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Biomedical subjects

H Mizuno

Publications and source records attributed to H Mizuno.

At least 235 records · Page 13Linked to original sources
PubMed1989

[Effects of flutropium bromide, a new antiasthma drug, with repeated administration on bronchomotor response and hepatic drug metabolizing enzymes].

Effects of flutropium bromide, a new antiasthma drug possessing the quarternary ammonium structure of atropine derivatives, were investigated on the bronchodilatory activity with repeated inhalations in guinea pigs and on the hepatic drug metabolizing enzyme activities with repeated i.v. administration in rats. Single inhalation of flutropium bromide (0.03%) inhibited the ACh-induced bronchoconstriction without changing the fall in blood pressure induced by ACh. Flutropium bromide (0.03%) was inhaled for 5 min a day by placing the animal in an inhalation box, successively during periods of 14 and 28 days. The bronchodilatory effect of flutropium bromide after 14- or 28-day repeated inhalations was almost the same potency as that after single inhalation. Twenty-eight-day repeated inhalations did not change the body weight curve in guinea pigs; and in addition, 14-day repeated i.v. administration did not change the hepatic drug metabolizing enzyme activities in rats. From the above results, it is indicated that flutropium bromide causes neither reduction in response nor cumulative effect after repeated inhalations, and that the agent maintains the bronchodilatory effect without change in the hepatic drug metabolizing enzyme activities.

Acetylcholine↗
PubMed1989

[A case of right atrial myxoma with successful removal].

The incidence of primary cardiac tumors is very rare. However, the number of reported cases has recently increased due to the widespread use of echocardiography. This patient was a 67-year-old male whose main complaint was dizziness on standing. Right atrial myxoma was diagnosed by two-dimensional echocardiogram. Because of persistent right heart failure, open heart surgery was performed as a sub-emergency procedure. The myxoma was removed successfully and its weight was 93 g. The site of origin of the tumor was the lateral wall of the right atrium close to the entrance of the inferior vena cava.

Aged↗
PubMed1988

NH2-terminal processing of Bacillus subtilis alpha-amylase.

Mature alpha-amylase of Bacillus subtilis is known to be formed from its precursor by removal of the NH2-terminal 41-amino acid sequence. To study the mechanism of this processing, the extracellular forms of alpha-amylase were analyzed for B. subtilis N7 alpha-amylase cloned and expressed in B. subtilis. The major form (form N34) isolated from log phase cultures in L-broth had an NH2 terminus corresponding to position 34 from the initiator Met but appeared to be microheterogeneous, as judged by native gel electrophoresis. The major forms from stationary phase cultures had NH2 termini at positions 40 (form N40) or 42 (form N42) and were homogeneous. The conversion of the larger to smaller forms could be achieved in culture supernatants or partially purified samples. The process N34----N40 was inhibited by EDTA; N40----N42 was facilitated by Ca2+. Phenylmethylsulfonyl fluoride inhibited the former but not the latter process. These results suggest that the signal peptidase cleavage site 30 decreases 35 is -Ala-Ala-Ala-Ser-Ala-Glu-Thr- (arrow or further upstream) and that proteolytic maturation occurs after secretion, which involves at least two different processing enzymes.

Amino Acid Sequence↗
PubMed1988

[Effects of flutropium bromide, a new antiasthma drug, on mediator release from mast cells and actions of mediators].

The effects of flutropium bromide (Ba598Br), a new antiasthma drug possessing the quarternary ammonium structure of atropine derivatives, on mediator release from mast cells and on actions of leukotriene (LT) D4 and serotonin were investigated. Flutropium bromide (3 and 10 mg/kg, i.v.) showed an inhibitory action on the 48 hr homologous PCA in guinea pigs. Atropine showed no inhibitory effect. Flutropium bromide also inhibited the release of histamine from isolated rat mast cells stimulated by antigen, although the inhibitory action was weaker than that of disodium cromoglycate. Atropine also had no inhibitory action in this case. Flutropium bromide and atropine showed no antagonistic action against LTD4-induced contraction of isolated tracheal smooth muscle of guinea pigs. Inhalation of flutropium bromide (0.3%) also showed no antagonistic action against serotonin-induced bronchoconstriction in dogs. From the above results, it is indicated that flutropium bromide has a weak mast cell stabilizing action, but no antagonistic action against LTD4 and serotonin.

Animals↗
PubMed1988

Cardiovascular pharmacology of RS-1893, an orally active cardiotonic agent with arterial and venous vasodilator actions.

RS-1893, 2-[2-chloro-4-(2,3,4,5-tetrahydro-3-oxo-6-pyridazinyl)]-phenoxy-N- (2-(2-morpholinoethyl)-acetamide, is a newly synthesized compound whose structure is different from that of cardiac glycosides and beta-stimulants. The in vitro cardiotonic action of RS-1893 was about 3 times more potent than that of milrinone. This action is most likely due to inhibition of phosphodiesterase-III, as has been suggested for many other cardiotonic agents. In pentobarbital anesthetized dogs, RS-1893 (1-30 micrograms/kg, i.v.) produced dose dependent increases in left ventricular dP/dtmax and cardiac output and caused decreases in blood pressure and total peripheral resistance with a relatively small increase in heart rate. Central venous pressure decreased markedly, suggesting venous vasodilation. The in vivo cardiotonic action of RS-1893 was 3 times more potent than that of milrinone and was not affected in the presence of a large dose of propranolol. Oral administration of RS-1893 (0.03 and 0.1 mg/kg) also produced a dose-related increase in cardiac contractility in conscious beagles. The increase in LVdP/dtmax reached a maximum in 1-3 hr after administration and lasted for more than 8 hr. Thus, RS-1893 appeared to be an orally active cardiotonic agent with vasodilator properties, probably acting on both arterioles and veins.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

[Effect of platonin on bone wound healing in rat calvaria--with special reference to the interaction of platonin and steroid hormones].

