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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 1,153 records · Page 64Linked to original sources
PubMed1991

[Experimental studies on argon laser angioplasty].

To evaluate the safety and efficacy of recanalization of the occlusive arterial diseases by Argon laser, we investigated the effects of the laser irradiation using bare-ended probe (BEP) and metal-tip probe (MTP) on human cadaveric aorta and canine femoral arteries with thrombotic occlusion. In case of the BEP, the incidence of perforation of the arterial wall was high as compared with the MTP. However, laser angioplasty with angioscopic guidance could reduce the perforation rate, and made it possible to observe the new channel recanalized by laser. In case of the MTP, it was confirmed that the smaller MTP showed higher tip temperature and was more effective on plaques under the same laser energy. Optimal laser energy for single ablation was from 15J to 25J in case of 2.0mm tip and from 30J to 40J in case of 2.5mm tip. Application of the MTP equipped with thermal feedback control system could avoid the excessive thermal damage in comparison with the conventional MTP. It was considered that optimal temperature of the MTP equipped with thermal feedback control system ranged between 200 degrees C and 300 degrees C. It was concluded that laser angioplasty would be a useful treatment for the occlusive diseases of the peripheral arteries.

Angiography↗
PubMed1991

[Left ventricular failure following valve replacement surgery in patients with mitral stenosis--its genesis, prognosis, and the method for the preoperative prediction].

To detect the genesis and the prognosis of left ventricular failure (LVF) following the valve replacement surgery to mitral stenosis (MS), preoperative values and postoperative courses were assessed in 90 patients with MS. The criteria for LVF were as follows: postoperative severe left ventricular (LV) dysfunction which required intra-aortic balloon pumping (IABP) support with large doses of catecholamine. Among these 90 patients, LVF had occurred in 13 patients, of which 6 had a definite cause of LVF (group A), but the other 7 patients failed to LVF despite uneventful operation (group B). Comparing the pre- and postoperative values in these two groups, the duration of IABP support was much longer in group A, and the weaning rate from IABP was also poor in this group. Long-term survival was achieved only by one patient in group A, whereas 5 out of 6 patients of group B survived long-term postoperatively. Evaluating the preoperative LV function in group B patients, depressed LV function [%fractional shortening (%FS) less than or equal to 27%] was observed in 5 patients. Among these 5 patients, three had low cardiac output; in other two, preoperative %FS was severely depressed. In such patients, the responses to preoperative dobutamine administration tests were poor, and the values of %fibrosis of the LV myocardium, which was demonstrated by intraoperative biopsy, was greater in them. In conclusion, the causes of postoperative LVF following the mitral valve replacement to MS was divided into two categories: one due to perioperative complication and another due to preoperatively impaired LV function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Successful surgical treatment of primary chylopericardium in infant--a usefulness of intraoperative thoracic ductgraphy].

Asymptomatic eight-year old girl was admitted to our surgical department from ophthalmology complaining enlarged heart size at the routine check before operation of strabismus. By pericardiocentesis it was confirmed that pericardial effusion was chyle biochemically and microscopically. In spite of several medical trials (i.e. diuretics, pericardial drainage, complete starvation with parenteral nutrition), copious amount of chyle discharge, measured 180 ml per day, couldn't be controlled. Mediastinal mass lesion and thoracic duct anomaly were excluded by both thoracic CT and lymphangiography, and primary chylopericardium without thoracic duct anomalies was suspected preoperatively. The diagnosis of primary pericardium was confirmed by intraoperative thoracic ductography which visualized thoracic duct and it's tributaries more clear than that of preoperative lymphangiography. Low thoracic duct ligation with resection of duct 55 mm in length and fenestration of the pericardium through right thoracotomy was successfully carried out. She was discharged on 8th day after surgery without any problems. She is doing well 7 months postoperation after discharge with reduced heart size and returns to normal activity. We concluded that intraoperative thoracic ductography had some advantages in terms of more clear visualization of thoracic duct anastomosis, precise diagnosis of etiology and choice of surgical options.

