The charge ordered state in half-doped Bi-based manganites studied by 17^{17}O and 209^{209}Bi NMR

We present a $^{209}$Bi and $^{17}$O NMR study of the Mn electron spin correlations developed in the charge ordered state of Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ and Bi$_{0.5}$Ca$_{0.5}$MnO$_{3}$. The unusually large local magnetic field $^{209}H_{loc}$ indicates the dominant $6s^{2}$ character of the lone electron pair of Bi$^{3+}$-ions in both compounds. The mechanism connecting the $s$ character of the lone pairs to the high temperature of charge ordering $T_{CO}$ is still not clarified. The observed difference in $^{209}H_{loc}$ for Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ to Bi$_{0.5}$Ca$_{0.5}$MnO$_{3}$ is probably due to a decrease in the canting of the staggered magnetic moments of Mn$^{3+}$-ions from. The modification of the $^{17}$O spectra below $T_{CO}$ demonstrates that the line due to the apical oxygens is a unique local tool to study the development of the Mn spin correlations. In the AF state the analysis of the $^{17}$O spectrum of Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$ and Bi$_{0.5}$Sr$_{0.5}$MnO$_{3}$ prompts us to try two different theoretical descriptions of the charge-ordered state, a site-centered model for the first manganite and a bond-centered model for the second one.Comment: 10 pages, 7 figure

Роль убиквитин-протеасомной системы в развитии плоскоклеточного рака полости рта

 The ubiquitin-proteasome system (UPS) controls the activity, subcellular localization, and stability of many cellular proteins that affect cellular homeostasis by regulating multiple signaling cascades. The activity of this system is associated with the emergence and progression of oral squamous cell carcinoma, since specific proteolysis of most intracellular proteins involved in the pathogenesis of cancer is implemented by this system.The review article presents data on the characteristics of proteasomes and the process of substrate protein ubiquitination. The role of the ubiquitin-proteasome system in the pathogenesis of oral squamous cell carcinoma is shown, and the prospects of its use in precancerous diseases are described. The  literature search was carried out in the search engines Medline, eLIBRARY, Scopus, The Cochrane Library, and RSCI.  Убиквитин-протеасомная система контролирует активность, субклеточную локализацию и стабильность множества клеточных белков, которые влияют на клеточный гомеостаз посредством регуляции сигнальных каскадов. Активность данной системы связана с возникновением и  прогрессированием плоскоклеточного рака полости рта, так как специфический протеолиз большинства  внутриклеточных протеинов, участвующих в патогенезе рака, происходит с помощью вышеупомянутой системы.В обзорной статье представлены данные о характеристике  протеасом и процессе убиквинтирования белковсубстратов. Показана роль убиквитин-протеасомной системы в  патогенезе плоскоклеточного рака полости рта, приведены сведения о перспективах использования ее при предраке. Поиск литературы осуществлялся в поисковых системах Medline, Elibrary, Scopus, The Cochrane Library, РИНЦ.

Влияние гуминовых веществ угля и биокомпозиций с наночастицами серебра на их основе на баланс аргинина в перитонеальных макрофагах интактных мышей

Background. Antigen-presenting cells (APCs), especially macrophages, play an important role in the body defense against various pathogens. Their dysfunction and polarization are associated with most inflammatory and autoimmune diseases. The inflammatory process is regulated by activation and / or inhibition of genes differentially expressed by macrophages. Successful correction of inflammation leads firstly to elimination of inflammatory stimuli and then to remodeling and restoration of tissues and organs. It was experimentally confirmed that silvercontaining bionanocomposites based on natural humic substances (HS) obtained from coal of different origin, as well as initial matrices of these HS, are capable of activating pro- and anti-inflammatory properties of macrophages.Aim. To study cytotoxic, pyrogenic, and immunomodulatory properties (arginine balance) of initial HS samples and samples of silver nanoparticles ultradispersed in these HS matrices (HS-AgNPs) in the cell culture of peritoneal macrophages, as well as their effect on pro- and anti-inflammatory properties of APCs.Materials and methods. Cultural and biochemical methods were used in the study.Results. The study showed that the samples CHE-K, CHE-AgNPs, CHS-K, and CHP-K increased M1 macrophage polarization due to stimulation of the NO-synthase activity and inhibition of arginase. The samples CHI-K, CHIAgNPs, CHP-AgNPs, and CHS-AgNPs modulated an alternative M2 or M2-like state of macrophage activation. At the same time, HS are not cytotoxic at effective concentrations, and three out of four studied samples did not contain pyrogenic impurities.Conclusion. The use of HS and their silver-containing bionanocomposites, which have the ability to greatly affect the polarization of antigen-presenting cells, is a promising research area in correction of the inflammatory response for solving an important social and medical problem of treating chronic wounds. Введение. Антигенпрезентирующие клетки, особенно макрофаги, играют важную роль в защите организма от различных патогенов, их дисфункции, и поляризация связана с большинством воспалительных и аутоиммунных заболеваний. Воспалительный процесс жестко регулируется активацией и (или) ингибированием дифференциально экспрессируемых макрофагами генов. Успешная коррекция воспалительного процесса приводит к устранению воспалительных стимулов и далее ремоделированию и восстановлению тканей и органов. Экспериментально доказано, что биокомпозиции с наночастицами серебра на основе природных гуминовых веществ (ГВ) угля различного генеза, а также исходные матрицы данных ГВ способны активировать про- и противовоспалительные свойства макрофагов.Цель. Исследование в культуре клеток перитонеальных макрофагов цитотоксических, пирогенных и иммуномодулирующих свойств (баланс аргинина) исходных образцов ГВ и образцов наночастиц серебра, ультрадиспергированных в данных матрицах гуминовых веществ (ГВ-AgNPs),а также их влияния на про- и противовоспалительные свойства антигенпрезентирующих клеток. Материалы и методы. Использовались культуральные и биохимические методы.Результаты. Показано, что образцы CHE-K, CHE-AgNPs, CHS-K, CHP-K за счет усиления активности NOсинтазы и ингибиции аргиназы способствуют поляризации перитонеальных макрофагов по классическому типу (М1). Образцы CHI-K, CHI-AgNPs, CHP-AgNPs и CHS-AgNPs модулируют альтернативный М2 или M2-подобный тип (M2-like state) активации макрофагов. При этом ГВ не цитотоксичны в эффективных концентрациях, а также три из четырех исследуемых образцов не содержат пирогенных примесей.Заключение. Применение ГВ и серебросодержащих бионанокомпозиций на основе ГВ, обладающих способностью широко влиять на поляризацию антигенпрезентирующих клеток, является перспективным направлением исследований коррекции воспалительной реакции и, в частности, для решения острой социальной и медицинской проблемы – лечения хронических ран.

