Allyl methyl disulfide (AMDS) prevents N,N-dimethyl formamide-induced liver damage by suppressing oxidative stress and NLRP3 inflammasome activation.

N,N-dimethylformamide (DMF), a widely consumed industrial solvent with persistent characteristics, can induce occupational liver damage and pose threats to the general population due to the enormous DMF-containing industrial efflux and emission from indoor facilities. This study was performed to explore the roles of allyl methyl disulfide (AMDS) in liver damage induced by DMF and the underlying mechanisms. AMDS was found to effectively suppress the elevation in the liver weight/body weight ratio and serum aminotransferase activities, and reduce the mortality of mice induced by DMF. In addition, AMDS abrogated DMF-elicited increases in malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels and decreases in glutathione (GSH) levels in mouse livers. The increase in macrophage number, mRNA expression of M1 macrophage biomarkers, and protein expression of key components in the NF-κB pathway and NLRP3 inflammasome induced by DMF exposure were all suppressed by AMDS in mouse livers. Furthermore, AMDS inhibited DMF-induced cell damage and NF-κB activation in cocultured AML12 hepatocytes and J774A.1 macrophages. However, AMDS per se did not significantly affect the protein level and activity of CYP2E1. Collectively, these results demonstrate that AMDS effectively ameliorates DMF-induced acute liver damage possibly by suppressing oxidative stress and inactivating the NF-κB pathway and NLRP3 inflammasome.

N, N-dimethylformamide exposure induced liver abnormal mitophagy by targeting miR-92a-1-5p-BNIP3L pathway in vivo and vitro.

N, N-dimethylformamide (DMF) is a widely existing harmful environmental pollutant from industrial emission which can threat human health for both occupational and general populations. Epidemiological and experimental studies have indicated liver as the primary target organ of DMF. However, the molecular mechanism under DMF-induced hepatoxicity remains unclear. In the present study, we identified that DMF could induce abnormal autophagy flux in cells. We also showed that DMF-induced mitochondrial dysfunction and lethal mitophagy which further leads to autophagic cell death. Next, miRNA microarray analysis identified miR-92a-1-5p as the most down-regulated miRNA upon DMF exposure. Mechanistically, miR-92a-1-5p regulated mitochondrial function and mitophagy by targeting mitochondrial protein BNIP3L. Exogenous miR-92a-1-5p significantly attenuated DMF-induced mitochondrial dysfunction and mitophagy in vitro and in vivo. Our study highlights the mechanistic link between miRNAs and mitophagy under environmental stress, which provided a new clue for the mitochondrial epigenetics mechanism on environmental toxicant-induced hepatoxicity.

Hsa_circ_0005915 promotes N,N-dimethylformamide-induced oxidative stress in HL-7702 cells through NRF2/ARE axis.

N,N-dimethylformamide (DMF) is an organic compound widely used in industrial production processes as a solvent with a low evaporation rate. Excessive exposure to DMF may lead to liver damage. Oxidative stress has been reported as one of the main causes of DMF-induced hepatotoxicity. Several doses of DMF (0, 1, 5, and 10 mM) were used to treat HL-7702 cells for a relatively long period to simulate the actual exposure pattern in occupational settings, and oxidative stress was induced. Previous studies illustrated that circular RNA (circRNA) plays a vital role in sustaining hepatocyte physiological function. To explore whether aberrant circRNA expression is involved in DMF-induced excessive ROS generation and hepatotoxicity, high-throughput transcriptional sequencing was performed to identify the altered circRNA expression profiles in HL-7702 liver cells after treatment with 0, 75, or 150 mM DMF for 48 h. We found that levels of induced oxidative stress were similar to those in the long-term exposure model. Among the altered circRNAs, one circRNA (hsa_circ_0005915) was significantly upregulated after DMF exposure, and it affected DMF-mediated oxidative stress in HL-7702 cells. Further experiments revealed that hsa_circ_0005915 downregulated the expression of nuclear factor erythoid-2-related factor 2 (NRF2) at the post-transcriptional level via promoting the ubiquitination and degradation of NRF2, which led to the increase of ROS accumulation. Further investigation demonstrated that the expression levels of NRF2-regulated antioxidative genes-heme oxygenase 1 (HO1) and NAD(P)H quinone dehydrogenase 1 (NQO1)-indeed declined after the overexpression of hsa_circ_0005915. In vivo study also indicated that DMF exposure can upregulate the expression of mmu_circ_0007941 (homologous circRNA of hsa_circ_0005915) and downregulated Nrf2 and Ho1 proteins. In summary, our results revealed that hsa_circ_0005915 plays an important role in promoting DMF-induced oxidative stress by inhibiting the transcriptional activity of the NRF2/ARE axis, which provides a potential molecular mechanism of DMF-mediated hepatotoxicity.