Child↗
PubMed1991

[Comparison of noninvasive techniques in evaluation of the Björk-Shiley and the St. Jude Medical valve prostheses in mitral position].

Pressure gradients and left ventricular function were assessed by Doppler echocardiography in 50 patients with Björk-Shiley mitral valve and 50 patients with St. Jude Medical valve prosthesis. There was correlation between pressure gradient and valve size, and between effective valve orifice area and valve size for St. Jude Medical valve. These correlations were not found in Björk-Shiley valve. Clinical improvement and cardiac function were quite satisfactory in 20 patients with Björk-Shiley valve and in 32 patients with St. Jude Medical valve whose pressure gradients were less than 10 mmHg. Twenty eight of 50 patients with Björk-Shiley valve and 42 of 50 patients with St. Jude Medical valve showed good response to the exercise test. Eight patients underwent reoperation because of unacceptably high gradient caused by thrombus and pannus formation. The patients who show high pressure gradient across the valve prosthesis should be followed up cautiously.

Cardiac Volume↗
PubMed1991

[A case of successful treatment of aneurysms of the suture line following Bentall's operation].

A 33-year-old male who had received Bentall's operation 10 years ago was admitted to our hospital with severe chest pain. The pseudoaneurysm at the right coronary ostium was observed on angiography and CT scan. He underwent the repair of the anastomosis between the graft and the right coronary ostium under extracorporeal circulation. Although he was discharged from the hospital asymptomatically, he was again admitted to our hospital with severe chest pain and back pain 4 months after re-operation. Aneurysmal formation of the ascending aorta due to blood leakage from the distal anastomotic suture line was observed and the graft was compressed by hematoma on angiography and CT scan. He underwent re-operation of the distal anastomosis of the graft, and could be discharged from the hospital uneventfully.

Adult↗
PubMed1991

[Experimental studies on coronary angioplasty by argon laser].

To establish the method of coronary angioplasty by Argon laser, the optimal condition of laser ablation was precisely investigated using bare-ended probe (BEP) and metal tip probe (MTP) of 1.5 mm in diameter. At first, the relationship between laser energy and the depth of the crater on human cadaveric arteries created by laser ablation was examined. Repeated ablation was found to be the most favorite condition and each laser ablation should be restricted between 1 and 5 watts in output and 1 and 2 seconds in ablation time using BEP, and between 5 and 10 watts at 2 seconds using MTP. Secondly, laser ablation was carried out in the canine coronary arteries under beating heart. In this experiment, perforations were seen in some cases using BEP, but no perforation and coronary spasm was observed using MTP. However, temporary drop in distal coronary artery pressure was observed when the size of metal tip was too large for the diameter of the vessel, suggesting vascular thermal constriction. Intraluminal laser thermal ablation using MTP in canine model for establishing the favorite relationship between the size of metal tip and the diameter of the vessel disclosed that MTP/vessel diameter ratio should be 0.7 or less to avoid the vascular thermal constriction. Finally, percutaneous transluminal laser thermal ablations in the coronary arteries were carried out in the living dogs under the condition described above. No perforation, severe arrhythmia, coronary spasm or stenosis were found in this experiment, and it could be concluded that laser angioplasty by Argon is applicable to the treatment of coronary artery disease clinically.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Aortocoronary bypass for coronary ostial stenosis following aortic valve replacement: a report of successfully treated case].

A 62-year-old man underwent aortic valve replacement with a Medtronic-Hall valve (21 mm) for aortic stenosis and regurgitation with normal coronary arteries. An intermittent selective coronary perfusion with metal tip cannula was employed for both the coronary arteries. Postoperative course was uneventful. However, he began to complain of chest pain six months later. Cardiac catheterization and coronary arteriography revealed a normally functioning valve with 75% stenosis at the main trunk of the left coronary artery. Coronary bypass grafting using a saphenous vein was successfully performed to the left anterior descending coronary artery and the circumflex of the coronary artery. Whenever this fatal complication of the coronary ostial stenosis is recognized, earlier coronary revascularization should be recommended to save the severely ill patient.

