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J Oba

Publications and source records attributed to J Oba.

17 recordsLinked to original sources
PubMed1997

Adrenergic neurotransmitters and calcium ionophore-induced situs inversus viscerum in Xenopus laevis embryos.

Xenopus laevis embryos at the blastula-early tail bud stage were exposed to norepinephrine or octopamine dissolved in culture saline until they reached the larval stage. The left-right asymmetry of the heart and gut was then examined. We found that these adrenergic neurotransmitters induced situs inversus in the heart and/or gut in up to 35% of tested neurula embryos. Norepinephrine-induced situs inversus was blocked by the alpha-1 adrenergic antagonist prazosin. Furthermore, A23187, a calcium ionophore, also increased the incidence of situs inversus up to 54% when late-neurula embryos were exposed to the solution. A23187 treatment initiated before neural groove formation was less effective. The incidence of situs inversus induced by these reagents decreased towards the control level (2.2%, 25 untreated embryos out of 1127 embryos in total) in embryos past the stage of neural tube closure. In the present experiments we obtained 22 gut-only situs inversus embryos having an inverted gut and a normal heart. In contrast, such embryos were not observed among the 1127 untreated embryos. An adrenergic signal mediated by an increase in intracellular free calcium may be involved in the asymmetrical visceral morphogenesis of Xenopus embryos.

Adrenergic alpha-Agonists↗
PubMed1997

[Surgical results of postinfarction ventricular septal perforation: operative planning using "endocardial patch repair with infarct exclusion"].

Between 1983 and 1996, twenty-two consecutive patients underwent surgical repair for postinfarction ventricular perforation (VSP). Overall hospital mortality was 31.8% in the reviewed group. 15 patients were operated upon within two weeks of onset of VSP and hospital mortality was 27.3% in this group. The earlier operation might provide more favorable results in the surgery of VSP. When the preoperative coronary angiography revealed multivessel disease, concomitant myocardial revascularization was performed. In recent 2 cases, we employed the new technique introduced by Komeda and David for the reconstruction of the left ventricule using a single pericardial patch. We found this new technique had many advantages over traditional "Daggett's method". Better operative results could be expected with this technique.

Aged↗
PubMed1995

Alterations in coagulation and fibrinolysis after surgery for aortic aneurysm.

We investigated the alterations in the coagulation and fibrinolysis systems after aortic aneurysm surgery under cardiopulmonary bypass (CPB) while using newly developed "molecular markers". Fibrinogen and antithrombin III (AT-III) decreased after surgery but returned to normal values within three days. The thrombin-antithrombin III complex (TAT) and plasmin-alpha-2-plasmin inhibitor complex (PIC) both showed increased values even preoperatively, which indicated that coagulation and fibrinolysis were activated in some patients with an aortic aneurysm. Both markers maintained a high level for at least 14 days after surgery. The fibrin degradation product (FDP) also showed an increased value before and after surgery. These results apparently showed that coagulation/fibrinolysis had already been activated in some patients and maintained such a state for at least 14 days after surgery. The relation of activated system and postoperative organ dysfunction as well as the means to suppress such activation are also discussed.

Aged↗
PubMed1995

Preoperative disseminated intravascular coagulation (DIC) associated with aortic aneurysm--does it need to be corrected before surgery?

Disseminated intravascular coagulation (DIC) is one of the complications accompanying aortic aneurysm. We herein report four patients with aortic aneurysm who had DIC preoperatively. In all four cases, DIC was corrected immediately after surgery; however, in two cases, DIC could not be corrected preoperatively. This prompted us to reconsider the importance of correcting DIC before surgery. Of the four cases reported in this paper, DIC existed even at the time of surgery in two cases, in spite of meticulous treatment with heparin and/or protease inhibitor; however, the DIC could be removed postoperatively even in these two cases. Surgeons should not waste time with intensive DIC treatment preoperatively. If the DIC cannot be corrected within more than 2 weeks of meticulous treatment, surgeons should then perform surgery on the patient. In addition, it is also essential to ensure that the DIC is due to the aneurysm itself and that no other disease processes have been overlooked.

Aged↗
PubMed1995

In vivo assessment of nonlinear myocardial deformation using finite element analysis and three-dimensional echocardiographic reconstruction.