Centrality Dependence of Neutral Pion Production in 158 A GeV Pb + Pb Collisions

The production of neutral pions in 158AGeV Pb+Pb collisions has been studied in the WA98 experiment at the CERN SPS. Transverse momentum spectra are studied for the range 0.3 GeV/c < mT-m0 < 4.0 GeV/c. The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30 participating nucleons which is most naturally explained by assuming an equilibrated system.Comment: 5 pages, Latex, including 3 eps figures, submitted to Phys.Rev.Lett; updated pQCD comparison due to new input from the author, updated references, corrected plotting error in figure

Scaling of Particle and Transverse Energy Production in 208Pb+208Pb collisions at 158 A GeV

Transverse energy, charged particle pseudorapidity distributions and photon transverse momentum spectra have been studied as a function of the number of participants (N_{part}) and the number of binary nucleon-nucleon collisions (N_{coll}) in 158 A GeV Pb+Pb collisions over a wide impact parameter range. A scaling of the transverse energy pseudorapidity density at midrapidity as N_{part}^{1.08 \pm 0.06} and N_{coll}^{0.83 \pm 0.05} is observed. For the charged particle pseudorapidity density at midrapidity we find a scaling as N_{part}^{1.07 \pm 0.04} and N_{coll}^{0.82 \pm 0.03}. This faster than linear scaling with N_{part} indicates a violation of the naive Wounded Nucleon Model.Comment: 13 pages, 16 figures, submitted to European Physical Journal C (revised results for scaling exponents

Systematics of Inclusive Photon Production in 158 AGeV Pb Induced Reactions on Ni, Nb, and Pb Targets

The multiplicity of inclusive photons has been measured on an event-by-event basis for 158 AGeV Pb induced reactions on Ni, Nb, and Pb targets. The systematics of the pseudorapidity densities at midrapidity (rho_max) and the width of the pseudorapidity distributions have been studied for varying centralities for these collisions. A power law fit to the photon yield as a function of the number of participating nucleons gives a value of 1.13+-0.03 for the exponent. The mean transverse momentum, , of photons determined from the ratio of the measured electromagnetic transverse energy and photon multiplicity, remains almost constant with increasing rho_max. Results are compared with model predictions.Comment: 16 pages including 4 figure

Search for DCC in 158A GeV Pb+Pb Collisions

A detailed analysis of the phase space distributions of charged particles and photons have been carried out using two independent methods. The results indicate the presence of nonstatistical fluctuations in localized regions of phase space.Comment: Talk at the PANIC99 Conference, June 9-16, 199

Multiplicity Distributions and Charged-neutral Fluctuations

Results from the multiplicity distributions of inclusive photons and charged particles, scaling of particle multiplicities, event-by-event multiplicity fluctuations, and charged-neutral fluctuations in 158$\cdot A$ GeV Pb+Pb collisions are presented and discussed. A scaling of charged particle multiplicity as $N_{part}^{1.07\pm 0.05}$ and photons as $N_{part}^{1.12\pm 0.03}$ have been observed, indicating violation of naive wounded nucleon model. The analysis of localized charged-neutral fluctuation indicates a model-independent demonstration of non-statistical fluctuations in both charged particles and photons in limited azimuthal regions. However, no correlated charged-neutral fluctuations are observed.Comment: Talk given at the International Symposium on Nuclear Physics (ISNP-2000), Mumbai, India, 18-22 Dec 2000, Proceedings to be published in Pramana, Journal of Physic