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Hiroaki Sasaki

Publications and source records attributed to Hiroaki Sasaki.

At least 19 recordsLinked to original sources
PubMed2006

Further enhancement of the thermostability of Hydrogenobacter thermophilus cytochrome c552.

Thermophile Hydrogenobacter thermophilus cytochrome c(552) (HT) is a stable protein with denaturation temperatures (T(m)) of 109.8 and 129.7 degrees C for the oxidized and reduced forms, respectively [Uchiyama, S., Ohshima, A., Nakamura, S., Hasegawa, J., Terui, N., Takayama, S. J., Yamamoto, Y., Sambongi, Y., and Kobayashi, Y. (2004) J. Am. Chem. Soc. 126, 14684-14685]. The removal of a single hydroxyl group from the hydrophobic core of HT, through the replacement of a Tyr by Phe, resulted in further elevation of the T(m) value of the oxidized form by approximately 6 degrees C, the T(m) value of the reduced one remaining essentially unaltered. As a result, the redox potential of the mutant with higher stability in the oxidized form exhibited a negative shift of approximately 20 mV relative to that of wild-type HT in an enthalpic manner. These findings indicated that the redox function of a protein can be enthalpically regulated through the stability of the oxidized form by altering the contextual stereochemical packing of hydrophobic residues in the protein interior using protein engineering.

Amino Acid Substitution↗
PubMed2006

Total arch replacement using a stepwise distal anastomosis for arch aneurysms with distal extension.

A total of 120 patients having arch to distal arch aneurysm with downstream extension underwent total arch replacement, with individual arch-vessel reconstruction through median sternotomy using a novel "stepwise" distal aortic anastomosis. Cardiopulmonary bypass was established by cannulating the right axillary artery and the ascending aorta or femoral artery. Hypothermia was at 22-28 degrees C. Through the aneurysm, the descending aorta was divided. Distal anastomosis using the stepwise technique was performed; a tube graft of length 7-12 cm was inserted into the descending aorta and anastomosed by running suture. The distal end of the inserted graft was extracted, and a further four-branched arch graft was joined to it. Selective cerebral perfusion was used for cerebral safety during arch repair. There were three hospital deaths (2.5%). Two patients (1.7%) developed permanent neurological dysfunction and three patients (2.5%) suffered transient cerebral deficits. Three patients (2.5%) required reentry for postoperative bleeding although in none of them bleeding was from the distal anastomosis site with the stepwise technique. Stepwise anastomosis is a useful and secure alternative for distal anastomosis in total arch replacement for arch to distal arch aneurysms with distal extension.

Aged↗
PubMed2006

Surgical outcome of aortic arch repair for patients with Takayasu arteritis.

BACKGROUND: Takayasu arteritis can cause segmental dilatation or stenosis of the aorta and its major branches, and surgical treatment of it is still difficult. Our objective was to review late results of aortic arch repair for patients with Takayasu arteritis. METHODS: Between 1987 and 2003, 21 patients underwent aortic arch repair under circulatory arrest. Diagnosis was performed by pathologic study of specimens for all patients. Total aortic arch repair was performed in 12 patients with separated branched grafts and in 2 patients with the island technique. Selective cerebral perfusion was used in 12 patients and retrograde cerebral perfusion in 2 patients in this type of surgery. Hemiarch replacement using retrograde cerebral perfusion was performed in 7 patients. Craniocervical vascular stenosis was found in 7 patients and aneurysm in 5 patients. The elephant trunk technique was used in 10 patients. The follow-up period was 6.2 +/- 4.2 years. RESULTS: There was one hospital death due to renal failure, and two late deaths, both of which were sudden. Late in follow-up, a patient who had undergone hemiarch replacement 12 years previously required total aortic arch repair for dilatation of the distal arch. Three patients required thoracoabdominal aortic repair and one patient descending aortic repair for residual aortic dilatation late in follow-up. Postoperative spinal infarction occurred in one patient who underwent hemiarch replacement. CONCLUSIONS: Surgical and late outcomes of aortic arch repair under circulatory arrest appear favorable, though late dilatation of the residual aorta is a matter of concern.

