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Biomedical subjects

N Kudo

Publications and source records attributed to N Kudo.

At least 109 records · Page 6Linked to original sources
PubMed1988

Fundamental study on transcutaneous biotelemetry using diffused light.

A new method of biotelemetry is proposed, which realizes non-restrained acquisition of biological signals using infrared light diffused out from animal skin. This technique is fundamentally different from conventional telemetry techniques which use radiofrequency electromagnetic waves. An optical transmitter, which consists of some LEDs is implanted beneath the skin. Biological information such as an ECG signal is collected in vivo and the light emitted from the LEDs is modulated by the signal. The light transmitted through the skin is strongly diffused and spread out in a wide angle. The light is collected by remotely located optical receivers and biological information is obtained by demodulating the signal. Thus, the biological information in vivo is obtained without restraining the object with cables or optical fibers. In order to verify the possibility of the above techniques, a system which obtains an ECG from a laboratory animal has been developed. An infrared light was chosen because it is invisible, and has high transmittance through the skin. In addition, there are wide variety of light sources and detectors available in the range of near-infrared. Considering the stability of the communication link and the power consumption of the implanted transmitter, a PFM (pulse frequency modulation) technique was used. Using the system the transcutaneous ECG telemetry was successfully performed. In the experiment the indirect light, reflected and scattered by walls, a ceiling and a floor, was shown to be useful for optical telemetry. Light transmission patterns through the skin of a mouse were measured. The results suggest the possibility of telemetry even from the deep part of the body cavity. It is concluded that recent progress in optical and electronic technology has reached the point where transcutaneous optical telemetry of biological signals has become possible.

Animals↗
PubMed1987

Trajectory of group Ia and Ib fibers from the hind-limb muscles at the L3 and L4 segments of the spinal cord of the cat.

Nineteen physiologically identified group Ia and five group Ib fibers at the L3 and L4 levels of the spinal cord originating from various hind-limb muscles were intraaxonally injected with horseradish peroxidase (HRP). The trajectories of the stained axons were reconstructed. They extended for distances of 8.6 mm-18.0 mm rostrocaudally. Ascending axons ran in various regions of the dorsal funiculus: The ascending axon from a toe muscle (3 microns in diameter) ran in the ventral most part of the paramedian region; those from shank muscles (3.0-5.0 microns) in both dorsal and ventral paramedian regions; those from thigh muscles (5.0-7.0 microns) in both the paramedian and the more lateral regions; and those from hip muscles (6.0-7.0 microns) in the lateral region. Main collaterals arising from the parent fiber were given off at intervals of 0.5-6.2 mm (mean 2.4 mm). Collaterals of a fiber from a toe muscle (1.0 micron in diameter) entered Clarke's column from the dorsomedial side and ramified mostly in the dorsomedial one-third of the column. Collaterals of fibers from shank muscles (1.0-2.0 microns) entered Clarke's column from the dorsal side and terminated in its middle parts as well as in laminae V-VII. Collaterals of fibers from thigh muscles (1.0-2.5 microns) passed lateral to or through the lateral part of Clarke's column and terminated in its ventrolateral part and in laminae V-VIII. Collaterals of fibers from hip muscles (1.5-2.5 microns) passed lateral to Clarke's column and ramified mostly in laminae VII-IX. As the muscle of origin became more proximal, the proportion of termination outside of Clarke's column progressively increased. Thus, the trajectory of group I fibers was somatotopically organized both in the dorsal funiculus and in the gray matter. The long axis of boutons ranged from 0.5 to 17 microns in Ia fibers and from 0.5 to 8 microns in Ib fibers. "Giant" Ia boutons (above 7 microns) were found both in and outside Clarke's column.

Animals↗
PubMed1987

N-methyl-D,L-aspartate-induced locomotor activity in a spinal cord-hindlimb muscles preparation of the newborn rat studied in vitro.

