Aflatoxins, hepatocellular carcinoma and public health

Aflatoxin in household maize for human consumption in Kenya, East Africa

The objective of this study is to determine the occurrence and level of aflatoxins (AFs) contamination in freshly harvested maize for human consumption in rural Kenya. Maize kernels and freshly milled maize flour (n = 338) were collected from households in Siaya and Makueni counties. While both counties are representatives of different environmental and climate conditions, Makueni County is the area with reported outbreaks of aflatoxicosis. Samples were analysed for AFB₁, AFB₂, AFG₁, and AFG₂ using Ultra High-Pressure Liquid Chromatography with Fluorescence detection. AFs were detected in 100% of the samples with the range of 2.14-411 µg/kg. The geometric mean of total AFs in all samples from Makueni County is 62.5 μg/kg with 95% CI: 53.7, 71.4 while in Siaya County is 52.8 μg/kg with 95% CI: 44.0, 61.7. This study showed that AFs contamination is prevalent in maize-based foods in the region.

Global scientific trends on aflatoxin research during 1998-2017: a bibliometric and visualized study

BACKGROUND

Aflatoxins are fungal metabolites associated with contaminated food products. Intake of aflatoxin-contaminated food results in serious health hazards and even death. Therefore, the aim of this study is to evaluate the global scientific output of research of aflatoxin by using bibliometric techniques.

METHODS

This bibliometric study was conducted using Scopus database and classified the retrieved publications were classified from different aspects, including the countries/region of focus, journals, authors, institutes, citations, and content analysis to discover any hot and emerging topics. In addition, the bibliometric analysis of the international collaborative network and hot research topics were generated by VOSviewer© software version 1.6.10. The publication period was restricted in the search for two decades (1998-2017).

RESULTS

The search engine of the Scopus database found 9845 documents published in the field of aflatoxin. The USA is the top publishing source in the world (22.85%), followed by China (11.85%), India (9.32%), and Italy (5.25%). In earlier years, researchers focused on terms related to the topics of "sources and biosynthesis of aflatoxin", "health effects by aflatoxin", and "detoxification and treatment of aflatoxin". However, in recent years, researchers pay more attention to the topic of detection and quantification of aflatoxin.

CONCLUSIONS

The quantity of research in global aflatoxin has substantially increased over the past two decades. The evaluation of the historical status and development trend in aflatoxin scientific research can guide future research, and ultimately provide the basis for improving management procedures for governmental decisions, healthcare, industries, and educational institutions.

Antifungal and antiaflatoxigenic activity of rosemary essential oil (Rosmarinus officinalis L.) against Aspergillus flavus

The increased risk to health by diverse pathologies, such as cancer, liver diseases, and endocrine alterations, caused by chemical residues in food, has led to the search for sustainable agricultural management alternatives, such as the use of essential oils for the development of natural and eco-friendly fungicides. The aim of this study was to evaluate the antifungal and antiaflatoxigenic activity of Rosmarinus officinalis L. essential oil (REO) against Aspergillus flavus Link. REO was obtained by hydrodistillation and its major components were identified as 1,8-cineole (eucalyptol, 52.2%), camphor (15.2%) and α-pinene (12.4%) by GC/MS and NMR. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were both 500 µg/mL. REO reduced the mycelial growth of A. flavus at a concentration of 250 µg/mL (15.3%). The results obtained from scanning electron microscopy (SEM) demonstrated a reduction in the size of conidiophores and in the thickness of hyphae in A. flavus caused by treatment with REO (250 µg/mL). The production of ergosterol and the biomass of mycelium were both reduced as the REO treatment concentration increased. The production of aflatoxins B₁ and B₂ was inhibited after treatment with 250 µg/mL REO, a concentration below the MIC/MFC, indicating that the antiaflatoxigenic effect of REO is independent of its antifungal effect and is likely due to its direct action upon toxin biosynthesis. The data demonstrated that REO may be used as an alternative to synthetic fungicides.

Aflatoxin levels in maize and peanut and blood in women and children: The case of Timor-Leste

Aflatoxins are toxic fungal metabolites produced by Aspergillus sp. with carcinogenic properties that are a common food contaminant of many crops including maize and peanuts. In Timor-Leste malnutrition and children's stunting are frequent and maize and peanuts are staple foods. This study aimed to provide information on aflatoxin exposure nationally. The study measured levels of aflatoxin in locally-produced maize and peanuts (296 samples) and of aflatoxin-albumin conjugate in blood samples of women and young children (514 and 620 respectively) across all municipalities. The average concentration of aflatoxin in the grain samples was low with most maize (88%) and peanut (92%) samples - lower than European Commission tolerated aflatoxin level. Although aflatoxin-albumin conjugate was detected in more than 80% of blood samples, the average concentration in children and adults of 0.64 and 0.98 pg mg^-1 alb, respectively, is much lower than in other similar rural-based countries. Although low in concentration, blood aflatoxin levels and aflatoxin contamination levels in maize across municipalities were correlated significantly for mothers (R² = 37%, n = 495) but not for children (R² = 10%). It is unlikely that the consumption of aflatoxin contaminated grain is a causative factor in the current level of malnutrition and stunting affecting Timor-Leste children.

