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Abstract: Introduction: A few days after implantation, the embryo grows intensely and trophoblast giant cells (TGC) undergo cell rearrangement, especially of their cytoskeleton. Although we previously showed vimentin in mouse antimesometrial TGC at embryonic days (E) 8.5–10.5, by immunostaining, we did not demonstrate what is the first embryonic day that TGC synthesize vimentin and whether mouse chorioallantoic placental TGC express vimentin. This is of particular interest because cytokeratin is a marker for TGC in the placenta. Methods: We performed in situ hybridization and immunolocalization, combined with histological and stereological techniques, to study vimentin expression between E6.5 and E12.5 and we investigated Vegf and Flt1/Vegfr1 expression in TGC. Results: Analyses of morphologic parameters of TGC showed that the highest expansion of nuclear and cytoplasmic volumes (p ≤ 0.05) occurred at E7.5. We detected vimentin expression in TGC from E7.5 onwards; vimentin disappeared as TGC degeneration advanced. Primary and secondary TGC showed intense positive immunostaining for vimentin, Vegf and Flt1/Vegfr1 at E7.5. In the chorioallantoic placenta, parietal TGC (zone of giant cells), spiral artery-associated TGC, maternal blood canal-associated TGC and TGC within the sinusoidal spaces of the labyrinth exhibited an intense immunopositive-reaction for vimentin. Discussion: At E7.5 TGC acquire vimentin, Vegf and Flt1/Vegfr1; at the same time, blood begins to drain from maternal vessels. Vimentin synthesis initiates during a differentiation process of TGC and continues throughout the stage of vascular TGC. Conclusions: We propose that vimentin is a characteristic factor of specialized (vascular) TGC, being a valuable tool for studying pathological pregnancies associated with defects in vascular trophoblasts in mice. [Copyright &y& Elsevier]

Abstract: Anterior sacral meningoceles are rare disorders featuring anterior herniation of the meninges through a sacral defect or foramen. They are frequently misdiagnosed as ovarian or abdominal cysts and surgical exploration has resulted in meningitis. In pregnancy it represents an obstacle to delivery of the fetus and rupture of the meningocele during vaginal delivery is a significant risk. The successful multidisciplinary management of a primiparous patient with an anterior sacral meningocele and previous abdominal surgery is presented. [Copyright &y& Elsevier]

Abstract: Outer surfaces of spacecraft in orbit are exposed to hypervelocity impact originating from micro-meteoroids and space debris. The structural composite materials are integral parts of the spacecraft envelope. We studied the impact response of structural micro-composites containing Kevlar 29, spectra 1000 and oxygen RF (Radio Frequency) plasma surface-treated spectra 1000 fibers of 27-μm diameter, embedded in 100-μm epoxy resin films, in a series of planar impact experiments. The composites were loaded by 50-μm aluminum and polycarbonate impactors having velocities ranging from 400 to 550m/s. The velocity of the free surface of the composite samples was continuously monitored by VISAR (Velocity Interferometer System for Any Reflector). The dynamic tensile (spall) strength of the micro-composites was calculated on the basis of the recorded free surface velocity profiles. Correlations were found between the spall strength and the separately measured: (i) fiber/matrix interfacial adhesion, (ii) tensile strengths of the fibers, of the matrix and of the micro-composites, and (iii) internal residual stresses. The spall strength of surface-treated spectra fibers micro-composites was found to be lower than that of both pristine spectra fibers micro-composites, and the pure epoxy film. The epoxy film reinforced by Kevlar fibers was found to have the highest spall strength. [Copyright &y& Elsevier]

Abstract: Investigation of composite materials response to hypervelocity impact by space debris has been carried out. In order to simulate hypervelocity impact, a unique laser driven flyer plate (LDFP) system was used, generating hypervelocity debris with velocities of up to 3km/s. The materials studied in this research were Kevlar 29/epoxy and Spectra1000/epoxy thin film micro-composites (thickness of about 100μm). Both Spectra and Kevlar fibers are used in long-duration spacecraft outer wall shielding to reduce the perforation threat. The micro-mechanical response of different composites was studied and correlated to the fiber, the matrix and the fiber/matrix interface properties. Visual and microscopic examinations of the damaged area identified fiber debonding as the prevailing failure mechanism. On the basis of a simple energy balance model it can be stated that for Spectra/epoxy composite the dominant mechanism is new surface creation, whereas for Spectra surface-treated fibers/epoxy the fiber pull out is the dominant mechanism. For Kevlar/epoxy fiber, pull out mechanism plays an important role. [Copyright &y& Elsevier]

