Search PubMed⌕ Search

Biomedical subjects

S Homma

Publications and source records attributed to S Homma.

At least 343 records · Page 19Linked to original sources
PubMed1983

Saltatory conduction revealed by unidimensional latency-topography of peripheral nerve impulse.

The ventral or dorsal root of the rat was placed on 12 electrodes arranged side by side at 0.4 mm intervals. Impulse conduction along the fiber was displayed using unidimensional latency-topography, which corresponds to the relation between latency and electrode distance. The relation revealed step-like displacement, which implies saltatory conduction of the impulse. Since the distance between the plateaux correspond to internodal length, the conduction velocity could be calculated from the length and the time differences between plateaux. It was found from 36 observations that : (i) mean internodal length was 0.92 +/- 0.13 mm (range 0.70--1.25 mm); (ii) mean conduction velocity was 76.1 +/- 20.7 m/s; and (iii) the correlation coefficient of conduction velocity and internodal length was statistically significant at r = 0.38 (P less than 0.025), so the longer the internodal length, the higher the conduction velocity.

Action Potentials↗
PubMed1983

Effects of electrical constants on conduction velocity of action potentials measured with unidimensional latency-topography in frog skeletal muscle fibers.

Conduction velocity (CV) of an action potential recorded from a single muscle fiber of the frog was measured with a new method, unidimensional latency-topography, and electrical membrane constants were determined for the same muscle fiber. CV = 1.96 +/- 0.27 m/sec (n = 52) at about 20 degrees C. Temperature coefficient of CV: Q10 = 2.0. Electrical membrane constants in the same muscle fibers (n = 52): lambda = 3.25 +/- 0.83 mm, tau = 33.4 +/- 14.3 msec, Cm = 6.09 +/- 2.13 mu F/cm2, D = 129.4 +/- 28.9 micron (mean +/- S.D.). The CV decreased linearly with increment of time constant, tau, and membrane capacity per unit area, Cm. The space constant, lambda, and the fiber diameter of the muscle fiber, D, did not correlate with CV. It was concluded that the T-system, which contributes largely to membrane capacity, has a great influence on the CV.

Action Potentials↗
PubMed1983

Lipid composition of winged bean (Psophocarpus tetragonolobus).

The lipids were extracted from the winged bean (Psophocarpus tetragonolobus) seed with water-saturated n-butanol. Lipids were separated into groups by preparative TLC on silica gel G. The amount of each lipid type was determined by analysis of the fatty acid constituents in each lipid type. Glyceride was the major lipid accounting for 89.6% of the total, followed by an unknown lipid 4%, free fatty acid of 2.3%, 1,3-diglyceride, 1,2-diglyceride and steryl ester as 1% each and finally a polar lipid as 0.2%. The results show that winged bean oil should be suitable for edible purposes. Triglycerides showed a similar profile of fatty acids to those of whole lipid: the major fatty acids were palmitic (10.9%), stearic (4.5%), oleic (37.1%), linoleic (19.0%), eicosenoic (3.6%), behenic (18.5%) and lignoceric (4.2%) acids. Compared to soybean oil, winged bean oil contained long chain fatty acids and a fairly small amount of linolenic acid which is favorable regarding oil stability against autoxidation.

Chemical Phenomena↗
PubMed1982

Estimation of generator potentials in primary spindle endings evoked by brief tendon taps in man.

The ligamentum patellae in human subjects was tapped by a random triangular waveform, while single primary spindle afferent spikes were recorded from the femoral nerve. Cross-correlation between the primary spindle afferent spikes and the taps revealed a prominent peaked distribution of the discharge probability. The cross-correlograms showed that response time from the onsets of taps to the afferent spike was 7.5 +/- 0.6 msec in 6 units and that the width between the feet of the peaked distribution was 3.3 +/- 0.2 msec in 6 units. The width of the peak implies jitter of the response time of the primary spindle spikes which appear to correspond with the time-to-peak of generator potentials elicited by the taps in primary endings of muscle spindles. Integration of the peaked distribution showed a slow slope at the beginning and near the summit and a steep slope on the way. This curve is assumed to represent the rising phase of the generator potentials in primary spindle endings.

Afferent Pathways↗
PubMed1982

Inhibitor effect of acupuncture on the vibration-induced grasp reflex in man.

The effect of acupuncture on the grasp reflex caused by mechanical vibrations of fingers produced by a cylinder-type vibrator (120 Hz) was studied in healthy man. As the hand grasped the vibrator during vibration, the volar surface of all fingers was simultaneously stimulated, resulting in a gradually increased force of the grasp, the vibration-induced grasp reflex (VGR). The VGR was inhibited by acupuncture with needles inserted into three acupuncture points (Shou Sanli, Chicheng and Szutu), but not into other sites in the hand.

