Dietary patterns and risk of Parkinson's disease: a case-control study in Japan.

BACKGROUND: Nearly all epidemiologic studies examining the association between the risk of Parkinson's disease (PD) and diet have focused on single foods and specific nutrients. However, epidemiologic evidence for the association of dietary pattern with PD, namely the measurement of overall diet by considering the cumulative effects of nutrients is extremely limited. We conducted a hospital-based case-control study in Japan to examine the relationship between dietary patterns and the risk of PD. METHODS: Patients with PD diagnosed using the UK PD Society Brain Bank criteria (n = 249) and controls without neurodegenerative diseases (n = 368) were recruited. At the time of recruitment, dietary intake during the preceding 1 month was assessed using a validated, self-administered diet history questionnaire. Dietary patterns from 33 predefined food groups (energy-adjusted food g/day) were extracted by factor analysis. RESULTS: Three dietary patterns were identified: 'Healthy', 'Western' and 'Light meal' patterns. After adjustment for potential non-dietary confounding factors, the Healthy pattern, characterized by a high intake of vegetables, seaweed, pulses, mushrooms, fruits and fish, was inversely associated with the risk of PD with a border-line significance (P for trend = 0.06). Multivariate Odds ratio (95% confidence intervals) for PD in the highest quartile of the Healthy pattern was 0.54 (0.32-0.92) compared with the lowest quartile. No associations with PD were detected for the other two dietary patterns. CONCLUSION: In this case-control study in Japan, a dietary pattern consisting of high intakes of vegetables, fruits and fish may be associated with a decreased risk of PD.

Risk modification by CYP1A1 and GSTM1 polymorphisms in the association of cigarette smoking and systemic lupus erythematosus in a Japanese population.

OBJECTIVES: Exposure to reactive oxygen species (ROS) through cigarette smoking is thought to contribute to the development of systemic lupus erythematosus (SLE). Metabolic enzymes are involved in ROS production. The aim of this study was to evaluate the modifying effect of metabolic polymorphisms on the association of cigarette smoking with SLE risk in a Japanese population. METHODS: We investigated the relationship of the cytochrome P450 (CYP) 1A1 rs4646903 and glutathione S-transferase (GST) M1 deletion polymorphisms to SLE risk with attention to interaction with cigarette smoking among 151 SLE cases and 421 controls in female Japanese subjects. Unconditional logistic regression was used to compute the odds ratios (ORs) and their 95% confidence intervals (CIs), with adjustments for several covariates. RESULTS: Smokers with the CC genotype of CYP1A1 rs4646903 were significantly associated with increased risk of SLE (OR 9.72, 95% CI 2.73-34.6). Similarly, smokers with the combined CYP1A1 rs4646903/GSTM1 'at-risk' genotype were significantly associated with increased risk of SLE (OR 17.5, 95% CI 3.20-95.9). More than 60% of the excess risk for SLE in smokers with the CC genotype and smokers with the combined 'at-risk' genotype was due to an additive interaction. A lack of association of the GSTM1 genotypes with smoking was observed. CONCLUSIONS: Our results suggest that a combination of smoking and either the CYP1A1 rs4646903 genotype or the combined metabolic genotype plays an important role in SLE susceptibility in our Japanese population. Additional studies are warranted to confirm the metabolic polymorphism-smoking interaction suggested in the present study.

Dietary intake of antioxidant vitamins and risk of Parkinson's disease: a case-control study in Japan.

