Introuduction: Squamous cell carcinoma is the most common malignancy in oral cavity. Approximately more than 90% of oral malignancies are squamous cell carcinoma, which have unknown etiology. Recently increased oxidative stress has been implicated in the pathogenesis of various diseases, consist of SCC. The aim of this study is evaluation of stress oxidative activity and oxidative DNA damage of saliva in SCC and in comparison with normal groups. Material and method: Twenty six patients with SCC (mean age 63.5±2.6), and 46 normal ones (48.4±1.2) were enrolled in this study. This study was conducted at the Clinic of Oral Medicine of Tehran University of Medical Sciences in 2009. The unstimulated whole saliva malondialdehyde (MDA), was assayed as an indicator of lipid peroxidation. TAC levels were assayed by thiobarbituric acid and ferric reducing antioxidant potential (FRAP), and 8-OH-dG as an indicator of DNA damage, respectively, in both groups. Results: Level of saliva MDA as a lipid peroxidation marker but not antioxidant level in patients with SCC was significantly higher than that of control group and level of 8-OH-dG as an oxidative DNA damage marker in comparison with control group was lower in patients with SCC, but it was not significant. Conclusion: Results of this study suggested that increased lipid peroxidation and oxidative DNA damage, and decline in antioxidant defence are involved in pathogenesis of SCC. Keywords: Stress oxidative, antioxidant, 8-OH-dG, squamous cell carcinoma, saliva doi:10.1016/j.clinbiochem.2011.08.490 Poster – [A-10-666-1] Effects of lead, nickel and cobalt on chromatin proteins in rat alveolar macrophages and hepatocyte nuclei Rabbani Chadegani Azra, Shahmir Nosrat, Babaei Masoome Department of Biochemistry, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran E-mail addresses: azrabbani@ibb.ut.ac.ir (R.C. Azra), Shahmir@ibb.ut.ac.ir (S. Nosrat), mbabaei@ibb.ut.ac.ir (B. Masoome) Introduction: Heavy metals are environmental pollutants, although we can't ignore the side effects of these metals, their application in developing technology and citizens is increased. Methods: In the present study the effects of lead, nickel and cobalt on chromatin proteins in alveolar macrophages and hepatocyte nuclei were investigated, using SDS and agarose gel electrophoresis, UV–Vis spectro- scopy and western blotting techniques. Alveolar macrophages were prepared from rat lung by lavage and incubated with various concentra- tions of metals. Results: The results showed that viability of the cells considerably decreased as metal concentrations were increased. The electrophoresis of histone and non-histone proteins showed that the histone proteins remain unchanged in the presence of metals although some minor effects were observed. Analysis of DNA extract from the treated cells and controls on agarose gel and also using fluorescent dyes revealed that all of these metals, at low concentration proceed the cells into apoptosis, as chromatin condensation and DNA fragmentation occurred in some cells. Whereas higher concentrations of metals induced necrosis. Studies on the effect of metals on nuclei represented that the absorbance at 260, 230 and 210 nm is decreased when metal concentration was increased. SDS gel electrophoresis and western blot also confirmed the results indicating that interaction of metals with the nuclei decreases the extractability of the histone proteins of the chromatin. Conclusion: It is finally concluded that lead, nickel and cobalt bind to chromatin proteins, however, the extent of binding was different among the metals. Keywords: Lead, nickle, cobalt, chromatin doi:10.1016/j.clinbiochem.2011.08.491 E.Poster – [A-10-718-2] Association between Cox-2 promoter -765G>C polymorphism and gastric adenocarcinoma in Iranian patients Kadivar Mehdi a , Rostami Massomeh b a Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran b Science and Research Branch, Islamic Azad University, Tehran, Iran E-mail addresses: kadivar@pasteur.ac.ir (K. Mehdi), kadivar@pasteur.ac.ir (R. Massomeh) Introduction: Gastric cancer (GC) is the second cause of cancer- related death and its frequency is increasing in general populations especially in Asian countries. The development of GC is assumed to be a complex interaction between genetics, heredity, dietary factors and infections especially with H. pylori infection. As up-regulation of cyclooxigenase-2 (Cox-2) has been observed in inhibition of apoptosis, tumor growth, and angiogenesis, we investigated single nucleotide polymorphism of −765G>C in Cox-2 gene promoter. Materials and methods: Five ml of peripheral blood was collected from 100 patients with GC and 100 controls. DNA extraction was performed using standard salting-out method. Genomic DNA samples were amplified by PCR using specific primers for Cox-2 gene promoter. Subsequently, PCR products were digested with Bsh1236I restriction endonuclease and results were observed in %3 agarose gel stained with Ethidium bromide. Results: The results showed that the frequency of CC, CG and GG genotypes were 4%, 32% and 64%, respectively in normal controls and 5%, 44% and 51% in patients with gastric adenocarcinoma. The statistical analysis revealed significant differences between genotypes (P value C polymorphism in Iranian population. Conclusion: We revealed that subjects with C carriers of Cox-2 gene are more susceptible to develop Gastric cancer. As the frequency of this polymorphism varies among different ethnic populations, it is important to identify each genetic polymorphism in each population. Keywords: Cox-2 gene, gastric adenocarcinoma, RFLP-PCR doi:10.1016/j.clinbiochem.2011.08.492 Poster – [A-10-731-1] Evaluation of K-ras mutations in colorectal carcinoma (CRC) patients of East-North of Iran Lary Sara, Ghaffarzadegan kamran, Afsharnezhad sima, Hoseinkhani Saman, Mohammadi Ghazaleh E-mail addresses: sara.lary@gmail.com (L. Sara), kghafarzadegan@hotmail.com (G. kamran), sanegad@yahoo.com (A. sima), saman_h@modares.ac.ir (H. Saman), ghi.mohammadi@yahoo.com (M. Ghazaleh) Introduction: Colon cancer is the third most common of digestive cancers in Iran after the stomach and esophagus cancer. K-ras mutations, one of the earliest events observed in colorectal carcinogenes, are a key step in colorectal cancer progression. K-ras mutations are mostly found in codons 12 and 13, and less frequently in codon 61. The aim of this study was identification of K-ras gene mutations in CRC patients among the East-North of Iran, and to assess whether they are linked with the clinicopathological parameters. Materials and methods: Tumor samples were collected from a consecutive series of 54 patients undergoing respective surgery for CRC. Abstracts S200