Integration of proteomics, lipidomics, and metabolomics reveals novel metabolic mechanisms underlying N, N-dimethylformamide induced hepatotoxicity.

N, N-Dimethylformamide (DMF) is a universal organic solvent which widely used in various industries, and a considerable amount of DMF is detected in industrial effluents. Accumulating animal and epidemiological studies have identified liver injury as an early toxic effect of DMF exposure; however, the detailed mechanisms remain poorly understood. In this study, we systematically integrated the quantitative proteomics, lipidomics, and metabolomics data obtained from the primary human hepatocytes exposed to DMF, to depict the complicated biochemical reactions correlated to liver damage. Eventually, we identified 284 deregulated proteins (221 downregulated and 63 upregulated) and 149 deregulated lipids or metabolites (99 downregulated and 50 upregulated) induced by DMF exposure. Further, the integration of the protein-metabolite (lipid) interactions revealed that N-glycan biosynthesis (involved in the endoplasmic reticulum stress and the unfolded protein response), bile acid metabolism (involved in the lipid metabolism and the inflammatory process), and mitochondrial dysfunction and glutathione depletion (both contributed to reactive oxygen species) were the typical biochemical reactions disturbed by DMF exposure. In summary, our study identified the versatile protein, lipid, and metabolite molecules in multiple signaling and metabolic pathways involved in DMF induced liver injury, and provided new insights to elucidate the toxic mechanisms of DMF.

A Case of Autoimmune Hepatitis after Occupational Exposure to N,N-Dimethylformamide.

N,N-dimethylformamide (DMF), a widely used solvent in the chemical industry, is known to induce toxic hepatitis. However, there have been no reported cases of DMF-associated autoimmune hepatitis. A 31-year-old healthy man working at a glove factory since July 2015 had intermittently put his bare hands into a diluted DMF solution for his first 15 days at work. After 2 months, he felt nausea, fatigue, and hand cramping, and a jaundice followed. His laboratory findings showed positive autoantibodies and elevated immunoglobulin G (IgG), and his liver biopsy pathology was typical of autoimmune hepatitis (AIH). Prednisolone and azathioprine therapy began, and he recovered rapidly without adverse events. Though his liver chemistry was normalized, the IgG level remained persistently upper normal range. His 2nd liver biopsy performed in April 2019 showed mild portal activity, and he was well under a low dose immunosuppressive therapy up to April 2020. This case warns of the hazard of occupational exposure to DMF, and clinicians should be aware of DMF-related AIH for timely initiation of immunosuppressive therapy.

Aberrant expression of miRNA-192-5p contributes to N,N-dimethylformamide-induced hepatic apoptosis.

Excessive exposure to N,N-dimethylformamide (DMF) can lead to occupational liver poisoning in workers; however, the underlying mechanism is not fully clarified. The importance of microRNAs (miRNAs) in chemical-induced hepatotoxicity has been demonstrated. To determine whether miRNAs are also involved in DMF-induced hepatotoxicity, we systematically analyzed the miRNA expression profiles in DMF-treated (75 and 150 mm) HL-7702 liver cells and controls by high-throughput sequencing. Among the altered miRNAs, miR-192-5p was the most significantly upregulated in HL-7702 cells after DMF exposure and was involved in DMF-mediated cell apoptosis. By contrast, suppression of miR-192-5p in HL-7702 cells attenuated the apoptosis induced by DMF. Furthermore, the anti-apoptotic gene (NIN1/RPN12 binding protein 1 homolog [NOB1]) was predicted to be a potential miR-192-5p target according to bioinformatics analysis. The direct interaction between miR-192-5p and NOB1 was confirmed by the dual-luciferase activity assay in HEK293FT cells. Overexpression of miR-192-5p efficiently reduced NOB1 mRNA and protein expression in HL-7702 cells. Alteration in NOB1 expression influenced DMF-induced hepatotoxicity by affecting hepatic apoptosis. In addition, the inverse correlation between miR-192-5p expression levels and NOB1 expression was further confirmed in DMF-exposed mouse liver tissue samples. These observations demonstrated that promotion of apoptosis from the suppression of NOB1 by miR-192-5p overexpression was responsible for the DMF-induced hepatotoxicity. This work provides the molecular mechanism at the miRNA level for hepatic apoptosis induced by DMF.

