Development of a Diagnostic Genetic Test for Simplex and Autosomal Recessive Retinitis Pigmentosa

PURPOSE: Retinitis pigmentosa (RP) causes hereditary blindness in adults (prevalence, approximately 1 in 4000). Each of the more than 30 causative genes identified to date are responsible for only a small percentage of cases. Genetic diagnosis via traditional methods is problematic, and a single test with a higher probability of detecting the causative mutation would be very beneficial for the clinician. The goal of this study therefore was to develop a high-throughput screen capable of detecting both known mutations and novel mutations within all genes implicated in autosomal recessive or simplex RP. DESIGN: Evaluation of diagnostic technology. PARTICIPANTS AND CONTROLS: Participants were 56 simplex and autosomal recessive RP patients, with 360 population controls unscreened for ophthalmic disease. METHODS: A custom genechip capable of resequencing all exons containing known mutations in 19 disease-associated genes was developed (RP genechip). A second, commercially available arrayed primer extension (APEX) system was used to screen 501 individual previously reported variants. The ability of these high-throughput approaches to identify pathogenic variants was assessed in a cohort of simplex and autosomal recessive RP patients. MAIN OUTCOME MEASURES: Number of mutations and potentially pathogenic variants identified. RESULTS: The RP genechip identified 44 sequence variants: 5 previously reported mutations; 22 known single nucleotide polymorphisms (SNPs); 11 novel, potentially pathogenic variants; and 6 novel SNPs. There was strong concordance with the APEX array, but only the RP genechip detected novel variants. For example, identification of a novel mutation in CRB1 revealed a patient, who also had a single previously known CRB1 mutation, to be a compound heterozygote. In some individuals, potentially pathogenic variants were discovered in more than one gene, consistent with the existence of disease modifier effects resulting from mutations at a second locus. CONCLUSIONS: The RP genechip provides the significant advantage of detecting novel variants and could be expected to detect at least one pathogenic variant in more than 50% of patients. The APEX array provides a reliable method to detect known pathogenic variants in autosomal recessive RP and simplex RP patients and is commercially available. High-throughput genotyping for RP is evolving into a clinically useful genetic diagnostic tool.

Impaired Immune Tolerance to Porphyromonas gingivalis Lipopolysaccharide Promotes Neutrophil Migration and Decreased Apoptosis.

Periodontitis, a chronic inflammatory disease of the tissues supporting the teeth, is characterized by an exaggerated host immune and inflammatory response to periopathogenic bacteria. Toll-like receptor activation, cytokine network induction, and accumulation of neutrophils at the site of inflammation are important in the host defense against infection. At the same time, induction of immune tolerance and the clearance of neutrophils from the site of infection are essential in the control of the immune response, resolution of inflammation, and prevention of tissue destruction. Using a human monocytic cell line, we demonstrate that Porphyromonas gingivalis lipopolysaccharide (LPS), which is a major etiological factor in periodontal disease, induces only partial immune tolerance, with continued high production of interleukin-8 (IL-8) but diminished secretion of tumor necrosis factor alpha (TNF-) after repeated challenge. This cytokine response has functional consequences for other immune cells involved in the response to infection. Primary human neutrophils incubated with P. gingivalis LPS-treated naïve monocyte supernatant displayed a high migration index and increased apoptosis. In contrast, neutrophils treated with P. gingivalis LPS-tolerized monocyte supernatant showed a high migration index but significantly decreased apoptosis. Overall, these findings suggest that induction of an imbalanced immune tolerance in monocytes by P. gingivalis LPS, which favors continued secretion of IL-8 but decreased TNF- production, may be associated with enhanced migration of neutrophils to the site of infection but also with decreased apoptosis and may play a role in the chronic inflammatory state seen in periodontal disease.

Local, European and global: An exploration of migration patterns of social workers into Ireland

Whilst the project to increase workforce mobility is part of a common labour force policy across the European Union, for some social workers, it has also been coupled with an aspiration to develop a pan-European identity within the profession (Lorenz, 1994, 2000; Frost, 2008). In this article, taking the island of Ireland as an example, we examine empirical data on the movement of social workers in recent years, both within Ireland and inward from outside the island, and consider the challenges and opportunities this has presented for the profession, also drawing on the British experience. From this analysis, some tentative conclusions are drawn about what is happening, what is possible and what is desirable in balancing aspirations for increased mobility within the European Union and a pan-European social work identity against the needs and interests of local, European and global communities.

Getting off the escalator? A study of Scots out-migration from a global city region

Something new is happening to reverse the historical trend of skilled Scots moving to London for career progression. The Scottish population of London and the South East is falling and this despite Scots enjoying continued occupational success within the South East labour market. The authors ask why Scots are leaving the UK's main escalator region and then investigate how these migration changes can best be theorised relative to literature on the mobility of the 'new service class'. Building on Fielding's escalator region hypothesis, the authors report on recent research on longer distance flows out of the UK's main escalator region. They advance the critique of the escalator region hypothesis set out by Findlay et al and ask why people would leave a global city offering good opportunities for occupational mobility. Demographic regime change provides only a partial answer. Other explanations can be found in the changing mobilities of the new service class as they engage in what Smith has defined as 'translocal' and 'transnational' urbanism. The authors argue that Scotland's changing relationship with London and the South East may be representative of a wider set of changes in migration linkages between regional economies and global cities.

