Aflatoxin exposure in viral hepatitis patients in Turkey.

BACKGROUND/AIMS: Hepatocellular carcinoma is the fifth most common cancer and a major public health problem worldwide. Differences in distribution of hepatocellular carcinoma incidence are probably due to different levels of exposure to hepatocellular carcinoma risk factors: chronic infections with hepatitis B virus (HBV) and aflatoxin exposure in developing countries, and smoking and alcohol abuse in developed countries. Aflatoxin is one of the most important of the environmental toxins that contribute to the pathogenesis of hepatocellular carcinoma, especially in the regions where dietary foodstuffs (peanuts, corn, Brazil nuts, pistachios, spices and figs) are highly contaminated. High aflatoxin levels have been shown in the foodstuffs that are produced in our country. The specific aim of this study was to assess the rate of aflatoxin exposure and to determine some clues about aflatoxin metabolism by measuring and comparing the levels of carcinogenic forms in healthy subjects, in different stages of viral disease, and in different viral hepatitis types. METHODS: This was a cross-sectional observational, single-center study. A total of 203 (male/female: 119/84) viral hepatitis patients who were consecutively admitted to Ankara University, School of Medicine, Gastroenterology Clinic, between January 2006 and June 2007 were enrolled into the study. Sixty-two healthy subjects (male/female: 33/29) with normal blood chemistry and negative viral serology served as controls. Chemical forms AFB1, AFB2, AFG1, and AFG2 were assessed in plasma of study participants by high-performance liquid chromatography. RESULTS: AFB1, AFB2, AFG1, and AFG2 were detected in 24.6%, 17.2%, 22.7%, 18.2% of the 203 patients, respectively, and were significantly higher than in the control group for all chemical forms. Percentage of AFB1-positive patients was significantly higher than in the control group irrespective of disease stage. There was no significant difference between chronic infected patients, cirrhotic patients and patients with Hepatocellular carcinoma with respect to percentage of aflatoxin-positive individuals. CONCLUSIONS: With this study, we have documented that in viral hepatitis patients, aflatoxin exposure is significantly higher than in healthy subjects in Turkey and it may play an important role in the development of hepatocellular carcinoma. Thus, large studies exploring the relation between aflatoxin exposure, viral hepatitis status, and risk of hepatocellular carcinoma development are needed.

Midkine secretion protects Hep3B cells from cadmium induced cellular damage.

AIM: To evaluate role of midkine secretion during Cadmium (Cd) exposure in the human hepatocyte cell line Hep3B cells. METHODS: Different dosages of Cd (0.5-1-5-10 microg/mL) were applied to Hep3B cells and their effects to apoptosis, lactate dehydrogenase (LDH) leakage and midkine secretion were evaluated as time dependent manner. Same experiments were repeated with exogenously applied midkine (250-5000 pg/mL) and/or 5 microg/mL Cd. RESULTS: Cd exposure induced prominent apoptosis and LDH leakage beginning from lower dosages at the 48th h. Cd induced midkine secretion with higher dosages (P < 0.001), (control, Cd 0.5-1-5-10 microg/mL respectively: 1123 +/- 73, 1157 +/- 63, 1242 +/- 90, 1886 +/- 175, 1712 +/- 166 pg/mL). Exogenous 500-5000 pg/mL midkine application during 5 microg/mL Cd toxicity prevented caspase-3 activation (control, Cd toxicity, 250, 500, 1000, 2500, 5000 pg/mL midkine+ Cd toxicity, respectively: 374 +/- 64, 1786 +/- 156, 1545 +/- 179, 1203 +/- 113, 974 +/- 116, 646 +/- 56, 556 +/- 63 cfu) LDH leakage and cell death in Hep3B cells (P < 0.001). CONCLUSION: Our results showed that midkine secretion from Hep3B cells during Cd exposure protects liver cells from Cd induced cellular damage. Midkine has anti-apoptotic and cytoprotective role during Cd toxicity. Further studies are needed to explain the mechanism of midkine secretion and cytoprotective role of midkine during Cd exposure. Midkine may be a promising therapeutic agent in different toxic hepatic diseases.

The effect of K-ATP channel blockage during erythropoietin treatment in renal ischemia-reperfusion injury.

ATP dependent K channels (K-ATP) take part in the Erythropoietin (EPO) induced cardioprotection but these channel activations have role in cytoprotective role of EPO in the renal ischemia reperfusion (IR) damage is still unknown. For this purpose rats were pretreated with EPO (500 IU/kg) and/or K-ATP channel blocker glibenclamide (40 mM/kg) i.p. before bilateral renal IR damage. Renal tissues were used for histological examination and measurement of caspase-3 and TNF-alpha levels. Renal functions were evaluated by glomerular filtration rate (GFR) fractional excretion of sodium (FENa) and potassium (FEK). Renal TNF-alpha and caspase-3 levels were decreased in both glibenclamide and EPO-treated IR rats compared to untreated rats. The protection afforded by the pretreatment with EPO alone was greater than that of administering glibenclamide alone. Application of glibenclamide at the same time partly abolished the cytoprotective effect of EPO treatment. K-ATP mediated cytoprotection is not the main mechanism of protective effect of EPO.

Erythropoietin attenuates hydrogen peroxide-induced damage of hepatocytes.

BACKGROUND/AIMS: High levels of hydrogen peroxide (H2O2) are observed during inflammatory and ischemic states of the liver and usually lead to cellular dysfunction and cytotoxicity. Recently, it has been reported that erythropoietin and mitochondrial K (ATP) channel openers have a protective effect via a pharmacological preconditioning action during ischemia reperfusion injury of the liver and heart. However, it remains unclear as to whether K (ATP) channel blockers can reduce the protective effect of erythropoietin in the H2O2-induced injury of hepatocytes. METHODS: To determine whether erythropoietin treatment decreases H2O2-induced toxicity, we used human hepatocyte cell line Hep3B for assays. Cells were pretreated with different dosages of erythropoietin (0.1-1-10-50 IU/ml) 2 h before H2O2 application. For determination of effects of blockage of mitochondrial K (ATP) channels during erythropoietin treatment, glibenclamide treatment was applied to the medium 2 h before H2O2 toxicity. Cell number, lactate dehydrogenase and caspase- 3 levels were measured in erythropoietin, glibenclamide and/or H2O2-treated groups. RESULTS: Erythropoietin treatment significantly increased cell number at the 24th and 48th h compared to the control group. H2O2 application induced apoptosis and lactate dehydrogenase release from Hep3B cells and decreased cell number. Erythropoietin prevents H2O2 toxicity in hepatocytes. The K channel inhibitor glibenclamide decreased the cytoproliferative and cytoprotective effect of erythropoietin during H2O2 toxicity of Hep3B cells. CONCLUSIONS: Erythropoietin treatment may be considered as a therapeutic agent during oxidative injuries of hepatocytes and its cytoprotective effect is abolished by glibenclamide.