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K Oohara

Publications and source records attributed to K Oohara.

At least 19 recordsLinked to original sources
PubMed2003

[Minimally invasive video-assisted thoracic surgery using radially expanding trocars].

We report a new and safer access device for thoracoscopic operation. This radially expanding trocar provides a smaller incision of skin and a lesser visceral, vascular or neural injury than a conventional cannula. Therefore, most of patients undergoing this operation do not feel much pain. Moreover, this device system is more cost effective than a conventional one. We prefer and recommend this minimally invasive technique for video-assisted thoracic surgery.

Equipment Design↗
PubMed2001

Stable operation of a 300-m laser interferometer with sufficient sensitivity to detect gravitational-wave events within our galaxy.

TAMA300, an interferometric gravitational-wave detector with 300-m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations; the interferometer was operated for over 10 hours stably and continuously. With a strain-equivalent noise level of h approximately 5x10(-21)/sqrt[Hz], a signal-to-noise ratio of 30 is expected for gravitational waves generated by a coalescence of 1.4M-1.4M binary neutron stars at 10 kpc distance. We evaluated the stability of the detector sensitivity with a 2-week data-taking run, collecting 160 hours of data to be analyzed in the search for gravitational waves.

Astronomy↗
PubMed1998

Infective endocarditis complicated by mycotic cerebral aneurysm: two case reports of women in the peripartum period.

Mycotic cerebral aneurysm is a relatively rare but very serious complication of infective endocarditis. Infective endocarditis is a rare but a potentially fatal complication of pregnancy. We report here two very rare cases of infective endocarditis associated with mycotic cerebral aneurysm in peripartum women. In one case, cardiac surgery was performed prior to cerebral surgery and after delivery. In the other case, emergency cerebral surgery was performed due to rupture on the day cardiac surgery had been scheduled, 45 days after delivery. The surgical management of a patient with infective endocarditis and mycotic cerebral aneurysm is reviewed. The surgical strategy for a pregnant patient is also reviewed.

Adult↗
PubMed1997

Body temperature influences regional tissue blood flow during retrograde cerebral perfusion.

OBJECTIVE: This study compared the cerebral microcirculation during retrograde cerebral perfusion with that during antegrade cardiopulmonary bypass under normothermic and hypothermic conditions. METHODS: Brain tissue blood flow was measured with the hydrogen-clearance and colored microsphere (15 and 50 microns) methods during antegrade cardiopulmonary bypass and retrograde cerebral perfusion. Measurements were performed during normothermia (37 degrees C), moderate hypothermia (28 degrees C) and deep hypothermia (20 degrees C) in groups of mongrel dogs (n = 8). RESULTS: During antegrade cardiopulmonary bypass, the microsphere method showed a significant decrease in cerebral blood flow as body temperature decreased (40.1 +/- 20.8 ml/min/100 gm at 37 degrees C, 16.2 +/- 18.0 ml/min/100 gm at 20 degrees C with 50 microns microspheres) At 20 degrees C, the cerebral blood flow measured with the 15 microns microspheres was significantly lower than that assessed with the hydrogen-clearance method (11.3 +/- 7.0 vs 24.8 +/- 7.0 ml/min/100 gm). During retrograde cerebral perfusion, the microsphere method also showed a significant decrease in cerebral blood flow with cooling. At 37 degrees C, the cerebral blood flow measured with the 15 microns microspheres (0.8 +/- 0.7 ml/min/100 gm) was significantly lower than that assessed with the hydrogen-clearance method (10.1 +/- 3.5 ml/min/100 gm). At both 28 degrees and 20 degrees C, the hydrogen-clearance method showed significantly higher cerebral blood flow (10.1 +/- 5.8 and 8.2 +/- 3.7 ml/min/100 gm) than did the 50 microns microspheres (1.8 +/- 0.6 and 1.0 +/- 0.8 ml/min/100 gm) and 15 microns microspheres (0.23 +/- 0.14 and 0.18 +/- 0.15 ml/min/100 gm). CONCLUSION: (1) Cerebral blood flow that shunts to capillaries is increased during antegrade cardiopulmonary bypass under deep hypothermia. (2) During retrograde perfusion, the majority of the blood flow shunts away from brain capillaries, even under normothermic conditions, and blood flow through large venoarterial shunts increases as body temperature decreases. Although the cerebral microcirculation during retrograde perfusion is decreased, retrograde perfusion provides some degree of oxygenation to the body.

