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Biomedical subjects

S Shirakata

Publications and source records attributed to S Shirakata.

At least 19 recordsLinked to original sources
PubMed1999

Plausible phosphoenolpyruvate binding site revealed by 2.6 A structure of Mn2+-bound phosphoenolpyruvate carboxylase from Escherichia coli.

We have determined the crystal structure of Mn2+-bound Escherichia coli phosphoenolpyruvate carboxylase (PEPC) using X-ray diffraction at 2.6 A resolution, and specified the location of enzyme-bound Mn2+, which is essential for catalytic activity. The electron density map reveals that Mn2+ is bound to the side chain oxygens of Glu-506 and Asp-543, and located at the top of the alpha/beta barrel in PEPC. The coordination sphere of Mn2+ observed in E. coli PEPC is similar to that of Mn2+ found in the pyruvate kinase structure. The model study of Mn2+-bound PEPC complexed with phosphoenolpyruvate (PEP) reveals that the side chains of Arg-396, Arg-581 and Arg-713 could interact with PEP.

Animals↗
PubMed1999

Crystallization and preliminary x-ray diffraction studies of C4-form phosphoenolpyruvate carboxylase from maize.

Phosphoenolpyruvate carboxylase is a key enzyme in the fixation of atmospheric CO(2) in C(4) and crassulacean acid metabolism (CAM) plants. The enzyme catalyzes the irreversible carboxylation of phosphoenolpyruvate to form oxaloacetate and inorganic phosphate, the first committed step in the fixation of external CO(2) in these plants. The enzyme has been isolated from maize leaves and crystallized using the hanging-drop vapour-diffusion method with PEG 8000 as a precipitant at pH 7.5. The crystals belong to space group C222(1), with unit-cell dimensions a = 160.2, b = 175.6, c = 255.5 A, and diffract to 3.2 A resolution.

Crystallization↗
PubMed1997

[3 Cases of blunt chest trauma].

3 Cases of blunt chest trauma were reported, including aortic isthmus rupture, diaphragmatic injury and right main bronchial rupture. All cases were injured by traffic accidents. The first case was a 21-year-old man complicated with aortic injury and femoral bone fracture and died of intrapleural rupture before thoracotomy. The second case was a 49-year-old man who had right 11th rib fracture and he received emergent thoracotomy due to hemorrhagic shock. We found accidentally arterial massive bleeding by the diaphragmatic injury at thoracotomy and ligated directly. The third case was a 19-year-old man and he was unconscious on admission and rupture of the right main bronchus was found by bronchofiberscope and performed pneumectomy. One patient died and other two patients have survived. Blunt chest trauma sometimes lead to fatal damage of vital organs. So it is necessary to make early diagnosis and perform the emergent operations for life salvage.

Accidents, Traffic↗
PubMed1993

Rhabdomyosarcoma in the inferior vena cava with secondary Budd-Chiari syndrome.

A 63-year-old man with symptoms of obstruction of the inferior vena cava was examined by computed tomography, ultrasound imaging and angiography. Examination revealed a tumor in the inferior vena cava, and transvenous biopsy revealed a rhabdomyosarcoma. The tumor was surgically resected and was easily separated from the surrounding tissues. Nevertheless, a local recurrence developed 43 days after the operation, and the patient's condition deteriorated rapidly. Hepatomegaly and ascites believed to represent the Budd-Chiari syndrome were noted. The patient died on the 163rd postoperative day. Autopsy revealed a tumor extending from the inferior vena cava just above the right renal vein to the right atrium and involving the lobus caudatus of the liver. Clinically, the tumor was thought to have arisen from the middle segment of the inferior vena cava. However, a diagnosis of primary hepatic rhabdomyosarcoma with extrahepatic growth could not be excluded. Only 12 cases of primary liver rhabdomyosarcoma have been reported, and none of those patients demonstrated Budd-Chiari syndrome. Our patient, diagnosed as rhabdomyosarcoma with secondary Budd-Chiari syndrome, is believed to be the first such report.

Budd-Chiari Syndrome↗
PubMed1992

[A ruptured thoracic aortic aneurysm with 4 cm diameter].

