Time filter

Source Type

Safarchi A.,University of New South Wales | Octavia S.,University of New South Wales | Luu L.D.W.,University of New South Wales | Tay C.Y.,University of Western Australia | And 6 more authors.
Vaccine | Year: 2016

Molecular epidemiological data indicates that the resurgence of pertussis (whooping cough) in populations with high vaccine coverage is associated with genomic adaptation of Bordetella pertussis, the causative agent of the disease, to vaccine selection pressure. We have previously shown that in the period after the introduction of acellular pertussis vaccine (ACV), the majority of circulating strains in Australia switched to single nucleotide polymorphism (SNP) cluster I (carrying ptxP3/prn2), replacing SNP cluster II (carrying ptxP1/prn3). In this study, we carried out an in vivo competition assay using a mouse model infected with SNP cluster I and II B. pertussis strains from Australia. We found that the SNP cluster I strain colonised better than the SNP cluster II strain, in both naïve and immunised mice, suggesting that SNP cluster I strains had better fitness regardless of immunisation status of the host, consistent with SNP cluster I strains replacing SNP cluster II. Nevertheless, we found that ACV enhanced clearance of both SNP cluster I and II strains from the mouse respiratory tract. © 2016 Elsevier Ltd Source

Afroughsabet V.,Polytechnic of Milan | Ozbakkaloglu T.,University of AdelaideSouth Australia
Construction and Building Materials | Year: 2015

This study investigates the effect of the addition of steel and polypropylene fibers on the mechanical and some durability properties of high-strength concrete (HSC). Hooked-end steel fibers with a 60-mm length were used at four different fiber volume fractions of 0.25%, 0.50%, 0.75%, and 1.0%. Polypropylene fibers with a 12-mm length were used at the content of 0.15%, 0.30%, and 0.45%. Some mixtures were produced with the combination of steel and polypropylene fibers at a total fiber volume fraction of 1.0% by volume of concrete, in order to study the effect of fiber hybridization. All the fiber-reinforced concretes contained 10% silica fume as a cement replacement. The compressive strength, splitting tensile strength, flexural strength, electrical resistivity, and water absorption of the concrete mixes were examined. Results of the experimental study indicate that addition of silica fume improves both mechanical and durability properties of plain concrete. The results also indicate that incorporation of steel and polypropylene fibers improved the mechanical properties of HSC at each volume fraction considered in this study. Furthermore, it was observed that the addition of 1% steel fiber significantly enhanced the splitting tensile strength and flexural strength of concrete. Among different combinations of steel and polypropylene fibers investigated, the best performance was attained by a mixture that contained 0.85% steel and 0.15% polypropylene fiber. Finally, the results show that introducing fibers to concrete resulted in a decrease in water absorption and, depending on the type of fibers, significant or slight reduction in the electrical resistivity of concrete compared to those of the companion plain concrete. ©2015 Elsevier Ltd. All rights reserved. Source

Hodyl N.A.,University of AdelaideSouth Australia | Crawford T.M.,University of AdelaideSouth Australia | McKerracher L.,Womens and Childrens Hospital | Lawrence A.,SA Pathology | And 2 more authors.
Early Human Development | Year: 2016

Background Neurotrophins are proteins critically involved in neural growth, survival and differentiation, and therefore important for fetal brain development. Reduced cord blood neurotrophins have been observed in very preterm infants (< 32 weeks gestation) who subsequently develop brain injury. Antenatal steroid exposure can alter neurotrophin concentrations, yet studies to date have not examined whether this occurs in the late preterm infant (33–36 weeks gestation), despite increasing recognition of subtle neurodevelopmental deficits in this population. Aim To assess the impact of antenatal steroids on cord blood neurotrophins in late preterm infants following antenatal steroid exposure. Study design Retrospective analysis. Subjects Late preterm infants (33–36 weeks; n = 119) and term infants (37–41 weeks; n = 129) born at the Women's and Children's Hospital, Adelaide. Outcome measures Cord blood neurotrophin-3 (NT-3), NT-4, nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) concentrations measured by ELISA. Results Cord blood NT-4 and NGF were increased at term compared to the late preterm period (p < 0.001), while BDNF and NT-3 were not different. In the late preterm period, cord blood NT-3 was reduced when antenatal steroids were administered > 24 h prior to delivery (p < 0.01). Conclusion This study identified an association between reduced cord blood NT-3 and antenatal steroid exposure in the late preterm period. The reduced NT-3 may be a consequence of steroids inducing neuronal apoptosis, thereby reducing endogenous neuronal NT3 production, or be an action of steroids on other maternal or fetal NT-3 producing cells, which may then affect neuronal growth, differentiation and survival. Regardless of the specific mechanism, a reduction in NT-3 may have long term implications for child neurodevelopment, and emphasizes the ongoing vulnerability of the fetal brain across the full preterm period. © 2016 Elsevier Ireland Ltd Source

