Search PubMed⌕ Search

Biomedical subjects

I Nagayama

Publications and source records attributed to I Nagayama.

31 records · Page 2Linked to original sources
PubMed1989

Effect of internally loaded iodide, thiocyanate, and perchlorate on sodium-dependent iodide uptake by phospholipid vesicles reconstituted with thyroid plasma membranes: iodide counterflow mediated by the iodide transport carrier.

Na+-dependent I- transport and I- counterflow were studied using phospholipid vesicles (P-vesicles) made of porcine thyroid plasma membranes and soybean phospholipid by sonication. 1) I- uptake by P-vesicles incubated in the presence of external Na+ was higher than that by P-vesicles incubated in choline+ instead of Na+. The vesicles exhibited Na+-dependent I- uptake. When P-vesicles were internally loaded with I- prior to incubation in Na+, a further increase in Na+-dependent I- uptake was observed, although the concentration of internal I- was very much higher than that outside. In the absence of external Na+, I- uptake by P-vesicles preloaded with I- was comparable to baseline uptake. 2) Na+-dependent I- uptake by P-vesicles not loaded with I- and enhanced Na+-dependent I- uptake by P-vesicles preloaded with I- were both inhibited by either of SCN- and ClO4- added outside the vesicles. 3) When P-vesicles were loaded with SCN- instead of I- and incubated in Na+, I- uptake by these vesicles was also higher than baseline Na+-dependent I- uptake. However, a ClO4- load did not result in an increase in I- uptake. These results indicate that Na+-dependent I- transport including Na+-dependent I- counterflow is specifically mediated by the thyroid I- carrier. SCN- - I- counterflow in addition to I- - I- counterflow occurs dependently on Na+, but ClO4- - I- counterflow does not.

Animals↗
PubMed1989

Preservation of sodium-dependent iodide transport activity by methimazole and mercaptoethanol in phospholipid vesicles containing thyroid plasma membranes: with evidence of difference in the action of perchlorate and thiocyanate.

The effect of methimazole (MMI) and 2-mercaptoethanol (ME) on I-transport was studied using phospholipid vesicles (P-vesicles) made from porcine thyroid plasma membranes and soybean phospholipids by sonication. 1. When buffer solutions contained either 1 mM MMI or 2 mM ME, I-uptake by P-vesicles in the presence of external Na+ was apparently higher than that in the absence of external Na+. Na+-dependent I- uptake was inhibited by both C1O4- and SCN- added externally. 2. When PM was treated with 4 mM N-ethylmaleimide prior to preparation of P-vesicles, the activity of Na+-dependent I- transport was completely lost even when P-vesicles were incubated in the presence of ME. 3. When neither MMI nor ME was added to buffers, I- uptake in the presence of external Na+ was not at all higher than that in the absence of external Na+. In these instances, however, I- uptake was much higher compared than the baseline uptake in the presence of MMI or ME, and was inhibited by external SCN- and not by C1O4- without relation to external Na+. These data indicate that MMI or ME has two distinct effects on our model system of I- transport. The one is preservation of the Na+-dependent I- transport activity by protecting a sulfhydryl group, and the other is reduction of nonspecific I- binding to P-vesicles. In addition, C1O4- is a more specific inhibitor of thyroid I- transport than SCN-, when non-specific I- oxidation is imperfectly prevented.

Animals↗
PubMed1988

Turner's syndrome: a qualitative and quantitative analysis of EEG background activity.

A qualitative and quantitative analysis was performed on the EEG background activity in 62 Danish girls and women with Turner's syndrome (30 with karyotype 45,X and 32 with other karyotypes) whose ages ranged from 6 to 47 years (87% were aged 15 years or more) and age-matched controls. The pooled data and a case-control study showed characteristic features in Turner subjects, including: (1) more rapid frequency, larger amplitude and lower amount of alpha waves, (2) higher amount of theta waves, (3) larger amplitude and higher amount of delta waves and (4) larger amplitude and higher amount of beta waves than in controls. These findings in Turner subjects were more pronounced in the left hemisphere, and more typical, except for the amplitude in alpha waves, in Turner subjects with 45,X than in those with other karyotypes. The effects of advancing age on the EEG background activity observed in controls--including more rapid frequency, decreased amplitude and amount of alpha waves, increased amount of theta and delta waves, and increased amount of beta waves, particularly after 35 years of age--were found in some Turner subjects. Hemispheric differences with higher activity (i.e. more rapid frequency, larger amplitude and higher amount of alpha waves, particularly at Fp1 and F3, and, inversely, lower amount of theta or delta waves) at P3, T3, T5 and O2 than at the opposite side were found in many Turner subjects. However, these findings were not specific for Turner subjects, since the same hemispheric differences were also observed much more markedly in controls. These topographic distributions with hemispheric differences did not provide evidence for hypofunction in the temporo-parieto-occipital tertiary area of the right hemisphere in Turner subjects, though this had been expected on the basis of neuropsychological examinations. Our findings, including transiently appearing brain hypofunction at the parietal, temporal and occipital areas, most often in the right hemisphere, indicate a relationship between the chromosomal constitution 45,X and EEG background activity. They suggest the presence of functional brain disturbance in the thalamus and in the ascending reticular activating system, which tends to disturb the thalamo-cortical circuit. Further studies, including topographic and sequential power spectrum analysis of EEG background activity, 24-h continuous EEG recording, blood flow studies (positron computerized tomography) and neuropathological examination, may be needed.

Adolescent↗
PubMed1988

[Clinical application of microfibrillar collagen hemostat (Avitene) in neurosurgical field].

