90,065 results

  • Adaptations of glutathione antioxidant system to endurance training are tissue and muscle fiber specific

    Leichtweis, Steven (1997)

    Journal article
    The University of Auckland Library

    The effect of endurance training on glutathione (GSH) status and antioxidant enzyme system was investigated in skeletal muscle, heart, and liver of female Sprague-Dawley rats pair fed an isocaloric diet. Ten weeks of treadmill training (25 m/min, 10% grade for 2 h/day, 5 days/wk) increased citrate synthase activity in the deep vastus lateralis (DVL) and soleus muscles by 79 and 39%, respectively (P < 0.01), but not in the heart or liver. In DVL, GSH content was increased 33% (P < 0.05) with training, accompanied by a 64% (P < 0.05) increase in glutamate content but no change in cysteine. Trained rats showed a 62 and 27% higher GSH peroxidase (GPX) and superoxide dismutase (SOD) activity, respectively (P < 0.05), in DVL compared with control rats. In contrast, GSH content and glutathione reductase (GR) activity in soleus declined with training (P < 0.05), whereas activities of GPX and SOD remained unchanged. Training did not alter GSH status in the liver or plasma but significantly decreased the GSH-to glutathione disulfide ratio in the heart. In addition, GR activity in the liver and GSH sulfur-transferase activity in the heart and DVL were significantly lower in the trained vs control rats DVL muscle had threefold higher gamma-glutamyl transpeptidase activity compared with other tissues; however no significant alteration was observed in the activity of gamma-glutamyltranspeptidase or gamma-glutamylcysteine synthetase in the liver, heart, or skeletal muscle. These data indicate that endurance training can cause tissue- and muscle fiber-specific adaptation of antioxidant systems and that GSH homeostasis in extrahepatic tissues may be determined by utilization and uptake of GSH via the gamma-glutamyl cycle.

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  • Quantifying the Effects of Chip Seal Volumetrics on the Occurrence of Pavement Flushing

    Kodippily, Sachi; Henning, Theunis; Ingham, Jason; Holleran, G (2014)

    Journal article
    The University of Auckland Library

    The reported study was undertaken to investigate the micromechanical interactions that occur between sprayed seal (chip seal) layer materials in order to examine their relationship to the initiation of flushing. In particular, the deformation patterns of chip seal pavement samples with respect to lateral cyclic loading as well as the changes that occur to the distribution of air voids within a chip seal layer during loading were investigated. The effect of binder volume and air void volume on the development of flushing of the chip seal samples was also investigated. The reported study was based on laboratory testing of chip seal pavement samples (cores) that were obtained from in-service, flushed pavements in New Zealand. The cores, of 200-mm diameter and thicknesses ranging from 32.4 to 55.5 mm, were subjected to varying levels of lateral cyclic loading using a wheel tracking machine and the deformation that had occurred on the surface of the cores was measured. The cores were then scanned using a computed tomography (CT) scanner to examine changes that had occurred to the air void volume of the cores during the wheel tracking test, and the reductions in air void volume were compared with the quantity of flushing that was displayed on the cores. The cores were tested to determine the binder volumes in order to investigate how flushing development was affected by the ratio of binder volume and air void volume. The results from the analyses demonstrated that a strong correlation existed between flushing and air void volume reduction, where a larger reduction in air void volume directly corresponded to a higher amount of flushing. The deformation pattern of the cores indicated the likely state of stability of the chip seal structure, and the state of stability in turn indicated the best method of maintenance that was required for a flushed surface. The study findings demonstrated that the combination of wheel tracking and CT scanning is an extremely effective analysis method that can be used to determine the state of stability of a chip seal and to select the best maintenance treatment for pavement flushing.

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  • How long is too long for cerebral cooling after ischemia in fetal sheep?

    Davidson, Joanne; Wassink, Guido; Yuill, Caroline; Zhang, FG; Bennet, Laura; Gunn, Alistair (2015)

    Journal article
    The University of Auckland Library

    Therapeutic hypothermia can partially reduce long-term death and disability in neonates after hypoxic-ischemic encephalopathy. The aim of this study was to determine whether prolonging the duration of cooling from 3 days to 5 days could further improve outcomes of cerebral ischemia in near-term fetal sheep. Fetal sheep (0.85 gestation) received 30 minutes bilateral carotid artery occlusion followed by 3 days of normothermia (n=8), 3 days of hypothermia (n=8), or 5 days of hypothermia (n=8) started 3 hours after ischemia. Sham controls received sham ischemia followed by normothermia (n=8). Cerebral ischemia was associated with profound loss of electroencephalography power and spectral edge, with greater and more rapid recovery in both hypothermia groups (P<0.05). Extending the duration of delayed therapeutic hypothermia from 3 to 5 days did not improve outcomes after severe ischemia, and was associated with reduced neuronal survival in some regions.

