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Biomedical subjects

T Sakaki

Publications and source records attributed to T Sakaki.

At least 289 records · Page 16Linked to original sources
PubMed1991

Partial corpus callosotomy beneficial for Lennox-Gastaut syndrome--report of two cases.

Seizures in patients with Lennox-Gastaut syndrome are very resistant to drug therapy. Division of the anterior half of the corpus callosum was performed in two patients with Lennox-Gastaut syndrome incapacitated by frequent atonic seizures leading to sudden falls. Postoperatively, the atonic seizures were completely eliminated and their mental reactivities remarkably improved. It is clear that they have benefited from a lower frequency of seizures and reduced dosages of anticonvulsant medication, which outweight the acquired disabilities.

Adult↗
PubMed1991

Spontaneous intracerebral hemorrhage in cases of severe angiospasm following ruptured aneurysm--a pathological study.

Eleven patients with a history of moderate or severe angiospasm following ruptured cerebral aneurysm developed spontaneous intracerebral hemorrhage between 31 and 111 months after aneurysm surgery. In all cases, hemorrhage occurred in the ipsilateral hemisphere to the original aneurysm. In nine patients, the hematoma was surgically evacuated and bleeding perforating arteries were resected for histological examination. Computed tomographic scans showed the hematomas to be unusually extended compared to those after hypertensive intracerebral hemorrhage. The histological examination showed various degenerative changes in the elastic lamina and media of the perforating arteries, even though most patients were young and normotensive. These findings suggest that patients who have suffered severe cerebral angiospasm may have a higher risk for subsequent development of intracerebral hemorrhage than those without prior angiospasm.

Aged↗
PubMed1991

Multiple calcified metastatic brain tumor--case report.

The authors describe an unusual case of pulmonary small cell carcinoma with numerous calcified metastatic nodules of the brain in a 62-year-old female. Computed tomographic scanning and magnetic resonance imaging demonstrated these lesions with ring enhancement. Autopsy revealed about 30 calcified metastatic nodules in the brain, but no calcification in the pulmonary lesion. Histological examination of the brain lesions disclosed necrosis and calcification in the center and small cell carcinoma cells in the periphery.

Brain Diseases↗
PubMed1991

[Sequential changes in content of excitatory amino acids in the epileptic focus during seizure].

Recently much attention has been paid to excitatory amino acids in seizure susceptibility and induction. In order to examine the relationship between epilepsy, especially seizure induction, and excitatory amino acids, we examined sequential change in content of excitatory amino acids in the epileptic focus by microdialysis system in a cat amygdaloid kindling model. Fifteen crossbred adult cats divided into three groups: a sham operation group (Sh) as the control, just after stage 4 group (S4), and just after stage 6 seizure group (S6). Under halothane anesthesia, Microdialysis probe was inserted to the kindled focus, the right amygdala, and glutamate and aspartate contents of extracellular fluid were measured from 15 minutes prior to 30 minutes after seizure by high performance liquid chromatography (HPLC). The probe was perfused with artificial cerebrospinal fluid at a flow rate of 2 microliters/min for 5 minutes. Before seizure, glutamate and aspartate concentration showed no significant changes in the S4 and S6 group compared with the Sh group. But after seizure, glutamate concentration was significantly higher in the S4 and S6 group temporally, while aspartate concentration was higher only in the S6 group temporally. Based on the results that the release of glutamate and aspartate do not change in seizure susceptibility, that glutamate is released in partial seizure, and that glutamate and aspartate are released in generalized seizure from the epileptic focus, excitatory amino acids are involved in seizure induction in a cat amygdaloid kindling.

Amino Acids↗
PubMed1991

[Experimental study on brain reversibility following temporary regional cerebral ischemia; from the point of view of vessel behavior and histological changes].

Using a middle cerebral artery occlusion model in adult cats, we investigated the ischemic time threshold for inflicting damage on cerebral vessel behavior and brain tissue. With the transorbital approach, a middle cerebral artery (MCA) was exposed and temporarily obstructed by a Zen's clip. Animals were divided into ten groups (each group: N = 8) according to the ischemic time of 10, 20, 30 minutes, 1, 2, 4, 6, 8, 12, 24 hours. Five hours after the recanalization, Evans' blue dye was injected intravenously and after further 30 minutes, the brain was fixed with transaortal perfusion for histological examinations. A cranial window was made above the ectosylvian gyrus which has poor anastomosis. The pial vessel behavior was observed through the cranial window and evaluated using an intravital microscope and a videoangiometer. Considering the correlation between functional change of vessel behavior and pathological change in the brain, the threshold time of ischemia inflicting irreversible damage was estimated. In the 30 minute ischemia group, deterioration of vessel behavior began to be observed as well as extravasation of Evans' blue dye. As the ischemic duration became longer, infarction and hemorrhage, which showed close correlation, increased. When the duration of ischemia was 6 hours, the infarcted area was significantly larger than that of the 4-hour ischemia group. Intracranial pressure (ICP) markedly increased as soon as recanalization took place. We think this phenomenon is due mainly to swelling. About three hours after recanalization, ICP further increased due to severe vasogenic edema in addition to the brain swelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[The effect of repeated occlusions of the middle cerebral artery on pial arterial behavior and cerebral structure].

