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Biomedical subjects

T Sakaki

Publications and source records attributed to T Sakaki.

At least 253 records · Page 14Linked to original sources
PubMed1993

[Experimental study of acute spinal cord injury: a study of spinal blood flow].

It is well known that the worsening of neurological findings after spinal cord injury is due to the secondary progression of pathological changes which may be caused by spinal cord blood flow disturbance. We measured spinal blood flow of 5mm rostrally and caudally distant portions from the injured point, using the laser Doppler flowmeter experimentally. Forty rats were used. Ten of these were used as a control group. And thirty animals were injured at the level of the tenth thoracic cord with a 50g epidural one minute compression method and measured continuously from 30 minutes before the injury to 6 hours after the injury. Twenty two surviving animals were evaluated. In the control group, spinal blood flow was stable. But in the injured group, spinal blood flow dropped by 30.6 + 9.8% on the rostral side and 37.3 + 17.6% on the caudal side in comparison with the resting value soon after the injury. Although the flow improved to 89.3 + 11.1 and 71.3 + 17.8% respectively 15 minutes later, it dropped again gradually and reached 42.8 + 14.1 and 66.2 + 16.4% respectively 6 hours after the injury had been inflicted. Lastly, in the animals, carbon perfusion was performed through the left ventricle. The normal figured vasculature in the preparation of the injured and measured portion was calculated with a microcomputer imaging analyzer and compared with control groups. The number of the normal vessels was significantly more abundant on the caudal side than on the rostral side (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Organella-targeted expression of rat liver cytochrome P450c27 in yeast. Genetically engineered alteration of mitochondrial P450 into a microsomal form creates a novel functional electron transport chain.

A modified rat cytochrome P450c27, whose mitochondrial targeting signal had been replaced by a possible microsomal targeting signal of bovine cytochrome P450c17, was expressed in yeast. The modified P450c27 hemoprotein was correctly localized on yeast microsomes and exhibited the P450c27-dependent monooxygenase activity by addition of bovine adrenodoxin (ADX) and NADPH-adrenodoxin reductase (ADR). Considering the previous observation that P450c27 with its own mitochondrial targeting signal was imported into yeast mitochondria (Akiyoshi-Shibata, M., Usui, E., Sakaki, T., Yabusaki, Y., Noshiro, M., Okuda, K., and Ohkawa, H. (1991) FEBS Lett. 280, 367-370), it is now suggested that the destination of P450c27 to either mitochondria or microsomes in yeast depends solely on the amino-terminal targeting signal. In addition, the modified P450c27 was simultaneously expressed in yeast with mature forms of bovine ADX and ADR. The recombinant yeast produced the P450 on the microsomes and mature forms of ADX and ADR in the cytoplasm, and showed the monooxygenase activity. Accordingly, a novel type of functional electron transport chain has been established between the cytoplasm and the microsomes in yeast.

Animals↗
PubMed1992

Astrocytoma with widespread calcification along axonal fibres.

We describe a 44-year-old man found to have a diffusely calcified astrocytoma originating in the left frontoparietal region and extending along the axonal fibres into the opposite cerebral hemisphere and brain stem. Computed tomography and magnetic resonance imaging clearly demonstrated the spread of the tumour. The tumour was partially resected and histologically diagnosed as an astrocytoma. A correct preoperative diagnosis was difficult, because the lesion was very slow-growing and its widespread calcification mimicked congenital or inflammatory calcium deposits.

Adult↗
PubMed1992

Isoflurane in the management of status epilepticus after surgery for lesion around the motor area.

When conventional treatment for status epilepticus fails, general anaesthesia is recommended. We present our experience with isoflurane, an inhalational anaesthetic, in the management of four patients with status epilepticus which occurred soon after surgery for motor area lesion. The seizures were controlled with relatively small concentrations of isoflurane. Hypotension, the only adverse effect of isoflurane, was managed easily with the use of dopamine in physiological saline. Although status epilepticus occurring soon after surgery is transient, it carries a risk of persistent brain damage if active treatment is not instituted promptly. Isoflurane general anaesthesia may be recommended to control it in the intensive neurosurgical care.

Adult↗
PubMed1992

Prostaglandin E1 and carbon dioxide reactivity during cerebral aneurysm surgery.

