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Biomedical subjects

Y Ohkawa

Publications and source records attributed to Y Ohkawa.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effects of sorbic acid and its salts on chromosome aberrations, sister chromatid exchanges and gene mutations in cultured Chinese hamster cells.

The ability of sorbic acid and its potassium and sodium salts to induce chromosome aberrations, sister chromatid exchanges (SCE) and gene mutations in cultured Chinese hamster V79 cells was examined. Sodium sorbate caused significant induction of chromosome aberrations and SCE, and also induced 6-thioguanine-resistant mutations in a dose-dependent manner. The clastogenic potency of sodium sorbate was found to be less than one hundredth of that of the potent clastogen N-methyl-N'-nitro-N-nitrosoguanidine. The induction of SCE by sodium sorbate was twice the control level, whereas that by methyl methanesulphonate, a potent inducer of SCE, was 14 times the control level. The mutagenic potency of sodium sorbate was less than one-tenth that of ethyl methanesulphonate, a potent inducer of mutation, when compared at an equitoxic level. Sorbic acid and its potassium salt induced chromosome aberrations, but only at the highest doses tested. These compounds also induced 1.2 times the control level of SCE, but neither compound induced 6-thioguanine-resistant mutations. The cytogenetic activity of sodium sorbate was concluded not to be due to the effect of osmotic pressure or an impurity. These results indicate that sodium sorbate is a genotoxic agent, although its potency seems to be weak, and that sorbic acid and potassium sorbate are less genotoxic than the sodium salt.

Animals↗
PubMed1984

A rapid, simple screening method for skin-tumor promoters using mouse peritoneal macrophages in vitro.

The enhancing effects in vitro of a potent skin-tumor promoter, phorbol myristate acetate (PMA), and its derivatives on nitroblue tetrazolium (NBT) reduction, phagocytosis and cell spreading of mouse peritoneal macrophages were compared. The enhancing effects on these markers of macrophage function, especially NBT reduction, were found to correlate well with the skin-tumor promoting activities of the phorbol esters. Another potent promoter, teleocidin, strongly enhanced NBT reduction, although teleocidin is structurally different from phorbol esters. Other tumor promoters, namely saccharin, phenobarbital, cantharidin and Tween 60 did not enhance NBT reduction by macrophages. These data indicate that this test system is appropriate for screening of PMA-type tumor promoters such as phorbol esters and teleocidin.

Animals↗
PubMed1984

Chromosomal aberrations in V79 cells induced by superoxide radical generated by the hypoxanthine-xanthine oxidase system.

The effect of the superoxide radical, generated by the hypoxanthine-xanthine oxidase system, on chromosomal mutation was examined in Chinese hamster V79 cells. When cells were treated with this system for 1 h in Hanks' solution, the incidence of metaphases with chromosomal aberrations was increased with hypoxanthine at concentrations of 2.5 to 10 micrograms/ml. On the other hand, in Eagle's minimum essential medium (MEM) or MEM supplemented with 10% fetal bovine serum, only hypoxanthine at 5 micrograms/ml plus xanthine oxidase induced chromosomal aberrations and higher concentrations of hypoxanthine were cytotoxic to V79 cells. The increased frequency of chromosomal aberrations and the cytotoxicity of hypoxanthine plus xanthine oxidase were not affected by superoxide dismutase, but were strongly inhibited by catalase.

Animals↗
PubMed1984

Comparison of 6-thioguanine-resistant mutation and sister chromatid exchanges in Chinese hamster V79 cells with forty chemical and physical agents.

