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Biomedical subjects

C Yamashita

Publications and source records attributed to C Yamashita.

At least 19 recordsLinked to original sources
PubMed1998

Role of endogenous endothelin in the development of graft arteriosclerosis in rat cardiac allografts: antiproliferative effects of bosentan, a nonselective endothelin receptor antagonist.

BACKGROUND: The purpose of this study was to determine whether endothelin-1 (ET-1) contributes to the development of graft arteriosclerosis and whether the orally active nonpeptide endothelin receptor antagonist bosentan, which blocks both ETA and ETB receptors, can protect against this pathologic damage. METHODS AND RESULTS: Recipient male Lewis rats were divided into three groups; group 1 received heterotopic heart transplantations from Lewis donors and groups 2 and 3 received transplantations from Brown-Norway donors; group 3 recipients also received bosentan orally at the dose of 20 mg/kg per day for 120 days. All recipients were given cyclosporine and were euthanized at examination 120 days after transplantation. Plasma ET-1 levels were significantly higher in group 2 than in group 1 (6.99+/-0.91 and 4.15+/-.83 pg/mL, respectively). Strong ET-1 immunoreactivity was seen in both the thickened neointima and the media of the coronary arteries in group 2 but not in group 1. The mean ratio of the coronary luminal area to the total vascular area in group 2 (19.0+/-11.7%) was significantly lower than that in group 1 (34.2+/-9.9%) and was significantly increased in group 3 (33.2+/-9.2%). CONCLUSIONS: These results show that local upregulation of ET-1, mainly in the thickened neointima and the media of the coronary arteries, may play an important role in the pathogenesis of graft arteriosclerosis by stimulating ETA receptors, ETB receptors, or both. Orally active bosentan might be a useful agent for the clinical prevention of graft arteriosclerosis.

Actins↗
PubMed1998

Impact of retrograde cerebral perfusion with posterolateral thoracotomy on distal arch aneurysm repair.

BACKGROUND: Repair of distal aortic arch aneurysms is difficult to accomplish through a median sternotomy or left thoracotomy, and stroke and respiratory disorders often become lethal complications with the use of circulatory arrest. We investigated the use of retrograde cerebral perfusion with a posterolateral thoracotomy in the repair of distal arch aneurysms. METHODS: Thirty-eight patients underwent repair of a distal arch aneurysm. They were divided into three groups according to the method of surgical repair used. Sixteen patients (group I) underwent proximal anastomosis of the graft with the use of an aortic cross-clamp. Eight patients (group II) underwent open proximal anastomosis with the use of retrograde cerebral perfusion (oxygenated blood perfusion through a superior vena cava cannula) and a median sternotomy and anterolateral thoracotomy. Fourteen patients (group III) also underwent open anastomosis with the use of retrograde cerebral perfusion (cerebral perfusion through blood returned to the right atrium with the patient in the Trendelenburg position) and a posterolateral thoracotomy. RESULTS: The operative mortality rate in group I was 25.0%; 4 of 16 patients died of stroke, myocardial infarction, and intestinal necrosis. In group II, 3 of 8 patients (37.5%) died of respiratory failure and aortic dissection. In group III, only 1 of 14 patients (7.1%) died, as a result of heart failure. CONCLUSIONS: The use of retrograde cerebral perfusion with a posterolateral thoracotomy is an alternative method that minimizes the risk of stroke and respiratory failure during distal aortic arch operations.

Adult↗
PubMed1998

Surgical treatment for transvenous tumor extension into the heart: four cases.

From 1984 to 1996, four patients with transvenous intracardiac tumor extension underwent operations in the Kobe University Hospital. The primary tumors of two were intravenous leiomyomatoses originating from the uterus; a third patient had invasive thymoma, and the fourth patient had clear cell sarcoma of the kidney. In 1985, one patient had a curative, staged resection. One-stage operations were carried out in three patients, and all intracardiac tumors were successfully resected en bloc with the primary tumors under conditions of electrical ventricular fibrillation and mild hypothermia. Combined venous reconstructions were necessary for en bloc resection in three cases. Two patients with malignancy received postoperative chemoradiotherapy, and all four patients were discharged uneventfully from our hospital. We consider radical resection with curative intent only for patients with tumors extending into the heart. In these cases, a one-stage operation is preferable, and electrical ventricular fibrillation with mild hypothermia is a recommended method of circulatory assist because of its simplicity.

