Toxicology Mechanisms and Methods最新文献

During out-of-area military operations, the presence of carcinogenic and/or genotoxic agents has been reported, posing potential health risks to deployed soldiers. Military working dogs (MWDs), trained to detect explosives in the same environments as soldiers, could also serve as sentinel animals, providing valuable information on exposure to hazardous agents. These dogs can help identify environmental and potential adverse effects on their health and that of their handlers, possibly before relevant pathologies manifest. This study aims to evaluate the effectiveness of 33 Italian Army MWDs, deployed to the Lebanese theater for six consecutive months from October 2013 to January 2015, as sentinel animals for detecting exposure to genotoxic agents. The Cytokinesis-Block MicroNucleus (CBMN) assay was used to assess DNA damage, cytostasis, and cytotoxicity in the lymphocytes of these dogs. DNA damage events were specifically scored in once-divided binucleated cells (BCs) and included: a) micronuclei (MNi), indicative of chromosome breakage and/or whole chromosome loss; b) nucleoplasmic bridges (NPBs), a marker of DNA misrepair and/or telomere end-fusions; and c) nuclear buds (NBUDs), which signal the elimination of amplified DNA and/or DNA repair complexes. Our findings revealed an increase in chromosomal damage, assessed before and after deployment, with a statistically significant rise in MNi frequency, thus supporting the use of MWDs as sentinels for human exposure to hazardous agents.

Current studies have clearly shown that aristolochic acid (AA) exposure can induce a variety of diseases, such as kidney disease, liver cancer, and urinary tract cancer (UTC). However, no studies have systematically analyzed and integrated these results. Therefore, we aimed to elucidate the association between AA exposure and the risk of safety outcomes for AA-related overall disease and different types of disease it causes. We conducted an exhaustive search of PubMed, EMBASE, Web of Science, and the Cochrane Library for relevant material up to April 2024. For AA-related overall disease, AA exposure was significantly associated with an increased incidence of AA-related overall disease (OR: 1.289, 95% CI: 1.183 - 1.404). For different types of disease, AA exposure was significantly associated with increased incidence of kidney disease (OR: 1.279, 95% CI: 1.029 - 1.590), UTC (OR: 1.842, 95% CI: 1.376 - 2.465) and liver cancer (OR: 1.146, 95% CI: 1.040 - 1.262). No significant association was found between AA exposure and the incidence of brain disease (OR: 1.161, 95% CI: 0.989 - 1.362). This study systematically analyzed various safety outcomes associated with AA exposure to provide a solid scientific basis for future prevention strategies and clinical management.

The harmful by-product of paracetamol is known as N-Acetyl-p-benzoquinoneimine, (NAPQI). When paracetamol is given at therapeutic dosages or in excess, it undergoes Phase I metabolism in the liver via Cytochrome P-450 2E1 (CYP2E1), and then it produces NAPQI. Previous studies reported that a non-ionic surfactant known as Brij 35 (Polyoxyethylene lauryl ether) has been shown to be an effective inhibitor of CYP2E1 and P-glycoprotein (P-gp). Hence, this in vitro and in vivo investigation set out to assess Brij 35 impact on paracetamol CYP2E1-mediated metabolism. For the in vitro investigation, isolated rat hepatocytes were used. Male Wistar rats were used for in vivo studies. There were thirty rats in total, with six individuals each group distributed among the five groups. The first group animals received 0.5% sodium carboxy methyl cellulose (control group); the second group animals treated with 300 mg/kg of paracetamol; the third group animals treated with Brij 35 (5 mg/kg) along with 300 mg/kg of paracetamol; the fourth group animals treated with 10 mg/kg of Brij 35 along with 300 mg/kg of paracetamol and the fifth group animals treated with 20 mg/kg of Brij 35 along with 300 mg/kg of paracetamol for consecutive 21 days. The current study found that paracetamol plasma concentrations were much higher and NAPQI plasma concentrations were much lower when Brij 35 was co-administered may be due to inhibition of CYP2E1-mediated metabolism and P-gp-mediated intestinal transport of paracetamol. Brij 35 also reduced the increased hepatic and renal markers with significant hepatoprotective and nephroprotective changes in the histopathological investigation.

