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Biomedical subjects

O Sato

Publications and source records attributed to O Sato.

At least 91 records · Page 5Linked to original sources
PubMed1996

Use of a nondissection method in lower extremity revascularization: a report on our 12-year experience of autogenous vein bypass surgery.

We report herein on our 12-year experience of performing autogenous vein grafting in the lower extremity using a nondissection method. This method involves limiting preparation for the distal anastomosis to exposure of the anterior surface of the vascular sheath, and substituting an Esmarch's rubber bandage or a pneumatic tourniquet for vascular clamps. A series of 86 consecutive patients who received 101 autogenous vein grafts employing this method were retrospectively analyzed. The causes of arterial occlusion were atherosclerosis in 55 patients, Buerger's disease in 23, and other causes in 9. There was one operative death, and 12 late deaths were recorded within a follow-up period extending to 12 years. Of four early occlusions and two stenoses, three were successfully revised within 30 days of surgery. A total of 11 revision operations were required for 10 grafts during the follow-up period, and late graft closure occurred in 9 bypasses. The primary, primary revised, and secondary patency rates at 5 years for the entire series (n = 101) were 65%, 85%, and 86%, respectively, with 42 bypasses to the tibial or peroneal artery having 84% primary revised and 86% secondary patency rates. These findings led us to conclude that minimization of the surgical injury at the distal anastomosis contributed to the long-term patency of the distal bypass.

Adult↗
PubMed1996

Early aneurysm surgery and dehydration therapy in patients with severe subarachnoid haemorrhage without ICH.

We prospectively analysed treatment results in patients with severe subarachnoid haemorrhage (SAH) who underwent early aneurysm surgery, and were managed by dehydration therapy. We studied a total of 31 patients with poor-grade SAH including 18 in grade IV, and 13 in grade V according to the WFNS classification system. Patients who were older than 70 years of age, or those with an intracerebral haemorrhage or absent brainstem response were excluded from this study. At surgery, clot evacuation from the peri-brainstem cisterns with/without external decompression was performed following obliteration of the aneurysmal neck. In the early postoperative period, patients were maintained in negative water balance using osmotic diuretics. When delayed ischaemic deficits had manifested themselves, the pulmonary wedge pressure and/or central venous pressure was immediately increased by the rapid injection of albumin until hypovolaemia reverted to normovolaemia with the continuous administration of dobutamine. The outcome at 3 months was good recovery in 16 (52%) patients, moderate disability in 3 (10%), severe disability in 5 (16%), a vegetative state in 1 (3%), and death in 6 (19%). We though that early aneurysm surgery and postoperative dehydration therapy in the acute stages of brain oedema resulting from primary brain damage are effective in the treatment of patients with severe SAH but reversible primary brain damage.

Adult↗
PubMed1996

Bleeding gastric varices as a result of splenic vein compression by a celiac arterial aneurysm.

Celiac arterial aneurysms are very unusual and often lack clinical manifestations. According to our review of the literature, this is the first report of a patient with a large celiac arterial aneurysm who exhibited hematemesis from gastric varices. Arteriography, as well as color Doppler ultrasonography and enhanced computed tomography, contributed to the diagnosis of this aneurysm, which was best exposed by a left thoracoabdominal approach. In this patient the lesion was a false aneurysm with perforation of the celiac artery, so simple closure of the orifice was carried out and the revascularization of the celiac artery was not necessary, but we should take care not to ignore the possible recurrence of vascular lesions. The risk of celiac arterial aneurysm rupture is relatively high, but the operative mortality of unruptured aneurysms is now so low that operation is strongly recommended for all patients with this type of aneurysm.

Aneurysm↗
PubMed1996

Surgical treatment of abdominal aortic aneurysms in octogenarians.

Due to the increase in life span and the decrease in mortality associated with aortic surgery, many geriatric patients now undergo surgery for abdominal aortic aneurysms (AAAs). Therefore, we studied our surgical results for AAAs in an elderly population to assess the value of such operations. Twenty-six patients aged 80 years or older underwent surgery during an 11-year period from 1984 to 1994 at our institutions, and their outcomes were compared with those of 212 younger patients. The ratio of ruptured to non-ruptured AAAs was significantly higher in the older patients (aged 80 years or older) than in the younger patients (aged 79 years or younger), and aneurysm size in cases of non-rupture was greater in older patients than in younger patients. For octogenarians with non-ruptured AAAs, the survival rate was 85.7% at 5 years, compared with 43.6% at 3 years for those with ruptured AAAs, and these figures were not significantly different from those in younger patients. The present findings support the value of our active surgical approach for octogenarians with AAAs. We believe that an aggressive approach for octogenarians will decrease the incidence of ruptured AAAs and contribute to better patient survival.

