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Biomedical subjects

M Fujino

Publications and source records attributed to M Fujino.

At least 271 records · Page 15Linked to original sources
PubMed1983

Effect of secretin on protein phosphorylation in dispersed acini from rat pancreas.

Dispersed acini from rat pancreas, incubated in the presence of KH2(32)PO4 to steady state 32P incorporation into cellular proteins, were exposed to secretin. 32P incorporated into selected proteins, separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, reached a plateau by 150 min. Effect of secretin on amylase release, cellular cyclic AMP levels and protein phosphorylation was then examined. Stimulation of amylase release was apparent with 10(-10)M and was maximal with 10(-7)M by 10 min incubation. Almost maximal increase in cellular cyclic AMP levels and 32P incorporation into selected proteins was also observed with 10(-7)M secretin by 10 min in the presence of 10 mM theophyllin. Both secretin (10(-8)M) and dibutyryl cyclic AMP (10(-3)M) induced the phosphorylation of similar proteins analyzed by counting 32P content in each peptide band after SDS gel electrophoresis. Addition of cyclic AMP (10(-6)M) to homogenates of acini also augmented 32P incorporation from [gamma-32P]ATP into similar proteins. These results indicate that secretin enhances protein phosphorylation in pancreatic acinar cells and cyclic AMP may mediate the action of secretin on protein phosphorylation.

Animals↗
PubMed1983

Conformational change of mastoparan from wasp venom on binding with phospholipid membrane.

The conformational change upon binding with phospholipid membrane has been studied of mastoparan from wasp venom, a tetradecapeptide causing the degranulation of mast cells. The 270-MHz 1H-NMR spectra and CD spectra indicate that the mastoparan molecule takes the alpha-helical conformation in methanol solution, but a much less ordered form in aqueous solution. On binding with phospholipid membrane, the alpha-helical conformation is formed even in aqueous medium. Such a conformational change is primarily due to the interaction between the aliphatic side chains of mastoparan and the hydrophobic interior of phospholipid membrane, in contrast to the case of melittin from bee venom.

Bee Venoms↗
PubMed1983

The effect of oxygen on the development of atherosclerosis in WHHL rabbits.

The effect of hyperoxic or hypoxic inhalation on blood lipid levels and on the development of atherosclerosis was studied in young male WHHL rabbits. They were exposed to ordinary room air containing different concentrations of oxygen: 6 animals were exposed to 40% oxygen (hyperoxia group) or 5-10% oxygen (hypoxia group) for 5 h a day, 5 days a week for 8 weeks. Four control rabbits inhaled ordinary room air. The following results were obtained. (1) The severity of aortic lesions significantly decreased in the hyperoxia group and increased in the hypoxia group, when these two groups were compared. However, both hypoxic and hyperoxic groups did not statistically differ from the control. (2) Plasma cholesterol levels were not changed either by hyperoxic or hypoxic inhalation. (3) Plasma triglyceride levels were elevated only in the hypoxia group, with significant differences from the values in both control and hyperoxia groups. (4) There was no significant correlation between mean plasma lipid level and severity of aortic lesions. From these results, we conclude that hyperoxic or hypoxic inhalation respectively regresses or aggravates the development of atherosclerotic lesions, not by an indirect action on blood lipid concentrations but by a direct action on the vascular wall.

Animals↗
PubMed1983

Ultrastructural studies of the mouse aorta and its endothelial pinocytosis in diet-induced arteriosclerosis.

In mice fed on an atherogenic diet for 4 to 8 months, the aortas were examined by transmission and scanning electron microscopy. After 8 months of being fed a high cholesterol diet, the animals developed aortic intimal lesions composed mainly of proliferated modified smooth muscle cells with an increase of connective tissues. Scanning electron microscopy showed changes in aortic luminal surface consisting primarily of altered distribution of microvilli. Quantitative analysis of these changes showed a statistically significant (P less than 0.001) increase in cholesterol-fed animals compared with controls and a significant (P less than 0.001) difference between at 4 months and at 8 months in cholesterol-fed mice. Ultrastructural study on the uptake of protein tracer, horseradish peroxidase (HRP), by aortic endothelial cells in vitro was performed. The uptake of HRP was essentially the same for controls and cholesterol-fed mice at 4 months, but a statistically significant (P less than 0.005) increased uptake of HRP was observed at 8 months. Additional mice were subjected to nephrectomy with DOCA administration for 4 months along with a cholesterol-feeding. These animals showed a 2-fold increase in HRP-uptake compared with nephrectomized mice without a cholesterol-feeding. These results suggest that the enhanced pinocytotic activity of aortic endothelial cells in vitro, especially in hypertensive condition, and altered distribution of microvilli might be correlated to the arteriosclerotic process.

Animals↗
PubMed1983

The relationship of aging to histological changes in the conduction system of the normal human heart.

The effect of aging on histological changes of the conduction system was studied by serially sectioning 55 autopsied hearts weighing less than 300 Gm. None of the hearts showed evidence of cardiovascular disease nor were there any abnormalities in the clinical findings and ECG taken during the last 3 months of life. A reduction in the number of muscle cells and an increase in the number of collagen fibers were apparent in hearts taken from patients over 70 years of age. These findings were most evident in the S-A node and less so in A-V node, bundle of His, and left and right bundle branches. Deposition of amyloid substances was not observed in any portion of the conduction system.

Adolescent↗
PubMed1982

Evidence that dynorphin-(1-13) acts as an agonist on opioid kappa-receptors.

