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T Yuasa

Publications and source records attributed to T Yuasa.

At least 109 records · Page 6Linked to original sources
PubMed1996

Purkinje cells express neuronal nitric oxide synthase after methylmercury administration.

To study the effects of chemical injury on the cerebellar nitric oxide synthase (NOS), we administered methylmercury chloride subcutaneously to mice, 10 mg/kg/day for 9 days. In the methylmercury-treated cerebellum. Purkinje cells were positive both for NADPH-diaphorase and for neuronal NOS. Calcium-dependent NOS activity was increased to 160% of the controls. The present study suggests the ability of Purkinje cells to produce NO through the expression of neuronal NOS.

Animals↗
PubMed1996

Vitamin K2 inhibits osteoclastic bone resorption by inducing osteoclast apoptosis.

In contrast to vitamin K1(VK1), vitamin K2(VK2) inhibited osteoclastic bone resorption by unfractionated bone cells and isolated osteoclasts. To investigate the mechanism of inhibition of osteoclastic bone resorption by VK2, we examined the effect of this vitamin on osteoclast apoptosis using a DNA-binding fluorescent dye, Hoechst 33258. In unfractionated bone cells and isolated osteoclasts on dentin slices, we first demonstrated that VK2 induced osteoclast apoptosis, but VK1 did not. Moreover, cycloheximide inhibited VK2-induced osteoclast apoptosis. These results suggest the possibility that VK2 inhibits osteoclastic bone resorption by targeting osteoclasts to undergo apoptosis, which leads to cell death.

Animals↗
PubMed1996

Surgical removal of submacular hemorrhage using tissue plasminogen activator and perfluorocarbon liquid.

PURPOSE: To assess the result of surgical removal of submacular hemorrhage by using tissue plasminogen activator and perfluorocarbon liquid. METHODS: In 22 consecutive patients (22 eyes), subretinal hemorrhage associated with age-related macular degeneration, which involved the fovea and completely obscured the choroidal vascular pattern, was treated by pars plana vitrectomy. The hemorrhages were liquefied with tissue plasminogen activator, squeezed into the vitreous cavity with perfluorocarbon liquid, and then evacuated. RESULTS: Efficacy of the procedure was judged by the best postoperative corrected visual acuity, which was 20/100 or better in 16 eyes (73%). Submacular hemorrhage recurred in four (18%) eyes, epiretinal membrane formed in three (14%) eyes, and retinal detachment occurred in three (14%) eyes. Best-corrected final visual acuity was improved postoperatively in 18 (82%) of the 22 eyes, unchanged in three (14%) eyes, and decreased in one (5%) eye, final visual acuity was 20/200 or better in 15 eyes (68%) and limited in other eyes by subretinal hemorrhage of greater than 30 days' duration or subfoveal neovascularizations. CONCLUSIONS: Use of tissue plasminogen activator and perfluorocarbon liquid in surgical removal of submacular hemorrhage may improve the outcome of surgery by reducing surgically induced retinal damage.

Aged↗
PubMed1996

Differential effects of fibronectin-derived oligopeptides on the attachment of rabbit lens epithelial cells in vitro.

Among the Arg-Gly-Asp (RGD)-containing sequences that are known to be cell-binding domains of fibronectin, 500 migrograms/ml of Arg-Gly-Asp-Ser (RGDS) and Gly-Arg-Gly-Asp-Ser showed 100% inhibition of the attachment of cultured lens epithelial cells (TOTL-86 cells), when they were added to culture medium and coincubated with the cells for 24 h whereas RGD at concentrations of 500, 1,000 and 2,000 micrograms/ml had no such activity. After 48 h of cocultivation of 800, 400 or 200 micrograms/ml of RGDS with TOTL-86 cells, the percentage of floating cells was 100, 30.1 or 11.1%, respectively. After 144 h of cocultivation with RGDS, the percentage of floating cells was 1.6, 2.4 or 1.9%, respectively, indicating that RGDS was not cytotoxic to lens epithelial cells. However, replacing the medium with fresh medium containing new RGDS peptide resulted in floating of cells. We also studied the inhibitory effect of two other amino acid sequences that are found in cell-binding sites of the fibronectin molecule: Glu-Ile-Leu-Asp-Val-Pro-Ser-Thr (EILDVPST) and Arg-Glu-Asp-Val (REDV). At 500 and 1,000 micrograms/ml, respectively, neither EILDVPST nor REDV has an inhibitory effect on the attachment of TOTL-86 cells, while RGDS at a concentration of 500 micrograms/ml completely inhibited the attachment of the cells in 24 h of incubation.

