Sei-ichi Nakamura

Bio: Sei-ichi Nakamura is an academic researcher from Kindai University. The author has contributed to research in topics: Furylfuramide & Ames test. The author has an hindex of 21, co-authored 52 publications receiving 1437 citations.

SOS-inducing activity of chemical carcinogens and mutagens in Salmonella typhimurium TA1535/pSK1002: examination with 151 chemicals.

Abstract: The umu test system is a newly developed method to evaluate genotoxic activities of a wide variety of environmental carcinogens and mutagens (Oda et al., 1985). In the present study, we further examined the abilities of 151 chemicals to induce umu gene expression in Salmonella typhimurium TA1535/pSK1002. Among the chemicals examined, 72 compounds induced umu gene expression, which could be defined on a basis of increased beta-galactosidase activity by 2-fold over the background level. The potent genotoxic compounds without metabolic activation were adriamycin, bleomycin, daunorubicin, 1,3-dinitropyrene, 1,6-dinitropyrene, 1,8-dinitropyrene, N-ethyl-N'-nitro-N-nitrosoguanidine, furylfuramide, methyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C, 1-nitropyrene and 4-nitroquino-line-1-oxide. In the presence of S9, aflatoxin B1, 2-aminoanthracene, Glu-P-1, IQ, MeIQ, MeIQx, Trp-P-1 and Trp-P-2 also induced umu gene expression markedly. Several chemicals such as 2-acetylaminofluorene, 9-aminoacridine, azobenzene, benzanthracene, benzidine, diethyl nitrosamine, 1-nitronaphthalene, paraquat, potassium dichromate and sodium nitrite were weakly genotoxic and the induction by these compounds could be detected only when the incubation time was prolonged from 2 h to 5 h. Data are also presented that some of the chemicals such as dimethyl sulfoxide, m-dioxan, 5-fluorouracil and paraquat, which have been reported to be non-mutagenic in Ames/Salmonella assay, were found to be active in inducing umu gene expression, while the known mutagenic compounds including acrylonitrile, 4,4'-dinitrobiphenyl, furfural, methylene chloride, 1-naphthylamine, sodium azide, o-tolidine and o-toluidine were non-genotoxic in the present assay system.

Antimutagenic effect of resveratrol against Trp-P-1.

Abstract: The methanol extract of Yucca schidigera (YE) showed a suppressive effect on umu gene expression of the SOS response induced by 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) in Salmonella typhimurium TA1535/pSK1002. The suppressive effect of YE was also observed for 2-aminoanthracene and activated Trp-P-1, without a significant effect on bacterial growth. The extract exhibited a weak suppressive effect on SOS-induction by N-methyl-N'-nitro-N-nitrosoguanidine, but not by furylfuramide or 4-nitroquinoline-1-oxide. The antimutagenic activity of YE against Trp-P-1 was demonstrated by Ames assay using Salmonella typhimurium TA98. Isolation and purification of the active component of YE was carried out using SiO2 column chromatography, and 275 mg of antimutagenic compound was isolated from 2.5 kg of dried chips of yucca roots and branches. The compound was identified as 3,4',5-trihydroxystilbene (THS). The SOS suppression and antimutagenicity of THS against Trp-P-1 was determined by umu test and Ames test.

Antimutagenic activity of flavonoids from Pogostemon cablin.

Abstract: A methanol extract from Pogostemon cablin showed a suppressive effect on umu gene expression of SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract was re-extracted with hexane, dichloromethane, butanol, and water. A dichloromethane fraction showed a suppressive effect. Suppressive compounds against furylfuramide in the dichloromethane fraction were isolated by SiO(2) column chromatography and identified as 7,4'-di-O-methyleriodictyol (1), 7, 3',4'-tri-O-methyleriodictyol (2), and 3,7,4'-tri-O-methylkaempferol (3). In addition, three flavonoids, ombuine (4), pachypodol (5), and kumatakenin (6), were isolated and identified from the dichrolomethane fraction. Compounds 1 and 3 suppressed >50% of the SOS-inducing activity at 80% of the SOS-inducing activity of Trp-P-1 at <0.06 micromol/mL, and compounds 1 and 2 suppressed 87 and 63% at a concentration of 0.3 micromol/mL. In addition, these compounds were assayed with activated Trp-P-1, and the suppressed effects of these compounds were further decreased when compared to Trp-P-1. The antimutagenic activities of these compounds against furylfuramide, Trp-P-1, and activated Trp-P-1 were assayed by the Ames test using S. typhimurium TA100.