NMR-Based Metabolic Profiles of Intact Zebrafish Embryos Exposed to Aflatoxin B1 Recapitulates Hepatotoxicity and Supports Possible Neurotoxicity

Aflatoxin B1 (AFB1) is a widespread contaminant of grains and other agricultural crops and is globally associated with both acute toxicity and carcinogenicity. In the present study, we utilized nuclear magnetic resonance (NMR), and specifically high-resolution magic angle spin (HRMAS) NMR, coupled to the zebrafish (Danio rerio) embryo toxicological model, to characterize metabolic profiles associated with exposure to AFB1. Exposure to AFB1 was associated with dose-dependent acute toxicity (i.e., lethality) and developmental deformities at micromolar (≤ 2 µM) concentrations. Toxicity of AFB1 was stage-dependent and specifically consistent, in this regard, with a role of the liver and phase I enzyme (i.e., cytochrome P450) bioactivation. Metabolic profiles of intact zebrafish embryos exposed to AFB1 were, furthermore, largely consistent with hepatotoxicity previously reported in mammalian systems including metabolites associated with cytotoxicity (i.e., loss of cellular membrane integrity), glutathione-based detoxification, and multiple pathways associated with the liver including amino acid, lipid, and carbohydrate (i.e., energy) metabolism. Taken together, these metabolic alterations enabled the proposal of an integrated model of the hepatotoxicity of AFB1 in the zebrafish embryo system. Interestingly, changes in amino acid neurotransmitters (i.e., Gly, Glu, and GABA), as a key modulator of neural development, supports a role in recently-reported neurobehavioral and neurodevelopmental effects of AFB1 in the zebrafish embryo model. The present study reinforces not only toxicological pathways of AFB1 (i.e., hepatotoxicity, neurotoxicity), but also multiple metabolites as potential biomarkers of exposure and toxicity. More generally, this underscores the capacity of NMR-based approaches, when coupled to animal models, as a powerful toxicometabolomics tool.

The effects of aflatoxin exposure on Hepatitis B-vaccine induced immunity in Kenyan children

BACKGROUND

Globally, approximately three million children die each year from vaccine preventable infectious diseases mainly in developing countries. Despite the success of the expanded immunization program, not all infants and children around the world develop the same protective immune response to the same vaccine. A vaccine must induce a response over the basal immune response that may be driven by population-specific, environmental or socio-economic factors. Mycotoxins like aflatoxins are immune suppressants that are confirmed to interfere with both cell-mediated and acquired immunity. The mechanism of aflatoxin toxicity is through the binding of the bio-activated AFB1-8, 9-epoxide to cellular macromolecules.

METHODS

We studied Hepatitis B surface antibodies [anti-HBs] levels to explore the immune modulation effects of dietary exposure to aflatoxins in children aged between one and fourteen years in Kenya. Hepatitis B vaccine was introduced for routine administration for Kenyan infants in November 2001. To assess the effects of aflatoxin on immunogenicity of childhood vaccines Aflatoxin B1-lysine in blood serum samples were determined using High Performance Liquid Chromatography with Fluorescence detection while anti-HBs were measured using Bio-ELISA anti-HBs kit.

RESULTS

The mean ± SD of AFB1-lysine adducts in our study population was 45.38 ± 87.03 pg/mg of albumin while the geometric mean was 20.40 pg/mg. The distribution of AFB1-lysine adducts was skewed to the right. Only 98/205 (47.8%) of the study population tested positive for Hepatitis B surface antibodies. From regression analysis, we noted that for every unit rise in serum aflatoxin level, anti-HBs dropped by 0.91 mIU/ml (-0.9110038; 95% C.I -1.604948, -0.21706).

CONCLUSION

Despite high coverage of routine immunization, less than half of the study population had developed immunity to HepB. Exposure to aflatoxin was high and weakly associated with low anti-HBs antibodies. These findings highlight a potentially significant role for environmental factors that may contribute to vaccine effectiveness warranting further research.

Occurrence and Human-Health Impacts of Mycotoxins in Somalia

Mycotoxins are secondary metabolites produced by various molds that contaminate many staple foods and cause a broad range of detrimental health effects in animals and humans through chronic exposure or acute toxicity. As such, the worldwide contamination of food and feed with mycotoxins is a significant problem, especially in sub-Saharan Africa. In this study, mycotoxin occurrence in staple foods consumed in Somalia was determined. A total of 140 samples (42 maize, 40 sorghum, and 58 wheat) were collected from a number of markets in Mogadishu, Somalia, and analyzed by a UPLC-MS/MS multimycotoxin method that could detect 77 toxins. All of the maize samples tested contained eight or more mycotoxins, with aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁) levels reaching up to 908 and 17 322 μg/kg, respectively, greatly exceeding the European Union limits and guidance values. The average probable daily intake of fumonisins (FB₁ and FB₂) was 16.70 μg per kilogram of body weight (kg bw) per day, representing 835% of the recommended provisional maximum tolerable daily intake value of 2 μg/(kg bw)/day. A risk characterization revealed a mean national margin of exposure of 0.62 for AFB₁ with an associated risk of developing primary liver cancer estimated at 75 cancers per year per 100 000 people for white-maize consumption alone. The results clearly indicate that aflatoxin and fumonisin exposure is a major public-health concern and that risk-management actions require prioritization in Somalia.

Hepatocellular Carcinoma: Etiology and Current and Future Drugs

Hepatocellular carcinoma (HCC) is swiftly increasing in prevalence globally with a high mortality rate. The progression of HCC in patients is induced with advanced fibrosis, mainly cirrhosis, and hepatitis. The absence of proper preventive or curative treatment methods encouraged extensive research against HCC to develop new therapeutic strategies. The Food and Drug Administration-approved Nexavar (sorafenib) is used in the treatment of patients with unresectable HCC. In 2017, Stivarga (regorafenib) and Opdivo (nivolumab) got approved for patients with HCC after being treated with sorafenib, and in 2018, Lenvima (lenvatinib) got approved for patients with unresectable HCC. But, owing to the rapid drug resistance development and toxicities, these treatment options are not completely satisfactory. Therefore, there is an urgent need for new systemic combination therapies that target different signaling mechanisms, thereby decreasing the prospect of cancer cells developing resistance to treatment. In this review, HCC etiology and new therapeutic strategies that include currently approved drugs and other potential candidates of HCC such as Milciclib, palbociclib, galunisertib, ipafricept, and ramucirumab are evaluated.

