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Gonnabathula P, Choi MK, Li M, Kabadi SV, Fairman K. Utility of life stage-specific chemical risk assessments based on New Approach Methodologies (NAMs). Food Chem Toxicol 2024; 190:114789. [PMID: 38844066 DOI: 10.1016/j.fct.2024.114789] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 05/17/2024] [Accepted: 06/03/2024] [Indexed: 06/17/2024]
Abstract
The safety assessments for chemicals targeted for use or expected to be exposed to specific life stages, including infancy, childhood, pregnancy and lactation, and geriatrics, need to account for extrapolation of data from healthy adults to these populations to assess their human health risk. However, often adequate and relevant toxicity or pharmacokinetic (PK) data of chemicals in specific life stages are not available. For such chemicals, New Approach Methodologies (NAMs), such as physiologically based pharmacokinetic (PBPK) modeling, biologically based dose response (BBDR) modeling, in vitro to in vivo extrapolation (IVIVE), etc. can be used to understand the variability of exposure and effects of chemicals in specific life stages and assess their associated risk. A life stage specific PBPK model incorporates the physiological and biochemical changes associated with each life stage and simulates their impact on the absorption, distribution, metabolism, and elimination (ADME) of these chemicals. In our review, we summarize the parameterization of life stage models based on New Approach Methodologies (NAMs) and discuss case studies that highlight the utility of a life stage based PBPK modeling for risk assessment. In addition, we discuss the utility of artificial intelligence (AI)/machine learning (ML) and other computational models, such as those based on in vitro data, as tools for estimation of relevant physiological or physicochemical parameters and selection of model. We also discuss existing gaps in the available toxicological datasets and current challenges that need to be overcome to expand the utility of NAMs for life stage-specific chemical risk assessment.
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Affiliation(s)
- Pavani Gonnabathula
- Division of Biochemical Toxicology, National Center for Toxicological Research (NCTR), US Food and Drug Administration (FDA), Jefferson, AR, 72079, USA
| | - Me-Kyoung Choi
- Division of Biochemical Toxicology, National Center for Toxicological Research (NCTR), US Food and Drug Administration (FDA), Jefferson, AR, 72079, USA
| | - Miao Li
- Division of Biochemical Toxicology, National Center for Toxicological Research (NCTR), US Food and Drug Administration (FDA), Jefferson, AR, 72079, USA
| | - Shruti V Kabadi
- Center for Food Safety and Applied Nutrition (CFSAN), US Food and Drug Administration (FDA), College Park, MD, 20740, USA
| | - Kiara Fairman
- Division of Biochemical Toxicology, National Center for Toxicological Research (NCTR), US Food and Drug Administration (FDA), Jefferson, AR, 72079, USA.
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2
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Bagga AD, Johnson BP, Zhang Q. Spatially Dependent Tissue Distribution of Thyroid Hormones by Plasma Thyroid Hormone Binding Proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.20.572629. [PMID: 38187691 PMCID: PMC10769377 DOI: 10.1101/2023.12.20.572629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Plasma thyroid hormone (TH) binding proteins (THBPs), including thyroxine-binding globulin (TBG), transthyretin (TTR), and albumin (ALB), carry THs to extrathyroidal sites, where THs are unloaded locally and then taken up via membrane transporters into the tissue proper. The respective roles of THBPs in supplying THs for tissue uptake are not completely understood. To investigate this, we developed a spatial human physiologically based kinetic (PBK) model of THs, which produces several novel findings. (1) Contrary to postulations that TTR and/or ALB are the major local T4 contributors, the three THBPs may unload comparable amounts of T4 in Liver, a rapidly perfused organ; however, their contributions in slowly perfused tissues follow the order of abundances of T4TBG, T4TTR, and T4ALB. The T3 amounts unloaded from or loaded onto THBPs in a tissue acting as a T3 sink or source respectively follow the order of abundance of T3TBG, T3ALB, and T3TTR regardless of perfusion rate. (2) Any THBP alone is sufficient to maintain spatially uniform TH tissue distributions. (3) The TH amounts unloaded by each THBP species are spatially dependent and nonlinear in a tissue, with ALB being the dominant contributor near the arterial end but conceding to TBG near the venous end. (4) Spatial gradients of TH transporters and metabolic enzymes may modulate these contributions, producing spatially invariant or heterogeneous TH tissue concentrations depending on whether the blood-tissue TH exchange operates in near-equilibrium mode. In summary, our modeling provides novel insights into the differential roles of THBPs in local TH tissue distribution.
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Affiliation(s)
- Anish D. Bagga
- Emory College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Brian P. Johnson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Qiang Zhang
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, GA 30322, USA
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Gilbert ME, O’Shaughnessy KL, Bell KS, Ford JL. Structural Malformations in the Neonatal Rat Brain Accompany Developmental Exposure to Ammonium Perchlorate. TOXICS 2023; 11:1027. [PMID: 38133428 PMCID: PMC10747616 DOI: 10.3390/toxics11121027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 12/23/2023]
Abstract
Environmental contaminants are often flagged as thyroid system disruptors due to their actions to reduce serum thyroxine (T4) in rodent models. The presence of a periventricular heterotopia (PVH), a brain malformation resulting from T4 insufficiency, has been described in response to T4 decrements induced by pharmaceuticals that reduce the hormone synthesis enzyme thyroperoxidase. In this report, we extend these observations to the environmental contaminant perchlorate, an agent that interferes with thyroid status by inhibiting iodine uptake into the thyroid gland. Pregnant rat dams were administered perchlorate in their drinking water (0, 30, 100, 300, 1000 ppm) from gestational day (GD) 6 until the weaning of pups on postnatal day (PN) 21. Serum T4 was reduced in dams and fetuses in late gestation and remained lower in lactating dams. Pup serum and brain T4, however, were not reduced beyond PN0, and small PVHs were evident in the brains of offspring when assessed on PN14. To emulate the developmental time window of the brain in humans, a second study was conducted in which pups from perchlorate-exposed dams were administered perchlorate orally from PN0 to PN6. This treatment reduced serum and brain T4 in the pup and resulted in large PVH. A third study extended the period of serum and brain TH suppression in pups by coupling maternal perchlorate exposure with maternal dietary iodine deficiency (ID). No PVHs were evident in the pups from ID dams, small PVHs were observed in the offspring of dams exposed to 300 ppm of perchlorate, and very large PVHs were present in the brains of pups born to dams receiving ID and perchlorate. These findings underscore the importance of the inclusion of serum hormone profiles in pregnant dams and fetuses in in vivo screens for thyroid-system-disrupting chemicals and indicate that chemical-induced decreases in fetal rat serum that resolve in the immediate postnatal period may still harbor considerable concern for neurodevelopment in humans.
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Affiliation(s)
- Mary E. Gilbert
- Centre for Public Health and Environmental Assessment, Office of Research and Development, Environmetal Protection Agency, Research Triangle Park, NC 27709, USA;
| | - Katherine L. O’Shaughnessy
- Centre for Public Health and Environmental Assessment, Office of Research and Development, Environmetal Protection Agency, Research Triangle Park, NC 27709, USA;
| | - Kiersten S. Bell
- College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA;
| | - Jermaine L. Ford
- National Center for Computational Toxicology, Office of Research and Development, Environmental Protection Agency, Research Triangle Park, NC 27709, USA;
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Fisher J, Housand C, Mattie D, Nong A, Moreau M, Gilbert M. Towards translating in vitro measures of thyroid hormone system disruption to in vivo responses in the pregnant rat via a biologically based dose response (BBDR) model. Toxicol Appl Pharmacol 2023; 479:116733. [PMID: 37866708 DOI: 10.1016/j.taap.2023.116733] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023]
Abstract
Despite the number of in vitro assays that have been recently developed to identify chemicals that interfere with the hypothalamic-pituitary-thyroid axis (HPT), the translation of those in vitro results into in vivo responses (in vitro to in vivo extrapolation, IVIVE) has received limited attention from the modeling community. To help advance this field a steady state biologically based dose response (BBDR) model for the HPT axis was constructed for the pregnant rat on gestation day (GD) 20. The BBDR HPT axis model predicts plasma levels of thyroid stimulating hormone (TSH) and the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Thyroid hormones are important for normal growth and development of the fetus. Perchlorate, a potent inhibitor of thyroidal uptake of iodide by the sodium iodide symporter (NIS) protein, was used as a case study for the BBDR HPT axis model. The inhibitory blocking of the NIS by perchlorate was associated with dose-dependent steady state decreases in thyroid hormone production in the thyroid gland. The BBDR HPT axis model predictions for TSH, T3, and T4 plasma concentrations in pregnant Sprague Dawley (SD) rats were within 2-fold of observations for drinking water perchlorate exposures ranging from 10 to 30,000 μg/kg/d. In Long Evans (LE) pregnant rats, for both control and perchlorate drinking water exposures, ranging from 85 to 82,000 μg/kg/d, plasma thyroid hormone and TSH concentrations were predicted within 2 to 3.4- fold of observations. This BBDR HPT axis model provides a successful IVIVE template for thyroid hormone disruption in pregnant rats.