Retinoid X receptor α (RXRα)-mediated erythroid-2-related factor-2 (NRF2) inactivation contributes to N,N-dimethylformamide (DMF)-induced oxidative stress in HL-7702 and HuH6 cells.

N,N-dimethylformamide (DMF) is a colorless industrial solvent that is frequently used for chemical reactions. Epidemiologic studies and clinical case reports have consistently indicated that the main toxic effect after exposure to DMF is hepatotoxicity. Previous studies have suggested that oxidative stress is the pivotal molecular event of DMF-mediated hepatotoxicity; however, its underlying mechanism remains unclear. In this study, we found that DMF (0-150 mM) exposure induced an increase in reactive oxygen species (ROS) levels and inhibited the transcriptional activity of nuclear factor erythroid-2-related factor-2 (NRF2) in a dose-dependent manner. Subsequently, our research revealed that the elevated ROS levels and the decline in NRF2-mediated anti-oxidative response in HL-7702 and HuH6 cells might be due to the DMF-induced accumulation of retinoid X receptor α (RXRα) protein. Further investigation demonstrated that phosphorylation of the RXRα protein, which is mediated by the activation of extracellular signal-regulated kinase (ERK), leads to the inhibition of RXRα protein degradation and in turn the accumulation of RXRα after DMF exposure. These findings provide information that improves our understanding of the role of RXRα in DMF-induced hepatotoxicity.

The essential role of CYP2E1 in metabolism and hepatotoxicity of N,N-dimethylformamide using a novel Cyp2e1 knockout mouse model and a population study.

N,N-Dimethylformamide (DMF) is a widespread contaminant of leather factories and their surrounding environment. There is a lack of direct in vivo evidence supporting CYP2E1 as a primary enzyme responsible for DMF metabolism and hepatotoxicity. In this study, a novel Cyp2e1 knockout (KO) mouse model was generated and used to assess whether DMF metabolism and hepatotoxicity is CYP2E1 dependent using an acute toxicity protocol with a single dose of 1500 mg DMF/kg. An epidemiological study in 698 DMF-exposed workers and 188 non-DMF-exposed controls was conducted to investigate the associations between functional polymorphisms of CYP2E1 (rs6413432/rs2031920) and DMF metabolite (N-methylcarbmoylated-hemoglobin [NMHb]). We successfully established Cyp2e1 KO mice with evidence from DNA sequence analysis, which showed 1-bp insertion at 65 bp (C) site of Cyp2e1 Exon 1. In addition, western blot and in vivo pharmacokinetic study also showed a complete absence of CYP2E1 protein and a 92% and 88% reduction in CYP2E1 activity among males and females, respectively. DMF metabolism as evidenced by increased blood NMHb, and hepatotoxicity as evidenced by elevated liver/body weight ratio, activity of liver enzymes and massive liver necrosis were detected in wild-type (WT) mice but were completely abrogated in KO mice, strongly supporting a CYP2E1-dependent pattern of DMF metabolism and hepatotoxicity. Moreover, variant allele of CYP2E1-rs6413432 was also significantly associated with higher NMHb levels in DMF-exposed workers (P = 0.045). The increase of glucose-regulated protein 94 detected in WT mice but not in KO mice suggested CYP2E1-dependent endoplasmic reticulum stress may be a key mechanism underlying DMF-induced hepatotoxicity.

Relationship between N,N-dimethylformamide exposure, PNPLA3, GCKR, COL13A1 and TM6SF2 genes, and liver injury.