Heavy Metal (Cd and Pb) and Aflatoxin Contamination in Tissues and Eggs from Free Grazing Ducks and Their Environment in Central Thailand

The cross-sectional study of heavy metals and aflatoxins was conducted by studying duck egg, blood, liver, feed, and water samples from 11 free grazing farms. The duck feed, soil, and rice samples were lower than the standard limit for aflatoxins at 20 ng g^-1. The highest levels of aflatoxin were detected in the liver, intestine, and egg yolk; these were 3.04, 1.73, and 4.56 ng g^-1 respectively, while the average levels were 1.6 ± 0.73, 1.31 ± 0.23, and 1.87 ± 0.99 ng g^-1, respectively. Interestingly, aflatoxin was not detected in any of the egg white albumin samples (90/90 samples), whereas aflatoxin contamination was predominantly found in the yolk. Additionally, the means and standard deviations of Pb and Cd found in the duck eggs were 118.61 ± 22.25 and 13.84 ± 9.06 ng g^-1 respectively. The maximum levels of Pb and Cd in eggs were 134.34 and 29.72 ng g^-1, respectively. Moreover, Pb contamination occurred in the duck liver tissue in 93.61% (88/94) of the samples, whereas Cd contamination was found in 100% (100/100). The maximum levels of Pb and Cd in the duck liver tissues were 606.16 and 22,946.20 ng g^-1, which was higher than those in the eggs. Pb contamination in the water from rice paddy fields after grazing was significantly higher than that in water samples taken before grazing. This is the first report of Pb and Cd contamination in blood, egg, and liver samples of free grazing ducks in Thailand.

Aflatoxin B1 induced multiple epigenetic modulators in human epithelial cell lines

The compulsive and insidious secondary metabolite aflatoxin B₁, produced by the opportunistic fungi Aspergillus flavus, upholds a distinguished place in midst of the toxicants causing fatal hazards to humans. Aflatoxins alter the function of host cells by inducing multiple effects through genetic and non-genetic pathways. Epigenetic mechanisms drag major attention towards finding novel and new mechanisms involved in this process. Our present work intends to study the functional expression profile of multiple epigenetic regulators. AFB₁ modulates multiple epigenetic regulators like DNA methyltransferases (DMNTs), histones modifying enzymes and polycomb proteins. AFB₁ upregulates the expression of DNMTs at gene and protein level in a dose dependent manner. It reduced the histone acetyl transferase (HAT) activity significantly with a remarkable increase in histone deacetylase (HDAC) activity along with an induction in expression of HDACs gene and protein in a dose dependent manner. The gene and protein expression of polycomb repressor proteins B cell specific moloney murine leukemia virus integration site 1 (BMI-1) and enhancer of zeste homolog 2 (EZH2) was significantly over expressed with enhanced trimethylation of H3K27 and ubiquitination of H2AK119. In summary, our results show impact of aflatoxin B₁ on multiple epigenetic modulations known to be pivotal in oncogenic processes.

Detection of Aflatoxigenic and Atoxigenic Mexican Aspergillus Strains by the Dichlorvos⁻Ammonia (DV⁻AM) Method

The dichlorvos⁻ammonia (DV⁻AM) method is a sensitive method for distinguishing aflatoxigenic fungi by detecting red (positive) colonies. In this study, the DV⁻AM method was applied for the isolation of aflatoxigenic and atoxigenic fungi from soil samples from a maize field in Mexico. In the first screening, we obtained two isolates from two soil subsamples of 20 independent samples and, in the second screening, we obtained two isolates from one subsample of these. Morphological and phylogenic analyses of the two isolates (MEX-A19-13, MEX-A19-2^nd-5) indicated that they were Aspergillus flavus located in the A. flavus clade. Chemical analyses demonstrated that one isolate could produce B-type aflatoxins, while the other produced no aflatoxins. These results demonstrate that the DV⁻AM method is useful for the isolation of both aflatoxigenic and atoxigenic Aspergilli.

Molecular Insights Into Development and Virulence Determinants of Aspergilli: A Proteomic Perspective

Aspergillus species are the major cause of health concern worldwide in immunocompromised individuals. Opportunistic Aspergilli cause invasive to allergic aspergillosis, whereas non-infectious Aspergilli have contributed to understand the biology of eukaryotic organisms and serve as a model organism. Morphotypes of Aspergilli such as conidia or mycelia/hyphae helped them to survive in favorable or unfavorable environmental conditions. These morphotypes contribute to virulence, pathogenicity and invasion into hosts by excreting proteins, enzymes or toxins. Morphological transition of Aspergillus species has been a critical step to infect host or to colonize on food products. Thus, we reviewed proteins from Aspergilli to understand the biological processes, biochemical, and cellular pathways that are involved in transition and morphogenesis. We majorly analyzed proteomic studies on A. fumigatus, A. flavus, A. terreus, and A. niger to gain insight into mechanisms involved in the transition from conidia to mycelia along with the role of secondary metabolites. Proteome analysis of morphotypes of Aspergilli provided information on key biological pathways required to exit conidial dormancy, consortia of virulent factors and mycotoxins during the transition. The application of proteomic approaches has uncovered the biological processes during development as well as intermediates of secondary metabolite biosynthesis pathway. We listed key proteins/ enzymes or toxins at different morphological types of Aspergillus that could be applicable in discovery of novel therapeutic targets or metabolite based diagnostic markers.

