75 research outputs found

    Cheilanthoid Ferns (Pteridaceae: Cheilanthoideae) in the Southwestern United States and Adjacent Mexico-A Molecular Phylogenetic Reassessment of Generic Lines

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    Cheilanthoids are the most commonly encountered fern species of the arid southwest and other xeric habitats throughout the world. Cheilanthes, Notholaena, Pellaea, and Bommeria are the best known southwestern genera, but some authors recognize segregate genera such as Argyrochosma, Aspidotis, Astrolepis, and Pentagramma. Others reject distinctions among some of these genera as artificial, leaving cheilanthoid generic concepts in a state of flux. This unsettled taxonomy is often attributed to morphological homoplasy associated with adaptation to xeric habitats, suggesting the need for new analyses that do not depend on potentially misleading morphology. Nucleotide sequences of the maternally inherited, chloroplast-encoded rbcL gene from 57 species that bear on the relationships of the cheilanthoids of the southwest were cladistically analyzed under the optimality criterion of maximum parsimony. The results provide new insights into phylogenetic relationships and generic circumscriptions of these ferns. Mexican Llavea cordifolia is rejected from the cheilanthoids, traditional Cheilanthes, Notholaena, and Pellaea are polyphyletic, and the segregations of Argyrochosma, Aspidotis, Astrolepis, and Pentagramma are supported. To assess confidence in these conclusions, results of the rbcL-based analysis are compared with those based on ITS sequences of biparentally inherited nuclear ribosomal DNA (nrDNA) for a subset of cheilanthoid taxa. These two data sets yield remarkably congruent topologies at shallower phylogenetic levels, suggesting that previous taxonomic problems in this group may indeed be attributable to difficulties in interpreting the taxonomic significance of morphological characters. Disagreement at deeper levels of the topologies suggests the need to incorporate data from less rapidly evolving nrDNA regions

    Salt and ionic cocrystalline forms of amides: protonation of carbamazepine in aqueous media

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    The products of reactions of the pharmaceutical amide carbamazepine (CBZ) with strong acids under aqueous conditions were investigated by both powder and single crystal X-ray diffraction. Despite previous claims to the contrary, it was found that salt forms with CBZ protonated at the amide O atom could be isolated from reactions with both HCl and HBr. These forms include the newly identified hydrate phase [CBZ(H)][Cl]·H O. Reactions with other mineral acids (HI and HBF ) gave ionic cocrystalline (ICC) forms (CBZ· [acridinium][I ]·2.5I and CBZ·[H O ] [BF ] ·H O) as well as the salt form CBZ·[CBZ(H)][BF ]·0.5H O. Reaction 2 4 3 2 5 2 0.25 4 0.25 2 4 2 of CBZ with a series of sulfonic acids also gave salt forms, namely, [CBZ(H)][O SC H ], [CBZ(H)][O SC H (OH)]· 3 6 5 3 6 4 0.5H O, [CBZ(H)] [O SCH CH SO ], and [CBZ(H)][O SC H (OH) (COOH)]·H O. CBZ and protonated CBZ(H) 2 2 3 2 2 3 3 6 3 2 moieties can be differentiated in the solid state both by changes to molecular geometry and by differing packing preference

    Structural study of salt forms of amides; paracetamol, benzamide and piperine

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    Single crystal x-ray diffraction has been used to investigate the structures of six complexes containing O-atom protonated cations derived from the pharmaceutically relevant amides benzamide (BEN), paracetamol (PAR) and piperine (PIP). The structures of the salt forms [PAR(H)][SO3C6H4Cl], [BEN(H)][O3SC6H4Cl] and [BEN(H)][Br].H2O are reported along with those of the hemi-halide salt forms [PAR(H)][I3].PAR , [PIP(H)][I3].PIP and [PIP(H)][I3]0.5[I]0.5.PIP. The structure of the cocrystal BEN.HOOCCH2Cl is also presented for comparison. The geometry of the amide group is found to systematically change upon protonation, with the C=O distance increasing and the C-N distance decreasing. The hemi-halide species all feature strongly hydrogen bonded amide(H)/amide pairs. The amide group C=O and C-N distances for both elements of each such pair are intermediate between those found for simple neutral amide and protonated amide forms. It was found that crystallising paracetamol from aqueous solutions containing Ba2+ ions gave orthorhombic paracetamol

    Loss of gastrokine-2 drives premalignant gastric inflammation and tumor progression

