Aflatoxin B1 Albumin Adduct Research Articles

Correlations of Aflatoxin Exposure from Cooking Oil and Dietary Foods During Pregnancy with Birth Weight and Gestational Age at Birth in Guangxi, China.

Cooking oil and dietary foods are easily contaminated by aflatoxins (AFs) in Guangxi, China where low birth weight and preterm birth were prevalent. However, there are no data on AF exposure in pregnant women or their impact on newborn birth outcomes. This study aims to measure the levels and correlations of AFs in cooking oil, estimated dietary intake (EDI) of AFs in dietary foods, and serum AFB1 albumin adducts (AFB1-alb) with newborn birthweight and gestational age at birth. A prospective study was conducted among 126 pregnant women in Guangxi, China. All recruited women were interviewed for demographic data and behavior and obstetric information and then followed up until giving birth. AF measurements were obtained from cooking oil, dietary foods, maternal serum, and cord blood and the correlations of AF levels with newborn birthweight and gestational age at birth were tested using correlation analysis. The median EDI of AFs in cooking oil was 2.61 ng/kg.bw/day and in dietary foods 2.95 ng/kg.bw/day. High positive correlations among EDI of aflatoxin B1 (AFB1) from cooking oil and dietary foods were found (r > 0.7). Low positive correlations of AFB1-alb in maternal serum and cord blood and both EDI of AFB1 in both cooking oil and dietary foods were shown (r ≈0.3). Significant correlations between AF levels in both cooking oil and dietary foods with birth weight were found, but very low negative correlations (r = - 0.244 ~ -0.285). AFB1 levels in foods, maternal serum and cord blood levels were high in pregnant women with newborn low birth weight and preterm birth. The EDIs of AFB1 from both cooking oil and dietary foods were significantly correlated with AFB1-alb in maternal serum and cord blood. Negative correlations of AFs from cooking oils and foods with newborn birth weight should be paid more attention.

Association of aflatoxin B1 levels with mean CD4 cell count and uptake of ART among HIV infected patients: A prospective study.

Aflatoxin suppresses cellular immunity and accentuates HIV-associated changes in T- cell phenotypes and B- cells. This prospective study was conducted to examine the association of aflatoxin levels with CD4 T-cell count and antiretroviral therapy uptake over time. Sociodemographic and food data were collected from antiretroviral therapy naïve HIV-infected patients. CD4+ counts were collected from participants' medical records. Plasma samples were tested for aflatoxin B1 albumin adducts, hepatitis B surface antigen, and HIV viral load. Participants were separated into high and low aflatoxin groups based on the median aflatoxin B1 albumin adduct level of 10.4 pg/ml for data analysis. Participants with high aflatoxin B1 albumin adduct levels had lower mean CD4 at baseline and at each follow-up period. Adjusted multivariable logistic regression analysis showed that higher baseline aflatoxin B1 adduct levels were associated with statistically significant lower CD4 counts (est = -66.5, p = 0.043). Not starting ART and low/middle socioeconomic status were associated with higher CD4 counts (est = 152.2, p<0.001) and (est = 86.3, p = 0.027), respectively. Consistent correlations of higher aflatoxin B1 adduct levels with lower CD4 over time indicate that there is an independent early and prolonged effect of aflatoxin on CD4 even with the initiation of antiretroviral therapy. The prospective study design, evaluation of baseline and follow-up measures, extensive control for potential confounders, and utilization of objective measures of aflatoxin exposure and CD4 count provide compelling evidence for a strong epidemiologic association that deserves careful attention in HIV care and treatment programs.

The mediating role of coagulation function on the association of prenatal exposure to aflatoxin B1 and postpartum hemorrhage in Guangxi, China.

