The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Raffaella Ceccatelli - One of the best experts on this subject based on the ideXlab platform.
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Endocrine Activity and developmental toxicity of cosmetic uv filters an update
Toxicology, 2004Co-Authors: M Schlumpf, Peter Schmid, Stefan Durrer, Marianne Conscience, Kirsten Maerkel, Manuel Henseler, Melanie Gruetter, Ingrid Herzog, Sasha Reolon, Raffaella CeccatelliAbstract:Abstract UV filters represent a new class of Endocrine active chemicals. In vitro, 8/9 chemicals showed estrogenic (MCF-7 cells), and 2/9 antiandrogenic Activity (MDA-kb2 cells). Six/nine filters (benzophenone (Bp)-1, Bp-2, Bp-3, 3-benzylidene camphor (3-BC), 4-methylbenzylidene camphor (4-MBC), octyl-methoxycinnamate (OMC)) increased uterine weight in immature rats. 3-Benzylidene camphor and 4-MBC displaced 16α 125 I-estradiol from human estrogen receptor (ER)β , not ERα. Developmental toxicity of 4-MBC (0.7–47 mg/kg body weight/day) and 3-BC (0.24–7 mg/kg), administered in chow was investigated in Long Evans (LE) rats. Weight gain of pregnant rats was reduced only by 3-BC, early postnatal survival rate and thymus weight by both compounds at higher doses. 4-Methylbenzylidene camphor and 3-BC delayed male puberty, and dose-dependently affected reproductive organ weights of adult male and female F1 offspring, with partly different effect patterns. Thyroid weight was increased by higher 4-MBC doses. Tissue-specific changes in mRNA levels of estrogen-regulated genes in prostate, uterus and brain regions, determined by real-time PCR, and in their response to acute estradiol challenge in adult gonadectomized offspring were observed. Lowest effective doses were 0.24 mg/kg/day for 3-BC and 7 mg/kg/day for 4-MBC. Fat tissue levels at 7 mg/kg 4-MBC (GC–MS) approached the range of UV filters in fish (Nagtegaal et al., 1997; Balmer et al., 2004).
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Endocrine Activity and developmental toxicity of cosmetic uv filters an update
Toxicology, 2004Co-Authors: M Schlumpf, Peter Schmid, Stefan Durrer, Marianne Conscience, Kirsten Maerkel, Manuel Henseler, Melanie Gruetter, Ingrid Herzog, Sasha Reolon, Raffaella CeccatelliAbstract:UV filters represent a new class of Endocrine active chemicals. In vitro, 8/9 chemicals showed estrogenic (MCF-7 cells), and 2/9 antiandrogenic Activity (MDA-kb2 cells). Six/nine filters (benzophenone (Bp)-1, Bp-2, Bp-3, 3-benzylidene camphor (3-BC), 4-methylbenzylidene camphor (4-MBC), octyl-methoxycinnamate (OMC)) increased uterine weight in immature rats. 3-Benzylidene camphor and 4-MBC displaced 16alpha125I-estradiol from human estrogen receptor (ER)beta, not ERalpha. Developmental toxicity of 4-MBC (0.7-47 mg/kg body weight/day) and 3-BC (0.24-7 mg/kg), administered in chow was investigated in Long Evans (LE) rats. Weight gain of pregnant rats was reduced only by 3-BC, early postnatal survival rate and thymus weight by both compounds at higher doses. 4-Methylbenzylidene camphor and 3-BC delayed male puberty, and dose-dependently affected reproductive organ weights of adult male and female F1 offspring, with partly different effect patterns. Thyroid weight was increased by higher 4-MBC doses. Tissue-specific changes in mRNA levels of estrogen-regulated genes in prostate, uterus and brain regions, determined by real-time PCR, and in their response to acute estradiol challenge in adult gonadectomized offspring were observed. Lowest effective doses were 0.24 mg/kg/day for 3-BC and 7 mg/kg/day for 4-MBC. Fat tissue levels at 7 mg/kg 4-MBC (GC-MS) approached the range of UV filters in fish (Nagtegaal et al., 1997; Balmer et al., 2004).
Thomas Braunbeck - One of the best experts on this subject based on the ideXlab platform.
