Demonstration of Right and Left Atrial Dissociation by Atrial Rapid Pacing or Extrastimulation During Fast-Slow (Uncommon) Form of Atrioventricular Nodal Reentrant Tachycardia

Some recent works suggest that extranodal atrial fibers may form part of the reenlry circuit in the atrioventricular (AV) nodal reentrant tachycardia (AVNRT). This hypothesis is based on the fact that the perinodal dissection successfully abolished AVNRT while preserving intact AV conduction. Apart from the surgical success, the electrophysiological evidence supporting this hypothesis has not been demonstrated, especially in the uncommon (fast-slow) form of AVNRT. We present some electrophysiological evidence suggesting atrial participation in eight patients with the fast-slow form of AVNRT. During the tachycardia, rapid pacing or extrastimulation was done from the orifice of the coronary sinus (CS) and the right atrium (RA), while recording the electrograms of the CS and the low septal RA. In seven patients, right and left atrial dissociation was demonstrated during pacing from the RA, while in the remaining one this was demonstrated from the CS. The interatrial dissociation will be unlikely if the intranodal reentry circuit connects with the atria via a single upper common pathway. This suggests that the upper turnaround of the reentry circuit involves atrial tissue and that the extranodal accessory pathway with long conduction times may form the ascending limb of the circuit (atrionodal reentry). Alternatively, the reentry circuit is entirely intranodal and two or more connecting pathways are present between the atria and the circuit.     

Effect of hypothermia on the in vitro potencies of neuromuscular blocking agents and on their antagonism by neostigmine

The effect of temperature on the potencies of neuromuscularblocking agents remains unclear. This study was undertaken toexamine the effects of different neuromuscular blocking agentsat 37 and 27 °C at a constant carbon dioxide content ( statprinciple). The effect of neostigmine 1 µmol litre^–1induced antagonism of these agents was also investigated. Phrenicnerve-hemidiaphragm preparations of rats were mounted in modifiedKrebs solution, maintained at 37 CC and aerated with a 5% carbondioxide-95% oxygen gas mixture, and at 27 °C with 4% carbondioxide to maintain the carbon dioxide content of the solutionconstant. Phrenic nerves were stimulated with 0.1 -Hz supra-maximalimpulses of 0.2-ms duration and the elicited tension of thediaphragm recorded. The potencies of the steroidal neuromuscularblocking agents (rocuronium, vecuronium, pancuronium and pipecuronium)increased significantly at 27 °C (P<0.05), while thepotencies of the benzyliso-quinolinium agents (tubocurarineand dimethyl-tubocurarine) did not change. Neostigmine-inducedantagonism of the steroidal agents did not differ significantlybetween each other but differed significantly from the benzylisoquinoliniumagents (P<0.05) at both temperatures. The ratios of IC₅₀(inhibitory concentration, 50%) with and without neostigmineat hypothermia were slightly higher for the steroidal agents,indicating slight enhancement of antagonism by neostigmine at27 °C. In contrast, the ratios were significantly greaterat 27 °C (P<0.05) for isoquinolinium agents, implyingsignificant enhancement of antagonism. Our results indicatethat at 27 °C the potency of all steroidal agents increasedand neostigmine-induced antagonism was slightly enhanced. Withthe isoquinolinium agents, hypothermia caused no change in potencyalthough neostigmine-induced antagonism was enhanced significantly.These findings suggest that the relative effects of steroidaland isoquinolinium agents on the neuromuscular junction aredifferent or that they have a different mechanism of actionon the neuromuscular junction.     