Effects of packaging and pre-storage treatments on aflatoxin production in peanut storage under controlled conditions

This study reports on aflatoxin production and peanut (Bailey's variety) quality, for four peanut pre-storage treatments; [(Raw clean (Raw-Cl), Raw inoculated with Aspergillus flavus NRRL 3357 (Raw-Inf), inoculated partially roasted but not-blanched (PRN-blanch); and inoculated partially roasted, blanched with discolored nuts sorted out (PR-blanched)]. All four treated samples were packaged in four different packaging systems [polypropylene woven sacks (PS), hermetic packs (HP), hermetic packs with oxygen absorbers (HPO), and vacuumed hermetic packs (HPV)] and stored under controlled conditions at a temperature of 30 ± 1 °C and water activity of 0.85 ± 0.02, for 14 weeks. Raw-Inf samples in PS had a higher fungal growth with a mean value of 8.01 × 10⁴ CFU/g, compared to the mean values of samples in hermetic packs: 1.07 × 10³ CFU/g for HP, 14.55 CFU/g for HPO, and 57.82 CFU/g for HPV. Similarly, the hermetic bags were able to reduce aflatoxin level of the Raw-Inf samples by 50.6% (HP), 63.0% (HPV), and 66.8% (HPO). Partial roasting and blanching in PS also reduced aflatoxin level by about 74.6%. Quality maintenance was the best for peanuts in HPO, recording peroxide value (PV) of 10.16 meq/kg and p-Anisidine (p-Av) of 3.95 meq/kg compared to samples in polypropylene woven sacks which had PV of 19.25 meq/kg and p-Av of 6.48 meq/kg. These results indicate that using zero-oxygen hermetic packaging, instead of the conventional polypropylene woven sacks, helped to suppress aflatoxin production and quality deterioration. Also, partially roasted, blanched and sorted peanuts showed a potential for reducing aflatoxin presence during storage.

Projections of primary liver cancer to 2030 in 30 countries worldwide

Primary liver cancer (PLC) is the sixth most common cancer worldwide and the second most common cause of cancer death. Future predictions can inform health planners and raise awareness of the need for cancer control action. We predicted the future burden of PLC in 30 countries around 2030. Incident cases of PLC (International Classification of Diseases, Tenth Revision, C22) were obtained from 30 countries for 1993-2007. We projected new PLC cases to 2030 using age-period-cohort models (NORDPRED software). Age-standardized incidence rates per 100,000 person-years were calculated by country and sex. Increases in new cases and rates of PLC are projected in both sexes. The largest increases in rates are, among men, in Norway (2.9% per annum), US whites (2.6%), and Canada (2.4%) and, among women, in the United States (blacks 4.0%), Switzerland (3.4%), and Germany (3.0%). The projected declines are in China, Japan, Singapore, and parts of Europe (e.g., Estonia, Czech Republic, Slovakia). A 35% increase in the number of new cases annually is expected compared to 2005. This increasing burden reflects both increasing rates (and the underlying prevalence of risk factors) and demographic changes. Japan is the only country with a predicted decline in the net number of cases and annual rates by 2030. Conclusion: Our reporting of a projected increase in PLC incidence to 2030 in 30 countries serves as a baseline for anticipated declines in the longer term through the control of hepatitis B virus and hepatitis C virus infections by vaccination and treatment; however, the prospect that rising levels of obesity and its metabolic complications may lead to an increased risk of PLC that potentially offsets these gains is a concern. (Hepatology 2018;67:600-611).

Activation of Aflatoxin Biosynthesis Alleviates Total ROS in Aspergillus parasiticus

An aspect of mycotoxin biosynthesis that remains unclear is its relationship with the cellular management of reactive oxygen species (ROS). Here we conduct a comparative study of the total ROS production in the wild-type strain (SU-1) of the plant pathogen and aflatoxin producer, Aspergillus parasiticus, and its mutant strain, AFS10, in which the aflatoxin biosynthesis pathway is blocked by disruption of its pathway regulator, aflR. We show that SU-1 demonstrates a significantly faster decrease in total ROS than AFS10 between 24 h to 48 h, a time window within which aflatoxin synthesis is activated and reaches peak levels in SU-1. The impact of aflatoxin synthesis in alleviation of ROS correlated well with the transcriptional activation of five superoxide dismutases (SOD), a group of enzymes that protect cells from elevated levels of a class of ROS, the superoxide radicals (O₂^-). Finally, we show that aflatoxin supplementation to AFS10 growth medium results in a significant reduction of total ROS only in 24 h cultures, without resulting in significant changes in SOD gene expression. Our findings show that the activation of aflatoxin biosynthesis in A. parasiticus alleviates ROS generation, which in turn, can be both aflR dependent and aflatoxin dependent.