Temporary clipping of the major arterial trunk is a very important maneuver to control excessive unexpected bleeding during a neurosurgical operation, but repeated temporary clippings sometimes give rise to severe neurological deficits after surgery. In clinical practice, a major stroke can occur after many transient ischemic attacks without distinct angiographic occlusion. To confirm and explain these clinical experiences, the present study was performed. First, 20-min, 30-min and 1-h occlusion of the middle cerebral artery was performed in each of 5 cats, and pial arterial behavior, cerebral edema and infarction were observed. In the 20-min occlusion group, no abnormal change was found 5 hours after recirculation. In the 30-min occlusion group, cerebral edema was present in 10.5 +/- 4.2% of the hemisphere, but no infarction was observed, and pial arterial caliber remained in a 10% dilated state throughout the experimental periods. In the 1-h occlusion group, cerebral edema was present in 41.2 +/- 7.5% of the hemisphere and infarction was found in 34.5 +/- 9.5%. Pial arteries returned to a 20% dilated state but redilated by 45% at the end of experiment. As the second experiment, three 20-min occlusions at 1-h interval and two 30-min occlusions at 1-h interval were performed in each 10 cats. Pial arteries had dilated by 40% after release of the last occlusion in both groups. The extent of cerebral edema was 19.5 +/- 8.1% of hemisphere in the 20-min occlusions group and 36.6 +/- 9.7% in the 30 min occlusions group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Cerebral transmural angiitis and ruptured cerebral aneurysms in patients with systemic lupus erythematosus.

Two cases of cerebral transmural angiitis and ruptured aneurysm in patients with established systemic lupus erythematosus are presented. A 22-year-old woman with a 4-year history of systemic lupus erythematosus was found to have a ruptured cerebral aneurysm at the trifurcation of the middle cerebral artery. She died 10 days after admission because of the brain swelling. Necropsy showed remarkable brain edema and focal transmural angiitis at the site of the ruptured aneurysm. Another 29-year-old woman with a 3-year history of systemic lupus erythematosus had an acute subdural hematoma resulting from a ruptured aneurysm of the right anterior cerebral artery. She was surgically treated. The ruptured aneurysm was resected and examined histologically. The transmural angiitis was demonstrated. This report describes two radiographically and pathologically confirmed cases of central nervous system lupus producing focal angiitis of a cerebral artery with secondary aneurysm formation.

Adult↗
PubMed1990

Expression of bovine cytochrome P450c21 and its fused enzymes with yeast NADPH-cytochrome P450 reductase in Saccharomyces cerevisiae.

Recombinant plasmids for expression of bovine cytochrome P450c21 (pA gamma 2), both P450c21 and yeast NADPH-cytochrome P450 reductase (pAR gamma 1), P450c21/yeast reductase fused enzymes (pAF gamma R1, pAF gamma R2, and pAF gamma R20), and yeast reductase/P450c21 fused enzymes (pAFR gamma 1 and pAFR gamma 2) were constructed by using expression vector pAAH5. The plasmids were each introduced into the yeast Saccharomyces cerevisiae AH22 cells. The recombinant yeast strains AH22/pA gamma 2 (Y21) and AH22/pAR gamma 1 (Y21R) produced 2-3 X 10(3) molecules of P450c21 per cell. The cultures of both strains converted progesterone and 17 alpha-hydroxyprogesterone into 11-deoxycorticosterone and 11-deoxycortisol, respectively. The 21-hydroxylase activity per cell of the strain Y21R was about three times higher than that of the strain Y21, probably due to overproduction of yeast reductase. The recombinant yeast strains AH22/pAF gamma R1 (Y21RF1), AH22/pAF gamma R2 (Y21RF2), and AH22/pAF gamma R20 (Y21RF20) produced about 1.1-2.0 X 10(4) molecules per cell of the corresponding P450c21/yeast reductase fused enzymes. The specific 21-hydroxylase activity toward 17 alpha-hydroxyprogesterone per cell of the strains Y21RF1, Y21RF2, and Y21RF20 was about 21, 28, and 49 times higher than that of the strain Y21, respectively. Thus, the fused enzymes were superior to P450c21 in the specific activity and in the expression level in the yeast. The Km values for 17 alpha-hydroxyprogesterone of P450c21 in the strains Y21 and Y21R, and of the fused enzymes in the strains Y21RF1 and Y21RF2 were 0.29, 0.30, 0.67, and 0.65 microM, respectively. The Vmax values of P450c21 in the strains Y21 and Y21R, and of the fused enzymes in the strains Y21RF1 and Y21RF2 were 28, 124, 151, and 222 moles/min.mole P450c21 or fused enzyme, respectively. These results indicated that the fused enzymes showed lower affinity for the substrate, probably due to structural modification and higher reaction rates through efficient intramolecular electron transfer as compared with those of P450c21. While the strain AH22/pAFR gamma 2 (YR21F2) produced about 3 X 10(4) molecules per cell of the reductase/P450c21 fused enzyme, the specific 21-hydroxylase activity of the fused enzyme toward 17 alpha-hydroxyprogesterone was extremely low, suggesting that the structure of the fused enzyme might not be suited for electron transfer in yeast microsomes.