Adult↗
PubMed1998

Neonatal erythema infectiosum.

A report is presented of a patient with neonatal erythema infectiosum who developed petechiae, transient thrombocytopenia and transient cardiac failure due to transplacental transmission of human parvovirus B19 (HPV B19) infection. It is suggested that the thrombocytopenia was caused by platelet-associated IgG produced by the patient, and that the cardiac failure may have been caused by direct entry of HPV B19 into the cardiac tissue.

Adult↗
PubMed1998

Surgical results of composite graft replacement of the aortic root aneurysm.

From 1986 to 1996, 20 patients underwent aortic root replacement. All of the patients had annulo aortic ectasia (AAE); Six had DeBakey type I aortic dissection, three were acute dissections associated with Marfan's syndrome; three had previously undergone the Koster-Collins operation. During 11 years, the original Bentall procedure (1986-91), the Cabrol procedure (1991-), and the modified Bentall procedure (Carrel patch or Piehler technique) were performed. There was only 1 hospital mortality (5.0%). Four patients died during the follow-up period (mediastinitis, myocardial infarction, cerebral bleeding, and rupture of the arch aneurysm). Only 2 patients required reoperation (repair of a pseudoaneurysm of the right coronary artery and paravalvular leakage of the aortic valve replacement). The satisfactory outcomes were the result of the full-thickness anastomoses performed during coronary artery reconstruction.

Adult↗
PubMed1997

Open distal anastomosis in retrograde cerebral perfusion for repair of ascending aortic dissection.

BACKGROUND: In patients with aortic dissection, a patent distal false lumen at long-term follow-up leads to complications. We investigated the feasibility of performing an open distal anastomosis using retrograde cerebral perfusion. METHODS: Over a 10-year period, 41 patients with acute type A aortic dissection underwent 43 surgical repairs. In 1991, an open distal anastomosis using retrograde cerebral perfusion (group 2) was introduced to replace the standard aortic cross-clamp method (group 1). The mean retrograde cerebral perfusion time was 47.3 minutes (range, 22 to 67 minutes), and there were no neurologic sequelae in surviving patients. RESULTS: The operative mortality rate was 18.5% in group 1 and 18.7% in group 2. At long-term follow-up, dilatation of the false lumen (more than 50 mm in diameter) occurred in 9 of 18 patients (50%) in group 1, and 2 patients died of aortic rupture. There were no deaths in group 2, and dilatation of the distal false lumen occurred in only 15.4% of patients (p < 0.05). CONCLUSIONS: The use of retrograde cerebral perfusion in patients with acute aortic dissection provides adequate time to perform a safe, open, distal anastomosis, and could decrease significantly the rate of enlarged, patent, false lumina.

Acute Disease↗
PubMed1997

Suppression of glucose absorption by some fractions extracted from Gymnema sylvestre leaves.

Extracts containing gymnemic acids, which were extracted from the leaves of Gymnema sylvestre (GS) as nine fractions, were evaluated for their effects on a high K(+)-induced contraction of guinea-pig ileal longitudinal muscles, on glucose transport mediated by the difference of glucose-evoked transmural potential difference (delta PD) in the inverted intestine of guinea-pig and rat, and on blood glucose in rat. Among nine fractions obtained by high performance liquid chromatography from the extract, f-2 and f-4 strongly suppressed the high K(+)-induced contraction of the ileal muscle, f-3 and f-5 did so moderately, and f-8 and f-9 did so weakly, whereas the other fractions did not affect it. The degree of suppression of high K(+)-induced contraction by f-2 at 74% was almost the same as that of f-4 at 67%, at concentrations of 0.1 mg/ml. The suppressed contraction by f-2 or f-4 was recovered by adding 5.5 mM pyruvate. The delta PD increased by 5.5 mM glucose in the inverted intestines of guinea-pig and rat were equally suppressed by 0.1 mg/ml of f-2 or f-4 to 40%. In a rat sucrose tolerance test, f-2 and f-4 suppressed the elevation of blood glucose level. Both f-2 and f-4 suppressed the contraction of guinea-pig ileal longitudinal muscle, interfered with the increase in delta PD induced by glucose in the inverted intestines of guinea-pig and rat, and inhibited the elevation of blood glucose level. In conclusion, it is suggested that some of the extracts containing gymnemic acids from GS leaves suppress the elevation of blood glucose level by inhibiting glucose uptake in the intestine.

