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Biomedical subjects

M Tsubota

Publications and source records attributed to M Tsubota.

At least 55 records · Page 3Linked to original sources
PubMed1992

Structural analysis of nucleic acids by precise denaturing gradient gel electrophoresis: II. Applications to the analysis of subtle and drastic mobility changes of oligo- and polynucleotides.

Precise denaturing gradient gel electrophoresis was effectively applied to various kinds of oligo- and polynucleotides. The analyses on oligonucleotides revealed that every oligonucleotide has its own characteristic normalized mobility profile (NMP), which can be used to identify, characterize and classify the molecules. The precise system also enabled us to obtain unequivocally the mobility transitions corresponding to the melting of hairpin structures of oligonucleotides, single-stranded (ss) DNAs, and RNAs. Another application to co-migration and separate migration experiments demonstrated that there were significant binding interactions between two species of ss molecules of similar mobility, even when they have little complementarity with each other. When the precise temperature gradient gel electrophoresis was applied to double-stranded DNAs, it could be confirmed with high reliability that the mobility transitions observed correspond to cooperative meltings and strand dissociations. Through these experiments, mu m, a parameter defined as a mobility transition point, was shown to be effective to deal with those phenomena quantitatively.

Base Sequence↗
PubMed1991

Long-term results of surgery for non-ischemic ventricular tachycardia.

Drug resistant, non-ischemic ventricular tachycardia (VT) was treated in 43 patients by direct surgery based on electrophysiological data. Two main surgical techniques were employed: myocardium was resected followed by cryocoagulation with a special probe in 23 patients with VT originating from the right ventricle. The myocardium was incised followed by cryocoagulation in 10 patients with VT from the left ventricle. The follow-up period ranged from 1 week to 10 years, 4 weeks (mean 3 years, 8 months). After operation, 36 patients (83%) showed complete disappearance of VT without antiarrhythmic therapy. Of these 2 patients died of congestive heart failure not related to VT in the postoperative period at 1 year 4 months, and 2 years 4 months, respectively. In 7 patients, VT remained. In 2, VT disappeared after catheter ablation. In 3 patients, VT became controllable with antiarrhythmic therapy. Operation was not successful in 2 patients (5%); 1 with a giant left ventricular aneurysm died of low cardiac output syndrome due to VT 1 week after operation; the other with arrhythmogenic right ventricular dysplasia originating from both ventricles died suddenly 5 months after operation. The 10-year survival is 89%, and the 10-year freedom from recurrent VT is 83%. These results indicate that surgical management for non-ischemic VT is safe and effective with a high chance of cure.

Adolescent↗
PubMed1991

Diagnosis and treatment of left ventricular false aneurysm.

Three patients are presented in whom a false aneurysm of the left ventricle was surgically treated. False aneurysm of the left ventricle is an unusual consequence of ventricular wall rupture with containment of the resulting hematoma. Most false aneurysms of the left ventricle develop following myocardial infarction. The false aneurysm wall contains no myocardium. The false aneurysm has a great tendency to rupture, regardless of its size. One patient developed progressive congestive heart failure following a myocardial infarction. The other two patients were asymptomatic following myocardial infarction. Preoperative magnetic resonance imaging showed characteristics of a false aneurysm. These included a distinct discontinuance of the myocardium at the neck of the aneurysm and a narrow neck relative to the diameter of the aneurysm. Two patients underwent successful closure of the orifice of the false aneurysms. One patient underwent emergency surgery because of acute rupture while awaiting surgery but died of cerebral damage. Surgical correction of a false aneurysm is clearly advisable even in the absence of symptoms.

Echocardiography↗
PubMed1990

Reappraisal of bronchial arterial infusion therapy for advanced lung cancer.

