PubMed Health⌕ Search

Biomedical subjects

Yusuke Tada

Publications and source records attributed to Yusuke Tada.

15 recordsLinked to original sources
PubMed2004

Expression of costimulatory molecules (4-1BBL and Fas) and major histocompatibility class I chain-related A (MICA) in aortic tissue with Takayasu's arteritis.

To further investigate the immunological mechanisms involved, we analyzed the expression of costimulatory molecules in aortic tissue and their counterpart molecules on infiltrating cells of patients with Takayasu's arteritis. We also examined the expression of major histocompatibility complex (MHC) class I chain-related (MIC) A in aortic tissue, which is known to be induced by external stress, and its counterpart NKG2D receptors on infiltrating cells. Among these costimulatory molecules, strong expression of 4-1BBL and Fas was induced in the aortic tissue, and most of the infiltrating cells expressed 4-1BB and FasL, suggesting these pathways play critical roles in T-cell-mediated vascular injury. We also found that MICA was strongly induced in the aortic tissue and that at least part of the infiltrating cells expressed NKG2D receptors. Some infiltrating cells - but not vascular smooth muscle cells - seemed to have undergone apoptosis. Our findings strongly suggest that 4-1BB/4-1BBL and Fas/FasL pathways play important roles in vascular injury in Takayasu's arteritis. We assume that gammadelta T cells infiltrated aortic tissue recognizing MICA, resulting in the induction of MHC antigens and costimulatory molecules, and then alphabeta T-cells infiltrated recognizing some auto-antigens presented by MHC antigens, leading to chronic inflammation.

4-1BB Ligand↗
PubMed2004

Critical values of hematocrit and mixed venous oxygen saturation as parameters for a safe cardiopulmonary bypass.

OBJECTIVE: Mixed venous oxygen saturation (SvO2) is high despite a low hematocrit implies that the relationship between oxygen demand and supply is in a safe state. This study was sought to determine the critical values for hematocrit and SvO2 for safe cardiopulmonary bypass. METHODS: Study 1: To evaluate the limit of hemodilution without cardiopulmonary bypass, normovolemic hemodilution with Dextran 40 (10%) was performed in 14 rabbits. SvO2 was monitored from the right atrium, and the hemodynamic parameters were recorded continuously. Study 2: To determine the critical values for hematocrit and SvO2 during cardiopulmonary bypass, normothermic and hypothermic cardiopulmonary bypass were performed in 13 rabbits and hemodynamic parameters were corrected. RESULTS: Study 1: The heart rate decreased to unsafe levels abruptly, when the SvO2 was < or = 43% or the hematocrit was < or = 10%. The lactate concentration increased when the SvO2 was < or = 46% or the hematocrit was < or = 12%. Study 2: When the hematocrit was < or = 12%, the SvO2 decreased gradually. Even when weaning was possible, the animals with a hematocrit < or = 12% collapsed hemodynamically within 40 minutes after cardiopulmonary bypass. Most of the animals could not be weaned from cardiopulmonary bypass during either normothermic or hypothermic cardiopulmonary bypass when the SvO2 was < or = 46%. CONCLUSIONS: Continuous monitoring of hematocrit and SvO2 provides evidence-based guidelines for safe cardiopulmonary bypass. The lower limits of critical range for a safer cardiopulmonary bypass are hematocrit of 12% and SvO2 of 46%.

Animals↗
PubMed2004

Arterial reconstruction in the upper extremities.

Arterial reconstruction in the upper extremities is rare relative to the incidence of reconstruction in the lower extremities. Twenty-three patients who underwent vascular reconstruction in the upper extremities from 1985 to 2000 were retrospectively reviewed. Atherosclerosis was observed in only two subclavian arteries. The most common cause of occlusion was thromboembolism from the heart, which occurred often in the brachial artery and could be treated successfully with thrombectomy. Seven of eight bypass grafts, including three procedures below the elbow, remained patent during follow-up periods ranging from 2 to 9 years. Arterial reconstruction of the upper extremities differs from that in the lower extremities. Atherosclerosis is a rare cause of ischemia, and the etiology varies with the site of obstruction. Bypass surgery below the elbow is feasible and successful in selected patients. Ischemia of the upper extremity causes significant morbidity and should be treated aggressively whenever possible.

Adult↗
PubMed2003

Long-term survival after surgical treatment of patients with Takayasu's arteritis.

