Publications by authors named "Burkhardt D"

Two methods dominate the way that zebrafish larvae are euthanized after experimental procedures: anesthetic overdose and rapid cooling. Although MS-222 is easy to apply, this anesthetic takes about a minute to act and fish show aversive reactions and interindividual differences, limiting its reliability. Rapid cooling kills larvae after several hours and is not listed as an approved method in the relevant European Union directive.

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Objective: To describe immune responses following administration of experimental Salmonella Dublin siderophore receptor protein (SRP) vaccines in Holstein heifer calves with adequate passive antibody transfer.

Methods: Calves were randomly assigned to receive placebo, vaccination with S Dublin SRP in adjuvant A, or vaccination with S Dublin SRP in adjuvant B at 7 ± 3 days of age and 3 weeks later. Before each vaccination, 4 and 8 days after the second vaccination (postvaccination), and 61 to 91 days postvaccination, S Dublin antibody titers were measured.

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  • Cells are crucial for studying health and diseases, but traditional models are limited in their ability to accurately represent cell function and behavior.
  • Advances in AI and omics technology enable the development of AI virtual cells (AIVCs), complex models that simulate molecular, cellular, and tissue behavior across various conditions.
  • The creation of AIVCs aims to enhance biological research by allowing detailed simulations, speeding up discoveries, and promoting collaborative and interdisciplinary approaches in open scientific research.
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  • Robotic magnetic navigation (RMN)-guided catheter ablation (CA) technology has been effectively used for nearly 20 years in treating heart rhythm disorders, showing benefits like greater catheter stability and safety.
  • This consensus paper aims to compile current knowledge and offer guidelines on utilizing RMN-guided CA for conditions like atrial fibrillation (AF) and ventricular arrhythmias (VA).
  • The expert group reviewed literature and shared experiences to create a structured set of recommendations, addressing practical aspects of RMN use in clinical settings for optimal patient care.
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The cell is arguably the most fundamental unit of life and is central to understanding biology. Accurate modeling of cells is important for this understanding as well as for determining the root causes of disease. Recent advances in artificial intelligence (AI), combined with the ability to generate large-scale experimental data, present novel opportunities to model cells.

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  • - The study analyzed swimming turn performance in male and female Swiss national team members using advanced statistical methods (PCA and multiple linear regression) to evaluate kinematic and kinetic key performance indicators (KPI) across different age groups (adult, junior, youth).
  • - A motion analysis system with underwater cameras and force plates was used to gather detailed data on swimmers' performances, allowing for a reduction of original variables and a comprehensive understanding of the factors affecting swimming turns.
  • - The KPIs identified can help coaches and swimmers assess performance by highlighting strengths and weaknesses, and the percentiles provided serve as benchmarks for evaluating individual swimmer's potential.
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  • The rise of single-cell analysis tools makes benchmarks crucial for guiding analysis and method improvement.
  • Current benchmarks suffer from issues like lack of standardization and limited adaptability, affecting their usefulness over time.
  • Open Problems is introduced as a dynamic, community-driven benchmarking platform that addresses these issues by encompassing 10 current single-cell tasks to enhance method selection and evaluation.
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  • The KEYNOTE-782 study investigated the effects of first-line pembrolizumab plus chemotherapy on patients with metastatic non-small cell lung cancer (NSCLC), focusing on the correlation between blood tumor mutational burden (bTMB) and treatment outcomes.
  • Results showed that the overall response rate to treatment was 40.2%, with a median progression-free survival of 7.2 months and overall survival of 18.1 months, but no significant association was found between baseline bTMB and patient outcomes.
  • Adverse events were reported in 96.6% of patients, primarily at grades 3-5, but were considered consistent with known safety profiles of the treatments used.
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  • 3D-intracardiac echocardiography (ICE) enhances visualization of the left atrial appendage (LAA) during surgical procedures and leads to a high success rate for LAA occlusions.
  • In a study of 274 patients, 3D-ICE showed better accuracy in sizing the device compared to traditional 2D-ICE, with a 96.3% agreement on the final device size.
  • Both imaging methods provided a similar procedural success rate, but 3D-ICE reduced the need for device recapture and resizing during the procedure.
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Objectives: Histological scoring remains the gold-standard for quantifying post-traumatic osteoarthritis (ptOA) in animal models, allowing concurrent evaluation of numerous joint tissues. Available systems require scoring multiple sections/joint making analysis laborious and expensive. We investigated if a single section allowed equivalent quantitation of pathology in different joint tissues and disease stages, in three ptOA models.

