The structure of divalent and trivalent cation substituted β-tricalcium phosphate

Current methods of nuclear waste disposal are not suitable for the immobilisation of novel defence-based waste due to the high halogen content resulting from pyrochemical reprocessing. The objective of this thesis was to investigate β-tricalcium phosphate (β- TCP, Ca3(PO4)2) encapsulated in a sodium aluminoborophosphate glass (NABP) matrix as a potential host for this waste using a variety of structural probes. Samples were prepared to determine the structural changes in β-TCP as components of the simulated waste streams were substituted into the material. Zn, Mg, Al, and Ga incorporation was investigated. A combination of X-ray and neutron diffraction was used to determine the changes in long-range order as a function of Zn and Mg substitution up to 13% and 25% cation substitution respectively. Both Zn and Mg substitution caused a contraction of the unit cell up to complete substitution of the Ca(5) site, at which point the contraction ceased. Under further substitution on the Ca(4) site, the a lattice parameter continued to decrease, while the c lattice parameter increased, resulting in an unchanged unit cell volume. Evidence of tricalcium trimagnesium phosphate second phase was observed for the Mg-based compositions above Ca2:8Mg0:2(PO4)2, as has been previously documented, however single phase samples were observed for all Zn-based compositions, in contrast to previous studies. 31P NMR was used to confirm this Ca(5)-Ca(4) substitution model for the Zn-based β-TCP compositions by tightly constrained simulations as a function of composition. A combination of solid-state NMR techniques were used to identify the substitution mechanism of Al and Ga in β-TCP up to the composition Ca9M(PO4)7, where M is Al or Ga respectively. The 31P and 43Ca NMR spectra were simulated as with the divalent cations mentioned above to determine the origin of each resonance in the spectra. Subsequently, 27Al-f31Pg and 71Ga-f31Pg R3-HMQC experiments were performed to explicitly identify substitution on the Ca(5) site only. Studies were also performed to model the NABP:β-TCP interface formed as a result of the encapsulation process, for both pure β-TCP and Ga-substituted β-TCP. To simulate the range of compositions expected at this interface, calcium phosphate and NABP preparations were mixed in proportions from 10 wt:% to 80 wt:% (Ga-substituted) β- TCP. 31P NMR and Raman spectroscopy showed a progressive depolymerisation of the phosphorus network, consistent with the replacement of Al3+ and Na+ with Ca2+. The Al3+ was shown to exist primarily in a 4 coordinated state, showing a tendency to exist within the phosphorus network, whereas 11B NMR showed the B to move from a 4 coordinated site in NABP to a B-rich 3 coordinated environment. Differential thermal analysis showed an increase in the temperature of the two recrystallisation events as a function of both β-TCP and Ga-substituted β-TCP. Studies of the phases present after recrystallisation of the pure β-TCP-based samples showed calcium sodium phosphate and Na Al co-substituted β-TCP for the lower and higher crystallisation temperatures with β-TCP incorporation. For the Ga-containing samples, Na Al Ga co-substituted β-TCP was observed for both crystallisation temperatures. Critically, Ga was shown to displace Al in the β-TCP phase

Quality standards for managing children and adolescents with bronchiectasis: an international consensus

The global burden of bronchiectasis in children and adolescents is being recognised increasingly. However, marked inequity exists between, and within, settings and countries for resources and standards of care afforded to children and adolescents with bronchiectasis compared with those with other chronic lung diseases. The European Respiratory Society (ERS) clinical practice guideline for the management of bronchiectasis in children and adolescents was published recently. Here we present an international consensus of quality standards of care for children and adolescents with bronchiectasis based upon this guideline. The panel used a standardised approach that included a Delphi process with 201 respondents from the parents and patients’ survey, and 299 physicians (across 54 countries) who care for children and adolescents with bronchiectasis. The seven quality standards of care statements developed by the panel address the current absence of quality standards for clinical care related to paediatric bronchiectasis. These internationally derived, clinician-, parent-and patient-informed, consensus-based quality standards statements can be used by parents and patients to access and advocate for quality care for their children and themselves, respectively. They can also be used by healthcare professionals to advocate for their patients, and by health services as a monitoring tool, to help optimise health outcomes.</p

Antagonism of Tetherin Restriction of HIV-1 Release by Vpu Involves Binding and Sequestration of the Restriction Factor in a Perinuclear Compartment

