Aflatoxins in liver biopsies from Sudanese children

Difference between kwashiorkor and marasmus: Comparative meta-analysis of pathogenic characteristics and implications for treatment

Kwashiorkor and marasmus are two clinical syndromes observed in severe acute malnutrition. In this review, we highlighted the differences between these two syndromes by reviewing the data comparing kwashiorkor and marasmus in literature, combined with recent microbiological findings and meta-analysis. Depletion of antioxidants, vitamins and minerals were more severe in kwashiorkor than marasmus. This was consistent with the severe and uncontrolled oxidative stress associated with the depletion of gut anaerobes and the relative proliferation of aerotolerant gut pathogens. This relative proliferation and invasion of gut microbes belonging to the aerotolerant Proteobacteria phylum and pathogens suggested a specific microbial process critical in the pathogenesis of kwashiorkor. Liver mitochondrial and peroxisomal dysfunction could be secondary to toxic microbial compounds produced in the gut such as ethanol, lipopolysaccharides and endotoxins produced by Proteobacteria, particularly Klebsiella pneumoniae, and aflatoxin produced by Aspergillus species. The gut-liver axis alteration is characterized by oedema and a fatty and enlarged liver and was associated with a dramatic depletion of methionine and glutathione, an excessive level of free circulating iron and frequent lethal bacteraemia by enteric pathogens. This was consistent with the fact that antibiotics improved survival only in children with kwashiorkor but not marasmus. The specific pathogenic characteristics of kwashiorkor identified in this review open new avenues to develop more targeted and effective treatments for both marasmus and/or kwashiorkor. Urgent correction of plasma glutathione depletion, alongside supply of specific essential amino acids, particularly methionine and cysteine, early detection of pathogens and an antibiotic more efficient than amoxicillin in supressing gut Proteobacteria including K. pneumoniae, and probiotics to restore the human gut anaerobic mature microbiota could save many more children with kwashiorkor.

Aflatoxin M1 in Africa: Exposure Assessment, Regulations, and Prevention Strategies - A Review

Aflatoxins are the most harmful mycotoxins causing health problems to human and animal. Many acute aflatoxin outbreaks have been reported in Africa, especially in Kenya and Tanzania. When ingested, aflatoxin B1 is converted by hydroxylation in the liver into aflatoxin M1, which is excreted in milk of dairy females and in urine of exposed populations. This review aims to highlight the AFM1 studies carried out in African regions (North Africa, East Africa, West Africa, Central Africa, and Southern Africa), particularly AFM1 occurrence in milk and dairy products, and in human biological fluids (breast milk, serum, and urine) of the populations exposed. Strategies for AFM1 detoxification will be considered, as well as AFM1 regulations as compared to the legislation adopted worldwide and the assessment of AFM1 exposure of some African populations. Egypt, Kenya, and Nigeria have the highest number of investigations on AFM1 in the continent. Indeed, some reports showed that 100% of the samples analyzed exceeded the EU regulations (50 ng/kg), especially in Zimbabwe, Nigeria, Sudan, and Egypt. Furthermore, AFM1 levels up to 8,000, 6,999, 6,900, and 2040 ng/kg have been reported in milk from Egypt, Kenya, Sudan, and Nigeria, respectively. Data on AFM1 occurrence in human biological fluids have also shown that exposure of African populations is mainly due to milk intake and breastfeeding, with 85-100% of children being exposed to high levels. Food fermentation in Africa has been tried for AFM1 detoxification strategies. Few African countries have set regulations for AFM1 in milk and derivatives, generally similar to those of the Codex alimentarius, the US or the EU standards.

Presence of unreported carcinogens, Aflatoxins and their hydroxylated metabolites, in industrialized Oaxaca cheese from Mexico City

