Effect of age and hypoxia/reoxygenation on mRNA expression of antioxidative enzymes in rat liver and kidneys

The influence of a short-time isobaric hypoxia as well as reoxygenation on markers of oxidative stress (MDA, total SOD, GSH) and on the mRNA expression of the antioxidative enzymes (Cu/Zn-and Mn-SOD, catalase, GSH reductase and GSH peroxidase) has been studied in liver and kidneys of young (6 months) and old (22–25 months) Wistar rats.

In livers of old animals, the concentration of GSH, the activity of SOD, and the mRNA expression of the antioxidative enzymes (except Mn-SOD) points to a restricted protection against oxidative stress or a lower production of ROS compared to young animals. Hypoxia resulted in a significant decrease of enzyme gene expression in both age groups. Reoxygenation caused an increase in mRNA of Cu/Zn-SOD and GPX in livers of young and of Mn-SOD in livers of old animals.

In kidneys, gene expression of Cu/Zn-SOD, GSH reductase, and GPX was significantly higher in old animals compared to young animals. Whereas hypoxia caused a decrease of gene expression in the livers, it lead to a significant increase of Cu/Zn-SOD, catalase, and GSH reductase mRNA in kidneys of young rats. A reduced gene expression was observed after reoxygenation. In old kidneys, the expression of all enzymes except for catalase progressively declined in the hypoxic and reoxygenation groups. These data show that gene expression of antioxidative enzymes is affected by age and significantly differs between liver and kidney.     

Measurement of serum paraoxonase-1 activity in the evaluation of liver function

Paraoxonase-1 （PON1） is an esterase and lactonase synthesized by the liver and found in the circulation associated with high-density lipoproteins. The physiological function of PON1 seems to be to degrade specific oxidized cholesteryl esters and oxidized phospholipids in lipoproteins and cell membranes. PON1 is, therefore, an antioxidant enzyme. Alterations in circulating PON1 levels have been reported in a variety of diseases involving oxidative stress including chronic liver diseases. Measurement of serum PON1 activity has been proposed as a potential test for the evaluation of liver function. However, this measurement is still restricted to research and has not been extensively applied in routine clinical chemistry laboratories. The reason for this restriction is due to the problem that the substrate commonly used for PON1 measurement, paraoxon, is toxic and unstable. The recent development of new assays with non-toxic substrates makes this proposal closer to a practical development. The present editorial summarizes PON1 biochemistry and function, its involvement with chronic liver impairment, and some aspects related to the measurement of PON1 activity in circulation.     

Efficacy of Hibiscus sabdariffa and Telfairia occidentalis in the attenuation of CCl4-mediated oxidative stress

ObjectiveTo assess the efficacy of Hibiscus sabdariffa (H. sabdariffa) and Telfairia occidentalis (T. occidentalis) extracts in the attenuation of CCl₄-mediated oxidative stress.MethodsSeventy-two healthy matured male albino rats weighing between (120±20) g were divided into 6 groups (A-F) in a 2×6 factorial experiment using completely randomized design. Rats in Group A received only water, B received 1 mL/kg CCl₄, C received 300 mg/kg, D received 600 mg/kg, E received CCl₄+300 mg/kg while F received CCl₄+600 mg/kg for each of the extract, respectively. Semen from epididymes was obtained for sperm analysis while blood was obtained through cardiac puncture for biochemical analysis, after the treatment regimen.ResultsOur results showed that CCl₄ induction elevated aspartate aminotransferase, alanine transaminase, alkaline phosphatase, total protein, globulin levels significantly (P<0.05) while albumin was reduced. For sperm profile after CCl₄ induction, sperm count, viability and motility were significant (P<0.05) reduced while sperm head abnormality increased. However, administering H. sabdariffa and T. occidentalis extracts at the doses of 300 and 600 mg/kg caused the reversal of these effects significantly.ConclusionsImplicitly, the implication of our results is that H. sabdariffa and T. occidentalis extracts might be ted and optimized for the management of oxidative stress-related organ injuries, including infertility, though further researches are needed.     