Aortic Valve↗
PubMed1991

[A case of localized pleural mesothelioma].

A case of localized pleural mesothelioma is reported. A 49-year-old man was operated for coin lesion detected on routine chest X-ray. A tumor arose from the visceral pleura of right lower lobe and was pedunculated. Size of the tumor was 4 x 3 x 3 cm. Cut surface of the tumor was solid and yellowish white. Pathological diagnosis was fibrous type of the pleural mesothelioma. The patient is well and has no sign of recurrence for three years. There are 123 cases of localized pleural mesothelioma including our case in Japan. Five in 78 cases which was diagnosed to be benign histologically at operation, had recurrence later. It is important to follow up strictly for long term.

Humans↗
PubMed1991

[Surgical treatment for the association of cardiovascular disease and cholelithiasis].

Six cases of the association of cardiovascular disease and cholelithiasis were treated in our surgical ward. Simultaneous operation was carried out for four of them, and two-stage operation was performed in the remaining two cases. As the time of the simultaneous operation, reconstruction of the abdominal aorta and cardiac surgery was firstly done, and cholecystectomy was secondly performed after closing the retroperitoneum or the median sternotomy. All of these cases were discharged from hospital uneventful. In conclusion, cholecystectomy could be safely performed at the same time of the aortic reconstruction and cardiac surgery without any high risk for the patients.

Adult↗
PubMed1990

Epidermal growth factor and transforming growth factor alpha induce ascitic fluid in mice.

Recent studies have suggested that pleural or peritoneal effusion associated with metastatic tumors is induced by some mediators produced by the tumor cells. We studied the ability of well-characterized peptide growth factors to produce ascites in mice. Peritoneal administration of epidermal growth factor (EGF, 10 to 40 micrograms/mouse/wk) or transforming growth factor alpha (TGF-alpha, 10 to 40 micrograms/mouse/wk) via osmotic minipumps resulted in formation of bloody ascites. The amount of ascites produced was dependent on the dose of growth factors. Vehicle alone or insulin-like growth factor I (40 micrograms/mouse/wk) was without effect. Indomethacin, a blocker of prostaglandin synthesis, significantly reduced the ascites accumulation induced by EGF, suggesting that prostaglandins are involved in ascites formation induced by EGF. Dexamethasone was also effective in attenuating the effect of EGF. Thus, it is possible that peritoneal effusion associated with disseminated tumors is, at least in part, due to EGF-like materials (most likely TGF-alpha) produced by tumor cells. The mechanism by which these peptides induce bloody ascites is not known for certain, but it may be due to the reported activity for neovascularization or increased vascular permeability.

Animals↗
PubMed1990

Effect of dipyridamole at the usual oral dose on exercise-induced myocardial ischemia in stable angina pectoris.

A randomized, double-blind, placebo-controlled study was performed to investigate the effect of dipyridamole at a usual oral dose of 150 mg/day on 18 patients with angina pectoris and positive treadmill exercise electrocardiography. After their angina pectoris was stabilized in phase 1, the patients were randomly assigned to sequence group A or B. Group A received a placebo 3 times daily in phase 2 and then 50 mg of dipyridamole 3 times daily in phase 3. Group B received the treatment in the reverse order. The degree of ST depression and the threshold for angina pectoris in treadmill exercise electrocardiography, which was performed on the last days of phases 2 and 3, were compared. The mean duration of exercise was 5 minutes and 23 seconds during dipyridamole and 5 minutes and 13 seconds during placebo administration, with no significant difference. Dipyridamole caused an aggravating effect on the ST change (earlier appearance of ST depression and/or deeper total sum of ST depression at the end of the exercise) in 3 patients, a salutary effect in 5 and no effect in 10. Dipyridamole decreased the threshold for angina pectoris in 5 patients, increased it in 6 and did not change it in 7. To summarize, dipyridamole showed adverse effects (aggravative effects on the ST change and/or on the threshold for angina pectoris) in 6 patients, beneficial effects in 8 and no effect in 4. A usual oral dose of dipyridamole induced myocardial ischemia during exercise in some patients while it improved it in a similar number of patients.

