Sympatric speciation in palms on an oceanic island.

The origin of species diversity has challenged biologists for over two centuries. Allopatric speciation, the divergence of species resulting from geographical isolation, is well documented. However, sympatric speciation, divergence without geographical isolation, is highly controversial. Claims of sympatric speciation must demonstrate species sympatry, sister relationships, reproductive isolation, and that an earlier allopatric phase is highly unlikely. Here we provide clear support for sympatric speciation in a case study of two species of palm (Arecaceae) on an oceanic island. A large dated phylogenetic tree shows that the two species of Howea, endemic to the remote Lord Howe Island, are sister taxa and diverged from each other well after the island was formed 6.9 million years ago. During fieldwork, we found a substantial disjunction in flowering time that is correlated with soil preference. In addition, a genome scan indicates that few genetic loci are more divergent between the two species than expected under neutrality, a finding consistent with models of sympatric speciation involving disruptive/divergent selection. This case study of sympatric speciation in plants provides an opportunity for refining theoretical models on the origin of species, and new impetus for exploring putative plant and animal examples on oceanic islands.

Epidermal growth factor receptor: a re-emerging target in glioblastoma.

PURPOSE OF REVIEW: Amplification and overexpression of the epidermal growth factor receptor (EGFR) gene are a hallmark of primary glioblastoma (45%), making it a prime target for therapy. In addition, these amplifications are frequently associated with oncogenic mutations in the extracellular domain. However, efforts at targeting the EGFR tyrosine kinase using small molecule inhibitors or antibodies have shown disappointing efficacy in clinical trials for newly diagnosed or recurrent glioblastoma. Here, we review recent insights into molecular mechanisms relevant for effective targeting of the EGFR pathway. RECENT FINDINGS: Molecular workup of glioblastoma tissue of patients under treatment with small molecule inhibitors has established drug concentrations in the tumor tissue, and has shed light on the effectiveness of target inhibition and respective effects on pathway signaling. Further, functional analyses of interaction of small molecule inhibitors with distinct properties to bind to the active or inactive form of EGFR have provided new insights that will impact the choice of drugs. Finally, vaccination approaches targeting the EGFRvIII mutant featuring a tumor-specific antigen have shown promising results that warrant larger controlled clinical trials. SUMMARY: A combination of preclinical and clinical studies at the molecular level has provided new insights that will allow refining strategies for targeting the EGFR pathway in glioblastoma.

Targetting of the ventro-intermediate nucleus using ultra-high field (7T) MRI for gamma knife surgery purposes: A pilot in vivo study on healthy subjects.

INTRODUCTION: Gamma Knife surgery (GKS) is a non-invasive neurosurgical stereotactic procedure, increasingly used as an alternative to open functional procedures. This includes targeting of the ventro-intermediate nucleus of the thalamus (e.g. Vim) for tremor. We currently perform an indirect targeting, as the Vim is not visible on current 3Tesla MRI acquisitions. Our objective was to enhance anatomic imaging (aiming at refining the precision of anatomic target selection by direct visualisation) in patients treated for tremor with Vim GKS, by using high field 7T MRI. MATERIALS AND METHODSH: Five young healthy subjects were scanned on 3 (T1-w and diffusion tensor imaging) and 7T (high-resolution susceptibility weighted images (SWI)) MRI in Lausanne. All images were further integrated for the first time into the Gamma Plan Software(®) (Elekta Instruments, AB, Sweden) and co-registered (with T1 was a reference). A simulation of targeting of the Vim was done using various methods on the 3T images. Furthermore, a correlation with the position of the found target with the 7T SWI was performed. The atlas of Morel et al. (Zurich, CH) was used to confirm the findings on a detailed analysis inside/outside the Gamma Plan. RESULTS: The use of SWI provided us with a superior resolution and an improved image contrast within the basal ganglia. This allowed visualization and direct delineation of some subgroups of thalamic nuclei in vivo, including the Vim. The position of the target, as assessed on 3T, perfectly matched with the supposed one of the Vim on the SWI. Furthermore, a 3-dimensional model of the Vim-target area was created on the basis of the obtained images. CONCLUSION: This is the first report of the integration of SWI high field MRI into the LGP, aiming at the improvement of targeting validation of the Vim in tremor. The anatomical correlation between the direct visualization on 7T and the current targeting methods on 3T (e.g. quadrilatere of Guyot, histological atlases) seems to show a very good anatomical matching. Further studies are needed to validate this technique, both by improving the accuracy of the targeting of the Vim (potentially also other thalamic nuclei) and to perform clinical assessment.

Imagerie par DXA: le couteau suisse multifonction [DXA imaging: the multifunction Swiss army knife?].

Les importants progrès dans la qualité et la résolution des images obtenues par «absorptiométrie biphotonique à rayons X» ou DXA ont amélioré certaines modalités existantes et favorisé le développement de nouvelles fonctions permettant d'affiner de manière significative la prise en charge de nos patients dans diverses pathologies. On peut par exemple améliorer la prédiction du risque fracturaire par l'analyse indirecte de la micro et de la macroarchitecture osseuse, rechercher les marqueurs de pathologies associées (recherche de fractures vertébrales ou de fractures fémorales atypiques), ou évaluer le statut métabolique par la mesure de la composition corporelle. Avec les appareils DXA les plus performants, on pourra bientôt déterminer l'âge osseux, estimer le risque cardiovasculaire (par la mesure de la calcification de l'aorte abdominale), ou prédire la progression de l'arthrose articulaire et son évolution après la prise en charge chirurgicale dans la routine clinique. The significant progress on the quality and resolution of the images obtained by "Dual X-ray Absorptiometry" or DXA has permitted on one hand to improve some existing features and on the other to develop new ones, significantly refining the care of our patients in various pathologies. For example, by improving the prediction of fracture risk by indirect analysis of micro- and macro-architecture of the bone, by looking for markers of associated bone diseases (research vertebral fractures or atypical femoral fractures), or by assessing the metabolic status by the measurement of body composition. With the best performing DXA devices we will soon be able, in clinical routine, to determine bone age, to estimate cardiovascular risk (by measuring the calcification of the abdominal aorta) or to predict the progression of joint osteoarthritis and its evolution after surgical management.