As preoperative adjuvant therapy for advanced lung cancer, bronchial arterial infusion (BAI) of a chemotherapeutic agent was administered to patients with stage IIIa and IIIb hilar lung cancer. The infusion modality was changed for each term, from a single drug infusion, to a two drug infusion and then a three drug infusion, and the combination of infused drugs was selected in accordance with cell types. A significant radiographic shrinkage was observed after BAI therapy by the single, two and three drug infusions, being noted as 40.7 per cent, 61.8 per cent and 83.9 per cent, respectively. The effect on squamous cell carcinoma was more prominent than on other cell types. Upon microscopic examination of the resected specimens, significant histo-pathological effects were observed in 57.7 per cent of the patients who received single or two drug infusions, while the rate increased to as high as 92.2 per cent in the patients who received the three drug infusion. The histological effects of BAI therapy were also most marked in squamous cell carcinoma. It is of special interest that 5 of the 10 patients who received the three drug infusion of Carboquone (CQ) + Mitomycin C (MMC) + Nimustine-HCL (ACNU) for squamous cell carcinoma, showed complete disappearance of viable cancer cells at the tumor site; something which was never observed after the single and two drug infusions. It was therefore concluded that BAI therapy for advanced lung cancer should be reappraised through the modification of infusion methods.

Adenocarcinoma↗
PubMed1990

Thermally controlled laser irradiation of the myocardium with intraoperative ultrasound monitoring.

We used intraoperative ultrasonography (IOUS) to study the feasibility and safety of Nd:YAG laser irradiation of the myocardium in 26 canine left ventricular segments. During the laser irradiation process, the myocardial temperature was monitored and surface cooling was used. Afterward, intraoperative ultrasonographic scans, which enabled the evaluation of the irradiated lesions, were compared with cross sections made through the tissues. The total dose of laser energy ranged from 200 to 3,600 joules, and the estimated volume of irradiated lesions ranged from 76.8 to 2590 mm3. There were significant correlations between the laser discharge output (in joules [J]) and the irradiated lesion volume (P less than 0.001), and between the laser energy density (in J/mm2) and the depth of the lesions (P less than 0.01). Macroscopic examination of the cross sections of irradiated myocardium revealed that the lesions were well-demarcated, but not charred or perforated. Thus, we could obtain a satisfactorily large zone of laser photocoagulation without inducing tissue damage, if surface cooling was used and the myocardial temperature was monitored. IOUS was successful in visualizing and locating the irradiated lesions that were seen as hypoechoic, clearly outlined nodules. We submit that this study has established the technical feasibility and dose-response relationship of thermally controlled laser irradiation, and has demonstrated the usefulness of IOUS for the precise localization and monitoring of such laser treatment.

Animals↗
PubMed1990

Mediastinal spread of metastatic lymph nodes in bronchogenic carcinoma. Mediastinal nodal metastases in lung cancer.

The location, frequency, and spread of metastases to the mediastinal lymph nodes were examined in 124 patients with histologically proven N2 disease who underwent pulmonary resection and total lymph node resection. There were one-level metastases in 47 percent of cases, two-level metastases in 29 percent, three-level in 12 percent, and 12 percent had four or more levels of metastases. Nodal metastases to the lower mediastinum from upper lobe cancer were frequently observed as were metastases of lower lobe cancer to the upper mediastinum. The frequency of the latter was higher than that of the former. About one third of squamous cell carcinoma and adenocarcinoma in the right upper lobe produced nodal metastases in the lower mediastinum. In addition, there were often skip metastases to the nonregional parts of the mediastinum without regional nodal involvement in the mediastinum. From the results of the present study, it appears that extensive mediastinal dissection should be recommended in surgery for lung cancer irrespective of the location of the primary tumor.

Carcinoma, Bronchogenic↗
PubMed1990

[Surgical treatment of Wolff-Parkinson-White syndrome].

The paper presents the data on 365 operations to arrest the Wolff-Parkinson-White syndrome, which were performed in the period of 1973 to July 1989 in the Clinical Hospital, University of Kanazawa. The authors were the first to apply an endocardial access to remove Kent's bundle. They obtained the following results: later on 344 of 365 patients undergone surgery had no recurrent tachycardias. Incomplete abolition was observed in 21 patients, but relapses of tachycardias were absent. A total of 11 patients died within 1 to 32 days of postsurgery. The authors have noted that they achieved 100% positive results in the last series of 101 operations: there was no relapse of tachycardias, repeated operations, atrioventricular block and deaths. At present, the surgical technique for arresting the WPW syndrome has some advantage over drug therapy. The operation fully makes the patient recovered, while with conservative therapy he has to be on drugs during his life.

Adult↗
PubMed1990

[Surgical treatment of non-ischemic ventricular tachycardia].

