[2.2](4,7)Isobenzofuranophanes - Synthesis, Characterisation and Reactivity

The isomeric Diels-Alder adducts 3, obtained by cycloaddition of tetraphenylcyclopentadienone to the 4,5:12,13-bis-(oxanorbornadieno)[2.2]paracyclophanes syn,syn- and anti,-syn-2[Note ][The stereochemical descriptors syn and anti refer to the orientation of the oxygen bridge in the oxabicyclo[2.2.1]heptadiene subunits with respect to the [2.2]paracyclophaneskeleton.], yield the unstable isobenzofuranophane 4 by consecutive extrusion of carbon monoxide and tetraphenylbenzene when heated to 180°C. The molecular ion of 4 was observed in the EI mass spectrum. The stable tetraphenyl-substituted analogue 10 was synthesized independently from the previously unknown 4,5,12,13-tetrabenzoyl[2.2]paracyclophane (9). UV/Vis as well as fluorescence spectra and an X-ray crystal structure analysis of 9 are reported

Atrophy of primary lymphoid organs induced by Marek's disease virus during early infection is associated with increased apoptosis, inhibition of cell proliferation and a severe B-lymphopenia

Marek's disease is a multi-faceted highly contagious disease affecting chickens caused by the Marek's disease alphaherpesvirus (MDV). MDV early infection induces a transient immunosuppression, which is associated with thymus and bursa of Fabricius atrophy. Little is known about the cellular processes involved in primary lymphoid organ atrophy. Here, by in situ TUNEL assay, we demonstrate that MDV infection results in a high level of apoptosis in the thymus and bursa of Fabricius, which is concomitant to the MDV lytic cycle. Interestingly, we observed that in the thymus most of the MDV infected cells at 6 days post-infection (dpi) were apoptotic, whereas in the bursa of Fabricius most of the apoptotic cells were uninfected suggesting that MDV triggers apoptosis by two different modes in these two primary lymphoid organs. In addition, a high decrease of cell proliferation was observed from 6 to 14 dpi in the bursa of Fabricius follicles, and not in the thymus. Finally, with an adapted absolute blood lymphocyte count, we demonstrate a major B-lymphopenia during the two 1st weeks of infection, and propose this method as a potent non-invasive tool to diagnose MDV bursa of Fabricius infection and atrophy. Our results demonstrate that the thymus and bursa of Fabricius atrophies are related to different cell mechanisms, with different temporalities, that affect infected and uninfected cells

A nuclear magnetic resonance biomarker for neural progenitor cells: is it all neurogenesis?

In vivo visualization of endogenous neural progenitor cells (NPCs) is crucial to advance stem cell research and will be essential to ensure the safety and efficacy of neurogenesis-based therapies. Magnetic resonance spectroscopic imaging (i.e., spatially resolved spectroscopy in vivo) is a highly promising technique by which to investigate endogenous neurogenesis noninvasively. A distinct feature in nuclear magnetic resonance spectra (i.e., a lipid signal at 1.28 ppm) was recently attributed specifically to NPCs in vitro and to neurogenic regions in vivo. Here, we demonstrate that although this 1.28-ppm biomarker is present in NPC cultures, it is not specific for the latter. The 1.28-ppm marker was also evident in mesenchymal stem cells and in non-stem cell lines. Moreover, it was absent in freshly isolated NPCs but appeared under conditions favoring growth arrest or apoptosis; it is initiated by induction of apoptosis and correlates with the appearance of mobile lipid droplets. Thus, although the 1.28-ppm signal cannot be considered as a specific biomarker for NPCs, it might still serve as a sensor for processes that are tightly associated with neurogenesis and NPCs in vivo, such as apoptosis or stem cell quiescence. However, this requires further experimental evidence. The present work clearly urges the identification of additional biomarkers for NPCs and for neurogenesis