Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of an SPUU-PEO-Heparin (B-PEO-HEP) copolymer coated blood contacting surface on patency and platelet deposition in small diameter (4 mm i.d.) Biomer grafts was investigated using a canine model. Grafts were implanted in the bilateral carotid and femoral arteries. B-PEO-HEP coated grafts still showed patency after 3 days. Control Biomer grafts occluded before 24 hr. (postoperatively). SEM of the luminal surfaces of the Biomer grafts demonstrated large amounts of adherent platelets with distorted morphologies, while B-PEO-HEP grafts did not. In platelet studies, B-PEO-HEP grafts showed significantly less platelet adhesion than Biomer grafts. The improved blood compatibility of B-PEO-HEP graft co-polymer coatings attests to their usefulness for coating or casting.
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PMID:SPUU-PEO-heparin graft copolymer surfaces. Patency and platelet deposition in canine small diameter arterial grafts. 175 Oct 86

This paper reports in vivo protein adsorption onto polymers, including Biomer, PEO grafted Biomer (B-PEO-4K), heparin immobilized Biomer with PEO spacers (B-PEO-4K-HEP), and HEMA-Styrene block copolymer (H-S). Vascular grafts (6 mm ID, 7 cm in length) were fabricated with Biomer, coated on their luminal surfaces with test polymers, and implanted into the abdominal aorta of dogs. After 3 weeks-1 month, the grafts were retrieved and processed for TEM and SEM. TEM measured the thickness of adsorbed protein layers stained with a OsO4 solution, and the distribution pattern of adsorbed proteins (albumin, IgG and fibrinogen) using the immunoperoxidase technique. Retrieved grafts of Biomer and B-PEO-4K showed mural thrombi along the graft length, while thrombus formation on B-PEO-4K-HEP and H-S grafts was limited to the anastomotic sites. SEM pictures of B-PEO-4-HEP and H-S surfaces demonstrated clear morphology, with minimal platelet adhesion and activation, and microthrombi. Biomer and B-PEO-4K demonstrated a thick proteinaceous layer (1000-2000 A), whereas B-PEO-4K-HEP and H-S showed what can be described as a monolayer protein thickness (200-300 A). B-PEO-4K-HEP and H-S showed a monolayer-like adsorbed protein pattern, with high concentrations of albumin and IgG, and less fibrinogen, while Biomer and B-PEO-4K showed multilayered patterns with relatively high concentrations of fibrinogen, and less albumin. These results suggest that the surface properties of polymer may control protein adsorption pattern, and the composition of adsorbed protein is essential to in vivo long-term blood compatibility.
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PMID:In vivo protein adsorption onto polymers: a transmission electron microscopic study. 268 16

Polyactive, a polyethylene oxide/polybutylene terephthalate (PEO/PBT) copolymer, has been reported to display bone-bonding behavior. Although a detailed description of the in vivo bone/Polyactive interface is available, the underlying bone-bonding mechanism is still largely unknown. In this in vitro study, a calvarial envelope method has been adopted to reproduce the in vivo bone-bonding phenomenon and subsequently to obtain information on the biological effect of varying PEO/PBT segment ratios. The following PEO/PBT ratios were examined: 70/30, 60/40, 55/45, 40/60, and 30/70. Light microscopy (LM) and scanning (SEM), transmission (TEM), and backscatter electron microscopy (BSE), as well as X-ray microanalysis (XRMA), were employed. Within the period of analysis (3 weeks), an intimate contact between mineralized deposition and the 70/30, 60/40, and, to a lesser extent, the 55/45 surface was observed. Calcified areas developed within the surface of these PEO/BPT proportions during the culture period. Needle-shaped crystals from the mineralized tissue compartment and from calcified areas within the materials surface were intermingled at the interface, providing a morphologic continuity. A cellular layer was interposed with the mineralization front and the noncalcified 40/60 and 30/70 substrates. Apparently, the percentage of PEO is important for calcification within the near surface of the polymer. This relation is such that the higher the PEO content in PEO/PBT ratios, the more rapid the calcification. The occurrence of material calcification is considered to be largely responsible for the subsequent interfacial interactions. The calvarial envelope culture method allows not only reproduction of the in vivo bone/Polyactive interface, but also a relatively rapid differentiation within the range of PEO/PBT ratios.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interfacial behavior of PEO/PBT copolymers (Polyactive) in a calvarial system: an in vitro study. 2690 52