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    Chronic mucosal inflammation is associated with a greater risk of gastric cancer (GC) and, therefore, requires tight control by suppressive counter mechanisms. Gastrokine-2 (GKN2) belongs to a family of secreted proteins expressed within normal gastric mucosal cells. GKN2 expression is frequently lost during GC progression, suggesting an inhibitory role; however, a causal link remains unsubstantiated. Here, we developed Gkn2 knockout and transgenic overexpressing mice to investigate the functional impact of GKN2 loss in GC pathogenesis. In mouse models of GC, decreased GKN2 expression correlated with gastric pathology that paralleled human GC progression. At baseline, Gkn2 knockout mice exhibited defective gastric epithelial differentiation but not malignant progression. Conversely, Gkn2 knockout in the IL-11/STAT3-dependent gp130[superscript F/F] GC model caused tumorigenesis of the proximal stomach. Additionally, gastric immunopathology was accelerated in Helicobacter pylori–infected Gkn2 knockout mice and was associated with augmented T helper cell type 1 (Th1) but not Th17 immunity. Heightened Th1 responses in Gkn2 knockout mice were linked to deregulated mucosal innate immunity and impaired myeloid-derived suppressor cell activation. Finally, transgenic overexpression of human gastrokines (GKNs) attenuated gastric tumor growth in gp130[superscript F/F] mice. Together, these results reveal an antiinflammatory role for GKN2, provide in vivo evidence that links GKN2 loss to GC pathogenesis, and suggest GKN restoration as a strategy to restrain GC progression

    An absent presence: Separated child migrants’ caring practices and the fortified neoliberal state

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    This paper explores the ambivalent positioning of separated child migrants in the UK with a focus on the care that they provide for each other. Drawing on interview data with state and non-state adult stakeholders involved in the immigration-welfare nexus, we consider how children’s care practices are viewed and represented. We argue that separated children’s caring practices assume an absent presence in the discourses mobilised by these actors: either difficult to articulate or represented in negative and morally-laden terms, reflective of the UK’s 'hostile environment' towards migrants and advanced capitalist constructions of childhood. Such an examination sheds light on the complex state attempts to manage the care and migration regimes, and the way that care can serve as a way of making and marking inclusions and exclusions. Here we emphasise the political consequences for separated child migrants in an age of neoliberal state retrenchment from public provision of care and rising xenophobic nationalism

    Comparative genomics of drug resistance in <i>Trypanosoma brucei rhodesiense</i>

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    Trypanosoma brucei rhodesiense is one of the causative agents of human sleeping sickness, a fatal disease that is transmitted by tsetse flies and restricted to Sub-Saharan Africa. Here we investigate two independent lines of T. b. rhodesiense that have been selected with the drugs melarsoprol and pentamidine over the course of 2 years, until they exhibited stable cross-resistance to an unprecedented degree. We apply comparative genomics and transcriptomics to identify the underlying mutations. Only few mutations have become fixed during selection. Three genes were affected by mutations in both lines: the aminopurine transporter AT1, the aquaporin AQP2, and the RNA-binding protein UBP1. The melarsoprol-selected line carried a large deletion including the adenosine transporter gene AT1, whereas the pentamidine-selected line carried a heterozygous point mutation in AT1, G430R, which rendered the transporter non-functional. Both resistant lines had lost AQP2, and both lines carried the same point mutation, R131L, in the RNA-binding motif of UBP1. The finding that concomitant deletion of the known resistance genes AT1 and AQP2 in T. b. brucei failed to phenocopy the high levels of resistance of the T. b. rhodesiense mutants indicated a possible role of UBP1 in melarsoprol-pentamidine cross-resistance. However, homozygous in situ expression of UBP1-Leu(131) in T. b. brucei did not affect the sensitivity to melarsoprol or pentamidine

    On the relational dynamics of caring: a psychotherapeutic approach to emotional and power dimensions of women’s care work

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    Care is double-edged and paradoxical, inspiring a vast range of strong feelings in both care-givers and care-recipients. This paper draws on ideas about psychotherapeutic relationships to offer a theorisation of the complex emotional and power dynamics and imaginative geographies of care. Examining the humanistic approach developed by Carl Rogers as well as the psychoanalytic tradition, I advance an interpretation of psychotherapeutic practices that foregrounds the fundamental importance of the emotional and power-inflected relationship between practitioners and those with whom they work. I show how different traditions offer conceptualisations of the shape of therapeutic relationships that are highly relevant to consideration of the emotional and power dynamics of giving and receiving care. Against this background I discuss current debates about care, emotions and power, drawing especially on feminist and disability perspectives and arguing that psychotherapeutic approaches offer a powerful lens through which to understand the emotional and power dynamics of caring relationships. I conclude by emphasising how this theorisation helps to illuminate ubiquitous features of women’s care work
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