Bath-applied N-methyl-D,L-aspartate (NMA) was found to elicit locomotor electromyogram (EMG) activity in ankle flexor and extensor muscles in an in vitro lumbar cord-hindlimb preparation of the newborn rat. The frequency and burst duration of the NMA-induced rhythmic EMG activity varied in a dose-dependent manner. The locomotor activity was also observed in a mid sagittally split lumbar spinal preparation, in which the frequency was much lower. It is concluded that spinal neurones with N-methyl-D-aspartate (NMDA) receptors are involved in producing locomotor activity in the rat and that each spinal half can generate hindlimb locomotion on the ipsilateral side.

Animals↗
PubMed1987

Morphological and physiological studies of development of the monosynaptic reflex pathway in the rat lumbar spinal cord.

1. The developmental process of the monosynaptic reflex pathway was investigated morphologically and electrophysiologically in isolated lumbar spinal cords of new-born and fetal rats. 2. Dorsal root fibres were stained with horseradish peroxidase in the fourth lumbar (L4) segment at different ages ranging from embryonic day (E) 15.5 to post-natal day (P) 0. At E15.5, several collaterals issued from axons in the dorsal funiculus and reached the dorsal part of the dorsal horn. At E16.5, the number of collaterals entering the grey matter increased. Also, a group of collaterals extended ventralwards forming a bundle, and reached the intermediate region. At E17.5, a small number of collaterals reached the motor nuclei. The number of collaterals entering the motor nuclei increased almost linearly with age: 0 at E15.5 and at E16.5, 27 at E17.5, 184 at E18.5, 432 at E19.5 and 746 at P0. 3. The tips of collaterals and their branches had growth cones, boutons (round or oval varicosities) or other varicosities. The mean number of branches with these structures per collateral in the motor nuclei was 1.2 at E17.5, 2.5 at E18.5, 3.6 at E19.5 and 5.8 at E20.5. 4. The percentage of collaterals having growth cones in the motor nuclei was 75% at E17.5, 70% at E18.5, 38% at E19.5 and 15% at E20.5. 5. The mean number of boutons per collateral in the motor nuclei was 0.6 at E17.5, 3.2 at E18.5, 4.9 at E19.5 and 10.7 at E20.5. This increase with age was caused by both branching of collaterals and the increase in the number of boutons of the en passant type. The estimated total number of boutons in the motor nuclei of the L4 segment steeply increased after E17.5: 16 at E17.5, ca. 600 at E18.5, ca. 2000 at E19.5 and ca. 8000 at E20.5-P0. 6. Stimulation of the L4 dorsal root evoked a reflex response in the L4 ventral root, recorded as the ventral root potential, in two out of nine preparations at E15.5 and in all preparations at and after E16.5. The onset of the ventral root potential indicated the onset of excitatory post-synaptic potentials in motoneurones. The segmental latency of the ventral root potentials was markedly shortened between E17.5 and E18.5 (from 12.5 to 7.2 ms) and essentially unchanged at the later stages. 7. The magnitude of monosynaptic reflex responses in the L4 segment gradually increased with age during prenatal stages, becoming maximal at P2-3 and then decreased at the following stages (P4-P8).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Protection against cadmium toxicity by zinc: decrease in the Cd-high molecular weight protein fraction in rat liver and kidney on Zn pretreatment.

The amounts of cadmium, associated with high molecular weight proteins, metallothionein and low molecular weight fractions obtained on Sephadex G-75 gel filtration, were determined in the liver and kidneys of rats treated with Cd. When rats were pretreated with zinc 24 h prior to the Cd injection, Cd associated with the high molecular weight proteins was decreased in both the liver and kidneys. Although the Cd concentration in the liver was increased, the liver showed less morphological damage in Zn-pretreated rats. The above results suggest that Cd-toxicity toward the liver and kidneys may be related to the accumulation of Cd in the high molecular weight proteins.

Alkaline Phosphatase↗