A fluidized bed kinetic model for the fluorination of Zircon

Please read the abstract in the section 00front of this documentDissertation (M Eng (Chemical Engineering))--University of Pretoria, 2006.Chemical Engineeringunrestricte

Oxygen carriers for a novel bio-artificial liver support system

The purpose of the investigation was the design and development of an oxygen carrier system for oxygenation of liver cells (hepatocytes) in a bio-artificial liver support system. Acute liver failure is a devastating condition with higher than 80% mortality. Currently the only successful treatment is orthotopic liver transplantation. The high mortality rate could be reduced if a system could be developed that could bridge the patient either until recovery (due to the liver’s well-known regeneration ability) or until transplantation. Such a system requires a bioreactor with a high density of cultured cells. Sufficient oxygen delivery to the cells is critical to ensure efficient cell function. The CSIR and University of Pretoria (UP) have designed and developed a novel bio-artificial liver support system (BALSS) that utilizes perfluorooctyl bromide (PFOB) as artificial oxygen carrier. As the PFOB is not miscible with water, it needs to be emulsified. To enable the use of the PFOB emulsion in the UP-CSIR BALSS, a study was carried out to investigate relevant aspects relating to the PFOB emulsion, i.e. the formulation, manufacturing procedure, stability, rheology and mass transfer characteristics. The study results are reported in this dissertation, including a proposed mass transfer model for describing oxygen mass transfer to and from the PFOB emulsions. Emulsion stability can be improved through control of the droplet size and size distribution, limiting Ostwald ripening, and control of zeta potential of the dispersed phase droplets. PFOB emulsions with dispersed phase (PFOB) volume fractions between 0.4 and 0.5 and Sauter mean droplet diameter between 100 and 200 nm were found to be optimal for oxygen mass transfer in cell culture systems. The PFOB emulsion in the UP-CSIR BALSS can be concentrated and recirculated using ultrafiltration. Quantitative recovery of PFOB from its emulsions can be carried out using distillation with orthophosphoric acid. Experimental overall mass transfer coefficients for membrane oxygenators obtained without PFOB compared well with literature reported values of 2.5x10-5 m/s by Goerke et al. (2002) and 1 – 3x10-5 m/s by Schneider et al. (1995) for similar systems. The addition of 0.2 v/v PFOB leads to an increase in the membrane oxygenator mass transfer coefficient by a factor of about 30, and an increase in oxygen carrying capacity by a factor of about 4.5. It was also shown that suitable PFOB emulsions can have a significant impact on the growth and function of hepatocytes in a BALSS.Thesis (PhD (Chemical Engineering))--University of Pretoria, 2005.Chemical Engineeringunrestricte

An in vitro and in vivo study on the properties of hollow polycaprolactone cell-delivery particles

