RESUMO
The intranasal (IN) route of administration is important for topical drugs and drugs intended to act systemically. More recently, direct nose-to-brain input was considered to bypass the blood-brain barrier.Processes related to IN absorption and nose-to-brain distribution are complex and depend, sometimes in contrasting ways, on chemico-physical and structural parameters of the compounds, and on formulation options.Due to the intricacies of these processes and despite the large number of articles published on many different IN compounds, it appears that absorption after IN dosing is not yet fully understood. In particular, at variance of the understanding and modelling approaches that are available for predicting the pharmacokinetics (PK) following oral administration of xenobiotics, it appears that there is not a similar understanding of the chemico-physical and structural determinants influencing drug absorption and disposition of compounds after IN administration, which represents a missed opportunity for this research field. This is even more true regarding the understanding of the direct nose-to-brain input. Due to this, IN administrations may represent an interesting and open research field for scientists aiming to develop PK property predictions tools, mechanistic PK models describing rate and extent of IN absorption, and translational tools to anticipate the clinical PK following IN dosing based on in vitro and in vivo non clinical experiments.This review intends to provide: i) some basic knowledge related to the physiology of PK after IN dosing, ii) a non-exhaustive list of preclinical and clinical examples related to compounds explored for the potential nose-to-blood and nose-to-brain passage, and iii) the identification of some areas requiring improvements, the understanding of which may facilitate the development of IN drug candidates.
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Administração Intranasal , Humanos , Barreira Hematoencefálica/metabolismo , Animais , Encéfalo/metabolismo , Xenobióticos/farmacocinética , Xenobióticos/administração & dosagem , Farmacocinética , Mucosa Nasal/metabolismoRESUMO
INTRODUCTION: The lungs possess many xenobiotic metabolizing enzymes which influence the pharmacokinetics and safety of inhaled medicines. Anticipating metabolism in the lungs provides an opportunity to optimize new inhaled medicines and overcome challenges in their development. AREAS COVERED: This article summarizes current knowledge on xenobiotic metabolizing enzymes in the lungs. The impact of metabolism on inhaled medicines is considered with examples of how this impacts small molecules, biologics and macromolecular formulation excipients. Methods for measuring and predicting xenobiotic lung metabolism are critically reviewed and the potential for metabolism to influence inhalation toxicology is acknowledged. EXPERT OPINION: Drugs can be optimized by molecular modification to (i) reduce systemic exposure using a 'soft drug' approach, (ii) improve bioavailability by resisting metabolism, or (iii) use a prodrug approach to overcome pharmacokinetic limitations. Drugs that are very labile in the lungs may require a protective formulation. Some drug carriers being investigated for PK-modification rely on lung enzymes to trigger drug release or biodegrade. Lung enzyme activity varies with age, race, smoking status, diet, drug exposure and preexisting lung disease. New experimental technologies to study lung metabolism include tissue engineered models, improved analytical capability and in silico models.
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Sistemas de Liberação de Medicamentos , Pulmão/metabolismo , Xenobióticos/metabolismo , Administração por Inalação , Animais , Disponibilidade Biológica , Simulação por Computador , Portadores de Fármacos/química , Humanos , Pulmão/enzimologia , Pneumopatias/fisiopatologia , Pró-Fármacos , Engenharia Tecidual , Xenobióticos/administração & dosagem , Xenobióticos/efeitos adversosRESUMO
In animal health risk assessment, hazard characterisation of feed additives has been often using the default uncertainty factor (UF) of 100 to translate a no-observed-adverse-effect level in test species (rat, mouse, dog, rabbit) to a 'safe' level of chronic exposure in farm and companion animal species. Historically, both 10-fold factors have been further divided to include chemical-specific data in both dimensions when available. For cats (Felis Sylvestris catus), an extra default UF of 5 is applied due to the species' deficiency in particularly glucuronidation and glycine conjugation. This paper aims to assess the scientific basis and validity of the UF for inter-species differences in kinetics (4.0) and the extra UF applied for cats through a comparison of kinetic parameters between rats and cats for 30 substrates of phase I and phase II metabolism. When the parent compound undergoes glucuronidation the default factor of 4.0 is exceeded, with exceptions for zidovudine and S-carprofen. Compounds that were mainly renally excreted did not exceed the 4.0-fold default. Mixed results were obtained for chemicals which are metabolised by CYP3A in rats. When chemicals were administered intravenously the 4.0-fold default was not exceeded with the exception of clomipramine, lidocaine and alfentanil. The differences seen after oral administration might be due to differences in first-pass metabolism and bioavailability. Further work is needed to further characterise phase I, phase II enzymes and transporters in cats to support the development of databases and in silico models to support hazard characterisation of chemicals particularly for feed additives.