Administration, Oral↗
PubMed1997

[Successful surgical treatment for giant non-specific cyst in the anterior mediastinum].

A 46-year-old woman was admitted to our hospital with giant cyst in the anterior mediastinum. We strongly suspected the cyst would be cystic teratoma from preoperative examinations. Cystectomy was undergone through a right thoracotomy in the 6th intercostal space. The cyst, 15 x 14 x 13 cm in size, had a fibrous wall and contained yellowish serous fluid with hair-ball which revealed aseptic bacteriologically. In the pathological study, the cyst had no recognizable specific epithelium or mesothelium, and this finding was incompatible with cystic teratoma. Due to lack of teratoid elements, the final diagnosis was "non-specific mediastinal cyst". The cyst was considered to be the result of inflammation or intracystic auto-digestion by enzymes from the alimentary tissue of the cystic teratoma.

Diagnosis, Differential↗
PubMed1997

Single lung transplantation for canine pulmonary hypertension.

BACKGROUND: In spite of recent reports of the clinical application of single lung transplantation for pulmonary hypertension, there is little underlying experimental data because of the lack of a reliable animal pulmonary hypertensive transplant model. We have established a pulmonary hypertensive model in beagles with dehydromonocrotaline and have been able to measure cardiopulmonary hemodynamics accurately and use circulatory assists during procedures. The purpose of this study was to determine whether single lung transplantation could be performed after the protocol of clinical procedure. METHODS AND RESULTS: In six control dogs, allografting was successfully completed without cardiopulmonary bypass. Because one pulmonary hypertensive recipient dog died of right ventricular failure during the procedure without cardiopulmonary bypass, we used bypass for allografting in five pulmonary hypertensive dogs. Cardiopulmonary bypass lowered pulmonary artery pressure, allowing pulmonary arterial clamping and avoiding right ventricular overload. All pulmonary hypertensive dogs undergoing bypass were successfully weaned from bypass, indicating a good hemodynamic response to transplantation. In pulmonary hypertensive dogs, transplantation resulted in significant decreases in systolic pulmonary artery pressure and pulmonary vascular resistance, and a significant increase in blood flow to the graft lung, whereas in controls the results were the reverse. CONCLUSIONS: Thus we were able to show that hemodynamics improved after single lung transplantation with cardiopulmonary bypass in a new pulmonary hypertensive animal model. These relatively larger animals are valuable for further studies of single, double, bilateral, and heart-lung transplantation for pulmonary hypertension.

Animals↗
PubMed1997

Retrograde cerebral perfusion with pharmacological cerebral protection in the repair of aortic arch aneurysm.

Twenty-six patients underwent resection and graft replacement of an aortic arch aneurysm (proximal arch,5; transverse arch:2, distal arch,8; and type A dissecting aneurysm. Retrograde cerebral perfusion with pharmacological cerebral protection was carried out during aortic arch aneurysm surgery. Prostaglandin E1, thiopental methylpredonisolone were administered for cerebral protection during core cooling. D-Mannitol and deferoxamine mesylate (radical scavengers) were administered for prevention of reperfusion injury. retrograde cerebral perfusion time was 48 +/- 16 minutes (range 20-80 minutes). Perfusion flow was 288 +/- 93 mL/min (range 150-500 mL/min). Since retrograde cerebral perfusion requires no arterial cannulation or aortic cross clamp, the operative field is simplified, and the risks of air and debris emboli to the brain were minimized. Reconstruction was designed to minimize the circulatory arrest time. Eleven cases underwent emergency surgery due to rupture and acute dissection. Five patients (19.2%) died (three from bleeding from the distal anastomosis, one from postoperative DIC and, one from intraoperative dissection). The remaining 21 patients survived neurologically intact. Retrograde cerebral perfusion with pharmacological cerebral protection is a very simple method to prevent air embolism or thromboembolism in aortic arch aneurysm surgery and allows aortic arch replacement in a bloodless field. In spite of the extended circulatory arrest time, recovery of consciousness was complete.

