Abstract Background Epicardial to endocardial breakthrough (EEB) exists widely in atrial arrhythmia and is a cause for intractable cavotricuspid isthmus (CTI)‐dependent atrial flutter (AFL). This study aimed to investigate the electrophysiological features of EEB in EEB‐related CTI dependent AFL. Methods Six patients with EEB‐related CTI‐dependent AFL were identified among 142 consecutive patients who underwent CTI‐dependent AFL catheter ablation with an ultra‐high‐density, high‐resolution mapping system in three institutions. Activation maps and ablation procedure were analyzed. Results A total of seven EEBs were found in six patients. Four EEBs (including three at the right atrial septum and one in paraseptal isthmus) were recorded in three patients during tachycardia. The other three EEBs were identified at the inferolateral right atrium (RA) during pacing from the coronary sinus. The conduction characteristics through the EEB‐mediated structures were evaluated in three patients. Two patients only showed unidirectional conduction. Activation maps indicated that CTI‐dependent AFL with EEB at the atrial septum was actually bi‐atrial macro‐reentrant atrial tachycardia (BiAT). Intensive ablation at the central isthmus could block CTI bidirectionally in four cases. However, ablation targeted at the inferolateral RA EEB was required in two cases. Meanwhile, local potentials at the EEB location gradually split into two components with a change in activation sequence. Conclusions EEB is an underlying cause for intractable CTI‐dependent AFL. EEB‐mediated structure might show unidirectional conduction. CTI‐dependent AFL with EEB at the atrial septum may represent BiAT. Intensive ablation targeting the central isthmus or EEB at the inferolateral RA could block the CTI bidirectionally.
The hypoxia-inducible factor 1alpha (HIF-1alpha) regulates transcriptional genes involved in cell proliferation, survival, and differentiation. Under normoxia, HIF-1alpha has a short half-life (t((1/2)) approximately 5 min) and low transcriptional activity. An HIF-1alpha mutant, produced by substitution of alanine (Ala) for proline (Pro) at position 564 and asparagine (Asp) at position 803, can prevent HIF-1alpha hydroxylation and results in a highly active form of HIF-1alpha (HIF-1alpha-Ala564-Ala803). We hypothesized that adenovirus (Ad)-mediated transfer of the active form of HIF-1alpha (pAd-HIF-1alpha-Ala564-Ala803) could effectively occur in bone marrow stem cells (MSCs) and promote MSC differentiation under normoxia. PCR-based site-specific mutagenesis was used to construct the Ad vector expressing HIF-1alpha-Ala564-Ala803. RT-PCR and immunostaining were used to study whether pAd-HIF-1alpha-Ala564-Ala803 affected MSC differentiation to cardiomyocyte (CMC). pAd-HIF-1alpha-Ala564-Ala803 exhibited higher transcriptional activity and stable HIF-1alpha protein expression. Under normoxia, an MSC-CMC co-culture treated with pAd-HIF1a-Ala564-Ala803 augmented TGF-beta(1), Smad4, NKx2.5, and GATA4 expression. Higher expression of cTnT and alpha-actinin was observed by immunostaining in MSCs, compared with the control and contrast groups. Adenovirus-mediated hypoxia-inducible factor 1alpha double-mutant, pAd-HIF-1alpha-Ala564-Ala803, can stably express HIF-1alpha and promote its downstream genes and MSC differentiation to CMC in the MSC-CMC co-culture system under normoxia.