In vitro data have shown that the myocardium exhibits nonlinear passive stress-strain relationship and a non-linear pressure-volume relationship. A finite element (FE) analysis and optimization algorithm was used on three-dimensional reconstructed left ventricular (LV) geometry using echocardiographic images, along with hemodynamic measurements, in seven closed-chest dogs to show a nonlinear stress-strain relationship in vivo. Our analysis included the computation of Poisson's ratio from the measured volumetric strain of the myocardium and a simulated pericardial pressure load ("equivalent pericardial pressure") applied to the epicardial surface of the reconstructed LV. LV geometry was reconstructed in three or four incremental time steps in diastasis and the myocardium was assumed to be homogeneous, isotropic, and linearly elastic during these short intervals in this initial study. Simultaneous LV chamber pressure and equivalent pericardial pressure were incorporated into the algorithm to predict actual LV expansion. Computations were performed iteratively at each interval to compute the optimized elastic modulus. By performing the FE analysis and optimization at each interval (a step-wise linear analysis approach), a linear relationship between the myocardial elastic modulus and LV chamber pressure was derived (r = .87 to .98). Such a linear relationship is equivalent to an exponential myocardial stress-strain relationship in vivo. Detailed measurement of nonhomogeneous regional deformation are becoming possible with the advent of sophisticated imaging techniques. The methodology described in this study, with appropriate modifications in the FE analysis and optimization algorithms, can be applied to assess the complex three-dimensional pressure-deformation characteristics in vivo.

Algorithms↗
PubMed1994

[Clinical results of selective cerebral perfusion during reconstruction of the transverse aortic arch].

Selective cerebral perfusion (SPC) has become a reliable method for brain protection during reconstruction of the transverse aortic arch. However, arterial cannulation technique for the branches of the aortic arch varies among groups, and the necessity of perfusion for the left subclavian artery is controversial. To avoid atheroembolism to the brain and malperfusion of the vertebral arterial system, we carefully selected the arterial cannulation technique according to the result of preoperative ultrasonographic and angiographic evaluation of the branches of the aortic arch, and decided the necessity of perfusion for the left subclavian artery according to the dominance of the two vertebral arteries and the result of pressure monitoring of all three branches. In this report, we analyzed our clinical results of selective cerebral perfusion on 22 consecutive patients, which was performed between April 1992 and December 1993. There were 14 atherosclerotic aneurysms and 8 aortic dissections. The flow rate for SCP was controlled by a single blood pump separate from that for systemic perfusion, with the mean value being 13.1 ml/kg/min. Mean of minimum left superficial temporal arterial pressure was 51 mmHg, mean duration of SCP was 134 minutes, and mean of the lowest esophageal temperature was 17.9 degrees C. Blood pH was regulated with alpha-stat strategy. Arterial cannula for SCP was inserted directly into the vessels through a stab wound in most cases. In three of four patients in whom dissection extended to the branches, a balloon catheter was introduced through the lumen of the aortic arch.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Hyperbaric oxygen therapy in the Hokkaido University Hospital].

We surveyed the hyperbaric oxygen therapy during the past seven years in the Hokkaido University Hospital. The mean number of patients was 27 per year. The average number of the therapy was 328 per year. There were neither complications nor accidents attributable to the hyperbaric oxygen therapy. Three representative diseased states hypoxic brain damage, sudden deafness and occlusion of retinal arteries, showed remarkable recovery by this therapeutic modality. A safety standard has been revised in 1991. We have been operating the hyperbaric oxygen therapy according to the revised standard. The inter-departmental approach in this therapeutic modality is mandatory in order to achieve effective outcome.

Female↗
PubMed1994

[A case of dissecting aortic aneurysm and presence of anti-Jr(a) antibody].

A 66-year-old woman was diagnosed as a DeBakey type II dissecting aortic aneurysm with angiography and CT. Antibody screening revealed circulating anti-Jr(a) antibody. Preoperatively, erythropoietin was administered twice a week. Over 24 days, a total of 1200 ml of her blood was removed and stored for autologous transfusion. The dissecting ascending aorta was replaced with the aid of cardiopulmonary bypass. The post operative course was uneventful. By using erythropoietin, pre-donated autologous blood, cell saver, aprotinin and transfusion of fresh autologous blood, it was possible to perform cardiovascular surgery on this patient who had an abnormal antibody. This patient is the first case of repair or dissecting aortic aneurysm with anti-Jr(a) antibody in Japan.

Aged↗
PubMed1994

[Acute dissection of the interatrial septum after re-replacement of the mitral valve--a case report].