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  • Structural basis for oxygen degradation domain selectivity of the HIF prolyl hydroxylases

    Chowdhury, R; Leung, Ka Ho Ivanhoe; Tian, Y-M; Abboud, MI; Ge, W; Domene, C; Cantrelle, F-X; Landrieu, I; Hardy, AP; Pugh, CW; Ratcliffe, PJ; Claridge, TDW; Schofield, CJ (2016-08-26)

    Journal article
    The University of Auckland Library

    The response to hypoxia in animals involves the expression of multiple genes regulated by the ????-hypoxia-inducible transcription factors (HIFs). The hypoxia-sensing mechanism involves oxygen limited hydroxylation of prolyl residues in the N- and C-terminal oxygen-dependent degradation domains (NODD and CODD) of HIF?? isoforms, as catalysed by prolyl hydroxylases (PHD 1???3). Prolyl hydroxylation promotes binding of HIF?? to the von Hippel???Lindau protein (VHL)???elongin B/C complex, thus signalling for proteosomal degradation of HIF??. We reveal that certain PHD2 variants linked to familial erythrocytosis and cancer are highly selective for CODD or NODD. Crystalline and solution state studies coupled to kinetic and cellular analyses reveal how wild-type and variant PHDs achieve ODD selectivity via different dynamic interactions involving loop and C-terminal regions. The results inform on how HIF target gene selectivity is achieved and will be of use in developing selective PHD inhibitors.

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  • Cultural invariance of goal orientation and self-efficacy in New Zealand: Relations with achievement

    Meissel, Kane; Davies, Christine (2016-03)

    Journal article
    The University of Auckland Library

    There is substantial evidence indicating that various psychological processes are affected by cultural context, but such research is comparatively nascent within New Zealand. As there are four large cultural groups in New Zealand, representing an intersection of individualist, collectivist, indigenous, colonial, and immigrant cultures, New Zealand is an important context in which to investigate the role of culture in such processes.This study investigated goal orientation and self-efficacy beliefs among students of different cultural backgrounds in New Zealand, associations between motivational beliefs and achievement, and whether any relations differed by cultural background.Participants were 2,210 students attending three intermediate schools.Participants responded to a questionnaire at the beginning of the school year to evaluate self-efficacy for mathematics and mastery and performance goal orientation. Participants also completed a standardized mathematics achievement test at the beginning and end of the year.The factor structure was sufficiently invariant by cultural group, but with statistically significant differences in average level of endorsement. Self-efficacy for mathematics predicted marginally higher end-of-year achievement after controlling for beginning-of-year achievement, with a stronger relationship for M??ori and Pasifika, but no statistically significant relationship with achievement among Asian students.The questionnaire used was a valid instrument for the four main cultural groups in New Zealand. Differences were found in motivation levels, and M??ori and Pasifika were more affected by their self-reported self-efficacy. Teachers may be able to raise students' self-beliefs by conveying high expectations for these students, potentially supporting higher academic outcomes.

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  • Amylin and severe acute pancreatitis

    Phillips, Anthony; Abu-Zidan, Fikri; Bonham, Martin; Cooper, Garth; Windsor, John (2000-01)

    Journal article
    The University of Auckland Library

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  • Administration of low-dose aspirin to mothers with small for gestational age fetuses and abnormal umbilical Doppler studies to increase birthweight: a randomised double-blind controlled trial

    McCowan, Lesley; Harding, Jane; Roberts, AB; Barker, SL; Ford, C; Stewart, Alistair (1999)

    Journal article
    The University of Auckland Library

    Objective To determine whether antenatal treatment (for greater than or equal to 14 days) with 100 mg aspirin daily, given to mothers with small for gestational age fetuses and abnormal umbilical Doppler, will increase birthweight. Design Randomised,

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  • Narlostructured biointerfaces

    Agheli, H; Malmstrom Pendred, Jenny; Hanarp, P; Sutherland, DS (2006)

    Journal article
    The University of Auckland Library

    Colloidal lithography is used to create nanostructured interfaces suitable for studying and interacting with cellular biosystems. Large areas of patterned surface can be produced. We investigate the use of plasma etching for transfer of the pattern of individual colloidal particles into the substrates to create short-range ordered arrays of topographic and/or chemical nanostructures. Colloidal masks perform differently to traditional photoresist masks and local redeposition of material around the particle has significant impact on the resultant structures. The colloidal particles can be reshaped to allow the fabrication of flat-topped structures. Topographic and chemical nanostructures can be used to template the self assembly of macromolecules. The phase separation of thin films of PS-PMMA symmetric block copolymers above nanostructure sites is aligned at the surface nanostructure by topographic features. PLL-PEG assembly at alkanethiol-modified nanoscale chemical patterns of gold/silicon allows the production of nanoscale protein patterns. Patterns of ferritin 100 nm in diameter are demonstrated. (c) 2005 Published by Elsevier B.V.

