Biomedical subjects
Publications and source records attributed to T Ohmoto.
A case of bilateral intracerebellar calcificaiton associated with cerebellar hematoma on the left side is reported. Clinical and microscopic examination failed to clarify the causes of calcification and hematoma. It is postulated that hemorrhage occurred from time to time through the fragile calcified vessel walls, since some portions of the organized hematoma were composed of massive erythrocytes.
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Eighteen patients with parkinsonism were treated with a combination of L-dopa and peripheral decarboxylase inhibitor, L-alphahydrazinomethyldopa (MK-486). Modification of L-dopa effect by MK-486 was also studied in parkinsonian patients as well as in cats. (1) Concentrations of dopa and dopamine in plasma and brain were measured in cats following intraperitoneal injection of L-dopa alone (100 mg/kg) or combined with MK-486 (10 mg/kg). Dopa levels in plasma and brain in the combination with MK-486 were three times as high as in L-dopa alone. Dopamine levels in caudate nucleus and putamen were increased nearly fourfold with the combination. (2) Plasma dopa and dopamine levels were measured in parkinsonian patients. Clinical pharmacological studies disclosed that a 1 : 10 ratio of MK-486 to L-dopa in dosage was preferable. (3) Maximum plasma dopa levels with the combination were four times those following L-dopa alone. Plasma dopa sustained a high level over a period of five hours. MK-486 markedly reduced plasma levels of dopamine. (4) There was no significant difference in dopa and dopamine levels in cerebrospinal fluid between L-dopa alone and a combination of MK-486, but dopamine levels in the CSF were still high at four hours after the combination of MK-486. (5) In clinical studies of eighteen patients with parkinsonism, the effectiveness of the combination therapy (mean dosage of L-dopa: 750 mg/day) was observed in all cases. Marked improvement was noted in 10 cases out of 15 (67%) with akinesia, in 12 cases out of 17 (71%) with rigidity and in six cases out of 14 (43%) with tremor. Maximum plasma dopa levels were higher in those cases with marked improvement, and were highest in patients with diskinesias as a side effect. (6) An addition of vitamin B6 did not show adverse effects. (7) Transient nausea and vomiting as a side effect, less severe than those experienced with L-dopa alone, were noted in five cases (28%). Dyskinesias in extremities, face, mouth and tongue were observed in six cases (33%). These dyskinesias were seen in a high percentage of cases with marked improvement and were never observed in the extremities contralateral to the side of thalamotomy.
Either L-dopa, in combination with 1-alpha-methyldopa hydrazine (MK-486), or 1-(2''-pyrimidyl)-4-piperonylpiperazine, an agent that stimulates dopamine receptors, relieves surgically induced tremor in monkeys and concomitantly evokes involuntary movements. These results indicate that tremor and involuntary movements are associated with a common mechanism and that the activity of the dopamine receptors is involved in the regulation of these dysfunctions.
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Magnetic resonance (MR) characteristics of metastatic brain tumors (MBTs) were studied using 15 cases (13 males and 2 females whose ages ranged from 32-78 yr, with the mean age of 57.8 yr; 12 adenocarcinomas, 2 squamous-cell carcinomas, 2 large-cell carcinomas). Nine cases showed hypointensities and five showed isointensities on T1-weighted images. Six cases showed markedly hypo- or hypointensities, two showed isointensities, and six showed markedly hyper- or hyperintensities on T2-weighted images. One case was markedly hyperintense on both T1- and T2-weighted images. The decrease of the signal intensity on the T2-weighted image was the main MR characteristic. A hypointense peritumoral rim was seen in four of the six hyperintense tumors on T2-weighted images. There was no correlation between the signal intensity and the histological classification.
Two cases of acute carbon monoxide poisoning are presented in this paper. Sequential magnetic resonance (MR) images of the brain showed abnormal lesions in the bilateral globus pallidus and/or in the subcortical white matter. The MR images disclosed that the severity of the white matter lesions correlated with the prognosis in acute carbon monoxide poisoning. However, they did not always correspond to the neurological condition in the acute and subacute stages.
We report the magnetic resonance features of meningiomas at the falcotentorial junction in six patients. Three tumors showed several characteristics on magnetic resonance images. They demonstrated hypo- or isointensity on T1-weighted images and iso- or hyperintensity on T2-weighted images. The degree of contrast between tumor and brain parenchyma, however, was less marked. The tumors often had a mottled appearance on T2-weighted images owing to their hypervascularity. All of the tumors had a peritumoral rim, and no edema was seen in adjacent brain parenchyma. With the injection of gadolinium, the tumors in all patients markedly enhanced; the adjacent dura was enhanced in four patients.
We evaluated the magnetic resonance images of the patients with intention tremor. Five patients out of seven had some atrophic structures or changes in signal intensity in the cerebello-rubral thalamic tract. Moreover, the T2-weighted images of the patients group detected the dentate and red nuclei more poorly than those of our control group. From these results, the etiological significance of the tract was confirmed and the mechanism of the intention tremor onset was discussed.