[Model of aggregation of pigments in the chlorosomal antenna of the green bacteria Chloroflexus aurantiacus]. / Model' agregatsii pigmentov v khlorosomnoi antenne zelenykh bakterii Chloroflexus aurantiacus.

Independent experimental and theoretical evaluation was performed for the adequacy of our previously proposed general molecular model of structural organization of light-harvesting pigments in chlorosomal bacteriochlorophyll (BChl) c/d/e-containing superantenna of different green bacteria. Simultaneous measurement of hole burning in the optical spectra of chlorosomal BChl c and temperature dependence of steady-state fluorescence spectra of BChl c was accomplished in intact cells of photosynthetic green bacterium Chloroflexus aurantiacus; this allows unambiguous determination of the structure of exciton levels of BChl c oligomers in this natural antenna, which is a fundamental criterion for adequacy of any molecular model for in vivo aggregation of antenna pigments. Experimental data were shown to confirm our model of organization of oligometric pigments in chlorosomal BChl c antenna of green bacterium Chloroflexus aurantiacus. This model, which is based on experimental data and our theory of spectroscopy of oligomeric pigments, implies that the unit building block of BChl c antenna is a cylindrical assembly containing six excitonically coupled linear pigment chains whose exciton structure with intense upper levels provides for the optimal spectral properties of the light-harvesting antenna.

[Photodynamic therapy in the treatment of diseases of the anterior and posterior eye segments]. / Primenenie fotodinamicheskoi terapii v lechenii zabolevanii perednego i zadnego otrezka glaza.

The article deals with the use of photodynamic therapy with regard for the modern choice of photosensitizing preparations and with regard for new-generation lasers, which reveal, to a full extent, the possibilities of the above treatment method. Examples of using the photodynamic therapy in the treatment of some oncology pathologies of various localizations, including the ocular pathologies, are depicted in the article. The use of photodynamic therapy at retinal diseases, caused by the onset of new-vascular membranes due to the age-related degeneration of the macular, is under discussion. The application of photodynamic therapy in the treatment of cystic filtration cushions, involving the technique offered by the authors, is described.

[Treatment of inflammatory conditions of the iris and ciliary body, accompanying fibrin exudation]. / Lechenie vospalitel'nykh sostoianii raduzhki i tsiliarnogo tela, soprovozhdaiushchikhsia fibrinoidnoi ékssudatsiei.

The paper presents a description of a new method for treatment of iris and ciliary body inflammation accompanied with fibrin exudation. We used low-level blue laser destroying a fibrin clot in its initial stage of formation. We also used herapin and ascorbic acid. In the absence of the greatest impact urokinase was additionally administered.

Dynamics of excitation energy transfer in the LH1 and LH2 light-harvesting complexes of photosynthetic bacteria.

Photosynthetic light harvesting is a unique life process that occurs with amazing efficiency. Since the discovery of the structure of the bacterial peripheral light-harvesting complex (LH2), this process has been studied using a variety of advanced laser spectroscopic methods. We are now in a position to discuss the physical origins of excitation energy transfer and trapping in the LH2 and LH1 antennae of photosynthetic purple bacteria. We demonstrate that the time evolution of the state created by the light is determined by the combined action of excitonic pigment-pitment interactions, energetic disorder, and coupling to nuclear motion in a pigment-protein complex. A quantitative fit of experimental data using Redfield theory allowed us to determine the pathways and time scales of exciton and vibrational relaxation and analyze separately different contributions to the measured transient absorption dynamics. Furthermore, these dynamics were observed to be strongly dependent on the excitation wavelength. A numerical fit of this dependence turns out to be extremely critical to a variation of the structure and disorder parameters and, therefore, can be used as a test for different antenna models (disordered ring, elliptical deformations, correlated disorder, etc.). The calculated equilibration dynamics in the exciton basis allow a visualization of the exciton motion using a density matrix picture in real space.

Model of detergent-induced spectral changes of the B800-850 complex from Chromatium minutissimum.

The absorption and circular dichroism spectra of the B800-850 complex from Chromatium minutissimum before and after the Triton X-100 treatment were simulated by means of standard exciton theory, taking into account inhomogeneous broadening. To explain the spectral changes of the B800-850 complex treated with Triton X-100, we have assumed that all bacteriochlorophyll pigments absorbing at 850 nm exhibit the same additional rotation of approximately 20 degrees around the axis perpendicular to the membrane plane. This has been sufficient to fit the transformation in absorption and circular dichroism spectra induced by detergent treatment of the B800-850 complex.