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Ração Animal/toxicidade , Sistema Enzimático do Citocromo P-450/metabolismo , Contaminação de Alimentos , Glucuronosiltransferase/metabolismo , Xenobióticos/farmacocinética , Animais , Gatos , Desintoxicação Metabólica Fase I , Desintoxicação Metabólica Fase II , Nível de Efeito Adverso não Observado , Ratos , Medição de Risco , Especificidade da Espécie , Especificidade por Substrato , Incerteza , Xenobióticos/administração & dosagem , Xenobióticos/toxicidadeRESUMO
PURPOSE: To advance physiologically-based pharmacokinetic modelling of xenobiotic metabolism by integrating metabolic kinetics with percutaneous absorption. METHOD: Kinetic rate equations were proposed to describe the metabolism of a network of reaction pathways following topical exposure and incorporated into the diffusion-partition equations of both xenobiotics and metabolites. The published ex vivo case study of aromatic amines was simulated. Diffusion and partition properties of xenobiotics and subsequent metabolites were determined using physiologically-based quantitative structure property relationships. Kinetic parameters of metabolic reactions were best fitted from published experimental data. RESULTS: For aromatic amines, the integrated transdermal permeation and metabolism model produced data closely matched by experimental results following limited parameter fitting of metabolism rate constants and vehicle:water partition coefficients. The simulation was able to produce dynamic concentration data for all the dermal layers, as well as the vehicle and receptor fluid. CONCLUSION: This mechanistic model advances the dermal in silico functionality. It provides improved quantitative spatial and temporal insight into exposure of xenobiotics, enabling the isolation of governing features of skin. It contributes to accurate modelling of concentrations of xenobiotics reaching systemic circulation and additional metabolite concentrations. This is vital for development of both pharmaceuticals and cosmetics.
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Aminas/farmacocinética , Simulação por Computador , Modelos Biológicos , Absorção Cutânea , Pele/metabolismo , Xenobióticos/farmacocinética , Administração Cutânea , Aminas/administração & dosagem , Disponibilidade Biológica , Difusão , Humanos , Xenobióticos/administração & dosagemRESUMO
Biocontainment is an essential feature when deploying genetically modified organisms (GMOs) in open system applications, as variants escaping their intended operating environments could negatively impact ecosystems and human health. To avoid breaches resulting from metabolic cross-feeding, horizontal gene transfer, and/or genetic mutations, synthetic auxotrophs have been engineered to become dependent on exogenously supplied xenobiotics, such as noncanonical amino acids (ncAAs). The incorporation of these abiological building blocks into essential proteins constitutes a first step toward constructing xenobiological barriers between GMOs and their environments. To transition synthetic auxotrophs further away from familiar biology, we demonstrate how bacterial growth can be confined by transition-metal complexes that catalyze the formation of an essential ncAA through new-to-nature reactions. Specifically, using a homogeneous ruthenium complex enabled us to localize bacterial growth on solid media, while heterogeneous palladium nanoparticles could be recycled and deployed up to five consecutive times to ensure the survival of synthetic auxotrophs in liquid cultures.
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Escherichia coli/metabolismo , Meios de Cultura , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Nanopartículas Metálicas/química , Organismos Geneticamente Modificados , Paládio/química , Estudo de Prova de Conceito , Biologia Sintética/métodos , Xenobióticos/administração & dosagemRESUMO
Elements of key enteric drug metabolism and disposition pathways are reviewed to aid the assessment of the applicability of current cell-based enteric experimental systems for the evaluation of enteric metabolism and drug interaction potential. Enteric nuclear receptors include vitamin D receptor, constitutive androstane receptor, pregnane X receptor, farnesoid X receptor, liver X receptor, aryl hydrocarbon receptor, and peroxisome proliferator-activated receptor. Enteric drug metabolizing enzyme pathways include both cytochrome P450 (P450) and non-P450 drug metabolizing enzymes based on gene expression, proteomics, and activity. Both uptake and efflux transporters are present in the small intestine, with P-glycoprotein found to be responsible for most drug-drug and food-drug interactions. The cell-based in vitro enteric systems reviewed are 1) immortalized cell line model: the human colon adenocarcinoma (Caco-2) cells; 2) human stem cell-derived enterocyte models: stem cell enteric systems, either from intestinal crypt cells or induced pluripotent stem cells; and 3) primary cell models: human intestinal slices, cryopreserved human enterocytes, permeabilized cofactor-supplemented (MetMax) cryopreserved human enterocytes, and cryopreserved human intestinal mucosa. The major deficiency with both immortalized cell lines and stem cell-derived enterocytes is that drug metabolizing enzyme activities, although they are detectable, are substantially lower than those for the intestinal mucosa in vivo. Human intestine slices, cryopreserved human enterocytes, MetMax cryopreserved human enterocytes, and cryopreserved human intestinal mucosa retain robust enteric drug metabolizing enzyme activity and represent appropriate models for the evaluation of metabolism and metabolism-dependent drug interaction potential of orally administered xenobiotics including drugs, botanical products, and dietary supplements. SIGNIFICANCE STATEMENT: Enteric drug metabolism plays an important role in the bioavailability and metabolic fate of orally administered drugs as well as in enteric drug-drug and food-drug interactions. The current status of key enteric drug metabolism and disposition pathways and in vitro human cell-based enteric experimental systems for the evaluation of the metabolism and drug interaction potential of orally administered substances is reviewed.
