Methanol-induced optic neuropathy: a still-present problem.

Methanol-induced optic neuropathy (Me-ION) is a serious condition that may result in long-term or irreversible visual impairment or even blindness secondary to damage and loss of function of the optic nerve and retina. Me-ION shows a tendency to occur as mass poisonings around the world with a clear predilection for poor societies in developing countries. The main mechanism underlying the molecular basis of Me-ION is the inhibition of the mitochondrial oxidative phosphorylation process through the binding of the toxic metabolite of methanol-formic acid-with the key enzyme of this process-cytochrome c oxidase. However, other mechanisms, including damage to the eye tissues by oxidative stress causing the intensification of the oxidative peroxidation process with the formation of cytotoxic compounds, as well as an increase in the synthesis of pro-inflammatory cytokines and influence on the expression of key proteins responsible for maintaining cell homeostasis, also play an important role in the pathogenesis of Me-ION. Histopathological changes in the eye tissues are mainly manifested as the degeneration of axons and glial cells of the optic nerve, often with accompanying damage of the retina that may involve all its layers. Despite the development of therapeutic approaches, persistent visual sequelae are seen in 30-40% of survivors. Thus, Me-ION continues to be an important problem for healthcare systems worldwide.

Effects of methanol and formic acid on CRYB, ALDH2, and ATP5A1 of RGCs.

OBJECTIVE: To explore the toxicity of methanol and its metabolite, formic acid on αB-crystallin(CRYB), aldehyde dehydrogenase (ALDH2), and ATPsynthase (ATP5A1) of rat retinal ganglion cells (RGCs). METHODS: RGCs are cultured in vitro in a toxic environment with 15/30/60 mM methanol or formic acid, respectively. Then, the morphological changes of RGCs and protein and mRNA levels of ALDH2, ATP5A1, and CRYB in rat RGCs were evaluated. RESULTS: 1) Compared to the toxicity of 15 mM formic acid on RGCs, 30 mM of formic acid environment significantly promoted apoptosis, and cell death occurred in the 60-mM formic acid group 24 h later. The toxicity of methanol for inducing apoptosis was not as obvious as formic acid. 2) In the 15-mM group, the level of CRYB protein was down-regulated after stimulating with both methanol and formic acid for 48 h, and ATP5A1 protein level decreased significantly with formic but not methanol. No change in ALDH2 was observed in methanol or formic acid. With a prolonged duration (>7 d) or high concentration (>30 mM) stimulation, cells treated with both methanol and formic acid showed severe apoptosis, rendering it challenging to collect a sufficient number of cells for protein detection. 3) In the 48-h group, no significant effect was detected on the mRNA of CRYB, ATP5A1, and ALDH2 by both 15/30 mM formic acid and 15 mM methanol. Conversely, 30 mM methanol had a significant up-regulation effect on the expression of the three genes, while no significant effect was observed in the 7-d groups. CONCLUSIONS: Formic acid exerted stronger toxicity on CRYB, ATP5A1, and ALDH2 than methanol and played a regulatory role at the translation level, while the effect of methanol is still uncertain, needing additional investigation.

Photochemical degradation of fragrance ingredient benzyl formate in water: Mechanism and toxicity assessment.

Recently, fragrance ingredients have attracted increasing attention due to their imperceptible risks accompanying the comfortable feeling. To understand transformation mechanisms and toxicity evolution of benzyl formate (BF) in environment, its photochemical degradation in water was thoroughly studied herein. Results showed that 83.5% BF was degraded under ultraviolet (UV) irradiation for 30 min. Laser flash photolysis and quenching experiments demonstrated that triplet excited state (3BF*), O2•-, and 1O2 were three main reactive species found during BF photodegradation. Eight degradation intermediates, including benzaldehyde, benzyl alcohol, o-cresol, bibenzyl, benzyl ether, 1,2-diphenylethanol, benzoic acid, and benzylhemiformal, were mainly formed as identified by LC-Q-TOF/MS and GC-MS analyses. Furthermore, the degradation mechanism was explained as the bond cleavage of 3BF* and BF•+, O2•-/1O2 oxidation, eaq- reduction, and •OH addition reactions. Aquatic assessment suggests that except benzyl alcohol, benzoic acid, and benzylhemiformal, all the products were persistent and could result in increased aquatic toxicity compared to original BF. Consequently, these degradation products may cause more toxicity to organisms if they remain accumulated in water environment for a long time.

