Toxicological Research最新文献

Skin sensitization is induced when certain chemicals bind to skin proteins. Direct peptide reactivity assay (DPRA) has been adopted by the OECD as an alternative method to evaluate skin sensitization by assessing a substance's reaction to two model peptides. A modified spectrophotometric method, Spectro-DPRA, can evaluate skin sensitization, in a high throughput fashion, to obviate some limitations of DPRA. Pre-validation studies for Spectro-DPRA were conducted to determine transferability and proficiency, within- and between-laboratory reproducibility, and predictive ability based on GLP principles at three laboratories (AP, KTR, and KCL). All laboratories confirmed high (> 90%) concordance for evaluating the sensitivity induced by ten chemical substances. The concordance among the three tests performed by each laboratory was 90% for AP, 100% for KTR, and 100% for KCL. The mean accuracy of the laboratories was 93.3% [compared to the standard operating procedure (SOP)]. The reproducibility among the three laboratories was as high as 86.7%; the accuracy was 86.7% for AP, 100% for KTR, and 86.7% for KCL (compared to the SOP). An additional 54 substances were assessed in 3 separate labs to verify the prediction rate. Based on the result, 29 out of 33 substances were classified as sensitizers, and 19 out of 21 identified as non-sensitizers; the corresponding sensitivity, specificity, and accuracy values were 87.9%, 90.5%, and 88.9%, respectively. These findings indicate that the Spectro-DPRA can address the molecular initiating event with improved predictability and reproducibility, while saving time and cost compared to DPRA or ADRA.

The present aimed to characterize the toxicity of silica nanoparticles in Sprague Dawley rats and determine the dose levels for a repeated-dose toxicity study. Silica nanoparticles (SiO₂, 20 nm and 50 nm) were administered as a single intratracheal instillation of standardized SiO₂ 20 nm (low dose, 200 µg/mL; high dose, 400 µg/mL) and 50 nm (low dose, 200 µg/mL; high dose, 400 µg/mL). Each group consisted of five male rats. We documented the mortality rate, clinical signs, body weight, bronchoalveolar lavage fluid analysis, hematological values, serum chemistry values, organ weight, gross findings at necropsy, and histopathological assessments. Rats treated with 200 µg/mL and 400 µg/mL SiO₂ 50 nm exhibited a decreased mean corpuscular volume, while those treated with 400 µg/mL of SiO₂ 50 nm showed increases in absolute monocyte and absolute lymphocyte count as well as prothrombin time. In addition, rats treated with 400 µg/mL SiO₂ 20 nm and 50 nm presented reduced creatinine, alanine aminotransferase, and sodium levels. Therefore, a single intratracheal instillation of SiO₂ 20 nm and 50 nm elicited no toxicity up to a dose of 400 µg/mL, and the approximate lethal dose of this test substance exceeded 400 µg/mL in male Sprague Dawley rats under the present experimental conditions.

The heart has an abundance of mitochondria since cardiac muscles require copious amounts of energy for providing continuous blood through the circulatory system, thereby implying that myocardial function is largely reliant on mitochondrial energy. Thus, cardiomyocytes are susceptible to mitochondrial dysfunction and are likely targets of mitochondrial toxic drugs. Various methods have been developed to evaluate mitochondrial toxicity by evaluating toxicological mechanisms, but an optimized and standardized assay for cardiomyocytes remains unmet. We have therefore attempted to standardize the evaluation system for determining cardiac mitochondrial toxicity, using AC16 human and H9C2 rat cardiomyocytes. Three clinically administered drugs (acetaminophen, amiodarone, and valproic acid) and two anticancer drugs (doxorubicin and tamoxifen) which are reported to have mitochondrial effects, were applied in this study. The oxygen consumption rate (OCR), which directly reflects mitochondrial function, and changes in mRNA levels of mitochondrial respiratory complex I to complex V, were analyzed. Our results reveal that exposure to all five drugs results in a concentration-dependent decrease in the basal and maximal levels of OCR in AC16 cells and H9C2 cells. In particular, marked reduction in the OCR was observed after treatment with doxorubicin. The reduction in OCR after exposure to mitochondrial toxic drugs was found to be associated with reduced mRNA expression in the mitochondrial respiratory complexes, suggesting that the cardiac mitochondrial toxicity of drugs is majorly due to dysfunction of mitochondrial respiration. Based on the results of this study, we established and standardized a protocol to measure OCR in cardiomyocytes. We expect that this standardized evaluation system for mitochondrial toxicity can be applied as basic data for establishing a screening platform to evaluate cardiac mitochondrial toxicity of drugs, during the developmental stage of new drug discovery.

