2,557 research outputs found

    Development of cyclosporin A mediated immunity in L1210 leukaemia.

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    Cyclosporin A (CsA) is an effective modulator of multidrug resistance (MDR) in vitro and in murine tumour systems in vivo. We now report the production of immunity to L1210 leukaemia by the addition of CsA to VP-16 therapy of leukaemic BDF/1 mice. VP-16/cyclosporin A tumour immunity induction arises as a consequence of active therapy independently of immunisation with modified tumour cells. The addition of CsA to VP-16 prolongs survival of BDF/1 host mice bearing L1210 leukaemia beyond that produced by equivalent dose VP-16 alone. A subpopulation of 60-day surviving mice after combined VP-16/CsA are immune to rechallenge with the same leukaemia inoculum to which they were originally exposed. Spleen cells from immune mice adoptively transfer anti-L1210 leukaemia immunity to untreated BDF/1 mice in a dose dependent, statistically significant manner. Adoptive transfer experiments additionally suggest active recruitment of immunologic response in recipient animals: (1) We have been able to perpetuate leukaemia immunity in four sequential cohorts of naive recipient mice. This propogation of adoptive immunity is accomplished by use of spleen cells harvested from each preceeding passively-protected animal cohort; (2) Cyclophosphamide pretreatment of adoptive transfer recipient mice abrogates the ability of their splenocytes to perpetuate passive protection in sequential adoptive transfer experiments

    Media(ted) fabrications: How the science-media symbiosis helped ‘sell’ cord banking

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    This paper considers the problematic role of the science–media symbiosis in the dissemination of misleading and emotionally manipulative information regarding services offered by CordBank, New Zealand's only umbilical cord blood banking facility. As this case study illustrates, the growing reliance of health and science reporters on the knowledge capital of medical specialists, biogenetic researchers, and scientists potentially enhances the ability of ‘expert’ sources to set the agenda for media representations of emerging medical and scientific developments, and may undermine the editorial independence of journalists and editors, many of whom in this case failed to critically evaluate deeply problematic claims regarding the current and future benefits of cord banking. Heavy reliance on established media frames of anecdotal personalization and technoboosterism also reinforced a proscience journalistic culture in which claims by key sources were uncritically reiterated and amplified, with journalistic assessments of the value of cord banking emphasizing potential benefits for individual consumers. It is argued that use of these media frames potentially detracts from due consideration of the broader social, ethical, legal, and health implications of emerging biomedical developments, along with the professional, personal, and increasingly also financial interests at stake in their public promotion, given the growing commercialization of biogenetic technologies

    Can Extra Mixing in RGB and AGB Stars Be Attributed to Magnetic Mechanisms?

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    It is known that there must be some weak form of transport (called cool bottom processing, or CBP) acting in low mass RGB and AGB stars, adding nuclei, newly produced near the hydrogen-burning shell, to the convective envelope. We assume that this extra-mixing originates in a stellar dynamo operated by the differential rotation below the envelope, maintaining toroidal magnetic fields near the hydrogen-burning shell. We use a phenomenological approach to the buoyancy of magnetic flux tubes, assuming that they induce matter circulation as needed by CBP models. This establishes requirements on the fields necessary to transport material from zones where some nuclear burning takes place, through the radiative layer, and into the convective envelope. Magnetic field strengths are determined by the transport rates needed by CBP for the model stellar structure of a star of initially 1.5 solar mass, in both the AGB and RGB phases. The field required for the AGB star in the processing zone is B_0 ~ 5x10^6 G; at the base of the convective envelope this yields an intensity B_E < 10^4 G (approximately). For the RGB case, B_0 ~ 5x10^4 to 4x10^5 G, and the corresponding B_E are ~ 450 to 3500 G. These results are consistent with existing observations on AGB stars. They also hint at the basis for high field sources in some planetary nebulae and the very large fields found in some white dwarfs. It is concluded that transport by magnetic buoyancy should be considered as a possible mechanism for extra mixing through the radiative zone, as is required by both stellar observations and the extensive isotopic data on circumstellar condensates found in meteorites.Comment: 26 pages, 4 figures, accepted by Astrophysical Journa

    The SAMI Galaxy Survey: Gas Streaming and Dynamical M/L in Rotationally Supported Systems

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    Line-of-sight velocities of gas and stars can constrain dark matter (DM) within rotationally supported galaxies if they trace circular orbits extensively. Photometric asymmetries may signify non-circular motions, requiring spectra with dense spatial coverage. Our integral-field spectroscopy of 178 galaxies spanned the mass range of the SAMI Galaxy Survey. We derived circular speed curves (CSCs) of gas and stars from non-parametric Diskfit fits out to r2rer\sim2r_e. For 12/14 with measured H I profiles, ionized gas and H I maximum velocities agreed. We fitted mass-follows-light models to 163 galaxies by approximating the radial starlight profile as nested, very flattened mass homeoids viewed as a S\'ersic form. Fitting broad-band SEDs to SDSS images gave median stellar mass/light 1.7 assuming a Kroupa IMF vs. 2.6 dynamically. Two-thirds of the dynamical mass/light measures were consistent with star+remnant IMFs. One-fifth required upscaled starlight to fit, hence comparable mass of unobserved baryons and/or DM distributed similarly across the SAMI aperture that came to dominate motions as the starlight CSC declined rapidly. The rest had mass distributed differently from starlight. Subtracting fits of S\'ersic profiles to 13 VIKING Z-band images revealed residual weak bars. Near the bar PA, we assessed m = 2 streaming velocities, and found deviations usually <30 km/s from the CSC; three showed no deviation. Thus, asymmetries rarely influenced our CSCs despite co-located shock-indicating, emission-line flux ratios in more than 2/3.Comment: 21 pages, 15 figures. Accepted to MNRA

    Targeted online liquid chromatography electron capture dissociation mass spectrometry for the localization of sites of in vivo phosphorylation in human Sprouty2

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    We demonstrate a strategy employing collision-induced dissociation for phosphopeptide discovery, followed by targeted electron capture dissociation (ECD) for site localization. The high mass accuracy and low background noise of the ECD mass spectra allow facile sequencing of coeluting isobaric phosphopeptides, with up to two isobaric phosphopeptides sequenced from a single mass spectrum. In contrast to the previously described neutral loss of dependent ECD method, targeted ECD allows analysis of both phosphotyrosine peptides and lower abundance phosphopeptides. The approach was applied to phosphorylation analysis of human Sprouty2, a regulator of receptor tyrosine kinase signaling. Fifteen sites of phosphorylation were identified, 11 of which are novel

    The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts

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    The apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives

    The Economic Resource Receipt of New Mothers

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    U.S. federal policies do not provide a universal social safety net of economic support for women during pregnancy or the immediate postpartum period but assume that employment and/or marriage will protect families from poverty. Yet even mothers with considerable human and marital capital may experience disruptions in employment, earnings, and family socioeconomic status postbirth. We use the National Survey of Families and Households to examine the economic resources that mothers with children ages 2 and younger receive postbirth, including employment, spouses, extended family and social network support, and public assistance. Results show that many new mothers receive resources postbirth. Marriage or postbirth employment does not protect new mothers and their families from poverty, but education, race, and the receipt of economic supports from social networks do
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