Publications by authors named "Kyoko Nabae"

Abstract The recent steep increase in the number of users of cellular phones is resulting in marked increase of exposure of humans to radiofrequency electromagnetic fields (EMFs). Children are of particular concern. Our goal was to evaluate potential adverse effects of long-term whole-body exposure to EMFs simulating those from base stations for cellular phone communication.

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Licorice flavonoid oil (LFO) is a new functional food ingredient consisting of hydrophobic licorice polyphenols in medium-chain triglycerides. Recently, it was reported that licorice and its derivatives have anticarcinogenic activity in some types of tumors. However, the anticarcinogenic activity has not been identified in the liver, which is a major target organ for carcinogenesis in human.

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The modifying potential of Agaricus blazei Murrill fruit-body extract (ABFE) on tumor development was investigated in a medium-term multi-organ carcinogenesis bioassay. Male 6-week-old F344 rats were treated with N-nitrosodiethylamine (DEN), N-methyl-N-nitrosourea (MNU), 1,2-dimethylhydrazine dihydrochloride (DMH), N-butyl-N-(hydroxybutyl)-nitrosamine (BBN), and diisopropanolnitrosamine (DHPN) for initiation (DMBDD treatment). After a 1-week withdrawal period, the animals received distilled water (vehicle control) or ABFE A, gamma-amino butyric acid (GABA) at 0.

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The present study was designed to evaluate whether gestational exposure to an EMF targeting the head region, similar to that from cellular phones, might affect embryogenesis in rats. A 1.95-GHz wide-band code division multiple access (W-CDMA) signal, which is one applied for the International Mobile Telecommunication 2000 (IMT-2000) system and used for the freedom of mobile multimedia access (FOMA), was employed for exposure to the heads of four groups of pregnant CD(SD) IGS rats (20 per group) for gestational days 7-17.

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A subchronic oral toxicity study of purple corn color (PCC), a natural food colorant, was performed with groups of 10 male and 10 female F344 rats fed the agent at dietary levels of 0%, 0.5%, 1.5% and 5.

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The modifying potential of diacylglycerol (DAG) oil on tumor development was investigated in a medium-term multi-organ carcinogenesis bioassay. DAG oil is a cooking oil that contains >80% diglycerides, <20% triglycerides and <5% monoglycerides. Male 6-week-old F344 rats (20 in each group) were sequentially treated with five carcinogens for initiation in different organ target sites for 4 weeks (DMBDD treatment), and then administered DAG oil at dietary levels of 0% (control), 1.

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Kojic acid (KA) has been widely used as a quasi-drug ingredient. Possible promotion activity of KA was suggested on livers of mouse and rat by findings obtained in genotoxicity and carcinogenicity studies performed thus far. Therefore, in order to examine safety as a quasi-drug ingredient, we investigated the presence of initiation activity in rat liver and the photo-genotoxicity and carcinogenicity in mouse skin.

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Chronic toxicity and carcinogenicity of hinokitiol (beta-thujaplicin), used as an antibiotic and fungicidal agent of a food additive, was examined in both sexes of F344/DuCrj (F344) rats. In this chronic toxicity study, groups of 10 rats of each sex were given a diet containing hinokitiol at doses of 0, 0.005, 0.

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F344 male rats were given five consecutive weekly subcutaneous injections of folic acid for induction of chronic renal dysfunction and then di(2-ethylhexyl)phthalate (DEHP) or di(2-ethylhexyl)adipate (DEHA) in the diet at a concentration of 0, 6000 or 25,000 ppm for 4 weeks in order to investigate whether male reproductive toxicity of the two chemicals might be enhanced under conditions of renal disease. Control animals also received DEHP or DEHA in the same manner but without folic acid pretreatment. Decreased testicular weights, seminiferous atrophy with vacuolization of sertoli cells and diminished sperm counts were more prominent in rats given folic acid and then 25,000 ppm DEHP as compared to those exposed to DEHP alone.

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Possible effects of 1439 MHz electromagnetic near field (EMF) exposure on the blood-brain barrier (BBB) were investigated using immature (4 weeks old) and young (10 weeks old) rats, equivalent in age to the time when the BBB development is completed and the young adult, respectively. Alteration of BBB related genes, such as those encoding p-glycoprotein, aquaporin-4, and claudin-5, was assessed at the protein and mRNA levels in the brain after local exposure of the head to EMF at 0, 2, and 6 W/kg specific energy absorption rates (SARs) for 90 min/day for 1 or 2 weeks. Although expression of the 3 genes was clearly decreased after administration of 1,3-dinitrobenzene (DNB) as a positive control, when compared with the control values, there were no pathologically relevant differences with the EMF at any exposure levels at either age.

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Modifying potential of annatto extract (norbixin) on liver carcinogenesis was investigated in male F344/DuCrj rats initially treated with N-nitrosodiethylamine (DEN). Two weeks after a single dose of DEN (200 mg/kg, intraperitoneally), rats were given annatto extract at dietary levels of 0, 0.03, 0.

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