快速老化小鼠P8肝脏组织形态学变化及氧化损伤的研究

目的 评价快速老化小鼠P8(SAMP8)作为肝脏衰老动物模型的可行性,并探讨氧化应激在SAMP8肝脏衰老过程的作用机制. 方法 选择9月龄雄性SAMP8为研究对象,抗快速老化小鼠R1亚系(SAMRl)为模型对照,采用苏木精-伊红(HE)、苏丹Ⅳ和Masson染色观察两组小鼠肝脏的组织病理学改变,组织化学染色法测定肝脏衰老相关β-半乳糖苷酶活性,化学比色法测定肝组织匀浆中丙二醛(MDA)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)的活性. 结果与SAMR1组比较,SAMP8组肝组织出现肝细胞广泛的脂肪变性、局灶性坏死及炎性细胞浸润等退行性改变,衰老相关β-半乳糖苷酶染色阳性细胞明显增多(SAMP8组为78.1±11.0,SAMR1组为23.9±8.8,t=10.887,P<0.01),SOD、CAT、GSH-Px活力明显降低(SOD:SAMP8组为214.8±34.8,SAMR1组为295.3±29.7,t=4.975,P<0.01;CAT:SAMP8组为23.0±4.0,SAMR1组为36.3±8.3,t=4.084,P<0.01;GSH-Px:SAMP8组为524.0±74.2,SAMR1组为648.4±102.8,t=2.776,P<0.05),MDA含量明显增高(SAMP8组为2.3±0.2,SAMR1组为1.8±0.1,t=6.329,P<0.01). 结论 SAMP8小鼠可作为研究肝脏衰老的动物模型,氧化应激在SAMP8肝脏衰老过程中可能起重要作用.     

Effects of the association of aging and obesity on lipids, lipoproteins and oxidative stress biomarkers: A comparison of older with young men

In this study, plasma lipids, lipoproteins and markers of oxidant/antioxidant status were investigated in young (n = 45) and older (n = 40) obese men and compared to those in young (n = 65) and older (n = 55) normal weight controls. The purpose was to determine whether obesity exacerbates or not lipid, lipoprotein abnormalities and oxidative stress in older men.Our findings showed that all obese patients had increased plasma triglyceride, cholesterol, LDL-cholesterol, -triglyceride and HDL-triglyceride levels concentrations compared to controls (P < 0.01). However, the younger obese men had relatively larger and accentuated changes in plasma lipids and lipoproteins than the older patients. Additionally, total antioxidant capacity (ORAC), vitamins C and E were lower while hydroperoxides and carbonyl proteins were higher in young and older obese patients compared to their respective controls (P < 0.001). Erythrocyte antioxidant SOD and catalase activities were enhanced in obese young patients, but reduced in obese older men. Glutathione peroxidase activity was low in obesity irrespective of age. In multiple regression analysis, BMI significantly predicted total cholesterol, LDL-C, LDL-TG and HDL-TG (P < 0.0001). These relationships were not modified by age. BMI alone was a not a significant predictor for ORAC, vitamins C, E, catalase and Glutathione peroxidase. However, the interaction BMI–age significantly predicted these parameters and explained 28–45% of their changes. BMI was a significant predictor of SOD, carbonyl proteins and hydroperoxides. This effect became more significant (P < 0.0001) and worsened with BMI–age interaction.In conclusion, lipoprotein metabolism and oxidant/antioxidant status are altered in obesity irrespective of age. However, obesity-related lipid and lipoprotein alterations were attenuated while oxidative stress was aggravated in older adults.     

