89,483 results

  • Improving regulatory frameworks for earthquake risk mitigation

    Egbelakin, T; Wilkinson, Suzanne; Potangaroa, R; Ingham, Jason (2013)

    Journal article
    The University of Auckland Library

    New Zealand's devastating Canterbury earthquakes provided an opportunity to examine the efficacy of existing regulations and policies relevant to seismic strengthening of vulnerable buildings. The mixed-methods approach adopted, comprising both qualitative and quantitative approaches, revealed that some of the provisions in these regulations pose as constraints to appropriate strengthening of earthquake-prone buildings. Those provisions include the current seismic design philosophy, lack of mandatory disclosure of seismic risks and ineffective timeframes for strengthening vulnerable buildings. Recommendations arising from these research findings and implications for pre-disaster mitigation for future earthquake and Canterbury's post-disaster reconstruction suggest: (1) a reappraisal of the requirements for earthquake engineering design and construction, (2) a review and realignment of all regulatory frameworks relevant to earthquake risk mitigation, and (3) the need to develop a national programme necessary to achieve consistent mitigation efforts across the country. These recommendations are important in order to present a robust framework where New Zealand communities such as Christchurch can gradually recover after a major earthquake disaster, while planning for pre-disaster mitigation against future earthquakes.

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  • The pathophysiology of Fuchs' endothelial dystrophy--a review of molecular and cellular insights

    Zhang, Jie; Patel, Dipika (2015-01)

    Journal article
    The University of Auckland Library

    Fuchs' endothelial corneal dystrophy (FECD) is the most common corneal endothelial dystrophy and commonly results in loss of vision. This review highlights the advances in our understanding of the pathophysiology of FECD through in??vivo confocal microscopy (IVCM) and in??vitro studies. All layers of the cornea may be affected by FECD, either primarily or secondary to corneal oedema. The primary changes include reduction of endothelial cell density and changes to endothelial morphology. Thickening of Descemet's membrane occurs, with addition of collagenous layers and formation of guttae. Changes secondary to corneal oedema include formation of epithelial bullae and sub-epithelial fibroblast and collagen infiltration, reduction of sub-basal corneal nerve density, and reduced anterior keratocyte density and fibroblastic transformation of stressed keratocytes in the stroma. Many of the microstructural changes occurring in FECD may be observed with IVCM, and these observations correlate well with histological studies. IVCM studies of early and mid-stage FECD are likely to provide further insight into the sequence of pathological processes that occur in this disease.

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  • Out-of-Plane Behavior of One-Way Spanning Unreinforced Masonry Walls

    Derakhshan, H; Griffith, MC; Ingham, Jason (2013-04)

    Journal article
    The University of Auckland Library

    An analytical model is developed to describe the out-of-plane response of one-way spanning unreinforced masonry (URM) walls by investigating the effects of various parameters. Horizontal crack height, masonry compressive strength, and diaphragm support stiffness properties are assumed as variables, and sensitivity analyses are performed to study the influence of these parameters on the cracked wall characteristic behavior. The parametric studies show that crack height significantly influences wall stability by affecting both the instability displacement and the wall lateral resistance. The reduction in cracked wall lateral resistance and in the instability displacement due to finite masonry compressive strength is shown to be significantly amplified by the applied overburden. A study using the typical configuration of flexible diaphragms and URM walls indicates that the wall top support flexibility does not significantly influence cracked wall out-of-plane response. An existing simplified wall behavioral model is improved, and a procedure is proposed for calculation of the wall out-of-plane response envelope.

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  • In-Plane Orthotropic Behavior of Timber Floor Diaphragms in Unreinforced Masonry Buildings

    Wilson, A; Quenneville, Pierre; Ingham, Jason (2014-01)

    Journal article
    The University of Auckland Library

    A full-scale experimental program consisting of testing four as-built diaphragms and four retrofitted diaphragms in both principal loading directions is presented. As-built configurations were typical of those found in historic unreinforced masonry buildings in North America and Australasia, whereas retrofitted diaphragms consisted of plywood panel overlays with stapled sheet metal blocking systems (SMBS). Test results were characterized using bilinear representations to establish recognizable performance parameters such as shear strength, shear stiffness, and ductility capacity, which were then used for comparative analysis. The nonlinear and low stiffness behavior of as-built diaphragms was confirmed in each principal loading direction. The plywood overlay and SMBS dramatically improved as-built diaphragm shear strength and shear stiffness and were shown to perform satisfactorily from a serviceability perspective. The orthotropic nature of as-built diaphragms was proven, with perpendicular-to-joist shear stiffness being as low as 68% of the corresponding orthogonal value. A typical duly framed stairwell penetration and discontinuous joists with two-bolt lapped connections were shown to have no detrimental impact on tested diaphragm performance. Predicted diaphragm performance using state-of-art assessment documents was shown to be inconsistent with corresponding values established from testing. It is recommended that these assessment procedures be updated with revised performance parameters and provisions to address diaphragm orthotropic behavior.