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Does hepatotoxicity interfere with Endocrine Activity in zebrafish (Danio rerio)
Chemosphere, 2019Co-Authors: Lisa Baumann, Helmut Segner, Lennart Weltje, Henrik Holbech, Heike Schmidt-posthaus, Angela P Moissl, Mark Hennies, Janina Tiedemann, Thomas BraunbeckAbstract:Abstract Vitellogenin (VTG), a well-established biomarker for the diagnosis of Endocrine Activity in fish, is used in multiple OECD test guidelines (TG) to identify activities of chemicals on hormonal pathways. However, the synthesis of VTG may not only be modified by typical Endocrine-related pathways, but also through non-Endocrine-mediated processes. In particular, hepatotoxicity, i.e. toxicant-induced impairment of liver structure and function, might influence VTG as a biomarker, since VTG is synthesized in hepatocytes. An intimate understanding of the interplay between Endocrine-related and non-Endocrine-related pathways influencing VTG production is crucial for the avoidance of erroneous diagnoses in hazard assessment for regulatory purposes of chemical compounds. In order to investigate whether hepatotoxicity may interfere with hepatic VTG synthesis, adult zebrafish (Danio rerio) were exposed to three well-known hepatotoxicants, acetaminophen, isoniazid and acetylsalicylic acid, according to OECD TG 230. Various hepatotoxicity- and Endocrine system-related endpoints were recorded: mRNA expression of selected Endocrine- and hepatotoxicity-related marker genes in the liver; VTG levels in head/tail homogenates; and liver histopathology. All three test compounds induced significant, but mild single cell necrosis of hepatocytes and transcriptional changes of hepatotoxicity-related marker genes, thus confirming hepatotoxic effects. A positive correlation between hepatotoxicity and reduced hepatic VTG synthesis was not observed, with the single exception of a weak increase in female zebrafish exposed to APAP. This suggests that – in studies conducted according to OECD TG 229 or 230 − it is unlikely that hepatotoxic chemicals will interfere with the hepatic capacity for VTG synthesis.
Louis J Guillette - One of the best experts on this subject based on the ideXlab platform.
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Endocrine Activity of Extraembryonic Membranes Extends beyond Placental Amniotes
2016Co-Authors: Lori Cruze, Louis J Guillette, Heather J Hamlin, Lori C. Albergotti, Michael W. MccoyAbstract:Background: During development, all amniotes (mammals, reptiles, and birds) form extraembryonic membranes, which regulate gas and water exchange, remove metabolic wastes, provide shock absorption, and transfer maternally derived nutrients. In viviparous (live-bearing) amniotes, both extraembryonic membranes and maternal uterine tissues contribute to the placenta, an Endocrine organ that synthesizes, transports, and metabolizes hormones essential for development. Historically, Endocrine properties of the placenta have been viewed as an innovation of placental amniotes. However, an Endocrine role of extraembryonic membranes has not been investigated in oviparous (egg-laying) amniotes despite similarities in their basic structure, function, and shared evolutionary ancestry. In this study, we ask whether the oviparous chorioallantoic membrane (CAM) of chicken (Gallus gallus) has the capability to synthesize and receive signaling of progesterone, a major placental steroid hormone. Methodology/Principal Findings: We quantified mRNA expression of key steroidogenic enzymes involved in progesterone synthesis and found that 3b-hydroxysteroid dehydrogenase, which converts pregnenolone to progesterone exhibited a 464 fold increase in the CAM from day 8 to day 18 of embryonic development (F5, 68 = 89.282, p,0.0001). To further investigat
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Endocrine Activity of Extraembryonic Membranes Extends beyond Placental Amniotes
2016Co-Authors: Lori C. Albergotti, Heather J Hamlin, Michael W. Mccoy, Louis J GuilletteAbstract:Background: During development, all amniotes (mammals, reptiles, and birds) form extraembryonic membranes, which regulate gas and water exchange, remove metabolic wastes, provide shock absorption, and transfer maternally derived nutrients. In viviparous (live-bearing) amniotes, both extraembryonic membranes and maternal uterine tissues contribute to the placenta, an Endocrine organ that synthesizes, transports, and metabolizes hormones essential for development. Historically, Endocrine properties of the placenta have been viewed as an innovation of placental amniotes. However, an Endocrine role of extraembryonic membranes has not been investigated in oviparous (egg-laying) amniotes despite similarities in their basic structure, function, and shared evolutionary ancestry. In this study, we ask whether the oviparous chorioallantoic membrane (CAM) of chicken (Gallus gallus) has the capability to synthesize and receive signaling of progesterone, a major placental steroid hormone. Methodology/Principal Findings: We quantified mRNA expression of key steroidogenic enzymes involved in progesterone synthesis and found that 3b-hydroxysteroid dehydrogenase, which converts pregnenolone to progesterone exhibited a 464 fold increase in the CAM from day 8 to day 18 of embryonic development (F5, 68 = 89.282, p,0.0001). To further investigate progesterone synthesis, we performed explant culture and found that the CAM synthesizes progesterone in vitro in the presence of a steroid precursor. Finally, we quantified mRNA expression and performed protein immunolocalization of th