The authors reviewed the results of 42 operations for non-ischemic ventricular tachycardias, tachycardia being arrested by laser ablation in 2 cases. Right and left ventricular tachycardias were seen in 26 and 14 patients, respectively. For diagnosis, preoperative electrophysiologic study, intraoperative epicardial mapping, and "delayed" potentials were used. In 38 of 40 patients who had undergone a direct operation, a positive result was obtained; in 31 patients, a complete disappearance without applying antiarrhythmics was observed. Four patients received drug therapy which proved to be ineffective before surgery. Two patients died after surgery due to recurrent tachycardia. Out of 38 survivals, 3 died of heart failure that was not caused by recurrent tachycardia.

Action Potentials↗
PubMed1990

[A successful surgical treatment of WPW syndrome associated with tricuspid atresia].

The occurrence of both tricuspid atresia and WPW syndrome is quite rare. To our knowledge, only two operated cases have been reported. In this report, a 8-year-old boy with this combination was reported. Tachycardia via the right side accessory pathway was for the first time pointed out after Kreutzer's operation. Epicardial mapping showed the earliest excitation at the right free wall. When fatty tissue around this area was removed by CUSA, a large cardiac vein appeared. By holding this vein with a forceps, the delta wave disappeared temporarily. ACP seemed to be present near this vein. Permanent disappearance of the delta wave was obtained after ligation and division. Four months after surgery, he is free from tachycardia attacks.

Child↗
PubMed1990

[Cryosurgical treatment of atrial tachyarrhythmia with atrial flutter].

Two cases of atrial tachyarrhythmias with atrial flutter requiring cryosurgical treatment are reported. In two cases, preoperative electrophysiological studies revealed supraventricular reentrant tachyarrhythmias during atrial flutter and showed enhanced conduction through the AV node that conducted atrial impulses rapidly to the ventricle. Based on intraoperative endocardial mapping, the earliest excitation site was localized along the AV node and His bundle during supraventricular tachyarrhythmias in one case. The cryosurgical treatment was administered at Koch's triangles and in one case additionally at coronary sinus. After the operation, supraventricular tachyarrhythmias were not inducible and no clinical recurrences have occurred. Normal atrioventricular conduction was preserved in two cases. We concluded that cryosurgical treatment is useful for the treatment of the atrial tachyarrhythmias.

Adult↗
PubMed1990

[Surgical treatment of ventricular tachycardia after radical correction of tetralogy of Fallot].

The patient was 21 year-old male with recurrent sustained VT following complete repair of tetralogy of Fallot. He underwent complete repair of tetralogy of Fallot at the age of 3. Eight years after the operation, he first noted episode of tachycardia. Sustained VT was first documented 15 years after operation, and he required direct-current cardioversion for this tachycardia. Because of life threatening arrhythmia he was transferred to our hospital for surgical management. Sustained VT was induced and found to originate from the inflow-septal and outflow area of right ventricle. During the operation only right outflow type tachycardia could be induced by programmed stimulation. Diastolic fractionated local electrical activity, which suggested a reentrant circuit, was recorded at the outflow epicardial area. The outflow muscle (2 X 2 cm) showing the earliest excitation during VT was excised with cryocoagulation at the outflow tract. The resected area was closed with a Gore-Tex patch using continuous sutures. Another cryocoagulation was applied to the inflow-septal area prophylactically. After surgery, a so-called non-clinical VT was inducible, however this VT could be prevented by antiarrhythmic drugs. No spontaneous episodes of VT have been postoperatively observed for 2 months.

Adult↗
PubMed1990

[Surgical treatment of Wolff-Parkinson-White syndrome].

The results of surgical treatment of 365 patients with the WPW syndrome are analysed. They underwent operation at the surgical department of the Kanazawa University Medical School in the period between 1973 and 1989. In 1969 T. Iva suggested an endocardial approach from the direction of the atrium for removal of the additional pathways, which the authors use at present also. The anomalies were congenital in 47 and acquired in 12 patients and were corrected in one stage during removal of the additional pathways. Multiple additional pathways were found in 33 patients. The additional pathways were completely removed in 33 patients. Paroxysms of tachycardia do not occur after the operation in 364 patients among the 365 who were operated on.

Adolescent↗
PubMed1990

[A new sock and snap electrode for epicardial mapping].