The study concerned the opioid-receptor subtype on which dynorphin-(1-13) acts in in vitro isolated preparations. The potency of dynorphin-(1-13) relative to that of ethylketocyclazocine (Mr 2266), a representative kappa-receptor agonist, in inhibiting the electrically evoked contractions of the guinea-pig ileum was found to be similar to that found with either mouse was deferens or rabbit ileum. Moreover, Mr 2266 was found to be several-fold more effective than naloxone to antagonize the agonist actions of both kappa-receptor agonists such as ethylketocyclazocine, ketocyclazocine and bremazocine, and dynorphin-(1-13) either in the guinea-pig ileum, mouse vas deferens, or in rabbit ileum. Additionally, dynorphin-(1-13) was found to have a significant inhibitory action on the rabbit vas deferens which had been shown to contain kappa-receptors exclusively. The data indicate that dynorphin-(1-13) acts as an endogenous agonist on kappa-receptors.

Animals↗
PubMed1982

Effects of solution of low pH and taurocholate on release of beta-endorphin-like immunoreactivity from human duodenal mucosa in vitro.

The presence of beta-endorphin-like immunoreactivity (beta-EpLI) in human duodenum and its release were studied. beta-EpLI was detected in the duodenum (mucosa, 26.7 +/- 6.3 pmol/g wet weight, mean +/- SEM; remaining tissue 23.1 +/- 5.3 pmol/g wet weight) and the stomach (7.1 pmol/g wet weight). The two activities gave similar curves for inhibition of beta-Ep radioimmunoassay of synthetic beta-Ep. On gel-filtration chromatography of a duodenal extract, two components of beta-EpLI were separated. When human duodenal mucosa was perfused with a solution of pH2 or 1mM or 5mM taurocholate, the release of beta-EpLI from mucosa into the perfusate increased 2-4 fold. These results indicate that beta-EpLI present in human duodenal is released by the direct action of low pH or taurocholate on the duodenal mucosa and suggest that it may have a physiological role.

Chromatography, Gel↗
PubMed1982

Ouabain potentiation and Ca release from sarcoplasmic reticulum in cardiac and skeletal muscle cells.

In this article, we describe a possible mechanism of ouabain potentiation in heart based on the following findings in cardiac and skeletal muscles of various species. (1) In heart ventricle muscles of frog and guinea pig, the ouabain potentiation is produced without an effect on Ca influx. In both frog and cat heart ventricle muscles, ouabain potentiates the rapid cooling contracture with or without caffeine in a Ca-deprived medium. It follows, therefore, that the ouabain potentiation is produced by an "intracellular" mechanism. (2) In crab single muscle fibers, contractile responses such as twitch, potassium-induced contracture, caffeine-induced contracture, and water-induced contracture are remarkably potentiated if ouabain is present within the fibers by microinjection, whereas the situation is reversed if the drug is given extracellularly. (3) The ouabain potentiated the Ca release from fragmented sarcoplasmic reticulum (FSR) isolated from cat, guinea pig, and frog heart and from skeletal muscles as a result of the procedures used, such as changing the ionic environment. (4) In frog, cat, and guinea pig heart ventricle muscles, a reduction of contractility as a result of pretreatment with urea--Ringer's was completely cancelled by ouabain almost without influencing the membrane depolarization. Based on these findings and others, the deduction was made that the positive inotropic effect of cardiac glycosides on the heart is brought about by potentiation of contraction - Ca release from the intracellular store sites, namely the sarcoplasmic reticulum.

Animals↗
PubMed1981

Correlation between pharmacological and opiate receptor binding activities of tetrapeptide acylhydrazide analogs of enkephalin.

The pharmacological and opiate receptor binding activities of four synthetic tetrapeptide acylhydrazide analogs of enkephalin (EK compound) were compared with those of reference compounds. EK-159 administered subcutaneously was less analgesic, while EK-209, EK-259 and EK-272 were more potent than morphine in the hot plate, Haffner's and phenylquinone writhing tests in mice. EK-272 being the most active was comparable to what was found with FK-33824. IC50 values of EK compounds in a sodium-free medium in the opiate receptor binding assay were lower than the values seen with morphine. The binding activities of EK compounds in 100 mM NaCl medium showed a clearer correlation with their analgesic activities than was seen in the absence of sodium ion. The binding affinity of EK-272 was the highest and the sodium response ratio (IC50 + NaCl/IC50-NaCl) was slightly lower than that of pentazocine. The analgesic action in rodents, respiratory inhibition in rabbits, inhibition of intestinal movement in mice, and hyperthermic action in rats, were all qualitatively, but not quantitatively similar to the effects seen with morphine. The analgesic action of EK compounds was relatively resistant to the antagonizing effect of naloxone and the EK compounds modified the analgesic action of morphine. These properties were inversely correlated with the sodium response ratios.

Analgesics↗
PubMed1981

Presence of dynorphin-like immunoreactivity in rat pituitary gland and hypothalamus.

Using a highly specific and sensitive radioimmunoassay for dynorphin(1-13), dynorphin-like immunoreactivity (dynorphin-LI) was detected in rat pituitary and hypothalamus. Gel chromatographic studies on Sephadex G-50 revealed three components of dynorphin-LI with molecular weights of approximately 7500-9500 (big dynorphin), 3500-5500 (intermediate dynorphin) and 1600-1900 (small dynorphin), the latter of which eluted at the same position as authentic dynorphin contamination in porcine ACTH extracts (Sigma). Dynorphin-LI in rat anterior pituitary existed mainly as big dynorphin, whereas dynorphin-LI in rat intermediate-posterior pituitary and hypothalamus eluted mainly at the position of authentic small dynorphin.

Animals↗