Mature alpha 2-plasmin inhibitor in human plasma has 12 more N-terminal residues than hitherto anticipated. The first residue is the methionine at position 28, downstream from the N-terminus of the pre-protein. The cDNA sequence predicts that the site cleaved upon formation of the mature inhibitor is a typical signal-peptidase recognition site. The mature inhibitor (464 residues) and the previously reported, and presumably degraded, form with N-terminal asparagine (452 residues), are present in plasma in about equal amounts. They both form a stable complex with plasmin. Recent studies on a recombinant alpha 2-plasmin inhibitor suggest that the 12 additional residues have functional implications [Sumi, Ichikawa, Nakamura, Miura and Aoki (1989) J. Biochem. 106, 703-707].
Autoprotection by acetaminophen, i.e. increased resistance to toxic effects caused by pretreatment, is a wellknown phenomenon. The purpose of the present work was to identify mechanisms for increased acetaminophen tolerance induced by pretreatment of rats. One group of female Wistar rats (pretreated rats) received acetaminophen orally in increasing doses (1 to 4.3 g/kg) twice a week for 3 weeks, one group (naïve rats) received the vehicle. At time zero pretreated rats received a toxic dose of 7.5 g/kg (100% lethal in naïve rats), and naïve rats received a toxic dose of 4.3 g/ kg. Blood and liver tissue were collected before and 12, 24, 36, and 48 hr after the toxic dose and were analysed for hepatic glutathione and cysteine contents, hepatic glutathione-S-transferase and blood alanine aminotransferase activity, as well as acetaminophen concentration in plasma. Steady-state mRNA levels of proteins involved in acetaminophen detoxification, cell division and acute phase response were measured, liver tissue was examined for proliferating cell nuclear antigen and degree of hepatocyte necrosis. Six naïve rats not receiving acetaminophen served as controls. The mortality was the same in pre-treated and naïve rats (33 percent). Thus, pretreatment increased the tolerance twice. Before the toxic dose pretreated rats compared to control rats had higher activity of glutathione-S-transferase (liver) and alanine aminotransferase (serum), higher hepatic mRNA level of glutathione-S-transferase and g-glutamylcysteine synthetase heavy and light chain subunits, and lower hepatic concentration of glutathione, cysteine and mRNA of CYP1A2 than control rats. After the toxic dose, the mRNA levels of glutathione-S-transferase, g-glutamylcysteine synthetase heavy and light chain subunits, and CYP1A2 in naïve rats rose, approaching those of pretreated rats. Proliferating cell nuclear antigen labelling was high in pretreated rats, while only slightly increased in a few of the naïve rats. Necrotic hepatocytes were found at all time intervals in pretreated rats, and in naïve rats they appeared after 12 hr, peaking after 36 hr. Pretreatment increased the tolerance to acetaminophen toxicity twice, as estimated by mortality. The data indicate that pretreatment may reduce the relative production of toxic metabolites, but it primarily enhances the protection against these metabolites by regenerating hepatocytes.
Serum concentrations of the actin scavenger Gc-globulin may provide prognostic information in acute liver failure (ALF). The fraction of Gc-globulin not bound to actin is postulated to represent a better marker than total Gc-globulin but has been difficult to measure. We tested a new rapid assay for actin-free Gc-globulin to determine its prognostic value when compared with the King's College Hospital (KCH) criteria in a large number of patients with ALF. A total of 252 patients with varying etiologies from the U.S. ALF Study Group registry were included; the first 178 patients constituted the learning set, and the last 74 patients served as the validation set. Actin-free Gc-globulin was determined with a commercial enzyme-linked immunosorbent assay kit. The median (range) actin-free Gc-globulin level at admission for the learning set was significantly reduced compared with controls (47 [0-183] mg/L vs. 204 [101-365] mg/L, respectively, P Ͻ 0.001). Gc-globulin levels were significantly higher in spontaneous survivors than in patients who died or were transplanted (53 [0-129] mg/L vs. 37 [0-183] mg/L, P ϭ 0.002). A receiver operating characteristic curve analysis showed that a 40 mg/L cutoff level carried the best prognostic information, yielding positive and negative predictive values of 68% and 67%, respectively, in the validation set. The corresponding figures for the KCH criteria were 72% and 64%. A new enzyme-linked immunosorbent assay for actin-free Gc-globulin provides the same (but not optimal) prognostic information as KCH criteria in a single measurement at admission. Liver Transpl 13: 1324Transpl 13: -1329Transpl 13: , 2007
Cyclosporine A and sirolimus are used alone or in combination as immunosuppressants in organ transplantation. To elucidate hepatic side effects, we examined hepatic mRNA of proteins involved in biliary and hepatocellular transport of drugs, formation of glutathione (GSH) and drug metabolising cytochrome P-450 enzymes (CYPs) in rats treated orally for 2 weeks with cyclosporine A (15 mg/kg/day), sirolimus (0.4 mg/kg/day), their combination (same doses), or vehicle. Liver function tests (alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and bilirubin) in blood were then analysed as were hepatic mRNA levels of canalicular transport proteins (Mrp2, Bsep, Mdr1b and Mdr2), sinusoidal transport proteins (Ntcp, Oatp1 and Oatp2), GSH related enzymes (gamma-glutamylcysteine synthetase light (GCSlc) and heavy (GCShc) chain subunits and glutathione-S-transferase) and CYPs (CYP3A9, CYP1A2, CYP2E1 and CYP2BI/II). Cyclosporine A caused moderate cholestatic changes in liver enzymes, which was synergistically exacerbated by sirolimus. The data suggest that the underlying mechanisms behind cholestasis were not totally identical in the different treatment regimens. Cholestasis secondary to cyclosporine A could be related to reduction in mRNA expression of GSH synthesising enzymes and Mrp2, leading to reduced protection against oxidative stress and reduced bile acid-independent bile flow. After sirolimus treatment, Mrp2 mRNA was also reduced together with reduced levels of most CYPs and increased Oatp2, possibly leading to accumulation of toxic metabolites in the hepatocytes. The enhanced cholestatic effect of the combination treatment could be related to reduced GSH synthesising enzymes and even more pronounced reduction in Mrp2 mRNA and increase of Oatp2 mRNA.
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