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Biomedical subjects

S Wakai

Publications and source records attributed to S Wakai.

At least 181 records · Page 10Linked to original sources
PubMed1982

[Computed tomographic measurement of regional cerebral blood flow by xenon enhancement (author's transl)].

The present study was conducted to overcome some of disadvantages of cerebral blood flow study by radionuclide, such as poor regionality of flow values and errors involved in pathological brains. Serial CT scanning was carried out during and after inhalation of 50 to 70% non-radioactive xenon in humans. Diffusible gas with high atomic number enhanced gray matter first 19 +/- 4 HU (mean +/- SD) on an average in Hounsfield unit (HU) and later white matter 24 +/- 4 HU. In seven normal subjects, blood flow in gray matter was 82 +/- 11 and that in white matter 24 +/- 5 ml/100 gm/min. Partition coefficient which is not readily obtainable by radionuclide study was 0.9 +/- 0.1 in normal gray matter and 1.4 +/- 0.2 in normal white matter. Two cases were presented to show k-map (clearance rate), lambda-map (partition coefficient) and CBF map, which displayed images of values calculated automatically, in black and white or color on CRT. The first case was a patient with metastatic brain tumor from lung in the left parietal region. The blood flow of the tumor was close to that of gray matter, whereas blood flow of edematous white matter surrounding the tumor was decreased to below 10 ml/100 g/min with partition coefficient ranged from 0 to 0.9. The second case was presented to demonstrate the resolution of the blood flow map obtained by this method. Multiple lacunar infarcts of the basal ganglia and white matter in the size of 1 to 3 mm, which were hardly identified on regular CT picture, were well visualized on CBF map. This method appeared to have several advantages over conventional isotope method and to provide useful clinical and research informations.

Aged↗
PubMed1981

Development of blood-cerebrospinal fluid barrier to horseradish peroxidase in the avian choroidal epithelium.

The penetration of horseradish peroxidase (HRP) from blood into ventricle via the avian choroid plexus was examined by electron microscopy in order to study the development of the blood-cerebrospinal fluid barrier (BCSFB). 1-20 mg HRP was injected into the allantoic vein of chick embryos between the 7th and 21st day of incubation. Until the 8th day (stage 34) the reaction products of injected HRP were observed in the interepithelial clefts at both luminal (ventricular) and abluminal sides. At the 9th day (stage 35), their penetration was blocked at most apical junctional complexes of the choroidal epithelia. At the 10th day (stage 36) and at every subsequent stage, HRP molecules were completely impeded at the apical tight junctions. These results show that the BCSFB to HRP in the avian choroidal epithelium is completely established by the 10th day, when molecules of HRP are still able to permeate between the capillary endothelia in the cerebellum and the spinal cord (Wakai and Hirokawa 1978).

Animals↗
PubMed1981

Characteristics of intracranial meningiomas in childhood.

18 cases of meningiomas in childhood below the age of 15 years at the onset of symptoms and signs were experienced in our clinic. They were studied as for the incidence, age and sex distributions, symptoms and signs at the onset, tumor locations, histological types, presence of cyst, dural attachments, and prognosis, in comparison with cases in adolescence (18 cases) and in adults (498 cases). Distinctive features in childhood meningiomas were: (1) relatively high incidence in the lateral ventricles (11.1%), (2) high incidence of cyst formation in the tumor (16.7%), and (3) of cases without any dural attachment (12.5%). These features were statistically significant as compared to adult cases (p less than 0.05). Features 1 and 2 were also true for adolescence cases. It was also revealed that male patients were predominant in childhood and adolescence (M:F = 10.8) in contrast to female predominance in adults (M:F = 1:1.6). The most frequent histological type was sarcomatous type (6 out of 18). It may be of interest that 3 cases of this malignant type have been alive for more than 10 years.

Adolescent↗
PubMed1981

The effect of a lipid hydroperoxide of arachidonic acid on the canine basilar artery. An experimental study on cerebral vasospasm.

