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T Hamano

Publications and source records attributed to T Hamano.

169 records · Page 10Linked to original sources
PubMedDate not supplied

Current source density mapping of somatosensory evoked responses following median and tibial nerve stimulation.

Potential recording of brain activities always encounters the problem resulting from the activation of reference electrodes. Current source density (CSD) computation does not take reference sites into account and consequently may better localize the generator sources. In the past, several attempts have been made to record CSDs of the somatosensory evoked responses (SERs) following median nerve stimulation. In order to compare the generating mechanisms of SERs following median nerve and tibial nerve stimulation, the scalp CSD distributions of the median nerve SER and the tibial nerve SER were compared in 5 normal subjects. In the median nerve SER, far-field potentials such as P14 and N16 were abolished in the CSD records. N20, P25 and N35 showed almost identical CSD distributions, albeit P25 had a reversed polarity. By contrast, the tibial nerve SER showed similar distributions for P40 and P60 CSDs, but N50 had a different distribution from the others. In the potential records, P40 and P60 were distributed predominantly ipsilateral to the stimulus (paradoxical lateralization), whereas the P40 and P60 CSDs formed a dipole localized over the contralateral foot somatosensory area. N50 disclosed the same tendency, although it had a slightly different CSD pattern from that of P40 and P60. These findings suggest that the median nerve and tibial nerve SER components are not necessarily comparable and that under certain circumstances CSDs are better indicators of local electrical events than the corresponding potentials.

Adult↗
PubMedDate not supplied

Unglycosylated Trk protein does not co-localize nor associate with ganglioside GM1 in stable clone of PC12 cells overexpressing Trk (PCtrk cells).

Our previous studies have shown that acidic glycosphingolipid, ganglioside GM1 (GM1), is an endogenous regulator of high affinity nerve growth factor receptor, Trk, which is an essential factor for the normal development and differentiation of neuronal cells by forming a complex with Trk. GM1 is also known to be a major constituent of caveola or glycosphingolipid-enriched microdomain (GEM) of the plasma membrane. In order to study the effect of the glycosylation of Trk on the formation of GM1-Trk complex and subcellular distribution of this protein, we generated PC12 cells stably overexpressing Trk (PCtrk). Pretreatment of this stable clones with tunicamycin, a potent inhibitor of N-glycosylation, caused the appearance of unglycosylated Trk core protein. These unglycosylated Trk can hardly respond to its ligand, NGF. Sucrose density gradient analysis revealed that unglycosylated Trk core protein was recovered in high density fractions, whereas most of GM1 is present in low density fractions corresponding to caveola or GEM fractions. Moreover, these unglycosylated Trk proteins lose their ability to form a complex with GM1, although GM1 is present in the same high density fractions. These data strongly suggest that spatial segregation of GM1 from the Trk protein by the inhibition of the glycosylation of Trk might be an important molecular mechanism for the unresponsiveness to NGF. Moreover, the binding site of GM1 in the Trk protein might act as an important determinant for the normal trafficking of the Trk protein within the cells.

Animals↗
PubMedDate not supplied

Corticobasal degeneration: an autopsy case clinically diagnosed as progressive supranuclear palsy.

We report an autopsy case diagnosed clinically as progressive supranuclear palsy (PSP), but neuropathologically confirmed as corticobasal degeneration (CBD). A 56-year-old Japanese woman slowly developed parkinsonism, dementia, character change, followed by vertical gaze palsy and dystonia. Brain MRI demonstrated diffuse cerebral atrophy with severe shrinkage of the brain stem tegmentum. The SPECT images using 123I-IMP disclosed symmetrical hypoperfusion in the frontal lobes. She died of respiratory failure at the age of 71. Gross inspection of the brain showed diffuse, symmetrical atrophy of the cerebrum and marked atrophy of the Luysian body, globus pallidus, substantia nigra and nuclei of the brain stem tegmentum. Microscopically, neuronal loss and fibrillary gliosis were observed in the Luysian body, globus pallidus, substantia nigra and nuclei of the brain stem tegmentum. The cerebellar dentate nucleus showed mild neuronal loss with some grumose degeneration. Neurofibrillary tangles were found only in the Luysian body, substantia nigra and raphe nuclei, whilst tau-positive inclusions were observed more extensively. Astrocytic plaques and swollen achromatic neurones were found in the postcentral gyrus. There were no tuft-shaped astrocytes in the brain. The clinicopathological similarities and differences between PSP and CBD are discussed.

Aged↗
PubMedDate not supplied

Tear volume in relation to contact lens wear and age.

We examined the tear volume of the inferior conjunctival sac in relation to patient age and complications of contact lens wear using a special phenol red thread test. Records of patients who had undergone this test between 1984 and 1987 were reviewed. Based on the wet length of the thread, three groups were defined: 9 mm or less, 10-14 mm, and 15 mm or more. Those patients who showed consistent results over three or more separate testings were selected for this study. A total of 11,336 eyes met this criterion. A confidence interval of 95% was established as a basis for comparison of the groups. We found that the percentage of eyes with 9 mm or less of wet length increased with the age of the subject group. Likewise, the percentage of each age group with 15 mm or more of wet length steadily decreased among progressively older groups. Eyes wearing PMMA lenses with 9 mm or less of wet length showed the highest incidence of superficial punctate keratitis (SPK) and erosion. The group of eyes wearing high-DK lenses with 15 mm or more of wet length showed the lowest incidence of SPK and erosion.

Adolescent↗