Aflatoxin B1 Occurrence in Children under the Age of Five's Food Products and Aflatoxin M1 Exposure Assessment and Risk Characterization of Arab Infants through Consumption of Infant Powdered Formula: A Lebanese Experience.

Aflatoxin M1 (AFM1) is a salient metabolite that can be used to assess Aflatoxin B1 (AFB1) exposure in humans and animals. The carcinogenic potency of AFB1 and AFM1 was severely reported. The aims of this study were (1) to survey the contamination level of AFM1 in the most traded infant powdered formula brands (IPF) (n = 42) along with the AFB1 level in under 5's children food brands (biscuits, cornflakes, and cereals) (n = 42) and (2) to assess the estimated daily intake (EDI), the hazard quotient (HQ) and the margin of exposure (MOE) of AFM1 among infants (0-12 months) in Lebanon. All of the samples were analyzed using ELISA technique. AFB1 was below detection limit in all of the children's food brands samples. Out of 42 IPF samples 9.5% were AFM1-positive in the range of 29.54-140.16 ng/L and exceeded the maximum tolerable limit (MTL) set by the European commission (25 ng/kg). The overall average contamination level was 5.72 ± 0.014 ng/L. The EDI of AMF1 for male was in the range of 0.37-0.78 ng/kg/b.w./day and 0.40-0.87 ng/kg/b.w./day for females. Similarly, the HQ calculation resulted in an average of 3.05 for males and 3.28 for females. MOE calculations were far lower from 10,000 in both genders which indicates a high risk of genotoxicity and carcinogenicity. Our findings show that AFM1's EDI, HQ and MOE scored high among Lebanese infants. As infants consume more IPF relative to their body weight, the persistence of IPF with high AFM1 levels threatens their health. Thus, infant's exposure risk to AFM1 in IPF should be a continuous focus of attention.

Hormones residues in bovine animals: Sampling, analysis and health risk assessment.

The use of hormones for breeding animal livestock has been banned since 1981 under the Council Directive 81/602/EC. So far, each country should monitor the use of anabolic hormones in animal production to protect the consumer's health against these unwanted residues. This paper presents the research results on steroid and non-steroid hormones residues carried out in Lebanon from 2018 to 2020. Using a newly developed and validated LC-MS/MS method, the detection and the quantification of hormones in bovine matrices were done. The targeted matrices were muscle, liver, kidney, and bile. A total of two-hundred and forty-seven samples were collected from different slaughterhouses located in six different cities in Lebanon. Interestingly, only four hormones were found: testosterone, progesterone, epitestosterone, and 6 propyl 2thiouracil. Based on the obtained data, the estimated daily intake, hazard quotient, and hazard index were calculated to evaluate an exposure assessment.

Chromatographic methods for the determination of a broad spectrum of UV filters in swimming pool water.

This paper describes an analytical approach based on solid-phase extraction (SPE) followed by analysis using liquid and gas chromatography coupled to mass spectrometry detectors for a determination of 18 organic UV filters from water samples. Extraction method parameters were optimized: 250 ml of water sample loaded on Chromabond C18 cartridges after adjustment to pH 4 and then eluted with acetonitrile. The mobile phase and the parameters of the mass spectrometer, as well as those of the ionization source, were tested to enhance detection sensitivity. During method validation, the extracted target compounds showed good recoveries (> 68%) with acceptable values in terms of repeatability (RSDr) and reproducibility (RSDR), where relative standard deviations values were lower than 20%. The validated method was applied to 10 water samples collected from different swimming pools located in Lebanon from which eight UV filters among the eighteen targets compounds were detected at concentrations ranged between 1 and 2526 µg L-1. The most detected compounds were padimate-O (OD-PABA) and octocrylene (OCR). This study represents the first available data on the occurrence of UV filter residues in Lebanese swimming pool opening hence future perspectives and insights to evaluate their degradation by-products and their toxicity on human health and marine ecosystem.

LC-MS/MS method for the determination of hormones: Validation, application and health risk assessment in various bovine matrices.