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Checkpoint inhibitors (CPIs) targeting programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) have revolutionized cancer treatment but can trigger autoimmune complications, including CPI-induced diabetes mellitus (CPI-DM), which occurs preferentially with PD-1 blockade. We found evidence of pancreatic inflammation in patients with CPI-DM with shrinkage of pancreases, increased pancreatic enzymes, and in a case from a patient who died with CPI-DM, peri-islet lymphocytic infiltration. In the NOD mouse model, anti-PD-L1 but not anti-CTLA-4 induced diabetes rapidly.

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Objective: To identify clinical characteristics and factors associated with the development of euglycemic diabetic ketoacidosis (eDKA), and develop suitable strategies to reduce such events.

Methods: Electronic health record (EHR) data were extracted to identify all patients between December 1, 2013, and March 30, 2021, who underwent surgical procedures and had been prescribed a sodium-glucose cotransporter 2 inhibitor (SGLT2i) before these procedures. The resulting list was streamlined to a subset of patients who either had diabetic ketoacidosis (DKA) listed as a hospital diagnosis, postoperative serum bicarbonate ≤ 16 mmol/L, or postoperative serum pH ≤ 7.

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Abstract: Phenotypic plasticity describes the ability of cancer cells to undergo dynamic, nongenetic cell state changes that amplify cancer heterogeneity to promote metastasis and therapy evasion. Thus, cancer cells occupy a continuous spectrum of phenotypic states connected by trajectories defining dynamic transitions upon a cancer cell state landscape. With technologies proliferating to systematically record molecular mechanisms at single-cell resolution, we illuminate manifold learning techniques as emerging computational tools to effectively model cell state dynamics in a way that mimics our understanding of the cell state landscape.

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As the biomedical community produces datasets that are increasingly complex and high dimensional, there is a need for more sophisticated computational tools to extract biological insights. We present Multiscale PHATE, a method that sweeps through all levels of data granularity to learn abstracted biological features directly predictive of disease outcome. Built on a coarse-graining process called diffusion condensation, Multiscale PHATE learns a data topology that can be analyzed at coarse resolutions for high-level summarizations of data and at fine resolutions for detailed representations of subsets.

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  • The study investigates how Human Accelerated Regions (HARs) impact gene regulation during human evolution, specifically focusing on the HAR HACNS1.
  • Using genetically modified mice, the researchers found that HACNS1 retains its enhancer function, influencing the expression of the Gbx2 gene, which is crucial for limb development.
  • Single-cell RNA-sequencing revealed that HACNS1 increases Gbx2 levels in specific cell types, indicating that HARs play a significant role in the evolution of human developmental traits.
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Identification of physiological modulators of nuclear hormone receptor (NHR) activity is paramount for understanding the link between metabolism and transcriptional networks that orchestrate development and cellular physiology. Using libraries of metabolic enzymes alongside their substrates and products, we identify 1-deoxysphingosines as modulators of the activity of NR2F1 and 2 (COUP-TFs), which are orphan NHRs that are critical for development of the nervous system, heart, veins, and lymphatic vessels. We show that these non-canonical alanine-based sphingolipids bind to the NR2F1/2 ligand-binding domains (LBDs) and modulate their transcriptional activity in cell-based assays at physiological concentrations.

