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Biomedical subjects

Y Nemoto

Publications and source records attributed to Y Nemoto.

At least 145 records · Page 8Linked to original sources
PubMed1988

Magnetic resonance images of tuberous sclerosis. Further observations and clinical correlations.

The cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR = 1800, TE = 120) images and inversion recovery (TR = 2100, TI = 500-600, TE = 40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

[Magnetic resonance imaging (MRI) of intracranial chordomas].

MR images of 5 patients with intracranial chordoma were evaluated and compared with those of other clival lesions (1 clival osteomyelitis, 1 metastatic clival tumor, 3 clival meningiomas). The MR examination was performed using a 0.5 T superconductive magnet, with approximately 10 mm section thickness, one average and a 256 x 256 matrix. T1 weighted images were obtained by inversion recovery (IR) with TR 2100-2500 msec, TI 600 msec and TE 40 msec. T2 weighted images were obtained by spin echo pulse sequence with TR 1800-2500 msec and TE 120 msec (long SE). In several cases, the spin echo pulse sequences with TR 1000 msec and TE 40 msec (short SE) were also done. Multiplaned images were obtained. Four of 5 intracranial chordomas were low in intensity compared to cerebral gray matter on T1 weighted images, and all of 5 chordomas were as high in intensity as cerebrospinal fluid or higher than that of cerebrospinal fluid on T2 weighted images. Clival fatty marrow is high intensity on T1 weighted images. Clival involvement by a tumor was a clearly demonstrated as disappearance of this high intensity in all cases. In two cases, the tumor extended to the retropharyngeal space and this was detected clearly on short SE image. Although clival fatty marrow was disappeared, osteomyelitis and metastatic tumor in clivus were iso-intense to cerebral gray matter on both T1 and T2 weighted images.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Magnetic resonance imaging (MRI) of pituitary adenomas].

MRI of 20 patients, 17-82 years old, with pituitary adenomas confirmed histopathologically, and 30 normal patients without pituitary dysfunction were reviewed. The studies were performed with a 0.5 Tesla MR scanner with a slice thickness of 10 mm. Inversion recovery sequences were employed as T 1-weighted examination, with repetition time (TR) of 2100-2500 msec, an inversion time (TI) of 600 msec and an echo time (TE) of 40 msec. The T 2-weighted examination had a TR of 1800-2500 msec and a TE of 120 msec. T 1-weighted images were obtained in all cases and T 2-weighted images in 14 cases. Spin echo images with a TR of 600-1000 msec and a TE of 40 msec (SE 40/600-1000) were also obtained in 14 cases. On T 1-weighted images, 20 adenomas were classified into six groups, according to their signal intensities; marked low intensity (1), low intensity (1), isointensity (11), high intensity (3), marked high intensity (1) and mixed intensity (3). On T 2-weighted images, 14 adenomas were classified into five groups; low intensity (1), isointensity (2), high intensity (4), marked high intensity (6) and mixed intensity (1). On SE 40/600-1000 images, 14 adenomas were also classified into four groups; low intensity (8), high intensity (2) and mixed intensity (3). Two adenomas with recent intratumoral hemorrhage had marked high intensity on both T1 and T2-weighted images. SE 40/600-1000 images were useful in evaluating the size and the extent of the visual pathway was best appreciated on IR images. Comparison between normal and involved cavernous sinus by adenomas was made.

Adenoma↗
PubMed1986

Purification and characterization of poly(ADP-ribose) glycohydrolase. Different modes of action on large and small poly(ADP-ribose).

Poly(ADP-ribose) glycohydrolase was purified approximately 74,000-fold to apparent homogeneity from calf thymus with a yield of 3.2%. The enzyme was a monomeric protein of Mr = 59,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The action of glycohydrolase on poly(ADP-ribose) was exoglycosidic in the direction of adenosine terminus----ribose terminus; radioactive ADP-ribose monomers were immediately produced from evenly labeled poly(ADP-ribose), but not from the polymer labeled selectively at the ribose terminus. The enzymatic degradation of large poly(ADP-ribose) (greater than 20 ADP-ribose residues) proceeded in a biphasic as well as bimodal manner. In the early and rapid phase, the enzyme degraded part of large polymers successively, leaving the remainder completely intact, and accumulated ADP-ribose monomers and small polymers of the size less than half of original polymers, indicating that the enzyme action was processive up to a certain extent. In the late and 20-fold slower phase, by contrast, the enzyme degraded the accumulated small polymers gradually and evenly, i.e. in a nonprocessive manner. The Km for large polymers was approximately 100-fold lower than that for small polymers. Similar rates and processivities were observed with large and small polymers bound to various proteins. These results suggested that the glycohydrolase may regulate differentially the levels of large and small poly(ADP-ribose) in the cell.

Animals↗