Clinical significance of the radiological severity score in Mycobacterium avium complex lung disease patients.

SETTING: Practical methods for assessing the radiographic findings of Mycobacterium avium complex lung disease (MAC-LD) have not been established. OBJECTIVE: To identify a correlation between the radiological score and semi-quantitative culture results of respiratory samples, and to assess the prognostic impact of this radiological score in MAC-LD patients. DESIGN: We retrospectively studied 218 MAC-LD patients. Radiographic findings were classified as nodule (N), infiltration shadow (I), cavity (C) and bronchiectasis (E), scored individually according to the area occupied on six lung field divisions, and added to give the radiological severity score. RESULTS: The radiological score positively correlated with the semi-quantitative culture score (P = 0.003). In univariate analysis, the radiological score was a significant negative prognostic factor for overall survival. On multivariate analysis, factors I, C and E were independent negative prognostic factors for overall survival. We compared the prognostic value of the total score of all four factors and the three significant factors (I, C and E) using receiver operating characteristic curve analysis; the corresponding areas under the curves were respectively 0.628 and 0.763 (P < 0.001). CONCLUSIONS: The radiological score correlates with prognosis. The combined score of factors I, C and E may more accurately predict prognosis in MAC-LD patients.

Efficacy of neoadjuvant chemotherapy followed by radical hysterectomy in locally advanced non-squamous carcinoma of the uterine cervix: a retrospective multicenter study of Tohoku Gynecologic Cancer Unit.

OBJECTIVE: Radical hysterectomy (RH) is a standard treatment for locally advanced non-squamous cell carcinoma (N-SCC) of the uterine cervix, but there have been no reports on whether neoadjuvant chemotherapy (NAC) followed by radical hysterectomy could improve the outcome of patients with this disease. MATERIALS AND METHODS: This multicenter retrospective study enrolled 77 patients with Stage IB2 to IIB N-SCC of the uterine cervix. Of these, 27 patients were treated with NAC prior to radical hysterectomy (NAC group) and 50 with RH alone (RH group). The two-year recurrence-free survival (RFS) rate, progression-free survival (PFS), and overall survival (OS) were compared between the two groups. Clinical parameters such as clinical stage, histological type, and postoperative treatment were also examined between the groups. RESULTS: While the two-year RFS rates were 81.5% and 70.0% in NAC and RH groups, respectively (p = 0.27) and the median PFS was 51 months and 35 months in NAC and RH groups, respectively (p = 0.35), the median OS was 58 months and 48 months in NAC and RH groups, respectively, which was significant (p = 0.0014). The median OS of patients with mucinous adenocarcinoma in NAC group was significantly higher than that in RH group: 58 months versus 37 months (p = 0.03). CONCLUSION: NAC prior to RH may offer the prognostic advantage of patients with locally advanced N-SCC of the uterine cervix, especially mucinous adenocarcinoma.

Simulation of deoxynivalenol intake from wheat consumption in Japan using the Monte Carlo method.

The aim of this study was to evaluate the current advisory level in Japan for deoxynivalenol (DON) in foods. To this end, we estimated the intake of DON based on its presence in wheat using a probabilistic computer simulation method. Values for the concentration of DON in wheat were based on those reported in surveys of 638 wheat samples conducted from 2002 to 2004. Data regarding consumption of 108 wheat-based products according to age group were obtained from the 2002 Japan national survey on food consumption. Two data sets on the consumption of wheat-based products and contamination of DON in wheat were analysed using three DON regulatory scenarios: no regulation, 1100 µg kg(-1) and 2000 µg kg(-1). Because consumption distributions contained two peaks for each age category, it was assumed that two log-normal distributions for each age category were needed to achieve a better fit to the distribution models. The results of simulated DON intake using the Monte Carlo method showed that children aged 1-6 years have the highest DON intake. However, the 95th percentile of simulated intake of DON in each age group was below the provisional maximum tolerable daily intake (TDI) of 1 µg kg(-1) body weight using any regulation scenario. The 99th percentile of simulated DON intake in the 1-6-year-old group was greater than TDI at approximately 2 µg kg(-1) body weight. These results suggest that the current dietary intake of DON from wheat consumption does not exert a significant health effect, but we may need to reconsider the current regulation value for the 1-6-year-old age group. In addition, we may need a better method to fit the distribution to the log-normal distribution better.

