The worldwide expansion of the Argentine ant

Aim The aim of this study was to determine the number of successful establishments of the invasive Argentine ant outside native range and to see whether introduced supercolonies have resulted from single or multiple introductions. We also compared the genetic diversity of native versus introduced supercolonies to assess the size of the propagules (i.e. the number of founding individuals) at the origin of the introduced supercolonies. Location Global. Methods We used mitochondrial DNA (mtDNA) markers and microsatellite loci to study 39 supercolonies of the Argentine ant Linepithema humile covering both the native (n = 25) and introduced range (n = 14). Results Data from three mitochondrial genes and 13 nuclear microsatellites suggest that the introduced supercolonies studied originated from at least seven founding events out of the native area in Argentina (primary introductions). The distribution of mtDNA haplotypes also suggests that supercolonies in the introduced range each derive from a single source supercolony and that one of these source supercolonies has been particularly successful, being the basis of many introduced populations spread across the world. Comparison of the genetic diversity of supercolonies based on the five most diverse loci also revealed that native and introduced supercolonies have greatly overlapping ranges of diversity, although the genetic diversity is on average less in introduced than in native supercolonies. Main conclusions Both primary introductions (from the native range) and secondary introductions (from sites with established invasive supercolonies) were important in the global expansion of the Argentine ant. In combination with the similar social organization of colonies in the native and introduced range, this indicates that invasiveness did not evolve recently as a unique and historically contingent event (e.g. reduction of genetic diversity) in this species. Rather, native L. humile supercolonies have characteristics that make them pre-adapted to invade new - and in particular disturbed - habitats when given the opportunity. These results have important implications with regard to possible strategies to be used to control invasive ants.

Luc-Actes: une unité à construire

(Résumé de l'ouvrage) This volume contains the papers presented at the 47th Colloquium Biblicum Lovaniense (Leuven, 1998). The general theme of the meeting was the unity of the Gospel of Luke and the Acts of the Apostles. Main papers on this topic were read by R.L. Brawley, J. Delobel, A. Denaux, J.A. Fitzmeyer, F.W. Horn, J. Kremer, A. Lindemann, O. Mainville, D. Marguerat, F. Neirynck, W. Radl, M. Rese, J. Taylor, C.M. Tuckett, and J. Verheyden. While a large majority of scholars agree that Luke intended his work to cover both the past and the continuing history of Jesus (Gospel and Acts), the essays also illustrate the complexities of this view on the unity of Luke-Acts when it comes to interpret the various aspects of Lukan theology, christology, pneumatology, and ecclesiology, the expansion of the Church in light of its Jewish origins, the genre of Luke-Acts, and the literary and stylistic means Luke used to make his work a unity. In total the volume includes some 40 papers, of which 24 are offered papers: L. Alexander, H. Baarlink, M. Bachmann, D. Bechard, T.L. Brodie, G.P. Carras, A. del Agua, C. Focant, G. Geiger, B.J. Koet, V. Koperski, D.P. Moessner, G. Oegema, J. Pichler, E. Plümacher, A. Puig i Tarrèch, U. Schmid, B. Schwank, N. Taylor, P.J. Tomson, S. Van den Eynde, S. Walton, G. Wasserberg, F. Wilk. This collection is an invaluable contribution to current discussions in Lukan study and to a nuanced understanding of the relationship between Luke's two volumes.

Compensatory β-cell mass expansion: a big role for a tiny actor.

Comment on: Jacovetti C, et al. J Clin Invest 2012; 122:3541-51.

Tumor antigen-specific FOXP3+ CD4 T cells identified in human metastatic melanoma: peptide vaccination results in selective expansion of Th1-like counterparts.

We have previously shown that vaccination of HLA-A2 metastatic melanoma patients with the analogue Melan-A(26-35(A27L)) peptide emulsified in a mineral oil induces ex vivo detectable specific CD8 T cells. These are further enhanced when a TLR9 agonist is codelivered in the same vaccine formulation. Interestingly, the same peptide can be efficiently recognized by HLA-DQ6-restricted CD4 T cells. We used HLA-DQ6 multimers to assess the specific CD4 T-cell response in both healthy individuals and melanoma patients. We report that the majority of melanoma patients carry high frequencies of naturally circulating HLA-DQ6-restricted Melan-A-specific CD4 T cells, a high proportion of which express FOXP3 and proliferate poorly in response to the cognate peptide. Upon vaccination, the relative frequency of multimer+ CD4 T cells did not change significantly. In contrast, we found a marked shift to FOXP3-negative CD4 T cells, accompanied by robust CD4 T-cell proliferation upon in vitro stimulation with cognate peptide. A concomitant reduction in TCR diversity was also observed. This is the first report on direct ex vivo identification of antigen-specific FOXP3+ T cells by multimer labeling in cancer patients and on the direct assessment of the impact of peptide vaccination on immunoregulatory T cells.

