Aperiodic optical variability of intermediate polars - cataclysmic variables with truncated accretion disks

We study the power spectra of the variability of seven intermediate polars containing magnetized asynchronous accreting white dwarfs, XSS J00564+4548,IGR J00234+6141, DO Dra, V1223 Sgr, IGR J15094-6649, IGR J16500-3307 and IGR J17195-4100, in the optical band and demonstrate that their variability can be well described by a model based on fluctuations propagating in a truncated accretion disk. The power spectra have breaks at Fourier frequencies, which we associate with the Keplerian frequency of the disk at the boundary of the white dwarfs' magnetospheres. We propose that the properties of the optical power spectra can be used to deduce the geometry of the inner parts of the accretion disk, in particular: 1) truncation radii of the magnetically disrupted accretion disks in intermediate polars, 2) the truncation radii of the accretion disk in quiescent states of dwarf novaeComment: Accepted for publication in A&

Fibroid explants reveal a higher sensitivity against MDM2-inhibitor nutlin-3 than matching myometrium

<p>Abstract</p> <p>Background</p> <p>Spontaneous cessation of growth is a frequent finding in uterine fibroids. Increasing evidence suggests an important role of cellular senescence in this growth control. Deciphering the underlying mechanisms of growth control that can be expected not only to shed light on the biology of the tumors but also to identify novel therapeutic targets.</p> <p>Methods</p> <p>We have analyzed uterine leiomyomas and matching normal tissue for the expression of p14^Arfand used explants to see if reducing the MDM2 activity using the small-molecule inhibitor nutlin-3 can induce p53 and activate genes involved in senescence and/or apoptosis. For these studies quantitative real-time RT-PCR, Western blots, and immunohistochemistry were used. Statistical analyses were performed using the student's <it>t </it>test.</p> <p>Results</p> <p>An in depth analysis of 52 fibroids along with matching myometrium from 31 patients revealed in almost all cases a higher expression of p14^Arfin the tumors than in the matching normal tissue. In tissue explants, treatment with the MDM2 inhibitor nutlin-3 induced apoptosis as well as senescence as revealed by a dose-dependent increase of the expression of <it>BAX </it>as well as of <it>p21</it>, respectively. Simultaneously, the expression of the proliferation marker Ki-67 drastically decreased. Western-blot analysis identified an increase of the p53 level as the most likely reason for the increased activity of its downstream markers <it>BAX </it>and <it>p21</it>. Because as a rule fibroids express much higher levels of p14^Arf, a major negative regulator of MDM2, than matching myometrium it was then analyzed if fibroids are more sensitive against nutlin-3 treatment than matching myometrium. We were able to show that in most fibroids analyzed a higher sensibility than that of matching myometrium was noted with a corresponding increase of the p53 immunopositivity of the fibroid samples compared to those from myometrium.</p> <p>Conclusions</p> <p>The results show that uterine fibroids represent a cell population of advanced cellular age compared to matching myometrium. Moreover, the data point to members of the p53-network as to potential novel therapeutic targets for the treatment of uterine fibroids.</p

Chromium removal from aqueous solution by a PEI-silica nanocomposite

It is essential and important to determine the adsorption mechanism as well as removal efficiency when using an adsorption technique to remove toxic heavy metals from wastewater. In this research, the removal efficiency and mechanism of chromium removal by a silica-based nanoparticle were investigated. A PEI-silica nanoparticle was synthesized by a one-pot technique and exhibited uniformly well-dispersed PEI polymers in silica particles. The adsorption capacity of chromium ions was determined by a batch adsorption test, with the PEI-silica nanoparticle having a value of 183.7 mg/g and monolayer sorption. Adsorption of chromium ions was affected by the solution pH and altered the nanoparticle surface chemically. First principles calculations of the adsorption energies for the relevant adsorption configurations and XPS peaks of Cr and N showed that Cr(VI), [HCrO4](-) is reduced to two species, Cr(III), CrOH2+ and Cr3+, by an amine group and that Cr(III) and Cr(VI) ions are adsorbed on different functional groups, oxidized N and NH3+

HIF1α drives chemokine factor pro-tumoral signaling pathways in acute myeloid leukemia

