In vitro cytotoxic effect of glyphosate mixture containing surfactants.

We investigated whether glyphosate influences the cellular toxicity of the surfactants TN-20 and LN-10 on the mouse fibroblast-like cells, alveolar epithelial cells, and a heart cell line. The cytotoxicity of TN-20 and LN-10 (0.4-100 µM), in the presence or absence of glyphosate was determined by assessing membrane integrity. TN-20 toxicity was significantly lower in the presence of 50 µM glyphosate for the fibroblast-like cell (6.25 µM; 3.9% ± 3.4% vs -4.8% ± 0.7%), for the alveolar cells (0.78 µM; 5.7% ± 0.9% vs 0.1% ± 0.6%), and for the heart cell line (25.0 µM; 7.9% ± 3.0% vs 19.4% ± 0.7%) compared to that of TN-20 alone. The cellular toxicity of LN-10 towards the fibroblast-like cells was found to be increased in the presence of 50 µM glyphosate when LN-10 concentrations of 50 µM (31.3% ± 3.9% vs 19.2% ± 0.9%) and 100 µM (62.1% ± 3.4% vs 39.0% ± 0.7%) were compared to that of LN-10 alone. These results suggest that the mixture toxicity may be a factor in glyphosate-surfactant toxicity in patients with acute glyphosate herbicide intoxication.

Cellular toxicity of surfactants used as herbicide additives.

The cellular toxicities of surfactants, a solvent, and an antifreeze that are included in herbicide formulations were assessed by measuring their effects on membrane integrity, metabolic activity, mitochondrial activity, and total protein synthesis rate in a cell culture. Polyethylene glycol, propylene glycol, and monoethylene glycol exhibited no cellular toxicity even at a high concentration of 100 mM. Sodium lauryl ether sulfate and polyoxyethylene lauryl ether significantly damaged the membrane, disturbed cellular metabolic activity, and decreased mitochondrial activity and the protein synthesis rate; however, their toxicity was far below those of the severely toxic chemicals at comparable concentrations. The severely toxic category included polyoxypropylene glycol block copolymer, polyoxyethylene tallow amine, and polyoxyethylene lauryl amine ether. These surfactants were cytotoxic between 3.125 µM and 100 µM in a dose-dependent manner. However, the toxicity graph of concentration vs toxicity had a point of inflection at 25 µM. The slope of the toxicity graph was gentle when the concentration was below 25 µM and steep when the concentration was greater than 25 µM. In conclusion, our results suggest that the toxicity of surfactants be taken care of pertinent treatment of acute herbicide intoxication.

Long-term effect of medium cut-off dialyzer on middle uremic toxins and cell-free hemoglobin.

The medium cut-off (MCO) dialyzer has shown good clearance of large middle molecules, but its long-term effects are unclear. We investigated whether MCO hemodialysis (HD) over one year could reduce middle molecule levels and cell-free hemoglobin (CFH), without albumin loss. A prospective cohort study in 57 hemodialysis patients was conducted. The patients were assigned to the MCO dialyzer group or the high-flux dialyzer group, according to the HD machine they used. The reduction ratio (RR) and one-year changes in small and middle molecules and CFH were analyzed. Over a 12-month follow-up, MCO HD did not reduce the serum levels of middle molecules (lambda free light chain [FLC], from 135.7 ± 39.9 to 132.0 ± 39.1 mg/L; kappa FLC, from 168.2 ± 58.5 to 167.7 ± 65.8 mg/L; ß2-microglobulin, from 25.6 ± 9.6 to 28.4 ± 4.8 mg/L) or albumin (from 3.96 ± 0.31 to 3.94 ± 0.37 g/dL). MCO HD provided excellent RR of lambda FLC (49.3 ± 10.3%), kappa FLC (69.6 ± 10.4%) and ß2-microglobulin (80.9 ± 7.3%), compared to high-flux HD. CFH was also removed well during an MCO HD session (RR of CPH, 85.5 [78.7-97.3] %), but long-term change was not significant (from 57.8 [46.2-79.1] to 62.0 [54.6-116.7] mg/L). The MCO dialyzer can be used effectively and safely in conventional HD settings, but long-term effects on large middle molecules and CFH were not significant. Further studies are needed to verify clinical benefits of the MCO dialyzer.

The effects of nonyl phenoxypolyethoxyl ethanol on cell damage pathway gene expression in SK-NSH cells.