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Endocrine Activity of Extraembryonic Membranes Extends beyond Placental Amniotes
PloS one, 2009Co-Authors: Lori C. Albergotti, Heather J Hamlin, Michael W. Mccoy, Louis J GuilletteAbstract:Sigma Xi (G20073141634396861); National Science Foundation (2008059161); UF-Howard Hughes G.A.T.O.R. Program; Howard Hughes Medical Institute Professorship
Lennart Weltje - One of the best experts on this subject based on the ideXlab platform.
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interpretation of sexual secondary characteristics sscs in regulatory testing for Endocrine Activity in fish
Chemosphere, 2020Co-Authors: James R Wheeler, Helmut Segner, Lennart Weltje, Thomas H HutchinsonAbstract:Abstract Secondary sexual characteristics (SSCs) are important features that have evolved in many fish species because of inter-individual competition for mates. SSCs are crucial not only for sexual selection, but also for other components of the reproductive process and parental care. Externally, they are especially clear in males (for instance, tubercles, fatpad, anal finnage, colouration) but are also externally present in the females (for instance, ovipositor). These characters are under hormonal control and as such there has been much interest in incorporating them as measures in fish test methods to assess the potential Endocrine Activity of chemicals. Here we describe the external SSCs in typical laboratory test species for Endocrine testing - fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), zebrafish (Danio rerio) and the three-spined stickleback (Gasterosteus aculeatus L.). We also provide some examples and discuss the utility of SSC responses to the Endocrine Activity of chemicals in the field and the laboratory. This paper is not aimed to provide a comprehensive review of SSCs in fish but presents a view on the assessment of SSCs in regulatory testing. Due to the current regulatory importance of establishing an Endocrine mode-of-action for chemicals, we also consider other, non-Endocrine factors that may lead to SSC responses in fish. We conclude with recommendations for how the assessment of SSCs in fish could be usefully incorporated into the Endocrine hazard and risk assessment of chemicals.
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Does hepatotoxicity interfere with Endocrine Activity in zebrafish (Danio rerio)
Chemosphere, 2019Co-Authors: Lisa Baumann, Helmut Segner, Lennart Weltje, Henrik Holbech, Heike Schmidt-posthaus, Angela P Moissl, Mark Hennies, Janina Tiedemann, Thomas BraunbeckAbstract:Abstract Vitellogenin (VTG), a well-established biomarker for the diagnosis of Endocrine Activity in fish, is used in multiple OECD test guidelines (TG) to identify activities of chemicals on hormonal pathways. However, the synthesis of VTG may not only be modified by typical Endocrine-related pathways, but also through non-Endocrine-mediated processes. In particular, hepatotoxicity, i.e. toxicant-induced impairment of liver structure and function, might influence VTG as a biomarker, since VTG is synthesized in hepatocytes. An intimate understanding of the interplay between Endocrine-related and non-Endocrine-related pathways influencing VTG production is crucial for the avoidance of erroneous diagnoses in hazard assessment for regulatory purposes of chemical compounds. In order to investigate whether hepatotoxicity may interfere with hepatic VTG synthesis, adult zebrafish (Danio rerio) were exposed to three well-known hepatotoxicants, acetaminophen, isoniazid and acetylsalicylic acid, according to OECD TG 230. Various hepatotoxicity- and Endocrine system-related endpoints were recorded: mRNA expression of selected Endocrine- and hepatotoxicity-related marker genes in the liver; VTG levels in head/tail homogenates; and liver histopathology. All three test compounds induced significant, but mild single cell necrosis of hepatocytes and transcriptional changes of hepatotoxicity-related marker genes, thus confirming hepatotoxic effects. A positive correlation between hepatotoxicity and reduced hepatic VTG synthesis was not observed, with the single exception of a weak increase in female zebrafish exposed to APAP. This suggests that – in studies conducted according to OECD TG 229 or 230 − it is unlikely that hepatotoxic chemicals will interfere with the hepatic capacity for VTG synthesis.
