The Lambda_b lifetime in the light front quark model

The enhancement of the Lambda_b decay width relative to B decay one due to the difference of Fermi motion effects in Lambda_b and B is calculated in the light--front quark model with the simplifying assumption that Lambda_b consists of the heavy quark and light scalar diquark. In order to explain the large deviation from unity in the experimental result for tau(Lambda_b)/tau(B), it is necessary that diquark be light and the ratio of the squares of the Lambda_b and B wave functions at the origin be \le 1.Comment: final journal version to appear in JETP Letter

Nonlinear saturation of electrostatic waves: mobile ions modify trapping scaling

The amplitude equation for an unstable electrostatic wave in a multi-species Vlasov plasma has been derived. The dynamics of the mode amplitude $\rho(t)$ is studied using an expansion in $\rho$; in particular, in the limit $\gamma\rightarrow0^+$, the singularities in the expansion coefficients are analyzed to predict the asymptotic dependence of the electric field on the linear growth rate $\gamma$. Generically $|E_k|\sim \gamma^{5/2}$, as $\gamma\rightarrow0^+$, but in the limit of infinite ion mass or for instabilities in reflection-symmetric systems due to real eigenvalues the more familiar trapping scaling $|E_k|\sim \gamma^{2}$ is predicted.Comment: 13 pages (Latex/RevTex), 4 postscript encapsulated figures which are included using the utility "uufiles". They should be automatically included with the text when it is downloaded. Figures also available in hard copy from the authors ([email protected]

Tubulohelical membrane arrays: From the initial observation to the elucidation of nanophysical properties and cellular function

Lipids undergo self-assembly to form ordered nonlamellar, nanoperiodic arrays both in vitro and in vivo. While engineering of such membrane arrays for technical devices is envisaged, we know little about their cellular function. Do they represent building blocks of an inherent cellular nanotechnology? Prospects for answering this question could be improved if the nanophysical properties of the membrane arrays could be studied in the context of specific cellular functions. Therefore, we draw attention to exceptional complex membrane arrays found in the renal epithelial cell line PtK2 that could provide perfect conditions for both biophysical and cell functional studies. The so-called tubulohelical membrane arrays (TUHMAs) combine nanoperiodicity of lipid membranes with that of helix-like proteinaceous core structures. Strikingly, they show several characteristics of dynamic, microtubule-associated single organelles. Our initial data indicate that TUHMA formation occurs in the depth of the cytoplasm under participation of cytoplasmic nucleoporins. Once matured, they may fuse with the nuclear membrane in polarized positions, either perpendicularly or in parallel to the nucleus. As a starting point for the initiation of functional studies we found a connection between TUHMAs and primary cilia, indicated by immunolabeling patterns of detyrosynated tubulin and cytoplasmic nucleoporins. We discuss these observations in the context of the ciliary cycle and of the specific requirement of ciliated renal epithelial cells for oriented cell division. Finally, we raise the question of whether putative nanooptical properties of TUHMAs could serve for communicating orientation between dividing cells

Molecular architecture of the Nup84–Nup145C–Sec13 edge element in the nuclear pore complex lattice

Nuclear pore complexes (NPCs) facilitate all nucleocytoplasmic transport. These massive protein assemblies are modular, with a stable structural scaffold supporting more dynamically attached components. The scaffold is made from multiple copies of the heptameric Y complex and the heteromeric Nic96 complex. We previously showed that members of these core subcomplexes specifically share an ACE1 fold with Sec31 of the COPII vesicle coat, and we proposed a lattice model for the NPC based on this commonality. Here we present the crystal structure of the heterotrimeric 134-kDa complex of Nup84–Nup145C–Sec13 of the Y complex. The heterotypic ACE1 interaction of Nup84 and Nup145C is analogous to the homotypic ACE1 interaction of Sec31 that forms COPII lattice edge elements and is inconsistent with the alternative 'fence-like' NPC model. We construct a molecular model of the Y complex and compare the architectural principles of COPII and NPC lattices.National Institutes of Health (U.S.) (Grant GM77537)Pew Charitable Trusts (Scholar Award

Reparative processes in liver after laser exposure of bone marrow localization zones

