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Biomedical subjects

Yuji Miyamoto

Publications and source records attributed to Yuji Miyamoto.

At least 37 records · Page 2Linked to original sources
PubMed2004

Successful surgical intervention for active infective endocarditis on a hemodialysis patient with cerebral infarction and disseminated intravascular coagulopathy.

A 48-year-old woman on hemodialysis developed congestive heart failure, neurologic deficits and disseminated intravascular coagulopathy (DIC) caused by methicillin resistant staphylococcus aureus infective endocarditis. Echocardiography showed large vegetation attached to the anterior leaflet of the mitral valve, severe mitral and aortic regurgitation, and poor left ventricular function. Computed tomography findings revealed recurrent embolic events including cerebral and splenic infarction, but no evidence of intracranial bleeding. Abnormal laboratory findings included DIC in addition to the administration of the daily dose of ticlopidine hydrochloride. Aortic and mitral valves were urgently replaced with bioprosthetic valves after the transfusion of fresh frozen plasma and platelet. During the follow-up period of one year, she was free from any cardiac events and infectious signs. Even though this report is limited to a case and its follow-up, it is sensible to conclude that only aggressive and timely surgical intervention can be the only lifesaving action for patients with highly infective endocarditis.

Aortic Valve↗
PubMed2004

Subdural hematoma induced by cerebrospinal fluid drainage: potentially catastrophic complication of spinal cord protection after thoracoabdominal aneurysm repair.

A 50-year-old man underwent replacement of the descending thoracic aorta for a DeBakey type III-b chronic dissecting aortic aneurysm. During the surgery, lumbar cerebrospinal fluid (CSF) drainage with a 10 cm H2O pop-off pressure was used to protect against spinal cord ischemia. During cardiopulmonary bypass, the patient's pupils were isocoric, but anisocoric at end of the operation. As computed tomography of the brain showed right subdural hematoma, neurosurgical drainage was instituted emergently. Although some neurological deficit remained, the patient recovered well and was discharged. This case provides a strong reminder that CSF drainage for spinal cord protection against ischemia might induce subdural hematoma, which can be catastrophic during an operation for thoracoabdominal aortic aneurysm.

Aortic Dissection↗
PubMed2004

Intraabdominal placement of a Novacor ventricular assist system by using an expanded polytetrafluoroethylene pouch.

The location of the pump pocket for the left ventricular assist system is of great importance because of its direct relation to subsequent complications. The Novacor device has usually been implanted at the space behind the rectus muscle, which leads to occasional bleeding from raw muscle surfaces and to subsequent pocket infection. Although intraabdominal placement causes less bleeding and is more refractory to later pocket infection, direct contact with the visceral organs sometimes causes serious complications. We constructed a pouch from an expanded polytetrafluoroethylene sheet, and this enabled intraabdominal placement of the Novacor device.

Abdomen↗
PubMed2004

Pharmacologic preconditioning of JTE-607, a novel cytokine inhibitor, attenuates ischemia-reperfusion injury in the myocardium.

BACKGROUND: Myocardial ischemia-reperfusion injury is a main cause of postoperative cardiac dysfunction, and a burst of proinflammatory cytokines, such as tumor necrosis factor alpha, interleukin 1 beta, interleukin 6, and interleukin 8, plays a pivotal role. Recently, JTE-607 has been reported as a potent inhibitor of the multiple inflammatory cytokines in the endotoxin shock mouse model. In this study we proved the hypothesis that JTE-607 might attenuate myocardial ischemia-reperfusion injury in a rat model. METHODS: The isolated rat hearts in the JTE-607 preconditioning group (J group, n = 8) or control group (C group, n = 8) were subjected to warm ischemia (37 degrees C) for 30 minutes, followed by 60 minutes of reperfusion with the Langendorff perfusion system. RESULTS: Left ventricular developed pressure and maximum dp/dt after reperfusion were significantly improved in the J group than in the C group (P <.01). Creatine phosphokinase leakage is significantly lower in the J group (P <.05). Moreover, the tissue cytokine levels, such as tumor necrosis factor alpha, interleukin 6, and interleukin 8, in the myocardium were significantly lower in the J group than in the C group (P <.05). CONCLUSION: These results suggested that the pharmacologic preconditioning of JTE-607 inhibits a burst of endogenous cytokines in the myocardium, resulting in the improvement of cardiac function after ischemia-reperfusion injury. Thus JTE-607 might be a novel therapeutic strategy for the protection of postoperative cardiac dysfunction in cardiac surgery.

