Normal cell functions and integrity of cell structures may be broken via considerable reactivity of ROS. The organism has enzymatic (e.g. superoxide dismutase, catalase, glutathione peroxidase) and non-enzymatic (e.g. vitamin C, vitamin E) antioxidant mechanisms that work as scavenger for this harmful ROS. Radical-scavenging antioxidants are consumed by the increased free radical activity associated with several conditions, and the total antioxidant response has been used to indirectly assess of free radical activity. The effects of various antioxidants in plasma are additive and the cooperation of antioxidants in human serum provides protection of the organism against attacks by free radicals [3
]. Therefore, the measurement of TAR may reflect accurately the antioxidant status of the organism [3
Oxidative stress can be defined as an increase in oxidants and/or a decrease in antioxidant capacity. Although determination of either oxidants or antioxidant components alone may give information about the oxidative stress, determination of oxidants along with antioxidants is more useful in this context. Therefore, oxidants and anti-oxidant capacity should be measured simultaneously to assess oxidative stress more exactly. In addition, the ratio of the total plasma peroxide level o TAR, regarded as OSI and an indicator of oxidative stress, reflects the redox balance between oxidation and anti-oxidation. Recently, it has been reported that OSI may reflect the oxidative status more accurately than TAR or total peroxide level alone [13
Various methods have been developed for the measurement of total antioxidant status. However, there is not yet an accepted "gold standard" reference method [18
], and decisions concerning standardization, and the terms and units used for the measurement of TAR have not yet been made [15
]. This implies that this topic needs to be studied further [12
]. The most widely used methods for TAR measurement are colorimetric, or involve either fluorescence or chemiluminescence [22
]. However, the fluorescence and chemiluminescence methods need sophisticated techniques, are not appropriate for routine usage and not present in most routine clinical biochemistry laboratories.
In the present study, antioxidant capacity of subjects was determined using TAR, and oxidants and antioxidant capacity were determined simultaneously to determine oxidative stress. The novel method that used in the present study provides several major advantages in comparison with other currently available methods. It is simple and cheap, and can easily be fully automated. It is also reliable and sensitive, and does not interact with commonly occurring serum components such as bilirubin, serum lipids, and anticoagulants. Accurate measurements of TAR can be obtained as little as 10 minutes, making this assay eminently suitable for the clinical biochemistry laboratory [12
The evidence of oxidative damage in human chronic viral hepatitis is accompanied by a significant rise of the plasma level of the fibrogenic cytokines TNFa and TGFb. In particular, the latter cytokine was shown increased already in plasma of patients with mild tissue inflammation in direct relation with the degree of tissue damage and fibrosis [5
]. In addition, excess amounts of reactive species generated in inflamed tissues can cause injury to host cells and also induce DNA damage and mutations [26
] and oxidative DNA damage has been suggested to play an important role in the development of HCC [6
In several studies [7
], increase in oxidative components or decrease in antioxidants or both have been reported in subjects with either acute or chronic HBV infection. Total antioxidant capacity in either acute or chronic HBV infection was measured in only in study of Irhsad et al [11
]. The remaining was used individual antioxidants measurement to assess antioxidant response of the organism. At the same way, simultaneously measurement of the oxidants and antioxidant components of the plasma in CHB infection was performed in only at study of Demirdag et al [9
The information in the literature about the antioxidant components in subjects with cirrhosis due to HBV infection is limited. Irhad et al [11
] found that total antioxidant capacity of subjects either with cirrhosis due to HBV infection or other liver disease due to viral etiology is either comparable to or higher than control. To our knowledge, there is no information in the literature about the oxidants in subjects with cirrhosis due to HBV infection, and neither oxidants nor antioxidants in inactive HbsAg carrier subjects.
In order to reflect the true state of oxidative stress in the liver, measurement of lipid peroxidation markers and antioxidant components in hepatic tissue is more ideal than plasma. Nevertheless, ethical and practical considerations make this very difficult for research purposes. Liver biopsy caries a significant morbidity and even mortality risk and it is impossible to perform multiple tests with current techniques on very limited amounts of biopsy specimen that obtained in needle biopsy. Thus, in the present study, we have chosen to perform the measurement of oxidative stress markers in plasma samples. Indeed, in various disorders of the liver, increase in oxidants and/or decrease in antioxidants have been shown in both plasma and liver tissue samples [27
It is well known that serum bilirubin has an antioxidant property [15
]. Additionally, poor nutritional status caused modifications to the enzymatic antioxidant systems, with a lower ability to reduce oxidative compounds and a state of lipid peroxidation [29
]. These two factors are frequently found in subjects with advanced stages of cirrhosis. Thus, in the present study, we included only the subjects with compensated Child A cirrhosis to evaluate the effects of cirrhosis due to HBV on oxidative status more accurately, and to exclude the effects of other additional factors.
In the present study, we found that TAR of CHB subjects was equivalent to inactive HBsAg carrier and controls. However, total peroxide level, a parameter of oxidative stress, and OSI was significantly higher in CHB subjects than inactive HBsAg carrier and controls. At the same way, there was a strict positive correlation between ALT level, and total peroxide level and OSI in CHB subjects, while no correlation between ALT level and TAR. Additionally, there was an inverse correlation between total peroxide level and OSI with TAR in cirrhotic subjects vs. inactive HBV carriers and controls.
Inactive HBsAg carrier and control subjects had comparable results in term of TAR, total lipid peroxide level and OSI. The lack of increase in TAR in the presence of increased oxidative components, and the strict correlation of ALT levels with total peroxide level and OSI are suggestive for the role of oxidative stress in the pathogenesis of CHB infection.
In the lightening of these findings, we concluded that oxidative stress may have a critical role in hepatic injury and is associated with the severity of disease and the replication status of virus in hepatitis B infection. The novel automated calorimetric assay is a useful, reliable, simple and easily applicable method in the assesment of the total plasma antioxidant response in various forms of hepatitis B virus infection.