17-alpha-Hydroxyprogesterone↗
PubMed1990

Expression of cloned yeast NADPH-cytochrome P450 reductase gene in Saccharomyces cerevisiae.

The NADPH-cytochrome P450 reductase gene isolated from the yeast Saccharomyces cerevisiae [Yabusaki et al., J. Biochem. 103, 1004-1010 (1988)] was expressed on a multi-copy plasmid in the yeast. The transformed yeast cells with the recombinant plasmid carrying the reductase gene with a length of 3 kb produced the corresponding mRNA read from the original transcription initiation site under the control of its own promoter with a maximum length of 300 bp. The reductase content in the transformed cells was 25 times higher than that of the endogenous reductase. When the coding region for the reductase was placed between the alcohol dehydrogenase I gene promoter and the terminator of the expression vector pAAH5, the expression level was 32 times higher than at the endogenous level. These recombinant yeast strains showed enhanced cytochrome c reductase activity with increased cellular reductase levels. A simultaneous expression of yeast P450 reductase with rat P450c or bovine P450(17 alpha) resulted in 25 times or a 5 times increase in the corresponding P450-dependent monooxygenase activity of the recombinant yeast strains, respectively, as compared with that of the yeast cells expressing the corresponding P450 species. These results suggested that the overproduction of yeast P450 reductase with a simultaneous expression of the mammalian P450 species enhanced the P450c- and P450(17 alpha)-dependent monooxygenase activities in the recombinant yeast strains, probably due to the increased frequency of the interaction between yeast P450 reductase and P450c or P450(17 alpha) in the yeast microsomes.

Alcohol Dehydrogenase↗
PubMed1990

The influence of volume expansion with induced hypertension on vessel reactivities, the blood-brain barrier, and cerebral infarction in cats with one-hour occlusion of the middle cerebral artery.

Thirty anesthetized cats were randomly assigned to three groups of 10 cats each: a 10% hydroxyethyl starch-treated group (10% HAES group), a 6% hydroxyethyl starch-treated group (6% HAES group), or a control group. Cerebral pial arterial reactivities were measured by means of intravital microscopic observation through a cranial window. The middle cerebral artery of the cat was clipped for 1 hour using the transorbital approach, 5 hours later Evans blue dye was injected intravenously, and 30 minutes later the animals was killed. Administration of hydroxyethyl starch or saline was started 15 minutes before clipping and lasted for 1 hour. Total volume administered was 10 ml/kg. Systemic arterial pressure was elevated to about 30 to 40% higher than the resting value by administration of dopamine soon after clipping and maintained for 1 hour. In the hydroxyethyl starch-treated groups, the sizes of infarctions and Evans blue dye leakage were significantly smaller than in the control group. Dye leakage in the 10% HAES group was larger than in the 6% HAES group (statistically significant). Regarding pial arterial reactivities, the caliber of arteries was different in each group after reopening of the clip. Arteries in the control group first returned to some 20% of resting state and redilated 40% or more, arteries in the 6% HAES group returned almost to the resting calibers, and arteries in the 10% HAES group constricted by -20% of the resting calibers. Moreover, 8 of 10 cats in the 10% HAES group showed extravasation of red cells. Only one cat in the 6% HAES group showed extravasation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of repeated temporary clipping of the middle cerebral artery on pial arterial diameter, regional cerebral blood flow, and brain structure in cats.

