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PCL
Terms modified by PCL Selected AbstractsFacets on the psychopathy checklist screening version and instrumental violence in forensic psychiatric patientsCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 4 2010Jenny Laurell Background,There is a recognised relationship between psychopathy and instrumental violence, but not all violence by people who meet the criteria for psychopathy is instrumental. Aims,Our aims were to compare offence types among forensic psychiatric patients with and without the Psychopathy Checklist: Screening Version (PCL: SV) criteria for psychopathy. Our specific questions were whether factor 1 , the interpersonal affective dimension , was related to instrumentality and on severity of the violent crime. Our hypothesis was that the relationship between psychopathy and instrumental violence would be dependent on the severity of the violent crime. Methods,Sixty-five male patients at the forensic psychiatric hospital in Sundsvall, all with a violent criminal history, were assessed for psychopathy through interview and records using the PCL: SV. Severity and the instrumentality of their previous violence were coded using the Cornell coding guide for violent incidents. Results,The interpersonal features of psychopathy (the interpersonal facet), and only the interpersonal features were significantly associated with instrumentality and severity of violence. Instrumentality was also significantly related to the severity of the violence, independent of psychopathy score. Conclusions,The results indicated that, at least among forensic psychiatric patients, planning is more likely than not with respect to serious crimes. The specific link between interpersonal features of psychopathy and instrumental and severe violence suggests potential clinical value in recognising subtypes of psychopathy. Copyright © 2010 John Wiley & Sons, Ltd. [source] Psychopathy and offence severity in sexually aggressive and violent youthCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 4 2009Amber Fougere Background,A large proportion of violent crimes are committed by youths. Youths with psychopathic traits may have a higher risk for recidivism and violence. Aims/hypotheses,Our aim was to compare sexually aggressive with violent young men on offence severity and psychopathy. Three hypotheses were proposed: first, young men with previous offences would display a progressive increase in seriousness of offence during their criminal career; secondly, the sexually aggressive and violent young men would not differ in scores on the Hare Psychopathy Checklist: Youth Version (PCL:YV); but, thirdly, PCL:YV scores would be positively correlated with the severity of the index crime, as measured by the Cormier,Lang System for Quantifying Criminal History. Methods,Information was collected from the files of 40 young men in conflict with the law, and the PCL:Youth Version (YV) rated from this by trained raters. Results,The offences of these young men became more serious over time, but we found no association between PCL:YV scores and offence type or seriousness. Conclusions and implications,This exploratory research suggests the importance of understanding the progression in offending careers, but a limited role for the PCL:YV in doing so. Given the small sample size, however, and the limit on access to information about details of age, the findings need replication. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of discordance among violence and general recidivism risk estimates on predictive accuracyCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 3 2006Jeremy F. Mills Introduction,Previous research has shown that the prediction of short-term inpatient violence is negatively affected when clinicians' inter-rater agreement is low and when confidence in the estimate of risk is low. This study examined the effect of discordance between risk assessment instruments used to predict long-term general and violence risk in offenders. Methods,The Psychopathy Checklist , Revised (PCL,R), Level of Service Inventory , Revised (LSI,R), Violence Risk Appraisal Guide (VRAG), and the General Statistical Information on Recidivism (GSIR) were the four risk-prediction instruments used to predict post-release general and violent recidivism within a sample of 209 offenders. Results,The findings lend empirical support to the assumption that predictive accuracy is threatened where there is discordance between risk estimates. Discordance between instruments had the impact of reducing predictive accuracy for all instruments except the GSIR. Further, the influence of discordance was shown to be greater on certain instruments over others. Discordance had a moderating effect on both the PCL,R and LSI,R but not on the VRAG and GSIR. Conclusions,There is a distinct advantage when attempting to predict recidivism to employing measures such as the LSI-R, which includes dynamic variables and intervention-related criminogenic domains, over a measure purely of fixed characteristics, such as the GSIR; however, if there is discordance between the risk estimates, caution should be exercised and more reliance on the more static historically based instrument may be indicated. Copyright © 2006 John Wiley & Sons, Ltd. [source] Characteristics of spousal homicide perpetrators: a study of all cases of spousal homicide in Sweden 1990,1999CRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 2 2004Professor Henrik Belfrage PhD Background In Sweden 20 000 cases of assault against women are reported to the police every year. Method All data on the perpetrators of spousal homicide in Sweden between 1990 and 1999 were investigated (n = 164). A control group of all other perpetrators of homicide in Sweden during the same period, i.e. cases of homicide not committed in the context of spouse violence (n = 690) was used. All verdicts, as well as all material in the police investigations, including interviews with all of the police investigators, were analysed. Copies of police examinations of the suspects, and forensic