Comparative biochemical and molecular evaluation of swarming of Proteus and effects of anti-swarm agents

In addition to inadequate understanding of swarming motility and virulence of Proteus, there is paucity of information on the relative effectiveness of the various anti-swarm agents. The anti-swarming effects of urea, sodium dodecylsulphate (SDS) and trihydroxymethylglycine (Tris) on 40 clinical isolates of Proteus Spp. were comparatively investigated and plasmids associated with swarming were characterized. The three substances elicited a comparable concentration-dependent anti-swarming property at 0.25 – 1.25% on nutrient agar. Anti-swarm agents displayed heterogeneity in their ability to cause significant decreases in the expression of virulence factors. Swarm motility was further found to be strongly associated with the expression of virulence factors in these strains. Of the Proteus strains tested, 32 were found to harbour 1 – 4 plasmids of size ranging from 6.0 – 33.5 kb. Plasmid curing resulted in loss of swarming in 65.6% of these strains. In order to reduce the risk of infection with virulent Proteus strains, the laboratory use of urea and SDS is suggested. Key Words: Proteus, swarming, urea, SDS, Tris. African Journal of Biotechnology Vol.3(1) 2004: 99-10

Design and fabrication of an improved plantain processing machine

Nigeria is the largest producer of plantain in West Africa with large percentage of it obtained in the southern part of the country. Plantains are of great nutritional importance, and the proximate analysis reported for plantain shows that per 100g edible portion, plantains contain 67.30 g water, 116 kcal of energy, and 31.15 g of carbohydrate. Although there are several machines that can process plantain but a complete machine that does pulverization, milling, drying, etc. is not readily available in Nigeria. In this research work, an improved plantain processing machine that comprises of all the units was designed and fabricated from available materials in Nigeria. 32kg of plantains were thoroughly peeled, washed, sliced and loaded in the pulverizer unit which pulverized the sliced plantain into paste. The plantain paste was properly dried and ground to obtained plantain flour. Performance evaluation was carried out on the fabricated machine. The results of the performance evaluation show that force, torque, and power of 320N, 33.60Nm, and 2533.7088W were required for operation of the machine. Furthermore, the total mass of flour produced from 32kg of plantain was 4.29kg. It was observed that mass of water in 32kg of plantain was 19.25kg. The total mass of plantain pulp after addition of 5kg of water was 37kg. These values were used to determine the percentage composition of water in the pulverized plantain pulp which was obtained as 65.54%. Besides, the efficiency of the machine and machine throughput capacity were obtained asKeywords: Plantain, Processing machine, Design, Fabrication, Flour, Pulverize

Differentiation of embryonic stem cells through controlled release of growth factors from microspheres

The development of microspheres for the sustained delivery of protein and small drug delivery has been utilised in tissue engineering and drug delivery applications. However problems exist in obtaining a controlled and predictable release pattern of the encapsulated molecules from these materials. In this study, microspheres with a zero order release kinetic profile and no lag phase were developed from a novel PLGA based polymer blend. The novel PLGA based polymer blend was made from blending PLGA with varying compositions of the triblock co-polymer PLGA-PEG-PLGA. These blends were subsequently used in the fabrication of lysozyme and dexamethasone loaded microspheres. Blending of the triblock copolymer with PLGA resulted in a reduction of the glass transition temperature (36.1ºC against 59.7ºC) and an increased mechanical strength (25.25 ± 1.26MPa against 0.26 ± 0.05MPa) for PLGA and 30% triblock w/w microspheres respectively. An incremental increase in the triblock composition within the Triblock/PLGA blends resulted in a corresponding reduction in glass transition temperature of the microspheres. Varying the triblock composition within the microspheres showed no significant effect on entrapment efficiency (EE) of lysozyme (protein) and dexamethasone (drug) within fabricated microspheres (EE ~ 60% for and 75% for loading weight 5% w/w for lysozyme and dexamethasone microspheres respectively). Controlled release experiments showed incorporation of the triblock increased the burst release of the protein and drug molecules from the microspheres and improved their release kinetics, with zero-order release profile (post burst phase) observed at a triblock composition of 30% w/w. A positive correlation between the amount of triblock within the triblock / PLGA blend and the rate of protein and drug release was also observed. The induction of osteogenesis and chondrogenesis within stem cells seeded on dexamethasone and ascorbate phosphate, and TGF-β3 loaded scaffolds was successfully demonstrated. Zonal release of TGF-β3 and BMP4 proteins from a bilayered scaffold was also demonstrated. However experiments conducted to demonstrate the tissue zonation within a bone cartilage bilayered construct developed from embryonic stem cell seeded TGF-β3 and BMP4 loaded bilayered scaffolds yielded inconclusive data. These results suggests that protein and drug loaded injectable microspheres for tissue engineering applications can be formed from triblock/PLGA blends, and that by varying the triblock composition, the temperature at which the microspheres form scaffolds, the release kinetics and the mechanical strength of the resulting scaffolds can be controlled

Influence of solute-source composition on composition-dependent interdiffusion coefficient

