categories and cultural minorities. Two printable activity packs are provided as additional materials for teachers who want to recreate or adapt the presented activities for their own contexts.

Virtual Reality as a Rehabilitation Tool for Community Re-Entry Activities

Virtual Reality as a Rehabilitation Tool for Community Re-Entry Activities

Searching for the Key to Foreseeing Left Atrial Fibrosis in Atrial Fibrillation: Could This Be Simple and Reliable with MRI?

Searching for the Key to Foreseeing Left Atrial Fibrosis in Atrial Fibrillation: Could This Be Simple and Reliable with MRI?

Noninvasive mapping before surgical ablation for persistent, long-standing atrial fibrillation

ObjectiveThe study objective was to study the electrophysiologic mechanism of atrial fibrillation using a noninvasive, beat-by-beat, 3-dimensional mapping technique in patients with persistent and long-standing persistent atrial fibrillation undergoing concomitant surgical ablation. MethodsIn this pilot trial, 10 patients (6 male; mean age, 70 ± 10 years) with persistent atrial fibrillation were mapped preoperatively with a noninvasive surface system (ECVUE, CardioInsight, Medtronic Inc, Minneapolis, Minn). Eight patients were candidates for mitral valve surgery, 1 patient was a candidate for aortic valve and ascending aortic replacement, and 1 patient was a candidate for coronary bypass surgery. In 5 patients, tricuspid valve repair was also performed. The Cox-Maze III/IV was performed using combined cryoablation and bipolar radiofrequency, and the left appendage was removed in all cases. The median preprocedural duration of atrial fibrillation was 30 months, and the diameter of the left atrium was 63 mm. Atrial regions were divided according to the Bordeaux classification. ResultsPreoperative mapping was successful in all patients with clear identification of the potential mechanism of atrial fibrillation. Biatrial pathology was recognized in all subjects. Rotor and macro re-entry activity were present in all patients, whereas focal activity was demonstrated in only 6 patients. Rotor activity in the right atrium was documented in all patients. ConclusionsThis is the first report on the preoperative use of the ECUVE in surgical candidates for concomitant surgical procedures. The fact that a biatrial mechanism for atrial fibrillation was detected in all patients emphasizes the importance of a Cox-Maze III/IV procedure to treat patients with valvular heart disease and nonparoxysmal atrial fibrillation. Preoperative mapping has the potential to significantly improve our understanding of the pathophysiology in atrial fibrillation and better guide the surgical ablation procedure of choice in a single patient.

Coupling interval variability of premature ventricular contractions in patients with different underlying pathology: an insight into the arrhythmia mechanism

PurposeCoupling interval (CI) variability of premature ventricular contractions (PVCs) is influenced by the underlying arrhythmia mechanism. The aim of this study was to compare CI variability of PVCs in different myocardial disease entities, in order to gain insight into their arrhythmia mechanism.MethodsSixty-four patients with four underlying pathologies were included: idiopathic (n = 16), non-ischemic dilated cardiomyopathy (NIDCM) (n = 16), familial cardiomyopathy (PLN/LMNA) (n = 16), and post-MI (n = 16)-associated PVCs. The post-MI group was included as a reference, on account of its known re-entry mechanism. On Holter registrations, the first 20 CIs of the dominant PVC morphology were measured manually after which median ΔCI and mean SD of CI/√R-R (= CI of PVC corrected for underlying heart rate) were obtained. Two observers independently measured PVC CIs on pre-selected Holter registrations in order to determine inter- and intra-observer reliability.ResultsThe largest ΔCI was seen in the PLN/LMNA group (220 ms (120–295)), the lowest in the idiopathic group (120 ms (100–190)). The ΔCI in the PLN/LMNA group was significantly larger than the post-MI group (220 ms (120–295) vs 130 ms (105–155), p = 0.023). Mean SD of CI/√R-R in the PLN/LMNA group was also significantly higher than in the post-MI group (p = 0.044). Inter- and intra-observer reliability was good (ICC = 0.91 vs 0.86 and 0.96 vs 0.77, respectively).ConclusionsLow ΔCI and SD of CI/√R-R of idiopathic and NIDCM PVCs suggest that the underlying arrhythmia mechanisms might be re-entry or triggered activity. Abnormal automaticity or modulated parasystole are unlikely mechanisms. High CI variability in PLN/LMNA patients suggests that the re-entry and triggered activity are less likely mechanisms in this group.