Pregnant women are vulnerable to certain environmental agents, one of which is aflatoxin. As one of the most popular aflatoxins, Aflatoxin B1 (AFB1) has recently garnered increased attention concerning its potential association between exposure and adverse pregnancy outcomes. The aims of the study were to examine the associations between prenatal exposure to AFB1 and postpartum hemorrhage (PPH), and whether coagulation function has a mediating effect on their relationship. A total of 379 mother-infant pairs were included in the present study. Prenatal serum AFB1 albumin (AFB1-Alb) adduct levels in peripheral venous blood were detected by using an ELISA kit. Multiple linear and logistics regression models were applied to analyze the relationship between AFB1-Alb levels and PPH. We found mothers with high levels of AFB1-Alb adduct levels had significantly increased postpartum blood loss (partial regression coefficient (β) = 50.71, 95% confidence interval (CI) 3.48, 97.95). Mothers with high levels of AFB1-Alb adduct levels also had significantly increased risk of PPH (odds ratio (OR) = 4.81, 95% CI 1.01, 22.98). Moreover, concentrations of AFB1-Alb were positively associated with activated partial thromboplastin time (APTT) while negatively associated with fibrinogen (FIB). One-unit increase in APTT was correlated with a 6.62-ml (95% CI 3.04, 10.20) increase in postpartum blood loss. Mediation analysis suggested that the maternal blood APTT levels had a positive mediating effect in the association between AFB1-Alb adduct levels and postpartum blood loss (β = 0.32, 95% CI 0.04, 0.68). These results indicated that prenatal exposure to AFB1 was associated with increased postpartum blood loss, possibly by interfering with maternal APTT levels.

Environmental exposure and clinical correlates of hepatocellular carcinoma in New York City: a case only study.

In the U.S., Hepatocellular carcinoma (HCC) incidence rates have increased. We aimed to determine whether environmental exposure plays a role in the high incidence of HCC observed in New York City. We conducted a hospital-based case only study to examine the prevalence of aflatoxin B1 (AFB1)- and polycyclic aromatic hydrocarbon (PAH)-albumin adducts and the distribution of adducts by different characteristics of HCC patients. Blood samples were collected from 155 HCC patients for biomarker analyses.We observed that about 46% and 49% of cases had detectable AFB1- and PAH-albumin adducts, respectively. There were significant differences between AFB1-albumin adducts and selected factors such as HCV infection status (p = 0.04), diabetes (p = 0.03) and Barcelona Clinic Liver Cancer stage (p = 0.02). Cases with detectable PAH-albumin adducts had a smoking history compared with those with nondetectable levels (p = 0.04). The level of AFB1-albumin adducts was positively correlated with plasma bilirubin (rs = 0.32, p < 0.0001) and adiponectin concentrations (rs = 0.28, p = 0.0005). The level of aflatoxin B1-albumin adducts was negatively associated with blood albumin concentration (rs = -0.28, p = 0.0009) and plasma DNA LINE-1 methylation (rs = -0.16, p = 0.04). Our study provides additional evidence that environmental exposures including to aflatoxin might drive the high incidence of HCC observed in the New York City.

Comparative Hepatotoxicity of Aflatoxin B1 among Workers Exposed to Different Organic Dust with Emphasis on Polymorphism Role of Glutathione S-Transferase Gene.

AIM:The study aimed to investigate effects of organic dust exposure from different sources on aflatoxin B1-albumin adducts (AFB1/Alb), and role of glutathione S-transferase (GST) gene polymorphism in hepatotoxicity of (AFB1) among exposed workers.MATERIAL AND METHODS:Liver enzymes, AFB1/Alb, and GST polymorphism were estimated in 132 wheat flour dust and 87 woods sawmill workers, and 156 controls.RESULTS:Results revealed that AFB1/Alb and liver enzymes were significantly elevated in exposed workers compared to controls, and were significantly higher in sawmill workers compared to flour workers. AFB1/Alb in flour and sawmill workers with GSTT1 and GSTM1&GSTT1 null genotypes were significantly higher than controls, and in sawmill workers with GSTM1&GSTT1 null than flour workers. Liver enzymes (ALT and AST) in sawmill workers were significantly higher than flour workers and controls in all GST polymorphism; except in GSTT1 polymorphism, where these enzymes were significantly higher in the two exposed groups than controls.CONCLUSIONS:In conclusion, organic dust exposure may cause elevation in AFB1/Alb and liver enzymes of exposed workers, and GST gene polymorphism plays an important role in susceptibility to hepatic parenchymal cell injury; except in workers with GSTT1&GSTM1 null genotype, gene susceptibility seemed to have little role and the main role was for environmental exposures.

Temporal Variation and Association of Aflatoxin B₁ Albumin-Adduct Levels with Socio-Economic and Food Consumption Factors in HIV Positive Adults.