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Affiliation(s)
| | - Conrad Housand
- Magnolia Sciences, Winter Springs, FL, United States of America
| | - David Mattie
- AFRL/711 HPW/RHBAF, WPAFB, OH, United States of America
| | - Andy Nong
- ScitoVation LLC, RTP, NC, United States of America
| | | | - Mary Gilbert
- Office of Research and Development, Center for Public Health and Environmental Assessment, US EPA, RTP, NC, United States of America
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Bagga AD, Johnson BP, Zhang Q. A minimal human physiologically based kinetic model of thyroid hormones and chemical disruption of plasma thyroid hormone binding proteins. Front Endocrinol (Lausanne) 2023; 14:1168663. [PMID: 37305053 PMCID: PMC10248451 DOI: 10.3389/fendo.2023.1168663] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 05/11/2023] [Indexed: 06/13/2023] Open
Abstract
The thyroid hormones (THs), thyroxine (T4) and triiodothyronine (T3), are under homeostatic control by the hypothalamic-pituitary-thyroid axis and plasma TH binding proteins (THBPs), including thyroxine-binding globulin (TBG), transthyretin (TTR), and albumin (ALB). THBPs buffer free THs against transient perturbations and distribute THs to tissues. TH binding to THBPs can be perturbed by structurally similar endocrine-disrupting chemicals (EDCs), yet their impact on circulating THs and health risks are unclear. In the present study, we constructed a human physiologically based kinetic (PBK) model of THs and explored the potential effects of THBP-binding EDCs. The model describes the production, distribution, and metabolism of T4 and T3 in the Body Blood, Thyroid, Liver, and Rest-of-Body (RB) compartments, with explicit consideration of the reversible binding between plasma THs and THBPs. Rigorously parameterized based on literature data, the model recapitulates key quantitative TH kinetic characteristics, including free, THBP-bound, and total T4 and T3 concentrations, TH productions, distributions, metabolisms, clearance, and half-lives. Moreover, the model produces several novel findings. (1) The blood-tissue TH exchanges are fast and nearly at equilibrium especially for T4, providing intrinsic robustness against local metabolic perturbations. (2) Tissue influx is limiting for transient tissue uptake of THs when THBPs are present. (3) Continuous exposure to THBP-binding EDCs does not alter the steady-state levels of THs, while intermittent daily exposure to rapidly metabolized TBG-binding EDCs can cause much greater disruptions to plasma and tissue THs. In summary, the PBK model provides novel insights into TH kinetics and the homeostatic roles of THBPs against thyroid disrupting chemicals.
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Affiliation(s)
- Anish D. Bagga
- Emory College of Arts and Sciences, Emory University, Atlanta, GA, United States
| | - Brian P. Johnson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
| | - Qiang Zhang
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, GA, Atlanta, United States
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Grossklaus R, Liesenkötter KP, Doubek K, Völzke H, Gaertner R. Iodine Deficiency, Maternal Hypothyroxinemia and Endocrine Disrupters Affecting Fetal Brain Development: A Scoping Review. Nutrients 2023; 15:nu15102249. [PMID: 37242131 DOI: 10.3390/nu15102249] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
This scoping review critically discusses the publications of the last 30 years on the impact of mild to moderate iodine deficiency and the additional impact of endocrine disrupters during pregnancy on embryonal/fetal brain development. An asymptomatic mild to moderate iodine deficiency and/or isolated maternal hypothyroxinemia might affect the development of the embryonal/fetal brain. There is sufficient evidence underlining the importance of an adequate iodine supply for all women of childbearing age in order to prevent negative mental and social consequences for their children. An additional threat to the thyroid hormone system is the ubiquitous exposure to endocrine disrupters, which might exacerbate the effects of iodine deficiency in pregnant women on the neurocognitive development of their offspring. Ensuring adequate iodine intake is therefore essential not only for healthy fetal and neonatal development in general, but it might also extenuate the effects of endocrine disruptors. Individual iodine supplementation of women of childbearing age living in areas with mild to moderate iodine deficiency is mandatory as long as worldwide universal salt iodization does not guarantee an adequate iodine supply. There is an urgent need for detailed strategies to identify and reduce exposure to endocrine disrupters according to the "precautional principle".
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Affiliation(s)
- Rolf Grossklaus
- Department of Food Safety, Federal Institute for Risk Assessment, D-10589 Berlin, Germany
| | | | - Klaus Doubek
- Professional Association of Gynecologists, D-80337 Munich, Germany
| | - Henry Völzke
- Study of Health in Pomerania/Clinical-Epidemiological Research, Institute for Community Medicine, University Medicine Greifswald, D-17475 Greifswald, Germany
| | - Roland Gaertner
- Medical Clinic IV, University of Munich, D-80336 Munich, Germany
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Błażewicz A, Niziński P, Dolliver I, Dolliver W, Makarewicz A, Skórzyńska-Dziduszko K. Alterations of urinary perchlorate levels in euthyroid postpubertal children with autism spectrum disorder. J Trace Elem Med Biol 2021; 68:126800. [PMID: 34102587 DOI: 10.1016/j.jtemb.2021.126800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/19/2021] [Accepted: 05/26/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Perchlorates ClO4(-) are known environmental and food contaminants that act as inhibitors of iodine uptake by the thyroid gland; however, information concerning their possible association with the development of autism spectrum disorder (ASD) is still missing. The current study is first presenting the alterations in perchlorate urine levels in euthyroid children with ASD. OBJECTIVES To examine urinary perchlorates and iodides in euthyroid children diagnosed with ASD, compared to age-, and BMI-matched neurotypical controls, and to verify the association between these two ions in ASD. METHODS Ions were determined in 24 h urine samples determined by ion chromatography-conductivity cell detection (IC-CD) and ion chromatography-pulsed amperometric detection (IC-PAD) techniques, respectively, in a total of 130 postpubertal euthyroid children with normal BMI (the mean age 14.46 years, SD = 1.32; the mean BMI 20.6, SD = 1.37), divided into age- and BMI-matched groups of ASD patients and neurotypical, healthy children (control). RESULTS The ASD group presented with significantly higher perchlorate urine levels than the controls (median = 1.05 μg/L, interquartile range(IQR) = 1.5 versus median = 0.09 μg/L, IQR = 0.097, respectively), as well as lower iodide urine levels (median = 100.2 μg/L, IQR = 37 versus median = 156.95 μg/L, IQR = 26.11, respectively). The ASD group presented significantly lower TSH and higher free thyroid hormone (fT4, fT3) levels than the controls. In regression analyses, perchlorate urine levels showed significant positive relationships with normal BMI values and serum TSH, and inverse relationships with serum fT4. Urinary iodide levels showed significant inverse relationships with BMI values. The absence of ASD was associated with decreased odds of perchlorate urine levels (OR = 0.012, 95 % confidence interval [CI] 0.0002-0.76), and increased odds of iodide urine levels (OR = 1.15, 95 %CI 1.05-1.27). CONCLUSIONS ASD may have an independent and significant impact on perchlorate as well as iodide levels in urine of euthyroid lean postpubertal children. Perchlorate levels do not appear to be directly associated with iodide levels in euthyroid children.