Aflatoxins (AFs) are toxic secondary metabolites of the fungi Aspergillus flavus, A. parasiticus and A. nomius. The fungi produce these AFs in cereals, oilseeds and spices. AFs have damaging effects on all organisms, including humans, and their symptoms can be classified as acute (vomiting, hemorrhage and death) or chronic (immunodepression, Reye syndrome, Kwashiorkor, teratogenesis, hepatitis, cirrhosis, and various cancers). Basic AFs (AFB₁, AFB₂, AFG₁, and AFG₂) are metabolized in the liver or by microbes that produce hydroxylated metabolites (AFM₁, AFM₂, and AFP₁) and aflatoxicol (AFL), soluble in water and easy to dispose. Thus, AFs can be excreted in fluids, such as milk. AFs are not destroyed in the process of making cheese. The purpose of this study was to identify and quantify the AFs present in 30 samples of industrialized Oaxaca-type cheese sold in Mexico City. The average concentrations of AFs detected in the 30 samples of industrialized cheese were as follows: AFB₁ (0.1 μg kg^-1) in 20% (6/30); a trace amount of AFB₂ (0.01 < LOD) in only 3% (1/30); AFG₁ (0.14 μg kg^-1) in 10% (3/30); AFG₂ (0.6 μg kg^-1) in 30% (9/30); AFM₁ (1.7 μg kg^-1) in 57% (17/30); AFP₁ (0.03% μg kg^-1) in 3% (1/30); and AFL (13.1 μg kg^-1) in 97% (29/30). AFB₁ and AFL were the most abundant aflatoxins in Oaxaca-type cheese. However, eight aflatoxins were present, contributing an average of 15.7 μg kg^-1 AFs distributed among the 30 samples. The risk assessment analysis showed that there was no substantial risk for cancer due to AFs in industrialized Oaxaca cheese from Mexico City.

Association of high viral load and abnormal liver function with high aflatoxin B1-albumin adduct levels in HIV-positive Ghanaians: preliminary observations

We examined the association between certain clinical factors and aflatoxin B(1)-albumin adduct (AF-ALB) levels in HIV-positive people. Plasma samples collected from 314 (155 HIV-positive and 159 HIV-negative) people were tested for AF-ALB levels, viral load, CD4+ T-cell count, liver function profile, malaria parasitaemia, and hepatitis B and C virus infections. HIV-positive participants were divided into high and low groups based on their median AF-ALB of 0.93 pmol mg(-1) albumin and multivariable logistic and linear regression methods used to assess relationships between clinical conditions and AF-ALB levels. Multivariable logistic regression showed statistically significant increased odds of having higher HIV viral loads (OR=2.84; 95% CI=1.17-7.78) and higher direct bilirubin levels (OR=5.47; 95% CI=1.03-22.85) among HIV-positive participants in the high AF-ALB group. There were also higher levels of total bilirubin and lower levels of albumin in association with high AF-ALB. Thus, aflatoxin exposure may contribute to high viral loads and abnormal liver function in HIV-positive people and so promote disease progression.

Assessment of exposure of Egyptian infants to aflatoxin M1 through breast milk

BACKGROUND

Mothers are exposed to many toxins that can reach their infants through breast milk. One of these toxins is aflatoxins, produced by Aspergillus fungus. Aspergillus colonizes grains, especially in tropical regions where there is high temperature and humidity. Aflatoxins are highly toxic, mutagenic, teratogenic, and carcinogenic. One of these is aflatoxin B1 that is excreted in breast milk as aflatoxin M1 (AFM1).

MATERIALS AND METHODS

This is a cross-sectional study in which 150 mother-infant dyads were included. All the infants were exclusively breastfed. Infant weights' standard deviation scores were documented at birth and at 6 months. At 6 months, before starting weaning, AFM1 was measured in breast milk by enzyme-linked immunosorbent assay and by liver enzymes; alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for all mothers and infants.

RESULTS

Ninety-eight mothers (65.3%) had AFM1-positive breast milk samples (AFM1>0.05 μg/l according to the European Community and Codex Alimentarius). AFM1 levels ranged between 0.2 and 19.0 μg/l (mean: 7.1±5.0 μg/l). In cases considered negative, AFM1 levels ranged between 0.01and 0.05 μg/l (mean: 0.04±0.01 μg/l). Infants of AFM1-positive mothers had lower weight standard deviation scores at birth and at 6 months (P=0.04 and 0.0001). ALT and aspartate aminotransferase of mothers and ALT of infants were significantly higher in dyads having AFM1-positive breast milk (P=0.0001, 0.0001, and 0.03, respectively).

CONCLUSION

Aflatoxins represent a real threat in Egypt. The higher liver enzymes in AFM1-positive cases might represent an alarm toward future development of hepatocellular carcinoma.

RECOMMENDATIONS

Cooperation of ministries is recommended to combat this problem. The public should be educated about proper food storage and about the hazards of aflatoxin ingestion.

