A Micro-Optic Stalk (muOS) System to Model the Collective Migration of Retinal Neuroblasts

Contemporary regenerative therapies have introduced stem-like cells to replace damaged neurons in the visual system by recapitulating critical processes of eye development. The collective migration of neural stem cells is fundamental to retinogenesis and has been exceptionally well-studied using the fruit fly model of Drosophila Melanogaster. However, the migratory behavior of its retinal neuroblasts (RNBs) has been surprisingly understudied, despite being critical to retinal development in this invertebrate model. The current project developed a new microfluidic system to examine the collective migration of RNBs extracted from the developing visual system of Drosophila as a model for the collective motile processes of replacement neural stem cells. The system scales with the microstructure of the Drosophila optic stalk, which is a pre-cursor to the optic nerve, to produce signaling fields spatially comparable to in vivo RNB stimuli. Experiments used the micro-optic stalk system, or μOS, to demonstrate the preferred sizing and directional migration of collective, motile RNB groups in response to changes in exogenous concentrations of fibroblast growth factor (FGF), which is a key factor in development. Our data highlight the importance of cell-to-cell contacts in enabling cell cohesion during collective RNB migration and point to the unexplored synergy of invertebrate cell study and microfluidic platforms to advance regenerative strategies

Implementing evidence-based medicine in general practice: a focus group based study

BACKGROUND: Over the past years concerns are rising about the use of Evidence-Based Medicine (EBM) in health care. The calls for an increase in the practice of EBM, seem to be obstructed by many barriers preventing the implementation of evidence-based thinking and acting in general practice. This study aims to explore the barriers of Flemish GPs (General Practitioners) to the implementation of EBM in routine clinical work and to identify possible strategies for integrating EBM in daily work. METHODS: We used a qualitative research strategy to gather and analyse data. We organised focus groups between September 2002 and April 2003. The focus group data were analysed using a combined strategy of 'between-case' analysis and 'grounded theory approach'. Thirty-one general practitioners participated in four focus groups. Purposeful sampling was used to recruit participants. RESULTS: A basic classification model documents the influencing factors and actors on a micro-, meso- as well as macro-level. Patients, colleagues, competences, logistics and time were identified on the micro-level (the GPs' individual practice), commercial and consumer organisations on the meso-level (institutions, organisations) and health care policy, media and specific characteristics of evidence on the macro-level (policy level and international scientific community). Existing barriers and possible strategies to overcome these barriers were described. CONCLUSION: In order to implement EBM in routine general practice, an integrated approach on different levels needs to be developed

Bone marrow transplantation generates T cell–dependent control of myeloma in mice

Transplantation with autologous hematopoietic progenitors remains an important consolidation treatment for patients with multiple myeloma (MM) and is thought to prolong the disease plateau phase by providing intensive cytoreduction. However, transplantation induces inflammation in the context of profound lymphodepletion that may cause hitherto unexpected immunological effects. We developed preclinical models of bone marrow transplantation (BMT) for MM using Vk*MYC myeloma-bearing recipient mice and donor mice that were myeloma naive or myeloma experienced to simulate autologous transplantation. Surprisingly, we demonstrated broad induction of T cell-dependent myeloma control, most efficiently from memory T cells within myeloma-experienced grafts, but also through priming of naive T cells after BMT. CD8+ T cells from mice with controlled myeloma had a distinct T cell receptor (TCR) repertoire and higher clonotype overlap relative to myeloma-free BMT recipients. Furthermore, T cell-dependent myeloma control could be adoptively transferred to secondary recipients and was myeloma cell clone specific. Interestingly, donor-derived IL-17A acted directly on myeloma cells expressing the IL-17 receptor to induce a transcriptional landscape that promoted tumor growth and immune escape. Conversely, donor IFN-γ secretion and signaling were critical to protective immunity and were profoundly augmented by CD137 agonists. These data provide new insights into the mechanisms of action of transplantation in myeloma and provide rational approaches to improving clinical outcomes

Measurement of melatonin in body fluids: Standards, protocols and procedures

Abstract: The circadian rhythm of melatonin in saliva or plasma, or of the melatonin metabolite 6‐ sulphatoxymelatonin in urine, is a defining feature of suprachiasmatic nucleus function, the endogenous oscillatory pacemaker. These measurements are useful to evaluate problems related to the onset or offset of sleep and for assessing phase delays or advances of rhythms in entrained individuals. Additionally, they have become an important tool for psychiatric diagnosis, its use being recommended for phase typing in patients suffering from sleep and mood disorders. Thus, the development of sensitive and selective methods for the precise detection of melatonin in tissues and fluids of animals emerges as necessary. Due to its low concentration and the co‐existence of many other endogenous compounds in blood, the determination of melatonin has been an analytical challenge. This review discusses current methodologies employed for detection and quantification of melatonin in biological fluids and tissues

A reference map of the human binary protein interactome.

Global insights into cellular organization and genome function require comprehensive understanding of the interactome networks that mediate genotype-phenotype relationships(1,2). Here we present a human 'all-by-all' reference interactome map of human binary protein interactions, or 'HuRI'. With approximately 53,000 protein-protein interactions, HuRI has approximately four times as many such interactions as there are high-quality curated interactions from small-scale studies. The integration of HuRI with genome(3), transcriptome(4) and proteome(5) data enables cellular function to be studied within most physiological or pathological cellular contexts. We demonstrate the utility of HuRI in identifying the specific subcellular roles of protein-protein interactions. Inferred tissue-specific networks reveal general principles for the formation of cellular context-specific functions and elucidate potential molecular mechanisms that might underlie tissue-specific phenotypes of Mendelian diseases. HuRI is a systematic proteome-wide reference that links genomic variation to phenotypic outcomes

Collective behaviors of Drosophila-derived retinal progenitors in controlled microenvironments.

Collective behaviors of retinal progenitor cells (RPCs) are critical to the development of neural networks needed for vision. Signaling cues and pathways governing retinal cell fate, migration, and functional organization are remarkably conserved across species, and have been well-studied using Drosophila melanogaster. However, the collective migration of heterogeneous groups of RPCs in response to dynamic signaling fields of development remains incompletely understood. This is in large part because the genetic advances of seminal invertebrate models have been poorly complemented by in vitro cell study of its visual development. Tunable microfluidic assays able to replicate the miniature cellular microenvironments of the developing visual system provide newfound opportunities to probe and expand our knowledge of collective chemotactic responses essential to visual development. Our project used a controlled, microfluidic assay to produce dynamic signaling fields of Fibroblast Growth Factor (FGF) that stimulated the chemotactic migration of primary RPCs extracted from Drosophila. Results illustrated collective RPC chemotaxis dependent on average size of clustered cells, in contrast to the non-directional movement of individually-motile RPCs. Quantitative study of these diverse collective responses will advance our understanding of retina developmental processes, and aid study/treatment of inherited eye disease. Lastly, our unique coupling of defined invertebrate models with tunable microfluidic assays provides advantages for future quantitative and mechanistic study of varied RPC migratory responses