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T Nishimura

Publications and source records attributed to T Nishimura.

At least 91 records · Page 5Linked to original sources
PubMed1991

Assembly, disassembly, and exchange of glial fibrillary acidic protein.

The kinetics and dynamics of glial fibrillary acidic protein (GFAP) assembly was explored by a fluorescence energy transfer assay method. Purified GFAP was stoichiometrically labeled at a single cysteine residue with fluorescein-maleimide. Soluble labeled GFAP in a low ionic strength buffer was assembled into 10 nm filaments by rapidly increasing the ionic strength, and the kinetics of GFAP assembly was monitored by the reduction in fluorescence due to self-quenching of fluorescein. The extent of fluorescence quench correlated with both the formation of 10 nm filament morphology and the amount of protein pelleted at 12,000g. The assembly of GFAP is critically dependent upon both protein and magnesium ion concentration, and at the critical concentration for GFAP assembly is approximately 40 micrograms/ml. Disassembly of GFAP filaments was also observed as a relief of fluorescence quenching after dilution of labeled GFAP filaments. When labeled GFAP filaments were mixed with an excess of unlabeled filaments, a rapid increase of fluorescence was observed, which is due to an exchange of subunits between labeled and unlabeled GFAP filaments. These results indicate that GFAP filaments are dynamic structures and that a small pool of kinetically active unassembled GFAP subunits are in a dynamic equilibrium with assembled GFAP filaments. The ability of GFAP to assemble, disassemble, and undergo subunit exchange has important implications for the organization and dynamics of astroglia cell cytoskeleton during development and in response to injury.

Animals↗
PubMed1991

Immunohistochemical study of microtubule-associated protein 2 and ubiquitin in chronically aluminum-intoxicated rabbit brain.

Experimental neurofibrillary change was produced in rabbit brain by daily subcutaneous aluminum tartrate injection for 40 days. The production of experimental neurofibrillary changes was confirmed by immunostaining with antibodies against neurofilament triplet proteins and the brain tissue was studied immunohistochemically with antibodies against microtubule-associated protein (MAP) 2 and ubiquitin. The hippocampal neurons of the chronically aluminum-intoxicated rabbit brain showed diminished staining of dendrites by anti-MAP2 antibody. The length of anti-MAP2-positive dendrites in hippocampus was significantly shorter than that of the control brain. In the cortex somata of a subset of pyramidal neurons were intensively stained by anti-MAP2 antibody, while the MAP2 immunoreactivity of distal dendrites was diminished. The immunostaining by anti-ubiquitin antibody revealed the positive staining of the neurons bearing experimental neurofibrillary changes in the lower brain stem nuclei. It is speculated that MAP2 dislocation and ubiquitination are accompanying phenomena of the production of experimental neurofibrillary changes in chronically aluminum-intoxicated rabbit brains.

Aluminum↗
PubMed1991

Brain stem auditory-evoked potentials in meningomyelocele. Natural history of Chiari II malformations.

Brain stem auditory-evoked potentials (BAEPs) were recorded in 30 patients with meningomyelocele and shunted hydrocephalus ranging in age from birth to 33 years. Twenty-two of them had Chiari II malformation, one of which was symptomatic. In 22 cases, including 15 with Chiari II malformation, BAEPs were recorded repeatedly after periods ranging from 18 months to 7 years. The results were as follows: (1) III-V interpeak latency (IPL) decreased progressively from prolonged to the normal range with growth until 25 years of age; (2) I-III IPL tended to prolong gradually from the normal range; (3) these findings may indicate that the natural history of Chiari II malformation is delayed maturation of the brain stem and intensification in the elongation and stretching of the hindbrain and lower cranial nerves.

Adolescent↗
PubMed1991

Change of accumulation and filling pattern in evolution of cerebral infarction with I-123 IMP brain SPECT.

