Respiratory Toxicity Research Articles

Delayed immune-related adverse events profile associated with immune checkpoint inhibitors: a real-world analysis

BackgroundImmune-related adverse events (irAEs) typically occur within 3 months of initiating immune-checkpoint inhibitors (ICIs), which has been extensively documented. But the clinical profiles of late-onset irAEs remain inadequately characterized. Therefore, this study aims to quantify the correlation between delayed irAEs and ICIs, and to delineate the profiles of delayed toxicities associated with ICIs using data from the Food and Drug Administration Adverse Event Reporting System (FAERS).MethodsData from the January 2011 to December 2023 in FAERS database were extracted. Four signal detection indices, reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN) and multi-item gamma Poisson shrinker (MGPS), were employed to evaluate the associations between ICIs and delayed irAEs.ResultsA total of 147,854 cases were included in this study, of which 3,738 cases related to delayed irAEs were identified. Generally, 8 signals at System Organ Class (SOC) level were found to be associated with ICIs. Males had a slightly higher reporting frequencies for respiratory disorders (ROR975 = 0.95) and blood and lymphatic system disorders (ROR025 = 1.22), but lower reporting frequencies for immune system disorders (ROR025 = 1.16). Three monotherapy (anti-PD-1, anti-PD-L1 and anti-CTLA-4) were all associated with significant increasing gastrointestinal disorders (ROR025 = 1.66, 1.16, 1.99) and metabolism disorders (ROR025 = 2.26, 1.74, 3.13). Anti-PD-1 therapy exhibited higher rates of respiratory toxicities (ROR025 = 1.46 versus 0.82) and skin toxicities (ROR025 = 1.27 versus 0.94) compared with anti-CTLA-4 therapy. At PT levels, pneumonitis (ROR025: from 11.85 to 29.27) and colitis (ROR025: from 2.11 to 24.84) were the most notable PT signals associated with all three ICI regimens. For outcomes of delayed irAEs, gastrointestinal disorders showed the highest proportion (51.06%) of death.ConclusionOur pharmacovigilance analysis indicates that a small percentage of patients receiving ICIs therapy experience delayed irAEs, which are challenging to manage and may result in severe consequences. Prompt identification and intervention of these delayed irAEs are crucial in clinical practice.

RIFM fragrance ingredient safety assessment, 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone, CAS Registry number 61315-75-1

The existing information supports the use of this material as described in this safety assessment.4-(4-Methyl-3-penten-1-yl)-2(5H)-furanone was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, photoirritation/photoallergenicity, skin sensitization, and environmental safety. Data show that 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone is not mutagenic. The clastogenicity endpoint was evaluated using the Threshold of Toxicological Concern (TTC) for the genotoxicity endpoint material, and the exposure to 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone is below the TTC (0.0025 μg/kg/day). The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the TTC for a Cramer Class III material, and the exposure to 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone is below the TTC (0.0015 mg/kg/day, 0.0015 mg/kg/day, and 0.47 mg/day, respectively). The skin sensitization endpoint was completed using the Dermal Sensitization Threshold (DST) for reactive materials (64 μg/cm2); exposure is below the DST. The photoirritation/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone is not expected to be photoirritating/photoallergenic. The environmental endpoints were evaluated; for the hazard assessment based on the screening data, 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone is not Persistent, Bioaccumulative, and Toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards. For the risk assessment, 4-(4-methyl-3-penten-1-yl)-2(5H)-furanone was not able to be risk screened as there were no reported volumes of use (VoU) for either North America or Europe in the 2019 IFRA Survey.

Integrated respiratory toxicity of municipal wastewater to human bronchial epithelial cells and 3D bronchospheres

