SEARCH · PubMed Health

Results for “Aflatoxin”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources

PubMedDate not supplied

Recent aflatoxin exposure and mutation at codon 249 of the human p53 gene: lack of association.

Experiments were done to show whether a G to T mis-sense mutation at the third base of codon 249 of the p53 tumour suppressor gene is a 'hot spot' of aflatoxin attack as suggested by the results of epidemiological studies. Liver tissue from liver cancer patients in Taiwan and Japan was analysed for the presence of aflatoxin-DNA adducts (ADA) as a marker for aflatoxin exposure and an AGG to AGT transversion at codon 249 of the p53 gene. Ten per cent of samples containing ADA, indicating definite exposure of the subjects to aflatoxin, was found to harbour the codon 249 mutation, whereas 18% of the samples with no detectable adducts also contained the mutation. Our data do not support the hypothesis that codon 249 of the p53 gene DNA is a hot spot for aflatoxin mutagenesis as a 'late stage event' in human hepatocellular carcinogenesis.

Aflatoxins↗

PubMed1996

A UK retail survey of aflatoxins in herbs and spices and their fate during cooking.

A survey of aflatoxins in herbs and spices has been carried out and cooking experiments conducted to assess the stability of aflatoxin in spice sauces. Of 157 retail samples which included curry powders, pepper, cayenne pepper, chilli, paprika, ginger, cinnamon and coriander, nearly 95% of samples contained below 10 micrograms/kg total aflatoxins and only nine samples had higher levels. The highest concentration in a retail sample was 48 micrograms/kg in a chilli powder. In addition to retail sampling, 14 consignments of whole chilli and chilli powder were sampled at the port of entry. Only two samples, both chilli powder, were above 10 micrograms/kg; containing 35 and 51 micrograms/kg total aflatoxins. Cooking experiments showed that aflatoxin levels in spiced sauces are not reduced by domestic cooking with either microwave or conventional gas oven heating.

Aflatoxins↗

PubMedDate not supplied

Occurrence of fumonisins and aflatoxins in corn from Thailand.

Eighteen corn samples collected from Thailand were analysed for fumonisins and aflatoxins by high performance liquid chromatography. Fumonisins B1 and B2 were detected in 16 (89%) and 12 (67%) samples at levels ranging from 63 to 18800 ng/g (mean, 1790 ng/g) and from 50 to 1400 ng/g (mean, 251 ng/g), respectively. Fusarium moniliforme and F. proliferatum isolated from Thai corn showed the production of fumonisins in corn grit cultures. Aflatoxins B1 and B2 were found in 15 and 10 samples at mean levels of 72 and 15 ng/g, respectively. It was noted that as many as 72.2% (13/18) of samples were coincidentally contaminated with fumonisins and aflatoxins. Based on these results, the interaction of fumonisin-producers and aflatoxin-producers on kernel infection and contamination of these mycotoxins in corn is discussed. This is the first report on the natural co-occurrence of fumonisins and aflatoxins in Thailand.

Aflatoxins↗

PubMed1992

Aflatoxins and kwashiorkor in Durban, South Africa.

The present investigation has indicated that maize seeds stored under various simulated seasonal conditions show a spectrum of fungi that appear as a succession. The aflatoxin-producing fungus, Aspergillus flavus, is favoured by storage conditions of high temperature and humidity (summer and autumn seasons). This coincides with the more frequent admission of children suffering from kwashiorkor at King Edward VIII Hospital in Durban. Aflatoxin analysis was undertaken on 74 children diagnosed at King Edward VIII Hospital in Durban as cases of kwashiorkor, marasmus or underweight (Wellcome classification). The control group consisted of 35 age-matched patients with no symptoms of protein energy malnutrition. Aflatoxins were detected in serum and/or urine from all groups, including the controls. The serum/urine ratio was significantly higher in the kwashiorkor group than in the other groups. The control group, however, had a higher proportion of urine aflatoxins than the kwashiorkor group. These findings were interpreted in terms of impaired liver function in kwashiorkor. Aflatoxins may have a rôle in the pathogenesis of kwashiorkor, although the present findings do not indicate that they are a causal factor.

Aflatoxins↗

PubMed1991

Aflatoxins in food: occurrence, biosynthesis, effects on organisms, detection, and methods of control.

Aflatoxins are secondary metabolites produced by species of Aspergilli, specifically Aspergillus flavus and Aspergillus parasiticus. These molds are ubiquitous in nature and grow on a variety of substrates, thereby producing aflatoxins. Aflatoxins are of great concern due to their biochemical and biological effects on living organisms. In this article, the occurrence of aflatoxins, their biosynthesis, factors influencing their production, their effects on living organisms, and methods of detection and control in food are reviewed. Future areas of research involving mathematical modeling of factors influencing aflatoxin production and alternative methods of control, such as modified atmosphere packaging, are also discussed.