Adult↗
PubMed1996

[Reconstruction of the crural artery in atherosclerotic occlusive arterial disease].

Limb threatening ischemia in patients with atherosclerotic occlusive disease is frequently induced by the association of crural artery occlusion. To improve the patency of distal bypass grafts, we developed a "non-dissection method" for reconstruction of these lesions. This method involves following procedures; an adventitial dissection limited to the frontal surface of the artery at the anastomotic site, complete evacuation of blood from the lower leg using a Esmarch's rubber bandage or a pneumatic tourniquet under systemic heparinization, and distal anastomosis with vein graft in end to side fashion with long arteriotomy (20 mm in length) without use of vascular clamps. This method has several advantages to the conventional method, such as easiness of suturing for accurate anastomosis, preservation of the muscular branches around the anastomosis, avoidance of surgery-induced injury to the artery and prevention of postoperative cicatrization around the anastomosis which may affect natural enlargement of the bypassed native artery. The technical details are described. Since 1982, 76 tibial bypass surgeries were performed using this method. Whenever stenotic lesions were recognized, the grafts were revised and counted as a primary occlusion. The primary patency rates at 1 year, 3 years, 5 years and 10 years are 82.2%. 75.8%, 63.9% and 63.9% respectively. The secondary patency rates are 89.1%, 84.8%, 80.8% and 80.8% respectively at the same term.

Arterial Occlusive Diseases↗
PubMed1996

Completion arteriography in paramalleolar bypasses: effect of configurational changes, with special reference to spasm, on long-term outcome.

PURPOSE: The purpose of this study was to ascertain the durability of paramalleolar bypasses and elucidate the effect of configurational changes, especially spasm, seen on the completion arteriography upon the outcome. DESIGN: Retrospective study. SETTING: University hospital experience. PATIENTS AND METHODS: Nineteen paramalleolar bypass operations in sixteen patients performed between April 1988 and March 1995 were studied retrospectively. Reversed saphenous vein grafts were used in all cases. One patient required an additional microvascular free flap transfer to cover a foot amputation stump. Seventeen completion arteriograms were obtained. Patients were followed for an average of 37 months. RESULTS: One patient died in hospital, giving a hospital death rate of 5.9%. Two grafts failed immediately and could not be salvaged. Inadvertent perforation of one graft required partial replacement with a polytetrafluoroethylene graft; it eventually failed after 42 months. There were no other graft failures during follow-up. Nine completion arteriograms showed spastic change of the run-off artery, but this change had disappeared on repeat angiograms obtained before discharge. CONCLUSION: Spasm of run-off artery is a frequent finding in distal bypass surgery and adversely affects the immediate outcome. Heparinization during the first 24 hours after surgery may reduce the consequences of spasm, and long-term patency can be expected providing that the whole graft consists of autogenous vein.

Adult↗
PubMed1995

Biodegradation of glutaraldehyde-tanned human umbilical vein grafts.

A retrospective analysis of the long-term behavior of 111 glutaraldehyde-tanned human umbilical vein (HUV) grafts implanted between September 1977 and December 1993 was conducted. A total of 81 patients, with a mean age of 68.7 years, received the grafts and were followed up for between 1 and 131 months. The 5-year primary cumulative patency rate for above-knee femoropopliteal bypass was 83.1%, whereas that of other bypasses was 60.9%. An aneurysm of the graft was defined as a physically apparent localized dilatation, with diffuse ectasia being excluded. There were 11 aneurysms found in 9 grafts, 2 of which arose at the factory-made suture lines. The accumulated incidence of aneurysms had reached 21.9% by the 6th year. One aneurysm compressed the graft and resulted in limb-threatening ischemia and another resulted in frank rupture. Moreover, reinforcement of the mesh could not prevent aneurysm development, the repair of which is mandatory due to the risk of rupture and acute thrombosis. The HUV grafts showed an acceptable patency rate in the above-knee location, but the incidence of aneurysm formation after 5 years was abnormally high. Thus, both the risks and benefits of HUV grafts must be taken into account when considering their clinical application.