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Produtos Biológicos/farmacocinética , Sistema Enzimático do Citocromo P-450/metabolismo , Mucosa Intestinal/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Xenobióticos/farmacocinética , Administração Oral , Disponibilidade Biológica , Produtos Biológicos/administração & dosagem , Células CACO-2 , Criopreservação , Avaliação Pré-Clínica de Medicamentos/métodos , Interações Medicamentosas , Enterócitos , Humanos , Taxa de Depuração Metabólica , Especificidade da Espécie , Células-Tronco , Xenobióticos/administração & dosagemRESUMO
The application of physiologically based modeling approaches in evaluating health risks in diverse environments is limited by scarcity of comprehensive reviews detailing how physiological parameters are altered due to stressors. A modern high-performance aviation environment in particular has the potential for simultaneous exposure to chemical and non-chemical stressors which may interact via non-chemical stressor-mediated pharmacokinetic alterations. To support physiologically based pharmacokinetic (PBPK) modeling of in-flight disposition inhaled chemicals, literature review, and synthesis was conducted to determine the impact of gravitational (+Gz) forces on PBPK modeling inputs. Specifically, changes in cardiac output and related parameters heart rate and stroke volume, breathing frequency, tidal volume, and pulmonary and alveolar ventilation rate in vivo were extracted from 36 publications and related mathematically to +Gz intensity. A scenario was simulated where a pilot performing test flights might inhale organic chemicals at the occupational exposure guideline level while experiencing sustained, elevated +Gz. Peak arterial blood concentrations of 1,2,4-trimethylbenzene during a 1 h-flight at +4 Gz were predicted to increase 2-fold relative to would occur on the ground under baseline conditions. This case study demonstrates the potential value of scenario-specific physiological information in assessing changes in risk-relevant internal dosimetry, providing better information for potential risk management actions.
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Aeronaves , Exposição Ambiental , Gravitação , Estresse Fisiológico , Xenobióticos/administração & dosagem , Humanos , Exposição OcupacionalRESUMO
Phytoseiids are predatory mites that prey on other mites and small arthropods, and several species are used in commercial agriculture for biological control of pests. To optimize phytoseiid mites' use in biocontrol, an efficient method for oral delivery of test compounds is required to assess their sensitivities to pesticides, RNAi for gene functional analysis and artificial diets. Here we developed four methods for oral delivery of a solution of xenobiotics to different life stages of the commercially available generalist predatory mite Neoseiulus californicus: (i) soaking mites in the solution, or allowing them to feed on (ii) spider mites soaked in the solution, (iii) a solution droplet, or (iv) solution-saturated filter paper. As measured by ingestion of a tracer dye, the droplet-based feeding system was most efficient; the dye was observed in the alimentary canal of >90% test mites of all life stages, with no mortality. The droplet-based feeding system was also effective for the commercially available specialist predatory mite Phytoseiulus persimilis, with >80% delivery efficiency. This study paves the way for development of methods for high-throughput RNAi and for toxicological or nutritional assays in phytoseiid mites.
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Acaridae/crescimento & desenvolvimento , Controle Biológico de Vetores/métodos , Xenobióticos/administração & dosagem , Acaridae/efeitos dos fármacos , Acaridae/fisiologia , Animais , Feminino , Ensaios de Triagem em Larga Escala , Praguicidas , Comportamento Predatório , Interferência de RNA , SolubilidadeRESUMO
The scientific interest in the influence of xenobiotics on the human body is due to the fact that immune organs are characterized by a pronounced response to the influence of endogenous and exogenous factors. Recently, the immunological impairment, as a manifestation of reactions to ecopathogenic conditions, suggests a major pathogenesis role in the development of cardiovascular, neuropsychiatric diseases, as well as diffuse diseases of connective tissue. Objectives - experiment was designed to elucidate the organometric changes in thymus of male rats due to impact of propylene glycol. 40 WAG matured male rats were divided randomly into two groups. The first group served as a control and constituted 8 animals. The second group of 32 rats, 8 rodents in each, were treated via gavage by aqueous solutions of propylene glycol in doze 1/10 LD50 in conversion to 26,38 g/kg during 7, 15, 30, 45 days. All animals were sacrificed on the term defined by experimental design. Thymus specimens were dissected out, and linear dimensions (length, width, height) using digital caliper were measured, along with mass and volume of the thymus. Limits of the thymus morphometric indices' variability in intact and experimental groups were calculated. The research indicates that exposure to propylene glycol caused marked organometric changes in rats' thymus. However, more pronounced changes were observed on 7th and 30th days. Were established the following limits of variability indices oscillations: IndHL of the experimental group thymus ranged from min=12.57 to max=47.54, the mean value was from 24.67 to 28.02; IndHW of the experimental group thymus ranged from min=11.96 to max=88.73, the mean value was from 36.78 to 41.41; IndT of the experimental group ranged from min = 38.17 to max=141.3, the mean value was from 71.1 to 86.52. The study of the morphometric parameters of the thymus in the experimental group of rats has established a significant reduction of all parameters and their deviation from the parameters of the control group, that shows active reaction of thymus on induced xenobiotic.