Aflatoxins↗

PubMed1997

Airborne aflatoxin in the grain processing industries in India.

Airborne aflatoxin generated in rice and maize processing plants was assayed by an indirect competitive enzyme-linked immunosorbent assay. In the rice mill, levels of airborne aflatoxin were always higher in the respirable dust samples (< 7 microns) compared with the total dust samples (< 7 microns). The concentrations of total airborne aflatoxin in the respirable dusts were 26 picogram/m3 and 19 pg/m3, respectively, for the workplace and the storage area of the rice mill, while the concentrations of total dust were 12 pg/m3 for the workplace and 11 pg/m3 for the storage area. Airborne aflatoxin was not detected in control sites of either of the grain processing plants or from the total dust samples obtained from the maize plant. Three sites in the maize processing plant-the elevator (18 pg/m3), the loading/unloading area (800 pg/m3), and the oil mill (816 pg/m3)-showed the presence of airborne aflatoxin only in the respirable dust samples.

Aflatoxins↗

PubMedDate not supplied

Effect of low level of dietary aflatoxins on baladi rabbits.

Aflatoxins B1, B2, G1 & G2 were administered in a low concentration (100 ppb of each aflatoxin (AN] in a mash offered to Baladi rabbits. An other group of rabbits were fed on the same contaminated mash in addition to 0.25% charcoal (CC). The two groups were compared to control animals fed on AN-free mash. Inclusion of AN in the diet decreased feed and water consumption, body weight and survival rate. Charcoal improved somewhat feed and water consumption and growth rate than AN-group. However, CC-group affected digestibility of organic matter more than AN-group. Relative weights of liver, kidneys, heart and adrenal glands were significantly higher in AN and CC groups than the control group. Blood haemoglobin content, packed cell volume percentage and sedimentation rate were lower in AN group. Although there were an increase in each of serum, calcium, inorganic phosphorus, cholesterol, phospholipids and glutamic-pyruvic transaminase in AN group, yet the serum nitrogen and glutamic-oxalacetic transaminase were reduced. Charcoal had alleviated AN-effects concerning N, GPT and phospholipids. Chemical analysis revealed elevation of water, ash and silica contents of liver and water content of muscles from AN-animals. On the other hand, fat content, GOT and vitamin A in the liver as well as muscles ash were reduced. Addition of CC to the diet reduced AN-effects on liver fat, ash and silica but resulted in a rise of the water content of liver and muscles and liver GPT activity. Charcoal also resulted in a sharp decrease in vitamin A content of the liver. Aflatoxin treatments (in AN and CC groups) reduced bone ash, silica and magnesium as well as bone volume. Charcoal administration increased Ca-content of bones. Aflatoxin feeding (in AN group) resulted in a high residual percentage of AN in muscles, serum, liver, heart and kidneys with relationships of 51 :24 : 3 :2 : 1, respectively. Only 1.42% of the fed AN was excreted in the faeces. Charcoal usage had a good effect as it prevented AN to accumulate in the organs. Aflatoxin contaminated diets (in AN and CC groups) resulted in paralysis, disorder of fat deposition, discolouration and haemorrhages of some organs. Scanning electron microscopic examination revealed no ill effect on the surface structure of the small intestine due to either AN or AN + CC. Pathological examination showed that the main affected organs were liver, heart and spleen, respectively. The changes include hepatic round cell infiltration, irregularities of lobular plats, focal necrosis and periportal fibrosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Adsorption↗

PubMed1990

Occurrence of some mycotoxins (aflatoxin, ochratoxin A, citrinin, zearalenone and vomitoxin) in various Egyptian feeds.