Exposure to aflatoxins in Japan: risk assessment for aflatoxin B1.

The intake of total aflatoxins (AFT) and aflatoxin B(1) (AFB(1)) from food in Japan was estimated from AFT and AFB(1) concentration and frequency data in 24 foods (884 samples) from a 3-year retail market survey from the summer of 2004 to the winter of 2006, and by food consumption data from the National Health and Nutrition Survey performed in 2005. The AFT and AFB(1) survey revealed that peanut, peanut products, cocoa, chocolate, pistachio, white pepper, red pepper, almond, job's tears, buckwheat and corn grits are considered to be contributors of AFT (or AFB(1)) intake in Japan (maximum AFB(1) (AFT) levels ranged from 0.21 to 28.0 microg kg(-1) (from 0.21 to 9.0 microg kg(-1))) in AFT-contaminated food. A probabilistic approach using the Monte Carlo method was carried out to simulate an estimate of the AFT (or AFB(1)) intake distributions in each age group in Japan. In this study, AFB(1) intake ranged from 0.003 to 0.004 ng kg(-1) body weight day(-1) (from lower to upper limits), and the potential risk for cancer using a formula devised by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives (JECFA) was estimated at 0.00004-0.00005 person/year/100,000 persons, even though this was in the higher levels (95.0th percentile) of the consumer population. The results suggest that the current dietary intake of AFB(1) in Japan has no appreciable effect on health.

The toxic effects and fate of intravenously administered zearalenone in goats.

To clarify the toxic effects and fate of zearalenone (ZEA) in ruminants, we studied histopathological changes and toxicokinetic profiles in goats administered with a single intravenous (iv) injection of ZEA at doses of 2.4 mg/kg bw and 1.2 mg/kg bw, respectively. The expression of the mRNA of estrogen receptor (ER) alpha and beta in tissues was also investigated. The histopathological study revealed that ZEA caused hepatocellular swelling and lymphocytic infiltration in the liver, kidney, and uterus. The expression of ERalpha mRNA was enhanced by ZEA in association with the histopathological changes, indicating the possible involvement of ERalpha in the toxic effects of ZEA. For toxicokinetic profiles, blood plasma, urine, and feces were collected consecutively after iv injection of ZEA and analyzed for ZEA and its metabolites with high performance liquid chromatography (HPLC). alpha-Zearalenol (ZOL) and beta-ZOL were detected with ZEA, but alpha-zearalanol (ZAL), beta-ZAL, and zearalanone were below the detection limits. The distribution half-life (t(1/2alpha)) and elimination half-life (t(1/2beta)) of ZEA were 3.15 and 28.58h, respectively. ZEA, alpha-ZOL, and beta-ZOL were excreted in urine and feces, with beta-ZOL being the predominant metabolite. The ZEA and ZOL in urine were largely in their glucuronide and/or sulphate conjugated forms, while those in feces were largely in their free forms. This study showed the toxic effect of zearalenone and its metabolites, and their pharmacokinetic characteristics in goats.

Impact of smoking as a risk factor for developing rheumatoid arthritis: a meta-analysis of observational studies.

OBJECTIVES: To assess whether smoking is a risk factor for developing rheumatoid arthritis (RA). DESIGN: Meta-analysis. DATA SOURCES: were observational studies that examined the association between smoking history and the risk of developing RA identified through Medline and EMBASE (from 1966 to December 2006), relevant books and a reference search. Two authors independently extracted the following: authors' names, publication year, sample size, participant characteristics, odds ratios (OR) or relative risks, adjustment factors, study design and area where the study was conducted. Data syntheses were based upon random effects model. Summarised syntheses effects were expressed by OR. RESULTS: Sixteen studies were selected from among 433 articles. For men, summary OR for ever, current and past smokers were 1.89 (95% CI 1.56 to 2.28), 1.87 (1.49 to 2.34) and 1.76 (1.33 to 2.31), respectively. For rheumatoid factor-positive (RF+) RA, summary OR for ever, current and past smokers were 3.02 (2.35 to 3.88), 3.91 (2.78 to 5.50) and 2.46 (1.74 to 3.47), respectively. Summary OR for 20 or more pack-years of smoking was 2.31 (1.55 to 3.41). For women, summary OR for ever, current and past smokers were 1.27 (1.12 to 1.44), 1.31 (1.12 to 1.54) and 1.22 (1.06 to 1.40), respectively. For RF+ RA, summary OR for ever, current and past smokers were 1.34 (0.99 to 1.80), 1.29 (0.94 to 1.77) and 1.21 (0.83 to 1.77). Summary OR for 20 or more pack-years of smoking was 1.75 (1.52 to 2.02). CONCLUSION: Smoking is a risk factor for RA, especially RF+ RA men and heavy smokers.

