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Biomedical subjects

I Uramoto

Publications and source records attributed to I Uramoto.

At least 19 recordsLinked to original sources
PubMed1995

[Postnatal development of evoked potentials in the rat somatosensory cortex].

The developmental changes of evoked potentials in the somatosensory cortex were studied using Long-Evans rats of postnatal age from day 2 to day 55. A hole of appropriate size was made in the skull under urethane anesthesia (1.4 g/kg) and somatosensory evoked potentials (SEPs) were recorded with a silver-ball electrode. Electrical stimulation was applied to whisker C 3 follicle. The electrode was moved on the dura over the hemisphere and SEPs were displayed on an oscilloscope. When a maximum SEP was obtained 100 successive responses were digitally processed with a time resolutions of 100 microseconds and averaged. From the averaged SEP, various peak latencies and amplitudes were calculated. In response to electrical stimulation of the whisker follicle, a short-latency positive wave appeared on postnatal day 2 (PND 2) and the second positive wave was recorded on PND 8 and a negative wave appeared on PND 10. The latency of these waves shortened, while the amplitude increased with age. SEPs in developing rats attained adult pattern on PND 17, although both the values of latency and amplitude reach the limit on PND 55. The placing reaction was also tested from PND 9 to PND 15 to examine the functional development of whisker. All subjects displayed positive placing reaction of chin hair on PND 10. At this age all components appeared in the SEP, 1st positive, 2nd positive and negative waves.

Aging↗
PubMed1986

Age-related changes in the content and composition of glycosaminoglycans isolated from the mouse skeletal muscle: normal and dystrophic conditions.

Glycosaminoglycans were isolated from the skeletal muscle of either normal or dystrophic mice aged from 3 to 18 weeks. The glycosaminoglycan content of the normal muscle, based on the tissue weight, decreased slightly during the period from 3 to 10 weeks, and remained almost unchanged after 10 weeks. The major glycosaminoglycan in normal muscle was hyaluronate, the relative amount of which increased slightly (from 70% to 80%) with age. Both dermatan sulfate and heparan sulfate were also obtained. The relative amounts of these sulfated glycosaminoglycans tended to decrease with age. On the other hand, the glycosaminoglycan content of the dystrophic muscle was higher than that of normal muscle even at 3 weeks. The proportion of hyaluronate was almost constant (about 65%) throughout the age range examined. The relative amount of dermatan sulfate increased from 20% to 30% with a compensatory decrease in the amount of heparan sulfate. Further, the incorporation of [35S]sulfate into glycosaminoglycans by the dystrophic muscle was reduced to about 60% of the normal. These differences in glycosaminoglycan composition and [35S]sulfate incorporation between the normal and the dystrophic muscles may be related to the progressive muscular dysfunction seen in this disease.

Aging↗
PubMed1985

Patterns of soleus muscle potentials to repetitive stimulation in young and aged rats.

Muscle potentials were recorded in the soleus muscle of Wistar rats anesthetized with urethane or Nembutal. The time course of their changes induced by repetitive stimulation of sciatic nerves at 5 Hz for 10 min was compared for young and aged rats. When stimulation commenced, muscle potentials from young rats were somewhat facilitated, followed by slight depression below control values, and thereafter they were gradually potentiated. On the contrary, muscle potentials from aged rats were rapidly reduced, attaining plateau levels 2 min or so after the onset of repetitive stimulation at 5 Hz.

Age Factors↗
PubMed1984

Differences among dystrophic, dwarf, and their crossbred mice in the time course of changes in extracellular muscle action potentials induced by 5-Hz stimulation.

With urethane anesthesia, extracellular action potentials were recorded in medial gastrocnemius muscles of dystrophic, dwarf, and their crossbred mice. When repetitive stimulation was delivered at 5 Hz for a relatively long period, characteristic features were revealed. (i) Dystrophic mice showed a slight decrease or even an increase in action potentials whereas in littermate normal mice the amplitudes were rapidly and notably reduced. (ii) In both dwarf and their littermate normal mice, a considerable reduction in amplitude was observed. Slightly more depression was produced than in nondystrophic mice of a comparable age. (iii) Crossbred mice were in two classes. A rapid and notable reduction in the amplitude of muscle action potentials was observed in one class, and slight changes in the potentials were produced in another class showing dystrophy-specific symptoms.

Action Potentials↗
PubMed1984

Ontogenetic aspects of changes in muscular potentials at medial gastrocnemius muscles of dystrophic mice due to prolonged stimulation.

Changes in muscular potentials at medial gastrocnemius (MG) muscles induced by prolonged stimulation at 5 Hz were compared in dystrophic mice and their normal littermates at various ages. A rapid and notable reduction in the amplitude of muscular potentials at MG muscles was observed in normal mice. This was in contrast with a slight decrease or even an increase in the amplitude in dystrophic mice. The magnitude of reduction in normal mice increased with age, but in dystrophic mice where the change (a decrease or even an increase) was slight, it was similar in extent regardless of age. The slight change in dystrophic mice under the present regimen would be called a fatigue, resistant-like property, and this was discussed in conjunction with analogous properties observed in electrophysiological, histological and biochemical fields.

Animals↗
PubMed1983

Contrast of time courses of changes in muscular potentials to prolonged stimulation at 5 Hz in rat medial gastrocnemius and soleus muscles.

Time courses of changes in muscular potentials to repetitive stimulation at 5 Hz for 10 min were compared between rat medial gastrocnemius (MG) and soleus (SOL) muscles. Stimuli were applied to a sciatic nerve near the entrance of the MG and lateral gastrocnemius (LG) muscles and its exit segment from the LG to the SOL muscles. Muscular potentials were generally evoked in the form of a biphasic wave at the MG muscle and were always of a simple biphasic pattern at the SOL muscle. It was found that, due to prolonged stimulation, muscular potentials were rapidly and notably reduced in the MG muscle, whereas they were gradually facilitated in the SOL muscle. This contrast was similar to differences in the time course of changes in muscular potentials under these conditions in the MG muscle of dystrophic and littermate normal mice.

Animals↗
PubMed1982

Different time courses of reduction in muscular potentials to moderate frequency stimulation in dystrophic and normal mice.

Muscular potentials were evoked by electrical stimulation of sciatic nerves and recorded from gastrocnemius muscles in dystrophic and normal mice. When frequency of stimulation was accelerated from 0.5 to 5 per sec and continued, the potentials were depressed to a notable extent in normal mice, whereas only a slight decrease or even an increase in them was observed in dystrophic mice. Thus, a simple method has been developed to differentiate pre- and/or postjunctional properties for impulse transmission in dystrophic mice from those in normal mice.

Action Potentials↗
PubMed1975

A late component of flash-evoked potentials in the cat's optic chiasma and superior colliculus: its appearance due to background illumination.

Flash-evoked potentials (FEPs) in the cat's optic chiasma and superior colliculus were recorded under the following two conditions: complete darkness and background illumination. Special attention was paid to a specific late component of FEP'S and comparison in the behavior of the late component was made between the two conditions. It was found that a late component of FEPs in the optic chiasma appeared in the presence of background illumination while it was not observed under the condition of complete darkness. A corresponding late component of FEPs was detected in the superior colliculus. The late component might be supposed to be driven from a class of W-cells in the cat's retina.

Animals↗