BACKGROUND: antioxidant vitamins are expected to protect cells from oxidative damage by neutralizing the effects of reactive oxygen species. However, epidemiological evidence regarding the associations between antioxidant vitamin intake and Parkinson's disease (PD) is limited and inconsistent. We investigated the relationship between dietary intake of selected antioxidant vitamins, vegetables and fruit and the risk of PD in Japan using data from a multicenter hospital-based case-control study. METHODS: included were 249 patients within 6 years of onset of PD. Controls were 368 inpatients and outpatients without a neurodegenerative disease. Information on dietary factors was collected using a validated self-administered diet history questionnaire. Adjustment was made for sex, age, region of residence, pack-years of smoking, years of education, body mass index, dietary intake of cholesterol, alcohol, total dairy products, and coffee and the dietary glycemic index. RESULTS: higher consumption of vitamin E and ß-carotene was significantly associated with a reduced risk of PD after adjustment for confounders under study: the adjusted odds ratio in the highest quartile was 0.45 (95% confidence interval [CI]: 0.25-0.79, P for trend = 0.009) for vitamin E and 0.56 (95% CI: 0.33-0.97, P for trend = 0.03) for ß-carotene. Stratified by sex, such inverse associations were significant only in women. No material relationships were shown between intake of vitamin C, α-carotene, cryptoxanthin, green and yellow vegetables, other vegetables, or fruit and the risk of PD. CONCLUSIONS: higher intake of vitamin E and ß-carotene may be associated with a decreased risk of PD.

Active and passive smoking and risk of Parkinson's disease.

OBJECTIVE: To assess the association between active and passive smoking and the risk of Parkinson's disease (PD), a case-control study with 249 PD patients and 369 controls was carried out in Japan. METHODS: Information on smoking was obtained through a self-administered questionnaire. Adjustment was made for age, sex, region of residence, educational level, and occupational exposure. RESULTS: Ever having smoked cigarettes was associated with a reduced risk of PD [adjusted odds ratio = 0.38; 95% confidence interval (CI): 0.24-0.59]. Risk for former smokers was intermediate between the high risk for never smokers and the low risk for current smokers. Adjusted odds ratios for former and current smokers were 0.51 (95% CI: 0.32-0.82) and 0.12 (95% CI: 0.05-0.26), respectively. There was an inverse dose-response gradient with pack-years smoked. No significant association was detected for passive smoking exposure. CONCLUSION: Our results appear to confirm data from previous epidemiological studies.

Metal ion and vitamin adsorption profiles of phosphate binder ion-exchange resins.

AIMS: To determine the metal ion and vitamin in vitro adsorption profile of sevelamer hydrochloride (sevelamer-HCl) and colestilan(INN)/colestimide(JAN), a novel ion-exchange resin being developed as a phosphate binder for end-stage renal disease (ESRD) patients undergoing hemodialysis, adsorption of metal ions (iron, cobalt, copper and zinc) and vitamins (B6, B12, C, K and folic acid) essential for hematopoiesis/blood coagulation was assessed. METHODS: Mixtures of each resin (colestilan or sevelamer-HCl, 4 mg/ml) and metal ions (Fe(III), Fe(II), Co(II), Cu(II), and Zn(II), 1 microg/ml) were adjusted to pH 1.2 or 6.8 and incubated at 37 degrees C for 1 hour. Metal ions in the recovered filtrate were detected by inductively coupled plasma optical emission spectrometry. In addition, the mixtures of each resin (4 mg/ml) and vitamins (B6, B12, C, K and folic acid, 0.5 - 250 microg/ml) were adjusted to pH 6.8 and incubated at 37 degrees C for 0.5 hour. The vitamin concentrations in the recovered filtrate were quantified by HPLC. RESULTS: Colestilan did not adsorb any metals tested at either pH level, whereas sevelamer-HCl adsorbed copper(II) and zinc(II) ion at pH 6.8 with adsorption ratios of 99% and 38%, respectively. Both resins showed almost complete adsorption of vitamin C, vitamin K, and folic acid, but weak adsorption of vitamin B6, and no adsorption of vitamin B12. CONCLUSIONS: The differing adsorption profiles for metal ions and vitamins between sevelamer-HCl and colestilan may be of importance for the individualized management of anemia and malnutrition in chronic hemodialysis patients receiving phosphate binding ion-exchange resins for the control of hyperphosphatemia.

A dose-escalation study of rituximab for treatment of systemic lupus erythematosus and Evans' syndrome: immunological analysis of B cells, T cells and cytokines.

