• Biomedical Science Letters
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• v.5 no.1
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• pp.59-66
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• 1999

To evaluate the effect of repeated treatment of xylene on its metabolism, m-xylene (0.25 ml of 50% in olive oi1/100 g body weight) has been intraperitoneally given to the rats 1, 4, 8, 12 and 16 times every other day. m-Xylene was once more administered to the animals after 24 hrs since last injection of it. And then the animals were sacrificed after 24 hrs. Four times xylene treated rats showed the significantly elevated urinary m-methylhippuric acid, compared to those treated with the single dose of m-xylene with the continued similiar high levels of urinary m-methylhippuric acid up to the animals pretreated 12 times and then those treated 16 times defined the significantly decreased urinary m-methylhippuric acid compared to those treated 12 times. On the other hand, hepatic aniline hydroxylase and alcohol dehydrogenase activities demonstrated a gradual increase from the first group to the 12 times xylene-treated animals, but those treated 16 times showed the significantly decreased value compared with the 12 times treated-group. And aldehyde dehydrogenase activities in rats treated with m-xylene 8, 12 or 16 times were significantly decreased compared to those pretreated one or four times. In the early stage of xylene administration, proliferation of SERs were seen whereas SERs were decreased and RERs were clearly increased in xylene-treated rats 16 times. These results indicate that the frequency of xylene injection may influence upon the changes in xylene metabolite, m-methylhippuric acid and it may be due to induction of xylene metabolizing enzymes.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.386-389
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• 2003

Organic solvent tolerance bacteria, Pseudomonas savastanoi BCNU 106 could utilize a high contentration of benzene, toluene, ethylbenzene, xylene isomers (BTEX) as a sole carbon source. It was founded that strain BCNU 106 transformed o-xylene to 2-methylbenzyl alcohol, 2-methylbenzoic acid through direct oxygenation of methyl residue on GC-MS analysis.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.909-915
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• 2002

The biodegradation of BTEX components (benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene) individually and in mixtures was investigated using the o-xylene-degrading thermo-tolerant bacterium Ralsronia sp. strain PHS1 , which utilizes benzene, toluene, ethylbenzene, or o-xylene as its sole carbon source. The results showed that as a single substrate for growth, benzene was superior to both toluene and ethylbenzene. While growth inhibition was severe at higher o-xylene concentrations, no inhibition was observed (up to 100 mg $l^-1$) with ethylbenzene. In mixtures of BTEX compounds, the PHS1 culture was shown to degrade all six BTEX components and the degradation rates were in the order of benzene, toluene, o-xylene, ethylbenzene, and m- and p-xylene. m-Xylene and p-xylene were found to be co-metabolized by this microorganism in the presence of the growth-supporting BTEX compounds. In binary mixtures containing the growth substrates (benzene, toluene, ethylbenzene. and o-xylene), PHS1 degraded each BTEX compound faster when it was alone than when it was a component of a BTEX mixture, although the degree of inhibition varied according to the substrates in the mixtures. p-Xylene was shown to be the most potent inhibitor of BTEX biodegradation in binary mixtures. On the other hand, the degradation rates of the non-growth substrates (m-xylene and p-xylene) were significantly enhanced by the addition of growth substrates. The substrate utilization patterns between PHS1 and other microorganisms were also examined.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.4
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• pp.310-319
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• 1993