Respiratory symptoms have been reported in wastewater treatment workers and residents living close to sewage treatment plant. However, toxicological research about the respiratory hazards of municipal wastewater is scarce. The present study aims to gain insight into the comprehensive respiratory hazards induced by the contaminant mixtures in municipal wastewater. The integrated respiratory hazards of effluents from four secondary wastewater treatment plants (SWTPs), a tertiary wastewater treatment plant (TTP), and a constructed wetland (CW) were evaluated using normal human bronchial epithelial cells (NHBE) bioassay, and toxicity reduction efficiency of various treatment techniques was analyzed. Effluents caused cytotoxicity, oxidative damage, inflammation response with the increased levels of IL-6 and CXCL8, and impaired barrier integrity with decreased expressions of ZO-1 and occludin in NHBE. Further, the effluents inhibited the development of 3D bronchospheres, increased irregular surface and cell debris, and suppressed the formation of luminal structures. TTP E effluent significantly increased the expression of MUC5AC in bronchospheres. The integrated biomarker response (IBR) of the influent was removed by 40.2% at SWTPs, 18.2% at TTP, and 36.6% at CW, respectively. The IBR of the final effluents from SWTPs, TTP, and CW were 7.2, 7.7, and 7.7, respectively. Significant correlation with toxicity biomarkers was frequently observed for stearyl alcohol, o-cresol, phenanthrene, butylated hydroxytoluene, and dimethyl phthalate. The present study provided human relevant evidence concerning the adverse respiratory effects associated with discharge. The necessity for deep water treatment, performance optimization, and the potential means were suggested for improving water quality and protecting respiratory health.

Environmentally Persistent Free Radicals stimulate CYP2E1-mediated generation of reactive oxygen species at the expense of substrate metabolism.

Environmentally persistent free radicals (EPFRs) are a recently recognized component of particulate matter that cause respiratory and cardiovascular toxicity. The mechanism of EPFR toxicity appears to be related to their ability to generate reactive oxygen species (ROS), causing oxidative damage. EPFRs were shown to affect P450 function, inducing the expression of some forms through the Ah receptor. However, another characteristic of EPFRs lies in their ability to inhibit P450 activities. CYP2E1 is one of the P450s that is inhibited by EPFR (MCP230) exposure. As CYP2E1 is also known to generate ROS, it is important to understand the ability of EPFRs to influence the function of this enzyme and to identify the mechanisms involved. CYP2E1 was shown to be inhibited by EPFRs, and to a lesser extent by non-EPFR particles. As EPFR-mediated inhibition was more robust at subsaturating NADPH-cytochrome P450 reductase (POR) concentrations, disruption of POR·CYP2E1 complex formation and electron transfer were examined. Surprisingly, neither complex formation nor electron transfer between POR and CYP2E1 were inhibited by EPFRs. Examination of ROS production showed that MCP230 generated a greater amount of ROS than the non-EPFR CuO-Si. When a POR/CYP2E1-containing reconstituted system was added to the pollutant-particle systems there was a synergistic stimulation of ROS production. The results indicate that EPFRs cause inhibition of CYP2E1-mediated substrate metabolism, yet do not alter electron transfer and actually stimulate ROS generation. Taken together, the results are consistent with EPFRs affecting CYP2E1 function by inhibiting substrate metabolism and increasing the generation of ROS. Significance Statement Environmentally persistent free radicals affect CYP2E1 function by inhibition of monooxygenase activity. This inhibition is not due to disruption of the POR·CYP2E1 complex or inhibition of electron transfer, but due to uncoupling of NADPH and oxygen consumption from substrate metabolism to the generation of ROS. These results show that EPFRs block the metabolism of foreign compounds, and also synergistically stimulate the formation of reactive oxygen species that lead to oxidative damage within the organism.

Can switching from cigarettes to heated tobacco products reduce consequences of pulmonary infection?

While tobacco industry data suggests that switching from combustible cigarettes to heated tobacco products (HTPs), like IQOS, may reduce the users' exposure to respiratory toxicants, it is not known if using HTPs impacts the outcomes of acute respiratory infections. Does switching from cigarettes to HTPs improve responses to pulmonary infection. We conducted experiments in which 3 groups of mice were pre-exposed to cigarette smoke for 8 weeks, followed by 8-week exposure to (1) HTPs (tobacco product switching), (2) air (smoking cessation), or (3) continued exposure to cigarette smoke. Pulmonary bacterial clearance and surrogate markers of lung damage were assessed as study outcomes. Significantly compromised clearance of bacteria from the lungs post-acute challenge occurred in both the switching group and in mice continuously exposed to cigarette smoke. Bacterial clearance, inflammatory T-cell infiltration into the lungs, and albumin leak improved at 12h post-acute challenge in the switching group compared to mice continuously exposed to cigarette smoke. Bacterial clearance, total lung immune-cell infiltration, inflammatory T-cell infiltration into the lungs, the content of total proteins in the BAL, and albumin leak measured post-acute challenge were compromised in the switching group compared to mice in the cessation group. Switching from cigarettes to HTPs did not improve lung myeloperoxidase and neutrophil elastase levels (markers for lung inflammation and damage), which, however, were significantly reduced in the cessation group. This study reveals only a modest improvement in respiratory infection outcomes after switching exposure from cigarettes to HTPs and significantly compromised outcomes compared to a complete cessation of exposure to all tobacco products.

