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PEI
Terms modified by PEI Selected AbstractsCutaneous Seeding of Hepatocellular Carcinoma Due to Percutaneous Ethanol Injection and Masquerading as a Pyogenic GranulomaDERMATOLOGIC SURGERY, Issue 3 2004Mei-Ching Lee MD Background. This investigation reports a 68-year-old man with a history of hepatocellular carcinoma (HCC) diagnosed 2 years previously who developed a single, easy-bleeding, pyogenic granuloma (PG)-like lesion on his right upper abdomen, located in the area of previous therapeutic percutaneous ethanol injection (PEI) for HCC treatment. The lesion developed 3 months after the injection. The tumor was found to be identical to his previous HCC. Objective. To describe a case of cutaneous seeding of HCC during PEI presented as a PG-like lesion. To our knowledge, this is the first such case reported in the literature. Methods. This is a case report and review the literature. Results. Immunostainings for ,-fetoprotein and hepatocyte monoclonal antibody confirmed the diagnosis. Besides, the patient had no other metastatic lesion. Conclusion. This tumor is believed to be caused by cutaneous seeding of HCC during PEI and is simulated clinically as a PG. [source] Synthesis and Characterization of MWNTs/Au NPs/HS(CH2)6Fc Nanocomposite: Application to Electrochemical Determination of Ascorbic AcidELECTROANALYSIS, Issue 16 2008Jian-Ding Qiu Abstract In this article, a detailed electrochemical study of a novel 6-ferrocenylhexanethiol (HS(CH2)6Fc) self-assembled multiwalled carbon nanotubes-Au nanoparticles (MWNTs/Au NPs) composite film was demonstrated. MWNTs/Au NPs were prepared by one-step in situ synthesis using linear polyethyleneimine (PEI) as bifunctionalizing agent. HS(CH2)6Fc, which acted as the redox mediator, was self-assembled to MWNTs/Au NPs via Au-S bond. Transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier transformed infrared absorption spectroscopy (FT-IR), UV-visible absorption spectroscopy, and cyclic voltammetry were used to characterize the properties of the MWNTs/Au NPs/HS(CH2)6Fc nanocomposite. The preparation of the nanocomposite was very simple and effectively prevented the leakage of the HS(CH2)6Fc mediator during measurements. The electrooxidation of AA could be catalyzed by Fc/Fc+ couple as a mediator and had a higher electrochemical response due to the unique performance of MWNTs/Au NPs. The nanocomposite modified electrode exhibited excellent catalytic efficiency, high sensitivity, good stability, fast response (within 3,s) and low detection limit toward the oxidation of AA at a lower potential. [source] On-line biosensors for simultaneous determination of glucose, choline, and glutamate integrated with a microseparation systemELECTROPHORESIS, Issue 18 2003Guoyue Shi Abstract An effective microseparation system integrated with ring-disc electrodes and two microfluidic devices was fabricated for in vivo determination using a microdialysis pump. The major interference of ascorbic acid (AA) was excluded by direct oxidation with ascorbate oxidase. Glucose, glutamate, and choline were successfully determined simultaneously through the biosensors modified with a bilayer of osmium-poly(4-vinylpyridine)gel-horseradish peroxidase (Os-gel-HRP)/glucose oxidase (GOD), glutamate oxidase (GlutaOD) or choline oxidase (ChOD). To stabilize the biosensors, 0.2% polyethylenimine (PEI) was mixed with the oxidases. The cathodic currents of glucose, glutamate, and choline biosensors started to increase after the standard solutions were injected into the microseparation system. The on-line biosensors show a wide calibration range (10,7,10,5 mol/L) with a detection limit of 10,8 mol/L at the working potential of ,50 mV. The variations of glucose, glutamate, and choline were determined simultaneously in a free moving rat when we perfused the medial frontal cortex with 100 ,mol/L N -methyl- D -aspartate (NMDA) solution, which is the agonist of the NMDA receptor. [source] Bradycardia and sinus arrest during percutaneous ethanol injection therapy for hepatocellular carcinomaEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2004A. Ferlitsch Abstract Background, Percutaneous ethanol injection (PEI) is an established method in the treatment of hepatocellular carcinoma (HCC) and considered a safe procedure, with severe complications occurring rarely. Cardiac arrhythmias have not been reported to date. Aim of the study was to investigate the occurrence of dysrhythmias during PEI. Patients and methods, Twenty-six consecutive patients with inoperable HCC were included. During ultrasound-guided PEI with 95% ethanol, electrocardiogram (ECG) monitoring was performed before starting and continuously during PEI. Results, During PEI a significant reduction in mean heart rate (> 20%) was seen in 15 of 26 (58%) patients. In 11 of 26 patients (42%) occurrence of sinuatrial block (SAB) or atrioventricular block (AVB) was observed after a median time of 9 s (range 4,50) from the start of PEI with a median length of 24 s (range 12,480). Clinical symptoms were seen in two patients, including episodes of unconsciousness, seizure-like symptoms in both and a respiratory arrest during PEI in one patient, requiring mechanical ventilation. In four of 12 patients with repeat interventions, dysrhythmias were reproducible during monthly performed procedures. There was a significant association between the occurrence of SAB or AVB and the amount of instilled alcohol (P = 0·03) and post-PEI serum ethanol levels (P = 0·03). Conclusions, Bradycardia and block formation occur frequently during PEI. These