BACKGROUND: Current researches show that N,N-dimethylformamide (DMF) exposure is associated with liver injury, but it is debatable whether PNPLA3, GCKR, COL13A1 and TM6SF2 gene polymorphisms are associated with liver injury. Our objective was to examine the relationship among DMF exposure, PNPLA3 rs738409, GCKR rs780094, COL13A1 rs1227756, TM6SF2 rs58542926 and liver injury. METHODS: The cohort consisted of 461 workers exposed above the DMF threshold limit value (TLV) and 211 exposed below the DMF TLV in China, who were followed for 5 years. The relationship between the measured dose of DMF and the relative risk (RR) of liver injury was also investigated by Poisson analysis. Logistic regression models were used to examine the association between measured dose of DMF, gene locus, and RR for liver injury. All workers had a annual physical examinations were conducted at certified physical examination centers in Taicang CDC, including liver serum transaminase assessment and abdominal ultrasound. Genomic DNA was extracted from peripheral blood leukocytes using a genomic DNA extraction kit. RESULTS: The incidence of liver injury in the above DMF TLV group was significantly higher than in the below DMF TLV group. GCKR rs780094 was associated with liver injury. The interaction among the GCKR rs780094, DMF exposure and liver injury showed no significant association. CONCLUSIONS: Our data indicated that in DMF exposure, GCKR rs780094 may contribute to the risk of liver injury. Our results suggest that GCKR rs780094 is a useful genetic marker to help identify liver injury.

The deleterious effects of N,N-dimethylformamide on liver: A mini-review.

N,N-dimethylformamide (DMF) is a versatile solvent with wide industrial applications. Evidences from animal studies and occupational poisoning cases have clearly demonstrated that DMF exposure can lead to different degrees of liver damage. It is noteworthy that DMF below the threshold limit value (TLV) may also cause liver injury in some sensitive populations. Unfortunately, the underlying mechanisms by which DMF induces hepatotoxicity remain largely unknown, despite considerable attention has been drawn to the hepatotoxic effects of DMF. Although some pilot studies have provided some evidences supporting the involvement of oxidative stress, the disturbance of gut microbiota and calcium homeostasis, etc, the causal roles of these factors on the onset of DMF-induced hepatotoxicity need to be confirmed. This article reviews the current knowledge about the deleterious effects of DMF on the liver.

Study on the potential way of hepatic cytotoxicity of N,N-dimethylformamide.

The intermediate metabolites and redox status imbalance were supported as the two major points for N,N-dimethylformamide (DMF)-induced hepatotoxicity. However, the potential mechanism has not yet been concerned. By applying two inhibitors, this study tried to seek the major role in DMF-induced toxicity on HL7702 cell. We observed that DMF induced cell apoptosis through mitochondrial-dependent and p53 pathway. Inhibition reactive oxygen species by catalase remarkably attenuated the mitochondrial transmembrane potential (MMP), apoptotic proteins, and apoptosis. On the contrary, it reduced the biodegradation rate of DMF by coincubation with CYP2E1 antagonist (DDC) partially reduced late apoptosis. However, the change in MMP, the ratio of Bax to Bcl-xl, and cleaved-caspase 9 was not attenuated by DDC. The pathway in DDC coincubation groups was related to the p53 rather than the mitochondrial pathway. Restoring the redox balance during biodegradation is much more effective than attenuating the metabolite rate of DMF. This study may provide a suitable prevention method to occupational workers.

Mitochondrial morphology and function impaired by dimethyl sulfoxide and dimethyl Formamide.

In this work, the effects of two non-ionic, non-hydroxyl organic solvents, dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) on the morphology and function of isolated rat hepatic mitochondria were investigated and compared. Mitochondrial ultrastructures impaired by DMSO and DMF were clearly observed by transmission electron microscopy. Spectroscopic and polarographic results demonstrated that organic solvents induced mitochondrial swelling, enhanced the permeation to H+/K+, collapsed the potential inner mitochondrial membrane (IMM), and increased the IMM fluidity. Moreover, with organic solvents addition, the outer mitochondrial membrane (OMM) was broken, accompanied with the release of Cytochrome c, which could activate cell apoptosis signaling pathway. The role of DMSO and DMF in enhancing permeation or transient water pore formation in the mitochondrial phospholipid bilayer might be the main reason for the mitochondrial morphology and function impaired. Mitochondrial dysfunctions induced by the two organic solvents were dose-dependent, but the extents varied. Ethanol (EtOH) showed the highest potential damage on the mitochondrial morphology and functions, followed by DMF and DMSO.