Safety Assessment of Formic Acid and Sodium Formate as Used in Cosmetics.

Formic acid functions as a fragrance ingredient, preservative, and pH adjuster in cosmetic products, whereas sodium formate functions as a preservative. Because of its acidic properties, formic acid is a dermal and ocular irritant. However, when used as a pH adjuster in cosmetic formulations, formic acid will be neutralized to yield formate salts, for example, sodium formate, thus minimizing safety concerns. Formic acid and sodium formate have been used at concentrations up to 0.2% and 0.34%, respectively, with hair care products accounting for the highest use concentrations of both ingredients. The low use concentrations of these ingredients in leave-on products and uses in rinse-off products minimize concerns relating to skin/ocular irritation or respiratory irritation potential. The Cosmetic Ingredient Review Expert Panel concluded that formic acid and sodium formate are safe in the present practices of use and concentration in cosmetics, when formulated to be nonirritating.

[Caustic necrosis due to topical formic acid 85% (Objectif ZeroVerrue(®))]. / Nécrose caustique sous acide formique à 85 % (Objectif ZeroVerrue(®)).

BACKGROUND: Formic acid 85% constitutes the active substance of a new wart removal agent marketed in France under the name of Objectif ZeroVerrue(®), a product sold over-the-counter for adults and children aged over four years, and on a doctor's recommendation for children aged under four years. Its mechanism of action may involve cellular destruction through dehydration. PATIENTS AND METHODS: Herein we report two cases of cutaneous necrosis following application of formic acid 85%. One case was severe, affecting the extremity of the middle finger and involving the underlying extensor apparatus in a girl aged 3 and a half years. This necrosis required the creation of a pedicled fasciocutaneous flap and temporary arthroereisis. DISCUSSION: The precautions for use set out in the information leaflet for this preparation based on formic acid must be strictly adhered to by patients. In particular, only one application should be made per week, taking care to avoid adjacent skin. It is essential to suspend treatment if the skin is still erythematous after the previous application, and the treated area must not be occluded with bandages. Doctors must be aware of the risk of necrosis, since their recommendation is required for children under the age of four years.

Effects of formaldehyde on mitochondrial dysfunction and apoptosis in SK-N-SH neuroblastoma cells.

Methanol ingestion is neurotoxic in humans due to its metabolites, formaldehyde and formic acid. Here, we compared the cytotoxicity of methanol and its metabolites on different types of cells. While methanol and formic acid did not affect the viability of the cells, formaldehyde (200-800 µg/mL) was strongly cytotoxic in all cell types tested. We investigated the effects of formaldehyde on oxidative stress, mitochondrial respiratory functions, and apoptosis on the sensitive neuronal SK-N-SH cells. Oxidative stress was induced after 2 h of formaldehyde exposure. Formaldehyde at a concentration of 400 µg/mL for 12 h of treatment greatly reduced cellular adenosine triphosphate (ATP) levels. Confocal microscopy indicated that the mitochondrial membrane potential (MMP) was dose-dependently reduced by formaldehyde. A marked and dose-dependent inhibition of mitochondrial respiratory enzymes, viz., NADH dehydrogenase (complex I), cytochrome c oxidase (complex IV), and oxidative stress-sensitive aconitase was also detected following treatment with formaldehyde. Furthermore, formaldehyde caused a concentration-dependent increase in nuclear fragmentation and in the activities of the apoptosis-initiator caspase-9 and apoptosis-effector caspase-3/-7, indicating apoptosis progression. Our data suggests that formaldehyde exerts strong cytotoxicity, at least in part, by inducing oxidative stress, mitochondrial dysfunction, and eventually apoptosis. Changes in mitochondrial respiratory function and oxidative stress by formaldehyde may therefore be critical in methanol-induced toxicity.