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Affiliation(s)
- Anna Błażewicz
- Department of Analytical Chemistry, Medical University of Lublin, 20-093, Lublin, Poland.
| | - Przemysław Niziński
- Department of Analytical Chemistry, Medical University of Lublin, 20-093, Lublin, Poland
| | - Iwona Dolliver
- Department of Analytical Chemistry, Medical University of Lublin, 20-093, Lublin, Poland
| | - Wojciech Dolliver
- The Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Boston, MA, 02115, USA
| | - Agata Makarewicz
- Department of Psychiatry, Psychotherapy and Early Intervention, Medical University of Lublin, 20-439, Lublin, Poland
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Handa S, Hassan I, Gilbert M, El-Masri H. Mechanistic Computational Model for Extrapolating In vitro Thyroid Peroxidase (TPO) Inhibition Data to Predict Serum Thyroid Hormone Levels in Rats. Toxicol Sci 2021; 183:36-48. [PMID: 34117770 DOI: 10.1093/toxsci/kfab074] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
High throughput (HTP) in vitro assays are developed to screen chemicals for their potential to inhibit thyroid hormones (THs) synthesis. Some of these experiments, such as the thyroid peroxidase (TPO) inhibition assay, are based on thyroid microsomal extracts. However, the regulation of thyroid disruption chemicals (TDCs) is based on THs in vivo serum levels. This necessitates the estimation of TDCs in vivo tissue levels in the thyroid where THs synthesis inhibition by TPO takes place. The in vivo tissue levels of chemicals are controlled by pharmacokinetic determinants such as absorption, distribution, metabolism and excretion (ADME), and can be described quantitatively in physiologically based pharmacokinetic (PBPK) models. An integrative computational model including chemical specific PBPK and TH kinetics models provides a mechanistic quantitative approach to translate thyroidal HTP in vitro assays to in vivo measures of circulating THs serum levels. This computational framework is developed to quantitatively establish the linkage between applied dose, chemical thyroid tissue levels, thyroid TPO inhibition potential, and in vivo TH serum levels. Once this link is established quantitively, the overall model is used to calibrate the TH kinetics parameters using experimental data for THs levels in thyroid tissue and serum for the two drugs Propylthiouracil (PTU) and Methimazole (MMI). The calibrated quantitative framework is then evaluated against literature data for the environmental chemical ethylenethiourea (ETU). The linkage of PBPK and TH kinetics models illustrates a computational framework that can be extrapolated to humans to screen chemicals based on their exposure levels and potential to disrupt serum THs levels in vivo.
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Affiliation(s)
- Sakshi Handa
- Center for Computational Toxicology and Exposure, Research Triangle Park, NC
| | - Iman Hassan
- Office of Air Quality Planning and Standards, Research Triangle Park, NC
| | - Mary Gilbert
- Center for Public Health and Environmental Assessment, Research Triangle Park, NC
| | - Hisham El-Masri
- Center for Computational Toxicology and Exposure, Research Triangle Park, NC
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9
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Physiologically based pharmacokinetic (PBPK) modeling of RNAi therapeutics: Opportunities and challenges. Biochem Pharmacol 2021; 189:114468. [PMID: 33577889 DOI: 10.1016/j.bcp.2021.114468] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023]
Abstract
Physiologically based pharmacokinetic (PBPK) modeling is a powerful tool with many demonstrated applications in various phases of drug development and regulatory review. RNA interference (RNAi)-based therapeutics are a class of drugs that have unique pharmacokinetic properties and mechanisms of action. With an increasing number of RNAi therapeutics in the pipeline and reaching the market, there is a considerable amount of active research in this area requiring a multidisciplinary approach. The application of PBPK models for RNAi therapeutics is in its infancy and its utility to facilitate the development of this new class of drugs is yet to be fully evaluated. From this perspective, we briefly discuss some of the current computational modeling approaches used in support of efficient development and approval of RNAi therapeutics. Considerations for PBPK model development are highlighted both in a relative context between small molecules and large molecules such as monoclonal antibodies and as it applies to RNAi therapeutics. In addition, the prospects for drawing upon other recognized avenues of PBPK modeling and some of the foreseeable challenges in PBPK model development for these chemical modalities are briefly discussed. Finally, an exploration of the potential application of PBPK model development for RNAi therapeutics is provided. We hope these preliminary thoughts will help initiate a dialogue between scientists in the relevant sectors to examine the value of PBPK modeling for RNAi therapeutics. Such evaluations could help standardize the practice in the future and support appropriate guidance development for strengthening the RNAi therapeutics development program.
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Assessing the impacts on fetal dosimetry of the modelling of the placental transfers of xenobiotics in a pregnancy physiologically based pharmacokinetic model. Toxicol Appl Pharmacol 2020; 409:115318. [PMID: 33160985 DOI: 10.1016/j.taap.2020.115318] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/26/2020] [Accepted: 11/02/2020] [Indexed: 02/07/2023]
Abstract
The developmental origin of health and diseases theory supports the critical role of the fetal exposure to children's health. We developed a physiologically based pharmacokinetic model for human pregnancy (pPBPK) to simulate the maternal and fetal dosimetry throughout pregnancy. Four models of the placental exchanges of chemicals were assessed on ten chemicals for which maternal and fetal data were available. These models were calibrated using non-animal methods: in vitro (InV) or ex vivo (ExV) data, a semi-empirical relationship (SE), or the limitation by the placental perfusion (PL). They did not impact the maternal pharmacokinetics but provided different profiles in the fetus. The PL and InV models performed well even if the PL model overpredicted the fetal exposure for some substances. The SE and ExV models showed the lowest global performance and the SE model a tendency to underprediction. The comparison of the profiles showed that the PL model predicted an increase in the fetal exposure with the pregnancy age, whereas the ExV model predicted a decrease. For the SE and InV models, a small decrease was predicted during the second trimester. All models but the ExV one, presented the highest fetal exposure at the end of the third trimester. Global sensitivity analyses highlighted the predominant influence of the placental transfers on the fetal exposure, as well as the metabolic clearance and the fraction unbound. Finally, the four transfer models could be considered depending on the framework of the use of the pPBPK model and the availability of data or resources to inform their parametrization.
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Fairman K, Li M, Kabadi SV, Lumen A. Physiologically based pharmacokinetic modeling: A promising tool for translational research and regulatory toxicology. CURRENT OPINION IN TOXICOLOGY 2020. [DOI: 10.1016/j.cotox.2020.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Bouazza N, Foissac F, Hirt D, Urien S, Benaboud S, Lui G, Treluyer JM. Methodological Approaches to Evaluate Fetal Drug Exposure. Curr Pharm Des 2020; 25:496-504. [PMID: 30892158 DOI: 10.2174/1381612825666190319102812] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 03/16/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Drug prescriptions are usual during pregnancy, however, women and their fetuses still remain an orphan population with regard to drugs efficacy and safety. Most xenobiotics diffuse through the placenta and some of them can alter fetus development resulting in structural abnormalities, growth or functional deficiencies. METHODS To summarize the different methodologies developed towards the prediction of fetal drug exposure. RESULTS Neonatal cord blood concentration is the most specific measurement of the transplacental drug transfer at the end of pregnancy. Using the cord blood and mother drug concentrations altogether, drug exchanges between the mother and fetus can be modeled and quantified via a population pharmacokinetic analysis. Thereafter, it is possible to estimate the fetus exposure and the fetus-to-mother exposure ratio. However, the prediction of placental transfer before any administration to pregnant women is desirable. Animal studies remain difficult to interpret due to structural and functional inter-species placenta differences. The ex-vivo perfusion of the human placental cotyledon is the method of reference to study the human placental transfer of drugs because it is thought to mimic the functional placental tissue. However, extrapolation of data to in vivo situation remains difficult. Some research groups have extensively worked on physiologically based models (PBPK) to predict fetal drug exposure and showed very encouraging results. CONCLUSION PBPK models appeared to be a very promising tool in order to predict fetal drug exposure in-silico. However, these models mainly picture the end of pregnancy and knowledge regarding both, development of the placental permeability and transporters is strongly needed.