Minimum information for reporting on the TEER (trans-epithelial/endothelial electrical resistance) assay (MIRTA).

Standard information reporting helps to ensure that assay conditions and data are consistently reported and to facilitate inter-laboratory comparisons. Here, we present recommendations on minimum information for reporting on the TEER (trans-epithelial/endothelial electrical resistance) assay (MIRTA). The TEER assay is extensively used to evaluate the health of an epithelial/endothelial cell culture model and as an indicator of the potential toxicity of a test substance. This publication is the result of an international collaboration─called the RespTox (Respiratory Toxicity) Collaborative─through which twelve laboratories shared their protocols for assessing the barrier function of respiratory epithelial cells using the TEER assay following exposure to substances. The protocols from each laboratory were reviewed to identify general steps for performing the TEER assay, interlaboratory differences between steps, the rationale for differences, whether these differences impact results or cross-laboratory comparisons between TEER measurements. While the MIRTA recommendations are focused on respiratory epithelial cell systems, these recommendations can be adapted for other cell systems that form barriers. The use of these recommendations will support data transparency and reproducibility, reduce challenges in data interpretation, enable cross-laboratory comparisons, help assess study quality, and facilitate the incorporation of the TEER assay into national and international testing guidance.

Liquid metal-embedded magnetic hydrogel beads as novel adsorbents for malachite green removal

Malachite green (MG) is widely used in aquaculture as a parasiticide. It has generated much concern due to its carcinogenesis, mutagenesis, chromosomal fractures, teratogenicity, and respiratory toxicity. Effective methods for removing MG from water or other media are highly needed. Here, liquid metal (LM) is embedded into the magnetic hydrogel to create magnetic LM hydrogel beads with high adsorption capacity. The morphology and physical properties of the LM-embedded magnetic hydrogel beads are characterized using scanning electron microscopy, optical microscopy, and texture analysis methods. The adsorption efficiency of malachite green was assessed using spectrophotometric analysis at a wavelength of 623 nm. The hardness of these hydrogel beads reached a maximum of 4610 g, and its adsorption capacity reached 10 mg/g. Under the optimal condition, 0.05 %wt LM embedded magnetic hydrogel could remove 100 % of MG. This highly efficient magnetic adsorbent for dye removal has considerable potential for rapidly separating toxic contaminants from aquatic animal tissues, providing a cost-effective and straightforward solution to reduce dye pollution in aquatic environments and food products.

Sodium dodecyl sulfate rearranges the conformation of transferrin and attenuates its iron-binding capacity

Sodium dodecyl sulfate (SDS), an anionic surfactant used in many cleaning and hygiene products, is known for its dermal and respiratory toxicity. However, how this surfactant influences the iron dynamics within the body and the mechanism is unknown. We explored the interaction between SDS and human transferrin (HTF), focusing on the effects on iron-binding capacity and structural changes. Results revealed that SDS exposure led to a significant release of iron from HTF in a dose-dependent manner, changing its structure and reducing the iron-binding ability. Spectroscopic analyses showed that the protein secondary structure and skeleton, as well as the micro-environment of aromatic amino acids of HTF, were destroyed after SDS binding. Isothermal titration calorimetry (ITC) results (ΔG, ΔS, and ΔH were −40.1 kcal·mol−1, 0.16 kcal·mol−1·K-1, and 10.1 kcal·mol−1, respectively) indicated a spontaneous and hydrophobic interaction with one strong binding site. Molecular docking identified the preferred binding sites, emphasizing hydrophobic forces (with the hydrophobic tail) and hydrogen bonds (with the hydrophilic head) as the primary driving forces, which aligns with the ITC results. Overall, this comprehensive analysis sheds light on the intricate interplay between SDS and HTF, providing insights into potential health risks associated with SDS exposure.