Clinical use of serum enzymes in liver disease

Some of the many enzymes found in hepatocytes can be measured in the serum and are used as tests of liver function. We now review the current knowledge of their physiology and pathophysiology and outline their clinical usefulness. We divide them into two categories: enzymes that primarily reflect cholestasis, such as the alkaline phosphatase, the 5-nucleotidase, and the gamma-glutamyl transpeptidase, and those that primarily reflect hepatocellular necrosis, such as the aminotransferases. We also briefly discuss several enzymes of more limited usefulness.     

Burden of liver disease in Europe: Epidemiology and analysis of risk factors to identify prevention policies

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Abnormal liver enzymes: A review for clinicians

Liver biochemical tests are some of the most commonly ordered routine tests in the inpatient and outpatient setting, especially with the automatization of testing in this technological era. These tests include aminotransferases, alkaline phosphatase, gamma-glutamyl transferase, bilirubin, albumin, prothrombin time and international normalized ratio (INR). Abnormal liver biochemical tests can be categorized based on the pattern and the magnitude of aminotransferases elevation. Generally, abnormalities in aminotransferases can be classified into a hepatocellular pattern or cholestatic pattern and can be further sub-classified based on the magnitude of aminotransferase elevation to mild [< 5 × upper limit of normal (ULN)], moderate (> 5-< 15 × ULN) and severe (> 15 × ULN). Hepatocellular pattern causes include but are not limited to; non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, alcohol use, chronic viral hepatitis, liver cirrhosis (variable), autoimmune hepatitis, hemochromatosis, Wilson’s disease, alpha-1 antitrypsin deficiency, celiac disease, medication-induced and ischemic hepatitis. Cholestatic pattern causes include but is not limited to; biliary pathology (obstruction, autoimmune), other conditions with hyperbilirubinemia (conjugated and unconjugated). It is crucial to interpret these commonly ordered tests accurately as appropriate further workup, treatment and referral can greatly benefit the patient due to prompt treatment which can improve the natural history of several of the diseases mentioned and possibly reduce the risk of progression to the liver cirrhosis.     

Influence of sex hormonal status on alcohol-induced oxidative injury in male and female rat liver

BACKGROUND: Oxidative stress contributes to the development of liver injury after chronic alcohol intake. Women exhibit greater sensitivity to alcohol-induced liver disease than do men. The aim of the study was to determine the relationship between the sex hormone status of male and female rats and the degree of alcohol-induced oxidative stress in the liver. METHODS: Male and female rats were pair-fed a liquid diet that contained 36% of their total daily calories as ethanol (EtOH group) or maltose (control group). Blood and liver samples were collected at the end of 8 weeks of diet. RESULTS: Male EtOH rats experienced a reduction in plasma testosterone (T) and an increase in estradiol (E2) levels, with an increase in their calculated E2/T ratio with respect to their controls. Malonaldehyde (MDA) levels, an index of lipid peroxidation, and protein carbonyl content, an index of protein oxidation, in the liver were greater among the EtOH groups in females than in males. In males, an inverse correlation was found between hepatic MDA and circulating T levels, and a direct correlation was disclosed between MDA and estradiol levels. In addition, the hepatic histopathological score correlated inversely with the plasma T levels and directly with the calculated E2/T ratio, an index of feminization. CONCLUSIONS: Alcohol-induced oxidative injury, which contributes to hepatic injury in both male and female rats, is enhanced in females compared with males. A role for plasma T levels in protecting male rat liver from ethanol-induced oxidative injury can be hypothesized.     

One-hour post-load plasma glucose levels are associated with elevated liver enzymes

Background and aims

Glucose-tolerant subjects who have 1-h post-load glucose levels ≥155 mg dl⁻¹ (normal glucose tolerance (NGT)-1h-high) are at an increased risk of developing type 2 diabetes. Prospectively conducted studies indicated that high levels of liver enzymes are predictors of a tendency to develop type 2 diabetes; however, it is unknown whether the NGT-1h-high subjects are at increased risk for secreting higher levels of liver biomarkers.