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Affiliation(s)
- Naïm Bouazza
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Unite de Recherche Clinique Paris Descartes Necker Cochin, AP-HP, France.,CIC-1419 Inserm, Cochin-Necker, Paris, France
| | - Frantz Foissac
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Unite de Recherche Clinique Paris Descartes Necker Cochin, AP-HP, France.,CIC-1419 Inserm, Cochin-Necker, Paris, France
| | - Déborah Hirt
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Unite de Recherche Clinique Paris Descartes Necker Cochin, AP-HP, France.,CIC-1419 Inserm, Cochin-Necker, Paris, France.,Service de Pharmacologie Clinique, Hôpital Cochin, AP-HP, Groupe Hospitalier Paris Centre, Paris, France
| | - Saïk Urien
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Unite de Recherche Clinique Paris Descartes Necker Cochin, AP-HP, France.,CIC-1419 Inserm, Cochin-Necker, Paris, France
| | - Sihem Benaboud
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Unite de Recherche Clinique Paris Descartes Necker Cochin, AP-HP, France.,CIC-1419 Inserm, Cochin-Necker, Paris, France.,Service de Pharmacologie Clinique, Hôpital Cochin, AP-HP, Groupe Hospitalier Paris Centre, Paris, France
| | - Gabrielle Lui
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Service de Pharmacologie Clinique, Hôpital Cochin, AP-HP, Groupe Hospitalier Paris Centre, Paris, France
| | - Jean-Marc Treluyer
- Universite Paris Descartes, EA7323, Sorbonne Paris Cite, France.,Unite de Recherche Clinique Paris Descartes Necker Cochin, AP-HP, France.,CIC-1419 Inserm, Cochin-Necker, Paris, France.,Service de Pharmacologie Clinique, Hôpital Cochin, AP-HP, Groupe Hospitalier Paris Centre, Paris, France
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13
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Codaccioni M, Bois F, Brochot C. Placental transfer of xenobiotics in pregnancy physiologically-based pharmacokinetic models: Structure and data. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.comtox.2019.100111] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Hines DE, Conolly RB, Jarabek AM. A Quantitative Source-to-Outcome Case Study To Demonstrate the Integration of Human Health and Ecological End Points Using the Aggregate Exposure Pathway and Adverse Outcome Pathway Frameworks. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:11002-11012. [PMID: 31436975 DOI: 10.1021/acs.est.9b04639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Exposure to environmental contaminants can lead to adverse outcomes in both human and nonhuman receptors. The Aggregate Exposure Pathway (AEP) and Adverse Outcome Pathway (AOP) frameworks can mechanistically inform cumulative risk assessment for human health and ecological end points by linking together environmental transport and transformation, external exposure, toxicokinetics, and toxicodynamics. This work presents a case study of a hypothetical contaminated site to demonstrate a quantitative approach for implementing the AEP framework and linking this framework to AOPs. We construct an AEP transport and transformation model and then quantify external exposure pathways for humans, fishes, and small herbivorous mammals at the hypothetical site. A Monte Carlo approach was used to address parameter variability. Source apportionment was quantified for each species, and published pharmacokinetic models were used to estimate internal target site exposure from external exposures. Published dose-response data for a multispecies AOP network were used to interpret AEP results in the context of species-specific effects. This work demonstrates (1) the construction, analysis, and application of a quantitative AEP model, (2) the utility of AEPs for organizing mechanistic exposure data and highlighting data gaps, and (3) the advantages provided by a source-to-outcome construct for leveraging exposure data and to aid transparency regarding assumptions.
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Affiliation(s)
- David E Hines
- U.S. Environmental Protection Agency , Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division , Research Triangle Park, Durham , North Carolina 27709 , United States
| | - Rory B Conolly
- U.S. Environmental Protection Agency , Office of Research and Development, National Health and Environmental Effects Research Laboratory, Integrated Systems Toxicology Division , Research Triangle Park, Durham , North Carolina 27709 , United States
| | - Annie M Jarabek
- U.S. Environmental Protection Agency , Office of Research and Development, National Center for Environmental Assessment , Research Triangle Park, Durham , North Carolina 27709 , United States
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A model of functional thyroid disease status over the lifetime. PLoS One 2019; 14:e0219769. [PMID: 31318913 PMCID: PMC6638952 DOI: 10.1371/journal.pone.0219769] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 07/01/2019] [Indexed: 11/23/2022] Open
Abstract
Mathematical models of the natural history of disease can predict incidence rates based on prevalence data and support simulations of populations where thyroid function affects other aspects of physiology. We developed a Markov chain model of functional thyroid disease status over the lifetime. Subjects were in one of seven thyroid disease states at any given point in their lives [normal, subclinical hypothyroidism, overt hypothyroidism, treated thyroid disease (ever), subclinical hyperthyroidism, overt hyperthyroidism, and reverted to normal thyroid status]. We used a Bayesian approach to fitting model parameters. A priori probabilities of changing from each disease state to another per unit time were based on published data and summarized using meta-analysis, when possible. The probabilities of changing state were fitted to observed prevalence data based on the National Health and Nutrition Examination Survey 2007–2012. The fitted model provided a satisfactory fit to the observed prevalence data for each disease state, by sex and decade of age. For example, for males 50–59 years old, the observed prevalence of ever having treated thyroid disease was 4.4% and the predicted value was 4.6%. Comparing the incidence rates of treated disease predicted from our model with published values revealed that 82% were within a 4-fold difference. The differences seemed to be systematic and were consistent with expectation based on national iodine intakes. The model provided new and comprehensive estimates of functional thyroid disease incidence rates for the U.S. Because the model provides a reasonable fit to national prevalence data and predicts thyroid disease status over the lifetime, it is suitable for simulating populations, thereby making possible quantitative bias analyses of selected epidemiologic data reporting an association of thyroid disease with serum concentrations of environmental contaminants.
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An evaluation of the USEPA Proposed Approaches for applying a biologically based dose-response model in a risk assessment for perchlorate in drinking water. Regul Toxicol Pharmacol 2019; 103:237-252. [DOI: 10.1016/j.yrtph.2019.01.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 01/18/2019] [Accepted: 01/20/2019] [Indexed: 12/18/2022]
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Willemin ME, Lumen A. Characterization of the modes of action and dose-response relationship for thiocyanate on the thyroid hormone levels in rats using a computational approach. Toxicol Appl Pharmacol 2019; 365:84-100. [DOI: 10.1016/j.taap.2019.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/04/2019] [Accepted: 01/08/2019] [Indexed: 01/16/2023]
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Acevedo-Barrios R, Sabater-Marco C, Olivero-Verbel J. Ecotoxicological assessment of perchlorate using in vitro and in vivo assays. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:13697-13708. [PMID: 29504076 DOI: 10.1007/s11356-018-1565-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 02/13/2018] [Indexed: 06/08/2023]
Abstract
Perchlorate is an inorganic ion widespread in the environment, generated as a natural and anthropogenic pollutant, with known endocrine disruption properties in the thyroid gland. Nonetheless, there are few reports of its ecotoxicological impact on wildlife. The aim of this study was to evaluate the adverse effects of KClO4 exposure on different cell lines, HEK, N2a, and 3T3, as well as in ecological models such as Vibrio fischeri, Pseudokirchneriella subcapitata, Daphnia magna, and Eisenia fetida. Perchlorate exhibited similar toxicity against tested cell lines, with LC50 values of 19, 15, and 19 mM for HEK, N2a, and 3T3, respectively; whereas in V. fischeri, the toxicity, examined as bioluminescence reduction, was considerably lower (EC50 = 715 mM). The survival of the freshwater algae P. subcapitata was significatively impaired by perchlorate (LC50 = 72 mM), and its effect on the lethality in the crustacean D. magna was prominent (LC50 = 5 mM). For the earthworm E. fetida, the LC50 was 56 mM in soil. In this organism, perchlorate induced avoidance behavior, weight loss, and decreased egg production and hatchling, as well as morphological and histopathological effects, such as malformations, dwarfism, and necrosis. In conclusion, perchlorate toxicity varies according to the species, although E. fetida is a sensitive model to generate information regarding the toxicological impact of KClO4 on biota.