Exciton levels structure of antenna bacteriochlorophyll c aggregates in the green bacterium Chloroflexus aurantiacus as probed by 1.8-293 K fluorescence spectroscopy.

We have demonstrated temperature-dependence of the steady-state fluorescence lineshape of the bacteriochlorophyll (BChl) c band measured for intact cells of the green bacterium Chloroflexus aurantiacus over the 1.8-293 K range. The measured temperature-dependence has been shown to be in good agreement with the theoretical one, calculated for our original model of pigment organization in the chlorosomal oligomeric antenna of green photosynthetic bacteria based on spectral hole-burning studies (Fetisova, Z.G. et al. (1996) Biophys. J. 71, 995-1010). This model implies that the BChl c antenna unit is a tubular aggregate of six exciton-coupled linear pigment chains having the exciton level structure with strongly allowed higher levels.

Disordered exciton model for the core light-harvesting antenna of Rhodopseudomonas viridis.

In this work we explain the spectral heterogeneity of the absorption band (. Biochim. Biophys. Acta. 1229:373-380), as well as the spectral evolution of pump-probe spectra for membranes of Rhodopseudomonas (Rps.) viridis. We propose an exciton model for the LH1 antenna of Rps. viridis and assume that LH1 consists of 24-32 strongly coupled BChl b molecules that form a ring-like structure with a 12- or 16-fold symmetry. The orientations and pigment-pigment distances of the BChls were taken to be the same as for the LH2 complexes of BChl a-containing bacteria. The model gave an excellent fit to the experimental results. The amount of energetic disorder necessary to explain the results could be precisely estimated and gave a value of 440-545 cm(-1) (full width at half-maximum) at low temperature and 550-620 cm(-1) at room temperature. Within the context of the model we calculated the coherence length of the steady-state exciton wavepacket to correspond to a delocalization over 5-10 BChl molecules at low temperature and over 4-6 molecules at room temperature. Possible origins of the fast electronic dephasing and the observed long-lived vibrational coherence are discussed.

Exciton delocalization in the B808-866 antenna of the green bacterium Chloroflexus aurantiacus as revealed by ultrafast pump-probe spectroscopy.

A model of pigment organization in the B808-866 bacteriochlorophyll a antenna of the green photosynthetic bacterium Chloroflexus aurantiacus based on femtosecond pump-probe studies is proposed. The building block of the antenna was assumed to be structurally similar to that of the B800-850 light-harvesting 2 (LH2) antenna of purple bacteria and to have the form of two concentric rings of N strongly coupled BChl866 pigments and of N/2 weakly coupled BChl808 monomers, where N = 24 or 32. We have shown that the Qy transition dipoles of BChl808 and BChl866 molecules form the angles 43 degrees +/- 3 degrees and 8 degrees +/- 4 degrees, respectively, with the plane of the corresponding rings. Using the exciton model, we have obtained a quantitative fit of the pump-probe spectra of the B866 and B808 bands. The anomalously high bleaching value of the B866 band with respect to the B808 monomeric band provided the direct evidence for a high degree of exciton delocalization in the BChl866 ring antenna. The coherence length of the steady-state exciton wave packet corresponds to five or six BChl866 molecules at room temperature.

Excitation delocalization in the bacteriochlorophyll c antenna of the green bacterium Chloroflexus aurantiacus as revealed by ultrafast pump-probe spectroscopy.

Room temperature absorption difference spectra were measured on the femtosecond through picosecond time scales for chlorosomes isolated from the green bacterium Chloroflexus aurantiacus. Anomalously high values of photoinduced absorption changes were revealed in the BChl c Qy transition band. Photoinduced absorption changes at the bleaching peak in the BChl c band were found to be 7-8 times greater than those at the bleaching peak in the BChl a band of the chlorosome. This appears to be the first direct experimental proof of excitation delocalization over many BChl c antenna molecules in the chlorosome.

Pigment organization and exciton dynamics in the B808-866 antenna of the green bacterium Chloroflexus aurantiacus.

