Mechanisms and mediators in hepatic necrosis

Under peroxisome proliferation acyl-CoA oxidase coordinates with catalase to enhance ethanol metabolism

In peroxisomes, acyl-CoA oxidase (ACOX) oxidizes fatty acids and produces H2O2, and the latter is decomposed by catalase. If ethanol is present, ethanol will be oxidized by catalase coupling with decomposition of H2O2. Peroxisome proliferator-activated receptor α (PPARα) agonist WY-14,643 escalated ethanol clearance, which was not observed in catalase knockout (Cat-/-) mice or partially blocked by an ACOX1 inhibitor. WY-14,643 induced peroxisome proliferation via peroxin 16 (PEX16). PEX16 liver-specific knockout (Pex16Alb-Cre) mice lack intact peroxisomes in liver, but catalase and ACOX1 were upregulated. Due to lacking intact peroxisomes, the upregulated catalase and ACOX1 in the Pex16Alb-Cre mice were mislocated in cytosol and microsomes, and the escalated ethanol clearance was not observed in the Pex16Alb-Cre mice, implicating that the intact functional peroxisomes are essential for ACOX1/catalase to metabolize ethanol. Alcohol-associated liver disease (ALD) is a spectrum of liver disorders ranging from alcoholic steatosis to steatohepatitis. WY-14,643 ameliorated alcoholic steatosis but tended to enhance alcoholic steatohepatitis. In mice lacking nuclear factor erythroid 2-related factor 2 (Nrf2-/-), WY-14,643 still induced PEX16, ACOX1 and catalase to escalate ethanol clearance and blunt alcoholic steatosis, which was not observed in the PPARα-absent Nrf2-/- mice (Pparα-/-/Nrf2-/-) mice, suggesting that WY-14,643 escalates ethanol clearance through PPARα but not through Nrf2.

Toxicological Effects of Thimerosal and Aluminum in the Liver, Kidney, and Brain of Zebrafish (Danio rerio)

Vaccination programs in the first years of a child's life are effective and extremely important strategies for the successful eradication of diseases. However, as no intervention is without risks, the metal-based components of some vaccines, such as thimerosal (TMS), a preservative composed of ethylmercury, and aluminum (Al), have begun to generate distrust on the part of the population. Therefore, this study evaluated the effects of exposure to thimerosal and aluminum hydroxide (alone or in mixture) on Danio rerio (zebrafish) specimens. The fish were exposed to thimerosal and/or aluminum hydroxide intraperitoneally. The liver, kidney, and brain were removed for a biochemical biomarker analysis, histopathological analysis, and metal quantification. As a result, we observed changes in the activity of the analyzed enzymes (SOD, GST, GPx) in the kidney and brain of the zebrafish, a reduction in GSH levels in all analyzed tissues, and a reduction in MT levels in the kidney and liver as well as in the brain. Changes in AChE enzyme activity were observed. The biochemical results corroborate the changes observed in the lesion index and histomorphology sections. We emphasize the importance of joint research on these compounds to increase the population's safety against their possible toxic effects.

Hepatoprotective effects of AdipoRon against d-galactosamine-induced liver injury in mice

Adiponectin is an antidiabetic and antiatherogenic adipokine, which plays distinct roles in the balance of energy homoeostasis. As an insulin sensitizing hormone, adiponectin exerts multiple biological effects by the specific receptors (AdipoR1 and AdipoR2), through activation of AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor (PPAR)α pathways. AdipoRon, an orally active synthetic small-molecule AdipoR agonist, shows very similar effects to adiponectin in vitro and in vivo, which could be a promising therapeutic approach for obesity-related disorders. In view of the regulatory effects of adiponectin or AdipoRon on inflammatory response and energy metabolism, they might be endowed a curative potential for tissue damage. Hence, its effects and possible mechanism were investigated. In vitro studies on hepatocytes (L02) and macrophages (RAW264.7) suggested a protective and anti-inflammatory potential of AdipoRon. The effects were verified in acute hepatic injury mice induced by d-galactosamine (D-GalN): hepatic lesions were restored by AdipoRon or bicyclol (positive reference drug) pretreatment, which were characterized by a significant increase in serological and hepatic biomarkers (AST, ALT, MDA and NOSs). Besides, AdipoRon attenuated the inflammation in the liver, characterized by the dwindling proinflammatory macrophage infiltration, as well as the shrinkage of tumor necrosis factor-α (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6); meanwhile conversely promoted AMPK activation by phosphorylation. Combined with liver histopathology, these results demonstrated the hepatoprotective effects of AdipoRon against D-GalN-induced damage, which might be ascribed to the attenuation of inflammation, inhibition of free radical reactions, as well as enhancement of liver energy metabolism.

Role of IL6 –174C/G gene polymorphism in development of chronic HCV infection

In the investigation it has been estimated the functional importance of gene interleukin 6 (IL6) polymorphism in progressing the chronic hepatitis C virus (HCV) infection. It has been determined the analysis of polymorphism –174 C/G frequency in gene IL6 promote zone at healthy donors and patients with chronic HCV-infection who are the Caucasian representatives of Tomsk region. The genotype GG carriers definitely dominated at patients with high activity rate of inflammatory process: it shows that G allele carriership have an impact on aggravation of inflammatory process activity in the liver patients with HCV-infections. In contrast to, carriership of C/G and C/C genotypes of polymorphism –174 C/G of gene IL6 have met more often at patients with minimal and moderate degree of inflammatory process.