BACKGROUND: Surgical interventions have been performed to ameliorate the complications of Takayasu's arteritis. However, the efficacy of surgery to increase long-term survival has not been established. METHODS AND RESULTS: A retrospective review was performed on the survival of 106 consecutive patients with Takayasu's arteritis who underwent surgical treatment during the past 40 years. Their ages ranged from 5 to 69 years (mean+/-SEM, 31.7+/-1.3 years). Survival was compared with the reported results of medically treated patients according to Ishikawa's prognostic classification. There were 12 hospital deaths, and the remaining 94 patients were followed up from 8 months to 41.8 years (mean, 19.8 years). A serious long-term complication was anastomotic aneurysm, with a cumulative incidence at 20 years of 13.8%. Thirty-one late deaths were observed, and the major cause was congestive heart failure. The overall cumulative survival rate at 20 years was 73.5%. The prognostic classification by Ishikawa had little influence on the survival of surgically treated patients. For stage 3 patients, surgery seemed to increase survival; however, surgery-related complications conversely decreased the survival of stage 1 patients. CONCLUSIONS: Surgery seems to increase the long-term survival of patients with stage 3 Takayasu's arteritis, whereas conservative treatment is recommended for those with stage 1 or 2 disease. An anastomotic aneurysm may occur at any time after surgery, and regular follow-up using imaging modalities such as multi-detector CT, MRI, or ultrasonography at least once every several years for the rest of the patient's life is mandatory for the early detection of anastomotic aneurysm.

Adolescent↗
PubMed2003

Preliminary results of intermittent retrograde cerebral perfusion during proximal aortic arch surgery.

OBJECTIVE: Continuous retrograde cerebral perfusion during aortic arch surgery is associated with cerebral edema. In this report, we describe the clinical use of a new type of intermittent retrograde cerebral perfusion. SUBJECTS AND METHODS: Fourteen patients with a Stanford type A dissection were included in this study. With the usual method of retrograde cerebral perfusion, about 2,500 mL venous blood is drained from bicaval cannulae into a hard-shell reservoir, and oxygenated blood is perfused through the superior vena caval cannula. The flow rate is 300 mL/min. After about 15 min, retrograde perfusion is discontinued, and drainage from the bicaval cannulae is restarted. When a bloodless field is necessary, perfusion also is discontinued. RESULTS: Two to seven cycles of intermittent retrograde cerebral perfusion were administered (average, 3.1+/-0.4, mean+/-SD). The total retrograde perfusion time was 36.0+/-1.9 min which was equivalent to 74.8% of the circulatory arrest time. No patient developed edema of the upper body. The time to wake-up was 3 to 14 h (average, 6.5+/-1.0 h). No patient suffered any neurologic complications even though the time of circulatory arrest was greater than 60 min in four cases. Head magnetic resonance imaging or computed tomography was performed in 12 cases, and no evidence of hypoxic brain injury was detected. CONCLUSIONS: Our clinical experience using a moderate amount of intermittent retrograde cerebral perfusion is superior to continuous retrograde cerebral perfusion for protecting the brain during aortic arch surgery.

Adult↗
PubMed2003

Vascular prosthetic implantation is associated with prolonged inflammation following aortic aneurysm surgery.

The purpose of this study was to semiquantify the magnitude of surgical stress in patients undergoing aortic surgery by measuring inflammatory responses perioperatively, focusing on cytokine secretion. Serum concentrations of interleukin (IL) 1alpha, IL-6, IL-8, and tumor necrotizing factor (TNF) Alpha were measured in patients undergoing abdominal or thoracic aortic aneurysmectomy preoperatively and periodically thereafter for 2 weeks. Urinary trypsin inhibitor (UTI/Cr) and C-reactive protein (CRP) concentration and the systemic inflammatory response syndrome (SIRS) score also were determined. Indices of inflammation and cytokine concentrations peaked at 1-3 days after surgery and decreased thereafter; however, IL-8 increased again after day 7. Concentrations of IL-8, UTI/Cr, and CRP and the SIRS score were still higher 14 days after surgery than preoperatively. The maximum concentrations of IL-6 and IL-8 were higher after thoracic than abdominal aortic repair; however, the maximum values of cytokines were not correlated with operative factors in all patients. A patient suffering from graft infection showed an increase in cytokine concentrations on day 7. The inflammatory response does not return to preoperative values within 2 weeks of surgery in patients undergoing thoracic or abdominal aortic aneurysm repair. The prolonged secretion of IL-8 suggests a host reaction to the synthetic prosthesis. A large increase in inflammatory cytokines on day 7 may indicate infection of the vascular graft.