Formic acid and acetic acid induce a programmed cell death in pathogenic Candida species.

Cutaneous fungal infections are common and widespread. Antifungal agents used for the treatment of these infections often have undesirable side effects. Furthermore, increased resistance of the microorganisms to the antifungal drugs becomes the growing problem. Accordingly, the search for natural antifungal compounds continues to receive attention. Apoptosis is highly regulated programmed cell death. During yeast cell apoptosis, amino acids and peptides are released and can stimulate regeneration of human epithelium cells. Thus, detection of chemical compounds inducing apoptosis in yeast and nontoxic for humans is of great medical relevance. The aim of this study was to detect chemical compound inducing apoptosis in pathogenic Candida species with the lowest toxicity to the mammalian cells. Five chemical compounds--acetic acid, sodium bicarbonate, potassium carbonate, lithium acetate, and formic acid--were tested for evaluation of antifungal activity on C. albicans, C. guilliermondii, and C. lusitaniae. The results showed that acetic acid and formic acid at the lowest concentrations induced yeast cells death. Apoptosis analysis revealed that cells death was accompanied by activation of caspase. Minimal inhibitory concentrations of potassium carbonate and sodium bicarbonate induced Candida cells necrosis. Toxicity test with mammalian cell cultures showed that formic acid has the lowest effect on the growth of Jurkat and NIH 3T3 cells. In conclusion, our results show that a low concentration of formic acid induces apoptosis-like programmed cell death in the Candida yeast and has a minimal effect on the survivability of mammalian cells, suggesting potential applications in the treatment of these infections.

Development of a phenotypic assay for characterisation of ethanologenic yeast strain sensitivity to inhibitors released from lignocellulosic feedstocks.

Inhibitors released by the breakdown of plant cell walls prevent efficient conversion of sugar into ethanol. The aim of this study was to develop a fast and reliable inhibitor sensitivity assay for ethanologenic yeast strains. The assay comprised bespoke 96-well plates containing inhibitors in isolation or combination in a format that was compatible with the Phenotypic Microarray Omnilog reader (Biolog, hayward, CA, USA). A redox reporter within the assay permits analysis of inhibitor sensitivity in aerobic and/or anaerobic conditions. Results from the assay were verified using growth on spot plates and tolerance assays in which maintenance of viability was assessed. The assay allows for individual and synergistic effects of inhibitors to be determined. It was observed that the presence of both acetic and formic acid significantly inhibited the yeast strains assessed, although this impact could be partially mitigated by buffering to neutral pH. Scheffersomyces stipitis, Candida spp., and Pichia guilliermondii demonstrated increased sensitivity to short chain weak acids at concentrations typically present in lignocellulosic hydrolysates. S. cerevisiae exhibited robustness to short chain weak acids at these concentrations. However, S. stipitis, Candida spp., and P. guilliermondii displayed increased tolerance to HMF when compared to that observed for S. cerevisiae. The results demonstrate that the phenotypic microarray assay developed in the current study is a valuable tool that can be used to identify yeast strains with desirable resistance to inhibitory compounds found in lignocellulosic hydrolysates.

Corynebacterium glutamicum harbours a molybdenum cofactor-dependent formate dehydrogenase which alleviates growth inhibition in the presence of formate.