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  • Lateral Performance of Nail Connections from Century-Old Timber Floor Diaphragms

    Wilson, A; Quenneville, Pierre; Moon, FL; Ingham, Jason (2014-01)

    Journal article
    The University of Auckland Library

    Nail connections salvaged from the timber floor diaphragms of two ???100??????year ???100??????year old unreinforced masonry buildings were pseudostatically tested to determine their hysteretic behavior. The research objective was to establish expected load-slip characteristics of nail connections in historic timber diaphragms to facilitate improved seismic assessment accuracy. A summary of the testing procedure, test results, and performance characterization is presented. Nail connections constructed from Kauri (Agathis australis) timber and wire-drawn nails in the 1890s were found to have an average yield strength of 1.0 kN and an average maximum strength 1.4 kN. Nail connections constructed in 1914 from Rimu (Dacrydium cupressinum) timber and wire-drawn nails were found to have an average yield strength of 0.8 kN and an average maximum strength of 1.0 kN. Both connection types exhibited an average ultimate displacement capacity of approximately 11.4 mm.

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  • Complete reducibility of subgroups of reductive algebraic groups over nonperfect fields 2

    Uchiyama, Tomohiro (2016-03)

    Journal article
    The University of Auckland Library

    Let k be a separably closed field. Let G be a reductive algebraic k-group. In this paper, we study Serre's notion of complete reducibility of subgroups of G over k. In particular, using the recently proved center conjecture of Tits, we show that the centralizer of a k-subgroup H of G is G-completely reducible over k if it is reductive and H is G-completely reducible over k. We also show that a regular reductive k-subgroup of G is G-completely reducible over k. Various open problems concerning complete reducibility are discussed. We present examples where the number of overgroups of irreducible subgroups and the number of G(k)-conjugacy classes of unipotent elements are infinite. This paper complements the author's previous work on rationality problems for complete reducibility.

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  • Seismic Zonation and Default Suite of Ground-Motion Records for Time-History Analysis in the North Island of New Zealand

    Oyarzo-Vera, CA; McVerry, G; Ingham, Jason (2012-05)

    Journal article
    The University of Auckland Library

    A seismic zonation to be used in the selection of ground-motion records for time-history analysis of buildings in the North Island of New Zealand is presented. Both deaggregations of the probabilistic seismic hazard model and the seismological characteristics of the expected ground motions at different locations were considered in order to define the zonation. A profile of the records expected to apply within each zone according to the identified hazard scenarios is presented and suites of records are proposed for each zone, based on region-wide criteria, to be used in time-history analysis in the absence of site specific studies. A solution for structures with fundamental periods of between 0.4 and 2.0 seconds is proposed, considering a 500-year return period and two common site classes (C and D, according to the New Zealand Loadings Standard).

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  • Gender and family caregiving at the end-of-life in the context of old age: A systematic review

    Morgan, Tessa; Williams, Lisa; Trussardi, G; Gott, Caryl (2016-07)

    Journal article
    The University of Auckland Library

    Background: As societies age and governments attempt to manage within constrained health budgets by moving care into community settings, women will be called upon to provide more palliative care in old age. However, little is known about gendered disparities for caregivers of people over the age of 65???years. Aim: To identify and synthesise the empirical literature between 1994 and 2014 that focusses on gender and family caregiving for people over the age of 65???years with a life-limiting illness. Design: Systematic review of qualitative and quantitative studies conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Supplemental review using a novel feminist quality appraisal framework. Data sources: Search of MEDLINE, CINAHL, PsycINFO, Sociological Abstracts and Gender Studies to find empirical studies on gender and family caregiving at end-of-life in the context of old age. Results: Of 19 studies identified, 9 presented thorough gender analyses. Gender themes included why people care, how they care, and the consequences of providing care. Women caregivers experienced a greater degree of mental and physical strain than their male counterparts. This was linked to societal expectation that women should provide a greater degree of care at the end-of-life for family members. Conclusion: Palliative family caregiving for older adults is gendered. Gender affects why people care and the consequences of providing care. Palliative care literature needs to incorporate a greater gender focus for future research and policy makers need to be aware of the gendered ramifications of providing more palliative care in the community.

