Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item The eggshell structure in apteryx; form, function, and adaptation(John Wiley and Sons, Ltd, 2021-04) Vieco-Galvez D; Castro I; Morel PCH; Chua WH; Loh MApteryx is a genus of flightless birds endemic to New Zealand known to lay very large eggs in proportion to body weight. The eggshell of Apteryx is unusually thin and less porous than allometrically expected possibly as a compensation for a very long incubation period. Past studies have been carried out on Apteryx australis, a species which once comprised all kiwi with brown plumage, now separated into three distinct species. These species use different habitats and live at different latitudes and altitudes, therefore generating a need to revise our knowledge of the attributes of their eggshells. In this study, we measured the physical characteristics and water conductance on eggshell fragments of these three species and Great-spotted Kiwi and relate them to the environmental conditions of their respective environments; we also measured the water vapor conductance of Brown Kiwi eggs of late stages of incubation. We found that several trade-offs exist between incubation behavior, environmental conditions, and eggshell structure. We found differences between species in eggshell water vapor conductance seemingly related to altitude; Brown Kiwi and Rowi generally inhabiting lower altitudes had the highest conductance and Tokoeka, generally living in montane environments, the lowest. This is achieved by an increased eggshell thickness rather than a pore area reduction. Finally, the water vapor conductance late in incubation was 58% higher than infertile unincubated eggs, suggesting a drastic increase in conductance throughout the long incubation period. Using the values previously reported, we calculated the embryonic eggshell thinning to be 32.5% at the equatorial region of the eggshell. We describe several new features, such as triangular mineral particles in the cuticle, reported for the extinct Trigonoolithus amoei, and confirmed the existence of plugged pores. We suggest that these structures provide microbial protection needed by a burrow nesting species with a long incubation period.Item Impact of high- and low-flow nebulized saline on airway hydration and mucociliary transport(European Respiratory Society, 2023) Kelly S; Valentine M; Chua WH; Tatkov SBACKGROUND: Nebulised drugs, including osmotic agents and saline, are increasingly used during noninvasive respiratory support, including nasal high-flow therapy. The authors conducted an in vitro study to compare the hydration effect of nebulised isotonic 0.9% and hypertonic 7.0% saline on mucociliary transport. METHODS: In a perfused organ bath, 10 sheep tracheas were exposed to 7.5 mL nebulised 0.9% and 7.0% saline entrained into heated (38°C) and humidified air delivered at high and low flow (20 and 7 L·min-1, respectively). Simultaneous measurements of the airway surface liquid height, mucus transport velocity, cilia beat frequency and surface temperature were made over time. The data are presented as mean±sd. RESULTS: The airway surface liquid height increased significantly with both 0.9% and 7.0% saline: at low-flow by 37.2±10.0 µm and 152.7±10.9 µm, respectively, and at high-flow by 62.3±5.6 µm and 163.4±25.4 µm, respectively (p<0.001). Mucus velocity was increased by both 0.9% and 7.0% saline from a baseline of 8.2±0.8 mm·min-1 to 8.8±0.7 mm·min-1 and 17.1±0.5 mm·min-1, respectively, with low-flow and at high-flow to 9.8±0.02 mm·min-1 (p=0.04) and 16.9±0.5 mm·min-1 (p<0.05), respectively. Ciliary beating did not change with 0.9% saline, but declined from 13.1±0.6 Hz to 10.2±0.6 Hz and 11.1±0.6 Hz (p<0.05) with 7.0% saline at low- and high-flow, respectively. CONCLUSIONS: The findings demonstrate that nebulised isotonic 0.9% saline, like hypertonic 7.0% saline, significantly stimulates basal mucociliary transport, and the use of high-flow delivery had no significantly different hydration effects compared with low-flow delivery. Hypertonic 7.0% saline suppressed ciliary beating, indicating an increase in airway surface liquid osmolarity, which may have negative effects on the airway surface with frequent use.Item Inhibisie