Epidemiology of hepatocellular carcinoma: target population for surveillance and diagnosis

Hepatocellular carcinoma (HCC) is the sixth most common cancer and the second leading cause of cancer mortality worldwide. Incidence rates of liver cancer vary widely between geographic regions and are highest in Eastern Asia and sub-Saharan Africa. In the United States, the incidence of HCC has increased since the 1980s. HCC detection at an early stage through surveillance and curative therapy has considerably improved the 5-year survival. Therefore, medical societies advocate systematic screening and surveillance of target populations at particularly high risk for developing HCC to facilitate early-stage detection. Risk factors for HCC include cirrhosis, chronic infection with hepatitis B virus (HBV), hepatitis C virus (HCV), excess alcohol consumption, non-alcoholic fatty liver disease, family history of HCC, obesity, type 2 diabetes mellitus, and smoking. Medical societies utilize risk estimates to define target patient populations in which imaging surveillance is recommended (risk above threshold) or in which the benefits of surveillance are uncertain (risk unknown or below threshold). All medical societies currently recommend screening and surveillance in patients with cirrhosis and subsets of patients with chronic HBV; some societies also include patients with stage 3 fibrosis due to HCV as well as additional groups. Thus, target population definitions vary between regions, reflecting cultural, demographic, economic, healthcare priority, and biological differences. The Liver Imaging Reporting and Data System (LI-RADS) defines different patient populations for surveillance and for diagnosis and staging. We also discuss general trends pertaining to geographic region, age, gender, ethnicity, impact of surveillance on survival, mortality, and future trends.

Integrated proteome and HPLC analysis revealed quercetin-mediated inhibition of aflatoxin B1 biosynthesis in Aspergillus flavus

The contamination of aflatoxins in maize or maize-related products synthesized by Aspergillus flavus causes severe economical loss and threat to human health. Use of eco-friendly phytochemicals has shown potential to inhibit secondary metabolites in Aspergillus species. Thus, A. flavus cultured in corn flour (CF) and corn flour with quercetin (CF_Q) was used for protein extraction for proteome analysis using nLC-Q-TOF mass spectrometer. Proteome analysis revealed the expressions of 705 and 843 proteins in CF_Q and CF, respectively. Gene Ontology Slim Categories (GOSC) of CF exhibited major transcriptional factors; involved in acetylation and deacetylation of histone proteins, carbohydrate metabolism, and hydrolase activity, whereas GOSC analysis of CF_Q showed membrane transport activity, including both influx and efflux proteins. cAMP/PKA signaling pathway was observed in CF_Q, whereas MAPK pathway in CF. To quantify biosynthesis of aflatoxin B1 (AFB1) in CF and CF_Q, HPLC analysis at 7, 12, 24 and 48 h was carried out which showed decrease in AFB1 (1%) at 7-24 h in CF_Q. However, remarkable decrease in AFB1 biosynthesis (51%) at 48 h time point was observed. Thus, the present study provided an insight into the mechanism of quercetin-mediated inhibition of aflatoxin biosynthesis in A. flavus and raises the possibility to use quercetin as an anti-aflatoxigenic agent.

Factors associated with the high prevalence of oesophageal cancer in Western Kenya: a review

Oesophageal carcinoma (OC) is highly prevalent in Western Kenya especially among the members of the Kalenjin community who reside in the Northern and Southern areas of the Rift Valley. Previous authors have suggested potential association of environmental and genetic risk factors with this high prevalence. The environmental factors that have been suggested include contamination of food by mycotoxins and/or pesticides, consumption of traditional alcohol (locally referred to “Busaa” and “Chan’gaa”), use of fermented milk (“Mursik”), poor diet, tobacco use and genetic predisposition. The aim of this paper is to critically examine the potential contribution of each of the factors that have been postulated to be associated with the high prevalence of the disease in order to establish the most likely cause. We have done this by analyzing the trends, characteristics and behaviours that are specifically unique in the region, and corroborated this with the available literature.

From our findings, the most plausible cause of the high incidence of OC among the Kalenjin community is mycotoxins, particularly fumonisins from the food chain resulting from poor handling of cereals; particularly maize combined with traditional alcohol laced with the toxins interacting synergistically with other high-risk factors such as dietary deficiencies associated alcoholism and viral infections, especially HPV. Urgent mitigating strategies should be developed in order to minimize the levels of mycotoxins in the food chain.

Safety of frozen liver for human consumption

The objective of this study was to ensure and evaluate the safety of imported frozen beef liver traded in supermarkets of Kafr El-Sheikh Governorate, Egypt, through detection of Salmonella typhimurium, Salmonella enteritidies, Escherichia coli O157:H7, antibiotic residues, and aflatoxin B1 residue. Fifty samples of imported frozen liver were randomly collected from different shops at Kafr El-Sheikh Governorate for isolation of S. typhimurium, S. enteritidies, and E. coli O157:H7. The results revealed that for both microorganisms 4% of the examined samples presumed to contain Salmonella and E. coli O157:H7 organisms, according to the colonial character on Harlequin Salmonella ABC agar media and Harlequin SMAC-BCIG agar media. According to biochemical and serological identifications, both organisms could not be detected in the examined samples. A total of 29 (58%) samples were positive for antibiotic residues, using the Premi test (a broad-spectrum screening test for the detection of antibiotic residues in meat) at or below the maximum residue limits. In addition, aflatoxin B1 was detected in one (2%) samples with a concentration of 1.1 μg/kg. The results reflect that there was good hygiene practice for handling and preparation of frozen liver while selling to consumers. However, a high percentage of antibiotic residues reflect ignorance of withdrawal time before slaughtering of animals as well as misuse of antibiotics in veterinary fields. Furthermore, aflatoxin B1 residue was detected in examined frozen liver samples at a concentration below the maximum residual level, which is not enough to cause threat to humans, but it is enough to cause problem if it is eaten regularly reflect contamination of animal feed with aflatoxins.