symptoms could be explained by a vasovagal reaction and/or the direct effect of ethanol on the sinus node or the right atrial conduction system. Ethanol dose is an important factor for the occurrence of SAB/AVB. ECG-monitoring seems mandatory during PEI. Prophylactic use of intravenously administered Atropine might be useful. [source] Construction of Polyethyleneimine-,-cyclodextrin/pDNA Multilayer Structure for Improved In Situ Gene Transfection,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Yan Hu This study reports in situ gene delivery from gene-functionalized poly(D,L -lactic acid) (PDLLA, Mw of around 2.0,×,105,g,mol,1) films, which were constructed via layer-by-layer (LbL) assembly technique with low molecular weight polyethylenimine-,-cyclodextrin (PEI-CD) conjugate and plasmid DNA (pDNA). PEI-CD was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), respectively. The buildup of multilayered PEI-CD/pDNA pairs onto PDLLA films was monitored with contact angle measurements and UV,Vis spectrometer, respectively. A sustained release of pDNA from multilayered films was observed for 28,h. The mechanism of in situ gene delivery on PDLLA film was investigated in this study as well. Spherical PEI-CD/pDNA complexes were formed and released following the deconstruction of multilayered films, which was confirmed by transmission electron microscopy (TEM) and gel electrophoresis, respectively. Surface mediated in situ gene transfection was achieved when culturing hepatoma G2 (HepG2) and human embryonic kidney 293 (HEK293) onto PEI-CD/pDNA multilayered films. Furthermore, PEI-CD improved the gene transfection efficiency when compared with that of PEI. Such gene-functionalized biomaterial reported here has potential application in tissue engineering and implant technology. [source] Functionalization of Chitosan via Atom Transfer Radical Polymerization for Gene DeliveryADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yuan Ping Abstract It is of crucial importance to modify chitosan-based polysaccharides in the designing of biomedical materials. In this work, atom transfer radical polymerization (ATRP) was employed to functionalize chitosan in a well-controlled manner. A series of new degradable cationic polymers (termed as PDCS) composed of biocompatible chitosan backbones and poly((2-dimethyl amino)ethyl methacrylate) (P(DMAEMA)) side chains of different length were designed as highly efficient gene vectors via ATRP. These vectors, termed as PDCS, exhibited good ability to condense plasmid DNA (pDNA) into nanoparticles with positive charge at nitrogen/phosphorus (N/P) ratios of 4 or higher. All PDCS vectors could well protect the condensed DNA from enzymatic degradation by DNase I and they displayed high level of transfectivity in both COS7, HEK293 and HepG2 cell lines. Most importantly, in comparison with high-molecular-weight P(DMAEMA) and ,gold-standard' PEI (25 kDa), the PDCS vectors showed considerable buffering capacity in the pH range of 7.4 to 5, and were capable of mediating much more efficient gene transfection at low N/P ratios. At their own optimal N/P ratios for trasnsfection, the PDCS/pDNA complexes showed much lower cytotoxicity. All the PDCS vectors were readily to be degradable in the presence of lysozyme at physiological conditions in vitro. These well-defined PDCS polymers have great potentials as efficient gene vectors in future gene therapy. [source] Biotemplated Synthesis of Gold Nanoparticle,Bacteria Cellulose Nanofiber Nanocomposites and Their Application in BiosensingADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Taiji Zhang Abstract Bacteria cellulose (BC) nanofibers are used as robust biotemplates for the facile fabrication of novel gold nanoparticle (NP),bacteria cellulose nanofiber (Au,BC) nanocomposites via a one-step method. The BC nanofibers are uniformly coated with Au NPs in aqueous suspension using poly(ethyleneimine) (PEI) as the reducing and linking agent. With the addition of different halides, Au,BC nanocomposites with different Au shell thicknesses are formed, and a possible formation mechanism is proposed by taking into account the special role played by PEI. A novel H2O2 biosensor is constructed using the obtained Au,BC nanocomposites as excellent support for horseradish peroxidase (HRP) immobilization, which allows the detection of H2O2 with a detection limit lower than 1,µM. The Au,BC nanocomposites could be further used for the immobilization of many other enzymes, and thus, may find potential applications in bioelectroanalysis and bioelectrocatalysis. [source] Nanoimprinted Polyethyleneimine: A Multimodal Template for Nanoparticle Assembly and ImmobilizationADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Chandramouleeswaran Subramani Abstract Polyethyleneimine (PEI) is used as a scaffold for integrated top-down/bottom-up fabrication. In this synergistic strategy, patterned PEI surfaces are created using thermal nanoimprint lithography (NIL) using a sacrificial polystyrene (PS) overlayer. These imprinted surfaces act as versatile templates for assembling nanoparticles and dyes, with the amine groups of the PEI enabling electrostatic assembly, carbodiimide coupling, and dithiocarbamate attachment to the nanoimprinted features. The efficient assembly of particles and dyes is confirmed through fluorescence and atomic force microscopy. In these studies the PS overlayer serves two roles. First, the PS layer protects the PEI surface during the plasma-etch removal of the residual layer of the NIL process. Second, the PS overlayer serves as a mask, enabling sequential functionalization