Expression and function of beta1 integrins on human eosinophils

Eosinophils preferentially accumulate at sites of chronic allergic diseases such as bronchial asthma. The mechanisms by which selective eosinophil migration occurs are not fully understood. However, interactions of cell-surface adhesion molecules on the eosinophil with molecular counterligands on endothelial and epithelial cells, and on extracellular matrix proteins, are likely to be critical during the recruitment process. One possible mechanism for selective eosinophil recruitment involves the alpha4beta 1 (VLA-4) integrin which is not expressed on neutrophils. Correlations have been found between infiltration of eosinophils and endothelial expression of VCAM-1, the ligand for VLA-4, in the lungs of asthmatic individuals as well as in late phase reactions in the lungs, nose and skin. Epithelial and endothelial cells respond to the Th2-type cytokines IL-4 and IL-13 with selective de novo expression of VCAM-1, consistent with the possible role of VCAM-1/VLA-4 interactions in eosinophil influx during allergic inflammation. Both beta 1 and beta 2 integrins on eosinophils exist in a state of partial activation. For example, eosinophils can be maximally activated for adhesion to VCAM-1 or fibronectin after exposure to beta 1 integrin-activating antibodies or divalent cations, conditions that do not necessarily affect the total cell surface expression of beta 1 integrins. In contrast, cytokines like IL-5 prevent beta 1 integrin activation while promoting beta 2 integrin function. Furthermore, ligation of integrins can regulate the effector functions of the cell. For example, eosinophil adhesion via beta 1 and/or beta 2 integrins has been shown to alter a variety of functional responses including degranulation and apoptosis. Thus, integrins appear to be important in mediating eosinophil migration and activation in allergic inflammation. Strategies that interfere with these processes may prove to be useful for treatment of allergic diseases.

EGFR signalling as a negative regulator of Notch1 gene transcription and function in proliferating keratinocytes and cancer.

The Notch1 gene has an important role in mammalian cell-fate decision and tumorigenesis. Upstream control mechanisms for transcription of this gene are still poorly understood. In a chemical genetics screen for small molecule activators of Notch signalling, we identified epidermal growth factor receptor (EGFR) as a key negative regulator of Notch1 gene expression in primary human keratinocytes, intact epidermis and skin squamous cell carcinomas (SCCs). The underlying mechanism for negative control of the Notch1 gene in human cells, as well as in a mouse model of EGFR-dependent skin carcinogenesis, involves transcriptional suppression of p53 by the EGFR effector c-Jun. Suppression of Notch signalling in cancer cells counteracts the differentiation-inducing effects of EGFR inhibitors while, at the same time, synergizing with these compounds in induction of apoptosis. Thus, our data reveal a key role of EGFR signalling in the negative regulation of Notch1 gene transcription, of potential relevance for combinatory approaches for cancer therapy.

Systematics and Population Level Analysis of Anopheles darlingi

A new phylogenetic analysis of the Nyssorhynchus subgenus (Danoff-Burg and Conn, unpub. data) using six data sets {morphological (all life stages); scanning electron micrographs of eggs; nuclear ITS2 sequences; mitochondrial COII, ND2 and ND6 sequences} revealed different topologies when each data set was analyzed separately but no heterogeneity between the data sets using the arn test. Consequently, the most accurate estimate of the phylogeny was obtained when all the data were combined. This new phylogeny supports a monophyletic Nyssorhynchus subgenus but both previously recognized sections in the subgenus (Albimanus and Argyritarsis) were demonstrated to be paraphyletic relative to each other and four of the seven clades included species previously placed in both sections. One of these clades includes both Anopheles darlingi and An. albimanus, suggesting that the ability to vector malaria effectively may have originated once in this subgenus. Both a conserved (315 bp) and a variable (425 bp) region of the mitochondrial COI gene from 15 populations of An. darlingi from Belize, Bolivia, Brazil, French Guiana, Peru and Venezuela were used to examine the evolutionary history of this species and to test several analytical assumptions. Results demonstrated (1) parsimony analysis is equally informative compared to distance analysis using NJ; (2) clades or clusters are more strongly supported when these two regions are combined compared to either region separately; (3) evidence (in the form of remnants of older haplotype lineages) for two colonization events; and (4) significant genetic divergence within the population from Peixoto de Azevedo (State of Mato Grosso, Brazil). The oldest lineage includes populations from Peixoto, Boa Vista (State of Roraima) and Dourado (State of São Paulo).