The association between aflatoxin exposure and alteration in immune responses observed in humans suggest that aflatoxin could suppress the immune system and work synergistically with HIV to increase disease severity and progression to AIDS. No longitudinal study has been conducted to assess exposure to aflatoxin (AF) among HIV positive individuals. We examined temporal variation in AFB1 albumin adducts (AF-ALB) in HIV positive Ghanaians, and assessed the association with socioeconomic and food consumption factors. We collected socioeconomic and food consumption data for 307 HIV positive antiretroviral naive adults and examined AF-ALB levels at recruitment (baseline) and at six (follow-up 1) and 12 (follow-up 2) months post-recruitment, by age, gender, socioeconomic status (SES) and food consumption patterns. Generalized linear models were used to examine the influence of socioeconomic and food consumption factors on changes in AF-ALB levels over the study period, adjusting for other covariates. AF-ALB levels (pg/mg albumin) were lower at baseline (mean AF-ALB: 14.9, SD: 15.9), higher at six months (mean AF-ALB: 23.3, SD: 26.6), and lower at 12 months (mean AF-ALB: 15.3, SD: 15.4). Participants with the lowest SES had the highest AF-ALB levels at baseline and follow up-2 compared with those with higher SES. Participants who bought less than 20% of their food and who stored maize for less than two months had lower AF-ALB levels. In the adjusted models, there was a statistically significant association between follow up time and season (dry or rainy season) on AF-ALB levels over time (p = 0.04). Asymptomatic HIV-positive Ghanaians had high plasma AF-ALB levels that varied according to season, socioeconomic status, and food consumption patterns. Steps need to be taken to ensure the safety and security of the food supply for the population, but in particular for the most vulnerable groups such as HIV positive people.

Association between aflatoxin B1 occupational airway exposure and risk of hepatocellular carcinoma: a case-control study.

The aim of this study was to determine the airway exposure of sugar and papermaking factory workers to aflatoxin B1 (AFB1) and to explore the potential association between AFB1 airway exposure and the risk of hepatocellular carcinoma (HCC) in a case-control study. Dust samples were collected from the sugarcane bagasse warehouse, and presser and paper production workshops. Blood samples were collected from 181 workshop employees and 203 controls who worked outside the workshop. AFB1 albumin adducts were detected using a double antibody sandwich enzyme-linked immunosorbent assay (ELISA). To explore the association between AFB1 airway exposure and the risk of HCC, the medical records of 68 HCC patients who worked in a sugar and papermaking factory between January 1994 and December 2013 were analyzed. A questionnaire was used to collect information from 150 healthy controls who worked for the same company and lived near the factory. AFB1 was detected in the dust samples, but could not be detected in any of the rice samples. An analysis of serum samples revealed serum AFB1 albumin adducts in 102 (56.35 %) of the study participants. However, in the control group, only 12 (5.9 %) individuals had detectable levels of AFB1 albumin adducts. Those with airway exposure to Aspergillus flavus-contaminated dust had an elevated risk of HCC compared to those without exposure (odds ratio, 5.24; 95 % confidence interval, 2.77–9.88; P = 0.00). The findings of this study indicate that occupational AFB1 airway exposure might be associated with the risk of AFB1-related HCC among the population that was used in this study. Intervention programs aimed at reducing exposure to inhalational AFB1 are needed urgently. Additional suitably designed, multicenter, prospective studies using large samples are needed to further confirm the results.

How does airway exposure of aflatoxin B1 affect serum albumin adduct concentrations? Evidence based on epidemiological study and animal experimentation.