Temporary clipping of the major arterial trunk is an important maneuver to control excessive unexpected bleeding in neurosurgical operations; however, repeated temporary clipping can give rise to severe neurological deficits after surgery. The present study was performed to confirm and explain these clinical findings. Initially, a single 20-minute or 1-hour occlusion of the middle cerebral artery was performed in each of 5 cats. Pial arterial diameter was determined by video imaging, regional cerebral blood flow was measured by autoradiography, and cerebral edema and infarction were observed. In the 20-minute occlusion group, no abnormal changes were found 5 hours after recirculation. In the 1-hour occlusion group, pial arteries were dilated by 45%, and regional cerebral blood flow increased to more than twice the resting cortical values. The extent of cerebral edema was 41.2 +/- 7.5% (SE) and infarction was 34.5 +/- 9.5% (SE) of the hemisphere. In the second experiment, three 20-minute occlusions of the middle cerebral artery in a 1-hour interval were performed in 20 cats. In 10 of them, thiopental (40 mg/kg) was used to protect the brain. In the group without barbiturate treatment, pial arteries were dilated by 40% at the end of experiment, regional cerebral blood flow decreased to about 70% compared with single 20-minute occlusion, cerebral edema was 19.5 +/- 8.1% (SE), and infarction was 8.1 +/- 3.7% (SE) of the hemisphere. In the treated group, these were only trivial changes. The effect of repeated clipping may cumulatively cause brain damage, and barbiturates should be used whenever repeated clipping is necessary.

Animals↗
PubMed1990

Conversion of monogalactosyldiacylglycerols to triacylglycerols in ozone-fumigated spinach leaves.

Molecular species and fatty acid distribution of triacylglycerol (TG) accumulated in spinach (Spinacia oleracea L.) leaves fumigated with ozone (0.5 microliter per liter) were compared with those of monogalactosyldiacylglycerol (MGDG). Analysis of positional distribution of the fatty acids in MGDG and the accumulated TG by the enzymatic digestion method showed that hexadecatrienoate (16:3) was restricted to sn-2 position of the glycerol backbone in both MGDG and TG, whereas alpha-linolenate (18:3) was preferentially located at sn-1 position in MGDG, and sn-1 and/or sn-3 positions in TG, suggesting that 1,2-diacylglycerol moieties of MGDG are the direct precursor of TG in ozonefumigated leaves. Further analysis of TG molecular species by argentation chromatography and mass spectrometry showed that TG increased with ozone fumigation consisted of approximately an equal molar ratio of sn-1,3-18:3-2-16:3 and sn-1,2,3-18:3. Because the molecular species of MGDG in spinach leaves is composed of a similar molar ratio of sn-1-18:3-2-16:3 and sn-1,2-18:3, we concluded that MGDG was converted to 1,2-diacylglycerol and acylated with 18:3 to TG in ozone-fumigated spinach leaves.

Journal Article↗
PubMed1990

Pathway for the synthesis of triacylglycerols from monogalactosyldiacylglycerols in ozone-fumigated spinach leaves.

When the upper leaf surface of spinach (Spinacia oleracea L.) plants was treated with [1-(14)C]acetate and grown for 2 days, (14)C was effectively incorporated into acyl moieties of leaf lipids in ratios approximately their composition by mass. Fumigation of the plants with ozone (0.5 microliter per liter) caused a redistribution of (14)C among lipid classes, i.e. a marked increase of (14)C content in triacylglycerol (TG) and 1,2-diacylglycerol (1,2-DG) and a decrease of label in monogalactosyldiacylglycerol (MGDG) without affecting (14)C distribution in leaf fatty acids. Label in both TG and 1,2-DG was found predominantly in their polyene molecular species. Since MGDG consists of similar polyene molecular species, the results indicate the synthesis of TG from MGDG via 1,2-DG. Label was also accumulated in tri- and tetragalactosyldiacylglycerol, products of galactolipid:galactolipid galactosyltransferase (GGGT). Moreover, there was a close relation between increases in the amounts of TG and the oligogalactolipids in ozonetreated leaves. These results indicate that MGDG was converted to 1,2-DG by GGGT and then to TG. In intact chloroplasts isolated from ozone-treated leaves, there was an enhanced production of free fatty acid (FFA), which was diminished by the addition of coenzyme A (CoA) and ATP, indicating that ozone stimulated the hydrolysis of MGDG to liberate FFA, which was in turn converted to acyl-CoA. The final step of TG synthesis, acylation of 1,2-DG with acyl-CoA, was confirmed by feeding with [1-(14)C]linolenic acid in leaf discs excised from ozone-fumigated leaves; (14)C was effectively incorporated into TG but not into 1,2-DG. These results demonstrate the synthesis of TG from 1,2-DG and FFA which were liberated from MGDG in ozone-fumigated spinach leaves.

