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Biomedical subjects

T Namba

Publications and source records attributed to T Namba.

At least 325 records · Page 18Linked to original sources
PubMed1971

Cholinesterase inhibition by organophosphorus compounds and its clinical effects.

The clinical manifestations of acute poisoning by organophosphorus compounds in man are in accord with, initially, the stimulation and, later, the blocking of cholinergic transmission due to acetylcholinesterase inhibition. The manifestations involve mainly the para-sympathetic nerves, the neuromuscular junctions, and the central nerve synapses, and to a smaller degree the cholinergic sympathetic nerves. Miosis and muscle fasciculations are useful signs for diagnosis and for the control of therapy. Blood cholinesterase determination is the best diagnostic test. The cause of death is usually respiratory paralysis. Persistent manifestations have not been confirmed. Atropine and pralidoxime are effective for treatment and useful for diagnosis. Other oximes are promising but their clinical value has not been established. Poisoning by malathion is characterized by a prolonged course and by motor signs. Poisoning by organophosphorus compounds in man differs from animal experiments in several ways: in man, exposure may occur by several different routes, the manifestations are detected more easily, and therapy is given throughout the course of illness.

Acetylcholinesterase↗
PubMed1970

Cholinesterase activity of motor end plate in human skeletal muscle.

The activity and properties of cholinesterase of the motor end plate in human intercostal muscle were studied in the isolated muscle membrane. This preparation was used because cholinesterase activity of the membrane preparation was localized in the motor end plate without contamination of cholinesterase of other muscle components. Under the experimental conditions, cholinesterase in a human end plate hydrolyzed 1.21 x 10(8) molecules of acetylcholine per msec, which is smaller than hydrolysis of 2.69 x 10(8) by a motor end plate of rat intercostal muscle. Studies with cholinesterase inhibitors and specific substrates indicated that about 90% of cholinesterase of human motor endplates is acetylcholinesterase, and about 10% is pseudocholinesterase. The end plate cholinesterase had an optimal pH of 7.8 and a Michaelis-Menten constant of 4.15 mmoles/liter, and was stable at 4 degrees C for at least 4 wk. Motor end plates were estimated to contain only about 2% of the total cholinesterase activity of human intercostal muscle, compared with about 20% in rat tibialis anterior muscle. The difference is due to the lower cholinesterase activity of the motor end plate and higher cholinesterase activity of non-end plate components in human muscle than in rat muscle. The isolated muscle membrane provides a useful preparation for the study of the properties of motor end plate in human skeletal muscle.

Acetylcholine↗