Publications by authors named "Stefanie Hessel-Pras"

Acrylamide (AA) is formed in foods due to thermal processes. AA was analysed in 230 foods in the first German Total Diet Study and the highest mean levels of AA were found in vegetable crisps (1430 μg/kg), followed by potato pancakes (558) μg/kg) and pan-fried potatoes (450 μg/kg). In various foods, e.

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Cytochrome P450 (CYP)3A4 induction by drugs and pesticides plays a critical role in the enhancement of pyrrolizidine alkaloid (PA) toxicity as it leads to increased formation of hepatotoxic dehydro-PA metabolites. Addressing the need for a quantitative analysis of this interaction, we developed a physiologically-based toxicokinetic (PBTK) model. Specifically, the model describes the impact of the well-characterized CYP3A4 inducer rifampicin on the kinetics of retrorsine, which is a prototypic PA and contaminant in herbal teas.

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Background: Cannabidiol (CBD), a non-intoxicating substance of Cannabis sativa L., is gaining consumer attention. Yet, legal regulations in the EU are complex and questions of potential health risks remain partly unanswered.

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The quinolizidine alkaloids matrine and its N-oxide oxymatrine occur in plants of the genus Sophora. Recently, matrine was sporadically detected in liquorice products. Morphological similarity of the liquorice plant Glycyrrhiza glabra with Sophora species and resulting confusion during harvesting may explain this contamination, but use of matrine as pesticide has also been reported.

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Genotoxicity data are mainly interpreted in a qualitative way, which typically results in a binary classification of chemical entities. For more than a decade, there has been a discussion about the need for a paradigm shift in this regard. Here, we review current opportunities, challenges and perspectives for a more quantitative approach to genotoxicity assessment.

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Retrorsine is a hepatotoxic pyrrolizidine alkaloid (PA) found in herbal supplements and medicines, food and livestock feed. Dose-response studies enabling the derivation of a point of departure including a benchmark dose for risk assessment of retrorsine in humans and animals are not available. Addressing this need, a physiologically based toxicokinetic (PBTK) model of retrorsine was developed for mouse and rat.

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Phytochemicals like pyrrolizidine alkaloids (PAs) can affect the health of humans and animals. PAs can occur for example in tea, honey or herbs. Some PAs are known to be cytotoxic, genotoxic, and carcinogenic.

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1,2-unsaturated pyrrolizidine alkaloids (PAs) represent a large group of secondary plant metabolites exhibiting hepatotoxic, genotoxic, and carcinogenic properties upon bioactivation. To examine how the degree of esterification affects the genotoxic profile of PA we investigated cytotoxicity, histone H2AX phosphorylation, DNA strand break induction, cell cycle perturbation, micronuclei formation, and aneugenic effects in different cell models. Analysis of cytotoxicity and phosphorylation of histone H2AX was structure- and concentration-dependent: diester-type PAs (except monocrotaline) showed more pronounced effects than monoester-type PAs.

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1,2-unsaturated Pyrrolizidine Alkaloids (PAs) are secondary plant metabolites that occur as food contaminants. Upon consumption, they can cause severe liver damage. PAs have been shown to induce apoptosis, to have cytotoxic and genotoxic effects, and to impair bile acid homeostasis in the human hepatoma cell line HepaRG.

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Scope: 1,2-unsaturated pyrrolizidine alkaloids (PAs) are secondary plant metabolites that are found in many plant species throughout the world. They are of concern for risk assessment as consumption of contaminated foodstuff can cause severe liver damage. Of late, transporter-mediated uptake and transport has advanced as a vital determinant of PA toxicity.

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Pyrrolizidine alkaloids (PAs) are secondary plant metabolites synthesized by a wide range of plants as protection against herbivores. These toxins are found worldwide and pose a threat to human health. PAs induce acute effects like hepatic sinusoidal obstruction syndrome and pulmonary arterial hypertension.

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Pyrrolizidine alkaloids (PAs) are a group of secondary plant metabolites being contained in various plant species. The consumption of contaminated food can lead to acute intoxications in humans and exert severe hepatotoxicity. The development of jaundice and elevated bile acid concentrations in blood have been reported in acute human PA intoxication, indicating a connection between PA exposure and the induction of cholestasis.