We investigated the features of reparative process in the resected liver after laser irradiation of the zones of red bone marrow localization In rat experiment, the wedge-shaped resection of a liver lobe was performed. Infrared laser was applied for 5 days after the operation. The hystological analysis of liver specimens demonstrated the increase in hepatocyte proliferation with the increase in the ki-67 index and the nuclear-cytoplasmic ratio, the increase in binuclear hepatocytes number, the increase in the expression level of VEGF and Hsp 70 in the laser treatment group that is the evidence of successful recovery process and neoangiogenesis. The activation of hepatic tissue regeneration after laser irradiation of bone marrow localization zones may be the basis for the development of methods for treatment of liver disease patients.Исследованы особенности репаративных процессов в резецированной печени после лазерного воздействия на зоны локализации красного костного мозга. В эксперименте на крысах моделировали клиновидную резекцию доли печени. Лазерное воздействие осуществляли инфракрасным лазером в течение 5 суток после операции. После морфометрического анализа препаратов печени отмечено усиление пролиферации гепатоцитов с повышением индекса кi-67 и ядерно-цитоплазматического отношения, увеличение содержания двуядерных гепатоцитов, повышение уровня экспрессии VEGF и Hsp 70, что является свидетельством успешно протекающих восстановительных процессов и неоангиогенеза. Полученные данные об активации регенерации печеночной ткани после лазерного воздействия на зоны локализации костного мозга могут являться основой для разработки методов лечения пациентов с заболеваниями печени

Brr6 drives the Schizosaccharomyces pombe spindle pole body nuclear envelope insertion/extrusion cycle

Insertion into and release of the cytoplasmic domain of the Schizosaccharomyces pombe spindle pole body from a nuclear envelope fenestra during mitosis requires Brr6

БАЛАНС ВЗАИМОДЕЙСТВИЯ ЭФФЕКТОРНЫХ И РЕГУЛЯТОРНЫХ КЛЕТОК ПАМЯТИ КАК ОСНОВА ВЫРАБОТКИ УСТОЙЧИВОЙ ИММУННОЙ ТОЛЕРАНТНОСТИ ПРИ ПЕРЕСАДКЕ ОРГАНОВ (АНАЛИЗ ПРОБЛЕМЫ НА ПРИМЕРЕ ТРАНСПЛАНТАЦИИ ПЕЧЕНИ)

In this article the main mechanisms and methods of immune tolerance producing under influence of different antigenic loads in organism were considered. It was shown that the state of steady tolerance was produced by making the balance of effectory and regulatory cell interactions into innate and adaptive immunities. But because of a high risk of transplant rejection at different methods of tolerance producing it is necessary to work out safe diagnostic and prognostic methods for controlling of an individual level and power tolerance stability. В статье представлен анализ механизмов и способов выработки иммунной толерантности в организме при воздействии антигенных нагрузок различной природы. Показано, что состояние устойчивой толерантности достигается путем воссоздания баланса взаимодей- ствия эффекторных и регуляторных клеток во врожденной и адаптивной иммунной системе. Однако из- за высокого риска отторжения трансплантата при разных способах выработки толерантности возникает необходимость разработки надежных диагностических и прогностических методов контроля уровня и степени индивидуальной устойчивости толерантности.

СОВРЕМЕННАЯ ТАКТИКА ИММУНОСУПРЕССИВНОЙ ТЕРАПИИ КАК СПОСОБ ФОРМИРОВАНИЯ ТОЛЕРОГЕННОЙ СТРАТЕГИИ ОРГАНИЗМА (НА ПРИМЕРЕ ТРАНСПЛАНТАЦИИ ПЕЧЕНИ)

In this article the necessity of working out of individual therapeutical immunosuppressive tactics was consi- dered. The authors believe that doses and schemes of used drugs must not prevent the immunity regulation. Immunosuppressive drugs must induce native mechanisms of immune tolerance and reparative regeneration for preventing of fibrotic processes in grafts (liver). For optimal effect of drug immunosuppression after clinical liver transplantation it was suggested to reveal tole- rogenic recipient’s groups and also to work out and use informative diagnostic and prognostic methods for value of individual level and power tolerance stability of recipients. В статье обсуждается необходимость разработки индивидуальной тактики медикаментозной иммуно- супрессии при трансплантации органов (печени). Авторы полагают, что препараты, их дозы и схемы применения не должны препятствовать регуляции иммунитета. Их назначение – тормозить образование эффекторных клеток и клеток памяти, а также способствовать индукции естественных механизмов толе- рантности и репаративной регенерации, тормозящих процессы фиброзирования органов (печени). Для оптимизации медикаментозной иммуносупрессии при трансплантации печени в клинике авторы предлагают выявлять толерогенные группы реципиентов, а также разрабатывать и применять инфор- мативные диагностические и прогностические методы для оценки уровня и степени индивидуальной толерогенной устойчивости реципиентов.