We tested the combined effects of antiangiogenic endostatin and epidermal growth factor receptor (EGFR) antisense gene therapy on squamous cell carcinoma (SCC).The 1483 cell line of human head and neck SCC (HNSCC) and SCC-VII/SF murine SCC cells was used to establish tumors in nude mice and immunocompetent C3H mice, respectively. Tumor-bearing mice were treated with endostatin (20 mg/kg/day, s.c.), liposomal EGFR-antisense expression plasmid (25 microg/mouse, three times/week, intratumoral), a combination of both agents, or liposomal EGFR-sense plasmid as a control. Endostatin or EGFR-antisense alone significantly, yet partially, inhibited the growth of 1483 and SCC-VII/SF tumors, and a combination of both treatments completely blocked tumor growth. Immunohistochemistry analysis demonstrated that a complete suppression of tumor angiogenesis was achieved by the combination treatment. Down-regulation of vascular endothelial growth factor was shown in EGFR-antisense-treated tumors. These results suggest that the EGFR-antisense treatment, in addition to its inhibitory activity on tumor cell proliferation, might have a synergistic effect with endostatin on SCC-induced angiogenesis. In vitro studies demonstrated that EGFR inhibition by antisense oligonucleotides or EGFR-specific tyrosine kinase inhibitor down-regulated the production of VEGF in HNSCC cells. Additional experiments demonstrated that these EGFR inhibition approaches also directly suppressed the growth of endothelial cells.A combination of endostatin and EGFR targeting strategies profoundly inhibited the angiogenesis and growth of SCC in vivo. EGFR-antisense therapy might have multiple inhibitory effects against both tumor cells and endothelial cells, leading to enhanced antitumor efficacy. Such a combination strategy might represent a novel and promising approach for HNSCC therapy.
Abstract Introduction Right ventricular outflow tract ventricular arrhythmias (RVOT VAs) often originate in the voltage‐transitional zone. The target electrogram could be compromised by the architecture of the roving catheter. Mini‐electrodes could improve the mapping resolution, especially in low‐voltage areas. The aim was to assess the electrophysiological characteristics of the earliest activation site (EAS) of RVOT VAs during mapping using mini‐electrodes. Methods and Results Twenty‐seven patients with RVOT‐type VAs were mapped using Orion mini‐electrodes and the Rhythmia mapping system. Bipolar and unipolar electrograms were analyzed and compared with conventional ablation catheter recordings. Twenty‐five patients (25 of 27) were successfully mapped and ablated at the RVOT. At the EAS, all 25 (100%) patients exhibited local sharp potentials (spiky potential) at the VAs, and 88% (22 of 25) individuals showed reverse late potentials in adjacent sinus beats on the bipolar mini‐electrode recordings. Related unipolar electrograms manifested 20% “q‐plateau‐QS,” 76% “gross QS,” and 4% “late QS” patterns related to spiky potential voltages and advanced times. Compared with electrograms recorded by ablation catheter, bipolar mini‐electrode recordings exhibited significantly shorter spiky potential durations ( P = 0.001) and a significantly increased incidence of the reverse late potentials ( P = 0.041). Unipolar mini‐electrode recordings had a lower incidence ratio of “late QS” patterns ( P = 0.039). Conclusion Compared with ablation catheter mapping, mini‐electrodes improved the mapping resolution of the EAS of RVOT VAs and exhibited shorter spiky potential durations and reduced incidence of “later QS” unipolar patterns.
To date no authentic embryonic stem cell (ESC) line or germline-competent-induced pluripotent stem cell (iPSC) line has been established for large animals. Despite this fact, there is an impression in the field that large animal ESCs or iPSCs are as good as mouse counterparts. Clarification of this issue is important for a healthy advancement of the stem cell field. Elucidation of the causes of this failure in obtaining high quality iPSCs/ESCs may offer essential clues for eventual establishment of authentic ESCs for large animals including humans. To this end, we first generated porcine iPSCs using nonintegrating replicating episomal plasmids. Although these porcine iPSCs met most pluripotency criteria, they could neither generate cloned piglets through nuclear transfer, nor contribute to later stage chimeras through morula injections or aggregations. We found that the reprogramming genes in iPSCs could not be removed even under negative selection, indicating they are required to maintain self-renewal. The persistent expression of these genes in porcine iPSCs in turn caused differentiation defects in vivo. Therefore, incomplete reprogramming manifested by a reliance on sustained expression of exogenous-reprogramming factors appears to be the main reason for the inability of porcine iPSCs to form iPSC-derived piglets.
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