Microfibrillar collagen hemostat (Avitene) is a new absorbable hemostatic agent, of which mechanisms are adhesion to the bleeding site and platelet aggregation. Histopathological examinations revealed that Avitene was biocompatible with cerebral cortex in an animal experiments. Our previous studies indicated that Avitene is very effective and safe to use as a topical hemostatic agent during craniotomy in an experimental animal. Avitene was used as a topical hemostatic agent during craniotomy in 36 patients with intracranial organic lesions. Its effectiveness of hemostasis was revealed in 95%. This agent was especially useful to prevent oozing during craniotomy. Side effect of this agent was not reported in this study. Therefore, Avitene is very effective and safe to use as a topical hemostatic agent in the neurosurgical field.

Brain↗
PubMed1987

[Tuberculoma and tuberculous meningitis mimicking metastatic brain tumor and meningeal carcinomatosis--case report].

A 45-year-old man was well until February 1986, when he experienced gait disturbance and psychiatric symptoms. On February 11 he fell down several times and developed generalized convulsion on the following day. He was admitted to a hospital in a delirious condition. The chest X-ray film showed infiltration in the left upper lobe, but computed tomographic (CT) scan of the head revealed no abnormality. Cerebrospinal fluid obtained by lumbar puncture contained 155 cells/mm3, all of which were lymphocytes, and protein and glucose concentrations were 372 mg/dl and 68 mg/dl respectively. In spite of negative smear tests of sputum and cerebrospinal fluid for tubercle bacilli he was administered antituberculosis drugs on the suspicion of pulmonary tuberculosis and tuberculous meningitis. His level of consciousness gradually returned to normal but the follow-up CT scans showed a low density area with contrast enhancement in the right thalamus and obliteration of the right quadrigeminal cistern which was also enhanced with contrast medium. He was transferred to our hospital on March 28 for further evaluation. On admission to our hospital he was alert and oriented, his pupils were equal and reactive to light and he had mild left hemiparesis, left hyperreflexia and left hemihypesthesia. Cell count of the cerebrospinal fluid was 243/mm3, 90% of which were lymphocytes and protein and glucose contents were 340 mg/dl and 42 mg/dl respectively. Both smear and culture of the cerebrospinal fluid were negative for tubercle bacilli and other organisms. Cytological examination of the cerebrospinal fluid demonstrated clusters of cells of various sizes with high N/C ratio which suggested these cells were malignant.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Neoplasms↗
PubMed1986

[Efficacy of intracisternal papaverine on symptomatic vasospasm].

This study reports the effect of intracisternal administration of papaverine in 15 patients with vasospasm due to rupture of aneurysm. All patients had undergone clipping of aneurysm and had neurological deterioration and decreasing level of consciousness. Bolus injection of 40 mg of 1% papaverine hydrochloride was started on day 6.3 +/- 1.7 and continued for 4.4 +/- 1.6 days. In seven cases serial angiogram after initial dose revealed dilatation of IC and/or anterior, middle cerebral arteries at 30 min and further dilatation up to 85% increase in diameter at 60 min, which continued at least 90 min. Arteries with marked vasospasm responded more to papaverine than those with less vasospasm. There was a close correlation between degree of vasospasm and vasodilatation effect (r = 0.88, p less than 0.01). In all but two cases vasodilatation tended to become prominent by repeat doses, twice a day, for two to seven days (r = 0.87, p less than 0.01). Vasodilatation was observed only in IC and proximal trunks of ACA and MCA where papaverine could make direct contact, but not in the distal branches beyond A3 or M3. Neurological examination showed improvement of paresis or level of consciousness in 7 cases but no effect in 6 cases. Intracerebral hematoma occurred in two cases (one by high concentration 4% papaverine) during the treatment. Therefore intracisternal papaverine is the treatment of choice in cases with symptomatic vasospasm with some cautions on concentration to be administered.

Cerebral Angiography↗
PubMedDate not supplied

Subdural hematoma associated with dural metastasis from paranasal sinus cancer: a case report and review of the literature.

We report a 72-year-old woman who developed a subdural hematoma following dural metastasis from paranasal sinus carcinoma. Subdural hematoma with malignant neoplasm is a serious condition seen only in advanced stages. The prognosis is poor, but appropriate measures can help the patient. Head and neck surgeons should note this unusual clinical entity.

Aged↗
PubMedDate not supplied

Clinical trial of intravenous infusion of bromodeoxyuridine (BUdR) for radiosensitization of malignant brain tumors.

Bromodeoxyuridine (BUdR) is a radiosensitizer that can be incorporated into cellular DNA as a substitute for thymidine at the time of DNA synthesis. As the steady-state arterial concentration of BUdR given by means of intravenous infusion was recently presented, the possibility of revival of BUdR as a radiosensitizer administered by the intravenous route was suggested. Based on the experience of BAR therapy and phase-I studies by NIH and UCSF, 12 hours of BUdR at a dose of 800-1,000 mg/m2 for five days a week was given to 23 patients with primary and secondary malignant brain tumors during radiation therapy. Radiation therapy was planned at a weekly dose of 10 Gy for five to six weeks. Fifteen patients received 1,000 mg/m2 of BUdR; six of them tolerated more than three weeks of treatment. In eight patients given doses of 800 mg/m2, five patients tolerated more than three weeks. The most remarkable toxic effects were myelosuppression and stomatitis, which were major obstacles to maintaining the schedule. More than 50% reduction of tumor volume was obtained in five of 12 cases of evaluated gliomas (42%) and three of four cases of metastatic tumors (75%). The median time to tumor progression in seven patients with glioblastoma was 37 weeks.

Adolescent↗