Evaluation of DNA damage by the Comet assay in shoe workers exposed to toluene and other organic solvents

The alkaline single-cell gel electrophoresis (or Comet) assay was applied to evaluate DNA damage in cryopreserved peripheral blood mononuclear leukocytes from 34 female shoe workers exposed to organic solvents and a group of 19 non-exposed women. We also investigated whether the polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes affect individual level of DNA damage possibly induced by the solvent exposure. Chemical measurements of workplace air in the two factories studied showed that the workers were exposed to acetone, gasoline, and toluene in both factories and to ethylacetate and diisocyanate in one factory. In the exposed workers, the average level of blood hemoglobin was lower and that of urinary hippuric acid higher than in the non-exposed individuals. However, the occupational exposure to organic solvents did not affect the Comet values. Neither did age, smoking, or the GSTM1 genotype have any effect on the outcome of this assay. The low prevalence of the GSTT1-null genotype precluded conclusions on the influence of GSTT1 polymorphism.     

Enzymatic catalysis in organic solvents: Polyethylene glycol modified hydrogenase retains sulfhydrogenase activity in toluene

Naturally occurring enzymes may be modified by covalently attaching hydrophobic groups that render the enzyme soluble and active in organic solvents, and have the potential to greatly expand applications of enzymatic catalysis. The reduction of elemental sulfur to hydrogen sulfide by a hydrogenase isolated from Pyrococcus furiosus has been investigated as a model system for organic biocatalysis. While the native hydrogenase catalyzed the reduction of sulfur to H(2)S in aqueous solution, no activity was observed when the aqueous solvent was replaced with anhydrous toluene. Hydrogenase modified with PEG p-nitrophenyl carbonate demonstrated its native biocatalytic ability in toluene when the reducing dye, benzyl viologen, was also present. Neither benzyl viologen nor PEG p-nitrophenyl carbonate alone demonstrated reducing capability. PEG modified cellulase and benzyl viologen were also incapable of reducing sulfur to H(2)S, indicating that the enzyme itself, and not the modification procedure, is responsible for the conversion in the nonpolar organic solvent. Sulfide production in toluene was tenfold higher than that produced in an aqueous system with equal enzyme activity, demonstrating the advantages of organic biocatalysis. Applications of bio-processing in nonaqueous media are expected to provide significant advances in the areas of fossil fuels, renewable feedstocks, organic synthesis, and environmental control technology. (c) 1996 John Wiley & Sons, Inc.     

Cytoenzymatic studies on neutrophils in workers having contact with organic solvents containing benzene, toluene and xylene

In 106 workers (47 women and 59 men) being in professional contact with organic solvents containing benzene and its homologues during 1 to 122 months the cytochemical examination of peripheral blood neutrophils has been performed. The patterns of neutrophil functional activation have been noted expressed in increased activities of acid phosphatase and beta-glucuronidase, increased NBT reduction and diminished glycogen reserves. Those changes were accompanied by diminished peroxidase and alkaline phosphatase activities. The stimulated NBT reduction, elevated in majority of workers, exhibited negative correlation with the exposure time what indicates the practical value of that test monitoring the biological effects of professional contact with the solvents.     

Micelle formation of diacylglycerophosphocholines in organic solvents I. effects of the solvents on krafft points

Krafft points of diacylglycerophosphocholines (PC) were measured in alkanes-cyclohexane solutions by differential scanning calorimetry, and it was found that they were regularly increased following the increase in alkane content in the solutions and the chain length of the alkanes. From these results it was deduced that the mixing of PC with alkanes occurred in the gel state of the PC, but not in micelles at higher temperatures above the Krafft points. where micellar solutions are provided. The penetration of alkanes into gel state PC was found to be dominated by Langmuir type interaction, and the affinity of alkanes increases with increasing in chain lengths. Above the Krafft points, the micelle formation was confirmed by using the fluorescence probe technique.     

In vitro effects of organic solvents on immunity indicators in serum

Serum treatment in vitro with organic solvents (chloroform, ether, toluene) failed to produce an effect on immunoglobulin levels and activity. After chloroform and ether treatment, no complement activity could be determined, with chloroform-treated serum beginning to express anticomplement activity against autologous, allogenic and xenogenic sera. The classical pathway of complement activation (C1, C4, C2, C3) was primarily inhibited, whereas the alternative pathway remained unaffected. Chloroform-treated sera exhibited significantly declined levels of C1-INH, C3 and C4 as well as of circulating immune complexes. Toluene did not influence any of the parameters tested, while ether blocked complement activity without affecting either the concentration or activity of the other components under investigation. The obtained findings are discussed from the aspect of organic solvent applications in preparing immune products and determining immunity indicators in the serum or other biological fluids.     

Promotive effects of organic solvents and kinetin on dark germination of lettuce seeds

Significant promotion in dark germination was observed when Grand Rapids lettuce (Lactuca sativa L.) seeds were soaked in acetone or dichloromethane, vacuum-dried, and imbibed at 25 C. Permeation of kinetin via these organic solvents further enhanced the dark germination. Those seeds that were affected by acetone and acetone-kinetin treatments and germinated in the dark escaped red-far red photocontrol of germination. Although abscisic acid was not detected in the organic solvent leachates, they did contain other inhibitory substances affecting lettuce seedling growth. In the light, acetone and acetone-kinetin treatments also enhanced the rate of germination and the increased germination by acetone-kinetin treatment was correlated with increased polyribosome formation. The possible mechanisms involved in promotion of lettuce seed germination by organic solvents and kinetin are discussed.     