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Propilenoglicóis/farmacologia , Timo/efeitos dos fármacos , Animais , Masculino , Propilenoglicóis/administração & dosagem , Distribuição Aleatória , Ratos , Xenobióticos/administração & dosagem , Xenobióticos/farmacologiaRESUMO
Although lifestyle and physiology in obese individuals are accepted to lead to changes in the intestinal microbiota, uncertainty remains about microbiota dysbiosis, and xenobiotics intake, as a source of selective pressure, independent of antimicrobial chemotherapy. The aim of this study was to compare the occurrence of antimicrobial resistance genetic markers (ARG) in faecal specimens of eutrophic, overweight and obese individuals, and their correlation with xenobiotic intake and gut bacteria density. Methods: This was a cross-sectional case-controlled study including 72 adult participants with no record of intestinal or systemic diseases, or recent use of antimicrobials, grouped as eutrophic, overweight, or obese. Anthropometric profile, eating habits and oral xenobiotics intake were recorded. Faecal metagenomic DNA was used to screen for ARG by PCR, and to measure bacterial groups by fluorescence in situ hybridization (FISH). Student's t and Wilcoxon tests were used to compare means and differences in ARG detection (95% confidence intervals). Correlation analyses (odds ratio) and relationships between bacteria density and ARG were determined. Results: Increase in abdominal circumference, waist circumference, hip, waist-hip ratio, BMI, carbohydrate, fibres, and total calorie intakes were different from eutrophic to obese participants. Habitual use of antihypertensive and anti-inflammatory drugs, antacids, and artificial sweeteners were associated mainly with obesity and overweight. Nutritional supplements were associated to the eutrophic group. ARG screening showed differences being more frequent among obese, and positive for 27 genetic markers related to ß-lactams, tetracyclines, the macrolide lincosamide and streptogramin group, quinolones, sulfonamides, aminoglycosides, and efflux pump. Positive correlation between ARG and BMI, caloric intake, and intake of xenobiotics, was observed for obese individuals. Relationships among ARG detection and bacteria densities were also different. Conclusions: This study reinforces the hypothesis that obese individuals may harbour an altered gut microbiota, if compared to eutrophic. The overweight individuals display a transitional gut microbiota which seems to be between eutrophic and obese. Furthermore, the increased xenobiotic intake associated to obesity may play an important role in the antimicrobial resistance phenomenon.
Assuntos
Resistência Microbiana a Medicamentos/genética , Trato Gastrointestinal/microbiologia , Sobrepeso/microbiologia , Adulto , Antiácidos/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , Anti-Hipertensivos/uso terapêutico , Suplementos Nutricionais , Fezes/microbiologia , Feminino , Microbioma Gastrointestinal/genética , Humanos , Hibridização in Situ Fluorescente , Masculino , Pessoa de Meia-Idade , Edulcorantes/administração & dosagem , Xenobióticos/administração & dosagem , Adulto JovemRESUMO
Sea urchin gametes have been historically used to demonstrate fertilization and early development in student laboratories. Large amounts of egg and sperm are easily acquired, and the conspicuous changes in egg surface morphology, indicative of sperm-egg fusion and egg activation, are readily observed in the classroom. However, less often incorporated into teaching labs are exercises that demonstrate the dramatic metabolic changes that accompany egg activation. One example is the massive up-regulation of various essential transport activities in the embryo's plasma membrane, including xenobiotic transporter activity. Here we outline a laboratory that incorporates this concept into a teaching lab, capitalizing on the magnitude and uniformity of the xenobiotic transporter activation event in certain species of sea urchins. The introduction of this chapter provides background information for the instructor, and the remainder serves as a laboratory manual for students. The experiments detailed within the manual can be completed in a total of 4-8h spread over one or two lab periods. The lab manual guides students through a modified version of the United States Environmental Protection Agency (EPA) toxicity test, a novel undergraduate-level laboratory on xenobiotic transporters, and analysis of microscope data using ImageJ. We have found this lab to be of interest to a wide range of biology and environmental science undergraduates, and effective in teaching underlying concepts in developmental biology, physiology and toxicology.