Aflatoxin B1 (AFB1) airway inhalation represents an additional route of exposure to this toxin. However, the association between AFB1 inhalation and serum AFB1 albumin adducts remains unclear. The aim of this study was to explore the association between airway exposure to AFB1 and serum AFB1 albumin adduct concentrations via an epidemiological study, as well as in an AFB1 airway exposure animal model. Our epidemiological study was conducted in a sugar factory in the Guangxi Autonomous Region of China. In order to examine fungal contamination, air samples were obtained in the workshop and areas outside the workshop, such as the office and nearby store. Dust samples were also collected from the bagasse warehouse and presser workshop, and were analyzed using an indirect competitive enzyme-linked immunosorbent assay (ELISA). Additionally, blood samples were collected from a total of 121 workshop workers, and a control group (n = 80) was comprised of workers who undertook administrative tasks or other work outside the workshop. The animal experiment was conducted in the laboratory animal center of Guangxi Medical University, where a total of 60 adult male rabbits were involved in this study. By intubation, AFB1 was administered in three groups of rabbits daily, at dose rates of 0.075, 0.05 and 0.025 mg/kg/day for a period of 7 days. Blood samples were collected on day 1, day 3, day 7 and day 21, and the measurements of the AFB1 albumin adducts in the serum were performed by a double antibody sandwich ELISA. The epidemiological study showed that serum albumin adducts were detected in 67 workshop workers (55.37%), and the values ranged 6.4 pg/mg albumin to 212 pg/mg albumin (mean value: 51 ± 4.62 pg/mg albumin). In contrast, serum albumin adducts were detected in only 7 control group participants, with the values ranging from 9 pg AFB1/mg albumin to 59 pg/mg albumin (mean value: 20 ± 13.72 pg/mg albumin). The animal experiment revealed that the rabbits had detectable levels of AFB1 in their serum with a minimum effective dose of 0.05 mg/kg/day; while 11 of 17 (64.71%) rabbits had detectable levels of AFB1 albumin adducts in the high exposure group (0.075 mg/kg/day), and only 5 rabbits (26.32%) had detectable levels of AFB1 albumin adducts in the moderate exposure group (0.05 mg/kg/day). No rabbits had detectable levels of AFB1 albumin adducts in the low exposure group (0.025 mg/kg/day). Our results demonstrated that only exposure to a certain level of AFB1 would result in detectable levels of serum AFB1 albumin adducts. Interventional programs aimed at reducing exposure to AFB1 by inhalation are urgently needed in high-risk populations. Additional large-sample, well-designed randomized controlled trials are needed to further confirm our results.

Association between high aflatoxin B1 levels and high viral load in HIV-positive people.

Since both aflatoxin and the human immunodeficiency virus (HIV) cause immune suppression, chronic exposure to aflatoxin in HIV-positive people could lead to higher levels of virus replication. This study was conducted to examine the association between aflatoxin B1 albumin adduct (AF-ALB) levels and HIV viral load. Antiretroviral naive HIV-positive people (314) with median CD4 count of 574 cells/μl blood (mean ± standard deviation = 630±277) were recruited in Kumasi, Ghana. Sociodemographic and health data, and blood samples were collected from participants. The plasma samples were tested for AF-ALB and HIV viral load. Univariate logistic regression analysis was conducted using viral load (high/low) as the outcome and AF-ALB quartiles as exposure. Multivariable logistic regression analysis was performed between quartile AF-ALB, viral load and CD4 adjusting for sex, age, and year of HIV diagnosis. Both univariate and multivariable logistic regression showed that viral load increased as AF-ALB levels increased. By univariate analysis, high viral load was 2.3 times more likely among persons in the third AF-ALB quartile (95% confidence interval (Cl): 1.13, 4.51), and 2.9 times more likely among persons in the fourth AF-ALB quartile (Cl: 1.41, 5.88), compared to persons in the first quartile. In the multivariable model, persons in the fourth AF-ALB quartile were about 2.6 times more likely to have high viral loads than persons in the first quartile (Cl: 1.19-5.69). When AF-ALB and viral load were log transformed and linear regression analysis conducted, the univariate linear regression analysis showed that for each pg/mg increase in AF-ALB, viral load increased by approximately 1.6 copies/ml (P=0.0006). The association was marginally significant in the adjusted linear regression model (i.e. for each pg/mg increase in AF-ALB, the mean viral load increased by approximately 1.3 copies/ml, P=0.073). These data show strong and consistent increases in HIV viral load with increasing AF-ALB levels. Since the median and mean CD4 were greater than 500 cells for participants in each AF-ALB quartile, the results indicate that the immune modulating and virus transcription effects of aflatoxin may occur quite early in HIV infection, even while the CD4 count is still above 500, resulting in higher viral loads.