Acute Kidney Injury↗
PubMed2006

Prediction and incidence of atrial fibrillation after aortic arch repair.

BACKGROUND: Although atrial fibrillation is often associated with increased morbidity after open heart surgery, neither the incidence nor the clinical consequences of atrial fibrillation after aortic surgery has been well investigated. The goal of this study was to elucidate the risks for incidence of postoperative atrial fibrillation after aortic arch repair. METHODS: From January 1993 to February 2004, 483 patients with atherosclerotic aortic arch aneurysm (n = 327) or aortic dissection (n = 156) underwent total aortic arch repair. All patients operated on as elective, urgent, or emergency aortic arch repair were included. One hundred sixteen patients received surgery on an emergency basis because of rupture or acute type A dissection. Twenty-four patients had atrial fibrillation preoperatively. Potential predictors of postoperative atrial fibrillation were estimated by a logistic regression model. RESULTS: The incidence of postoperative, new onset of atrial fibrillation was 52.7% (242 of 459). The length of postoperative hospital stay was longer in patients with postoperative atrial fibrillation (48 +/- 52 days) than in patients without it (35 +/- 29 days; p = 0.001). The length of intensive care unit stay was also longer in patients with postoperative atrial fibrillation (12.1 +/- 23.2) than in patients without it (6.2 +/- 8.8; p = 0.002). Advanced age (p = 0.007; odds ratio = 1.34; 95% confidence interval: 1.14 to 1.62, per 10 years) was the only risk factor that correlated with postoperative new onset of atrial fibrillation. CONCLUSIONS: Atrial fibrillation was not uncommon after aortic arch repair. Advanced age was the only preoperative risk factor for postoperative atrial fibrillation.

Age Factors↗
PubMed2006

Surgical management of distal arch aneurysm: another approach with improved results.

BACKGROUND: Surgical treatment for distal arch aneurysm carries the risk of stroke. Although left thoracotomy has been used for repair of distal arch aneurysm as a standard approach, we have performed total arch replacement under deep hypothermia with circulatory arrest through a midsternotomy for this subset of aneurysms. METHODS: From January 1998 to February 2003, 119 patients underwent elective total arch replacement (mean age, 72.3 +/- 6.0 years) for distal arch aneurysm under deep hypothermia with circulatory arrest. Antegrade selective cerebral perfusion was used for brain protection. Arch vessels were independently reconstructed using quadrifurcated grafts. Concomitant procedures included tricuspid annuloplasty in 1 patient, aortic valve operations in 2, sinotubular junction plication in 6, and coronary artery grafting in 22. RESULTS: The early mortality rate was 0.84% (1 of 119). The mean duration of circulatory arrest was 67.1 +/- 19.7 minutes. Perioperative stroke rate was 0.84% (1 of 119). This stroke occurred 9 days postoperatively in an 81-year-old man with a history of cerebral infarction. Other complications were reexploration for bleeding in 1 patient (0.84%) and respiratory failure in 6 (5.0%). CONCLUSIONS: This operative approach for distal arch aneurysm featured a low mortality rate and low risk of perioperative stroke. Concomitant cardiac surgery could be performed routinely in standard fashion. Distal arch aneurysms that do not involve a large segment of the descending thoracic aorta can thus be repaired with low mortality and few cerebral complications through a midsternotomy.

Aged↗
PubMed2006

Limitations of EuroSCORE for measurement of risk-stratified mortality in aortic arch surgery using selective cerebral perfusion: is advanced age no longer a risk?