Orthogonal higher order structure and confirmatory factor analysis of the French Wechsler Adult Intelligence Scale (WAIS-III).

According to the most widely accepted Cattell-Horn-Carroll (CHC) model of intelligence measurement, each subtest score of the Wechsler Intelligence Scale for Adults (3rd ed.; WAIS-III) should reflect both 1st- and 2nd-order factors (i.e., 4 or 5 broad abilities and 1 general factor). To disentangle the contribution of each factor, we applied a Schmid-Leiman orthogonalization transformation (SLT) to the standardization data published in the French technical manual for the WAIS-III. Results showed that the general factor accounted for 63% of the common variance and that the specific contributions of the 1st-order factors were weak (4.7%-15.9%). We also addressed this issue by using confirmatory factor analysis. Results indicated that the bifactor model (with 1st-order group and general factors) better fit the data than did the traditional higher order structure. Models based on the CHC framework were also tested. Results indicated that a higher order CHC model showed a better fit than did the classical 4-factor model; however, the WAIS bifactor structure was the most adequate. We recommend that users do not discount the Full Scale IQ when interpreting the index scores of the WAIS-III because the general factor accounts for the bulk of the common variance in the French WAIS-III. The 4 index scores cannot be considered to reflect only broad ability because they include a strong contribution of the general factor.

Roles of canonical Wnt/TCF-1 signaling for hematopoiesis, lymphocyte development and function