Animals↗
PubMed2004

Sinus of valsalva aneurysm with congenital aortic stenosis and aortic coarctation.

A 52-year-old female was diagnosed with the extremely rare combination of sinus of Valsalva aneurysm, congenital unicuspid aortic valve stenosis, and coarctation of the aorta. She was successfully treated in a two-stage operation. The first operation consisted of a bypass graft to correct the coarctation. The second, performed 31 days later, included aortic valve replacement, patch closure of the aneurysm, and translocation of the right coronary artery.

Abnormalities, Multiple↗
PubMed2004

Early result of heart transplantation in Japan: Osaka University experience.

Since the new organ transplantation law was established in 1997, 17 heart transplantations have been performed in Japan, 7 of which were carried out at Osaka University Hospital. Recipient diagnosis was dilated cardiomyopathy in 2, dilated phase of hypertrophic cardiomyopathy in 4, and post-myocarditis cardiomyopathy in 1. Ages ranged from 8 to 49 years with a mean of 35.3 years. Five patients were bridged with a left ventricular assist device. The waiting period was 182-977 days (mean, 643 days). There was no early or late death during follow-up of 1-4.8 years. Under a standard triple-drug regimen using mycophenolate, there were 3 rejection episodes greater than grade 3 in 2 patients, and humoral rejection requiring plasmapheresis in one. A young boy whose donor was a hemodynamically compromised adult developed neurological sequelae after resuscitation following ventricular tachycardia. All patients were discharged and went back to work or their regular daily life. Although the donor shortage is still severe in Japan, the resumption of heart transplantation has been satisfactory, and left ventricular assist devices have played a crucial role.

Adult↗
PubMed2004

Advantages of off-pump coronary artery bypass grafting in long-term hemodialysis patients: multicenter analysis.

OBJECTIVE: Long-term hemodialysis remains a major risk factor for coronary artery bypass grafting (CABG). Off-pump CABG (OPCAB) is expected to offer benefits for these high risk patients; however, this issue has not been clarified. To elucidate the issue, we conducted a multicenter retrospective review of long-term hemodialysis patients who underwent on- or off-pump CABG. PATIENTS: Between January 1998 and December 2002, 53 hemodialysis patients underwent elective CABG at 14 centers. Nineteen patients underwent OPCAB, and 34 patients underwent conventional CABG (CCAB). Preoperative and perioperative variables, morbidity, and mortality were compared in the 2 groups. There were no significant differences in preoperative variables between the 2 groups. RESULTS: The length of intensive care unit (ICU) stay (3.7 versus 5.9 days), the amount of blood loss (668 versus 1100 mL), and the amount of red cell transfusion (4.7 versus 12.2 units) were less in the OPCAB group. The perioperative morbidity was significantly lower in the OPCAB group (0.0% versus 26.5%). The hospital mortality was not significant but was low in the OPCAB group (0% versus 14.7%, P = .079). CONCLUSION: OPCAB significantly decreased blood loss, blood transfusion, ICU stay, and major perioperative morbidity compared with the values for CCAB. OPCAB may have advantages over CCAB in long-term hemodialysis patients.

Blood Transfusion↗
PubMed2004

Valvuloplasty for anterior mitral leaflet prolapse due to infective endocarditis: report of 2 cases.

We report 2 clinical cases of successful repair of an infected mitral valve with a broad-range prolapse of the anterior mitral leaflet (AML) with large vegetation. The chordal transfer technique was used in both cases, and autologous pericardium was transplanted in one case. There was neither residual mitral regurgitation nor recurrence of mitral valve infection. Chordal transfer is a useful technique for AML lesions of infective endocarditis if the corresponding area of the posterior ML remains normal, and even in the case of a broadly destroyed lesion of the AML, it is valuable to try to apply this technique with an autologous pericardial patch.