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Fertilização/efeitos dos fármacos , Ouriços-do-Mar/efeitos dos fármacos , Xenobióticos/administração & dosagem , Animais , Transporte Biológico/efeitos dos fármacos , Membrana Celular/metabolismo , Biologia do Desenvolvimento/métodos , Embrião de Mamíferos/efeitos dos fármacos , Células Germinativas/efeitos dos fármacosRESUMO
Qingre Xiaoyanning capsule is a famous traditional Chinese medicine prescription which consisted of Sarcandrae Herba (also named Caoshanhu in China) water extract for the frequent treatment of inflammation and immunity related diseases. Until now, the in vivo bioactive components of Qingre Xiaoyanning capsule have not yet been fully addressed. In this study, a total of 42 xenobiotics including 20 prototypes and 22 metabolites were identified in rats after oral administration of Qingre Xiaoyanning capsule using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Subsequently, isofraxidin and rosmarinic acid, two bioactive components with high exposure in rat plasma, were quantitatively analyzed, while another 20 major absorbed components were semi-quantitatively measured, to investigate together the pharmacokinetics behavior of Qingre Xiaoyanning capsule. Taken together, this study provided comprehensive knowledge of in vivo disposal of this prescription, which could help reveal the potential bioactive components, and would be conducive to further pharmacological mechanism research as well as quality control approach improvement of Qingre Xiaoyanning capsule and Sarcandrae Herba related prescriptions.
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Medicamentos de Ervas Chinesas/farmacocinética , Xenobióticos/farmacocinética , Administração Oral , Animais , Cromatografia Líquida de Alta Pressão , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/metabolismo , Masculino , Medicina Tradicional Chinesa , Estrutura Molecular , Ratos , Ratos Sprague-Dawley , Espectrometria de Massas em Tandem , Fatores de Tempo , Xenobióticos/administração & dosagem , Xenobióticos/metabolismoRESUMO
Oxidative stress leads to the activation of the Nuclear factor-erythroid-2-related factor 2 (Nrf2) pathway. While most studies have focused on the activation of the Nrf2 pathway after single chemical treatment, little is known about the dynamic regulation of the Nrf2 pathway in the context of repeated exposure scenarios. Here we employed single cell live imaging to quantitatively monitor the dynamics of the Nrf2 pathway during repeated exposure, making advantage of two HepG2 fluorescent protein reporter cell lines, expressing GFP tagged Nrf2 or sulfiredoxin 1 (Srxn1), a direct downstream target of Nrf2. High throughput live confocal imaging was used to measure the temporal dynamics of these two components of the Nrf2 pathway after repeated exposure to an extensive concentration range of diethyl maleate (DEM) and tert-butylhydroquinone (tBHQ). Single treatment with DEM or tBHQ induced Nrf2 and Srxn1 over time in a concentration-dependent manner. The Nrf2 response to a second treatment was lower than the response to the first exposure with the same concentration, indicating that the response is adaptive. Moreover, a limited fraction of individual cells committed themselves into the Nrf2 response during the second treatment. Despite the suppression of the Nrf2 pathway, the second treatment resulted in a three-fold higher Srxn1-GFP response compared to the first treatment, with all cells participating in the response. While after the first treatment Srxn1-GFP response was linearly related to Nrf2-GFP nuclear translocation, such a linear relationship was less clear for the second exposure. siRNA-mediated knockdown demonstrated that the second response is dependent on the activity of Nrf2. Several other, clinically relevant, compounds (i.e., sulphorophane, nitrofurantoin and CDDO-Me) also enhanced the induction of Srxn1-GFP upon two consecutive repeated exposure. Together the data indicate that adaptation towards pro-oxidants lowers the Nrf2 activation capacity, but simultaneously primes cells for the enhancement of an antioxidant response which depends on factors other than just Nrf2. These data provide further insight in the overall dynamics of stress pathway activation after repeated exposure and underscore the complexity of responses that may govern repeated dose toxicity.
Assuntos
Fator 2 Relacionado a NF-E2/metabolismo , Xenobióticos/toxicidade , Relação Dose-Resposta a Droga , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células Hep G2 , Humanos , Hidroquinonas/administração & dosagem , Hidroquinonas/toxicidade , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator de Transcrição MafF/genética , Fator de Transcrição MafG/genética , Maleatos/administração & dosagem , Maleatos/toxicidade , Imagem Molecular/métodos , Fator 2 Relacionado a NF-E2/genética , Proteínas Nucleares/genética , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/genética , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Transporte Proteico/efeitos dos fármacos , Proteínas Repressoras/genética , Análise de Célula Única/métodos , Testes de Toxicidade , Xenobióticos/administração & dosagemRESUMO
As a continuous source of hormonal stimulation, environmentally ubiquitous estrogenic chemicals, ie, xenoestrogens (XEs), are a potential risk factor for breast carcinogenesis. Given their wide distribution in the environment and the fact that bisphenol-A (BPA), methylparaben (MP), and perfluorooctanoic acid (PFOA) are uniformly detected in unselected body fluid samples, it must be assumed that humans are simultaneously exposed to these chemicals almost daily. We studied the effects of a ternary mixture of BPA, MP, and PFOA on benign breast epithelial cells at the range of concentrations observed for single chemicals in human samples. Measurements of exposure impact relevant to the breast were based on endpoints associated with "hallmarks" of cancer and "key characteristics" of carcinogens. These included modulation of total estrogen receptor (ER)α, phosphorylated ERα (pERα), total ERß, S-phase induction, and apoptotic evasion. Data from live cell measurements were fit to a log-linear dose-response model. Concentration-dependent reduction of ERß and apoptosis evasion was observed concurrently with the induction of ERα, pERα, and S-phase fraction, and an increased rate of cell proliferation. Beyond additive effects predicted by the sum of individual test XEs, mixture treatment demonstrated synergism for the ERß and apoptosis suppression phenotypes (p > .001). Nonmalignant breast cells were more sensitive than commonly used breast cancer lines to XE treatment in 3 of 5 endpoints. All observations were validated with cells isolated from the normal breast tissue of 14 individuals. At relatively low concentrations, a chemical mixture has striking effects on normal cell function that are missed by evaluation of single components.
