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Biomedical subjects

S Takikawa

Publications and source records attributed to S Takikawa.

36 records · Page 2Linked to original sources
PubMed1994

Input functions for 6-[fluorine-18]fluorodopa quantitation in parkinsonism: comparative studies and clinical correlations.

UNLABELLED: PET has been used to quantify striatal 6-[18F]fluoro-L-dopa (FDOPA) uptake as a measure of presynaptic dopaminergic function. Striatal FDOPA uptake rate constants (Ki) can be calculated using dynamic PET imaging with measurements of the plasma FDOPA input function determined either directly or by several estimation procedures. METHODS: We assessed the comparative clinical utility of these methods by calculating the striato-occipital ratio (SOR) and striatal Ki values in 12 patients with mild to moderate PD and 12 age-matched normal volunteers. The plasma FDOPA time-activity curve (KiFD); the plasma 18F time-activity curve (KiP); the occipital time-activity curve (KiOCC); and a simplified population-derived FDOPA input function (KiEFD) were used to calculate striatal Ki. RESULTS: Mean values for all striatal Ki estimates and SOR were significantly lower in the PD group. Although all measured parameters discriminated PD patients from normals, KiFD and KiEFD provided the best between-group separation. KiFD, KiEFD and KiOCC measures correlated significantly with quantitative disease severity ratings, although KiFD predicted quantitative clinical disability most accurately. CONCLUSION: These results suggest that KiFD may be an optimal marker of the parkinsonian disease process. KiEFD may be a useful alternative to KiFD for most clinical research applications.

Adult↗
PubMed1993

Striatal hypometabolism distinguishes striatonigral degeneration from Parkinson's disease.

Regional and global metabolic rates for glucose were estimated using 18F-fluorodeoxyglucose and positron emission tomography in 10 patients with a clinical likelihood of striatonigral degeneration (2 men and 8 women; mean age, 61.8 +/- 6.9 years; mean disease duration, 4.7 +/- 2.2 years; mean Hoehn and Yahr score, 3.5 +/- 0.8). Measures of brain glucose metabolism in these patients were compared with those for 10 age-matched normal volunteers, 10 disease severity-matched patients with Parkinson's disease (PD), and 10 disease duration-matched patients with PD. Normalized glucose metabolism was significantly reduced in the caudate (p < 0.03) and putamen (p < 0.003) as compared with that in normal and PD control subjects, and discriminated patients with striatonigral degeneration from control subjects (p < 0.002). Putamenal hypometabolism in patients with striatonigral degeneration correlated significantly with quantitative ratings of motor disability (p < 0.02). These results suggest that quantitative 18F-fluorodeoxyglucose positron emission tomography techniques may be useful in supporting a diagnosis of striatonigral degeneration in life, and in objectively assessing disease severity and potential therapeutic interventions.

Aged↗
PubMed1993

Positron emission tomographic findings in Filipino X-linked dystonia-parkinsonism.

Regional and global metabolic rates for glucose (rCMRGlc and GMR) were estimated using [18F]fluorodeoxyglucose and positron emission tomography in 3 patients with Filipino X-linked dystonia-parkinsonism (lubag). In all 3 patients a selective reduction in normalized striatal glucose metabolism (rCMRGlc/GMR) was observed compared with 15 normal volunteer subjects. Presynaptic nigrostriatal function was assessed in these patients using [18F]fluorodopa and positron emission tomography. Striatal rate constants for [18F]flurodopa uptake were found to be in the normal range in all 3 patients with lubag. These findings suggest that the extrapyramidal manifestations of lubag are metabolically localized to the striatum and that clinical parkinsonism in these patients may be secondary to extranigral factors.

Adult↗
PubMed1993

Striatal 18F-dopa uptake: absence of an aging effect.