Acupuncture Therapy↗
PubMed1982

EMG activity and kinematics of human cycling movements at different constant velocities.

Surface electromyographic (EMG) activity was recorded from the rectus femoris, vastus medialis, biceps femoris, gastrocnemius and tibialis anterior in the human lower extremity while subjects performed bicycling movements over a range of constant pedalling velocities. Kinematics of knee and hip cyclical movements were analyzed from 16 mm film. The reciprocal pattern of activation in agonist and antagonist muscles and timing of EMG initiation relative to knee joint were studied. Reciprocal activation of rectus femoris and biceps femoris muscles was generally observed to occur during the mid-extension or mid-flexion phase of knee movements. This timing of activation pattern coincided well with the period of peak angular velocity and zero angular acceleration. As pedalling speeds approached maximum, activation times of the bifunctional, biarticular rectus femoris, biceps and gastrocnemius muscles were considerably advanced in phase relative to knee joint angles, whereas, EMG initiation of monofunctional, single joint, tibalis anterior and vastus medialis muscles maintained a relatively stable knee position-activation time relationship. At higher velocities, biceps femoris EMG activity was characterized as having a double burst pattern of activation. A less distinctive double burst pattern was seen in the rectus femoris EMG at higher cycling speeds. EMG pattern analysis of the rectus and biceps femoris muscles revealed an earlier onset of activity for both muscles during maximum cycling velocities, relative to cyclical phases of the knee joint angle. Considerable overlapping of the EMG bursts was seen beyond pedalling rates of 1 Hz. Co-contraction between rectus femoris and biceps femoris muscles could be observed during the acceleration period involving an abrupt switch to maximum pedalling performance. When co-contraction was observed, the joint angular acceleration curves observed during the knee flexion period accounted for a larger portion of a single cycle, and were more irregular than the angular accelerations observed during knee extension.

Adolescent↗
PubMed1982

Characterization of alpha-fetoprotein secreted from cultured reuber H-35 hepatoma cells.

Reuber H-35 hepatoma cells were examined for their ability to synthesize protein in vitro, especially to produce alpha-fetoprotein (AFP). The presence of AFP in the culture supernatant solution was determined immunologically by the micro-Ouchterlony method. Charge heterogeneity of AFP was examined electrophoretically in continuous gradient polyacrylamide microgels. With regard to the duration of culture, there was no remarkable change in the ratio of two peaks of AFP, and which came out as a major combined peak and a similar peak by PAS staining on the condition of added SDS. These findings indicated that Reuber H-35 hepatoma cells had potential to produce two charge variants of AFP in vitro.

Animals↗
PubMed1981

Depression of ventral root--dorsal root potential by DL-alpha-aminoadipate in frog spinal cord.

Ventral root--dorsal root potential (VR--DRP) was partially depressed in the presence of 1 mM DL-alpha-aminoadipate (DL-alpha-AAD), probably corresponding to 0.5 mM D-alpha-AAD, in isolated hemisected frog spinal cord. It was suggested that acidic amino acid receptors might be subserving for the generation of VR--DRP in addition to the initial cholinergic link between motoneurons and interneurons and the electrical coupling between motoneurons and primary afferent terminals and the last step between unidentified interneurons and primary afferent terminals which had been reported to be mediated by GABA.

2-Aminoadipic Acid↗
PubMed1981

Properties of gizzard erosion-inducing substance in fish meal.

Heated whole fish meal, produced from mackerel, was proved to induce gizzard erosion in broiler chicks by feeding for 6 days. The constituents of the water-soluble fraction of fish meal were suspected to be the cause of this lesion. Of them, histidine, histamine and nucleotides were examined. When added to milk casein and heated, histidine appeared to be the most toxic. It seemed, however, that histamine and IMP (inosine 5'-monophosphate) might be less toxic even when treated in the same way a histidine. Feeding of a large amount of histamine alone resulted in giving rise to a much disturbed profile of body weight gain, while a low incidence of gizzard erosion was observed in this case. Both heated fish meal and a heated mixture of casein and histidine were easily reduced in toxicity by acid hydrolysis. The latter was more sensitive to this treatment. On the contrary, papain had an action to diminish the toxicity of heated fish meal at all. Even after treated with papain, the heated casein-histidine mixture was still effective to induce gizzard erosion. These results might have come from different structural changes caused by heating of the two samples.

Amino Acids↗