Amino Acid Sequence↗
PubMed1996

Elevation of cerebral lactate detected by localized 1H-magnetic resonance spectroscopy in migraine during the interictal period.

We used localized 1H-magnetic resonance spectroscopy (MRS) to study the metabolic changes in the brains of patients with migraine during the interictal period. Measurement of metabolite levels in the occipital visual cortex in six normal subjects and six patients disclosed high lactate levels in the five patients who had experienced a migraine attack within the previous 2 months. One patient who had not experienced a migraine attack in the previous 4 years did not show a lactate peak. We speculate that anaerobic glycolysis occurs in the brains of patients with migraine during the interictal period, and a long attack-free period may normalize the subclinical metabolic disturbance.

Adolescent↗
PubMed1996

Immortalization of cells from brains derived from a strain (MSM/MSfB6C3F1) of wild mouse.

Escape from cellular aging is the rate-limiting step of multistep carcinogenesis. While normal human cells invariably undergo cellular aging and almost never spontaneously immortalize, cells derived from rodents such as mice are relatively easily immortalized. In this experiment, we studied the immortalization patterns of cells obtained from brain tissues of an inbred strain (MSM/MSfB6C3F1) derived from wild mice. We established 12 cell strains derived from 12 mouse brains in order to investigate whether these cells show cellular aging in the same fashion as human cells or whether these cells are immortalized as easily as rodent cells reported previously. As a result, all cell strains were immortalized up to about 200 days in culture. One strain immortalized very early, in the first 50 days, four strains immortalized in the last 200 days, and the other seven strains became immortal between 150 and 200 days in culture. All immortalized cell strains showed varying amounts of chromosome abnormalities, numerically and structurally, but no specific changes related to immortalization were detected. Before immortalization, three types of cells, glial-like, polygonal flat-thin, and fibroblast-like cells, were observed in culture, but after immortalization most of the cultures became fibroblastic. From these results, we concluded that fibroblast-like cells derived from brains of these mice immortalized in like fashion to fibroblasts of other inbred mice.

Animals↗
PubMed1996

[Influence of recirculation type blood cardioplegia on perfusion pressure in open heart surgery].

Infusion blood cardioplegia often decreases the perfusion pressure during open heart surgery. The blood level of bradykinin (BK) was measured in both the cardiopulmonary bypass (CPB) and blood cardioplegia circuit. Infusion cardioplegia with recirculation type circuit increased the BK level of cardioplegia and the perfusion pressure decreased abruptly with the increase BK level in the CPB circuit. In the case of single pass type circuit the BK level was not increased either in cardioplegia or CPB and perfusion pressure was not decreased. We concluded that the single pass type of cardioplegia circuit is superior to the recirculation type because of less production of BK.

Aged↗
PubMed1996

[A case report of mitral valve papillary fibroelastoma leading to embolic stroke].

A 39-year-old man presented with acute onset of left arm and left side face weakness, and mild expressive aphasia. He was referred for two-dimensional echocardiography, which demonstrated a 13 mm diameter pedunculated, mobile, echodense mass attached to the anterior leaflet of the mitral valve. At operation, the tumor was a 10 x 10 x 15 mm, rounded, and yellow-whitish mass with a short stalk arising from rough zone of the anterior leaflet of the mitral valve. The surface appeared to be sean anemone. The mitral valve with this tumor was excised and replaced with a 29 mm St Jude Medical mechanical valve. The pathological findings are typical of a papillary fibroelastoma.

Adult↗
PubMed1996

[Immunohistochemical study of cytokeratin and vimentin expression in mixed type of adenocarcinoma and squamous cell carcinoma].