of the sides and the tops of the PEI features. [source] PEI,PEG,Chitosan-Copolymer-Coated Iron Oxide Nanoparticles for Safe Gene Delivery: Synthesis, Complexation, and TransfectionADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Forrest M. Kievit Abstract Gene therapy offers the potential of mediating disease through modification of specific cellular functions of target cells. However, effective transport of nucleic acids to target cells with minimal side effects remains a challenge despite the use of unique viral and non-viral delivery approaches. Here, a non-viral nanoparticle gene carrier that demonstrates effective gene delivery and transfection both in vitro and in vivo is presented. The nanoparticle system (NP,CP,PEI) is made of a superparamagnetic iron oxide nanoparticle (NP), which enables magnetic resonance imaging, coated with a novel copolymer (CP,PEI) comprised of short chain polyethylenimine (PEI) and poly(ethylene glycol) (PEG) grafted to the natural polysaccharide, chitosan (CP), which allows efficient loading and protection of the nucleic acids. The function of each component material in this nanoparticle system is illustrated by comparative studies of three nanoparticle systems of different surface chemistries, through material property characterization, DNA loading and transfection analyses, and toxicity assessment. Significantly, NP,CP,PEI demonstrates an innocuous toxic profile and a high level of expression of the delivered plasmid DNA in a C6 xenograft mouse model, making it a potential candidate for safe in vivo delivery of DNA for gene therapy. [source] Pseudobilayer Vesicle Formation via Layer-by-Layer Assembly of Hydrophobically Modified Polymers on Sacrificial Substrates,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2005J. Khopade Abstract A bilayer of a hydrophobically modified polyelectrolyte, octadecyl poly(acrylamide) (PAAm), sandwiched between the layers of a hydrophilic polyelectrolyte, poly(ethyleneimine) (PEI), is prepared by the sequential electrostatic,hydrophobic,electrostatic-interaction-driven self-assembly on planar and colloid substrates. This process results in a PEI/[PAAm]2/PEI-multilayer-coated substrate. The removal of a PAA/PEI/[PAAm]2/PEI-multilayer-coated decomposable colloidal template produces hollow capsules. Irregular hydrophobic domains of the [PAAm]2 bilayer in the PEI/[PAAm]2/PEI-multilayer capsule are infiltrated with a lipid to obtain a uniform, distinct hydrophobic layer, imparting the capsule with a pseudobilayer vesicle structure. [source] Transamination by Polymeric Enzyme MimicsHELVETICA CHIMICA ACTA, Issue 11 2003Wenjun Zhou Pyridoxamine was linked to a series of polyethylenimines (PEIs) with Mn=600, 1800, 10,000, and 60,000, both simply permethylated and with additional attached dodecyl chains. They were examined in the transamination of pyruvic acid and of phenylpyruvic acid, and showed MichaelisMenten behavior. The values of k2 and of KM determined showed only small variations with polymer size. Thus, the previously reported strong advantage of pyridoxamines attached to the Mn=60,000 PEI, relative to simple pyridoxamine alone, is seen to almost the same extent with the smaller PEIs. [source] The Preliminary Employment Interview as a Predictor of Assessment Center OutcomesINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 2 2008Kobi Dayan The current study examined the relationships between personnel employment interview scores (PEI), cognitive ability test scores (CAT) and assessment center (AC) scores, as well as the potential to circumvent the costly AC method for some of the candidates by using these less expensive selection methods. A total of 423 Israeli police force candidates participated in the study. Their PEI and CAT scores were collected in the first stage of the selection process. They subsequently participated in an AC and a final decision was made regarding their acceptance to the police force. It was found that PEI and CAT scores significantly correlated with the AC scores and the recruitment decision, although the PEI scores demonstrated stronger correlations with the criteria. An actuarial analysis demonstrated the benefit of using the AC procedure for those achieving middle range scores on the PEI and CAT, circumventing the costly ACs for those achieving high and low scores. This strategy resulted in minor costs of both , and , errors. Organizations can adopt this economical strategy when the AC costs exceed the manpower costs incurred by disposing of the AC. [source] Immobilisation of the BINAP Ligand on Dendrimers and Hyperbranched Polymers: Dependence of the Catalytic Properties on the Linker UnitADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Jutta Abstract A series of immobilised Carbo-BINAP ligands has been synthesised using poly(propylene imine) (PPI) dendrimers as soluble supports. They contain up to 64 BINAP ligands at their periphery without an additional linking unit. Despite the high steric requirements of the ligand, all dendrimers could be completely functionalised, resulting in the immobilised systems in good yields. Furthermore, the immobilisation strategy that worked out for the fixation of AMINAP ligands with additional linking units as well as of Carbo-BINAP ligands without additional linking units on dendrimers has thus been extended to less regularly hyperbranched poly(ethylene imines) (PEI) as soluble supports. In that way it has been possible to attach on average 9, 26, and 138 Glutaroyl-AMINAP or Carbo-BINAP ligands to PEIs of different molecular weights. The catalytic properties of these systems in