Atrial fibrillation ablation in athletes: an Olympic challenge?

Sports practice is very popular in our Western society as an epitome of a healthy life style, and endurance athletes have been our heroes since the days of the Greek in Olympia. However, aside from direct physical injury, there appear to be more indirect pathophysiological dangers that lurk around the corner. It has been established that individuals participating in regular intense physical exercise for several times a week have a two-fold risk of developing atrial fibrillation (AF). The Arrhythmia Unit of the Hospital Clinic in Barcelona, Spain, was among the first to make such observations in a population of AF patients with long-term sports activity.1 The Barcelona group extends their research by examining the results of ablation in athletes with AF.2 What is it that may distinguish athletes from other individuals? An increased physical demand may lead to structural adaptations of the heart, such as hypertrophy, dilatation, and fibrosis. Also, functional alterations in cellular ion channel expression and electrolyte handling may be evoked. In addition, an increased vagal tone and a lower resting heart rate can be found in well-trained athletes. Such changes may affect the electrophysiological properties of the atria and promote reentry and focal activity, which are established mechanisms for AF. The next question would be whether athletes with AF are any different … *Corresponding author. Tel: +31 30 609 9111, Fax: +31 30 609 2274, Email: l.boersma{at}Antonius.net

Biological monitoring and questionnaire for assessing exposure to ethylenebisdithiocarbamates in a multicenter European field study

This study deals with pesticide exposure profile in some European countries with a specific focus on ethylenebisdithiocarbamates (EBDC). In all, 55 Bulgarian greenhouse workers, 51 Finnish potato farmers, 48 Italian vineyard workers, 42 Dutch floriculture farmers, and 52 Bulgarian zineb producers entered the study. Each group was matched with a group of not occupationally exposed subjects. Exposure data were gained through self-administered questionnaires and measuring ethylenethiourea (ETU) in two spot urine samples collected, respectively, before the beginning of seasonal exposure (T0), and after 30 days, at the end of the exposure period (T30). Controls underwent a similar protocol. Study agriculture workers were involved in mixing and loading pesticides, application of pesticide mixture with mechanical or manual equipments, re-entry activities, and cleaning equipments. Chemical workers were involved in synthesis, quality controls, and packing activities. The number of pesticides to whom these subjects were exposed varied from one (zineb production) to eight (potato farmers). The use of personal protective devices was variegate and regarded both aerial and dermal penetration routes. EBDC exposure, assessed by T30 urinary ETU, was found to follow the order: greenhouse workers, zineb producers, vineyard workers, potato farmers, floriculture farmers with median levels of 49.6, 23.0, 11.8, 7.5, and 0.9 microg/g creatinine; the last group having ETU at the same level of controls (approximately 0.5 microg/g creatinine). Among agriculture workers, pesticide application, especially using manual equipment, seems to be the major determinant in explaining internal dose. Although the analysis of self-administered questionnaires evidenced difficulties especially related to lack and/or poor quality of reported data, biological monitoring confirms to be a powerful tool in assessing pesticide exposure.