Aflatoxin and ochratoxin A contamination of retail foods and intake of these mycotoxins in Japan.

A survey was undertaken of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), G2 (AFG2), ochratoxin A (OTA), and fumonisin B1 (FB1), B2 (FB2) and B3 (FB3) contamination of various retail foods in Japan during 2004-05. The mycotoxins were analysed by high-performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS) or high-performance thin-layer chromatography (HPTLC). Aflatoxins (AFs) were detected in ten of 21 peanut butter and in 22 of 44 bitter chocolate samples; the highest level of AFB1, 2.59 microg kg(-1), was found in peanut butter. Aflatoxin contamination was not observed in corn products (n = 55), corn (n = 110), peanuts (n = 120), buckwheat flour (n = 23), dried buckwheat noodles (n = 59), rice (n = 83) or sesame oil (n = 20). OTA was detected in 120 out of 192 samples of oatmeal, wheat flour, rye, buckwheat flour, raw coffee, roasted coffee, raisin, beer, wine and bitter chocolate, but not in rice or corn products. OTA levels in the positive samples were below 13 microg kg(-1). AFs and OTA intakes through the consumption of foods containing cacao were estimated using the data for mycotoxin contamination in bitter chocolate and those for the consumption of foods containing cacao in Japan.

Thymic granulomatous lesions in pigs.

Rare cases of thymic granulomatous lesions were found in pigs. The lesions consisted of epithelioid cells, multinucleated giant cells, and lymphocytes. Such lesions also were observed in the mesenteric lymph nodes, spleen, kidney, and stomach. The cytoplasm of the majority of giant cells and some epithlioid cells was periodic acid-Schiff (PAS) positive. All cells were positive for vimentin, lysozyme, and desmin. Ultrastructurally, the giant cells were rich in organella and attached to adjacent epithelioid cells by membrane interdigitation. The cells included numerous coated vesicles and granules. No etiologic pathogen, including porcine circovirus type 2, was detected in the lesions. This is the rare case of idiopathic thymic granulomatous lesion in pigs.

Troglitazone inhibits cell growth and induces apoptosis of B-cell acute lymphoblastic leukemia cells with t(14;18).

Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the nuclear receptor superfamily, has been detected in several human leukemia cells. Recent studies reported that PPARgamma ligands inhibit cell proliferation and induce apoptosis in both normal and malignant B-lineage cells. We investigated the expression of PPARgamma and the effects of PPARgamma ligands on UTree-O2, Bay91 and 380, three B-cell acute lymphoblastic leukemia (B-ALL) cell lines with t(14;18), which show a poor prognosis, accompanying c-myc abnormality. Western blot analysis identified expression of PPARgamma protein and real-time PCR that of PPARgamma mRNA on the three cell lines. Troglitazone (TGZ), a synthetic PPARgamma ligand, inhibited cell growth in these cell lines in a dose-dependent manner, which was associated with G(1) cell cycle arrest and apoptosis. We also found this effect PPARgamma independent since PPARgamma antagonists failed to reverse this effect. We assessed the expression of c-myc, an apoptosis-regulatory gene, since c-myc abnormality was detected in most B-ALL cells with t(14;18). TGZ was found to dose-dependently downregulate the expression of c-myc mRNA and c-myc protein in the three cell lines. These results suggest that TGZ inhibits cell growth via induction of G(1) cell cycle arrest and apoptosis in these cell lines and that TGZ-induced apoptosis, at least in part, may be related to the downregulation of c-myc expression. Moreover, the downregulation of c-myc expression by TGZ may depend on a PPARgamma-independent mechanism. Further studies indicate that PPARgamma ligands may serve as a therapeutic agent in B-ALL with t(14;18).

Gamma/delta T-cell receptor type granular lymphocyte proliferative disorder associated with rheumatoid arthritis.

