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Biomedical subjects

Y Yonekawa

Publications and source records attributed to Y Yonekawa.

At least 19 recordsLinked to original sources
PubMed1992

Solidifying liquid with novel initiation system for detachable balloon catheters.

In endovascular surgery, to permanently hinder blood inflow into an aneurysm for example, a catheter is percutaneously introduced into an artery and the balloon is positioned and inflated by a solidifying liquid and then released into the diseased part. A novel solidifying liquid for the inflated balloon curable under the continuous feeding of oxygen through the wall of the balloon is described here. Glucose oxidase which oxidizes glucose producing hydrogen peroxide was used for polymerization of the solidifying liquid. This solidifying liquid cured even in the presence of oxygen and water. It was radiopaque when mixed with the iodinated X-ray contrast chemical iopamidol. In addition, the solidified liquid had appropriate mechanical properties. The endovascular surgery could be carried out safely using it.

Catheterization↗
PubMed1992

High cervical intradural lipoma--case report.

A rare high cervical intradural subpial lipoma unassociated with spinal dysraphism manifested by a slowly progressive myelopathy simulating Brown-Sequard syndrome in a 37-year-old male. The diagnosis was based on neuroradiological imaging. Intraoperative recording of somatosensory evoked potentials showed recovery of the prolonged N20 latency, indicating adequate decompression was achieved.

Adult↗
PubMed1992

Treatment of unclippable giant posterior cerebral artery aneurysms with detachable balloons--report of three cases.

Three patients presented with rare giant posterior cerebral artery aneurysms, clinically manifesting as cerebral ischemia, mass effect, and subarachnoid hemorrhage. All aneurysms were partially thrombosed, originated at the P2 segment, and possessed broad necks. Surgical neck clipping was difficult but proximal occlusion of the parent artery was feasible. Aneurysm occlusion sparing the parent artery was attempted in all cases, but failed because the detachable balloon did not successfully block the aneurysmal neck. All patients tolerated test occlusion at the P2 segment, so the parent artery was occluded proximally with detachable balloons, leaving the important perforating arteries unaffected. Two transient ischemic attacks were associated with the procedure. Where surgical treatment is unusually difficult, and proximal ligation or trapping just feasible, embolization with detachable balloons is an acceptable substitute.

Adolescent↗
PubMed1992

Worldwide distribution of moyamoya disease.

Many cases of spontaneous occlusion of the circle of Willis (moyamoya disease) have been reported in Japan, but the worldwide distribution is unclear. The total number of cases in each country reported in the literature and complications were evaluated. A total of 1063 cases have occurred worldwide excluding Japan. Cases were observed most frequently in Asia and in people of non-Caucasian origin.

Global Health↗
PubMed1992

Changes in major phospholipids of mitochondria during postischemic reperfusion in rat brain.

Major mitochondrial phospholipids were examined in rat brain after 30 minutes of reperfusion following 30- or 60-minute periods of ischemia to examine their changes and explore their relationship to mitochondrial dysfunction during postischemic reperfusion. The amount of phospholipids and the percentage of polyunsaturated fatty acid chains, which tended to decrease during 30 minutes of ischemia, recovered after reperfusion. However, after ischemia lasting for 60 minutes, these parameters did not recover but decreased further, suggesting progressive disruption of phospholipids by phospholipase A2 after reperfusion. These changes were particularly notable in cardiolipin, which is contained specifically in mitochondria. The changes were also closely associated with mitochondrial respiration and respiratory enzyme (cytochrome c oxidase and F0F1-adenosine triphosphatase) activities, which have been known to correlate with the amount of cardiolipin. These results suggest that phospholipid metabolism in mitochondrial membranes is an important factor bearing on the integrity of energy metabolism during postischemic reperfusion.

Adenosine Triphosphatases↗
PubMed1992

Superselective intra-arterial infusion of papaverine for the treatment of cerebral vasospasm after subarachnoid hemorrhage.

This report describes the successful treatment of cerebral vasospasm after subarachnoid hemorrhage with superselective intra-arterial infusion of papaverine hydrochloride. Thirty-seven vascular territories in 10 patients with symptomatic vasospasm were treated according to the following protocol. Percutaneous transluminal angioplasty was performed in two steps. First, a silicone balloon was used for dilation of the internal carotid artery and the proximal portions of the middle cerebral artery. A silicone leak balloon or Tracker-18 catheter was then introduced into or just proximal to the site of vasospasm not accessible to the angioplasty balloon catheter for superselective infusion of 0.2% papaverine. Thirty-four of 37 vascular territories were successfully dilated, and eight of 10 patients showed improvement in neurological function after the procedure. There were no serious side effects due to infusion of papaverine. It is essential to infuse the papaverine just proximal to the spastic vessels in order to deliver sufficient concentration of drug, and infusion should be carried out as early as possible before the artery loses its ability to return to a normal luminal size. Superselective intraarterial infusion of papaverine is an alternative method of treatment for symptomatic vasospasm.