Developing cost-effective aflatoxin detection kits

Food safety is equally important to food and nutritional security, and hence ICRISAT has given priority to this area of research. Aflatoxins are an important group of mycotoxins and pose a serious threat to food safety worldwide, but more particular developing countries where inappropriate post-harvest handling and processing facilities increase the risks. Currently >75% of the countries in the world have their own regulations on aflatoxins, indicating the level of concern that the present day world is putting on food safety issues. Unfortunately, aflatoxin contamination is often invisible, and it is difficult to physically separate contaminated grains. So it is inevitable to estimate and quantify toxins in commodities to safeguard human and animal health. Commercially available analytical and chromatographic techniques to researchers and traders are expensive. Hence ICRISAT has developed simple and cost-effective methods for detecting aflatoxins in various foods and feed commodities. ICRISAT has a fully equipped Mycotoxicology lab to produce monoclonal and polyclonal antibodies for Aflatoxin B1 and polyclonal antibodies to other mycotoxins such as Aflatoxin M1, Ochratoxin A, Fumonisin B1 by immunizing the animals with respective toxin-BSA conjugate (Devi et al. 1999, 2002). The antibodies are utilized to develop competitive ELISAs for the estimation of the toxin(s) in food, feed and milk. Two types of competitive ELISAs (direct and indirect) have been developed, and both types are heterogeneous assays that produce uniform results. The competitive ELISAs are simple, sensitive, rapid, versatile, and cost-effective for aflatoxins estimation and the results obtained were comparable with that of HPLC analysis (Waliyar et al., 2009). The sensitivity of aflatoxin M1 detection is 0.5 μg/kg, and 1.0 μg/kg for other aflatoxins and ochratoxin, and 20 μg/kg for fumonisins. This suggests that these assays meet global standards for screening food samples. In all the assays the analysis cost is about US$ 1 per sample as against the $ 30 with HPLC systems. These detection tools provide unique opportunity for ICRISAT and its partners to test a large number of samples from field trials to devise pre- and post-harvest management strategies and to deploy appropriate interventions in value chains to enhance the food safety, human/animal health, and trade. ICRISAT's thrust towards capacity building of its national partners lead to setting up of more than 20 aflatoxin detection laboratories and trained more than 150 scientists/technicians in India, Kenya, Malawi, Mali, Mexico, Mozambique, Nigeria, Philippines and Vietnam, that rely on ELISA technology. These laboratories are successfully contributing to the quality certification of farmers’ produce and enhancing product competitiveness in the global market. Recently ICRISAT developed a simple ELISA for quantitative estimation of Aflatoxin B1 albumin adducts in humans (Anitha et al., 2011).

Epidemiology of Viral Hepatitis and Hepatocellular Carcinoma

Most cases of hepatocellular carcinoma (HCC) are associated with cirrhosis related to chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Changes in the time trends of HCC and most variations in its age-, sex-, and race-specific rates among different regions are likely to be related to differences in hepatitis viruses that are most prevalent in a population, the timing of their spread, and the ages of the individuals the viruses infect. Environmental, host genetic, and viral factors can affect the risk of HCC in individuals with HBV or HCV infection. This review summarizes the risk factors for HCC among HBV- or HCV-infected individuals, based on findings from epidemiologic studies and meta-analyses, as well as determinants of patient outcome and the HCC disease burden, globally and in the United States.

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 B1–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.

Aflatoxin B1 albumin adducts in plasma and aflatoxin M1 in urine are associated with plasma concentrations of vitamins A and E.

Although aflatoxin exposure has been associated with micronutrient deficiency in animals, there are few investigations on the effects of aflatoxin exposure on micronutrient metabolism in humans. To examine the relationship between aflatoxin B1 (AFB1) albumin adducts (AF-ALB) in plasma and the aflatoxin M1 (AFM1) metabolite in urine and plasma concentrations of retinol (vitamin A) and alpha-tocopherol (vitamin E) in Ghanaians. A cross-sectional study of 147 adult participants was conducted. Blood and urine samples were tested for aflatoxin and vitamins A and E levels. Multivariable analysis showed that participants with high AF-ALB (>or=0.80 pmol/mg albumin) had increased odds of having vitamin A deficiency compared to those with lower AF-ALB [Odds Ratio (OR)=2.61; CI=1.03-6.58; p=0.04]. Participants with high AF-ALB also showed increased odds of having vitamin E deficiency but this was not statistically significant (OR=2.4; CI=0.96-6.05; p=0.06). Conversely, those with higher AFM1 values had a statistically nonsignificant reduced odds of having vitamin A deficiency (OR=0.31; CI=0.09-1.02; p=0.05) and a statistically significant reduced odds of having vitamin E deficiency (OR=0.31; CI=0.10-0.97; p=0.04). Participants with high AF-ALB or high AFM1 (>or=437.95 pg/dL creatinine) were almost 6 times more likely to be hepatitis B virus surface antigen (HBsAg)-positive (OR=5.88; CI=1.71-20.14; p=0.005) and (OR=5.84; CI=1.15-29.54; p=0.03) respectively. These data indicate that aflatoxin may modify plasma micronutrient status. Thus, preventing aflatoxin exposure may reduce vitamin A and E deficiencies.