The purpose of this study was to evaluate the effect of prostaglandin E1 (PGE1) on CO2 reactivity during cerebral aneurysm surgery in 37 patients under neuroleptoanaesthesia (NLA). The patients were divided into two groups based on the timing of surgery (A: late surgery B: early surgery). In the early surgery group, aneurysm surgery was performed within three days of subarachnoid haemorrhage (SAH) and in the late surgery group surgery was performed more than four days after SAH. Presurgical neurological status was worse in the early surgery group than in the late surgery group (P less than 0.01). Local cerebral blood flow (LCBF) measurements were made using a thermal gradient blood flow meter. Hypotension was induced by PGE1 administration at an initial dose of 0.1 micrograms.kg-1.min-1 and adjusted to maintain the mean arterial pressure (MAP) at about 70 mmHg. The CO2 reactivity was calculated by the % change in LCBF divided by the change in PaCO2 (% delta LCBF/delta PaCO2 (%.mmHg-1)). LCBF, heart rate and mean arterial blood pressure were measured during and after PGE1 infusion. Carbon dioxide reactivity was measured before, during and after PGE1 administration. The LCBF did not change throughout the study but CO2 reactivity was greater in Group A (before hypotension: 2.74 +/- 0.85 %.mmHg-1, during hypotension: 2.54 +/- 0.73 % .mmHg-1, after hypotension: 2.59 +/- 1.17 %.mmHg-1) than in group B (before hypotension: 1.54 +/- 0.57%.mmHg-1, during hypotension: 1.56 +/- 0.59 %.mmHg-1, after hypotension: 1.49 +/- 0.42%.mmHg-1) (P less than 0.01). Outcome which was graded by Glasgow Outcome Scale at discharge, was better in Group A (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Secretory meningioma with elevated serum carcinoembryonic antigen level.

We recently encountered a 68-year-old woman with right sphenoid wing meningioma of the secretory type accompanied by an elevated serum carcinoembryonic antigen level. This case was neuroradiologically characterized by marked brain edema. Histologically, the lesion was rated as having meningothelial components and was rich in blood vessels and pseudopsammoma bodies. Carcinoembryonic antigen, epithelial membrane antigen, keratin, and cytokeratin were immunohistochemically detected in the pseudopsammoma bodies and the cells producing these bodies.

Aged↗
PubMed1992

Neuroepithelial cyst of the lateral ventricle. Clinical features and treatment.

This report concerns eight patients with noncolloid neuroepithelial cyst of the lateral ventricle, including four surgical and four conservative cases. Of the surgical patients, two had headache, one had orbital pain, and one had seizures. In the conservative group there were no symptoms due to the cysts and no changes in computed tomography scan during follow-up for an average of 1.4 years. Magnetic resonance imaging was performed in five cases and showed a cyst with an intensity similar to cerebrospinal fluid, while a cyst membrane was also detected in three cases. Our findings suggest that (1) the majority of symptomatic neuroepithelial cysts in the lateral ventricle are located in the trigone; (2) the cause of symptoms suggestive of obstruction, such as headache, is an isolated ventricle that demonstrates dilatation of the inferior horn on computed tomography and magnetic resonance imaging; (3) the operative indication is obstructive symptoms; and (4) cyst-peritoneal shunt is an effective procedure.

Adult↗
PubMed1992

Analysis of chondroitin sulfate isomers in the periodontium of the monkey using high-performance liquid chromatography.

Glycosaminoglycan (GAG) was extracted from monkey periodontium, consisting of gingiva, periodontal ligament, alveolar bone and cementum, and from dental pulp and dentin by digestion with Pronase E. Unsaturated disaccharide isomers formed by chondroitinase AC digestion from chondroitin sulfate were labeled with dansylhydrazine and analyzed by high-performance liquid chromatography. These tissues showed different molar ratios of the unsaturated chondroitin sulfate disaccharides. The ratio of delta Di-4S to delta Di-6S was lowest in the dental pulp, followed by the gingiva, periodontal ligament, dentin, alveolar bone, and cementum, in that order. It was greater in the calcified than in the uncalcified tissues.

Alveolar Process↗
PubMed1992

Cortical and subcortical cavernous angioma: a comparison of patients with and without hemorrhage as the initial symptom.

Cavernous angioma is a benign vascular hamartoma with an obscure etiology. Clinical, radiological, and histological features of 24 cases of cortical and subcortical cavernous angiomas were analyzed to investigate the etiology. The lesions were classified as hemorrhaging (8 cases) or non-hemorrhaging (16 cases) according to the initial symptom. Age, sex, location, calcification and postcontrast enhancement by computed tomography (CT), tumor staining by angiography, and calcification and hemosiderin by histological examination were analyzed. Multivariate analysis showed that calcification by CT and histological examination correlated with non-hemorrhaging cases. Histological examination showed that calcification occurred inside and outside the blood vessels, within the vessel walls and in the adjacent brain tissue. Hemosiderin was also seen in most cases. These findings suggest that cavernous angiomas without hemorrhage have a poor circulation, resulting in minor recurrent bleeding and thrombosis, as well as calcification.