Analysis of a finite volume element method for the Stokes problem

In this paper we propose a stabilized conforming finite volume element method for the Stokes equations. On stating the convergence of the method, optimal a priori error estimates in different norms are obtained by establishing the adequate connection between the finite volume and stabilized finite element formulations. A superconvergence result is also derived by using a postprocessing projection method. In particular, the stabilization of the continuous lowest equal order pair finite volume element discretization is achieved by enriching the velocity space with local functions that do not necessarily vanish on the element boundaries. Finally, some numerical experiments that confirm the predicted behavior of the method are provided.

Optimum in vitro expansion of human antigen-specific CD8 T cells for adoptive transfer therapy.

Increasing evidence suggests that adoptive transfer of antigen-specific CD8(+) T cells could represent an effective strategy in the fight against chronic viral infections and malignancies such as melanoma. None the less, a major limitation in the implementation of such therapy resides in the difficulties associated with achieving rapid and efficient expansion of functional T cells in culture necessary to obtain the large numbers required for intravenous infusion. Recently, the critical role of the cytokines interleukin (IL)-2, IL-7 and IL-15 in driving T cell proliferation has been emphasized, thus suggesting their use in the optimization of expansion protocols. We have used major histocompatibility complex (MHC) class I/peptide multimers to monitor the expansion of antigen-specific CD8 T lymphocytes from whole blood, exploring the effect of antigenic peptide dose, IL-2, IL-7 and IL-15 concentrations on the magnitude and functional characteristics of the antigen-specific CD8(+) T cells generated. We show here that significant expansions of antigen-specific T cells, up to 50% of the CD8(+) T cell population, can be obtained after a single round of antigen/cytokine (IL-2 or IL-15) stimulation, and that these cells display good cytolytic and interferon (IFN)-gamma secretion capabilities. Our results provide an important basis for the rapid in vitro expansion of autologous T cells from the circulating lymphocyte pool using a simple procedure, which is necessary for the development of adoptive transfer therapies.

Expansion of intraocular gas bubbles due to altitude: do meteorological factors play a role?

BACKGROUND: Intraocular gas bubbles expand as patients move up to higher altitude. This may cause an acute intraocular pressure (IOP) rise with associated vascular obstructions and visual loss. MATERIALS AND METHODS: Two pseudophakic patients underwent a pars plana vitrectomy and 23% SF6 gas tamponade for a pseudophakic retinal detachment. During the immediate post-operative phase, the patients travelled daily up to their domicile, which was situated approximately 600 m higher than the level where they had been operated on. These travels were always without any pain or visual loss. However 1 week after surgery both patients developed severe ocular pain, and one patient had complete temporary loss of vision after ascending to altitude levels, which had previously presented no problem. Both episodes occurred in parallel with a change in barometric pressure. RESULTS: Treatment with acetazolamide reduced the increased IOP to normal levels, and visual acuity recovered. CONCLUSIONS: Although the post-operative size of an intraocular gas bubble decreases progressively over time, problems with bubble expansion may still occur even at a late stage if meteorological factors, that may increase the bubble size, change.

Volumetric quantification of atherosclerotic plaque in CT considering partial volume effect.

Coronary artery calcification (CAC) is quantified based on a computed tomography (CT) scan image. A calcified region is identified. Modified expectation maximization (MEM) of a statistical model for the calcified and background material is used to estimate the partial calcium content of the voxels. The algorithm limits the region over which MEM is performed. By using MEM, the statistical properties of the model are iteratively updated based on the calculated resultant calcium distribution from the previous iteration. The estimated statistical properties are used to generate a map of the partial calcium content in the calcified region. The volume of calcium in the calcified region is determined based on the map. The experimental results on a cardiac phantom, scanned 90 times using 15 different protocols, demonstrate that the proposed method is less sensitive to partial volume effect and noise, with average error of 9.5% (standard deviation (SD) of 5-7mm(3)) compared with 67% (SD of 3-20mm(3)) for conventional techniques. The high reproducibility of the proposed method for 35 patients, scanned twice using the same protocol at a minimum interval of 10 min, shows that the method provides 2-3 times lower interscan variation than conventional techniques.