Ninety five samples of various Egyptian feedstuffs were investigated for the aflatoxin B1, B2, G1, and G2 means thin layer chromatography (TLC). Out of these samples 44.2% were positive (maize, rice crack, rice germ, rice germ cake, rice bran, wheat bran, cotton seed, cotton seed cake, peanut, and mixed feed for broilers, egg production, calf fattening and milk production). High percentage (90.5%) of the positive samples were contaminated with less than 100 ppb total aflatoxins. Peanut from "Ismailia" showed the highest contamination-mean of 400 ppb aflatoxin B1. The contamination relationship between kernels and shell of the same pods of the peanut was 1:7. The lowest contamination-mean was 5 ppb B1 in soya bean samples. All samples of horse bean and fish meal were negative. Aflatoxin B1 was present alone so frequently (in 76.2% of the positive samples). The relationship between the concentrations of aflatoxins B2:G1:B1 was 1:2.3:22.4. 51 different samples of foods and feeds from various Egyptian regions were collected and investigated for the nephrotoxic mycotoxin ochratoxin A means TLC. Twelve samples (23.5%) from them were designated as positive samples. The positive samples belonged to white maize, wheat, wheat bran, beans, rice germ, rice germ cake, broilers feed, egg production feed, and milk production feed; whereas the yellow maize (hybrid), soya beans, wheat soya meal, rice crack, cotton seed, cotton seed cake, and fish meal samples were negative. The contamination range was from 4 ppb to 577 ppb with an average of 58.2 +/- 22.9 ppb. Half of the positive samples was contaminated with 10-100 ppb whereas 41.7% from the positive samples had less than 10 ppb and 8.3% only had more than 100 ppb. Citrinin is existing in Egyptian food and feedstuffs. Out of 52 different samples--from various Egyptian regions-15.4% were positive. These were rice bran, rice germ, maize (white), wheat bran, cotton seed cake and fish meal. The highest contamination was in fish meal (40-70 ppb) whereas the lowest was in wheat bran (3 ppb). Mean of the contamination level was 25.9 +/- 3.4 ppb with a range of 3-70 ppb. For the first time in the Egyptian foods and feeds will be informed about the presence of the mycotoxin zearalenone with a high concentration. From several Egyptian places, 64 samples were collected (4 samples for each food or feed stuff).(ABSTRACT TRUNCATED AT 400 WORDS)

Aflatoxins↗

PubMed2003

Influence of ascorbic acid supplementation on the haematological and clinical biochemistry parameters of male rabbits exposed to aflatoxin B1.

This study was undertaken to evaluate the effectiveness of L-ascorbic acid (AA) in alleviating the toxicity of aflatoxin B1 (AFB1) in male New-Zealand white rabbits. Five rabbits (6 months of age and mean body weight 3.12 kg) per group were assigned to 1 of 6 treatment groups: 0 mg AA and 0 mg AFB1/kg BW (control); 20 mg AA/kg BW; 15 microg AFB1/kg BW; 15 microg AFB1 plus 20 mg AA/kg BW; 30 pg AFB1/kg BW; 30 pg AFB1 plus 20 mg AA/kg BW. Rabbits were orally administered their respective doses every other day for 9 weeks, followed by a 9-week recovery period where all drugs were withdrawn. Evaluations were made for hemato-biochemical parameters and enzymatic activities. Results showed that AFB1 significantly (p < 0.05) decreased hemoglobin (Hb), total erythrocytic count (TEC) and packed cell volume (PCV), in a dose-dependent manner, and these effects were continued during the recovery period. Ascorbic acid caused an increase in these parameters, and alleviated the negative effect of AFB1 during the treatment period. Additionally, serum concentrations of total protein, albumin and glucose were significantly (P < 0.05) declined by treatment with the high dose of aflatoxin and these effects were continued during the recovery period. Ascorbic acid caused non-significant increases in these parameters and alleviated the harmful effect of AFB1. On the other hand, aflatoxin treatment caused significant increases (P < 0.05) in the activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (AlP) during the treatment period in a dose dependent manner, and this effect was continued during the recovery period, especially with the high dose. Also, treatment with the high dose of aflatoxin caused significant increases (P<0.05) in cholesterol and total bilirubin. Ascorbic acid caused significant decreases in these parameters and alleviated the harmful effects of AFB1. Whereas, Total leukocyte count (TLC), urea and creatinine were not significantly affected by aflatoxin-treatment. Generally, it is interesting feature that the treatment with AA alone had no negative effects on most of the previous parameters. Also, the presence of AA could diminished the adverse effects of AFB1 on most of hematological and biochemical values, and enzymatic activities in rabbits.

Administration, Oral↗

PubMed1992

Aflatoxin B1--DNA adduct formation in rat liver following exposure by aerosol inhalation.