the copper-catalysed hydrosilylation of acetophenone were investigated. The dendritic PPI-bound Carbo-BINAP ligands displayed a strong dependence of enantioselectivity and activity on the generation of the dendrimer. For the Carbo-BINAP and Glutaroyl-AMINAP ligands immobilised on the hyperbranched polymers, however, activities and enantioselectivities comparable to those of the mononuclear catalysts were found. The macromolecular, immobilised BINAP ligands could be recycled several times without any observable loss of activity or enantioselectivity. [source] NBT-PABA test to assess efficiency and kinetics of substituted proteolytic enzyme action in pancreatic duct ligated minipigs,JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3 2008A. Mößeler Summary The NBT-PABA test is an established method for diagnosis of pancreatic exocrine insufficiency. In the present study the NBT-PABA test was used to test and compare the efficacy of two multienzyme preparations (product A and B) differing in galenic preparation in minipigs in which pancreatic exocrine insufficiency (PEI) was induced by pancreatic duct ligation. Without enzyme substitution no distinct increase in PABA was found in blood after oral administration of NBT-PABA. Administration of both enzyme preparations led to a clear dose dependent rise in PABA-concentrations in blood. Interestingly, the two preparations showed different time curves of serum PABA concentration, indicating differences in the kinetic of proteolytic enzyme action. It is concluded that the NBT-PABA test can be a very useful test for indirectly evaluating proteolytic enzyme efficacy in vivo, and also gives information about the kinetics of enzyme action, not only the end-result of enzyme action (like digestibility trials which were used traditionally). A single test is performed in a few hours and there is no need for fistulated animals. [source] Nano-AlN functionalization by silane modification for the preparation of covalent-integrated epoxy/poly(ether imide) nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Jingkuan Duan Abstract Aluminum nitride nanoparticle (nano-AlN) organically modified with the silane-containing epoxide groups (3-glycidoxypropyltrimethoxy silane, GPTMS) was incorporated into a mixture of poly(ether imide) (PEI), and methyl hexahydrophthalic anhydride-cured bisphenol A diglycidyl ether grafted by GPTMS was prepared for nanocomposite. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to investigate the microscopic structures of nanocomposites. According to experimental results, it was shown that addition of nano-AlN and PEI into the modified epoxy could lead to the improvement of the impact and bend strengths. When the concentrations of nano-AlN and PEI were 20 and 10 pbw, respectively, the toughness/stiffness balance could be achieved. Dynamic mechanical analysis (DMA) results displayed that two glass transition temperatures (Tg) found in the nanocomposites were assigned to the modified epoxy phase and PEI phase, respectively. As nano-AlN concentration increased, Tg value of epoxy phase had gradually increased, and the storage modulus of the nanocomposite at the ambient temperature displayed an increasing tendency. Additionally, thermal stability of the nanocomposite was apparently improved. The macroscopic properties of nanocomposites were found to be strongly dependent on their components, concentrations, dispersion, and resulted morphological structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation of poly(ester imide) ultrafine fibers by gas-jet/electrospinningJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009Bing Wang Abstract In this study, ultrafine fibers of poly(ester imide) (PEI) were produced by gas-jet/electrospinning of its solutions in mixtures of phenol and dichloromethane (DCM). The process parameters, including the solution concentration, gas flow rate, applied voltage, tip-to-collector distance (TCD), and inner diameter of the metal needle, were investigated by scanning electron microscopy. The results show that the solution concentration, gas flow rate, TCD, and inner diameter of the needle were the most important process parameters influencing the average diameter and morphology of the PEI gas-jet/electrospun fibers. An increase in the solution concentration resulted in a larger average diameter in the PEI gas-jet/electrospun fibers. Mixed-bead fibers were obtained when the concentration of PEI in phenol/DCM was below 20 wt % during gas-jet/electrospinning. A larger diameter of the capillary and a smaller gas flow rate favored the formation of ultrafine fibers with thicker fibers. Thinner and uniform PEI fibers with an average diameter of 298 nm were formed at a TCD of 25 cm. On the basis of the systematic parameters study, uniform PEI ultrafine fibers with an average diameter of 293 nm were prepared by this gas-jet/electrospinning with the following optimal process parameters: the concentration of the polymer solution was 20 wt %, the gas flow rate was 10.0 L/min, the applied voltage was 25.0 kV, the TCD was 25 cm, and the inner diameter of the metal needle was 0.24 mm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Fabrication and characterization of solution cast MWNTs/PEI nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Lu Shao Abstract Under mild conditions with the aid of ultrasonic, multi-walled carbon nanotubes (MWNTs) have been functionalized by mixed acid treatment which was proved by FTIR and XPS. According to SEM, acid treatment on MWNTs decreased the thickness of the membrane. However, no devastating damage and fracture happened