Long-term Stability of Human Aflatoxin B1 Albumin Adducts Assessed by Isotope Dilution Mass Spectrometry and High-Performance Liquid Chromatography–Fluorescence

The measurement of the aflatoxin B(1)-lysine serum albumin adduct in human blood samples is the most facile biomarker for the assessment of chronic exposure to aflatoxin B(1). Many technologies have been developed for the measurement of this protein adduct including immunoassays, high-performance liquid chromatography (HPLC) with fluorescence detection, and a newly developed isotope-dilution mass spectrometry method. Irrespective of the technology used to determine this adduct level, an important question remains about the long-term stability of this damage product in stored samples. To address this issue, 19 human serum samples that had been previously analyzed for the aflatoxin B(1)-lysine adduct by high-performance liquid chromatography-fluorescence in 1989 were re-analyzed by isotope dilution mass spectrometry after storage at -80 degrees C. The adduct concentrations measured by these two techniques were identical within 4% over the range 5 to 100 pg of aflatoxin B(1)-lysine/mg albumin. In addition, the specific chemical structure of the aflatoxin B(1)-lysine adduct in human samples was confirmed for the first time by collision-induced dissociation full scan mass spectrometry analysis of the protonated adduct molecular ion. These results illustrate that the aflatoxin B(1)-lysine serum albumin adduct can be stable in human serum stored at -80 degrees C since 1989, and this provides confidence for the measurement of this biomarker in repository samples from epidemiologic investigations.

Aflatoxin-related immune dysfunction in health and in human immunodeficiency virus disease.

Both aflatoxin and the human immunodeficiency virus (HIV) cause immune suppression and millions of HIV-infected people in developing countries are chronically exposed to aflatoxin in their diets. We investigated the possible interaction of aflatoxin and HIV on immune suppression by comparing immune parameters in 116 HIV positive and 80 aged-matched HIV negative Ghanaians with high (≥0.91 pmol/mg albumin) and low (<0.91 pmol/mg albumin) aflatoxin B1 albumin adduct (AF-ALB) levels. AF-ALB levels and HIV viral load were measured in plasma and the percentages of leukocyte immunophenotypes and cytokine expression were determined using flow cytometry. The cross-sectional comparisons found that (1) among both HIV positive and negative participants, high AF-ALB was associated with lower perforin expression on CD8+ T-cells (P = .012); (2) HIV positive participants with high AF-ALB had significantly lower percentages of CD4+ T regulatory cells (Tregs; P = .009) and naive CD4+ T cells (P = .029) compared to HIV positive participants with low AF-ALB; and (3) HIV positive participants with high AF-ALB had a significantly reduced percentage of B-cells (P = .03) compared to those with low AF-ALB. High AF-ALB appeared to accentuate some HIV associated changes in T-cell phenotypes and in B-cells in HIV positive participants.

Evaluation of oxidative stress in a group of adolescents exposed to a high level of aflatoxin B1 a multi-center and multi-biomarker study

