ABSTRACT
Catalase enzyme plays an important role in the anti-oxidation defense of body so it is important to measure its activity. Nowadays catalase activity measurement is performed by expensive imported kits in various scientific fields. The purpose of this study was to design a sensitive fluorimetry method for measuring catalase activity with improved sensitivity, accuracy and speed. In this study, the reaction of hydrogen peroxide with peroxidase [as a reaction accelerator] was used in fluorimetry for catalase activity measuring in serum samples in order to increase the sensitivity of the assay. The sensitivity and intra- and inter-assay accuracy, verification test, recovery and parallelism tests, comparison method and correlation and coherence investigation methods were also performed. In order to increase the accuracy and speed of reading, the assay was performed in microplates and reading was done in fluorimetry plates. The percentage of intra- and inter-assay variation coefficients were measured 3.8-6.6% and 4.1-7.3%, respectively. Comparison of the results of mentioned method for 50 serum samples with common colorimetric method showed a good correlation [0.917]. In assessing the accuracy, the recovery percent was obtained 91% to 107%. The test sensitivity was measured 0.02 IU/ml. The fluorimetry method by microplate reading has a sufficient precision, accuracy and efficiency for catalase activity measuring as well as speed of measurement. Thus it can be an alternative method to conventional imported colorimetric methods
ABSTRACT
Transcriptional silencing of tumor suppressor genes and tumor related genes like GSTP1 by methylation of promotor region CpG island is believed to be an important mechanism in tumorigenesis. The GSTP1 gene encodes the enzyme glutathione S-transferase Pi which defends the cells against oxidative damage and electrophilic carcinogens. To gain insight into the role of epigenetic silencing of GSTP1 in colorectal cancer, its methylation was investigated in the blood samples obtained from tumor tissues [n=37] and the adjacent normal tissues [n=29] of patients with colorectal cancer as well as the blood samples taken from control subjects [n=42] by PCR after using methylation - sensitive restriction endonuclease ACCI. Methylation of GSTP1 was detected in the blood samples of control and blood, adjacent normal tissue and tumor tissue groups at 9.52%, 10.81%, 17.24% and 62.1% in respectively. There was a significant association between mehtylation of the GSTP1 in tumor tissues and the risk of colorectal cancer compared to adjacent normal tissues [OR= 7.86; 95% CI= 2.316 - 26.633]. The difference between methylation of the GSTP1 in the blood samples of case and control group [OR= 1.121; 95% CI= [0.26 - 4.84] was not statistically significant. Our findings indicate that methylation of the GSTP1 promotor may be detected in the tumor tissues. This could serve as a molecular diagnosis tool in detection and treatment of colorectal cancer