Endothelial progenitor cells populate the stromal stem niche of tympanum

The tympanic membrane (TM) integrity is of utmost importance for the sense of hearing. Therefore, the intrinsic potential of the TM to regenerate and repair deserves complete characterisation. Existing studies brought evidence on the epithelial stem niche of the TM. However, the stromal compartment was not evaluated for harbouring a distinctive stem, or progenitor, niche. We aimed doing this in transmission electron microscopy. We used TMs dissected out from 3 male Oryctolagus cuniculus rabbits. Evidence of stromal quiescent stem cells was gathered. Moreover, endothelial progenitor cells were found in the TM, being accurately identified by two specific ultrastructural markers of the endothelial lineage: the Weibel-Palade bodies and the stomatal diaphragms of the subplasmalemmal caveolae. The stromal stem niche of the TM appears to be a distinctive contributor during physiological and pathological processes of the TM, such as cholesteatoma formation, at least as a biological support for processes of vasculogenesis. However, further characterisation of the molecular pattern of the stromal stem niche of the TM is mandatory

Human adult dental pulp CD117/c-kit-positive networks of stromal cells

Dental pulp tissue was collected from 6 healthy adult patients, prior to prosthetic treatments, in order to evaluate the in situ phenotype of dental pulp stromal cells and compare with that of dental pulp stem cells. A CD34–/CD44+/CD105–/CD117+/CD146–/nestin– phenotype of stromal cells in the dental pulp core was found. Cells with a similar phenotype, but CD44–, were found in the cell richzone. Dental pulp stromal networks (DPSNs) were found CD117+/CD44+ in the pulp core, but CD117+/CD44– in the cell rich zone. The c-kit-positive DPSNs were contacting pulp nerves and were, in this regard only, comparable to interstitial Cajal cells. Stromal signalling in dental pulp needs further evaluation, in normal tissue as well as a possible cause of persisting pain after endodontic treatment

Late snowfall and blizzards in Moldavia. April 2017 summary case of study

While these are normal phenomena for Romania’s geographical position, heavy snows and intense blizzards can have severely negative effects, especially when they occur unseasonably, before or after the typical period. The blizzard recorded on 19-20 April 2017 was particularly violent and one of the latest blizzard events in the history of meteorological observations. In comparison, the last significant late winter event, albeit lower in intensity, was recorded on 15-16 April 1996. However, the blizzard formation mechanism in the month of April in eastern regions is relatively similar. The presence of a high-pressure zone in the central-western European region led, in both cases, to fast large-scale penetrations of arctic air from high latitudes towards areas with high cyclogenetic potential in the Mediterranean Sea basin. Thus, the depressions of Mediterranean origin, which formed in the Genova Gulf area, advanced towards the Black Sea basin via trans-Balkan trajectories, where they regenerated and resulted in strong windintensification and abundant precipitation in the Moldavian region. With regard to the event this study analyses, the high thermobaric contrast and the presence of a sufficiently cold air mass favored, during the night between the 19th and the 20th of April, the occurrence of a strong blizzard event in Moldavia, following abundant wet snowfall during the day. At several meteorological stations across Moldavia and Transylvania, as well as in mountainous areas, the maximum winter snow layer thickness was exceeded on the 20th and 21st of April