To clarify the pattern of cytokeratin and vimentin expression in mixed adenocarcinoma and squamous cell carcinoma of the uterine cervix, twenty-three cases of formalin-fixed paraffin-embedded specimen were examined immunohistochemically using a panel of four different monoclonal anti-cytokeratin antibodies and anti-vimentin antibody. Fifty-seven cases of benign or malignant tissue were selected for controls. The results were summarized as follows. 1) In four cases of co-existing adenocarcinoma and squamous cell carcinoma, their immunostaining patterns were compatible with original histological cell type. 2) In four cases of adenoacanthoma, high molecular weight-cytokeratin (HCK) was positive in each acanthomatous component and only a small part of one adenocarcinomatous component. 3) In twelve cases of cervical adenosquamous carcinoma, HCK were positive in four adenocarcinomatous components. Out of eight cases with non-stained adenocarcinomatous components, six cases showed negativity for HCK even in the squamous cell carcinomatous component. 4) Though vimentin was negative in all cases of mixed type of cervical carcinoma, some cases of mixed type endometrial carcinoma were stained positively for vimentin. It was indicated from our study that adenosquamous carcinoma of the cervix could originate either in reserve cells or columunar epithelium and that vimentin positive cases could originate in the endometorial gland.

Adenocarcinoma↗
PubMed1996

Assessment and comparison of algorithms for in vivo ESR-CT imaging of bioradicals with L-band microwaves.

In ESR-CT imaging, it is much more difficult to obtain satisfactory images than in imaging with other modalities, since two inverse problems, i.e. deconvolution of observed data and reconstruction from projections, must be solved. In this work, suitable algorithms for ESR-CT are examined using simulations and experiments. The algorithms were applied to actual data from a rat's head and a satisfactory reconstructed image was obtained from the viewpoint of morphological imaging. Several properties of the algorithms are discussed: (1) which combination of deconvolution and reconstruction method is favorable, (2) whether or not a raw differential signal should be integrated before deconvolution and reconstruction procedures, and (3) how SIRT, which offers good performance in ESR-CT, depends on an initial value and a noise type.

Algorithms↗
PubMed1995

Identification of regions on the hemagglutinin-neuraminidase protein of human parainfluenza virus type 2 important for promoting cell fusion.

The hemagglutinin-neuraminidase (HN) and fusion (F) glycoproteins of two paramyxoviruses, human parainfluenza virus type 2 (PIV2) and simian virus 41 (SV41), were expressed in HeLa cells by transfecting with recombinant plasmid harboring each glycoprotein gene. Expressed F proteins could not induce cell fusion by themselves, but evoked prominent cell fusion when coexpressed with homologous HN proteins. It was also proved that PIV2 HN protein could weakly promote SV41 F-mediated cell fusion. By analyzing the fusion-promoting function of chimeric HN proteins of PIV2 and SV41, it was revealed that the N-terminal region (about 16% of total amino acids) of either PIV2 HN or SV41 HN protein could define the type-specific fusion-promoting function for homologous F protein. Analyses of additional chimeras indicated that the N-terminal region in PIV2 HN protein (designated region I, consisting of 94 amino acids) could be reduced to a 58-amino-acid region (region I') which was located at the membrane-proximal end of the ectodomain. Furthermore, PIV2 HN protein proved to promote cell fusion mediated by PIV4A F protein. Unexpectedly, analyses of another set of chimeras revealed that the promoting function of PIV2 HN protein for PIV4A F-mediated cell fusion was not merely carried by its region I but also by another region ranging from residue 148 to 209 (region II). Finally, it was indicated that regions I' (in the presumed stalk domain) and II (in the globular head) in PIV2 HN protein might play important roles in promoting cell fusion mediated by the F proteins.

Amino Acid Sequence↗
PubMed1995

Suppression of motor cortical excitability by magnetic stimulation of the cerebellum.

EMG responses of the relaxed right thenar muscle evoked by magnetic stimulation over the sensorimotor cortex were suppressed by magnetic conditioning stimulation over the occiput. The optimal interstimulus interval for reduction of the EMG amplitude was 4-6 ms. The optimal conditioning position and induced current direction were 3-4 cm below the inion when the induced current in the center of the figure-8 coil flowed from right to left horizontally. It differed from that for activating the descending motor pathway. We consider this suppression to be due to the inhibition of motor cortex excitability caused by stimulation of the dentato-thalamo-cortical pathway at the dentate nuclei or superior cerebellar peduncle.

