[A device for endoluminal thermal obliteration of varicose veins]. / Ustroistvo dlia provedeniia éndoliuminal'noi termicheskoi obliteratsii varikoznykh ven.

Amongst the techniques of endoluminal thermal obliteration of varicose veins, the most commonly employed treatment modalities are endovasal radiofrequency ablation and endovasal laser obliteration, both using a generating source and a special device for carrying out thermal obliteration. It has been noted that each of the methods of thermal obliteration has a number of disadvantages, irrespective of using the energy of magnetic oscillations in a radiofrequency range or laser radiation, including high cost of expendable materials and equipment. The device we worked out for endoluminal thermal obliteration of varicose veins was based on the principle of high efficacy and safety, with a significant decrease in the cost of carrying out the manipulation. This was achieved by means of developing a new device wherein a thermal effect is exerted not via the direct impact of laser radiation on the venous wall but at the expense of using laser energy exceptionally for heating a metal tip located at the distal end of high-strength metallized fibre coated with a heat-resistant polymer. Analysing the initial short-term results of using the new technique of thermal obliteration in treating a total of 50 patients presenting with varicose veins made it possible to draw a conclusion on high efficacy of the method and its safety. The proposed device may repeatedly be used with any and simplest-in-design source of laser radiation regardless of the wavelength and power of radiation. Implementation of this technique into clinical practice will make it possible to decrease manifold the cost of the procedure of thermal obliteration of varicose veins, currently carried out with the use of the classic techniques - endovasal laser obliteration and endovasal radiofrequency ablation.

[A new-type device for endovasal laser obliteration of varicose veins]. / Novyi tip ustroistva dlia provedeniia éndovazal'noi lazernoi obliteratsii varikoznykh ven.

The purpose of the study was to work out a Russian-made, simple-to-manufacture, safe, inexpensive and efficient device for performing endovasal laser obliteration (EVLO) of varicose veins, with the underlying principle of endoluminal distribution of the total laser energy into several flows. The development of this device was based on the principle of dividing the total laser radiation into two energy flows. One flow has a shape of circularly formed, continuous field of laser radiation of specified width within the angular range from 50 to 90°, which ensures the main energetic contribution to thermal impact on the vascular wall. The second energetic flow is formed in the part of the tip having a shape of a truncated cone, along the axis of the optical fibre within the angular range from 10 to 50°, which ensures additional thermal effect of radiation on the narrowing walls of the venous channel. Starting from 2016, EVLO with the use of the developed device was performed in a total of 50 patients with class C2-C3 varicose veins. The morphogenesis of the occurring restructuring of the venous wall was studied intraoperatively and in various time periods. Tissue specimens obtained intraoperatively demonstrated in the majority of cases complete or partial intimal detachment, swelling, disorganization of the middle membrane, adventitial loosening with thrombosis of the elements of the vasa vasorum in the majority of portions. The histological specimens harvested at 10 to 14 days were found to contain in the venous wall clear-cut distinct evidence of actively commensing connective-tissue proliferation. At 1 month of follow up the specimens of the veins treated with EVLO using the developed device showed the beginning of collagenisation of the wall, with finally fibrous restructuring and wall hyalinosis by month 3 after EVLO. The proposed device for EVLO of varicose veins makes it possible to act upon the venous wall simultaneously with two energy flows which excludes negative thermal action of excess energy of laser radiation on the vascular wall while using unidirectional radiation in the form of one or even two, but thin rings and, thus, dramatically decreasing reducing the risk for the development of complications. Implementation of the new device into the phlebological practice in Russia in conditions of complete import substitution has significant economic benefit.

[Study of photodynamic treatment for P-388 lympho-leukemia in mice].

Data are presented on the results of photodynamic treatment (PDT) of mice DBA2 with transplantable lympho-leukemia P-388. Different regimens of photosensitizer Dimegin and emission were used. Both intravenous PDT and in combination with local PDT should be recommended.

Kinetic model of bacteriorhodopsin photocycle: pathway from M state to bR.

A model of the last parts of the bacteriorhodopsin (bR) photocycle is proposed on the basis of experimental data for the kinetic behavior of the 'O' intermediate during a temperature pulse in distilled water suspension. The model includes the previously proposed (but not well characterized) intermediate 'N' between the 'M' and 'O' states of bR. This intermediate exists in fast temperature-dependent quasi-stationary equilibrium with the red-shifted intermediate 'O' and has a maximum of absorption close to the bR spectrum.

[Kinetics of primary photocycle stages of bacteriorhodopsin at low temperatures]. / Kinetika pervichnykh stadii fototsikla bakteriorodopsina pri nizkikh temperaturakh.

According to the changes of absorption spectra kinetics of two primary stages of bacteriorhodopsin photochemical cycle was studied in the temperature range 160 +/- 300 degrees K. It has been found that for K610-L550 transition in the range under study the rate-temperature relationship is described by Arrhenius law with the activation energy Ea = 0.68 eV. For L550-M412 transition Ea = 0.69 eV. The character of temperature relationship, of the rate and amplitude for this transition indicates that at T less than or equal to 270 degrees K a phase transition is possible.

Studies of electron transport dynamics in photosynthetic reaction centers using fast temperature changes.

Rates of thermoinduced conformational transitions of reaction center (RC) complexes providing effective electron transport were studied in chromatophores and isolated RC preparations of various photosynthesizing purple bacteria using methods of fast freezing and laser-induced temperature jump. Reactions of electron transfer from the primary to secondary quinone acceptors and from the multiheme cytochrome c subunit to photoactive bacteriochlorophyll dimer were used as probes of electron transport efficiency. The thermoinduced transition of the acceptor complex to the conformational state facilitating electron transfer to the secondary quinone acceptor was studied. It was shown that neither the characteristic time of the thermoinduced transition within the temperature range 233-253 K nor the characteristic time of spontaneous decay of this state at 253 K exceeded several tens of milliseconds. In contrast to the quinone complex, the thermoinduced transition of the macromolecular RC complex to the state providing effective electron transport from the multiheme cytochrome c to the photoactive bacteriochlorophyll dimer within the temperature range 220-280 K accounts for tens of seconds. This transition is thought to be mediated by large-scale conformational dynamics of the macromolecular RC complex.

Spectrally silent transitions in the bacteriorhodopsin photocycle.

The photocycle kinetics of bacteriorhodopsin were analyzed from 0 to 40 degrees C at 101 wavelengths (330-730 nm). The data can be satisfactorily approximated by eight exponents. The slowest component (half-time 20 ms at 20 degrees C) belongs to the 13-cis cycle. The residual seven exponentials that are sufficient to describe the all-trans photocycle indicate that at least seven intermediates of the all-trans cycle must exist, although only five spectrally distinct species (K, L, M, N, and O) have been identified. These seven exponentials and their spectra at different temperatures provide the basis for the discussion of various kinetic schemes of the relaxation. The simplest model of irreversible sequential transitions includes after the first K--> L step the quasiequilibria of L<-->M, M<-->N, and N<-->O intermediates. These quasiequilibria are controlled by rate-limiting dynamics of the protein and/or proton transfer steps outside the chromophore region. Thus there exists an apparent kinetic paradox (i.e., why is the number of exponents of relaxation (at least seven) higher than the number of distinct spectral intermediates (only five)), which can be explained by assuming that some of the transitions correspond to changes in the quasiequilibria between spectrally distinct intermediates (i.e., are spectrally silent).