OBJECTIVE: Accumulating evidence suggests that B-cell depletion therapy by rituximab may be effective for autoimmune disorders. However, an optimal dose of rituximab and a mechanism of its action remain to be established. We performed a dose-escalation study for treatment of Japanese patients with autoimmune diseases including eight with SLE and one with Evans' syndrome. METHODS: Rituximab was infused intravenously, weekly 4 times in a dose-escalating fashion at three different doses of 100, 250 or 375 mg/m(2) to three patients each. Immunological parameters were monitored at certain points until 12 months after the treatment. RESULTS: Rituximab was well tolerated and safe in these patients. Seven out of eight SLE patients and one with Evans' syndrome clinically responded completely or partially to the treatment. Four patients achieved long-term remission (18-30 months) without any additional treatment. In these patients, a significant decrease in circulating B cells continued for 6 months after the treatment. The mean fluorescence intensities of CD19, CD21, CD40 and BR3 on the residual B cells as well as the percentage of CD69+ CD4+ T cells decreased significantly. Serum TNF-alpha levels decreased significantly on day 2. The Th1/Th2 balance of CD4+ T cells gradually shifted towards a Th1 type by 6 months. CONCLUSION: In addition to B-cell depletion, modification of B-cell and T-cell phenotypes as well as cytokine profiles may be involved in the action of rituximab.

Association of polymorphisms in complement component C3 gene with susceptibility to systemic lupus erythematosus.

OBJECTIVE: Identification of the genes responsible for systemic lupus erythematosus (SLE). METHODS: All the exons and putative promoter regions of 53 candidate genes (TNFRSF6/Fas, TNFSF6/FasL, Fli1, TNFSF10/TRAIL, TNFSF12/TWEAK, Bcl-2, PTEN, FADD, TRADD, CDKN1A, TNFRSF1A/TNFR1, TNFRSF4/OX40, TNFSF4/OX40L, TNFSF5/CD40L, TNFSF13B/BAFF, ICOS, CTLA4, CD28, FYN, G2A, CR2, PTPRC/CD45, CD22, CD19, Lyn, PDCD1, PTPN6, TGFB1, TGFB2, TGFB3, TGFBR1, TGFBR2, TGFBR3, CD3Z, DNASE1, APCS, MERTK, C3, C1QA, C1QB, C1QG, C2, MBL2, IGHM, IL-2, IL-4, IL-10, IFNG, TNFA, MAN2A1, TNFRSF11A/RANK, TNFRSF11B/OPG, TNFSF11/OPGL) were screened for single nucleotide polymorphisms (SNPs) and their association with SLE was assessed by case-control studies. A total of 509 cases and 964 controls of Japanese descent were enrolled. RESULTS: A total of 316 SNPs was identified. When analysed in the Japanese population, the allele frequencies of T at rs7951 and G at rs2230201 of the C3 gene were 0.110 and 0.626, respectively, in SLE patients; significantly higher than the frequencies of 0.081 and 0.584, respectively, in controls [odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.05-1.86, P = 0.016 and OR=1.19, 95% CI = 1.01-1.41, P = 0.038, respectively]. The mean serum C3 level of carriers of the rs7951 T allele was significantly lower than that of non-carriers of the T allele in 87 SLE patients whose medical records were available (P = 0.0018). CONCLUSION: rs7951 T allele of the C3 gene was significantly associated with SLE, and decreased serum level of C3 seems to be correlated with this allele.

Breastfeeding and the risk of wheeze and asthma in Japanese infants: the Osaka Maternal and Child Health Study.