Adolescent↗
PubMed1992

Immunohistochemical study of a newly defined oncofetal antigen (HGR-Ag) in tumors of the central nervous system.

The oncofetal antigen (HGR-Ag) in brain tumors was newly defined using the monoclonal antibody derived from tissue extracts of an anaplastic astrocytoma. The HGR-Ag was purified through sequential chromatography using diethylaminoethyl-Sephadex A-50 and Con-A Sepharose affinity columns. The latter method indicated that HGR-Ag is not a glycoprotein, and Western blot analysis indicated a molecular weight of 80-90 kd. Purified antigen was used to produce antibody. This new antibody, designated H1H2, was shown to be an immunoglobulin G1 by immunodiffusion assay. Histological/immunohistochemical studies using the H1H2 antibody on paraffin and frozen tissue sections showed HGR-Ag to be intracellular rather than membrane-associated. The immunoreactivity of H1H2 was highest in malignant astrocytomas, glioblastomas, and normal fetal brain tissue. Neurinomas and certain carcinomas of other organs showed lesser, variable reactivity to H1H2. The strength of the antigen-antibody binding was correlated with the degree of malignancy in human gliomas. H1H2 bound to fetal brain tissue and undifferentiated neural tumors, but not to normal adult brain tissue, so HGR-Ag is probably a fetal oncoantigen.

Animals↗
PubMed1992

Diaphragma sellae meningioma associated only with signs of hypopituitarism--case report.

A rare diaphragma sellae meningioma presenting only with signs of hypopituitarism occurred in a 54-year-old male. Preoperative magnetic resonance (MR) imaging clearly demonstrated a small lesion in the supradiaphragmatic area immediately beneath the optic chiasm, displacing the pituitary stalk laterally. Intraoperatively, the tumor was confirmed to be attached only to the posterior leaf of the diaphragma sellae. Histological examination revealed a transitional type meningioma. Such a small meningioma may be associated only with hypopituitarism, as compression is confined to the pituitary stalk, not affecting the optic pathways. MR imaging can demonstrate the clinicopathological features of this small but significant tumor.

Humans↗
PubMed1992

Anaplastic astrocytoma of an oncocytic type occurring in the cerebellar vermis in Pierre Robin syndrome--case report.

A 44-year-old male with Pierre Robin syndrome and funnel chest was diagnosed with a tumor of the cerebellar vermis and spontaneous pneumothorax. He received tube thoracostomy for pneumothorax and ventriculoperitoneal shunt for hydrocephalus, followed by radiological examination, subtotal removal of the tumor, pneumonorrhaphy, and chemoradiotherapy. Light microscopy of the tumor sample revealed marked pleomorphism of the tumor cells and numerous giant cells, without mitotic figures. Microcystic changes due to vasogenic edema were also evident throughout the tumor. Electron microscopy showed more than 50% of all tumor cells to be oncocytes, with numerous mitochondria in the cytoplasm. The tumor was diagnosed as anaplastic astrocytoma of an oncocytic type.

Adult↗
PubMed1992

Perfusion pressure breakthrough threshold of cerebral autoregulation in the chronically ischemic brain: an experimental study in cats.

A study was designed to investigate hyperperfusion syndrome after the restoration of normal cerebral blood flow in a chronically cerebral ischemic state resulting from high-flow arteriovenous malformations or severe carotid stenosis. A fistula between the left distal common carotid artery and the jugular vein was created and the left vertebral artery was simultaneously occluded in 44 cats to produce a chronic cerebral ischemic state. For control experiments, 10 cats underwent occlusion of the left common carotid and vertebral arteries. Six weeks later, pial arterial behavior, disruption of the blood-brain barrier (BBB), and cerebral histological changes were investigated using three experimental methods. In the first, in which a fistula was occluded under normal conditions, pial arteries contracted to some 80% of the resting state; however, no BBB disruption or histological changes were observed. In the second experiment, in which a 20-minute occlusion of the left middle cerebral artery was performed in the cats with a patent fistula, a 30% to 40% dilated state of the pial arteries continued after recirculation, and BBB disruption-induced cerebral edema and infarction were observed. These findings were more prominent in the cats that underwent occlusion of the fistula. On the other hand, in the control group, the pial arteries returned to resting size within 40 minutes, and no BBB disruption or histological changes were observed. In the third experiment, in which moderate hypertension was induced for 1 hour, the pial arteries dilated much more remarkably; BBB disruption and cerebral edema were revealed to be more extensive in the cases of fistula occlusion than within those with a patent fistula. In the control group, however, the pial arteries contracted 10% during hypertension, while BBB disruption and histological changes were not evident. The results indicate that the perfusion pressure breakthrough threshold in the chronically ischemic brain may not be reduced by the restoration of normal blood flow, but may be decreased by the addition of new ischemic insults or hypertension.

