Exposure to toxic metals and pollutants is a major environmental problem. Cadmium is a metal causing acute hepatic injury but the mechanism of this phenomenon is poorly understood. In the present study, we investigated the mechanism and time-course of cadmium-induced liver injury in rats, with emphasis being placed on apoptosis in parenchymal and nonparenchymal liver cells. Cadmium (3.5 mg/kg body weight) was injected intraperitoneally and the rats were killed 0, 9, 12, 16, 24, 48 and 60 h later. The extent of liver injury was evaluated for necrosis, apoptosis, peliosis, mitoses and inflammatory infiltration in hematoxylin-eosin-stained liver sections, and by assaying serum enzyme activities. The number of cells that died via apoptosis was quantified by TUNEL assay. The identification of nonparenchymal liver cells and activated Kupffer cells was performed histochemically. Liver regeneration was evaluated by assaying the activity of liver thymidine kinase and by the rate of 3H-thymidine incorporation into DNA. Both cadmium-induced necrotic cell death and parenchymal cell apoptosis showed a biphasic elevation at 12 and 48 h and peaked at 48 and 12 h, respectively. Nonparenchymal cell apoptosis peaked at 48 h. Peliosis hepatis, another characteristic form of liver injury, was first observed at 16 h and, at all time points, closely correlated with the apoptotic index of nonparenchymal liver cells, where the lesion was also maximial at 48 h. Kupffer cell activation and neutrophil infiltration were minimal for all time points examined. Based on thymidine kinase activity, liver regeneration was found to discern a classic biphasic peak pattern at 12 and 48 h. It was very interesting to observe that cadmium-induced liver injury did not involve inflammation at any time point. Apoptosis seems to be a major mechanism for the removal of damaged cells, and constitutes the major type of cell death in nonparenchymal liver cells. Apoptosis of nonparenchymal cells is the basis of the pathogenesis of peliosis hepatis. The first peaks of necrosis and parenchymal cell apoptosis seem to evolve as a result of direct cadmium effects whereas the latter ones result from ischemia.
In this study, a comprehensive methodology for modelling the hepatitis C virus (HCV) epidemic is proposed to predict the future disease burden and assess whether the recent decline in the incidence of HCV may affect the future occurrence of cirrhosis and hepatocellular carcinoma (HCC) cases. Using the prevalence of HCV, the distribution of chronic hepatitis C (CHC) patients within the various transmission groups and their infection-onset times, it was possible to reconstruct the incident infections per year in the past that progressed to CHC in Greece. The natural history of the disease was simulated in subcohorts of newly infected subjects using transition probabilities derived either empirically between fibrosis stages 0-4 or from literature review. Annual estimates of the incidence and prevalence of CHC by fibrosis stage, HCC and mortality in Greece were obtained up to 2030. HCV incidence peaked in the late 1980s at five new infections/10,000 person-years. Under the assumption of 20-100% decline in HCV incidence after 1990, the cumulative number of incident cirrhosis and HCC cases from 2002-2030 was projected to be lower by 9.6-48.2% and 5.9-29.5%, respectively, than that estimated under the assumption of no decline. However, the prevalent cirrhotic/HCC cases and HCV-related deaths are predicted to decline in the next 30 years only under the assumption of complete elimination of new HCV infections after 1990. Despite the progress in the reduction of HCV transmission, primary prevention does not seem adequate to reverse the rise in the incidence of cirrhosis and HCC.
Serotonin receptor 2 blockade can arrest liver regeneration only when administered close to G1/S transition point, and that while serotonin may be a cofactor for DNA synthesis, it does not play a role in initiation of liver regeneration.
We have previously shown that deferoxamine (DFO) infusion protected myocardium against reperfusion injury in patients undergoing open heart surgery, and reduced brain edema, intracranial pressure, and lung injury in pigs with acute hepatic ischemia (AHI). The purpose of this research was to study if DFO could attenuate sepsis inflammatory response syndrome (SIRS) and confer renoprotection in the same model of AHI in anesthetized pigs. Fourteen animals were randomly allocated to two groups. In the Group DFO (n=7), 150mg/kg of DFO dissolved in normal saline was continuously infused in animals undergoing hepatic devascularization and portacaval anastomosis. The control group (Group C, n=7) underwent the same surgical procedure and received the same volume of normal saline infusion. Animals were euthanized after 24h. Hematological, biochemical parameters, malondialdehyde (MDA), and cytokines (interleukin [IL]-1β, IL-6, IL-8, IL-10, and tumor necrosis factor-α) were determined from sera obtained at baseline, at 12h, and after euthanasia. Hematoxylin-eosin and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling were used to evaluate necrosis and apoptosis, respectively, in kidney sections obtained after euthanasia. A rapid and substantial elevation (more than 100-fold) of serum IL-6 levels was observed in Group C reaching peak at the end of the experiment, associated with increased production of oxygen free radicals and lipid peroxidation (MDA 3.2±0.1nmol/mL at baseline and 5.5±0.9nmol/mL at the end of the experiment, P<0.05) and various manifestations of SIRS and multiple organ dysfunction (MOD), including elevation of high-sensitivity C-reactive protein, severe hypotension, leukocytosis, thrombocytopenia, hypoproteinemia, and increased serum levels of lactate dehydrogenase (fourfold), alkaline phosphatase (fourfold), alanine aminotransferase (14-fold), and ammonia (sevenfold). In sharp contrast, IL-6 production and lipid peroxidation were completely blocked in DFO-treated animals offering remarkable resistance to the development of SIRS and MOD. Profound proteinuria, strips of extensive necrosis of tubular epithelial cells, and occasional apoptotic tubular epithelial cells were already present in Group C, but not in Group DFO animals at the time of euthanasia. DFO infusion attenuated lipid peroxidation, blocked IL-6 production, and substantially diminished SIRS and MOD, including tubulointerstitial damage in pigs after acute ischemic hepatic failure. This finding shows that iron, IL-6, and lipid peroxidation are important participants in the pathophysiology of renal injury in the course of generalized inflammation and provides novel pathways of therapeutic interventions for renal protection.
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