There is growing concern that human exposure to respirable grain dust contaminated with aflatoxin B1 (AFB1), a potent hepatocarcinogen, may be a risk factor for a number of human diseases. The objective of this study was to determine if liver DNA adduct formation occurs in rats following either intratracheal injection or nose-only aerosol inhalation exposure to AFB1. Male Fischer 344 rats were exposed by both routes of administration, and in preliminary data using intratracheal instillation, up to 2% of the administered dose became bound to liver DNA. In the nose-only aerosol inhalation experiments, rats were exposed for up to 120 min. Immediately after exposure, four animals were killed at each time point and their livers removed, DNA isolated and purified and analyzed for aflatoxin-DNA adducts by HPLC. A linear dose-response relationship was observed with a correlation coefficient of 0.96 between increasing length of exposure, and the amount of aflatoxin-N7-guanine adducts formed per mg DNA, the mean values and standard errors were 4.2 +/- 0.18, 15.3 +/- 4.3, 21.6 +/- 2.8 and 56.8 +/- 4.6 pmol aflatoxin-DNA adducts per mg DNA for the 20, 40, 60 and 120 min exposures respectively. The amounts of aflatoxin-DNA adducts formed were statistically significantly different (P less than 0.01) among the treated groups. These results indicate that aerosol inhalation is an effective route of exposure to AFB1 in rats that results in genotoxic damage in the liver.

Administration, Inhalation↗

PubMed1982

Photoactivated aflatoxins are mutagens to Salmonella typhimurium and bind covalently to DNA in vitro.

The mutagenesis of Salmonella typhimurium TA100 and covalent binding in vitro of photoactivated aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) were investigated. Covalent binding levels of 1140, 225, 330 and 8 pmol aflatoxin per mumol nucleotide phosphate were obtained for AFB1, AFG1, AFB2 and AFG2, respectively, at 50 microM mycotoxin after 2 h of irradiation. Mutant frequencies to histidine prototrophy wre 97, 19, 49 and 0 x 10(-6) for AFB1, AFG1, AFB2 and AFG2 respectively, after 2 h irradiation at 100 microM mycotoxin in the surviving fraction of the mutagenized cultures. Toxicity to Salmonella was 0.59, 0.03, 0.31 and 0 lethal hits under the conditions specified for mutagenesis for AFB1, AFG1, AFB2 and AFG2, respectively.

Aflatoxins↗

PubMed1975

Influence of riboflavin on disturbances in trytophan metabolism and hepatoma production after a single dose of aflatoxin B1.

Female Wistar rats were given a single oral dose of aflatoxin B1, either alone or with a large amount of riboflavin. Biochemical and histologic studies were performed for 30 months. Nine animals of 19 in the aflatoxin-treated group and only 5 of 18 in the riboflavin-aflatoxin-treated group developed hepatomas. The number of rats was insufficient for tests of statistical significance to be fruitful. Urinary excretion of tryptophan metabolites was studied in aflatoxin- and riboflavin-treated rats after an oral administration of 10 mg tryptophan/100 g rat. Riboflavin did not affect the percentage of aflatoxin-treated animals with abnormal urinary excretion patterns, but did increase the magnitude of the disturbances in elimination of kynurenic and xanthurenic acids. The hepatic tryptophan-oxygenase activity was increased only in the two groups given riboflavin, and the levels of nucleic acids were the same in all groups.

Aflatoxins↗

PubMed1979

Aflatoxins and anthraquinones from diploids of Aspergillus parasiticus.

Three spore colour, two mycelial colour and 12 auxotrophic mutants were isolated from an aflatoxigenic strain of Aspergillus parasiticus. These mutants and heterozygous diploids formed by pairwise combinations of auxotrophs were assayed for aflatoxin production; norsolorinic acid and versicolorin A production were also assayed in the diploids. In general, introduction of an auxotrophic marker lowered aflatoxin production in haploids. The green-spored, prototrophic diploids resembled haploid wild-type strains in that they produced high levels of aflatoxin, low levels of versicolorin A, and no detectable norsolorinic acid. Parasexual analysis of segregants from four heterozygous diploids was hampered by the uniform conidiospore diameter of haploids and diploids and by the non-random recovery of genotypes among somatic segregants with and without treatment with p-fluorophenylalanine. Nevertheless, this technique is useful for recombinational analysis of mutants blocked in aflatoxin synthesis. The fortuitous association of mycelial pigmentation with certain blocked aflatoxin mutants should prove useful in future analyses of the genetics and biosynthesis of these economically important secondary metabolites.

Aflatoxins↗

PubMed1986

Pyridine nucleotides and redox state regulation of aflatoxin biosynthesis in Aspergillus parasiticus NRRL 3240.

In vivo regulation of lipid and aflatoxin biosynthesis by pyridine nucleotides and their derived functions was studied in Aspergillus parasiticus NRRL 3240. Aflatoxins, total lipids and pyridine nucleotide content were estimated under different growth conditions. Aflatoxin formation was highest in cultures grown in sucrose-low salts medium followed by asparagine- and zinc-deficient media. The lipid content of the cultures followed an inverse pattern. The levels of oxidized nucleotides decreased with age under all culture conditions employed. Concentrations of NADPH peaked before the onset of aflatoxin biosynthesis. For each medium used, the estimated catabolite reduction charge was constant at all stages of growth whereas the anabolic reduction charge varied. A direct relationship between the level of extracellular ammonium ions and anabolic reduction charge was established. A high anabolic reduction charge was associated with increased lipid biosynthesis rather than aflatoxin biosynthesis.

