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Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, (Ron) Hoogenboom L, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Wallace H, Benford D, Fürst P, Hart A, Rose M, Schroeder H, Vrijheid M, Ioannidou S, Nikolič M, Bordajandi LR, Vleminckx C. Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food. EFSA J 2024; 22:e8497. [PMID: 38269035 PMCID: PMC10807361 DOI: 10.2903/j.efsa.2024.8497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024] Open
Abstract
The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.
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Schrenk D, Bignami M, Bodin L, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Vleminckx C, Wallace H, Alexander J, Goldbeck C, Grob K, Gómez Ruiz JÁ, Mosbach‐Schulz O, Binaglia M, Chipman JK. Update of the risk assessment of mineral oil hydrocarbons in food. EFSA J 2023; 21:e08215. [PMID: 37711880 PMCID: PMC10498375 DOI: 10.2903/j.efsa.2023.8215] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023] Open
Abstract
Mineral oil hydrocarbons (MOH) are composed of saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH). Due to the complexity of the MOH composition, their complete chemical characterisation is not possible. MOSH accumulation is observed in various tissues, with species-specific differences. Formation of liver epithelioid lipogranulomas and inflammation, as well as increased liver and spleen weights, are observed in Fischer 344 (F344) rats, but not in Sprague-Dawley (SD) rats. These effects are related to specific accumulation of wax components in the liver of F344 rats, which is not observed in SD rats or humans. The CONTAM Panel concluded that F344 rats are not an appropriate model for effects of MOSH with wax components. A NOAEL of 236 mg/kg body weight (bw) per day, corresponding to the highest tested dose in F344 rats of a white mineral oil product virtually free of wax components, was selected as relevant reference point (RP). The highest dietary exposure to MOSH was estimated for the young population, with lower bound-upper bound (LB-UB) means and 95th percentiles of 0.085-0.126 and 0.157-0.212 mg/kg bw per day, respectively. Considering a margin of exposure approach, the Panel concluded that the present dietary exposure to MOSH does not raise concern for human health for all age classes. Genotoxicity and carcinogenicity are associated with MOAH with three or more aromatic rings. For this subfraction, a surrogate RP of 0.49 mg/kg bw per day, calculated from data on eight polycyclic aromatic hydrocarbons, was considered. The highest dietary exposure to MOAH was also in the young population, with LB-UB mean and 95th percentile estimations of 0.003-0.031 and 0.011-0.059 mg/kg bw per day, respectively. Based on two scenarios on three or more ring MOAH contents in the diet and lacking toxicological information on effects of 1 and 2 ring MOAH, a possible concern for human health was raised.
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Nuber M, Lindner A, Baumgart J, Baumgart N, Heimann A, Schröder A, Muensterer OJ, Oetzmann von Sochaczewski C. Sex represents a relevant interaction in Sprague–Dawley rats: the example of oesophageal length*. ALL LIFE 2020. [DOI: 10.1080/26895293.2020.1806118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Maximilian Nuber
- Translational Animal Research Centre, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Andreas Lindner
- Department of Paediatric Surgery, Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Jan Baumgart
- Translational Animal Research Centre, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Nadine Baumgart
- Translational Animal Research Centre, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Axel Heimann
- Institute of Neurosurgical Pathophysiology, Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
| | - Arne Schröder
- Department of Paediatrics, Elisabeth-Krankenhaus Essen, Essen, Germany
| | - Oliver J. Muensterer
- Department of Paediatric Surgery, Universitätsmedizin Mainz der Johannes Gutenberg-Universität, Mainz, Germany
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Xian TH, Parasuraman S, Sinniah K, Ravichandran M, Prabhakaran G. Repeated dose toxicity evaluation of a cold chain-free, live, attenuated oral cholera vaccine in Sprague Dawley rats. Vaccine 2019; 37:711-720. [PMID: 30630696 DOI: 10.1016/j.vaccine.2018.12.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 12/17/2022]
