The merger of vertically offset quasi-geostrophic vortices

We examine the critical merging distance between two equal-volume, equal-potential-vorticity quasi-geostrophic vortices. We focus on how this distance depends on the vertical offset between the two vortices, each having a unit mean height-to-width aspect ratio. The vertical direction is special in the quasi-geostrophic model (used to capture the leading-order dynamical features of stably stratified and rapidly rotating geophysical flows) since vertical advection is absent. Nevertheless vortex merger may still occur by horizontal advection. In this paper, we first investigate the equilibrium states for the two vortices as a function of their vertical and horizontal separation. We examine their basic properties together with their linear stability. These findings are next compared to numerical simulations of the nonlinear evolution of two spheres of potential vorticity. Three different regimes of interaction are identified, depending on the vertical offset. For a small offset, the interaction differs little from the case when the two vortices are horizontally aligned. On the other hand, when the vertical offset is comparable to the mean vortex radius, strong interaction occurs for greater horizontal gaps than in the horizontally aligned case, and therefore at significantly greater full separation distances. This perhaps surprising result is consistent with the linear stability analysis and appears to be a consequence of the anisotropy of the quasi-geostrophic equations. Finally, for large vertical offsets, vortex merger results in the formation of a metastable tilted dumbbell vortex.Publisher PDFPeer reviewe

Success for All in England: Results From the Third Year of a National Evaluation

This article reports the third-year findings of a longitudinal evaluation in England of Success for All (SFA), a comprehensive literacy program. Eighteen SFA schools across England and 18 control schools, matched on prior achievement and demographics, were included in this quasi-experimental study. The results of hierarchical linear modeling analysis reveal a statistically significant positive school-level effect for SFA schools compared with control schools on standardized reading measures of word-level and decoding skills, and there were directionally positive but nonsignificant school-level effects on measures of comprehension and fluency. Practical and policy implications of these findings are discussed, particularly as they relate to recent English government policies encouraging schools to implement research-proven approaches

Optimisation of the RT-PCR detection of immunomagnetically enriched carcinoma cells

BACKGROUND: Immunomagnetic enrichment followed by RT-PCR (immunobead RT-PCR) is an efficient methodology to identify disseminated carcinoma cells in the blood and bone marrow. The RT-PCR assays must be both specific for the tumor cells and sufficiently sensitive to enable detection of single tumor cells. We have developed a method to test RT-PCR assays for any cancer. This has been investigated using a panel of RT-PCR markers suitable for the detection of breast cancer cells. METHODS: In the assay, a single cell line-derived tumor cell is added to 100 peripheral blood mononuclear cells (PBMNCs) after which mRNA is isolated and reverse transcribed for RT-PCR analysis. PBMNCs without added tumor cells are used as specificity controls. The previously studied markers epidermal growth factor receptor (EGFR), mammaglobin 1 (MGB1), epithelial cell adhesion molecule (EpCAM/TACSTD1), mucin 1 (MUC1), carcinoembryonic antigen (CEA) were tested. Two new epithelial-specific markers ELF3 and EphB4 were also tested. RESULTS: MUC1 was unsuitable as strong amplification was detected in 100 cell PBMNC controls. Expression of ELF3, EphB4, EpCAM, EGFR, CEA and MGB1 was found to be both specific for the tumor cell, as demonstrated by the absence of a signal in most 100 cell PBMNC controls, and sensitive enough to detect a single tumor cell in 100 PBMNCs using a single round of RT-PCR. CONCLUSIONS: ELF3, EphB4, EpCAM, EGFR, CEA and MGB1 are appropriate RT-PCR markers for use in a marker panel to detect disseminated breast cancer cells after immunomagnetic enrichment

S.4.1 N-terminal pro-brain natriuretic peptide levels predict incident pulmonary arterial hypertension in SSc

Introduction. Pulmonary arterial hypertension (PAH) is a major cause of mortality in SSc. NT-proBNP may be a useful biomarker of prevalent PAH but its role in screening for incident PAH has not been evaluated. Methods. Patients recruited into the Australian Scleroderma Cohort Study undergo annual echocardiography, pulmonary function tests (PFTs), 6-min walk test (6MWT) and have serum NT-proBNP measured (ElecsysproBNP II). The diagnosis of PAH is based on Dana point criteria at right heart catheterization (RHC). Patients with LV dysfunction or eGFR 36 mmHg, (ii) FVC/DLCO% >1.6 and no significant ILD, (iii) DLCO 189.2 pg/ml had a likelihood ratio of 26.4 for presence of PAH (c-statistic = 0.9; sensitivity 85%; specificity 97%). An NT-proBNP level 189.2 pg/ml and <82.9 pg/ml defining patients with a high and low likelihood of PAH, respectively. Further prospective studies are required in unselected patients in order to confirm these finding

