An evaluation of near-patient testing of anticoagulant control in general practice.

PURPOSE: This paper aims to compare anticoagulant management in secondary care for the year prior to the introduction of near-patient testing in a general practice, and in the subsequent year after it was introduced. DESIGN/METHODOLOGY/APPROACH: This paper is a retrospective, paired before-after study. Details of test results in the two-year-long periods on the 46 patients who met the inclusion criteria were collected and analysed pairwise. FINDINGS: Despite an increase in the frequency of testing this set of patients were controlled as well in general practice as they had been with a secondary-care service, and better that in a number of studies in the literature. RESEARCH LIMITATIONS/IMPLICATIONS: This research reviews a recently introduced service at a single centre. Further research of patient satisfaction and adverse events in a multi-centre longer-term trial are desirable. PRACTICAL IMPLICATIONS: Technology now allows the increasing amount of individuals on anticoagualtion to be controlled with near-patient testing in general practice. This study shows that satisfactory control can be maintained in patients who transfer from a secondary care-based to a primary care-based service. ORIGINALITY/VALUE: This paper demonstrates that a single general practice can provide a high quality anticoagulant service using near-patient testing and computer-based decision support. This adds to the already available evidence and will hopefully encourage other practices to adopt the same.

EWS-FLI1 causes neuroepithelial defects and abrogates emigration of neural crest stem cells.

The most frequently occurring chromosomal translocation that gives rise to the Ewing's sarcoma family of tumors (ESFT) is the chimeric fusion gene EWS-FLI1 that encodes an oncogenic protein composed of the N terminus of EWS and the C terminus of FLI1. Although the genetic basis of ESFT is fairly well understood, its putative cellular origin remains to be determined. Previous work has proposed that neural crest progenitor cells may be the causative cell type responsible for ESFT. However, surprisingly little is known about the expression pattern or role of either wild-type EWS or wild-type FLI1 in this cell population during early embryonic development. Using the developing chick embryo as a model system, we identified EWS expression in emigrating and migratory neural crest stem cells, whereas FLI1 transcripts were found to be absent in these populations and were restricted to developing endothelial cells. By ectopically expressing EWS-FLI1 or wild-type FLI1 in the developing embryo, we have been able to study the cellular transformations that ensue in the context of an in vivo model system. Our results reveal that misexpression of the chimeric EWS-FLI1 fusion gene, or wild-type FLI1, in the developing neural crest stem cell population leads to significant aberrations in neural crest development. An intriguing possibility is that misexpression of the EWS-FLI1 oncogene in neural crest-derived stem cells may be an initiating event in ESFT genesis.

Snail2 directly represses cadherin6B during epithelial-to-mesenchymal transitions of the neural crest.

The neural crest, a transient population of migratory cells, forms the craniofacial skeleton and peripheral nervous system, among other derivatives in vertebrate embryos. The transcriptional repressor Snail2 is thought to be crucial for the epithelial-to-mesenchymal transition (EMT) that promotes neural crest delamination from the neural tube; however, little is known about its downstream targets. To this end, we depleted avian Snail2 in the premigratory neural crest using morpholino antisense oligonucleotides and examined effects on potential targets by quantitative PCR. Several dorsal neural tube genes were upregulated by alleviating Snail2 repression; moreover, the cell adhesion molecule cadherin6B was derepressed within 30 minutes of blocking Snail2 translation. Examination of the chick cadherin6B genomic sequence reveals that the regulatory region contains three pairs of clustered E boxes, representing putative Snail2 binding sites. Furthermore, in vivo and in vitro biochemical analyses demonstrate that Snail2 directly binds to these sites and regulates cadherin6B transcription. These results are the first to describe a direct target of Snail2 repression in vivo and in the context of the EMT that characterizes neural crest development.

Abnormalities in neural crest cell migration in laminin alpha5 mutant mice.

Although numerous in vitro experiments suggest that extracellular matrix molecules like laminin can influence neural crest migration, little is known about their function in the embryo. Here, we show that laminin alpha5, a gene up-regulated during neural crest induction, is localized in regions of newly formed cranial and trunk neural folds and adjacent neural crest migratory pathways in a manner largely conserved between chick and mouse. In laminin alpha5 mutant mice, neural crest migratory streams appear expanded in width compared to wild type. Conversely, neural folds exposed to laminin alpha5 in vitro show a reduction by half in the number of migratory neural crest cells. During gangliogenesis, laminin alpha5 mutants exhibit defects in condensing cranial sensory and trunk sympathetic ganglia. However, ganglia apparently recover at later stages. These data suggest that the laminin alpha5 subunit functions as a cue that restricts neural crest cells, focusing their migratory pathways and condensation into ganglia. Thus, it is required for proper migration and timely differentiation of some neural crest populations.

A vertebrate crossveinless 2 homologue modulates BMP activity and neural crest cell migration.

Previous work has revealed that proteins that bind to bone morphogenetic proteins (BMPs) and inhibit their signalling have a crucial role in the spatial and temporal regulation of cell differentiation and cell migration by BMPs. We have identified a chick homologue of crossveinless 2, a Drosophila gene that was identified in genetic studies as a promoter of BMP-like signalling. Chick Cv-2 has a conserved structure of five cysteine-rich repeats similar to those found in several BMP antagonists, and a C-terminal Von Willebrand type D domain. Cv-2 is expressed in the chick embryo in a number of tissues at sites at which elevated BMP signalling is required. One such site of expression is premigratory neural crest, in which at trunk levels threshold levels of BMP activity are required to initiate cell migration. We show that, when overexpressed, Cv-2 can weakly antagonise BMP4 activity in Xenopus embryos, but that in other in vitro assays Cv-2 can increase the activity of co-expressed BMP4. Furthermore, we find that increased expression of Cv-2 causes premature onset of trunk neural crest cell migration in the chick embryo, indicative of Cv-2 acting to promote BMP activity at an endogenous site of expression. We therefore propose that BMP signalling is modulated both by antagonists and by Cv-2 that acts to elevate BMP activity.

Roles of erbB4, rhombomere-specific, and rhombomere-independent cues in maintaining neural crest-free zones in the embryonic head.

Within the developing vertebrate head, the migration of neural tube-derived neural crest cells (NCCs) through the cranial mesenchyme is patterned into three streams, with mesenchyme adjacent to rhombomeres (r)3 and r5 maintained NCC-free. The receptor tyrosine kinase erbB4 is expressed within r3 and r5 and is required to maintain the r3-adjacent NCC-free zone in mouse embryos. In this study, we demonstrate that the extent of r3 involvement in patterning mouse NCC migration is restricted to the same dorsolateral region regulated by erbB4. In chick embryos, we show that erbB4 signaling similarly maintains the r3-adjacent NCC-free zone. However, although r5 expresses erbB4, this is insufficient to maintain the r3-adjacent NCC-free zone in grafting experiments where r5 replaced r3, indicating that erbB4 requires additional factors at the A-P level of r3 to pattern NCC migration. Furthermore, we show that the r5-adjacent NCC-free zone is maintained independently of r5, but requires surface ectoderm. Finally, we demonstrate that avian cranial surface ectoderm is patterned molecularly, with dorsolateral surface ectoderm at the levels of r2/3 and r7 expressing the sulfatase QSulf1 in quail, or the orthologue CSulf1 in chick. Aberrant NCC migration into r3-adjacent mesenchyme correlated with more focused QSulf1 expression in r2/3 surface ectoderm.