Intracellular calcium dynamics at the core of endocardial stationary spiral waves in Langendorff-perfused rabbit hearts

In vitro models of sustained monomorphic ventricular tachycardia (MVT) are rare and do not usually show spiral reentry on the epicardium. We hypothesized that MVT is associated with the spiral wave in the endocardium and that this stable reentrant propagation is supported by a persistently elevated intracellular calcium (Ca(i)) transient at the core of the spiral wave. We performed dual optical mapping of transmembrane potential (V(m)) and Ca(i) dynamics of the right ventricular (RV) endocardium in Langendorff-perfused rabbit hearts (n = 12). Among 64 induced arrhythmias, 55% were sustained MVT (>10 min). Eighty percent of MVT showed stationary spiral waves (>10 cycles, cycle length: 128 +/- 14.6 ms) in the endocardial mapped region, anchoring to the anatomic discontinuities. No reentry activity was observed in the epicardium. During reentry, the amplitudes of V(m) and Ca(i) signals were higher in the periphery and gradually decreased toward the core. At the core, maximal V(m) and Ca(i) amplitudes were 42.95 +/- 5.89% and 43.95 +/- 9.46%, respectively, of the control (P < 0.001). However, the trough of the V(m) and Ca(i) signals at the core were higher than those in the periphery, indicating persistent V(m) and Ca(i) elevations during reentry. BAPTA-AM, a calcium chelator, significantly reduced the maximal Ca(i) transient amplitude and prevented sustained MVT and spiral wave formation in the mapped region. These findings indicate that endocardial spiral waves often anchor to anatomic discontinuities causing stable MVT in normal rabbit ventricles. The spiral core is characterized by diminished V(m) and Ca(i) amplitudes and persistent V(m) and Ca(i) elevations during reentry.

Spontaneous abortion and maternal work in greenhouses

A positive association between maternal occupational exposure to pesticide and spontaneous abortion has been reported in some studies. Work in greenhouses may imply exposure of pregnant women to pesticides continuously and at elevated level. A total of 717 women working in greenhouses provided information on 973 pregnancies, including 110 spontaneous abortions. These pregnancies were classified as exposed or not exposed according to maternal occupation, re-entry activities and application of pesticides in greenhouses during at least 1 month in the first trimester of pregnancy. The ORs for spontaneous abortion were estimated through a generalised estimate equations model for all orders of pregnancy together, and through a logistic regression model limited to first pregnancies. Increased risks of spontaneous abortion were found for maternal re-entry activities within 24 hr after pesticides were applied (all orders of pregnancy: OR 3.2, 95% CI 1.3-7.7; first pregnancies: OR 3.8, 95% CI 1.0-13.9) and for those who applied pesticides (all orders of pregnancy: OR 2.6, 95% CI 1.0-6.6; first pregnancies: OR 3.7, 95% CI 0.7-20,6) The observed results support the hypothesis of an association between maternal work in greenhouses and spontaneous abortion. The main limitations of the study are lack of information on the specific chemicals used and the small number of pregnancies heavily exposed to pesticides.

Improving Employment Outcomes Through the Massachusetts Parole Board's Regional Reentry Center Initiative: Policy Analysis and Recommendations

The growth of the prison population in the United States over the past twenty-five years has yielded a number of complex policy debates, including the efficacy of lengthy sentences as a deterrent of crime, the social costs of imprisoning a growing proportion of American citizens, and the appropriate conditions of confinement. Receiving much less attention, however, is a question closely related to the growth of the prison population: what should the state do to aid the reentry of the increasing number of former prisoners released from confinement? Facing growing numbers of unsupervised releasees from state facilities, many state governments have enacted programs designed to provide voluntary sevices to ex-offenders upon their release. In this policy context, we review the efficacy of the Massachusetts Regional Reentry Center Initiative (RRCI), a service program for unsupervised offenders released from state correctional facilities. The RRCI attempts to assist released prisoners with issues related to housing, substance abuse, mental and physical healthcare, employment, and the special needs of convicted sex offenders. We conclude that the RRCI, while a critical first step towards addressing the needs of the Commonwealth's growing population of unsupervised releasees, has several shortcomings that limit its efficiacy. We find that - The Department of Corrections' reentry activities are not integrated into the RRCI, resulting in redundancy and missed opporuntities to improve each agency's effectiveness; - RRC staff lacks the skill set necessary to address RRCI clients' needs; - The RRCI's strategy of referring clients to career centers for employment services does not appear to be effective; and - There is a mismatch between the timing of RRCI intervention and when most clients are actually seeking such services. We offer seven policy recommendations that will improve the efficacy of the RRCI and reduce the costs of managing the growing offender population's adjustment upon release.