The model for the B808-866 antenna of the green photosynthetic bacterium Chloroflexus aurantiacus based on femtosecond pump-probe studies is proposed. The three-dimensional structure of the B808-866 antenna is assumed to be similar to the structure of the B800-850 antenna of purple bacteria, i.e. it has the form of two concentric rings of N strongly coupled BChl866 pigments and of N/2 weakly coupled BChl808 monomers. The Qy transition dipoles of BChl808 and BChl866 molecules form the angles 43 degrees +/- 3 degrees and 8 degrees +/- 4 degrees, respectively, with the plane of the corresponding rings. The lowest limit of the BChl866 aggregate size is N = 18. The anomalously high bleaching value of the BChl866 band with respect to the monomeric BChl808 band provides evidence for a high degree of exciton delocalization. To account for this phenomenon, the exciton model describing exciton dynamics in the spectrally disordered circular BChl866 aggregate is developed. According to this model, the effective exciton size in this antenna (Neff) is 6-8.

[Treatment of solitary subconjunctival cysts of filtration pad after fistulizing surgery of glaucoma]. / Lechenie solitarnykh subkon"iunktival'nykh kist fil'tratsionnoi podushechki posle fistuliziruiushchikh antiglaukomatoznykh operatsii.

The clinical picture and cytostatic treatment of solitary subconjunctival cysts of filtration pad after fistula-forming antiglaucoma surgery are described. Twenty-seven eyes with hypertension which developed as a result of subconjunctival cysts formed in the early postoperative period in 7% of patients operated on for open-angle glaucoma. Probable mechanisms of the pathogenesis of the formation of solitary cysts are discussed and 3-staged therapy proposed, including beta-blockers, perforation of the cyst wall by YAG laser, and, in 10% of cases with rigid cysts, microsurgical revision of filtration pad.

Energy transfers in the B808-866 antenna from the green bacterium Chloroflexus aurantiacus.

Energy transfers within the B808-866 BChl a antenna in chlorosome-membrane complexes from the green photosynthetic bacterium Chloroflexus aurantiacus were studied in two-color pump-probe experiments at room temperature. The steady-state spectroscopy and protein sequence of the B808-866 complex are reminiscent of well-studied LH2 antennas from purple bacteria. B808-->B866 energy transfers occur with approximately 2 ps kinetics; this is slower by a factor of approximately 2 than B800-->B850 energy transfers in LH2 complexes from Rhodopseudomonas acidophila or Rhodobacter sphaeroides. Anisotropy studies show no evidence for intra-B808 energy transfers before the B808-->B866 step; intra-B866 processes are reflected in 350-550 fs anisotropy decays. Two-color anisotropies under 808 nm excitation suggest the presence of a B808-->B866 channel arising either from direct laser excitation of upper B866 exciton components that overlap the B808 absorption band or from excitation of B866 vibronic bands in nontotally symmetric modes.

Functioning of oligomeric-type light-harvesting antenna.

In our previous work, we developed, for the first time, a theory of excitation energy transfer within an oligomeric-type light-harvesting antenna and, in particular, within the chlorosome of green bacteria (Biophys.J., 1996, vol.71, pp.995-1010). The theory was recently developed for a new original exciton model of aggregation of chlorosomal pigments, bacteriochlorophylls (BCh1) c/d/e (Biochem, Mol.Biol.Int., 1996, vol.40, No.2, pp. 243-252). In this paper, it was demonstrated with picosecond fluorescence spectroscopy that this theory explains the antenna-size-dependent kinetics of fluorescence decay in chlorosomal antenna, measured for intact cells of different cultures of the green bacterium Chlorobium limicola with different chlorosomal antenna size determined by electron microscopic examination of the ultrathin sections of the cells. According to our model, the energy transfer dynamics within the chlorosome imply the formation of a cylindrical exciton, delocalized over a tubular aggregate of BCh1 c chains, and inductive-resonance-type transfer of such a cylindrical exciton between the nearest tubular BCh1 c aggregates and to BCh1 a of the chlorosome.

Structure of bacteriochlorophyll aggregates in chlorosomes of green bacteria: a spectral hole burning study.

