Effect of low protein diet on chronic aflatoxin B1-induced liver injury in rhesus monkeys

Aflatoxin M1in breast-milk of UAE women

A study was undertaken to determine whether breast-milk of mothers from the United Arab Emirates (UAE) contained aflatoxins. One hundred and forty lactating mothers, 55 who had delivered premature infants (<2500 g, </=37 wk gestational age) and 85 who had full-term infants, agreed to participate in the study. Breast-milk was collected during regular feeding of infants in the special care baby unit and postnatal wards using an electric breast pump and ten ml of milk was siphoned off into a zinc-free plastic container for analysis. Aflatoxin M(1) concentration in the breast-milk samples was measured by HPLC. Samples were collected between January 1999 and December 2000. Approximately 66% of the mothers were expatriates and 34% were UAE nationals. Babies' weight, postnatal age, sex, birthweight and gestational age, and mothers' nationality, age and parity were recorded. Overall, 92% of the breast-milk samples contained aflatoxin M(1). Both univariate and multivariate logistic regression analysis failed to show significant correlation between aflatoxin M(1) and gestational age, postnatal age, gender, nationality and clinical condition. Levels of lactose, protein and lipids did not correlate significantly with levels of aflatoxin M(1). The public should be educated about storing food and the hazards of aflatoxin ingestion to reduce the unacceptably frequent presence of aflatoxin in breast-milk.

Cerebellar abscess in a cynomolgus macaque (Macaca fascicularis)

BACKGROUND

A cynomolgus macaque (Macaca fascicularis) presented with decreased appetite, lethargy, ataxia, disorientation and visual impairment. It was used in a hepatitis B (HBV) study involving injections of HBV plasmid construct (450 microg) and aflatoxin B1 (25 microg/kg) in an effort to develop a model of liver cirrhosis and hepatocellular carcinoma.

METHODS

The case work-up included physical examination, including assessment of hydration, thoracic and abdominal radiographs and abdominal ultrasound. Clinical pathology included complete blood counts and tests for levels of plasma ammonia (NH(3)) and serum electrolytes, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, total bilirubin, and gamma-glutamyl transferase. Serum samples had also been serially tested for the presence of HBsAg, anti-HBc antibodies, HBV e-antigen, and HBV DNA. With a tentative diagnosis of hepatic encephalopathy, treatment with lactulose, antibiotics, and fluid therapy was initiated.

RESULTS

Clinical pathology and diagnostic imaging performed on the animal revealed no abnormalities except for the hyperammoniemia. Absence of HBV markers in the serum indicated unsuccessful inoculation. Not fully responding to therapeutic intervention, the animal was euthanized. Necropsy revealed fibrous peritoneal adhesions and an abscess in the cerebellopontine angle. Exudate culture indicated the presence of alpha-hemolytic streptococcus, Eubacterium lentum, and Bacteroides stercoris.

CONCLUSIONS

Brain abscesses are uncommon in non-human primates. This case of cerebellar abscess is characterized by important features similar to that found in humans, including the presenting signs and the presence of the above-cultured bacteria.

Effect of dietary casein levels on activation of promutagens in the spiral Salmonella mutagenicity assay. II. Studies with induced rat liver S9

In the previous study (Mutation Res., this issue), we showed that increased levels of dietary casein as the sole protein source for male F344 rats decreased the ability of the uninduced liver S9s to activate 2-aminoanthracene (2AN) to a mutagen in strain TA98 using the spiral Salmonella mutagenicity assay. No effects of dietary casein levels were noted for the ability of uninduced liver S9s to activate the promutagens aflatoxin B1 (AFB) and benzo[a]pyrene (BAP). In the present study, we have extended this study to include liver S9s induced with either Aroclor 1254, phenobarbital or 3-methylcholanthrene (3MC). S9s were derived from individual male F344 rats fed for 6 weeks on semisynthetic diets containing 8%, 12% or 22% methionine-supplemented casein as the sole source of protein (diets were made isocaloric by adjusting the corn starch content). Rats were housed in large, raised-bed cages by groups of three/diet/inducing agent. S9 activation mixtures were prepared at 5 mg of S9 protein/ml of S9 mix. Slopes from the linear portions of the mutagenicity dose-response curves were analyzed by ANOVA comparisons. Assays used to elucidate the phase I activities of microsomal preparations were cytochrome P-450 content, cytochrome-c reductase activity, flavin-containing monooxygenase activity, 7-ethoxyresorufin O-deethylation (EROD) activity, N-demethylation of benzphetamine, and para-nitrophenol O-deethylation. Phase II activities were assayed by estimating glutathione (GSH) content and measuring the metabolism of 1-chloro-2,4-dinitrobenzene (CDNB) by glutathione S-transferase in cytosolic preparations. None of the phase I or phase II endpoints were significantly affected by dietary casein levels. In general, increasing levels of dietary casein resulted in increased body and liver wet weight and amount of S9 protein. Aroclor-induced S9s from rats fed the 22% or 12% casein diet were most effective at activating AFB, depending on the lot of Aroclor used for induction; these divergent results were replicated with two groups of rats for each lot of Aroclor. The observed differences between Aroclor lots are assumed to arise from variation in the mix of PCB isomers. The Aroclor-induced S9s did not exhibit any casein-related effects for the activation of BAP or 2AN. For 3MC-induced S9s, the 12% casein diets produced S9s with the highest ability to activate AFB and BAP when standardized for protein content. Phenobarbital-induced S9s did not demonstrate any dietary casein-related effects on the activation of the three model promutagens. These results illustrate the complex interaction between dietary levels of casein, enzyme inducing agent and promutagen.