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Biomedical subjects

S Watanuki

Publications and source records attributed to S Watanuki.

At least 55 records · Page 3Linked to original sources
PubMed1988

Measurement of the ratio of cerebral oxygen consumption to glucose utilization by positron emission tomography: its consistency with the values determined by the Kety-Schmidt method in normal volunteers.

The regional interrelationship between cerebral oxygen consumption (CMRO2) and cerebral glucose utilization (CMRGlc) was studied in normal subjects using positron emission tomography (PET) and the 15O steady-state inhalation and the [18F]fluoro deoxyglucose method. The use of standard sets of rate constants and the model lumped constant of 0.52 as well as the regional blood-brain partition coefficient for water and the blood volume correction for oxygen extraction fraction provided a CMRO2/CMRGlc ratio of 4.89 in the cortical gray matter, 5.27 in the basal ganglia and 5.82 in the centrum semiovale (white matter). The values of CMRO2/CMRGlc for the basal ganglia and the white matter were consistent with those reported for the whole brain with the Kety-Schmidt method. There was no significant difference in the CMRO2/CMRGlc between the basal ganglia and the white matter indicating the similar nature of in vivo oxidative metabolism of glucose in neuron-rich region and glial cell-rich region.

Aged↗
PubMed1987

Myocardial imaging using 11C-CoQ10 with positron emission tomography.

The potential of 11C-labeled coenzyme Q10(CoQ10) as a myocardial imaging tracer was explored with positron emission tomography (PET). Serial myocardial imaging studies were performed using 11C-CoQ10, 45Ti-diethylenetriaminepentaacetic acid (45Ti-DTPA), and 2-deoxy-2-[18F]fluoro-D-mannose (18FDM) in the same dog. Cross sectional images of the heart with 11C-CoQ10 showed relatively high radioactivity in the blood pool, when compared with images taken with 18FDM. However, when the blood spillover of radioactivity is adequately corrected with 45Ti-DTPA data, it was found that 11C-CoQ10 accumulated in the myocardium with time.

Animals↗
PubMed1986

Metabolic imaging in hemianopsia using positron emission tomography with 18F-deoxyfluoroglucose.

To evaluate the usefulness of metabolic mapping by positron emission tomography using 18F-deoxyfluoroglucose as a tracer in the diagnosis of hemianopsia, we examined eight patients who had had cerebrovascular accident, and four controls. Neuro-ophthalmologic examination disclosed hemianopsia in five and incomplete hemianopsia in three patients; computed tomography showed low-density areas in four patients; and nuclear magnetic resonance imaging demonstrated a prolonged T2 area in five patients. The cerebral metabolic rate for glucose without visual stimulation in the visual cortex was 7.4 +/- 1.0 mg/min/100 g of brain without interhemispheric asymmetry. Light stimulation increased cerebral metabolic rate for glucose in the visual cortex of the nonaffected hemisphere and decreased it in the affected hemisphere. Asymmetry in the metabolic rate in the posterior medial occipital cortex in complete hemianopsia was 22% 12% (P less than .01).

Adult↗
PubMed1986

Characteristics of specific in vivo labeling of neuroleptic binding sites with 3-N-[11C]methylspiperone.

In vivo binding of 3-N-[11C]methylspiperone ([11C]NMSP) was saturable in the rat forebrain, but not in the cerebellum. Nonspecific binding was almost equivalent in all brain regions except for the white matter. [11C]NMSP binding was localized to receptor-rich fractions when low doses were administered (less than 20 nmol/kg body weight). The striatum-to-cerebellum ratio was a function of time after injection and administered dose. This ratio remained constant in low doses of under 30 nmol/kg. The radioactivity curve of the cerebellum in a control positron-emission tomographic study almost equaled that of the striatum in the dog pretreated with spiperone (2 mg). This indicates that the amount of binding in the cerebellum might be considered a nonspecific binding and unbound pool. The data obtained by the pretreatment study was different from that of displacement, which suggested that displaceable [11C]NMSP in the specific binding sites of the striatum was not completely cleared from the brain tissue by a large amount of unlabeled spiperone.

