HEMOGLOBIN BINDING TO PHOSPHOLIPID MEMBRANES AS REVEALED BY PYRENE FLUORESCENCE STUDY

In this work hemoglobin (Hb) association with lipid bilayers was investigated using fluorescent probe pyrene. Model membranes were prepared from zwitterionic lipid phosphatidylcholine (PC), anionic lipid phosphatidylglycerol (PG) and cholesterol (Chol). Hb-lipid binding was followed by the pyrene fluorescence quenching. Hb-induced decrease of pyrene monomer fluorescence was followed by the increase of relative intensities of vibronic bands. Presumably, Hb penetration into the bilayer increases the space between neighbouring lipids and promotes water penetration into the membrane core. Pyrene excimer emission quenching was interpreted in terms of resonance energy transfer. The greatest depth of Hb penetration into the lipid bilayer was observed in PC vesicles. In Chol-containing liposomes sterol condensing effect prevents deep protein penetration into the membrane. PG has an ability to stabilize lipid bilayers due to the ordered state of its lipid tails and H-bonding interactions between lipid molecules. This also can prevent Hb access to the inner membrane regions. KEY WORDS: hemoglobin, model membranes, protein-lipid complexes, pyrene, fluorescence spectroscopy. ДОСЛІДЖЕННЯ ЗВ'ЯЗУВАННЯ ГЕМОГЛОБІНУ З ФОСФОЛІПІДНИМИ МЕМБРАНАМИ ЗА ДОПОМОГОЮ ПІРЕНУ O.К. Куценко, Г.П. Горбенко, В.М. Трусова Харківський національний університет імені В.Н. Каразіна, пл. Свободи, 4, Харків, 61077 В даній роботі комплексоутворення гемоглобіну (Hb) з ліпідними бішарами різного складу досліджувалось за допомогою флуоресцентного зонду пірену. Зв'язування Hb з ліпідами характеризувалось гасінням флуоресценції зонда, що супроводжувалось зростанням відносної інтенсивності вібронних смуг. Можливо, Hb, проникаючи у бішар, розсуває сусідні молекули ліпідів, сприяючи проникненню води у мембрану. Гасіння випромінювання ексимерів інтерпретувалось у термінах резонансного переносу енергії. Найбільша глибина проникнення білка спостерігалась у РС везикулах. У ліпосомах, які містили Chol, конденсуючий ефект стерола перешкоджав проникненню білка у мембрану. Структурні властивості PG сприяють стабілізації ліпідного бішару, що також може перешкоджати проникненню Hb у внутрішні регіони мембрани. КЛЮЧОВІ СЛОВА: гемоглобін, модельні мембрани, білок-ліпідні комплекси, пірен, флуоресцентна спектроскопія. ИССЛЕДОВАНИЕ СВЯЗЫВАНИЯ ГЕМОГЛОБИНА С ФОСФОЛИПИДНЫМИ МЕМБРАНАМИ С ПОМОЩЬЮ ПИРЕНА O.К. Куценко, Г.П. Горбенко, В.М. Трусова Харьковский национальный университет имени В.Н. Каразина, пл. Свободы, 4, Харьков, 61077 В данной работе комплексообразование гемоглобина (Hb) с липидными бислоями различного состава исследовалось с помощью флуоресцентного зонда пирена. Связывание Hb с липидами характеризовалось тушением флуоресценции пирена, что сопровождалось увеличением относительной интенсивности вибронных полос пирена. Возможно, Hb, проникая в бислой, раздвигает соседние молекулы липидов, способствуя проникновению воды в мембрану. Тушение испускания эксимеров интерпретировалось в терминах резонансного переноса энергии. Наибольшая глубина проникновения белка наблюдалась в РС везикулах. В липосомах, содержащих Chol, конденсирующий эффект стерола препятствовал проникновению белка в мембрану. Структурные свойства PG способствуют стабилизации липидного бислоя, что также может препятствовать проникновению Hb во внутренние области мембраны. КЛЮЧЕВЫЕ СЛОВА: гемоглобин, модельные мембраны, белок-липидные комплексы, пирен, флуоресцентная спектроскопия

Pion photoproduction on the nucleon in the quark model

We present a detailed quark-model study of pion photoproduction within the effective Lagrangian approach. Cross sections and single-polarization observables are investigated for the four charge channels, $\gamma p\to \pi^+ n$, $\gamma n\to \pi^- p$, $\gamma p\to \pi^0 p$, and $\gamma n\to \pi^0 n$. Leaving the $\pi N\Delta$ coupling strength to be a free parameter, we obtain a reasonably consistent description of these four channels from threshold to the first resonance region. Within this effective Lagrangian approach, strongly constrainted by the quark model, we consider the issue of double-counting which may occur if additional {\it t}-channel contributions are included.Comment: Revtex, 35 pages, 16 eps figures; version to appear on PR

Features of the immune response in children with acute respiratory infections caused by DNA and RNA viruses