Liu Y.,University of AdelaideSouth Australia | Wang T.,University of The Sunshine Coast | Calabrese A.N.,University of AdelaideSouth Australia | Carver J.A.,Australian National University | And 2 more authors.
Peptides | Year: 2015

The amphibian host-defense peptide caerin 1.8 [1GLFKVLGSV10AKHLLPHVVP20VIAEKL(NH2)] inhibits fibril formation of amyloid β 1-42 [1DAEFRHDSG10YEVHHQKLVF20FAEDVGSNKG30AIIGLMVGGV40VIA] [Aβ42] (the major precursor of the extracellular fibrillar deposits of Alzheimer's disease). Some truncated forms of caerin 1.8 also inhibit fibril formation of Aβ42. For example, caerin 1.8 (1-13) [1GLFKVLGSV10AKHL(NH2) and caerin 1.8 (22-25) [KVLGSV10AKHLLPHVVP20VIAEKL(NH2)] show 85% and 75% respectively of the inhibition activity of the parent caerin 1.8. The synthetic peptide KLVFFKKKKKK is a known inhibitor of Aβ42 fibril formation, and was used as a standard in this study. Caerin 1.8 is the more effective fibril inhibitor. IC50 values (±15%) are caerin 1.8 (75 μM) and KLVFFKKKKKK (370 μM). MALDI mass spectrometry shows the presence of a small peak corresponding to a protonated 1:1 adduct [caerin 1.8/Aβ42]H+. Molecular dynamics simulation suggests that both hydrogen bonding and hydrophobic interactions between Aβ42 and caerin 1.8 facilitate the formation of a 1:1 complex in water. Fibril formation from Aβ42 has been proposed to be based around the 16KLVF20F region of Aβ42; this region in the 1:1 complex is partially blocked from attachment of a further molecule of Aβ42. © 2015 Published by Elsevier Inc. Source

He X.-F.,China University of Geosciences | He X.-F.,University of AdelaideSouth Australia | Santosh M.,China University of Geosciences | Santosh M.,University of AdelaideSouth Australia | And 5 more authors.
Lithos | Year: 2016

Among the various Precambrian crustal blocks in the North China Craton (NCC), the geology and evolution of the Ordos Block remain largely enigmatic due to paucity of outcrop. Here we investigate granulite-facies metapelites obtained from deep-penetrating drill holes in the Ordos Block and report petrology, calculated phase equilibria and in-situ monazite LA-ICP-MS geochronology. The rocks we studied are two samples of cordierite-bearing garnet–sillimanite–biotite metapelitic gneisses and one graphite-bearing, two-mica granitic gneiss. The peak metamorphic age from LA-ICP-MS dating of monazite in all three samples is in the range of 1930–1940 Ma. The (U + Pb)–Th chemical ages through EPMA dating reveals that monazite occurring as inclusions in garnet are older than those in the matrix. Calculated metamorphic phase diagrams for the cordierite-bearing metapelite suggest peak P–T conditions ca. 7–9 kbar and 775–825 °C, followed by decompression and evolution along a clockwise P–T path. Our petrologic and age data are consistent with those reported from the Khondalite Belt in the Inner Mongolia Suture Zone in the northern part of the Ordos Block, suggesting that these granulite-facies metasediments represent the largest Paleoproterozoic accretionary belt in the NCC. © 2016 Elsevier B.V. Source

Discover hidden collaborations