reports from the autopsies, were also examined. Data on all registered criminality were collected from the National Police Register, and in cases where the perpetrators had been subject to forensic psychiatric examinations, those reports were obtained from the Swedish National Board of Forensic Medicine. In addition, the Psychopathy Checklist: Screening Version scores were rated from the forensic psychiatric examinations. Results There was a four times higher suicide rate among the spousal homicide perpetrators (24%, n = 40) compared with the perpetrators in the control-group (6%, n = 39, chi-squared = 55,42df = 1 , p < 0.001). Consequently, suicidal ideation must be considered as an important risk factor for spousal homicide. In 79% of the cases the spousal homicide perpetrators were subject to forensic psychiatric examinations. All except 5% were diagnosed with at least one psychiatric diagnosis, and 34% were sentenced to forensic psychiatric treatment. If it is assumed that the psychiatric morbidity was high in the 24% of the perpetrators who committed suicide, then 80% of all perpetrators of spouse homicide during the study period can be characterized as mentally disordered. ,Psychopathic' perpetrators, who generally are over-represented in most violent criminality, were comparatively uncommon. Only seven (4%) in the study group met the diagnostic criteria for psychopathy as measured with the PCL:SV. Discussion The group of spouse killers studied here fits the dysphoric/borderline group of spouse assaulters. This is a group that may benefit from treatment. Perhaps police officers could help identify this kind of spouse assaulter before a fatality occurs. Copyright © 2004 Whurr Publishers Ltd. [source] A Case of Primary Cardiac Lymphoma: Analysis of the Role of Echocardiography in Early DiagnosisECHOCARDIOGRAPHY, Issue 8 2007Giorgio Faganello M.D. Primary Cardiac Lymphoma (PCL) is defined as a non-Hodgkin's lymphoma involving only the heart and/or pericardium. Diagnosis of this rare disease is particularly difficult due to its nonspecific clinical manifestations. In this review the role of echocardiography in the early diagnosis of PCL is assessed, moreover we report an improvement in the outcome of PCL related to increased availability and utilization of echocardiography. [source] Low Temperature Fabrication of ,-TCP,PCL Nanocomposites for Bone Implants,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Michael Bernstein Abstract A method to fabricate strong bioresorbable calcium phosphate,polymer nanocomposites with low polymer content without exposing the material to excessively high-processing temperatures is reported. Dense ,-TCP-based nanocomposites containing 5 or 15,vol% of uniformly distributed polycaprolactone (PCL) polymer were obtained by mixing ,-TCP nanopowder with PCL dissolved in chloroform followed by room temperature consolidation at the high pressure of 2.5,GPa (cold sintering). The composites had an attractive combination of compressive strength and ductility, and their dissolution behavior was similar to that of pure cold sintered ,-TCP. The immersion of ,-TCP,PCL composites in simulated body fluid (SBF) yielded in vitro deposition of a bone-like apatite layer suggesting the ability of these materials to bind to native bone tissue upon implantation. [source] Reprogramming Hansenula polymorpha for penicillin production: expression of the Penicillium chrysogenum pcl geneFEMS YEAST RESEARCH, Issue 7 2007Loknath Gidijala Abstract We aim to introduce the penicillin biosynthetic pathway into the methylotrophic yeast Hansenula polymorpha. To allow simultaneous expression of the multiple genes of the penicillin biosynthetic pathway, additional markers were required. To this end, we constructed a novel host,vector system based on methionine auxotrophy and the H. polymorpha MET6 gene, which encodes a putative cystathionine ,-lyase. With this new host,vector system, the Penicillium chrysogenum pcl gene, encoding peroxisomal phenylacetyl-CoA ligase (PCL), was expressed in H. polymorpha. PCL has a potential C-terminal peroxisomal targeting signal type 1 (PTS1). Our data demonstrate that a green fluorescent protein,PCL fusion protein has a dual location in the heterologous host in the cytosol and in peroxisomes. Mutation of the PTS1 of PCL (SKI-COOH) to SKL-COOH restored sorting of the fusion protein to peroxisomes only. Additionally, we demonstrate that peroxisomal PCL,SKL produced in H. polymorpha displays normal enzymatic activities. [source] Conductive Core,Sheath Nanofibers and Their Potential Application in Neural Tissue EngineeringADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Jingwei Xie Abstract Conductive core,sheath nanofibers are prepared by a combination of electrospinning and aqueous polymerization. Specifically, nanofibers electrospun from poly(, -caprolactone) (PCL) and poly(L -lactide) (PLA) are employed as templates to generate uniform sheaths of polypyrrole (PPy) by in-situ polymerization. These conductive core,sheath nanofibers offer a unique system to study the synergistic effect of different cues on neurite outgrowth in vitro. It is found that explanted dorsal root ganglia (DRG) adhere well to the conductive core,sheath nanofibers and generate neurites across the surface when there is a nerve growth factor in the medium. Furthermore, the neurites can be oriented along one direction and enhanced by 82% in terms of maximum length when uniaxially aligned conductive core,sheath nanofibers are compared with their random counterparts. Electrical stimulation, when applied through the mats of conductive core,sheath nanofibers, is found to further increase the maximum length of neurites for random and aligned samples by 83% and 47%, respectively, relative to the controls without electrical stimulation. Together these results suggest the potential use of the conductive core,sheath nanofibers as scaffolds in applications such as neural tissue engineering. [source] pH-Responsive Flower-Type Micelles Formed by a Biotinylated Poly(2-vinylpyridine)- block -poly(ethylene oxide)- block -poly(, -caprolactone) Triblock CopolymerADVANCED FUNCTIONAL MATERIALS, Issue 9 2009Kathy Van Butsele Abstract In the present work, a method is proposed to assemble pH-responsive, flower-like micelles that can expose a targeting unit at their periphery upon a decrease in pH. The micelles are composed of a novel biotinylated triblock copolymer of poly(,, -caprolactone)- block -poly(ethylene oxide)- block -poly(2-vinylpyridine) (PCL- b -PEO- b -P2VP) and the non-biotinylated analogue. The block copolymers are synthesized by sequential anionic and ring-opening polymerization. The pH-dependent micellization behaviour in aqueous solution of the triblock copolymers developed is studied using dynamic light scattering, zeta potential, transmission electron microscopy (TEM), and fluorimetric measurements. The shielding of the biotin at neutral pH and their availability at the micelle surface upon protonation is established by TEM and surface plasmon resonance with avidin and streptavidin-coated gold surfaces. The preliminary stealthy behavior of these pH-responsive micelles is examined using the complement activation (CH50) test. [source] One-Step Process for Creating Triple-Shape Capability of AB Polymer NetworksADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Marc Behl Abstract Triple-shape polymers can move from a first shape (A) to a second shape (B) and from there to a third shape (C), where both shape changes are induced by temperature increases. This triple-shape capability is obtained for multiphase polymer networks after application of a complex thermomechanical programming process, which consists of two steps; these steps create shapes (B) and (A), while shape (C) is defined by the covalent crosslinks of the polymer network. Here, the creation of the triple-shape capability for an AB polymer network system by a simple one-step process similar to a conventional dual-shape programming process is reported. The polymer networks are based on poly(, -caprolactone) (PCL) and poly(cyclohexyl methacrylate); favorable compositions for obtaining a triple shape effect have a PCL content between 35 and 60 wt%. This finding substantially facilitates handling of the triple-shape technology and is an important step toward the realization of potential applications in which more than one shape change is required. [source] Poly(,-caprolactone)-Functionalized Carbon Nanotubes and Their Biodegradation Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2006H.-L. Zeng Abstract Biodegradable poly(,-caprolactone) (PCL) has been covalently grafted onto the surfaces of multiwalled carbon nanotubes (MWNTs) by the "grafting from" approach based on in-situ ring-opening polymerization of ,-caprolactone. The grafted PCL content can be controlled easily by adjusting the feed ratio of monomer to MWNT-supported macroinitiators (MWNT-OH). The resulting products have been characterized with Fourier-transform IR (FTIR), NMR, and Raman spectroscopies, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). After PCL was coated onto MWNT surfaces, core/shell structures with nanotubes as the "hard" core and the hairy polymer layer as the "soft" shell are formed, especially for MWNTs coated with a high density of polymer chains. Such a polymer shell promises good solubility/dispersibility of the MWNT,PCL nanohybrids in low-boiling-point organic solvents such as chloroform and tetrahydrofuran. Biodegradation experiments have shown that the PCL grafted onto MWNTs can be completely enzymatically degraded within 4,days in a phosphate buffer solution in the presence of pseudomonas (PS) lipase, and the carbon nanotubes retain their tubelike morphologies, as observed by SEM and TEM. The results present possible applications for these biocompatible PCL-functionalized CNTs in bionanomaterials, biomedicine, and artificial bones. [source] Microencapsulation of rosmarinic acid using polycaprolactone and various surfactantsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2010H.-J. Kim Synopsis Rosmarinic acid (RA) has a number of interesting biological activities, e.g. anti-viral, anti-bacterial, anti-inflammatory and antioxidant. The antioxidant activity of RA is stronger than that of vitamin E. Despite its strong antioxidant activity, it was limited to use in cosmetics because of the low water solubility, discolouration and chemical instability. The purpose of this study was to prepare RA-loaded polycaprolactone (PCL) microspheres using emulsion solvent evaporation method and characterize them with different surfactants used in the formation process. Finally, long-term stability of RA was evaluated in the cosmetic formulation. As a result, PCL microspheres were found to be spherical in shape, with zwitterionic surfactant-PCL particles being the smallest size distribution and highest entrapment efficiency of RA. Emulsions containing RA-loaded PCL microspheres showed a better long-term stability of the RA compared with those containing only RA. These results suggest that RA may be stably and efficiently encapsulated into polycaprolactone microspheres. Résumé Micro encapsulation d'acide rosmarinique utilisant la polycaprolactone et divers surfactants L'acide rosmarinique a un certain nombre d'activités biologiques intéressantes, par exemple antivirales, antibactériennes, anti-inflammatoires et antioxydantes. L'activité antioxydante de l'acide rosmarinique est plus puissante que celle de la vitamine E. Malgré sa forte activité antioxydante, son usage en cosmétique est limité en raison de sa faible solubilité dans l'eau, sa décoloration et son instabilité chimique. Le but de cette étude était de préparer des microsphères de PCL chargées d'acide rosmarinique par la méthode d'émulsification par d'évaporation de solvant et de les caractériser selon les différents surfactants utilisés dans le processus de fabrication. Enfin, la stabilitéà long terme de l'acide rosmarinique a étéévaluée dans la formulation cosmétique. Les microsphères PCL ont été trouvé de forme sphérique, avec les surfactants zwitterioniques, les particules PCL offrent une distribution de petites tailles et une