389 research outputs found

    Registration of ovarian cancer in England and Wales

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    High potential for weathering and climate effects of non-vascular vegetation in the Late Ordovician

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    It has been hypothesized that predecessors of today’s bryophytes significantly increased global chemical weathering in the Late Ordovician, thus reducing atmospheric CO2 concentration and contributing to climate cooling and an interval of glaciations. Studies that try to quantify the enhancement of weathering by non-vascular vegetation, however, are usually limited to small areas and low numbers of species, which hampers extrapolating to the global scale and to past climatic conditions. Here we present a spatially explicit modelling approach to simulate global weathering by non-vascular vegetation in the Late Ordovician. We estimate a potential global weathering flux of 2.8 (km3 rock) yr−1, defined here as volume of primary minerals affected by chemical transformation. This is around three times larger than today’s global chemical weathering flux. Moreover, we find that simulated weathering is highly sensitive to atmospheric CO2 concentration. This implies a strong negative feedback between weathering by non-vascular vegetation and Ordovician climate

    Exposure to rosiglitazone, a PPAR-gamma agonist, in late gestation reduces the abundance of factors regulating cardiac metabolism and cardiomyocyte size in the sheep fetus

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    It is unknown whether cardiomyocyte hypertrophy and the transition to fatty acid oxidation as the main source of energy after birth is dependent on the maturation of the cardiomyocytes' metabolic system, or on the limitation of substrate availability before birth. This study aimed to investigate whether intrafetal administration of a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, rosiglitazone, during late gestation can stimulate the expression of factors regulating cardiac growth and metabolism in preparation for birth, and the consequences of cardiac contractility in the fetal sheep at ∼140 days gestation. The mRNA expression and protein abundance of key factors regulating growth and metabolism were quantified using quantitative RT-PCR and Western blot analysis, respectively. Cardiac contractility was determined by measuring the Ca(2+) sensitivity and maximum Ca(2+)-activated force of skinned cardiomyocyte bundles. Rosiglitazone-treated fetuses had a lower cardiac abundance of insulin-signaling molecules, including insulin receptor-β, insulin receptor substrate-1 (IRS-1), phospho-IRS-1 (Tyr-895), phosphatidylinositol 3-kinase (PI3K) regulatory subunit p85, PI3K catalytic subunit p110α, phospho-3-phosphoinositide-dependent protein kinase 1 (Ser-241), protein kinase B (Akt-1), phospho-Akt (Ser-273), PKCζ, phospho-PKCζ(Thr-410), Akt substrate 160 kDa (AS160), phospho-AS160 (Thr-642), and glucose transporter type-4. Additionally, cardiac abundance of regulators of fatty acid β-oxidation, including adiponectin receptor 1, AMPKα, phospho-AMPKα (Thr-172), phospho-acetyl CoA carboxylase (Ser-79), carnitine palmitoyltransferase-1, and PGC-1α was lower in the rosiglitazone-treated group. Rosiglitazone administration also resulted in a decrease in cardiomyocyte size. Rosiglitazone administration in the late-gestation sheep fetus resulted in a decreased abundance of factors regulating cardiac glucose uptake, fatty acid β-oxidation, and cardiomyocyte size. These findings suggest that activation of PPAR-γ using rosiglitazone does not promote the maturation of cardiomyocytes; rather, it may decrease cardiac metabolism and compromise cardiac health later in life.Shervi Lie, Melisa Hui, I. Caroline McMillen, Beverly S. Muhlhausler, Giuseppe S. Posterino, Stacey L. Dunn, Kimberley C. Wang, Kimberley J. Botting, Janna L. Morriso

    Low birth weight activates the renin-angiotensin system, but limits cardiac angiogenesis in early postnatal life

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    Low birth weight (LBW) is associated with increased risk of adult cardiovascular disease and this association may be partly a consequence of early programming of the renin-angiotensin system (RAS). We investigated the effects of LBW on expression of molecules in the RAS and cardiac tissue remodeling. Left ventricular samples were collected from the hearts of 21 days old lambs that were born average birth weight (ABW) and LBW. Cardiac mRNA expression was quantified using real-time RT-PCR and protein expression was quantified using Western blotting. DNA methylation and histone acetylation were assessed by combined bisulfite restriction analysis and chromatin immunoprecipitation, respectively. There were increased plasma renin activity, angiotensin I (ANGI), and ANGII concentrations in LBW compared to ABW lambs at day 20. In LBW lambs, there was increased expression of cardiac ACE2 mRNA, decreased ANGII receptor type 1 (AT1R) protein, and acetylation of histone H3K9 of the AT1R promoter but no changes in AT1R mRNA expression and AT1R promoter DNA methylation. There was no difference in the abundance of proteins involved in autophagy or fibrosis. BIRC5 and VEGF mRNA expression was increased; however, the total length of the capillaries was decreased in the hearts of LBW lambs. Activation of the circulating and local cardiac RAS in neonatal LBW lambs may be expected to increase cardiac fibrosis, autophagy, and capillary length. However, we observed only a decrease in total capillary length, suggesting a dysregulation of the RAS in the heart of LBW lambs and this may have significant implications for heart health in later life.Kimberley C. W. Wang, Doug A. Brooks, Brooke Summers‐Pearce, Larisa Bobrovskaya, Darran N. Tosh, Jaime A. Duffield, Kimberley J. Botting, Song Zhang, I. Caroline McMillen, Janna L. Morriso

    ‘I already have a culture.’ Negotiating competing grand and personal narratives in interview conversations with new study abroad arrivals

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    In an interview with a postgraduate student about her intercultural experience of recently arriving for study abroad, it was found that the two researchers and the student were engaged in a mutual exploration of cultural identity. The in- terview events became conversational and took the form of small culture formation on the go in which each participant employed diverse narratives to project, make sense of and negotiate expression of cultural identity. The stu- dent shifted between personal narratives drawn from her particular cultural trajectories and splintered from grand narratives of nation and global position- ing, between non- essentialist threads and essentialist blocks. The researchers learned from her and intervened to facilitate shifts to non-essentialist threads, drawing on narratives from their own personal cultural trajectories, but some- times also falling into essentialist blocks splintered from grand narratives. The roles of ideology and competing essentialist and non-essentialist discourses of culture were implicit in these negotiations, as were the personal agency of the student as she responded to the constraining conflicts, structures and hierarchies encountered through the events she spoke about. Rather than providing a picture of intercultural assimilation and integration, interculturality is revealed as a hesitant and searching negotiation, sometimes of vulnerability, wrong-footedness and occasional assault on identity
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