Endocrine-disrupting chemicals (EDCs) significantly contribute to health issues by interfering with hormonal functions. Bisphenol A (BPA), a prominent EDC, is extensively utilized as a monomer and plasticizer in producing polycarbonate plastic and epoxy resins, making it one of the highest-demanded chemicals in commercial use. This is the major component used in plastic products, including bottles, containers, storage items, and food serving ware. Exposure of BPA happens through oral, respiratory, transdermal routes and eye contact. As an EDC, BPA disrupts hormonal binding, leading to various health problems, such as cancers, reproductive abnormalities, metabolic syndrome, immune dysfunction, neurological effects, cardiovascular problems, respiratory issues, and obesity. BPA mimics the hormone estrogen but exhibits a weak affinity for estrogen receptors. This weak binding affinity triggers multiple cell death pathways, including necroptosis, pyroptosis, apoptosis, ferroptosis, and autophagy, across different cell types. Numerous clinical, in-vitro, and in-vivo experiments have demonstrated that BPA exposure results in unfavorable health effects. This review highlights the mechanisms of cell death pathways initiated through BPA exposure and the associated negative health consequences. The extensive use of BPA and its frequent detection in environmental and biological models underscore the urgent need for further investigation into its effects and the development of safe alternatives. Addressing the health risks posed by BPA involves a comprehensive approach that includes reducing exposure and finding novel substitutes to lessen its detrimental impact on humans.

Mitochondria are affected by chemical substances and play a critical role in drug-induced liver injury (DILI). Chemical substances can have a significant impact on various cellular processes, such as the disruption of oxidative phosphorylation, oxidative stress, and alteration of glucose metabolism. Given the consequences of these effects, it is crucial to understand the molecular pathways of chemical substances in the context of hepatotoxicity to prevent and treat DILI. In this regard, the Seahorse XFe24 Analyzer is a valuable tool for assessing mitochondrial bioenergetics and glucose metabolism. The Mito Stress Test and Glycolytic Rate Assay allow real-time assessment of the metabolic state after chemical exposure. Additionally, HepG2 spheroids have emerged as an important alternative tool for assessing hepatotoxicity, as they provide results that are more comparable to those found in humans than monolayer cultures or animal tests (such as rodent tests). By integrating these two powerful tools, it is possible to bridge the gap between animal and human tests, resulting in more reliable results in the assessment of human hepatotoxicity and DILI. However, because of the high variability in characteristics between 3D cultures (such as spheroids and organoids), XF analyzer assays are not well optimized for use with HepG2 spheroids. Here, we describe a streamlined and optimized protocol for performing the Mito Stress Test and Glycolytic Rate Assay using HepG2 spheroids cultured in alginate microcapsules in the Seahorse XFe24 Analyzer.

Pymetrozine (a pyridine azomethine pesticide) is one of the most commonly and frequently used insecticides. Scanty information is available about the deleterious effects of Pymetrozine on fish especially bighead carp. Hence, the current study investigated chronic toxicological effects of pymetrozine in bighead carp. A total of 80 fish were reared and divided into four groups(A-D) each containing 20 fish. Pymetrozine was given to experimental fish of groups B, C, and D mixed in water at doses of 5, 10, and 15 mg/L respectively for 30 days. Group A remained as control group. On days 10, 20, and 30 of the experiment, blood and other visceral tissues were collected for analysis of genotoxic effects, erythrocytic morphological and nuclear changes, antioxidant enzymes, and oxidative stress profile. The results revealed significantly higher values of various nuclear abnormalities (erythrocyte with micronuclei, red blood cells with condensed and lobed nuclei) and morphological changes (pear shaped erythrocyte, spindle shaped erythrocytes and spherocyte) in erythrocytes of bighead carp. The investigations on status of antioxidant enzymes and oxidative stress indicated higher values of oxidative stress biomarkers and lower values of antioxidant enzymes in visceral organs (brain, liver, gills, and kidneys) of treated fish. The findings on genotoxic potential of pymetrozine revealed a considerably increased frequency of DNA damage in isolated cells of multiple tissues (brain, liver, gills, and kidneys) of experimental fish at higher doses. In conclusion, it may be suggested that pymetrozine induces toxic effects via disruption of physiological mechanisms of multiple visceral organs of bighead carp.