A reappraisal of fungi producing aflatoxins

Aflatoxins are decaketide-derived secondary metabolites which are produced by a complex biosynthetic pathway. Aflatoxins are among the economically most important mycotoxins. Aflatoxin B1 exhibits hepatocarcinogenic and hepatotoxic properties, and is frequently referred to as the most potent naturally occurring carcinogen. Acute aflatoxicosis epidemics occur in several parts of Asia and Africa leading to the death of several hundred people. Aflatoxin production has incorrectly been claimed for a long list of Aspergillus species and also for species assigned to other fungal genera. Recent data indicate that aflatoxins are produced by 13 species assigned to three sections of the genus Aspergillus: section Flavi (A. flavus, A. pseudotamarii, A. parasiticus, A. nomius, A. bombycis, A. parvisclerotigenus, A. minisclerotigenes, A. arachidicola), section Nidulantes (Emericella astellata, E. venezuelensis, E. olivicola) and section Ochraceorosei (A. ochraceoroseus, A. rambellii). Several species claimed to produce aflatoxins have been synonymised with other aflatoxin producers, including A. toxicarius (=A. parasiticus), A. flavus var. columnaris (=A. flavus) or A. zhaoqingensis (=A. nomius). Compounds with related structures include sterigmatocystin, an intermediate of aflatoxin biosynthesis produced by several Aspergilli and species assigned to other genera, and dothistromin produced by a range of non-Aspergillus species. In this review, we wish to give an overview of aflatoxin production including the list of species incorrectly identified as aflatoxin producers, and provide short descriptions of the 'true' aflatoxin producing species.

Prevalence of Aflatoxins in Blood and Urine of Egyptian Infants with Protein–Energy Malnutrition

The aim of the present work was to study the presence of aflatoxins in blood and urine of infants with protein–energy malnutrition (PEM). The study was conducted on 60 infants, 30 with kwashiorkor and 30 with marasmus, with 10 age-matched healthy infants studied as a control group. Complete blood count, liver function tests, and determination of the level of aflatoxins (B1, B2, G1, G2, M1, M2, G2a, B3, GM1, P, and aflatoxicol R0) in blood and urine were carried out in all studied infants. Serum aflatoxins were detected in more infants with kwashiorkor (80%) than in those with marasmus (46.7%). The mean serum levels of total aflatoxins, AFB1, AFG1, and AFB2a, were significantly higher in infants with kwashiorkor (p <.001). Aflatoxin B1 (AFB1) was the most commonly detected type. The prevalence of aflatoxin excretion in the urine of infants with kwashiorkor was 80%, a higher value than that in infants with marasmus (46.7%). The mean urinary concentration of total aflatoxins followed the same pattern of distribution (p < .052). There were no significant differences between groups in the mean urinary concentrations of AFB1, AFG1, AFB2a, AFM1, and AFG2a. Aflatoxins were not detected in any of the serum or urine samples of the control group. Aflatoxins are highly prevalent in this study population and show a high degree of correlation with severe PEM.

Aflatoxins in the lungs of children with kwashiorkor and children with miscellaneous diseases in Nigeria

Autopsy lung specimens from 20 children with kwashiorkor and 20 with other miscellaneous diseases, at the Obafemi Awolowo Teaching Hospital complex, Ile-Ife, Nigeria, were analyzed for the presence of aflatoxin using high-performance liquid chromatography. Aflatoxins were detected in 18 children who died from kwashiorkor but only in 13 of those who died from miscellaneous diseases. Of the 10 children, 5 in each group, who died with pneumonia, all had detectable levels of aflatoxins in their lungs. The two children with congestive cardiac failure, one secondary to pneumonia and the other secondary to tuberculous pericarditis, had more than two detectable aflatoxins in their lungs. These findings demonstrate that Nigerian children are exposed to aflatoxins and that high levels can accumulate in lung tissue.

Aflatoxin exposure in Singapore: blood aflatoxin levels in normal subjects, hepatitis B virus carriers and primary hepatocellular carcinoma patients