Piecing together the stunting puzzle: a framework for attributable factors of child stunting

Reducing the burden of stunting in childhood is critical to improving health in low- and middle-income settings. However, because many aetiologies underlie linear growth failure, stunting has proved difficult to prevent and reverse. Understanding the contributions these aetiologies make to the burden of stunting can help the development of targeted, effective interventions. To begin to frame these causes, a qualitative and a quantitative framework of the primary drivers of stunting in low-resource settings were developed. Population attributable fractions (PAF) were estimated to inform the quantitative framework. According to these estimates, infectious diseases were responsible for large attributable fractions in all settings, and a combination of dietary indicators also comprised a large fraction in Africa. However, the PAF calculation was found to have several limitations, including a requirement for a binary outcome and sensitivity to confounding, which necessitate broad interpretation of the results. More robust tools to model complex causality are needed in order to understand the causal aetiology of stunting.

Roles of p53 in extrinsic factor-induced liver carcinogenesis

Liver cancer remains one of the most common human cancers with a high mortality rate. Therapies for hepatocellular carcinoma (HCC) remain ineffective, due to the heterogeneity of HCC with regard to both the etiology and mutation spectrum, as well as its chemotherapy resistant nature; thus surgical resection and liver transplantation remain the gold standard of patient care. The most common etiologies of HCC are extrinsic factors. Humans have multiple defense mechanisms against extrinsic factor-induced carcinogenesis, of which tumor suppressors play crucial roles in preventing normal cells from becoming cancerous. The tumor suppressor p53 is one of the most frequently mutated genes in liver cancer. p53 regulates expression of genes involved in cell cycle progression, cell death, and cellular metabolism to avert tumor development due to carcinogens. This review article mainly summarizes extrinsic factors that induce liver cancer and potentially have etiological association with p53, including aflatoxin B1, vinyl chloride, non-alcoholic fatty liver disease, iron overload, and infection of hepatitis viruses.

Effect of dietary macronutrients on aflatoxicosis: a mini-review

Aflatoxin is a toxin produced by Aspergillus species of fungi. The main route of aflatoxin exposure is through the diet. Indeed, long-term aflatoxin exposure is linked to the development of hepatocellular carcinoma (HCC). Aflatoxin causes aflatoxicosis, which can be affected by several factors and is prevalent in many developing Asian and African countries. This mini-review discusses the effects of carbohydrate, fat and protein on aflatoxicosis based on findings from animal and human studies. It was found that high carbohydrate intake enhanced aflatoxicosis occurrence, while low ingestion of carbohydrate with caloric restriction slowed the symptoms associated with aflatoxicosis. Additionally, diets with low protein content worsened the symptoms related to HCC due to aflatoxin exposure. Nevertheless, a study reported that a high-protein diet favored detoxification of aflatoxin in vivo. There were also conflicting results on the influence of dietary fat, as high ingestion of fat enhanced aflatoxicosis development as compared with a low-fat diet. Moreover, the type of fat also plays a significant role in influencing aflatoxin toxicity. In regard to food safety, understanding the influence of macronutrients toward the progression of aflatoxicosis can improve preventive measures against human and animal exposure to aflatoxin. © 2017 Society of Chemical Industry.

Inhibitory Activities of Blasticidin S Derivatives on Aflatoxin Production by Aspergillus Flavus

Blasticidin S (BcS) is a protein synthesis inhibitor which shows strong growth inhibitory activity against a number of microorganisms. However, BcS inhibited aflatoxin production by Aspergillus flavus without affecting its growth. In order to obtain information about the structure–activity relationship of BcS as an aflatoxin production inhibitor, BcS derivatives were prepared and their aflatoxin production inhibitory activities were evaluated. Among five derivatives, blasticidin S carboxymethyl ester, deaminohydroxyblasticidin S, and pyrimidinoblasticidin S showed inhibitory activity, while the others did not. The IC₅₀ value for aflatoxin production of the carboxymethyl ester derivative was one-fifth of that of BcS although their antimicrobial activities were almost the same. These results indicate that the inhibitory activity of BcS against aflatoxin production was enhanced by esterification of its carboxyl group and that the carboxymethyl ester derivative might be more suitable for practical use than BcS because of the specificity of the carboxymethyl ester derivative, which inhibited aflatoxin production more than BcS.

Battlefield against hepatitis B infection and HCC in Africa

Despite effective and safe hepatitis B virus (HBV) vaccine and antiviral therapies, HBV-related hepatocellular carcinoma (HCC) remains a major cause of deaths in young adults in Africa. There are multiple barriers to control the burden of HBV infection and HCC. In comparison to other major infectious diseases, HBV infection and liver diseases have received remarkably little attention from the global health community. There is an urgent need to improve birth dose vaccine coverage and implementing screening and treatment interventions. This requires a dramatic simplification of the management of chronic hepatitis B in Africa, with access to reliable, robust and inexpensive diagnostic tools and strong support from the local governments and the international health community. This review analyses 1) the characteristics of HBV hepatitis and HCC epidemics in Africa and 2) the barriers and potential solutions to control it.

Genome-wide association study: new genetic insights into HBV/HCV-related hepatocellular carcinoma genomes

Hepatocellular carcinoma (HCC) is the third common cause of cancer-related death with highest prevalence in developing countries, such as Southeast China and Saharan African. The major pathogenic factors can be categorized into environmental effects and genetic variations, and it is mostly caused by hepatitis B or C virus (HBV and HCV). The geographic prevalence of chronic hepatitis B and C (CHB and CHC) varies, with HBV heavily-infected in developing countries and HCV prevalent in developed countries. The infection of either hepatitis virus B or C causes damage to the liver cells through cellular immune attack by the mechanism of inflammation. However, how liver cell injury progresses to HCC development is still poorly understood. Along with the maturation of genome-wide association study (GWAS) technology, the specific genetic mutations responsible for the progression from CHB or CHC to HCC have been identified. Moreover, the findings of similar studies for these variants are different from each other due to diverse populations. More functional experiments are warranted to confirm the precise roles of these genetic mutations in the correlations between HBV/HCV and HCC for the future clinical application.