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  • Multiscale modeling in computational biomechanics

    Tawhai, Merryn; Bischoff, Jeffrey; Einstein, D; Erdemir, A; Guess, T; Reinbolt, J (2009)

    Journal article
    The University of Auckland Library

    Biomechanics is broadly defined as the scientific discipline that investigates the effects of forces acting on and within biological structures. The realm of biomechanics includes the circulatory and respiratory systems, tissue mechanics and mechanotransduction, and the musculoskeletal system and motor control. As in many other biological phenomena, many spatial scales are crossed by biomechanics research: intracellular, multicellular, and extracellular matrices; and tissue, organ, and multiorgan systems. It is well established that the effect of forces at higher scales influence behavior at lower scales and that lower-scale properties influence higher-scale response. However, computational methods that incorporate these interactions in biomechanics are relatively rare. In general, computational models that include representation of multiple spatial or temporal scales are loosely defined as multiscale. The fact that multiscale modeling is not well defined lends the term to a variety of scenarios within the computational physiology community. In biomechanics, multiscale modeling may mean establishing a hierarchical link between the spatial and temporal scales, while the output of a larger-scale system is passed through a finely detailed representation at a lower scale (e.g., body-level movement simulations that provide net joint loading for tissue-level stress analysis). In reality, multiscale modeling may require more intricate representation of interactions among scales. A concurrent simulation strategy is inevitable to adequately represent nonlinear associations that have been known for decades [1].

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  • Virtual Environments and the Acceleration of Experiential Learning

    Wild, Christopher (2007)

    Journal article
    The University of Auckland Library

    Summary Darius et al. (2007) and Nolan & Temple Lang (2007) give examples of virtual environments that can, for specific purposes, substitute for the real world. We are in the early stages of developments that could revolutionize statistics education by making it possible to capture efficiently important aspects of the thinking and practice of professional statisticians previously learned only from long years of experience. The ability of virtual environments to automate processes provides a potent weapon for tackling the tyranny that Time exercises over such modes of learning. We discuss the many new possibilities that are opened up by virtual environments together with cognitive and pedagogical imperatives to be addressed to ensure that environments actually do teach the lessons they were designed to teach. We echo Nolan and Temple Lang's call for the development of environments to be modular and open source. Taking the R-project as a model, this can lead to a growing repository of building blocks that make the construction of future environments less costly, thus facilitating the realization of more and more ambitious conceptions.

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  • Reaction of bromonaphthofurans with bis(pinacolato)diboron

    Brimble, Margaret; Issa, F (1999)

    Journal article
    The University of Auckland Library

    The synthesis of a dimeric pyranonaphthoquinone (8) was investigated focusing on a late-stage biaryl coupling of suitably functionalized bromonaphthofurans by using Suzuki-Miyaura methodology. Bromonaphthofuran (16) underwent reaction with bis(pinaco

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  • Reactions of semiquinones in aqueous solution. A comparison of the one electron reduction of kalafungin and analogues with other semiquinones using pulse radiolysis

    Anderson, Robert; Brimble, Margaret; Nairn, MR; Packer, JE (1999)

    Journal article
    The University of Auckland Library

    The radical anions of the pyranonaphthoquinone antibiotic kalafungin 1 and analogues have been studied in aqueous solution by pulse radiolysis using transient absorption spectrophotometry. Radical absorption spectra were similar regardless of the nat

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  • Synthesis and neuroprotective activity of analogues of glycyl-L-prolyl-L-glutamic acid (GPE) modified at the alpha-carboxylic acid

    Trotter, Nicholas; Brimble, MA; Harris, Paul; Callis, DJ; Sieg, Frank (2005)

    Journal article
    The University of Auckland Library

    The synthesis of nine GPE* analogues, wherein the alpha-carboxylic acid group of glutamic acid has been modified, is described by coupling readily accessible N-benzyloxycarbonyl-glycyl-L-proline 2 with various analogues of glutamic acid. Pharmacologi

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  • Synthesis and pharmacological evaluation of side chain modified glutamic acid analogues of the neuroprotective agent glycyl-L-prolyl-L-glutamic acid (GPE)

    Brimble, MA; Trotter, Nicholas; Harris, Paul; Sieg, Frank (2005)

    Journal article
    The University of Auckland Library

    The synthesis of eight GPE* analogues, wherein the gamma-carboxylic moiety of the glutamic residue has been modified, is described by coupling readily accessible N-benzyloxycarbonyl-glycyl-L-proline with various analogues of glutamic acid. Pharmacolo

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  • Synthesis of Aromatic Spiroacetals Related to gamma-Rubromycin Based on a 3H-Spiro[1-benzofuran-2,2 chromane] Skeleton