Abstract: There is evidence that extracellular nucleotides, acting through multiple P2 receptors, may play an important role in the regulation of bone metabolism by activating intracellular signaling cascades. We have studied the modulation of mitogen-activated protein kinase (MAPK) signaling pathways and its relationship to changes in intracellular calcium concentration ([Ca2+]i) induced by ATP in ROS-A 17/2.8 osteoblastic cells. ATP and UTP (10μM) increased [Ca2+]i by cation release from intracellular stores. We have found that when the cells are subsequently subjected to mechanical stress (medium perturbation), a transient calcium influx occurs. This mechanical stress-activated calcium influx (MSACI) was not observed after ADP stimulation, indicating that P2Y2 receptor activation is required for MSACI. In addition, ERK 1/2 and p38 MAPK were activated by ATP in a dose- and time-dependent manner. This activation was almost completely blocked using neomycin (2.5mM), an inhibitor of phosphoinositide-phospholipase C (PI-PLC), Ro 318220 (1μM), a protein kinase C (PKC) inhibitor, and PP1 (50μM), a potent and selective inhibitor of the Src-family tyrosine kinases. Ca2+-free extracellular medium (containing 0.5mM EGTA) and the use of gadolinium (5μM), which suppressed MSACI, prevented ERK 1/2 and p38 phosphorylation by ATP. Altogether, these results represent the first evidence to date suggesting that P2Y2 receptor stimulation by ATP in osteoblasts sensitizes mechanical stress activated calcium channels leading to calcium influx and a fast activation of the ERK 1/2 and p38 MAPK pathways. This effect also involves upstream mediators such as PI-PLC, PKC and Src family kinases. [Copyright &y& Elsevier]

In recent years atomic oxygen (AO) has become a major challenge for the space community. AO is the most dominant species of the residual atmosphere in low Earth orbit (LEO). In addition, AO was found at the top of the Venusian and Martian atmospheres. As a result of exposure to AO, organic space-facing materials erode, leading to changes in their roughness, thermo-optical properties, and mass loss. In the past years, there has been a growing interest in very low Earth orbit missions, below an altitude of 350 km, where AO density and thus, AO flux, are extremely high. At these low altitudes, material degradation by AO erosion poses a great risk to the integrity of any space-facing material, unless well protected. As such, measuring the AO flux and the consequential material erosion by AO, in real-time while under actual space conditions, are of great interest to the space community. Thus, in this work we present real-time AO material erosion measurements that were conducted, for the first-time in LEO, using the on-orbit material degradation detector (ORMADD). The ORMADD is a low-cost and simple to operate detector, comprised of photovoltaic cells coated with semi-transparent AO sensitive coatings. Two ORMADDs were integrated on TAUSAT-1, a 3U CubeSat, deployed into LEO from the international space station. The first ORMADD was coated with a thin amorphous-carbon coating and the second was covered with a thick pyrolytic Kapton film. Using ORMADD, we were able to follow the erosion of the coatings in real-time conditions and calculate the AO flux in TAUSAT-1 orbit. The average in-orbit flux, derived from ORMADD data, was found to be comparable to the theoretical average AO flux calculated by the space environment information system (SPENVIS) software. This work demonstrates the abilities of ORMADD as a space environment detector, as well as a space material degradation research instrument. • Atomic oxygen measurements were done by the on-orbit material degradation detector. • The on-orbit material degradation detector is based on coated photovoltaic cells. • The erosion of the coating was measured and the atomic oxygen flux was derived. • Atomic oxygen flux was also simulated by the SPENVIS simulation software. • Space measured atomic oxygen flux is comparable to the flux simulated by SPENVIS. [ABSTRACT FROM AUTHOR]