P01-37 The INSPIRE Initiative: using in vitro systems to predict respiratory toxicity of surfactants by pipetting and aerosol exposure

P01-37 The INSPIRE Initiative: using in vitro systems to predict respiratory toxicity of surfactants by pipetting and aerosol exposure

Detection of 6-PPD and 6-PPDQ in airborne particulates and assessment of their toxicity in lung cells

The extensive use of synthetic antioxidants, notably N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6-PPD), in rubber-related products, particularly in tire manufacturing, has induced concerns regarding their environmental impact and potential health hazards. Despite the identification of 6-PPD and its derivative, 6-PPD quinone (6-PPDQ), in various water samples and their lethal effects on certain aquatic species (e.g., coho salmon, rainbow trout and brook trout), the levels of airborne 6-PPD/6-PPDQ and their respiratory toxicity remain relatively unexplored. In this study, we aimed to evaluate the respiratory toxicity potential of 6-PPD and its derivatives, with a specific focus on detecting these compounds in airborne particulates and assessing their toxic effects on lung cells. Characterization of four airborne fine particulate (FP) samples revealed spherical morphologies with diameters ranging from 17.7 to 225.7 nm, displaying slight agglomeration and negative surface charge. methanol/acetonitrile extraction followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis confirmed the presence of both 6-PPD and 6-PPDQ on the surfaces of FPs, with significant variations (0.26–1.05 μg g−1) in loading capacity observed among the samples. Subsequent exposure of lung cells (THP-1, BEAS-2B, and A549) to 6-PPD and 6-PPDQ revealed dose-dependent declines in mitochondrial metabolic activity induced by 6-PPD, along with severe membrane damage, ATP depletion, and pro-inflammatory cytokine release. Conversely, 6-PPDQ exhibited negligible toxicity in all tested parameters. These findings underscore the potential health risks associated with airborne 6-PPD exposure and emphasize the importance of further research into the respiratory toxicity of 6-PPD derivatives.

Update to RIFM fragrance ingredient safety assessment, 2-methyl-4-phenylbutyraldehyde, CAS Registry Number 40654-82-8

The existing information supports the use of this material as described in this safety assessment.2-Methyl-4-phenylbutyraldehyde was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, photoirritation/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog β-methyl-benzenepentanal (CAS # 55,066-49-4) show that 2-methyl-4-phenylbutyraldehyde is not expected to be genotoxic and provide a calculated Margin of Exposure (MOE) > 100 for the repeated dose toxicity endpoint. Data on read-across analog phenylacetaldehyde (CAS # 122-78-1) provide a calculated MOE >100 for the reproductive toxicity endpoint. Data show that there are no safety concerns for 2-methyl-4-phenylbutyraldehyde for skin sensitization under the current declared levels of use. The photoirritation/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; 2-methyl-4-phenylbutyraldehyde is not expected to be photoirritating/photoallergenic. The local respiratory toxicity endpoint was evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class I material, and the exposure to 2-methyl-4-phenylbutyraldehyde is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; 2-methyl-4-phenylbutyraldehyde was found not to be Persistent, Bioaccumulative, and Toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use (VoU) in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

Molecular docking of sterol derivatives in Tagetes erecta Linn. as an antiatherosclerotic agents through activation of PPARγ and LXRα receptors

