Development of Bioactivity and Pull-out Torque Control Technology on Ti Implant Surface and its Application for Cold Thread Rolled Bone Screw

AbstractThe influence of cold thread rolling conditions and a production method of titania (TiO2) films on surface bioactivity and pull-out torque of a titanium bone screw was investigated. The bone screw with micro surface roughness distribution was formed by cold thread rolling with a pair of parallel dies. The die shape and surface roughness distribution were changed to the 3 grades. The TiO2 films were coated on the surface of the bone screw using anodizing in aqueous solutions (hydro-coating). We introduced the rolled bone screws into tibia of rats for two weeks and examined the effects of the combinations of the surface morphology and the TiO2 film on osteoconductivity in an in-vivo experiment. As the results, it is found that we could control the bioactivity and pull-out torque by controlling the surface roughness at the bottom of the screw root

Superiority of Biphasic Over Monophasic Defibrillation Shocks Is Attributable to Less Intracellular Calcium Transient Heterogeneity

ObjectivesThe purpose of this study was to test the hypothesis that superiority of biphasic waveform (BW) over monophasic waveform (MW) defibrillation shocks is attributable to less intracellular calcium (Cai) transient heterogeneity.BackgroundThe mechanism by which BW shocks have a higher defibrillation efficacy than MW shocks remains unclear.MethodsWe simultaneously mapped epicardial membrane potential (Vm) and Cai during 6-ms MW and 3-ms/3-ms BW shocks in 19 Langendorff-perfused rabbit ventricles. After shock, the percentage of depolarized area was plotted over time. The maximum (peak) post-shock values (VmP and CaiP, respectively) were used to measure heterogeneity. Higher VmP and CaiP imply less heterogeneity.ResultsThe defibrillation thresholds for BW and MW shocks were 288 ± 99 V and 399 ± 155 V, respectively (p = 0.0005). Successful BW shocks had higher VmP (88 ± 9%) and CaiP (70 ± 13%) than unsuccessful MW shocks (VmP 76 ± 10%, p < 0.001; CaiP 57 ± 8%, p < 0.001) of the same shock strength. In contrast, for unsuccessful BW and MW shocks of the same shock strengths, the VmP and CaiP were not significantly different. The MW shocks more frequently created regions of low Cai surrounded by regions of high Cai (post-shock Cai sinkholes). The defibrillation threshold for MW and BW shocks became similar after disabling the sarcoplasmic reticulum (SR) with thapsigargin and ryanodine.ConclusionsThe greater efficacy of BW shocks is directly related to their less heterogeneous effects on shock-induced SR Ca release and Cai transients. Less heterogeneous Cai transients reduces the probability of Cai sinkhole formation, thereby preventing the post-shock reinitiation of ventricular fibrillation

Abnormal asexual reproduction of thalli of Ecklonia stolonifera (Laminariales, Phaeophyceae) off the coast of Nakanoshima in the Oki Islands, Japan

Multiple abnormal individuals of Ecklonia stolonifera with thalli that developed numerous shoot-like structures on the lateral blades were found in two littoral regions of Nakanoshima in the Oki Islands, Shimane Prefecture, Japan. Except for the presence of these diagnostic structures, no other morphological differences were observed between the abnormal and normal individuals. The development of the shoot-like structures isolated from the lateral blade was the same as that of typical vegetative reproductive sporophytes that formed on stolons. In the abnormal individuals, when cultivation was performed using zoospores, the shoot-like structures were observed on the progeny after 18 months of culture and 20.0% of individuals exhibited these structures

Electrophysiological and anatomical background of the fusion configuration of diastolic and presystolic Purkinje potentials in patients with verapamil-sensitive idiopathic left ventricular tachycardia

Background: It is unclear whether false tendons (FTs) are a substantial part of the reentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT). This study aimed to prove the association between FTs and the slow conduction zone by evaluating the electro-anatomical relationship between the so-called diastolic Purkinje (Pd) potentials and FTs using an electro-anatomical mapping (EAM) system (CARTO). Methods: The 1st protocol evaluated the spatial distribution of Pd and presystolic Purkinje (Pp) potentials in 6 IVLT patients using a conventional CARTO system. In the remaining 2 patients (2nd protocol), the electro-anatomical relationship between the Pd–Pp fusion potential and the septal connection of the FT was evaluated using an EAM system incorporating an intra-cardiac echo (CARTO-Sound). Results: Pd potentials were observed in the posterior–posteroseptal region of the LV and had a slow conduction property, whereas Pp potentials were widely distributed in the interventricular (IV) septum. At the intersection of the 2 regions, which was located in the mid-posteroseptal area, both Pd and Pp potentials were closely spaced and often had a fused configuration. In the latter 2 patients (2nd protocol), it was confirmed that the intra-cardiac points at which the Pd–Pp fusion potential was recorded were located in the vicinity of the attachment site of the FT to the IV septum. In all patients, ILVTs were successfully eliminated by the application of radiofrequency at those points. Conclusion: FTs may at least partly contribute to the formation of the Pd potential, and thus form a critical part of the reentry circuit of ILVT

The role of Purkinje fibers in the emergence of an incessant form of polymorphic ventricular tachycardia or ventricular fibrillation associated with ischemic heart disease

Background: The clinical and electrophysiological characteristic of ventricular premature contractions (VPCs) which trigger the incessant form of polymorphic ventricular tachycardia (VT), so-called “electrical storm” associated with ischemic heart disease, remains unclarified. The aim of this study was to evaluate those matters and the possible role of the Purkinje network in the emergence of an electrical storm. Methods and results: We experienced 5 patients (68 ± 5 years, mean LVEF: 29%) with electrical storms which occurred during the acute phase of an infarction in 3 patients and the remote phase in 2. The triggering VPCs were multifocal in 3 patients and monofocal in the remaining 2. Radiofrequency (RF) catheter ablation was performed for a goal of eliminating the triggering VPCs. A total of 9 different kinds of VPCs differentiated by their morphology were successfully eliminated by the RF deliveries targeting the VPCs’ foci. At the successful ablation sites, Purkinje potentials preceded the QRS onset of the VPC by 67 ± 23 ms, suggesting the VPCs originated in the surviving Purkinje fibers. Moreover, the extensive RF deliveries applied at the surviving Purkinje network rendered the polymorphic VT unable to be induced by programmed stimulation which reproducibly induced it before the ablation in 2 patients. Conclusion: A surviving Purkinje network might contribute not only to the initiation of the repetitive form of lethal ventricular arrhythmias, but also to the perpetuation of the arrhythmias in patients with ischemic heart disease