on MWNTs after acid treatment under mild conditions. Precipitation observation illustrated that the enhanced solubility of MWNTs in water, ethanol, and dimethylformaide (DMF). Further, MWNTs/polyetherimide (PEI) nanocomposite films have been prepared by the simple solution casting method. The dispersion of MWNTs in polyetherimide (PEI) matrix was observed by Atomic Force Microscopy (AFM) which illustrated the improved dispersion for acid treated MWNTs in PEI. The adding of MWNTs in PEI decreased the dispersive component of surface energy and increased the polar component of surface energy, which resulted in the decrement of film surface energy. Differential scanning calorimetry showed that the glass transition temperature of PEI increased by about 4°C after the introduction of MWNTs. This improvement was related to the better affinity between MWNTs and PEI matrix, which also resulted in the improvement of mechanical strength in MWNTs/PEI nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Semi-IPN asymmetric membranes based on polyether imide (ULTEM) and polyethylene glycol diacrylate for gaseous separationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Sundar Saimani Abstract Semi-interpenetrating polymer networks (semi-IPN) formed with commercial polyether imide (ULTEM®, PEI) and poly (ethylene glycol) diacrylate (PEGDA) were used to make asymmetric membranes. The effect of increasing amount of PEGDA on the bulk and the gas separation properties of semi-IPN membranes were studied. The formation of IPNs was confirmed by Fourier Transform Infra Red (FT-IR) spectroscopy. The 5% weight loss temperature decreased and the percent weight loss of the first step increased with increase in the PEGDA content, which indicated the incorporation of more poly (ethylene glycol) (PEG) segments to the semi-IPNs. The microscopic experiments revealed the change in morphology with change in PEGDA content. The Scanning electron micrographs exhibited typical finger-like voids in the sub layer, which is characteristic morphology of asymmetric membranes. The increase in PEGDA content up to 5.7 wt % increased the CO2/N2 selectivity of the semi-IPN after which the selectivity decreased and permeance increased. Although, the increase in the polar poly (ethylene glycol) molecules is expected to render better CO2 selectivity, the performance of the membrane was found to decrease as PEGDA content exceeded 5.7% for the given ratio. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Comparison of the effects of polyethylenimine and maleated polypropylene coupling agents on the properties of cellulose-reinforced polypropylene compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008C. González-Sánchez Abstract The desire to improve the properties of cellulose-reinforced composites while producing them by methods as similar as possible to those used on an industrial scale is one of the driving forces in this field of research. In this work, extensive research for determining the mechanical, thermal, rheological, and physical properties of novel cellulose-reinforced polypropylene composites containing a polyethylenimine (PEI) coupling agent was conducted. A comparison of their properties with those of reference composites without any coupling agent or containing a maleated polypropylene (MAPP) coupling agent was also carried out. The presence of the PEI coupling agent mainly gave rise to a substantial increase in the tensile and flexural strengths and elongations as well as the impact strength, heat deflection temperature (HDT), melt volume flow index, and water absorption of PEI-containing composites in comparison with composites without any coupling agent added. However, the increases achieved in the tensile and flexural composite strengths and HDT were lower than those achieved with the MAPP coupling agent mainly for composites containing 50 wt % cellulose fibers. On the other hand, PEI-containing composites exhibited, in most cases, larger elongations and energies required to break in tensile tests as well as larger impact strengths, melt volume flow indices, and water absorption percentages than MAPP-containing composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] In vitro release of complexed pDNA from biodegradable polymer filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Y. Ramgopal Abstract The controlled delivery of low-molecular weight drugs and proteins from biodegradable polymers has received considerable attention. However, controlled release studies of pDNA from such polymers have not been reported to date. In this study, a plasmid DNA was complexed with the cationic polymer called polyethylenimine (PEI). This gene vector has been shown to be very effective in transfecting cells. The complexed DNA were then incorporated into different types of poly-lactic- co -glycolic acid (PLGA) film; PLGA 53/47 (Mw 90 kDa), 50/50 (Mw 11 kDa, end group is lauryl ester) and 75/25 (Mw 120 kDa). Their release profiles from a buffer solution were studied. An initial (small) burst release of PEI-DNA from film was observed in PLGA 53/47 and 50/50, followed by a plateau phase and finally a rapid erosion-controlled release. For PLGA 50/50, the rapid release started after 14 days; erosion-controlled release for PLGA 53/47 started after 9 days; for PLGA 75/25, the release rate was governed by an initial burst release (10%) followed by a slow release controlled by diffusion. No obvious erosion-controlled release rate was observed for this polymer up to 27 days. Thus, the controlled release of complexed DNA follows the general features exhibited by lower- Mw drugs. This is of significance in designing gene vector matrices that offer the promise of more lasting gene therapy compared with particulate formulations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Sulfonated poly(ether imide) and poly(ether sulfone) blends for direct methanol fuel cells.