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Biomedical subjects

H Fukuda

Publications and source records attributed to H Fukuda.

At least 1,225 records · Page 68Linked to original sources
PubMed1977

The effect of basal hypothalamic isolation on pituitary-thyroid activity and the response to propylthiouracil.

Basal hypothalamic deafferentation extending from the posterior border of the optic chiasm to the mid-mammillary bodies resulted in depression of plasma TSH, thyroxine (T4), and triiodothyronine (T3) concentration to 50% of normal controls within 7 days. Administration of 0.15% propylthiouracil (PTU) in the diet form postoperative day 26 caused a pronounced drop in the plasma T3 level and a rise in plasma TSH level within two days in the control animals, but had little effect during this interval in the deafferented animals. After 12 days of PTU, plasma T3 and T4 concentrations had dropped to undetectable concentrations in the control animals but both were still detectable in the deafferented animals. After 25 days of PTU, plasms T4 and T3 levels were undetectable and plasma TSH levels were significantly elevated above normal in all animals. Thyroid hypertrophy at that time was as great in the deafferented as in the control rats, although plasma TSH concentration was 50% lower in the former. Administration of 0.1 mug/100 g BW TRH iv on postoperative day 37, when plasma T4 and T3 were undetectable in the controls but still present in the deafferented animals, produced an equally high concentration of plasma TSH in all animals. We interpret these data to support the concepts that: 1) a major source of neural drive of that TRH which stimulates the secretion of TSH by the adenohypophysis lies outside the medial basal hypothalamus, 2) a decrease in TRH reaching the adenohypophysis causes a lower setting of the "thyrostat" sensitive to the concentration of circulating thyroid hormone, and 3) increased TSH secretion and resultant goitrogenesis is delayed in animals with impaired TRH secretion because of the slower rate of secretion of thyroid hormone than in intact controls and the longer time thus required to markedly reduce the concentration of circulating thyroid hormone.

Afferent Pathways↗
PubMed1977

[Pharmacological study on 5-(o-chlorophenyl)-1-methyl-7-nitro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-690), with special reference to the effects on motor systems].

Effects of ID-690 on motor systems were compared with those of clonazepam, diazepam and nitrazepam. ID-690 exerted muscle relaxant action in the rotarod method using rats and mice; this action was almost equal in potency to clonazepam and nitrazepam and more potent than diazepam. Pretreatment with ID-690, clonazepam and nitrazepam increased the sleeping time of mice under thiopental anesthesia to the same degree, whereas diazepam produced a lesser effect. ID-690 was almost equal in potency to diazepam and nitrazepam in protecting against oxotremorine-induced tremor in mice, and approximately 10 times as potent as clonazepam. The anticonvulsant action of ID-690 was similar to that of clonazepam. These benzodiazepines effectively augmented the dorsal root reflexes, while showing no effects on the ventral root reflexes. Rigidity in rats due to anemic decerebration was not affected after intraduodenal administration of these drugs, while phasic augmentation of the rigidity by mechanical stimulation of the hind limb was clearly depressed. These drugs had no effects on the neuromuscular junction. From these results, it is concluded that ID-690 has a wider pharmacological spectrum than clonazepam, is almost equal in potency to nitrazepam and is more potent than diazepam.

Animals↗
PubMed1976

Preoperative cell-mediated immune status of gastric cancer patients.

The status of cell-mediated immunity was studied in 360 patients with gastric cancer before surgery. For the skin test, tuberculin and DNCB were employed. For the in vitro test, the blastogenesis of peripheral blood lymphocytes to phytohemagglutinin (PHA), the ratio of rosette-forming T cells to sheep blood red cells, and the macrophage migration inhibiotry factor against autochthonous tumor antigens were measured. As a result, it was found that in progressive gastric cancers the cell-mediated immunity decreased specifically or nonspecifically, especially the DNCB reaction; and the blastogenesis against PHA showed an inverse correlation to the advance of gastric cancer.

Adult↗
PubMed1976

[Effect of drugs affecting sodium permeability on the muscle spindle of frogs].

Afferent discharges of about 10 Hz were recorded in the nerve from the isolated muscle spindle of the m. extensor longus digiti IV of the bullfrog subjected to a sustained stretch. When grayanotoxin-I, ventridine or aconitine was added to the Ringer's solution, the rate of discharges markedly increased and thereafter decreased. In these terms of decrease of discharges, abortive spikes were observed. The rate of discharges was markedly decreased by the application of procaine, diphenylhydantoin, chlorpromazine or tetrodotoxin. With the latter three drugs, abortive spikes were observed in the course of decrease of discharges. Increase of the discharge rate induced by grayanotoxin-I, veratridine and aconitine was antagonized by procain. No alteration was evident in the conduction of afferent discharges, when test drugs were applied to the nerve trunk in concentrations sufficient to change the rate of discharges when applied to the muscle spindle. These results suggest that the rate of the muscle spindle discharges is closely related to sodium permeability of the membrane.

Aconitine↗
PubMed1976

Effects of metabolic inhibitors and ouabain on static afferent discharges from the isolated frog muscle spindle.

Effects of metabolic inhibitors and ouabain on the rate of afferent discharges from isolated muscle spindle of the bullfrog were examined in vitro to elucidate the mechanism for generating afferent action potentials. Dinitrophenol, NaCN, iodoacetic acid, and ouabain gradually reduced the rate of discharges. These drugs were without direct effect on the nerve axon. The rate of discharges was also reduced by Li+, which is known to be minimally extruded from the interior of cells by an active transport mechanism. The rate of discharges remained approximately 50% in the presence of NaCN or in the absence of oxygen, suggesting that the energy required for the maintenance of the Na+-pump can be supplied to some extent in an anaerobic condition. It appears that the metabolic inhibitors and ouabain reduce the afferent discharges from the frog muscle spindle by affecting the Na+-pump in fibers of nerve terminals.

Afferent Pathways↗
PubMed1976

[Effects of divalent cations on the muscle spindle of frogs].

Afferent discharges were recorded in the nerve from the isolated muscle spindle of the m. extensor longus digiti IV of the bullfrog. Discharges of about 10 Hz generated by a sustained stretch were reduced concentration-dependently when Ca2+, Mg2+ or Mn2+ (1.0 approximately 8.0 mM) was added to normal Ringer's solution containing 2.0 mM Ca2+. In terms of the decrease of discharges following the addition of Ca2+ or Mn2+ (4.0 mM), abortive spikes were observed. With an excess of Mg2+ (4.0 mM), abortive spikes were not apparent. Removal of Ca2+ from the Ringer's solution caused an increase in the rate of discharges, and normal levels were restored by the addition of Ca2+ (2.0 mM), Mg2+ (2.3 mM) or Mn2+ (1.8 mM). Application of much higher concentrations of these ions to the nerve trunk produced no alterations in the conduction of afferent discharges. It appears that Ca2+ in the external medium contributes to the inhibition of the mechanism responsible for generating afferent discharges in the muscle spindle and that Ca2+ action is not specific since Mg2+ and Mn2+ can act as substitutes for Ca2+ to regulate afferent discharges.

Afferent Pathways↗