Simultaneous recording of epicardial activation from multiple sites during anti-arrhythmic surgery is essential to determine the location of the arrhythmic source. We formed a new sock from Presnet tubular dressing material with 87 snap electrodes. Bipolar recording sites, 1.0 mm in diameter and separated 1.5 mm, are constructed of gold and attached to steel wire directly at the male snap without button. This new Sock and Snap electrode was used to record in 7 patients; 5 of WPW syndrome and 2 of non-ischemic ventricular tachycardia. Satisfactory epicardial contact was obtained in all patients without any hemodynamic change. We could get a rapid display of epicardial mapping using a computer.

Adult↗
PubMed1989

Surgical management of tachyarrhythmias.

In this study of surgical procedures for various tachyarrhythmias, Wolff-Parkinson-White syndrome comprised most of the cases. An endocardial approach was used to ablate accessory pathways. Additional use of cryocoagulation after surgical incision of the atrium, previously routinely performed, is at present only done occasionally for septal accessory pathways. Ventricular tachycardia (VT) was the next most frequent condition. The surgical procedures for ischemic and nonischemic VTs are completely different, although both are based on the principle of complete electrophysiologic mapping. For ischemic VT, surgery consists of resection of the left ventricular aneurysm and excision or cryocoagulation of the endocardium, or both. For nonischemic VT, either excision of the entire thickness of the myocardium (2.0 X 2.5 cm on average) at the earliest excitation site of the right ventricle and cryocoagulation of the area of delayed potential or only incision and cyrocoagulation of the left ventricle were performed to avoid reduction of the left ventricular cavity. Ectopic atrial tachycardia was cured by excision of the earliest excitation site without use of a heart-lung machine, when the focus was located in the atrial free wall. Other successful treatments were of reentrant atrial tachycardia by cryocoagulation, atrial flutter by cryocoagulation of impulse pathways at the coronary sinus and around the atrioventricular node, and a new surgery for atrial fibrillation and flutter, which retained sinus rhythm. Johnson's procedure was used for surgical ablation of atrioventricular nodal reentrant tachycardia.

Adolescent↗
PubMed1989

[Stress analysis of post-reconstructed teeth with dead space at the apex of the post].

Reconstruction of the crowns of non-vital teeth with posts can be a very useful technique. However, there are many cases where the length of the posts are insufficient, resulting in a poor fit and dead space at the apex of the post. The purpose of this study was to compare the post length to the depth of the post preparation using parallel X-ray films of 31 teeth (incisors, canines and premolars) and to locate the dead space at the apex of the post. In addition, stress analysis of the post-reconstructed upper central incisor models having five types of posts with dead space at the apex and two levels of supporting conditions were calculated using the finite element method. The results obtained were as follows: 1. From the roentogenographic survey, the depth of the post preparations averaged two thirds of the remaining root length, and one half the length of the root in bone. However, lengths of the posts were on the average 20% shorter than the depth of the post preparation. 2. As the dead space increased and supporting levels diminished, stresses of post-reconstructed teeth were found to increase gradually and to concentrate in the remaining dentin near the apex of the post.

Crowns↗
PubMed1989

[Skeletal muscle ventricle used for right ventricle assistance].

There are a number of advantages in using an electrically stimulated autogenous skeletal muscle to construct an auxiliary ventricle to assist a heart. The purpose of this study was to determine the feasibility of biological right ventricular assistance using long-term electrically stimulated skeletal muscle grafts. In fourteen dogs, the latissimus dorsi muscles and the right thoracodorsal nerves were exposed and unipolar pulse generator was implanted. The initial rate of 70 cycle/min. was increased to a rate of 100 cycle/min. Six or 12 months later, the latissimus dorsi was wrapped around a latex pouch equipped with inflow and outflow valved conduit (skeletal muscle ventricles; SMVs). The SMVs were connected to main pulmonary artery and right atrium. These SMVs were stimulated 20 Hz for 200 msec at a fixed rate of 90 cycle/min, the hemodynamic changes with or without skeletal muscle ventricular assistance (SMVA) were measured. In as animals the circulation failed after total right ventricular bypass without SMVA. But the SMVA increased aortic blood pressure, aortic blood flow, left atrial pressure and peak pulmonary pressure significantly. There was a linear correlation between central venous pressure and skeletal muscle ventricular assist flow. Histologic studies showed the conditioned muscles had a greater percentage of slow-twitch, fatigue resistant fibers on ATPase stain. These results suggested the long-term electrical conditioning skeletal muscle could be possible to use SMVs in humans to provide support in children with some types of congenital heart disease.

Animals↗