Adult↗
PubMed1995

Neuronal overmaturation in dysraphism: ontogenic expression of neuropeptides in the fetal brain and developmental anomalies in exencephaly.

Starting from knowledge obtained in our previous studies of experimental dysraphism in chick embryos, the entity of neuronal overgrowth observed in exencephaly was further investigated. The ontogenic expression of neuron-specific enolase (NSE), vasoactive intestinal polypeptide (VIP), and somatostatin was analyzed both in chick exencephaly of the natural product and in normal chick fetuses by carrying out immunohistochemical studies. In normal fetuses, immunostained elements positive for NSE first appeared in the spinal gray matter on postincubation day 16 and increased in intensity during the fetal period. By postnatal day 2, the cerebral peduncle, brain stem neurofibers, molecular layer of the cerebellum, corpus striatum, and piriform cortex became immunoreactive. No immunohistochemical reaction to VIP was observed during these stages. Somatostatin-positive elements were not identified during the fetal period, except in limited regions, such as the corpus striatum, which appeared to have weakly positive staining on day 21. The exencephalic fetuses, however, demonstrated extremely advanced neuronal maturation, with intense immunoreactivity already being manifest in various regions, including the corpus striatum, piriform cortex, spinal gray matter, and brain stem nuclei, on day 16 of the fetal period. Somatostatin-positive elements also appeared at this stage in chick exencephaly, but such immunoreactivity was localized, particularly in the overgrown foci. The present study showed that the neuronal maturation process in some neurons of exencephalic brain and spinal cord was definitely further advanced than that in normal controls. A possible clinical application of NSE and somatostatin measurement as markers for dysraphic states in the fetus is suggested.

Amniotic Fluid↗
PubMed1995

Morphological analysis of progressive hydrocephalus and shunt-dependent arrested hydrocephalus. An experimental study.

This experimental study was performed to determine if surgically treated feline hydrocephalus could produce any morphological and physiological changes in the periventricular tissue. The result was analyzed with clinical outcome, comparing two differently prepared models in which the biomechanical characteristics of the container property of the brain were altered. Craniectomies were performed in adult mongrel cats and the dura mater was left untouched in group A, while the dura was incised in crucial fashion in group B. Thirty-four animals underwent ventriculopleural shunt surgery 6-8 weeks after kaolin induction into the cisterna magna. In 19 animals, no shunt was implanted; they served as sham controls. These and 10 normal animals were subjected to transmission electron microscopic study or measurement of white matter water content. The regions studied were divided into three sections according to their depth from the ventricular surface (W1, W2 and W3). Considering the efficacy of shunting, the increased water content observed in preshunt animals decreased and was almost identical to normal controls after effective diversion surgery. On the other hand, the animals with ineffective shunt failed to normalize the water content and the figures were similar to the time-matched sham animals. These trends were preserved in groups A and B, but water content was much higher in group B. On histological observation, the chronological profile of subependymal extracellular space (W1, W2) in chronic condition did not correspond to the chronological changes in water content, while both changes observed after successful shunt were apparently linked. Subependymal glial proliferation was increased in volume as a function of time in all animals observed, but this was much more marked in group A than group B. Furthermore, gliosis was more evident in shunted animals than in the other group and was more prominent in cats with effective shunts than in those with ineffective shunts. These histological changes and clinical outcome were not closely related in this study. These results indicated that: (1) The shunting procedure itself could promote subependymal gliosis and this progresses unexpectedly even if CSF pressure is low enough after effective shunting. (2) This histological change is not necessarily a sufficient explanation for clinical improvement after successful shunting. (3) A biomechanical characteristic of the differently treated container property of the brain exerts an influence on the histological change and change in CSF dynamics in periependymal tissue mostly at an early stage of hydrocephalus rather than at a later stage. Therefore early treatment should be considered while avoiding an overindication for shunting.

Animals↗
PubMed1995

Responses of immunocompetent cells to cavity preparation in rat molars: an immunohistochemical study using OX6-monoclonal antibody.