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  • The STROKE-VT study was a multicenter trial comparing the effectiveness of direct oral anticoagulants (DOACs) versus aspirin (ASA) in preventing cerebrovascular events after left ventricular arrhythmia (LVA) ablation.
  • Results showed that patients taking DOACs had significantly lower rates of stroke and transient ischemic attacks, as well as fewer asymptomatic cerebrovascular events at both 24 hours and 30 days post-procedure compared to those taking ASA.
  • Despite these differences in cerebrovascular outcomes, the rate of acute complications and in-hospital mortality was similar in both treatment groups.
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Often when biological entities are measured in multiple ways, there are distinct categories of information: some information is easy-to-obtain information (EI) and can be gathered on virtually every subject of interest, while other information is hard-to-obtain information (HI) and can only be gathered on some. We propose building a model to make probabilistic predictions of HI using EI. Our feature mapping GAN (FMGAN), based on the conditional GAN framework, uses an embedding network to process conditions as part of the conditional GAN training to create manifold structure when it is not readily present in the conditions.

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  • Atrioesophageal fistula (AEF) is a serious complication of atrial fibrillation ablation, with a median symptom onset of 21 days post-procedure and a high mortality rate of 59.3%.
  • Most patients (75%) showed neurological issues, and those evaluated at walk-in clinics faced longer delays in treatment compared to those seen by specialists.
  • Early recognition of symptoms, understanding diagnostic challenges, and timely coordination with electrophysiologists are crucial to improve outcomes and minimize mortality rates associated with AEF.
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  • Substrate catheter ablation is a common treatment for scar-related ventricular tachycardia (VT) in patients with ischemic cardiomyopathy, aiming to eliminate abnormal electrical signals within heart scars.
  • A study of 134 patients revealed that those on amiodarone therapy had better procedural outcomes, requiring less ablation time and fewer epicardial procedures compared to those not on the medication.
  • Over a follow-up period of nearly two years, patients not on amiodarone experienced a higher recurrence rate of ventricular arrhythmias, indicating that amiodarone may help maintain long-term success post-ablation.
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Current methods for comparing single-cell RNA sequencing datasets collected in multiple conditions focus on discrete regions of the transcriptional state space, such as clusters of cells. Here we quantify the effects of perturbations at the single-cell level using a continuous measure of the effect of a perturbation across the transcriptomic space. We describe this space as a manifold and develop a relative likelihood estimate of observing each cell in each of the experimental conditions using graph signal processing.

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Marginal differences in race results between top swimmers have evoked the interest in competition-based success factors of long-term athlete development. To identify novel factors for the multi-dimensional model of talent development, the aim of the study was to investigate annual variation in competition performance (ACV), number of races per year, and age. Therefore, 45,398 race results of all male participants ( = 353) competing in individual events, i.

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Background: Left atrial appendage electrical isolation (LAAEI) has been proposed for the treatment of nonparoxysmal atrial fibrillation (AF). The long-term clinical outcomes of this approach remain unclear. The objective of our study was to investigate the incremental benefit and safety of LAAEI in patients undergoing catheter ablation for nonparoxysmal AF.

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The percutaneous epicardial approach has become an adjunctive tool for electrophysiologists to treat disparate cardiac arrhythmias, including accessory pathways, atrial tachycardia, and particularly ventricular tachycardia. This novel technique prompted a strong impulse to perform epicardial access as an alternative strategy for pacing and defibrillation, left atrial appendage exclusion, heart failure with preserved ejection fraction, and genetically engineered tissue delivery. However, because of the incremental risk of major complications compared with stand-alone endocardial ablation, it is still practiced in a limited number of highly experienced centers across the world.

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Background: Thromboembolic stroke is a rare but devastating consequence of atrial fibrillation (AF) ablation. Transesophageal echocardiography (TEE) is recommended to rule out left atrial appendage thrombus; however, its use is variable.

Objective: The purpose of this study was to assess whether TEE is mandatory in patients undergoing AF ablation on uninterrupted direct oral anticoagulants (DOACs).

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