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Biomedical subjects

M Miyazaki

Publications and source records attributed to M Miyazaki.

At least 865 records · Page 48Linked to original sources
PubMed1984

Heterogeneity in the response to vasoconstrictors of isolated dog proximal and distal middle cerebral arteries.

Responses to vasoconstrictor agents were compared in helical strips of proximal and distal middle cerebral arteries isolated from the same dogs. Contractions induced by 30 mM K+ per cross-sectional areas in the large and small artery strips did not differ significantly so that contractions induced by the agents could be compared relative to those induced by K+. The contractions induced by serotonin were greater in the proximal than in the distal arteries. Histamine produced a greater contraction in the proximal arteries under resting conditions. Distal arteries partially precontracted with prostaglandin F2 alpha responded to histamine with relaxations. The histamine-induced contraction was attenuated by chlorpheniramine, whereas the relaxation was suppressed by cimetidine. Prostaglandin F2 alpha or carbocyclic thromboxane A2 produced similar magnitudes of contractions in the proximal and distal arteries. Thrombin contracted the distal arteries to a greater extent. Contractions induced by norepinephrine or bradykinin did not differ in the proximal and distal arteries. It may be concluded that the ratio of histaminergic H1 and H2 receptor functions decreases peripherally along middle cerebral arteries, whereas the contractile response to bradykinin was not influenced in these arteries of a relatively short distance. The functions of receptor sites for serotonin and thrombin appear to be quite different in large and small cerebral arteries of such a short distance, but alpha-adrenoceptor functions seem to be identical.

Animals↗
PubMed1984

Modification by yohimbine and prazosin of the mechanical response of isolated dog mesenteric, renal and coronary arteries to transmural stimulation and norepinephrine.

Some functions of pre- and postsynaptic alpha-receptors were compared in isolated dog arteries. In mesenteric and renal arteries, contractile responses to transmural electrical stimulation were potentiated by yohimbine, a selective alpha 2-antagonist; the potentiation was greater in mesenteric arteries. Concentration-response curves for norepinephrine were shifted to the right by high concentrations of yohimbine. Prazosin, a selective alpha 1-antagonist, in low concentrations preferentially attenuated the contractile response to transmural stimulation, when compared with the response to equiactive concentrations of norepinephrine. Relaxant responses of coronary arteries to transmural stimulation were also potentiated by yohimbine. Relaxations induced by norepinephrine were not influenced by yohimbine but were potentiated by prazosin. Contractile responses of coronary arteries treated with propranolol to transmural stimulation were abolished by prazosin. It is concluded that the involvement of presynaptic alpha 2-receptors in the negative feedback mechanism in transmitter release differs in a variety of dog arteries and that the adrenoceptors subserving contraction are of both subtypes (alpha 1 and alpha 2) in the mesenteric and renal arteries, but only of the alpha 1 subtype in coronary artery.

Animals↗
PubMed1984

Polypeptide chain elongation factor 1 alpha (EF-1 alpha) from yeast: nucleotide sequence of one of the two genes for EF-1 alpha from Saccharomyces cerevisiae.

Messenger RNA for yeast cytosolic polypeptide chain elongation factor 1 alpha (EF-1 alpha) was partially purified from Saccharomyces cerevisiae. Double-stranded complementary DNA (cDNA) was synthesized and cloned in Escherichia coli with pBR327 as a vector. Recombinant plasmid carrying yEF-1 alpha cDNA was identified by cross-hybridization with the E. coli tufB gene and the yeast mitochondrial EF-Tu gene (tufM) under non-stringent conditions. A yeast gene library was then screened with the EF-1 alpha cDNA and several clones containing the chromosomal gene for EF-1 alpha were isolated. Restriction analysis of DNA fragments of these clones as well as the Southern hybridization of yeast genomic DNA with labelled EF-1 alpha cDNA indicated that there are two EF-1 alpha genes in S. cerevisiae. The nucleotide sequence of one of the two EF-1 alpha genes (designated as EF1 alpha A) was established together with its 5'- and 3'-flanking sequences. The sequence contained 1374 nucleotides coding for a protein of 458 amino acids with a calculated mol. wt. of 50 300. The derived amino acid sequence showed homologies of 31% and 32% with yeast mitochondrial EF-Tu and E. coli EF-Tu, respectively.

Amino Acid Sequence↗
PubMed1984

Distribution of polymorphic forms of troponin components in extra- and intrafusal fibers of an avian slow muscle.