Antimutagenic activity of isoflavone from Pueraria lobata.

Abstract: A methanol extract from Pueraria lobata showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract from P. lobata was re-extracted with hexane, dichloromethane, ethyl acetate, butanol, and water, respectively. A suppressive compound in the dichloromethane and ethyl acetate extract fractions was isolated by SiO(2) column chromatography and identified as tectorigenin (1) by EI-MS and (1)H and (13)C NMR spectroscopy. Compound 1 and its methylated derivative [7,4'-di-O-methyltectorigenin (2)] had the suppressive effects on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against furylfuramide, 4-nitroquinoline-1-oxide, N-methyl-N'-nitrosoguanidine, and activated Trp-P-1, which do not require live metabolic activation by S9. These compounds also showed suppression of SOS-inducing activity against Trp-P-1 and AfB(1), which requires liver metabolizing enzymes. In addition to the antimutagenic activities of these compounds against furylfuramide, Trp-P-1 and activated Trp-P-1 were also assayed by an Ames test using S. typhimurium TA100.

Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry

Abstract: The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.

Role of Resveratrol in Prevention and Therapy of Cancer: Preclinical and Clinical Studies

Abstract: Resveratrol, trans-3,5,4'-trihydroxystilbene, was first isolated in 1940 as a constituent of the roots of white hellebore (Veratrum grandiflorum O. Loes), but has since been found in various plants, including grapes, berries and peanuts. Besides cardioprotective effects, resveratrol exhibits anticancer properties, as suggested by its ability to suppress proliferation of a wide variety of tumor cells, including lymphoid and myeloid cancers; multiple myeloma; cancers of the breast, prostate, stomach, colon, pancreas, and thyroid; melanoma; head and neck squamous cell carcinoma; ovarian carcinoma; and cervical carcinoma. The growth-inhibitory effects of resveratrol are mediated through cell-cycle arrest; upregulation of p21Cip1/WAF1, p53 and Bax; down-regulation of survivin, cyclin D1, cyclin E, Bcl-2, Bcl-xL and clAPs; and activation of caspases. Resveratrol has been shown to suppress the activation of several transcription factors, including NF-kappaB, AP-1 and Egr-1; to inhibit protein kinases including IkappaBalpha kinase, JNK, MAPK, Akt, PKC, PKD and casein kinase II; and to down-regulate products of genes such as COX-2, 5-LOX, VEGF, IL-1, IL-6, IL-8, AR and PSA. These activities account for the suppression of angiogenesis by this stilbene. Resveratrol also has been shown to potentiate the apoptotic effects of cytokines (e.g., TRAIL), chemotherapeutic agents and gamma-radiation. Phamacokinetic studies revealed that the target organs of resveratrol are liver and kidney, where it is concentrated after absorption and is mainly converted to a sulfated form and a glucuronide conjugate. In vivo, resveratrol blocks the multistep process of carcinogenesis at various stages: it blocks carcinogen activation by inhibiting aryl hydrocarbon-induced CYP1A1 expression and activity, and suppresses tumor initiation, promotion and progression. Besides chemopreventive effects, resveratrol appears to exhibit therapeutic effects against cancer. Limited data in humans have revealed that resveratrol is pharmacologically quite safe. Currently, structural analogues of resveratrol with improved bioavailability are being pursued as potential therapeutic agents for cancer.

Cytokines and the brain: implications for clinical psychiatry.

Abstract: OBJECTIVE: This article reviews recent developments in cytokine biology that are relevant to clinical psychiatry.METHOD: The authors reviewed English-language literature of the last 15 years that pertains to the biology of cytokines with emphasis on central nervous system effects in general and psychiatric disorders in particular.RESULTS: Growing evidence suggests that, in addition to providing communication between immune cells, specific cytokines play a role in signaling the brain to produce neurochemical, neuroendocrine, neuroimmune, and behavioral changes. This signaling may be part of a generalized, comprehensive mechanism to mobilize resources in the face of physical and/or psychological stress and to maintain homeostasis. The clinical implications of these findings are far-reaching and include a possible role for cytokines in the pathophysiology of specific psychiatric disorders such as major depression, schizophrenia, and Alzheimer’s disease. The effects of cytokines in the central nervous system ...