Effect of ternary phosphate-based glass compositions on osteoblast and osteoblast-like prolferation, differentiation and death in vitro

There is currently a need to expand the range of graft materials available to orthopaedic surgeons. This study investigated the effect of ternary phosphate based glass (PBG) compositions on the behaviour of osteoblast and osteoblast-like cells. PBGs of the formula in mol% P2O5 (50)-CaO (50-X)-Na2O (X), where X was either 2, 4, 6, 8 or 10 were produced and their influence on the proliferation, differentiation and death in vitro of adult human bone marrow stromal cells (hBMSCs) and human fetal osteoblast 1.19 (HFOB 1.19) cells were assessed. Tissue culture plastic (TCP) and hydroxyapatite (HA) were used as controls. Exposure to PBGs in culture inhibited cell adhesion, proliferation and increased cell death in both cell types studied. There was no significant difference in %cell death between the PBGs which was significantly greater than the controls. However, compared to other PBGs, a greater number of cells was found on the 48 mol% CaO which may have been due to either increased adherence, proliferation or both. This composition was capable of supporting osteogenic proliferation and early differentiation and supports the notion that chemical modification of the glass could to lead to a more biologically compatible substrate with the potential to support osteogenic grafting. Realisation of this potential should lead to the development of novel grafting strategies for the treatment of problematic bone defects.

Genome-wide analysis of p63 binding sites identifies AP-2 factors as co-regulators of epidermal differentiation

The p63 transcription factor (TP63) is critical in development, growth and differentiation of stratifying epithelia. This is highlighted by the severity of congenital abnormalities caused by TP63 mutations in humans, the dramatic phenotypes in knockout mice and de-regulation of TP63 expression in neoplasia altering the tumour suppressive roles of the TP53 family. In order to define the normal role played by TP63 and provide the basis for better understanding how this network is perturbed in disease, we used chromatin immunoprecipitation combined with massively parallel sequencing (ChIP-seq) to identify >7500 high-confidence TP63-binding regions across the entire genome, in primary human neonatal foreskin keratinocytes (HFKs). Using integrative strategies, we demonstrate that only a subset of these sites are bound by TP53 in response to DNA damage. We identify a role for TP63 in transcriptional regulation of multiple genes genetically linked to cleft palate and identify AP-2alpha (TFAP2A) as a co-regulator of a subset of these genes. We further demonstrate that AP-2gamma (TFAP2C) can bind a subset of these regions and that acute depletion of either TFAP2A or TFAP2C alone is sufficient to reduce terminal differentiation of organotypic epidermal skin equivalents, indicating overlapping physiological functions with TP63.

Linking response strategies adopted by construction firms during the 2007 economic recession to Porter’s generic strategies

The time period bridging the years 2007 to 2012 will be remembered as one characterised by dramatic changes in the Irish and UK construction industries. Construction companies witnessed unprecedented changes in the environment, namely the coincidence of a sharp economic downturn, the significant decline of public works, a reduction in lending, increased competition, and structural changes in the marketplace. Nevertheless, little has been documented on what response strategies construction companies adopt as a result of an economic recession. Based on four exploratory case studies, a taxonomy framework of the response strategies adopted by Irish and UK construction companies during the 2007 economic recession was developed relative to Porter’s (1980) generic strategies of cost leadership, differentiation, and focus. Porter’s model (1980) is a well known theoretical framework among business strategists and industrial economists worldwide. The analysis provides strong support for the adoption of cost leadership strategies as a means to surviving the 2007 economic recession. The case studies further suggest that cost control initiatives are one of the most important attributes in companies’ responses to the 2007 recession. The findings provide valuable assistance for construction contractors in developing effective strategies and thus reducing business failures during recessionary periods.

Biofilm formation by Bacillus subtilis: new insights into regulatory strategies and assembly mechanisms

Biofilm formation is a social behaviour that generates favourable conditions for sustained survival in the natural environment. For the Gram-positive bacterium Bacillus subtilis the process involves the differentiation of cell fate within an isogenic population and the production of communal goods that form the biofilm matrix. Here we review recent progress in understanding the regulatory pathways that control biofilm formation and highlight developments in understanding the composition, function and structure of the biofilm matrix.