Methods and results

In this study, oral glucose tolerance tests (OGTTs) were performed in a cohort of 1000 non-diabetic Caucasians and levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) were measured in these subjects. The NGT-1h-high subjects had increased levels of ALT and GGT, but not AST, as compared with the NGT-1h-low. Following adjustment for age and gender, the ALT, AST and GGT levels were all found to be significantly correlated with body mass index (BMI), waist circumference, blood pressure, triglycerides as well as fasting and post-challenge glucose and insulin levels. In a logistic regression analysis adjusted for age and gender, NGT-1h-high subjects were found to be at increased risk of having ALT levels in the highest quartile as compared with NGT-1h-low subjects (odds ratio (OR) = 1.71; 95% confidence interval (CI): 1.16-2.52). In addition, NGT-1 h-high subjects exhibited an increased risk for having GGT levels in the highest quartile (OR = 1.50; 95%CI: 1.02-2.17). These associations remained significant after adjustment for BMI, blood pressure and lipids, but were not significant following further adjustment for an insulin sensitivity index. NGT-1h-high subjects were at increased risk of having AST levels in the highest quartile as compared with NGT-1h-low subjects (OR = 1.51; 95%CI: 1.04-2.22). This association ceased to be significant following adjustment for BMI, blood pressure and lipids.

Conclusions

These data suggest that a 1hPG ≥ 155 mg dl⁻¹ cut-off may facilitate the identification of NGT individuals at risk of developing liver abnormalities.     

The relative expression of hepatocellular and cholestatic liver enzymes in adult patients with liver disease

Introduction and objectivesHepatocellular liver injury is characterized by elevations in serum alanine (ALT) and aspartate (AST) aminotransferases while cholestasis is associated with elevated serum alkaline phosphatase (ALP) levels. When both sets of enzymes are elevated, distinguishing between the two patterns of liver disease can be difficult. The aim of this study was to document the predicted ranges of serum ALP values in patients with hepatocellular liver injury and ALT or AST values in patients with cholestasis.Materials and methodsLiver enzyme levels were documented in adult patients with various types and degrees of hepatocellular (non-alcoholic fatty liver disease, hepatitis B and C, alcohol and autoimmune hepatitis) and cholestatic (primary biliary cholangitis and primary sclerosing cholangitis) disease.ResultsIn 5167 hepatocellular disease patients with ALT (or AST) values that were normal, 1–5×, 5–10× or >10× elevated, median (95% CI) serum ALP levels were 0.64 (0.62–0.66), 0.72 (0.71–0.73), 0.80 (0.77–0.82) and 1.15 (1.0–1.22) fold elevated respectively. In 252 cholestatic patients with ALP values that were normal, 1–5× or >5× elevated, serum ALT (or AST) values were 1.13 (0.93–1.63), 2.47 (2.13–2.70) and 4.57 (3.27–5.63) fold elevated respectively. In 56 patients with concurrent diseases, ALP levels were beyond predicted values for their hepatitis in 38 (68%) and ALT (or AST) values beyond predicted values for their cholestatic disorder in 24 (43%).ConclusionsThese data provide health care providers with predicted ranges of liver enzymes in patients with hepatocellular or cholestatic liver disease and may thereby help to identify patients with concurrent forms of liver disease.     