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1,2-unsaturated pyrrolizidine alkaloids (PAs) are secondary plant metabolites occurring as food contaminants that can cause severe liver damage upon metabolic activation in hepatocytes. However, it is yet unknown how these contaminants enter the cells. The role of hepatic transporters is only at the beginning of being recognized as a key determinant of PA toxicity.

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1,2-unsaturated pyrrolizidine alkaloids (PAs) belong to a group of secondary plant metabolites. Exposure to PA-contaminated feed and food may cause severe hepatotoxicity. A pathway possibly involved in PA toxicity is the disturbance of bile acid homeostasis.

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Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants produced by incomplete combustion of organic matter. They induce their own metabolism by upregulating xenobiotic-metabolizing enzymes such as cytochrome P450 monooxygenase 1A1 (CYP1A1) by activating the aryl hydrocarbon receptor (AHR). However, previous studies showed that individual PAHs may also interact with the constitutive androstane receptor (CAR).

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Pyrrolizidine alkaloids (PAs) are a group of secondary metabolites produced in various plant species as a defense mechanism against herbivores. PAs consist of a necine base, which is esterified with one or two necine acids. Humans are exposed to PAs by consumption of contaminated food.

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Carcinogenic benzo[a]pyrene (BP) and other non-carcinogenic polycyclic aromatic hydrocarbons (PAH) like fluoranthene (FA) and pyrene (PYR) occur as food contaminants. Molecular effects of BP, FA and PYR in human liver cells were investigated using mixtures occurring in grilled meat. Activation of aryl hydrocarbon receptor (AHR) and constitutive androstane receptor (CAR) was investigated along with target gene expression.

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Pyrrolizidine alkaloids (PA) are secondary plant metabolites that occur as food and feed contaminants. Acute and subacute PA poisoning can lead to severe liver damage in humans and animals, comprising liver pain, hepatomegaly and the development of ascites due to occlusion of the hepatic sinusoids (veno-occlusive disease). Chronic exposure to low levels of PA can induce liver cirrhosis and liver cancer.

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The biotoxin okadaic acid (OA) is a lipophilic secondary metabolite of marine microalgae. Therefore, OA accumulates in the fatty tissue of various shellfish and may thus enter the food chain. The ingestion of OA via contaminated marine species can lead to the diarrhetic shellfish poisoning syndrome characterized by the occurrence of a series of acute gastrointestinal symptoms in humans.

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Pyrrolizidine alkaloids (PAs) are widely occurring phytotoxins which can induce severe liver damage in humans and other mammalian species by mechanisms that are not fully understood. Therefore, we investigated the development of PA hepatotoxicity in vivo, using an acutely toxic dose of the PA senecionine in mice, in combination with intravital two-photon microscopy, histology, clinical chemistry, and in vitro experiments with primary mouse hepatocytes and liver sinusoidal endothelial cells (LSECs). We observed pericentral LSEC necrosis together with elevated sinusoidal marker proteins in the serum of senecionine-treated mice and increased sinusoidal platelet aggregation in the damaged tissue regions.

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The lipophilic phycotoxin okadaic acid (OA) occurs in the fatty tissue and hepatopancreas of filter-feeding shellfish. The compound provokes the diarrhetic shellfish poisoning (DSP) syndrome after intake of seafood contaminated with high levels of the DSP toxin. In animal experiments, long-term exposure to OA is associated with an elevated risk for tumor formation in different organs including the liver.

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Pyrrolizidine alkaloids (PA) are widely distributed phytotoxins contaminating food and feed. Hepatic enzymes are considered to bioactivate PA. Previous studies showed differences in the metabolism rate in liver homogenates of different species.

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Lipophilic phycotoxins are secondary metabolites produced by phytoplanktonic species. They accumulate in filtering shellfish and can cause human intoxications. Humans can be exposed to combinations of several phycotoxins.

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Okadaic acid (OA) is a lipophilic phycotoxin that accumulates in the hepatopancreas and fatty tissue of shellfish. Consumption of highly OA-contaminated seafood leads to diarrhetic shellfish poisoning which provokes severe gastrointestinal symptoms associated with a disruption of the intestinal epithelium. Since the molecular mechanisms leading to intestinal barrier disruption are not fully elucidated, we investigated the influence of OA on intestinal tight junction proteins (TJPs) in differentiated Caco-2 cells.

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Scope: Pyrrolizidine alkaloids (PAs) are common phytotoxins. Intoxication can lead to liver damage. Previous studies showed PA-induced apoptosis in liver cells.

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