By indirect immunofluorescence microscopy, the reactivities of extra- and intrafusal muscle fibers with antibodies against troponin (TN) components were studied in an avian slow muscle, the anterior latissimus dorsi (ALD) of the chicken. Serial cross sections of the muscle were exposed to antibodies specific to TN components (TN-T, -I, and -C) from adult chicken breast and ventricular muscles. In extrafusal fibers, four distinct categories were identified on the basis of differential reactivity with these antibodies. The predominant population of fibers (greater than 95%) reacted weakly only with antiventricular TN-C. The second type of fibers (less than 5%) was stained with antibodies raised against breast TN components. The third group of fibers (less than 1%) was labeled not only with antibreast TN components, but also with antiventricular TN-T and -C. The last class of fibers (less than 1%) reacted with antibodies directed against ventricular TN-T and -C. These results were correlated with myofibrillar ATPase staining patterns of fibers. In intrafusal muscle fibers of this muscle, the same four types of fibers were observed; in these fibers, however, there appeared to be a longitudinal variation in the reactivity. In conclusion, the slow ALD muscle of the adult chicken contains populations of both extrafusal and intrafusal fibers which are heterogeneous in reactivity with TN component antibodies.

Adenosine Triphosphatases↗
PubMed1984

Comparison of cytologic and biochemical properties between liver cells isolated from adult rats by trypsin perfusion and those isolated by collagenase perfusion.

Primary cultures of liver cells isolated from adult rats by trypsin and collagenase perfusion techniques were carried out to compare cytologic and biochemical properties between the differently prepared cells. Trypsin-dispersed cells consisted of comparatively smaller cells, whereas collagenase-dispersed cells consisted of larger cells. The cell attachment efficiency on culture day 1 was about twice as high in the liver cells prepared with collagenase than those prepared with trypsin. Mature hepatocytes isolated by collagenase perfusion could be maintained in the primary culture for a longer period than those isolated by trypsin perfusion. Epithelial-like clear cells started to grow much earlier in the primary culture of the trypsin-dispersed liver cells than in that of the collagenase-dispersed liver cells. Earlier proliferation of epithelial-like clear cells could not be induced by in vitro trypsinization of the collagenase-dispersed liver cells. Both kinds of enzymatically prepared liver cells showed albumin production and exhibited glucose 6-phosphatase (D-glucose-6-phosphate phosphohydrolase, EC 3.1.3.9, G6Pase) and tyrosine aminotransferase (L-tyrosine: 2-oxoglutarate amino-transferase, EC 2.6.1.5, TAT) activities for 1 week in the primary culture. Albumin production was higher in the liver cells prepared with collagenase than those prepared with trypsin, whereas G6Pase activity was almost the same between them. TAT activity up to culture day 2 was about 3-fold higher in the liver cells prepared with collagenase than in those prepared with trypsin. Combined supplementation of dexamethasone (1 X 10(-5)M) and insulin (10 micrograms/ml) consistently improved the cell attachment efficiency and was very effective in the maintenance of mature hepatocytes in both types. Furthermore, these hormones enhanced the albumin production and TAT activity in both types.

Albumins↗
PubMed1984

Intra-arterial administration of heated albumin microspheres containing mitomycin C to rabbits with VX-2 tumor.

In an attempt to enhance antitumor effects, we prepared heated albumin microspheres containing mitomycin C (MMC). These MMC microspheres have an average diameter of 45 +/- 8 micrometers and contain about 5 per cent of MMC. The intra-arterial MMC microsphere treatment, for albino rabbits with implanted VX-2 tumor, increased remarkably the tissue MMC levels, compared to that with conventional MMC, and resulted in conspicuous antitumor efficacy. This approach to antitumor chemotherapy should be effective for selected patients with malignant tumor receiving a blood supply from an end-artery.

Animals↗
PubMed1984

Amosulalol, a combined alpha and beta adrenoceptor antagonist: kinetics after intravenous and oral doses.