L-[18F]6-Fluoro-DOPA (L-[18F]6-fluoro-3,4-dihydroxyphenylalanine; FDOPA) has been used with quantitative positron emission tomography (PET) to assess presynaptic nigrostriatal dopaminergic function in life. The relationship of estimated kinetic rate constants for striatal FDOPA uptake [Ki(FDOPA)] to the normal aging process has been the subject of conflicting reports. Resolution of this issue has been hampered by methodological differences in previous FDOPA/PET investigations. We studied 19 healthy normal subjects (aged 27-77 years) and measured striatal Ki-(FDOPA) according to each of the earlier methods. While significant correlations (p < 0.005) existed between Ki(FDOPA) values estimated by the various techniques, none correlated with normal aging. We conclude that normal striatal Ki(FDOPA) values estimated using quantitative FDOPA/PET are uncorrelated with the aging process.

Adult↗
PubMed1993

Noninvasive quantitative fluorodeoxyglucose PET studies with an estimated input function derived from a population-based arterial blood curve.

The authors have developed a technique to estimate input functions from a population-based arterial blood curve in positron emission tomography (PET) studies with fluorine-18 fluorodeoxyglucose (FDG). A standardized pump injection was used in 34 subjects. A population-based blood curve was generated based on the first 10 subjects. In the remaining 24 subjects, an estimated input function (EIFa) was obtained by scaling the population-based curve with two arterial blood samples, one obtained at 10 minutes and the other at 45. Time integrals for EIFa and the real arterial input function (RIF) were in excellent agreement (r = .998, P < .0001). Cerebral metabolic rates for glucose calculated with EIFa and RIF and the autoradiographic method also correlated excellently (r = .992, P < .0001). Analogous correlations were achieved with arterialized venous samples as scaling factors. These results suggest that individually scaled, population-derived input functions may serve as an adequate alternative to continuous arterial blood sampling in quantitative FDG-PET imaging.

Adult↗
PubMed1992

Pteridines in the yellow-colored chromatophores of the isopod, Armadillidium vulgare.

Biochemical analyses of the dorsal integument of the isopod, Armadillidium vulgare, revealed that sepiapterin, biopterin, pterin, isoxanthopterin and uric acid accumulated in the yellow-colored chromatophores which are distinguishable from ommochrome chromatophores. The pattern of the yellow-colored chromatophores in the female is externally observable at the dorsal surface of the integument as yellow markings. In contrast, the yellow-colored chromatophores are not externally observable in the male, since they are covered by an ommochrome chromatophore layer. The content of both sepiapterin and biopterin in the male chromatophores was about two times greater than that in the female. The yellow-colored chromatophores were observable by light microscopy as pigmented granules. Electron microscopy showed that morphological properties of the granules were similar to those of pteridine granules which contain uric acid occurring in the silkworm integument. These facts indicate that both pteridines and uric acid in the integument of A. vulgare are localized in the pigmented granules of the yellow-colored chromatophores.

Animals↗
PubMed1991

Proximal clipping and bypass between bilateral vertebral arteries using a radial arterial graft for the treatment of a dissecting aneurysm of the vertebral artery.

Proximal clipping has been performed recently as the main surgical treatment for a dissecting aneurysm of the vertebral artery. When there is a contralateral vertebral artery of a smaller size with arteriosclerotic changes, some form of bypass to prevent cerebellar and brain stem infarction is needed in addition to proximal clipping. We treated a 50-year-old man with a ruptured dissecting aneurysm of the left vertebral artery and stenosis at the V3 segment of the right vertebral artery. The caliber of the right vertebral artery was smaller than the left. After an anastomosis between bilateral vertebral arteries using a radial arterial graft, dissecting aneurysm was clipped at the proximal portion of the aneurysm.

Aortic Dissection↗
PubMed1991

[Neurological deterioration due to cerebral hyperperfusion following carotid endarterectomy. Case report].

Recently attention has been drawn to postoperative cerebral hyperperfusion after carotid endarterectomy (CEA) associated with a preoperative state of impaired cerebral hemodynamics. Rarely postoperative neurological deficits are caused by cerebral edema due to hyperperfusion. The patient was a 65-year-old male with dysarthria and right hemiparesis. Because of the presence of severe stenosis of the left carotid artery, CEA was performed. On the 6th postoperative day, he developed severe right hemiparesis and aphasia due to cerebral edema in the subcortical region of the left cerebral hemisphere. Left carotid angiography showed normal circulation without evidence of the carotid stenosis. Later the cerebral edema and the neurological deficits gradually disappeared.

