Effects of spiked metals on the MSW anaerobic digestion.

This study aimed to investigate the effects of eight metals on the anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) in bioreactors. Anaerobic bioreactors containing 200 mL MSW mixed completely with 200 m L sludge seeding. Ca and K (0, 1000, 2000 and 6,000 mg L(-1)) and Cr, Ni, Zn, Co, Mo and W (0, 5, 50 and 100 mg L(-1)) of various dose were added to anaerobic bioreactors to examine their anaerobic digestion performance. Results showed that except K and Zn, Ca (~728 to ~1,461 mg L(-1)), Cr (~0.0022 to ~0.0212 mg L(-1)), Ni (~0.801 to ~5.362 mg L(-1)), Co (~0.148 to ~0.580 mg L(-1)), Mo (~0.044 to ~52.94 mg L(-1)) and W (~0.658 to ~40.39 mg L(-1)) had the potential to enhance the biogas production. On the other hand, except Mo and W, inhibitory concentrations IC(50) of Ca, K, Cr, Ni, Zn and Co were found to be ~3252, ~2097, ~0.124, ~7.239, ~0.482, ~8.625 mg L(-1), respectively. Eight spiked metals showed that they were adsorbed by MSW to a different extent resulting in different liquid metals levels and potential stimulation and inhibition on MSW anaerobic digestion. These results were discussed and compared to results from literature.

Human biliary beta-glucuronidase activity before and after relief of bile duct obstruction: is it the major role in the formation of pigment gallstones?

BACKGROUND AND AIMS: The bacterial beta-glucuronidase (bBG) can deconjugate conjugated bilirubin to form calcium bilirubinate gallstone. Yet, the role of the human biliary beta-glucuronidase (hBG) in the pathogenesis of pigment gallstone formation still remains unsolved. METHODS: Hepatic bile was collected from bile-duct-obstructed patients on the day of, and 3 days after, biliary drainage. Patients were divided into pigment-stone (PS) group (n = 34) and stone-free (SF) group (n = 29). All patients of the PS group had the complication of cholangitis. The concentrations of bile contents and the activities of bBG and hBG were measured. RESULTS: The activities of hBG and bBG in bile obtained on the day of biliary drainage were higher in the PS group than in the SF group (activities corrected for bile salt concentration: hBG 128.7 +/- 340.0 vs 13.1 +/- 25.0 U/mmol; bBG 12.5 +/- 22.2 vs 4.6 +/- 7.7 U/mmol, P < 0.05). This difference disappeared after biliary drainage. The changes of enzyme activity in the bile of the SF group were unremarkable before and after biliary drainage. The mean concentrations of bile pigments and free calcium in the PS group were lower than those in the SF group. CONCLUSIONS: An increase in the activity of hBG may be a secondary response, developed after bile duct inflammation because it was elevated only when the bile duct obstruction was associated with infection.

Protective effect of melatonin on renal injury of rats induced by bile duct ligation.

Oxygen radicals have been implicated in the pathogenesis of renal injury induced by extrahepatic cholestasis. We conduct this study to investigate whether melatonin can have a protective effect against such injury. Either normal saline or gentamicin with or without melatonin was injected into rats that received either a bile duct ligation or a sham operation. The serum levels of malondialdehyde and total antioxidative activity were measured. The kidney was fixed for histologic scoring of renal injury. The serum malondialdehyde level was highest in the rats that received both bile duct ligation and gentamicin injection. Treatment with melatonin significantly increased the serum total antioxidative activity and reduced the serum malondialdehyde concentration. The mean score of renal injury, highest in the rats receiving bile duct ligation and gentamicin injection, was significantly reduced with melatonin treatment. By reducing the systemic oxygen radicals, supplementation with antioxidants exerts a protective effect on the renal injury induced by extrahepatic cholestasis.

Melatonin prevents pigment gallstone formation induced by bile duct ligation in guinea pigs.

Free radical-mediated oxidative stress has been implicated in the genesis of gallstone in vitro. This study was designed to examine the oxidative stress changes during pigment gallstone formation and to investigate whether melatonin (MLT) could act as a chemopreventive agent for cholelithiasis in a guinea pig model. The common bile duct of guinea pigs was ligated with or without MLT pretreatment. Animals were studied on day 7, 9, 12, and 14 after surgery. Stone and/or sludge developed in ligated guinea pigs without MLT. Fourier transform infrared spectra of the sludge showed the presence of calcium bilirubinate, whose peak height per milligram of sludge gradually increased with time after ligation. Total antioxidant activity (TAA) in bile of guinea pigs at day 14 after ligation reduced to one third of the level in sham-operated controls (P <.001). In addition, the bile of ligated guinea pigs had increased pH (P <.001), bile salts (P <.01), and malondialdehyde (MDA) (P <.05), compared to sham controls. Pretreatment of guinea pigs with MLT at a dose of 1,000 microg/kg significantly decreased the incidence of pigment gallstone formation at day 14 after ligation, as compared to no pretreatment (0/7 vs. 8/10). MLT also reverted the ligation-induced changes in biliary bile salts, pH, MDA, and TAA to control levels. These in vivo findings support a causative role of oxidative stress in the bile duct ligation-induced pigment gallstone formation. Antioxidants may prove useful in preventing pigment gallstone formation in humans.