Adult↗
PubMed2004

Delayed chronic type A dissection with a functional midline crossing right internal thoracic artery after CABG: surgical approach to an ascending aorta without dissecting the midline crossing internal thoracic artery.

We successfully treated chronic type A dissection and coronary artery disease with a functional midline crossing right internal thoracic artery (RITA) after coronary artery bypass grafting (CABG). A 68-year-old man was incidentally diagnosed as chronic type A dissection by follow-up cardiac catheterization after CABG, with 90% stenosis in the right coronary artery (RCA) No. 2. The dissecting aneurysm (max. 6 cm in diameter) was localized at the right portion of the ascending aorta with a functional RITA to the left anterior descending coronary artery. The dissecting aneurysm was treated with patch closure and the RCA was revascularized with a right gastroepiploic artery and saphenous vein composite graft through combined right antero-axillar thoracotomy and lower mini-sternotomy without RITA dissection. Treatment of chronic type A dissection following CABG becomes more challenging with a functional midline crossing RITA. It is important that a safe and less invasive surgical strategy be implemented for such complicated case.

Aged↗
PubMed2003

Successful treatment of Novacor pump pocket infection by omental transposition.

Device-related infection remains a major factor restricting the long-term use of left ventricular assist systems. Severe pocket infection is especially difficult to manage and removal of the device has been the only curative treatment in most cases. We report a case of a Novacor device pocket infection treated successfully with continuous local irrigation and transposition of omental flap. This procedure provides another option for the management of pocket infection, which is mandatory for destination therapy the permanent usage of LVAS for the purpose of circulatory supports in patients with end-stage heart failure, who are not indicated for heart transplantation.

Adult↗
PubMed2003

Changes in left anterior descending coronary artery flow profiles after coronary artery bypass grafting examined by means of transthoracic Doppler echocardiography.

OBJECTIVE: We sought to investigate the changes of velocity profiles in the left anterior descending coronary artery after coronary artery bypass grafting using transthoracic Doppler echocardiography. METHODS: Forty-five patients who received a bypass graft to the left anterior descending coronary artery were studied. Before coronary artery bypass grafting, Doppler velocity profiles of the distal left anterior descending coronary artery were recorded with transthoracic Doppler echocardiography. Peak systolic velocity, mean systolic velocity, peak diastolic velocity, mean diastolic velocity, total velocity time integral, systolic velocity time integral, and diastolic velocity time integral were measured. Three weeks after coronary artery bypass grafting, left anterior descending coronary artery antegrade flow in the distal portion of the anastomosis was obtained by using the same method. Coronary angiography was performed before and 3 weeks after coronary artery bypass grafting. RESULTS: The overall success rate of measuring the left anterior descending coronary artery flow was 60.0% preoperatively and 80.0% postoperatively. In 25 patients, in whom all parameters were obtained both before and after coronary artery bypass grafting, the following increased significantly after coronary artery bypass grafting: peak systolic velocity (14.86 +/- 7.50 vs 25.07 +/- 17.02 cm/s, P =.0045), mean systolic velocity (9.86 +/- 5.42 vs 18.03 +/- 12.94 cm/s, P =.0026), peak diastolic velocity (24.26 +/- 12.54 vs 48.28 +/- 31.66 cm/s, P =.0021), mean diastolic velocity (14.94 +/- 6.65 vs 30.36 +/- 20.71 cm/s, P =.0022), diastolic velocity time integral (7.22 +/- 2.88 vs 15.55 +/- 10.39 cm, P =.0009), total velocity time integral (10.50 +/- 4.48 vs 19.27 +/- 12.63 cm, P =.0034), and diastolic-to-systolic velocity time integral ratio (3.09 +/- 1.53 vs 4.97 +/- 2.75, P =.0044). Angiography showed graft patency and no significant change in left anterior descending coronary artery stenosis in all patients. CONCLUSIONS: Transthoracic Doppler echocardiography showed a significant increase in some parameters in left anterior descending coronary artery flow after coronary artery bypass grafting. Measurement of left anterior descending coronary artery flow by means of transthoracic Doppler echocardiography might be a noninvasive method to evaluate the effect of bypass grafting on the left anterior descending coronary artery.