Summary : The canonical Wnt signaling pathway plays key roles in the maintenance of self-renewing tissues, like the gut or the skin. In contrast, the role of this pathway in hematopoiesis remains poorly defined. Wnt ligands transmit signals through ß-catenin which activates gene transcription upon its association with Lymphoid Cell Enhancer/T Cell Factor (LEF/TCF). Currently, v-catenin is the only alternative factor known to transduce canonical Wnt signals. The ß-/γ-catenin bindiná domain in TCF-1 is required to partly rescue thymopoiesis and NK cell development in TCF-1-deficient mice. However, T cell development and hematopoiesis w-as normal in mice deficient of ß-catenin, or of γ-catenin. Surprisingly we found that hematopoiesis and thymopoiesis was also normal in the combined absence of ß- and γ-catenin. Reporter assays showed that double-deficient lymphocytes were still able to transduce canonical wnt signals. These data provided evidence that hematopoietic cells can transduce canonical Wnt signals in the combined absence of ß- and γ-catenin. There exist numerous TCF-1 isoforrns including those that harbor the N-terminal ß-/y-catenin binding domain or that contains a C-terminal CRARF domain whose role in vivo has not been previously tested. We found that the CRARF domain influences lymphocyte development in conjunction with the N-treminal ß-/γ-catenin binding. The presence of the two domains directs thymocytes to the CD8+ T cell lineage whereas NK cell development is abolished. Roles of the canonical Wnt/TCF-1 pathway for lymphocyte function have not been defined. We demonstrate that TCF-1 deficient CDBT T cells mount a normal primary response to viral infection but these T cells fail to expand upon restimulation. The failure of CD8+ T cells to respond to IL-2 during primary infection seems to account for this phenotype. Thus, TCF-1 is essential for programming functional CD8+ T cell memory. Collectively, these data provide significant new insights into the role of Wnt/TCF-1 pathway for lymphocyte development and function and suggest a novel mechanism of Wnt signal transuction in hematopoietic cells. Résumé : La voie de signalisation canonique Wnt joue un rôle prépondérant dans le renouvellement de tissus, comme l'intestin ou la peau. Son rôle dans l'hématopoïèse est quant à lui mal défini. Le ligand Wnt transmet le signal via la ß-catenin qui active la transcription de gènes cibles quand il est associé avec Lymphoid Cell Enhancer,~T Cell Factor (LEF/TCF). Actuellement, la γ-catenin est le seul autre facteur connu pouvant se substituer à la fonction de la ß-catenin. Un variant de TCF-1 contenant le domaine liant ß-/,~-catenin est capable de restaurer le développement des lymphocytes T et NK en l'absence de TCF-1. Cependant la thymopoïèse et l'hématopoïèse sont normales dans les souris déficientes pour la ß-catenin ou la γ-catenin. De façon surprenante, nous avons trouvé que l'hématopoïèse et le développement des lymphocytes sont normaux lors de l'absence combinée de ß-/γ-catenin. De plus, la transduction des signaux de la voie de signalisation Wnt est maintenue dans des lymphocytes déficients pour ß-/γ-catenin. Ces résultats démontrent que les cellules hématopoïétiques peuvent transmettre les signaux de la voie canonique Wnt lors de l'absence combinée de la ß et la γ -catenin. Il existe de nombreuses isofonnes de TCF-1, y compris certaines qui comprennent un domaine qui lie ß-/γ-catenin du côté N-terminus ou qui contiennent un domaine CRARF du côté C-terminus. Nous montrons ici que le domaine CRARF influence le développement des lymphocytes en conjonction avec le domaine liant ß-/γ-catenin. La présence des deux domaines dirige les thymocytes vers la lignée de cellules T CD8, alors que le développement des cellules NK est aboli. Au-delà de sa fonction sur le développement des lymphocytes, le rôle de la soie de signalisation canonique Wnt/TCF-1 lors d'une infection n'a pas été défini. Nous avons montré que les cellules T CD8, déficientes pour TCF-1, développent une réponse primaire normale à une infection virale, mais qu'elles ne s'accumulent pas après restimulation. L'incapacité des cellules TCD8 à répondre à l'IL-2 durant la réponse primaire peut expliquer ce phénotype. Ainsi; TCF-1 est essentiel pour la programmation de cellules T CD8 mémoires fonctionnelles. L'ensemble de ces résultats fournit de nouveaux aperçus du rôle de la voie de signalisation Wnt/TCF-1 pour le développement et la fonction des lymphocytes et suggèrent un nouveau mécanisme de transduction du signal Wnt dans les cellules hématopoïétiques.

Consequences of sleep deprivation on neurotransmitter receptor expression and function.

Several pieces of evidence suggest that sleep deprivation causes marked alterations in neurotransmitter receptor function in diverse neuronal cell types. To date, this has been studied mainly in wake- and sleep-promoting areas of the brain and in the hippocampus, which is implicated in learning and memory. This article reviews findings linking sleep deprivation to modifications in neurotransmitter receptor function, including changes in receptor subunit expression, ligand affinity and signal transduction mechanisms. We focus on studies using sleep deprivation procedures that control for side-effects such as stress. We classify the changes with respect to their functional consequences on the activity of wake-promoting and/or sleep-promoting systems. We suggest that elucidation of how sleep deprivation affects neurotransmitter receptor function will provide functional insight into the detrimental effects of sleep loss.

Characterization of Sm14 related components in different helminths by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis

Sm14 was the first fatty acid-binding protein homologue identified in helminths. Thereafter, members of the same family were identified in several helminth species, with high aminoacid sequence homology between them. In addition, immune crossprotection was also reported against Fasciola hepatica infection, in animals previously immunized with the Schistosoma mansoni vaccine candidate, r-Sm14. In the present study, data on preliminary sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis of nine different helminth extracts focusing the identification of Sm14 related proteins, is reported. Out of these, three extracts - Ascaris suum (males and females), Echinostoma paraensei, and Taenia saginata - presented components that comigrated with Sm14 in SDS-PAGE, and that were recognized by anti-rSm14 policlonal serum, in Western blotting tests.