Evaluation of gender differences in caregiver burden in home care: Nagoya Longitudinal Study of the Frail Elderly (NLS-FE)

Background: Japan is presently experiencing a growth in the number of male caregivers and this situation has given rise to some concerns over gender differences. Previous studies have suggested that there are gender differences in caregiver burden in home care, however, it is still unclear whether or not gender differences exist. We therefore conducted this study to attain a better understanding of the Japanese male caregiver burden in home care, using data from the Nagoya Longitudinal Study of Frail Elderly (NLS‐FE). Methods: NLS‐FE is a large prospective study of community‐dwelling elderly persons eligible for public long‐term care insurance who live in Nagoya city and use the services of the Nagoya City Health Care Service Foundation for Older People, which comprises 17 visiting nursing stations and corresponding care‐managing centers, from November to December 2003. Data used in this study included the Japanese version of the Zarit Caregiver Burden Interview, caregivers’ and dependents’ characteristics, and the caregiving situation. The differences in dependent and caregiver characteristics between male and female caregiver groups were assessed using the χ²‐test for categorical variables or the unpaired t‐test for continuous variables. Multiple logistic regression was used to examine the association between dependent and caregiver characteristics and caregiver burden. Results: A total of 399 male caregivers and 1193 female caregivers were included in our analysis. Before and after controlling baseline variables, we did not detect a difference between male and female caregivers with respect to caregiver burden. Conclusion: Our study suggests that differences in caregiver burden may not necessarily exist between male and female caregivers in Japan.     

Significance of erb B-2 Gene Product as a Target Molecule for Cancer Therapy

The new monoclonal antibodies (MoAbs) E401, E811, E907 and E919 were prepared and characterized. These recognized an extracellular domain (amino acids No. 292–370) on the human c-erbB-2 gene product. Utilizing MoAb E811 and MoAb E919, a double determinant immunoassay (DDIA) was established to detect the soluble and the shed forms of the c-erbB-2 molecule. The levels of circulating erbB-2 antigen in the sera of patients with benign diseases and healthy controls were very low. The incidence of positivity for shed c-erbB-2 antigen in gastric cancer, eolonic cancer, gall-bladder caneer, pancreatic eancer and other cancers were 7.4%, 4.2%, 0%, 6.7% and 0%, respectively. Four of 54 patients with gastric carcinoma showed high levels of serum c-erbB-2 antigen. They belonged to clinical stage IV and their histological types were all well differentiated adenoeareinomas (two papillary and two tubular adenoeareinomas). Furthermore, the incidence of positive staining in gastric cancer was 34.6%; higher than that for shedding erbB-2 antigen. Most of the cases v-hich showed erbB-2 expression on cells were well-differentiated adenoeareinomas. Meanwhile, the distribution of erbB-2 antigen was limited in normal tissues. The results suggest that the expression of erbB-2 antigen is largely restricted to adenocarcinoma cells. It may not shed easily from these cells, and therefore It may be a very useful target molecule for passive immunotherapy.     

Clinical study of complicated urinary tract infection using ''The UTI Criteria (Draft Fourth Edition)'': Measurement methods for pyuria

OBJECTIVE: To evaluate the influences the change of the measurement method of pyuria from conventional centrifuged sediment to microchamber uncentrifuged urine for the results of evaluation of antimicrobial agents in clinical study against complicated urinary tract infections. From the viewpoint of international harmonization of judgement criteria, the recent method for counting white blood cells (WBC) in urine has changed from using uncentrifuged urine to using a microchamber in all countries. METHODS: Targeted diseases were non-catheterized complicated urinary tract infection, and cefcapene pivoxil hydrochloride or levofloxacin were used as antimicrobial drug. Pyuria was examined using the counting chamber method, a quantitative method using uncentrifuged urine with a microchamber, and the sedimentation method. RESULTS: Overall clinical efficacy in early evaluation by the two methods in measuring pyuria was evaluated as different in eight patients (7.3%). It was rated excellent in 63 (52.9%), moderate in 32 patients (26.9%) and poor in 24 (20.2%) with an efficacy rate of 79.8% using the counting chamber method, and excellent in 68 (57.1%), moderate in 27 (22.7%) and poor in 24 (20.2%) with an efficacy rate of 79.8% using the conventional sedimentation method CONCLUSION: No significant difference was seen between the two methods of WBC count in urine.     

