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Biomedical subjects

F Yamada

Publications and source records attributed to F Yamada.

At least 55 records · Page 3Linked to original sources
PubMed1993

Glucoregulatory hormones in the immobilization stress-induced increase of plasma glucose in fasted and fed rats.

We investigated 1) the effect of immobilization stress on glucose metabolism in rats after sham operation (SHAM), adrenomedullectomy (ADMX), and adrenalectomy (ADX); and 2) the effect of glucoregulatory hormone infusion on plasma glucose using untreated normal fasted and fed rats under unanesthetized conditions. In immobilization stress, the plasma glucose concentration increased only in the SHAM group during fasting, while under fed conditions, all three groups showed significant increases (SHAM > ADMX > ADX). Plasma glucagon and norepinephrine significantly increased in all groups; plasma epinephrine increased only in the SHAM group, and plasma corticosterone increased in SHAM and ADMX groups under both conditions. The hepatic glycogen content in all fed groups significantly decreased after immobilization stress, while a very low content before stress and an undetectable level after stress were observed in all fasted groups. Only epinephrine infusion increased plasma glucose during fasting, while epinephrine and glucagon infusion increased it under fed conditions. Corticosterone infusion did not change it under either condition. These results suggest that in the fasted condition, only epinephrine plays an essential role, while under fed conditions, glucagon and corticosterone as well as epinephrine also act as synergistic factors in stress-induced hyperglycemia.

Adrenal Medulla↗
PubMed1993

Epidermoid cysts of the callosal region--three case reports.

Three patients with rare epidermoid cyst in the callosal region are described, two adjacent and one in the corpus callosum. Computed tomography revealed atypical features, i.e. a large, well-defined high-density mass unenhanced postcontrast and a well-defined hypodense mass with marginal calcification in one case each. Such a diffuse high-density mass may be caused by hemorrhage, highly concentrated protein or calcification of keratinized debris within the cyst. Marginal calcification may occur for unknown reasons. The cysts were subtotally removed.

Adult↗
PubMed1993

TV game play and obesity in Japanese school children.

A survey conducted in 9 cities in Japan indicated for 1517 boys and 1546 girls there was more use of TV games for longer periods when children were classified as obese than when classified as moderate or lean. More boys than girls played although most children had experience and many owned TV game machines.

Body Mass Index↗
PubMed1992

Diphosphorylation of platelet myosin ex vivo in the initial phase of activation by thrombin.

We prepared anti-platelet 20-kDa myosin light chain (MLC-20) antibody and demonstrated diphosphorylation of MLC-20 in platelets ex vivo in the initial phase of activation by thrombin. Our results are as follows. (1) By Western blotting, using anti-MLC-20 antibody, both mono- and diphosphorylated myosin were seen in the initial phase of aggregation of platelets by thrombin. The peak of the diphosphorylation was later than that of monophosphorylation and the degree of both mono- and diphosphorylation reduced in the process of aggregation. (2) ML-7 (a synthetic inhibitor of MLCK) inhibited both mono- and diphosphorylation of myosin and also blocked aggregation of thrombin-activated platelets. However, H-7 (an inhibitor of protein kinase C) had little effect on either the (di)phosphorylation of myosin or the aggregation of thrombin-activated platelets. (3) Arg-Gly-Asp-Ser (RGDS) peptide, a synthetic anti-adhesive peptide, inhibited aggregation of thrombin-activated platelets in a dose-dependent manner (100-200 microM). However, it had little effect on either mono- or diphosphorylation of myosin in the process of the platelet aggregation stimulated by thrombin. From these results, we conclude that mono- and diphosphorylation of myosin by MLCK play a role in the initial phase of activation of thrombin-stimulated platelets in vivo and that mono- and diphosphorylation of myosin by MLCK precedes the secondary signal mediated by GPIIb/IIIa.

Azepines↗
PubMed1992

[A case of giant pigmented nevus with multiple meningiomas].

A 36-year-old female had a giant congenital pigmented nevus on her anterior trunk. She complained of muscle weakness of the right arm and leg in August 1988, and she was admitted to our hospital to take medical examinations in September 1988. Neurological examination revealed right hemiparesis and exaggerated deep tendon reflexes. Three small falx meningiomas were shown on CT scans and MR images, but they did not appear to be causes of her symptoms. CT-myelography and MR images revealed an intradural extramedullary tumor spreading from the foramen magnum to C2. Oncotomy and C1 laminectomy were performed. Histological finding was compatible with transitional meningioma. Neurological symptoms markedly improved after operation. This patient is considered as a case of neurocutaneous syndrome with central nervous system tumors. Considering that both giant pigmented nevus and meningioma originate from neural crest, they appear to be closely related each other. Such a combination of giant pigmented nevus and meningioma has not yet been reported.

Adult↗
PubMed1992

[A pharmacokinetic study of intra-arterial chemotherapy for prophylactic treatment of liver metastasis after hepatectomy for liver cancer].

As a fundamental study of efficacy of intra-arterial administration using ADM, ERB and MMC for prophylactic treatment of liver metastasis after hepatectomy for liver cancer, the pharmacokinetics of three drugs (ADM 10mg (n = 5), ERB 20mg (n = 3) and MMC 6 mg (n = 3)) were studied in patients who underwent hepatectomy after intra-arterial injection. The hepatic extraction calculated from the areas under the plasma concentration time curve of both administrations was 40% in ADM, 60% in ERB, and 0% in MMC. From these findings, it is suggested that intra-arterial administration could reduce by half the systemic toxic side effects of ADM or ERB, but the advantage of intraarterial infusion of MMC was not obvious.