Strategic Review of Medical Training and Career Structure Interim Report

Click here to download Strategic Review of Medical Training and Career Structure Interim Report PDF 44kb Click here to download Strategic Review of Medical Training and Career Structure Terms of Reference PDF 59KB

Strategic Review of Medical Training and Career Structures Report on Medical Career Structures and Pathways following completion of Specialist Training

The Minister for Health decided, in July 2013, to establish a Working Group, chaired by Professor Brian MacCraith, President of DCU, to carry out a strategic review of medical training and career structure. The Working Group will examine and make high-level recommendations relating to training and career pathways for doctors with a view to: From January-April 2014, the Working Group prioritised work on career structures and pathways following completion of specialist training in order to report to the Minister for Health on these issues in this report. Download the Report (PDF, 800 kb)  

Strategic Review of Medical Training and Career Structure Final Report

  Final report of the Strategic Review Working Group chaired by Professor Brian MacCraith (President, DCU) This final report focuses on issues relating to strategic medical workforce planning and career planning and mentoring supports for trainee doctors and makes recommendations. It also addresses specific issues in relation to the specialties of public health medicine, general practice and the community-based aspects of psychiatry.   Download the report here.  

Disorders of pupillary structure and function.

Neurologists are frequently consulted because of a pupillary abnormality. An unequal size of the pupils, an unusual shape, white colored pupils, or a poorly reactive pupil are common reasons for referral. A directed history and careful observation of the iris and pupil movements can bear out ocular pathology such as congenital or structural anomalies as the cause of abnormal pupils. Thereafter, it is important to evaluate the neurologic causes of anisocoria and poor pupil function. The first part of this article emphasizes pupillary abnormalities frequently encountered in infants and children and discusses some of the more common acquired iris structural defects. The second part focuses on evaluation of lesions in the neural pathways that result in pupillary dysfunction, with particular attention to those conditions having neurologic, systemic, or visual implications.

Nitric oxide: a major determinant of mast cell phenotype and function

Mast cells (MC) are important in the numerous physiological processes of homeostasis and disease. Most notably, MC are critical effectors in the development and exacerbation of allergic disorders. Nitric oxide (NO) is a diatomic radical produced by nitric oxide synthase (NOS), and has pluripotent cell signaling and cytotoxic properties. NO can influence many MC functions. Recent evidence shows the source of this NO can be from the mast cell itself. Governing the production of this endogenous NO, through alterations in the expression of tetrahydrobiopterin (BH4), a NOS cofactor, has stabilizing effects on MC degranulation. Furthermore, NO regulates the synthesis and secretion of de novo generated mediators, including leukotrienes and chemokines. These novel observations add to the growing body of knowledge surrounding the role of NO in the MC.

Mechanisms of leukocyte lipid body formation and function in inflammation

An area of increasingly interest for the understanding of cell signaling are the spatio-temporal aspects of the different enzymes involved in lipid mediator generation (eicosanoid-forming enzymes, phospholipases and their regulatory kinases and phosphatases) and pools of lipid precursors. The compartmentalization of signaling components within discrete and dynamic sites in the cell is critical for specificity and efficiency of enzymatic reactions of phosphorilation, enzyme activation and function. We hypothesized that lipid bodies - inducible non-membrane bound cytoplasmic lipid domains - function as specialized intracellular sites of compartmentalization of signaling with major roles in lipid mediator formation within leukocytes engaged in inflammatory process. Over the past years substantial progresses have been made demonstrating that all enzymes involved in eicosanoid synthesis localize at lipid bodies and lipid bodies are distinct sites for eicosanoid generation. Here we will review our current knowledge on the mechanisms of formation and functions of lipid bodies pertinent to inflammation.

Unraveling the complex network of cuticular structure and function.

A hydrophobic cuticle is deposited at the outermost extracellular matrix of the epidermis in primary tissues of terrestrial plants. Besides forming a protective shield against the environment, the cuticle is potentially involved in several developmental processes during plant growth. A high degree of variation in cuticle composition and structure exists between different plant species and tissues. Lots of progress has been made recently in understanding the different steps of biosynthesis, transport, and deposition of cuticular components. However, the molecular mechanisms that underlie cuticular function remain largely elusive.