Approximately 80% of patients diagnosed with acute myeloid leukemia (AML) die as a consequence of failure to eradicate the tumor from the bone marrow microenvironment. We have recently shown that stroma-derived interleukin-8 (IL-8) promotes AML growth and survival in the bone marrow in response to AML-derived macrophage migration inhibitory factor (MIF). In the present study we show that high constitutive expression of MIF in AML blasts in the bone marrow is hypoxia-driven and, through knockdown of MIF, HIF1α and HIF2α, establish that hypoxia supports AML tumor proliferation through HIF1α signaling. In vivo targeting of leukemic cell HIF1α inhibits AML proliferation in the tumor microenvironment through transcriptional regulation of MIF, but inhibition of HIF2α had no measurable effect on AML blast survival. Functionally, targeted inhibition of MIF in vivo improves survival in models of AML. Here we present a mechanism linking HIF1α to a pro-tumoral chemokine factor signaling pathway and in doing so, we establish a potential strategy to target AML

Оптические свойства аэрозоля раствора нанопорошка феррита кобальта

Optimal concentrations of the cobalt ferrite nanopowder for production of a stable aerosol are determined. The dependence of laser radiation absorption by the aerosol on the nanomaterial concentration in the initial solution is revealed.Определены оптимальные концентрации нанопорошка феррита кобальта для получения устойчивого аэрозоля, выявлена зависимость поглощения лазерного излучения аэрозолем от концентрации наноматериала в исходном растворе

Rad51 Polymerization Reveals a New Chromatin Remodeling Mechanism

Rad51 protein is a well known protagonist of homologous recombination in eukaryotic cells. Rad51 polymerization on single-stranded DNA and its role in presynaptic filament formation have been extensively documented. Rad51 polymerizes also on double-stranded DNA but the significance of this filament formation remains unclear. We explored the behavior of Saccharomyces cerevisiae Rad51 on dsDNA and the influence of nucleosomes on Rad51 polymerization mechanism to investigate its putative role in chromatin accessibility to recombination machinery. We combined biochemical approaches, transmission electron microscopy (TEM) and atomic force microscopy (AFM) for analysis of the effects of the Rad51 filament on chromatinized templates. Quantitative analyses clearly demonstrated the occurrence of chromatin remodeling during nucleoprotein filament formation. During Rad51 polymerization, recombinase proteins moved all the nucleosomal arrays in front of the progressing filament. This polymerization process had a powerful remodeling effect, as Rad51 destabilized the nucleosomes along considerable stretches of DNA. Similar behavior was observed with RecA. Thus, recombinase polymerization is a powerful mechanism of chromatin remodeling. These remarkable features open up new possibilities for understanding DNA recombination and reveal new types of ATP-dependent chromatin dynamics

Deciphering the sophomore slump: changes to student perceptions during the undergraduate journey

The second year of university is little-researched, despite being a focal point for declining performance, persistence, and satisfaction. It is important to establish appropriate methods for studying this ‘sophomore slump’ and to pinpoint specific antecedents from broad domains noted in literature (e.g. students’ social integration, perceptions of the curriculum). Using a novel methodology, 166 undergraduates were surveyed in successive years of study to derive a gold standard ‘within-subjects’ data sample. Under a replicated design, a ‘between-subjects’ sample of over 1000 students completed the same e-survey just once, in year one, two, or three. Quantitative comparison of the responses across years showed over 85% agreement between samples. This endorses between-subject approaches (i.e. simultaneously surveying students from different years) to facilitate rapid interventions that benefit students before they graduate. In terms of detailed findings, year two saw positive trends in students’ academic engagement (e.g. self-reported independent study time), social integration (e.g. feeling accepted, involvement in extra-curricular activities), and views on teaching staff (e.g. approachability). Although appraisals remained broadly favourable, there was, in contrast, significant deterioration in global perceptions of the learning atmosphere (e.g. course enjoyment), as well as specific elements of the teaching provision (e.g. contact hours, feedback). Notably, there appeared to be little progression in students’ academic self-perceptions (e.g. confidence to make presentations, enter class debates). Year two also saw increased thoughts of drop-out. These results highlight the unique character of the second year at university and indicate potential target areas for enhancing this phase of the undergraduate journey

Regulation of ABCC6 trafficking and stability by a conserved C-terminal PDZ-like sequence