N-terminal pro-brain natriuretic peptide in a novel screening algorithm for pulmonary arterial hypertension in systemic sclerosis: a case-control study

INTRODUCTION: Pulmonary arterial hypertension is a major cause of mortality in systemic sclerosis. N-terminal probrain natriuretic peptide (NT-proBNP) has emerged as a candidate biomarker that may enable the early detection of systemic sclerosis-related pulmonary arterial hypertension (SSc-PAH). The objective of our study was to incorporate NT-proBNP into a screening algorithm for SSc-PAH that could potentially replace transthoracic echocardiography (TTE) as a more convenient and less costly “first tier” test. METHODS: NT-proBNP levels were measured in patients from four clinical groups: a group with right heart catheter (RHC)-diagnosed SSc-PAH before commencement of therapy for PAH; a group at high risk of SSc-PAH based on TTE; a group with interstitial lung disease; and systemic sclerosis (SSc) controls with no cardiopulmonary complications. NT-proBNP levels were compared by using ANOVA and correlated with other clinical variables by using simple and multiple linear regression. ROC curve analyses were performed to determine the optimal cut point for NT-proBNP and other clinical variables in prediction of PAH. RESULTS: NT-proBNP was highest in the PAH group compared with other groups (P < 0.0001), and higher in the risk group compared with controls (P < 0.0001). NT-proBNP was positively correlated with systolic pulmonary artery pressure (PAP) on TTE (P < 0.0001), and mean PAP (P = 0.013), pulmonary vascular resistance (P = 0.005), and mean right atrial pressure (P = 0.006) on RHC. A composite model wherein patients screened positive if NT-proBNP was ≥ 209.8 pg/ml, and/or DLCOcorr was < 70.3% with FVC/DLCOcorr ≥ 1.82, had a sensitivity of 100% and specificity of 77.8% for SSc-PAH. CONCLUSION: We have proposed a screening algorithm for SSc-PAH, incorporating NT-proBNP level and PFTs. This model has high sensitivity and specificity for SSc-PAH and, if positive, should lead to TTE and confirmatory testing for PAH. This screening algorithm must be validated prospectively.Vivek Thakkar, Wendy M. Stevens, David Prior, Owen A. Moore, Jillian Byron, Danny Liew, Karen Patterson, Pravin Hissaria, Janet Roddy, Jane Zochling, Joanne Sahhar, Peter Nash, Kathleen Tymms, David Celermajer, Eli Gabbay, Peter Youssef, Susanna M. Proudman and Mandana Nikpou

S.8.1 An immunochip-based interrogation of scleroderma susceptibility variants

Introduction. Understanding the genetic architecture of scleroderma (SSc) susceptibility is vital both in gene discovery and in determining the influence of previously identified susceptibility variants. It is particularly important in understanding disease mechanism in a disease with few therapies and great morbidity and mortality. Methods. We selected 557 cases from the Australian Scleroderma Cohort Study (ASCS), for genotyping with the Immunochip, a custom Illumina Infinium genotyping array containing 196 524 rare and common variants shown to be important in a wide variety of autoimmune disorders. A total of 4537 controls were taken from the 1958 British Birth cohort. Genotype data were analysed with PLINK. Samples and SNPs with low call rates were excluded, as were SNPs in Hardy-Weinberg disequilibrium or with less than two occurrences of the minor allele. Eigenstrat was used to analyse population structure. The final data set consisted of 505 cases, 4491 controls and 146 867 SNPs. Allelic association analyses were conducted using Fisher's exact test. Genotype clusters were manually examined for all associations of P < 10−5 since calling is difficult for some rare variants. Results. Significant and suggestive associations were detected at seven loci. Several of these have been previously implicated in scleroderma susceptibility (HLA-DRB1 and STAT4) and several are novel associations, including SNPs near PXK (P = 4.4 × 10−6) and CFDP1(P = 2.6 × 10−6). The strongest associations were with SNPs in the Class II region of the MHC. One of the most strongly associated SNPs [rs4639334; P = 1.6 × 10−8; odds ratio (OR) = 1.8] is in linkage disequilibrium (r2 = 0.46) with the Class II allele HLA-DRB1*11:01. This allele has been associated with SSc. Another strongly associated SNP is rs2857130 (P = 1.6 × 10−8; OR = 0.67), which lies in the promoter region of HLA-DRB1, but is not in LD with any classical MHC alleles. Outside the MHC, there were six regions of association with P < 10−5,including the confirmed SSc locus at STAT4. Several SNPs implicate a locus at PXK, which has been previously associated with SLE but not with SSc. The remaining associations are novel for both SSc and SLE and require replication. Of particular interest is a rare variant located within a non-coding RNA on chromosome 6q21 which was ∼20 times more frequent in cases than controls. We are currently dissecting the potential biological implications of this locus. Conclusions. This pilot study has confirmed previously reported SSc associations, revealed further genetic overlap between SSc and SLE, and identified putative novel SSc susceptibility loci including a rare allele with major effect siz