Journal Article↗
PubMed1990

Free Fatty acids regulate two galactosyltransferases in chloroplast envelope membranes isolated from spinach leaves.

Effects of MgCl(2) and free fatty acids (FFA) on galactolipid:galactolipid galactosyltransferase (GGGT) and UDP-galactose: 1,2-diacylglycerol galactosyltransferase (UDGT) in chloroplast envelope membranes isolated from spinach (Spinacia oleracea L.) leaves were examined. GGGT activity was sigmoidally stimulated by MgCl(2) with a saturated concentration of more than 5 millimolar. Free alpha-linolenic acid (18:3) caused a drastic increase in GGGT activity under limiting concentrations of MgCl(2), without affecting its maximum activity at higher MgCl(2) concentrations. Free 18:3 alone did not affect the GGGT activity. The effective species of FFA for the stimulation of GGGT activity in the presence of MgCl(2) were unsaturated 16- and 18-carbon fatty acids. GGGT activity was also stimulated by 18:3 in the presence of MnCl(2), CaCl(2) and a high concentration of KCl in place of MgCl(2). UDGT activity was hyperbolically enhanced by MgCl(2) with a saturated concentration of 1 to 2 millimolar. In contrast to GGGT, UDGT was severely inhibited by 18:3, and MgCl(2)-induced stimulation was completely abolished by 18:3. Unsaturated 16- and 18-carbon fatty acids were more inhibitory to UDGT than the saturated acids. The dependence of GGGT activity on monogalactosyldiacylglycerol (MGDG) and MgCl(2) concentrations was identical in the envelope membranes isolated from non- and ozone (0.5 microliter/liter)-fumigated spinach leaves, indicating that GGGT remained active in the leaves during ozone fumigation. The results are discussed in relation to the regulation of galactolipid biosynthesis by the endogenous FFA in the envelopes and to the involvement of GGGT in the triacylglycerol synthesis from MGDG in ozone-fumigated leaves.

Journal Article↗
PubMed1990

Is Chiari I malformation in the aged initiated by mechanical factors? Report of three cases.

Three cases in which the signs and symptoms of Chiari I malformation were induced and worsened after the occurrence of supratentorial mass lesions are reported. The symptoms improved markedly after removal of the supratentorial lesions in these cases. In the first case, a meningioma in the right parietal region coexisted with Chiari I malformation. Although the cerebellar ataxia and nystagmus disappeared after tumor removal, decompressive surgery for the malformation was performed because of upper cervical nerve symptoms and the patient recovered completely. In the second case, the symptoms first occurred after a car accident, and a computed tomographic scan revealed not only a subdural hematoma, but also tonsillar herniation due to Chiari I malformation. After evacuation of the hematoma and decompressive surgery on the craniospinal junction, the symptoms disappeared. In the third case, the symptoms of malformation developed gradually with depression and gait disturbance. A meningioma in the left frontal region coexisted with Chiari I malformation. Although the symptoms improved remarkably after tumor removal, decompressive surgery on the craniospinal junction was performed because of upper cervical nerve symptoms, and the patient recovered completely. These clinical findings indicate that a supratentorial mass lesion may provoke the symptoms of Chiari I malformation in the aged.

Aged↗
PubMed1990

Hemangioblastomas of the central nervous system--immunohistochemical and ultrastructural study.

Immunohistochemical studies using immunoperoxidase staining for glial fibrillary acidic protein (GFAP), S-100 protein, and factor VIII-related antigen (VIII-RAg) were performed on 10 hemangioblastomas of the central nervous system to determine the origin of stromal cells. No cytoplasmic immunoreactivity for anti-GFAP, anti-S-100 protein, or anti-VIII-RAg was detected in most stromal cells. A small number of GFAP-positive cells were found only in the periphery of the tumor; they were thought to be trapped astrocytes or stromal cells taking up GFAP. Most stromal cells had abundant, clear cytoplasm with some microfilaments and lipid vacuoles. Cylindrical cytoplasmic processes and intermediate junctions were observed in some stromal cells, but most cells did not possess any junctional device. No stromal cell possessed any feature clearly suggesting endothelial cells or pericytes. Our immunohistochemical and ultrastructural investigations did not support the theories of stromal cell origin from astrocytes or endothelial cells. We concluded that stromal cells can be regarded as an aberrant cell type of angiogenic mesenchymal derivation.

Adolescent↗