Atherosclerosis is a condition characterized by inflammation in the arteries, which is linked with the accumulation of lipids and alterations in metabolism. Considering that atherosclerosis is the main factor causing death in the world, it is necessary to carry out immediate prevention and treatment to reduce the risk of developing clinical severity. The creation of foam cells, which originate from macrophages, is considered a key element in cardiovascular ailments, particularly in the advancement of atherosclerosis. Two types of the nuclear receptors known as Peroxisome proliferator-activated receptor γ (PPARγ) and liver X receptor α (LXRα), which serve as a primary regulator of cholesterol, intracellular lipid homeostasis and they are instrumental in the process of reverse cholesterol transport (RCT). Activation of these receptors could potentially decrease foam cell formation, consequently lowering the risk of atherogenesis and reducing cardiovascular disease risk. This research aims to determine sterol derivative compounds in Tagetes erecta Linn. which have the best interaction and potential as anti-atherosclerosis through peroxisome proliferator-activated receptor γ (PPARγ) and liver X receptor α (LXRα) activation. The analysis of this study is using docking molecular analysis. The parameters observed in this study were docking score, visualization results, absorption, distribution, metabolism, excretion profile, and toxicity value. The molecular docking outcomes indicate that β-sitosterol and 7β-hydroxysitosterol possess the most favorable binding energy values. They exhibit a positive pharmacokinetic profile, with the exception of gastrointestinal absorption and respiratory toxicity.

Evaluation of Respiratory Toxicity Potential of Acrylamide in Zebrafish: Oxidative Stress Parameters, mRNAs Expression, and Histomorphological Changes in Gills

Evaluation of Respiratory Toxicity Potential of Acrylamide in Zebrafish: Oxidative Stress Parameters, mRNAs Expression, and Histomorphological Changes in Gills

In Silico Toxicological Analysis of Active Compounds Present in Selected Pesticides Sold in South-West Nigeria

Introduction: The study investigated the molecular effects of human exposure to commonly used pesticides in Nigeria. Methods: Utilizing computational methods like clustering analysis, toxicokinetic predictions, molecular docking, and molecular dynamic (MD) simulation, various health impacts were identified. Results and Discussion: The results revealed significant gastrointestinal absorption, P-glycoprotein bypass, blood-brain barrier penetration, and cytochrome P450 inhibition for certain pesticide agents. Notably, oxathiapiprolin showed hepatotoxicity, propanil exhibited drug-induced liver injury (DILI), and 2,4-dichloro-phenoxyacetic acid demonstrated carcinogenicity. Respiratory toxicity was predicted for most pesticides, except propanil and N-(2,6-diethylphenyl) acetamide. Molecular targets were identified, such as bifenthrin targeting programmed cell death 1 ligand 1 and Atrazine targeting potassium voltage-gated channel subfamily H member 3. Binding affinities were computed, with oxathiapiprolin showing -6.526 kcal/mol with short transient receptor potential channel 7. Molecular dynamic simulations indicated significant binding energy changes over time. Atrazine's binding with potassium voltage-gated channel subfamily H member 3 exhibited a total binding energy ΔGbind of -39.410 kcal/mol and -49.135 kcal/mol at 0 ns and 100 ns, respectively. Oxathiapiprolin's binding with short transient receptor potential channel 7 showed ΔGbind of -53.481 kcal/mol and -44.122 kcal/mol at 0 ns and 100 ns. Conclusion: This study suggests potential hepatotoxicity and carcinogenicity of certain pesticides, emphasizing the need for environmental monitoring and stringent regulations to safeguard public health.

Autophagy aggravates multi-walled carbon nanotube-induced ferroptosis by suppressing PGC-1 dependent-mitochondrial biogenesis in lung epithelial cells

Multi-walled carbon nanotube (MWCNT) induced respiratory toxicity has become a growing concern, with ferroptosis emerging as a novel mechanism implicated in various respiratory diseases. However, whether ferroptosis is involved in MWCNT-elicited lung injury and the underlying molecular mechanisms warrant further exploration. In this study, we found that MWCNT-induced ferroptosis is autophagy-dependent, contributing to its cellular toxicity. Inhibiting of autophagy by pharmacological inhibitors 3-MA or ATG5 gene knockdown significantly attenuated MWCNT-induced ferroptosis, concomitant with rescued mitochondrial biogenesis. Rapamycin, the autophagy agonist, exacerbated the mitochondrial damage and MWCNT-induced ferroptosis. Moreover, lentivirus-mediated overexpression of PGC-1α inhibited ferroptosis, while inhibition of PGC-1α aggravated ferroptosis. In summary, our study unveils ferroptosis as a novel mechanism underlying MWCNT-induced respiratory toxicity, with autophagy promoting MWCNT-induced ferroptosis by hindering PGC-1α-dependent mitochondrial biogenesis.

