This volume of „Progress of Medical Science” is prepared by the researchers of the Department of Biochemistry and Molecular Biology, Medical Center of Postgraduate Education. The articles making up this issue, both original and review reflect our current scientific interest.

Two manuscript written by the team of dr hab. Tadeusz Pacuszka describes “Membranes, detergent resistant membrane fraction and lipid rafts”. Theoretical considerations of the above as well their own published and unpublished observations on ganglioside functions are presented. Review written by the PhD student Natalia Fedoryszak-Kuśka discusses the impact of the gangliosides on the activity of epidermal growth factor receptors.

The spatial structure and antigenic activity of thyroid peroxidase (TPO), the primary enzyme in the biosynthesis of thyroid hormones and one of the three major thyroid antigens in autoimmune thyroid diseases (AITD), has been studied in our Department for several years. Two papers, original and review presented by dr. Marlena Godlewska and co-authors, apply to this problem. The experimental work using as a tool murine monoclonal antibodies and antibodies produced against the peptides of the human TPO investigated the localization of the immunodominant domain recognized by the human autoantibodies present in sera of patients with AITD. The results indicate that at least a part of the sequence of some peptides may participate in the immunodominant epitope of human TPO. A review summarizes current knowledge about the biology and physiological functions of thyroid peroxidase.

Another original work (dr. Urszula Piotrowska and prof. Grażyna Adler) presents a study on the membrane transmitters and intracellular signaling pathways activated by TSH in the normal thyroid follicular cells transfected with large T antigen of SV40 virus. The study showed that the „immortalization” of normal thyroid epithelial cells reduces sensitivity to TSH and suggest caution in the use of this cell line as a normal thyrocytes.

DNA damage plays an important role in the mutagenesis, carcinogenesis and the development of diseases in humans and the abnormalities in its repair may be a risk factor for many diseases, including cancer. A review by Justyna Janik presents the current knowledge on the involvement of oxidative stress, DNA damage, reactive oxygen species (ROS), somatic mutations and changes in the DNA repair mechanisms in the development of cancers, including possible participation in the development of thyroid carcinomas.

Work by dr. Piotr Popławski concerns tyronamino-derivatives of thyroid hormones discovered fifty years ago, forgotten, and re- discovered in the last few years. Tyronamins act as signaling molecules and cause diverse effects on the body and as recently postulated may also have therapeutic use. The process of autoimmunity is one of the etiological factors of development of primary biliary cirrhosis, and presence of autoantibodies in the sera of patients are useful tools in the diagnosis of the disease. These issues are considered in the recent work by dr. Alice Bauer, which summarizes current knowledge of autoantibodies detected in patients with PBC.

Autoimmune thyroid diseases (AITD) are the most common organ-specific autoimmune disorders. The etiology of AITD is still unclear, but the susceptibility to it is determined by a combination of genetic, environmental and epigenetic factors. The last review by prof. Ewa Brzeziańska and co-authors discusses the genetic background of AITD, the possible role of immunoregulatory genes, and epigenetic mechanisms of its development.