Adult↗
PubMed2003

Peroneal artery reconstruction via medial approach using tourniquet occlusion.

As peroneal artery bypass surgery is technically demanding, a simplified medial approach was used in 23 peroneal artery reconstructions in 21 patients between January 1993 and December 2001. The outcomes were reviewed retrospectively. Peroneal artery reconstruction was undertaken through a medial skin incision using tourniquet occlusion and saphenous vein grafts. Graft patency was confirmed by angiography or duplex color imaging. Peroneal bypass was possible through the medial approach in 20 cases; in 1 limb, the target was occluded. During a mean follow-up of 43.9 months, there were 4 graft occlusions. None of the failures was due to a technical error related to the procedure. All of the other patients had relief of their symptoms, including those who presented with disabling claudication. Technical improvements have made peroneal bypass a reasonable choice in below-knee arterial reconstruction. This technique should not be restricted to limb salvage.

Aged↗
PubMed2002

Thoracic aortic aneurysm associated with pseudocoarctation of the aorta.

Pseudocoarctation is a rare anomaly in the descending thoracic aorta. A 44-year-old man experienced sudden onset of back pain for 5 days prior to admission. Computed tomography showed kinking and stenosis in the distal aortic arch with a distal aneurysm. The patient underwent emergency surgery, with a diagnosis of impending rupture. The aneurysm was lobular with a very thin wall. Pseudocoarctation is rare and most often is asymptomatic. However, the aneurysm should be treated surgically, and the area of stenosis resected.

Adult↗
PubMed2002

Partial left ventriculectomy in pediatric end-stage dilated cardiomyopathy.

OBJECTIVE: Although a recent survey on pediatric cardiomyopathy in Japan showed that 48% of patients died despite the medical treatment, pediatric cardiac transplantation is not legal in Japan. We determined the feasibility of partial left ventriculectomy as an alternative to end-stage dilated cardiomyopathy. METHOD: We retrospective analyzed partial left ventriculectomy in 4 pediatric patients with end-stage dilated cardiomyopathy. RESULTS: In case 1, an 8-month-old girl underwent semiemergency partial left ventriculectomy. Her ejection fraction increased from 10% to 25%, and her condition improved initially, but she developed heart failure and underwent cardiac transplantation 6 months later in the US. In case 2, a 3-year-old boy developed severe heart failure 2 months after ventricular septal defect repair. Intensive medical therapy failed, so partial left ventriculectomy was done, which increased his ejection fraction from 15% to 35%. His condition is stable 35 months after surgery. In case 3, a 2-year-old girl with a chromosomal anomaly undergoing ventricular septal defect repair developed progressive heart failure 1 year later. Despite emergency partial left ventriculectomy, she died of hemoptysis 2 weeks postoperatively. In case 4, a 2-year-old girl developing progressive heart failure unresponsive to medical therapy after 10 months underwent elective partial left ventriculectomy and remains in stable condition 18 months postoperatively. CONCLUSION: Partial left ventriculectomy is appropriate for selected patients with end-stage dilated cardiomyopathy if medical therapy is not effective and heart transplantation is not possible.

Cardiac Surgical Procedures↗
PubMed2002

Surgical treatment of retroperitoneal leiomyosarcoma invading the inferior vena cava: report of three cases.

Retroperitoneal leiomyosarcoma is a rare neoplasm for which complete surgical removal provides the only effective treatment, as local recurrence adversely affects prognosis. However, invasion of major vessels may occur, making complete resection difficult. This report describes the cases of three patients who required concomitant resection of parts of the inferior vena cava because of direct tumor invasion. The major vessels should be isolated in preference to the tumor capsule during surgery to prevent sudden exsanguination or incomplete tumor resection. Resection of a recurrent sarcoma or a solitary metastasis can be effective in selected patients.

Adult↗
PubMed2002

Successful surgical treatment of a patient with multiple visceral artery aneurysms due to fibromuscular dysplasia.

Multiple visceral artery aneurysms due to fibromuscular dysplasia are rare. A 43-yr-old man with a pulsatile abdominal mass detected by ultrasonography had multiple visceral artery aneurysms diagnosed by angiography. This included a huge superior mesenteric artery aneurysm. Aneurysm resection and arterial reconstruction was performed successfully. Pathologic examination revealed fibromuscular dysplasia of the medial fibroplasia type.

