In recent years, the introduction of new molecular techniques in experimental and clinical settings has allowed researchers and clinicians to propose circulating-tumor DNA (ctDNA) analysis and liquid biopsy as novel promising strategies for the early diagnosis of cancer and for the definition of patients’ prognosis. It was widely demonstrated that through the non-invasive analysis of ctDNA, it is possible to identify and characterize the mutational status of tumors while avoiding invasive diagnostic strategies. Although a number of studies on ctDNA in patients’ samples significantly contributed to the improvement of oncology practice, some investigations generated conflicting data about the diagnostic and prognostic significance of ctDNA. Hence, to highlight the relevant achievements obtained so far in this field, a clearer description of the current methodologies used, as well as the obtained results, are strongly needed. On these bases, this review discusses the most relevant studies on ctDNA analysis in cancer, as well as the future directions and applications of liquid biopsy. In particular, special attention was paid to the early diagnosis of primary cancer, to the diagnosis of tumors with an unknown primary location, and finally to the prognosis of cancer patients. Furthermore, the current limitations of ctDNA-based approaches and possible strategies to overcome these limitations are presented.

The relationship between the concentration of cell-free DNA (cfDNA) and the number of proliferating/apoptotic lymphocytes in peripheral blood of premature newborns of different gestation age and full-term newborns was determined. The experiments were performed using fluorescent spectrophotometry (with Hoechst 33342), flow cytometry, and microscopy (Feulgen staining of lymphocytes). It was determined that the lymphocyte population of premature newborns may consist of 4.6% of proliferating and 22.1% apoptotic cells. For full-term newborns, the percentage was 2.5% and 2.9%, respectively. A direct correlation between the concentration of extracellular DNA and the number of proliferating lymphocytes of full-term newborns was ascertained (r= 0.400; P < 0.05). For premature newborns, the concentration of extracellular DNA correlated both with proliferating lymphocytes and apoptotic cells. The results show that premature birth causes the induction in lymphocytes of both apoptosis and proliferation that are accompanied by an increased extracellular DNA concentration in the blood of newborn babies.

Compounds that contain (R)-3-amino-4-(2,4,5-trifluorophenyl)butanoic acid substituted with bicyclic amino moiety (2-aza-bicyclo[2.2.1]heptane) were designed using molecular modelling methods, synthesised, and found to be potent DPP-4 (dipeptidyl peptidase-4) inhibitors. Compound 12a (IC50 = 16.8 ± 2.2 nM), named neogliptin, is a more potent DPP-4 inhibitor than vildagliptin and sitagliptin. Neogliptin interacts with key DPP-4 residues in the active site and has pharmacophore parameters similar to vildagliptin and sitagliptin. It was found to have a low cardiotoxic effect compared to sitagliptin, and it is superior to vildagliptin in terms of ADME properties. Moreover, compound 12a is stable in aqueous solutions due to its low intramolecular cyclisation potential. These findings suggest that compound 12a has unique properties and can act as a template for further type 2 diabetes mellitus drug development.

Molecular mechanisms of development of normal and pathological neuroendocrine and immune adaptive response to psychological (mental) stress are analyzed considering its possible provoking role in the development of rheumatoid arthritis (RA). A detailed analysis reveals the synergism of mechanisms that provoke the development of pathological anti-stress adaptive response and RA. It is possible that in persons at risk of developing RA minimal and unobtrusive for the individual stressful situations, periodically provoking prolonged production of pro-inflammatory cytokines, can, finally, lead to the development of rheumatic disease.