Epidemiological evidence for an effect of breastfeeding on asthma continues to be inconclusive. The present prospective study examined the relationship between breastfeeding and the risk of wheeze and asthma in Japanese infants. A birth cohort of 763 infants was followed. The first survey during pregnancy and the second survey between 2 and 9 months postpartum collected information on potential confounding factors. Data on breastfeeding, wheeze, and asthma were obtained from questionnaires in the third survey from 16 to 24 months postpartum. Adjustment was made for maternal age, maternal and paternal history of asthma, atopic eczema, and allergic rhinitis, indoor domestic pets (cats, dogs, birds, or hamsters), family income, maternal and paternal education, maternal smoking during pregnancy, baby's sex, baby's older siblings, household smoking in the same room as the infant, and time of delivery before the third survey. By the third survey, the cumulative incidence of wheeze and asthma was 22.1% and 4.3%, respectively. Neither exclusive breastfeeding for 4 months or more nor partial breastfeeding for 6 months or more were materially related to the risk of wheeze. No measurable association was observed between exclusive breastfeeding for 4 months or more and the risk of asthma. Partial breastfeeding for 6 months or more was inversely related to the risk of asthma although the adjusted odds ratio (OR) was not statistically significant. When infants were stratified according to whether there was a negative or positive allergic history in at least 1 parent, a nearly 40% and 60% decrease, respectively, in the ORs were found for exclusive and partial breastfeeding only in infants without a parental allergic history, although the ORs were not statistically significant. The present prospective study showed no statistically significant relationship between breastfeeding duration and the risk of wheeze or asthma in Japanese infants.

Cigarette smoking, CYP1A1 MspI and GSTM1 genotypes, and colorectal adenomas.

Cigarette smoking has been related to increased risk of colorectal adenomas, but the underlying mechanisms are unknown. Genetic polymorphisms are known for enzymes involved in the activation of polycyclic aromatic hydrocarbons and other tobacco-related carcinogens. Polycyclic aromatic hydrocarbons are activated by cytochrome P4501A1 (CYP1A1) and detoxified by glutathione S-transferases. We investigated the relation of CYP1A1 MspI and GSTM1 genotypes to the risk of colorectal adenomas with special reference to interaction with cigarette smoking among 205 cases of colorectal adenomas and 220 controls with normal total colonoscopy in a male Japanese population. Cigarette smoking was strongly associated with increased risk of colorectal adenomas. Overall, neither the CYP1A1 MspI genotype nor the GSTM1 genotype was related to colorectal adenomas. A significant trend for increased risk of colorectal adenomas associated with smoking was observed for each of the CYP1A1 MspI genotypes, and the increasing trends did not differ by MspI genotype. The positive association between smoking and colorectal adenomas did not vary much with GSTM1 genotypes. Among former and current smokers, adenoma risk did not differ according to the combination of CYP1A1 MspI and GSTM1 genotypes. CYP1A1 MspI and GSTM1 genotypes do not seem to modify the risk of colorectal adenomas associated with cigarette smoking.

Polymorphisms of human Ah receptor gene are not involved in lung cancer.

The Ah receptor (Ahr) is a ligand-dependent transcription factor that positively regulates inducible expression of the CYP1A1 gene. Based on the sequence information of the human Ahr and the intron-exon junctions of the mouse counterpart, an analysis of single-strand conformational polymorphism (SSCP) was carried out to detect subtle base differences in the coding region of the gene among individuals. We found that the Ahr protein has at least two forms of variants in a Japanese gene pool, and that these variants can be ascribed to one amino acid replacement of Arg by Lys at codon 554. The frequencies of Arg-coded and Lys-coded alleles were 0.57 and 0.43, respectively. We found, however, that this germ line polymorphism of the Ahr gene did not show a significant association with aryl hydrocarbon hydroxylase (AHH) inducibility nor with lung cancer incidence.

The relationship between CYP1A1 aryl hydrocarbon hydroxylase activity and lung cancer in a Japanese population.