Animals↗
PubMed1996

Histological evidence for cholinergic alteration in the hippocampus following entorhinal cortex lesion.

The initial stage of Alzheimer's disease is characterized by neuropathological alteration in the entorhinal cortex. To model one aspect of the neurodegeneration observed and to investigate anatomical changes of the hippocampus associated with unilateral entorhinal cortex lesion, excitotoxin ibotenic acid was used to produce selective unilateral neuronal loss in rat entorhinal cortex. Histological and morphometrical analyses confirmed excitotoxic lesion of the entorhinal cortex after 3 months and showed a decrease of acetylcholineste-rase-stained fibers in the stratum moleculare of the dentate gyrus and the stratum radiatum of the CA3 field. This study demonstrates the importance of the entorhinal cortex in the hippocampal cholinergic function which appears to be important to memory and learning, and raises the possibility that memory deficit in Alzheimer's disease may be associated with partial neuronal loss in the entorhinal cortex.

Acetylcholinesterase↗
PubMed1996

[Mobile right atrial thrombus: a case report of surgical removal].

A 71-year-old man was admitted due to brain infarction. An abnormal floating mass was found in the right atrium by echocardiography. The mass was assumed to be a thrombus. The patient was failed to be in danger of pulmonary embolism, so it was decided to remove surgically. The thrombus was removed under cardiopulmonary bypass including the atrial wall where it was attached, because it was difficult to rule out the possibility of cardiac tumor macroscopically. The tumor showed pathological findings of thrombus. Postoperative course was uneventful.

Aged↗
PubMed1996

[Pre-emptive analgesia from intravenous administration of opioid: no effect with pentazocine].

The influence of timing of administration of preoperative pentazocine on pain and analgesic requirements after surgery was studied in 46 patients undergoing total abdominal hysterectomy. Twenty-three patients received thiamylal 5 mg.kg-1 on induction of anesthesia, followed by pentazocine 30 mg or 60 mg before surgical incision (group A). Twenty-three control patients received pentazocine 30 mg or 60 mg, 5 min after abdominal incision (group B). The visual analogue scales for pain 24 h after operation were 6.0 cm at 30 mg dose in group A or 5.3 cm at 60 mg dose in group A and 5.7 cm at 30 mg dose in group B or 4.7 cm at 60 mg dose in group B. There were no differences in the visual analogues scales. Pentazocine consumption in the first 24 h after surgery was 67.5 mg at 30 mg dose in group A or 52.5 mg at 60 mg dose in group A and 70.9 mg at 30 mg dose in group B or 51.8 mg at 60 mg dose in group B. We conclude that postoperative pentazocine consumption and pain scores are no different when pentazocine is given before or after skin incision for abdominal hysterectomy and that there is no clinically useful pre-emptive analgesic effect with these doses of pentazocine.

Adult↗
PubMed1995

Regional cerebral tissue blood flow measured by the colored microsphere method during retrograde cerebral perfusion.

Brain tissue blood flow was measured precisely by the colored microsphere method during retrograde cerebral perfusion in 10 normothermic mongrel dogs. The average tissue blood flow rates to the cerebral cortex, cerebral medulla, brain stem, cerebellum, and spinal cord during retrograde cerebral perfusion at 25 mm Hg of external jugular venous pressure were 10.5 +/- 10.3, 4.2 +/- 4.6, 11.1 +/- 9.8, 12.3 +/- 8.6, and 9.1 +/- 5.8 ml/min per 100 gm, respectively. The brain was perfused wholly by retrograde cerebral perfusion without lateralization. Total cerebral blood flow was calculated as the sum total rates of blood flow to each area. Total cerebral blood flow during retrograde cerebral perfusion at 25 mm Hg was 7.8 +/- 4.4 ml/min, which represented 3.5% +/- 1.9% of whole body blood flow and one third of the total cerebral blood flow (28.0 +/- 4.2 ml/min) during cardiopulmonary bypass at a flow rate of 1000 ml/min. Oxygen consumption and carbon dioxide elimination by the total cerebrum during retrograde cerebral perfusion at 25 mm Hg were 0.54 +/- 0.23 ml/min and 34 +/- 15 mumol/min, respectively, or 8.6% +/- 3.6% and 7.0% +/- 3.1% of the corresponding whole body value and represented about one third of that measured during cardiopulmonary bypass (1.21 +/- 0.39 ml/min and 96 +/- 15 mumol/min). Total cerebral blood flow, total cerebral oxygen consumption, and carbon dioxide elimination increased as the external jugular venous pressure increased from 15 to 25 mm Hg; however, no further increase occurred once the external jugular venous pressure exceeded 25 mm Hg.