Assuntos
Apoptose/efeitos dos fármacos , Mama/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/metabolismo , Xenobióticos/administração & dosagem , Xenobióticos/toxicidade , Compostos Benzidrílicos/administração & dosagem , Compostos Benzidrílicos/toxicidade , Mama/metabolismo , Mama/patologia , Caprilatos/administração & dosagem , Caprilatos/toxicidade , Linhagem Celular , Relação Dose-Resposta a Droga , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Fluorocarbonos/administração & dosagem , Fluorocarbonos/toxicidade , Humanos , Parabenos/administração & dosagem , Parabenos/toxicidade , Fenóis/administração & dosagem , Fenóis/toxicidadeRESUMO
The US EPA's ToxCast program is designed to assess chemical perturbations of molecular and cellular endpoints using a variety of high-throughput screening (HTS) assays. However, existing HTS assays have limited or no xenobiotic metabolism which could lead to false positive (chemical is detoxified in vivo) as well as false negative results (chemical is bioactivated in vivo) and thus potential mischaracterization of chemical hazard. To address this challenge, the ten most prevalent human liver cytochrome P450 (CYP) enzymes were introduced into a human cell line (HEK293T) with low endogenous metabolic capacity. The CYP enzymes were introduced via transfection of modified mRNAs as either singlets or as a mixture in relative proportions as expressed in human liver. Initial experiments using luminogenic substrates demonstrate that CYP enzyme activities are significantly increased when co-transfected with an mRNA encoding a CYP accessory protein, P450 oxidoreductase (POR). Transfected HEK293T cells demonstrate the ability to produce predicted metabolites following treatment with well-studied CYP substrates for at least 18â¯h post-treatment. As a demonstration of how this method can be used to retrofit existing HTS assays, a proof-of-concept screen for cytotoxicity in HEK293T cells was conducted using 56 test compounds. The results demonstrate that the xenobiotic metabolism conferred by transfection of CYP-encoding mRNAs shifts the dose-response relationship for some of the tested chemicals such as aflatoxin B1 (bioactivation) and fenazaquin (detoxification). Overall, transfection of CYP-encoding mRNAs is an effective and portable solution for retrofitting existing cell-based HTS assays with metabolic competence.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Ensaios de Triagem em Larga Escala/métodos , RNA Mensageiro/metabolismo , Xenobióticos/metabolismo , Aflatoxina B1/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Relação Dose-Resposta a Droga , Células HEK293 , Humanos , Fígado/enzimologia , Quinazolinas/metabolismo , Transfecção , Xenobióticos/administração & dosagemRESUMO
INTRODUCTION: It was assumed for decades that the human placenta serves as a barrier, protecting the fetus from exposure to xenobiotics circulating in the mother. The thalidomide disaster completely reversed this concept. The study of the human placenta is therefore critical to understanding the mechanisms by which xenobiotics reach the fetus and exert their effects. Areas covered: This review describes mechanisms by which drugs interact with the human placenta, and experimental methods to study these interactions in humans. We have selected three areas of current clinical interest, where the placenta exhibits critical role in drug transport: The ABC transporters, the placental handling of cancer therapeutic drugs and the interaction between the placenta and immunoglobulins. Expert commentary: The optimal model to predict drug transfer and transport from the mother to the fetus is the isolated human placental lobule perfused in vitro. Unlike subcellular preparations or tissue homogenates, data obtained from a perfused intact tissue, where structural integrity and cell-cell organization are maintained, more closely reflect the in vivo situation. Moreover, confounding metabolic and physiologic influences are minimized and the experimental conditions can be controlled. It is important to remember that due to significant differences in the function of the placenta in the first two months (histiotrophic nutrition) and later in pregnancy (hemotrophic nutrition) there might be differences in the transplacental transfer of drugs. While most of our knowledge comes from studies on term placentae, we are in need of studies on young placenta that functions during the period of organogenesis.