Because aryl hydrocarbon hydroxylase (AHH) is considered to be responsible for the activation of benzo(a)pyrene and other polyaromatic hydrocarbons in cigarette smoke to carcinogens, it is important to examine CYP1A1 (AHH) activity in the determination of susceptibility to lung cancer. We investigated AHH activity in peripheral mitogen-treated lymphocytes in 108 lung cancer patients and 95 healthy control individuals. Non-induced AHH activity was detectable in all the samples. AHH inducibility (3-methylcholanthrene-induced/non-induced AHH activity) showed a very wide interindividual variation as well as non-induced AHH activity. No significant associations were found between adjusted AHH activity and histologic type of tumor among lung cancer patients. Adjusted AHH inducibility of genotype C [geometric mean and 95% confidence interval (CI); 15.56 and 11.69-20.71] in MspI polymorphism was significantly higher than those of the other two genotypes (P = 0.0001), while no significant difference was observed between genotypes A (4.76 and 3.82-5.93) and B (5.60 and 4.57-6.86). On the other hand, non-induced AHH activity of genotype Val/Val (0.121 and 0.082-0.178 pmol/min/10(6) cells) in isoleucine-valine (Ile-Val) polymorphism was significantly higher than those of genotypes Ile/Ile (0.042 and 0.034-0.052 pmol/min/10(6) cells) and Ile/Val (0.040 and 0.030-0.053 pmol/min/10(6) cells) (P < 0.0001). Even after controlling for age, cigarettes smoked per day and season of the year, high AHH inducibility (7.0 < versus 0 < < or = 3.0: OR and 95 %CI, 12.4 and 2.88-53.4) was an independent risk factor for lung cancer. The data indicate that high AHH inducibility may strongly associate with the susceptibility to lung carcinogenesis.

Metabolic gene polymorphism frequencies in control populations.

Using the International Project on Genetic Susceptibility to Environmental Carcinogens (GSEC) database containing information on over 15,000 control (noncancer) subjects, the allele and genotype frequencies for many of the more commonly studied metabolic genes (CYP1A1, CYP2E1, CYP2D6, GSTM1, GSTT1, NAT2, GSTP, and EPHX) in the human population were determined. Major and significant differences in these frequencies were observed between Caucasians (n = 12,525), Asians (n = 2,136), and Africans and African Americans (n = 996), and some, but much less, heterogeneity was observed within Caucasian populations from different countries. No differences in allele frequencies were seen by age, sex, or type of controls (hospital patients versus population controls). No examples of linkage disequilibrium between the different loci were detected based on comparison of observed and expected frequencies for combinations of specific alleles.

Immunohistochemically detected p53 and P-glycoprotein predict the response to chemotherapy in lung cancer.

While resistance to chemotherapy is a major problem in lung cancer treatment, there is no useful predictor of treatment response. We thus designed this study to determine the utility of p53 and P-glycoprotein expression in predicting the response to chemotherapy in patients with primary lung cancer, retrospectively. We evaluated transbronchial biopsy (TBB) specimens from 60 patients with lung cancer, who were previously untreated. Formalin-fixed, paraffin-embedded TBB specimens were immunostained using anti-p53 antibody (DO-1) and anti-P-glycoprotein antibody (JSB-1). The positivity of p53 was 63%, and that of P-glycoprotein was 17%. No correlation was observed between p53 and P-glycoprotein immunostaining. Positivity of p53 correlated significantly (P = 0.004) with a lack of response to chemotherapy in non-small cell lung cancer (NSCLC), but not in small cell lung cancer (SCLC). In contrast, positivity of P-glycoprotein was correlated with chemotherapy resistance in SCLC (P = 0.003), but not in NSCLC. Multiple logistic regression analysis revealed that positive immunostaining for p53 was a significant risk factor for chemotherapy resistance in NSCLC. These results suggest that immunostaining of p53 and P-glycoprotein for TBB specimens may help to predict response to chemotherapy in NSCLC and SCLC, although the results should be confirmed in a larger, more homogeneous series.

Methylenetetrahydrofolate reductase polymorphism and risk of colorectal adenomas.

A homozygous mutation at bp 677 in the gene for the methylenetetrahydrofolate reductase (MTHFR) was previously shown to be associated with a decreased risk of colorectal cancer. We examined the relation between the MTHFR genetic polymorphism and risk of colorectal adenoma in Japanese men using 205 cases of colorectal adenomas and 220 controls of normal total colonoscopy. The homozygous mutation was not measurably associated with colorectal adenomas. The findings corroborate the lack of an association between the MTHFR genotype and colorectal adenomas, but do not deny the possibility that the genotype may be involved in the late stage of colorectal carcinogenesis.

Apolipoprotein E genotype, serum lipids, and colorectal adenomas in Japanese men.