Chemotherapy, Adjuvant↗
PubMed1991

Potencies and stereoselectivities of enantiomers of huperzine A for inhibition of rat cortical acetylcholinesterase.

The stereoselectivities and mechanisms of the inhibition of rat cortical acetylcholinesterase by the enantiomers of huperzine A were determined. (-)-Huperzine A was the more potent enantiomer with a Ki value of 8 nM. (+)-Huperzine A inhibited the enzyme 38-fold less potently with a Ki value of 300 nM. Racemic huperzine A was about two-fold less potent than the more active isomer, (-)-huperzine A. The mechanism of inhibition of acetylcholinesterase for all three drugs was of the mixed linear competitive type.

Alkaloids↗
PubMed1990

cDNA cloning and sequencing for the import precursor of subunit B in H(+)-ATP synthase from rat mitochondria.

The nucleotide sequence of the import precursor of subunit b of rat liver H(+)-ATP synthase has been determined from a recombinant cDNA clone isolated by screening a rat liver cDNA library with a probe DNA. The sequence was composed of 1,124 nucleotides including a coding region for the import precursor of subunit b and noncoding regions of both the 5'- and 3'-sides. The import precursor of subunit b and its mature polypeptide deduced from the open reading frame consisted of 256 and 214 amino acid residues with a molecular weight of 28,867 and 24,628, respectively. The presequence of 42 amino acids could be the import signal peptide which serves to direct the protein into the mitochondrial matrix.

Amino Acid Sequence↗
PubMed1990

cDNA cloning and sequencing of component C5 of proteasomes from rat hepatoma cells.

Proteasomes are multicatalytic proteinase complexes consisting of a set of non-identical polypeptide subunits. A cDNA for component C5 of rat proteasomes was isolated by screening a Reuber H4TG hepatoma cell cDNA library using synthetic oligodeoxynucleotide probes corresponding to partial amino acid sequences of the protein. The polypeptide deduced from the open reading frame consisted of 240 amino acid residues with a calculated molecular weight of 26,479. Computer analysis revealed little similarity of C5 to other proteins reported so far. The primary structure of C5 showed partial sequence homology to that of another component C3, but no regions of homology with the sequence of component C2. Thus C5 is concluded to be a new type of subunit of the proteasome complex.

Amino Acid Sequence↗
PubMed1990

Pharmacokinetics of midaglizole, a new hypoglycaemic agent, in healthy subjects.

The objective of this study was to evaluate the pharmacokinetics of midaglizole, a new orally effective hypoglycaemic agent, in healthy male subjects. In Study I, volunteers were given single oral doses of 150, 200, 300, and 500 mg of midaglizole 20 min before breakfast. In Study II, 200 mg of midaglizole was given 30 min after breakfast. In Study III, multiple oral administration study was carried out at a dose of 200 mg t.i.d. 20 min before meals for 7 days. The disposition of midaglizole was adequately described by a one-compartment open model with first order absorption. It was essentially dose-dependent up to 500 mg given orally. The pharmacokinetic parameters calculated by employing this model indicated that the disposition of this drug was characterized by good absorption from the intestine, a wide distribution in the body, and a rapid excretion via the kidneys. The absorption rate of midaglizole from the intestine was definitely slowed by the presence of food, probably due to a decrease in the rate of gastric emptying. No clinical significant accumulation of midaglizole in the body was observed during or after multiple doses. A linear correlation was found between the area under the curve of plasma concentration of midaglizole versus time and the area calculated from the curve of change in blood glucose level versus time after oral administration of midaglizole.

Adult↗
PubMed1990

Changes of eye-blink activities during hypnotic state.

Three experiments were conducted to examine eye-blink activity during the hypnotic state. The results were as follows: (1) eye-blink rate was dramatically reduced during the hypnotic as compared to the nonhypnotic state, (2) blink-rate variability between events (for example, the task and rest period) was smaller under the hypnotic than under the nonhypnotic state, (3) decrements, after induction of hypnosis, were observed in all aspects of blink-wave attributes (amplitude, duration, slope, and area). These findings can be interpreted in terms of the facilitation of motor inhibition by hypnosis.

Adult↗
PubMed1989

Activation of trout macrophages and production of CRP after immunization with Vibrio anguillarum.

To examine the mechanism of the protection of rainbow trout (Salmo gairdneri) against Vibrio anguillarum in the early stage of immunization, the activation of macrophages and production of C-reactive protein (CRP) were investigated. Fish immunized with formalin-killed bacteria emulsified in Freund's complete adjuvant (FCA) resisted intraperitoneal challenge with living bacteria seven and ten days after immunization. The activation of macrophages was demonstrated by a significant increase of the chemiluminescent (CL) response and phagocytic activity. These fish also showed a significant increase of the CRP level in sera. Fish immunized with V. anguillarum alone or injected with FCA, however, did not resist the challenge. Though FCA itself increased CRP level and the sera enhanced phagocytic activity, increase of CL activity was weak. These results indicated that the increase of CL activity and opsonising effect of CRP on the phagocytosis of specifically activated macrophages concern to host defense in the early stage of infection.

Animals↗