BACKGROUND: The European system for cardiac operative risk evaluation (EuroSCORE) is a risk stratification tool for perioperative mortality of cardiothoracic surgery that was developed in Europe and validated in North America in more than 500,000 patients. The operative mortality of aortic arch surgery has been improved by various novel operative techniques and adjuncts, whereas the number of such procedures for elderly patients has recently been increasing. The aim of this study was to examine the usefulness of the EuroSCORE, and our modification of it regarding age, in predicting mortality after aortic arch repair performed with selective cerebral perfusion. METHODS: We reviewed 358 consecutive patients with a mean age of 69 +/- 10 years undergoing aortic arch repair with selective cerebral perfusion between January 1993 and February 2004. Observed in-hospital mortality was compared with predicted mortality as determined by both additive and logistic EuroSCOREs. We also evaluated a version of the EuroSCORE modified for age, which was obtained by subtracting the contribution of age from the original EuroSCORE. Score validities were assessed by calculating the areas under receiver operating characteristic curves. RESULTS: Overall hospital mortality was 6.2% compared with 7.7% (additive EuroSCORE) and 11.8% (logistic EuroSCORE). Area under the receiver operating characteristic curve was 0.58 for the additive EuroSCORE and 0.58 for the logistic EuroSCORE as well. The overall age-unrelated EuroSCOREs were 5.1% (additive) and 5.2% (logistic), respectively, and areas under the receiver operating characteristic curve were 0.70 for additive and 0.69 for logistic. CONCLUSIONS: The original additive and logistic EuroSCOREs overpredicted mortality in this patient group, whereas the age-unrelated EuroSCORE was better in predicting mortality.

Age Factors↗
PubMed2006

Combined use of adamkiewicz artery demonstration and motor-evoked potentials in descending and thoracoabdominal repair.

BACKGROUND: We retrospectively reviewed the outcome of distal descending aortic and thoracoabdominal aortic repair with preoperative identification of the Adamkiewicz artery by magnetic resonance angiography and intraoperative monitoring of transcranial motor-evoked potentials. METHODS: We began combined use of demonstration of the Adamkiewicz artery and intraoperative recording of motor-evoked potentials for prevention of spinal cord complications in descending and thoracoabdominal aortic aneurysm repair in 1998. Ninety-two consecutive patients were studied, with descending aneurysm in 53 and thoracoabdominal aneurysm in 39 patients. The repair was performed through a left thoracic or thoracoabdominal incision, using partial cardiopulmonary bypass to prevent spinal cord injury. Magnetic resonance angiography revealed the Adamkiewicz artery in 70.7% of cases. During surgery, spinal cord ischemia was monitored using motor-evoked potentials. Anastomoses were performed using a segmental clamp technique to reduce spinal cord ischemic time. Based on the findings of magnetic resonance angiography and motor-evoked potentials, the Adamkiewicz artery and other relevant intercostals and lumbar arteries were revascularized or preserved, or both. RESULTS: The mean durations of partial cardiopulmonary bypass, cross-clamping, and surgery, respectively, were 144.4 +/- 232.2, 106.0 +/- 65.5, and 411.8 +/- 170.7 minutes. Three hospital deaths (3.3%) occurred in patients with a thoracoabdominal aortic aneurysm. Motor-evoked potentials changed in 9 patients (9.8%), in 8 (88.9%) of whom they were eventually restored. Although paraplegia developed in 1 patient (1.1%) with a mycotic descending aneurysm, the other patients survived without spinal cord injury. CONCLUSIONS: Combined visualization of the Adamkiewicz artery and determination of motor-evoked potentials are useful in preventing spinal cord injury in descending and thoracoabdominal aortic repair.

Adult↗
PubMed2006

Long-term recovery of exercise ability after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.