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  • Path Analysis Identifies Receptor Activator of Nuclear Factor-??B Ligand, Osteoprotegerin, and Sclerostin as Potential Mediators of the Tophus-bone Erosion Relationship in Gout

    Chhana, Ashika; Aati, O; Gamble, Gregory; Callon, Karen; Doyle, Anthony; Roger, M; McQueen, Fiona; Horne, Anne; Reid, Ian; Cornish, Jillian; Dalbeth, Nicola (2016-02)

    Journal article
    The University of Auckland Library

    Objective. To determine the relationship between tophus, erosion and bone remodeling factors in gout. Methods. Computed tomography bone erosion and circulating bone factors were measured in adults with tophaceous gout. Multiple regression modeling and path analysis were used to determine predictors of erosion. Results. Tophus number, M??ori or Pacific ethnicity, creatinine, receptor activator of nuclear factor-??B ligand (RANKL), osteoprotegerin (OPG), and sclerostin were independently associated with erosion. Path analysis showed a direct effect of tophus number on erosion, partially mediated through OPG, RANKL, and sclerostin. Conclusion. Tophus number is strongly associated with bone erosion in gout. Circulating RANKL, OPG, and sclerostin are potential mediators of tophus-related erosion.

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  • Effect of Antifreeze Peptide Pretreatment on Ice Crystal Size, Drip Loss, Texture, and Volatile Compounds of Frozen Carrots

    Kong, CHZ; Hamid, N; Liu, T; Sarojini Amma, Vijayalekshmi (2016)

    Journal article
    The University of Auckland Library

    Ice crystal formation is of primary concern to the frozen food industry. In this study, the effects of antifreeze peptides (AFPs) on ice crystal formation were assessed in carrot during freezing and thawing. Three synthetic analogues based on naturally occurring antifreeze peptides were used in this study. The AFPs exhibited modification of ice crystal morphology, confirming their antifreeze activity in vitro. The ability of the synthetic AFPs to minimize drip loss and preserve color, structure, texture, and volatiles of frozen carrot was evaluated using the techniques of SEM, GC-MS, and texture analysis. The results prove the potential of these AFPs to preserve the above characteristics in frozen carrot samples.

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  • Effect of Diversion Ileostomy on the Occurrence and Consequences of Chemotherapy-Induced Diarrhea

    Robertson, JP; Wells, CI; Vather, R; Bissett, Ian (2016-03)

    Journal article
    The University of Auckland Library

    BACKGROUND: The benefits of adjuvant chemotherapy in the treatment of colorectal cancer are well established. Chemotherapy-induced diarrhea is a common adverse effect of these regimens. The occurrence of chemotherapy-induced diarrhea not only directly affects patient health but may also compromise treatment efficacy because of consequent dosing alterations or discontinuation. OBJECTIVE: This study aimed to investigate the effect of diverting loop ileostomy during chemotherapy on the occurrence and consequences of chemotherapy-induced diarrhea. DESIGN: This was a retrospective evaluation of a prospective surgical database. SETTINGS: This was a single-institution retrospective study. PATIENTS: All patients receiving curative adjuvant chemotherapy after anterior resection for colorectal cancer at Auckland Hospital from 2002 to 2013 were retrospectively evaluated. MAIN OUTCOME MEASURES: Patient-, perioperative-, and chemotherapy-related variables were collected. Chemotherapy-induced diarrhea occurrence was graded according to National Cancer Institute Common Terminology Criteria for Adverse Events. Logistic regression analysis was performed to identify independent predictors for chemotherapy-induced diarrhea occurrence, treatment modifications, and hospital admission. RESULTS: A total of 109 identified patients received 691 chemotherapy cycles; 84% of patients with a diverting ileostomy experienced chemotherapy-induced diarrhea compared with 47% in those who were not defunctioned (p < 0.01). On logistic regression analysis, the presence of a diverting ileostomy during chemotherapy was an independent predictor of chemotherapy-induced diarrhea grade 3 or higher (OR, 13.6 (95% CI: 1.2???150.9); p = 0.02), the need for a dosing reduction (OR, 4.0 (95% CI: 1.3???12.4); p = 0.02), and the need for any modification in the chemotherapy regimen (OR, 3.4 (95% CI: 1.2???9.6); p = 0.02). LIMITATIONS: This study is limited by its retrospective design, potentially limiting the accuracy of chemotherapy-induced diarrhea grade reporting. CONCLUSIONS: The presence of an ileostomy during adjuvant chemotherapy is a predictor of severe chemotherapy-induced diarrhea and the need for modifications in the chemotherapy regimen. This may have important consequences for long-term survival. Prospective investigation is needed to further assess the impact of diverting ileostomy on the delivery of chemotherapy and oncologic outcomes.

