Immunohistochemical detection of p53 protein in basal cell skin cancer after microwave-assisted antigen retrieval.

p53 is the most frequently altered tumor-suppressor gene in skin cancer. In normal tissues the p53 protein (wild type) has a very short half-life and it is not detectable immunohistochemically. In contrast, the mutant p53 protein has an extended half-life in tumor cells and can be detected by immunohistochemical methods. p53 is widely used as an indicator of tumor aggression and progression. Fixation methods especially formaldehyde based fixation may mask the immunohistochemical detection of p53 protein but antigen retrieval methods enhance the inmmunohistochemical detection of p53 protein by remodification of protein structure. This study was designed to evaluate the efficacy of different fixatives, of microwaving and microwave pretreatment method to retrieve p53 immunoreactivity in paraffin-embedded non-lesioned (adjacent normal tissue) human skin samples or pathological human skin samples diagnosed as basal cell carcinoma. The samples were fixed at RT and/or in microwave oven either in neutral buffered formalin or alcohol for different time periods. For antigen retrieval, the sections were irradiated in a microwave oven for 5 cycles in 10 mM citrate buffer (pH 6.00). In this study the effects of six different fixation methods on the immunohistochemical staining have been investigated in basal cell tumor specimens. The application of antigen retrieval method was also examined and compared. Optimal results were obtained using samples fixed in alcohol either at room temperature (24 h) or in microwave oven.

The role of triple therapy, age, gender and smoking on the genotoxic effects of Helicobacter pylori infection.

The role of age, gender and smoking on both the genotoxic effects of Helicobacter pylori and the efficacy of eradication therapy in a group of patients with gastritis was investigated. Gastritis was confirmed by endoscopy and biopsy, and the presence of H. pylori by urease testing. Pre- and post-treatment peripheral blood lymphocyte cultures were prepared from 17 patients and 25 metaphases per patients were analysed for sister chromatid exchange (SCE), a well-established technique for the evaluation of human exposure to toxic agents. Treatment with omeprazole, clarithromycin and amoxycillin triple therapy eradicated H. pylori in 94% of patients and significantly reduced the SCE frequency. Pre-treatment SCE frequency was found to be positively correlated with age. Female smokers tended to have higher post-treatment SCE frequencies than male smokers, and pre- and post-treatment SCE frequencies were higher in older males than in older females. Eradication therapy decreased the genotoxicity of H. pylori, but age in males and smoking in females may decrease treatment efficacy.