Amosulalol kinetic studies were conducted in seven subjects who received 0.16 mg/kg iv and in 18 subjects who received 12.5, 25, 50, 100, or 150 mg by mouth. Plasma levels of amosulalol after intravenous dosing declined biphasically and fitted a two-compartment model. Kinetics were as follows: coefficients A = 0.85 +/- 0.09 microgram/ml and B = 0.22 +/- 0.01 microgram/ml; rate constants alpha = 2.78 +/- 0.24 hr-1 and beta = 0.25 +/- 0.01 hr-1; elimination rate constants, k12 = 1.36 +/- 0.17 hr-1, k21 = 0.78 +/- 0.06 hr-1, and kel = 0.88 +/- 0.06 hr-1; terminal phase volume of distribution = 0.75 +/- 0.06 l/kg; clearance = 8.09 +/- 0.54 l/hr; AUC = 1.22 +/- 0.09 microgram . hr/ml; and t1/2 alpha = 0.26 +/- 0.02 hr and t1/2 beta = 2.8 +/- 0.1 hr. After single oral doses, amosulalol peak plasma levels were generally reached within 2 to 4 hr. Maximum plasma concentrations and AUC increased in a dose-dependent manner, whereas t1/2 were about 5 hr (range 4.4 to 5.7 hr) at each dose. Systemic availability of amosulalol was about 100% as determined by the ratio of AUC after oral and intravenous dosing. These results suggest that amosulalol is well absorbed and is little affected by first-pass metabolism.

Administration, Oral↗
PubMed1984

Vascular angiotensin-converting enzyme activity in man and other species.

Angiotensin-converting enzyme (ACE) activity in blood vessels of different species was determined. ACE was solubilized by Nonidet P-40, and assayed by reversible phase high performance liquid chromatography. Approximately 98% ACE was recovered in the liquid phase by the use of the detergent. The ACE activity varied with chloride ion (Cl-) concentrations; the maximum activities in dog, human, monkey and rabbit tissues were obtained at the concentrations of 800, 600, 600 and 300 mmol/l respectively. The optimal Cl- concentration was quite similar in different tissues and plasma obtained from the same species. The ACE activity in the cerebral, mesenteric, pulmonary and renal arteries was in a range between 1.01 and 1.60 m-units/mg of protein in dogs and between 0.43 and 0.94 m-unit/mg of protein in monkeys. The activity in dog aortae was 0.20 +/- 0.02 m-unit/mg of protein, and the activity in aortic endothelial cells was 2.61 +/- 0.65 m-units/mg of protein. ACE activities in the dog lung, kidney cortex and cerebral cortex were 28.6 +/- 2.6, 15.7 +/- 3.0 and 3.5 +/- 0.6 m-units/mg of protein respectively. SA-446, a captopril-like ACE inhibitor, reduced the ACE activity in arteries in a dose-dependent manner. Vascular ACE appears to be concentrated in the endothelium and may contribute to regulate vascular muscle tone and local blood flow by a conversion of angiotensin I into II.

3-Mercaptopropionic Acid↗
PubMed1984

Responses of isolated dog arteries to amrinone.

Helically-cut strips of dog cerebral, coronary, mesenteric, renal and femoral arteries contracted with prostaglandin (PG) F2 alpha or K+ responded to amrinone (10(-5) to 10(-4) mol X litre-1) with relaxation, which was not influenced by treatment with propranolol, atropine, cimetidine, aminophylline or aspirin. The contractile response of mesenteric arteries to transmural electrical stimulation (2, 5 and 20 Hz) and noradrenaline was attenuated by amrinone (3 X 10(-5) and 10(-4) mol X litre-1); the attenuation of the response to nerve stimulation and noradrenaline did not significantly differ. Ca2+-induced contractions in mesenteric arteries exposed to Ca2+-free media and depolarised by excess K+ were inhibited by amrinone, and the inhibition could not be reversed by the addition of excess Ca2+. Treatment with amrinone potentiated the relaxant responses of mesenteric arteries to adenosine but did not alter the response to isoprenaline. Amrinone in concentrations sufficient to produce moderate and marked relaxation did not significantly alter the content of cyclic AMP in mesenteric arteries. Attenuation by amrinone of the contractile response to transmural stimulation, noradrenaline and Ca2+ and the relaxation of a variety of arteries induced by amrinone may not be due to interference with the transmembrane influx of Ca2+ and intracellular accumulation of cyclic AMP but to a nonspecific action on arterial smooth muscle. Amrinone appears to increase the metabolic vasodilatation by potentiating the vasodilator action of adenosine.

Adenosine↗
PubMed1984

Spontaneous resolution of chronic epidural hematomas: report of three cases.

We report three cases of the spontaneous resolution of a traumatic chronic epidural hematoma. The patients were young adults with only mild headache after trauma. All patients were treated conservatively because of the very mild symptoms and the time lapse of 1 to 2 weeks between trauma and our unexpected detection of the frontal epidural hematomas. Slow, spontaneous resolution of the hematoma occurred in all three cases.

Adult↗