腹腔镜手术对肝功能变化的影响

目的 了解腹腔镜手术对肝功能变化的影响以及探讨其可能的发生机制。方法 286例腹腔镜胆囊切除术（LC）患者被随机分为a,b2组，在术前及手术后第1，2，7天接受肝功能检测。把40例开腹胆囊切除术（OC）患者的手术前，后肝功能与LC进行对照。另外，18例腹腔镜结，直肠癌手术（LCR）患者与23例开腹结，直肠癌（OCR）手术的患者也参与了研究。结果 LC与LCR患者的血清谷丙转氨酶（ALT）与谷草转氨酶（AST）与术前比较，都有显著性差异（P＜0．05）。LC与OC，LCR与OCR相比，ALT术后24h与48h均有显著性差异（P＜0．05）。同样，LC与OC，LCR与OCR相比，AST术后24h与48h也均有显著性差异（P＜0．05）。同时也对功能指标进行了检测与数据处理，未发现有意义的改变。结论 腹腔镜手术可导致血清肝转移酶有统计学意义的短暂性增高。CO2气腹是造成血清肝转移酶变化的主要原因。这种血清肝脏酶学的短暂性改变对大多数接受腹腔镜手术的患者不会造成不良影响，无临床意义。     

Genetic polymorphisms of genes coding to alcohol-metabolizing enzymes in western Mexicans: association of CYP2E1*c2/CYP2E1*5B allele with cirrhosis and liver function

Background: Alcoholic cirrhosis constitutes a major public health problem in the world where ADH1B, ALDH2, and CYP2E1 polymorphisms could be playing an important role. We determined ADH1B*2, ALDH2*2, and CYP2E1*c2 allele frequencies in healthy control individuals (C) and patients with alcoholic cirrhosis (AC) from western Mexico. Methods: Ninety C and 41 patients with AC were studied. Genotype and allele frequency were determined through polymerase chain reaction‐restriction fragment length polymorphisms. Results: Polymorphic allele distribution in AC was 1.6%ADH1B*2, 0.0%ALDH2*2, and 19.5%CYP2E1*c2; in C: 6.1%ADH1B*2, 0%ALDH2*2, and 10.6%CYP2E1*c2. CYP2E1*c2 polymorphic allele and c1/c2 genotype frequency were significantly higher (p < 0.05 and p < 0.01, respectively) in patients with AC when compared to C. Patients with AC, carrying the CYP2E1*c2 allele, exhibited more decompensated liver functioning evaluated by total bilirubin and prothrombin time, than c1 allele carrying patients (p < 0.05). Cirrhosis severity, assessed by Child’s Pugh score and mortality, was higher in patients carrying the c2 allele, although not statistically significant. Conclusions: In this study, CYP2E1*c2 allele was associated with susceptibility to AC; meanwhile, ADH1B*2 and ALDH2*2 alleles were not. CYP2E1*c2 allele was associated with AC severity, which could probably be attributed to the oxidative stress promoted by this polymorphic form. Further studies to clearly establish CYP2E1*c2 clinical relevance in the development of alcohol‐induced liver damage and its usefulness as a probable prognostic marker, should be performed. Also, increasing the number of patients and including a control group conformed by alcoholic patients free of liver damage may render more conclusive results. These findings contribute to the understanding of the influence of gene variations in AC development among populations, alcohol metabolism, and pharmacogenetics.     

褪黑素对糖尿病大鼠肾脏抗氧化物酶的影响

与正常大鼠比较,STZ诱发的糖尿病大鼠肾与血清的丙二醛水平升高,以及抗氧化物酶活性降低,在褪黑素治疗后均见明显改善,同时伴随出现尿白蛋白排泄率、血尿酸、血脂谱以及肾重对体重的比值等的降低。     

Alcoholic liver injury:Influence of gender and hormones

This article discusses several subjects pertinent to a consideration of the role of gender and hormones in alcoholic liver injury (ALI). Beginning with an overview of factors involved in the pathogenesis of ALI, we review changes in sex hormone metabolism resulting from alcohol ingestion, summarize research that points to estrogen as a cofactor in ALI, consider evidence that gut injury is linked to liver injury in the setting of alcohol, and briefly review the limited evidence regarding sex hormones and gut...     