Blood screening conducted on Singaporeans over 1991-1992 showed exposure to predominantly aflatoxin B1 and to a lesser extent G1. The extent of exposure to B1 among three groups of residents in Singapore, namely normal subjects (n = 423), hepatitis B virus carriers (n = 302) and primary hepatocellular carcinoma (PHC) patients (n = 58) were extensive as reflected by the positive rates of 15.1, 0.7 and 1.7 per cent respectively. However, the degree of individual exposure to this toxin among the three groups was considered low as shown by the low respective mean blood levels of 5.4 +/- 3.2 (range 3.0-17), 7.7 (range 7.5-7.9) and 7.5 picogrammes per ml of blood. It is not immediately clear whether or not such low levels would precipitate an undesirable health effect. The higher positive rate seen in normal subjects as compared with the other groups could be due to differences in dietary intake of aflatoxin B1, differences in metabolic patterns or both. About 70 per cent of PHC patients studied were carriers. The degree of aflatoxin B1 exposure among normal subjects in Singapore was a factor of 22.1 times less than that in Japan, 40.9 times less than that in Indonesia and 51.3 times less than that in the Philippines. Similarly, the extent of exposure among hepatitis B carriers in Singapore was a factor of 8.2 times, 39.6 times and 24.2 times less than those in the other three Asiatic countries respectively. The results reflected stringent Government control over the quality of food stuff imported into this country. As Singapore imports almost all of its dietary needs from elsewhere, it can afford to be selective at a cost. Aflatoxin M1, a metabolite of B1, was most commonly encountered in the liver tissues of deceased (n = 154) who died of causes other than sickness or disease in 1992-93, consistent with our blood findings of prevalence of aflatoxin B1. High performance liquid chromatography (HPLC) with fluorescence detection using one of the aflatoxins G2 or B2 as an internal standard was used for the detection and quantification of aflatoxins. The use of an internal standard structurally and chemically similar to those required to be quantified minimizes errors in quantifications. This is because differences in the quenching of fluorescence between specimen extracts and spiked-standard extracts were internally standardized and compensated for. The presence of an internal standard also helped to locate aflatoxins of interest more accurately.(ABSTRACT TRUNCATED AT 400 WORDS)

Aflatoxin excretion in children with kwashiorkor or marasmic kwashiorkor--a clinical investigation

A group of five children with kwashiorkor, seven with marasmic kwashiorkor and one underweight child were given an aflatoxin-free diet consisting of maize meal and milk powder. Blood specimens were collected on admission; on day 4 and 10, 24 hour urine and stool samples were collected for the first ten days. Serum, urine and stool samples were analysed for aflatoxins using high performance liquid chromatography with fluorescent detection, after various extraction and clean-up procedures. The children with kwashiorkor and marasmic kwashiorkor excreted aflatoxins in stools for up to 9 and 6 days after admission respectively. No aflatoxins were detected in the stools or urine of the underweight child. In kwashiorkor, urinary excretion ceased after 2 days, while in marasmic kwashiorkor urinary excretion persisted for 4 days. In stools, B1 was the type of aflatoxin detected most frequently in kwashiorkor and least frequently in marasmic kwashiorkor. Aflatoxin M2 was frequently detected in the stools of both groups of children. Estimates of the total amount of aflatoxin excreted by kwashiorkor and marasmic kwashiorkor indicate that these children were harbouring up to 4 micrograms/kg body weight at the time of admission. These findings establish that aflatoxins accumulate in body fluids and tissues in kwashiorkor and marasmic kwashiorkor which is only slowly eliminated.

Aflatoxins and kwashiorkor: clinical studies in Sudanese children

Aflatoxin analysis of blood and urine by high performance liquid chromatography in 584 Sudanese children is reported. The results in 404 malnourished children comprising 141 kwashiorkor, 111 marasmic kwashiorkor and 152 with marasmus are compared with 180 age-matched controls and correlated with clinical findings. The aflatoxin detection rate and mean concentration were higher in serum of children with kwashiorkor than the other groups. The difference between the detection rate in kwashiorkor and controls was significant (p less than 0.05). The aflatoxin detection rate in urine was highest in the marasmic kwashiorkor group and the mean concentration was higher in the marasmic kwashiorkor and marasmic groups than in the kwashiorkor and control groups. There were important differences in the detection of certain aflatoxins between the groups. Aflatoxicol was detected in the sera of 16 (11.6%) kwashiorkor, in six (6.1%) marasmic kwashiorkor, but in none of the controls and only once in marasmus. These differences are highly significant (p less than 0.0001). The ratio of AFB1 to AFM1 was higher in the sera and urines of kwashiorkors than in controls, suggesting that the normal transformation of AFB1 to AFM1 may be impaired in kwashiorkor with consequent increase in transformation of AFB1 to aflatoxicol. The study therefore provides evidence of differences in the metabolism of aflatoxins in children with kwashiorkor compared with children with other forms of malnutrition and normally nourished children and confirms the association between aflatoxins and kwashiorkor contained in a preliminary report on this work.