Time to pregnancy among female greenhouse workers

Female greenhouse workers, who constitute a major occupational group exposed to pesticides at childbearing age, were studied to measure the effects of pesticide exposure on time to pregnancy. Data were collected through postal questionnaires with detailed questions on time to pregnancy, lifestyle factors (eg, smoking habits, coffee and alcohol consumption), and worktasks (eg, application of pesticides, re-entry activities, and workhours) of the respondents and their partners in a 6-month period prior to conception of the most recent pregnancy. The relation between time to pregnancy and exposure to pesticides among 398 female greenhouse workers and 524 referents was studied in a Cox's proportional hazards model. The crude fecundability ratio for female greenhouse workers versus the reference group was 1.18 [95% confidence interval (95% CI) 1.03-1.35], but correction for confounding changed the fecundability ratio to 1.11 (95% CI 0.96-1.29). An evaluation of specific biases for time-to-pregnancy studies showed that these results were biased by the reproductively unhealthy worker effect. Restricting the analyses to full-time workers or first pregnancies only resulted in an adjusted fecundability ratio of 0.89 (95% CI 0.67-1.19) and 0.90 (95% CI 0.62-1.32), respectively. Among the primigravidous greenhouse workers, an association was observed between prolonged time to pregnancy and gathering flowers (fecundability ratio 0.46, 95% CI 0.18-1.19). This study may offer some evidence for the hypothesis of adverse effects of pesticide exposure on time to pregnancy, but more research is needed to elucidate these effects.

Ventrikuläre Tachykardien

The origin of ventricular tachycardia lies in the ventricular tissue and includes a variety of symptoms such as monomorphic and polymorphic ventricular tachyarrhythmia (VT), ventricular flutter and ventricular fibrillation. Due to transitions of one form of VT to another, any form of VT incurs in principal the risk of cardiac failure. Apart from different electrophysiologic mechanisms such as reentry or triggered activity, any occurrence of VT has to be considered in an individual context: VT can be caused by structural heart disease such as coronary artery disease or dilative cardiomyopathy, or primary electrical disease such as long or short QT syndromes or can even occur without any detectable cause (idiopathic VT). Correct identification of the underlying cause of the arrhythmia is essential for the prognosis, differential therapy and long-term treatment of patients.

Diagnosis and treatment of idiopathic ventricular tachycardia.

Idiopathic ventricular tachycardia in patients with an anatomically normal heart is a distinct entity whose management and prognosis differs from ventricular tachycardia associated with structural heart disease. The tachycardia's QRS morphology on surface electrocardiogram (ECG) predicts the site of origin and is commonly classified as right ventricular tachycardia or left ventricular tachycardia. The tachycardia is further characterized by clinical features such as repetitive monomorphic ventricular tachycardia (VT), paroxysmal sustained VT, or catecholamine dependent VT. The responsiveness of VT to adenosine or verapamil is useful in differentiating the mechanism, which may be reentry or triggered activity. Patients generally tolerate the tachycardia but may present with dizziness, syncope, or palpitations. Sudden cardiac death is rare in this patient population. Patient work-up should include 12-lead ECG, signal-averaged ECG, ambulatory ECG recording, stress testing, and tests to rule out structural heart disease such as echocardiography, cardiac angiography, endomyocardial biopsy, or magnetic resonance imaging. Treatment options include pharmacotherapy or catheter ablation. Although the prognosis of these patients remains excellent, they should continue to have periodic cardiac follow-up to rule out latent progressive heart disease such as arrhythmogenic right ventricular dysplasia or cardiomyopathy or other forms of cardiomyopathies.