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Abstract This investigation examines characteristics of sulfonated polyether imides (SPEI) with various ion exchange capacity values (IEC) and completes previous work to enable its blends to be adopted as polyelectrolyte in direct methanol fuel cells (DMFC). Polyether imides (PEI) were sulfonated by using chlorosulfonic acid as the sulfonating agent and chloroform as the solvent. The structure of SPEI was observed by FTIR and 1H NMR. The sulfonate or sulfonic acid content of the polymers, expressed as a number per repeat unit of the polymer, was accurately determined by elemental analysis and conductometric titration. Physical properties such as solubility, intrinsic viscosities, thermal stability, and glass transition temperature (Tg) were studied for both PEI and SPEI. TGA-FTIR verified that sulfonic groups, attached to the aromatic ring in the PEI backbone, are split at 230,350°C, but the main-chain splitting temperature of SPEI is similar to that of pure polymer. The sulfonated samples exhibited good solubilities and increased glass transition temperatures (Tg values) as degree of sulfonation (DS) increased; two Tg values were detected when IEC was sufficiently high. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and characterization of injectable bioadhesive hydrogels for nucleus pulposus replacement and repair of the damaged intervertebral discJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2010J. Vernengo Abstract Bioadhesive polymers are natural or synthetic materials that can be used for soft tissue repair. The aim of this investigation was to develop an injectable, bioadhesive hydrogel with the potential to serve as a synthetic replacement for the nucleus pulposus of the intervertebral disc or as an annulus closure material. Branched copolymers of poly(N -isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (PEG) were blended with poly(ethylene imine) (PEI). This three component injectable system can form a precipitated gel at physiological temperature due to the phase transition of PNIPAAm. The injection of glutaraldehyde into the gel core will adhere the implant to the surrounding tissues. 1H NMR results indicated the successful physical incorporation of PEI into the PNIPAAm-PEG network by blending. In addition, the covalent crosslinking between the amine functionalities on the PEI and the aldehyde functionalities on the glutaraldehyde was verified using FTIR difference spectroscopy. Mechanical characterization of these blends showed a significant increase (p < 0.05) in compressive modulus following glutaraldehyde injection. The in vitro bioadhesive force studies with porcine skin showed a significant increase (p < 0.05) in the mean maximum force of detachment for PNIPAAm-PEG/PEI gels when glutaraldehyde was injected into the gel core. The results of this study indicate that the reactivity between amines and aldehyde functionalities can be exploited to impart bioadhesive properties to PNIPAAm-PEG/PEI copolymers. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [source] Hepatic resection compared to percutaneous ethanol injection for small hepatocellular carcinoma using propensity score matchingJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 10 2007Yong Beom Cho Abstract Background:, Several surgical and non-surgical therapeutic modalities have been used for the treatment of hepatocellular carcinoma (HCC). There have been several studies comparing hepatic resection (HR) and percutaneous ethanol injection (PEI) for the treatment of HCC. However, there is still disagreement about the best treatment modality. Methods:, From 130 patients undergoing HR, 116 patients were individually matched to 116 controls from 249 patients undergoing PEI using propensity score matching to overcome possible biases in non-randomized study. Survival analyses were undertaken to compare these propensity score-matched groups. Results:, After matching by propensity score, the major clinical outcomes in the HR (n = 116) and the PEI (n = 116) groups were found to be similar. The 1-, 3- and 5-year overall survival rates were higher in the HR group (94.8%, 76.5% and 65.6%) compared to the PEI group (95.7%, 73.5% and 49.3%) (P = 0.059). The cumulative 1-, 3- and 5-year disease-free survival rates showed the same trend (HR: 76.1%, 50.6% and 40.6%; PEI: 62.6%, 25.5% and 19.1%) (P < 0.001). However, when stratified by Child,Pugh classification, it was no longer the case in the Child B patients. Single intrahepatic recurrence was the most common pattern of tumor recurrence after both treatments. Conclusions:, Patients undergoing HR had a better survival profile than those undergoing PEI. However, when considering which technique to use for optimal HCC management, the individual patient's hepatic function must be considered. [source] Prognostic factors in patients with small hepatocellular carcinoma treated by percutaneous ethanol injectionJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 11 2002Hitoshi Kuriyama Abstract Background: Percutaneous ethanol injection (PEI) has been widely performed and is now accepted as a viable alternative to hepatic resection in patients with small hepatocellular carcinomas (HCC). However, only a few extensive investigations have been conducted regarding the