Here, we show that Corynebacterium glutamicum ATCC 13032 co-metabolizes formate when it is grown with glucose as the carbon and energy source. CO(2) measurements during bioreactor cultivation and use of (13)C-labelled formate demonstrated that formate is almost completely oxidized to CO(2). The deletion of fdhF (cg0618), annotated as formate dehydrogenase (FDH) and located in a cluster of genes conserved in the family Corynebacteriaceae, prevented formate utilization. Similarly, deletion of fdhD (cg0616) resulted in the inability to metabolize formate and deletion of cg0617 markedly reduced formate utilization. These results illustrated that all three gene products are required for FDH activity. Growth studies with molybdate and tungstate indicated that the FDH from C. glutamicum ATCC 13032 is a molybdenum-dependent enzyme. The presence of 100 mM formate caused a 25 % lowered growth rate during cultivation of C. glutamicum ATCC 13032 wild-type in glucose minimal medium. This inhibitory effect was increased in the strains lacking FDH activity. Our data demonstrate that C. glutamicum ATCC 13032 possesses an FDH with a currently unknown electron acceptor. The presence of the FDH might help the soil bacterium C. glutamicum ATCC 13032 to alleviate growth retardation caused by formate, which is ubiquitously present in the environment.

RIFM fragrance ingredient safety assessment, cis-3-hexenyl methyl carbonate, CAS Registry Number 67633-96-9.

The following paper presents the method of determination of the percolation threshold in cement composites with expanded graphite by impedance spectroscopy. Most of the applications of cement composites with conductive additives require exceeding the percolation threshold. The ionic conductivity of cement matrix below the percolation threshold has a major impact on the conductivity of the composite, as a result, it significantly hinders the exploitation of these composites. The electric properties of cement composites with expanded graphite were evaluated by DC measurements and impedance spectroscopy (IS). Based on Nyquist plots, two equivalent circuits were adopted for the composites. Next, the values of capacitance and inductance of cement composites with expanded graphite were calculated from the fitted equivalent circuits. The analysis of the results shows that the percolation threshold occurs when the reactance of the composite changes from captative to inductive. Comparison between the values of percolation threshold obtained from DC measurements and IS shows that the method is effective for cement composites with conductive additives.

Characteristic effects of methylglyoxal and its degraded product formate on viability of human histiocytes: a possible detoxification pathway of methylglyoxal.

Methylglyoxal (MGO) is a toxic and highly reactive alpha-oxoaldehyde, elevated in the states of various diseases underlying enhanced oxidative stress. Furthermore, MGO has been reported to generate another aldehyde, formic acid (FA). In this sense, investigating the biological property of FA is crucially important. The present study examined the effects of MGO and FA on cell viability using the U937 human histiocytic cell line. FA showed a dose-dependent increase in cell viability at the concentrations of MGO in which cell viability decreased. The mechanism of the increase by FA involved the presence of endogenous hydrogen peroxide (H2O2) and tetrahydrofolate in the folate pathway, whereas that of the decrease in cell viability by MGO involved interaction with H2O2 and oxidative damage. These findings suggest that FA production by MGO degradation may play a role in attenuation of oxidative cellular injury caused by MGO. We hypothesize that FA generation pathway constitutes a detoxification system for MGO.

Formic acid triggers the "Acid Crash" of acetone-butanol-ethanol fermentation by Clostridium acetobutylicum.

Solvent production by Clostridium acetobutylicum collapses when cells are grown in pH-uncontrolled glucose medium, the so-called "acid crash" phenomenon. It is generally accepted that the fast accumulation of acetic acid and butyric acid triggers the acid crash. We found that addition of 1 mM formic acid into corn mash medium could trigger acid crash, suggesting that formic acid might be related to acid crash. When it was grown in pH-uncontrolled glucose medium or glucose-rich medium, C. acetobutylicum DSM 1731 containing the empty plasmid pIMP1 failed to produce solvents and was found to accumulate 0.5 to 1.24 mM formic acid intracellularly. In contrast, recombinant strain DSM 1731 with formate dehydrogenase activity did not accumulate formic acid intracellularly and could produce solvent as usual. We therefore conclude that the accumulation of formic acid, rather than acetic acid and butyric acid, is responsible for the acid crash of acetone-butanol-ethanol fermentation.