Exciton level structure, homogenous absorption and hole-burning spectra were calculated for different models of bacteriochlorophyll aggregation in chlorosomal antennae of green bacteria. It was demonstrated that none of the earlier proposed models of noninteracting linear bacteriochlorophyll aggregates and linear bacteriochlorophyll chains assembling in tubular aggregates with high density of packing, exhibits the in vivo exciton level structure revealed by hole-burning experiments on intact cells of green bacteria. The models of linear exciton-coupled bacteriochlorophyll chains with a low packing density, approximating that in vivo, were proposed as alternative, to obtain the main spectral features found in natural antennae.

Excitation energy transfer in chlorosomes of green bacteria: theoretical and experimental studies.

A theory of excitation energy transfer within the chlorosomal antennae of green bacteria has been developed for an exciton model of aggregation of bacteriochlorophyll (BChl) c (d or e). This model of six exciton-coupled BChl chains with low packing density, approximating that in vivo, and interchain distances of approximately 2 nm was generated to yield the key spectral features found in natural antennae, i.e., the exciton level structure revealed by spectral hole burning experiments and polarization of all the levels parallel to the long axis of the chlorosome. With picosecond fluorescence spectroscopy it was demonstrated that the theory explains the antenna-size-dependent kinetics of fluorescence decay in chlorosomal antenna, measured for intact cells of different cultures of the green bacterium C. aurantiacus, with different chlorosomal antenna size determined by electron microscopic examination of the ultrathin sections of the cells. The data suggest a possible mechanism of excitation energy transfer within the chlorosome that implies the formation of a cylindrical exciton, delocalized over a tubular aggregate of BChl c chains, and Forster-type transfer of such a cylindrical exciton between the nearest tubular BChl c aggregates as well as to BChl a of the baseplate.

Exciton delocalization in the antenna of purple bacteria: exciton spectrum calculations using Z-ray data and experimental site inhomogeneity.

Electron absorption and circular dichroism spectra of the peripheral light-harvesting complex (LH2) of photosynthetic purple bacteria were calculated taking into account the real-life spatial arrangement and experimental inhomogeneous broadening of bacteriochlorophyll molecules. It was shown that strong excitonic interactions between 18 bacteriochlorophyll molecules (BCh1850) within the circular aggregate of the LH2 complex result in an exciton delocalization over all these pigment molecules. The site inhomogeneity (spectral disorder) practically has no influence on exciton delocalization. The splitting between two lowest exciton levels corresponds to experimentally revealed splitting by hole-burning studies of the LH2 complex.

Antenna size dependent exciton dynamics in the chlorosomal antenna of the green bacterium Chloroflexus aurantiacus.

Using picosecond fluorescence spectroscopy, we demonstrated antenna size dependent exciton dynamics in chlorosomal antenna, measured for intact cells of different cultures of the green bacterium Chloroflexus aurantiacus with different chlorosomal antenna size determined by electron microscopic examination of ultrathin sections of the cells. The measured bacteriochlorophyll (BChl) c excitation lifetimes show a quasilinear dependence on chlorosome size as predicted in our model for cylindrical exciton migration within the three-dimensional chlorosomal antenna. The migration model was developed for the proposed exciton model of chlorosomal BChl c aggregation. The data predict the time constant values for excitation energy transfer between BChl c aggregates as well as to BChl a of the baseplate.

Site inhomogeneity and exciton delocalization in the photosynthetic antenna.

The influence of energy disorder on exciton states of molecular aggregates (the dimer and the circular aggregate) was analyzed. The dipole strength and inhomogeneous line shapes of exciton states were calculated by means of numerical diagonalization of Hamiltonian with diagonal energy disorder without intersite correlation. The disorder degree corresponding to destruction of coherent exciton states was estimated. The circular aggregates were treated as a model of light-harvesting antenna structures of photosynthetic bacteria. It was concluded that the site inhomogeneity typical for LH1 and LH2 complexes of purple bacteria cannot significantly influence the exciton delocalization over the whole antenna.

Excitation delocalization over the whole core antenna of photosynthetic purple bacteria evidenced by non-linear pump-probe spectroscopy.

Anomalously high values of photoinduced absorption changes were revealed in the antenna of photosynthetic purple bacteria. They were found to be 4-16 times greater at the bleaching peak of the antenna than at the bleaching peak of the BChl dimer of the reaction center. This is direct proof of excitation delocalization over many pigment molecules. Calculations according to the model of exciton delocalization over all core antenna BChls allow one to explain the observed phenomenon.