Adaptation of Pseudomonas putida S12 to high concentrations of styrene and other organic solvents.

Pseudomonas putida S12 could adapt to grow on styrene in a two-phase styrene-water system. Acetate was toxic for P. putida S12, but cells were similarly able to adapt to higher acetate concentrations. Only by using these acetate-adapted cells was growth observed in the presence of supersaturating concentrations of toxic nonmetabolizable solvents such as toluene.     

Dual effects of organic solvents on chloroplast phosphoribulokinase and NADP-glyceraldehyde-3-P dehydrogenase

Organic solvents miscible in water (cosolvents) exerted a dual effect on the activation stage of two thioredoxin-linked enzymes of the reductive pentose phosphate cycle, phosphoribulokinase and NADP-glyceraldehyde-3-P dehydrogenase, both from spinach chloroplast; the enzyme specific activity was stimulated and inhibited by low and high concentrations of alcohols, respectively. On the contrary, cosolvents inhibited the catalytic process. In the stimulation of phosphoribulokinase activation, organic solvents reduced the requirement for thioredoxin-f and changed the thiol specificity, so that monothiols became functional. The cosolvent-mediated enhancement of NADP-glyceraldehyde-3-P dehydrogenase was obtained in the absence of modulators. With both enzymes, the concentration of the organic solvents required for activation was inversely proportional to its hydrophobicity (1-butanol < 1-propanol < 2-propanol < ethanol). The present results demonstrate the participation of a new component, the enzyme microenvironment, in the regulation of thioredoxin-linked chloroplast enzymes.     

Proteins in organic solvents

Catalysis in organic solvents and the mapping of protein surfaces using multiple solvent crystal structures are two rapidly developing areas of research. Recent advances include the study of protein folding and stability in different solvents, and the demonstration that it is possible to qualitatively rank the affinities of protein binding sites for a given organic solvent using the multiple solvent crystal structures method.     

两液相培养中有机溶剂对细胞毒性的研究进展

在生物化学工程中 ,细胞培养 -分离耦合过程的研究越来越引起人们的重视[1] ,其主要原因一是为了减少代谢产物的反馈作用 ,提高代谢产物产率 ,促进更多的细胞培养工业化进程 ;二是为了协调上游和下游加工过程 ,使整个过程的研究得到优化 ,以提高生产效率 ,降低生成成本。因此近十年细胞培养 -分离耦合过程的研究有了较大的发展。可以说几乎所有主要的生化分离技术都有用在细胞培养 -分离耦合过程的研究上。但研究较多的是细胞培养与萃取分离耦合 ,即两液相培养 ,并证明这是一项很有用的技术。两液相培养研究所涉及的内容很多 ,但最重要的是…     

Solvent effects on the catalytic activity of subtilisin suspended in organic solvents

We studied a model transesterification reaction catalyzed by subtilisin Carlsberg suspended in toluene, n-hexane, diisopropyl ether, and mixtures of these solvents. To account for solvent effects due to differences in water partitioning between the enzyme and the bulk solvents, we measured water sorption isotherms for the enzyme in each solvent. We measured catalytic activity as a function of enzyme hydration and obtained bell-shaped curves with maxima at the same enzyme hydration in all the solvents. However, the activity maxima were different in all the media, being the lowest in toluene. Differences in the partitioning of substrates and product between the bulk solvent phase and the enzyme active site were accounted for but could not explain the lower catalytic activity observed in toluene. The fact that toluene is very similar to one of the substrates suggested the possibility of competitive inhibition by this solvent. We derived a model allowing for differences in solvation of the substrates, by using thermodynamic activities instead of concentrations, as well as for competitive inhibition by toluene. The model fit the experimental data well, confirming that toluene had a direct adverse effect on the catalytic activity of the enzyme. (c) 1996 John Wiley & Sons, Inc.     

Effect of organic solvents on penicillin acylase-catalyzed reactions: interaction of organic solvents with enzymes

The effects of various organic solvents on penicillin acylase-catalyzed synthesis of β-lactam antibiotics (pivampicillin and ampicillin) have been investigated in water-solvent mixtures. The rates of penicillin acylase-catalyzed reactions were found to be significantly reduced by the presence of a small amount of organic solvent. In particular, the rate of enzyme catalysis was extremely low in the presence of ring-structured solvents and acids while enzyme activities were fully restored after removing the solvents. This indicates that interactions between the solvents and the enzyme are specific and reversible. To correlate the inhibitory effects of organic solvents with solvent properties the influence of solvent hydrophobicities and solvent activity on the rate of pivampicillin synthesis was examined. The reaction rate was found to decrease with increasing solvent hydrophobicities, and a better correlation was observed between the reaction rate and solvent activity. The effects of ionic strength on the synthesis of pivampicillin and ampicillin were also examined. The ionic strength dependence indicates that electrostatic interactions are involved in the binding of ionic compounds to the enzyme. On the basis of the active site structure of penicillin acylase, a possible mechanism for molecular interactions between the enzyme and organic solvents is suggested.