The size of a thoracic aortic aneurysm (TAA) is an important factor of the operative indication. We experienced a ruptured TAA the diameter of which was only 4 cm. A 71 years old man was admitted due to the severe back pain under the shocked condition. We diagnosed him a ruptured TAA by CT scan. Because he had no progressive anemia and the hemodynamics was very stable, we followed him conservatively. Two months later, the operation was performed. We resected the aneurysm and inserted an aortic prosthetic graft. From the operative findings, the aneurysm was certified as a true aneurysm, and the maximal diameter was only 4 cm. First choice for the treatment of ruptured TAA is the emergent operation. But when the hemodynamics is extremely stable and the anemia does not progress at all, a conservative therapy can be selected. Even if the aneurysm is very small, the control of hypertension is quite important.

Aged↗
PubMed1990

[A case of "chronic expanding hematoma", with an intrapulmonary fresh hemorrhage resected 25 years after thoracic injury].

A case of a 60-year-old man who had a chronic expanding hematoma with an intrapulmonary fresh hemorrhage in the right thorax is reported. He suffered blunt trauma of his right thorax in a traffic accident 25 years ago. He has no symptoms and signs after the accident. But he had hemoptysis twice and he was taken to our hospital. He underwent the resection of the chronic expanding hematoma and right lower lobe of the lung. The surgical specimen consisted of the hematoma measuring 17 x 13 x 6 cm. The chronic expanding hematoma contained aseptic brownish muddy substances. The patient recovered without complications and hemoptysis. Chronic expanding hematomas occur in many locations, often simulating neoplasms. Although the mechanism of chronic expanding hematoma is unclear, the self-perpetuating expanding nature of the lesion may appear to be due to the irritant effects of blood and its breakdown products, causing repeated exudation or bleeding from capillaries in the granulation tissue.

Chronic Disease↗
PubMed1989

Successful correction of a Collett Edwards type II truncus arteriosus after bilateral pulmonary artery banding--a case report.

A case of a 4-year-old girl who underwent successful correction of a Collett Edwards type II truncus arteriosus following bilateral pulmonary artery banding is reported herein. The diagnosis of Collett Edwards type II truncus arteriosus was made when she was 5 months of age, after which the bilateral pulmonary artery banding was performed. This proved very effective and enabled elective radial surgery to be done. The radical operation was performed safely by a modified version of Rastelli's procedure. The patient had an uneventful recovery and is now well with no symptoms one year following her operation.

Child, Preschool↗
PubMed1989

[Central neurocytoma. Case report].

A 24-year-old female was hospitalized for progressive headache and nausea. Computed tomography showed a mass lesion in the left lateral ventricle near the foramen of Monro. On light microscopy, this tumor morphologically resembled an oligodendroglioma. However, ultrastructural examination disclosed synapses and neuronal differentiation. Review of the literature revealed 21 cases of intraventricular neuronal tumors in adults that were diagnosed as central neurocytoma or differentiated neuroblastoma. Fourteen of the 21 patients were males and seven were females. Their ages ranged from 16 to 52 years and averaged 30.7 years. All of the tumors were located near the foramen of Monro and the clinical symptoms were primarily headache and nausea. The outcome was generally good. Surgical removal was the most effective treatment, whereas the effect of radiation therapy was unclear. The diagnosis requires demonstration of neuronal differentiation. Generally, the diagnosis is neurocytoma if the neuronal tissue is mature, with complete synapses, and neuroblastoma if it is immature. However, the criteria for differentiation between these two tumors are still controversial.

Adult↗
PubMed1989

[The successful surgery of lung abscess formed from pulmonary aspergilloma in a patient with recurrence of acute promyelocytic leukemia during remission induction therapy].

This is a case report of a successful case of surgical treatment of a lung abscess formed from pulmonary aspergilloma in a patient with a recurrence of acute promyelocytic leukemia during remission induction therapy. A 39 year-old woman was admitted to our hospital for remission induction therapy of a recurrence of acute promyelocytic leukemia. We were successful in bringing her to a state of complete remission by a therapy of a intermediate-dose of Ara-C. Pulmonary aspergilloma was formed in the right lung during therapy. We performed transbronchial infusions to Amphotericin B which dissipated the fungus ball. However, a lung abscess was formed. We needed radical therapy, and there were no complications in the following surgical treatment. Recently, along with the tendency for the use of stronger chemotherapy treatment regimes for acute leukemia, there has been an increase of the number of mycosis cases such as the pulmonary aspergilloma case reported here. Accordingly, surgical treatment is becoming more and more a matter of necessity in the clinical course of leukemia patients.