[Delayed effect of liver injury and metabolism of dimethylformamide after high exposures in rats].

Objective: To investigate the delayed effect of liver injury and metabolism of dimethylformamide (DMF) after high exposures in rats. Methods: A total of 12 rats were randomly divided into four groups and 3 rats were in each group. Rats in 1d DMF+2 d delayed group were dosed for 1 day and rested for 2 days, and sacrificed at the 4th day. Rats in 3 d DMF group were dosed for 3 days and sacrificed at the 4th day. Rats in 3 d DMF+3 d delayed group were dosed for 3 days and rested for 3 days, and sacrificed at the 7th day. Rats in control group were administrated with water for 3 days, sacrificed at the 7th day. The administrated dose was 1 000 mg/kg (body weight·d) DMF by oral. The daily observation and body weight were recorded during the study period. After the experiment, the blood biochemistry, including alanine aminotransferase (ALT) , aspartate aminotransferase (AST) , lactic dehydrogenase (LDH) , alkaline phosphatase (ALP) , total bilirubin (TBIL) etc. were detected. Liver weight, kidney weight, liver/body ratio, kidney/body ratio and pathologic examination of liver and kidney were investigated. The concentrations of hemoglobin-adduct (NMHb) were detected. Results: During the period of 1~3 d, body weight growth rate of rats in each treated group had no significant difference with control rats. In the 4~6 th day of the period, rats in group 3 became thinner than before, and the body weight was negative growth (-4.22±3.29 g/d) and significant lower than that of control rats (10.33±3.21 g/d, F=30.07, P<0.05) . AST and LDH levels of 3 d DMF group were significant higher than control group (P<0.05) . Liver/body ratio in 3 d DMF+3 d delayed group were significant higher than control group (P<0.05) . The gross inspection showed 1 rat and 3 rats were observed liver injury in 3 d DMF group and 3 d DMF+3 d delayed group, respectively. Histopathological lesions of 1d DMF+2 d delayed group, 3 d DMF group and 3 d DMF+3 d delayed group were mainly spotty necrosis, focal necrosis and large necrosis of liver cells, respectively. Only NMHb level of control group was undetectable. NMHb levels in 3 d DMF+3 d delayed group were significantly higher than 3 d DMF group (F=135.46, P<0.05) . Conclusion: The DMF-induced liver injury and DMF metabolism may be delayed after high DMF exposures in rats.

A Comparative Benchmark Dose Study for N, N-Dimethylformamide Induced Liver Injury in a Chinese Occupational Cohort.

Widespread contamination of N,N-dimethylformamide (DMF) has been identified in the environment of leather industries and their surrounding residential areas. Few studies have assessed the dose-response relationships between internal exposure biomarkers and liver injury in DMF exposed populations. We assessed urinary N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoyl) cysteine (AMCC) and blood N-methylcarbmoylated hemoglobin (NMHb) levels in 698 Chinese DMF-exposed workers and 188 nonDMF- exposed workers using ultraperformance liquid-chromatography tandem mass-spectrometry. Liver injury was defined as having abnormal serum activities of any of the 3 liver enzymes, including alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transpeptidase. Higher liver injury rates were identified in DMF-exposed workers versus nonDMF-exposed workers (9.17% vs 4.26%, P = .029) and in male versus female workers (11.4% vs 3.2%, P < .001). Positive correlations between environmental exposure categories and internal biomarker levels were identified with all 3 biomarkers undetectable in nonDMF-exposed workers. Lower confidence limit of benchmark dose (BMDL) was estimated using the benchmark dose (BMD) method. Within all study subjects, BMDLs of 14.0 mg/l for NMF, 155 mg/l for AMCC, and 93.3 nmol/g for NMHb were estimated based on dose-response relationships between internal levels and liver injury rates. Among male workers, BMDLs of 10.9 mg/l for NMF, 119 mg/l for AMCC, and 97.0 nmol/g for NMHb were estimated. In conclusion, NMF, AMCC, and NMHb are specific and reliable biomarkers and correlate well with DMF-induced hepatotoxicity. NMF correlates the best with liver injury, while NMHb may be the most stable indicator. Males have a greater risk of liver injury than females upon DMF exposure.