Responses of immunocompetent cells, especially class II major histocompatibility complex (MHC) antigen-expressing cells, were investigated after cavity preparation in the erupted upper first molar teeth of rats, by immunohistochemistry using OX6-monoclonal antibody. In control teeth, OX6-immunopositive cells were predominantly located beneath the odontoblast layer in the dental pulp. Cavity preparation caused an acute edematous reaction between the injured odontoblasts and predentin, and most of OX6-immunopositive cells in the affected site shifted away from the pulp-dentin border. After 12-24 hours, many OX6-immunopositive cells accumulated along the pulp-dentin border and extended their cytoplasmic processes into the exposed dentinal tubules. After 72 hours, newly differentiated odontoblasts replaced the degenerated odontoblasts, and few OX6-immunopositive cells remained along the pulp-dentin border. Our data suggest that some of the class II MHC antigen-expressing cells in the dental pulp participate in the initial defense reaction and presumably serve as a biological sensor for the external stimuli arriving through the exposed dentinal tubules.

Animals↗
PubMed1995

[Fatigue and stress of anesthesiologists at work--third report: investigation with a flicker photometer and a stabilo-meter].

We previously studied the fatigue and stress of anesthesiologists at work using a flicker photometer, visual reaction time test, questionnaires, and Holter EKG. In the present study, we investigated the fatigue and stress in seven junior anesthesiologists at work using a flicker photometer and a stabilo-meter. The stabilo-meter measures postural stabilization. We performed each test three times on each subject for a total of twenty-one times. The flicker test and the stabilo-test showed the increase in fatigue in 17 (18%) and in 16 tests (76%), respectively, in all seven subjects. Increase of fatigue in both the flicker and stabilo-tests was observed in 13 tests (61%) of 6 subjects. There was a good relationship between the flicker test and the stabilo-test. Therefore, the stabilo-test appears to be a useful method for investigating the fatigue of anesthesiologists.

Anesthesiology↗
PubMed1995

[Management of delayed ischemic neurological deficit in subarachnoid hemorrhage before aneurysmal surgery].

The incidence of rerupture during the period of delayed ischemic neurological deficit (DIND) was studied in patients with aneurysmal subarachnoid hemorrhage (SAH) before surgical aneurysmal obliteration, and optimal management of DIND for preventing rerupture is discussed. At Tokai University Hospital, 511 patients with SAH were admitted during the 5-year period from 1988 to 1992. Of these, 247 had not undergone obliteration of the aneurysm neck within 3 days after SAH. In this group, 31% (77 patients) developed DIND. Of these 77 patients, 40 were managed with induced hypertension and/or hypervolemic therapy for DIND (25 with both (group 1), 15 with normotensive hypervolemic therapy (group 2)), and 37 did not receive either kind of therapy (group 3). The incidences of rerupture were as follows: all SAH patients: 11.5%; group 1: 48%; group 2: 7%; group 3: 11%. The incidence of rerupture in group 1 was significantly higher than that in the other groups. On the other hand, the favorable outcome rate (excellent and good) was as follows: group 1: 40%; group 2: 73%; group 3: 22%. This rate was significantly higher in patients who received normotensive hypervolemic therapy, than in other groups. This study suggests that, to avoid rerupture and unfavorable outcome, normotensive hypervolemic therapy is the optimal management approach in patients with DIND after SAH who have not undergone obliteration of the aneurysmal neck.

Aneurysm, Ruptured↗
PubMed1994

[Clinical trials of TAE using micro-coil coated with n-butyl 2-cyanoacrylate and lipiodol].

Clinical trials of TAE using microcoils (Target, USA) coated with n-butyl 2-cyanoacrylate and lipiodol were performed. The procedures were as follows. First, a small amount of lipiodol was injected into a Tracker 18 catheter. Secondly, a microcoil coated with n-butyl 2-cyanoacrylate and lipiodol was inserted into the microcatheter. Thirdly, a small amount of lipiodol was again administered into the catheter just behind the coil. Finally, the coil was pushed safely out from the catheter with a special guidewire. With this method, excellent occlusion of small arteries was obtained. There were no complications.

Embolization, Therapeutic↗
PubMed1994

[Usefulness and safety of segmental-subsegmental TAE for hepatocellular carcinoma in cases of liver hypofunction].

We analyzed the safety of the segmental-subsegmental TAE for hepatocellular carcinoma in 18 cases of liver hypofunction by checking total bilirubin change after TAE. The TAE was performed safely in all of the cases. The highest value of total bilirubin before TAE was 5.1 mg/dl in the 1-2 subsegment TAE group, 3.8 mg/dl in the 3-4 subsegment TAE group and 2.0 mg/dl in the 6 subsegment TAE group. We conclude that segmental TAE is safe even in the patient of liver hypofunction.

Aged↗