Adult↗
PubMed1992

[STA-ACA anastomosis with interposed vein graft; a case report].

We report our experience with the use of three saphenous vein grafts for treating advanced occlusive cerebrovascular disease in the anterior cerebral artery (ACA) in two patients. Superficial temporal artery (STA)-ACA anastomosis with interposed vein graft is thought to be indicated for patients who have STA of insufficient length to anastomose to the ACA. Vein graft has already been demonstrated to be applicable in extracranial-intracranial artery bypass, as well as in aorto-coronary bypass. Two factors considered to be essential for successful revascularization are technical proficiency, including protection from drying, smooth approximation of vessels, and proper orientation of the graft, and the relative size of donor and recipient vessels. Because the vein graft must be anastomosed with the proximal ACA to reduce the size discrepancy between vessels, prolonged interruption of circulation during suturing is inevitable. Our operative results suggest that anastomosis to a superficial branch of the ACA just distal to the interhemispheric fissure seems to be preferable to anastomosis using vein graft, and we recommend the option of vein graft only when the STA cannot be used.

Anastomosis, Surgical↗
PubMed1992

[A case of giant aneurysm of the posterior cerebral artery, treated with a detachable balloon].

We report a case with a giant PCA aneurysm successfully treated using the detachable balloon technique. The case was a 52 year-old man with episodes of minor stroke probably due to the giant aneurysm. The aneurysm was located in the P2 segment of the right PCA and was broad-based. Clipping of the neck was considered to be impossible and proximal clipping was the alternative treatment. Instead of surgery, proximal occlusion of the PCA was performed with the use of a detachable balloon.

Catheterization↗
PubMed1991

[Effect of nizofenone on the symptomatic vasospasm after aneurysmal subarachnoid hemorrhage and its relationship to the levels of serum complements (CH50, C3 and C4)].

Serum complements (CH50, C3 and C4) after aneurysmal subarachnoid hemorrhage were measured in 42 patients over 2 to 3-week period. Nizofenone, an anti-vasospasmotic agent, was administered to 11 patients. In the nizofenone-treated group, 8 patients showed decreased serum C4 levels 5 days after the onset of subarachnoid hemorrhage, but among them, only 2 patients showed symptomatic vasospasm. Considering our previous data (majority of patients who showed decreased serum C4 levels presented with symptomatic vasospasm), these results suggest a favorable effect of nizofenone on the symptomatic vasospasm after aneurysmal subarachnoid hemorrhage.

Adult↗
PubMed1991

Dural arteriovenous malformation in the anterior cranial fossa: report of a case.

We present an unusual case involving intracranial arteriovenous malformations in the anterior cranial fossa located symmetrically on both sides. A mixed pial and dural arteriovenous malformation, the nidus of which was localized in the brain parenchyma, was found on the right side and a pure dural arteriovenous malformation on the left side. Our case is felt to support the hypothesis of a congenital origin for dural arteriovenous malformation in the anterior cranial fossa, because the dural arteriovenous malformation coexisted with the mixed pial and dural arteriovenous malformation, which can be attributed to a disturbance of normal embryonic development.

Carotid Arteries↗
PubMed1991

Degradation of mitochondrial phospholipids during experimental cerebral ischemia in rats.

Changes in content of brain mitochondrial phospholipids were examined in rats after 30 and 60 min of decapitation ischemia compared with controls, to explore the degradation of the mitochondrial membrane and its relation to dysfunction of mitochondria. Activities of respiratory functions and respiratory enzymes (cytochrome c oxidase; F0F1-ATPase) decreased significantly during ischemia. Considerable decreases in cardiolipin and phosphatidylinositol content were observed after 60 min, and other phospholipids showed similar but nonsignificant decreases in content. The amount of polyunsaturated fatty acids chains, such as arachidonic and docosahexaenoic acids, was reduced in each phospholipid, in some cases significantly, after 30 and 60 min of ischemia in time-dependent manners. Degradation of mitochondrial phospholipids during ischemia associated with the deterioration of mitochondrial respiratory functions suggested the significance of such changes in phospholipid content in disintegration of cellular energy metabolism during cerebral ischemia.