Low-Dose N,N-Dimethylformamide Exposure and Liver Injuries in a Cohort of Chinese Leather Industry Workers.

OBJECTIVE: We assessed the risk of liver injuries following low doses of N,N-dimethylformamide (DMF) below threshold limit values (20 mg/m) among leather industry workers and comparison groups. METHODS: A cohort of 429 workers from a leather factory and 466 non-exposed subjects in China were followed for 4 years. Poisson regression and piece-wise linear regression were used to examine the relationship between DMF and liver injury. RESULTS: Workers exposed to a cumulative dose of DMF were significantly more likely than non-exposed workers to develop liver injury. A nonlinear relationship between DMF and liver injury was observed, and a threshold of the cumulative DMF dose for liver injury was 7.30 (mg/m) year. CONCLUSIONS: The findings indicate the importance of taking action to reduce DMF occupational exposure limits for promoting worker health.

Alteration of gut microbial community after N,N-Dimethylformamide exposure.

N,N-Dimethylformamide (DMF), a solvent commonly used in factories, can induce liver toxicities, including hepatitis, fibrosis, cirrhosis and hepatoma. It is well known that the gut microbial community plays a role in the metabolism of many toxic substance and in liver regeneration. However, the effect of DMF on rat gut microbial community is poorly understood. The gut microbiotas in control rats and rats exposed to DMF were characterized by high-throughput sequencing of the bacterial 16S rRNA gene. The levels of biochemical parameters in the serum of rats, including cholesterol, bile acid, alanine aminotransferase (ALT), and aspartate aminotransferase (AST), were evaluated. The weight was lower in the DMF exposure group than in the control group. DMF exposure led to changes in gut microbiotas that were reflected in a decreased abundance of Prevotellaceae, Lactobacillaceae, and increased abundance of S24-7, Baceroidaceae, Rikenellaceae and Peptostreptococcaceae. Compared with control group, the cholesterol level was substantially reduced in the DMF exposure group (p < 0.05), while the concentration of bile acid was significantly increased in the DMF exposure group (p < 0.05). The present data established that the gut microbiotasy were changed after DMF exposure, and it revealed the relationship between DMF and gut microbiotas for the first time.

Genetic Variations in the Promoter of the APE1 Gene Are Associated with DMF-Induced Abnormal Liver Function: A Case-Control Study in a Chinese Population.

Acute or long-term exposure to N,N-dimethylformamide (DMF) can induce abnormal liver function. It is well known that DMF is mainly metabolized in the liver and thereby produces reactive oxygen species (ROS). The base excision repair (BER) pathway is regarded as a very important pathway involved in repairing ROS-induced DNA damage. Several studies have explored the associations between GSTM1, GSTT1, CYP2E1 polymorphisms and DMF-induced abnormal liver function; however, little is known about how common hOGG1, XRCC1 and APE1 polymorphisms and DMF induce abnormal liver function. The purpose of this study was to investigate whether the polymorphisms in the hOGG1 (rs159153 and rs2072668), XRCC1 (rs25487, rs25489, and rs1799782), APE1 (rs1130409 and 1760944) genes in the human BER pathway were associated with the susceptibility to DMF-induced abnormal liver function in a Chinese population. These polymorphisms were genotyped in 123 workers with DMF-induced abnormal liver function and 123 workers with normal liver function. We found that workers with the APE1 rs1760944 TG/GG genotypes had a reduced risk of abnormal liver function, which was more pronounced in the subgroups that were exposed to DMF for <10 years, exposed to ≥10 mg/m³ DMF, never smoked and never drank. In summary, our study supported the hypothesis that the APE1 rs1760944 T > G polymorphism may be associated with DMF-induced abnormal liver function in the Chinese Han population.

Metabolite profiles of rats in repeated dose toxicological studies after oral and inhalative exposure.

