Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single Site and Biatrial Pacing

It has been reported that a trial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS-d), or biatrial (simultaneous BAA and CS-d) pacing. In the AF group, AF inducibility was significantly higher with BAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS-d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS-d paced drive. The atrial recovery time (ART) at RAA and CS-d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS-d was calculated as the ART difference (ARTD). The ARTD was significantly longer during BAA pacing in the AF group than in control group (155.0 +/- 32.8 vs 128.8 +/- 32.9 ms, P < 0.05). In the AFgroup, ARTDs during biatrial (52.0 +/- 24.2 ms) and CS-d pacing (51.7 +/- 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS-d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS-d and biatrial pacing significantly reduced ARTD compared with RAA pacing.     

Reduced shear stress and disturbed flow may lead to coronary aneurysm and thrombus formations

BACKGROUND: With Kawasaki disease it is important to clarify the mechanisms of coronary artery aneurysm and thrombus to avoid acute myocardial infarction. The authors tested the hypothesis that shear stress is reduced at coronary branching sites and in coronary artery aneurysms, and that this reduction of shear stress can promote formation of coronary artery aneurysms and thrombus. METHODS: The subjects were 111 children with Kawasaki disease with left coronary artery aneurysms, classified into three groups: giant coronary artery aneurysm (n= 28, diameter of coronary artery >8 mm), aneurysm (n= 44, diameter of coronary artery =8 mm), and normal-appearing coronary (n= 39). Averaged peak flow velocity (APV), flow patterns and shear stress were measured and calculated at normal-appearing coronary vessels, left coronary artery branching sites and intra-coronary aneurysm using flow wire, and coronary angiography. Also, presence and appearance of thrombus were detected by intravascular ultrasonography. RESULTS: The authors found that 90.3% of the coronary artery aneurysms occurred at major left coronary branching sites. APV and shear stress were significantly decreased in giant coronary artery aneurysms (APV, 7.1 +/- 2.1 cm/s; shear stress, 3.8 +/- 2.1 dyne/cm(2)) and at the left coronary artery branching site (APV, 9.1 +/- 1.2; shear stress, 1+/-+/-.2 3.0). In total, 20 of 24 thrombi were detected only in giant aneurysm, and all patients exhibited disturbed flow pattern in their giant coronary artery aneurysms. CONCLUSIONS: Reduced shear stress and disturbed flow pattern may lead to coronary artery aneurysm and thrombus formation.     

Developing a questionnaire on the quality of working life for female medical and healthcare professionals

This study aimed to develop a questionnaire on the quality of working life among female medical and healthcare professionals and examine its validity and reliability. The questionnaire was developed from an item pool drawing on the literature. The four trait scales included 40 items, covering female-specific stress in continuing a career, stress of lifestyle in maintaining personal values, job satisfaction and social support network. The questionnaire’s validity and reliability were assessed using data from 1,784 female doctors, dentists, and nurses. Validity was examined using exploratory factor analysis on each trait for construct validity, and multitrait scaling analysis for convergent and discriminant validity. Reliability was tested using Cronbach’s alpha for trait subscales and scales. Exploratory factor analysis on each trait was convergent. One trait derived three subscales, and another two. The remaining two traits were convergent for one factor. Multitrait scaling analysis showed that all scales and subscales were independent. The questionnaire was therefore internally consistent and had construct validity. Cronbach’s alpha was 0.85 for the total and between 0.72 and 0.83 for the subscales. These results validate the four-trait combination questionnaire and suggest that it would be suitable for use in future research, perhaps in combination with other existing scales.     

Pharmacokinetics of a new histamine H2-receptor antagonist,Z-300, in rat and dog

1. The plasma level of Z-300 reached a maximum (C_max) at 30?min after the oral administration of Z-300 to dog, and disappeared from the systemic circulation with a halflife of 8-9 h. The bioavailability of Z-300 was 52% after the oral administration of Z-300, 3?mg/kg. At doses ranging from 3 to 30?mg/kg, C_max and AUC (area under the plasma concentration-time curve) were proportional to the dose. 2. The plasma level of Z-300 reached C_max at 10?min after the oral administration of Z-300 to rat, and disappeared from the systemic circulation with a half-life of 0.8-1.6 h. The bioavailability of Z-300 was 39% after the oral administration of Z-300, 10?mg/kg, and there was a non-linear relationship between the plasma level-time profile of Z-300 and the administered dose (3-50?mg/kg). 3. The binding of Z-300 to plasma protein was 92% in man, 65% in dog and 25% in rat. It is suggested that these species differences were due to the content of α₁-acid glycoprotein (α₁-AG), because Z-300 bound more strongly to α₁-AG than to albumin.     