Abstract
The repeated dose toxicity of a prototype cold chain-free, live, attenuated oral cholera vaccine containing 5 × 106 CFU/mL of the VCUSM14P strain was evaluated in Sprague Dawley (SD) rats (single dose administered daily for 30 days) to ascertain its safety for clinical use. Repeated dose toxicity studies for cholera vaccines in the literature have administered 2 or 3 fixed doses at 7, 14, 21 or 69 day intervals. The present study reports an evaluation of 30 repeated doses of cholera vaccine administered at three different concentrations (Group II (1.25 × 106 CFU), Group III (2.5 × 106 CFU) and Group IV (5 × 106 CFU)) in SD rats. The liquid vaccine was administered orally to the rats with the respective dose every day, and normal saline was administered to the control group (Group I). No significant difference (P > 0.05) was observed in the body weights and biochemical parameters of the rats after 15 and 30 repeated doses compared to those of the control group. However, compared to those of Group I, a significant increase (P < 0.05) in the organ to body weight ratios of the lungs, ureter, liver, kidney, heart and spleen was found in G-II, G-III and G-IV. In the haematological analysis, a significant increase in the WBC was observed in G-II and G-IV compared to that in G-I. The histopathological findings indicated mild to moderate degeneration in the liver, kidney, heart and spleen in the treated rats. Mild to moderate lymphocytic infiltration in the lungs was observed in the G-II and G-III rats, and severe infiltration was observed in the G-IV rats. These histopathological findings may be attributed to the 30 doses of vaccine given in daily succession without an interval. In the acute toxicity study, a single dose of vaccine up to 10 × 106 CFU did not cause any adverse effects and lethality in SD rats.
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Affiliation(s)
- Tew Hui Xian
- Department of Biotechnology, Faculty of Applied Sciences, AIMST University, Semeling 08100, Kedah, Malaysia
| | - Subramani Parasuraman
- Unit of Pharmacology, Faculty of Pharmacy, AIMST University, Semeling 08100, Kedah, Malaysia
| | - Kurunathan Sinniah
- Department of Biotechnology, Faculty of Applied Sciences, AIMST University, Semeling 08100, Kedah, Malaysia
| | - Manickam Ravichandran
- Department of Biotechnology, Faculty of Applied Sciences, AIMST University, Semeling 08100, Kedah, Malaysia
| | - Guruswamy Prabhakaran
- Department of Biotechnology, Faculty of Applied Sciences, AIMST University, Semeling 08100, Kedah, Malaysia.
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Insulation fiber deposition in the airways of men and rats. A review of experimental and computational studies. Regul Toxicol Pharmacol 2018; 94:252-270. [PMID: 29444452 DOI: 10.1016/j.yrtph.2018.01.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/07/2018] [Accepted: 01/24/2018] [Indexed: 12/22/2022]
Abstract
The typical insulation rock, slag and glass wool fibers are high volume materials. Current exposure levels in industry (generally ≤ 1 fiber/cm3 with a median diameter ∼1 μm and length ≥10 μm) are not considered carcinogenic or causing other types of severe lung effects. However, epidemiological studies are not informative on effects in humans at fiber levels >1 fiber/cm3. Effects may be inferred from valid rat studies, conducted with rat respirable fibers (diameter ≤ 1.5 μm). Therefore, we estimate delivery and deposition in human and rat airways of the industrial fibers. The deposition fractions in humans head regions by nasal (∼0.20) and by mouth breathing (≤0.08) are lower than in rats (0.50). The delivered dose into the lungs per unit lung surface area during a 1-day exposure at a similar air concentration is estimated to be about two times higher in humans than in rats. The deposition fractions in human lungs by nasal (∼0.20) and by mouth breathing (∼0.40) are higher than in rats (∼0.04). The human lung deposition may be up to three times by nasal breathing and up to six times higher by oral breathing than in rats, qualifying assessment factor setting for deposition.
