Publications by authors named "David E Lefebvre"

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzyme deficiency in the world and renders those affected susceptible to potentially severe oxidative hemolysis. Although the resulting hemolysis is most often associated with drug exposure, it has also been reported after consumption of certain foods. With the exception of review articles that reiterated the historical knowledge that fava beans can provoke severe oxidative hemolysis in individuals with G6PD deficiency, very few articles have examined the safety of other food ingredients and food additives for people with G6PD deficiency.

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The presence of the mycotoxin ochratoxin A (OTA) in cereal grains is due to the growth of toxigenic Penicillium mold on stored crops. Human exposure to OTA is higher in infants, toddlers, and children than in adolescents and adults, based on exposure assessments of ng OTA consumed/kg body weight/day. Ochratoxin A is nephrotoxic and teratogenic in animals, but its effects on juveniles exposed during the reproduction and development period have not been studied.

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The chemical amaranth (AM) is permitted as a colouring agent in a variety of foods. Safety was established based on chronic rodent studies. AM and its metabolite naphthionic acid (NA) can be absorbed through the intestine, exposing circulating immune cells including splenocytes.

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The brominated flame retardant TBECH is used as an additive to delay ignition and inhibit fires in construction materials and consumer goods. Trends in human exposure are not clear, although humans may be exposed to TBECH via indoor dust and air. In birds and fish there is some evidence of disruption in endocrine and reproductive parameters due to TBECH.

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Humans could become exposed to carbon black nanoparticles (CBNPs) in consumer products or an occupational setting. In rodent models, acute respiratory, subcutaneous, and direct immune cell exposure to CBNPs has been shown to enhance allergic sensitization to co-administered ovalbumin (OVA) protein from chicken egg. However, little is known about the effects of ingested CBNPs on immunological responses and oral tolerance to food antigens.

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Exposure to the mycotoxin ochratoxin A (OTA) causes nephropathy in domestic animals and rodents and renal tumors in rodents and poultry. Humans are exposed to OTA by consuming foods made with contaminated cereal grains and other commodities. Management of human health risks due to OTA exposure depends, in part, on establishing a mode of action (MOA) for OTA carcinogenesis.

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Many natural chemicals in food are in the nanometer size range, and the selective uptake of nutrients with nanoscale dimensions by the gastrointestinal (GI) tract is a normal physiological process. Novel engineered nanomaterials (NMs) can bring various benefits to food, e.g.

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Engineered metal/mineral, lipid and biochemical macromolecule nanomaterials (NMs) have potential applications in food. Methodologies for the assessment of NM digestion and bioavailability in the gastrointestinal tract are nascent and require refinement. A working group was tasked by the International Life Sciences Institute NanoRelease Food Additive project to review existing models of the gastrointestinal tract in health and disease, and the utility of these models for the assessment of the uptake of NMs intended for food.

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The increasing use of zinc oxide nanoparticles (ZnO-NPs) has raised concerns about their potential hazards to human and environmental health. In this study, the characterization and cytotoxicity of two ZnO-NPs products (Z-COTE and Z-COTE HP1) were investigated. The zinc content of Z-COTE and Z-COTE HP1 was 82.

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Agglomerated carbon black nanoparticles (CBNPs) administered via respiratory or subcutaneous routes have been shown to promote allergic sensitization to coadministered ovalbumin (OVA) protein in rodents. In the present study, we aimed to model and elucidate the mechanism of this adjuvanticity using an in vitro assay based on T cell sensitization to ovalbumin₃₂₃₋₃₃₉ peptide (OVA(p)). CBNP base particles of 22 and 39 nm were characterized and termed CBNP22 and CBNP39 powders.

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We are exposed to millions of microbial and dietary antigens via the gastrointestinal tract, which likely play a key role in type 1 diabetes (T1D). We differentiated the effects of these two major environmental factors on gut immunity and T1D. Diabetes-prone BioBreeding (BBdp) rats were housed in specific pathogen-free (SPF) or germ-free (GF) conditions and weaned onto diabetes-promoting cereal diets or a protective low-antigen hydrolyzed casein (HC) diet, and T1D incidence was monitored.

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Brominated diphenyl ethers (BDEs) are persistent environmental contaminants found in human blood, tissues, and milk. To assess the impact of the commercial BDE mixture DE-71 on the developing immune system in relation to hepatic and thyroid changes, adult (F0) rats were exposed to DE-71 by gavage at doses of 0, 0.5, 5, or 25 mg/kg body weight (bw)/d for 21 weeks.

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Objective: There is evidence of gut barrier and immune system dysfunction in some patients with type 1 diabetes, possibly linked with exposure to dietary wheat polypeptides (WP). However, questions arise regarding the frequency of abnormal immune responses to wheat and their nature, and it remains unclear whether such responses are diabetes specific.

Research Design And Methods: In type 1 diabetic patients and healthy control subjects, the immune response of peripheral CD3(+) T-cells to WPs, ovalbumin, gliadin, alpha-gliadin 33-mer peptide, tetanus toxoid, and phytohemagglutinin was measured using a carboxyfluorescein diacetate succinimidyl ester (CFSE) proliferation assay.

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Perfluorooctanesulfonate (PFOS) is a stable and environmentally persistent metabolic or degradation product of perfluorooctanyl compounds that were manufactured for a variety of industrial and consumer applications. PFOS itself was sold for use as a surfactant. The structurally related contaminants perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), and N-ethyl perfluorooctane sulfonamide (N-EtPFOSA) were shown to suppress immune responses in laboratory rodents.

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Type 1 diabetes is an autoimmune disease in which the patient's immune system destroys the insulin-secreting beta-cells in the pancreatic islets of Langerhans. A majority of cases is thought to occur as a result of gene-environment interactions. The identity of the environmental factors remains unknown mainly because of the difficulty in linking past exposures with later disease development.

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The differentiation of naive T-helper (Th) cells towards Th1 or Th2 cells is regulated by the transcription factors T-box expressed in T-cells (T-bet) and GATA-binding protein-3 (GATA-3). In the present study, the gene expression of T-bet and GATA-3 was measured by semi-quantitive reverse transcription polymerase chain reaction (RT-PCR) in Th1 and Th2 cells derived from purified splenic CD4+ T cells from DO11.10/Rag2(-/-) transgenic mice and control BioBreeding (BBc) Wistar rat splenic T cells stimulated under Th1 or Th2 conditions.

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