Mitochondrial DNA alterations in blood of the humans exposed to N,N-dimethylformamide

Ligand-field-controlled catalysis: Enzymatic hydrolysis of N, N-dimethylformamide

N, N-dimethylformamide (DMF) is a widely used polar aprotic solvent as well as a troublesome toxic pollutant, removal of which has attracted increasing attention. Certain organisms encode N, N-dimethylformamidase (DMFase) to metabolize DMF. In the present work, molecular dynamics and quantum mechanics/molecular mechanics were adopted to explore the mechanism of DMF in DMFase. The calculations show that the structure that N atom of DMF coordinated with Fe3+ is the preferred initial conformation (N-pathway), compared with the structure in which O atom coordinated with Fe3+ (O-pathway). In the N-pathway, the coordination of N and Fe3+ disables the conjugation effect of the amide bond in the substrate and ligand field is highly flexible. By contrast, the conjugated structure of DMF is maintained well in the O-pathway, and ligand field is highly rigid with conserved electronic states during the water attack step. These two factors lead to the higher energy barrier in the O-pathway, while N-pathway is the preferred mechanism for DMF degradation. In addition, we displayed that Glu657 is involved in the catalytic process as a proton transfer mediator. Our work sheds light on the metabolic mechanism of DMF in DMFase, revealing the important role of ligand field in the catalytic process.

Treatment of cosmetic wastewater containing N, N-dimethylformamide and high concentration of chloride salt by chemical precipitation and electrochemical method

High-strength wastewater containing elevated levels of chloride salt and N, N-dimethylformamide (DMF) solvent was collected from manufacturing of sunscreen cream (for UVA/UVB protection) at a cosmetic factory. In evaporation process, precipitates, formed due to the high chloride content (around 160 g/L), clog the pipeline, seriously reducing the treatment efficiency. This study aimed to develop a two-stage process integrating chemical precipitation and electrochemical oxidation to specifically remove the concentrated chloride salt and organic compounds (COD >100 g/L). Chloride ions were initially recovered as insoluble Friedel's salt using calcium hydroxide (Ca(OH)2) and sodium aluminate (NaAlO2) as the precipitants. The [Cl]/[Ca]/[Al] ratio and solution pH were optimized to obtain a pure crystallized phase of Ca2AlCl(OH)6•2H2O. Afterwards, the organic compound were treated by a Fered-Fenton with the addition of H2O2 and FeSO4 to degrade the remaining COD. The cost and energy consumption of this integrated processes were evaluated, compared to the conventional evaporation method.

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.

Human Biomonitoring Initiative (HBM4EU): Human Biomonitoring Guidance Values Derived for Dimethylformamide

Within the European Joint Program on Human Biomonitoring HBM4EU, human biomonitoring guidance values (HBM-GVs) for the general population (HBM-GV_GenPop) or for occupationally exposed adults (HBM-GV_Worker) are derived for prioritized substances including dimethylformamide (DMF). The methodology to derive these values that was agreed upon within the HBM4EU project was applied. A large database on DMF exposure from studies conducted at workplaces provided dose–response relationships between biomarker concentrations and health effects. The hepatotoxicity of DMF has been identified as having the most sensitive effect, with increased liver enzyme concentrations serving as biomarkers of the effect. Out of the available biomarkers of DMF exposure studied in this paper, the following were selected to derive HBM-GV_Worker: total N-methylformamide (tNMF) (sum of N-hydroxymethyl-N-methylformamide and NMF) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine. The proposed HBM-GV_Worker is 10 mg·L⁻¹ or 10 mg·g⁻¹ creatinine for both biomarkers. Due to their different half-lives, tNMF (representative of the exposure of the day) and AMCC (representative of the preceding days’ exposure) are complementary for the biological monitoring of workers exposed to DMF. The levels of confidence for these HBM-GV_Worker are set to “high” for tNMF and “medium-low” for AMCC. Therefore, further investigations are required for the consolidation of the health-based HBM-GV for AMCC in urine.