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Chen Q, Yang L, Han M, Cai E, Zhao Y. Synthesis and pharmacological activity evaluation of arctigenin monoester derivatives. Biomed Pharmacother 2016; 84:1792-1801. [DOI: 10.1016/j.biopha.2016.10.093] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/26/2016] [Accepted: 10/30/2016] [Indexed: 10/20/2022] Open
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Rosa JDL, Cavariani MM, Borges CDS, Leite GAA, Anselmo-Franci JA, Kempinas WDG. Lack of Reproductive Toxicity in Adult Male Rats Exposed to Interferon-Alpha. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:1288-1298. [PMID: 26488366 DOI: 10.1080/10937404.2015.1083518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Interferon-alpha (IFN- α), a type I IFN, is a protein with antiviral, antiproliferative, and immunoregulatory activities, widely used in the treatment of several types of cancers as well as hepatitis B and C. Decrease of libido and erectile dysfunction are commonly reported by male patients during treatment of chronic hepatitis C with IFN- α . However, IFN therapy-associated underlying factors attributed to sexual dysfunction are still not well defined. Currently, there are few studies investigating the effects of IFN on male reproductive system functions. Given that, the aim of the present investigation was to examine effects of subchronic exposure to IFN- α (5 × 10(4) U/kg and 10 × 10(4) U/kg, 30 d) on serum hormones, sperm parameters, fertility, and testicular and epididymal hystopathology and morphometry in adult male Wistar rats. None of the evaluated parameters was markedly altered by IFN- α . Thus, our results suggest that exposure to IFN- α , in this experimental design, did not adversely affect sperm quality and fertile capacity of male rats.
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Affiliation(s)
- Josiane de Lima Rosa
- a Laboratory of Biology and Toxicology of Reproduction and Development, Department of Morphology , Institute of Biosciences, UNESP-Universidade Estadual Paulista , Botucatu , São Paulo , Brazil
| | - Marilia Martins Cavariani
- a Laboratory of Biology and Toxicology of Reproduction and Development, Department of Morphology , Institute of Biosciences, UNESP-Universidade Estadual Paulista , Botucatu , São Paulo , Brazil
| | - Cibele dos Santos Borges
- a Laboratory of Biology and Toxicology of Reproduction and Development, Department of Morphology , Institute of Biosciences, UNESP-Universidade Estadual Paulista , Botucatu , São Paulo , Brazil
| | - Gabriel Adan Araújo Leite
- a Laboratory of Biology and Toxicology of Reproduction and Development, Department of Morphology , Institute of Biosciences, UNESP-Universidade Estadual Paulista , Botucatu , São Paulo , Brazil
| | - Janete Aparecida Anselmo-Franci
- b Department of Morphology, Stomatology and Physiology, School of Dentistry , USP-Universidade de São Paulo , Ribeirão Preto , São Paulo , Brazil
| | - Wilma De Grava Kempinas
- a Laboratory of Biology and Toxicology of Reproduction and Development, Department of Morphology , Institute of Biosciences, UNESP-Universidade Estadual Paulista , Botucatu , São Paulo , Brazil
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Hebar A, Koller C, Seifert JM, Chabicovsky M, Bodenteich A, Bernkop-Schnürch A, Grassauer A, Prieschl-Grassauer E. Non-clinical safety evaluation of intranasal iota-carrageenan. PLoS One 2015; 10:e0122911. [PMID: 25875737 PMCID: PMC4395440 DOI: 10.1371/journal.pone.0122911] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/16/2015] [Indexed: 12/19/2022] Open
Abstract
Carrageenan has been widely used as food additive for decades and therefore, an extended oral data set is available in the public domain. Less data are available for other routes of administration, especially intranasal administration. The current publication describes the non-clinical safety and toxicity of native (non-degraded) iota-carrageenan when applied intranasally or via inhalation. Intranasally applied iota-carrageenan is a topically applied, locally acting compound with no need of systemic bioavailability for the drug’s action. Animal experiments included repeated dose local tolerance and toxicity studies with intranasally applied 0.12% iota-carrageenan for 7 or 28 days in New Zealand White rabbits and nebulized 0.12% iota-carrageenan administered to F344 rats for 7 days. Permeation studies revealed no penetration of iota-carrageenan across nasal mucosa, demonstrating that iota-carrageenan does not reach the blood stream. Consistent with this, no relevant toxic or secondary pharmacological effects due to systemic exposure were observed in the rabbit or rat repeated dose toxicity studies. Data do not provide any evidence for local intolerance or toxicity, when carrageenan is applied intranasally or by inhalation. No signs for immunogenicity or immunotoxicity have been observed in the in vivo studies. This is substantiated by in vitro assays showing no stimulation of a panel of pro-inflammatory cytokines by iota-carrageenan. In conclusion, 0.12% iota-carrageenan is safe for clinical use via intranasal application.