Adult↗
PubMed1995

A cell fusion-inhibiting monoclonal antibody binds to the presumed stalk domain of the human parainfluenza type 2 virus hemagglutinin-neuraminidase protein.

Previously, we obtained a neutralizing monoclonal antibody directed against the hemagglutinin-neuraminidase (HN) protein of human parainfluenza type 2 virus (PIV2), which was able to prevent cell fusion without affecting the hemagglutinating and neuraminidase activities. In this study, four escape mutants of PIV2 have been obtained under pressure of the monoclonal antibody. Intriguingly, the HN protein of each mutant proved to have two amino acid substitutions, one of which is at 83Asn or 91Lys, and another one is at 150Leu, 160Ala, or 186Met. One mutant designated F13, which has substitutions at 83Asn and 186Met in the HN protein, could not cause cell fusion in HeLa cells despite its multiple replication, while the other mutants formed typical syncytial cells. The deduced amino acid sequence of F13 fusion (F) protein proved to be identical to that of wild-type F protein, and furthermore, protein expression analyses have revealed that the low-fusion phenotype of F13 was due to its mutated HN protein, whose antigenicity to the monoclonal antibody was abolished by the single mutation at 83Asn. These observations have suggested that the principal epitope for the monoclonal antibody resides in the presumed stalk domain of the HN protein, which may play an important role in promoting cell fusion.

Amino Acid Sequence↗
PubMed1995

Lactate rise in the basal ganglia accompanying finger movements: a localized 1H-MRS study.

To investigate whether motor activation can cause lactate elevation, we observed the metabolic changes in seven right-handed volunteers by localized 1H-magnetic resonance spectroscopy (MRS). The volume of interest (VOI) was centered on a region including portions of the putamen and globus pallidus. Finger opposition movements were applied as the motor tasks. On the side contralateral to the finger movements, lactate rose in all subjects. No lactate rise occurred in basal ganglia ipsilateral to the movements.

Basal Ganglia↗
PubMed1995

Nitrite, nitrate and cGMP in the cerebrospinal fluid in degenerative neurologic diseases.

To investigate whether nitric oxide (NO) plays a role in degenerative neurologic disease (DND), we measured nitrite, nitrate and cyclic GMP in cerebrospinal fluid (CSF) samples from patients with Parkinson's disease (PD), spinocerebellar ataxia (SCA) and amyotrophic lateral sclerosis (ALS). We found no significant change in CSF nitrite, nitrate or cyclic GMP in patients with any DND compared with control values. These results suggest that NO production is preserved in PD, SCA and ALS.

Aged↗
PubMed1995

Effects of MCI-225 on memory and glucose utilization in basal forebrain-lesioned rats.

The effects of MCI-225 on amnesia, the cerebral glucose metabolism, and choline acetyltransferase (ChAT) activity in basal forebrain (BF)-lesioned rats were studied in comparison with those of tacrine. Bilateral BF lesions with ibotenic acid impaired the performance in passive avoidance (PA) tasks. Single administration of MCI-225 (10 mg/kg, PO) after a 2-week postoperative recovery period, increased the escape latencies in the PA task, but was not statistically significant. Repeated administration of MCI-225 (0.3 and 1 mg/kg, PO for 6 days) significantly reversed the PA failure. The BF-lesioned rat exhibited a marked decrease in the local cerebral glucose utilization (LCGU) in the frontal cortex, parietal cortex, and caudate-putamen. MCI-225 (1 mg/kg, PO for 5 days) significantly ameliorated the reduction of the LCGU in the parietal cortex. MCI-225 did not change the decrease in the cortical ChAT activity induced by the BF lesion. Repeated administration of tacrine reversed the PA failure (0.3 mg/kg, PO) but failed to prevent the decrement in the LCGU and the ChAT activity. These results suggest that MCI-225 could be effective in the treatment of senile dementia of the Alzheimer type, which is accompanied with both deficit in the BF-cortex cholinergic neuron and cerebral glucose hypometabolism.

Animals↗