efficacité de piégeage en acide rosmarinique la plus élevée. Les émulsions contenant des microsphères PCL chargées d'acide rosmarinique ont montréà long terme une meilleure stabilité en acide rosmarinique que celles contenant l'acide seul. Ces résultats suggèrent que l'acide rosmarinique peut être encapsulé de façon efficace et stable dans des microsphères de polycaprolactone. [source] Magnetite-Loaded Polymeric Micelles as Ultrasensitive Magnetic-Resonance Probes,ADVANCED MATERIALS, Issue 16 2005H. Ai Increased contrast in magnetic resonance imaging (MRI) is accomplished using polymeric micelles loaded with superparamagnetic iron oxide (SPIO) nanoparticles encapsulated in biocompatible, biodegradable poly(,-caprolactone)- b -poly(ethylene glycol) (PCL- b -PEG) copolymers (see Figure). The loaded micelles show significantly improved T2 relaxivities and remarkable MRI detection sensitivity. [source] Disc structure function and its potential for repairINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 1 2002J. Melrose The intervertebral disc (IVD) is the largest predominantly avascular, aneural, alymphatic structure of the human body. It provides articulation between adjoining vertebral bodies and also acts as a weight-bearing cushion dissipating axially applied spinal loads. The IVD is composed of an outer collagen-rich annulus fibrosus (AF) and a central proteoglycan (PG)-rich nucleus pulposus (NP). Superior and inferior cartilaginous endplates (CEPs), thin layers of hyaline-like cartilage, cover the ends of the vertebral bodies. The AF is composed of concentric layers (lamellae) which contain variable proportions of type I and II collagen, this tissue has high tensile strength. The NP in contrast is a gelatinous PG-rich tissue which provides weight-bearing properties to the composite disc structure. With the onset of age, cells in the NP progressively die as this tissue becomes depleted of PGs, less hydrated and more fibrous as the disc undergoes an age-dependent fibrocartilaginous transformation. Such age-dependent cellular and matrix changes can decrease the discs' biomechanical competence and trauma can further lead to failure of structural components of the disc. Annular defects are fairly common and include vertebral rim-lesions, concentric (circumferential) annular tears (separation of adjacent annular lamellae) and radial annular tears (clefts which initiate within the NP). While vascular in-growth around annular tears has been noted, evidence from human post-mortem studies indicate they have a limited ability to undergo repair. Several experimental approaches are currently under evaluation for their ability to promote the repair of such annular lesions. These include growth of AF fibrochondrocytes on a resorbable polycaprolactone (PCL) bio-membrane.1 Sheets of fibrochondrocytes lay down type-I collagen and actin stress fibres on PCL. These matrix components are important for the spatial assembly of the collagenous lamella during annular development and correct phenotypic expression of cells in biomatrices.1 An alternative approach employs preparation of tissue engineered IVDs where AF and NP cells are separately cultured in polyglycolic acid and sodium alginate biomatrices, either separately or within a manifold designed to reproduce the required IVD dimensions for its use as a prospective implant device.2 AF and NP cells have also been grown on tissue culture inserts after their recovery from alginate bead culture to form plugs of tissue engineered cartilage.3 A key component in this latter strategy was the stimulation of the high density disc cell cultures with osteogenic protein-1 (OP-1) 200 ng/mL.3 This resulted in the production of tissue engineered AF and NP plugs with compositions, histochemical characteristics and biomechanical properties approaching those of the native disc tissues.2,3 Such materials hold reat promise in future applications as disc or annular implants. The introduction of appropriate genes into disc cells by gene transduction methodology using adenoviral vectors or ,gene-gun' delivery systems also holds considerable promise for the promotion of disc repair processes.4 Such an approach with the OP-1 gene is particularly appealing.5 The anchoring of discal implants to vertebral bodies has also been evaluated by several approaches. A 3D fabric based polyethylene biocomposite holds much promise as one such anchorage device6 while biological glues used to seal fibrocartilaginous structures such as the AF and meniscus8 following surgical intervention, also hold promise in this area. Several very promising new experimental approaches and strategies are therefore currently under evaluation for the improvement of discal repair. The aforementioned IVD defects are a common cause of disc failure and sites of increased nerve in-growth in symptomatic IVDs in man and are thus often sources of sciatic-type pain. Annular defects such as those described above have formerly been considered incapable of undergoing spontaneous repair thus a clear need exists for interventions which might improve on their repair. Based on the rapid rate of progress and the examples outlined above one may optimistically suggest that a successful remedy to this troublesome clinical entity will be developed in the not so distant future. References 1JohnsonWEBet al. (2001) Directed cytoskeletal orientation and intervertebral disc cell growth: towards the development of annular repair techniques. Trans Orthop Res Soc26, 894. 2MizunoHet al. (2001) Tissue engineering of a composite intervertebral disc. Trans Orthop Res Soc26, 78. 3MatsumotoTet al. (2001) Formation of transplantable disc shaped tissues by nucleus pulposus and annulus fibrosus cells: biochemical and biomechanical properties. Trans Orthop Res Soc26, 897. 4NishidaKet al. (2000) Potential applications of gene therapy to the treatment of intervertebral disc disorders. Clin Orthop Rel Res379 (Suppl), S234,S241. 5MatsumotoTet al. (2001) Transfer of osteogenic protein-1 gene by gene gun system promotes matrix synthesis in bovine intervertebral disc and articular cartilage cells. Trans Orthop Res Soc26, 30. 