Aged↗
PubMed2003

Leukocyte-depleted terminal blood cardioplegia provides superior myocardial protective effects in association with myocardium-derived nitric oxide and peroxynitrite production for patients undergoing prolonged aortic crossclamping for more than 120 minutes.

OBJECTIVES: This study was designed to examine the myocardial protective effect of leukocyte-depleted terminal blood cardioplegia in association with nitric oxide and peroxynitrite production, especially for patients undergoing prolonged aortic crossclamping. METHODS: Fifty-four patients (34 men, 20 women, mean age 56.7 +/- 12.7 years) undergoing aortic valve replacement were randomly allocated to one of two groups; group LDTC (n = 27) received 10 minutes of leukocyte-depleted terminal blood cardioplegic solution, and group CONT (n = 27) served as controls. Each group was subdivided into 2 groups: aortic crossclamping for less than 120 minutes in groups LDTC-S (n = 13) and CONT-S (n = 14); aortic crossclamping for 120 minutes or more in groups LDTC-L (n = 14) and CONT-L (n = 13). RESULTS: After aortic unclamping, group LDTC-L showed higher incidence of spontaneous defibrillation (78.6% vs 30.8%, P =.0213), higher plasma nitrate + nitrite in the coronary sinus effluent (32.5 +/- 4.1 vs 28.7 +/- 3.0 micromol/L, P =.0013), lower differences between coronary sinus effluent and arterial blood in the percentage ratio of nitrotyrosine to tyrosine (myocardium-derived peroxynitrite; 2.987% +/- 0.576% vs 3.951% +/- 0.952%, P =.0036), and plasma polymorphonuclear-elastase (113.9 +/- 21.3 vs 155.5 +/- 41.6 microg/L, P =.0029) and malondialdehyde (2.75 +/- 0.67 vs 4.02 +/- 0.96 micromol/L, P =.0005) than group CONT did. Postoperatively, group LDTC-L showed lower human-heart fatty acid-binding protein (111.4 +/- 25.2 vs 156.4 +/- 38.6 IU/L, P =.0013), lower creatine kinase-muscle and brain (19.2 +/- 4.7 vs 24.8 +/- 6.5 IU/L, P =.0120), and smaller requirement of catecholamine (5.44 +/- 2.29 vs 8.45 +/- 3.42 microg x kg(-1) x min(-1), P =.0122). There were no significant differences in these parameters between groups LDTC-S and CONT-S. CONCLUSIONS: This study demonstrated that leukocyte-depleted terminal blood cardioplegia provided superior myocardial protective effects and regulated myocardial-derived nitric oxide and peroxynitrite production only for patients undergoing aortic crossclamping for more than 120 minutes. The results suggest that prolonged aortic crossclamping deteriorates the tolerance to leukocyte-mediated myocardial injury accompanied by endothelial dysfunction associated with nitric oxide and peroxynitrite production.

Adolescent↗
PubMed2003

Hypertrophic non-obstructive cardiomyopathy with aortic and mitral regurgitation: an unusual presentation for surgical option.

The case is described of a pediatric patient with hypertrophic non-obstructive cardiomyopathy (HNCM) presenting with aortic and mitral regurgitation. This 17-year-old boy had been followed for HNCM since he was aged 4 years. Serial echocardiography had been showing the emergence and progression of aortic regurgitation and mitral regurgitation since the patient was aged 6 years. He started to have syncope attacks at 16 years of age and fell into congestive heart failure at 17 years. He underwent successful mitral valve repair by means of double-orifice technique, and aortic valve repair with raphe triangular resection, cusp plication and subvalvular annuloplasty.

Adolescent↗
PubMed2003

Aortic arch replacement with proximal first technique.

