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Biomedical subjects

M Ishida

Publications and source records attributed to M Ishida.

At least 559 records · Page 31Linked to original sources

Pharmacological distinction between the excitatory junctional potential and the glutamate potential revealed by concanavalin A at the crayfish neuromuscular junction.

The effect of concanavalin A(Con A) on desensitization of the glutamate receptor was investigated in the crayfish opener muscle. The depolarization of the crayfish muscle fiber caused by bath-applied L-glutamate was greatly augmented by Con A. The time course of the appearance of the augmentation was slow. Con A completely prevented the development of desensitization of the glutamate receptor. When L-glutamate was applied iontophoretically with a constant current pulse, a decline of the depolarization was seen during the course of the drug application which was presumably due to desensitization of the glutamate receptor. The glutamate potential was slightly increased by Con A, though the increase was transient. On the other hand, the amplitude of excitatory junctional potentials (EJPs) was not increased but decreased by addition of Con A. In normal saline, the amplitudes of both glutamate potentials and EJPs remarkably decreased because of desensitization of the glutamate receptor, but the decrease in amplitude of the glutamate potential was completely prevented by previous application of Con A. On the other hand, Con A had no influence upon the decrease in amplitude of EJPs. These results show that there is a pharmacological difference between the glutamate potential and EJPs.

Animals↗

Established cell line sensitive to influenza C virus.

Various strains of influenza C virus grew productively in an established line of monkey kidney cells (LLCMK2) without prior adaptation. When trypsin was added to the medium, higher virus yields were obtained than in other cell cultures. All influenza C virus strains tested formed well defined plaques under the agar overlay medium containing trypsin. Infectivity determined by plaque assay in LLCMK2 cells was higher than that determined by amniotic inoculation of fertile hens' eggs.

Animals↗

Insulin and glucagon secretion in hepatic glycogenoses.

Insulin and glucagon secretion was investigated in ten patients with hepatic glycogenosis, types I and III, in order to understand the relationship between hypoglycemia and pancreatic function. In all patients, both oral glucose tolerance and intravenous arginine infusion tests revealed hypoinsulinemia. Decreased urinary C-peptide levels with standard food intake also supported hypofunction of pancreatic beta cells. On the contrary, the normal secretion pattern of glucagon in both types indicated in the arginine loading test, intact alpha cells in the pancreas. Persistent hypoinsulinism, which is apparently an adaptation to hypoglycemia, could be an important cause of nutritional dwarfism in both types of glycogenosis. The usefulness of the measurement of urinary C-peptide, which evaluates the pancreatic function and provides management for normal body growth, is discussed.

Blood Glucose↗

A case of mesenchymoma in the oral cavity clinically resembling a large pleomorphic adenoma.

A report is made of a 52-year-old male whose main complaint was a painless tumor at the right side of the palate resulting in speech disturbance. He was diagnosed as a case of what Stout called benign mesenchymoma. Some discussion is also made of the tumor pathology in terms of genetic factors, predirective sites, age range, sex differences and therapy.

Adenoma, Pleomorphic↗

Glutamate potential : differences from the excitatory junctional potential revealed by diltiazem and concanavalin A in crayfish neuromuscular junction.

1. The effect of diltiazem and concanavalin A (Con A) on the crayfish neuromuscular junction was investigated in order to compare the action of L-glutamate with that of the excitatory transmitter. 2. When diltiazem (0.3 nM) was added to the perfusion fluid, the iontophoretic glutamate potential was reduced to about half, whereas the amplitude of excitatory junctional potentials (EJPs) increased by about two times. 3. Dose-response curves of L-glutamate suggested that diltiazem acted in a non-competitive manner. The decrease in amplitude of the glutamate potential caused by diltiazem was not due to the acceleration of desensitization of the glutamate receptor. 4. The increase in amplitude of EJPs caused by diltiazem was due to the increase in membrane resistance. The quantal content and size of extracellular EJPs were not affected by diltiazem. 5. In normal saline, bath application of glutamate decreased the amplitude of both glutamate potentials and EJPs because of desensitization of the glutamate receptor. The decrease in amplitude of the glutamate potential was completely prevented by previous application of Con A (10(-6) M). On the other hand, Con A had no influence on the decrease in amplitude of EJPs. 6. Some possible explanations of these pharmacological differences between glutamate potentials and EJPs revealed by diltiazem and Con A are considered.

Animals↗