Animals↗
PubMed1995

[Epidemiological study of the prognosis and relevant factors of demented patients].

One hundred twenty patients diagnosed as having dementia at the Center for Elderly Dementia in Hyogo College of Medicine, were recruited for this study to investigate the factors related to the prognosis of dementia. Patients were classified into the following two groups: those staying at home (group 1); those who died at home (group 2). The proportion of various dementias was almost equal in each group: vascular dementia, 30%; senile dementia of Alzheimer's type, 40%; mixed dementia, 20%; Alzheimer's disease, 10%. The average duration of disease in the two groups were not significantly different. The average age of onset in group 2 was higher than that in group 1. The rate of those with severe dementia was higher in group 2 than group 1. Those in group 2 scored less on the Mini-Mental State examination than those in group 1. Symptoms of dementia were assessed by the modified GBS-scale. In group 2, patients scored higher in impaired intellectual and motor functions. The CT findings suggested cortical atrophy, ventricular enlargement and periventricular lucency more often in group 2 than in group 1. Laboratory findings revealed that decrease in red blood cell count, hemoglobin, hematocrit and serum protein were more apparent in group 2 than group 1. It was considered that impaired motor functions, cortical atrophy, white matter lesions, anemia and malnutrition enhanced the probability of death. The study has confirmed that the prognosis of dementia is not only related to intellectual impairment but also deteriorated physical conditions such as motor dysfunction, anemia and malnutrition.

Aged↗
PubMed1995

Acute aortic dissection, aortic insufficiency, and a single coronary artery in a patient with Turner's syndrome.

A rare case of acute aortic dissection and aortic regurgitation in a patient with Turner's syndrome is reported. A 25-year-old woman with a history of Turner's syndrome presented to our hospital with complaints of chest pain and dyspnea. Emergent surgery was performed after chest roentgenography and two-dimensional echocardiography. Intraoperatively, the patient was found to have a single coronary artery and a bicuspid aortic valve. The patient was treated successfully with a composite graft consisting of a 24 mm woven dacron graft, a 21 mm St. Jude Medical aortic prosthetic valve, and an equine pericardial skirt. The composite graft was inverted into the ascending aorta and connected to a small coronary artery graft. The patient's postoperative course was uneventful. A cardiac catheterization was performed postoperatively and revealed a competent anastomotic site and no evidence of aortic regurgitation. We provide a brief review of coronary anomalies and aortic diseases associated with patients with Turner's syndrome. The most commonly associated complications include coarctation of the aorta and bicuspid aortic valve disease. The incidence of coronary anomalies in patients with Turner's syndrome is maybe rare.

Acute Disease↗
PubMed1994

Determination of organ blood flows during retrograde inferior vena caval perfusion.

Cerebral, renal, and hepatic blood flows and oxygen metabolism were measured in 8 mongrel dogs undergoing hypothermic (20 degrees C) retrograde perfusion via the inferior vena cava (IVC) and compared with cardiopulmonary bypass and retrograde superior vena caval perfusion. Inferior vena caval perfusion was performed with aortic drainage and clamping of the superior vena cava at an IVC pressure of 20 or 30 mm Hg. Cerebral, renal, and hepatic blood flows at 30 mm Hg of IVC pressure were 7.5 +/- 3.8, 8.1 +/- 3.1, and 15.3 +/- 5.5 mL.min-1.100 g-1, respectively, as determined by the hydrogen clearance method. Organ blood flows during retrograde IVC perfusion were 28%, 42%, and 57% of cardiopulmonary bypass values at a flow rate of 1,000 mL/min and 61%, 119%, and 131% of retrograde superior vena caval perfusion values at 30 mm Hg of superior vena caval pressure, respectively. Oxygen consumption was 7.4 +/- 3.7 mL/min. At an IVC pressure of 20 mm Hg, cerebral, renal, and hepatic blood flows and oxygen consumption were 5.1 +/- 2.7, 5.9 +/- 4.1, and 11.6 +/- 4.0 mL.min-1 x 100 g-1 and 3.0 +/- 0.8 mL/min. As IVC pressure increased, cerebral, renal, and hepatic blood flows and oxygen consumption increased. However, high IVC pressure was associated with high portal venous pressure, which may produce ascites. Regional blood flow during retrograde IVC perfusion was measured by the colored microsphere method in another 8 normothermic dogs. Inferior vena caval perfusion at 30 mm Hg supplied adequate blood flow to the liver (15.44 +/- 12.1 mL.min-1 x 100 g-1) and kidneys (6.35 +/- 2.0 mL.min-1 x 100 g-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Comparative experimental study between retrograde cerebral perfusion and circulatory arrest.

