Aflatoxin B1 in the serum of a patient with primary hepatic carcinoma

Aflatoxin levels in chronic hepatitis B patients with cirrhosis or hepatocellular carcinoma in Balıkesir, Turkey

Aflatoxins, the secondary metabolites produced by species of naturally occurring Aspergilli, are commonly found in food such as cereals, dried fruits and juice, wine, beer and spices. They are hepatotoxic and are well known human carcinogens based on evidence from human studies. Aflatoxins are an environmental risk factor for the development of hepatocellular carcinoma (HCC). Chronic hepatitis B-infected patients are at increased risk of cirrhosis, hepatic failure and liver cancer. This study was designed to determine the serum aflatoxin B1 (AFB1 ), aflatoxin B2 (AFB2 ), aflatoxin G1 (AFG1 ) and aflatoxin G2 (AFG2 ) concentrations using high-pressure liquid chromatography (HPLC) in hepatitis B-infected patients with or without cirrhosis and liver cancer, alongside healthy controls in Balıkesir, Turkey. The mean AFB1 and total AF levels in patients without liver cancer and cirrhosis were significantly higher than healthy controls. The mean AFB1 and total AF levels in patients with chronic hepatitis B and HCC were significantly higher than infected patients with or without cirrhosis. These results suggest that patients with chronic hepatitis B who are exposed to AFs are at increased risk for developing HCC, which might be prevented by reducing consumption of contaminated foods.

Serum aflatoxin levels of the healthy adult population living in the north and south regions of Turkey

OBJECTIVE

To determine the serum concentrations of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) in the healthy adult population living in both the Black Sea and Mediterranean regions of Turkey and to investigate the regional, seasonal and gender variability in aflatoxins (AF) exposure in these regions.

DESIGN

Serum AFB1, AFB2, AFG1 and AFG2 concentrations were analysed by HPLC. Settings In total, four hundred and eighty-four serum samples were analysed.

SUBJECTS

Four hundred and eighty-four healthy adult volunteers living in rural areas of the Black Sea and Mediterranean regions of Turkey were studied.

RESULTS

The mean serum concentration of total AF in the Black Sea region was 1·33 ppb (min-max 0·15-3·38 ppb) and 0·90 ppb (min-max 0·18-2·48 ppb) for summer and winter, respectively. In the Mediterranean region, the mean serum concentration of total AF was determined as 0·55 ppb (range 0·04-1·72 ppb) for summer and 0·45 ppb (range 0·12-1·43 ppb) for winter. The total AF concentrations in serum samples were statistically higher in summer compared with winter for the two regions. The differences between the regions were statistically significant concerning all samples, with higher total AF concentrations in the Black Sea region.

CONCLUSIONS

The overall results suggest that the Turkish population living in these two regions is continuously exposed to AF, particularly in the summer, and that mycotoxin contamination in food should be monitored routinely for food safety and human health.

Aflatoxin contamination in food and body fluids in relation to malnutrition and cancer status in Cameroon

Aflatoxins are food contaminants usually associated with hepatitis, immunodepression, impairment of fertility and cancer. The present work was to determine the presence of aflatoxins in eggs, milk, urine, and blood samples that were collected from various sources and periods; and hepatitis B virus antigen in blood samples. Aflatoxin was found in eggs (45.2%), cow raw milk (15.9%), breast milk (4.8%), urine from kwashiorkor and marasmic kwashiorkor children (45.5%), and sera from primary liver cancer patients (63.9%); HbsAg was also detected in 69.4% of the serum samples, but there was no association between both factors. Both AF and hepatitis B virus seem to be risk factors that could increase the incidence and prevalence rates of malnutrition and cancer in Cameroon.

Analysis of UK sera for aflatoxin by enzyme-linked immunosorbent assay

1. Aflatoxins are toxic, carcinogenic secondary fungal metabolites produced by certain moulds that commonly infest foods. Measurement of aflatoxins in human serum would give a direct measurement of exposure. 2. Twenty-seven serum samples from UK blood donors were found to contain aflatoxin levels not greater than 64 pmol/l (20 pg/ml) by an enzyme-linked immunosorbent assay. 3. These findings may indicate that present UK guideline tolerances for aflatoxin in imported food are effective in limiting human exposure to toxic aflatoxins in the UK diet, though further work would be needed to confirm this. In particular, sub-populations suspected of being at higher risk may need special considerations.

Characterization of the aflatoxin B1-binding site of rat albumin

A fluorescence-enhancement method was used to investigate the non-covalent interaction between aflatoxin B1 and rat albumin. Solvent-induced shifts in the emission spectrum of aflatoxin B1 provided evidence that the aflatoxin B1-binding site of rat albumin is a highly nonpolar environment. A dissociation constant of 20 microM was determined at 20 degrees C. The possibility that aflatoxin B1 binds one of the three major drug sites of albumin was investigated by ligand-displacement experiments. Mechanisms whereby marker ligands displace aflatoxin B1 were further investigated by comparing the experimental binding parameters with those derived theoretically, assuming competitive binding. The results indicate that: aflatoxin B1 and phenylbutazone compete for a common high-affinity site on rat albumin; high-affinity binding of aflatoxin B1 and site-II marker ligands takes place independently; aflatoxin B1 does not compete with either cholate or warfarin for the same high-affinity site, but the simultaneous binding of warfarin or cholate negatively modulates the binding of aflatoxin B1 to albumin. Fluorescence energy-transfer studies show that the lone tryptophan residue, Trp-214, is not associated with the aflatoxin B1-binding site.

Precipitins to an aflatoxin-producing strain of Aspergillus flavus in patients with malignancy

Serum samples from 121 patients in whom malignant disease had been diagnosed, were assayed for precipitins to fungal isolates from leukemia-associated environments. Control sera were from age-, sex-, and race-matched patients with no history of malignant disease. Sera from 36 (30%) malignancy patients and seven (6%) controls yielded a precipitin band to an aflatoxin-producing Aspergillus flavus isolate from a leukemia-associated house (x2 = 222, p less than 0.05%). No significant numbers of precipitins were obtained to either of the other fungal isolates from that and another such house. Although A. fumigatus has frequently been incriminated as a source of infection in patients with malignancy, only 9% of malignancy patients had a precipitin response to it, as did 1.6% of controls. Also, the presence of the precipitins to A. flavus was not connected with past radiation or immunosuppressive therapy. However, among patients with precipitins to A. fumigatus there was a higher death rate in the year following the study. Precipitins to A. flavus may be related to heavy environmental exposure possibly leading to aflatoxin exposure which may contribute to development of malignancy though immunosuppressive effects.