The induction of sister chromatid exchanges (SCE) and mutation at the hypoxanthine-guanine phosphoribosyl transferase locus and toxicities of 40 different chemical and physical agents were examined on Chinese hamster V79 cells. These agents included mono-, di-, tri-, and polyfunctional alkylating agents, intercalators, gamma-rays, and UV light irradiation. Mutation was measured as resistance to 6-thioguanine and toxicity as loss of cell-plating efficiency. SCE were examined 29 hr after treatment. With the agents examined, a highly positive correlation (r = 0.89) existed between SCE-inducing and mutagenic potencies, when expressed as increase in the number per a unit dose over the control values. But the great difference of the ratios of mutagenic potencies versus SCE-inducing potencies among agents was observed, the maximal difference in the ratios being about 200-fold. The agents that showed the higher values of the ratio (agents producing more mutations than SCE) were bleomycin, cobalt-60 gamma-rays, all ethylating agents (N-ethyl-N-nitrosourea, N-ethyl-N'-nitro-N-nitrosoguanidine, ethyl methanesulfonate, and diethylsulfate), N-propyl-N-nitrosourea, N-butyl-N-nitrosourea, isopropyl methanesulfonate, intercalating acridine compounds (2-methoxy-6-chloro-9-[3-(ethyl-2-chloroethyl)aminopropylamino]-acridine X 2HCl and 2-methoxy-6-chloro-9-[3-(chloroethyl)-aminopropylamino]acridine 2HCl) and UV light at 254 nm. The agents that showed the lower values (agents producing more SCE than mutations) were platinum compounds (cis-diamminedichloro-platinum and trans-diamminedichloroplatinum), epoxides (epichlorohydrin, styrene oxide, and diepoxybutane) and aziridines (mitomycin C, decarbamoyl mitomycin C, tris(1-aziridinyl)phosphine sulfide, triethylenemelamine, and carboquone). The agents that showed the intermediate values included all methylating agents (N-methyl-N-nitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine, methyl methanesulfonate, and dimethyl sulfate), N-(2-hydroxyethyl)ethyleneimine, beta-propiolactone, treatment of 8-methoxypsoralen plus near-UV light irradiation at 352 nm, 4-nitroquinoline-1-oxide, quinacrine mustard, sodium sorbate, cigarette tar, and diesel tar. For most agents that induced SCE, the toxicity dependency of induced SCE was rather biphasic; increase in SCE was steep at low to moderate toxicity and less at moderate to high toxicity. At equitoxic doses, the agents showed great difference in induction of SCE.

Animals↗
PubMed1981

Surgical treatment of anomalous origin of the left coronary artery from the pulmonary artery associated with tetralogy of Fallot.

An 8-year-old boy with anomalous origin of the left coronary artery from the pulmonary artery associated with tetralogy of Fallot, which was definitely diagnosed preoperatively, was operated on with success. Direct implantation of the left coronary artery into the aorta following division of the left coronary artery from the pulmonary artery and, concomitantly, total repair for tetralogy of Fallot using an external valved conduit were performed. Postoperative cineangiogram revealed a hemodynamically well-repaired intracardiac condition and anterograde filling of the left coronary artery, compared with retrograde left coronary flow from intercoronary collateral vessels preoperatively. To the best of our knowledge, there is not a previously published report of anomalous origin of the left coronary artery from the pulmonary artery associated with tetralogy of Fallot that was treated surgically with success.

Aortography↗
PubMed1978

Persistent left superior vena cava draining into the left atrium associated with the atrial septal defect and partial anomalous pulmonary venous drainage: surgical correction with sepcially designed prosthetic material.

Anomalous drainage of the persistent left superior vena cava into the left atrium with partial anomalous pulmonary venous return and the atrial septal defect is relatively rare condition, and there reported various kinds of surgical procedures in correction for this lesion. This report describes the original and simple surgical procedure in total correction of these lesions performed in our institute, using a large Dacron patch connected with a knitted Dacron vascular graft in its center. Surgical correction was accomplished by anastomosis of a Dacron draft with the orfice of the persistent left superior vena cava into the left atrium, widening of the atrial septal defect, and reconstruction of a new atrial septum with a Dacron patch. Postoperative cardiac evaluation revealed good condition of blood stream through a Dacron draft from the left superior vena cava to the right atrium, with corrected pulmonary venous drainage into the left atrium without pulmonary venous congestion and superior vena cava syndrome.

Blood Vessel Prosthesis↗