Helmut Segner - One of the best experts on this subject based on the ideXlab platform.
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interpretation of sexual secondary characteristics sscs in regulatory testing for Endocrine Activity in fish
Chemosphere, 2020Co-Authors: James R Wheeler, Helmut Segner, Lennart Weltje, Thomas H HutchinsonAbstract:Abstract Secondary sexual characteristics (SSCs) are important features that have evolved in many fish species because of inter-individual competition for mates. SSCs are crucial not only for sexual selection, but also for other components of the reproductive process and parental care. Externally, they are especially clear in males (for instance, tubercles, fatpad, anal finnage, colouration) but are also externally present in the females (for instance, ovipositor). These characters are under hormonal control and as such there has been much interest in incorporating them as measures in fish test methods to assess the potential Endocrine Activity of chemicals. Here we describe the external SSCs in typical laboratory test species for Endocrine testing - fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), zebrafish (Danio rerio) and the three-spined stickleback (Gasterosteus aculeatus L.). We also provide some examples and discuss the utility of SSC responses to the Endocrine Activity of chemicals in the field and the laboratory. This paper is not aimed to provide a comprehensive review of SSCs in fish but presents a view on the assessment of SSCs in regulatory testing. Due to the current regulatory importance of establishing an Endocrine mode-of-action for chemicals, we also consider other, non-Endocrine factors that may lead to SSC responses in fish. We conclude with recommendations for how the assessment of SSCs in fish could be usefully incorporated into the Endocrine hazard and risk assessment of chemicals.
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Does hepatotoxicity interfere with Endocrine Activity in zebrafish (Danio rerio)
Chemosphere, 2019Co-Authors: Lisa Baumann, Helmut Segner, Lennart Weltje, Henrik Holbech, Heike Schmidt-posthaus, Angela P Moissl, Mark Hennies, Janina Tiedemann, Thomas BraunbeckAbstract:Abstract Vitellogenin (VTG), a well-established biomarker for the diagnosis of Endocrine Activity in fish, is used in multiple OECD test guidelines (TG) to identify activities of chemicals on hormonal pathways. However, the synthesis of VTG may not only be modified by typical Endocrine-related pathways, but also through non-Endocrine-mediated processes. In particular, hepatotoxicity, i.e. toxicant-induced impairment of liver structure and function, might influence VTG as a biomarker, since VTG is synthesized in hepatocytes. An intimate understanding of the interplay between Endocrine-related and non-Endocrine-related pathways influencing VTG production is crucial for the avoidance of erroneous diagnoses in hazard assessment for regulatory purposes of chemical compounds. In order to investigate whether hepatotoxicity may interfere with hepatic VTG synthesis, adult zebrafish (Danio rerio) were exposed to three well-known hepatotoxicants, acetaminophen, isoniazid and acetylsalicylic acid, according to OECD TG 230. Various hepatotoxicity- and Endocrine system-related endpoints were recorded: mRNA expression of selected Endocrine- and hepatotoxicity-related marker genes in the liver; VTG levels in head/tail homogenates; and liver histopathology. All three test compounds induced significant, but mild single cell necrosis of hepatocytes and transcriptional changes of hepatotoxicity-related marker genes, thus confirming hepatotoxic effects. A positive correlation between hepatotoxicity and reduced hepatic VTG synthesis was not observed, with the single exception of a weak increase in female zebrafish exposed to APAP. This suggests that – in studies conducted according to OECD TG 229 or 230 − it is unlikely that hepatotoxic chemicals will interfere with the hepatic capacity for VTG synthesis.