A practical miniature long-term bone marrow culture system for investigating early myelodysplasia

A method was devised to grow haemopoietic cells in long-term bone marrow culture (LTBMC) which requires only 1 x 10(6) cells/culture. Such miniature cultures were used to study growth patterns of marrow from patients with myelodysplastic syndromes (MDS). Consistent differences in LTBMC cellularity and cellular composition were noted between MDS and normal marrow. These differences were accentuated by rGM-CSF. The criteria which distinguished between and MDS marrows were: cell count at weeks 1 and 4, % neutrophils and % blasts. In 10 patients with unexplained macrocytosis or pancytopenia miniature LTBMC results clearly segregated into either 'normal' or 'MDS' growth patterns. Miniature LTBMC with rGM-CSF may therefore be a useful diagnostic test for early MDS.

Gentamicin-loaded nanoparticles show improved antimicrobial effects towards Pseudomonas aeruginosa infection

Gentamicin is an aminoglycoside antibiotic commonly used for treating Pseudomonas infections, but its use is limited by a relatively short half-life. In this investigation, developed a controlled-release gentamicin formulation using poly(lactide-co-glycolide) (PLGA) nanoparticles. We demonstrate that entrapment of the hydrophilic drug into a hydrophobic PLGA polymer can be improved by increasing the pH of the formulation, reducing the hydrophilicity of the drug and thus enhancing entrapment, achieving levels of up to 22.4 µg/mg PLGA. Under standard incubation conditions, these particles exhibited controlled release of gentamicin for up to 16 days. These particles were tested against both planktonic and biofilm cultures of P. aeruginosa PA01 in vitro, as well as in a 96-hour peritoneal murine infection model. In this model, the particles elicited significantly improved antimicrobial effects as determined by lower plasma and peritoneal lavage colony-forming units and corresponding reductions of the surrogate inflammatory indicators interleukin-6 and myeloperoxidase compared to free drug administration by 96 hours. These data highlight that the controlled release of gentamicin may be applicable for treating Pseudomonas infections.

Novel, antibacterial silicone biomaterials for the prevention of microbial adherence and infection in urinary catheters

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Essay - The role of ecological theory in microbial ecology

Microbial ecology is currently undergoing a revolution, with repercussions spreading throughout microbiology, ecology and ecosystem science. The rapid accumulation of molecular data is uncovering vast diversity, abundant uncultivated microbial groups and novel microbial functions. This accumulation of data requires the application of theory to provide organization, structure, mechanistic insight and, ultimately, predictive power that is of practical value, but the application of theory in microbial ecology is currently very limited. Here we argue that the full potential of the ongoing revolution will not be realized if research is not directed and driven by theory, and that the generality of established ecological theory must be tested using microbial systems.

Vasculogenic and osteogenesis-enhancing potential of human umbilical cord blood endothelial colony-forming cells

Umbilical cord blood-derived endothelial colony-forming cells (UCB-ECFC) show utility in neovascularization, but their contribution to osteogenesis has not been defined. Cocultures of UCB-ECFC with human fetal-mesenchymal stem cells (hfMSC) resulted in earlier induction of alkaline phosphatase (ALP) (Day 7 vs. 10) and increased mineralization (1.9×; p <.001) compared to hfMSC monocultures. This effect was mediated through soluble factors in ECFC-conditioned media, leading to 1.8-2.2× higher ALP levels and a 1.4-1.5× increase in calcium deposition (p <.01) in a dose-dependent manner. Transcriptomic and protein array studies demonstrated high basal levels of osteogenic (BMPs and TGF-ßs) and angiogenic (VEGF and angiopoietins) regulators. Comparison of defined UCB and adult peripheral blood ECFC showed higher osteogenic and angiogenic gene expression in UCB-ECFC. Subcutaneous implantation of UCB-ECFC with hfMSC in immunodeficient mice resulted in the formation of chimeric human vessels, with a 2.2-fold increase in host neovascularization compared to hfMSC-only implants (p = .001). We conclude that this study shows that UCB-ECFC have potential in therapeutic angiogenesis and osteogenic applications in conjunction with MSC. We speculate that UCB-ECFC play an important role in skeletal and vascular development during perinatal development but less so in later life when expression of key osteogenesis and angiogenesis genes in ECFC is lower.

Self-potential and spectral induced polarization signals associated with microbial sulphate reduction

Self-potential and spectral induced polarization responses associated with microbial processes involved in sulphate reduction have been monitored in a Perspex Winogradsky column filled with glass beads and growth medium. Salt-bridge is utilized as an electrolytic contact between experiment and control column. Equally spaced SP electrodes are used in combination of Ag-AgCl electrodes to compare electrodic and SP signals associated with the microbial processes involved in sulphate reduction. This study reveals that magnitude of SP varies from 5 to -2 mV and Electrodic potential 0 to -20 mV at the time of domination (day 39) of sulphate reducing bacteria which are very small in comparison to those measured by fixing both measuring and reference Ag-AgCl electrodes in experiment column. We observed that real and imaginary parts of complex conductivities increase with increase in production of H2S and CO in the experiment column. Both real and imaginary parts of surface complex conductivity vary at low frequencies similar to typical growth curve of bacterial population. Sodium lactate as a carbon source, dissolved in Lagan River water was flushed into the column for biostimulation on 144th day. The dissolved oxygen in flushed fluid might have killed the anaerobes in the column and decrease in complex conductivities similar to death phase of bacteria is observed for one week. The results obtained from this experiment should contribute to further understanding the biogeophysical responses involved in complex environments.


Read More: http://library.seg.org/doi/abs/10.1190/segj092009-001.57

Flux and turnover of fixed carbon in soil microbial biomass of limed and unlimed plots of an upland grassland ecosystem

The influence of liming on rhizosphere microbial biomass C and incorporation of root exudates was studied in the field by in situ pulse labelling of temperate grassland vegetation with (13)CO(2) for a 3-day period. In plots that had been limed (CaCO(3) amended) annually for 3 years, incorporation into shoots and roots was, respectively, greater and lower than in unlimed plots. Analysis of chloroform-labile C demonstrated lower levels of (13)C incorporation into microbial biomass in limed soils compared to unlimed soils. The turnover of the recently assimilated (13)C compounds was faster in microbial biomass from limed than that from unlimed soils, suggesting that liming increases incorporation by microbial communities of root exudates. An exponential decay model of (13)C in total microbial biomass in limed soils indicated that the half-life of the tracer within this carbon pool was 4.7 days. Results are presented and discussed in relation to the absolute values of (13)C fixed and allocated within the plant-soil system.