Quantitative Analysis of Concealed Conduction into Accessory Atrioventricular Pathways in Wolff-Parkinson-White Syndrome

Concealed conduction is demonstrated to occur in an accessory AV pathway (AP). To test the hypothesis that anterograde and retrograde concealed conduction in the AP would have different characteristics, 35 consecutive patients with single APs were studied. The anterograde or retrograde ERP of the AP could be determined in 23 of those patients. Anterograde concealed conduction in the AP was assessed in the first 13 patients with retrograde AP conduction (8 APs with retrograde conduction only and 5 with both directions) (group A). Retrograde concealed conduction in the AP was evaluated in the remaining 10 patients with anterograde AP conduction (6 APs with anterograde conduction only and 4 with both directions) (group B). The concealed conduction in the AP was quantified by determining the ERP of the AP using a “probe” extrastimulus (S_p) introduced in the opposite chamber. The ERP was determined both during conventional extrastimulus (S₁S₂ method; ERP_c) and during that with an S_p (S₁S_pS₂ method; ERP_p). The S_p was delivered before or after the last S₁ with various S₁S_p intervals. The ERP_p was determined at each S₁S_p interval. Three distinct patterns in concealed conduction in the AP were noted. In the first pattern, the ERP_p was always shorter than the ERP_c, whereas the reverse relation was noted in the second pattern. The third pattern showed a combination of the two. In group A, only the first pattern was noted. In group B, the first, second, and third patterns were noted in 4, 2, and 4 patients, respectively. The first pattern was noted only in septal APs and the second and third were seen only in left free-wall APs. The second pattern was seen in patients with retrograde AP conduction, whereas the third one was mainly noted in patients without retrograde AP conduction. These observations indicate that anterograde and retrograde concealed conduction in the AP have different characteristics. Shortening of the ERP_p might be due to the “peeling back” phenomenon, and its lengthening might be caused by the presence of the inhomogeneous refractory periods of the AP. (PACE 1997; 20[Pt. I]:1342-1353)     

Endoscopy-Assisted Radiofrequency Ablation Around the Coronary Sinus Ostium in Dogs:

Endoscopy for Ablation Around the CS Ostium. Introduction : Radiofrequency ablation of the slow pathway can prolong atrioventricular (AV) nodal properties and RR intervals during atrial fibrillation (AF) in many patients with AV nodal reentrant tachycardia. However, it is not well elucidated whether these changes are related to the presence of dual AV nodal pathway physiology. The aim of this study was to evaluate changes of AV nodal properties and RR intervals during AF caused by ablation of two specific areas in dogs.
Methods and Results : Assisted by fiberoptic endoscopy, linear lesions were created between the coronary sinus ostium and tricuspid valve annulus (area 1) or posterior to the ostium (area 2) in 15 dogs. Three additional dogs served as controls. The measurements were made under autonomic blockade. Catheter ablation could be assisted in all dogs by means of endoscopy. Linear lesions were confirmed at autopsy. AV nodal parameters and RR intervals showed no overall changes. Individual data showed that ablation of area I resulted in modification of AV nodal properties in 54.5% (facilitation in 363% and inhibition in 18.2%), whereas ablation of area 2 induced changes in 50% (facilitation in 10% and inhibition in 40%). The RR intervals were shortened in 33.3% and 20% and prolonged in 44.5% and 40% after ablation of areas 1 and 2, respectively. The RR intervals during AF correlated well with the Wenckebach cycle length and the AV node functional refractory period before and after ablation (r = 0.78 to 0.94, P < 0.01 for each).
Conclusions : Ablation of the two specific areas around the coronary sinus ostium was equally effective in modifying AV nodal properties and the ventricular response during AF without dual AV nodal pathway physiology. The ventricular rate to AF after ablation correlated well with the residual AV nodal properties.