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Affiliation(s)
- Rosa Acevedo-Barrios
- Environmental and Computational Chemistry Group, School of Pharmaceutical Sciences, Zaragocilla Campus, University of Cartagena, Cartagena, 130015, Colombia
- Biological and Chemical Studies Group, School of Basic Sciences, Technological University of Bolivar, Cartagena, 130010, Colombia
| | | | - Jesus Olivero-Verbel
- Environmental and Computational Chemistry Group, School of Pharmaceutical Sciences, Zaragocilla Campus, University of Cartagena, Cartagena, 130015, Colombia.
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Determination of Thresholds of Radioactive Iodine Uptake Response With Clinical Exposure to Perchlorate. J Occup Environ Med 2018; 60:e199-e206. [DOI: 10.1097/jom.0000000000001239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Hines DE, Edwards SW, Conolly RB, Jarabek AM. A Case Study Application of the Aggregate Exposure Pathway (AEP) and Adverse Outcome Pathway (AOP) Frameworks to Facilitate the Integration of Human Health and Ecological End Points for Cumulative Risk Assessment (CRA). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:839-849. [PMID: 29236470 PMCID: PMC6003653 DOI: 10.1021/acs.est.7b04940] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Cumulative risk assessment (CRA) methods promote the use of a conceptual site model (CSM) to apportion exposures and integrate risk from multiple stressors. While CSMs may encompass multiple species, evaluating end points across taxa can be challenging due to data availability and physiological differences among organisms. Adverse outcome pathways (AOPs) describe biological mechanisms leading to adverse outcomes (AOs) by assembling causal pathways with measurable intermediate steps termed key events (KEs), thereby providing a framework for integrating data across species. In this work, we used a case study focused on the perchlorate anion (ClO4-) to highlight the value of the AOP framework for cross-species data integration. Computational models and dose-response data were used to evaluate the effects of ClO4- in 12 species and revealed a dose-response concordance across KEs and taxa. The aggregate exposure pathway (AEP) tracks stressors from sources to the exposures and serves as a complement to the AOP. We discuss how the combined AEP-AOP construct helps to maximize the use of existing data and advances CRA by (1) organizing toxicity and exposure data, (2) providing a mechanistic framework of KEs for integrating data across human health and ecological end points, (3) facilitating cross-species dose-response evaluation, and (4) highlighting data gaps and technical limitations.
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Affiliation(s)
- David E. Hines
- U.S. Environmental Protection Agency, Office of Research and Development, National, Health and Environmental Effects Research Laboratory
| | - Stephen W. Edwards
- U.S. Environmental Protection Agency, Office of Research and Development, National, Health and Environmental Effects Research Laboratory
| | - Rory B. Conolly
- U.S. Environmental Protection Agency, Office of Research and Development, National, Health and Environmental Effects Research Laboratory
| | - Annie M. Jarabek
- U.S. Environmental Protection Agency, Office of Research and Development, National, Center for Environmental Assessment
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21
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Dietrich JW, Midgley JEM, Hoermann R. Editorial: "Homeostasis and Allostasis of Thyroid Function". Front Endocrinol (Lausanne) 2018; 9:287. [PMID: 29922229 PMCID: PMC5996081 DOI: 10.3389/fendo.2018.00287] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/15/2018] [Indexed: 12/14/2022] Open
Affiliation(s)
- Johannes W. Dietrich
- Medical Department 1, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, North Rhine-Westphalia, Germany
- Ruhr Centre of Rare Diseases (CeSER), Ruhr University of Bochum, Bochum, North Rhine-Westphalia, Germany
- Ruhr Centre of Rare Diseases (CeSER), Witten/Herdecke University, Bochum, North Rhine-Westphalia, Germany
- *Correspondence: Johannes W. Dietrich,
| | | | - Rudolf Hoermann
- Private Consultancy, Research and Development, Yandina, QLD, Australia
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22
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Bell SM, Chang X, Wambaugh JF, Allen DG, Bartels M, Brouwer KLR, Casey WM, Choksi N, Ferguson SS, Fraczkiewicz G, Jarabek AM, Ke A, Lumen A, Lynn SG, Paini A, Price PS, Ring C, Simon TW, Sipes NS, Sprankle CS, Strickland J, Troutman J, Wetmore BA, Kleinstreuer NC. In vitro to in vivo extrapolation for high throughput prioritization and decision making. Toxicol In Vitro 2017; 47:213-227. [PMID: 29203341 DOI: 10.1016/j.tiv.2017.11.016] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 11/28/2017] [Accepted: 11/30/2017] [Indexed: 01/10/2023]
Abstract
In vitro chemical safety testing methods offer the potential for efficient and economical tools to provide relevant assessments of human health risk. To realize this potential, methods are needed to relate in vitro effects to in vivo responses, i.e., in vitro to in vivo extrapolation (IVIVE). Currently available IVIVE approaches need to be refined before they can be utilized for regulatory decision-making. To explore the capabilities and limitations of IVIVE within this context, the U.S. Environmental Protection Agency Office of Research and Development and the National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods co-organized a workshop and webinar series. Here, we integrate content from the webinars and workshop to discuss activities and resources that would promote inclusion of IVIVE in regulatory decision-making. We discuss properties of models that successfully generate predictions of in vivo doses from effective in vitro concentration, including the experimental systems that provide input parameters for these models, areas of success, and areas for improvement to reduce model uncertainty. Finally, we provide case studies on the uses of IVIVE in safety assessments, which highlight the respective differences, information requirements, and outcomes across various approaches when applied for decision-making.
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Affiliation(s)
- Shannon M Bell
- Integrated Laboratory Systems, Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA.
| | - Xiaoqing Chang
- Integrated Laboratory Systems, Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA.
| | - John F Wambaugh
- U.S. Environmental Protection Agency, 109 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA.
| | - David G Allen
- Integrated Laboratory Systems, Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA.
| | | | - Kim L R Brouwer
- UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Campus Box 7569, Chapel Hill, NC 27599, USA.
| | - Warren M Casey
- National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
| | - Neepa Choksi
- Integrated Laboratory Systems, Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA.
| | - Stephen S Ferguson
- National Toxicology Program, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
| | | | - Annie M Jarabek
- U.S. Environmental Protection Agency, 109 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA.
| | - Alice Ke
- Simcyp Limited (a Certara company), John Street, Sheffield, S2 4SU, United Kingdom.
| | - Annie Lumen
- National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA.
| | - Scott G Lynn
- U.S. Environmental Protection Agency, William Jefferson Clinton Building, 1200 Pennsylvania Ave. NW, Washington, DC 20460, USA.
| | - Alicia Paini
- European Commission, Joint Research Centre, Directorate Health, Consumers and Reference Materials, Chemical Safety and Alternative Methods Unit incorporating EURL ECVAM, Via E. Fermi 2749, Ispra, Varese 20127, Italy.
| | - Paul S Price
- U.S. Environmental Protection Agency, 109 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA.
| | - Caroline Ring
- Oak Ridge Institute for Science and Education, P.O. Box 2008, Oak Ridge, TN 37831, USA.
| | - Ted W Simon
- Ted Simon LLC, 4184 Johnston Road, Winston, GA 30187, USA.
| | - Nisha S Sipes
- National Toxicology Program, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
| | - Catherine S Sprankle
- Integrated Laboratory Systems, Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA.
| | - Judy Strickland
- Integrated Laboratory Systems, Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA.
| | - John Troutman
- Central Product Safety, The Procter & Gamble Company, Cincinnati, OH 45202, USA.
| | - Barbara A Wetmore
- ScitoVation LLC, 6 Davis Drive, Research Triangle Park, NC 27709, USA.
