HORMONAL-REGULATION OF TISSUE-TYPE PLASMINOGEN-ACTIVATOR AND PLASMINOGEN-ACTIVATOR INHIBITOR TYPE-1 IN CULTURED MONKEY SERTOLI CELLS

Sertoli cells play a central role in the control and maintenance of spermatogenesis. Isolated Sertoli cells of mouse and rat testes have been shown to secrete plasminogen activator (PA) and a plasminogen activator inhibitor type-1 (PAI-1) in culture. In this study, we have investigated the hormonal regulation of PA and PAI-1 activities in cultured monkey Sertoli cells. Sertoli cells (5x10(5) cells/well) isolated from infant rhesus monkey testes were preincubated at 35 degrees C for 16 h in 24-well plates precoated with poly(D-lysine) (5 mu g/cm(2)) in 0.5 mi McCoy's 5a medium containing 5% of fetal calf serum and further incubated for 48 h in 0.5 mi serum-free medium with or without various hormones or other compounds, PA as well as PAI-1 activities in the conditioned media were assayed by fibrin overlay and reverse fibrin autography techniques respectively. The Sertoli cells in vitro secreted only tissue-type PA (tPA), no detectable amount of urokinase-type PA (uPA) could be observed, Monkey Sertoli cells were also capable of secreting PAI-1, Immunocytochemical studies indicated that both tPA and PAI-1 positive staining localized in the Sertoli cells, spermatids and residual bodies of the seminiferous epithelium; Northern blot analysis further confirmed the presence of both tPA and PAI-1 mRNA in monkey Sertoli cells. Addition of follicle-stimulating hormone (FSH) or cyclic adenosine monophosphate (cAMP) derivatives or cAMP-generating agents and gonadotrophin-releasing hormone (GnRH) agonist or phorbol ester (PMA) to the cell culture significantly increased tPA activity. PAI-1 activity in the culture was also enhanced by these reagents except 8-bromo-dibutyryl-cAMP, forskolin and 3-isobutyl-1-methylxanthin (MIX) which greatly stimulated tPA activity, whereas decreased PAI-1 activity, implying that neutralization of PAI-1 activity by tile high level of tPA in the conditioned media may occur. These data suggest that increased intracellular signals which activate protein kinase A (PKA), or protein kinase C (PKC) can modulate Sertoli cell tPA and PAI-1 activities, The concomitant induction of PA and PAI-1 by the same reagents in the Sertoli cells may reflect a finely tuned regulatory mechanism in which PAI-1 could limit the excession of the proteolysis.

Purification, characterization and primary structure of a chymotrypsin inhibitor from Naja atra venom

A chymotrypsin inhibitor, designated NA-CI, was isolated from the venom of the Chinese cobra Naja atra by three-step chromatography. It inhibited bovine (x-chymotrypsin with a K-i of 25 nM. The molecular mass of NA-CI was determined to be 6403.8 Da by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) analysis. The complete amino acid sequence was determined after digestion of S-carboxymethylated inhibitor with Staphylococcus aureus V8 protease and porcine trypsin. NA-CI was a single polypeptide chain composed of 57 amino acid residues. The main contact site with the protease (PI) has a Phe, showing the specificity of the inhibitor. NA-CI shared great similarity with the chymotrypsin inhibitor from Naja naja venom (identities = 89.5%) and other snake venom protease inhibitors. (C) 2003 Elsevier Inc. All rights reserved.

Observation of early to full covering stages of ethylene-based CVD of graphene

Scalable growth is essential for graphene-based applications. Recent development has enabled the achievement of the scalability by use of chemical vapor deposition (CVD) at 1000°C with copper as a catalyst and methane as a precursor gas. Here we report our observation of early stage of graphene growth based on an ethylene-based CVD method, capable of reducing the growth temperature to 770°C for monolayer graphene growth on copper. We track the early stages of slow growth under low ethylene flow rate and observe the graphene domain evolution by varying the temperature and growth time. Temperature-dependence of graphene domain density gives an apparent activation energy of 1.0 eV for nucleation.

Compression and tensile properties of self-reinforced poly(ethylene terephthalate)-composites

Tensile and compression properties of self-reinforced poly(ethylene terephthalate) (SrPET) composites has been investigated. SrPET composites or all-polymer composites have improved mechanical properties compared to the bulk polymer but with maintained recyclability. In contrast to traditional carbon/glass fibre reinforced composites, SrPET composites are very ductile, resulting in high failure strains without softening or catastrophic failure. In tension, the SrPET composites behave linear elastically until the fibre-matrix interface fails, at which point the stiffness starts decreasing. As the material is further strained, strain hardening occurs and the specimen finally fails at a global strain above 10%. In compression, the composite initially fails through fibre yielding, and at higher strains through fibre bending. The stress-strain response is reminiscent of an elastic-perfectly plastic material with a high strain to failure (typically over 10%). This indicates that SrPET composites are not only candidates as semi-structural composites but also as highly efficient energy absorbing materials. © 2012 Elsevier Ltd. All rights reserved.

Macrocyclic polyamine-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith for capillary electrochromatography

1,4,10,13,16-Pentaazatricycloheneicosane-9,17-dione (macrocyclic polyamine)-modified polymer-based monolithic column for CEC was prepared by ring opening reaction of epoxide groups from poly(glycidyl methacrylate-co-ethylene dimethacrylate) (GMA-co-EDMA) monolith with macrocyclic polyamine. Conditions such as reaction time and concentration of macrocyclic polyamine for the modification reaction were optimized to generate substantial EOF and enough chromatographic interactions. Anodic EOF was observed in the pH range of 2.0-8.0 studied due to the protonation of macrcyclic polyamine at the surface of the monolith. Morphology of the monolithic column was examined by SEM and the incorporation of macrocyclic polyamine to the poly(GMA-co-EDMA) monolith was characterized by infrared (IR) spectra. Successful separation of inorganic anions, isomeric benzenediols, and benzoic acid derivatives on the monolithic column was achieved for CEC. In addition to hydrophobic interaction, hydrogen bonding and electrostatic interaction played a significant role in the separation process.

