Trace metals such as zinc, manganese, and iron are necessary for the growth and function of the brain. The transport of trace metals into the brain is strictly regulated by the brain barrier system, i.e., the blood-brain and blood-cerebrospinal fluid barriers. The alteration of homeostasis of trace metals in the brain is associated with brain diseases. Trace metals usually serve the function of metalloproteins in neurons and glial cells, while a portion of trace metals exists in the presynaptic vesicles and may be released with neurotransmitters into the synaptic cleft. Zinc and manganese influence the concentration of neurotransmitters in the synaptic cleft, probably via the action against neurotransmitter receptors and transporters and ion channels. Zinc may be an inhibitory neuromodulator of glutamate release in the hippocampus, while neuromodulation by manganese might have both functional and toxic aspects in the synapse. Dietary zinc deficiency affects zinc homeostasis in the brain, followed by an enhanced excitotoxicity of glutamate in the hippocampus. Transferrin may be involved in the physiologic transport of iron and manganese into the brain and their utilization there.
Oxidative stress derived from reactive oxygen species and/or heavy metal ions is believed to cause random damage to components in a living body, as well as aging and/or various disorders. A variety of systems that protect the living body from oxidative stress-induced damage are known; the present author elucidated three new defense systems against oxidative stress. Firstly, although it has been thought that lipid peroxidation in the living body promotes oxidative stress and increases the degree of oxidative damage, it was found that lipid peroxidation attenuated the DNA damage induced by such stress. This was determined by careful estimation of in situ lipid peroxidation. Secondly, red blood cells suffered from oxidative stress during their circulation, and membrane band 3 became aggregated and clustered so that anti-band 3 IgG and macrophages attached to it through sialylated poly-N-acctyllactosaminyl (PL) sugar chains. The PL sugar chain attachment to macrophages was stimulated by oxidative stress in the macrophages. Thirdly, the presence of oxidized protein hydrolase (OPH) that preferentially hydrolyzed proteins damaged by oxidative stress was found, and this enzyme may constitute a secondary defense system of the cells against such stress.
We evaluated the properties and real existence of an electrolyzed-reduced water, which we prepared, and three commercially purchased water goods, that are advertised to have antioxidant activities by the action of “active hydrogen,” on the basis of the results of examinations for inhibitory effects on the oxidative reactions of biomolecules, quantitative analyses of the minerals, and the ESR spectral data in measurement of the scavenging ability for reactive oxygen species. The results suggested that all of the examined aqueous solution systems undoubtedly have antioxidant activities in vitro and that such effects are derived from ordinary molecular hydrogen (hydrogen gas) and/or (a) reductive vanadium ion(s). “Active hydrogen” seems to be absent as an effective component of the antioxidant activities of these aqueous solution systems.
Liver disease has been increased in proportion to the rise of alcohol and fat consumption. The purpose of this study was to investigate the effects of Natural Product Extract (NPE; Astragalus membranaceus + Salvia miltiorrhiza + Pueraria lobata) on fatty liver induced by alcohol diet. Male Sprague-Dawley rats fed with ethanol-containing diets for 6 weeks showed increase in hepatic lipids, indicating the onset of alcoholic fatty liver. NPE was orally administered (3 g/kg/day, 1 g/kg/day, 0.33 g/kg/day) for 4 weeks following alcohol withdrawal, results revealed reduction in alcohol-induced lipid accumulation and reversed fatty liver. This inhibition of fatty liver by NPE was indirectly accompanied by recovery of hepatic lipase activity. The activity of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly increased in alcohol fed group, and decreased in NPE treated group. We can conclude from our experiment, NPE can reduce the serum and hepatic contents of triglycerides and cholesterol, which can be used as a remedy for alcoholic fatty liver.
The protective effect of curcumin, a potent inducer of heat shock protein (Hsp) 70, against the acute toxicity produced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was studied in vivo in C57BL/6J mice. Curcumin reduced the loss of body weight gain produced by TCDD regardless of having no effect on hepatomegaly and thymic atrophy. Hsp70.1 mRNA levels in liver and intestine were unaffected or tended to be reduced by TCDD and/or curcumin treatment. Curcumin also had no effect on the induction of hepatic ethoxyresorufin O-deethylase activity by TCDD. These data suggest that curcumin exhibits a protective effect against some forms of dioxin toxicity by a mechanism(s) distinct from the increase in hepatic and intestinal Hsp70 and inhibition of arylhydrocarbon receptor activation.
