Estimated 24-hour urinary sodium excretion as a risk factor for oxidative stress in Zambian adults: A cross-sectional study.

INTRODUCTION: Persistent oxidative stress predisposes to various non-communicable diseases (NCDs), whose occurrence is increasing in sub-Saharan Africa. The aim of this study was to evaluate the link between markers of oxidative stress and some risk factors for NCDs in a Zambian cohort. METHODS: We assessed oxidative stress by measuring 8-isoprostane (lipid oxidative stress) and 8-hydroxydeoxyguanosine (DNA oxidative stress). In addition, we measured mycotoxins (aflatoxin M1 and ochratoxin A), salt intake estimated from 24-hour sodium excretion calculated using the Tanaka and Kawaski formulae, and 1-hydroxypyrene (a metabolite of polycyclic aromatic hydrocarbons). Data on lifestyle risk factors were collected using questionnaires. RESULTS: Included were 244 participants; 128 (52%) were female and the median age was 48 years (IQR 39-58). The median level of 8-isoprostane was 0.13 ng/mg creatinine (IQR 0.08-0.23) while that of 8-hydroxydeoxyguanosine (8-OHdG) was 4 ng/mg creatinine (IQR 2-10). The median 24-hour sodium excretion was 21 g (IQR 16-25 g), with none being less than the 5 g recommended by WHO. Unadjusted urinary levels of 8-isoprostane were moderately correlated with 1-hydroxypyrene (Spearman r = 0.30, p<0.001) and estimated 24-hour urine sodium (Spearman r = 0.38, p<0.001). Urinary levels of 8-OHdG were not correlated with 1-hydroxypyrene, estimated 24-hour urine sodium, aflatoxin M1 or ochratoxin A (all p-values >0.05). Using logistic regression, adjusted and unadjusted 8-isoprostanes levels were associated with 1-hydroxypyrene (p = 0.02 and p = 0.001 respectively) and estimated 24-hour urine sodium method (p = 0.003 and p<0.001 respectively). However, only unadjusted 8-OHdG was associated with 1-hydroxypyrene (p = 0.03) and age (p = 0.007). CONCLUSIONS: Estimated 24-hour urinary sodium is high among Zambians and it is associated with lipid but not DNA oxidative stress. High exposure to polycyclic aromatic hydrocarbons is also associated with oxidative stress.

Study of aflatoxicosis reduction: effect of Alchornea cordifolia on biomarkers in an aflatoxin B1 exposed rats.

The toxicity of aflatoxins results in cancer and liver disease. Several natural substances such as plants exhibited their ability to inhibit the initiation of aflatoxin carcinogenesis. The aim of this study was to evaluate the effect of Alchornea cordifolia on biomarkers in an aflatoxin B1 (AFB1) exposed rats. The contents of polyphenols, flavonoids and the antioxidant activity of A. cordifolia ethanolic leaf extract (EELac) were assessed. Groups of rats were treated orally with a daily dose of a mixture of AFB1 at a dose of 150 µg/kg body weight and EELac (50, 100 and 300 mg/kg body weight) for 21 days. Biomarkers of AFB1, such as the AFB1-lysine adduct and aflatoxin M1 were assayed in blood and urine, respectively, using an HPLC system with a fluorescence detector. The contents of polyphenols and flavonoids were 6783.23 ± 272.76 µg EAG/g and 10.54 ± 3.15% of dry matter, respectively. EELac showed a good antioxidant activity (IC50 = 12.65 ± 0.13 µg/mL). The administration of the mixture (AFB1 + EELac) at different doses significantly reduced the level of AFB1-lysine adduct from 14.04 ± 2.1 to 4.13 ± 0.9 ng/mg albumin and that of Aflatoxin M1 (AFM1) from 456 ± 16 to 220 ± 24 ng/mL (p <0.05). The rate of reduction was 70.58% for AFB1-lysine adduct and 51.75% for AFM1. A. cordifolia could be used in the prevention of toxicity induced by AFB1 on account of its high content in phenolic compounds.

A novel electrochemical aptasensor for detection of aflatoxin M1 based on target-induced immobilization of gold nanoparticles on the surface of electrode.