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Troca Materno-Fetal , Placenta/metabolismo , Xenobióticos/farmacocinética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Transporte Biológico/fisiologia , Feminino , Feto/metabolismo , Humanos , Gravidez , Xenobióticos/administração & dosagemRESUMO
Bisphenol A (BPA), a common environmental xenoestrogen, has been implicated in physiological and behavioral impairment, but the neuronal basis remains elusive. Although various synaptic mechanisms have been shown to mediate BPA-induced brain deficits, there are almost no reports addressing its underlying physiological mechanisms at the individual neuron level, particularly in the primary visual system. In the present study, using multiple-channel recording technique, we recorded the responses of single neurons in the primary visual system of cats to various direction stimuli both before and after BPA exposure. The results showed that the orientation selectivity of neurons in the primary visual cortex (area 17, A17) was obviously decreased after 2 h of intravenous BPA administration (0.2 mg/kg). Moreover, there were worse performances of information transmission of A17 neurons, presenting markedly decreased signal-to-noise ratio (SNR). To some extent, these functional decreases were attributable to the altered information inputs from lateral geniculate nucleus (LGN), which showed an increased spontaneous activity. Additionally, local injection of BPA (3.3 µg/ml) in A17 resulted in an obvious increase in orientation selectivity and a decrease in neuronal activity, involving enhanced activity of fast-spiking inhibitory interneurons. In conclusion, our results first demonstrate that acute BPA exposure can restrict the visual perception of cats, mainly depending on the alteration of the LGN projection, not the intercortical interaction. Importantly, BPA-induced-brain deficits might not only be confined to the cortical level but also occur as early as at the subcortical level.
Assuntos
Compostos Benzidrílicos/toxicidade , Neurônios/efeitos dos fármacos , Fenóis/toxicidade , Córtex Visual/efeitos dos fármacos , Vias Visuais/efeitos dos fármacos , Animais , Compostos Benzidrílicos/administração & dosagem , Gatos , Corpos Geniculados/efeitos dos fármacos , Corpos Geniculados/patologia , Neurônios/patologia , Fenóis/administração & dosagem , Estimulação Luminosa , Razão Sinal-Ruído , Córtex Visual/patologia , Vias Visuais/patologia , Xenobióticos/administração & dosagem , Xenobióticos/toxicidadeRESUMO
In marine animals with external fertilization, gametes are released into seawater where fertilization and embryo development occur. Consequently, pollutants introduced into the marine environment by human activities may affect gametes and embryos. These xenobiotics can alter cell physiology with consequent reduction of fertilization success. Here the adverse effects on the reproductive processes of the marine invertebrate Ciona intestinalis (ascidian) of different xenobiotics: lead, zinc, an organic tin compound and a phenylurea herbicide were evaluated. By using the electrophysiological technique of whole-cell voltage clamping, the effects of these compounds on the mature oocyte plasma membrane electrical properties and the electrical events of fertilization were tested by calculating the concentration that induced 50% normal larval formation (EC50). The results demonstrated that sodium currents in mature oocytes were reduced in a concentration-dependent manner by all tested xenobiotics, with the lowest EC50 value for lead. In contrast, fertilization current frequencies were differently affected by zinc and organic tin compound. Toxicity tests on gametes demonstrated that sperm fertilizing capability and fertilization oocyte competence were not altered by xenobiotics, whereas fertilization was inhibited in zinc solution and underwent a reduction in organic tin compound solution (EC50 value of 1.7 µM). Furthermore, fertilized oocytes resulted in a low percentage of normal larvae with an EC50 value of 0.90 µM. This study shows that reproductive processes of ascidians are highly sensitive to xenobiotics suggesting that they may be considered a reliable biomarker and that ascidians are suitable model organisms to assess marine environmental quality.
Assuntos
Ciona intestinalis/efeitos dos fármacos , Oócitos/efeitos dos fármacos , Oócitos/fisiologia , Poluentes Químicos da Água/toxicidade , Xenobióticos/toxicidade , Animais , Membrana Celular/efeitos dos fármacos , Ciona intestinalis/fisiologia , Diurona/toxicidade , Relação Dose-Resposta a Droga , Eletrofisiologia/métodos , Feminino , Fertilização/efeitos dos fármacos , Larva/efeitos dos fármacos , Chumbo/administração & dosagem , Chumbo/toxicidade , Masculino , Sódio/metabolismo , Interações Espermatozoide-Óvulo/efeitos dos fármacos , Testes de Toxicidade/métodos , Poluentes Químicos da Água/administração & dosagem , Xenobióticos/administração & dosagem , Zinco/administração & dosagem , Zinco/toxicidadeRESUMO