van osteoklastvorming en beenresorpsie deur poli-onversadigde vetsure in RAW 264.7 muismonosiete(AOSIS Ltd, 2012) Boeyens JCA; Chua WH; Kruger M; Joubert AM; Coetzee MInhibition of osteoclast differentiation and bone resorption by polyunsaturated fatty acids in RAW 264.7 murine macrophages. This study investigated the effects of polyunsaturated fatty acids on osteoclast formation and bone resorption in RAW 264.7 murine pre-osteoclasts. Data obtained suggests an inhibitory effect of these compounds on osteoclastogenesis and bone resorption in the cell line tested. Beenhermodellering in volwassenes is ‘n fisiologiese proses wat die sintese van beenmatriks deur osteoblaste en die resorpsie (afbraak) van been deur osteoklaste behels. Osteoklaste ontstaan deur die samesmelting van hematopoïetiese selle van monosiet-makrofaagafkoms en speel ‘n deurslaggewende rol in beenhermodellering. Osteoklast-ooraktiwiteit kan die afbraak van been in verskeie patologiese toestande tot gevolg hê. Kliniese- en dierestudies het aangedui dat sommige poli-onversadigde vetsure ‘n voordelige effek op been kan hê. Die doel van hierdie proefstudie was om te bepaal of omega-3 en omega-6 poli-onversadigde vetsure osteoklastvorming vanaf RAW 264.7 monosiete moduleer en daardeur die aantal volwasse resorberende osteoklaste kan beïnvloed. Monosiet/makrofaag-muisselle (RAW 264.7 pre-osteoklaste) is teen 1.5x104 selle/putjie in steriele 24-put plaatjies in die aanwesigheid van 15 ng/ml muisreseptor-aktiveerder van NFκBligand (RANKL) gesaai. RANKL is noodsaaklik vir osteoklastvorming vanaf voorgangerselle. Etanol (oplosmiddelkontrole), die omega-6 poli-onversadigde vetsure aragidoonsuur en gammalinoleensuur asook die omega-3 poli-onversadigde vetsure eikosapentaënöesuur en dokosaheksaënöesuur is by die selkulture teen konsentrasies van 5–20 μg/ml gevoeg. Palmitiensuur, ‘n versadigde vetsuur, teen ‘n konsentrasie van 20 μg/ml is as positiewe kontrole vir inhibisie van osteoklastvorming gebruik. Na vyf dae inkubasie is osteoklastvorming geëvalueer deur van tartraat-weerstandigesuurfosfatase (TRAP)-kleuring gebruik te maak. TRAP-positiewe selle met vyf of meer kerne word as veelkernige osteoklaste beskou. Soortgelyke eksperimente is uitgevoer op plaatjies wat bedek is met ‘n sintetiese anorganiese beenoppervlak. Na sewe dae inkubasie is die selle afgewas en resorpsie van die oppervlak met behulp van mikroskoopfoto’s waargeneem. Die persentasie resorpsie-oppervlak is daarna met behulp van toepaslike rekenaarsagteware bepaal. Verder is RAW 264.7 selle op beenskyfies gesaai om die effek van poli-onversadigde vetsure op die degradering van organiese en anorganiese beenkomponente te evalueer. Na nege dae is die gekondisioneerde media afgetrek en die hoeveelheid Ca2+ en kollageenfragmente, beendegraderingsprodukte onderskeidelik afkomstig vanaf die anorganiese en organiese komponente van beenafbraak, deur gepaste kolorimetriese metodes bepaal. Resultate van hierdie studie het getoon dat die vorming van veelkernige osteoklaste deur die blootstelling aan poli-onversadigde vetsure by konsentrasies van 5–20 μg/ml geïnhibeer word. Blootstelling aan al die vetsure het tot inhibering van osteoklastvorming gelei met die grootste effek by die hoogste vetsuurkonsentrasies. Dokosaheksaënöesuur (omega-3) het die mees betekenisvolle inhiberende effek oor al die konsentrasies getoon en eikosapentaënöesuur die minste. Resorpsieholtes op die gesimuleerde beenplaatjies was kleiner waar die selle aan aragidoonsuur en dokosaheksaënöesuur blootgestel was in vergelyking met dié van die oplosmiddelkontrole, wat moontlik aan die laer voorkoms van volwasse veelkernige osteoklaste toegeskryf kan word. ‘n Afname in die beendegraderingsprodukte is ook waargeneem waar selle blootgestel is aan aragidoonsuur en dokosaheksaënöesuur in vergelyking met die oplosmiddelkontrole. Die resultate ondersteun die vermoede dat poli-onversadigde vetsure die vorming van volwasse osteoklaste inhibeer en daardeur ‘n beenbeskermende effek tot gevolg mag hê. Verdere navorsing is nodig om duidelikheid oor die meganismes wat hier betrokke is, te verkry. Hierdie navorsing is deur die Mediese Navorsingsraad en die Navorsings-ontwikkelingsprogram (Universiteit van Pretoria) befonds.