pH-dependent binding of ATP aptamer to the target and competition strands: Fluorescent melting curve fitting study.

The pH varies in different tissues and organelles and also changes during some diseases. In this regard, the application of molecular switches that use a competition-based aptamer switch design in biological systems requires studying the thermodynamics of such systems at different pH values. In this work, we studied the binding of the classical ATP aptamer to ATP and competition strands under different pH and ionic conditions using fluorescent melting curve analysis. We have developed an original approach to processing source data from a PCR thermal cycler. It is based on constructing a thermodynamic model of the melting profile and the subsequent fit of experimental curves within this model. We have shown that this approach enables us to narrow the temperature region under study to the width of the melting region without a significant loss in the quality of the result. This impressively expands the application area of this approach compared to frequently used techniques that require mandatory measurement of the signal outside the melting region. The results obtained by the method showed that the thermodynamic parameters of the ATP aptamer and its duplexes with competition strands change depending on pH. Therefore, molecular switches that use a competition strand to the ATP aptamer may have a pH-dependent sensitivity that has not been previously considered. This should be taken into account for future rational design of similar systems.

Neutral vs Charged Luminescent Radicals: Anti-Kasha Emission and the Impact of Molecular Surrounding.

Organic luminescent materials attract growing interest as an elegant solution for sustainable and inexpensive light-emitting devices. Most of them are neutral-emitting molecules with an implicit restriction of 25% internal quantum efficiency due to a spin-forbidden nature of the T1 → S0 transition. Utilizing organic radicals allows one to overcome such limits by theoretically boosting quantum yield up to 100%. Recently, different light-emitting radicals based on carbonyl- and carboxyl-substituted benzenes were synthesized and stabilized in different polymer matrices or ionic liquids. While some of them were proved to be suitable luminescent materials, the exact theoretical explanation of the nature of their emission is missing. There are two main hypotheses proposed in the literature. The first one suggests that the origin of luminescence is D2 → D0 anti-Kasha emission from anion radicals, while the second theory is based on D1 → D0 Kasha emission from neutral protonated radicals. In this work, we investigate both hypotheses and compare their derivatives with the available experimental data. We used density functional theory and complete-active space perturbation theory to investigate the absorption and emission properties in various aromatic carbonyl radicals. We found that both emission mechanisms can coexist simultaneously, with a dominant emission contribution made by anion radicals because of better agreement between oscillator strengths and radiative rate constants. Our numerical simulations agree with the experimental data and provide theoretical foundations for the fabrication of next-generation light-emitting devices based on luminescent radicals.

Internal conversion rate constant calculations considering Duschinsky, anharmonic and Herzberg-Teller effects.

A novel method for calculating rate constants for internal conversion (kIC) that simultaneously accounts for Duschinsky, anharmonic and Herzberg-Teller effects has been developed and implemented. This method has been applied to robust planar molecules like tetraoxa[8]circulene (4B), free-base porphyrin (H2P) and pyrometene (PM567) with small Duschinsky rotation (i.e. with almost identical normal coordinates in the ground and excited states) and to poly[n]fluorenes (P[n]F) (n = 2-14) with a substantial Duschinsky rotation. The obtained results show that the Duschinsky effect is large in the harmonic approximation, whereas it is in general much smaller in the anharmonic approximation. The Duschinsky effect is found to be large for high frequency vibrational modes with energies of ∼3300 cm-1 such as the X-H (X = C, N and O) stretching modes that mix in the S1 → S0 electronic transition. However, even in this case, the increase in kIC due to the Duschinsky effect does not exceed one order of magnitude. The calculations show that anharmonic contributions to kIC are larger than Herzberg-Teller contributions which in turn are larger than contributions from the Duschinsky effect ANH > HT > Du. We also show that an approximation, where only X-H bonds are considered in the kIC calculation, is accurate even for P[n]F (n = 2-14).

[The acute appendicitis' diagnostic Alvorado's system].

The recent studies prove that the treatment of the acute appendicitis should aim the preservation of the organ, considering the important functions of the least. The combined antimicrobial therapy allows the successful conservative treatment of all cases of the acute appendicitis but the gangrenous, which should be treated operatively. The use of glucocorticosteroids together with antibiotics is pathogenetically substantiated. To improve the diagnostics of the acute appendicitis, the modernized Alvorado's system was suggested by the authors. The least is adopted for the diagnostics of intraabdominal abscesses and gangrenous appendicitis.

[Resection of the left atrium in lung cancer].

An analysis of results of surgical treatment of 28 patients with lung cancer who underwent resection of the left atrium has shown that squamous cell cancer was diagnosed in 18 patients (64%), adenocarcinoma--in 5 (18%), dimorphous cancer--in 2 (7%), mucoepidermoid cancer in 2 (7%), atypical carcinoid--in 1 patient (4%). The degree of regional lymphogenic spread of the tumor NO took place in 11 patients (39%), N1--in 6 patients (22%), N2--in 11(39%). True invasion of the tumor to the left atrium myocardium took place in 20 patients (71%), involvement of the pulmonary vein orifices in the tumor process--in 8 (29%). Resection of the atrium was made using mechanical suturing apparatuses. The right side resections were fulfilled in 16 patients (57%), left side resections in 12 patients (43%). Pneumonectomy was fulfilled in 26 patients (93%), lobectomy--in 2 patients (7%). The operative interventions in five cases (18%) were estimated as microscopically non-radical (R1). The average time in the intensive care unit after operation was 3 days (from 1 till 12), in the surgical thoracal department--18 days (from 13 till 37). In the early postoperative period one patient died (4%), complications were noted in 5 patients (18%). The total one year survival was 69%, three year survival--39%, 5 year survival--17%. The survival median was 23 months. Resection of the left atrium in the selected lung cancer patients was not followed by growing operative lethality and the acceptable long term results were obtained.