BACKGROUND: Deep hypothermic circulatory arrest (DHCA) without retrograde cerebral perfusion (RCP) has a strict time limit. We modified a surgical technique for anastomosis to shorten the period of DHCA and unilateral cerebral perfusion (UCP). METHODS: Between March 1993 and August 2001, retrospective analysis was done on 23 consecutive patients, who underwent aortic arch replacement with branches. The patients were divided into two groups: DHCA group and UCP group. The DHCA group, in which DHCA alone and without additional cerebral perfusion was performed, comprised of nine patients. Proximal aortic anastomosis was performed first during systemic cooling; then both the brachiocephalic artery and left carotid artery were reconstructed with the branches of the artificial graft during circulatory arrest; thereafter, cerebral and coronary perfusions were resumed. The UCP group, in which DHCA was not used but right hemisphere perfusion during deep hypothermia was performed when the origin of brachiocephalic artery was safely clamped, consisted of 14 patients. RESULTS: Mean time of DHCA was 18.8+/-4.2 minutes and that of right hemisphere perfusion time was 11.0+/-3.8 minutes, respectively. Twenty-one patients survived the surgery (91.3%), and two (8.7%) died during hospitalization. Transient cerebral complication occurred in four patients in the DHCA group and all recovered. Logistic regression analysis revealed that DHCA was the only parameter to significantly influence temporary neurological dysfunction. There was no other significant difference between the two groups. CONCLUSION: With our modified and simple surgical technique for aortic arch repair, we were able to successfully shorten the DHCA time and right hemisphere perfusion time. However, because DHCA was the only parameter to significantly influence temporary neurological dysfunction, some form of continuous cerebral perfusion at deep hypothermia may be a safer method to preserve cerebral function.

Adult↗
PubMed2002

Identification of Saccharomyces cerevisiae isoleucyl-tRNA synthetase as a target of the G1-specific inhibitor Reveromycin A.

To dissect the action mechanism of reveromycin A (RM-A), a G(1)-specific inhibitor, a Saccharomyces cerevisiae dominant mutant specifically resistant to RM-A, was isolated from a strain in which the genes implicated in nonspecific multidrug resistance had been deleted. The mutant gene (YRR2-1) responsible for the resistance was identified as an allele of the ILS1 gene encoding tRNA(Ile) synthetase (IleRS). The activity of IleRS, but not several other aminoacyl-tRNA synthetases examined in wild type cell extract, was highly sensitive to RM-A (IC(50) = 8 ng/ml). The IleRS activity of the YRR2-1 mutant was 4-fold more resistant to the inhibitor compared with that of wild type. The mutation IleRS(N660D), near the KMSKS consensus sequence commonly found in the class I aminoacyl transferases, was found to be responsible for RM-A resistance. Moreover, overexpression of the ILS1 gene from a high-copy plasmid conferred RM-A resistance. These results indicated that IleRS is a target of RM-A in vivo. A defect of the GCN2 gene led to decreased RM-A resistance. IleRS inhibition by RM-A led to transcriptional activation of the ILS1 gene via the Gcn2-Gcn4 general amino acid control pathway, and this autoregulation seemed to contribute to RM-A resistance.

Cell Cycle↗
PubMed2002

A comprehensive catalog of CpG islands methylated in human lung adenocarcinomas for the identification of tumor suppressor genes.

CpG island methylation is an important mechanism in gene silencing and is a key epigenetic event in cancer development. As yet, the number and identities of the genes that are inactivated in cancer cells has not been determined. In order to address this issue, we have performed a comprehensive isolation of CpG islands that are methylated in human lung adenocarcinomas. We have isolated approximately 200 CpG islands that are methylated in tumor DNA including those of known tumor-associated genes such as the HOXA5 gene. As the library contains the CpG islands of a number of known tumor suppressor genes it is highly likely that additional, previously unidentified tumor suppressor genes, will be present. On average, 1-2% of CpG islands were methylated specifically in tumors although this figure differed greatly between patients. This study provides an important resource in the search for genes inactivated in tumors and for the investigation of epigenetic dysregulation of gene expression by CpG island methylation.

Adenocarcinoma↗