The Effect of a School-Based Intervention on Physical Activity and Well-Being: a Non-Randomised Controlled Trial with Children of Low Socio-Economic Status

Abstract Background Self-determination theory (SDT) has been used to predict children’s physical activity and well-being. However, few school-based SDT intervention studies have been conducted, and no research exists with children of low socio-economic status (SES). Therefore, SDT-derived needs-supportive teaching techniques informed the design and analyses of the Healthy Choices Programme (HCP). The aim was to determine if the HCP could enhance moderate-to-vigorous physical activity (MVPA) and well-being among children of low SES through increasing autonomy-support, needs satisfaction and intrinsic motivation. Method A mixed factorial two (group) × two (time) wait-list controlled trial was conducted and reported using the TREND guidelines. A total of 155 children (56% females; intervention n = 84, control n = 71) took part and completed measures at baseline (week 0) and post-intervention (week 11). The effect of the intervention on MVPA (model 1) and well-being (model 2) was tested through serial mediation models with three mediators (i.e. autonomy-support, needs satisfaction and intrinsic motivation). Results In comparison to the control group, the intervention was related to increases in MVPA (β = .45) and autonomy-support (β = .17). In model 1, analyses revealed partial mediation of the MVPA change through autonomy-support (β = .14), intrinsic motivation (β = .51) and all three SDT mediators in sequence (total r 2  = .34). In model 2, well-being was indirectly enhanced through autonomy-support (β = .38) and autonomy-support and needs satisfaction in sequence (total r 2  = .21). Conclusions The HCP enhanced MVPA and well-being by engendering a needs-supportive physical activity environment. The scientific and practical contribution of this study was the application of SDT in all aspects of the HCP intervention’s design and analyses. Practitioners may consider integrating SDT principles, as implemented in the HCP, for health promotion. Trial Registration This study is registered on Research Registry (number researchregistry2852)

Transformation induced by Ewing's sarcoma associated EWS/FLI-1 is suppressed by KRAB/FLI-1

Ewing's sarcoma is a childhood bone tumour with poor prognosis, most commonly associated with a t(11;22)(q24;q12) reciprocal translocation that fuses the EWS and FLI-1 genes, resulting in the production of an aberrant chimeric transcription factor EWS/FLI-1. To erucidate the mechanisms by which EWS/FLI-1 mediates transformation in mouse models, we have generated a murine Ews/Fli-1 fusion protein. We demonstrate that this protein transforms fibroblast celrs in vitro similar to human EWS/FLI-1 as demonstrated by serum and anchorage-independent growth, the formation of tumours in nude mice and elevation of the oncogenic marker c-myc. Furthermore, transformation of these cells was inhibited by a specific represser, KRAB/FLI-1. The KRAB/FLI-1 repressor also suppressed the tumorigenic phenotype of a human Ewing's sarcoma cell line. These findings suggest that the transformed phenotype of Ewing's sarcoma cells can be reversed by using the sequence-specific FLI-1-DNA-binding domain to target a gone repressor domain. The inhibition of EWS/FLI-1 is the first demonstration of the KRAB domain suppressing the action of an ETS factor. This approach provides potential avenues for the elucidation of the biological mechanisms of EWS/FLI-1 oncogenesis and the development of novel therapeutic strategies. © 2003 Cancer Research UK.link_to_subscribed_fulltex