prognostic factors for HCC patients treated with PEI. Methods: We investigated the prognostic factors in 100 patients with small HCC who had undergone PEI. Univariate analysis and multivariate analysis with Cox's proportional hazards model were used to determine the factors potentially related to survival. For clinical application, a prognostic index was calculated based on the regression coefficients of the independent variables identified from the multivariate analysis. Results: Median survival time and 1, 3 and 5 year survival rates were 71 months and 100, 84 and 62%, respectively. Among the 15 potential prognostic variables investigated, only three variables, namely a serum albumin level ,,3.5 g/dL, the presence of tumor stain and a serum glutamic oxaloacetic transaminase level>,66 IU/L, were identified as factors independently associated with a shorter survival. A prognostic index based on the regression coefficients of these three factors was proposed to classify patients into three groups, those with a good (5 year survival rate 91%), intermediate (64%) and poor prognosis (22%). Conclusions: The results of the present study may be useful in predicting the survival of HCC patients treated with PEI and in the design and analysis of future clinical trials of PEI for HCC. © 2002 Blackwell Publishing Asia Pty Ltd [source] Synthesis and evaluation of a water-soluble polymer to reduce Ac-225 daughter migrationJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2007Jonathan Fitzsimmons Abstract The actinium decay chain has been promoted as an in vivo alpha generator for therapy, but migration of daughters from the primary conjugate has lead to increased toxicity away from the target organ. To reduce daughter migration, polyethylenimine (PEI) was used with a primary chelator and secondary chelators. The primary chelator, DOTA, was used to coordinate 225Actinium and secondary chelators-acetate and DTPA, were added to the polymer for coordination of daughters formed by decay. The 225Actinium polymer derivatives containing secondary chelators were found to retain radioactive daughters better than the 225Actinium bond to the primary alone. The retention of 213Bismuth and 209Thallium had the following order from highest retained to lowest DOTA-PEI-DTPA,DOTA-PEI-CH2OO- > DOTA-PEI. The data suggests this polymer approach could be used to reduce daughter migration and has potential for development of actinium labeled radiopharmaceuticals. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effect of surface modifying macromolecules stoichiometric ratio on composite hydrophobic/hydrophilic membranes characteristics and performance in direct contact membrane distillationAICHE JOURNAL, Issue 12 2009M. Qtaishat Abstract The stoichiometric ratio for the synthesis components of hydrophobic new surface modifying macromolecules (nSMM) was altered systematically to produce three different types of nSMMs, which are called hereafter nSMM1, nSMM2, and nSMM3. The newly synthesized SMMs were characterized for fluorine content, average molecular weight, and glass transition temperature. The results showed that fluorine content decreased with increasing the ratio of ,,,-aminopropyl poly(dimethyl siloxane) to 4,4,-methylene bis(phenyl isocyanate). The synthesized nSMMs were blended into hydrophilic polyetherimide (PEI) host polymer to form porous hydrophobic/hydrophilic composite membranes by the phase inversion method. The prepared membranes were characterized by the contact angle measurement, X-ray photoelectron spectroscopy, gas permeation test, measurement of liquid entry pressure of water, and scanning electron microscopy. Finally, these membranes were tested for desalination by direct contact membrane distillation and the results were compared with those of commercial polytetraflouroethylene membrane. The effects of the nSMM type on the membrane morphology were identified, which enabled us to link the membrane morphology to the membrane performance. It was found that the nSMM2/PEI membrane yielded the best performance among the tested membranes. In particular, it should be emphasized that the above membrane was superior to the commercial one. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Phosphothioated oligodeoxynucleotides induce nonspecific effects on neuronal cell adhesion in a growth substrate-dependent manner,JOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2009Eitan Okun Abstract Synthetic phosphothioated (PTO) oligodeoxynucleotide (ODN) sequences are commonly used for a variety of applications that benefit from nuclease protection. The PTO modification is implemented mainly in antisense ODN, but also in ODN that were shown to activate members of the toll-like receptor (TLR) family such as TLR3 (poly-I:C), TLR8 (ssRNA), and TLR9 (CpG). Neurons are routinely plated on surfaces coated with either cationic substances such as poly-L-ornithine (PLO), polyethylenimine (PEI), poly-L-lysine or ECM components such as laminin, collagen, or fibronectin. We found that PTO-ODN aimed at activating TLR9 induces a non-TLR9-specific detachment phenotype in cortical neurons plated on either laminin or PEI, but not on PLO. This phenotype was correlated with decreased viability and was partially inhibited when caspase-3 was inhibited with Ac-DEVD-CMK. This finding suggests that the use of PTO-ODN can cause nonspecific effects on cell adhesion that could compromise interpretation of data from experiments using PTO-ODN. © 2009 Wiley-Liss, Inc. [source] Colonic delivery of ,-lactamases does not affect amoxicillin pharmacokinetics in ratsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2008Sandrine Bourgeois Abstract Pectin beads containing ,-lactamases were designed for the hydrolysis of colonic residual antibiotics responsible for the emergence of resistance. Beads were prepared by ionotropic gelation in CaCl2 and stabilized by coating with polyethylenimine (PEI) to resist disintegration in the upper GI tract. Particle characterization showed that dried beads had a diameter around 1 mm independently of the presence of PEI. Seven to ten percent (w/w) of PEI was located on bead surface forming a coating layer as observed by scanning electron microscopy. PEI improved considerably bead stability in simulated intestinal medium while affecting slightly the encapsulation efficiency of active ,-lactamases. Coated beads were able to preserve ,-lactamases from premature leakage in the upper GIT whereas, in simulated colonic medium, pectinases induced matrix degradation and reduction of ,-lactamase content especially in beads coated in a 0.8% PEI solution. Finally, the pharmacokinetics of amoxicillin in rat after oral administration was not modified by the co-administration of beads containing ,-lactamases. In conclusion, PEI-coated beads are stable in the upper GIT but remain sensitive to the action of pectinolytic enzymes allowing release of ,-lactamases in a colonic medium without modification of the absorption of a ,-lactam antibiotic when co-administered with loaded beads. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 1853,1863, 2008 [source] Maintenance of nonviral vector particle size during the freezing step of the lyophilization process is insufficient for preservation of activity: Insight from other structural indicatorsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2001Marion d.C. Molina Abstract The instability of nonviral vectors as liquid formulations has stimulated considerable interest in developing dehydrated formulations that would be resistant to shipping stresses and could be stored at room temperature. Recently, we reported that high sucrose/DNA ratios are capable of maintaining particle size during the freezing step of the lyophilization process and we suggested that the separation of individual particles within sugar matrices is responsible for the reported protection of nonviral vectors during the freezing step of a typical lyophilization protocol. The purpose of this study was to extend these observations to other nonviral vectors that incorporate different cationic components. Cationic lipid-based complexes composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), with helper lipid cholesterol (Chol) or dioleoylphosphatidyl-ethanolamine (DOPE), showed similar protection by sucrose. Formulations of a polyethylenimine (PEI)-based vector required much higher excipient/DNA ratios for size protection compared with protamine- and lipid-based vectors. At low sucrose/DNA ratios, zeta potentials for all complexes were significantly lowered during freezing. Similar results were obtained at high sucrose/DNA ratios, except for DOTAP,DOPE-containing vectors which maintained zeta potential values comparable to unfrozen controls. The changes in zeta potential values indicate that complexes are altered during freezing despite the maintenance of particle size as determined by light scattering. Furthermore, these changes might explain the observed reduction in transfection activity and provide new information about the effects of physicochemical changes of nonviral vectors during the freezing step of lyophilization. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1445,1455, 2001 [source] Prevalence of Pervasive Developmental Disorders in Two Canadian ProvincesJOURNAL OF POLICY AND PRACTICE IN INTELLECTUAL DISABILITIES, Issue 3 2006Hélčne Ouellette-Kuntz Abstract, Although it is generally accepted that the proportion of children diagnosed with pervasive developmental disorders (PDDs) has increased in the past two decades, there is no consensus on the prevalence of these conditions. The accompanying large rise in demand for services, together with uncertainty regarding the extent to which the observed increases are due to a true change in risk, has made PDDs a major public health concern. As few data exist on the prevalence of PDDs in Canada, the aim of this study was to estimate the prevalence of diagnosed PDDs in two Canadian provinces (Manitoba and Prince Edward Island (PEI)) and compare characteristics of diagnosed cases between the two regions. To obtain the estimates, children under the age of 15 years with a PDD diagnosis who lived in either province in 2002 were identified by workers at Children's Special Services, a provincial government program that supports children with special needs in Manitoba, and by the PEI provincial early intervention coordinator (Department of Social Services and Seniors) and special education autism coordinator (Department of Education). The findings show that the prevalence among children 1,14 years of age was 28.4 per 10,000 (95% confidence interval: 26.1,30.8) in Manitoba and 35.2 per 10,000 (95% confidence interval: 28.2,43.4) in PEI. In Manitoba, children of aboriginal identity with PDDs (8.3%) were significantly underrepresented compared with the general population of aboriginal children living off native reserves (15.6%). Sex ratio, sibling risk, and age at initial diagnosis were similar in the two provinces. These findings can serve as a baseline from which to monitor the prevalence of these conditions over time, providing valuable data for researchers, planners, and service providers. [source] | ||||||||||||||||||||||||||||||||||