Showing papers by "Liqun Zhang published in 2002"
TL;DR: Investigation of human primary airway epithelial cell cultures revealed that lumenal columnar cells, specifically ciliated epithelial cells, were targeted by RSV and that cultures became susceptible to infection as they differentiated into a ciliated phenotype, suggesting that RSV infection in the absence of an immune response can be tolerated for >3 months.
Abstract: Gene therapy for cystic fibrosis (CF) lung disease requires efficient gene transfer to airway epithelial cells after intralumenal delivery. Most gene transfer vectors so far tested have not provided the efficiency required. Although human respiratory syncytial virus (RSV), a common respiratory virus, is known to infect the respiratory epithelium, the mechanism of infection and the epithelial cell type targeted by RSV have not been determined. We have utilized human primary airway epithelial cell cultures that generate a well-differentiated pseudostratified mucociliary epithelium to investigate whether RSV infects airway epithelium via the lumenal (apical) surface. A recombinant RSV expressing green fluorescent protein (rgRSV) infected epithelial cell cultures with high gene transfer efficiency when applied to the apical surface but not after basolateral inoculation. Analyses of the cell types infected by RSV revealed that lumenal columnar cells, specifically ciliated epithelial cells, were targeted by RSV and that cultures became susceptible to infection as they differentiated into a ciliated phenotype. In addition to infection of ciliated cells via the apical membrane, RSV was shed exclusively from the apical surface and spread to neighboring ciliated cells by the motion of the cilial beat. Gross histological examination of cultures infected with RSV revealed no evidence of obvious cytopathology, suggesting that RSV infection in the absence of an immune response can be tolerated for >3 months. Therefore, rgRSV efficiently transduced the airway epithelium via the lumenal surface and specifically targeted ciliated airway epithelial cells. Since rgRSV appears to breach the lumenal barriers encountered by other gene transfer vectors in the airway, this virus may be a good candidate for the development of a gene transfer vector for CF lung disease.
507 citations
TL;DR: It is found that firefly luciferase expression in prostate cancer cells can be varied over an 800-fold range and a single plasmid bearing the optimized enhancer, GAL4-VP16 derivative, and reporter expressed fireflyLuciferase at 20-fold higher levels than the cytomegalovirus enhancer.
123 citations
TL;DR: In this paper, the authors examined the oxygen-transport properties of poly(ethylene naphthalate) (PEN) isothermally crystallized from the melt (melt crystallization) or quenched to the glass and subsequently was isothermic crystallized by heating above the glass transition temperature (cold crystallization).
Abstract: In the present study we examined the oxygen-transport properties of poly(ethylene naphthalate) (PEN) isothermally crystallized from the melt (melt crystallization) or quenched to the glass and subsequently isothermally crystallized by heating above the glass transition temperature (cold crystallization). The gauche/trans conformation of the glycol linkage was determined by infrared analysis, and the crystalline morphology was examined by atomic force microscopy (AFM). Explanation of the unexpectedly high solubility of crystallized PEN required a two-phase transport model consisting of an impermeable crystalline phase of constant density and a permeable amorphous phase of variable density. The resulting relationship between oxygen solubility and amorphous-phase density was consistent with free volume concepts of gas sorption. Morphological observations provided a structural model for solubility and permeability. The model consisted of a permeable amorphous matrix of constant density containing dispersed sp...
69 citations
TL;DR: In this article, the effect of compatibilizers on mechanical properties and morphology of EPDM/nylon copolymer (PA) blends was investigated, and three forms of structures were proposed to discuss the relationship between the morphologies and mechanical properties.
53 citations
TL;DR: In this article, the authors studied the rate and extent of crystallization in crosslinked samples of natural rubber (NR), cis-1,4-polybutadiene (BR), and butyl rubber (IIR), held at low temperatures.