We present here a case report of a 69-year-old female patient with T granular lymphocyte proliferative disorder (T-GLPD) expressing the gamma/delta T-cell receptor. The patient had been treated for rheumatoid arthritis for 25 years, and presented with mild anaemia. Cell-surface marker analysis was carried out using flow cytometry and natural killer function was determined using a chromium release assay. The case report is followed by a summary of the 21 other gamma/delta T-GLPD cases reported in the literature and a comparison of their clinical characteristics with those of T-GLPD cases expressing the alpha/beta T-cell receptor. The clinical symptoms and the frequency of association with rheumatoid arthritis are similar in gamma/delta and alpha/beta T-GLPD, but a prevalence of the CD8- cell-surface marker and enhanced natural killer function appear to be characteristics of gamma/delta T-GLPD.

A novel polymorphism of the SSA1 gene is associated with anti-SS-A/Ro52 autoantibody in Japanese patients with primary Sjögren's syndrome.

OBJECTIVE: To investigate the association of polymorphisms of the SSA1 gene (OMIM 109092) with primary Sjögren's syndrome (SS) and anti-SS-A/Ro52 antibody production. METHODS: Polymorphisms of SSA1 gene in 111 Japanese SS patients and in 97 healthy controls were analyzed with polymerase chain reaction and automated DNA sequencing. RESULTS: A new single-nucleotide polymorphism (SNP) was identified in intron 1 at position 7216. The allele frequency and genotype of 7216A/G were not significantly different between SS patients and control subjects. However, the allele frequency and genotype of 7216A/G were associated with the presence of anti-SS-A/Ro52 antibody among primary SS patients. The association was not found in patients with SLE, suggesting the limited role for the SNP in anti-SS-A/Ro52 antibody production. The 9571C/T polymorphism, which has been shown to associate with anti-SS-A/Ro52 antibody in Caucasian patients, was not associated with the presence of anti-SS-A/Ro52 antibody in Japanese patients. CONCLUSIONS: 7216A/G polymorphism of SSA1 gene may be one of the genetic factors that determine the presence of anti-SS-A/Ro52 antibody in patients with primary SS.

Modification of cytokine milieu by A2A adenosine receptor signaling--possible application for inflammatory diseases.

Pro-inflammatory cytokine TNF-alpha (TNF) production from in vitro lipopolysaccharide (LPS)-stimulated human peripheral blood CD14+ cells (PB-CD14) was inhibited by A2A adenosine receptor (AdoR) (A2AR) or beta2 adrenergic receptor (ADR) (beta2R) signaling in a concentration-dependent manner. These inhibitory effects were presumably mediated by the increase in intracellular cAMP. Furthermore A2AR agonist and beta2R agonist synergistically inhibited the TNF production of LPS-stimulated PB-CD14 cells. These results suggest that the anti-inflammatory effect of extracellular adenosine is, at least in part, due to the modification of the cytokine milieu via A2A signaling, and that the targeting of both A2AR and beta2R may have strong therapeutic potential for the inflammatory diseases.

Occurrence of aflatoxin M1 in domestic milk in Japan during the winter season.

A total of 208 samples of commercial pasteurized milk gathered from retail outlets across Japan during the winter season were analysed for aflatoxin M1 (AFM1). Japan was divided into 11 regions from north to south, and nine to 45 milk samples from each region were randomly purchased between December 2001 and February 2002. Each milk sample was cleaned up by an immunoaffinity column, and AFM1 was quantified by liquid chromatography with fluorescence detection in four independent laboratories. The limit of detection of the method was 0.001 microg kg(-1). The identity of the putative AFM1 in milk sample was confirmed by the formation of AFM1 hemi-acetal with trifluoroacetic acid. Based on the results obtained with spiked samples (0.05 microg AFM1 kg(-1)), the mean recovery was 91.4%, the relative standard deviation for repeatability was 4.6%, and the relative standard deviation for reproducibility was 8.0% among four independent laboratories. AFM1 was detected in 207 (99.5%) of 208 milk samples at 0.001-0.029 microg kg(-1), with a mean of 0.009 microg kg(-1) and a 90th percentile of 0.014 microg kg(-1). No significant difference of the level of AFM1 contamination was observed among the regions.

Quantitative nested reverse transcriptase PCR vs. real-time PCR for measuring AML1/ETO (MTG8) transcripts.