Adaptation and mitigation options to manage aflatoxin contamination in food with a climate change perspective

Understanding the impact of climate change remains vital for food safety and public health. Of particular importance is the influence of climatic conditions on the growth of Aspergillus flavus and production of their toxins. Nevertheless, little is known about the actual impact of climate change on the issue. Setting up of relevant measures to manage the impact has therefore become a daunting task especially in developing nations. Therefore, this study aimed at providing adaptation and mitigation options to manage this risk with a special focus on Kenya where cases of aflatoxicosis have been recurrent. We used a systematic literature review of review and research articles, with limited searching but systematic screening to explore available qualitative and quantitative data. Projections from the data, showed that on average, a 58.9% increase of aflatoxin contamination in the Central and Western parts and a decrease of 44.6% in the Eastern and Southern parts is expected but with several possible scenarios. This makes the impact of climate change on aflatoxin contamination in Kenya complex. To protect the public and environment from the negative impact, a regulatory framework that allows for an integrated management of aflatoxins in a changing climate was proposed. The management practices in the framework are divided into agronomic, post-harvest and institutional levels. Given the multiple points of application, coordination amongst stakeholders along the chain is fundamental. We therefore proposed a complimentary framework that allows the food safety issues to be addressed in an integrated manner while allowing for transparent synergies and trade-offs (in implementing the measures). A policy-oriented foresight should be carried out to provide policy based evidence for the applicability of the proposed adaptation and mitigation measures.

Scientific and Regulatory Perspectives in Herbal and Dietary Supplement Associated Hepatotoxicity in the United States

In the United States (US), the risk of hepatotoxicity linked to the widespread use of certain herbal products has gained increased attention among regulatory scientists. Based on current US law, all dietary supplements sold domestically, including botanical supplements, are regulated by the Food and Drug Administration (FDA) as a special category of foods. Under this designation, regulatory scientists do not routinely evaluate the efficacy of these products prior to their marketing, despite the content variability and phytochemical complexity that often characterizes them. Nonetheless, there has been notable progress in the development of advanced scientific methods to qualitatively and quantitatively measure ingredients and screen for contaminants and adulterants in botanical products when hepatotoxicity is recognized.

Role of biomarkers in the prediction and diagnosis of hepatocellular carcinoma

The prevalence of hepatocellular carcinoma (HCC) has progressively increased in recent years and is now the fifth and the second most common cancer in the World and in Egypt, respectively. Much work has focused in the development of assays for detecting hepatic carcinogensis before the observance of hepatic focal lesions. Particular attention has been directed towards HCC-specific biomarkers for use in the early diagnosis of HCC and in the confirmation of radiological studies. Although a number of biomarkers have been identified, none have been considered reliable indicators of early HCC lesions. This review presents a few of the most relevant HCC biomarkers and suggests improvements to the accuracy of diagnostic assays through their combined use. Furthermore, we present an algorithm for the biomarker-based diagnosis of HCC and highlight its important role in the early prediction of HCC.

Challenging Role of Dietary Aflatoxin B1 Exposure and Hepatitis B Infection on Risk of Hepatocellular Carcinoma

Aflatoxins (AFT) are poisonous substances which are classified in Group 1 carcinogenic agents to humans by International Agency for Research on Cancer (IARC). AFT can occur naturally in food commodities (maize, corn, rice) as a result of fungal contamination in hot and humid environments. In the food, toxin contamination can remain during manufacturing and long after fungi have stopped being biologically active. Aflatoxin B1 (AFB1) is the most dominant and potent agent from all AFT. In developing countries, high exposure to AFB1 can cause chronic toxicity and usually increases the incidence of Hepatocellular Carcinoma (HCC). However, in these regions hepatitis B is the most common risk factor for HCC cases. Many researches were aimed to enlighten the mechanism and the role of two etiological agents on risk of HCC, but the obtained data was conflicting with each other. It was uncertain that the indicators/biomarkers might be the contribution of the carcinogenic status of the patient; and, the biomarker samples from the subject may only reflect the recent effects of the toxin exposure after consumption of AFB1 contaminated commodities. The studies were facing with the errors of methods which were un-fit to enlighten the possible interaction between Hepatitis B and AFB1 on contribution to HCC. It was pivotal to understand the effect of each risk factor in order to prevent and improve public health in poor and undeveloped regions. Although some of the studies evaluate AFB1 alone as a considerable factor on HCC risk, according to this review it was concluded vice versa. This study was aimed to clarify the main etiological agent of HCC where AFB1 and HBV are endangering public health. In additionally, the purpose was to enlighten the possible synergistic effect between these two factors among HCC pathogenesis. Hence forth, appropriate and right applications could be conducted in undeveloped countries in order to protect public health.

Hepatitis B virus infection in children

For two decades, hepatitis B vaccine has been integrated into national routine childhood vaccination programs in almost all countries. The prevalence of HBsAg has decreased in children worldwide. However, there are children who miss the benefit of hepatitis B vaccine in some regions and countries. Long-term follow-up studies have revealed the clinical outcomes of chronic hepatitis B virus infection in children. A small percentage of chronically infected children develop liver cirrhosis and hepatocellular carcinoma. However, it is controversial who should be treated and when antiviral treatment should be initiated in children. Compared with adult studies, the data are insufficient to evaluate the pathogenesis of hepatitis B infection and the efficacy of antiviral treatment in childhood. New antiviral drugs have been approved for children and adults. Also, oral antiviral drugs are administered to pregnant women to reduce the hepatitis B virus mother-to-child transmission rate.