Aged↗
PubMed1991

[Vertebral dissecting aneurysm treated with trapping and bilateral posterior inferior cerebellar artery side-to side anastomosis; case report].

A case is reported of ruptured dissecting aneurysm of the intracranial vertebral artery (VA) operated on with VA trapping and bilateral posterior inferior cerebellar artery (PICA) side-to-side anastomosis. A 42-year-old male suddenly developed severe headache and vomiting. On admission, 3 hours later, he was in a state of moderate confusion (Japan Coma Scale 3) and had neck stiffness. Computed tomography (CT) revealed diffuse subarachnoid hemorrhage, especially thick in the posterior fossa with right side dominance. Right vertebral angiography disclosed a fusiform dilatation with proximal narrowing of the right VA which originated just proximal to the VA-PICA junction. Lateral suboccipital craniectomy was undertaken with the patient in a left park bench position. Right VA was dilated and discolored black, and right PICA arose from the proximal portion of this aneurysmal dilatation. Since it was impossible to clip the VA distal to the PICA for the proximal clip-occlusion, the VA including the VA-PICA junction was trapped. Considering the risk of developing infarction at the PICA territory, bilateral PICA was anastomosed at their posterior medullary segment in a side-to-side fashion because the occipital artery (OA) had been cut at the skin incision and could not be used for the OA-PICA anastomosis. The postoperative course was benign, but a mild lateral medullary syndrome developed. CT revealed no abnormal low density area and left vertebral angiography demonstrated the patency of the bypass. Thereafter, the deficit subsided gradually and the patient was discharged. He is presently working without neurological deficit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Usefulness of MRI in the diagnosis of spontaneous hematomyelia; a case of intramedullary cavernous hemangioma].

Recent improvement of MRI has enabled us to clearly visualize intramedullary spinal lesions which previously could not be recognized by CT scan or myelography. We reported a case of hematomyelia caused by intramedullary cavernous hemangioma. In this case, MRI was very useful in efforts to recognize the lesions. With the use of MRI, we will be able to accurately ascertain the location and characteristics of intramedullary spinal lesions. The number of surgically treated cases of idiopathic hematomyelia will increase in the future.

Hemangioma, Cavernous↗
PubMed1991

[A case report: intraspinal canal osteochondroma at the cervicothoracic junction causing spinal cord compression].

Osteochondromas are one of the most common benign tumors. They typically develop on long, tubular bones, only rarely compressing the spinal cord. We report the case of a 9-year-old boy who suffered paraparesis secondary to a cervical osteochondroma based at the vertebral body. The tumor was removed using laminectomy. CT scanning, plain X-ray films, and MR imaging were used in the preoperative assessment of the lesion and the operative method.

Child↗
PubMed1990

Hemodynamic evaluation of vascular reconstructive surgery for childhood moyamoya disease using single photon emission computed tomography.

To evaluate the efficacy of vascular reconstructive surgery for childhood moyamoya disease, the cerebral blood flow (CBF) in 31 hemispheres of 16 patients was examined by single photon emission computed tomography (SPECT) using the 133Xe inhalation method. Results were divided into two groups; 17 hemispheres with superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis [A(+) group] and 14 hemispheres without anastomosis [A(-) group]. The mean hemispheric CBF (mCBF) and regional CBF (rCBF) in the frontal, temporal, occipital, and basal ganglia regions were calculated. Pre- and postoperative SPECT on the 10 hemispheres of the A(+) group showed an increase in mCBF in 6 hemispheres, the disappearance of the low perfusion area (LPA) in all 5 hemispheres where LPA was present before surgery, and an improvement in rCBF distribution (an increase in rCBF in the frontal and temporal lobes and a decrease in the basal ganglia). This suggests that vascular reconstruction is greatly effective in treating this disease. A comparison between the A(+) group and the A(-) group by postoperative SPECT, as well as the clinical outcomes and the postoperative findings of electroencephalography and angiography, revealed that the A(+) group was superior to the A(-) group in the frequency of LPA (12% and 43%, respectively) and rCBF in the frontal region where STA-MCA anastomosis was usually performed. These results indicate that STA-MCA anastomosis with indirect synangiosis is the most effective treatment of childhood moyamoya disease.