EFFECTS OF SEED SAPONINS OF THEA SINENSIS L. (RYOKUCHA SAPONIN) ON ALCOHOL ABSORPTION AND METABOLISM

We evaluated the effects of the seed saponins of Thea sinensisL. on alcohol absorption and metabolism in rats and mice. Anethanolic extract from the seeds of T. sinensis was orally administeredto the rats 1 hr before or 0.5 hr after administration of ethanol(2 g/kg), and the blood ethanol assayed 0.5, 1, 2, 3, and 4hr after ethanol administration. The ethanol level decreasedafter both pie- and post- administration of the extract. Theextract was further purified to obtain a saponin fraction whichwas orally administered to mice 1 hr before ethanol administration.Blood, liver, and stomach were obtained 0, 1, 3, and 6 hr afterethanol administration, and the ethanol, acetaldehyde, acetate,and acetone concentrations in each specimen were measured byhead space gas chromatography. The saponin fraction decreasedthe ethanol levels in the blood and liver but increased thatin the stomach five-fold over the control level, suggestinginhibition of alcohol absorption. The ethanol disappearancetime from the blood was shortened, suggesting the promotionof alcohol disappearance. The acetate and acetone levels wereunaffected. However, the acetaldehyde level decreased in theblood, liver, and stomach. The decreases in the ethanol andacetaldhyde levels in the liver suggested the protective effectsof the seed saponins on the liver. The saponins did not directlyinhibit hepalic alcohol dehydrogenase activity. The seed saponinsof T. sinensis seem to suppress alcohol absorption by slowinggastric emptying and by inhibiting absorption across the cellmembranes of the digestive tract.     

Inhibition of Lipid Peroxidation by Sesquiterpenoid in Heterotheca inuloides

A sesquiterpenoid, 7-hydroxy-3,4-dihydrocadalin, isolated from a Mexican medicinal plant Heterotheca inuloides was evaluated as an antioxidant. This sesquiterpenoid inhibited mitochondrial and microsomal lipid peroxidation induced by Fe(III)-ADP/NADH or Fe(III)-ADP/NADPH. Furthermore, 7-hydroxy-3,4-dihydrocadalin protected red cells against oxidative haemolysis. This sesquiterpene was thus shown to be effective in protecting biological systems against oxidative stresses.     

The cells of the rabbit meniscus: their arrangement, interrelationship, morphological variations and cytoarchitecture

Four major morphologically distinct classes of cells were identified within the adult rabbit meniscus using antibodies to cytoskeletal proteins. Two classes of cell were present in the fibrocartilage region of the meniscus. These meniscal cells exhibited long cellular processes that extended from the cell body. A third cell type found in the inner hyaline-like region of the meniscus had a rounded form and lacked projections. A fourth cell type with a fusiform shape and no cytoplasmic projections was found along the superficial regions of the meniscus. Using a monoclonal antibody to connexin 43, numerous gap junctions were observed in the fibrocartilage region, whereas none were seen in cells either from the hyaline-like or the superficial zones of the meniscus. The majority of the cells within the meniscus exhibited other specific features such as primary cilia and 2 centrosomes. The placement of the meniscal cell subtypes as well as their morphology and architecture support the supposition that their specific characteristics underlie the ability of the meniscus to respond to different types of environmental mechanical loads.     

Perspectives on phantom boarder symptom

Phantom boarder symptom (PBS) is a hallucinatory and delusional syndrome that tends to occur in the elderly, in which the patient imagines that someone uninvited is living in their home. This article provides an overview of the historical background that has led to the current focus on PBS as a single symptom, from its classification as late paraphrenia to its being recognized as a type of misidentification, and discusses classification problems and PBS subclassifications. In addition, the results of our own investigation of PBS, which focused on PBS in senile dementia, support the findings of previous studies, such as the absence of a relationship between dementia severity and the occurrence of delusion. The discussion therefore focuses on the psychosocial factors that serve as the mechanism of PBS onset, and directions and possibilities for therapy are suggested.     

Effects of High-frequency Current on Pacemakers during Endoscopic Gastric Surgery: Experimental Study

Abstract: This study examined the effects of high-frequency current on pacemakers. Pacemakers were implanted in mongrel dogs, gastric mucosal resection was performed endoscopically using monopolar and bipolar snares, and the times for resection and magnitude of interference current (IC) in the myocardial electrodes were compared. The time for resection was 9.56±2.87 seconds with a monopolar snare and 0.82±0.13 seconds with a bipolar snare (p<0.01). The magnitude of the IC was 0.59±0.26 mV with a monopolar snare and 0.26±0.12 mV with a bipolar snare (p<0.01). The times required for resection and the magnitude of the IC using a bipolar snare in the coagulation mode at an output of approximately 12 W were 1.97±0.65 seconds and 0.03±0.02 mV, respectively, and those in the cutting mode were 1.68±0.50 seconds and 0.07±0.04 mV, respectively. The magnitude of the IC was significantly less (p<0.01), but the time required for resection was longer in the coagulation mode. No abnormalities were noted in the pacemaker mode in any of the 10 pacemakers examined after mucosal resection with high-frequency current at an output of 300 W. These results suggest that endoscopic therapy using high-frequency current can be performed more safely with a bipolar snare than with a monopolar snare in patients with pacemakers. In addition, the selection of the endoscope mode is considered to be important. (Dig Endosc 1999; 11: 150–157)