Aflatoxins↗

PubMed2005

Metal ions modulate gene expression and accumulation of the mycotoxins aflatoxin and zearalenone.

AIMS: To determine the modulating action of some metal ions (Zn+2, Fe+2, Cu+2) on gene expression of enzymes related to fungal growth and accumulation of the mycotoxins aflatoxin and zearalenone. METHODS AND RESULTS: The effect of the metal ions, as single or mixed treatments, was observed in submerged cultures of toxigenic Aspergillus flavus or Fusarium graminearum, which produce the mycotoxins aflatoxin or zearalenone, respectively. The enzyme-linked immunosorbent assay results showed that the single metals Zn+2 or Cu+2 stimulated aflatoxin accumulation while Cu+2 or Fe+2 stimulated zearalenone in fungal cultures. Single Zn+2 treatment also affected conidial differentiation and pigmentation. A cDNA suppression subtractive library was also produced and followed by sequencing of potential metal treatment-specific clones, thus determining induced genes. The genes uncovered included enzymes and regulators of cell growth and division, including many genes with unknown functions were uncovered. A Northern blot analysis was used to verify the expression pattern of the corresponding genes under metal treatment. The metal ions enhanced the expression of alcohol dehydrogenase Adh1 homologue by up to 33-fold in A. flavus and ca fourfold in F. graminearum. Encoding homologues of a neutral amino acid permease, were also used in the Northern analysis. However, the expression of the permease was not significantly affected by metal ion treatments. CONCLUSIONS: The results showed a significant effect of metal ions on expression of gene related to fungal growth, development, conidiation and production of both aflatoxin and zearalenone. SIGNIFICANT AND IMPACT OF THE STUDY: At the molecular and cellular level, the significant effects of metal ions on fungal growth and development, conidiation, and production of both aflatoxin and zearalenone were demonstrated.

Aflatoxins↗

PubMedDate not supplied

Aflatoxin and p53 abnormality in duck hepatocellular carcinoma.

Recent studies have revealed that a point mutation at codon 249 in the p53 gene predominates in hepatocellular carcinoma (HCC) cases from Southern Africa and China, where infection with hepatitis B virus (HBV) and contamination of aflatoxin B1 in food are risk factors for HCC. This unique mutation from G to T at the third base in codon 249 observed in human HCC cases is suggested to be linked to aflatoxin exposure. Six ducks with HCC, five of which were fed a diet containing aflatoxin B1 for 1-2 years, were analysed for the presence of point mutations at this codon of the p53 gene by polymerase chain reaction and direct nucleotide sequencing. None of the six ducks with HCC showed the change at this codon regardless of duck hepatitis B virus infection. This suggests that aflatoxin B1 itself might not be involved in the unique mutation at codon 249 in hepatocarcinogenesis, or that other factors coincident with aflatoxin may be responsible for this unique mutation.

Aflatoxin B1↗

PubMed1993

Risk assessment for aflatoxin: an evaluation based on the multistage model.

Lifetime cancer potency of aflatoxin was assessed based on the Yeh et al. study from China in which both aflatoxin exposure and hepatitis B prevalence were measured. This study provides the best available information for estimating the carcinogenic risk posed by aflatoxin to the U.S. population. Cancer potency of aflatoxin was estimated using a biologically motivated risk assessment model. The best estimate of aflatoxin potency was 9 (mg/kg/day)-1 for individuals negative for hepatitis B and 230 (mg/kg/day)-1 for individuals positive for hepatitis B.

Adult↗

PubMed1998

Genetic organization and function of the aflatoxin B1 biosynthetic genes.

Aflatoxins are secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Most of the genes involved in the biosynthesis of aflatoxin are contained within a single cluster in the genome of these filamentous fungi. Studies directed toward understanding the molecular biology of aflatoxin biosynthesis have led to a number of important discoveries. A pair of fatty acid synthase genes were identified that are involved uniquely in aflatoxin biosynthesis. Two genes were also characterized that represent new families of cytochrome P450 monooxygenases. Gene expression is coordinated during aflatoxin production and is under the control of a positive regulatory gene belonging to a family of fungal transcriptional activators associated with various metabolic pathways in fungi.

Aflatoxin B1↗