Last data update: Jan 27, 2025. (Total: 48650 publications since 2009)
Records 1-5 (of 5 Records) |
Query Trace: Zitomer N[original query] |
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Association between low maternal serum aflatoxin B1 exposure and adverse pregnancy outcomes in Mombasa, Kenya, 2017-2019: A nested matched case-control study
Osoro E , Awuor AO , Inwani I , Mugo C , Hunsperger E , Verani JR , Nduati R , Kinuthia J , Okutoyi L , Mwaengo D , Maugo B , Otieno NA , Mirieri H , Ombok C , Nyawanda B , Agogo GO , Ngere I , Zitomer NC , Rybak ME , Munyua P , Njenga K , Widdowson MA . Matern Child Nutr 2024 e13688 We examined the association between serum aflatoxin B1-lysine adduct (AFB1-lys) levels in pregnant women and adverse pregnancy outcomes (low birthweight, miscarriage and stillbirth) through a nested matched case-control study of pregnant women enroled at ≤28 weeks' gestation in Mombasa, Kenya, from 2017 to 2019. Cases comprised women with an adverse birth outcome, defined as either delivery of a singleton infant weighing <2500 g, or a miscarriage, or a stillbirth, while controls were women who delivered a singleton live infant with a birthweight of ≥2500 g. Cases were matched to controls at a ratio of 1:2 based on maternal age at enrolment, gestational age at enrolment and study site. The primary exposure was serum AFB1-lys. The study included 125 cases and 250 controls. The median gestation age when serum samples were collected was 23.0 weeks (interquartile range [IQR]: 18.1-26.0) and 23.5 (IQR: 18.1-26.5) among cases and controls, respectively. Of the 375 tested sera, 145 (38.7%) had detectable serum AFB1-lys: 36.0% in cases and 40.0% in controls. AFB1-lys adduct levels were not associated with adverse birth outcomes on multivariable analysis. Mid-upper arm circumference was associated with a 6% lower odds of adverse birth outcome for every unit increase (p = 0.023). Two-fifths of pregnant women had detectable levels of aflatoxin midway through pregnancy. However, we did not detect an association with adverse pregnancy outcomes, likely because of low serum AFB1-lys levels and low power, restricting meaningful comparison. More research is needed to understand the public health risk of aflatoxin in pregnant women to unborn children. |
Assessing the impacts of preanalytical field sampling challenges on the reliability of serum aflatoxin B1-lysine measurements by use of LC-MS/MS
Zitomer NC , Rybak ME , Sternberg MR . Toxins (Basel) 2022 14 (9) Aflatoxin exposure is endemic in developing countries with warm, humid climates that promote toxigenic mold growth on crops and foodstuffs. Estimating human aflatoxin exposure is key to identifying and abating contamination sources. Serum aflatoxin B1 bound to albumin lysine (AFB1-lys) is a preferred exposure biomarker, but field sample collection, processing, transportation, and storage logistics are challenging. We validated an improved LC-MS/MS method for serum AFB1-lys and applied it to three field sampling challenges: transportation/storage (elevated temperature); collection/processing (hemolysis); and sample type substitution (heparinized plasma). Our new LC-MS/MS method had a LOD of 0.03 ng/mL, accuracy (mean spike recovery) of 112%, total imprecision (replicate pool measurements) 5% at 0.2 ng/mL, and results that were 95.1% similar (mean percentage similarity) to an established method. AFB1-lys in human serum spiked with serum from aflatoxin-dosed rats was stable for 14 days at both ambient (22.5 C) and elevated (38 C) temperatures. Simulated hemolysis (adding 0.25-3 mg hemoglobin) did not affect AFB1-lys accuracy at 0.5 ng/mL but caused 10-25% signal suppression. Heparinized plasma AFB1-lys was 99.0% similar to serum but interfered with albumin measurements (bromocresol green) causing spurious low bias. Further investigation is warranted, but our findings suggest that AFB1-lys is pre-analytically robust. |
Human aflatoxin exposure in Uganda: Estimates from a subset of the 2011 Uganda AIDS indicator survey (UAIS)
Zitomer NC , Awuor AO , Widdowson MA , Daniel JH , Sternberg MR , Rybak ME , Mbidde EK . Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2020 38 (1) 1-12 Aflatoxins are carcinogenic mycotoxins that contaminate a variety of crops worldwide. Acute exposure can cause liver failure, and chronic exposure can lead to stunting in children and liver cancer in adults. We estimated aflatoxin exposure across Uganda by measuring a serum biomarker of aflatoxin exposure in a subsample from the 2011 Uganda AIDS Indicator Survey, a nationally representative survey of HIV prevalence, and examined its association with geographic, demographic, and socioeconomic variables. We analysed a subsample of 985 serum specimens selected among HIV-negative participants from 10 survey-defined geographic regions for serum aflatoxin B1-lysine (AFB1-lys) by use of isotope dilution LC-MS/MS and calculated results normalised to