| | - Nicole C Kleinstreuer
- National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
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23
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Hassan I, El-Masri H, Kosian PA, Ford J, Degitz SJ, Gilbert ME. Neurodevelopment and Thyroid Hormone Synthesis Inhibition in the Rat: Quantitative Understanding Within the Adverse Outcome Pathway Framework. Toxicol Sci 2017; 160:57-73. [PMID: 28973696 PMCID: PMC10623382 DOI: 10.1093/toxsci/kfx163] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2023] Open
Abstract
Adequate levels of thyroid hormone (TH) are needed for proper brain development, deficiencies may lead to adverse neurologic outcomes in humans and animal models. Environmental chemicals have been linked to TH disruption, yet the relationship between developmental exposures and decline in serum TH resulting in neurodevelopmental impairment is poorly understood. The present study developed a quantitative adverse outcome pathway where serum thyroxin (T4) reduction following inhibition of thyroperoxidase in the thyroid gland are described and related to deficits in fetal brain TH and the development of a brain malformation, cortical heterotopia. Pregnant rats were exposed to 6-propylthiouracil (PTU 0, 0.1, 0.5, 1, 2, or 3 parts per million [ppm]) from gestational days 6-20, sequentially increasing PTU concentrations in maternal thyroid gland and serum as well as in fetal serum. Dams exposed to 0.5 ppm PTU and higher exhibited dose-dependent decreases in thyroidal T4. Serum T4 levels in the dam were significantly decreased with exposure to 2 and 3 ppm PTU. In the fetus, T4 decrements were first observed at a lower dose of 0.5 ppm PTU. Based on these data, fetal brain T4 levels were estimated from published literature sources, and quantitatively linked to increases in the size of the heterotopia present in the brains of offspring. These data show the potential of in vivo assessments and computational descriptions of biologic responses to predict the development of this structural brain malformation and use of quantitative adverse outcome pathway approach to evaluate brain deficits that may result from exposure to other TH disruptors.
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Affiliation(s)
| | - Hisham El-Masri
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Patricia A Kosian
- Mid-Continent Ecology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Duluth, Minnesota 55804
| | - Jermaine Ford
- Analytical Chemistry Research Core/Research Cores Unit, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Sigmund J Degitz
- Mid-Continent Ecology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Duluth, Minnesota 55804
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Evaluation of the risk of perchlorate exposure in a population of late-gestation pregnant women in the United States: Application of probabilistic biologically-based dose response modeling. Toxicol Appl Pharmacol 2017; 322:9-14. [DOI: 10.1016/j.taap.2017.02.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/11/2017] [Accepted: 02/27/2017] [Indexed: 01/16/2023]
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25
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Lin Z, Jaberi-Douraki M, He C, Jin S, Yang RSH, Fisher JW, Riviere JE. Performance Assessment and Translation of Physiologically Based Pharmacokinetic Models From acslX to Berkeley Madonna, MATLAB, and R Language: Oxytetracycline and Gold Nanoparticles As Case Examples. Toxicol Sci 2017; 158:23-35. [DOI: 10.1093/toxsci/kfx070] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Willemin ME, Lumen A. Thiocyanate: a review and evaluation of the kinetics and the modes of action for thyroid hormone perturbations. Crit Rev Toxicol 2017. [DOI: 10.1080/10408444.2017.1281590] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Marie-Emilie Willemin
- Division of Biochemical Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR, USA
| | - Annie Lumen
- Division of Biochemical Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR, USA
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Lumen A, George NI. Estimation of iodine nutrition and thyroid function status in late-gestation pregnant women in the United States: Development and application of a population-based pregnancy model. Toxicol Appl Pharmacol 2016; 314:24-38. [PMID: 27818216 DOI: 10.1016/j.taap.2016.10.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/27/2016] [Accepted: 10/30/2016] [Indexed: 12/15/2022]
Abstract
Previously, a deterministic biologically-based dose-response (BBDR) pregnancy model was developed to evaluate moderate thyroid axis disturbances with and without thyroid-active chemical exposure in a near-term pregnant woman and fetus. In the current study, the existing BBDR model was adapted to include a wider functional range of iodine nutrition, including more severe iodine deficiency conditions, and to incorporate empirically the effects of homeostatic mechanisms. The extended model was further developed into a population-based model and was constructed using a Monte Carlo-based probabilistic framework. In order to characterize total (T4) and free (fT4) thyroxine levels for a given iodine status at the population-level, the distribution of iodine intake for late-gestation pregnant women in the U.S was reconstructed using various reverse dosimetry methods and available biomonitoring data. The range of median (mean) iodine intake values resulting from three different methods of reverse dosimetry tested was 196.5-219.9μg of iodine/day (228.2-392.9μg of iodine/day). There was minimal variation in model-predicted maternal serum T4 and ft4 thyroxine levels from use of the three reconstructed distributions of iodine intake; the range of geometric mean for T4 and fT4, was 138-151.7nmol/L and 7.9-8.7pmol/L, respectively. The average value of the ratio of the 97.5th percentile to the 2.5th percentile equaled 3.1 and agreed well with similar estimates from recent observations in third-trimester pregnant women in the U.S. In addition, the reconstructed distributions of iodine intake allowed us to estimate nutrient inadequacy for late-gestation pregnant women in the U.S. via the probability approach. The prevalence of iodine inadequacy for third-trimester pregnant women in the U.S. was estimated to be between 21% and 44%. Taken together, the current work provides an improved tool for evaluating iodine nutritional status and the corresponding thyroid function status in pregnant women in the U.S. This model enables future assessments of the relevant risk of thyroid hormone level perturbations due to exposure to thyroid-active chemicals at the population-level.
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Affiliation(s)
- A Lumen
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA.
| | - N I George
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA.
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28
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Willemin ME, Lumen A. Development of a PBPK model of thiocyanate in rats with an extrapolation to humans: A computational study to quantify the mechanism of action of thiocyanate kinetics in thyroid. Toxicol Appl Pharmacol 2016; 307:19-34. [DOI: 10.1016/j.taap.2016.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/07/2016] [Accepted: 07/15/2016] [Indexed: 12/13/2022]
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Alayoubi A, Sullivan RD, Lou H, Patel H, Mandrell T, Helms R, Almoazen H. In Vivo Evaluation of Transdermal Iodide Microemulsion for Treating Iodine Deficiency Using Sprague Dawley Rats. AAPS PharmSciTech 2016; 17:618-30. [PMID: 26288943 DOI: 10.1208/s12249-015-0392-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/09/2015] [Indexed: 11/30/2022] Open
Abstract
The objective of this study was to evaluate the transdermal efficiency of iodide microemulsion in treating iodine deficiency using rats as an animal model. Animals were fed either iodine-deficient diet (20 μg/kg iodide) or control diet (200 μg/kg iodide) over a 17-month period. At month 14, iodide microemulsion was applied topically in iodine-deficient group and physiological evaluations of thyroid gland functions were characterized by monitoring the thyroid hormones (T3, T4), thyroid-stimulating hormone (TSH), iodide ion excretion in urine, and the overall rat body weights in both groups. Moreover, morphological evaluations of thyroid gland before and after treatment were performed by ultrasound imaging and through histological assessment. Prior to microemulsion treatment, the levels of T3, T4, and TSH in iodine-deficient group were statistically significant as compared to that in the control group. The levels of T3 and T4 increased while TSH level decreased significantly in iodine-deficient group within the first 4 weeks of treatment. After treatment, iodide concentration in urine increased significantly. There was no statistical difference in weight between the two groups. Ultrasound imaging and histological evaluations showed evidence of hyperplasia in iodine-deficient group. Topical iodide microemulsion has shown a promising potential as a novel delivery system to treat iodine deficiency.
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Schlosser PM. Revision of the affinity constant for perchlorate binding to the sodium-iodide symporter based on in vitro and human in vivo data. J Appl Toxicol 2016; 36:1531-1535. [PMID: 27177048 DOI: 10.1002/jat.3337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 11/07/2022]
Abstract
A series of previously published physiologically based pharmacokinetic (PBPK) models describe the effect of perchlorate on iodide uptake by the thyroid, with the mechanism being competitive inhibition of iodide transport by the sodium-iodide symporter (NIS). Hence a key parameter of these models is the affinity of perchlorate for the NIS, characterized as the Michaelis-Menten kinetic constant, Km . However, when model predictions were compared to published results of a human study measuring radio-iodide uptake (RAIU) inhibition after controlled perchlorate exposures, it was found to only fit the lowest exposure level and underpredicted RAIU inhibition at higher levels. Published in vitro data, in which perchlorate-induced inhibition of iodide uptake via the NIS was measured, were re-analyzed. Km for binding of perchlorate to the NIS originally derived from these data, 1.5 μm, had been obtained using Lineweaver-Burk plots, which allow for linear regression but invert the signal-noise of the data. Re-fitting these data by non-linear regression of the non-inverted data yielded a 60% lower value for the Km , 0.59 μm. Substituting this value into the PBPK model for an average adult human significantly improved model agreement with the human RAIU data for exposures <100 μg kg-1 day-1 . Thus, this lower Km value both fits the in vitro NIS kinetics and provides better predictions of human in vivo RAIU data. This change in Km increases the predicted sensitivity of humans to perchlorate over twofold for low-level exposures. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Paul M Schlosser
- US EPA, National Center for Environmental Assessment, Washington, DC, USA.