The active component in wasabi leafstalk (Wasabia japonica MATSUM.), which has a stimulatory effect on bone calcification in mouse calvaria tissue culture in vitro, was purified. Wasabi leafstalk extract was obtained from a homogenate with 20% ethanol. The active component, which was found in ethanol extraction, was purified by gel filtration chromatography with HiLoad 26/80 Superdex 30 pg column and reversed-phase chromatography (RPC) on a resource 15 RPC 3 ml column. The result of ESI mass spectra of the purified active component showed that its material had a molecular weight of 158. The absorption spectra of the material gave the maximum absorption at a wavelength of 221 nm. The material in wasabi leafstalk extract differed from genistein and 17β-estradiol, which can stimulate bone calcification in vitro, and had a comparatively lower molecular weight. This study demonstrates that the material with a low molecular weight of 158 is an active component in wasabi leafstalk which stimulates bone calcification.
The effect of β-cryptoxanthin on bone components in the femoral tissues of aged rats was investigated. β-Cryptoxanthin was isolated from Satsuma mandarin (Citrus unshiu MARC.). β-Cryptoxanthin (5, 10, or 20 μg/100 g body weight) was orally administered once daily for 7 days to aged (50 week old) female rats. The administration of β-cryptoxanthin (10 or 20 μg/100 g body weight) caused a significant increase in calcium content, alkaline phosphatase activity and deoxyribonucleic acid (DNA) content in the femoral-diaphyseal and -metaphyseal tissues. Femoral-diaphyseal calcium content and alkaline phosphatase activity were significantly increased by the dose of 5 μg/100 g body weight. A significant increase in metaphyseal alkaline phosphatase activity was also seen with the dose of 5 μg β-cryptoxanthin/100 g body weight. Moreover, bone tissues were cultured for 48 hr in serum-free Dulbecco's modified Eagle's medium containing either vehicle or β-cryptoxanthin (10-7 or 10-6 M). The presence of β-cryptoxanthin (10-7 or 10-6 M) caused a significant increase in calcium content and alkaline phosphatase activity in the femoral-diaphyseal and -metaphyseal tissues obtained from aged (50 week old) female rats. These increases were completely abolished in the presence of cycloheximide (10-6 M), an inhibitor of protein synthesis. This study demonstrated that β-cryptoxanthin has an anabolic effect on bone components in aged female rats in vivo and in vitro.
Polycyclic aromatic hydrocarbons (PAHs) were analyzed in maternal blood and fetuses from Fischer 344 rats exposed to diesel exhaust (DE) during pregnancy, and in breast milk from rats exposed to DE during pregnancy and lactation using high performance liquid chromatography with fluorescence detection. Concentrations of phenanthrene (Phe), anthracene (Ant) and benz[a]anthracene (BaA) were significantly higher in maternal blood of the DE group than those of the control group. Concentration of Phe in fetuses of the DE group was significantly higher than those of the control group. Concentrations of fluorene, Ant, fluoranthene (Flu), pyrene (Pyr), BaA and chrysene (Chr) tended to be higher in fetuses of the DE group. The levels of Ant, Flu, Pyr and Chr in breast milk from the DE group were significantly higher than those of the control group. These results indicate that PAHs taken into mother rat by the inhalation of DE are transferred into fetuses via placenta and into breast milk. This is the first report to clarify the transportation of inhaled PAHs into fetuses and breast milk from mother rats.