    Tsang, Kit; Brimble, Margaret (2007)

    Journal article
    The University of Auckland Library

    The synthesis of a series of aromatic 5,6-benzannelated and naphthyl-benzannelated spiroacetals related to the spiroacetal unit present in the quinonoid antibiotic ??-rubromycin is reported. The key steps include the use of Sonogashira coupling to construct an aryl acetylene that is coupled to an aryl aldehyde forming a propargyl alcohol intermediate. Hydrogenation of the resultant alkynol followed by oxidation produces a masked dihydroxyketone that upon treatment with silica-supported sodium hydrogen sulfate undergoes concomitant deprotection and cyclisation to afford the desired fused aromatic spiroacetal.

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  • Synthesis of N-(3-Phenylpropyl)-Substituted Tricyclic ABE Ring Analogues of the Alkaloid Methyllycaconitine

    Lehmann, Anna; Brocke, C; Barker, David; Brimble, Margaret (2006)

    Journal article
    The University of Auckland Library

    The synthesis of several ABE tricyclic analogues 5, 31 and 32 of the alkaloid methyllycaconitine (1) is reported. The analogues contain two key pharmacophores: a tertiary N-(3-phenylpropyl) substituent attached to a 3-azabicyclo[3.3.1]nonane ring system and a 2-(3-methyl-2,5-dioxopyrrolidin-1-yl)benzoate ester. Double Mannich reaction of the cyclic ??-keto esters 6 and 17 with the bis(aminol) ether 7 using methyltrichlorosilane as an activating agent provided an efficient method for the construction of the 3-azabicyclo[3.3.1]nonanes 8 and 18. Ring-closing metathesis of the derived dienes 11, 19, and 20 afforded the tricyclic ethers 12, 21, and 22, respectively, the C-8 ester of which was reduced to a hydroxymethyl group to form the ABE tricyclic analogues 13, 23, and 24. Conversion of the alcohol 13 to the anthranilate ester 14 using N-(trifluoroacetyl)anthranilic acid followed by fusion with methylsuccinic anhydride afforded the analogue 5 containing the key N-(methylsuccinimido)anthranilate pharmacophore. In the case of the alcohols 23 and 24 the 2-(3-methyl-2,5-dioxopyrrolidin-1-yl)benzoate ester pharmacophore was appended by direct esterification with unsaturated acid 28 followed by hydrogenation to the ABE tricyclic compounds 33 and 34.

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  • Synthesis of regioisomeric analogues of crisamicin A

    Brimble, MA; Lai, MYH (2003)

    Journal article
    The University of Auckland Library

    The synthesis of bis-furonaphthopyrans 12a and 12b, regioisomeric analogues of the dimeric pyranonaphthoquinone antibiotic crisamicin A 1 is described. The key intermediate 16 was prepared via a one-pot in situ Suzuki-Miyaura homocoupling of naphthyl

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  • Synthesis of the 1,6,8-trioxadispiro[4.1.5.2]tetradec-11-ene ring system present in the spirolide family of shellfish toxins and its conversion into a 1,6,8-trioxadispiro[4.1.5.2]-tetradec-9-en-12-ol via base-induced rearrangement of an epoxide

    Brimble, MA; Furkert, Daniel (2004)

    Journal article
    The University of Auckland Library

    The synthesis of the 1, 6,8-trioxadispiro [4.1.5.2]tetradec-11-enes 12 present in the shellfish toxins spirolides B 1 and D 2, is reported. The two spirocentres were constructed via iterative radical oxidative cyclization of hydroxyalkyl dihydropyran

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  • Synthesis of the spiroacetal fragment of broussonetine H

    Brimble, MA; Park, Jae; Taylor, Carol (2003)

    Journal article
    The University of Auckland Library

    (2S,6S)-2-(3-Bromopropyl)-1,7-dioxaspiro[5.5]undecane 3 was prepared by the addition of the acetylide derived from (4S)-4-benzyloxy-7-tert-butyldiphenylsilyloxyhep-1-yne 8 to delta-valerolactone 6 followed by treatment with hydrogen and palladium on

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  • Synthetic strategies towards pyranonaphthoquinone antibiotics

    Brimble, MA; Nairn, MR; Prabaharan, H (2000)

    Journal article
    The University of Auckland Library

    The class of compounds known as the pyranonaphthoquinone antibiotics are isolated from various strains of bacteria and fungi, the majority being microbial in origin.1 The basic skeleton of these antibiotics is the naphtho[2,3-c]pyran-5,10-dione ring system (Fig. 1), with some members of the family containing an additional ??-lactone ring fused to the dihydropyran moiety as the basic subunit. This substituted benzoisochromane skeleton represents a biosynthetic product common to all members of this class and is built up from acetate/malonate units via a polyketide pathway

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