6ShikinamiY , Kawarada (1998) Potential application of a triaxial three-dimensional fabric (3-DF) as an implant. Biomaterials19, 617,35. [source] Bladder wall grafting in rats using salt-modified and collagen-coated polycaprolactone scaffolds: Preliminary reportINTERNATIONAL JOURNAL OF UROLOGY, Issue 10 2007Dah-Shyong Yu Aim: A rat model was used for the evaluation of collagen-coated and salt-modified polycaprolactone (PCL) scaffolds for bladder grafting after hemicystectomy. Methods: SD rats underwent partial cystectomy and cystoplasty with collagen-coated and salt-modified polycaprolactone scaffolds. The grafts of the regenerated bladder wall were harvested at different intervals and tissue regeneration was evaluated microscopically. Anatomic and functional characters were evaluated by cystography and urodynamics. Results: At harvesting, after 1 and 2 months, we found good preservation of the bladder shape and volume in all 16 rats receiving PCL cystorrhaphy. No stone formation was observed. Good epithelialization and ingrowth of smooth muscle cells were seen after 2 months grafting. Collagen-coated PCL scaffolds showed considerable encrustation, which appeared to be absorbed and disappear with time. The cystographic and urodynamic examinations revealed intact contour and a well-accommodated bladder with reservoir volume and contractility. Conclusions: In the rat model, we have successfully demonstrated the applicability of collagen coated and salt-modified PCL in reconstruction of the partial cystectomized bladder. [source] Linear-dendritic copolymers as nanocatalystsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009M. Adeli Abstract Functionalized poly(ethylene glycol) (PEG) containing four chloride end functional groups (PEG-Cl4) was synthesized through reaction between cyanuric chloride and PEG-(OH)2. Chloride end functional groups of PEG-Cl4 were able to initiate the ring opening polymerization of 2-ethyl-2-oxazoline and star copolymers containing a PEG core, and poly(2-ethyl-2-oxazoline) (POX) arms were obtained. Polymerization was quenched using diethanolamine, and star copolymers containing hydroxyl end functional groups (PEG-POX-OH) were obtained. ,-Caprolactone was then polymerized using the hydroxyl end functional groups of star copolymers and amphiphilic linear-dendritic copolymers containing PEG and POX, and poly(caprolactone) (PCL) blocks were synthesized. Linear-dendritic copolymers were able to load the organic and inorganic guest molecules. Application of host-guest systems such as nanocatalyst for Heck chemical reaction was also investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Surface modification of starch nanocrystals through ring-opening polymerization of ,-caprolactone and investigation of their microstructuresJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Hassan Namazi Abstract Bionanoparticles of starch obtained by submitting native potato starch granules to acid hydrolysis conditions. The resulted starch nanoparticles were used as core or macro initiator for polymerization of ,-caprolactone (CL). Starch nanoparticle- g -polycaprolactone was synthesized through ring-opening polymerization (ROP) of CL in the presence of Sn(Oct)2 as initiator. The detailed microstructure of the resulted copolymer was characterized with NMR spectroscopy. Thermal characteristic of the copolymer was investigated using DSC and TGA. By introducing PCL, the range of melting temperature for starch was increased and degradation of copolymer occurred in a broader region. X-ray diffraction and TEM micrographs confirmed that there was no alteration of starch crystalline structure and morphology of nanoparticles, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and characterization of fullerene grafted poly(,-caprolactone)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Weihua Kai Abstract The fullerene grafted poly(,-caprolactone) (PCL) was successfully synthesized with a graft efficiency of 80%. The fullerene moieties grafted onto the PCL chain aggregate into 1,2 ,m particles so that a physical pseudo -network is formed. Because of the existence of the network structure, the fullerene grafted PCL film can retain its shape at much higher temperatures than that of pure PCL film, as observed in dynamic mechanical tests. It shows a hydrophobic gelling behavior in chloroform solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Biodegradable poly(vinyl alcohol)- graft - poly(,-caprolactone) comb-like polyester: Microwave synthesis and its characterizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Zhaoju Yu Abstract Poly(vinyl alcohol)-initiated microwave-assisted ring opening polymerization of ,-caprolactone in bulk was investigated, and a series of poly(vinyl alcohol)- graft -poly(,-caprolactone) (PVA- g -PCL) copolymers were prepared, with the degree of polymerization (DP) of PCL side chains and the degree of substitution (DS) of PVA by PCL being in the range of 3,24 and 0.35,0.89, respectively. The resultant comb-like PVA- g -PCL copolymers were confirmed by means of FTIR, 1H NMR, and viscometry measurement. The introduction of hydrophilic backbone resulted in the decrease in both melting point and crystallization property of the PVA- g -PCL copolymers comparing with linear PCL. With higher microwave power, the DP of PCL side chains and DS of PVA backbone were higher, and the polymerization reaction proceeded more rapidly. Both the DP and monomer conversion increased with irradiation time, while the DS increased first and then remained constant. With initiator in low concentration, the DP and DS were higher, while the monomer was converted more slowly. Microwaves dramatically improved the polymerization reaction in comparison of conventional heating method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3973,3979, 2007 [source] Characterization of pegylated copolymeric micelles and in vivo pharmacokinetics and biodistribution studiesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006Wen-Jen Lin Abstract The aim of this study was to evaluate the