Mutations in the ABCC6 ABC-transporter are causative of pseudoxanthoma elasticum (PXE). The loss of functional ABCC6 protein in the basolateral membrane of the kidney and liver is putatively associated with altered secretion of a circulatory factor. As a result, systemic changes in elastic tissues are caused by progressive mineralization and degradation of elastic fibers. Premature arteriosclerosis, loss of skin and vascular tone, and a progressive loss of vision result from this ectopic mineralization. However, the identity of the circulatory factor and the specific role of ABCC6 in disease pathophysiology are not known. Though recessive loss-of-function alleles are associated with alterations in ABCC6 expression and function, the molecular pathologies associated with the majority of PXE-causing mutations are also not known. Sequence analysis of orthologous ABCC6 proteins indicates the C-terminal sequences are highly conserved and share high similarity to the PDZ sequences found in other ABCC subfamily members. Genetic testing of PXE patients suggests that at least one disease-causing mutation is located in a PDZ-like sequence at the extreme C-terminus of the ABCC6 protein. To evaluate the role of this C-terminal sequence in the biosynthesis and trafficking of ABCC6, a series of mutations were utilized to probe changes in ABCC6 biosynthesis, membrane stability and turnover. Removal of this PDZ-like sequence resulted in decreased steady-state ABCC6 levels, decreased cell surface expression and stability, and mislocalization of the ABCC6 protein in polarized cells. These data suggest that the conserved, PDZ-like sequence promotes the proper biosynthesis and trafficking of the ABCC6 protein. © 2014 Xue et al

Perturbation of Host Nuclear Membrane Component RanBP2 Impairs the Nuclear Import of Human Immunodeficiency Virus -1 Preintegration Complex (DNA)

HIV-1 is a RNA virus that requires an intermediate DNA phase via reverse transcription (RT) step in order to establish productive infection in the host cell. The nascent viral DNA synthesized via RT step and the preformed viral proteins are assembled into pre-integration complex (PIC) in the cell cytoplasm. To integrate the viral DNA into the host genome, the PIC must cross cell nuclear membrane through the nuclear pore complex (NPC). RanBP2, also known as Nup358, is a major component of the cytoplasmic filaments that emanates from the nuclear pore complex and has been implicated in various nucleo-cytoplasmic transport pathways including those for HIV Rev-protein. We sought to investigate the role of RanBP2 in HIV-1 replication. In our investigations, we found that RanBP2 depletion via RNAi resulted in profound inhibition of HIV-1 infection and played a pivotal role in the nuclear entry of HIV DNA. More precisely, there was a profound decline in 2-LTR DNA copies (marker for nuclear entry of HIV DNA) and an unchanged level of viral reverse transcription in RanBP2-ablated HIV-infected cells compared to RanBP3-depleted or non-specific siRNA controls. We further demonstrated that the function of Rev was unaffected in RanBP2-depleted latently HIV infected cells (reactivated). We also serendipitously found that RanBP2 depletion inhibited the global ectopic gene expression. In conclusion, RanBP2 is a host factor that is involved in the nuclear import of HIV-1 PIC (DNA), but is not critical to the nuclear export of the viral mRNAs or nucleo-cytoplasmic shuttling of Rev. RanBP2 could be a potential target for efficient inhibition of HIV

Nuclear Interactions Of Super High Energy Cosmic-rays Observed In Mountain Emulsion Chambers

