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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 793 records · Page 44Linked to original sources
PubMed1981

Evidence for involvement of the frontal cortex in pain-related cerebral events in cats: increase in local cerebral blood flow by noxious stimuli.

Noxious stimuli were shown to induce a remarkable increase in local cerebral blood flow restricted to the forepart of the cerebral hemispheres bilaterally anterior to the posterior sigmoid gyrus in cats. This increase in local cerebral blood flow was averted by lesions in the bilateral ventromedial thalamus and attenuated by pretreatment with an intraventricular injection of 6-hydroxydopamine.

Animals↗
PubMed1981

Long lasting suppression of firing of cortical neurons and decrease in cortical blood flow following train pulse stimulation of the locus coeruleus in the cat.

Single neuron activity and local cerebral blood flow were recorded simultaneously in the same spot of the gyrus proreus in cats. Train pulse stimulation (10-20 Hz, 30 sec) of the ipsilateral locus coeruleus induced long lasting suppression of firing in up to 78% of neurons and decrease in local flow, which lasted 1.9-5.6 min and 3.8-6.5 min, respectively. Single pulse stimulation evoked inhibition of firing in 55% of the neurons investigated.

Animals↗
PubMed1981

Primary cerebral malignant lymphoma with macroglobulinemia and carcinoma of the colon.

A case of primary cerebral malignant lymphoma, immunoblastic type was reported. The immunoelectrophoresis of the patient serum showed an abnormal bow of IgM lambda type. Autopsy revealed that the cerebral lymphoma showed no extracranial spread except for adenocarcinoma of the colon with hepatic metastasis. Ultrastracturally, some of the lymphoma cells showed plasmacytoid differentiation. Immunoperoxidase study showed intracytoplasmic polyclonal immunoglobulins in non-neoplastic plasma cells around the colonic carcinoma, in the bone marrows, and spleen. However, neither IgM nor lambda light chain was found in the cerebral lymphoma cells. The source of the macroglobulinemia in this case was discussed.

Adenocarcinoma↗
PubMed1981

Mediators of slow synaptic potentials in the myenteric plexus of the guinea-pig ileum.

1. Intracellular recordings were made from neurones in the myenteric plexus of the ileum isolated from adult guinea-pigs.2. Three synaptic potentials were evoked in different myenteric neurones by focal stimulation of the ganglion surface at a distance of up to 100 mum from the cell body from which the recording was made. These were the fast cholinergic excitatory post-synaptic potential (e.p.s.p.), the slow e.p.s.p. and the slow inhibitory post-synaptic potential (i.p.s.p.).3. 5-hydroxytryptamine and substance P were applied to the neurones by superfusion (10 nm-1 mum) or by electrophoresis within 5 mum of the neurone cell body. 5-HT depolarized, hyperpolarized or had no effect on approximately equal numbers of neurones, whereas substance P depolarized 90% of neurones.4. Many neurones with a depolarizing slow e.p.s.p. were hyperpolarized by superfusion or electrophoretic application of 5-HT.5. Superfusion with 5-HT reversibly depressed the fast e.p.s.p., slow e.p.s.p. and slow i.p.s.p. Superfusion with substance P depressed the slow e.p.s.p.6. Methysergide (10-30 mum) reduced the amplitude of the fast e.p.s.p., the slow e.p.s.p. and the slow i.p.s.p.7. Chymotrypsin (200 mug/ml.) reversibly reduced the amplitude of the slow e.p.s.p., but had no effect on membrane potential, the action potential or the fast e.p.s.p. Chymotrypsin reduced or abolished the depolarization caused by electrophoretic application of substance P, but had no effect on the depolarization or hyperpolarization caused by 5HT.8. The results provide evidence that 5-HT is not the transmitter which mediates the slow e.p.s.p. in myenteric neurones. The slow e.p.s.p. may be caused by substance P or another similar peptide.

Animals↗
PubMed1980

Evidence that substance P is a neurotransmitter in the myenteric plexus.

Substance P (SP) is an undecapeptide originally isolated from the gut and since shown to occur within neurones in several parts of the peripheral and central nervous systems. Immunohistochemical studies indicate an exceedingly dense network of SP-containing nerves within the myenteric plexus of the guinea pig ileum. These nerves are intrinsic to the gut wall and can release SP to contract the longitudinal muscle layer. We have previously shown that SP directly depolarizes myenteric neurones and that this depolarization has a time course and ionic mechanism similar to the slow excitatory postsynaptic potential (e.p.s.p.) which can be produced by electrical stimulation of presynaptic nerves within the myenteric ganglia. We wondered whether SP might mediate this slow synaptic potential. We report here that the SP depolarization and the slow e.p.s.p. are reversibly depressed by chymotrypsin, an enzyme which degrades SP, although the responses to acetylcholine, serotonin and an unknown hyperpolarizing transmitter are unaffected. The results provide direct evidence that a peptide can mediate chemical transmission between neurones in the mammalian nervous system.

Animals↗
PubMed1980

Changes in local cerebral blood flow and neuronal activity during sensory stimulation in normal and sympathectomized cats.

Activities of neurons of the thalamic relay nucleus and cortical somatosensory area which are capable of producing excitatory potentials in response to stimulation of the sciatic nerve were recorded, and local cerebral blood flow was measured simultaneously using a double microelectrode under local anesthesia in both non-pretreated cats and cats undergoing chemical denervation of the vasoadrenergic nerves by intraventricular injection of 6-hydroxydopamine (6-OHDA), in order to unmask the neural control on the cerebral vessels during increase of local metabolic rate. The results obtained may be summarized as follows. (1) A positive correlation was found between an increase in firing rate of a single neuron in the thalamic relay nucleus and somatosensory area and an increase in local cerebral blood flow following stimulation of the sciatic nerve. A distinct spatial and quantitative correlation was thus observed between neural activity and cerebral blood flow. (2) In 6-OHDA-pretreated cats, an increase in neuronal firing rate was observed following stimulation of the sciatic nerve, as it was in non-pretreated cats, but the concurrent response of local cerebral blood flow was seriously impaired. All these findings indicate that the increase in local cerebral blood flow occurring in association with increased neural activity does not result solely from increased local metabolism and a consequent increase in CO2 production, but requires for its occurrence that certain basic conditions be satisfied and maintained by the vasoadrenergic innervation.

Adrenergic Fibers↗
PubMed1980

alpha-Guanidinoglutaric acid in cobalt-induced epileptogenic cerebral cortex of cats.

Guanidino compounds in the cobalt-induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G-520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic alpha-guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative-butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of alpha-guanidinoglutaric acid butylester (M+ = 365).

Animals↗