The in vivo spasmogenic capacity of a lipid hydroperoxide (15-hydroperoxy arachidonic acid: 15-HPAA) was studied in a chronic experiment using the dog. The 15-HPAA was injected into the cisterna magna (0.2 or 2 mg emulsified in bovine serum albumin solution). The changes in diameter of the basilar artery were followed by angiography, and the morphological changes were studied by electron microscopy. The cisternal injection of 0.2 mg of 15-HPAA caused a mild constriction of the basilar artery which lasted about 7 hours. The cisternal injection of 2 mg of 15-HPAA caused a biphasic constriction, the initial phase of which was a moderate narrowing lasting about 10 hours. The second phase started on the 2nd or the 3rd day after injection. The intensity of the arterial narrowing was more pronounced in the second phase than in the first. The prolonged secondary constriction of the basilar artery continued until sacrifice on the 7th day after injection. Electron microscopic study revealed a marked degenerative change in the endothelium and myonecrotic changes in the tunica media. The prolonged arterial constriction in the second phase was invariably associated with remarkable degeneration of the endothelium. On the other hand, myonecrotic changes were limited to a small number of smooth-muscle cells. The results of the present study are consonant with the hypothesis that lipid peroxidation associated with lysis of the subarachnoid clot is involved in the genesis of chronic vasospasm in subarachnoid hemorrhage.

Animals↗
PubMed1981

Pituitary apoplexy: its incidence and clinical significance.

The occurrence of hemorrhage from pituitary adenoma (so-called "pituitary apoplexy") was investigated in a consecutive series of 560 cases operated on during the past 30 years. There were 93 cases (16.6%) in which hemorrhage from pituitary adenomas was confirmed either clinically or surgically. These patients were analyzed in terms of age, sex, symptoms and signs, size of tumor, hormonal function, and histological types of adenomas, and computerized tomography findings. In 90 cases (16.6%), hematoma or old bloody fluid was verified within the tumor tissue at surgery. Three other patients presented with subarachnoid hemorrhage, but there was no detectable intratumor hematoma in any of them. Among these 93 patients, 42 (7.5%) showed no evidence of clinical symptoms related to hemorrhage (asymptomatic hemorrhage). Fifty-one patients (9.1%) had definite histories of an acute episode that suggested sudden bleeding (symptomatic hemorrhage: pituitary apoplexy). Thirty-eight patients (6.8%) had a major attack manifested by disturbances of consciousness, hemiparesis, loss of vision, or ocular palsy. In two acromegalic patients, pituitary apoplexy developed during bromocriptine treatment. There was one case of sudden death due to massive hemorrhage from the tumor 14 months after the completion of postoperative radiation therapy. The other 13 symptomatic patients (2.3%) developed a minor attack which included headache, nausea, vomiting, and vertigo. Bleeding from pituitary adenomas was not statistically correlated with any of the following factors: sex, hormonal function of adenomas, and histological types, but it was correlated with age. The number of asymptomatic cases in the third decade was significantly greater than that of the whole group of pituitary adenoma patients in the same decade. The present investigation revealed that the incidence of pituitary apoplexy was unexpectedly high: a major attack in 6.8% of pituitary adenoma patients, a minor attack in 2.3%, and asymptomatic hemorrhage in 7.5% of the cases. This risk of pituitary apoplexy should be kept in mind in treating pituitary adenomas.

Adenoma↗
PubMed1981

Evaluation of prostaglandin biosynthetic activity in canine basilar artery following subarachnoid injection of blood.