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  • Remotely Delivered Exercise-Based Cardiac Rehabilitation: Design and Content Development of a Novel mHealth Platform

    Rawstorn, Jonathan; Gant, Nicholas; Meads, Andrew; Warren, Ian; Maddison, R (2016-06-24)

    Journal article
    The University of Auckland Library

    Background: Participation in traditional center-based cardiac rehabilitation exercise programs (exCR) is limited by accessibility barriers. Mobile health (mHealth) technologies can overcome these barriers while preserving critical attributes of center-based exCR monitoring and coaching, but these opportunities have not yet been capitalized on. Objective: We aimed to design and develop an evidence- and theory-based mHealth platform for remote delivery of exCR to any geographical location. Methods: An iterative process was used to design and develop an evidence- and theory-based mHealth platform (REMOTE-CR) that provides real-time remote exercise monitoring and coaching, behavior change education, and social support. Results: The REMOTE-CR platform comprises a commercially available smartphone and wearable sensor, custom smartphone and Web-based applications (apps), and a custom middleware. The platform allows exCR specialists to monitor patients??? exercise and provide individualized coaching in real-time, from almost any location, and provide behavior change education and social support. Intervention content incorporates Social Cognitive Theory, Self-determination Theory, and a taxonomy of behavior change techniques. Exercise components are based on guidelines for clinical exercise prescription. Conclusions: The REMOTE-CR platform extends the capabilities of previous telehealth exCR platforms and narrows the gap between existing center- and home-based exCR services. REMOTE-CR can complement center-based exCR by providing an alternative option for patients whose needs are not being met. Remotely monitored exCR may be more cost-effective than establishing additional center-based programs. The effectiveness and acceptability of REMOTE-CR are now being evaluated in a noninferiority randomized controlled trial.

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  • Cardiac activation heat remains inversely dependent on temperature over the range 27-37??C

    Johnston, CM; Han, June; Loiselle, Denis; Nielsen, Poul; Taberner, Andrew (2016-06-01)

    Journal article
    The University of Auckland Library

    The relation between heat output and stress production (force per cross-sectional area) of isolated cardiac tissue is a key metric that provides insight into muscle energetic performance. The heat intercept of the relation, termed "activation heat," reflects the metabolic cost of restoring transmembrane gradients of Na(+) and K(+) following electrical excitation, and myoplasmic Ca(2+) concentration following its release from the sarcoplasmic reticulum. At subphysiological temperatures, activation heat is inversely dependent on temperature. Thus one may presume that activation heat would decrease even further at body temperature. However, this assumption is prima facie inconsistent with a study, using intact hearts, which revealed no apparent change in the combination of activation and basal metabolism between 27 and 37??C. It is thus desired to directly determine the change in activation heat between 27 and 37??C. In this study, we use our recently constructed high-thermal resolution muscle calorimeter to determine the first heat-stress relation of isolated cardiac muscle at 37??C. We compare the relation at 37??C to that at 27??C to examine whether the inverse temperature dependence of activation heat, observed under hypothermic conditions, prevails at body temperature. Our results show that activation heat was reduced (from 3.5 ?? 0.3 to 2.3 ?? 0.3 kJ/m(3)) at the higher temperature. This leads us to conclude that activation metabolism continues to decline as temperature is increased from hypothermia to normothermia and allows us to comment on results obtained from the intact heart by previous investigators.