Animals↗
PubMed1986

Simplified enzymatic synthesis and biodistribution of 11C-S-adenosyl-L-methionine.

11C-S-Adenosyl-L-methionine (11C-SAM) was synthesized enzymatically from 11C-L-methionine using rat-liver extract [40%-50% saturated (NH4)2SO4 fraction] as the enzyme source. In biodistribution studies in rats, the highest uptake of 11C-SAM was found in the kidneys. 11C-SAM was also accumulated in the small intestine, pancreas, adrenal gland, liver, and spleen. The uptake of 11C-SAM in the brain increased with time, but remained low. At 30 min after injection, about 50%-60% of the 11C radioactivity was present in the acid-insoluble fraction of the kidneys and liver. When a high loading dose of 11C-SAM was administered, the kidney uptake was enhanced, but the proportion of the radioactivity present in the acid-insoluble fraction was lower. In a study of one rabbit, the kidney uptake was of 11-SAM clearly visualized using positron-emission tomography.

Animals↗
PubMed1986

Orbital tumor diagnosis by positron emission tomography using 18F-fluorodeoxyuridine.

The distribution of 18F-labeled 5-fluoro-2'-deoxyuridine (18F-FdUrd) in orbital tissue, tumor and aseptic inflammation was examined in rats. The distribution in paraorbital structures, other than bone, was low. The tumor-to-organ ratios were sufficient for tumor imaging by positron emission tomography (PET). Positron emission tomography with 18F-FdUrd clearly showed the experimental orbital VX-2 tumor in rabbits. The difference between the experimental orbital tumor and croton oil-induced aseptic inflammation or a normal orbit was apparently established in the PET image with slow and fast clearance of radioactivity, respectively.

Animals↗
PubMed1985

The influence of clothing ensembles on the lower critical temperature.

This paper describes the effect of clothing insulation on the lower critical temperature (LCT). Twelve young adult females were exposed to a temperature of 10 degrees C for 2 1/2 h. LCT was estimated at five different clothing conditions according to the intersect method. The total weights of clothing ensembles (CW) of the five conditions were 0.45, 0.52, 0.82, 1.34, and 2.56 kg, and their thermal insulating values (I) were 0.44, 0.60, 0.77, 1.21, and 2.14 clo, respectively. LCT of the five clothing ensembles were estimated to be 26.4, 25.4, 23.5, 21.5, and 17.5 degrees C, respectively. The regression equation of the logarithm of LCT on CW was calculated as logLCT = 1.4469-0.08283 CW and that on I was log LCT = 1.4613-0.10526 I, respectively. The rate of changes in LCT is suggested to be dependent on the clothing conditions as for the following equations: dLCT/dCW = -5.34 exp(-0.1907 CW) or dLCT/dI = -7.01 exp(-0.2424 I).

Adolescent↗
PubMed1985

Biodistribution of a positron-emitting suicide inactivator of monoamine oxidase, carbon-11 pargyline, in mice and a rabbit.

Carbon-11 (11C) pargyline, which is a suicide inactivator of Type B monoamine oxidase (MAO), was synthesized by the reaction of N-demethylpargyline with 11CH3I. Biodistribution was investigated in mice, and positron tomographic images of the heart and lung in a rabbit were obtained. The distribution of 11C after administration of [11C]pargyline was measured in several organs and blood at various time intervals. After 30 min its concentrations in the organs were constant. Subcellular distribution studies in the brain, lung, liver, and kidney showed that 59-70% of the 11C became acid-insoluble and 9-33% was present in the crude mitochondrial fraction at 60 min after injection. However, a high loading dose influenced the subcellular distribution but had little effect on tissue distribution. The uptakes of the 11C in each organ except for the kidney and spleen seemed to correlate with the in vitro enzymatic activity of Type B MAO. At high loading dose a nonspecific uptake was observed.

Animals↗