Differences in arrhythmogenicity between the canine right ventricular outflow tract and anteroinferior right ventricle in a model of Brugada syndrome

BACKGROUND: The Brugada syndrome is characterized by ST-segment elevation on the ECG, especially in the right precordial leads sensitive to the right ventricular outflow tract (RVOT). OBJECTIVES: The purpose of this study was to evaluate the hypothesis that right ventricular electrophysiologic heterogeneity caused arrhythmogenicity in the Brugada syndrome. METHODS: Action potentials (APs) were mapped on the epicardium of 14 RVOT preparations and on the transmural surfaces of 15 pairs of RVOT and right ventricular anteroinferior (RVAI) preparations isolated from canine hearts. Brugada ECG and arrhythmias were induced with pilsicainide (2.5-12.5 micromol/L), pinacidil (1.25-12.5 micromol/L), and terfenadine (2.0 micromol/L). RESULTS: Low doses of drugs elevated the J-ST segment and induced APs with both short and long action potential durations (APDs) in contiguous RVOT epicardial regions. In addition, APs in the RVOT had a larger phase 1 notch and longer APD than in RVAI. The longest APDs were in the epicardium in RVOT but in the endocardium in RVAI regions. High doses of drugs eliminated the phase 2 dome of the AP and abbreviated APDs in the epicardium but not in endocardium and reduced the epicardial heterogeneity of APs but increased the transmural gradient of APD in 14 (93%) of the RVOT preparations. In contrast, abbreviations of epicardial APDs occurred in only 4 (27%) of the RVAI preparations. Ventricular tachycardia occurred more frequently in the RVOT (47%) than in paired RVAI preparations (7%). Blocking the transient outward current reduced the heterogeneity of APs and eliminated arrhythmogenicity in all preparations. CONCLUSION: Compared with the RVAI region, the RVOT has greater electrophysiologic heterogeneity that contributes to arrhythmogenicity in this model of Brugada syndrome.     

Design of a Centrifugal Blood Pump with Magnetic Suspension

Abstract: A new concept blood pump, whose impeller is suspended by permanent magnets and a mechanical pivot without seals or ball bearings, is presented in this paper. The primary aim of the blood pump is an application to implantable artificial hearts. The prototype model is of a centrifugal type with a four-vaned semiopen impeller 50 mm in diameter. Since this mechanism has no seals or ball bearings, flow stagnation or heat generation that might cause blood cell denaturation is expected to be small. The results of performance testing for the prototype model 2 were satisfactory regarding pump head and efficiency. The radial-suspension magnets and the magnetic coupling were stable. As a result, the present mechanism has been verified to be a candidate applicable to implantable artificial hearts.     

Phenotypic abnormalities in CD8+ T lymphocyte subsets in patients with rheumatoid arthritis.

We analyzed the cell surface phenotype of CD8+ cells in both peripheral blood and synovial fluid (SF) of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Utilizing the monoclonal antibodies anti-CD45RA, anti-CD29 and anti-S6F1-, one can define both suppressor effector (CD45RA+CD29-S6F1-) and killer effector (CD45RA-CD29+S6F1+) cells within the CD8 population. In patients with OA, normal proportions of CD8+CD45RA+, CD8+CD29+ and CD8+S6F1+ cells were found in both peripheral blood and SF. The peripheral blood of patients with RA, in contrast, showed a decreased percentage of CD8+CD45RA+ cells (13.4 +/- 2.6) (p less than 0.05), but a normal percentage of CD8+CD29+ and CD8+S6F1+ cells. In the SF of patients with RA, we observed a more dramatic decrease in CD8+CD45RA+ suppressor effector cells (6.4 +/- 5.0) (p less than 0.001), a significant increase in killer effector cells as measured by both CD8 + CD29+ (35.5 +/- 9.9) (p less than 0.001) and CD8 + S6F1+ cells (28.2 +/- 11.4) (p less than 0.01). These changes may contribute to the immunologic abnormalities previously noted in this disease and may provide some insight into the pathophysiologic mechanisms of RA.     

Clinical features of patients with mild systemic lupus erythematosus.

Clinical features of 16 patients with mild systemic lupus erythematosus (SLE) were compared with those of 21 control patients with moderate or severe disease. Age at the time of diagnosis of SLE was higher in mild disease group. The incidence of the coexistence of Sj?gren's syndrome (SS) at the time of diagnosis of SLE was higher in patients who later developed mild disease. Anti-Sm antibody and decreased levels of C3, C4, and CH50 occurred less frequently in patients with mild disease. SLE patients with the coexistence of SS at the time of diagnosis of SLE may represent a subset with a benign prognosis.     

Experimental focal cerebral ischemia produced by embolization with silicone cylinder in normotensive (NTR) and spontaneously hypertensive rats (SHR): comparison of neurological and pathological findings

A focal cerebral ischemic model was produced by occlusion of the intracranial main cerebral artery with a silicone cylinder in normotensive (NTR) and spontaneously hypertensive rats (SHR). Main cerebral artery could be successfully occluded in approximately 90%. The most frequent embolized site was the distal part of the internal cerebral artery (ICb) and less frequently the horizontal segment of the anterior cerebral artery (Al). Mortality rate of NTR with ICb occlusion (NTR-ICb) was 43% at 72 hours after embolization and that of SHR with ICb occlusion (SHR-ICb) was 67% at 24 hours after embolization. NTR-ICb showed neurological signs (i.e. circling movement, hemiparesis, poor response to pain stimuli) and histologically, showed infarction in the deep cerebral structures (i.e. thalamus, hypothalamus, hippocampus, and internal capsule) accompanied with mild disruption of blood-brain barrier (BBB). SHR-ICb showed more serious neurological signs and more severe cerebral infarction in the deep cerebral structures with severe disruption of BBB. In SHR-ICb, ischemic cerebral edema was more prominent which may deteriorate symptoms and pathological findings compared to NTR-ICb. This embolization model is proposed to be useful for studying the pathophysiology of focal cerebral ischemia, especially, early ischemic edema.     

Clinical outcomes of two different endometrial preparation methods for cryopreserved-thawed embryo transfer in patients with a normal menstrual cycle

Aim:  To compare the clinical outcomes of cryopreserved-thawed embryo transfer among patients with a normal menstrual cycle who had natural or hormone-replacement cycles.
Methods:  From January 2004 to June 2006, cryopreserved embryos following conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) were thawed and transferred in a total of 720 natural cycles and 136 hormone-replacement cycles.
Results:  Cryopreserved-thawed embryo transfer in patients who had a natural or hormone-replacement cycle resulted in clinical pregnancy in 43.1% and 40.4%, respectively; a rate of miscarriage of 14.5% and 23.6%, respectively; and a rate of ongoing pregnancy and delivery of 36.5% and 30.9%, respectively. None of these differences were statistically significant.
Conclusions:   Patients with a normal menstrual cycle who have natural or hormone-replacement cycles can be expected to have comparable clinical outcomes with cryopreserved-thawed embryo transfer. (Reprod Med Biol 2007; 6 : 53–57)