Adult↗
PubMed1997

[Surgical treatment of aortic dissection (Stanford type A) using hypothermic retrograde cerebral perfusion in patients older than 70 years of age].

Since 1991, 27 consecutive patients with aortic dissection (Stanford A) have been operated on using deep hypothermic retrograde cerebral perfusion (RCP). There were no differences in ECC time (247 +/- 15 vs 307 +/- 22 min), and RCP time (47 +/- 2 vs 47 +/- 3 min) between the aged (> or = 70 y.o., n = 11) and non-aged (< 70 y.o., n = 16) group. Although the aged group showed the higher incidences of postoperative neurological complications of prolonged emergence (2 cases) and delirium (3 cases), respiratory disorder (3 cases), and renal dysfunction (3 cases), there was no significant difference in hospital mortality (18% in the aged vs 13% in the non-aged). We concluded that RCP is well acceptable procedure for surgical treatment of the aged patients with aortic dissection.

Age Factors↗
PubMed1997

Rupture of a dissecting aneurysm into the superior vena cava in Marfan's syndrome.

Aneurysmal dilatation of the aorta with subsequent dissection or rupture occurs frequently in patients with Marfan's syndrome. These complications are among the major causes of death. We report the case of a 51-year-old man with annulo-aortic ectasia in Marfan's syndrome. Acute aortic dissection and rupture into the superior vena cava occurred 8 years after aortic valve replacement. The preoperative diagnosis was made by right heart catheterization and computed tomography. A markedly increased left-to-right shunt occurred with rapid enlargement of the fistula due to the fragility of the aortic wall characteristic of Marfan's syndrome. Postmortem examination demonstrated severe medial necrosis with rupture of the aortic wall into the superior vena cava which was adherent to the suture line of the aortotomy from the previous surgery. Type A aortic dissection with severe congestive heart failure strongly suggested rupture into the pulmonary circulation.

Aortic Dissection↗
PubMed1997

[A case of hemodialysis-associated innominate vein stenosis inducing superior vena cava syndrome].

Twenty years after making an arteriovenous shunt in the left arm, a 45-year-old man on hemodialysis developed progressive swelling in the face to left arm and venous dilatation on the left anterior chest. Venogram disclosed severe stenosis of the left innominate vein at the junction of the superior vena cava, which was considered to be a primary lesion because he had no history of subclavian vein cannulation or mediastinal disease. Surgical resection of the stenotic lesion and direct anastomosis of the innominate vein resulted in a rapid recovery of the symptom of venous hypertension. This is a rare case of hemodialysis-associated large vein complication leading to superior vena cava syndrome.

Arteriovenous Shunt, Surgical↗
PubMed1997

Cerebral complications and distal false lumen in the repair of aortic dissection with retrograde cerebral perfusion.

BACKGROUND: In aortic dissection, patent distal false lumen at long-term follow-up leads to complications. We investigated the feasibility of an open distal anastomosis under retrograde cerebral perfusion. METHODS: During a 15-year period (1981-1995), 51 patients with type A dissection underwent 59 surgical repairs. In 1990, a distal open anastomosis with retrograde cerebral perfusion (group II) was introduced to replace the aortic cross clamp method (group I). Mean retrograde cerebral perfusion time was 50 minutes (range 22 to 65 minutes) with no neurologic sequelae in surviving patients. RESULTS: Operative mortality was 28.6% in group I, and 16.1% in group II. At long-term follow-up, dilatation of the false lumen (more than 50 mm in diameter) occurred in 56.2% (9/16) in group I, and 4 patients died of aortic rupture. There was no mortality in group II, and dilatation of the distal false lumen occurred in only 15.3% (p<0.05). CONCLUSIONS: Use of retrograde cerebral perfusion in aortic dissection allowed for adequate time to perform a safe, open, distal anastomosis. Intraoperative cerebral complications and enlarged patent false lumens decreased significantly.