The field of dermal fillers is evolving rapidly and numerous products are currently on the market. Biodegradable polymers such as polycaprolactone (PCL) have been found to be compatible with several body tissues, and this makes them an ideal material for dermal filling purposes. Hollow PCL spheres were developed by the Council for Scientific and Industrial Research (CSIR) to serve both as an anchor point and a ªtissue harbourº for cells. Particles were tested for cytotoxicity and cell adherence using mouse embryo fibroblasts (MEF). MEFs adhered to the particles and no significant toxic effects were observed based on morphology, cell growth, cell viability and cell cycle analysis, suggesting that the particles are suitable candidates for cell delivery systems in an in vivo setting. The objective of providing a ªtissue harbourº was however not realized, as cells did not preferentially migrate into the ported particles. In vivo studies were conducted in BALB/c mice into whom particles were introduced at the level of the hypodermis. Mice injected with PCL particles (ported and nonported; with or without MEFs) showed evidence of local inflammation and increased adipogenesis at the site of injection, as well as a systemic inflammatory response. These effects were also observed in mice that received apparently inert (polystyrene) particles. Ported PCL particles can therefore act as a cell delivery system and through their ability to induce adipogenesis, may also serve as a dermal bulking agent.S1 File. Figure A: Chronic inflammation in the test animals over the trial period. Figure B: Acute inflammation in the test animals over the trial period. Figure C: Tissue necrosis in the test animals over the trial period. Figure D: Fibrosis in the test animals over the trial period. Figure E: Granulomatous/foreign body response in the test animals over the trial period. Figure F: Representative TEMs of skin biopsies of particles group (A) and particles+MEFs group (B) in the in vivo experiment injecting particles+MEFs. Particles could be identified in skin biopsies of both the particles and particles+MEFs groups. The aim of the TEM investigation was to determine if any cells could be detected inside the particles. No cells were present inside the particles in either group. These results reflect the conclusion that was made after the light microscopy study, indicating that cells did not migrate into the ported PCL particles. Bar in A = 5μm and in B = 10μm.S2 File. In vitro and in vivo data. Table A: Groups of rats used in the biotoxicity trial. Table B: Observations on mice in the in vivo experiment assessing the effect of ported PCL particles and cells. Table C: Statistical comparisons preformed between the various white blood cell types assessed from blood smears of experimental mice injected with ported PCL particles with or without MEFs. Table D: Schedule of the in vivo experiment assessing the effect of ported and non-ported PCL as well as polystyrene (PS) particles. Table E: Overview of the animals, tests and procedures performed in the in vivo experiment assessing the effect of ported and non-ported PCL as well as polystyrene (PS) particles in BALB/c mice.S3 File. All data underlying the findings of the study.The Council for Scientific and Industrial Research, South Africa, by the Institute for Cellular and Molecular Medicine of the University of Pretoria and by the South African Medical Research Council (Flagship Award SAMRC-RFA-UFSP-01-2013/ STEM CELLS and the SAMRC Extramural Unit for Stem Cell Research and Therapy).http://www.plosone.orgam2019ImmunologyPhysiolog

Thermo-responsive non-woven scaffolds for "smart" 3D cell culture

The thermo-responsive polymer poly(N-isopropylacrylamide) has received widespread attention for its in vitro application in the non-invasive, non-destructive release of adherent cells on two dimensional surfaces. In this study, 3D non-woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (PET) and nylon that had been grafted with PNIPAAm were tested for their ability to support the proliferation and subsequent thermal release of HC04 and HepG2 hepatocytes. Hepatocyte viability and proliferation was estimated using the Alamar Blue assay and Hoechst 33258 total DNA quantification. The assays revealed that the pure and grafted non-woven scaffolds maintained the hepatocytes within the matrix and promoted 3D proliferation comparable to that of the commercially available AlgimatrixTM alginate scaffold. Albumin production and selected cytochrome P450 genes expression was found to be superior in cells growing on pure and grafted non-woven PP scaffolds as compared to cells grown as a 2D monolayer. Two scaffolds, namely, PP-g- PNIPAAm-A and PP-g-PNIPAAm-B were identified as having far superior thermal release capabilities; releasing the majority of the cells from the matrices within 2 h. This is the first report for the development of 3D non-woven, thermo-responsive scaffolds able to release cells from the matrix without the use of any enzymatic assistance or scaffold degradation.The Council for Scientific and Industrial Researchhttp://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-0290hb2016Biochemistr

Qualitative assessment of smooth muscle cells propagated on 2D-and 3D-polycaprolactone polymers via scanning electron microscope

Polycaprolactone (PCL) polymers which illustrate both biocompatibility and resorbability for replacement or bulking of damaged or diseased tissue are important in tissue engineering. Cytocompatibilty of these polymers was assessed on two-dimensional PCL disks and threedimensional PCL solid and PCL hollow microspheres using human uterine mixed leiomyosarcoma (SKUT-1) and hamster ductus deferens leiomyosarcoma (CRL-1701) cell lines. Possible PCL cytotoxicity and morphology were investigated in SKUT- and CRL-1701 cells. SKUT cells cultured in disk and microsphere extracts between 24 h and 5 day time periods displayed statistically increased metabolic activity, though activity decreased significantly on 1 month and 1 year extracts. However, the metabolic activity of CRL-1701 cells was similar to controls. Activity increased significantly on the 1 month extracts and decreased significantly on the 1 year extracts. Scanning electron microscopy illustrated increased cell density of cells attached to pre-conditioned disks. After 5 days, cells were spindle-shaped, following microspheres contours indicating high focal adhesion. Both cell lines migrated inside the hollow microspheres, indicating that they benefit from the sheltered environment. This in vitro study suggests that hollow microspheres allow for further cell expansion with a sheltered environment to protect cells from sheer stress experienced in vivo.The Biomaterials and Polymer Division from the Council of Scientific and Industrial Research (Pretoria, South Africa) and the Department of Physiology, University of Pretoria (Pretoria, South Africa).http://www.jstage.jst.go.jp/browse/biomedre

