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Biomedical subjects

S Hashimoto

Publications and source records attributed to S Hashimoto.

At least 1,351 records · Page 75Linked to original sources
PubMed1981

Distribution of slow cortical potentials preceding self-paced hand and hindlimb movements in the premotor and motor areas of monkeys.

Surface negative-depth positive, slowly increasing potentials prior to self-paced hand and hindlimb movements were recorded in the dorsal aspect of the motor and premotor cortices with chronically implanted electrodes. It was shown that the potentials were recorded in the contralateral forelimb motor area prior to hand movements but were hardly seen in the hindlimb motor area. On hindlimb movements, the contralateral hindlimb motor area showed the premovement potentials, whereas the forelimb motor area revealed little or no premovement potentials. The contralateral premotor cortex was shown to induce the premovement potentials in its wider areas and participate in both of hand and hindlimb movements in a similar fashion, with predominances in its dorsolateral portion for hand movements and in its dorsomedial portion for hindlimb movements respectively. In the hemisphere ipsilateral to the moving hand, the relatively large premovement slow potentials emerged frequently also in the premotor cortex, whereas only the small potential was obtained from the forelimb motor area. These results suggest that the premotor cortex (area 6) participates in the more general and associative organization of motor function than the motor cortex (area 4) which represents the specialized role in the motor performance.

Action Potentials↗
PubMed1981

Nucleotide sequences and mapping of novel heterogenous 5'-termini of adenovirus 2 early region 4 mRNA.

The major 5'-termini of human adenovirus type 2 early gene block 4 mRNA were sequenced. Poly(A+) polyribosomal RNA was isolated from Ad2 early infected cells, the 5'-terminal m7GPPP removed and the 5'-OH of the penultimate 2'-0-methylated nucleotide labeled with [gamma-32P]ATP using polynucleotide kinase. Ad2 E4 mRNA was purified by hybridization to the Ad2 EcoRI-C fragment and was digested with RNase T1. The resulting oligonucleotides were resolved by two dimensional paper electrophoresis-homochromatography. Four major and 3-4 minor 5'-terminal sequences were identified and characterized. The sequence of the 5'-terminal structures of the major four termini are: (1) m7GpppUmU(m)UUACACUGp, (2) m7GpppUmU(m)UACACUGp, (3) m7GpppUmU(m)ACACUGp, and (4) m7Gppp(m6)AmC(m)ACUGp. These major 5'-terminal sequences were aligned with nucleotide 325, 326, 327, and 329 from the righthand end of the known Ad2 DNA sequence (1) in the region mapped as the 5'-terminus of E4 mRNA by electron microscopy (2,3) and S1 nuclease-gel (4) mapping. Two potential ribosomal binding sites and an initiator codon were found at 40 to 65 nucleotides and about 80 nucleotides, respectively, from these heterogenous 5'-termini. Ad2 E4 major mRNA species appear to be unique since mRNA molecules initiate at a pyrimidine, perhaps by RNA polymerase stuttering, or they are products of an unusual type of RNA processing.

Adenoviruses, Human↗
PubMed1981

Influences of cerebellar hemispherectomy upon cortical potentials preceding visually initiated hand movements in the monkey.

With chronically implanted electrodes, surface and depth potentials of the premotor and motor cortices were recorded on hand movements in response to a visual stimulus in monkeys, and influences of cerebellar hemispherectomy were examined upon visually initiated premovement cortical potentials. Early, surface positive--depth negative premovement potentials emerged in the cortices on both sides, and following surface negative--depth positive premovement potentials appeared in the motor cortex contralateral to the moving hand. Cerebellar hemispherectomy contralateral to the motor cortex eliminated the following potentials. This suggests the participation of the neocerebellum in preparing the motor cortex for visually initiated movements.

Animals↗
PubMed1981

Cortical field potentials preceding visually initiated hand movements in the monkey.

With electrodes implanted chronically on the surface and in the depth of the cortex, field potentials were led from the premotor cortex and forelimb areas of the motor and somatosensory cortices of monkeys performing visually initiated hand movements, and then averaged. It was found that the visually initiated movement was preceded by early (latency about 40 ms after the visual stimulus), surface positive, depth negative potentials in the premotor and forelimb motor cortices on both sides. Later on (at about 120 ms latency), surface negative, depth positive potentials emerged prior to the movement in the motor cortex contralateral to the moving hand. The early responses were interpreted as being induced via deep thalamo-cortical and/or corticocortical projections, while the later responses were via superficial thalamo-cortical projections, according to laminar field potential analyses of cortical evoked potentials made in our previous acute experiments. These potentials recorded in the respective cortices prior to self-paced hand movements: monkeys performing self-paced hand movements showed slowly increasing, surface negative, depth positive premovement potentials in the premotor cortex and the forelimb motor and somatosensory areas contralateral to the moving hand. It was concluded that the central nervous mechanism preparing the cerebral cortex for visually initiated movements is considerably different from that for self-paced movements, both of which consist of the same wrist extension in lifting a lever.

Animals↗
PubMed1981

ABR audiometry in the diagnosis of cerebellopontine angle tumors.

Auditory brain-stem responses (ABR) examination with simultaneous lobe-vertex (L-V) and membrane-vertex cm-v) recording was performed in 34 ears with cerebellopontine angle tumors. The detectability of wave I was better in M-V recording than in L-V recording, whereas L-V recording exhibited better detectability of wave V. ABR waveforms were classified into three groups, and the relations between the waveforms and the size of tumor or the degree of hearing loss were analyzed. Positive finding in ABR were obtained in 25 out of 34 ears in the present study. It was stressed that this dual recording in ABR was extremely useful in the diagnosis of cerebellopontine angle tumors.

Adolescent↗
PubMed1981

Mortality and survival for Down syndrome in Japan.

Mortality and survival data for 1,052 Japanese patients with Down syndrome who were born between 1966 and 1975 were analyzed. The survival rate at age 10 was estimated to be about 86%. Mortality in each age group for Down syndrome was elevated over that of the general population. In the survival rate at age 10, there was no significant difference between males and females, but the difference between cases with and without congenital heart disease was highly significant. Using data from this study-for mortality up to age 10-and from the study of institutionalized cases for mortality over age 10, a hypothetical life table was constructed; it shows that the life expectancy at birth for cases with Down syndrome is nearly 50 years.

Adolescent↗
PubMed1981

Dimer formation in radiation-irradiated aqueous solution of lysozyme studied by light-scattering-intensity measurement.

The reaction of lysozyme with OH., Br.-2 and e-aq, produced in an aqueous solution by pulsed electrons and gamma-rays, were investigated. Irradiated enzymes showed an increase in the light scattering intensity (LSI) which is proportional to the absorbed dose. Results obtained from SDS gel electrophoresis confirm dimerization of lysozyme, which is considered to be responsible for the increase in LSI. It was found that the rate constant of the dimerization of protein radicals produced in the reaction with OH. is 2K=(1.0 +/- 0.3) X 10(6)M-1 s-1 and the yield of the dimerization is 0.6 in G. The enzymatic activity of the dimer is shown to be reduced to about 30 per cent of that of the intact enzyme. It is concluded that the radiation-induced inactivation of lysozyme is largely due to dimerization.

Electrons↗