Bibliothek

Notizen: Abstract: The structures of [3H]pargyline-labeled, flavin-containing polypeptides of monoamine oxidase (MAO) from hybrid NCB20 cells, and their parental cells, A/J mouse brain cells and Chinese hamster brain cells, were analyzed and compared by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and limited proteolysis and one-dimensional peptide mapping in SDS gels. After preincubation of mitocnondrial preparations with deprenyl or clorgyline, the flavin-containing polypeptide of type A or type B MAO was selectively labeled with [3H]pargyline. SDS-PAGE of [3H]pargyline-labeled mitochondrial samples revealed that the polypeptide with apparent Mr of 62,000 was associated with type A activity in the three types of cells, and that the polypeptide with apparent Mr of 61,000 or 58,000 was associated with type B activity in Chinese hamster brain cells and NCB20 cells or A/J mouse brain cells, respectively. Chymotrypsin digestion of the [3H]pargyline-labeled polypeptides and the peptide mapping in SDS gels from A/J mouse and Chinese hamster brain cells produced identical map patterns between the two type A MAOs, almost the same map patterns (with the exception of one additional peptide fragment) between the two type B MAOs, and different map patterns between type A and type B MAOs. The results of identical treatments of the [3H]pargyline-labeled polypeptides of MAOs in NCB20 cells showed that type A and type B MAO in NCB20 cells were similar to type A MAO of A/J mouse and Chinese hamster brain cells and to type B MAO of Chinese hamster brain cells. We previously reported that the activity of type A MAO in NCB20 cells coincided with the activity of MAO in N18TG-2 neuroblastoma cells which originate from A/J mouse and express solely type A MAO activity. Previous karyological studies indicated that most chromosomes of NCB20 cells derived from A/J mouse and that chromosome X, which may contain type A MAO of Chinese hamster origin, could not be recognized in NCB20 cells. The present study and these previous findings indicate that type A and type B MAOs in NCB20 cells may originate from A/J mouse and Chinese hamster, respectively, and that type A and type B MAO activities may be associated with distinct enzyme molecules.

Notizen: Introduction: A rapidly firing or triggered ectopic focus located within a pulmonary vein (PV) or close to the PV ostium could induce atrial fibrillation (AF). The aim of this study was to evaluate the efficacy and safety of a radiofrequency thermal balloon catheter for isolation of the PV from the left atrium (LA). Methods and Results: Twenty patients with drug-resistant paroxysmal AF were treated by isolating the superior PVs using an RF thermal balloon catheter. Using a transseptal approach, the balloon, which had an inflated diameter 5 to 10 mm larger than that of the PV ostium, was wedged at the LA-PV junction. It was heated by a very-high-frequency current (13.56 MHZ) applied to the coil electrode inside the balloon for 2 to 3 minutes, and the procedure was repeated up to four times. The balloon center temperature was maintained at 60° to 75°C by regulating generator output. Successful PV isolation was achieved in 19 of the 20 left superior PVs and in all 20 of the right superior PVs and was associated with a decrease in amplitude of the ostial potentials. Total procedure time was 1.8 ± 0.5 hours, which included 22 ± 7 minutes of fluoroscopy time. After a follow-up period of 8.1 ± 0.8 months, 17 patients were free from AF, with 10 not taking any antiarrhythmic drugs and 7 taking the same antiarrhythmic agent as before ablation. Electron beam computed tomography revealed no complications, such as PV stenosis at ablation sites. Conclusion: The PV and its ostial region can be safely and quickly isolated from the LA by circumferential ablation around the PV ostia using a radiofrequency thermal balloon catheter for treatment of AF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 609-615, June 2003)

Notizen: Endovascular interventions are considered the main therapeutic treatment modality for many vascular occlusive diseases. New indications emerge as short- and long-term successes are reported. For new devices, there is a need to determine the superiority of one device or technique over another. Evaluation of these techniques is further complicated by the fact that the alternative therapeutic options (medical and surgical management) also are undergoing progressive refinement. While some of these results have been validated through state-of-the-art and expensive clinical trials, others are supported only by limited observational data due to lack of sufficient funding or restrictive regulations. New and modified devices allow cardiac interventionists to perform more complicated procedures and successfully treat more complex lesions in sicker and older patients. Still, there are many limitations such as diffuse lesions, poor distal run-off, or too small vessels. Another limitation is that the procedure is not affordable for the majority of patients. There are many unanswered questions regarding the techniques, strategies, and effectiveness of these new modalities of treatment. Only through additional studies and the passage of time will we know the answers to these questions.

Notizen: This article discusses the clinical issues pertaining to an optimal stenting result and analyzes relevant stent structures and functions. There are five components of optimal stenting: favorable clinical features, easy stent delivery, ideal scaffolding, low stent thrombosis, and low restenosis. In straightforward cases, such as stenting in the mid-right coronary artery with a straight proximal segment, procedural success can be achieved with any stent. In vessels with curved, tortuous proximal segments, a highly flexible stent is needed for a smooth and successful delivery. For ostial, protected left main, or aortoanastomotic lesions, stents with sufficient radial strength and good visibility are needed. The two major concerns of an interventional cardiologist choosing a stent are excellent trackability for fast delivery and low long-term restenosis rate. In all situations, the procedural success depends on the operator's manual dexterity, experience with a particular stent design, and critical evaluation of different structural stent features to maximize benefits. Any new stent with high longitudinal flexibility, excellent scaffolding and radial strength, adequate radiopacity, complete deployment after one inflation, and that is easily recrossed and provides a good symmetrical conduit for a smooth coronary flow resulting in little tendency for thrombosis or restenosis would be today's stent of choice.

Notizen: Primary stent implantation in acute myocardial infarction (AMI) is defined as the intentional (not rescue) implantation of intracoronary stent(s) to the culprit lesion of AMI during emergency catheterization. All available data showed that this strategy has favorable short- and long-term clinical effects compared to primary balloon angioplasty.

Notizen: Transradial coronary intervention can result in similar procedural and clinical outcomes compared to those of transfemoral coronary intervention with lower access site complications. Continuing improvements in intracoronary stents and other interventional devices will facilitate further the coronary interventions by the transradial approach.