The functional roles of phenylalanine at position 120 (Phe-120) in the oxidation of bunitrolol (BTL), debrisoquine (DB) and bufuralol (BF) by cytochrome P450 2D6 (CYP2D6) were examined using a yeast cell expression system (Saccharomyces cerevisiae AH-22 strain). The substitution of Phe-120 by alanine markedly increased the activities of enantiomeric BTL 4-hydroxylase and DB 4-hydroxylase, whereas it did not remarkably affect BF 1′′-hydroxylase activities. Kinetic studies revealed that the substitution of Phe-120 by alanine increased the Km and Vmax values for enantiomeric BTL 4-hydroxylation, but increased only the Vmax value for DB 4-hydroxylation without changing the Km value. Km and Vmax values for BF 1′′-hydroxylation were similar between the mutant and the wild-type. The dissociation constants of the mutant calculated from the binding spectra for BTL enantiomers were higher than those of the wild-type, suggesting that the substitution of Phe-120 by alanine decreased the affinity of CYP2D6 for BTL enantiomers. These results indicate that Phe-120 has an important role in the oxidation of substrates by CYP2D6.
The in vitro binding assay seems to be a useful first screening method for endocrine disrupting chemicals. The various methods have been developed and applied to the testing of chemicals. Although these assays should be applied to estrogen receptors (ER) of not only humans but also wildlife, a standardized system is yet to be established. Furthermore, a method for Xenopus ER is not yet developed. We previously expressed the ligand-binding domain (LBD) of quail ERα and ERβ as a fusion protein with glutathione S-transferase, and developed a competitive enzyme immunoassay for detecting the capacity of chemicals to bind ERs. It seems that this system is a powerful tool, since it needs no special equipment. In this report, we first produced ER-LBD protein of human, Xenopus and medaka as well as quail. Then, we established a competitive enzyme immunoassay for these ERs as a standardized method, and compared the species specificity of the ability of 4-nonylphenol and p-octylphenol to bind ERs. Although a significant difference was not detected among ERβ of human, quail and medaka, 4-nonylphenol and p-octylphenol exhibited the higher affinity for the medaka ERα than human ERα. These results indicate the species specificity of the capacity of chemicals to bind ERs.
Six full-length cDNAs encoding pig cytochrome P450 (CYP) enzymes, CYP1A1, CYP2A19, CYP2B22, CYP2C33v4, CYP2C49, and CYP2E1, were isolated and sequenced. The cDNA sequences of pig CYP1A1, CYP2A19, CYP2B22, CYP2C49, and CYP2E1 showed high similarity to human CYP1A1 (85.4%), CYP2A13 (88.6%), CYP2B6 (81.1%), CYP2C18 (85.3%), and CYP2E1 (82.5%), respectively, and pig CYP2C33v4 cDNA showed high similarity to rat CYP2C23 (79.2%). Reverse transcription-polymerase chain reaction (RT-PCR) assays revealed hepatic gene expression of all these pig CYP enzymes: the order of expression was CYP2C33v4 and CYP2E1 > CYP2C49 > CYP1A1 and CYP2A19 > CYP2B22. In the kidney, the CYP2C33v4 gene was expressed at the same level as in the liver, but the CYP1A1, CYP2A19, and CYP2B22 genes were expressed at lower levels than in the liver. Little renal gene expression of CYP2C49 and CYP2E1 was observed. We revealed for the first time the full-length cDNA sequences encoding pig CYP1A1 and five CYP enzymes belonging to the CYP2 gene family, thus making it possible to examine the gene expression levels of these CYP enzymes in pig tissues by RT-PCR.
To establish a highly sensitive and convenient reporter gene assay for aryl hydrocarbon receptor (AhR) ligands, the chimera plasmid xenobiotic responsible element-luciferase (XRE-Luc) containing an XRE, minimal SV40 promoter, and luciferase reporter gene, was first constructed. The XRE-Luc and the expression vector pRC/CMV containing a neomycin-resistant gene were transfected into a rat hepatic cell line, Kan-R2, and then KanR2-XL8 was selected as a cell clone, which showed the highest response to the induction of luciferase by aryl hydrocarbons, 3-methylcholanthlene (3-MC) and benzo[a]pyrene. Furthermore, AhR-regulated genes, CYP1A1 and CYP1B1, in KanR2-XL8 cells were also activated by 3-MC. In the present study, we established a hepatic cell line, KanR2-XL8, that is useful for screening of AhR ligands with two parameters, the activations of the transfected luciferase gene and the AhR-regulated genes in a host cell.