Twenty-eight patients with cerebral infarction were examined by brain SPECT with I-123 IMP a total of 46 times from Day 2 to Day 84 after the onset of stroke. Depending on the pattern of change in the abnormal accumulation of I-123 IMP between the early and delayed images, the patients were classified into one of five types. The number of patients in each type and the number of days after infarction at which each type occurred were as follows: Type (I), n = 5 and 4 +/- 2 days; Type (II), n = 8 and 12 +/- 4 days; Type (III), n = 17 and 21 +/- 11 days; Type (IV), n = 13 and 38 +/- 18 days; and Type (V), n = 3 and 60 +/- 16 days. In 12 patients, 30 brain SPECT were performed that showed the chronological evolution of infarction in sequence from Types (I) to (IV). Hyperactivity in the early image was seen in Type (I) with a subsequent image defect, while in Type (II) there was persistent hyperactivity. Hypoactivity in the early image was seen in Types (III), (IV), and (V), and the activity in the delayed image gradually decreased as the process of infarction terminated. The early image reflected the distribution of lipophilic I-123 IMP, indicating regional cerebral blood flow, while the delayed image showed the distribution of hydrophilic I-123 IMP metabolites superimposed on that of lipophilic I-123 IMP which had accumulated in the brain at the first extraction. Combining the early and delayed images of I-123 IMP brain SPECT may help to understand the evolution of cerebral infarction.

Adult↗
PubMed1991

Dietary restriction reduces the incidence of 3-methylcholanthrene-induced tumors in mice: close correlation with its potentiating effect on host T cell functions.

All mice treated with 3-methylcholanthrene (MC) suffered with tumor 114 days after treatment. However, 40% dietary restriction caused a great inhibition of tumor incidence. In order to understand the mechanisms by which dietary restriction decreased the occurrence of tumor in mice, we investigated the correlation between tumor incidence and host T cell immune responses. At 114 days after MC administration, the mice were sacrificed and their T cell immune responses were assessed. Flow cytometry studies demonstrated that dietary restriction caused a marked increase of the proportion of Thy 1.2+, L3T4+ T cells in MC-treated diet-restricted mice. Consistent with this result, T cell responses against concanavalin A and interleukin-2 were also potentiated in spleen cells obtained from MC-treated diet-restricted mice, while spleen cells obtained from MC-treated unrestricted mice showed decreased T cell responses because of their tumor burden. Such potentiation of T cell functions by dietary restriction was also observed at earlier stages of MC-induced tumorigenesis. During the course of carcinogenesis, spleen cells obtained from diet-restricted mice showed decreased natural killer activity in vivo. However, in vitro induction of cytotoxic T cells was markedly augmented in MC-treated diet-restricted mice compared with unrestricted mice. These results strongly suggest that the increase of host T cell immune responses might be one of the major causes for the reduction of tumor occurrence by dietary restriction.

Animals↗
PubMed1991

Continuous determination of cardiac output using a flow-directed Doppler pulmonary artery catheter.

A newly developed, flow-directed, Doppler pulmonary artery catheter that uses multiple ultrasonic transducers to measure instantaneous and continuous cardiac output was evaluated in 20 patients undergoing cardiac and vascular surgical procedures. Cardiac output was determined using the product of the average velocity and the area of the main pulmonary artery. Pulmonary artery area was obtained from measurements of diameter via ultrasound transit time, and average velocity of blood flow was determined from the Doppler shift frequency. Two hundred thirty-eight simultaneous Doppler catheter and thermodilution cardiac output measurements were obtained preoperatively, intraoperatively, and during postoperative recovery. Catheter indwelling time varied from 18 through 94 hours (mean +/- SD, 40 +/- 19 hours) with 2 to 26 (mean +/- SD, 12 +/- 6) sets of triplicate cardiac output measurements obtained per patient. Doppler catheter cardiac output correlated well with thermodilution (r = 0.76, slope or m = 0.87, and SEE = 0.05 with P = 0.0001) and mean predictive error (bias) appeared clinically insignificant (bias +/- SD, -0.13 +/- 0.79 L/min). Accurate, continuous monitoring of instantaneous and mean cardiac output appears possible with use of this Doppler pulmonary artery catheter system.

Blood Flow Velocity↗
PubMed1991

Clinical application of video image flexible ureteronephroscope for diagnosis of upper urinary tract disorders.

Ureteroscopy has become the diagnostic and therapeutic procedure of choice for many conditions of the upper urinary tract. Technology is progressing rapidly in endourology, facilitating both goals. As reported previously, we developed a 2F video image flexible ureteronephroscope. This instrument is the smallest caliber of all ureteronephroscopes available to date. Because of the small diameter the device can be inserted into the ureter cystoscopically in a manner similar to catheter insertion. The procedure is done with the patient under local anesthesia. We performed ureteronephroscopic procedures on 79 patients using mainly a 6F passively deflecting flexible ureteronephroscope, which consists of the aforementioned 2F video image flexible ureteronephroscope and a 3F working channel. The area to be viewed was accessed successfully in 41 of 43 patients (95%). Over-all, diagnostic maneuvers were successful in 64 of 79 patients (87%). We suggest that the 2F and 6F flexible ureteronephroscopes would be indicated when conclusive diagnosis for upper urinary disease is not obtained by other means.