ToxMPNN: A deep learning model for small molecule toxicity prediction.

Machine learning (ML) has shown a great promise in predicting toxicity of small molecules. However, the availability of data for such predictions is often limited. Because of the unsatisfactory performance of models trained on a single toxicity endpoint, we collected toxic small molecules with multiple toxicity endpoints from previous study. The dataset comprises 27 toxic endpoints categorized into seven toxicity classes, namely, carcinogenicity and mutagenicity, acute oral toxicity, respiratory toxicity, irritation and corrosion, cardiotoxicity, CYP450, and endocrine disruption. In addition, a binary classification Common-Toxicity task was added based on the aforementioned dataset. To improve the performance of the models, we added marketed drugs as negative samples. This study presents a toxicity predictive model, ToxMPNN, based on the message passing neural network (MPNN) architecture, aiming to predict the toxicity of small molecules. The results demonstrate that ToxMPNN outperforms other models in capturing toxic features within the molecular structure, resulting in more precise predictions with the ROC_AUC testing score of 0.886 for the Toxicity_drug dataset. Furthermore, it was observed that adding marketed drugs as negative samples not only improves the predictive performance of the binary classification Common-Toxicity task but also enhances the stability of the model prediction. It shows that the graph-based deep learning (DL) algorithms in this study can be used as a trustworthy and effective tool to assess small molecule toxicity in the development of new drugs.

FDA Approved Niraparib-based Virtual Screening and Molecular Docking Studies to Discover Novel 6NRF Protein Modulator for Ovarian Cancer

The abstract summarizes the findings of a comprehensive analysis of chemical compounds, focusing on their potential therapeutic relevance in ovarian cancer treatment. Utilizing data from the ChEMBL database, pharmacophore-based screening identified compounds with promising activity against ovarian cancer, with notable catching scores ranging from 0.556 to 1.000. Crystallographic refinement metrics highlighted improvements in structural accuracy and quality following PDB-REDO refinement, with reductions in R and R-free values and significant enhancements in bond length RMS Z-scores. Molecular docking studies revealed predicted binding affinities ranging from -9.6 to -8.4, indicating strong interactions with target proteins. ADME analysis of niraparib, a lead compound, demonstrated favorable physicochemical properties and pharmacokinetic profiles, with Lipinski, Ghose, Veber, and Egan’s rules for drug-likeness and bioavailability met. Toxicity prediction models identified potential organ toxicity endpoints, with neurotoxicity, respiratory toxicity, and immunotoxicity showing active involvement. These findings underscore the complexity of structure-activity relationships and the importance of predictive models in guiding drug discovery efforts and ensuring safety profiles. Overall, this study provides valuable insights into the landscape of PARP inhibitors and their potential in advancing personalized medicine approaches for ovarian cancer therapy.

Development of UPLC–MS/MS method for the simultaneous quantification of valproic acid and phenytoin in human plasma and application to study pharmacokinetic interaction in epilepsy patients

Valproic acid and phenytoin are two prevalent antiepileptic medications known for their narrow indices and propensity for cardiovascular and respiratory system toxicity. Therefore, therapeutic drug monitoring (TDM) of valproic acid (VAL) and phenytoin (PHE) concentrations in patient plasma is extremely beneficial for improving clinical choices, avoiding adverse reactions, and optimizing treatment for individual patients. In this study, a rapid and sensitive ultra-performance liquid chromatographic tandem mass spectrometer (UPLC-MS/MS) method was developed and validated for the simultaneous quantitative determination of valproic acid (VAL) and phenytoin (PHE) in human plasma. Negative electron spray ionization (ESI-) mode with selective ion recording (SIR) was employed to determine the transitions of m/z 142.98 and m/z 250.93 for VAL and PHE, respectively. The internal standard (IS) betamethasone (BETA) was ionized using positive electron spray ionization (ESI+) and detected by multi-reaction monitoring (MRM) mode to obtain precursor ions and specific fragment ions for quantification, and the MRM transition was chosen to be m/z 393.17 → 355.16. The separation was performed using a Phenomenex Synergi Hydro-RP (4 μm, 250 × 4.6 mm, I.D.) with an isocratic mobile phase consisting of acetonitrile – water (75:25, v/v) at a flow rate of 0.8 mL/min. The column temperature was maintained at 25 °C. The lower limit of quantification of VAL and PHE was 3.6 μg/mL and 0.72 μg/mL, respectively, which resulted in a recovery of more than 85 % for most analytes. According to US-FDA bioanalytical technique validation, the specificity, intra- and inter-day precision and accuracy, matrix effect, carryover, dilution, and stability of all analytes were within acceptable ranges. This analytical method was successful in evaluating the levels of valproic acid and phenytoin in human plasma from epileptic patients.