BACKGROUND: The exercise capacity of patients with thromboembolic pulmonary hypertension was investigated to clarify the long-term effects of pulmonary endarterectomy. This capacity was assessed by measuring cardiopulmonary factors during cardiopulmonary exercise testing at the maximal level of exercise and a 6-minute walk test at the submaximal level. Their survival rate was also determined. METHODS: We conducted a retrospective review of the clinical records of 102 patients who underwent pulmonary endarterectomy (63 women; median age, 53 years). RESULTS: Eight (7.8%) hospital mortalities were encountered. Three late mortalities due to fulminant hepatitis, breast cancer, and pneumonia in a patient under steroid therapy were unrelated to pulmonary endarterectomy. The actual survival rate including hospital mortalities was 90.9% at 3 years and 84.0% at 5 years. All hemodynamic measurements significantly improved and reached a plateau 1-month after endarterectomy. The cardiopulmonary exercise test at the maximal exercise level revealed that peak oxygen uptake (V(O2)) baseline was 13.8 +/- 3.2 mL/min/kg, and at 1-month was 16.2 +/- 4.2 mL/min/kg (p = 0.0015) and ventilatory response to carbon dioxide production (V(E)-V(CO2)) slope baseline was 46.5 +/- 8.4 mL/min/kg, and at 1-month was 39.9 +/- 7.4 (p = 0.0006), which gradually and significantly improved during the first year after endarterectomy (peak V(O2), 19.9 +/- 3.9 mL/min/kg [p < 0.0001] and V(E)-V(CO2) slope, 33.2 +/- 5.4 mL/min/kg [p <0.0001]). The 6-minute walk test, which reflects the systemic response at the submaximal level of functional capacity, showed that the walking distance gradually and significantly increased for up to 1 year after endarterectomy (baseline, 358 +/- 102 meters [m]; at 1-month, 433 +/- 105 m; and at 1-year, 490 +/- 80 m [p < 0.0001]) and then reached a plateau. CONCLUSIONS: After pulmonary endarterectomy, the hemodynamic recovery occurred immediately, and the patients' exercise capacity improved during the year. The 6-minute walk test was a good indicator to assess the recovery of exercise capacity.

Adult↗
PubMed2006

Japanese single-center experience of surgery for chronic thromboembolic pulmonary hypertension.

BACKGROUND: We review the outcome of surgery for chronic thromboembolic pulmonary hypertension (CTEPH). METHODS: Between 1995 and 2004, 88 patients underwent surgery for CTEPH. Mean pulmonary artery pressure and pulmonary vascular resistance were 46 mm Hg (range, 23 to 70 mm Hg) and 986 dynes.sec(-1).cm(-5) (298 to 2,231 dynes.sec(-1).cm(-5)). The pulmonary artery lesion was proximally located in 51 patients, subsegmental in 34 patients, and peripheral in 3 patients. Pulmonary endarterectomy was performed using cycles of 15-minute intermittent circulatory arrest followed by 10-minute reperfusion at 16 degrees C to 18 degrees C. RESULTS: The median durations of circulatory arrest, cardiopulmonary bypass, and surgery were 58, 217, and 355 minutes, respectively. Percutaneous extracorporeal membrane oxygenation was used in 8 patients (9.1%) who had difficulty being weaning from cardiopulmonary bypass. Three recent patients for whom this was performed promptly were weaned and survived. There were 7 hospital deaths (8.0%, including 6 30-day deaths) from pulmonary bleeding in 2 patients, residual pulmonary hypertension in 3, rupture of bulla in 1, and empyema in 1. In the 81 survivors, mean pulmonary artery pressure and pulmonary vascular resistance fell significantly after surgery (p < 0.0001, each case). Age more than 60 years was a risk factor for hospital mortality on multivariate analysis. Although distal pulmonary artery disease including subsegmental and peripheral lesions was not a significant risk factor for mortality, it did influence patient recovery: the frequency of percutaneous extracorporeal membrane oxygenation was higher and hemodynamic improvement less pronounced in patients with distal disease. The actuarial survival rate was 90.7% at 3 years and 86.4% at 5 years. None of the patients have suffered recurrence. The event-free rate was 97.1% at 3 years and 93.5% at 5 years. Of the 68 patients surviving for more than 1 year after surgery, 67.6% were successfully weaned from home oxygen therapy and 13.2% required only occasional use of oxygen. CONCLUSIONS: Pulmonary endarterectomy can be safely performed with relatively low mortality and favorable prognosis with long-term survival, although it should be performed carefully for patients with distal disease.