BACKGROUND/AIMS: Most pesticide formulations contain both chief and additive ingredients. But, the additives may not have been tested as thoroughly as the chief ingredients. The surfactant, nonyl phenoxypolyethoxylethanol (NP40), is an additive frequently present in pesticide formulations. We investigated the effects of NP40 and other constituents of a validamycin pesticide formulation on cell viability and on the expression of genes involved in cell damage pathways. METHODS: The effects of validamycin pesticide ingredients on cell viability and of NP40 on the mRNA expression of 80 genes involved in nine key cellular pathways were examined in the human neuroblastoma SK-N-SH cell line. RESULTS: The chemicals present in the validamycin pesticide formulation were cytotoxic to SK-N-SH cells and NP40 showed the greatest cytotoxicity. A range of gene expression changes were identified, with both up- and down-regulation of genes within the same pathway. However, all genes tested in the necrosis signaling pathway were down-regulated and all genes tested in the cell cycle checkpoint/arrest pathway were up-regulated. The median fold-change in gene expression was significantly higher in the cell cycle checkpoint/arrest pathway than in the hypoxia pathway category (p = 0.0064). The 70 kDa heat shock protein 4 gene, within the heat shock protein/unfolded protein response category, showed the highest individual increase in expression (26.1-fold). CONCLUSIONS: NP40 appeared to be particularly harmful, inducing gene expression changes that indicated genotoxicity, activation of the cell death (necrosis signaling) pathway, and induction of the 70 kDa heat shock protein 4 gene.

Mixtures of glyphosate and surfactant TN20 accelerate cell death via mitochondrial damage-induced apoptosis and necrosis.

Glyphosate, a common herbicide, is not toxic under normal exposure circumstances. However, this chemical, when combined with a surfactant, is cytotoxic. In this study, the mechanism of the additive effect of glyphosate and TN-20, a common surfactant in glyphosate herbicides, was investigated. After exposure of rat H9c2 cells to glyphosate and TN-20 mixtures, following assays were performed: flow cytometry to determine the proportion of cells that underwent apoptosis and necrosis; western blotting to determine expression of mitochondrial proteins (Bcl-2 and Bax); immunological methods to evaluate translocation of cytochrome C; luminometric measurements to determine activity of caspases 3/7 and 9; and tetramethyl rhodamine methyl ester assay to measure mitochondrial membrane potentials. Bcl-1 intensity decreased while Bax intensity increased with exposure to increasing TN-20 and/or glyphosate concentrations. Caspase activity increased and mitochondrial membrane potential decreased only when the cells were exposed to a mixture of both TN-20 and glyphosate, but not after exposure to either one of these compounds. The results support the possibility that mixtures of glyphosate and TN-20 aggravate mitochondrial damage and induce apoptosis and necrosis. Throughout this process, TN-20 seems to disrupt the integrity of the cellular barrier to glyphosate uptake, promoting glyphosate-mediated toxicity.

The effect of dialysis membrane flux on amino acid loss in hemodialysis patients.

We examined whether high flux membranes (HF) may induce a greater loss of amino acids compared to low flux membranes (LF). Ten hemodialysis patients participated in this study. Pre- and post-hemodialysis plasma amino acid profiles were measured by reverse-phase high pressure liquid chromatography for both HF and LF. We measured the dialysate amino acid losses during hemodialysis. The reduction difference for plasma total amino acid (TAA), essential amino acid (EAA), and branch chained amino acid (BCAA) was not significantly different in comparisons between the two membranes. (HF vs. LF; TAA 66.85 +/- 30.56 vs. 53.78 +/- 41.28, p=0.12; EAA 14.79 +/-17.16 vs. 17.97 +/- 28.69, p=0.12; BCAA 2.21 +/- 6.08 vs. 4.16 +/- 10.98 mg/L, p=0.13). For the HF, the reduction in plasma amino acid levels for TAA and EAA were statistically significant. Although it was not statistically significant, the dialysate losses of BCAA were greater than the reduction in plasma (plasma reduction vs. dialysate loss; HF 2.21 +/- 6.08 vs. 6.58 +/- 4.32, LF 4.16 +/- 10.98 vs. 7.96 +/- 3.25 mg/L). HF with large pores and a sieving coefficient do not influence dialysate amino acid losses. Hemodialysis itself may influence the dialysate amino acid losses and may have an effect on protein metabolism.