A pilot study was conducted in order to investigate the concentrations of indoor and outdoor VOCs (Volatile Organic Compounds) at ten homes and four building offices in Seoul during March-April, 1993. The five components of VOCs(Benzene, Toluene, Ethylbenzene, o-Xylene, m/p-Xylene) were collected using charcoal tube and were analysed using Gas Chromatography(GC) with a Flame Ionization Detector(FID). The mean concentations of indoor VOCs were shown as Benzene of 38.9 .mu.g/m$^{3}$. Toluene of 165.0 .mu.g/m$^{3}$, Ethylbenzene of 21.7 .mu.g/m$^{3}$, o-Xylene of 11.6 .mu.g/m$^{3}$ and m/p-Xylene of 29.3 .mu.g/m$^{3}$, but those corresponding that indoor levels of VOCs were higher than corresponding outdoor levels. The ratio of indoor and outdoor VOCs were higher than corresponding outdoor levels. The ratio of indoor and outdoor VOCs concentrations was 0.99 for Benzene, 1.23 for Toluene, 5.86 for Ethylbenzene, 5.23 for o-Xylene, 2.41 for m/p-Xylene in homes, while 2.02 for Benzene, 1.15 for Toulene, 0.96 for Ethylbenzene, 1.41 for o-Xylene, 1.38 for m/p-Xylene in offices, respectively. The mean concentrations of VOCs in homes were higher than those levels in offices, while the mean concentration of VOCs during active hour of occupants in a day were higher 1-3 times than the levels during non-active hour. Comparing VOCs levels by building's age, the mean concentrations of Benzene, o-Xylene and m/p-Xylene were higher in new building than old building, but the mean concentrations of Toluene and Etylbenzene in new building were lower than old building. The mean concentrations in all components of VOCs in smoking area were higher than non-smoking area. These results suggested that the VOC levels were affected by various indoor characteristics and behavioral activity of occupants.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.10-16
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• 2001

To evaluate an effect of circadian variation on the xylene metabolizing enzyme activities, 50% m-xylene in olive oil(0.25 $m\ell$/100g body weight) was intraperitoneally administered to the rats every other day for 6 days both in the night; 24:00 and the day; 12:00. Then animals were sacrigiced at 8hr after last injection of m-xylene. Hepatic microsomal cytochrome p450 contents were more increased both in control and xylene treated rats of night phase than those of day phase. But the activity of hepatic alcohol dehydrogenase(ADH) in control of night phase showed the similar value with that in those of day phase and xylene treated rats of day phase showed an increasing tendency of hepatic ADH activity as those of night phase showing similar activity. Furthermore, control rats of night phase than those of day phase. And by xylene treatment, enzyme activities of rats of day phase were higher tendency in rats of control but those of night phase were somewhat inhibited. Besides, xylene-treated animals of night phase showed increasing tendency of urinary methylhippuric acid concentration compared with those of day phase. On the other hand, liver weight per body weight(%), hepatic lipid peroxide content and serum xanthine oxidase activity were higher in night phase. And the activities of hepatic oxygen free radical metabolizing enzymes such as xanthine oxidase, gluthathione S-transferase, and xylene-treated rats of night phase than those of day phase. In conclusion, it can be hypothesized on the basis of the results that the accumulation rate of m-xylene intermediate metabolite, i.e. m-methylbenzaldehyde in liver tissus may be higher in night phase than in day phase and it may be responsible for higher liver toxicity in bight phase than in day phase.

• Biomedical Science Letters
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• v.6 no.3
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• pp.193-199
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• 2000

To evaluate an effect of aging on the xylene toxicity, 50% m-xylene in olive oil (0.25 ml/100 g body wt.) was administered to 5 week and 12 week-old rats one times intraperitoneally and sacrificed at 24 hrs afterwards. The increasing rate of urinary m-methylhippuric acid concentration was higher in 12 week-old rats than 5 week-old rats by the treatment of m-xylene. On the liver function findings, i.e., liver weigh/body weight (%), serum levels of ALT activity and hepatic malondialdehyde content, 12 week-old rats showed more severe liver injury than 5 weeks those in xylene-treated rats. And the hepatic cytochrome P-450 contents was higher in 12 weeks rats than those of in 5 week-old rats, but the increasing rate of that was lower in 12 week-old rats. Hepatic alcohol dehydrogenase activity was also higher in 12 week-old rats than in 5 week-old rats whereas the increasing rate of that was higher in 5 week-old than those in 12 week-old rats by the xylene treatment. Furthermore, the hepatic aldehyde dehydrogenase activities were no differences between the 5 and 12 week-old rats both in the control and xylene-treated group. In conclusion, age may influences upon the hepatotoxicity with xylene and it may be responsible for xylene metabolism in rats.