Adult↗
PubMed2006

Monoparesis after graft replacement of non-ruptured abdominal aortic aneurysm.

A 67-year-old man was admitted with a saccular aneurysm of the abdominal aorta. Preoperative CT revealed cylindrical calcification of the abdominal aorta and the patent internal iliac arteries (IIAs). At the elective surgery, a cylinder-shaped and severely calcified intimal layer was found, and the lumbar arteries were totally occluded. Hypotension caused by the loose iliac clamp due to severe calcification continued for 15 minutes and long-time cross clamp was necessary. Monoparesis of the left lower extremity and dysuria occurred postoperatively. Spinal MRI revealed small infarction at the Th10 level. Symptoms improved and he could walk with a cane and within a few months no uninary catheter support was needed. Thoracic spinal cord infarction after abdominal aortic aneurysm (AAA) surgery and a severely calcified abdominal aorta indicated the importance of the blood flow in the IIA as the significant source of spinal blood supply. To prevent spinal cord injury (SCI) which is rare but significant complication of AAA surgery, understanding of the spinal blood supply, quick surgery, and complete revascularization of pelvic arteries are important.

Aged↗
PubMed2005

Surgical treatment of aortic regurgitation due to Takayasu arteritis: long-term morbidity and mortality.

BACKGROUND: The goal of this retrospective study was to determine the late outcome of surgical treatment for aortic valve regurgitation due to Takayasu arteritis and correlate it with evidence of inflammation on pathological examination. METHODS AND RESULTS: Ninety consecutive patients who underwent surgery for aortic valve regurgitation due to Takayasu arteritis between 1979 and 2003 were studied. Intraoperative pathological specimens of the aortic wall from 69 patients were retrospectively examined for inflammation. Aortic valve replacement was performed in 63 patients (group A) and composite graft repair in 27 patients (group B). The aortic root diameter was 39.9+/-9.5 mm in group A and 54.4+/-13.6 mm in group B (P<0.0001). Preoperative steroid therapy was performed in 40 patients (44.4%). Hospital mortality was 4.8% (3/63) in group A and 7.4% (2/27) in group B. The overall 15-year survival rate was 76.1%. Detachment of the valve or graft occurred in 11.1% (7/63) of group A and in 3.7% (1/27) of group B patients (P=0.43). Late dilatation (>50 mm) of the residual ascending aorta occurred in 11.1% (7/63) of group A and in 3.7% (1/27) of group B patients (P=0.43). Active inflammation was confirmed in intraoperative pathological specimens of 10 patients, and detachment of the valve or graft occurred in 4 of these patients. Univariate analysis of background variables revealed active inflammation to be a risk factor for detachment (P=0.0001; risk ratio 55). CONCLUSIONS: Late dilatation of the ascending aorta after aortic valve replacement is a clinically important finding. Active inflammation could be related to valve or graft detachment.

Adult↗
PubMed2005

Multivariate analysis of predictors of late stroke after total aortic arch repair.

OBJECTIVE: The number of aortic surgeries has recently increased, with improvement of outcome due to the development of various novel operative techniques and adjuncts. Although the postoperative incidence of stroke, the most severe complication of aortic surgery, is still a matter of concern and has been described well previously, late stroke after aortic arch repair has not been described well. We assessed the incidence and predictors of late stroke after total aortic arch repair. METHODS: From January 1993 to December 2003, 470 patients underwent total aortic arch repair in our institution. All patients, whether undergoing elective, urgent, or emergent aortic arch repair, were included. Emergent operation was required for 115 patients because of rupture or acute type A dissection. For brain protection, retrograde cerebral perfusion was used in 27% (125) and selective cerebral perfusion in 75% (353) of cases. The follow-up period was 32.5+/-31.5 months. Late stroke was defined as stroke occurring more than 30 days postoperatively. RESULTS: The incidence of early postoperative stroke was 4.9% (23/470), while that of late postoperative stroke was 6.0% (28/470). On univariate analysis, postoperative atrial fibrillation (P=0.014), preoperative prevalence of craniocervical lesions (P=0.0001), and advanced age (P=0.046) were each significantly related to late stroke. A Cox proportional hazards model detected postoperative atrial fibrillation (P=0.013, OR=3.02, 95% CI: 1.26-7.24) and preoperative prevalence of craniocervical lesions (P=0.0001, OR=5.37, 95% CI: 2.30-12.52) as predictors of late stroke. CONCLUSIONS: Postoperative atrial fibrillation and preoperative prevalence of craniocervical lesions were found to be risk factors for late stroke after total aortic arch repair.