To evaluate the efficacy of retrograde cerebral perfusion in protecting the brain, we comparatively studied retrograde cerebral perfusion and total circulatory arrest in 18 hypothermic (20 degrees C) mongrel dogs (retrograde cerebral perfusion, n = 10; total circulatory arrest, n = 8). Retrograde cerebral perfusion was performed, maintaining an external jugular venous pressure of 25 mm Hg for 60 minutes. Retrograde cerebral perfusion provided half the cerebral blood flow and a third of the oxygen that was supplied during hypothermic cardiopulmonary bypass, which had a flow rate of 100 ml/min per kilogram. Oxygen consumption and carbon dioxide exudation did not increase on resuming cardiopulmonary bypass after retrograde cerebral perfusion, whereas they increased after total circulatory arrest (oxygen consumption 10.7 +/- 5.3 versus 19.1 +/- 8.6 ml/min, p < 0.05; carbon dioxide exudation, 0.92 +/- 0.54 versus 1.64 +/- 0.78 mmol/min, p < 0.05). Therefore, oxygen debt during retrograde cerebral perfusion was smaller than during total circulatory arrest. Retrograde cerebral perfusion also cooled the brain better than did total circulatory arrest (20.4 degrees +/- 1.5 degrees C versus 22.7 degrees +/- 0.7 degrees C, p < 0.01). Cerebral tissue oxygen tension decreased slightly (27.5 +/- 7.7 versus 12.3 +/- 3.0 mm Hg, p < 0.01), and cerebral tissue carbon dioxide tension increased slowly during retrograde cerebral perfusion (95 +/- 34 versus 147 +/- 44 mm Hg, p < 0.05). These changes were smaller than those seen in total circulatory arrest. Tissue concentrations of adenosine triphosphate in the brain remained relatively high during retrograde cerebral perfusion but decreased rapidly during total circulatory arrest (0.49 +/- 0.16 versus 0.21 +/- 0.05 mmol/gm, p < 0.01, just before resuming cardiopulmonary bypass). Retrograde cerebral perfusion cannot maintain aerobic metabolism but may reduce ischemic damage of the brain and may safely extend the cerebral circulation interruption time.

Adenosine Triphosphate↗
PubMed1994

Determination of optimum retrograde cerebral perfusion conditions.

Retrograde cerebral perfusion through a superior vena caval cannula is a new technique used to protect the brain during operations on the aortic arch. We measured cerebral tissue blood flow, oxygen consumption, and cerebrospinal fluid pressure under various perfusion conditions in hypothermic (20 degrees C) mongrel dogs (n = 18, 12.8 +/- 0.6 kg) to determine the optimum conditions for retrograde cerebral perfusion. Retrograde cerebral perfusion was performed by infusion via the superior vena caval cannula and drainage via the ascending aortic cannula while the inferior vena cava and azygos vein were clamped. Retrograde cerebral perfusion was performed as the external jugular venous pressure was changed from 15 to 35 mm Hg in increments of 5 mm Hg. Cerebral tissue blood flow was measured by the hydrogen clearance method. Hypothermic retrograde cerebral perfusion with an external jugular venous pressure of 25 mm Hg provided about half the cerebral tissue blood flow of hypothermic (20 degrees C) cardiopulmonary bypass with a flow rate of 1000 ml/min (13.7 +/- 7.9 versus 32.7 +/- 8.5 ml/min per 100 gm). It decreased significantly as the external jugular venous pressure was decreased from 25 to 15 mm Hg but did not increase significantly as the external jugular venous pressure was increased from 25 to 35 mm Hg. Whole-body oxygen consumption during hypothermic retrograde cerebral perfusion with an external jugular venous pressure of 25 mm Hg was one quarter of that during hypothermic cardiopulmonary bypass (3.4 +/- 0.7 versus 12.7 +/- 5.6 ml/min) and varied in proportion to external jugular venous pressure. The cerebrospinal fluid pressure was a little lower than the external jugular venous pressure (19.2 +/- 4.5 mm Hg versus 24.8 +/- 2.4 mm Hg) but also varied with the external jugular venous pressure. The cerebrospinal fluid pressure remained lower than 25 mm Hg so long as the external jugular venous pressure remained lower than 25 mm Hg. High external jugular venous pressure was associated with high intracranial pressure, which restricts cerebral tissue blood flow and may cause brain edema. We believe that a venous pressure of 25 mm Hg is the optimum condition for retrograde cerebral perfusion.