Acute Disease↗
PubMed1996

Exclusion of the beta-subunit of type II calmodulin kinase for the wobbler spinal muscular atrophy gene.

The wobbler mouse (wr) is an attractive model for studying motor neuron disease but the genetic defect is unknown. The beta-subunit of calmodulin kinase II (beta-CaMK II) is a good candidate for the wr mutation because of its chromosomal localization and tissue distribution. In this report, we found normal levels of CaM KII mRNA and enzyme activity making it highly unlikely that a mutation in the beta-CaM KII gene is the cause of the wr phenotype.

Animals↗
PubMed1996

Sterol 14-demethylase P450 activity expressed in rat gonads: contribution to the formation of mammalian meiosis-activating sterol.

Sterol 14-demethylase P450 (P45014DM)-dependent formation of 4,4-dimethylcholesta-8,14,24-trienol, that has been reported for a mammalian meiosis-activating sterol, in rat ovaries was confirmed. Transient elevation of ovarian P45014DM activity, that might be related to the female sexual cycle of rat, was observed. The P45014DM activity of immature ovaries was induced by pregnant mare's serum gonadotropin. These facts suggest the contribution of ovarian P45014DM to the gonadotropin-dependent formation of the meiosis-activating sterol, and provide a clue to understanding the mechanism how gonadotropins initiate the resumption of meiosis of mammalian oocytes. It was also found that rat testicular P45014DM participated in the production of 4,4-dimethylcholesta-8,24-dienol that was reported for another meiosis-activated sterol isolated from bull testes.

Animals↗
PubMed1996

Right ventricular ejection fraction in the preoperative risk evaluation of candidates for pulmonary resection.

The major determinants of postoperative morbidity and mortality after lung resection are the physiologic and functional statuses of the pulmonary and cardiac systems. In our previous study, serial measurements of right ventricular performance after pulmonary resection demonstrated significant right ventricular dysfunction in the postoperative period. This study evaluates the preoperative measurement of right ventricular ejection fraction as a predictor of postoperative complications. In addition to conventional cardiopulmonary functional tests, right ventricular function was assessed with a thermodilution technique at rest and during exercise in 18 patients before and 3 weeks after lobectomy or pneumonectomy. The patients were grouped according to severity of right ventricular functional defect: right ventricular ejection fraction of at least 45% (group Ia, n = 8), right ventricular ejection fraction less than 45% (group Ib, n = 10), exercise-induced increases in right ventricular ejection fraction (group IIa, n = 8), and exercise-induced decreases in right ventricular ejection fraction (group IIb, n = 10). Postoperative cardiopulmonary morbidity was recorded for two patients (25%) in group Ia, three patients (30%) in group Ib, no patients (0%) in group IIa, and five patients (50%) in group IIb. Postoperative hospital stay was 28.9 +/- 8.5 days in group Ia, 29.9 +/- 20.2 days in group Ib, 19.4 +/- 8.0 days in group IIa, and 37.5 +/- 15.9 days in group IIb (p < 0.05, group IIa vs group IIb). Although resection-induced changes in forced expiratory volume in 1 second did not differ significantly between group Ia and group Ib, these values appeared to be increased in groups IIa (not statistically significant) and IIb (significantly, p < 0.05). The measured postoperative values of forced expiratory volume in 1 second and vital capacity were significantly higher than the predicted postoperative values (p < 0.05) in group IIa, but not in groups Ia, Ib, and IIb. We conclude that evaluation of right ventricular performance is useful in determining which patients are at increased risk for medical complications after lung resection. Exercise-induced change in right ventricular ejection fraction may be a better indicator of high risk among candidates for pulmonary resection than the absolute value of this parameter.

Aged↗