A 64-year-old man who had received a Carpentier-Edward mitral valve replacement seven years earlier was seen with dyspnea on exertion. After re-replacement of the mitral valve with SJM prosthesis, the patient developed acute left-sided heart failure on the third postoperative day. Transesophageal echocardiography revealed abnormal lumen posterior to the left atrium with regurgitant flow from the left ventricle. Right and left atriotomy revealed dissection of the interatrial septum and after removal of the prosthesis, communication between the left ventricle and the dissected lumen was recognized. After closing the communicating orifice, SJM prosthesis was again sutured on the mitral annulus with sub-annular pledgets to reinforce the annular attachment. Excessive debridement of the annular tissue was thought to be a causative factor to develop the dissection of the interatrial septum after mitral valve replacement.

Acute Disease↗
PubMed1993

Optimal pleurodesis: a comparison study.

With the resurgence of thoracoscopy, there is renewed interest in less invasive methods of pleurodesis. We wished to compare in an animal model a variety of methods suggested in reports. The purpose of the study was to rank the effectiveness of each procedure against the standard mechanical pleurodesis. Twenty-five mongrel dogs (weight, 25 to 35 kg) underwent bilateral thoracotomy. Each animal was randomly assigned to receive two of the following methods of pleurodesis: tetracycline, talc, mechanical abrasion, neodymium: yttrium-aluminum garnet (Nd:YAG) laser (Hereus Inc, E. Rutherford, NJ) photocoagulation, and argon beam coagulator (ABC) (Beacon Lab, Bloomfield, CO) electrocoagulation of the parietal pleura. At evaluation at 30 +/- 2 days, the efficacy of pleurodesis was graded on a scale of 0 to 4, with 0 representing a complete absence of pleural symphysis and 4 the adhesion of more than one lobe to both the chest wall and mediastinum. Mean grade and standard deviation of each method were: talc, 3.0 +/- 0.67; mechanical, 3.0 +/- 0.82; tetracycline, 2.3 +/- 1.4; ABC, 1.5 +/- 0.97; and Nd:YAG laser, 0.7 +/- 0.95. Both the talc and mechanical methods were superior to either the Nd:YAG laser or the ABC (p < 0.01). In this study, neither the Nd:YAG laser nor the ABC proved efficacious in producing pleurodesis. Talc poudrage is the only method of pleural symphysis comparable with mechanical abrasion.

Animals↗
PubMed1993

[Effect of percutaneous cardiopulmonary support (PCPS) on cardiac function with special reference to the significance of left ventricular venting].

Direct effects of percutaneous cardiopulmonary support (PCPS) on cardiac function were evaluated. Also, the efficacy of left ventricular venting to unload the heart was assessed. Eleven open-chested dogs were placed on PCPS with the flow equal to the baseline cardiac output for 30 minutes. Six out of eleven had left ventricle vented (VENT) by means of venting tube which was indwelt in the left ventricular cavity, while other five did not (NONVENT). Hemodynamic indices were obtained before and on PCPS. Measured, derived or calculated variables included heart rate (HR), mean aortic pressure (mean AOP), left ventricular end-diastolic pressure (LVEDP), peak left ventricular pressure (peak LVP), peak LVdp/dt, rate-pressure product (RPP, HR x peak LVP) and aortic-coronary sinus oxygen content difference (ACsO2D). There was no difference in any variables between the groups at baseline. On PCPS, in the VENT group, HR increased 27% from baseline (p < 0.05), while mean AOP did not change. All other variables showed significant (p < 0.05) reduction in VENT. Percent change from baseline value in VENT was: -24% for LVEDP, -47% for peak LVP, -41% for peak LVdp/dt, -32% for RPP and -42% for ACsO2D. No variable differed significantly from baseline in the NONVENT group on PCPS. The author concluded that left ventricular venting favorably alters the loading and contractile profile of the heart on PCPS without affecting systemic circulation.

Animals↗
PubMed1993

[Surgical aspects of automatic implantable cardioverter defibrillator (AICD) in patients with life-threatening ventricular tachyarrhythmias].