Effect of dimethylformamide on sperm quality and fertilizing ability of Indian red jungle fowl (Gallus gallus murghi)

The present study investigates the efficacy of dimehtlyformamide (DMF) as a permeable cryoprotectant and its effect on quality and fertility of Indian red jungle fowl sperm. Semen was collected from eight mature roosters, pooled, divided into five aliquots and diluted with red fowl extender having DMF (0%, 4%, 6%, 8% and 10%). Diluted semen samples were cooled from 37 °C to 4 °C, 20% glycerol added to control (0% DMF), equilibrated for 10 min and filled in 0.5 mL French straws, kept over liquid nitrogen vapors for 10 min and plunged into liquid nitrogen. Sperm motility, plasma membrane functionality, viability and acrosome integrity were assessed at post dilution, cooling, equilibration and freeze-thawing stage of cryopreservation. Cryopreservation stages had negative effects (P < 0.05) on semen quality parameters. Percentages of sperm motility, plasma membrane functionality, viability and acrosome integrity were recorded highest in extender having 8% DMF at post-dilution, cooling, equilibration and freeze-thawing stage. Fertility results after artificial insemination were recorded higher (P < 0.05) with 8% DMF compared to 20% glycerol. Dimehtlyformamide (8%) in red fowl extender improves the post thaw semen quality and fertility in Indian red jungle fowl and can be used effectively to avoid the contraceptive effects of glycerol.

Bio-Engineered Graphene-Based Cage for Efficient Local Enrichment and Biodegradation of Aqueous Organic Wastes

Microorganism immobilization has attracted great attention as a traditional method to overcome aqueous organic wastes containing N, N-dimethylformamide (DMF). In this approach, graphene oxide was modified with functional polymer firstly to obtain micro-composites material (PGO), and then the prepared composites were deposited on the surface of copper mesh (CM) to block the meshes and CM@PGO was achieved. Moreover, cage-shaped model was designed based on CM@PGO and P. denitrificans was packed inside the cage for batch experiments. This strategy could enrich the local concentration of DMF due to the formation of hydrogen bonds with the oxygen-containing groups from PGO and the character of bacteria in captivity could also contribute to the process of degradation. Results showed that the approach could remove DMF more efficiently about 15% compared with free microorganism and presented excellent cycling performance. Meantime, physical adsorption and chemical adsorption were both contributed to the process of PGO adsorption, and the adsorption isotherm fits Langmuir model well, furthermore, the theoretical maximum of adsorption ability calculated through Langmuir model is 95 mg/g. In other words, this cage-shaped CM@PGO provided a facile platform for treating various wastewaters by altering the species of packed microorganisms, which exhibited considerable prospects for wastewater treatment.

Draft Genome Sequence of a Pseudomonas aeruginosa Strain Able To Decompose N , N -Dimethyl Formamide

Pseudomonas aeruginosa is a Gram-negative bacterium, which uses a variety of organic chemicals as carbon sources. Here, we report the genome sequence of the Cu1510 isolate from wastewater containing a high concentration of N,N-dimethyl formamide.

Efficient simultaneous adsorption-biodegradation of high-concentrated N,N-dimethylformamide from water by Paracoccus denitrificans-graphene oxide microcomposites

Water contamination becomes one of the most pervasive environmental issues all over the world in recent years. In this paper, the functionalization of graphene oxide (GO) with copolymers containing methacrylic acid (MAA) and butyl methacrylate (BMA) was investigated to prepare a new microcomposite material (PGO) via free radical solution polymerization. PGO was used for the adsorption of N,N-dimethylformamide (DMF) from aqueous solution by utilizing the characteristics of ultralarge surface and the Van der Waals force between DMF molecules and polymers on the surface of PGO. Besides, PGO was used not only a high-capable adsorbent but also a carrier for the immobilization of Paracoccus denitrificans cells in the treatment of high-concentrated DMF. Bacterial cells could immobilized on the PGO (PGO@P. denitrificans) stably by covalent coupling process after acclimatization and high-concentrated DMF (2000 mg/L) could be removed completely and relatively rapidly from aqueous solutions by the simultaneous adsorption-biodegradation (SAB) process of PGO@P. denitrificans. Furthermore, the excellent recycle performance of PGO@P. denitrificans made the whole process more economical and practical.

A novel chemical/biological combined technique for N, N-dimethylformamide wastewater treatment

N, N-Dimethylformamide (DMF) is a widely used organic solvent whose wastewater is difficult to biodegrade directly. In this paper, a novel chemical/biological combined technique consisting of alkaline hydrolysis stripping, activated sludge and a bio-trickling filter (BTF) was developed for DMF wastewater treatment. The main pollutant, DMF, was decomposed to dimethylamine and formate under alkaline conditions, and the dimethylamine was stripped out by the BTF. The pretreated wastewater was then degraded in an activated sludge process. The operation performances of alkaline hydrolysis, activated sludge and BTF processes were investigated separately. At the optimal conditions of an alkali dosage of 40 g/L, an air/liquid ratio of 3000:1 and 5 h in the air-stripping process, the removal of total organic carbon and DMF was found to be 58% and 96%, respectively. A chemical oxygen demand removal efficiency of 80-90% was obtained in the activated sludge process. The performance of BTF was excellent with a dimethylamine removal efficiency close to 90% even at a high loading of 16 g/d.