Adult↗
PubMed2002

Bradykinin inhibits serum-depletion-induced apoptosis of human vascular endothelial cells by inducing nitric oxide via calcium ion kinetics.

Vascular endothelial cells play important roles in atherogenesis, and bradykinin is associated with atherosclerosis. The effect of bradykinin on apoptosis in human umbilical vein endothelial cells (HUVECs) was investigated, with a focus on Ca2+ kinetics and nitric oxide production. In serum-free conditions, the number of apoptotic cells increased in a time-dependent manner, but this increase was inhibited by bradykinin in a dose-dependent manner. The apoptosis inhibited by bradykinin was reduced by nitric oxide inhibitor N(G)-monomethyl-L-arginine (L-NMMA) and consequently restored by combined treatment with L-NMMA and L-arginine. Bradykinin increased influx of extracellular Ca2+, generation of inositol 1,4,5-trisphosphate, and release of Ca2+ from intracellular storage sites, thus increasing the total intracellular Ca2+ concentration ([Ca2+]i). Bradykinin increased nitric oxide production, which was inhibited by L-NMMA and restored by combined treatment with L-NMMA and L-arginine. Sodium nitroprusside (SNP) dose-dependently increased nitric oxide production and inhibited apoptosis; however, 10(-5) M SNP did not inhibit apoptosis. Caspase-3 inhibitor, acetyl-Asp-Met-Gln-Asp-aldehyde, enhanced bradykinin-induced inhibition of apoptosis but did not effect bradykinin-induced nitric oxide production. These findings suggest that bradykinin inhibits serum-depletion-induced apoptosis in HUVECs by enhancing nitric oxide production via an increase in [Ca2+]i.

Apoptosis↗
PubMed2002

Indications for partial left ventriculectomy in pediatric dilated cardiomyopathy.

The purpose of this study was to define the role and indications of partial left ventriculectomy (PLV) in children with end-stage dilated cardiomyopathy (DCM). Clinical data were collected by retrospective chart review of children with DCM who were treated from 1997 to 2000. Four patients underwent PLV (PLV group) and 5 patients were managed without PLV (non-PLV group). In the PLV group, 2 patients are well 18 and 35 months postoperatively. One infant survived 6 months and then successfully underwent heart transplantation, and the other child died of hemoptysis 2 weeks postoperatively. Factors affecting outcome were preoperative status, in particular whether surgery was performed urgently or electively. In the non-PLV group, 4 patients were well controlled by medical treatment and 1 infant underwent mitral valve replacement for severe mitral regurgitation. The cardiothoracic ratio ranged from 72% to 76% in the PLV group and from 45% to 60% in the non-PLV group. The percentage of the expected left ventricular diastolic dimension ranged from 184% to 218% in the PLV group and from 109% to 163% in the non-PLV group. Ejection fractions in the PLV group were from 10% to 22% and from 36% to 56% in the non-PLV group. The serum brain natriuretic peptide concentration was above 1,200 pg/ml in the PLV group and below 168 pg/ml in the non-PLV group. In conclusion, PLV is indicated for selected children with end-stage DCM, and is most appropriate when medical therapy is not effective and heart transplantation is unavailable.

Adolescent↗
PubMed2002

Accessory hepatic vein complicating extra-cardiac total cavopulmonary connection.

We encountered unexpected, severe hypoxia after the right heart bypass operation in a patient with isomerism. A 2-year-old girl with polysplenia had a complex cardiac anomaly consisting of a single atrium, single ventricle, pulmonary stenosis, absence of the right superior vena cava, hemiazygos continuation of the left inferior vena cava, and d-malposition of the great arteries. After a total cavopulmonary shunt, we performed an extra-cardiac total cavo-pulmonary connection with a 14 mm tube graft. The postoperative course was complicated by severe hypoxia. Angiography performed 20 days after the operation showed that contrast medium in the conduit poured into the hepatic vein, and through the intrahepatic communications, it passed into a left-sided accessory hepatic vein, which was connected directly to the left side of the aspect of the atrium. As the intrahepatic communication was adequate, we ligated the accessory hepatic vein within the pericardial cavity. The SpO2 returned to normal and no hepatic dysfunction was detected. We conclude that surgeons performing extra-cardiac total cavopulmonary connection need to pay closer attention to the possibility that an accessory hepatic vein might exist.

Child, Preschool↗