The issues of immunopathogenesis of acute respiratory viral infections (ARVI) remain relevant, despite a long history of study. The aim of the study was to investigate the characteristics of the content of some cytokines in the blood serum of children with ARVI caused by DNA and RNA-containing viruses. Material and methods. We examined 92 children with ARVI at the age from 1 to 15 years, hospitalized in the hospital of the Children’s Clinical Hospital No. 6 (Novosibirsk). In order to determine the etiological factor, a study was carried out using the RT-PCR method (test systems AmpliSensORVI-screen-FL, “InterLabService”, Russia) of mucus from the nose and throat for the presence of genetic material of viruses that cause ARVI. Determination of the content of IL-8, IL-17, IFN-γ in the blood serum in children of all groups was carried out by the method of solid-phase ELISA using commercial test systems of LLC “Cytokin” (Russia). Results and discussion. 4 groups were formed: group I (n = 20) children with ARVI caused by DNA-containing viruses (group B, C, E adenoviruses, bocaviruses); group II (n = 53) children with ARVI caused by RNA viruses (RS virus, metapneumovirus, parainfluenza viruses 1, 2, 3, 4, rhinovirus and coronoviruses); group III (n = 12) children with ARVI caused by mixed infection; group IV (n = 7) – the genetic material of the pathogen has not been isolated. Concentration of IL-8, IL-17, IFN-γ was significantly increased in all groups compared to the normative values. Higher values of IFN-γ and IL-8 were revealed in patients with DNA viruses compared with the group with RNA-containing viruses, although the excess of IFN-γ was not statistically significant. Differences in the content of IFN-γ, IL-8 and IL-17 were noted for various etiological viral agents, but they were not significant. Conclusions. The results obtained can serve as confirmation that the functional characteristics of the response of the immune system in children with ARVI are determined not so much by the etiological factor as by its individual state. With ARVI in children, the presence of genetic material from more than one virus, apparently, is not a significant potentiating factor in the activation of the immune response. At the same time, a negative PCR result with a detailed clinical picture of ARVI does not exclude the viral genesis of the disease

Møllerov polarimetar za elektrone u dvorani A u JLabu

As part of the spin-physics program at Jefferson Laboratory (JLab), a Moller polarimeter was developed to measure the polarization of electron beam of energies 0.8 to 5.0 GeV. A unique signature for Moller scattering is obtained using a series of three quadrupole magnets which provide an angular selection, and a dipole magnet for energy analysis. The design, commissioning and the first results of the polarization measurements of this polarimeter will be presented as well as future plans to use its small scattering angle capabilities to investigate physics in very low Q2 regime.Kao dio programa istraživanja spinske fizike, u Jeffersonovom se laboratoriju sagradio Møllerov polarimetar radi mjerenja polarizacije elektrona energije 0,8 do 5,0 GeV. Jedinstven signal za Møllerovo raspršenje se postiže nizom od tri kvadrupolna magneta koji određuju kut, te dipolnim magnetom za analizu impulsa elektrona. Opis, preuzimanje i prva mjerenja s tim polarimetrom se izlažu, kao i planovi za buduću upotrebu mogućnosti sustava za mjerenja na malim kutovima raspršenja radi istraživanja fizike za vrlo male Q2

Solving the Simplest Theory of Quantum Gravity

We solve what is quite likely the simplest model of quantum gravity, the worldsheet theory of an infinitely long, free bosonic string in Minkowski space. Contrary to naive expectations, this theory is non-trivial. We illustrate this by constructing its exact factorizable S-matrix. Despite its simplicity, the theory exhibits many of the salient features expected from more mature quantum gravity models, including the absence of local off-shell observables, a minimal length, a maximum achievable (Hagedorn) temperature, as well as (integrable relatives of) black holes. All these properties follow from the exact S-matrix. We show that the complete finite volume spectrum can be reconstructed analytically from this S-matrix with the help of the thermodynamic Bethe Ansatz. We argue that considered as a UV complete relativistic two-dimensional quantum field theory the model exhibits a new type of renormalization group flow behavior, "asymptotic fragility". Asymptotically fragile flows do not originate from a UV fixed point.Comment: 32+4 pages, 1 figure, v2: typos fixed, published versio

Møllerov polarimetar za elektrone u dvorani A u JLabu

As part of the spin-physics program at Jefferson Laboratory (JLab), a Moller polarimeter was developed to measure the polarization of electron beam of energies 0.8 to 5.0 GeV. A unique signature for Moller scattering is obtained using a series of three quadrupole magnets which provide an angular selection, and a dipole magnet for energy analysis. The design, commissioning and the first results of the polarization measurements of this polarimeter will be presented as well as future plans to use its small scattering angle capabilities to investigate physics in very low Q2 regime.Kao dio programa istraživanja spinske fizike, u Jeffersonovom se laboratoriju sagradio Møllerov polarimetar radi mjerenja polarizacije elektrona energije 0,8 do 5,0 GeV. Jedinstven signal za Møllerovo raspršenje se postiže nizom od tri kvadrupolna magneta koji određuju kut, te dipolnim magnetom za analizu impulsa elektrona. Opis, preuzimanje i prva mjerenja s tim polarimetrom se izlažu, kao i planovi za buduću upotrebu mogućnosti sustava za mjerenja na malim kutovima raspršenja radi istraživanja fizike za vrlo male Q2

Polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei

The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The ($\gamma,pp$) and ($\gamma,pn$) angular cross sections, photon asymmetries and outgoing nucleon polarizations are calculated for the target nuclei $^{16}$O and $^{12}$C and photonenergies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on $^3S_1(T=0)$ proton-neutron and $^1S_0(T=1)$ proton-proton pairs in the nuclear medium. The calculations demonstrate that dominance of $S$ wave photoabsorption in the ($\gamma,pn$) channel does not necessarily imply that the reaction mechanism is similar to what is observed in deuteron photodisintegration.Comment: 27 pages, REVTeX 3.0 with epsf.sty, 11 figures in EPS forma

Quark-Hadron Duality in Neutron (3He) Spin Structure

We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.Comment: 13 pages, 3 figure

Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial wave analysis

Masses, widths and photocouplings of baryon resonances are determined in a coupled-channel partial wave analysis of a large variety of data. The Bonn-Gatchina partial wave formalism is extended to include a decomposition of t- and u-exchange amplitudes into individual partial waves. The multipole transition amplitudes for $\gamma p\to p\pi^0$ and $\gamma p\to n\pi^+$ are given and compared to results from other analyses.Comment: 18 pages, 14 figure