Localization and distribution of tissue type and urokinase type plasminogen activators and their inhibitors type 1 and 2 in human and rhesus monkey fetal membranes

Fetal membranes consist of 10 distinct layers including components of amnion, chorion and decidua, the latter being of maternal origin. They form mechanically integrated sheets capable of retaining amniotic fluid and play an essential role in protecting fetal growth and development in the pregnant uterus. The extracellular matrix, substrate for plasminogen activators (PAs), is an important supportive framework of the fetal membranes. :Fetal membranes from women with preterm premature rupture of membranes may differ in their protease activity compared with normal membranes. To identify the presence of PAs and their inhibitors (PAI) and their possible role in the process of fetal membrane rupture, this study in investigated the distribution and localization of both protein and mRNA for tissue (t) and urokinase (u) PA and their inhibitors type 1 (PAI-1) and type 2 (PAI-2) in amniochorion of human and rhesus monkey using conventional and. confocal immunofluorescence microscopy. In situ hybridization analysis showed that the distribution and localization of mRNAs for tPA, uPA, PAI-I and PAI-2 were similar in the fetal membranes of human and rhesus monkey; no obvious species difference was observed. Evidence of tPA mRNA was detected in amniotic epithelium, trophoblast cells and nearly all cells of the decidual layer. Strong expression of uPA mRNA was noted in the decidual cells which increased in intensity as the abscission point was approached. Weak staining in chorion laeve trophoblast was also detected. In situ hybridization experiments showed PAI-1 mRNA to be concentrated mainly in the decidual cells, some of which were interposed into the maternal-facing edge of the chorion laeve. Maximal labelling of the decidua occurred towards the zone of abscission. Weak expression of PAI-1 mRNA nas also noted in some cells of the chorion laeve. The distribution of PAI-2 mRNA in amniochorion was also concentrated in the cells of the decidual layer, maximum expression of the mRNA was in the level of abscission. No detectable amount of mRNAs for tPA, uPA, PAI-1 and PAI-2 was found in the fibroblast, reticular and spongy layers. Distribution of the proteins of tPA, uPA and PAI-1 in the fetal membranes of these two species was consistent with the distribution of their mRNA. Anti-PAI-2 immunofluorescence was found to be strongly concentrated in the amniotic epithelium, but PAI-2 mRNA was negative in this layer, suggesting that the epithelium-associated PAI-2 is not of epithelial origin. These findings suggest that a local fibrinolysis in fetal membranes generated by precisely balanced expression of PAs and their inhibitors via paracrine or autocrine mechanisms may play an essential role in fetal membrane development, maturation and in membrane rupture. Following an analysis of the distribution and synthesis of activators and inhibitors it was found that they may play a role in abscission during the third stage of labour. (C) 1998 W. B. Saunders Company Ltd.

Cold-gas chemical vapor deposition to identify the key precursor for rapidly growing vertically-aligned single-wall and few-wall carbon nanotubes from pyrolyzed ethanol

Vertically-aligned carbon nanotubes (VA-CNTs) were rapidly grown from ethanol and their chemistry has been studied using a "cold-gas" chemical vapor deposition (CVD) method. Ethanol vapor was preheated in a furnace, cooled down and then flowed over cobalt catalysts upon ribbon-shaped substrates at 800 °C, while keeping the gas unheated. CNTs were obtained from ethanol on a sub-micrometer scale without preheating, but on a millimeter scale with preheating at 1000 °C. Acetylene was predicted to be the direct precursor by gas chromatography and gas-phase kinetic simulation, and actually led to millimeter-tall VA-CNTs without preheating when fed with hydrogen and water. There was, however a difference in CNT structure, i.e. mainly few-wall tubes from pyrolyzed ethanol and mainly single-wall tubes for unheated acetylene, and the by-products from ethanol pyrolysis possibly caused this difference. The "cold-gas" CVD, in which the gas-phase and catalytic reactions are separately controlled, allowed us to further understand CNT growth. © 2012 Elsevier Ltd. All rights reserved.

Chemical vapor deposition of nanocrystalline graphene directly on arbitrary high-temperature insulating substrates

Large area uniform nanocrystalline graphene is grown by chemical vapor deposition on arbitrary insulating substrates that can survive ∼1000°C. The as-synthesized graphene is nanocrystalline with a domain size in the order of ∼10 nm. The material possesses a transparency and conductivity similar to standard graphene fabricated by exfoliation or catalysis. A noncatalytic mechanism is proposed to explain the experimental phenomena. The developed technique is scalable and reproducible, compatible with the existing semiconductor technology, and thus can be very useful in nanoelectronic applications such as transparent electronics, nanoelectromechanical systems, as well as molecular electronics. © 2012 IEEE.

Noncatalytic chemical vapor deposition of graphene on high-temperature substrates for transparent electrodes

A noncatalytic chemical vapor deposition mechanism is proposed, where high precursor concentration, long deposition time, high temperature, and flat substrate are needed to grow large-area nanocrystalline graphene using hydrocarbon pyrolysis. The graphene is scalable, uniform, and with controlled thickness. It can be deposited on virtually any nonmetallic substrate that withstands ∼1000 °C. For typical examples, graphene grown directly on quartz and sapphire shows transmittance and conductivity similar to exfoliated or metal-catalyzed graphene, as evidenced by transmission spectroscopy and transport measurements. Raman spectroscopy confirms the sp 2-C structure. The model and results demonstrate a promising transfer-free technique for transparent electrode production. © 2012 American Institute of Physics.

Low partial pressure chemical vapor deposition of graphene on copper

A systematic study of the Cu-catalyzed chemical vapor deposition of graphene under extremely low partial pressure is carried out. A carbon precursor supply of just P CH4∼ 0.009 mbar during the deposition favors the formation of large-area uniform monolayer graphene verified by Raman spectra. A diluted HNO 3 solution is used to remove Cu before transferring graphene onto SiO 2/Si substrates or carbon grids. The graphene can be made suspended over a ∼12 μm distance, indicating its good mechanical properties. Electron transport measurements show the graphene sheet resistance of ∼0.6 kΩ/□ at zero gate voltage. The mobilities of electrons and holes are ∼1800 cm 2/Vs at 4.2 K and ∼1200 cm 2/Vs at room temperature. © 2011 IEEE.