The Vpu accessory protein promotes HIV-1 release by counteracting Tetherin/BST-2, an interferon-regulated restriction factor, which retains virions at the cell-surface. Recent reports proposed β-TrCP-dependent proteasomal and/or endo-lysosomal degradation of Tetherin as potential mechanisms by which Vpu could down-regulate Tetherin cell-surface expression and antagonize this restriction. In all of these studies, Tetherin degradation did not, however, entirely account for Vpu anti-Tetherin activity. Here, we show that Vpu can promote HIV-1 release without detectably affecting Tetherin steady-state levels or turnover, suggesting that Tetherin degradation may not be necessary and/or sufficient for Vpu anti-Tetherin activity. Even though Vpu did not enhance Tetherin internalization from the plasma membrane (PM), it did significantly slow-down the overall transport of the protein towards the cell-surface. Accordingly, Vpu expression caused a specific removal of cell-surface Tetherin and a re-localization of the residual pool of Tetherin in a perinuclear compartment that co-stained with the TGN marker TGN46 and Vpu itself. This re-localization of Tetherin was also observed with a Vpu mutant unable to recruit β-TrCP, suggesting that this activity is taking place independently from β-TrCP-mediated trafficking and/or degradation processes. We also show that Vpu co-immunoprecipitates with Tetherin and that this interaction involves the transmembrane domains of the two proteins. Importantly, this association was found to be critical for reducing cell-surface Tetherin expression, re-localizing the restriction factor in the TGN and promoting HIV-1 release. Overall, our results suggest that association of Vpu to Tetherin affects the outward trafficking and/or recycling of the restriction factor from the TGN and as a result promotes its sequestration away from the PM where productive HIV-1 assembly takes place. This mechanism of antagonism that results in TGN trapping is likely to be augmented by β-TrCP-dependent degradation, underlining the need for complementary and perhaps synergistic strategies to effectively counteract the powerful restrictive effects of human Tetherin

Cation substitution in β-tricalcium phosphate investigated using multi-nuclear, solid-state NMR

The substitution of aluminium, gallium and sodium cations into β-tricalcium phosphate (β-TCP; Ca3(PO4)2) has been investigated, and the Ca sites involved successfully determined, using a combination of 1D 31P, 27Al, 71Ga, 23Na and 43Ca (natural abundance) NMR and 2D 27Al{31P}, 71Ga{31P} and 23Na{31P} rotary-resonance-recoupled heteronuclear multiple-quantum correlation (R3-HMQC) NMR. Over the compositional range studied, substitution of Ca2+ by Al3+ or Ga3+ was observed only on the Ca(5) site, whilst substitution by Na+ was confined to the Ca(4) site. Some AlPO4 or GaPO4 second phase was observed at the highest doping levels in the Al3+ and Ga3+ substituted samples

Comparative clinical effectiveness of prophylactic voriconazole/posaconazole to fluconazole/itraconazole in patients with acute myeloid leukemia/myelodysplastic syndrome undergoing cytotoxic chemotherapy over a 12-year period

Post-induction aplasia for acute myeloid leukemia/myelodysplastic syndrome is a high-risk period for invasive fungal diseases. The effectiveness of fluconazole, itraconazole solution, voriconazole and posaconazole prophylaxis used consecutively from December 1998 to January 2010 in patients with acute myeloid leukemia/myelodysplastic syndrome undergoing remission-induction chemotherapy was retrospectively evaluated. A total of 216 consecutive patients received 573 prophylaxis courses. Breakthrough-invasive fungal disease incidence in fluconazole, itraconazole, voriconazole, posaconazole recipients was 25%, 16%, 14% and 3%, respectively. Voriconazole/posconazole versus fluconazole/itraconazole combined was associated with significant reductions in breakthrough-invasive fungal disease incidence (20% vs. 8%, P=0.011), premature discontinuations (46% vs. 22% P<0.001) and empiric antifungal treatment (31% vs. 8.5%, P<0.001). Microbiologically confirmed infections were molds. Posaconazole compared to other drugs was associated with fewer courses requiring computed-tomography (43% vs. 26%, P<0.001). Adoption of voriconazole/posaconazole has decreased invasive fungal disease incidence, empiric antifungal treatment and for posaconazole, computed-tomography demand, with effectiveness of posaconazole comparable to clinical trial experience

Loss of complement regulatory proteins on red blood cells in mild malarial anaemia and in Plasmodium falciparum induced blood-stage infection

BACKGROUND: Anaemia is a major consequence of malaria, caused by the removal of both infected and uninfected red blood cells (RBCs) from the circulation. Complement activation and reduced expression of complement regulatory proteins (CRPs) on RBCs are an important pathogenic mechanism in severe malarial anaemia in both Plasmodium falciparum and Plasmodium vivax infection. However, little is known about loss of CRPs on RBCs during mild malarial anaemia and in low-density infection. METHODS: The expression of CRP CR1, CD55, CD59, and the phagocytic regulator CD47, on uninfected normocytes and reticulocytes were assessed in individuals from two study populations: (1) P. falciparum and P. vivax-infected patients from a low transmission setting in Sabah, Malaysia; and, (2) malaria-naïve volunteers undergoing P. falciparum induced blood-stage malaria (IBSM). For clinical infections, individuals were categorized into anaemia severity categories based on haemoglobin levels. For IBSM, associations between CRPs and haemoglobin level were investigated. RESULTS: CRP expression on RBC was lower in Malaysian individuals with P. falciparum and P. vivax mild malarial anaemia compared to healthy controls. CRP expression was also reduced on RBCs from volunteers during IBSM. Reduction occurred on normocytes and reticulocytes. However, there was no significant association between reduced CRPs and haemoglobin during IBSM. CONCLUSIONS: Removal of CRPs occurs on both RBCs and reticulocytes during Plasmodium infection even in mild malarial anaemia and at low levels of parasitaemia