• Journal of Microbiology and Biotechnology
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• v.8 no.3
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• pp.222-228
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• 1998

The characteristics of cometabolic removal of xylenes by Alcaligenes xylosoxidans Y234 were investigated. m-Xylene was found to be degraded while ο- and p-xylene were biotransformed into cresols in the presence of benzene or toluene. A lower level of benzene was required than that of toluene to remove the same amount of xylenes, which suggested benzene was a more effective primary substrate than toluene. ο-Xylene was found to be the most toxic to Alcaligenes xylosoxidans Y234 followed by p-xylene and m-xylene. Rates of cell decay during cometabolic removal of ο-, m-, or p-xylene were decreased by up to $76\%$ when benzene-adapted cells were inoculated. Xylenes were removed efficiently using benzene-adapted cells.

• Journal of the Korean Institute of Gas
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• v.14 no.5
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• pp.19-25
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• 2010

The flash points for the systems, o-xylene+n-pentanol and m-xylene+n-hexanol, were measured by using Tag open-cup tester(ASTM D1310-86). The experimental data were compared with the values calculated by the Raoult's law and the optimization method using van Laar and Wilson equations. The calculated values based on the optimization method were found to be better than those based on the Raoult's law. The predictive curve of the flash point prediction model based on the van Laar equation described the experimentally-derived data more effectively than was the case when the prediction model was based upon the Wilson equation.

• Toxicological Research
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• v.11 no.2
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• pp.205-213
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• 1995

This study was undertaken to investigate the effects of organic solvents on xenobiotic metabollzing enzyme system in vivo by meaas of experimental conditions i.e. (1) single group which was treated by benzene (B), toluene (T) and xylene (X), respectively, (2) combination group which was treated by mixture of benzene+toluene (BT), benzene+xylene (BX), and toluene+xylene (TX), respectively, (3) mixture group which was treated by benzene+ toluene+xylene mixture (M), and to interpreat the interaction between the organic solvents metabolizing enzymes. 1. The contents of cytochrome P-450 in liver microsomes were increased (p < 0.01) in organic solvents treated groups, and the contents of cytochrome P-450 were increased by following order of B < T < M < BT=BX < X < TX. 2. The activity of cytochrome P-450 dependent AHHase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the activity of AHHase was increased by following order of B < T < BT=BX=TX=xylene < M. 3. The activity of NADPH P-450 reductase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the order of M < combinated group < X < T

• Journal of Soil and Groundwater Environment
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• v.18 no.6
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• pp.38-47
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• 2013

This study was performed to identify the optimal operating conditions and to evaluate the xylene removal efficiency, applying in-situ soil flushing with the low concentrated solution of 'Tween 80' at the xylene contaminated site. The pilot scale test site ($5m{\times}5m{\times}3m$), was mainly composed of 'sandy loam', with the average hydraulic conductivity of $9.1{\times}10^{-4}cm\;s^{-1}$. The average xylene concentration of the site was 42.1 mg $kg^{-1}$, which was more than 2.5 times higher than Korea soil pollution warning limit (15 mg $kg^{-1}$). For the soil flushing, 7,800 L of 0.1~0.2% surfactant solution was injected into three injection wells at the average injection time of 9 hr $d^{-1}$ for 10 days, followed by the additional only groundwater injection of 6,000 L. The same amount of the effluent solution was extracted from three extraction wells. From the analysis for xylene concentration of all effluent at 3 extraction wells, total 166 g of xylene was removed by in-situ surfactant flushing. Even though the residual xylene concentrations of 7 soil sampling locations in the test site were different due to the soil heterogeneity, from the comparison of xylene concentration at 7 locations before/after the feasibility test, 53.9% of the initial xylene in the site was removed from three extraction wells (mainly Ext-N and Ext-M well). The results showed that the in-situ soil flushing by using low concentrated 'Tween 80' solution had a great potential to remediate the xylene contaminated site.