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Zhao C, Li Z, Li C, Yang L, Yao L, Fu Y, He X, Shi K, Lu Z. Optimized extraction of polysaccharides from Taxus chinensis var. mairei fruits and its antitumor activity. Int J Biol Macromol 2015; 75:192-8. [DOI: 10.1016/j.ijbiomac.2015.01.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 01/18/2015] [Accepted: 01/25/2015] [Indexed: 11/29/2022]
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10
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Franconi F, Rosano G, Campesi I. Need for gender-specific pre-analytical testing: the dark side of the moon in laboratory testing. Int J Cardiol 2014; 179:514-35. [PMID: 25465806 DOI: 10.1016/j.ijcard.2014.11.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/27/2014] [Accepted: 11/03/2014] [Indexed: 01/16/2023]
Abstract
Many international organisations encourage studies in a sex-gender perspective. However, research with a gender perspective presents a high degree of complexity, and the inclusion of sex-gender variable in experiments presents many methodological questions, the majority of which are still neglected. Overcoming these issues is fundamental to avoid erroneous results. Here, pre-analytical aspects of the research, such as study design, choice of utilised specimens, sample collection and processing, animal models of diseases, and the observer's role, are discussed. Artefacts in this stage of research could affect the predictive value of all analyses. Furthermore, the standardisation of research subjects according to their lifestyles and, if female, to their life phase and menses or oestrous cycle, is urgent to harmonise research worldwide. A sex-gender-specific attention to pre-analytical aspects could produce a decrease in the time for translation from the bench to bedside. Furthermore, sex-gender-specific pre-clinical pharmacological testing will enable adequate assessment of pharmacokinetic and pharmacodynamic actions of drugs and will enable, where appropriate, an adequate gender-specific clinical development plan. Therefore, sex-gender-specific pre-clinical research will increase the gender equity of care and will produce more evidence-based medicine.
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Affiliation(s)
- Flavia Franconi
- Department of Biomedical Sciences, University of Sassari, National Laboratory of Gender Medicine of the National Institute of Biostructures and Biosystems, Osilo, Sassari, Italy; Vicepresident of Basilicata Region.
| | - Giuseppe Rosano
- Cardiovascular and Cell Sciences Research Institute, St George's University of London, United Kingdom
| | - Ilaria Campesi
- Department of Biomedical Sciences, University of Sassari, National Laboratory of Gender Medicine of the National Institute of Biostructures and Biosystems, Osilo, Sassari, Italy
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Toyoda T, Cho YM, Mizuta Y, Akagi JI, Nishikawa A, Ogawa K. A 13-week subchronic toxicity study of sodium iron chlorophyllin in F344 rats. J Toxicol Sci 2014; 39:109-19. [PMID: 24418715 DOI: 10.2131/jts.39.109] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Sodium iron chlorophyllin (SIC), a water-soluble chlorophyll derivative, has been used as a food additive for green coloration. In the present study, a subchronic toxicity study of SIC was performed in male and female F344 rats with oral administration in diet at concentrations of 0%, 0.2%, 1.0%, and 5.0% for 13 weeks. No mortalities, abnormal clinical signs, and hematological changes were observed in any of the groups during the experiment. Significant reduction of body weight gain was noted in 5.0% males. In serum biochemistry, serum transferrin levels were significantly increased in 5.0% males and females. Relative spleen weights of both sexes were markedly reduced with 5.0% SIC as compared to the controls, and absolute weights of spleen were also significantly decreased in males. On histopathological assessment, diffuse hypertrophy of acinar cells in the parotid gland was observed in all examined 5.0% males and females, but not in the other groups. Based on the histopathology of the parotid glands, the no-observed-adverse-effect level (NOAEL) of SIC in the present study was estimated to be 1.0% (609 mg/kg bw/day for males and 678 mg/kg bw/day for females).
