AIMS: Catheter ablation is an effective treatment method for recurrent ventricular tachycardias (VTs). However, at least in part, procedural and clinical outcomes are limited by challenges in generating an adequate lesion size in the ventricular myocardium. We investigated procedural and clinical outcomes of VT ablation using a novel 'large-footprint' catheter that allows the creation of larger lesions either by radiofrequency (RF) or by pulsed field (PF) energy. METHODS AND RESULTS: In prospectively collected case series, we describe our initial experience with VT ablation using a lattice-tip, dual-energy catheter (Sphere-9, Medtronic), and a compatible proprietary electroanatomical mapping system (Affera, Medtronic). The study population consisted of 18 patients (aged 55 ± 15 years, one woman, structural heart disease: 94%, ischaemic heart disease: 56%, left ventricular ejection fraction: 34 ± 10%, electrical storm: 22%) with recurrent sustained VTs and ≥1 previously failed endocardial RF ablation with conventional irrigated-tip catheter in 66% of patients. On average, 12 ± 7 RF and 8 ± 9 PF applications were delivered per patient. In three-fourths of patients undergoing percutaneous epicardial ablation, spasms in coronary angiography were observed after PF applications. All resolved after intracoronary administration of nitrates. No acute phrenic nerve palsy was noted. One patient suffered from a stroke that resolved without sequelae. Post-ablation non-inducibility of VT was achieved in 89% of patients. Ventricular-arrhythmia-free survival at three months was 78%. CONCLUSION: VT ablation using a dual-energy lattice-tip catheter and a novel electroanatomical mapping system is feasible. It allows rapid mapping and effective substrate modification with good outcomes during short-term follow-up.
- MeSH
- Action Potentials MeSH
- Time Factors MeSH
- Equipment Design MeSH
- Progression-Free Survival MeSH
- Adult MeSH
- Electrophysiologic Techniques, Cardiac * MeSH
- Catheter Ablation * methods instrumentation adverse effects MeSH
- Tachycardia, Ventricular * surgery physiopathology diagnosis MeSH
- Middle Aged MeSH
- Humans MeSH
- Prospective Studies MeSH
- Recurrence MeSH
- Aged MeSH
- Cardiac Catheters * MeSH
- Feasibility Studies * MeSH
- Treatment Outcome MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Plant cytokinesis is orchestrated by a specialized structure, the phragmoplast. The phragmoplast first occurred in representatives of Charophyte algae and then became the main division apparatus in land plants. Major cellular activities, including cytoskeletal dynamics, vesicle trafficking, membrane assembly, and cell wall biosynthesis, cooperate in the phragmoplast under the guidance of a complex signaling network. Furthermore, the phragmoplast combines plant-specific features with the conserved cytokinetic processes of animals, fungi, and protists. As such, the phragmoplast represents a useful system for understanding both plant cell dynamics and the evolution of cytokinesis. We recognize that future research and knowledge transfer into other fields would benefit from standardized terminology. Here, we propose such a lexicon of terminology for specific structures and processes associated with plant cytokinesis.
- MeSH
- Models, Biological MeSH
- Cell Membrane metabolism MeSH
- Cell Division MeSH
- Chromosomes, Plant metabolism MeSH
- Cytokinesis * MeSH
- Cytoplasm metabolism MeSH
- Cytoskeleton metabolism MeSH
- Microtubules metabolism MeSH
- Plant Cells metabolism MeSH
- Terminology as Topic * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Intermediate filaments (IFs) are essential constituents of the metazoan cytoskeleton. A vast family of cytoplasmic IF proteins are capable of self-assembly from soluble tetrameric species into typical 10-12 nm wide filaments. The primary structure of these proteins includes the signature central 'rod' domain of ~ 300 residues which forms a dimeric α-helical coiled coil composed of three segments (coil1A, coil1B and coil2) interconnected by non-helical, flexible linkers (L1 and L12). The rod is flanked by flexible terminal head and tail domains. At present, the molecular architecture of mature IFs is only poorly known, limiting our capacity to rationalize the effect of numerous disease-related mutations found in IF proteins. Here we addressed the molecular structure of soluble vimentin tetramers which are formed by two antiparallel, staggered dimers with coil1B domains aligned (A11 tetramers). By examining a series of progressive truncations, we show that the presence of the coil1A domain is essential for the tetramer formation. In addition, we employed a novel chemical cross-linking pipeline including isotope labelling to identify intra- and interdimeric cross-links within the tetramer. We conclude that the tetramer is synergistically stabilized by the interactions of the aligned coil1B domains, the interactions between coil1A and the N-terminal portion of coil2, and the electrostatic attraction between the oppositely charged head and rod domains. Our cross-linking data indicate that, starting with a straight A11 tetramer, flexibility of linkers L1 and L12 enables 'backfolding' of both the coil1A and coil2 domains onto the tetrameric core formed by the coil1B domains. Through additional small-angle X-ray scattering experiments we show that the elongated A11 tetramers dominate in low ionic strength solutions, while there is also a significant structural flexibility especially in the terminal domains.