The association between aflatoxin B1 (AFB1) exposure and oxidative stress was extensively examined in 84 adolescents from an area at high risk for hepatocellular carcinoma in China. Plasma level of aflatoxin B1-albumin adducts (AAAs) was associated with AFB1 excretion in urine (r = 0.394, P < 0.001). Urinary AFB1 was also associated with both the urinary excretion of 8-hydroxydeoxyguanosine (8-OHdG) (r > or = 0.479, P < 0.001) and 8-OHdG and hOGG1 levels in peripheral leukocytes (r > or = 0.308, P < or = 0.005). Similarly, AAA was significantly associated with both the urinary excretion of 8-OHdG (r > or = 0.259, P < or = 0.018) and the 8-OHdG and hOGG1 levels in peripheral leukocytes (r > or = 0.313, P < or = 0.004). In addition, urinary 8-OHdG was correlated with both the level of DNA 8-OHdG (r > or = 0.24, P < or = 0.05) and the expression of hOGG1 in peripheral leukocytes (r > or = 0.429, P < 0.001). Protein carbonyl content (PCC) level was significantly associated with not only the level of DNA 8-OHdG (r > or = 0.366, P < 0.001) and the urinary 8-OHdG (r > or = 0.258, P < or = 0.018) but also the expression of hOGG1 in peripheral leukocytes (r = 0.485, P < 0.001). A significant but weak association was found between high-performance liquid chromatograph-electrochemical detection (HPLC-ECD) and enzyme-linked immunosorbent assay (ELISA) for urinary 8-OHdG (r = 0.334, P = 0.002) and between HPLC-ECD and flow cytometry assays for 8-OHdG in leucocytes (r = 0.395, P < 0.001). Significant associations were observed between AAA and PCC and liver function indices (alanine aminotransferase and aspartate aminotransferase). These findings suggest significant contribution from AFB1 exposure to oxidative stress and subsequent repair among adolescents that may impose substantial risk for hepatocarcinogenesis in adulthood in this region.

Association between aflatoxin exposure and health characteristics, liver function, hepatitis and malaria infections in Ghanaians

Purpose. We examined the relationship between various health parameters and aflatoxin B1 (AFB1) albumin adduct levels in plasma.Design. A cross‐sectional field study was conducted in four villages in the Ashanti region of Ghana.Methods. A survey on socio‐demographic and health characteristics was administered to 162 volunteers and blood (20 ml) was donated by 140 participants. AFB1 albumin adduct levels, liver function, hepatitis B and C viruses (HBV, HCV) and malaria infections were determined.Results. AFB1 levels ranged from 0.12 to 2.995 pmol mg−1 albumin (mean±standard deviation = 0.89±0.46) and was categorized based on the median as low (<0.80 pmol mg−1) or high (⩾0.80 pmol mg−1) and used in the analyses. By multivariate analysis, significantly higher levels of AFB1 were obtained for participants who reported symptoms of acute aflatoxicosis: history of yellow mouth (odds ratio = 5.5, confidence interval = 1.04–29.07, p = 0.04); history of sore swollen stomach (odds ratio = 4.54, confidence interval = 1.28–15.62, p = 0.01). A history of painful vomiting was marginally associated (p = 0.09) with high AFB1 levels. Between 30 and 40% of the study group had abnormal liver function and HBV/HCV infections. Total protein and alanine transaminase (ALT) were positively correlated to AFB1 levels (p<0.01 and p = 0.02, respectively). For every unit increase in AFB1, total protein increased by 0.27 units and ALT increased by 0.20 units. HBV was associated with high AFB1 levels (p = 0.055) and HCV was marginally associated with low AFB1 levels (p = 0.08). Approximately 20% of study participants were positive for malaria antigen in blood. A number of symptoms and disease markers were not significantly associated with AFB1.Conclusions. These results show high levels of AFB1 and symptoms of acute aflatoxicosis in a population that also has high levels of HBV/HCV infections and abnormal liver function. Thus, a high proportion of these study participants are at significant risk of developing hepatocellular carcinoma.

Is correction for protein concentration appropriate for protein adduct dosimetry? Hypothesis and clues from an aflatoxin B1‐exposed population

Protein adducts are useful biomarkers for assessing exposure, metabolism and risk of carcinogens. Aflatoxin B1-albumin adducts (AAA) and protein carbonyl content (PCC) have long been used for assessing aflatoxin exposure and oxidative stress to proteins, and the quantitative data are almost exclusively expressed per mg protein. Given the large variation in protein concentrations in plasma among populations, this may not be the most appropriate method. The objective was to test the hypothesis that AAA and PCC should be expressed per mL plasma in population studies. AAA and PCC were analyzed among 402 subjects from three regions of China with a gradient in hepatocellular carcinoma (HCC) mortality ranging from 21 to 97 per 100,000. When biomarker values were expressed per mL plasma, the AAA level was significantly associated with plasma PCC (r = 0.262, P < 0.001), and adjusted levels of AAA and PCC paralleled HCC mortalities in the three regions, suggesting a role for aflatoxin-related oxidative stress in hepatocarcinogenesis in this population. In addition, there were statistically significant associations between both protein biomarkers, expressed per mL plasma, and the levels of alanine aminotransferase and aspartate aminotransferase in hepatitis B virus-infected subjects, suggesting roles for aflatoxin exposure, oxidative stress and hepatitis B virus infection in the development of HCC. The present data suggest that interindividual variation in plasma protein concentration may influence the dosimetry and relevant interpretation of protein biomarkers.