Adolescent↗
PubMed1990

[Complete occlusion of right middle cerebral artery by radiation therapy after removal of pituitary adenoma: case report].

Radiation angiopathy is a well-known complication accompanying irradiation. But the majority of effected vessels are small vessels. Cases of intracranial major arteries being effected are not so numerous. We report the case of a 47-year-old female patient. The removal of pituitary adenoma was carried out on her in 1982. After that, 4500rad irradiation was performed. It was about six years after irradiation that the first angiography was made. Right MCA occlusion, multiple stenosis of both ACAs and Moya-Moya like vessels were discovered. On admission light paresis on her left lower extremity was recognized and hyperlipidemia was noted. It was interesting that the multiple stenosis was found in an area outside the irradiation field. MCA-STA anastomosis was performed and the prognosis was good. The authors described this case and reviewed the pertinent literature.

Adenoma↗
PubMed1986

Biosynthesis of tetrahydrobiopterin. Purification and characterization of 6-pyruvoyl-tetrahydropterin synthase from human liver.

6-Pyruvoyl-tetrahydropterin synthase, which catalyzes the first step in the conversion of 7,8-dihydroneopterin triphosphate to tetrahydrobiopterin, was purified approximately 140,000-fold to apparent homogeneity from human liver. The molecular mass of the enzyme is estimated to be 83 kDa. 7,8-Dihydroneopterin triphosphate was a substrate of the enzyme in the presence of Mg2+, and the pH optimum of the reaction was 7.5 in Tris HCl buffer. The Km value for 7,8-dihydroneopterin triphosphate was 10 microM. The product of this enzymatic reaction was the presumed intermediate 6-pyruvoyl-tetrahydropterin. This latter compound was converted to tetrahydrobiopterin in the presence of NADPH and partially purified sepiapterin reductase from human liver. The conditions and the effect of N-acetylserotonin on this reaction, and on the formation of the intermediates 6-(1'-hydroxy-2'-oxopropyl)-tetrahydropterin and 6-(1' oxo-2'-hydroxypropyl)-tetrahydropterin have been studied.

Alcohol Oxidoreductases↗
PubMed1986

Purification of 6-pyruvoyl-tetrahydropterin synthase from human liver.

The enzyme which catalyzes the first step in the conversion of dihydroneopterin triphosphate to tetrahydrobiopterin has been purified approx. 40,000-fold from human liver to apparent homogeneity. The enzyme has a native molecular weight of approximately 83,000 and consists of four identical subunits, each of which has a molecular weight of approximately 19,000. It contains carbohydrates and is remarkably stable to heat treatment. In the presence of purified sepiapterin reductase, Mg2+, and NADPH, this enzyme catalyzes efficiently the formation of tetrahydrobiopterin from dihydroneopterin triphosphate. This indicates that these two proteins are sufficient for the overall conversion.

Alcohol Oxidoreductases↗
PubMed1979

Pterin deaminase from Bacillus megaterium. Purification and properties.

A pterin deaminase catalyzing the hydrolytic deamination of various pteridines was found in the bacterium, Bacillus megaterium, and partially purified from bacterial extract. The specific activity was raised 90-fold over that of the crude extract. The pH optimum is around 7.3, and the Km value for 6-carboxypterin is 1.3 mM. The molecular weight of the enzyme was estimated by gel filtration to be about 110,000. The enzyme deaminated pterin, 6-carboxypterin, biopterin, 6-methylpterin, 7-methylpterin, xanthopterin, 6-hydroxymethylpterin, sepiapterin, isosepiapterin, folic acid, and 6,7-dimethylpterin to their corresponding lumazines, whereas guanine, 7-carboxypterin, leucopterin, isoxanthopterin, and 6-methylisoxanthopterin did not serve as substrates. The enzyme was inhibited by PCMB and 8-azaguanine.

Aminohydrolases↗