Implantations of automatic implantable cardioverter defibrillator were performed in five patients with life-threatening ventricular tachyarrhythmias. Preoperative diagnoses of arrhythmias were sustained ventricular tachycardia (VT) in two cases, ventricular fibrillation (VF) in two cases and sustained VT+VF in one case. Four of five cases had basic diseases respectively (broad anterior myocardial infarction, dilated cardiomyopathy, arrhythmogenic right ventricular dysplasia, hypertrophic cardiomyopathy), and the other case was idiopathic. Preoperative CTR were 43-65% (mean 57.4%) and left ventricular ejection fraction were 26-76% (mean 51.2%). Implantation of AICD was indicated for patients who survived circulatory arrest or life-threatening VT. Median sternotomy (3) or left antero-lateral thoracotomy (2) were performed for implantation of large-small patch electrodes for defibrillation. AICD generators were implanted in the pocket under abdominal rectal muscle in all cases. Postoperatively myocardial insufficiency, pericarditis, pleuritis occurred in three cases respectively. In the follow-up periods (2-25 months, mean 13 months), AICD worked effectively in two patients with spontaneous VT (6 months, 1 year after operation) and no cardiac death was experienced. We concluded that AICD system is effective for the life-threatening ventricular tachyarrhythmias, although the further estimation in longer follow-up periods are warranted.

Adult↗
PubMed1992

Successful extended lung preservation with UW solution.

Maximum preservation times of 4-6 hr continue to plague lung transplantation. The high-potassium colloid University of Wisconsin solution (UWS) has proved superior to the crystalloid modified Eurocollins' solution (ECS) for preservation of the liver, kidney, and pancreas. The purpose of this study was to compare UWS and ECS for extended lung preservation using a technique of combined pulmonary and bronchial artery perfusion. Simultaneous pulmonary artery and bronchial artery (via a closed aortic segment) perfusion was employed to harvest the lungs of ten mongrel dogs (wt 25-35 kg) using either UWS (n = 5) or ECS (n = 5) preservation solutions. Following 17 hr of cold (4 degrees C) pulmoplegic storage, the lungs were placed in an isolated perfused working lung (IPWL) apparatus. Seven freshly harvested lungs served as a control group (CON). Lung aerodynamics and gas exchange were evaluated at standard intervals until failure of the lung on the IPWL apparatus. Time until failure (mean +/- SEM) for each group was: CON = 209 +/- 14 min; UWS = 227 +/- 26 min; and ECS = 123 +/- 29 min. Only one of the ECS lungs lasted longer than 90 min. UWS-preserved lungs displayed a gas exchange efficiency equal to the CON group and better than that in the ECS-preserved lungs (lower A-aDO2, lower intrapulmonary shunt), suggesting better protection of the alveolar capillary membrane. Although the UWS lungs were initially less compliant than the ECS lungs, at no time was there a significant difference in the total work of respiration between the two groups. We conclude that UWS provides superior protection of the alveolar capillary membrane. The aerodynamic disadvantages of UWS preservation did not effect lung survival or total work of respiration.

Adenosine↗
PubMed1992

Short-term and long-term results of experimental wrapping techniques for bronchial anastomosis.

Major complications of bronchial anastomoses for either transplantation or sleeve resection include early leak, fistula formation, granulation tissue, and stenosis. To evaluate the impact of technique on these complications, we designed a nonimmunocompromised canine model with a totally ischemic bronchial segment. We wished to discover the prevalence of early and late complications of a telescoping anastomosis and if wrapping techniques modify them. We autotransplanted 25 mm of left main-stem bronchus by telescoping 1 mm of proximal into distal bronchus sutured with interrupted 4-0 polyglactin sutures. The animals were divided into four groups: no wrap; omental pedicle wrap; detached-free omental wrap; and Gelfoam sponge soaked in porcine omental extract. Weekly bronchoscopic studies assessed airway patency. After the animals were put to death at 70 days, the luminal areas of the proximal anastomoses were compared with the origin of the left main bronchus. No air leak, bronchial disruption, or infection occurred in any group at any time. Luminal narrowing occurred in all four groups but was most pronounced in the three groups in which wrapping techniques were used. We conclude that wrapping of a telescoped anastomosis is not necessary to prevent early complications. However, no method completely eliminates stenosis. Further experiments should determine the effects of immunomodulation in this model.

Anastomosis, Surgical↗
PubMed1991

Endoscopic thoracic sympathectomy: evaluation of pulsatile laser, non-pulsatile laser, and radiofrequency-generated thermocoagulation.

We describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space-anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2 laser (14 W, CW, 2 mm spot size), Nd:YAG laser (88 W, CW, 3 mm spot size), and radiofrequency-generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1-T2 nerve roots by excimer laser required 83 +/1 1 Joules over an exposure period of 118 seconds. Ablation by CO2 and Nd:YAG laser required 153 +/- 13 Joules and 554 +/- 47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810 +/- 50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2 laser lesions were narrower in configuration compared to RF and Nd:YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2 (1.5 mm) and RF (1.3 mm), but deeper for Nd:YAG (3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