In order to improve the thromboresistance of the commercial polyurethane(PU), its surface modification was accomplished by three new different methods and their surface characteristics were investigated using ATR-FTIR, ESCA, SEM, and dynamic contact angle measurements. Sulfonations using propane sultone were performed directly onto PU or onto hydrophobic dodecanediol (DDO) grafted PU or onto hydrophilic poly(ethyleneoxide) (PEO) grafted PU. ESCA data coincided well with ATR-IR results, as more 0 at. % for PEO grafted PUs and the presence of S for the sulfonated PUs were revealed. At SEM observation the surfaces of PU-DDO and PU-PEO were relatively smooth, whereas all the sulfonated PU surfaces showed excellent smoothness and homogeneity. The hydrophilicity of the surfaces was considerably increased after PEO grafting or sulfonation. In addition, all the sulfonated PU surfaces, particularly PU-PEO-SO3, which has further hydrophilicity, exhibited complete wetting behavior due to the negatively charged SO3 groups.
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PMID:Preparation and surface properties of PEO-sulfonate grafted polyurethanes for enhanced blood compatibility. 828 Jun 72

Oligosaccharides of heparin with high affinity for antithrombin III (ATIII) have been immobilized onto surface-modified NHLBI Primary Reference low density polyethylene (PE). PE was modified by radiofrequency plasma polymerized (< 150 nm thick) films derived from N-vinyl-2-pyrrolidone (PPNVP) or allyl alcohol (PPAA), and coupled by chemical derivatization to either 3-aminopropyltriethoxysilane or amino-terminated poly(ethylene oxide). High affinity heparin oligosaccharides (HA-heparin, anti-factor Xa activity of 592 +/- 120 IU/mg) prepared by partial deaminative cleavage of commercial crude heparin and fractionated by agarose-ATIII affinity chromatography, were immobilized to surface-modified PE by reductive amination. The anticoagulant activity, as determined by a chromogenic assay for the inhibition of factor Xa, was estimated to be 30-70 mIU/cm2, with binding estimated to be 56-119 ng/cm2. The highest activity was obtained for the HA-heparin immobilized to PE modified by PPNVP with a PEO spacer. Visual confirmation of ATIII binding to immobilized HA-heparin was demonstrated by a gold-labeled double antibody method with imaging by SEM.
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PMID:Immobilization of high-affinity heparin oligosaccharides to radiofrequency plasma-modified polyethylene. 840 11

Cellular interaction and platelet adsorption were investigated on poly(ethylene oxide) (PEO) immobilized silicone rubber membrane (SR) which has polyacrylic acid grafts on the surfaces. Polyacrylic acid (PAA) had been introduced to the SR surface after Ar plasma treatment of SR surfaces to introduce peroxide groups. Surface characterizations were made using ATR-FTIR, ESCA, SEM, and contact angle measurements. Experimental results obtained by ESCA high resolution curve fitting spectra indicated that the amount of bisamino PEO of different molecular weights immobilized onto SR surfaces were similar, which showed that the influence of the length of molecular chains (-C-C-O-) on the reactivity of terminal amino group is negligible. The wettability of modified SR surfaces increased with an increase in PEO molecular weight. Biological studies such as corneal epithelial cell culture and blood platelet adhesion were performed to understand the biocompatibility of modified SR surfaces. Biological studies using corneal epithelial cells showed that cell migration, attachment and proliferation onto PEO-20000 immobilized SR surface were suppressed, whereas these biological activities on PEO-600 were enhanced. Another study on platelet adhesion revealed that many platelets attached to PEO-600 immobilized SR, while platelet deposition was rarely observed on SR grafted with PEO-3350. The effects of different PEO molecular chains on biological response were discussed.
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PMID:Platelet adhesion and cellular interaction with poly(ethylene oxide) immobilized onto silicone rubber membrane surfaces. 883 31