Interaction of Platonin (PI) and dexamethasone (DM) or testosterone propionate (TP) on bone wound healing was studied by measuring the areas of wound holes which were made in the rat parietal bone. The result was compared with that of the growth of the femur. 1) No significant difference was observed between the control group and pl groups (1, 10 and 100 micrograms/kg, s.c., for 4 weeks) on the wound hole area or the length, weight, calcium content (Ca) or hydroxyproline content (HP) in the femur. 2) The bone wound healing was delayed by DM (2 mg/kg, s.c., for the first 2 weeks). The inhibition of growth was also observed in the femur length and weight, but no significant effect of DM was observed in the Ca and HP of the femur. The combination of Pl and DM promoted the recovery from delayed bone wound healing and femur weight gain caused by DM. 3) No significant effects of TP (4 mg/kg, s.c., for the first 2 weeks) were observed on the wound healing and the femur growth, but an increase of the femur weight and Ca was observed by the combination of Pl and TP. These results indicate that Pl promotes the recovery from delayed bone wound healing and femur weight gain by DM, although no significant effects were observed in bone growth and bone wound healing by the administration of Pl alone. It is also suggested that a combination of Pl and TP promotes bone growth and mineralization.

Animals↗
PubMed1987

Effects of combined treatment with nimustine hydrochloride and radiation on solid FM3A tumor in mice.

Female C3H/HeN mice bearing solid FM3A tumors were treated with a combination of ACNU (or Nimustine hydrochloride) and radiation in order to investigate the antitumor effects and also to determine the optimal treatment schedule of ACNU in such combined therapy. ACNU was intravenously injected either twice with an interval of 2 weeks and a dose of 30 mg/kg (intermittent large-dose treatment), or as 4 weekly doses of 15 mg/kg (fractionated small-dose treatment). Local irradiation (5 Gy) at the tumor site was performed twice with an interval of 2 weeks between the doses. Synergistic effects were obtained by the combination of ACNU and radiotherapy in terms of tumor growth inhibition and prolongation of survival. Histology also revealed much greater reduction of viable tumor cells in the case of combination treatment. With either treatment with ACNU alone or in combination with irradiation, the intermittent large-dose injections resulted in better inhibition of tumor growth than did the fractionated small-dose injections, but the survival times with the intermittent treatments were not as prolonged as would be expected from the direct effects. Loss of body weight and depression of WBC number were also much more severe in the intermittent treatment group. Thus, it may be concluded that when ACNU is combined with radiotherapy, the intermittent large-dose regimen is not necessarily superior to the fractionated small-dose one.

Animals↗
PubMed1987

Protective effect of nimustine hydrochloride against radiation-induced pulmonary injury in mice.

Female C3H/HeN mice were irradiated in the thorax at a dose ranging from 10 to 25 Gy with or without ACNU (nimustine hydrochloride) treatment in order to determine whether the chemotherapeutic agent would lead to an enhancement of radiation-induced lung damage. ACNU given intravenously at 15 mg/kg immediately prior to irradiation reduced the mortality of mice irradiated with a low dose; mortality with either radiation alone or radiation plus ACNU was 4/10 (40%) or 0/10 (0%) at 13.1 Gy, and 9/10 (90%) or 6/10 (60%) at 15 Gy, respectively. The presence of ACNU during thoracic irradiation also prolonged the survival time of mice approximately 2-fold over that of animals given radiation alone. Histological examination of mice sacrificed 80 days after treatments revealed that the combination of drug and irradiation produced no radiation pneumonitis, which was predominant in mice given radiation alone. It is unexpectedly concluded that ACNU may have a protective effect against radiation-induced lung injury.

Animals↗
PubMed1986

Conformations of cyclo(L-orD-Phe-L-Pro-Aca) and cyclo(L-Pro-L- or D-Phe-Aca). Cyclized dipeptide models for specific types of beta-bends.

Conformational analyses on four cyclic model peptides of the beta-bend, cyclo(L- or D-Phe-L-Pro-epsilon-aminocaproyl(Aca] and cyclo(L-Pro-L- or D-Phe-Aca), were carried out both experimentally and theoretically. Cyclo(D-Phe-L-Pro-Aca) was shown to exist as a single conformer taking the type II' beta-bend. The comparison of its CD spectra with those of cyclo(L-Ala-L-Ala-Aca) revealed that type I and II' beta-bends, both with alpha-helix-like CD spectra, can be distinguished. Cyclo(L-Phe-L-Pro-Aca) was shown to exist as a single conformer with a cis L-Phe-L-Pro peptide bond, taking the type VI beta-bend. Its CD spectrum has thus been observed for the first time for the bend containing a cis peptide bond. Cyclo(L-Pro-L-Phe-Aca) was shown to exist as a mixture of two conformers, the major one taking the type I beta-bend with a trans Aca-L-Pro peptide bond and the minor one with a cis Aca-L-Pro peptide bond. Cyclo(L-Pro-D-Phe-Aca) was suggested to exist as a mixture of two conformers, the major one taking the type II beta-bend with a trans Aca-L-Pro peptide bond and the minor one with a cis Aca-L-Pro peptide bond.

Dipeptides↗