Risk assessment of N,N-dimethylformamide on residents living near synthetic leather factories

Dimethylformamide (DMF) is a broad solvent used in the production of synthetic leather. Decades of year's research have been focused on workers in leather factories suffering from the release of DMF. However, little attention was paid on general population. Here, we examined the relationship between consistent DMF exposure and annual hospitalizations of local residents in Longwan, China, in 2008. We found a positive correlation with a relative risk (RR) increase of 1.110 for total hospitalizations. When the data were stratified by sex, we observed a higher correlation for female hospitalizations than for male hospitalizations, with RR values of 1.55 and 1.084, respectively. This might be attributed to the differences in genotypes of oxidant enzyme between gender. The significance of the correlations did not disappear after we excluded the extreme value of DMF or adjusted for SO2, NO2, and PM10. Population living near the leather factory has experienced almost constant DMF exposure, and real concern should be raised regarding such exposure. Governments should take responsibility for the protection of not only occupational workers but also residents, especially women.

Effects of N,N-dimethylformamide on behaviour and regeneration of planarian Dugesia japonica

In this study, the toxicity, behavioural and regeneration effects of dimethylformamide (DMF) on planarian Dugesia japonica were investigated. One control and six different concentrations of DMF (10 ppm, 100 ppm, 500 ppm, 1000 ppm, 5000 ppm and 10,000 ppm) were used in triplicate. The results showed that the mortality was directly proportional to the DMF concentration and planarian locomotor velocity (pLMV) was significantly reduced by increasing the exposure time and DMF concentration. pLMV of D. japonica was significantly reduced at a lower concentration of 10 ppm after 7 days of continuous exposure to DMF. The recovery of the motility of planarians pretreated with DMF was found to be time- and dose dependent, all planarians had complete recovery in their motility after 48 h. The appearance of auricles in regenerating animals was easily affected by DMF exposure in comparison with the appearance of eyespot. The present results suggest that the intact adult mobility in the aquatic planarian D. japonica is a more sensitive biomarker than mortality, and the appearance of auricles in regenerating animals is a more sensitive biomarker than eyespot.

Generation of continuous packed bed reactor with PVA-alginate blend immobilized Ochrobactrum sp. DGVK1 cells for effective removal of N,N-dimethylformamide from industrial effluents

Effective removal of dimethylformamide (DMF), the organic solvent found in industrial effluents of textile and pharma industries, was demonstrated by using free and immobilized cells of Ochrobactrum sp. DGVK1, a soil isolate capable of utilizing DMF as a sole source of carbon, nitrogen. The free cells have efficiently removed DMF from culture media and effluents, only when DMF concentration was less than 1% (v/v). Entrapment of cells either in alginate or in polyvinyl alcohol (PVA) failed to increase tolerance limits. However, the cells of Ochrobactrum sp. DGVK1 entrapped in PVA-alginate mixed matrix tolerated higher concentration of DMF (2.5%, v/v) and effectively removed DMF from industrial effluents. As determined through batch fermentation, these immobilized cells have retained viability and degradability for more than 20 cycles. A continuous packed bed reactor, generated by using PVA-alginate beads, efficiently removed DMF from industrial effluents, even in the presence of certain organic solvents frequently found in effluents along with DMF.

Clinical outcomes of occupational exposure to n,n-dimethylformamide: perspectives from experimental toxicology

N,N-Dimethylformamide (DMF) is globally used as an organic solvent in the production of synthetic leather and resins because of its low volatility, making it an attractive industrial material. Despite its excellent property as a chemical solvent, utilization of DMF is somewhat controversial nowadays due to its hazardous effects on exposed workers in work places. Many toxification cases are being reported globally and the number of cases of liver damage is still increasing in developing countries. On account of this, a series of epidemiologic surveys are being conducted to understand the degrees of liver damage caused by DMF exposure. Furthermore, many investigations have been performed to clarify the mechanism of DMF-induced liver toxicity using both human and experimental animal models. This review summarizes the current occupational cases reported on liver damage from workers exposed to DMF in industrial work places and the research results that account for DMF-induced liver failure and possible carcinogenesis. The findings reviewed here show the synergistic toxicity of DMF exposure with other toxicants, which might occur through complicated but distinct mechanisms, which may extend our knowledge for establishing risk assessments of DMF exposure in industrial work places.