Administration, Oral↗
PubMed1990

Regulatory system of guinea-pig complement C3b: two factor I-cofactor proteins on guinea-pig peritoneal granulocytes.

Complement factor I is a plasma protease serving for proteolytic inactivation of C3b together with its cofactor. We have identified two factor I-cofactor activities in solubilized extracts of guinea-pig peritoneal granulocytes using guinea-pig factor I (Igp) and fluorescent-labeled methylamine-treated guinea-pig C3 (f-C3(MA)gp). One of these eluted from a chromatofocusing column between pH 7.6-7.1, and the other at about pH 5.7. These two cofactor fractions both interacted with Igp and, to a lesser degree, with human factor I (Ihu) on C3(MA)gp cleaving it into an inactive C3bi analogue, but did not cleave methylamine-treated human C3 (C3(MA)hu) together with Igp or Ihu. These factors are therefore species specific. The neutral and acidic fractions with cofactor activity contained C3(MA)gp-binding proteins with a doublet of 55 kDa and 42 kDa, and a singlet of 160 kDa, respectively, on SDS-PAGE. These proteins may be membrane cofactor protein (MCP) and C3b/C4b receptor (CR1) of guinea-pigs.

Animals↗
PubMed1990

The mechanism of carbohydrate-mediated complement activation by the serum mannan-binding protein.

Serum mannan-binding protein (S-MBP), a lectin specific for mannose and N-acetylglucosamine, was documented to activate complement through the classical pathway. In this study, we examined the mechanism that initiates this activation. By a passive hemolysis test using sheep erythrocytes coated with yeast mannan, the activation of complement by human S-MBP was shown to proceed in the absence of C1q. The following binding studies using 125I-labeled C1r2s2 and C1s indicated that the activated form of C1r2s2 bound to S-MBP located on the surface of the cells with high affinity. The binding of C1s to the cell-bound S-MBP require the presence of C1r, suggesting that C1r2s2 binds to S-MBP through C1r. The activation of C1s from a proenzyme to a protease was mediated by cell-bound S-MBP in the presence of C1r and the activated protease remained associated with the cells and was not released into the medium. The activation of complement with S-MBP was a solid phase event and did not proceed in a fluid phase. On the basis of these results, it was concluded that S-MBP is responsible for the initiation of carbohydrate-mediated complement activation as C1q does in immune complex-mediated complement activation.

Animals↗
PubMed1990

Insulin-like growth factor I and transforming growth factor alpha as autocrine growth factors in human pancreatic cancer cell growth.

The roles of insulin-like growth factor I (IGF-I) and transforming growth factor alpha (TGF-alpha) as autocrine factors in the proliferation of MIA-PaCa 2 cells (human pancreatic cancer cells, PC cells) were investigated. Furthermore, the mechanism(s) of inhibition of PC cell growth by a phorbol ester in relation to these two kinds of growth factor was also studied. PC cells grew autonomously when Dulbecco's modified essential medium supplemented with 4% fetal calf serum was changed to serum-free medium (0.3% bovine serum albumin-Dulbecco's modified essential medium). In addition, serum-free conditioned medium from PC cells dialyzed against fresh Dulbecco's modified essential medium had a stimulatory action on the growth of the same kind of cells when compared with that induced by nonconditioned medium. These observations suggest that a factor(s) produced and released by PC cells stimulates their own growth. Analysis of conditioned medium from PC cells revealed the presence of immunoreactive (IR)-IGF-I and IR-TGF-alpha. The molecular size of IR-IGF-I was similar to that of authentic IGF-I. On the other hand, IR-TGF-alpha was present as multiple forms when analyzed using gel chromatography. Authentic IGF-I and TGF-alpha added to culture medium stimulated PC cell growth by 1.45- and 1.5-fold above control value, respectively. A monoclonal antibody to IGF-I receptor was able to inhibit PC cell growth. PC cell proliferation was markedly inhibited by 12-O-tetradecanoyl-13-acetate (greater than 0.16 nm), whereas cell growth of human fibroblasts was stimulated by it. 12-O-Tetradecanoyl-phorbol-13-acetate also reduced the binding of 125I-TGF-alpha, but not 125I-IGF-I, to PC cells. Decrease in TGF-alpha binding was mainly due to the reduced affinity of receptors to the ligand. These results suggest that IGF-I and TGF-alpha are involved in PC cell proliferation as autocrine factors. Further, the inhibition of PC cell growth by phorbol ester could be, at least partly, due to the decreased binding of TGF-alpha to the cells.