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Affiliation(s)
- Takeshi Toyoda
- Division of Pathology, National Institute of Health Sciences
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12
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Craig EA, Yan Z, Zhao QJ. The relationship between chemical-induced kidney weight increases and kidney histopathology in rats. J Appl Toxicol 2014; 35:729-36. [PMID: 25092041 DOI: 10.1002/jat.3036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/20/2014] [Accepted: 05/21/2014] [Indexed: 11/09/2022]
Abstract
The kidney is a major site of chemical excretion, which results in its propensity to exhibit chemically-induced toxicological effects at a higher rate than most other organs. Although the kidneys are often weighed in animal toxicity studies, the manner in which these kidney weight measurements are interpreted and the value of this information in predicting renal damage remains controversial. In this study we sought to determine whether a relationship exists between chemically-induced kidney weight changes and renal histopathological alterations. We also examined the relative utility of absolute and relative (kidney-to-body weight ratio) kidney weight in the prediction of renal toxicity. For this, data extracted from oral chemical exposure studies in rats performed by the National Toxicology Program were qualitatively and quantitatively evaluated. Our analysis showed a statistically significant correlation between absolute, but not relative, kidney weight and renal histopathology in chemically-treated rats. This positive correlation between absolute kidney weight and histopathology was observed even with compounds that statistically decreased terminal body weight. Also, changes in absolute kidney weight, which occurred at subchronic exposures, were able to predict the presence or absence of kidney histopathology at both subchronic and chronic exposures. Furthermore, most increases in absolute kidney weight reaching statistical significance (irrespective of the magnitude of change) were found to be relevant for the prediction of histopathological changes. Hence, our findings demonstrate that the evaluation of absolute kidney weight is a useful method for identifying potential renal toxicants.
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Affiliation(s)
- Evisabel A Craig
- Oak Ridge Institute for Science and Education, Oak Ridge, 37831, TN, USA.,National Center for Environmental Assessment, Office of Research Development, U.S. Environmental Protection Agency, Cincinnati, 45268, OH, USA
| | - Zhongyu Yan
- Oak Ridge Institute for Science and Education, Oak Ridge, 37831, TN, USA.,National Center for Environmental Assessment, Office of Research Development, U.S. Environmental Protection Agency, Cincinnati, 45268, OH, USA
| | - Q Jay Zhao
- National Center for Environmental Assessment, Office of Research Development, U.S. Environmental Protection Agency, Cincinnati, 45268, OH, USA
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Parthasarathy A, Datta J, Torres JAL, Hopkins C, Bartlett EL. Age-related changes in the relationship between auditory brainstem responses and envelope-following responses. J Assoc Res Otolaryngol 2014; 15:649-61. [PMID: 24845405 PMCID: PMC4141432 DOI: 10.1007/s10162-014-0460-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 04/24/2014] [Indexed: 12/22/2022] Open
Abstract
Hearing thresholds and wave amplitudes measured using auditory brainstem responses (ABRs) to brief sounds are the predominantly used clinical measures to objectively assess auditory function. However, frequency-following responses (FFRs) to tonal carriers and to the modulation envelope (envelope-following responses or EFRs) to longer and spectro-temporally modulated stimuli are rapidly gaining prominence as a measure of complex sound processing in the brainstem and midbrain. In spite of numerous studies reporting changes in hearing thresholds, ABR wave amplitudes, and the FFRs and EFRs under neurodegenerative conditions, including aging, the relationships between these metrics are not clearly understood. In this study, the relationships between ABR thresholds, ABR wave amplitudes, and EFRs are explored in a rodent model of aging. ABRs to broadband click stimuli and EFRs to sinusoidally amplitude-modulated noise carriers were measured in young (3-6 months) and aged (22-25 months) Fischer-344 rats. ABR thresholds and amplitudes of the different waves as well as phase-locking amplitudes of EFRs were calculated. Age-related differences were observed in all these measures, primarily as increases in ABR thresholds and decreases in ABR wave amplitudes and EFR phase-locking capacity. There were no observed correlations between the ABR thresholds and the ABR wave amplitudes. Significant correlations between the EFR amplitudes and ABR wave amplitudes were observed across a range of modulation frequencies in the young. However, no such significant correlations were found in the aged. The aged click ABR amplitudes were found to be lower than would be predicted using a linear regression model of the young, suggesting altered gain mechanisms in the relationship between ABRs and FFRs with age. These results suggest that ABR thresholds, ABR wave amplitudes, and EFRs measure complementary aspects of overlapping neurophysiological processes and the relationships between these measurements changes asymmetrically with age. Hence, measuring all three metrics provides a more complete assessment of auditory function, especially under pathological conditions like aging.
