Impairment of lipoglycoprotein metabolism in rat liver cells induced by 1,2-dichloroethane

Roles of CYP2e1 in 1,2-dichloroethane-induced liver damage in mice

The aim of this study was to explore the roles of cytochrome P450 2E1 (CYP2E1) in 1,2-dichloroethane (1,2-DCE)-induced liver damage. Two parts were included in this study: first, effect of 1,2-DCE on microsomal expression of CYP2E1, and second, potential of an inhibitor of CYP2E1 to reduce 1,2-DCE-induced liver damage. In part one, mice were exposed to 0, 0.225, 0.45, or 0.9 g/m³ 1,2-DCE for 10 days, 3.5 h per day through static inhalation. In part two, mice were divided into blank control, solvent control, inhibitor control, 1,2-DCE-poisoned group, and low or high intervention group. In part one, compared to the control, serum alanine aminotransferase (ALT) activities and hepatic malondialdehyde (MDA) levels in 0.9 g/m³ 1,2-DCE group, and microsomal CYP2E1 protein expression and activity in both 0.45 and 0.9 g/m³ 1,2-DCE groups increased significantly; conversely, hepatic nonprotein sulfhydryl (NPSH) levels in both 0.45 and 0.9 g/m³ 1,2-DCE groups and hepatic SOD activities in 0.9 g/m³ 1,2-DCE group decreased significantly. In part two, microsomal CYP2E1 protein expression and activity decreased significantly in both low and high intervention groups compared to 1,2-DCE-poisoned group. Along with the changes of CYP2E1, hepatic MDA levels and serum ALT activities decreased; conversely, hepatic NPSH levels and SOD activities increased significantly in high intervention group. Taken together, our results suggested that 1,2-DCE could enhance CYP2E1 protein expression and enzymatic activity, which could cause oxidative damage in liver, serving as an important mechanism underlying 1,2-DCE-induced liver damage. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1430-1438, 2016.

The demise of repetitive strain injury in sceptical governing rationalities of workplace managers

In the mid-1990s, RSI (repetitive strain injury) loomed as an occupational health epidemic in industrialised countries. A decade later, the problem appears to have faded away, but there has been little explanation for how this problem might have diminished. This paper offers an explanation for the decline of RSI in the social relations of workplaces, in the pragmatic, day-to-day governance of occupational health by workplace managers. Using the conceptual lens of governmentality theory, this study examined how workplace managers conceptualised, rationalised and responded to RSI in their work organisations. Open-ended interviews were conducted with 35 managers at four Ontario newspaper workplaces. This paper describes managers as guided by a discourse of scepticism about the legitimacy of RSI complaints. This discourse was 'practised' in different ways at each newspaper in varied RSI-management strategies, but each strategy privileged ideas about RSI being problematic in certain types of workers rather than in types of physical work environments. This conceptualisation of RSI splintered, subordinated and collapsed the problem within a broad human resources framework. This paper suggests that the 'taming' of RSI might have occurred in the context of micro-political, workplace-level shifts in the conceptualisation and management of RSI as an occupational health problem.

Influence of chronic ethanol consumption on toxic effects of 1,2-dichloroethane: glycolipoprotein retention and impairment of dolichol concentration in rat liver microsomes and Golgi apparatus

Our previous investigations demonstrated that 1,2-dichloroethane (DCE) and chronic ethanol treatment separately are able to impair glycoprotein metabolism and secretion, and reduce dolichol concentration in liver membranes. The purpose of this study was to investigate whether chronic ethanol consumption can induce potentiation of rat liver damage due to DCE haloalkane used in several chemical processes and in agriculture. Rats were given 36% of their total energy as ethanol in the Lieber-DeCarli liquid diet for 8 weeks (CH group). The pair-fed control group received an isocaloric amount of dextrine-maltose (PF group). "In vitro" experiments: the DCE (6.5 mM) treatment of isolated hepatocytes from CH rats enhanced glycoprotein retention and further reduced glycoprotein secretion and 14C-glucosamine incorporation compared to the hepatocytes from CH or from PF and DCE treated rats. "In vivo" experiments: a marked decrease of dolichol concentration in microsomes (in which dolichyl phosphate is rate-limiting for the initial glycosylation of protein) and in Golgi membranes (in which total dolichol is very important for membrane permeability, fluidity and vesicle fusion) was observed in CH rats acutely treated with 628 mg/kg bw of DCE (CH+DCE) compared with CH or PF+DCE treated rats. These data suggest that chronic ethanol consumption increases DCE liver toxicity by affecting protein glycosylation processes and impairing glycolipoprotein secretion, with a concomitant retention at the level of the Golgi apparatus.

Effects of vitamin E on dolichol content of rats acutely treated with 1,2-dichloroethane

Previous investigations have demonstrated that 1,2-dichloroethane (DCE) poisoning affects dolichol (Dol) concentration in rat liver. Dol, a long-chain polyprenol, is considered an important membrane component: as dolichyl phosphate, it is rate limiting for the synthesis of glycoprotein; as free or fatty acid, it is highly concentrated in the Golgi apparatus (GA) where it can increase membrane fluidity and permeability, required glycoprotein maturation and secretion. DCE biotransformation may stimulate pro-oxidant events through hepatocellular glutathione depletion. Since the molecules of Dol are susceptible to oxidative degradation, the aim of this investigation is to verify whether vitamin E (vit. E) supplementation in rats is able to prevent Dol breakdown during acute DCE treatment. Before acute DCE administration (628 mg/kg body weight), a group of male Wistar rats were pretreated with vit. E (33 mg/kg body weight) for 3 days. High-performance liquid chromatography analysis has shown that within 5-60 min after DCE administration, the Dol concentration decreased in liver homogenate, cytosol, microsomes and GA. Particularly, 60 min after the treatment, Dol levels in the trans Golgi fraction were 71% lower than in controls. Rat pre-treatment with vit. E prevented the DCE-induced decrease in Dol concentrations of all liver fractions considered, in particular the reduction of total-Dol observed in the trans Golgi fraction 60 min after treatment was only 40%. These data suggest that hepatic metabolism of DCE is able to promote peroxidative attacks which lead to the degradation of Dol molecules. The pre-treatment of rats with vit. E results in a good, although not complete, prevention of total-Dol depletion after DCE poisoning.