Block copolymers consisting of poly(gamma-benzyl L-glutamate) (PBLG) as the hydrophobic block and poly(ethylene oxide) (PEO) as the hydrophilic block were synthesized and characterized. Core-shell type nanoparticles of the block copolymers (abbreviated as GE) were prepared by the diafiltration method. The particle size diameter obtained by dynamic light scattering of GE-1 (PBLG content: 60.5 mol%), GE-2 (PBLG content: 40.0 mol %), GE-3 (PBLG content: 124.4 mol %) copolymer was 309.9 +/- 160.9, 251.9 +/- 220.6 and 200.5 +/- 177.1nm, respectively. The shape of the nanoparticles by SEM or TEM was almost spherical. The critical micelle concentration of the block copolymers obtained by fluorescence spectroscopy was dependent on the chain length of hydrophobic PBLG. The micelle structure of the copolymers nanoparticle was very stable against sodium dodecyl sulfate. Clonazepam (CZ) was loaded onto the core part of the nanoparticle as the crystalline state. Release of CZ from the nanoparticles in vitro was dependent on the drug loading contents and PBLG chain length.
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PMID:Clonazepam release from core-shell type nanoparticles in vitro. 968 14

Type I collagen-PEO fibers and non-woven fiber networks were produced by the electrospinning of a weak acid solution of purified collagen at ambient temperature and pressure. As determined by high-resolution SEM and TEM. fiber morphology was influenced by solution viscosity, conductivity, and flow rate. Uniform fibers with a diameter range of 100-150 nm were produced from a 2-wt% solution of collagen-PEO at a flow rate of 100 microl min(-1). Ultimate tensile strength and elastic modulus of the resulting non-woven fabrics was dependent upon the chosen weight ratio of the collagen-PEO blend. 1H NMR dipolar magnetization transfer analysis suggested that the superior mechanical properties, observed for collagen-PEO blends of weight ratio 1:1, were due to the maximization of intermolecular interactions between the PEO and collagen components. The process outlined herein provides a convenient, non-toxic, non-denaturing approach for the generation collagen-containing nanofibers and non-woven fabrics that have potential application in wound healing, tissue engineering, and as hemostatic agents.
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PMID:Engineered collagen-PEO nanofibers and fabrics. 1178 24

Microencapsulation of the water soluble pesticide monocrotophos (MCR), using polyurethane (PU) as the carrier polymer, has been developed using two types of steric stabilizers, namely PLMA macrodiol and PLMA-g-PEO graft copolymer. The microencapsulation process is carried out in non-aqueous medium and at a moderate temperature to avoid any chemical degradation of monocrotophos during the encapsulation process. Microcapsules were characterized by optical microscopy and SEM for particle size and morphology, respectively. The effects of loading of MCR, crosslinking density of PU, and nature of steric stabilizer on the release of MCR from PU microcapsules have been studied.
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PMID:Preparation and characterization of microcapsules of water-soluble pesticide monocrotophos using polyurethane as carrier material. 1202 95

This paper describes the functionalization and crosslinking of PluronicRTM derivatives in aqueous solution at 37 degrees C. Pluronic dimethacrylate was obtained by reacting native PEO-PPO-PEO triblocks with methacryloyl chloride and then crosslinking them by free radical polymerization at 37 degrees C, using a redox system. The resulting gel and its rheological behavior were characterized by different techniques. The swelling study of the crosslinked polymer was indicative of its reverse thermo-responsive behavior, as illustrated by the almost 800% water uptake of the polymer at 37 degrees C, as opposed to the 1600% attained by the polymer at 25 degrees C. As expected, while the Pluronic dimethacrylate gel displayed an Ec value of 142.5 +/- 29.7 kPa at 37 degrees C, the crosslinked system attained a Young's modulus three times higher: 415.2 +/- 45.7 kPa. Finally, the environmental SEM analysis revealed the porous microstructure of the crosslinked gels.
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PMID:Crosslinkable PEO-PPO-PEO-based reverse thermo-responsive gels as potentially injectable materials. 1271 96


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