Tetrahydroxy-1,4-benzoquinone (THQ) is a highly redox-active substance that generates reactive oxygen species (ROS), which can induce apoptosis in cell culture experiments. The underlying mechanism for ROS production has previously been postulated to be the autoxidation of THQ to rhodizonic acid (RhA). However, our results suggest that the cells detoxify THQ by reducing it to hexahydroxybenzene (HHB), catalyzed by the NADPH-quinone-oxidoreductase (NQO1). Then, HHB undergoes autoxidation back to THQ, closing a redox cycle that continuously generates ROS. Only this continuous mechanism produces enough ROS to trigger apoptosis. The cell's protective measures can effectively eliminate the ROS generated by a single autoxidation of THQ to RhA because RhA is not reduced back to THQ and thus does not close a redox cycle. This also explains why only fresh THQ solutions are cytotoxic, whereas older THQ solutions, which are readily autoxidized to RhA, are not.

The rat S9 microsome fraction is commonly used to assess compound metabolite formation during in vitro genotoxicity assessments. However, methods using S9 have not been standardized for genotoxicity studies, and different experimental methods are used at various facilities. Therefore, this study investigated whether the differences between the two experimental conditions (1) S9 inducers, phenobarbital + beta-naphthoflavones vs. Aroclor 1254 and (2) the plate incubation vs. preincubation method) in the micro-Ames test would affect the results. Nitrosamine and in-house genotoxicity-positive compounds were used with benzopyrene and 2-aminofluorene as positive control compounds. No differences were observed in the genotoxicity results in the groups treated with the positive control. However, the S9 fraction induced by Aroclor 1254 showed higher cytochrome P450 activity than the fraction induced by phenobarbital and beta-naphthoflavone. The incubation method also affected the results; the nitrosamine compounds showed different genotoxicity activity between the plate incorporation method and preincubation method. In-house aminomethyl quinoline compounds also showed different results depending on the S9 type. These results suggest that different inducers and methods induce various metabolic enzyme activities, which may lead to differences in genotoxicity through distinct metabolite production.

Sanguinarine (SAN) is an alkaloid with multiple biological activities, mainly extracted from Sanguinaria canadensis or Macleaya cordata. The low bioavailability of SAN limits its utilization. At present, the nature and mechanism of SAN intestinal absorption are still unclear. The pharmacokinetics, single-pass intestinal perfusion test (SPIP), and equilibrium solubility test of SAN in rats were studied. The absorption of SAN at 20, 40, and 80 mg/L in different intestinal segments was investigated, and verapamil hydrochloride (P-gp inhibitor), celecoxib (MPR2 inhibitor), and ko143 (BCRP inhibitor) were further used to determine the effect of efflux transporter proteins on SAN absorption. The equilibrium solubility of SAN in three buffer solutions (pH 1.2, 4.5 and 6.8) was investigated. The oral pharmacokinetic results in rats showed that SAN was rapidly absorbed (T_max=0.5 h), widely distributed (Vz/F = 134 L/kg), rapidly metabolized (CL = 30 L/h/kg), and had bimodal phenomena. SPIP experiments showed that P-gp protein could significantly affect the effective permeability coefficient (P_eff) and apparent absorption rate constant (Ka) of SAN. Equilibrium solubility test results show that SAN has the best solubility at pH 4.5. In conclusion, SAN is a substrate of P-gp, and its transport modes include efflux protein transport, passive transport and active transport.