Here we present a summary of joint discussions on the results of three mountain experiments with large-scale emulsion chambers, at Pamir, Mt. Fuji and Chacaltaya. Observations cover gamma quanta, hadrons and their clusters (called "families"). The following topics are covered, concerning the characteristics of nuclear interactions the energy region 1014-1016 eV: (i) rapid dissipation seen in atmospheric diffusion of high-energy cosmic-rays; (ii) multiplicity and Pt increase in produced pi-mesons in the fragmentation region; (iii) existence of large-Pt jets, (iv) extremely hadron-rich family of the Centauro type; (v) exotic phenomena in the extremely high energy region beyond 1016 eV. © 1981.1911125(1977) Acta Univ. Lodz ser. II, (60)(1973) 13th Int. Cosmic-ray Conf., 3, p. 2228(1975) 14th Int. Cosmic-Ray Conf., 7, p. 2365(1979) AIP Conf. Proc. no. 49, p. 334(1979) 16th Int. Cosmic-ray Conf., 6, p. 344(1979) 16th Int. Cosmic-ray Conf., 7, p. 6816th Int. Cosmic-ray Conf. (1979) 16th Int. Cosmic-ray Conf., 7, p. 284(1979) 16th Int. Cosmic-ray Conf., 7, p. 294(1979) 16th Int. Cosmic-ray Conf., 13, p. 87(1979) 16th Int. Cosmic-ray Conf., 13, p. 92(1979) 16th Int. Cosmic-ray Conf., 13, p. 98(1979) AIP Conf. Proc. no. 49, p. 94(1979) AIP Conf. Proc. no. 49, p. 145(1979) AIP Conf. Proc. no. 49, p. 317(1979) 16th Int. Cosmic-ray Conf., 6, p. 350(1979) 16th Int. Cosmic-ray Conf., 6, p. 356(1979) 16th Int. Cosmic-ray Conf., 6, p. 362Nikolsky, Proc. 9th Int. High-energy Symp. (1978) CSSR, 21. , ToborMiyake, (1978) Proc. 19th Int. Conf. on High-energy physics, p. 433Vernov, (1977) Physica, 3, p. 1601Khristiansen, (1978) JETP Lett., 28, p. 124(1973) 13th Int. Cosmic-ray Conf., 3, p. 2219Izv. Acad. Nauk USSR, ser Phys. (1974) Izv. Acad. Nauk USSR, ser Phys., 38, p. 918(1975) 14th Int. Cosmic-ray Conf., 7, p. 2365(1979) 16th Int. Cosmic-ray Conf., 7, p. 68Dunaevsky, Urysson, Emelyanov, Shorin, Tashimov, (1975) FIAN preprint no. 150Dunaevsky, Urysson, Emelyanov, Shorin, Tashinov, (1979) Acta Univ. Lodz ser. II, (60), p. 199Ivanenko, Kanevskya, Roganova, (1978) JETP Lett., 40, p. 704Ivanenko, Kanevsky, Roganova, (1979) 16th Int. Cosmic-ray Conf., 7, p. 101Ivanenko, Kanevsky, Roganova, (1979) 16th Int. Cosmic-ray Conf., 7, p. 198Wrotniak, (1977) Acta Univ. Lodz ser. II, (60), p. 165Krys, Tomaszevski, Wrotniak, (1979) 16th Int. Cosmic-ray Conf., 7, p. 182Krys, Tomaszevski, Wrotniak, (1979) 16th Int. Cosmic-ray Conf., 7, p. 186Fomin, Kempa, Khristiansen, Levina, Piotrowska, Wdowczyk, (1977) 15th Int. Cosmic-ray Conf., 7, p. 248Fomin, Kempa, Khristiansen, Levina, Piotrowska, Wdowczyk, (1979) 16th Int. Cosmic-ray Conf., 13, p. 82Azimov, Mullazhanov, Yuldashbayev, (1979) 16th Int. Cosmic-ray Conf., 7, p. 262Azimov, Mullazhanov, Yuldashbayev, (1977) Acta Univ. Lodz ser. II, (60), p. 275Kasahara, Torri, Yuda, (1979) 16th Int. Cosmic-ray Conf., 13, p. 70Kasahara, Torii, Yuda, (1979) 16th Int. Cosmic-ray Conf., 13, p. 79Shibata, (1979) 16th Int. Cosmic-ray Conf., 7, p. 176H. Semba, T. Shibata and T. Tabuki, Suppl. Prog. Theor. Phys., to be publishedZhdanov, Roinishvilli, Smorodin, Tomaszevski, (1975) FIAN preprint no. 163Lattes, Fujimoto, Hasegawa, Hadronic interactions of high energy cosmic-ray observed by emulsion chambers (1980) Physics Reports, 65, p. 152Ellsworth, Gaisser, Yodh, (1981) Phys. Rev., 23 D, p. 764Baradzei, Smorodin, (1974) FIAN preprint nos. 103, 104Baradzei, Smorodin, (1977) Acta Univ. Lodz ser. II, (60), p. 51Zhdanov, (1980) FIAN preprint no. 140H. Semba, T. Shibata and T. Tabuki, Suppl. Prog. Theor. Phys., to be publishedShibata, (1980) Phys. Rev., 22 D, p. 100Slavatinsky, (1980) Proc. 7th European Symp. on Cosmic rays, , Leningrad, to be published(1979) AIP Conference Proc. no. 49, p. 145Azimov, Abduzhamilov, Chudakov, (1963) JETP (Sov. Phys.), 45, p. 40713th Int. Cosmic-ray Conf. (1973) 13th Int. Cosmic-ray Conf., 5, p. 326Acharya, Rao, Sivaprasad, Rao, (1979) 16th Int. Cosmic-ray Conf., 6, p. 289Ellsworth, Goodman, Yodh, Gaisser, Stanev, (1981) Phys. Rev., 23 D, p. 771Bariburina, Guseva, Denisova, (1980) Acta Univ. Lodz, 1, p. 9415th Int. Cosmic-ray Conf. (1977) 15th Int. Cosmic-ray Conf., 7, p. 184(1979) AIP Conf. Proc. no. 49, p. 33