Acute Disease↗
PubMed2005

Sustained upregulation of inflammatory chemokine and its receptor in aneurysmal and occlusive atherosclerotic disease: results form tissue analysis with cDNA macroarray and real-time reverse transcriptional polymerase chain reaction methods.

BACKGROUND: Although cytokines are known to be pivotal in the development of atherosclerotic diseases, few data exist regarding their expressions in the established stages such as aneurysmal or occlusive lesions. Therefore, in the present study the gene expression levels of cytokine-related substances in abdominal aortic aneurysm (AAA) and carotid artery stenosis (CAS) were determined using cDNA macroarray and real-time reverse transcriptase polymerase chain reaction (RT-PCR) methods. METHODS AND RESULTS: Tissue samples were obtained from 31 patients with AAA and 24 with CAS. The array-specific [33P]-labeled cDNA probe mixture synthesized from 2.5 microg total RNA with gene-specific primers was hybridized with nylon membranes containing 375 cDNA clones. Densitometric analysis confirmed differences in expression (>5-fold) for 97 of the cytokine-related gene products between AAA and adjacent control tissue. Among these, simultaneous upregulation was found in the expression of interleukin (IL)-8 (9-fold) and its receptor, CXCR-2 (11-fold). Thus, the expressions of IL-8 and CXCR-2 were further quantified by real-time RT-PCR. The expression of both the genes was significantly upregulated in both AAA and CAS compared with control regions as followed: IL-8=0.53+/-0.16 vs 0.11+/-0.04 (p<0.01); CXCR-2=2.04+/-0.75 vs 0.29+/-0.10 (p<0.01) in AAA, and IL-8=1.35 +/-0.25 vs 0.60+/-0.16; CXCR-2=2.00 +/-0.51 vs 0.58+/-0.21 (p<0.05) in CAS. Under these conditions, the gene expressions of monocyte chemotactic protein-1 and its receptor, CCR-2, were not significantly different in the control and diseased regions of both AAA and CAS. CONCLUSIONS: Sustained upregulation of IL-8 and CXCR-2 was observed in both AAA and CAS, suggesting the inflammatory process is still active in established dilated and occlusive atherosclerotic diseases. Whether upregulation of this system could be protective or not protective for disease development requires further study.

Aged↗
PubMed2005

Successful surgical treatment for aneurysm of splenic artery with anomalous origin.

The splenic artery is the third common site of an infrarenal abdominal arterial aneurysm after the abdominal aorta and iliac arteries, and the most common site of a visceral artery aneurysm. It is a rare, but clinically important form of vascular disease with the potential for life-threatening rupture. We report a 64-year-old woman with a splenic artery aneurysm. Though she was asymptomatic, calcification around the left upper quadrant was incidentally detected. A saccular aneurysm with calcification located in the proximal portion of the splenic artery was detected by computed tomography (CT). Anomalous origin of the splenic artery, from the superior mesenteric artery (SMA), was also detected. Aneurysmal resection without splenectomy was carried out successfully. A suitable approach to aneurysms must be selected in each case, because the splenic artery exhibits congenital anomaly in 10% of all the people.

Aneurysm↗