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Affiliation(s)
- Aravindakshan Parthasarathy
- />Department of Biological Sciences and the Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, 47907 West Lafayette, IN USA
| | - Jyotishka Datta
- />Department of Statistics, Purdue University, West Lafayette, IN USA
| | | | - Charneka Hopkins
- />Department of Public Health, Western Illinois University, Macomb, IL USA
| | - Edward L. Bartlett
- />Department of Biological Sciences and the Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, 47907 West Lafayette, IN USA
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Shao K, Gift JS, Setzer RW. Is the assumption of normality or log-normality for continuous response data critical for benchmark dose estimation? Toxicol Appl Pharmacol 2013; 272:767-79. [PMID: 23954464 DOI: 10.1016/j.taap.2013.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 08/06/2013] [Indexed: 11/26/2022]
Abstract
Continuous responses (e.g. body weight) are widely used in risk assessment for determining the benchmark dose (BMD) which is used to derive a U.S. EPA reference dose. One critical question that is not often addressed in dose-response assessments is whether to model the continuous data as normally or log-normally distributed. Additionally, if lognormality is assumed, and only summarized response data (i.e., mean±standard deviation) are available as is usual in the peer-reviewed literature, the BMD can only be approximated. In this study, using the "hybrid" method and relative deviation approach, we first evaluate six representative continuous dose-response datasets reporting individual animal responses to investigate the impact on BMD/BMDL estimates of (1) the distribution assumption and (2) the use of summarized versus individual animal data when a log-normal distribution is assumed. We also conduct simulation studies evaluating model fits to various known distributions to investigate whether the distribution assumption has influence on BMD/BMDL estimates. Our results indicate that BMDs estimated using the hybrid method are more sensitive to the distribution assumption than counterpart BMDs estimated using the relative deviation approach. The choice of distribution assumption has limited impact on the BMD/BMDL estimates when the within dose-group variance is small, while the lognormality assumption is a better choice for relative deviation method when data are more skewed because of its appropriateness in describing the relationship between mean and standard deviation. Additionally, the results suggest that the use of summarized data versus individual response data to characterize log-normal distributions has minimal impact on BMD estimates.
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Affiliation(s)
- Kan Shao
- ORISE Postdoctoral Fellow, National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.
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15
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Wolansky MJ, Tornero-Velez R. Critical consideration of the multiplicity of experimental and organismic determinants of pyrethroid neurotoxicity: a proof of concept. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2013; 16:453-490. [PMID: 24298913 DOI: 10.1080/10937404.2013.853607] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Pyrethroids (PYR) are pesticides with high insecticidal activity that may disrupt neuronal excitability in target and nontarget species. The accumulated evidence consistently showed that this neurophysiologic action is followed by alterations in motor, sensorimotor, neuromuscular, and thermoregulatory responses. Nevertheless, there are some equivocal results regarding the potency of PYR in lab animals. The estimation of potency is an important step in pesticide chemical risk assessment. In order to identify the variables influencing neurobehavioral findings across PYR studies, evidence on experimental and organismic determinants of acute PYR-induced neurotoxicity was reviewed in rodents. A comprehensive analysis of these studies was conducted focusing on test material and dosing conditions, testing conditions, animal models, and other determinants such as testing room temperature. Variations in the severity of the neurotoxicity, under lab-controlled conditions, was explained based upon factors including influence of animal species and age, test material features such as chemical structure and stereochemistry, and dosing conditions such as vehicle, route of exposure, and dose volume. If not controlled, the interplay of these factors may lead to large variance in potency estimation. This review examined the scope of acute toxicological data required to determine the safety of pesticide products, and factors and covariates that need to be controlled in order to ensure that predictivity and precaution are balanced in a risk assessment process within a reasonable time-frame, using acute PYR-induced neurotoxicity in rodents as an exemplar.
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Affiliation(s)
- M J Wolansky
- a Laboratorio de Toxicología de Mezclas Químicas, Instituto de Investigación IQUIBICEN, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento Química Biológica, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Ciudad Universitaria UBA, Ciudad Autónoma de Buenos Aires , Argentina
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