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T Otsuka

Publications and source records attributed to T Otsuka.

At least 469 records · Page 26Linked to original sources
PubMed1975

Morphological and functional identifications of catfish retinal neurons. II. Morphological identification.

In this study the morphological origins of the responses from the catfish retinal neurons evoked by step inputs were determined by injecting intracellularly a dye, Procion yellow. A method was devised to view the dye-injected neurons in flat mount to study their dendritic expansion; later the same neurons could be sectioned radially to locate the levels of their somata or dendritic expansion. The results of this study show the inherent danger of identifying dye-injected neurons only in a radial or tangential view. Bipolar cells could be identified functionally without any ambiguity by changing widely the stimulus parameters, because the stimulation of their receptive-field center and surround gave rise to responses of opposing polarity. We found no exception to this rule. The neurons in the proximal layers produced a large variety of responses which could not be segregated into two such classes as the amacrine and ganglion cells. In this part II they were classified into three broad categories: neurons giving rise to sustained, transient, and spiking responses. The demarcation among the three types, morphologywise and functionwise, was vague and not well established. The sustained responses were recoreded from the starburst and spaghetti neurons (part I (9)) which correspond to Ramón y Cajal's (2) amacrine cells. The transient responses, whose patterns were largely invariant of the changes in the stimulus parameters, were recorded from a class of neurons with spindle-shaped somata in the INL. We do not know whether they had axons or not, but we will not be surprised if a future study defines them as a class of ganglion cells. Responses with or without spike discharges were recorded from a class of neurons which were identified as ganglion cells. Observations made on a large number of Procion-injected neurons in both flat-mount preparations and radial sections show that finer dendritic arborizations were not seen in the dye-injected neurons although the presence of such branches was proved in the Golgi preparations. Probably this was due to the weak contrast of the Procion-injected cell against the tissue background, rather than the failure of the dye to diffuse into finer branches. We recognize the severe difficulty involved in the traditional approach of identifying a class of neurons based on typical but subjectively selected functional and structural samples. Neurons have to be classified statistically according to their (quantitative) parameters. (cont'd)

Animals↗
PubMed1975

Development of a live attenuated varicella vaccine.

The Oka strain of varicella virus, isolated in our labolatory, was serially cultivated in guinea-pig embryo cultures (GPEC), and a considerable amount of cell-free virus was obtained from infected cell. GPEC passage virus at the 6th passage level was used in a small scale field trial. Susceptible children of 1 to 10 years old were injected subcutaneously with 100 to 1,000 PFU of virus. No clinical reactions due to the vaccination were observed in any children, and a high rate of antibody response was obtained with viral doses of more than 200 PFU. Attenuated virus obtained by passage in GPEC was propagated in human diploid (WI-38) cells, and it was also effective in inducing an immune response without clinical reactions. The results show that the Oka strain of varicella virus passaged in GPEC and human diploid (WI-38) cells may be used safely and effectively as a live attenuated vaccine.

Animals↗
PubMed1972

Effects of chemicals on receptors and horizontal cells in the retina.

1. By applying atomized chemical solutions on to gecko and carp retinae, neuropharmacological reactions of the photoreceptors and horizontal cells were observed.2. Sodium L-glutamate and L-aspartate, glycine, ACh and GABA, had no appreciable effect on the photoreceptor activity.3. Carp horizontal cells were depolarized by both L-glutamate and L-aspartate. When maximally depolarized, the action of the endogenous transmitter from the receptor terminals was completely masked, resulting in abolition of the S-potentials.4. Responses to red light in both L- and C-type horizontal cells were more strongly affected by aspartate than responses to blue light.5. Glycine and GABA hyperpolarized the horizontal cells, and the S-potentials were diminished.6. ACh had no effect on the activity of the horizontal cells.

Acetylcholine↗