Abstract: The rate and extent of crystallization in crosslinked samples of natural rubber (NR), cis-1,4-polybutadiene (BR), and butyl rubber (IIR), were studied by observing the relaxation of stress in stretched strips, held at low temperatures. Melting temperatures were measured from the recovery of stress on warming. The melting temperature was raised by stretching, and the rise was significantly greater for NR than for BR, consistent with the lower heat of fusion of NR. In some cases crystallization was also followed by volume changes, or by DSC or x-ray diffraction. The maximum degree of crystallization was estimated to be only about 20% for BR, 28% for NR, and somewhat higher for IIR. On raising the temperature the tensile strength showed a marked drop to only 1–2 MPa when the elastomer failed to crystallize on stretching. At lower temperatures, when strain-induced crystallization occurred, the tensile strength was much higher, but the values were different for the three elastomers: about 10 MPa for B...
39 citations
TL;DR: The relationship of compatibility and properties of acrylonitrileitrile-butadiene-styrene (ABS) binary and ternary blends was discussed in this article, where poly(methyl methacrylate) and styrene-maleic anhydride (SMA) can improve the thermal properties of conventional ABS.
Abstract: The mechanical and heat-resistant properties of acrylonitrile–butadiene–styrene (ABS) binary and ternary blends were investigated. The relationship of compatibility and properties was discussed. The results show that poly(methyl methacrylate) (PMMA) and styrene–maleic anhydride (SMA) can improve the thermal properties of conventional ABS. The Izod impact property of ABS/PMMA blends increases significantly with the addition of PMMA, whereas that of ABS/SMA blends decreases significantly with the addition of SMA. Blends mixed with high-viscosity PMMA are characterized by higher heat-distortion temperature (HDT), and their heat resistance is similar to that of blends mixed with SMA. For high-viscosity PMMA, from 10 to 20%, it is clear that blends appear at the brittle–ductile transition, which is related to the compatibility of the two phases. TEM micrographs show low-content and high-viscosity PMMA in large, abnormally shaped forms in the matrix. Compatibility between PMMA and ABS is dependent on both the amount and the viscosity of PMMA. When the amount of high-viscosity PMMA varied from 10 to 20 wt %, the morphology of the ABS binary blends varied from poor to satisfactory compatibility. As the viscosity of PMMA decreases, the critical amount of PMMA needed for the compatibility of the two phases also decreases. SMA, as a compatibilizer, improved the interfacial adhesiveness of ABS and PMMA, which results in PMMA having good dispersion in the matrix. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2652–2660, 2002
15 citations
Patent•
27 Sep 2002
TL;DR: In this article, the authors provided infectious recombinant viral vectors (e.g., parainfluenza virus (PIV) and a respiratory syncytial virus (RSV) comprising a viral genome comprising a heterologous nucleic acid of interest.
Abstract: The present invention provides infectious recombinant viral vectors (e.g., parainfluenza virus (PIV) and a respiratory syncytial virus (RSV) vectors) comprising a viral genome comprising a heterologous nucleic acid of interest. Also provided are pseudotyped recombinant viral vectors comprising (i) a viral envelope and (ii) a viral genome comprising heterologous nucleic acids of interest. The viral envelope comprises a structural protein selected from the group consisting of envelope proteins from PIV and/or RSV. Further provided are methods of delivering heterologous nucleic acids of interest into airway epithelial cells comprising introducing viral vectors of the present invention comprising nucleic acids of interest into airway epithelial cells so that the nucleic acids of interest are expressed therein.
10 citations
Patent•
27 Sep 2002
TL;DR: In this article, the authors propose a method for distribuer les acides nucleiques heterologues d'interet dans des cellules epitheliales des voies aeriennes.
Abstract: L'invention concerne des vecteurs viraux infectieux de recombinaison (par exemple, des vecteurs de virus paragrippaux (PIV) et de virus syncytiaux respiratoires (RSV) comprenant un genome viral qui contient un acide nucleique heterologue d'interet. L'invention concerne egalement des vecteurs viraux pseudotypes de recombinaison comprenant i) une enveloppe virale et ii) un genome viral qui contient un acide nucleique heterologue d'interet. L'enveloppe virale comprend une proteine structurelle selectionnee dans le groupe constitue par des proteines d'enveloppe de PIV et/ou RSV. L'invention concerne enfin des methodes permettant de distribuer les acides nucleiques heterologues d'interet dans des cellules epitheliales des voies aeriennes, qui consistent a introduire des vecteurs viraux de l'invention comprenant des acides nucleiques d'interet dans les cellules epitheliales des voies aeriennes de sorte que lesdits acides nucleiques y sont exprimes.