Study of crystallinity and thermomechanical analysis of annealed poly(ethylene terephthalate) films

The objective of this article was the determination of the degree of crystallinity of a series of heat-set poly(ethylene terephthalate) (PET) films and their study by thermomechanical analysis (TMA) in order to elucidate a peculiar behaviour that takes place around the glass transition region. For this purpose, amorphous cast Mylar films from DuPont were annealed at 115 °C for various periods of time. Four methods were used to study the crystallinity of the samples prepared: differential scanning calorimetry (DSC), density measurements (DM), wide-angle X-ray diffraction (WAXD), and Fourier transform infrared spectroscopy (FT-IR). From the results obtained, the following conclusions are drawn: amorphous PET Mylar films can be crystallized in a degree of about up to 30% after thermal treatment for 30 min (cold crystallization) above glass transition temperature. When these semicrystalline samples are subjected to TMA, they show a two step penetration of the probe into them, which decreases with the increase of the degree of crystallinity. The first step of penetration was attributed to the shrinkage of the amorphous or semicrystalline sample, which takes place on the glass transition temperature, while the second step was attributed to the continuous softening of the sample, and the reorganization of the matter which takes place on heating run due to cold crystallization. © 2008 Elsevier Ltd. All rights reserved.

The fabrication of TiO2-supported zeolite with core/shell heterostructure for ethanol dehydration to ethylene

The TiO2-supported zeolite with core/shell heterostructure was fabricated by coating aluminosilicate zeolite (ASZ) on the TiO2 inoculating seed via in situ hydrothermal synthesis. The catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), nitrogen physisorption (BET), and Fourier transform infrared spectroscopy (FT-IR). The surface acidity of the catalysts was measured by pyridine-TPD method. The catalytic performance of the catalysts for ethanol dehydration to ethylene was also investigated. The results show that the TiO2-supported zeolite composite catalyst with core/shell heterostructure exhibits prominent conversion efficiency for ethanol dehydration to ethylene.

Catalytic Dehydration of Ethanol to Ethylene on TiO2/4A Zeolite Composite Catalysts

TiO2/4A zeolite composite catalysts were prepared by coating TiO2 on 4A zeolite via liquid phase deposition. The TiO 2/4A zeolite composite catalysts wtih higher surface weak acidity and lower mediate strong acidity exhibit much better catalytic performance on ethanol dehydration to ethylene compared with 4A zeolite. It is suggested that the TiO2 promoter could improve the effective Lewis acidity of composite catalyst which consequently enhanced the catalytic performance.

Experimental Investigation on Propane Hydrate Dissociation by High Concentration Methanol and Ethylene Glycol Solution Injection

The dissociation behaviors of propane hydrate by high concentration alcohols inhibitors injection were investigated. Methanol (30.0, 60.1, 80.2, and 99.5 wt %) and ethylene glycol (30.0, 60.1, 69.8, 80.2, and 99.5 wt %) solution were injected, respectively, as alcohols inhibitors in 3.5 L transparent reactor. It is shown that the average dissociation rates of propane hydrate injecting methanol and ethylene glycol solution are 0.02059-0.04535 and 0.0302-0.0606 mol.min(-1).L-1, respectively. The average dissociation rates increase with the mass concentration increase of alcohols solution, and it is the biggest when 99.5 wt % ethylene glycol solution was injected. The presence of alcohols accelerates gas hydrate dissociation and reduces the total need of external energy to dissociate the hydrates. Density differences act as driving force, causing the acceleration effects of ethylene glycol on dissociation behaviors of propane hydrate are better than that of methanol with the same injecting flux and mass concentration.

Experimental investigation of production behavior of methane hydrate under ethylene glycol injection in unconsolidated sediment

This article investigates the gas production behavior from methane hydrate (MH) in porous sediment by injecting ethylene glycol (EG) solution with the different concentrations and the different injection rates in an one-dimensional experimental apparatus. The results suggest that the gas production process can be divided into the four stages: (1) the initial injection, (2) the EG diluteness, (3) the hydrate dissociation, and (4) the remained gas output. Nevertheless, the water production rate keeps nearly constant during the whole production process. The production efficiency is affected by both the EG concentration and the EG injection rate, and it reaches a maximum with the EG concentration of 60 wt %.

Recombinant protein of heptad-repeat HR212, a stable fusion inhibitor with potent anti-HIV action in vitro

HR212, a recombinant protein expressed in Escherichia coli, has been previously reported to inhibit HIV-1 membrane fusion at low nanomolar level. Here we report that HR212 is effective in blocking laboratory strain HIV-1IIIB entry and replication with EC50 values of 3.92±0.62 and 6.59±1.74 nM, respectively, and inhibiting infection by clinic isolate HIV-1KM018 with EC50 values of 44.44±10.20 nM, as well as suppressing HIV-1- induced cytopathic effect with an EC50 value of 3.04±1.20 nM. It also inhibited HIV-2ROD and HIV-2CBL-20 entry and replication in the μM range. Notably, HR212 was highly effective against T20-resistant strains with EC50 values ranging from 5.09 to 7.75 nM. Unlike T20, HR212 showed stability sufficient to inhibit syncytia formation in a time-of-addition assay, and was insensitive to proteinase K digestion. These results suggest that HR212 has great potential to be further developed as novel HIV-1 fusion inhibitor for treatment of HIV/ AIDS patients, particularly for those infected by T20-resistant variants.