Characterization of a composite polylactic acid-hydroxyapatite 3D-printing filament for bone-regeneration

Autologous cancellous-bone grafts are the current gold standard for therapeutic interventions in which bone-regeneration is desired. The main limitations of these implants are the need for a secondary surgical site, creating a wound on the patient, the limited availability of harvest-safe bone, and the lack of structural integrity of the grafts. Synthetic, resorbable, bone-regeneration materials could pose a viable treatment alternative, that could be implemented through 3D-printing. We present here the development of a polylactic acid-hydroxyapatite (PLA-HAp) composite that can be processed through a commercial-grade 3D-printer. We have shown that this material could be a viable option for the development of therapeutic implants for bone regeneration. Biocompatibility in vitro was demonstrated through cell viability studies using the osteoblastic MG63 cell-line, and we have also provided evidence that the presence of HAp in the polymer matrix enhances cell attachment and osteogenicity of the material. We have also provided guidelines for the optimal PLA-HAp ratio for this application, as well as further characterisation of the mechanical and thermal properties of the composite. This study encompasses the base for further research on the possibilities and safety of 3D-printable, polymer-based, resorbable composites for bone regeneration

The Role of Dysregulated Glucose Metabolism in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic cancer and also one of the most poorly understood. Other health issues that are affecting women with increasing frequency are obesity and diabetes, which are associated with dysglycemia and increased blood glucose. The Warburg Effect describes the ability of fast-growing cancer cells to preferentially metabolize glucose via anaerobic glycolysis rather than oxidative phosphorylation. Recent epidemiological studies have suggested a role for hyperglycemia in the pathogenesis of a number of cancers. If hyperglycemia contributes to tumour growth and progression, then it is intuitive that antihyperglycemic drugs may also have an important antitumour role. Preliminary reports suggest that these drugs not only reduce available plasma glucose, but also have direct effects on cancer cell viability through modification of molecular energy-sensing pathways. This review investigates the effect that hyperglycemia may have on EOC and the potential of antihyperglycemic drugs as therapeutic adjuncts

Effect of demineralising agents on organic and inorganic components of dentine

There is a requirement to ensure that in-vitro studies that use demineralised human dentine models are reliable and clinically relevant. The literature reports several strategies for these studies with a lack of consensus on the mode of action of the different demineralising acids on human dentine. This in-vitro study aims to characterise the effect of clinically-relevant acids on human dentine, using standardised substrates and complementary analytical techniques. The study focuses on an analysis of the mineral content and the integrity of the collagen following partial demineralisation. Samples of human dentine were exposed to a range of acids commonly encountered in the oral cavity. Characterisation of the mineral content used Vickers micro-hardness, Energy dispersive spectroscopy and X-ray fluorescence. Characterisation of the collagen integrity was undertaken by means of Scanning electron microscopy and Hydroxyproline assay. The following conclusions were reached: (i) Each demineralising agent tested had a unique effect on the mineral levels; (ii) Chelating agents, strong acids and weak acids affect the mineral and organic phases of dentine in significantly different ways with no correlation between them; (iii) The demineralising agents caused some degree of collagen denaturation, citric acid causing the most damage. Overall, there is no clear link between the type of demineralising agent and the effect on the organic and inorganic dentine. The choice of demineralising agent should be aligned to the experiment objectives so that the selected dentine (caries or erosion) model is fit for purpose

Basal metabolism of obese adolescents: Evidence for energy conservation compared to normal and lean adolescents

To test if obese adolescents systematically conserve energy, comparisons of basal metabolic rate (BMR) of obese, normal, and lean male and female adolescents were made. Obese had eleevated values by as much as 23% ( P ≤ 0.05) expressed as kJ · 24 hr −1 compared to the normal and lean. When indexed to body mass (kJ · kg-BM −1 · hr −1 ), the BMR for the obese was depressed by as much as −53% ( P ≤ 0.01), and when indexed to fat free mass (kJ · kg-FFM −1 · hr −1 ) it was depressed by −33% compared to normal and lean adolescents. A “theoretical metabolic rate” (TMR), based on the observed fat free mass, fat mass, and their thermal equivalents, was proposed as a theoretical way to properly index basal metabolism, referenced to body composition. Comparisons of the TMR between the obese, normal, and lean revealed that the obese values were depressed by an average −22% ( P ≤ 0.05). In comparison, differences in TMR between the normal and lean males and females were no larger than 8% (ns). It was concluded that since both the observed BMR (expressed relative to body composition), and the derived TMR values were depressed for the obese compared to the normal and lean adolescent, the data suggest an energy saving hypothesis for obese adolescents.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38546/1/1310020510_ftp.pd