We examined the relation of serum lipids and apolipoprotein E genotype to colorectal adenomas among 205 cases and 220 controls with normal colonoscopy in Japanese men. With adjustment for body mass index, cigarette smoking, alcohol use, and other covaiates, odds ratios of proximal and distal adenomas associated with the presence of an allele varepsilon4 were 0.59 (95% confidence interval 0.23-1.45) and 0.99 (0.50-1.98), respectively. While serum total and LDL cholesterol were unrelated to both proximal and distal adenomas, serum triglycerides were positively related to distal adenomas. The findings suggest that altered lipid metabolism may be differentially associated with tumorigenesis in the proximal and distal colorectum.

Glutathione S-transferase polymorphisms and risk of colorectal adenomas.

Glutathione S-transferases (GSTs) are a superfamily of detoxification enzymes that may play an important role in human carcinogenesis. While the genetic polymorphisms GSTM1 and GSTT1 have drawn particular interest in relation to cancer susceptibility, previous studies of colorectal cancer are inconsistent regarding their role. We examined the relation between GSTM1 and GSTT1 genotypes combined and colorectal adenomas, and the interaction with cigarette smoking among 205 cases of colorectal adenomas and 220 controls with normal total colonoscopy in Japanese men. Neither GSTM1 nor GSTT1 was related to colorectal adenomas, nor were the null genotypes of GSTM1 and GSTT1 combined. The lack of an association with GSTM1 and GSTT1 genotypes combined persisted even when the analysis was done separately for proximal and distal colorectal adenomas. A three- to fivefold significant increase in the odds of colorectal adenomas was observed among men with a high exposure to cigarette smoking across the genotype groups, and a statistically significant increasing trend was noted within each genotype group. The present findings do not support the role for GSTM1 and GSTT1 genotypes in the development of colorectal adenomas.

Inducing potency of aryl hydrocarbon hydroxylase activity in human lymphoblastoid cells and mice by polychlorinated dibenzofuran congeners.

Aryl hydrocarbon hydroxylase (AHH)-inducing potency of eight polychlorinated dibenzofuran (PCDF) isomers, 3,4,5,3',4',5'-hexachlorobiphenyl (HCB) and 2,3,7,8-tetrachlorodibenzo-p-dioxon (TCDD) in two inbred mouse strains (AHH responsive and nonresponsive mouse strains) and eight human lymphoblastoid cell lines (four males and four females) was investigated to evaluate their relative toxic potency. In AHH nonresponsive DBA mouse strain, only TCDD induced hepatic AHH activity at a dose of 30 micrograms/kg, while in AHH responsive C57 mouse strain, six PCDF isomers besides TCDD could enhance the enzyme activity significantly. 2,3,7,8-Tetrachlorodibenzofuran (2,3,7,8-TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1,2,3,7,8-PCDF) and 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PCDF) showed the highest AHH inducing activity among the PCDF isomers tested. In contrast with the results obtained from the mouse experiments, in human lymphoblastoid cells, 2,3,4,7,8-PCDF, 1,2,3,4,6,7-hexachlorodibenzofuran (1,2,3,4,6,7-HCDF) and 1,2,3,7,8-hexachlorodibenzofuran (1,2,3,4,7,8-HCDF) elicited the highest AHH induction and were as potent AHH inducers as TCDD. These observations suggest that toxicities of 2,3,4,7,8-PCDF, 1,2,3,4,6,7-HCDF and 1,2,3,4,7,8-HCDF in human tissues may be comparable to that of TCDD. It was also observed that in both male and female human cell lines, the degree of AHH inducibilities of these compounds were roughly parallel to that of 3-methylcholanthrene, possibly indicating that genetic susceptibility among human population to the toxic compounds are also present similar to those reported among mouse strains.

Relationship of alcohol use, physical activity and dietary habits with serum carotenoids, retinol and alpha-tocopherol among male Japanese smokers.