In this study, a novel electrochemical aptasensor was developed for detection of AFM1 aflatoxin M1 (AFM1) based on the hairpin-shaped structure of AFM1 aptamer (Apt), gold nanoparticles (AuNPs) and complementary strand of the aptamer (CS). The conformational change of hairpin structure of Apt in the presence and absence of AFM1 and also negatively charged AuNPs allowed detection of AFM1 with high sensitivity and selectivity. In the absence of the AFM1, the hairpin structure of the Apt was intact. So, a weak peak current was obtained. However, addition of AFM1 could disassemble the hairpin structure of the Apt. Thus, the CS-modified AuNPs came to close proximity of the surface of electrode and a strong current signal was recorded upon the addition of methylene blue as redox agent. The aptasensor allowed determination of AFM1 with a detection limit of 0.9 ng/L. Finally, the aptasensor was successfully applied for detection of AFM1 in real samples, including milk and serum samples.

Comparison of urinary aflatoxin M1 and aflatoxin albumin adducts as biomarkers for assessing aflatoxin exposure in Tanzanian children.

PURPOSE: To determine levels of urinary aflatoxin M1 (AFM1) in children and correlate the concentrations with previously reported aflatoxin albumin adduct (AF-alb) levels in these children. MATERIALS AND METHODS: Matched urine and blood samples were collected from 84 Tanzanian children aged 6-14 months old. From 31 children in one village (Kigwa), samples were collected at three time points six months apart. Samples were collected from 31 and 22 children from two different regions at the second time point only. Urinary AFM1 was measured using a commercial enzyme-linked immunosorbent assay (ELISA) kit with a modified protocol to improve sensitivity. AF-alb was measured using an established ELISA method. RESULTS: The relative ranking of the three villages for exposure to aflatoxin based on either AFM1 or AF-alb biomarker measurements was the same. In Kigwa village, both AFM1 and AF-alb levels were higher at six months post-harvest compared to baseline. However, at the next visit, the AFM1 levels dropped from a GM (interquartile range) of 71.0 (44.7, 112.6) at visit two to 49.3 (31.5, 77.3) pg/ml urine, whereas AF-alb levels increased from 47.3 (29.7, 75.2) to 52.7 (35.4, 78.3) pg/mg albumin between these two visits, reflecting the fact that AFM1 measures short-term exposure, whereas AF-alb measures longer term exposure. There was a correlation between AFB1 intake and AFM1 excretion (r= 0.442, p ≤ 0.001). CONCLUSIONS: Urinary AFM1 is a good biomarker for AFB1 exposure in Tanzanian children, reflecting geographical and temporal variations in exposure to this foodborne toxin.

Detection of aflatoxin among hepatocellular carcinoma patients in Egypt.

The present research were tempted to investigate whether Aflatoxin is an additive factor in development of HCC through detecting its metabolite Aflatoxin Ml1 in serum and urine of HCC and cirrhotics in Egypt. Present study comprised (46) Hepatocellular Carcinoma (HCC) patients with mean age (56.28 +/- 8.08), 30 males and 16 females, (12) cirrhotic patients with mean age (47.83 +/- 18.20), 7 males and 5 females and (12) sex and age matched healthy controls. All were exposed to, liver function tests, abdominal ultrasonography and detection of Aflatoxin metabolite M1 in serum and urine by means of the reverse phase HPLC device. Aflatoxin M1 was detected in sera of HCC group, cirrhotics and controls (57.8%) (5.61 +/- 17.21 ng mL(-1)), (91.7%) (19.23 +/- 20.42 ng mL(-1)) and (50%) (0.66 +/- 0.84 ng mL(-1)), respectively and in urine (41.3%) (3.82 +/- 8.03 ng mL(-1)) (91.7%) (43.22 +/- 45.02 ng mL(-1)) and (50%) (0.98 +/- 1.4 ng mL(-1)), respectively representing significant increase in the serum of the cirrhotic group (p < 0.02) and a high significant increase in urine of the cirrhotic group (p < 0.0001). Among HCC group patients, there is high significant value of M1 concentration in urine of upper Egypt residents compared to those of lower Egypt (p < 0.002). The mean value of Aflatoxin M1 concentration among females of the HCC group was significantly higher than that among males (p = 0.006). There is higher statistical significance of aflatoxin prevalence and concentration in serum and urine ofcirrhotics than HCC patients and controls and in concentration in urine of HCC patients from upper than lower Egypt.

Morbidity in neonates of mothers who have ingested aflatoxins.

This study was undertaken to assess whether aflatoxin M(1) concentrations in newborn infants correlated with those of their mothers and to determine whether the presence of aflatoxin M(1) in cord blood was associated with an increase in morbidity in the newborn. There was a strong correlation (r =0.797, p <0.0001) between mothers' and cord blood levels of aflatoxin. There was also a strong negative correlation between aflatoxin levels and birthweight (r =-0.565, p <0.001) but there was no association between aflatoxin M(1) concentration in maternal or cord blood and rates of jaundice or infection.