Adult↗
PubMed1990

Successful treatment of refractory anemia with high-dose methylprednisolone.

Five patients with refractory anemia were treated with high-dose methylprednisolone. An immediate and long-lasting hematological improvement without serious side effects was achieved in two of the patients, although chromosomal abnormalities persisted in both. The clinical course and laboratory data of these two patients are described. Restoration of normal hematopoiesis was achieved regardless of the enhancement of colony formation of granulocyte progenitor cells by the simultaneous addition of hydrocortisone in vitro. The same treatment was given to six patients who had refractory anemia with an excess of myeloblasts (RAEB), but no improvement was observed in any of these patients. It appears that high-dose methylprednisolone can be valuable in the treatment of refractory anemia, but is not useful for RAEB.

Adult↗
PubMed1990

Müller cells in detached human retina express glial fibrillary acidic protein and vimentin.

We investigated the expression of vimentin and glial fibrillary acidic protein (GFAP) within Müller cells in normal human retinas and in detached human retinas of proliferative vitreoretinopathy (PVR) cases using the immunogold method. Müller cells in normal retinas showed vimentin immunoreactivity and faint GFAP immunoreactivity; however, in detached retinas they showed distinct GFAP immunoreactivity as well as vimentin immunoreactivity. Immunoelectron microscopic observation revealed that intermediate filaments (IF) within Müller cells in normal retinas showed vimentin immunoreactivity and that those within Müller cells in detached retinas showed both vimentin and GFAP immunoreactivity. Double staining for vimentin and GFAP showed that in detached retinas, these two protein immunoreactivities were observed in the same filaments. These results indicate that IF of human Müller cells consist of vimentin under normal conditions and that Müller cells in detached retinas contain different IF, which consist of vimentin and GFAP.

Adolescent↗
PubMed1990

Possible mechanisms involved in gastric hypermotility caused by indomethacin in the rat. Role of glycoprivic response.

Pathogenesis of indomethacin-induced gastric lesions was investigated in the rat by measuring lesions, gastric motility, and terminal blood glucose levels and correlating them with each other. Subcutaneously administered indomethacin (3-25 mg/kg) dose-dependently produced lesions in the stomach with concomitant gastric hypermotility and reduction of blood glucose levels. When the lesion score and the motility were plotted against terminal glucose levels, a highly significant relationship was found among these three factors (P less than 0.01). Gastric lesions and hypermotility induced by indomethacin (25 mg/kg) were suppressed significantly by 16,16-dmPGE2 (10 micrograms/kg) with no effect on the glucose levels, while intravenous infusion of glucose (25% w/w, 1.4 ml/hr) prevented these responses and restored the reduced glucose levels above the basal values. In addition, both 16,16-dmPGE2 and glucose infusion afforded a significant protection against gastric lesions induced by indomethacin even in the acid-perfused stomach (150 mM HCl). These results confirmed gastric hypermotility as a key element in the pathogenesis of indomethacin-induced lesions and further suggested that indomethacin may sensitive gastric contractility through glycoprivic receptors by inducing hypoglycemia and PG deficiency.

16,16-Dimethylprostaglandin E2↗