BACKGROUND: Despite considerable interest in the anticarcinogenic and anti-atherosclerotic effects of carotenoids and alpha-tocopherol, little is known about determinants of these serum micronutrients. METHODS: The association of lifestyle factors including alcohol use, physical activity and dietary habits with serum levels of carotenoids (lycopene, lutein, cryptoxanthin and beta-carotene), retinol and alpha-tocopherol were studied in 194 healthy men aged 24-60 years who smoked > 15 cigarettes/day. A self-administered questionnaire ascertained consumption frequency of 12 food items, alcohol consumption, levels of physical activity and the number of cigarettes smoked per day. RESULTS: Of the dietary items studied, total vegetable intake was significantly, positively associated with beta-carotene levels, as was fruit intake with serum levels of each carotenoid. Tofu intake was unexpectedly, but strongly related to decreased levels of cryptoxanthin and beta-carotene. None of the food items was materially related to serum levels of retinol and alpha-tocopherol. Alcohol consumption was most strongly and inversely associated with levels of all the carotenoids except lutein, whereas was positively associated with retinol level but not with alpha-tocopherol level. Frequency of participation in sports was significantly and positively associated with both retinol and alpha-tocopherol levels. The amount of cigarettes smoked per day was unrelated to each micronutrient level in this study of moderate or heavy smokers. CONCLUSIONS: The consumption of vegetables and fruits is an important determinant of serum carotenoid levels even in smokers. Alcohol consumption is inversely associated with carotenoid levels, although the mechanism for this is not clear. Tofu and physical activity influence serum levels of antioxidative micronutrients, and these relationships need further studies.

In vivo effect of 7,8-benzoflavone on aryl hydrocarbon hydroxylase activity of mouse liver microsomes.

In vivo administration of 3-methylcholanthrene (MC) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produced much higher hepatic microsomal aryl hydrocarbon hydroxylase (AHH) induction than 7,8-benzoflavone (7,8-BF) in both aromatic hydrocarbon (Ah)-responsive and nonresponsive strains of mice. Simultaneous treatment or pre-treatment with 7,8-BF produced an inhibitory effect on AHH induction by MC or TCDD (i.e., the degrees of the inhibition, with TCDD, were 28% in the Ah-responsive strain C57BL/6N (C57) mice and 45% in the nonresponsive strain DDD;Qdj (DDD) mice). However, posttreatment with 7,8-BF was inclined to promote the induction of AHH by MC or TCDD (i.e., the degrees of the enhancement, with MC, were 15% in C57 mice and 45% in DDD mice). These results may suggest that the inhibitory effect of 7,8-BF in vivo is limited not to the combination of AHH inducer (MC or TCDD) but to its application of timing or Ah responsiveness.

Aryl hydrocarbon hydroxylase activity levels in the hepatic microsomal fraction from MC- or TCDD-treated mice: a comparison between aromatic hydrocarbon responsive and non-responsive strains.

The effects of in vivo administration of polycyclic aromatic hydrocarbons on the levels of aryl hydrocarbon hydroxylase (AHH) activity in aromatic hydrocarbon (Ah) responsive and non-responsive strains of mice were studied using the hepatic microsomal fraction. Injection of 3-methylcholanthrene (MC; 42 mg/kg body wt.) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 120 micrograms/kg body wt.) into both strains produced marked enhancement of AHH activity except for MC treatment of Ah non-responsive strains. Addition of 7,8-benzoflavone (BNF) to the microsomal AHH assay mixture prepared from mice previously injected with vehicle (olive oil) alone caused an increase in activity when the mice were responsive, while BNF lowered the activity in non-responsive strains. With regard to MC-injected mice, BNF and 3-methyl-sulphonyl-4,5,3',4'-tetrachlorobiphenyl (3-MSF-TCB) decreased microsomal AHH activity in Ah-responsive mice, whereas these drugs enhanced the activity in Ah-non-responsive strains. 3-MSF-TCB also had inhibitory potency on AHH activity, but the mechanism of inhibition seems to be somewhat different from that of BNF. It may also suggest that cytochrome P-450 isozymes inhibited by BNF are different from those inhibited by 3-MSF-TCB.