Adiponectin agonist ADP355 attenuates CCl4-induced liver fibrosis in mice

Liver fibrosis is a growing global health problem characterized by excess deposition of fibrillar collagen, and activation of hepatic stellate cells (HSCs). Adiponectin is known to possess anti-fibrotic properties; however a high physiological concentration and multiple forms circulating in blood prohibit clinical use. Recently, an adiponectin-like small synthetic peptide agonist (ADP355: H-DAsn-Ile-Pro-Nva-Leu-Tyr-DSer-Phe-Ala-DSer-NH2) was synthesized for the treatment of murine breast cancer. The present study was designed to evaluate the efficacy of ADP355 as an anti-fibrotic agent in the in vivo carbon tetrachloride (CCl4)-induced liver fibrosis model. Liver fibrosis was induced in eight-week old male C57BL/6J mice by CCl4-gavage every other day for four weeks before injection of a nanoparticle-conjugated with ADP355 (nano-ADP355). Control gold nanoparticles and nano-ADP355 were administered by intraperitoneal injection for two weeks along with CCl4-gavage. All mice were sacrificed after 6 weeks, and serum and liver tissue were collected for biochemical, histopathologic and molecular analyses. Biochemical studies suggested ADP355 treatment attenuates liver fibrosis, determined by reduction of serum aspartate aminotransferase (AST), alanine aminotransferase ALT) and hydroxyproline. Histopathology revealed chronic CCl4-treatment results in significant fibrosis, while ADP355 treatment induced significantly reversed fibrosis. Key markers for fibrogenesis-α-smooth muscle actin (α-SMA), transforming growth factor-beta1 (TGF-β1), connective tissue growth factor (CTGF), and the tissue inhibitor of metalloproteinase I (TIMP1) were also markedly attenuated. Conversely, liver lysates from ADP355 treated mice increased phosphorylation of both endothelial nitric oxide synthase (eNOS) and AMPK while AKT phosphorylation was diminished. These findings suggest ADP355 is a potent anti-fibrotic agent that can be an effective intervention against liver fibrosis.

N-alkylpyridinium quaternization for assisting electrospray ionization of sterols in oil by quadrupole-time of flight mass spectrometry

RATIONALE

The illegal cooking oil has become a serious social problem and raised widespread alarm recently. However, an efficient and sensitive technique for identifying the potential illegal cooking oil is still unavailable, especially when mixed with the ordinary ones; there is an urgent need to develop an efficient method for identifying the illegal cooking oil. Sterols in the cooking oil could be used as an indicator to identify the source and quality of oil by detecting the kinds of phytosterols and zoosterols. However, those sterols are difficult to be ionized by electrospray ionization, which resulted in the low sensitivity in electrospray ionization (ESI)-mass spectrometric (MS) analysis.

METHODS

N-alkylpyridinium isotope quaternization was extended to charge label sterols in different cooking oil and attached N-cationic pyridinium tag onto the sterols in the presence of trifluoromethanesulfonic anhydride (Tf2 O); the kinds of sterols were identified and quantified by comparing d0 /d5 pairs and product scan from ESI-quadrupole-time of flight (Q-TOF) MS analysis.

RESULTS

The derivatized sterols were attached with permanent charge, resulting in the significant enhancement of ionization in ESI-Q-TOF MS analysis. The detection limits of analytes were improved to 0.02-0.05 ng/mL; different kinds of phytosterol, zoosterol and oxides were identified and quantified by comparing d0 /d5 pairs from full scan and product scan. The method was applied in the detection of zoosterol for identifying the potential recycled cooking oil, even when the illegal oil has been blended into the ordinary one. More zoosterol was detected in the recycled oil compared with other cooking oil.

CONCLUSIONS

The use of N-alkylpyridinium isotope quaternization method provided an alternative method for identifying the potential illegal cooking oil.

Non-linear relationships between aflatoxin B₁ levels and the biological response of monkey kidney vero cells

Aflatoxin-producing fungi contaminate food and feed during pre-harvest, storage and processing periods. Once consumed, aflatoxins (AFs) accumulate in tissues, causing illnesses in animals and humans. Most human exposure to AF seems to be a result of consumption of contaminated plant and animal products. The policy of blending and dilution of grain containing higher levels of aflatoxins with uncontaminated grains for use in animal feed implicitly assumes that the deleterious effects of low levels of the toxins are linearly correlated to concentration. This assumption may not be justified, since it involves extrapolation of these nontoxic levels in feed, which are not of further concern. To develop a better understanding of the significance of low dose effects, in the present study, we developed quantitative methods for the detection of biologically active aflatoxin B₁ (AFB1) in Vero cells by two independent assays: the green fluorescent protein (GFP) assay, as a measure of protein synthesis by the cells, and the microculture tetrazolium (MTT) assay, as a measure of cell viability. The results demonstrate a non-linear dose-response relationship at the cellular level. AFB1 at low concentrations has an opposite biological effect to higher doses that inhibit protein synthesis. Additional studies showed that heat does not affect the stability of AFB1 in milk and that the Vero cell model can be used to determine the presence of bioactive AFB1 in spiked beef, lamb and turkey meat. The implication of the results for the cumulative effects of low amounts of AFB1 in numerous foods is discussed.