Animals↗
PubMed1991

Ecological cycle of thermostable direct hemolysin-producing strains of Vibrio parahaemolyticus in a brackish-water area with special reference to molluscs and attached microalgae.

Prevalences of thermostable direct hemolysin (TDH)-producing strains in communities of a gastropod mollusc. Clithon retropictus, and a bivalve mollusc, Corbicula japonica, and levels of the strains in attached microalgae and muddy sediments were investigated at a brackish-water area along Hashizu Creek and Togo Pond in Japan, V. parahaemolyticus was detected from attached microalgae at Hashizu Creek in summer months with the highest level of 1.4 x 10(5) cfu/g. Levels of the organism among 20 animals of C. retropictus and C. japonica at the area varied betwen non-detectable level and 10(3) per mollusc in summer months. TDH was detected from culture supernatants of 11-16% of strains isolated from the algae, sediments and C. japonica and 28% of those isolated from C. retropictus at Hashizu Creek. These evidences suggest that C. retropictus would get TDH-positive strains from the algae.

Animals↗
PubMed1991

Hypoplasia of the internal carotid artery--report of an unusual case.

We present a rare case of unilateral internal carotid artery (ICA) hypoplasia associated with arterial anomalies in the circle of Willis. The ipsilateral middle cerebral artery was supplied via anomalous arteries from the posterior cerebral artery and the ICA. The ipsilateral common carotid artery also originated from the anomalous brachiocephalic trunk. The etiology of the hypoplastic ICA is uncertain, but the associated multiple vascular anomalies support the congenital origin.

Adult↗
PubMed1991

Hemodynamic study of posterior circulation using hydraulic vascular model--critical stenosis of the vertebrobasilar artery and tolerance to occlusion therapy.

A hydraulic vascular model with glass and silicone tubes of the intracranial portion of the vertebro-basilar artery was used to determine the critical stenosis causing vertebrobasilar insufficiency, and the minimum diameter of the posterior communicating arteries (PComAs) necessary to tolerate therapeutic vertebrobasilar occlusion for unclippable aneurysms. The critical stenosis of one vertebral artery (VA) or basilar artery (BA) differed greatly depending upon the anatomical variations of the PComA and the posterior cerebral artery (PCA): 1.14 mm diameter when the artery supplies 80 ml/min to the cerebellum and brainstem only, 1.33 mm when 140 ml/min to these structures and one PCA, and 1.56 mm when 200 ml/min to these structures and both PCAs. The minimum PComA diameter to tolerate therapeutic occlusion depended largely upon the occlusion site: one PComA with 1.54 mm diameter for bilateral VA occlusion and 1.25 mm for BA occlusion distal to the branching of the superior cerebellar arteries. The total volume of collateral flow through both PComAs can be estimated by summing the squares of the diameters. These values cannot be applied rigidly to clinical cases, but are useful standards to evaluate the stenotic lesion or tolerance to occlusion.

Blood Flow Velocity↗
PubMed1991

Pituitary prolactinoma associated with polycystic ovary--case report.

A 25-year-old female presented with pituitary prolactinoma associated with polycystic ovarian disease and amenorrhea. After trans-sphenoidal adenomectomy, the serum prolactin level returned to normal. Postoperative ultrasonography revealed resolution of the polycystic ovary. Regular menses recommenced 2 months after surgery. Our experience suggests that pituitary prolactinoma may be a cause of polycystic ovarian disease.

Adult↗
PubMed1991

Synergistic action of vitamin E and vitamin C in vivo using a new mutant of Wistar-strain rats, ODS, unable to synthesize vitamin C.

It is well known that vitamins E and C exhibit synergistic action in in vitro systems, but with regard to in vivo systems, much of the available data are confusing. To elucidate this problem we used a new mutant of Wistar-strain rats that cannot synthesize vitamin C, namely, ODS rats. Two experiments were planned: (1) during development of vitamin E deficiency, whether vitamin C could spare the consumption of vitamin E; and (2) under conditions of a regular level of vitamin E intake, whether different dose levels of vitamin C can affect vitamin E concentration in tissues. The results obtained show that with vitamin C intake, higher levels of vitamin E were deposited in tissues in both experiments. With the development of vitamin E deficiency, rats in the group with a higher dose of vitamin C deposited higher concentrations of alpha-tocopherol. With simultaneous administration of vitamin E and vitamin C to the same mutant rats, the rats in the group with a higher dose of vitamin C deposited higher levels of vitamin E in all tissues tested. Thus, we concluded that vitamin C can spare the consumption of vitamin E in vivo as well as in vitro.

Animals↗