serum albumin. We used statistical techniques for censored data to estimate geometric means (GMs), standard deviations, and percentiles. We detected serum AFB1-lys in 71.7% of specimens (LOD = 0.5 pg/mg albumin). Unadjusted GM AFB1-lys (pg/mg albumin) was 1.33 (95% CI: 1.21-1.47). Serum AFB1-lys was higher in males (GM: 1.57; 95% CI: 1.38-1.80) vs. females (GM: 1.12; 95% CI: 0.97-1.30) (P = .0019), and higher in persons residing in urban settings (GM: 2.83; 95% CI: 2.37-3.37) vs. rural (GM: 1.10; 95% CI: 0.99-1.23) (P < .0001). When we used a multivariable censored regression model to assess confounding and interactions among variables we found that survey region, gender, age, occupation, distance to marketplace, and number of meals per day were statistically significant predictors of aflatoxin exposure. While not nationally representative, our findings provide an improved understanding of the widespread burden of aflatoxin exposure throughout Uganda and identify key geographic, demographic, and socioeconomic factors that may modulate aflatoxin exposure risk. |
Evaluation of efficacy, acceptability and palatability of calcium montmorillonite clay used to reduce aflatoxin B1 dietary exposure in a crossover study in Kenya
Awuor AO , Montgomery J , Yard E , Martin C , Daniel J , Zitomer N , Rybak M , Lewis L , Phillips T , Romoser A , Elmore S , Oyugi E , Amwayi S , Bii C , Vulule J . Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2016 34 (1) 93-102 Acute aflatoxin exposure can cause death and disease (aflatoxicosis) in humans. Aflatoxicosis fatality rates have been documented to be as high as 40% in Kenya. The inclusion in the diet of calcium silicate 100 (ACCS100), a calcium montmorillonite clay, may reduce aflatoxin bioavailability; thus potentially decreasing the risk of aflatoxicosis. We investigated the efficacy, acceptability, and palatability of ACCS100 in a population in Kenya with recurring aflatoxicosis outbreaks. Healthy adult participants were enrolled in this double-blinded, cross-over clinical trial in 2014. Following informed consent, participants (n=50) were randomized to receive either ACCS100 (3g/day) or placebo (3g/day) for seven days. Treatments were switched following a five-day washout period. Urine samples were collected daily and assessed for urinary aflatoxin M1 (AFM1). Blood samples were collected at the beginning and end of the trial and assessed for aflatoxin B1-lysine adducts from serum albumin (AFB1-lys). AFM1 concentrations in urine; were significantly reduced while taking ACCS100 compared to calcium carbonate placebo (beta=0.49, 95% confidence limit: 0.32-0.75). The 20 day interval included both the placebo and ACCS100 treatments as well as a washout period. There were no statistically significant differences in reported taste, aftertaste, appearance, color, or texture by treatment. There were no statistically significant differences in self-reported adverse events by treatment. Most participants would be willing to take ACCS100 (98%) and give it to their children (98%). ACCS100 was effective, acceptable, and palatable. More work is needed to test ACCS100 among vulnerable populations and to determine if ACCS100 remains effective at the levels of aflatoxin exposure that induce aflatoxicosis. |
Determination of Aflatoxin B1 in Smokeless Tobacco Products by Use of UHPLC-MS/MS
Zitomer N , Rybak ME , Li Z , Walters MJ , Holman MR . J Agric Food Chem 2015 63 (41) 9131-8 This work developed a UHPLC-MS/MS method for the detection and quantitation of aflatoxins in smokeless tobacco products, which was then used to determine aflatoxin B1 concentrations in 32 smokeless tobacco products commercially available in the United States. Smokeless tobacco products were dried, milled, and amended with 13C17-labeled internal standards, extracted in water/methanol solution in the presence of a surfactant, isolated through use of immunoaffinity column chromatography, and reconstituted in mobile phase prior to UHPLC-MS/MS analysis. The method was capable of baseline separation of aflatoxins B1, B2, G1, and G2 in a 2.5 min run by use of a fused core C18 column and a water/methanol gradient. MS/MS transition (m/z) 313.3 --> 241.2 was used for aflatoxin B1 quantitation, with 313.3 --> 285.1 used for confirmation. The limit of detection (LOD) for aflatoxin B1 was 0.007 parts per billion (ppb). Method imprecision for aflatoxin B1 (expressed as coefficient of variation) ranged from 5.5 to 9.4%. Spike recoveries were 105-111%. Aflatoxin B1 concentrations in the smokeless tobacco products analyzed ranged from <LOD to 0.271 ppb (dry mass). Aflatoxin B1 was most frequently detected in dry snuffs and chews, whereas all moist snuff products tested were below LOD. The amounts of aflatoxin B1 detected were low relative to the 20 ppb regulatory limit established by the U.S. Food and Drug Administration for foods and feeds. |
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