Mitochondrial aging is accelerated by anti-retroviral therapy through the clonal expansion of mtDNA mutations

There is emerging evidence that people with successfully treated HIV infection age prematurely, leading to progressive multi-organ disease, but the reasons for this are not known. Here we show that patients treated with commonly used nucleoside analog anti-retroviral drugs progressively accumulate somatic mitochondrial DNA (mtDNA) mutations, mirroring those seen much later in life caused by normal aging. Ultra-deep re-sequencing by synthesis, combined with single-cell analyses, suggests that the increase in somatic mutation is not caused by increased mutagenesis but might instead be caused by accelerated mtDNA turnover. This leads to the clonal expansion of preexisting age-related somatic mtDNA mutations and a biochemical defect that can affect up to 10% of cells. These observations add weight to the role of somatic mtDNA mutations in the aging process and raise the specter of progressive iatrogenic mitochondrial genetic disease emerging over the next decade.

Airborne particulate matter and mitochondrial damage: a cross-sectional study

Oxidative stress generation is a primary mechanism mediating the effects of Particulate Matter (PM) on human health. Although mitochondria are both the major intracellular source and target of oxidative stress, the effect of PM on mitochondria has never been evaluated in exposed individuals.

METHODS

In 63 male healthy steel workers from Brescia, Italy, studied between April and May 2006, we evaluated whether exposure to PM was associated with increased mitochondrial DNA copy number (MtDNAcn), an established marker of mitochondria damage and malfunctioning. Relative MtDNAcn (RMtDNAcn) was determined by real-time PCR in blood DNA obtained on the 1st (time 1) and 4th day (time 2) of the same work week. Individual exposures to PM10, PM1, coarse particles (PM10-PM1) and airborne metal components of PM10 (chromium, lead, arsenic, nickel, manganese) were estimated based on measurements in the 11 work areas and time spent by the study subjects in each area.

RESULTS

RMtDNAcn was higher on the 4th day (mean = 1.31; 95%CI = 1.22 to 1.40) than on the 1st day of the work week (mean = 1.09; 95%CI = 1.00 to 1.17). PM exposure was positively associated with RMtDNAcn on either the 4th (PM10: beta = 0.06, 95%CI = -0.06 to 0.17; PM1: beta = 0.08, 95%CI = -0.08 to 0.23; coarse: beta = 0.06, 95%CI = -0.06 to 0.17) or the 1st day (PM10: beta = 0.18, 95%CI = 0.09 to 0.26; PM1: beta = 0.23, 95%CI = 0.11 to 0.35; coarse: beta = 0.17, 95%CI = 0.09 to 0.26). Metal concentrations were not associated with RMtDNAcn.

CONCLUSIONS

PM exposure is associated with damaged mitochondria, as reflected in increased MtDNAcn. Damaged mitochondria may intensify oxidative-stress production and effects.

Plasmid pAMI2 of Paracoccus aminophilus JCM 7686 carries N,N-dimethylformamide degradation-related genes whose expression is activated by a LuxR family regulator

N,N-Dimethylformamide (DMF), a toxic solvent used in the chemical industry, is frequently present in industrial wastes. Plasmid pAMI2 (18.6 kb) of Paracoccus aminophilus JCM 7686 carries genetic information which is crucial for methylotrophic growth of this bacterium, using DMF as the sole source of carbon and energy. Besides a conserved backbone related to pAgK84 of Agrobacterium radiobacter K84, pAMI2 carries a three-gene cluster coding for the protein DmfR, which has sequence similarities to members of the LuxR family of transcription regulators, and two subunits (DmfA1 and DmfA2) of N,N-dimethylformamidase, an enzyme of high substrate specificity that catalyzes the first step in the degradation of DMF. Genetic analysis revealed that these genes, which are all placed in the same orientation, constitute an inducible operon whose expression is activated in the presence of DMF by the positive transcription regulator DmfR. This operon was used to construct a strain able to degrade DMF at high concentrations that might be used in the biotreatment of DMF-containing industrial wastewaters. To our knowledge, this is the first study to provide insights into the genetic organization and regulation as well as the dissemination in bacteria of genes involved in the enzymatic breakdown of DMF.