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31
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Fisher W, Wang J, George NI, Gearhart JM, McLanahan ED. Dietary Iodine Sufficiency and Moderate Insufficiency in the Lactating Mother and Nursing Infant: A Computational Perspective. PLoS One 2016; 11:e0149300. [PMID: 26930410 PMCID: PMC4773173 DOI: 10.1371/journal.pone.0149300] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/29/2016] [Indexed: 12/27/2022] Open
Abstract
The Institute of Medicine recommends that lactating women ingest 290 μg iodide/d and a nursing infant, less than two years of age, 110 μg/d. The World Health Organization, United Nations Children’s Fund, and International Council for the Control of Iodine Deficiency Disorders recommend population maternal and infant urinary iodide concentrations ≥ 100 μg/L to ensure iodide sufficiency. For breast milk, researchers have proposed an iodide concentration range of 150–180 μg/L indicates iodide sufficiency for the mother and infant, however no national or international guidelines exist for breast milk iodine concentration. For the first time, a lactating woman and nursing infant biologically based model, from delivery to 90 days postpartum, was constructed to predict maternal and infant urinary iodide concentration, breast milk iodide concentration, the amount of iodide transferred in breast milk to the nursing infant each day and maternal and infant serum thyroid hormone kinetics. The maternal and infant models each consisted of three sub-models, iodide, thyroxine (T4), and triiodothyronine (T3). Using our model to simulate a maternal intake of 290 μg iodide/d, the average daily amount of iodide ingested by the nursing infant, after 4 days of life, gradually increased from 50 to 101 μg/day over 90 days postpartum. The predicted average lactating mother and infant urinary iodide concentrations were both in excess of 100 μg/L and the predicted average breast milk iodide concentration, 157 μg/L. The predicted serum thyroid hormones (T4, free T4 (fT4), and T3) in both the nursing infant and lactating mother were indicative of euthyroidism. The model was calibrated using serum thyroid hormone concentrations for lactating women from the United States and was successful in predicting serum T4 and fT4 levels (within a factor of two) for lactating women in other countries. T3 levels were adequately predicted. Infant serum thyroid hormone levels were adequately predicted for most data. For moderate iodide deficient conditions, where dietary iodide intake may range from 50 to 150 μg/d for the lactating mother, the model satisfactorily described the iodide measurements, although with some variation, in urine and breast milk. Predictions of serum thyroid hormones in moderately iodide deficient lactating women (50 μg/d) and nursing infants did not closely agree with mean reported serum thyroid hormone levels, however, predictions were usually within a factor of two. Excellent agreement between prediction and observation was obtained for a recent moderate iodide deficiency study in lactating women. Measurements included iodide levels in urine of infant and mother, iodide in breast milk, and serum thyroid hormone levels in infant and mother. A maternal iodide intake of 50 μg/d resulted in a predicted 29–32% reduction in serum T4 and fT4 in nursing infants, however the reduced serum levels of T4 and fT4 were within most of the published reference intervals for infant. This biologically based model is an important first step at integrating the rapid changes that occur in the thyroid system of the nursing newborn in order to predict adverse outcomes from exposure to thyroid acting chemicals, drugs, radioactive materials or iodine deficiency.
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Affiliation(s)
- W. Fisher
- US FDA, National Center for Toxicological Research, 3900 NCTR Rd, Jefferson, Arkansas, 72079, United States of America
- * E-mail:
| | - Jian Wang
- US FDA, Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, Silver Springs, Maryland, 20993, United States of America
| | - Nysia I. George
- US FDA, National Center for Toxicological Research, 3900 NCTR Rd, Jefferson, Arkansas, 72079, United States of America
| | - Jeffery M. Gearhart
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, 2729 R Street, Bldg 837, Wright-Patterson AFB, Ohio, 43433, United States of America
- Wright State University Boonshoft School of Medicine, Dayton, Ohio, 45435, United States of America
| | - Eva D. McLanahan
- CDC/ATSDR, Division of Community Health Investigations, 4770 Buford HWY NE, Atlanta, Georgia, 30341, United States of America
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Zhang T, Ma Y, Wang D, Li R, Chen X, Mo W, Qin X, Sun H, Kannan K. Placental transfer of and infantile exposure to perchlorate. CHEMOSPHERE 2016; 144:948-954. [PMID: 26432537 DOI: 10.1016/j.chemosphere.2015.09.073] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/17/2015] [Accepted: 09/18/2015] [Indexed: 06/05/2023]
Abstract
Fetuses and infants are vulnerable to perchlorate toxicity. We assessed fetal and infantile exposure to perchlorate in two Chinese cities (Nanchang and Tianjin). Perchlorate was widely found (82%-100%) in breast milk, dissolved infant formula, infants' urine, maternal and cord blood samples. Perchlorate levels in infants' urine (mean ± standard deviation: 22.4 ± 35.6 ng mL(-1)), breast milk (36.6 ± 48.1 ng mL(-1)), and cord blood (3.18 ± 3.83 ng mL(-1)) samples collected from Nanchang and Tianjin were approximately an order of magnitude higher than those reported for the U.S. Perchlorate concentrations in cord blood were comparable to that in maternal blood, indicating that perchlorate is transferred from mother to fetus through placenta. Among all infants providing urine samples, the average daily intake of perchlorate (DOSEU) was estimated to be 1.17 ± 1.57 μg kg(-1) bw d(-1), and 40% of these infants had DOSEU exceeding the RfD (0.7 μg kg(-1) bw d(-1)) recommended by U.S. EPA. However, approximately 70% of exclusively breast-fed infants had perchlorate exposure dose via breast milk exceeding the RfD. For breast-fed infants, breast milk was the overwhelmingly predominant exposure pathway; while infant formula and indoor dust ingestion were major perchlorate exposure sources for formula-fed infants. To our knowledge, this is the first report to assess the fetal and infantile exposure to perchlorate in China.
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Affiliation(s)
- Tao Zhang
- School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-Sen University), Guangzhou 510275, China; College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China.
| | - Yufang Ma
- College of Environmental Sciences and Engineering, Peking University, Beijing, China
| | - Dou Wang
- College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China
| | - Rudan Li
- College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China
| | - Xiaojia Chen
- College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China
| | - Weiwen Mo
- College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China
| | - Xiaolei Qin
- College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China; Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China
| | - Hongwen Sun
- College of Environmental Sciences and Engineering, Nankai University, Tianjin 300071, China; Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071, China.