OBJECTIVES: This study sought to evaluate the safety and acute performance of the lattice tip for the treatment of atrial flutter and fibrillation (AF). BACKGROUND: A novel catheter using an expandable lattice structure with a wide thermal footprint incorporating multiple surface thermocouples/mini-electrodes has been designed for high-resolution mapping and high-current, temperature-controlled radiofrequency ablation (RFA). METHODS: Patients with typical right atrial flutter or AF were prospectively enrolled in a single-arm study at 3 centers. Patients with atrial flutter underwent cavotricuspid isthmus (CTI) ablation. Patients with paroxysmal AF underwent pulmonary vein isolation (PVI) and CTI if desired, and for patients with persistent AF, mitral isthmus and left atrial roof lines were also permitted. Mapping was performed with the lattice (Sphere-9) catheter and a novel compatible electroanatomic mapping system (Prism-1). RFA was performed in a point-by-point fashion (Tmax, 73°C to 80°C; range 2 to 7 s). Patients were followed for 3 months. RESULTS: A total of 71 patients underwent ablation: 65 PVI (38% with persistent AF) and 22 mitral isthmus, 24 roof, and 48 CTI lines. PVI was achieved in 64 of 65 (98.5%) by using the lattice alone and required a mean of 2.7 ± 0.70 RFA min. Mitral block was achieved in 100% by using 11.5 ± 10.7 applications and 1.0 ± 0.92 RFA min; only 1 patient required adjunctive epicardial coronary sinus ablation. Roof line and CTI block were achieved in 95.8% and 100% of patients, using 4.9 ± 1.9 and 5.9 ± 3.1 applications for 0.4 ± 0.16 and 0.5 ± 0.24 RFA min, respectively. At 3 months, there were no deaths, strokes, tamponade, or atrioesophageal fistula. CONCLUSIONS: This first-in-human study demonstrated clinical feasibility and safety for rapid high-current, temperature-controlled point-by-point PVI and linear ablation.
- MeSH
- Atrial Fibrillation * surgery MeSH
- Catheter Ablation * MeSH
- Catheters MeSH
- Humans MeSH
- Temperature MeSH
- Pulmonary Veins * surgery MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Hemihedral twinning is a crystal-growth anomaly in which a specimen is composed of two crystal domains that coincide with each other in three dimensions. However, the orientations of the crystal lattices in the two domains differ in a specific way. In diffraction data collected from hemihedrally twinned crystals, each observed intensity contains contributions from both of the domains. With perfect hemihedral twinning, the two domains have the same volumes and the observed intensities do not contain sufficient information to detwin the data. Here, the use of molecular replacement and of noncrystallographic symmetry (NCS) averaging to detwin a 2.1 Å resolution data set for Aichi virus 1 affected by perfect hemihedral twinning is described. The NCS averaging enabled the correction of errors in the detwinning introduced by the differences between the molecular-replacement model and the crystallized structure. The procedure permitted the structure to be determined from a molecular-replacement model that had 16% sequence identity and a 1.6 Å r.m.s.d. for C(α) atoms in comparison to the crystallized structure. The same approach could be used to solve other data sets affected by perfect hemihedral twinning from crystals with NCS.
- MeSH
- Chlorocebus aethiops MeSH
- Kobuvirus ultrastructure MeSH
- Crystallization MeSH
- Crystallography, X-Ray MeSH
- Models, Molecular MeSH
- Protein Binding MeSH
- Virion chemistry ultrastructure MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Vývoj a existenci specifických aktivit nervové buňky si nelze představit bez adekvátně strukturované nosné membrány. Začlenění funkčních proteinových komponent je kauzálně svázáno se stavbou lipidové dvojvrstvy která umožňuje nejen určitou prostorovou stabilitu (fixaci), ale současně i prostorovou návaznost, součinnost a variabilitu. Pohyb bílkovinných molekul v tekuté mozaice membrány je omezen jejich zakotvením do cytoskeletu. Ten má mechanicky podpůrný význam a hraje důležitou úlohu v přenosu informace do nitra buňky. U nervových buněk řídí interakce cytoskeletu a membrány výdej neurotransmitéru z presynaptických zakončení a recyklaci synaptických váčků. V souvislosti s hledáním markerů psychických poruch se předmětem intenzivního výzkumu stala i membrána červených krvinek, která má vysoce komplexní strukturu, srovnatelnou se strukturou membrán většiny eukaryotických buněk. Byly pozorovány četné biochemické abnormality červených krvinek při různých psychických poruchách, jako jsou změny v aktivitě některých membránově vázaných enzymů a receptoru, různé hladiny oxidativního stresu a změny ve složení lipidů.
Development and existence of specific activities of nerve cells are indispensable from the adequate structure of the supporting membrane. Integration of functional protein components determines the structure of lipid bilayer. It brings not only a certain special stability (fixation) but also a specific relationship, cooperation and variability among the components of the membrane. Movements of protein molecules within the fluid mosaic of the membrane are limited by their anchoring to the cytoskeleton. Cytoskeleton has mechanically supporting function and it plays an important role in the transmission of signals into the cell. In nerve cells interaction of cytoskeleton and membrane controls the release of neurotransmitter from the presynaptic terminals and recycling of synaptic vesicles. In relation to the quest for markers of psychic impairments, erythrocytal membrane became intensively studied. In its complex structure, comparable to the membrane of most of eukaryotic cells, biochemical abnormalities related to various psychic disorders were described: Changes in the activity of some membrane-bound enzymes and receptors, in the composition of lipids, and in different levels of oxidative stress.