Novel interactions of mitochondria and reactive oxygen/nitrogen species in alcohol mediated liver disease

Mitochondrial dysfunction is known to be a contributing factor to a number of diseases including chronic alcohol induced liver injury. While there is a detailed understanding of the metabolic pathways and proteins of the liver mitochondrion, little is known regarding how changes in the mitochondrial proteome may contribute to the development of hepatic pathologies.Emerging evidence indicates that reactive oxygen and nitrogen species disrupt mitochondrial function through post-translational modifications to the mitochondrial proteome. Indeed, various new affinity labeling reagents are available to test the hypothesis that post-translational modification of proteins by reactive species contributes to mitochondrial dysfunction and alcoholic fatty liver disease. Specialized proteomic techniques are also now available, which allow for identification of defects in the assembly of multi-protein complexes in mitochondria and the resolution of the highly hydrophobic proteins of the inner membrane. In this review knowledge gained from the study of changes to the mitochondrial proteome in alcoholic hepatotoxicity will be described and placed into a mechanistic framework to increase understanding of the role of mitochondrial dysfunction in liver disease.     

Polyenylphosphatidylcholine protects against alcohol but not iron-induced oxidative stress in the liver

BACKGROUND: We reported before that, in baboons, the alcohol-induced oxidative stress in the liver is associated with depletion of dilinoleoylphosphatidylcholine [the major component of polyenylphosphatidylcholine (PPC)] and that both can be corrected by the administration of PPC, but we did not determine whether this protection extended to iron-induced oxidative stress. METHODS: To compare the effects of PPC on alcohol- and iron-induced hepatic oxidative stress, 56 Sprague Dawley male rats were pair-fed nutritionally adequate liquid diets containing ethanol (36% of energy) or isocaloric carbohydrate and PPC (3 mg/ml) or safflower oil (2.73 mg/ml), with or without 5 mg/ml carbonyl iron for 2 months. Markers of oxidative stress (4-hydroxynonenal and reduced glutathione), antioxidants (vitamin E, ubiquinol-9, and ubiquinol-10), and phosphatidylcholine (PC) species were assessed by HPLC and/or gas chromatography/mass spectrometry. RESULTS: Alcohol feeding increased hepatic 4-hydroxynonenal 3-fold and decreased glutathione by 19%, ubiquinol-10 by 53%, and PC species containing arachidonate (palmitoyl- and stearoylarachidonoylphosphatidylcholines by 24% and 21%, respectively) and total phospholipids by 14%. PPC feeding prevented the rise of 4-hydroxynonenal, restored glutathione, and increased the hepatic content of dilinoleoylphosphatidylcholine and of some other PC carrying polyunsaturated fatty acids. Administration of iron alone increased hepatic iron, doubled 4-hydroxynonenal and glutathione, whereas it decreased vitamin E, ubiquinol-9, total phospholipids, and several polyunsaturated PC. Alcohol given with iron further exacerbated the hepatic oxidative stress, as documented by the increase of 4-hydroxynonenal and the decrease in glutathione and ubiquinols-10. PPC did not prevent this oxidative stress, although it increased hepatic glutathione. Hepatic dilinoleoylphosphatidylcholine content was comparable with and without dietary iron. CONCLUSIONS: PPC prevents the alcohol-induced oxidative stress but only in the absence of iron overload.     

Oxidative stress signaling underlying liver disease and hepatoprotective mechanisms

Oxidative stress is a redox imbalance between pro-oxidants and antioxidants in favour of the former ones, leading to different responses depending on the level of pro-oxidants and the duration of the exposure. In this article, we discuss the damaging or cytoprotective signaling mechanisms associated with oxidative stress by addressing (1) the role of prolonged and severe oxidative stress and insulin resistance as determinant factors in the pathogenesis of non-alcoholic fatty liver disease associated with obesity, which, with the concurrence of nutritional factors, may determine the onset of fatty liver and its progression to steatohepatitis; and (2) the development of an acute and mild pro-oxidant state by thyroid hormone administration, which elicits the redox up-regulation of the expression of proteins affording cell protection, as a preconditioning strategy against ischemia-reperfusion liver injury.