Adult↗
PubMed1989

[Postoperative thromboembolism of acquired mitral valve disease--comparison between valve replacement and commissurotomy].

Thromboembolism after mitral commissurotomy (MC) was compared with that after mitral valve replacement (MVR). In 216 surgical cases of acquired mitral valve diseases, including combined operative cases of other valves, thromboembolic complications after MC were observed in 9/137 cases (13 times, 0.94%/patient-year), and those after MVR in 8/70 cases (11 times, 2.55%/patient-year). No thromboembolism occurred in 9 cases of annuloplasty. Thromboembolism-free period after MVR (49 +/- 44 months) was significantly shorter than that after MC (102 +/- 43 months, p less than 0.05). Postoperative CTR of thromboembolic cases (69.5 +/- 8.2%) was significantly larger than that of non-thromboembolic cases (61.4 +/- 9.9%) in MVR group (p less than 0.005), but no significant difference existed between thromboembolic and non-thromboembolic cases in MC group. Thromboembolism after MVR occurred in severe cases, but that after MC often occurred in mild cases. Postoperative echocardiogram of MC group showed significantly lower DDR in thromboembolic cases (1.9 +/- 0.7 cm/sec) than in non-thromboembolic cases (3.2 +/- 1.2 cm/sec, p less than 0.025). Mitral valve area (MVA) of all re-stenotic cases in thromboembolic cases after MC was under 1.5 cm2, comparing that in non-thromboembolic cases there were only two cases that had MVA under 1.5 cm2. After MC, careful management including anticoagulant therapy and reoperation is necessary especially in patients with atrial fibrillation, DDR under 2 cm/sec, and MVA under 1.5 cm2, even though they don't have cardiomegaly.

Adult↗
PubMed1988

[Late occlusion at the anastomosis site of an extended polytetrafluoroethylene (E-PTFE) graft with small caliber].

Recently expanded polytetrafluoroethylene (E-PTFE) graft is often used in arterial bypass for atherosclerosis obliterans. In our series of 38 patients (48 legs) undergoing femoropopliteal bypass with E-PTFE graft of 6mm-caliber, a cumulative patency rate was 40.8% at 36 months after operation and a mean duration of patency was 26.3 months. To clarify the cause of occlusion, the diseased grafts were removed and histopathologically examined. Macroscopically, the E-PTFE graft was occluded by the intimal hyperplasia, so called pannus ingrowth from the recipient artery into the graft. The pannus formation of the graft was more remarkable in the distal than in the proximal site of anastomosis, suggesting the influence of blood flow on its formation. Microscopically, no endothelial cells were observed inside the E-PTFE graft except for the surface of pannus. Thus, less extension of endothelialization was thought to be a cause of late occlusion in E-PTFE grafts. Most desirable is the autologous saphenous vein for femoropopliteal bypass. However, when it is not available, E-PTFE graft with a larger caliber must be used in combination with postoperative anticoagulant therapy.

Arteriosclerosis Obliterans↗
PubMed1988

[Development of a small caliber vascular graft using a connective tissue tube with temporary antithrombogenicity].

A connective tissue tube containing collagen fibrils and capillary blood vessels is an ideal material for artificial artery, since the collagen fibrils compose an excellent supporting framework for cell migration and proliferation and the endothelial cells of the capillary can be the origin of the endothelialization of the graft. However, its thrombogenicity has remained a problem. This experiment was designed to develop a small caliber (3mm) vascular graft using an autogenous connective tissue provided with temporary antithrombogenicity. A tube knitted of ultra-fine polyesters was implanted subcutaneously in the back of mongrel dogs for three weeks. Thus accomplished connective tissue grafts were heparinized ionically in vitro, using cross-link agents. Then the treated grafts, 5-6 cm in length and 3mm in diameter, were segmentally replaced with bilateral carotid arteries. During the follow-up period up to 55 days, 7 of 8 grafts (88%) were patent. Histological examinations revealed that there was no thrombus and the neointima formation with a lining of endotherial cells was completed, extending overall length of the grafts. Thus, newly devised hybrid type of connective tissue graft is thought to be usefull for a replacement for arteries with a small caliber.

Animals↗