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Biomedical subjects

T Shibazaki

Publications and source records attributed to T Shibazaki.

At least 19 recordsLinked to original sources
PubMed1991

Pathophysiology of central (thalamic) pain: a possible role of the intralaminar nuclei in superficial pain.

In 15 patients with central pain (thalamic pain) after stroke, CT, PET scan and intraoperative thalamic microrecordings were performed. The results are considered together to evaluate a possible role of thalamic intralaminar nuclei in the genesis of central pain, especially of superficial pain. In the non-thalamic lesion group (deep pain dominant), thalamic background neural activity (BNA) was relatively high in Vim but low in CL. Conversely, in the thalamic lesion group (superficial pain dominant), thalamic BNA was higher in CL than in Vim, and markedly decreased in VC. In this group, regional cerebral oxygen consumption (rCMRO2) was relatively maintained, and regional oxygen extraction ratio (raOEF) and the relative value of regional cerebral glucose utilization (CMRGL), compared to rCMRO2, was increased in the cerebral cortex around the central sulcus. The genesis of superficial pain is discussed.

Aged↗
PubMed1991

[Evaluation of 201Tl SPECT in patients with glioma: a comparative study with histological diagnosis, clinical feature and proliferative activity].

The purpose of this study is to clarify the usefulness of 201Tl brain SPECT in the prediction of clinical degree of malignancy. Quantitative evaluation of 201Tl uptake in the tumor was expressed as count ratio of tumor site over contralateral normal region (D/C ratio) on 201Tl SPECT image. Fourteen patients with gliomas received an intravenous administration of bromodeoxyuridine (BUdR) at surgery to label tumor cells in the DNA synthesis phase. BUdR-positive cells in excised tumor specimen were stained with anti-BUdR monoclonal antibody by indirect immunoperoxidase staining. Percentage of labeled cells in relation to the total number of tumor cells in microscopic fields was defined as labeling index (BUdR-LI). D/C ratio in patients with grade IV glioma (198.7 +/- 31.7) was higher than that in patients with grade III glioma (138.3 +/- 33.9) or more low-grade gliomas (94.2 +/- 11.9, p less than 0.001). BUdR-LI in patients with high-grade glioma was also higher than that in patients with low-grade glioma. D/C ratio correlated well (r = 0.753) with BUdR-LI, which is considered to represent proliferative activity of the tumor. D/C ratio does not only correlate well with histological grade of glioma, but with clinical course or prognosis of individual patient with glioma. In conclusion, degree of 201Tl uptake in the tumor may provide non-invasive prediction of malignancy grade of gliomas and accurate estimation of efficacy of the therapy and early detection of recurrence or malignant transformation of the tumors, by delineating viable tumor tissue in patients with gliomas.

Adult↗
PubMed1990

Strategy of selective VIM thalamotomy guided by microrecording.

Our routine procedure for stereotactic selective Vim thalamotomy is described briefly. Preoperative steps identify the tremor qualitatively and quantitatively. The highlight of the procedure is the use of intraoperative microrecording to determine tremor time-locked rhythmic discharge in the presumed Vim nucleus. Results of the operation are also estimated quantitatively.

Electrocoagulation↗
PubMed1979

Comparative studies on eight dissolution method using 21 commercial chloramphenicol tablets and a nondisintegrating benzoic acid tablet.

Eight dissolution methods (beaker, rotating basket, oscillating basket, solubility simulator, rotating flask, and column) were evaluated using 21 commercial film-coated chloramphenicol (I) tablets and a nondisintegrating benzoic acid (II) tablet. The relative agitating intensities obtained from different dissolution methods were compared through the relative zero-order nondisintegrating tablet dissolution rate constants. Correlation coefficients between I dissolution rate parameters (lag time, T20, T50, and T80) were determined. Significant correlation was observed for the lag time among seven methods, and all pairwise regression lines passed through zero except one. The regression line slopes reflected the relative destructive force intensities produced by each dissolution method on the coated I tablet films. The seven dissolution methods could be classified into two main groups according to correlations of four dissolution rate parameters. The classification criterion agreed well with that based on the agitation method. However, dissolution methods may not be interchangeable even though they belong to the same dissolution method group.

Benzoates↗
PubMed1979

Dissolution systems for chloramphenicol tablet bioavailability.

The relationship between chloramphenicol (I) tablet bioavailability and in vitro dissolution rates was examined. The effect of solid food on the I tablet and powder bioavailability was also studied. Five tablets of I were selected for bioavailability testing on the basis of the dissolution rates of 18 I tablets (250 mg) determined by several methods. Compound I, 500 mg, was administered orally to five subjects, following overnight fasting, according to a crossover design. The bioavailability parameters were obtained from urinary I excretion. Among the five formulations studied, only one tablet (F) showed significantly poorer bioavailability. The dissolution rates at pH 1.2 did not give the same rank order as the bioavailability. The dissolution rate of Tablet F showed remarkable pH dependency. The dissolution rates at pH 4 showed good correlation with in vivo bioavailability data. The bioavailability of I powder was not affected by solid food. Tablet F, which had poor bioavailability in the fasting state, showed good bioavailability when administered just after the standard breakfast.

Adult↗
PubMed1978

Estimation of neural noise. Functional anatomy of the human thalamus.

In the course of stereotactic thalamotomy, the neural noise level of subcortical structures was estimated quantitatively with the aid of two semimicro-electrodes. The neural noise showed several characteristic features in terms of its amplitude and discharge pattern so that it was correlated with the possible anatomical substrate, thus providing the functional anatomy of the subcortical structures. The study on saggital plane revealed a systematic difference of the noise level between VL and Vim-Vc that could be explained by the different cell size in respective nucleus. Several exceptional cases were also presented, emphasizing the neural noise study in stereotactic surgery.

Adult↗