Animals↗
PubMed1992

[Epithelial cyst occurring on the anterior surface of the brain stem--case report and review of the literatures].

Epithelial cysts in the posterior fossa are very rare, and only 22 cases have been reported in literatures. We report a case of epithelial cyst occurring on the anterior surface of the brain stem. A 31-year-old man was admitted to our hospital complaining of right hemiparesis and dysarthria. Plain CT showed a heterogeneous (isodense-hyperdense) mass in front of the pons, and was not enhanced after injection of contrast medium. As for findings of MRI, the tumor revealed as heterogeneous (isointense-hyperintense) mass on T1-weighted image and also heterogeneous (hypointense-hyperintense) mass on T2-weighted image. We removed partially the tumor which content was like yogurt. The histological findings of the cyst wall revealed a pseudostratified columnar ciliated epithelium.

Adult↗
PubMed1992

[Local cerebral blood flow and its CO2 reactivity in the ischemic cerebrovascular diseases before and after bypass].

We evaluated the effects of the STA-MCA anastomosis on local cerebral blood flow (LCBF) and CO2 cerebrovascular reactivity (CVR) in ischemic cerebrovascular diseases (CVD). [Patients and Methods] We examined the LCBF and CVR of 21 patients with ischemic CVD subjected standard STA-MCA anastomosis. During surgery, LCBF was continuously measured using the thermal diffusion method sometimes in a state of decreased PaCO2 (median: 7.2mmHg) before and after bypass. CVR was represented as % delta LCBF/delta CO2. [Results] 1) In the control group (with non-ruptured aneurysm, n = 7), LCBF was 58.6 +/- 14.1 ml/100g/min and % delta LCBF/delta CO2 was 4.68 +/- 1.68%/mmHg. 2) Before bypass, LCBF was 46.7 +/- 10.3ml/100g/min. It was significantly (p < 0.05) lower than control level. After bypass, LCBF increased significantly (p < 0.05) to 62.0 +/- 14.3 ml/100g/min. 3) Before bypass, % delta LCBF/delta CO2 was -1.36 +/- 4.34%/mmHg. In the 14 cases (66.7%), % delta LCBF/delta CO2 was below the 0%/mmHg (inverse steal effect). 4) After bypass, it increased to 0.08 +/- 2.73%/mmHg. 11 cases (52.4%) showed % delta LCBF/delta CO2 was above the 0%/mmHg. 5) In the group with a preoperative % delta LCBF/delta CO2 of less than 0%/mmHg, preoperative LCBF was 43.6 +/- 9.3 ml/100g/min, which was significantly low (p < 0.01) compared to that in the group with higher % delta LCBF/delta CO2. After bypass, LCBF and % delta LCBF/delta CO2 remarkably increased in the group with % delta LCBF/delta CO2 below 0%/mmHg. [Conclusion] Before bypass, LCBF was low and CVR was severely disturbed. In the 14 cases % delta LCBF/delta CO2 was below 0%/mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Changes in seizure-triggering threshold and after discharge duration in seizure susceptibility].

Epilepsy is analysed on terms of two different conditions, seizure susceptibility and seizure induction. Reports on detailed changes of seizure-triggering threshold and after discharge duration in seizure susceptibility are few. We examined staged changes of seizure-triggering threshold and after discharge duration in seizure susceptibility in a cat amygdaloid kindling model. Ten crossed adult cats were used. We investigated after discharge threshold (ADT), partial seizure threshold (PST) in stage 4 group (P) and generalized seizure threshold (GST) in stage 6 group (C). At the same time, we examined after discharge duration on electroencephalograph (EEG) in each stage. Seizure-triggering threshold decreases significantly step by step. After discharge duration increases significantly step by step. It is concluded that staged decrease of seizure-triggering threshold and increase of seizure's grade and duration was seen in seizure susceptibility.

Amygdala↗