Tabaco e álcool são considerados os principais fatores de risco para o carcinoma de células escamosas (CCE) bucal contribuindo de maneira desfavorável para o tratamento e desfecho clínico. Seus carcinógenos são metabolizados em duas fases, sendo a segunda fase realizada pelas Glutationa S-transferases (GSTs). O objetivo do presente estudo foi avaliar a expressão gênica da forma selvagem dos genes GSTM1, GSTP1 e GSTT1 por qPCR em 33 amostras de CCE bucal de fumantes, ex-fumantes e não fumantes, e 15 controles em busca de uma correlação clínica com consumo de tabaco, álcool e estadiamento clínico. A dependência nicotínica foi avaliada pelo Teste de Fagerström pra Dependência a Cigarros (TFDC) e para consumo de etílicos o Teste AUDIT. Foi observado aumento da expressão de GSTM1 no Grupo CCE fumante em relação ao Grupo Controle (p=0,0161). Contrariamente, foi encontrada uma menor expressão de GSTT1 no Grupo CCE fumante em relação ao Grupo Controle fumante (p=0,0183). No grupo CCE fumante não foi encontrada uma correlação entre a expressão dos genes estudados e fatores ligados ao tabagismo, etilismo e estadiamento clinico. No grupo Controle fumante, houve correlação entre teste AUDIT e a expressão de GSTM1 (p=0,0000). Para GSTP1 e GSTT1 houve correlação entre a expressão quando comparada a idade do paciente (p=0,0008; p=0,0095), idade de inicio do tabagismo (p=0,0033; p=0,0081), TFDC (p=0,0102; p=0,0085) e AUDIT (p=0,0052; p=0,0219) respectivamente. Para GSTT1 foi encontrada uma correlação entre a expressão e número de cigarros/dia (p=0,0175). Concluímos que as formas selvagens das GSTs estudadas apresentaram uma alta expressão nas amostras de CCE bucal, entretanto, quantitativamente essa expressão foi baixa, com grande variabilidade interindividual. Outrossim, não houve uma correlação direta entre níveis de expressão, carga tabágica, TFDC, teste AUDIT e estadiamento clínico. O aumento da expressão de GSTM1 e GSTP1 parece não ter tido um efeito protetor. A baixa expressão de GSTT1 em pacientes fumantes com CCE bucal se mostrou um potencial marcador a ser avaliado em pacientes fumantes que ainda não desenvolveram uma neoplasia maligna(AU)
Tobacco and alcohol are considered to be the main risk factors for oral squamous cell carcinoma (SCC), contributing to treatment and clinical outcome. Its carcinogens are metabolized in two phases, being the second phase carried out by Glutathione Stransferases (GSTs). The objective of the present study was to evaluate the wild-type gene expression of the GSTM1, GSTP1 and GSTT1 genes by qPCR in 33 samples of oral SCC from smokers, former smokers and nonsmokers, and 15 controls looking for a clinical correlation with tobacco and alcohol consumption and clinical staging. Nicotinic dependence was assessed by the Fagerström Test for Cigarette Dependence (TFCD) and alcohol consumption by the AUDIT Test. Increased expression of GSTM1 in the Smoker SCC Group was observed in relation to the Control Group (p=0.0161). Conversely, a lower expression of GSTT1 was found in the smoker SCC group compared to the Smoker Control Group (p=0.0183). In the smoker SCC group, no correlation was found between the genes expression studied and factors related to smoking, alcoholism and clinical staging. In the Smoker Control Group, there was a correlation between the AUDIT test and the GSTM1 expression (p=0.0000). For GSTP1 and GSTT1, there was a correlation between the expression compared with the patient's age (p=0.0008, p=0.0095), age of starting smoking (p=0.0033, p=0.0081), FTCD (p=0.0102, p=0.0085) and AUDIT (p=0.0052, p=0.0219) respectively. For GSTT1 a correlation was found between expression and number of cigarettes/day (p=0.0175). We concluded that the wild forms of the GSTs studied presented a high expression in the samples of oral SCC; however, quantitatively this expression was low, with great interindividual variability. Also, there was no direct correlation between levels of expression, pack-years, FTCD, AUDIT Test and clinical stage. Increased expression of GSTM1 and GSTP1 appears to have had no protective effect. The low GSTT1 expression in smokers with oral SCC was shown to be a potential marker to be evaluated in smoker patients who have not yet developed a malignant neoplasm(AU)
Assuntos
Humanos , Neoplasias Bucais/etnologia , Carcinogênese/efeitos dos fármacos , Carcinoma de Células Escamosas/complicações , Expressão Gênica/genética , Xenobióticos/administração & dosagemRESUMO
The human body is an open system that receives a variety of xenobiotics in the course of dietary route or respiration and in the form of the drugs. As a lump sum scores of toxic and potentially toxic substances are detected in a human body that significantly affect health and human lifespan. There are also thousands of diseases, dozens of which latently occur in the body of each person. Traditional diagnosis is not able to screen all the variety of xenobiotics and potential human diseases. For this purpose metabolomic blood test is available which is of non-targeted (review) nature. The test can reveal all the diversity of low molecular weight substances in blood, including tens of thousands of xenobiotics and markers of different diseases. Detection of xenobiotics in the blood, directional detoxification and subsequent monitoring of "body's chemical purity" together with the control of "normality" of all biochemical processes in the organism, using metabolomics blood tests is a necessary and presumably a sufficient condition in the implementation of inherent human genotype longevity. This article describes the purpose, implementation and interpretation of metabolomic blood test facilitating the implementation of this method in the Russian Federation, in order to significantly increase the average life expectancy.