The validity of a long-held implicit assumption that the composition-dependent interdiffusion coefficient is a material parameter that is isothermally constant, irrespective of solute-source composition, is studied theoretically and experimentally. Solute concentration distributions under the influence of diffusion-induced stress generation and relaxation are numerically simulated, and the results are used to compute and compare composition-dependent interdiffusion coefficients under different solute-source compositions. The results of both the theoretical and experimental analyses show that solute-source concentration can significantly change the composition dependency of interdiffusion coefficient, in contrast to what is often implicitly assumed. Accordingly, the use of concentration-dependent interdiffusion functions, obtained from pure-metal/pure-metal diffusion couples, to predict or analyze diffusion effects when the solute-source is an alloy instead of a pure-metal can be grossly inaccurate

Flow and Heat Transfer Analysis of the Sodium Alginate Conveying Copper Nanoparticles between Two Parallel Plates

In this study, the steady incompressible flow of a non-Newtonian sodium alginate (SA) fluid conveying copper nanoparticles (Cu) which flow within two vertical parallel plates is investigated by using the homotopy perturbation analytical scheme to solve the coupled nonlinear ordinary equations arising from the mechanics of the fluid. The developed analytical solutions are used to investigate the effect of the fluid flow and heat transfer parameters such as the nanoparticle concentration, the non-Newtonian parameter and the viscosity variation parameter. The obtained analytical results as compared to existing works in literature are in satisfactory agreements. Moreover, the results obtained from the present study can be used for further analysis of the behavior of the sodium alginate in applications such as food processing and chemical and pharmaceutical industries

Differentiation of embryonic stem cells through controlled release of growth factors from microspheres

The development of microspheres for the sustained delivery of protein and small drug delivery has been utilised in tissue engineering and drug delivery applications. However problems exist in obtaining a controlled and predictable release pattern of the encapsulated molecules from these materials. In this study, microspheres with a zero order release kinetic profile and no lag phase were developed from a novel PLGA based polymer blend. The novel PLGA based polymer blend was made from blending PLGA with varying compositions of the triblock co-polymer PLGA-PEG-PLGA. These blends were subsequently used in the fabrication of lysozyme and dexamethasone loaded microspheres. Blending of the triblock copolymer with PLGA resulted in a reduction of the glass transition temperature (36.1ºC against 59.7ºC) and an increased mechanical strength (25.25 ± 1.26MPa against 0.26 ± 0.05MPa) for PLGA and 30% triblock w/w microspheres respectively. An incremental increase in the triblock composition within the Triblock/PLGA blends resulted in a corresponding reduction in glass transition temperature of the microspheres. Varying the triblock composition within the microspheres showed no significant effect on entrapment efficiency (EE) of lysozyme (protein) and dexamethasone (drug) within fabricated microspheres (EE ~ 60% for and 75% for loading weight 5% w/w for lysozyme and dexamethasone microspheres respectively). Controlled release experiments showed incorporation of the triblock increased the burst release of the protein and drug molecules from the microspheres and improved their release kinetics, with zero-order release profile (post burst phase) observed at a triblock composition of 30% w/w. A positive correlation between the amount of triblock within the triblock / PLGA blend and the rate of protein and drug release was also observed. The induction of osteogenesis and chondrogenesis within stem cells seeded on dexamethasone and ascorbate phosphate, and TGF-β3 loaded scaffolds was successfully demonstrated. Zonal release of TGF-β3 and BMP4 proteins from a bilayered scaffold was also demonstrated. However experiments conducted to demonstrate the tissue zonation within a bone cartilage bilayered construct developed from embryonic stem cell seeded TGF-β3 and BMP4 loaded bilayered scaffolds yielded inconclusive data. These results suggests that protein and drug loaded injectable microspheres for tissue engineering applications can be formed from triblock/PLGA blends, and that by varying the triblock composition, the temperature at which the microspheres form scaffolds, the release kinetics and the mechanical strength of the resulting scaffolds can be controlled

Full Length Research Paper - Comparative biochemical and molecular evaluation of swarming of Proteus and effects of anti-swarm agents

In addition to inadequate understanding of swarming motility and virulence of Proteus, there is paucity of information on the relative effectiveness of the various anti-swarm agents. The anti-swarming effects of urea, sodium dodecylsulphate (SDS) and trihydroxymethylglycine (Tris) on 40 clinical isolates of Proteus Spp. were comparatively investigated and plasmids associated with swarming were characterized. The three substances elicited a comparable concentration-dependent anti-swarming property at 0.25 -1.25% on nutrient agar. Anti-swarm agents displayed heterogeneity in their ability to cause significant decreases in the expression of virulence factors. Swarm motility was further found to be strongly associated with the expression of virulence factors in these strains. Of the Proteus strains tested, 32 were found to harbour 1 - 4 plasmids of size ranging from 6.0 -33.5 kb. Plasmid curing resulted in loss of swarming in 65.6% of these strains. In order to reduce the risk of infection with virulent Proteus strains, the laboratory use of urea and SDS is suggested