The protonation of o-, m-and p-benzotoluidide in sulfuric acid solutions is studied by UV spectroscopy in the 190–350 nm region. Principal component analysis is applied to estimate the contributions of the effect of protonation and the medium effect. For the substances studied in this work, the first principal component (PC) captures about 98 % of the variance and the second PC ∼100 % of the cumulative percentage variance in the 210–350 nm region. The same spectral region is used for calculation of the ionization ratio from the coefficients of the first PC and mole fractions of the base and its conjugate acid. Using these data and Hammett's equation (pK _{BH +} = H _X + log I), the pK _{BH +} values for the protonation reaction are obtained. The dissociation constants as well as the solvent parameters m* (∼0.43) and ϕ (∼0.60) are calculated using the Excess Acidity Method (-pK _{BH +}= 2.28–2.30) and the Bunnett-Olsen Method (-pK _{BH +}= 2.24–2.28). The probable sites of protonation are discussed.

Background/Aim. Surgeons often face with the problem when selecting a reconstructive method for nasal skin defects. The aim of this study was to determine functional and aesthetic character-istics of different reconstructive methods used for skin defects in different regions of the nose. Methods. The study involved 44 patients with basocellular carcinoma in nasal area. The nasal skin was divided into four subunits: the tip, the alar lobules, the side-walls and the dorsum. The average skin defect size was 10 mm in diameter. Local flaps and full thickness skin grafts were used in the study. We analyzed the functional and esthetic results of dif-ferent reconstructive methods used for nasal defects in different regions of the nose 12 months after the surgery. Results. The study shows that different reconstructive methods produce dif-ferent functional and esthetic results in the same nasal subunits and that the same reconstructive method produces different re-sults in different nasal subunits. Conclusions. Estimation the postoperative functional and esthetic characteristics of different reconstructive methods is one of the basic preconditions of suc-cessful reconstruction.

The protonation of 3-methylindole, D-tryptophan, 3-formylindole, 3-acetylindole and indolyl-2-carboxylic acid in sulfuric acid media was studied by UV spectroscopy. The measurement of the absorbance at four selected wavelengths enabled the calculation of the corresponding molar absorptivities. The results were used to calculate the pKa value of the protonated form of the indole derivatives by the Hammett Method. The Hammett postulate (the slope of the plot log [c(BH+)/c(B)]vs. H should be equal to 1) was tested. The dissociation constants and solvent parameter m* were also obtained by applying the Excess Acidity Method. The position of the additional protons in the protonated compounds is discussed.

Introduction: Oral cancer is the most common subtype of cancer in the head and neck region, with an increasing incidence worldwide. Unfortunately, no specific biomarkers are used in everyday clinical practice. Small non-coding RNA molecules, microRNA (miRNA), are considered sensitive biomarkers for early diagnosis as well as prognosis in patients with oral cancer. Especially, microRNA derived from the H19 locus are poorly investigated for their potential role in oral cancer. Aim: The aim of this study was to evaluate expression of hsa-miR675-5p in tumor and non-tumor tissues of oral cancer patients and to associate it with pathohistological features. Material and Methods: The study group consisted of 35 patients with oral cancer. Tumor and surrounding non-tumor tissues were taken from each patient. Relative expression was measured using the quantitative reverse transcription - real time PCR method. Results: The relative expression of hsa-miR-675-5p was lower in oral cancer tumor than in non-tumor tissue suggesting its tumor suppressive role. hsa-miR-675-5p has diagnostic potential for sensitive distinction of tumor and non-tumor tissues in oral cancer patients. There was no difference in overall survival rates between patients with low and high hsa-miR-675-5pexpression, confirming that hsa-miR-675-5p cannot be used as a prognostic biomarker in patients with oral cancer. Conclusion: hsa-miR-675-5p can be considered as a potential diagnostic but not a prognostic molecular biomarker in oral cancer.

This study aimed to analyze the diagnostic and prognostic significance of miR-146a-5p in oral cancer and the association of the rs2910164 gene variant with miR-146a-5p expression. Thirty-five oral cancer patients participated in the study. Expression of miR-146a-5p in oral cancer, adjacent non-cancerous tissue, and the rs2910164 genotype variant were examined by real-time PCR. No difference was observed in miR-146a-5p expression between cancerous and non-cancerous tissues (P=0.272). It was concluded that miR-146a-5p is not a good diagnostic biomarker. There was no difference in miR- 146a-5p expression depending on the rs2910164 genotype. The rs2910164 variant was associated with tumor histological grade (P=0.037), stage (P=0.036), and lymph node status (P=0.025). There was a difference in survival between oral cancer patients with high and low miR-146a-5p expression (P=0.026), but not between patients with the GG and GC genotypes (P=0.400). Oral cancer patients with the wild-type GG genotype and high miR-146a-5p expression had significantly shorter survival when compared to patients with miR-146a-5p expression below the optimal cut-off and the wild-type genotype (P=0.035). A high miR-146a-5p level could be considered a potential biomarker of poor survival in patients with oral cancer, especially in those with the wild-type GG genotype of the rs2910164 variant.