Trisodium phosphonoformate, a new antiviral compound.

Trisodium phosphonoformate selectively inhibits cell-free DNA polymerase activity induced by herpesvirus. The new inhibitor has an antiviral effect on herpes simplex virus types 1 and 2, pseudorables virus, and infectious bovine rhinotracheitis virus in cell culture. It has a good therapeutic activity against cutaneous herpes simplex virus infection in guinea pigs.

Indoor winter fumigation with formic acid for control of Acarapis woodi (Acari: Tarsonemidae) and nosema disease, Nosema sp.

Indoor fumigation of honey bees, Apis mellifera L., with formic acid to control varroa mites, Varroa destructor Anderson & Trueman, allows simultaneous fumigation of multiple colonies with little labor input and good efficacy. Several experiments were designed to test the efficacy of formic acid as a treatment for honey bee mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), and nosema disease, Nosema sp., indoors in winter. The objectives of this study were (1) to determine the efficacy of formic acid fumigation for honey bee mite control by using both the thoracic slice and live dissection methods and (2) to determine whether indoor fumigation can reliably prevent the buildup of nosema disease in overwintering honey bee colonies. Indoor winter fumigation of honey bee colonies with formic acid was effective in killing a high percentage of honey bee mites but did not significantly reduce the proportion of bees with infested tracheae over the duration of the experiments. Thus, the method used to determine the efficacy of the treatment affected the results. Under conditions of relatively low or decreasing levels of nosema, fumigation tended to suppress the mean abundance of nosema spores relative to the controls. In three separate fumigation experiments using a range of formic acid concentrations, there was no statistical difference between the buildup or maintenance of nosema spore mean abundance over the winter in bees from formic acid fumigated colonies compared with untreated controls. However, fumigation with formic acid during winter at a low concentration for extended periods significantly suppressed spore buildup of mixed populations of nosema (Nosema apis and Nosema ceranae) in 1 yr.

Acute toxicity and risk evaluation of the CSO disinfectants performic acid, peracetic acid, chlorine dioxide and their by-products hydrogen peroxide and chlorite.

The ecotoxicological evaluation of combined sewer overflow (CSO) disinfectants, with their degradation products, is important for ensuring safe use. For this form of toxicity, data for organisms representing different trophic levels are needed. We studied the toxicity of the alternative disinfectants peracetic acid (PAA), performic acid (PFA) and chlorine dioxide (ClO2) and their degradation products hydrogen peroxide (H2O2) and chlorite (ClO2-) on Vibrio fischeri and Daphnia magna. ClO2 was more toxic to D. magna (EC50 < 0.09 mg/L) and PFA was most toxic to V. fischeri (EC50 0.24 mg/L). EC50 of PFA, PAA, ClO2, H2O2 and ClO2- on D. magna were 0.85, 0.78, <0.09, 3.46 and 0.36 mg/L, respectively. Similarly, EC50 of PFA, PAA, ClO2, H2O2 and ClO2- on V. fischeri were 0.24, 0.42, 1.10, 5.67 and 30.93 mg/L, respectively. For both PFA and ClO2, the degradation in water was faster than for PAA, H2O2 and chlorite. Using these data together with literature values, we derived environmental quality standards. By combining these with typical concentrations of disinfectants used for CSOs, we estimated the dilution required for discharging CSOs after disinfection, which can be used for quick assessment of the environmental feasibility of disinfection systems at specific CSO sites. Minimal dilutions in the receiving water, in the orders of 44, 70 or 138-fold, are needed for ClO2, PFA and PAA, respectively. This highlights PFA as the most widely applicable disinfectant, taking into account both its efficiency and the lower risk of unwanted environmental effects.