Transformation of arachidonic acid into prostaglandins was investigated in the basilar artery by incubating sections of artery with carbon-14-labeled arachidonic acid. Thin-layer radiochromatography revealed that, in normal canine basilar arteries, 14C-arachidonic acid was transformed mainly to 6-keto-prostaglandin (PG)F1 alpha, a spontaneous metabolite of prostacyclin (PGI2). Among other prostaglandins, only a small amount of PGF2 alpha was detected, whereas PGD2, PGE2, and thromboxane B2 were not. Arteries removed on Days 3 and 8 after subarachnoid blood injection showed a prostaglandin synthesis profile similar to that in the normal cerebral artery. In borate-buffered saline (0.1M borate buffer, pH 9.0/0.15M NaCl = 1:9, vol/vol), canine basilar artery produced a PGI2-like substance that inhibited adenosine diphosphate (ADP)-induced platelet aggregation. Its anti-aggregatory activity was completely abolished by acidification. Aspirin likewise inhibited production of the anti-aggregatory substance. From these results, it was concluded that the anti-aggregatory activity was due solely to the production of PGI2 by the arterial specimen. Based on the above results, PGI2 biosynthetic activity in the cerebral artery exposed to subarachnoid blood injection was bioassayed by measuring the inhibitory activity of the incubation product upon ADP-induced platelet aggregation following incubation of the arteries in borate-buffered saline for 5 to 30 minutes at 20 degrees C, using synthetic PGI2-Na as a standard. The synthetic activity of PGI2 in the artery exposed to subarachnoid blood injection had diminished remarkably by Days 3 and 8. This diminution of PGI2 synthesis in the cerebral artery may be involved in the pathogenesis of cerebral vasospasm.

Animals↗
PubMed1981

[Development of blood-brain and blood-cerebrospinal fluid barrier (author's transl)].

In this article, the author reviewed the world literatures concerning the development of blood-brain (BBB) and blood-cerebrospinal fluid barrier (BCSFB) in both humans and animals. The author also briefly reviewed the results of his investigations on the development of these barriers to horseradish peroxidase (HRP) in chick embryos. The barriers to water-soluble macromolecules are likely to develop almost completely before birth in humans as well as in experimental animals. However, the timing of their completion is different between BBB and BCSFB. This may reflect the different nature of the tight junctions between capillary endothelial and choroidal epithelia. BBB and BCSFB to lipid soluble substances, water-soluble low molecular particles and electrolytes develops in different manners and timing. Development of selective barrier or transport system of metabolically active substances such as D-glucose or essential amino acids may be roughly synchronous to the maturation process of the brain and become fully effective after complete evolution of BBB and BCSFB to macromolecules. To study development of BBB and BCSFB is of great importance for understanding the pathogenesis of kernicterus and various CNS malformations.

Amino Acids, Essential↗
PubMed1980

Traumatic intracavernous aneurysm of the internal carotid artery following surgery for chronic sinusitis.

A case of traumatic intracavernous aneurysm is presented. The aneurysm at the siphon of the internal carotid artery was produced as a result of injury during an operation for chronic sinusitis. In addition to the formation of the aneurysm, the angiogram showed an irregular intimal dissection along the internal carotid artery distal to the aneurysm. To prevent disastrous bleeding from the aneurysm and further progression, a trapping operation was made in combination with a superficial temporal-middle cerebral artery anastomosis.

Carotid Artery Injuries↗
PubMed1979

Tight junctions in choroid plexus papillomas.

Four cases of choroid plexus papilloma (CPP) obtained at the time of surgical excision were examined by electron microscopy and compared with normal choroid plexus (CP) of mouse and chick. In apical tight junctions fusion of the two outer leaflets of the adjacent cytoplasmic membrane was verified as in CP. This fact suggests that there is a blood-CSF barrier not only in CP but also in CPP.

Animals↗
PubMed1979

[The ultrastructural study of choroid plexus papillomas (author's transl)].

Four cases of choroid plexus papilloma (CPP) obtained at the time of surgical excision were examined by light and electron microscopy and compared with normal choroid plexus (CP) of mouse and chick. Ultrastructurally CPPs were the same as CP except in the following two points: In CCPs 1) pinocytotic vesicles of the vascular endothelium and 2) cytoplasmic filaments were more increased in number than in CP. In one case, which showed malignant changes in some parts, we found prominently increased spot desmosomes and cytoplasmic filaments as compared with other three cases, microcysts at the apical portion with other features suggesting the secretory process except for the absence of basal infoldings and myelin bodies. As for the apical tight junction fusion of the two outer-leaflets of the adjacent cytoplasmic membrane was observed as in CP. This fact suggests that there is a blood-CSF barrier also in CPPs as in CP.

Adolescent↗