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  • Restoration of normal colonic motor patterns and meal responses after distal colorectal resection

    Vather, R; O'Grady, Gregory; Arkwright, JW; Rowbotham, DS; Cheng, Leo; Dinning, PG; Bissett, Ian (2016-03)

    Journal article
    The University of Auckland Library

    Background: Colorectal resections alter colonic motility, including disruption of control by neural or bioelectrical cell networks. The long-term impact of surgical resections and anastomoses on colonic motor patterns has, however, never been assessed accurately. Fibreoptic high-resolution colonic manometry was employed to define motility in patients who had undergone distal colorectal resection. Methods: Recruited patients had undergone distal colorectal resections more than 12???months previously, and had normal bowel function. Manometry was performed in the distal colon (36 sensors; 1-cm intervals), with 2-h recordings taken before and after a meal, with comparison to controls. Analysis quantified all propagating events and frequencies (cyclical, short single, and long single motor patterns), including across anastomoses. Results: Fifteen patients and 12 controls were recruited into the study. Coordinated propagating events directly traversed the healed anastomoses in nine of 12 patients with available data, including antegrade and retrograde cyclical, short single and long single patterns. Dominant frequencies in the distal colon were similar in patients and controls (2???3???cycles/min) (antegrade P???=???0??482; retrograde P???=???0??178). Compared with values before the meal, the mean(s.d.) number of dominant cyclical retrograde motor patterns increased in patients after the meal (2??1(2??7) versus 32??6(31??8) in 2???h respectively; P???<???0??001), similar to controls (P???=???0??178), although the extent of propagation was 41 per cent shorter in patients, by a mean of 3??4???cm (P???=???0??003). Short and long single propagating motor patterns were comparable between groups in terms of frequency, velocity, extent and amplitude. Conclusion: Motility patterns and meal responses are restored after distal colorectal resection in patients with normal bowel function. Coordinated propagation across healed anastomoses may indicate regeneration of underlying cellular networks.

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  • Heterozygous deletions at the ZEB1 locus verify haploinsufficiency as the mechanism of disease for posterior polymorphous corneal dystrophy type 3

    Liskova, P; Evans, CJ; Davidson, AE; Zaliova, M; Dudakova, L; Trkova, M; Stranecky, V; Carnt, N; Plagnol, V; Vincent, Andrea; Tuft, SJ; Hardcastle, AJ (2016-07)

    Journal article
    The University of Auckland Library

    A substantial proportion of patients with posterior polymorphous corneal dystrophy (PPCD) lack a molecular diagnosis. We evaluated 14 unrelated probands who had a clinical diagnosis of PPCD who were previously determined to be negative for mutations in ZEB1 by direct sequencing. A combination of techniques was used including whole-exome sequencing (WES), single-nucleotide polymorphism (SNP) array copy number variation (CNV) analysis, quantitative real-time PCR, and long-range PCR. Segregation of potentially pathogenic changes with disease was confirmed, where possible, in family members. A putative run of homozygosity on chromosome 10 was identified by WES in a three-generation PPCD family, suggestive of a heterozygous deletion. SNP array genotyping followed by long-range PCR and direct sequencing to define the breakpoints confirmed the presence of a large deletion that encompassed multiple genes, including ZEB1. Identification of a heterozygous deletion spanning ZEB1 prompted us to further investigate potential CNVs at this locus in the remaining probands, leading to detection of two additional heterozygous ZEB1 gene deletions. This study demonstrates that ZEB1 mutations account for a larger proportion of PPCD than previously estimated, and supports the hypothesis that haploinsufficiency of ZEB1 is the underlying molecular mechanism of disease for PPCD3.

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  • Reply to: Letter to the Editor: Re Srinivasa et??al., International Journal of Surgery 2014

    Srinivasa, Sanket; Taylor, MH; Hill, Andrew (2016-05)

    Journal article
    The University of Auckland Library

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  • Access to Surgical Care in Developing Countries

    Sammour, T; Hill, Andrew (2016-03)

    Journal article
    The University of Auckland Library

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  • Protection against glucocorticoid-induced damage in human tenocytes by modulation of ERK, Akt, and forkhead signaling

    Poulsen, Raewyn; Carr, AJ; Hulley, PA (2011-02)

    Journal article
    The University of Auckland Library

    Antiinflammatory glucocorticoid (GC) injections are extensively used to treat painful tendons. However, GC cause severe tissue wasting in other collagen-producing tissues such as skin and bone. The objective of this study was to determine the effects of GC on tenocytes and to explore strategies to protect against unwanted side effects of GC treatment. Cell survival, collagen production, and the induction of signaling pathways in primary human tenocytes treated with dexamethasone (Dex) were assessed. Antioxidant and growth factor approaches to protection were tested. Dex treatment resulted in reduced viable cell number, cell proliferation, and collagen production. Dex induced reactive oxygen species generation in tenocytes and strongly up-regulated the stress-response transcription factors FOXO1 and FOXO3A. Phosphorylation of ERK and protein kinase B/Akt, which regulate cell proliferation and also inhibit forkhead activity, was decreased. Chemical inhibition of ERK or Akt activity significantly reduced tenocyte cell number. Ameliorating the Dex-induced reduction in ERK or Akt activity by cotreatment with vitamin C or insulin protected against the Dex-induced reduction in cell number. Silencing FOXO1 prevented the Dex-induced reduction in collagen 1??1 expression. Cotreatment with vitamin C or insulin protected against the Dex-induced increase in FOXO and the Dex-induced inhibition of collagen 1??1 expression. Reduced ERK and Akt activation and increased forkhead signaling contribute to the negative effects of GC on tenocytes. Cotreatment therapies that target these signaling pathways are protective. Vitamin C in particular may be a clinically useable co-therapy to reduce connective tissue side effects associated with GC therapy.