Endoscopes↗
PubMed1991

Radiation-induced cranial nerve palsy: hypoglossal nerve and vocal cord palsies.

Cranial nerve palsies are an unexpected complication of radiotherapy for head and neck tumours. We present a case of this radiation-induced cranial palsy. An 18-year-old female with nasopharyngeal carcinoma developed a right hypoglossal nerve palsy 42 months after cancericidal doses of radiotherapy. In addition, she developed a bilateral vocal cord palsy 62 months after therapy. Follow-up over four years has demonstrated no evidence of tumour recurrence and no sign of neurological improvement.

Adolescent↗
PubMed1991

Venous haemangioma of the neck and mediastinum.

A case of cervico-mediastinal venous haemangioma with diffuse upper respiratory airway involvement is reported. The lesion was considered to be an ordinary supraglottic haemangioma at first. We recommend that adult cases of laryngeal haemangioma should be carefully examined for extra-laryngeal lesions.

Bronchoscopy↗
PubMed1991

Chondrosarcoma of the parapharyngeal space.

Chondrosarcoma is rarely found arising in the head and neck region. An unusual case arising in the parapharyngeal space in a male is reported and the differential diagnosis, pathology and treatment are discussed.

Adult↗
PubMed1991

Differential diagnosis of pleomorphic adenoma by immunohistochemical means.

Immunohistochemical study of major salivary gland tumours was performed on 60 pleomorphic adenomas, five basal cell adenomas and 10 adenoid cystic carcinomas to determine the diagnostic value of each antigen. Immunoreactivity examined were intermediate filaments (keratin, vimentin, desmin and glial fibrillary acidic protein [GFAP]) and related substances (actin, S-100 protein and secretory component). In pleomorphic adenomas, there was positive immunoreactivity for GFAP which was not observed in normal tissue or other neoplastic tissues. Immunoreactivity of GFAP was closely related to myxomatous and early chondromatous differentiation in pleomorphic adenoma. It is considered that GFAP immunoreactivity should be assessed in the occasional differential diagnostic dilemma of pleomorphic adenoma versus adenoid cystic carcinoma and basal cell adenoma, because of its ability to show potential and definite myxochondromatous differentiation.

Adenoma↗
PubMed1991

Embolic stroke following carotid radiation angiopathy demonstrated with I-123 IMP brain SPECT.

Radiation angiopathy was developed by the process of accelerated atherosclerosis at the site of irradiation. The case of a 44-year-old man with right hemiparesis showing a high signal intensity in the left semioval center on MRI and a defect in the left temporo-parietal area with subsequent filling-in with I-123 IMP brain SPECT is reported. Digital subtraction angiography showed typical radiation angiopathy with ulceration in the left common carotid artery. Twenty-four years previously, he underwent curative irradiation of a neck mass that revealed Hodgkin's disease by biopsy. The emboli formed at the site of radiation-induced angiopathy and caused cerebral infarction. The perfusion abnormality in the territory of the embolic artery was detected by I-123 IMP SPECT. Long-term survivors of neck irradiation are at high risk for the development of carotid arterial disease and should be watched carefully.

Adult↗
PubMed1991

Validation to eliminate vascular activity on 99Tcm-HMPAO brain SPECT for regional cerebral blood flow (rCBF) determination.

Since more than 15% of the injected dose of 99Tcm-HMPAO 10 min after injection labels plasma or red blood cells (RBC), the elimination of vascular activity from actual brain activity is mandatory to evaluate accurately regional cerebral blood flow (rCBF) with 99Tcm-HMPAO brain SPECT. The late image (4 h post-injection) will show a reduced vascular activity of approximately 30% compared to the initial image (30 min post-injection), due principally to a plasma fraction reduction of 54%, and an insignificant reduction of activity in the RBC fraction. The circulating RBC count can then be normalized for both the injected dose and total blood volume, because the entrapment mechanism of 99Tcm-HMPAO with RBC is the same as that with brain retention. After elimination of the vascular contribution using the RBC activity the mean counts in the 14 middle cerebral artery areas from seven cases on 99Tcm-HMPAO SPECT showed a good correlation (r = 0.85) with the initial slope index of 133Xe cerebrography. It was concluded that the elimination of the vascular activity on 99Tcm-HMPAO brain SPECT is needed to quantify rCBF accurately.

Adult↗