A quantitative nested reverse transcriptase polymerase chain reaction (QN-RT-PCR) method was developed using a plasmid cDNA containing the AML1/ETO (MTG8) fusion transcript from Kasumi-1 cells, an acute-myelogenous leukemia cell line with the t(8;21) translocation. In this method, the plasmid was detectable at a concentration of 10(-17) m. The fusion transcript in a mixture of 10(7) Rice94 (Burkitt lymphoma cell line) cells containing two Kasumi-1 cells was detectable at 10(-17) m. In a previously published real-time PCR method, the plasmid containing the fusion transcript was detectable at 10(-16) m or higher, and 20 or more Kasumi-1 cells were detectable in 10(7) Rice94 cells. Thus, this QN-RT-PCR method is more sensitive than the real-time PCR. When the same samples were examined by real-time PCR and our QN-RT-PCR method, in one patient in clinical remission after chemotherapy and allogeneic-bone marrow transplantation (BMT), the transcript was detected by QN-RT-PCR 60 days prior to hematological relapse, in contrast to 10 days before hematological relapse by real-time PCR. The transcript level was below 10(-17) m (undetectable) with this QN-RT-PCR in patients in clinical remission after chemotherapy and BMT, while it was 10(-15)-10(-16) m in patients in clinical remission after chemotherapy alone. The quantitative difference of the transcript level in minimal residual disease (MRD) between these two different types of clinical remission was estimated to be at least 10(2)-fold. This QN-RT-PCR method is useful for predicting hematological relapse and for quantitatively estimating MRD in different types of clinical remission.

Effect of mutated transporters associated with antigen-processing 2 on characteristic major histocompatibility complex binding peptides: analysis using electrospray ionization tandem mass spectrometry.

A novel allele of transporters associated with the antigen-processing (TAP) 2 gene, TAP2*Bky2 (Val(577)), is significantly increased in Japanese patients with Sjögren's syndrome (SS), and has a strong association with SS-A/Ro autoantibody production in SS and autoantibody including anti-SS-A/Ro and anti-U1 RNP antibody in systemic lupus erythematosus (SLE). To determine the influence of this natural mutated TAP on peptides loaded onto MHC class I, we analyzed the repertoire of peptides loaded onto MHC class I on transfectants with TAP1 and TAP2 or mutated TAP2 by electrospray ionization tandem mass spectrometry (ESI-MS/MS). After comparison of the peptide profiles we identified three peptides from only mutated TAP transfectants. Moreover, one of these peptides is derived from snRNP A, which is a target for anti-U1 RNP antibody. To our knowledge this is the first report to show that the natural mutation of TAP2 changes the peptide profile loaded onto MHC class I molecules.

Activation-induced cytidine deaminase expression in follicular lymphoma: association between AID expression and ongoing mutation in FL.

Activation-induced cytidine deaminase (AID) is required for somatic hypermutation (SHM) and class switch recombination (CSR) of the immunoglobulin (Ig) gene. AID has been reported to be specifically expressed in the germinal center (GC). Follicular lymphoma (FL) cells are known to be exposed to GC reaction, as characterized by a high degree of SHM with some heterogeneity in terms of intraclonal microheterogeneity and antigen selection. The heterogeneity of SHM pattern in FL intrigued us to investigate the AID expression. AID expression was investigated in 19 FL materials consisting of 15 cases of FL fresh cells and four cell lines. In all, 10 fresh cells and three cell lines expressed AID, but the others did not. SHM was investigated in 12 fresh cells and four cell lines. The ongoing mutation was significantly different between AID-positive and AID-negative FL fresh cells (unpaired Student's t-test, P=0.047). Ongoing mutation was not seen in any of the cell lines. AID expression was associated with the ongoing mutation in FL fresh cells (two-tailed Pearson's coefficient correlation, r=0.899, P=0.01). The switch off of AID expression may start in the B-lineage differentiation stage counterpart of FL after optimizing SHM, indicated by the cessation of the ongoing mutation in AID-negative FL fresh cells.

Phase I clinical and pharmacological study of intraperitoneal cis-bis-neodecanoato( trans- R, R-1, 2-diaminocyclohexane)-platinum II entrapped in multilamellar liposome vesicles.