Animals↗
PubMed1994

[A case of left atrial free-floating ball thrombus].

A rare case of left atrial free floating ball thrombus with mitral stenosis is reported. A 66-year-old woman was admitted for epigastralgia and acute heart failure without atrial fibrillation and previous embolization. The patient was treated successfully with removal of ball thrombus and mitral valve replacement. Intraoperative transesophageal echocardiography was effective for monitoring of mobile left atrial thrombus.

Aged↗
PubMed1993

[Effect of ketamine on hepatic circulation and oxygen metabolism during hypoxia in dog].

The present study was designed to determine whether ketamine could maintain hepatic circulation and oxygen metabolism even in the presence of serious hepatic hypoxia. Hepatic oxygen delivery as well as consumption and the hepatic energy charge were assessed in twenty mongrel dogs receiving 30 mg.kg-1.h-1 of ketamine or thiamylal intravenously while inhaling graded hypoxic gas mixtures (FIO2 0.21 to 0.08). Hepatic blood flow was measured using electromagnetic flowmetry: hepatic oxygen delivery and consumption were calculated from hepatic blood flow and oxygen content in hepatic arterial, portal venous and hepatic venous blood. The hepatic energy charge was assessed by measuring arterial ketone body ratio (AKBR). In the ketamine group, hepatic arterial blood flow was well maintained but portal venous blood flow decreased significantly at FIO2 0.21 and 0.12 compared with thiamylal group. At FIO2 0.08, hepatic oxygen delivery, consumption and AKBR decreased significantly in the ketamine group mainly due to the decrease in oxygen delivery from portal vein, with concomitant increase in catecholamine level. These results suggest that ketamine could not suppress the exaggerated reaction to hypoxemia, and it could not maintain hepatic circulation, hepatic oxygen metabolism or hepatic mitochondrial redox state in better condition during serious hypoxemia compared with thiobarbiturate.

Animals↗
PubMed1991

Normal brain damage after radiotherapy of brain tumours.

A total of 106 patients were examined for adverse effects to the brain from 60Co or proton radiotherapy. Radiation induced change (RIC) developed within the irradiated field 40-60 months after doses of 800-1000 neuNSD or 70 TDF and in 10-20 months after doses of more than 1700 neuNSD or 100 TDF. The incidence of RIC increased significantly with increasing age. Furthermore pathological changes like oedema and infarction in the brain tissue may be an important factor for the development of RIC in the central nervous system (CNS).

Adult↗
PubMed1990

[Psoas lymph node metastasis in patients with carcinoma of the uterine cervix].

Enlargement of lymph nodes between the psoas muscle and lumbar spine was demonstrated on CT in three of 14 cases having Stage IIb and III uterine cervical carcinoma with iliac or paraaortic lymphadenopathy. In two of these, the adjacent lumbar vertebral body was destroyed. We define psoas lymph nodes to include all lymph nodes located between the psoas muscle and the spine. Psoas lymph nodes may be divided into upper and lower groups: the upper group distributed along the lumbar arteries above in level of L4-L5 and the lower group distributed along the lumbar branches of the iliolumbar arteries below L5. There appears to be paravertebral communication between these two groups. The region of the psoas lymph nodes should be scrutinized in interpretating CT in patients with malignant pelvic tumors which have already spread to iliac or paraaortic lymph nodes. Obliteration of fat plane between psoas muscle and lumbar vertebra is a clue to the presence of enlargement of the psoas lymph nodes on CT. Massive enlargement of psoas lymph nodes may be difficult to distinguish from metastasis to psoas muscle. In such cases, MR imaging would be of help to differentiate these two conditions.

Adult↗