Development of thermoresponsive poly(propylene-g-N-isopropylacrylamide) non-woven 3D scaffold for smart cell culture using oxyfluorination-assisted graft polymerisation

Growing cells on 3D scaffolds is far superior to the conventional 2D monolayer culture method. In this study, a novel 3D thermoresponsive poly(propylene-g-N-isopropylacrylamide) (PP-g-PNIPAAm) nonwoven fabric (gNWF) was developed for cell culture using oxyfluorination-assisted graft polymerisation (OAGP). New polar functional groups were detected on the oxyfluorinated NWF (oNWF), and PNIPAAm was confirmed in the gNWF by attentuated total-reflectance Fourier transform infrared (ATR-FTIR) and scanning X-ray photoelectron spectroscopy (S-XPS). Scanning electron microscopy (SEM) revealed a rough surface morphology and confinement of the PNIPAAm graft layer to the surface of the fibres in the gNWF. The OAGP method did not affect the crystalline phase of bulk PP, however, twin-melting thermal peaks were detected for the oNWF and gNWF indicating crystal defects. Contact angle studies showed that the surface of the gNWF exhibited a thermoresponsive behaviour. Hepatocyte cells attached onto gNWF disks in a bioreactor at 37 ◦C and remained viable for 10 days in culture. Upon cooling the cell culture media to 20 ◦C, cells were spontaneously released as 3D multi-cellular constructs without requiring destructive enzymes. The development of 3D thermoresponsive scaffolds capable of non-invasive 3D cell culture could provide a more reliable in vitro model for cells.http://www.elsevier.com/locate/colsurfahb201

Experiential dream analysis as a stress management technique with adolescents

Advanced project (M.A.) -- University of Stellenbosch, 1987.Full text to be digitised and attached to bibliographic record

Hepatocyte function in a radial-flow bioreactor using a perfluorocarbon oxygen carrier

The aims of this study were, first, to indicate the metabolic activity of hepatocytes in a radial-flow polyurethane foam matrix bioreactor relative to monocultures, and second, to evaluate the effect on the hepatocytes of including a synthetic perfluorocarbon (PFC) oxygen carrier to the recirculating medium. The efficient O2-carrying ability of PFCs may be beneficial to bioreactors employed in stressed cellular environments. Thus, they may also be useful in the treatment of an acute liver failure patient with a bioartificial liver support system (BALSS). Data on the function of three-dimensional (3-D) hepatocyte cultures exposed to emulsified PFCs are lacking. RESULTS: the metabolic functions of the 3-D hepatocyte cultures were improved relative to monocultures. Three-dimensional cultures with and without PFC behaved similarly, and no adverse effects could be detected when PFC was included in the recirculating medium. The addition of PFC significantly improved lidocaine clearance possibly due to the presence of higher O2 tension in the medium. Imaging indicated that large aggregates formed and that seeding had followed flow through the matrix. Simulations indicated first, that the cell numbers used in this study had been insufficient to challenge the bioreactor O2 supply explaining the similarity in performance of the 3-D cultures, and second, that the benefit of adding PFC would be more pronounced at the cell densities likely to be used in a BALSS bioreacto

Acridine orange-stained MEFs attached to ported PCL particles.

<p>Cells were propagated in glass Kimble tubes together with particles (A and B) and stained 24 h after seeding. MEFs attached to particles as clumps.</p

An <i>in vitro</i> and <i>in vivo</i> study on the properties of hollow polycaprolactone cell-delivery particles - Fig 9

<p><b>Monocyte (A), neutrophil (B), eosinophil (C) and lymphocyte (D) profiles at 1, 2, 4 and 8 weeks in mice injected with non-ported PCL, ported PCL and PS particles</b>. No significant differences were observed between the test groups and the controls at 1, 2, 4 and 8 weeks. Increases in monocyte, neutrophil and eosinophil counts and decreases in lymphocyte counts were seen between week 1 and subsequent time points in all particle injected mice. Connecting lines indicate a <i>P</i>-value <0.05.</p