PURPOSE: To perform a phase I study of intraperitoneal cis-bis-neodecanoato ( trans- R, R-1, 2-diaminocyclohexane)-platinum II entrapped in multilamellar vesicles (L-NDDP) for peritoneal carcinomatosis or sarcomatosis. METHODS: Eligible patients had normal renal, hematologic, and liver functions. Laparoscopy was performed on the first two courses for evaluation, adhesiolysis, and chemotherapy administration. Afterwards, chemotherapy was administered through a peritoneal catheter. Up to six courses were allowed. Peritoneal imaging with technetium-labeled sulfur colloid was used to determine adequate distribution prior to each course. Volunteering patients underwent pharmacokinetics studies during the second course. RESULTS: Fifteen of 16 registered patients, seven women and eight men (median age 53 years (range 26-76) and median performance status of 1) were assessable. Diagnoses were: malignant mesothelioma (six patients), signet ring cell (three), colon adenocarcinoma, pseudomyxoma peritonei, gastrointestinal stromal tumor (two each), and ovarian carcinoma (one). Median number of courses was two (range, one to six) Dose-limiting toxicity symptoms were fatigue and abdominal pain. Hematologic toxicities were minimal. Peri-operative complications included one colonic perforation requiring primary closure, a peritoneal catheter malfunction, a port site hematoma, and an ascites leak requiring re-suture. Five patients survived at least 3 years. Pharmacokinetics studies indicated a rapid but low absorption of drug into the systemic circulation, with a prolonged retention of platinum in the plasma compartment. Peritoneal L-NDDP exposure was 17 to 49-times greater than in the plasma compartment. CONCLUSIONS: Peritoneal cavity exposure to L-NDDP is prolonged, and systemic absorption is limited, yielding a high peritoneal/plasmatic ratio. The recommended dose for phase II studies is 400 mg/m2 every 28 days.

Gold sodium thiomalate suppresses the differentiation and function of human dendritic cells from peripheral blood monocytes.

OBJECTIVE: Gold sodium thiomalate (GST) is a drug commonly used for the treatment of rheumatoid arthritis (RA). To clarify the mechanism of therapeutic effects of GST on RA, we investigated if GST affects the differentiation of dendritic cells (DC), which are thought to play a pivotal role in RA pathogenesis. METHODS: We generated immature DC (iDC) in vitro from PB monocytes during the 5 to 7-day culture in the presence of IL-4 and GM-CSF. Mature DC (mDC) were induced by adding TNF alpha on day 5 of the 7-day culture with GM-CSF and IL-4. DC capacity of stimulating T cells was examined in allogenic MLR using generated DC as stimulators. IL-12 production from DC was assayed with ELISA. RESULTS: We found that: 1) mDC generated in the presence of GST showed lower expression of CD1a, CD83, CD80, CD86, HLA-ABC and HLA-DR compared to control mDC on FACS analysis. 2) GST-treated mDC showed reduced capacity of stimulating allogenic T cells in mixed leukocyte reaction. 3) IL-12p70 production after stimulation with SAC or LPS plus IFN gamma was markedly reduced in GST-treated mDC. CONCLUSION: GST suppresses the differentiation and function of DC generated from peripheral blood monocytes. This previously unknown action may explain the in vivo effects of GST in the treatment of RA.

Glutathione-S-transferase activity toward aflatoxin epoxide in livers of mastomys and other rodents.

In order to study the liver glutathione-S-transferase (GST) activity toward aflatoxin B1 (AFB1) epoxide in mastomys in comparison with other rodents, we performed in vitro studies of the cytosolic GST activity toward AFB1-epoxide using mastomys, rat, mouse and hamster liver. Also AFB1 metabolism by liver microsomes including formation of AFB1-DNA adducts was studied. Cytosolic GST activity toward AFB1-epoxide was highest in mastomys liver, and higher in the hamster and mouse livers than in the rat liver, correlating well with the differences of the sensitivity of these species to the toxicity of AFB1. However, no relationship was noted between the sensitivity of a given species to the toxicity of AFB1 and the microsomal activity of binding of AFB1 to DNA or metabolizing AFB1 to AFM1, AFQ1 and AFP1. These results demonstrate the importance of the GST mediated AFB1-epoxide conjugation with glutathione in determining the differing sensitivities of these species to AFB1 toxicity. The extremely high activity of GST in mastomys indicates that this species would be a good model animal for studying GST toward AFB1-epoxide.