Histopathological examination is important for the diagnosis of various diseases. Conventional histopathology provides a two-dimensional view of the tissues, and requires the tissue to be extracted, fixed, and processed using histotechnology techniques. However, there is an increasing need for three-dimensional (3D) images of structures in biomedical research. The objective of this study was to develop reliable, objective tools for visualizing and quantifying metastatic tumors in mouse lung using micro-computed tomography (micro-CT), optical coherence tomography (OCT), and field emission-scanning electron microscopy (FE-SEM). Melanoma cells were intravenously injected into the tail vein of 8-week-old C57BL/6 mice. The mice were euthanized at 2 or 4 weeks after injection. Lungs were fixed and examined by micro-CT, OCT, FE-SEM, and histopathological observation. Micro-CT clearly distinguished between tumor and normal cells in surface and deep lesions, thereby allowing 3D quantification of the tumor volume. OCT showed a clear difference between the tumor and surrounding normal tissues. FE-SEM clearly showed round tumor cells, mainly located in the alveolar wall and growing inside the alveoli. Therefore, whole-tumor 3D imaging successfully visualized the metastatic tumor and quantified its volume. This promising approach will allow for fast and label-free 3D phenotyping of diverse tissue structures.

The plant Combretum hypopilinum Diels (Combretaceae) has been utilized in Nigeria and other African nations to treat many diseases including liver, inflammatory, gastrointestinal, respiratory, infectious diseases, epilepsy and many more. Pharmacological investigations have shown that the plant possesses anti-infective, antidiarrhoeal, hepatoprotective, anti-inflammatory, anticancer, sedative, antioxidant, and antiepileptic potentials. However, information on its toxicity profile is unavailable despite the plant's therapeutic potential. As such, this work aimed to determine the acute and sub-acute oral toxic effects of the hydromethanolic leaves extract of C. hypopilinum. The preliminary phytochemical evaluation was carried out based on standard procedures. The acute toxicity evaluation was conducted by oral administration of the extract at the dose of 5000 mg/kg based on the guideline of the Organization of Economic Co-operation and Development (OECD) 423. To investigate the sub-acute toxicity effects, the extract was administered orally to the animals daily for 28-consecutive days at the doses of 250, 500, and 1000 mg/kg. Mortality, body weight and relative organ weight were observed. The hepatic, renal, haematological, and lipid profile parameters were investigated. The liver, kidney, heart, lung, small intestine, and stomach were checked for any histopathological alterations. The results of the phytochemical investigation showed cardiac glycosides, tannins, steroids, flavonoids, alkaloids, saponins, and triterpenes. Based on the acute toxicity investigation outcome, no death and signs of toxic effects were observed. The result showed that the oral median lethal dose (LD₅₀) of the extract was more than the 5000 mg/kg. The extract remarkably reduced the weekly body weight of the animals at 500 mg/kg in the first and second weeks. It also significantly decreased the relative kidney weight, alkaline phosphatase, glucose, potassium, and low-density lipoprotein. There was a remarkable elevation in the percentage of eosinophils, basophils, monocytes, and granulocyte. There were histopathological abnormalities on the kidney, lung, stomach, and small intestine. The extract is relatively safe on acute exposure but moderately toxic at higher doses on sub-acute administration, particularly to the kidney.

The pharmacological or toxicological activities of the degradation products of drug candidates have been unaddressed during the drug development process. Ischemic stroke accounts for 80% of all strokes and is responsible for considerable mortality and disability worldwide. Despite decades of research on neuroprotective agents, tissue plasminogen activators (t-PA), a thrombolytic agent, remains the only approved acute stroke pharmacological therapy. NXY-059, a free radical scavenger, exhibited striking neuroprotective properties in preclinical models and met all the criteria established by the Stroke Academic Industry Roundtable (STAIR) for a neuroprotective agent. In phase 3 clinical trials, NXY-059 exhibited significant neuroprotective effects in one trial (SAINT-I), but not in the second (SAINT-II). Some have hypothesized that N-t-butyl hydroxylamine (NtBHA), a breakdown product of NXY-059 was the actual neuroprotective agent in SAINT-I and that changes to the formulation of NXY-059 to prevent its breakdown to NtBHA in SAINT -II was the reason for the lack of efficacy. We evaluated the neuroprotective effect of NtBHA in N-methyl-D-aspartate (NMDA)-treated primary neurons and in rat focal cerebral ischemia. NtBHA significantly attenuated infarct volume in rat transient focal ischemia, and attenuated NMDA-induced cytotoxicity in primary cortical neurons. NtBHA also reduced free radical generation and exhibited mitochondrial protection.