Da Bisanzio alla Santa Russia : Nikodim Kondakov (1844-1925) e la nascita della storia dell'arte in Russia : con la traduzione del primo volume dell' "Ikonografija Bogomateri"

Da Bisanzio alla Santa Russia Résumé Ivan Foletti Le texte du premier volume de YIkonografija Bogomatri (Iconographie de la mère de Dieu), publié en 1914 à Saint Pétersbourg par Nikodim Kondakov et traduit dans le cadre de ce travail, soulève chez le lecteur contemporain de nombreuses questions quant au développement des études byzantines, entre la fin du XIXe et le début du XXe siècle. Il s'agit, avant tout, de comprendre les enjeux fondamentaux de la naissance de cette discipline, dans le cadre de l'Europe romantique et plus particulièrement de son acculturation à la réalité russe. En se concentrant sur le personnage de Nikodim Kondakov, considéré par ses contemporains comme le patriarche des études byzantines, ce travail propose d'articuler la réflexion autour de deux axes principaux. Il s'agit d'une part de la relation entre histoire de l'art et société : dans le contexte russe et plus largement dans celui de l'Europe, la recherche semble se développer en étroite relation avec les tendances politiques et sociales de ces années. C'est probablement la raison du choix pour Nikodim Kondakov de se dédier aux études de Byzance, dans les années où la Russie prépare sa guerre contre la Turquie (1877-1878), tandis que l'opinion publique est martelée avec un revival de l'ancienne idéologie de Moscou comme « troisième Rome » et héritière de Byzance. Un autre aspect significatif est la décision de ce même chercheur d'étudier les antiquités russes sous le règne de Alexandre III, le tzar « contre-réformateur », quand la Russie se replie sur elle même autour de trois mots d'ordre: Orthodoxie, autocratie, et nationalité. D'autre part, la réception de Kondakov en Occident, semble aussi dépendre de questions politiques. Son accueil très favorable en France et en Angleterre contraste avec une perception bien plus négative en Autriche et en Allemagne ; il s'agit là d'une position en étonnante harmonie avec les traités politiques - l'alliance franco-russe de 1891 et la triple entente de 1911 qui opposent les pays membres aux empires centraux. Le deuxième axe considéré est celui d'une analyse systématique de la naissance des études sur les images cultuelles russes, les icônes. Les pages dédiées à ce phénomène dans Γ Ikonograflja Bogomatri, mais également dans les autres ouvrages de Kondakov, posent clairement la question des raisons nationalistes et populistes de la redécouverte, autour de 1900, en Russie et en Europe de cette expression visuelle. Conclusion logique de la tradition historiographique du XIXe siècle - qui s'est préoccupé des icônes perçues comme documents historiques - cette nouvelle vague d'intérêt pose la question de l'icône commé"oeuvre d'art. C'est autour de ce débat, alimenté également par l'apparition des avant-gardes, que se situent les plus importants savants russes de ces années en opposant deux manières radicalement différentes de percevoir l'art : à l'approche positiviste s'oppose celle d'un renouveau d'Hegel. Ce débat sera brusquement interrompu par la révolution, suivie par les années staliniennes qui vont définitivement « discerner » laquelle des deux méthodes et approches est la « juste », en congelant de fait, pour des décennies, toute possibilité de discussion. Cette thèse souhaiterait donc ouvrir en Occident un débat pour l'instant marginal dans les études : celui de la naissance d'une histoire de l'art moderne en Russie, mais également de l'émergence d'une nouvelle Europe savante autour de 1900 où l'histoire de l'art byzantin s'affirme comme un domaine émergent.

Free-breathing inner-volume black-blood imaging of the human heart using two-dimensionally selective local excitation at 3 T.

Black-blood fast spin-echo imaging is a powerful technique for the evaluation of cardiac anatomy. To avoid fold-over artifacts, using a sufficiently large field of view in phase-encoding direction is mandatory. The related oversampling affects scanning time and respiratory chest motion artifacts are commonly observed. The excitation of a volume that exclusively includes the heart without its surrounding structures may help to improve scan efficiency and minimize motion artifacts. Therefore, and by building on previously reported inner-volume approach, the combination of a black-blood fast spin-echo sequence with a two-dimensionally selective radiofrequency pulse is proposed for selective "local excitation" small field of view imaging of the heart. This local excitation technique has been developed, implemented, and tested in phantoms and in vivo. With this method, small field of view imaging of a user-specified region in the human thorax is feasible, scanning becomes more time efficient, motion artifacts can be minimized, and additional flexibility in the choice of imaging parameters can be exploited.