923 resultados para Biological sciences


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Phospholipid (PL) molecules form the main structure of the membrane that prevents the direct contact of opposing articular cartilage layers. In this paper we conceptualise articular cartilage as a giant reverse micelle (GRM) in which the highly hydrated three-dimensional network of phospholipids is electrically charged and able to resist compressive forces during joint movement, and hence loading. Using this hypothetical base, we describe a hydrophilic-hydrophilic (HL-HL) biopair model of joint lubrication by contacting cartilages, whose mechanism is reliant on lamellar cushioning. To demonstrate the viability of our concept, the electrokinetic properties of the membranous layer on the articular surface were determined by measuring via microelectrophoresis, the adsorption of ions H, OH, Na and Cl on phospholipid membrane of liposomes, leading to the calculation of the effective surface charge density. The surface charge density was found to be -0.08 ± 0.002 cm-2 (mean ± S.D.) for phospholipid membranes, in 0.155 M NaCl solution and physiological pH. This value was approximately five times less than that measured in 0.01 M NaCl. The addition of synovial fluid (SF) to the 0.155 M NaCl solution reduced the surface charge density by 30% which was attributed to the binding of synovial fluid macromolecules to the phospholipid membrane. Our experiments show that particles charge and interact strongly with the polar core of RM. We demonstrate that particles can have strong electrostatic interactions when ions and macromolecules are solubilized by reverse micelle (RM). Since ions are solubilized by reverse micelle, the surface entropy influences the change in the charge density of the phospholipid membrane on cartilage surfaces. Reverse micelles stabilize ions maintaining equilibrium, their surface charges contribute to the stability of particles, while providing additional screening for electrostatic processes. © 2008 Elsevier Ireland Ltd. All rights reserved.

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Many of the undergraduate and postgraduate programs of the former Faculty of Built Environment and Engineering PLUS Faculty of Sciences and Technology are changing as a result of merging these two large organisations, with some disciplines relocating to faculties of Creative Industries and Health respectively. The new STEM precinct under construction has begun rising from the proverbial hole-in-the-ground. Existing Surveying and Spatial Sciences programs, assets and staff are being repositioned with the newly formed School of Earth, Environment and Biological Sciences.2011. Golden graduates morning tea organised by QUT Alumni. Technology upgrades to the Mapping Sciences lab benefits 3-D learning experiences. Second and third-year students are undertaking Work Integrated Learning (WIL) over the summer vacation period. Final year students recently presented capstone project presentations at mini-conference in the Gibson Rooms overlooking a vibrant Southbank and sparkling Brisbane River. Discussion on end of year graduation ceremony held at QPAC.

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Eukaryotic cell cycle progression is mediated by phosphorylation of protein substrates by cyclin-dependent kinases (CDKs). A critical substrate of CDKs is the product of the retinoblastoma tumor suppressor gene, pRb, which inhibits G1-S phase cell cycle progression by binding and repressing E2F transcription factors. CDK-mediated phosphorylation of pRb alleviates this inhibitory effect to promote G1-S phase cell cycle progression. pRb represses transcription by binding to the E2F transactivation domain and recruiting the mSin3·histone deacetylase (HDAC) transcriptional repressor complex via the retinoblastoma-binding protein 1 (RBP1). RBP1 binds to the pocket region of pRb via an LXCXE motif and to the SAP30 subunit of the mSin3·HDAC complex and, thus, acts as a bridging protein in this multisubunit complex. In the present study we identified RBP1 as a novel CDK substrate. RBP1 is phosphorylated by CDK2 on serines 864 and 1007, which are N- and C-terminal to the LXCXE motif, respectively. CDK2-mediated phosphorylation of RBP1 or pRb destabilizes their interaction in vitro, with concurrent phosphorylation of both proteins leading to their dissociation. Consistent with these findings, RBP1 phosphorylation is increased during progression from G 1 into S-phase, with a concurrent decrease in its association with pRb in MCF-7 breast cancer cells. These studies provide new mechanistic insights into CDK-mediated regulation of the pRb tumor suppressor during cell cycle progression, demonstrating that CDK-mediated phosphorylation of both RBP1 and pRb induces their dissociation to mediate release of the mSin3·HDAC transcriptional repressor complex from pRb to alleviate transcriptional repression of E2F.

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This paper provides a critique of the Water Sensitive Urban Design (WSUD) paradigm by discussing its congruence with an established sustainable design principle called 'whole system design'. It was found that WSUD is congruent with the whole system design approach as a philosophy, but not in practice. Future improvement of WSUD practice may depend on the adoption of a front-loaded, teamwork-based design and planning process that is embedded in the principle of whole system design.