Repeat treatment of organotypic airway cultures with ethyl methanesulfonate causes accumulation of somatic cell mutations without expansion of bronchial-carcinoma-specific cancer driver mutations

The human in vitro organotypic air-liquid-interface (ALI) airway tissue model is structurally and functionally similar to the human large airway epithelium and, as a result, is being used increasingly for studying the toxicity of inhaled substances. Our previous research demonstrated that DNA damage and mutagenesis can be detected in human airway tissue models under conditions used to assess general and respiratory toxicity endpoints. Expanding upon our previous proof-of-principle study, human airway epithelial tissue models were treated with 6.25–100 µg/mL ethyl methanesulfonate (EMS) for 28 days, followed by a 28-day recovery period. Mutagenesis was evaluated by Duplex Sequencing (DS), and clonal expansion of bronchial-cancer-specific cancer-driver mutations (CDMs) was investigated by CarcSeq to determine if both mutation-based endpoints can be assessed in the same system. Additionally, DNA damage and tissue-specific responses were analyzed during the treatment and following the recovery period. EMS exposure led to time-dependent increases in mutagenesis over the 28-day treatment period, without expansion of clones containing CDMs; the mutation frequencies remained elevated following the recovery. EMS also produced an increase in DNA damage measured by the CometChip and MultiFlow assays and the elevated levels of DNA damage were reduced (but not eliminated) following the recovery period. Cytotoxicity and most tissue-function changes induced by EMS treatment recovered to control levels, the exception being reduced proliferating cell frequency. Our results indicate that general, respiratory-tissue-specific and genotoxicity endpoints increased with repeat EMS dosing; expansion of CDM clones, however, was not detected using this repeat treatment protocol. DisclaimerThis article reflects the views of its authors and does not necessarily reflect those of the U.S. Food and Drug Administration. Any mention of commercial products is for clarification only and is not intended as approval, endorsement, or recommendation.

Metabolite analysis of 14C-labeled chloromethylisothiazolinone/methylisothiazolinone for toxicological consideration of inhaled isothiazolinone biocides in lungs

5-Chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT) used as preservatives in various products, including humidifier disinfectants, presents substantial health hazards. This research delves into the toxicological assessments of CMIT/MIT in the respiratory system using animal models. Through the synthesis of radiolabeled [14C]CMIT and [14C]MIT, we investigated the biological uptake and in vivo behaviors of CMIT/MIT in the respiratory tissues following intratracheal exposure. Quantitative whole-body autoradiography (QWBA) revealed significant persistence of CMIT/MIT in lung tissue. In addition, radio high-performance liquid chromatography (radio-HPLC) with tandem mass spectrometry (LC-MS/MS) was employed for metabolite profiling and identification. Notably, around 28% of the radiolabel was retained in tissue after the extraction step, suggesting covalent binding of CMIT/MIT and their metabolites with pulmonary biomolecules. This observation demonstrates the propensity of the electrophilic isothiazolinone ring in CMIT/MIT to undergo chemical interactions with biothiols in proteins and enzymes, fostering irreversible alterations of biomolecules. Such accumulations of transformations could result in direct toxicity at both cellular and organ levels. Additionally, the detection of metabolites, including a MIT dimer conjugated with glutathione (GSH), as analyzed by mass spectrometry indicates the possible reduction of cellular GSH levels and subsequent oxidative stress. This investigation offers an in-depth insight into the toxic mechanisms of CMIT/MIT, underlying their capability to engage in complex formations with biomacromolecules and induce pronounced respiratory toxicity. These results highlight the imperative for stringent safety assessments of these chemicals, advocating for improved public health and safety measures in the use of chemicals.