Endocrine-disrupting chemicals (EDCs) are a structurally diverse class of synthetic and natural compounds. EDCs can cause non-communicable diseases such as obesity, type 2 diabetes, thyroid disorders, neurodevelopmental disease, hormone-dependent cancers, and reproductive disorders. The embryoid body test (EBT) is a developmental toxicity test method that determines the size of embryoid bodies (EBs) and the viability of mouse embryonic stem cells (mESCs) and fibroblasts (3T3 cells). The present study used the EBT to perform cytotoxicity evaluations of 10 EDCs and assessed the mechanistic relationship between endoplasmic reticulum (ER) stress and cytotoxicity. According to the statistical analysis and prediction model results, methylparaben, butylparaben, propylparaben, ethylparaben, triclosan, octylphenol, methoxychlor, bisphenol A, and diethylstilbestrol were classified as cytotoxic, but trichloroacetic acid was non-toxic. Classification accuracy was 90%. The mechanistic study showed that the cytotoxicities of butylparaben, propylparaben, octylphenol, and triclosan were induced by ER stress. The mRNA expressions of BiP, CHOP, and ATF4 were significantly higher following treatments with four EDCs compared to those after the control treatment. Compared to the control treatment, the mRNA levels of XBP1u and XBP1s increased significantly after butylparaben and propylparaben treatments, but did not increase with octylphenol and triclosan treatments. These results indicate that the EBT can be applied as an alternative toxicity test when evaluating the cytotoxicity of EDCs.

Scavenger receptor class F member 2 (SCARF2) is expressed by endothelial cells with very large cytoplasmic domains and is the second isotype, also known as scavenger receptor expressed by endothelial cells 2 (SREC-2). SREC-1 plays an important role in the binding and endocytosis of various endogenous and exogenous ligands. Many studies have been carried out on modified low-density lipoprotein internalization activity, but there have been few studies on SCARF2. Higher expression of SCARF2 has been found in glioblastoma (GBM) than normal brain tissue. Through analysis of The Cancer Genome Atlas database, it was confirmed that SCARF2 is widely expressed in GBM, and increased SCARF2 expression correlated with a poor prognosis in patients with glioma. The results of this study showed that the expression of SCARF2 is increased in GBM cell lines and patients, suggesting that SCARF2 may be a potential diagnostic marker and therapeutic molecule for cancers including glioma.

Medicinal plants play an important role in the management of various diseases, so their use has become widespread. However, in some cases the population uses plant species regardless of the toxicity they may possess. The objective of this study was to evaluate the acute toxicity of aqueous extract from the leaves of Ambrosia arborescens Mill. on the biochemical and histopathological parameters of albino Holtzman rats. To do this, the leaves of A. arborescens were collected in the province of Julcan, La Libertad Region-Peru. OECD (Organisation for Economic Cooperation and Development) guideline 423 was conducted, forming experimental groups of 10 animals each one (5 males and 5 females): Group I (Control), which received 2 mL physiological saline solution (SSF 0.9%), Groups II and III (A. arborescens-300 and A. arborescens-2000), which were given the aqueous extract leaves of A. arborescens in a single dose of 300 and 2000 mg/kg/day, respectively. On the 14th day of exposure, biochemical (creatinine, ALT and AST) and histopathological parameters were measured. The results show that the aqueous extract of A. arborescens at the dose of 2000 mg/kg produces an increase in biochemical parameters which is related to histopathological analysis of liver and renal tissue with mild congestion. The study concludes that the aqueous extract leaves of A. arborescens has a LD50 greater than 2000 mg/kg and produces mild congestion in kidneys and liver, but showed no significant toxicological changes in the other albino Holtzman rats organs.