A new method, using liquid chromatography coupled to mass spectrometry (LC-MS/MS) for the detection of fourteen natural and synthetic hormones in muscles, was validated in other bovine matrices (liver, kidney, bile and hair) according to the Decision Commission 2002/657/EC. As result, this method demonstrates good linearity (R2 > 0.99) as well as accuracy with coefficients of variation for repeatability and reproducibility lower than 23%. Moreover, the values of decision limit (CCα) and detection capability (CCß) were determined indicating values ranging from 0.13 to 0.86 µg/kg and 0.25-1.72 µg/k for the majority of analytes. Recovery rate in the different matrices varied from 51.5 to 107%. Indeed, this method has been successfully applied to detect anabolic hormones in eighty-eight samples (muscle, liver, kidney, and bile) collected from different local slaughterhouses. Results showed that progesterone was found in 30 samples at concentrations ranging from 0.11 to 11.7 µg/kg, while testosterone was detected in 34 samples at concentrations ranging from 0.5 to 9.52 µg/kg. All bile samples contain epi-testosterone at concentration ranging from 0.89 to 280 µg/kg. These obtained data were used to calculate the estimated daily intake, hazard quotient and hazard index as exposure assessment.

Autophosphorylation activation and inhibition by curcumin of the epidermal growth factor receptor reconstituted in liposomes.

The epidermal growth factor receptor (EGFR) is a 170-kDa transmembrane protein with intrinsic protein kinase activity. It is involved in the regulation of essential cellular processes such as proliferation, differentiation, survival, and migration. An increase in EGFR activity has been correlated to malignant evolution of the cells. We have used proteoliposomes as a platform to study the mechanism of activation and inhibition of EGFR. We have been able to reconstitute functional EGFR in liposomes through detergent removal by Bio-Beads and have measured the receptor dimerization and its autophosphorylation resulting from its inherent tyrosine kinase activity. In particular, we have studied the activation of autophosphorylation by the natural ligand epidermal growth factor and its inhibition by curcumin, a polyphenol from Curcuma longa. This artificial membrane model provides a convenient tool to both qualitatively and quantitatively elucidate the mechanism of activation and inhibition of EGFR. It allows studying the isolated receptor under well-defined conditions, which enables one to use a number of biochemical and physico-chemical techniques that are difficult to put into practice with living cells. We believe that this platform can be used as a systematic screening tool for membrane receptor modulators, which are potential drug candidates.

A tethered bilayer assembled on top of immobilized calmodulin to mimic cellular compartmentalization.

BACKGROUND: Biomimetic membrane models tethered on solid supports are important tools for membrane protein biochemistry and biotechnology. The supported membrane systems described up to now are composed of a lipid bilayer tethered or not to a surface separating two compartments: a "trans" side, one to a few nanometer thick, located between the supporting surface and the membrane; and a "cis" side, above the synthetic membrane, exposed to the bulk medium. We describe here a novel biomimetic design composed of a tethered bilayer membrane that is assembled over a surface derivatized with a specific intracellular protein marker. This multilayered biomimetic assembly exhibits the fundamental characteristics of an authentic biological membrane in creating a continuous yet fluid phospholipidic barrier between two distinct compartments: a "cis" side corresponding to the extracellular milieu and a "trans" side marked by a key cytosolic signaling protein, calmodulin. METHODOLOGY/PRINCIPAL FINDINGS: We established and validated the experimental conditions to construct a multilayered structure consisting in a planar tethered bilayer assembled over a surface derivatized with calmodulin. We demonstrated the following: (i) the grafted calmodulin molecules (in trans side) were fully functional in binding and activating a calmodulin-dependent enzyme, the adenylate cyclase from Bordetella pertussis; and (ii) the assembled bilayer formed a continuous, protein-impermeable boundary that fully separated the underlying calmodulin (trans side) from the above medium (cis side). CONCLUSIONS: The simplicity and robustness of the tethered bilayer structure described here should facilitate the elaboration of biomimetic membrane models incorporating membrane embedded proteins and key cytoplasmic constituents. Such biomimetic structures will also be an attractive tool to study translocation across biological membranes of proteins or other macromolecules.