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.

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.

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.

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.

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.

Lethality of synthetic and natural acaricides to worker honey bees (Apis mellifera) and their impact on the expression of health and detoxification-related genes.

In this study, honey bees (Apis mellifera L.) were exposed to LD05 and LD50 doses of five commonly used acaricides for controlling the parasitic mite, Varroa destructor. LD50 values at 48 h post-treatment showed that tau-fluvalinate was the most toxic, followed by amitraz, coumaphos, thymol, and formic acid. However, the hazard ratios, which estimate the hive risk level based on a ratio of a standard dose of acaricide per hive to the LD50 of the acaricide, revealed that tau-fluvalinate was the most hazardous followed by formic acid, coumaphos, amitraz, and thymol. The expression of the honey bee acetylcholinesterase gene increased after treatment with the LD05 and LD50 acaricide doses and could distinguish three patterns in the timing and level of increased expression between acaricides: one for amitraz, one for tau-fluvalinate and formic acid, and one for coumaphos and thymol. Conversely, changes in cytochrome P450 gene expression could also be detected in response to all five acaricides, but there were no significant differences between them. Changes in vitellogenin gene expression could only detect the effects of tau-fluvalinate, amitraz, or coumaphos treatment, which were not significantly different from each other. Among the acaricides tested, coumaphos, amitraz, and thymol appear to be the safest acaricides based on their hazard ratios, and a good marker to detect differences between the effects of sub-lethal doses of acaricides is monitoring changes in acetylcholinesterase gene expression.