The MetaMap(®)-Tox database contains plasma-metabolome and toxicity data of rats obtained from oral administration of 550 reference compounds following a standardized adapted OECD 407 protocol. Here, metabolic profiles for aniline (A), chloroform (CL), ethylbenzene (EB), 2-methoxyethanol (ME), N,N-dimethylformamide (DMF) and tetrahydrofurane (THF), dosed inhalatively for six hours/day, five days a week for 4 weeks were compared to oral dosing performed daily for 4 weeks. To investigate if the oral and inhalative metabolome would be comparable statistical analyses were performed. Best correlations for metabolome changes via both routes of exposure were observed for toxicants that induced profound metabolome changes. e.g. CL and ME. Liver and testes were correctly identified as target organs. In contrast, route of exposure dependent differences in metabolic profiles were noted for low profile strength e.g. female rats dosed inhalatively with A or THF. Taken together, the current investigations demonstrate that plasma metabolome changes are generally comparable for systemic effects after oral and inhalation exposure. Differences may result from kinetics and first pass effects. For compounds inducing only weak changes, the differences between both routes of exposure are visible in the metabolome.

Oxidative stress-related DNA damage and homologous recombination repairing induced by N,N-dimethylformamide.

The intensified anthropogenic release of N,N-dimethylformamide (DMF) has been proven to have hepatotoxic effects. However, the potential mechanism for DMF-induced toxicity has rarely been investigated. Our research implicated that DMF induced a significantly dose-dependent increase in reactive oxygen species (ROS) in HL-7702 human liver cells. Moreover, oxidative stress-related DNA damage, marked as 8-hydroxy-2'-deoxyguanosine, was increased 1.5-fold at 100 mmol l(-1) . The most severe DNA lesion (double-strand break, DSB), measured as the formation of γH2AX foci, was increased at/above 6.4 mmol l(-1) , and approximately 50% of cells underwent DSB at the peak induction. Subsequently, the DNA repair system triggered by molecules of RAD50 and MRE11A induced the homologous recombination (HR) pathway by upregulation of both gene and protein levels of RAD50, RAD51, XRCC2 and XRCC3 at 16 mmol l(-1) and was attenuated at 40 mmol l(-1) . Consequently, cellular death observed at 40 mmol l(-1) was exaggerated compared with exposure at 16 mmol l(-1) . Although the exact mechanism relying on the DMF-induced hepatotoxicity needs further clarification, oxidative stress and DNA damage involved in DSBs partially explain the reason for DMF-induced liver injury. Oxidative stress-induced DNA damage should be first considered during risk assessment on liver-targeted chemicals. Copyright © 2015 John Wiley & Sons, Ltd.

Serum activities of liver enzymes in workers exposed to sub-TLV levels of dimethylformamide.

OBJECTIVES: The aim of this study has been to investigate serum activities of liver enzymes in workers exposed to sub-TLV levels of dimethylformamide (DMF). MATERIAL AND METHODS: Seventy-two workers and 72 healthy controls participated in the study. All subjects underwent complete physical examinations and abdominal ultrasound examination. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and c-glutamyl transpeptidase (c-GT) were determined by an auto-chemistry analyzer. The data of airborne concentrations of DMF was obtained from the local Center of Disease Control and Prevention. The level of urine N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) was measured by means of high-performance liquid chromatography. RESULTS: Time weighted average (TWA) concentration of the DMF in workplace was 18.6 (range: 9.8-36.2) mg/m3. The concentration of the AMCC in workers' urine was 28.32 (range: 1.8-58.6) mg/l and 9 workers' AMCC exceeded the biological exposure index (40 mg/l). Thirty-one workers reported gastrointestinal symptoms (abdominal pain, nausea, anorexia) and 10 workers reported headache, dizziness and/or palpitation in the exposed group. Serum analysis revealed that both the mean of serum activities of liver enzymes (ALT, AST and c-GT) and the percentage of workers with abnormal liver function were significantly higher in the exposed group as compared to the controls. CONCLUSIONS: Dimethylformamide can cause liver damage even if air concentration is in the sub-threshold limit value (sub-TLV) level. The protection of skin contact against the exposure to the DMF might be a critical issue as far as the occupational health is concerned.