| | - Kurunthachalam Kannan
- Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Albany, NY 12201, USA
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Lewandowski TA, Peterson MK, Charnley G. Iodine supplementation and drinking-water perchlorate mitigation. Food Chem Toxicol 2015; 80:261-270. [DOI: 10.1016/j.fct.2015.03.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 02/03/2015] [Accepted: 03/13/2015] [Indexed: 10/23/2022]
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Lumen A, McNally K, George N, Fisher JW, Loizou GD. Quantitative global sensitivity analysis of a biologically based dose-response pregnancy model for the thyroid endocrine system. Front Pharmacol 2015; 6:107. [PMID: 26074819 PMCID: PMC4444753 DOI: 10.3389/fphar.2015.00107] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/04/2015] [Indexed: 12/15/2022] Open
Abstract
A deterministic biologically based dose-response model for the thyroidal system in a near-term pregnant woman and the fetus was recently developed to evaluate quantitatively thyroid hormone perturbations. The current work focuses on conducting a quantitative global sensitivity analysis on this complex model to identify and characterize the sources and contributions of uncertainties in the predicted model output. The workflow and methodologies suitable for computationally expensive models, such as the Morris screening method and Gaussian Emulation processes, were used for the implementation of the global sensitivity analysis. Sensitivity indices, such as main, total and interaction effects, were computed for a screened set of the total thyroidal system descriptive model input parameters. Furthermore, a narrower sub-set of the most influential parameters affecting the model output of maternal thyroid hormone levels were identified in addition to the characterization of their overall and pair-wise parameter interaction quotients. The characteristic trends of influence in model output for each of these individual model input parameters over their plausible ranges were elucidated using Gaussian Emulation processes. Through global sensitivity analysis we have gained a better understanding of the model behavior and performance beyond the domains of observation by the simultaneous variation in model inputs over their range of plausible uncertainties. The sensitivity analysis helped identify parameters that determine the driving mechanisms of the maternal and fetal iodide kinetics, thyroid function and their interactions, and contributed to an improved understanding of the system modeled. We have thus demonstrated the use and application of global sensitivity analysis for a biologically based dose-response model for sensitive life-stages such as pregnancy that provides richer information on the model and the thyroidal system modeled compared to local sensitivity analysis.
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Affiliation(s)
- Annie Lumen
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration Jefferson, AR, USA
| | | | - Nysia George
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, U.S. Food and Drug Administration Jefferson, AR, USA
| | - Jeffrey W Fisher
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration Jefferson, AR, USA
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Min H, Dong J, Wang Y, Wang Y, Teng W, Xi Q, Chen J. Maternal Hypothyroxinemia-Induced Neurodevelopmental Impairments in the Progeny. Mol Neurobiol 2015; 53:1613-1624. [PMID: 25666160 DOI: 10.1007/s12035-015-9101-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/15/2015] [Indexed: 12/16/2022]
Abstract
Maternal hypothyroxinemia can induce neurodevelopmental impairments in the developing fetus. We here review recent studies on the epidemiology and molecular mechanisms associated with this important public health issue. In 2011, the American Thyroid Association defined maternal hypothyroxinemia as low serum free thyroxine (FT4) levels (<5th or <10th percentile) existing in conjunction with normal serum free triiodothyronine (FT3) or thyroid stimulating hormone (TSH) levels during pregnancy. Compared to clinical or subclinical hypothyroidism, hypothyroxinemia is more commonly found in pregnant women. Hypothyroxinemia usually ensues in response to several factors, such as mild iodine deficiency, environmental endocrine disrupters, or certain thyroid diseases. Unequivocal evidence demonstrates that maternal hypothyroxinemia leads to negative effects on fetal brain development, increasing the risks for cognitive deficits and poor psychomotor development in resulting progeny. In support of this, rodent models provide direct evidence of neurodevelopmental damage induced by maternal hypothyroxinemia, including dendritic and axonal growth limitation, neural abnormal location, and synaptic function alteration. The neurodevelopmental impairments induced by hypothyroxinemia suggest an independent role of T4. Increasing evidence indicates that adequate thyroxine is required for the mothers in order to protect against the abnormal brain development in their progeny.
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Affiliation(s)
- Hui Min
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110013, People's Republic of China
- Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, People's Republic of China
| | - Jing Dong
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110013, People's Republic of China
- Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, People's Republic of China
| | - Yi Wang
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110013, People's Republic of China
- Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, People's Republic of China
| | - Yuan Wang
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110013, People's Republic of China
- Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, People's Republic of China
| | - Weiping Teng
- Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, People's Republic of China
| | - Qi Xi
- Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
| | - Jie Chen
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110013, People's Republic of China.
- Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, People's Republic of China.
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Suh M, Abraham L, Hixon JG, Proctor DM. The effects of perchlorate, nitrate, and thiocyanate on free thyroxine for potentially sensitive subpopulations of the 2001-2002 and 2007-2008 National Health and Nutrition Examination Surveys. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2014; 24:579-587. [PMID: 24149973 DOI: 10.1038/jes.2013.67] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/10/2013] [Indexed: 06/02/2023]
Abstract
Among women with urinary iodine concentration <100 μg/l in the 2001-2002 National Health and Nutrition Examination Survey (NHANES), urinary perchlorate was associated with significant changes in thyroid stimulating hormone and total thyroxine (T4). Although perchlorate, nitrate, and thiocyanate all potentially act to inhibit iodide uptake, free T4 was not found to be associated with exposure to these chemicals in the same data. Fetuses of pregnant mothers with iodine deficiency are thought to be a sensitive subpopulation for perchlorate exposure, but the potential associations between free T4 and exposure to these chemicals among pregnant mothers in NHANES 2001-2002 and 2007-2008 have not been specifically evaluated to date. This study investigates the potential associations between urinary perchlorate, nitrate, and thiocyanate and serum free T4 in individuals with low urinary iodine levels and pregnant women. Multivariate regression models of free T4 were conducted and included urinary perchlorate, nitrate, thiocyanate, and covariates known to have an impact on the thyroid (anti-thyroid peroxidase (TPO) antibodies, age, race/ethnicity, body mass index, and hours of fasting). Meta-analyses were also conducted on non-pregnant and on pregnant women from the two survey cycles. Urinary nitrate was associated with serum free T4 in non-pregnant women of NHANES 2001-2002 who had urinary iodine ≥100 μg/l. In the meta-analysis, urinary perchlorate, nitrate, and thiocyanate were significant predictors of serum free T4 in non-pregnant women. No association was found in men and pregnant women. TPO antibodies were significant predictors of free T4 among non-pregnant women only when the models included urinary perchlorate, nitrate, or thiocyanate. Risk assessment for perchlorate exposure should consider co-exposure to nitrate and thiocyanate.
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Affiliation(s)
- Mina Suh
- ToxStrategies, Inc., Mission Viejo, California, USA
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Scientific Opinion on the risks to public health related to the presence of perchlorate in food, in particular fruits and vegetables. EFSA J 2014. [DOI: 10.2903/j.efsa.2014.3869] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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Lutter R. An upper-bound assessment of the benefits of reducing perchlorate in drinking water. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2014; 34:1944-1956. [PMID: 25196433 DOI: 10.1111/risa.12261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The Environmental Protection Agency plans to issue new federal regulations to limit drinking water concentrations of perchlorate, which occurs naturally and results from the combustion of rocket fuel. This article presents an upper-bound estimate of the potential benefits of alternative maximum contaminant levels for perchlorate in drinking water. The results suggest that the economic benefits of reducing perchlorate concentrations in drinking water are likely to be low, i.e., under $2.9 million per year nationally, for several reasons. First, the prevalence of detectable perchlorate in public drinking water systems is low. Second, the population especially sensitive to effects of perchlorate, pregnant women who are moderately iodide deficient, represents a minority of all pregnant women. Third, and perhaps most importantly, reducing exposure to perchlorate in drinking water is a relatively ineffective way of increasing iodide uptake, a crucial step linking perchlorate to health effects of concern.
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The hypothalamic-pituitary-thyroid axis in infants and children: protection from radioiodines. J Thyroid Res 2014; 2014:710178. [PMID: 24971190 PMCID: PMC4058186 DOI: 10.1155/2014/710178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 05/07/2014] [Indexed: 11/17/2022] Open
Abstract
Potassium iodide (KI) is recommended as an emergency treatment for exposure to radioiodines, most commonly associated with nuclear detonation or mishaps at nuclear power plants. Protecting the thyroid gland of infants and children remains a priority because of increased incidence of thyroid cancer in the young exposed to radioiodines (such as (131)I and (133)I). There is a lack of clinical studies for KI and radioiodines in children or infants to draw definitive conclusions about the effectiveness and safety of KI administration in the young. In this paper, we compare functional aspects of the hypothalamic-pituitary-thyroid (HPT) axis in the young and adults and review the limited studies of KI in children. The HPT axis in the infant and child is hyperactive and therefore will respond less effectively to KI treatment compared to adults. Research on the safety and efficacy of KI in infants and children is needed.
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