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  • Ileal and faecal digestibility of daidzein and genistein and plasma bioavailability of these isoflavones and their bioactive metabolites in the ovariectomised rat

    Poulsen, Raewyn; Loots, DT; Moughan, PJ; Kruger, MC (2009-05)

    Journal article
    The University of Auckland Library

    Consumption of the soya isoflavones genistein and daidzein may provide protection against postmenopausal bone loss. The purpose of this study was to determine ileal and faecal digestibility of daidzein and genistein and the extent of formation of metabolites in the gastrointestinal (GI) tract in the ovariectomised rat, a model for postmenopausal bone loss. Twenty female rats were ovariectomised and fed either genistein or daidzein (0.026% of diet) for 4 wks. Genistein, daidzein and their GI-derived metabolites were quantitatively determined in plasma, urine, faeces and ileal digesta using GC/MS. Ileal and faecal digestibility of genistein (93 and 99.9%, respectively) were significantly greater than that of daidzein (32 and 77.5%, respectively). In genistein-supplemented animals, 4-ethylphenol was present in plasma in relatively high concentrations. The bioactivity of 4-ethylphenol may contribute to the physiological effects attributed to genistein consumption. The daidzein metabolite equol, was present in relatively high amounts in ileal digesta indicating substantial biotransformation of daidzein occurred in the small intestine presumably as a result of the activity of the resident microbiota. Further studies are required to determine whether 4-ethylphenol is a major metabolite of genistein in humans and the extent of biotransformation of daidzein to equol in the small intestine in humans.

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  • Long chain polyunsaturated fatty acids alter membrane-bound RANK-L expression and osteoprotegerin secretion by MC3T3-E1 osteoblast-like cells

    Poulsen, Raewyn; Wolber, FM; Moughan, PJ; Kruger, MC (2008-02)

    Journal article
    The University of Auckland Library

    Inflammation triggers an increase in osteoclast (bone resorbing cell) number and activity. Osteoclastogenesis is largely controlled by a triad of proteins consisting of a receptor (RANK), a ligand (RANK-L) and a decoy receptor (osteoprotegerin, OPG). Whilst RANK is expressed by osteoclasts, RANK-L and OPG are expressed by osteoblasts. The long chain polyunsaturated fatty acid (LCPUFA) arachidonic acid (AA, 20:4n-6) and its metabolite prostaglandin E2 (PGE2), are pro-inflammatory and PGE2 is a potent stimulator of RANKL expression. Various LCPUFAs such as eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and gamma-linolenic acid (GLA, 18:3n-6) have anti-inflammatory activity. We aimed to determine if AA itself can stimulate RANKL expression and whether EPA, DHA and GLA inhibit RANKL expression in osteoblasts. MC3T3-E1/4 osteoblast-like cells were cultured under standard conditions with each of the LCPUFAs (5microg/ml) for 48h. Membrane-bound RANKL expression was measured by flow cytometry and OPG secretion measured by ELISA. In a second experiment, RANKL expression in MC3T3-E1/4 cells was stimulated by PGE2 treatment and the effect of EPA, DHA and GLA on membrane-bound RANKL expression and OPG secretion determined. The percentage of RANKL-positive cells was higher (p<0.05) in mean OPG secretion. The percentage of RANKL positive cells was significantly lower following co-treatment with PGE2 and either DHA or EPA compared to treatment with PGE2 alone. Mean OPG secretion remained lower than controls in cells treated with PGE2 regardless of co-treatment with EPA or DHA. Results from this study suggest COX products of GLA and AA induce membrane-bound RANKL expression in MC3T3-E1/4 cells. EPA and DHA have no effect on membrane-bound RANKL expression in cells cultured under standard conditions however both EPA and DHA inhibit the PGE2-induced increase in RANKL expression in MC3T3-E1/4 cells.

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