influence of pegylated copolymeric micelle carrier on the biodistribution of drug in rats. The copolymers were synthesized via a modified ring-opening copolymerization of lactone monomers (,-caprolactone, ,-valerolactone, L -lactide) and poly(ethylene glycol) (PEG10,000 and PEG4000). The molecular weights and the polydispersities of synthesized copolymers were in the range of 15,000,31,000 g/mol and 1.7,2.7, respectively. All of the pegylated amphiphilic copolymers were micelles formed with low CMC values in the range of 10,7,10,8M. The drug-loaded micelles were prepared via a dialysis method. The average particle size of micelles was around 150,200 nm. The cytotoxicity in terms of cell viability after treated with PCL,PEG, PVL,PEG, and PLA,PEG micelles was insignificant. PCL,PEG and PVL,PEG micelles without branch side chain in structures had higher drug loading than PLA,PEG micelles. In vitro release profiles indicated the release of indomethacin from these micelles exhibited a sustained release behavior. The similar phenomenon was also observed in vivo in rats. The pegylated copolymeric micelles not only decreased drug uptake by the liver and kidney, but also prolonged drug retention in the blood. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Ranolazine Exerts Potent Effects on Atrial Electrical Properties and Abbreviates Atrial Fibrillation Duration in the Intact Porcine HeartJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2009KAPIL KUMAR M.D. Introduction: In vitro studies and ambulatory ECG recordings from the MERLIN TIMI-36 clinical trial suggest that the novel antianginal agent ranolazine may have the potential to suppress atrial arrhythmias. However, there are no reports of effects of ranolazine on atrial electrophysiologic properties in large intact animals. Methods and Results: In 12 closed-chest anesthetized pigs, effects of intravenous ranolazine (,9 ,M plasma concentration) on multisite atrial effective refractory period (ERP), conduction time (CT), and duration and inducibility of atrial fibrillation (AF) initiated by intrapericardial acetylcholine were investigated. Ranolazine increased ERP by a median of 45 ms (interquartile range 29,50 ms; P < 0.05, n = 6) in right and left atria compared to control at pacing cycle length (PCL) of 400 ms. However, ERP increased by only 28 (24,34) ms in right ventricle (P < 0.01, n = 6). Ranolazine increased atrial CT from 89 (71,109) ms to 98 (86,121) ms (P = 0.04, n = 6) at PCL of 400 ms. Ranolazine decreased AF duration from 894 (811,1220) seconds to 621 (549,761) seconds (P = 0.03, n = 6). AF was reinducible in 1 of 6 animals after termination with ranolazine compared with all 6 animals during control period (P = 0.07). Dominant frequency (DF) of AF was reduced by ranolazine in left atrium from 11.7 (10.7,20.5) Hz to 7.6 (2.9,8.8) Hz (P = 0.02, n = 6). Conclusions: Ranolazine, at therapeutic doses, increased atrial ERP to greater extent than ventricular ERP and prolonged atrial CT in a frequency-dependent manner in the porcine heart. AF duration and DF were also reduced by ranolazine. Potential role of ranolazine in AF management merits further investigation. [source] Modeling and simulation of polymeric nanocapsule formation by emulsion diffusion methodAICHE JOURNAL, Issue 8 2009M. Hassou Abstract The objective of this work is to develop a predictive dynamical model of a nanoencapsulation process using an emulsion diffusion method. This model describes the formation of the polymeric membrane around the oil droplet and its size reduction due to the solvent diffusion. To this end, we assume that the phase separation is only due to purely diffusive mechanism. This work is illustrated on the formation of poly-,-caprolactone (PCL) around the oily core formed of labrafac from the initial homogeneous polymer-solvent-nonsolvent solution (PCL, ethyl acetate, and labrafac). The polymeric membrane formation, the size reduction of the nanocapsule after the solvent diffusion, and the morphology of nanocapsules are experimentally investigated. It is shown that the results obtained in simulation from the dynamical model are in agreement with the experimental ones. The model is then used to predict the effect of the initial composition on the nanocapsule morphology. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Multifunctioning pH-responsive nanoparticles from hierarchical self-assembly of polymer brush for cancer drug deliveryAICHE JOURNAL, Issue 11 2008Youqing Shen Abstract Polymer nanoparticles are extensively explored as drug carriers but they generally have issues of premature burst drug release, slow cellular uptake, and retention in acidic intracellular compartments. Herein, we report multifunctioning three-layered nanoparticles (3LNPs) that can overcome these problems. The 3LNPs have a poly(,-caprolactone) (PCL) core, a pH-responsive poly[2-(N,N-diethylamino)ethyl methacrylate](PDEA) middle layer and a polyethylene glycol (PEG) outer layer. The pH-responsive PDEA layer is insoluble at pH above 7 but becomes positively charged and soluble via protonation at pH lower than 6.5. Thus, this layer has three functions: it covers on the PCL core inhibiting the premature burst drug release at the physiological pH, becomes positively charged and thus promotes endocytosis for fast cellular internalization in the acidic interstitium of solid tumors, and is highly positively charged in lysosomes to disrupt the lysosomal membrane and release the nanoparticle into the cytosol. The multifunctioning nanoparticles are an efficient carrier for cancer cytosolic drug delivery. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Promotion of osteogenesis in tissue-engineered bone by pre-seeding endothelial progenitor cells-derived endothelial cellsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2008Haiying Yu Abstract In addition to a biocompatible scaffold and an osteogenic cell population, tissue-engineered bone requires an appropriate vascular bed to overcome the obstacle of nutrient and oxygen transport in the 3D structure. We hypothesized that the addition of endothelial cells (ECs) may improve osteogenesis and prevent necrosis of engineered bone via effective neovascularization. Osteoblasts and ECs were differentiated from bone marrow of BALB/c mice, and their phenotypes were confirmed prior to implantation. Cylindrical porous polycaprolactone (PCL)-hydroxyapatite (HA) scaffolds were synthesized. ECs were seeded on scaffolds followed by seeding of osteoblasts in the EC-OB group. In the OB group, scaffolds were only seeded with osteoblasts. The cell-free scaffolds were denoted as control group. A 0.4-cm-long segmental femur defect was established and replaced with the grafts. The grafts were evaluated histologically at 6 weeks postimplantation. In comparison with the OB group, the EC-OB group resulted in a widely distributed capillary network, osteoid generated by osteoblasts and absent ischemic necroses. Pre-seeding scaffold with ECs effectively promoted neovascularization in grafts, prevented the ischemic necrosis, and improved osteogenesis. The integration of bone marrow-derived ECs and osteoblasts in porous scaffold is a useful strategy to achieve engineered bone. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1147,1152, 2008 [source] One- and two-strand posterior cruciate ligament reconstructions: Cyclic fatigue testingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2005Jason T. Shearn This study examined how one- and two-strand posterior cruciate ligament (PCL) reconstructions resist the return of posterior translation during repetitive knee cycling. The femoral attachment of the one-strand graft and the anterior strand of the two-strand (AD2) grafts were located within the anterior one-third of the femoral PCL footprint. The second strand was placed within the middle third of the femoral footprint in one of three locations: middle,distal (MD), middle,middle (MM), or middle,proximal (MP). During repetitive knee cycling from 5° to 120° flexion with a 100 N posterior force, the intact knee had less than 1 mm of residual posterior translation after 2048 flexion,extension cycles. Under similar cyclic conditions, the AD2 -MM reconstruction achieved the most cycles before failure; however, this two-strand configuration failed in less than 700 cycles. The other reconstructions, either one strand or two strand, failed in less than 350 cycles. The surface failure location for 19 of 25 graft strands was within the femoral one-third of the strand. We concluded that one- and two-strand reconstructions under moderate loading and a range of motion from 5° to 120° flexion have an unacceptably high cyclic failure rate suggesting modifications of the allowable postoperative knee flexion and loading. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Biomechanical effects of medial,lateral tibial tunnel placement in posterior cruciate ligament reconstructionJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2003Keith L. Markolf With most posterior cruciate (PCL) reconstruction techniques, the distal end of the graft is fixed within a tibial bone tunnel. Although a surgical goal is to locate this tunnel at the center of the PCL's tibial footprint, errors in medial,lateral tunnel placement of the tibial drill guide are possible because the position of the tip of the guide relative to the PCL's tibial footprint can be difficult to visualize from the standard arthroscopy portals. This study was designed to measure changes in knee laxity and graft forces resulting from mal-position of the tibial tunnel medial and lateral to the center of the PCL's tibial insertion. Bone,patellar tendon,bone allografts were inserted into three separate tibial tunnels drilled into each of 10 fresh-frozen knee specimens. Drilling the tibial tunnel 5 mm medial or lateral to the center of the PCL's tibial footprint had no significant effect on knee laxities: the graft pretension necessary to restore normal laxity at 90° of knee flexion (laxity match pretension) with the medial tunnel was 13.8 N (29%) greater than with the central tunnel. During passive knee flexion,extension, graft forces with the medial tibial tunnel were significantly higher than those with the central tunnel for flexion angles greater than 65° while graft forces with the central tibial tunnel were not significantly different than those with the lateral tibial tunnel. Graft forces with medial and lateral tunnels were not significantly different from those with a central tunnel for 100 N applied posterior tibial force, 5 N m applied varus and valgus moment, and 5 N m applied internal and external tibial torque. With the exception of slightly higher graft forces recorded with the medial tunnel beyond 65° of passive knee flexion, errors in medial,lateral placement of the tibial tunnel would not appear to have important effects on the biomechanical characteristics of the reconstructed knee. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Solubilization of hydrophobic drugs by methoxy poly(ethylene glycol)-block-polycaprolactone diblock copolymer micelles: Theoretical and experimental data and correlationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2008Kevin Letchford Abstract The solubilization of five model hydrophobic drugs by a series of micelle-forming, water-soluble methoxy poly(ethylene glycol)-block-polycaprolactone diblock copolymers (MePEG-b-PCL) with varying methoxy poly(ethylene glycol) (MePEG) and polycaprolactone (PCL) block lengths was investigated. Variation of the feed weight ratio of MePEG to caprolactone resulted in the synthesis of copolymers with predictable block lengths. The micelle diameter and pyrene partition coefficient (Kv) were directly related to the PCL block length whereas the critical micelle concentrations (CMC) were inversely related to the PCL block length. The aqueous solubilities of the model hydrophobic drugs, indomethacin, curcumin, plumbagin, paclitaxel, and etoposide were increased by encapsulation within the micelles. Drug solubilization was directly related to the compatibility between the solubilizate and PCL as determined by the Flory,Huggins interaction parameter (,sp). Furthermore, the concentration of solubilized drug was also directly related to the PCL block length. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:1179,1190, 2008 [source] Methoxypolyethylene glycol- block -polycaprolactone diblock copolymers reduce P-glycoprotein efflux in the absence of a membrane fluidization effect while stimulating P-glycoprotein ATPase activityJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2007Jason Zastre Abstract We have previously shown that amphiphilic diblock copolymers composed of methoxypolyethylene glycol- b -polycaprolactone (MePEG- b -PCL) increased the cellular accumulation and reduced the basolateral to apical flux of the P-glycoprotein substrate, rhodamine 123 (R-123) in caco-2 cells. The purpose of this study was to investigate membrane perturbation effects of MePEG- b -PCL diblock copolymers with erythrocyte membranes and caco-2 cells and the effect on P-gp ATPase activity. The diblock copolymer MePEG17 -b-PCL5 induced increasing erythrocyte hemolysis at concentrations which correlated with increasing accumulation of R-123 into caco-2 cells. However, no increase in cellular accumulation of R-123 by non-P-gp expressing cells was observed, suggesting that diblock did not enhance the transmembrane passive diffusion of R-123, but that the accumulation enhancement effect of the diblock in caco-2 cells was likely mediated primarily via P-gp inhibition. Fluorescence anisotropy measurements of membrane fluidity and P-gp ATPase activity demonstrated that MePEG17 - b -PCL5 decreased caco-2 membrane fluidity while stimulating ATPase activity approximately threefold at concentrations that maximally enhanced R-123 caco-2 accumulation. These results suggest that inhibition of P-gp efflux by MePEG17 - b -PCL5 does not appear to be related to increases in membrane fluidity or through inhibition in P-gp ATPase activities, which are two commonly reported cellular effects for P-gp inhibition mediated by surfactants. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 864,875, 2007 [source] Effect of lipid bilayer alteration on transdermal delivery of a high-molecular-weight and lipophilic drug: Studies with paclitaxelJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2004Ramesh Panchagnula Abstract Skin forms an excellent barrier against drug permeation, due to the rigid lamellar structure of the stratum corneum (SC) lipids. Poor permeability of drugs can be enhanced through alteration in partition and diffusion coefficients, or concentration gradient of drug with an appropriate choice of solvent system, along with penetration enhancers. The aim of the current investigation was to assess applicability of lipid bilayer alteration by fatty acids and terpenes toward the permeation enhancement of a high-molecular-weight, lipophilic drug, paclitaxel (PCL) through rat skin. From among the fatty acids studied using ethanol/isopropyl myristate (1:1) vehicle, no significant enhancement in flux of PCL was observed (p,>,0.05). In the case of cis mono and polyunsaturated fatty acids lag time was found to be similar to control (p,>,0.05). This suggests that the permeation of a high-molecular-weight, lipophilic drug may not be enhanced by the alteration of the lipid bilayer, or the main barrier to permeation could lie in lower hydrophilic layers of skin. A significant increase in lag time was observed with trans unsaturated fatty acids unlike the cis isomers, and this was explained on the basis of conformation and preferential partitioning of fatty acids into skin. From among the terpenes, flux of PCL with cineole was significantly different from other studied terpenes and controls, and after treatment with menthol and menthone permeability was found to be reduced. Menthol and menthone cause loosening of the SC lipid bilayer due to breaking of hydrogen bonding between ceramides, resulting in penetration of water into the lipids of the SC lipid bilayer that leads to creation of new aqueous channels and is responsible for increased hydrophilicity of SC. This increased hydrophilicity of the SC bilayer might have resulted in unfavorable conditions for ethanol/isopropyl myristate (1:1) along with PCL to penetrate into skin, therefore permeability was reduced. The findings of this study suggest that the permeation of a high-molecular-weight and lipophilic drug cannot be enhanced through bilayer alteration by penetration enhancers, and alteration in partitioning of drug into skin could be a feasible mode to enhance the permeation of drug. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:2177,2183, 2004 [source] Synthesis and self-assembly of well-defined cyclodextrin-centered amphiphilic A14B7 multimiktoarm star copolymers based on poly(,-caprolactone) and poly(acrylic acid)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2010Peng-Fei Gou Abstract Novel amphiphilic A14B7 multimiktoarm star copolymers composed of 14 poly(,-caprolactone) (PCL) arms and 7 poly(acrylic acid) (PAA) arms with ,-cyclodextrin (,-CD) as core moiety were synthesized by the combination of controlled ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). 14-Arm star PCL homopolymers (CDSi-SPCL) were first synthesized by the CROP of CL using per-6-(tert -butyldimethylsilyl)-,-CD as the multifunctional initiator in the presence of Sn(Oct)2 at 125 °C. Subsequently, the hydroxyl end groups of CDSi-SPCL were blocked by acetyl chloride. After desilylation of the tert -butyldimethylsilyl ether groups from the ,-CD core, 7 ATRP initiating sites were introduced by treating with 2-bromoisobutyryl bromide, which further initiated ATRP of tert -butyl acrylate (tBA) to prepare well-defined A14B7 multimiktoarm star copolymers [CDS(PCL-PtBA)]. Their molecular structures and physical properties were in detail characterized by 1H NMR, SEC-MALLS, and DSC. The selective hydrolysis of tert -butyl ester groups of the PtBA block gave the amphiphilic A14B7 multimiktoarm star copolymers [CDS(PCL-PAA)]. These amphiphilic copolymers could self-assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2961,2974, 2010 [source] | |||||||||||||||||||||||||||||||||||||