To clarify the degradation pathway of acrinol by light, isolation and identification of acrinol degradation products (ANDP) were attempted. A novel acrinol degradation product, ANDP-8, one of the ANDPs, was isolated by extraction with methanol from cloths dampened with acrinol solution, and purified by column chromatography on Diaion HP-10 and Sephadex LH-20. The structural elucidation of ANDP-8 was examined by infrared, 1H-NMR, 13C-NMR and electron impact ionization (EI)-mass spectra studies. From the spectroscopic data, the structure of ANDP-8 was determined to be 2-ethoxyl-6, 9-acridinediamine-5, 8-dione, that was found to be a novel degradation product of acrinol by light. Antimicrobial activities of ANDP-8 against Gram-positive bacteria were 10 to 100-fold higher than those of acrinol. ANDP-8 was also active against yeast and fungi. Nevertheless, acrinol did not show growth inhibition even at a concentration of 100 μg/ml.
ESR methods for detecting irradiated foods are used internationally. In the present study, an identification method for irradiated unboned meats, fish with bone, and shellfish were studied. These foods were found to give ESR signals that were specific for irradiated samples. The signals appeared to originate from hydroxyapatite, calcium carbonate, collagen, chitin, melanin, and/or other complex materials. The shape of the ESR spectra for irradiated samples can be complex and difficult to analyze. Each ESR spectrum in the present study had several peaks, some of which were not affected by the doses applied. Some peak intensities, however, did increase with increases in dose. Minimum detectable dose was approximately 1 to 0.5 kGy. These results indicate that the shape of the ESR spectrum depends on the sample components.
Toxicity studies using the nematode Caenorhabditis elegans (C. elegans) as a model organism have shown that perfluoro organic compounds have sub-lethal toxicity at the 10 pM-100 nM range on multi-generation assays. We examined the acute lethal toxicity and multi-generational sublethal toxicity (fecundity and reproduction) of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and salts of perfluoro-1-octansulfonic acid (PFOS) using 1.7% agar Nematode Growth Medium (NGM) plates. The fluorine compounds affected the fecundity of C. elegans at concentrations 105- to 108-fold lower than the median effective concentrations (EC50). In particular, worm abundance during the first generation did not differ significantly from controls, while in contrast, the number of worms in the fourth generation at 10 pM PFOS-tetraethylammonium (TEA) decreased significantly to about 50% of control (p < 0.01) and the number of eggs and worms in the fourth generation at 1 nM PFNA decreased significantly to about 30% of control (p < 0.01). However, no dose-response relationship was observed in this study. We confirmed that perfluoro organic compounds strongly disrupt fecundity in C. elegans.
TFIIS is a general transcription elongation factor that interacts with Elongin (SIII), a product of the tumor suppressor gene for the human hereditary disorder von Hippel-Lindau (VHL) disease. Here, we have studied the promoter region of the Xenopus general type TFIIS (XGTFIIS) gene using a luciferase assay. The previously cloned region 1600-bp upstream of the XGTFIIS gene was divided into 12 sequential deletion fragments, and each fragment was inserted into the pGL3-Basic vector, which was used as a reporter for a luciferase assay in the Xenopus cultured cell-line, XTC. Except for the proximal promoter region close to the transcription start sites, no positively or negatively regulating element was found for TFIIS gene expression within the 1600-bp upstream region of the XGTFIIS gene. Of the two previously identified transcription start sites, the one that is distal to the ATG codon was preferred over the proximal one.
Many researchers have found evidence of the estrogenic effects of phthalate esters (PEs), but the disruption mechanism is not fully elucidated. Once PEs are hydroxylated at the ring 4-position, the resulting compounds exhibit unequivocal binding affinity for human estrogen receptors. In this study, we first succeeded to demonstrate the generation of potent estrogenic metabolite from PEs. We used rat liver microsomes and dimethyl phthalate (DMP) as a representative for the metabolism of PEs. Among the metabolites detected by HPLC, one of them was consistent with an authentic compound, 4-hydroxylated DMP (DMP-4OH) on their HPLC profiles. Together with the UV (λmax = 257 nm) and MS (m/z 210) data, the metabolite was concluded to be DMP-4OH. We propose that this ring-hydroxylated metabolite could be a key active species in the endocrine disrupting processes of PEs.