Aflatoxin B1 albumin adduct levels and cellular immune status in Ghanaians

Although aflatoxins (AFs) have been shown to be immune-suppressive agents in animals, the potential role of AFs in modifying the distribution and function of leukocyte subsets in humans has never been assessed. We examined the cellular immune status of 64 Ghanaians in relation to levels of aflatoxin B1 (AFB1)-albumin adducts in plasma. The percentages of leukocyte immunophenotypes in peripheral blood, CD4+ T cell proliferative response, CD4+ T(h) and CD8+ T cell cytokine profiles and monocyte phagocytic activity were measured using flow cytometry. NK cell cytotoxic function was determined by perforin and tumor necrosis factor-alpha expression in CD3-CD56+ NK cells. AFB1-albumin adducts levels ranged from 0.3325 to 2.2703 (mean = 0.9972 +/- 0.40, median = 0.9068) pmol mg(-1) albumin. Study participants with high AFB1 levels had significantly lower percentages of CD3+ and CD19+ cells that showed the CD69+ activation marker (CD3+CD69+ and CD19+CD69+) than participants with low AFB1 levels (P = 0.002 for both). Also, the percentages of CD8+ T cells that contained perforin or both perforin and granzyme A were significantly lower in participants with high AFB1 levels compared with those with low AFB1 (P = 0.012 for both). Low levels of CD3+CD69+ (r = -0.32, P = 0.016) and CD19+CD69+ (r = -0.334, P = 0.010) cells were significantly associated with high AFB1 levels using correlation analysis. By multivariate analysis, there were strong negative correlations between the percentages of these cells (CD3+CD69+: b = -0.574, P = 0.001, and CD19+CD69+: b = -0.330, P = 0.032) and AFB1 levels. These alterations in immunological parameters in participants with high AFB1 levels could result in impairments in cellular immunity that could decrease host resistance to infections.

Epidemiological characteristics and risk factors of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the major cancers in the world. There is a striking variation in HCC incidence rates between various countries, with a highest-to-lowest ratio of 112.5 for males and 54.7 for females. The high-risk populations are clustered in sub-Saharan Africa and eastern Asia. The male-to-female ratio for HCC ranges from < 1 to 6.4 and mostly from 2 to 4. There exist significant variations in the incidence of HCC among different ethnic groups living in the same area and among migrants of the same ethnic groups living in different areas. The age curves of HCC are significantly different in various countries, suggesting variability in exposure to risk factors. Chronic carriers of hepatitis B and C viruses (HBV and HCV, respectively) have an increased risk of HCC. The relative and attributable HCC risk of HBV and HCV carrier status varies in different countries. There exists a synergistic interaction on HCC between the two viruses. Aflatoxin exposure, cigarette smoking, heavy alcohol consumption, low vegetable intake, inorganic arsenic ingestion, radioactive thorium dioxide exposure, iron overload and the use of oral contraceptives and anabolic steroids have been documented as HCC risk factors. Recent molecular epidemiological studies have shown that low serum retinol levels as well as elevated serum levels of testosterone, neu oncoprotein and aflatoxin B1-albumin adduct are associated with an increased HCC risk. There is a synergistic interaction on HCC between chronic HBV infection and aflatoxin exposure. Familial aggregation of HCC exists and a major susceptibility gene of HCC has been hypothesized. Patients of some genetic diseases are at an increased risk of HCC. The genetic polymorphisms of cytochrome P450 2E1 and 2D6 and arylamine N-acetyltransferase 2 are associated with the development of HCC. A dose-response relationship between aflatoxin exposure and HCC has been observed among chronic HBV carriers who have null genotypes of glutathione S-transferase M1 or T1, but not among those who have non-null genotypes. Human hepatocarcinogenesis is a multistage process with the involvement of a multifactorial aetiology. Gene-environment interactions are involved in the development of HCC in humans.