Hepatoprotective effects of whey protein on D-galactosamine-induced hepatitis and liver fibrosis in rats

The hepatoprotective effects of whey protein on two injections of D-galactosamine (300 mg/kg, i.p.) were investigated in rats fed a modified AIN-93M diet formulated with a protein source of casein or whey for 16 d. The whey protein-containing diet clearly suppressed an increase in plasma alanine and aspartate aminotransferase activity, lactate dehydrogenase and bilirubin, which are hepatitis markers, and also hyaluronic acid, a fibrosis marker. In addition, it suppressed histopathological signs of portal fibrosis, bile duct proliferation, and perivenular sclerosis. These results suggest that supplementation with whey protein can help prevent the development of hepatitis and portal fibrosis.

Effect of Tridax procumbens on liver antioxidant defense system during lipopolysaccharide-induced hepatitis in D-galactosamine sensitised rats

The present study was carried out to assess the effect of chloroform insoluble fraction of ethanolic extract of Tridax procumbens (TP) against D-Galactosamine/Lipopolysaccharide (D-GalN/LPS)-induced hepatitis in rats. Induction of rats with D-GalN/LPS (300 mg/kg body weight/30 microg/kg body weight) led to a marked increase in lipid peroxidation as measured by thiobarbituric acid reactive substances (TBARS) in liver. Further there was a decline in the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione s-transferase and the levels of non-enzymic antioxidants namely reduced glutathione, vitamin C and vitamin E. These biochemical alterations were normalised upon pretreatment with TP extract. Thus, the above results suggest that TP (300 mg/kg body weight orally for 10 days) is very effective in allievating the D-GalN/LPS-induced oxidative stress suggesting its antioxidant property.

The role of nitric oxide in hepatic metabolism

Nitric oxide (NO) may regulate hepatic metabolism directly by causing alterations in hepatocellular (hepatocyte and Kupffer cell) metabolism and function or indirectly as a result of its vasodilator properties. Its release from the endothelium can be elicited by numerous autacoids such as histamine, vasoactive intestinal peptide, adenosine, ATP, 5-HT, substance P, bradykinin, and calcitonin gene-related peptide. In addition, NO may be released from the hepatic vascular endothelium, platelets, nerve endings, mast cells, and Kupffer cells as a response to various stimuli such as endotoxemia, ischemia-reperfusion injury, and circulatory shock. It is synthesized by nitric oxide synthase (NOS), which has three distinguishable isoforms: NOS-1 (ncNOS), a constitutive isoform originally isolated from neuronal sources; NOS-2 (iNOS), an inducible isoform that may generate large quantities of NO and may be induced in a variety of cell types throughout the body by the action of inflammatory stimuli such as tumor necrosis factor and interleukin (IL)-1 and -6; and NOS-3 (ecNOS), a constitutive isoform originally located in endothelial cells. Another basis for differentiation between the constitutive and inducible enzymes is the requirement for calcium binding to calmodulin in the former. NO is vulnerable to a plethora of biologic reactions, the most important being those involving higher nitrogen oxides (NO2-), nitrosothiol, and nitrosyl iron-cysteine complexes, the products of which (for example, peroxynitrite), are believed to be highly cytotoxic. The ability of NO to react with iron complexes renders the cytochrome P450 series of microsomal enzymes natural targets for inhibition by NO. It is believed that this mechanism provides negative feedback control of NO synthesis. In addition, NO may regulate prostaglandin synthesis because the cyclooxygenases are other hem-containing enzymes. It may also be possible that NO-induced release of IL-1 inhibits cytochrome P450 production, which ultimately renders the liver less resistant to trauma. It is believed that Kupffer cells are the main source of NO during endotoxemic shock and that selective inhibition of this stimulation may have future beneficial therapeutic implications. NO release in small quantities may be beneficial because it has been shown to decrease tumor cell growth and levels of prostaglandin E2 and F2 alpha (proinflammatory products) and to increase protein synthesis and DNA-repair enzymes in isolated hepatocytes. NO may possess both cytoprotective and cytotoxic properties depending on the amount and the isoform of NOS by which it is produced. The mechanisms by which these properties are regulated are important in the maintenance of whole body homeostasis and remain to be elucidated.

ASTRO Research Fellowship: apoptosis as a predictor of tumor response to radiation in stage IB cervical carcinoma. American Society for Therapeutic Radiology and Oncology

PURPOSE

Levels of apoptosis predict for tumor responsiveness to radiation in various animal systems. To investigate the potential role of apoptosis as a predictor of response in human tumors, a retrospective review was undertaken of patients with adenocarcinoma of the cervix whose primary lesion at presentation measured at least 4 cm and who underwent definitive radiation therapy. A previous report had indicated that roughly half this group of patients should have a long-term relapse free survival.

METHODS AND MATERIALS

Pretreatment biopsy specimens of 44 patients with Stage IB adenocarcinoma of the cervix, whose primary lesion at presentation measured at least 4 cm in greatest dimension, were scored for apoptosis by two independent investigators without knowledge of the treatment outcome, and the results were averaged. Actuarial methods were used to assess overall survival, disease-free survival, determinate survival, and local control as a function of the baseline level of apoptosis. Patients ranged in age from 21 to 87 years and were treated with definitive radiotherapy between 1964 and 1989. Follow-up for the surviving patients ranged from 1 to 278 months, with a mean of 101 months.

RESULTS

Patients whose tumors had a baseline level of apoptosis above the median value (2%) had a better overall survival than those with lower levels of apoptosis (p = 0.056). A similar trend for disease-free survival (p = 0.32) and determinate survival (p = 0.27) did not reach statistical significance, perhaps because of the small number of patients. Because only 6 of the 44 patients (13%) had a local tumor failure, it was not possible to establish a correlation between the pretreatment level of apoptosis and the local tumor control by radiation.

CONCLUSION

The baseline level of apoptosis predicted for survival in patients with Stage IB cervical adenocarcinoma. Further investigation of the measurement of apoptosis as a potential predictive assay is warranted in other human tumor systems.