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Biomedical subjects

K Nagami

Publications and source records attributed to K Nagami.

5 recordsLinked to original sources
PubMed1992

Three distinctive activities of human triceps surae muscle during the stance phase in treadmill walking and running.

Activity of human triceps surae muscle (TS) during locomotion was investigated in relation to the muscle shortening and lengthening contractions. Length changes in the TS were presumed from its girth recorded using a mercury-in-silastic gauge wrapped around the muscle belly. The muscle girth during the stance phase resulted in three peaks corresponding to the actions of heel contact, weight support and toe kick. These peak heights were apparently larger than the girth level in the perpendicular standing posture. Three girth increases in running appeared in the process of ankle dorsiflexion. During walking, girth increases on weight support and toe kick were seen in the same phase. The TS through the stance phase is considered to always contract into a shortening state less than the muscle length in the perpendicular standing posture. These muscle activities are probably imposed to resist the muscle stretching. Therefore, it was suggested that the TS contracts eccentrically, with no lengthening contraction.

Adult↗
PubMed1990

Blood flow changes following brief concentric contractions of human calf muscles.

The present study was designed to clarify the venous return, filling velocity (Maximum Inflow Rate: MIR), and post-contraction hyperemia following brief concentric contractions of human calf muscles, using a double-stranded mercury-in-silastic gauge. The subject, in a prone position, extended the right ankle joint to 5, 10, 15, and 20 degrees at 20 degrees.sec-1 with a load of 20% of maximum voluntary contraction in ankle extensors. There was a significant relation between increase in calf girth at contraction and the amount of decrease, increase, total change (decrease plus increase), and MIR in calf volume after relaxation, and also between the MIR and amount of decrease, increase and total change in calf volume. The amplitude of the volume pulse wave apparently increased immediately after muscle relaxation, then progressively decreased. The maximum value appeared with the greatest increase in ankle extension. It was found that with increased muscle contraction, there was accelerated venous return, filling velocity of blood, and post-contraction hyperemia. Pulsatile blood flow into muscle tissue after brief muscle contractions might be qualitatively measured by the amplitude of the volume pulse wave.

Adult↗
PubMed1990

Excess venous return immediately after brief contraction of human calf muscles.

Venous return immediately after brief contraction of human calf muscles was measured. The subject extended his ankle joint in the range of 20 degrees for one second against loads of 10, 20, 30, and 40% of the maximum voluntary contraction in the ankle extensors. Venous return was determined by the difference between the increase in calf volume with (calf blood flow: CBF) and without (maximum inflow rate: MIR) thigh venous occlusion immediately after muscle relaxation. CBF and MIR progressively increased with the loads, and CBF was significantly greater than MIR. The level of venous return was correlated with the increase in the load. Transient increase in venous return was not associated with muscle pumping. Excess venous return should counteract arterial inflow and contribute to maintenance of equilibrium of the transmural pressure between muscle tissue and the capillaries.

Adult↗
PubMed1978

Inhibition of DNA synthesis by griseolutein in Escherichia coli through a possible interaction at the cell surface.

Griseolutein acts as a bactericidal agent, its toxicity decreasing with increase in cell density. There is no evidence that griseolutein acts at a specific stage of cell cycle. Inhibition of incorporation of radioactive thymidine into acid-insoluble fraction of cells is marked and rapid, while inhibition of incorporation of uridine also takes place. Incorporation of 32Pi into the acid-insoluble fraction of cells is inhibited while the incorporation into the nucleotide pool is not. Concentration of any of the four deoxyribonucleoside triphosphates in griseolutein-treated cells are similar to or higher than those in untreated cells. No extensive degradation of cellualr DNA is caused by griseolutein. DNA synthesis in plasmolyzed cells in not inhibited by griseolutein.

Anti-Bacterial Agents↗