Panel Stationarity Test with Structural Breaks

In this paper, we extend the heterogeneous panel data stationarity test of Hadri [Econometrics Journal, Vol. 3 (2000) pp. 148–161] to the cases where breaks are taken into account. Four models with different patterns of breaks under the null hypothesis are specified. Two of the models have been already proposed by Carrion-i-Silvestre et al.[Econometrics Journal,Vol. 8 (2005) pp. 159–175]. The moments of the statistics corresponding to the four models are derived in closed form via characteristic functions.We also provide the exact moments of a modified statistic that do not asymptotically depend on the location of the break point under the null hypothesis. The cases where the break point is unknown are also considered. For the model with breaks in the level and no time trend and for the model with breaks in the level and in the time trend, Carrion-i-Silvestre et al. [Econometrics Journal, Vol. 8 (2005) pp. 159–175]showed that the number of breaks and their positions may be allowed to differ acrossindividuals for cases with known and unknown breaks. Their results can easily be extended to the proposed modified statistic. The asymptotic distributions of all the statistics proposed are derived under the null hypothesis and are shown to be normally distributed. We show by simulations that our suggested tests have in general good performance in finite samples except the modified test. In an empirical application to the consumer prices of 22 OECD countries during the period from 1953 to 2003, we found evidence of stationarity once a structural break and cross-sectional dependence are accommodated.

PANEL DATA UNIT ROOT TEST WITH FIXED TIME DIMENSION

The consideration of the limit theory in which T is fixed and N is allowed to go to infinity improves the finite-sample properties of the tests and avoids the imposition of the relative rates at which T and N go to infinity.

Immunobiosensor detection of domoic acid as a screening test in bivalve molluscs: Comparison with liquid chromatography-based analysis

A rapid and sensitive immuno-based screening method was developed to detect domoic acid (DA) present in extracts of shellfish species using a surface plasmon resonance-based optical biosensor. A rabbit polyclonal antibody raised against DA was mixed with standard or sample extracts and allowed to interact with DA immobilized onto a sensor chip surface. The characterization of the antibody strongly suggested high cross-reactivity with DA and important isomers of the toxin. The binding of this antibody to the sensor chip surface was inhibited in the presence of DA in either standard solutions or sample extracts. The DA chip surface proved to be highly stable, achieving approximately 800 analyses per chip without any loss of surface activity. A single analytical cycle (sample injection, chip regeneration, and system wash) took 10 min to complete. Sample analysis (scallops, mussels, cockles, oysters) was achieved by simple extraction with methanol. These extracts were then filtered and diluted before analysis. Detection limits in the ng/g range were achieved by the assay; however, the assay parameters chosen allowed the test to be performed most accurately at the European Union's official action limit for DA of 20 mu g/g. At this concentration, intra- and interassay variations were measured for a range of shellfish species and ranged from 4.5 to 7.4% and 2.3 to 9.7%, respectively.

Computer simulations of seasonal outbreak and diurnal vertical migration of cyanobacteria

Algal blooms caused by cyanobacteria are characterized by two features with different time scales: one is seasonal outbreak and collapse of a bloom and the other is diurnal vertical migration. Our two-component mathematical model can simulate both phenomena, in which the state variables are nutrients and cyanobacteria. The model is a set of one-dimensional reaction-advection-diffusion equations, and temporal changes of these two variables are regulated by the following five factors: (1) annual variation of light intensity, (2) diurnal variation of light intensity, (3) annual variation of water temperature, (4) thermal stratification within a water column and (5) the buoyancy regulation mechanism. The seasonal change of cyanobacteria biomass is mainly controlled by factors, (1), (3) and (4), among which annual variations of light intensity and water temperature directly affect the maximum growth rate of cyanobacteria. The latter also contributes to formation of the thermocline during the summer season. Thermal stratification causes a reduction in vertical diffusion and largely prevents mixing of both nutrients and cyanobacteria between the epilimnion and the hypolimnion. Meanwhile, the other two factors, (2) and (5), play a significant role in diurnal vertical migration of cyanobacteria. A key mechanism of vertical migration is buoyancy regulation due to gas-vesicle synthesis and ballast formation, by which a quick reversal between floating and sinking becomes possible within a water column. The mechanism of bloom formation controlled by these five factors is integrated into the one-dimensional model consisting of two reaction-advection-diffusion equations.

First records of oceanic dive profiles for leatherback turtles, Dermochelys coriacea, indicate behavioural plasticity associated with long-distance migration

We used Satellite Relay Data Loggers to obtain the first dive profiles for critically endangered leatherback turtles outside the nesting season. As individuals moved from the Caribbean out into the Atlantic, key aspects of their diving behaviour changed markedly, in line with theoretical predictions for how dive duration should vary with foraging success. In particular, in the Atlantic, where foraging success is expected to be higher, dives became much longer than in the Caribbean. The deepest-ever dive profile recorded for a reptile was obtained in the oceanic Atlantic, with a 54-min dive to 626 m on 26 August 2002. However, dives were typically much shallower (generally