bluuebunny/crossref_metadata_2025_split huggingface dataset:
24S‐hydroxycholesterol in relation to disease manifestations of acute experimental autoimmune encephalomyelitis
Authors: Teunissen C.E. , Floris S. , Sonke M. , Dijkstra C.D. , De Vries H.E. , Lütjohann D. 
Published: April 2007

AbstractLevels of the brain‐specific cholesterol metabolite 24S‐hydroxycholesterol are proposed as possible biomarkers for multiple sclerosis (MS). It is not yet clear for which aspect of the MS disease manifestations 24S‐hydroxycholesterol is a reflection. We studied the relation of serum levels of 24S‐hydroxycholesterol and other sterols to the disease characteristics of acute experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Serum was analyzed for cholesterol precursors, oxysterols, and plant sterols during the course of disease development. Significantly increased levels of the cholesterol metabolites 24S‐hydroxycholesterol and 27‐hydroxycholesterol were observed on day 9, before the onset of clinical signs. The serum levels of these oxysterols gradually increased up to 193% and 415%, respectively, at day 17, when clinical symptoms had recovered. Total cholesterol levels were slightly but significantly decreased on day 9 and day 17 in treated animals. Serum levels of cholesterol precursors and plant sterols decreased gradually from day 11 and day 14, respectively. Immunostaining of the 24S‐hydroxycholesterol‐forming enzyme Cyp46 was shown in macrophage infiltrates. In vitro experiments confirmed the presence of Cyp46 in macrophages and showed a decreased expression after LPS treatment. The data indicate that changes in serum oxysterols occur early in EAE and can be formed by macrophages. These early changes indicate an important role for oxysterols in the development of EAE. © 2007 Wiley‐Liss, Inc.
Role of c‐Jun N‐terminal kinase in early brain injury after subarachnoid hemorrhage
Authors: Yatsushige Hiroshi , Ostrowski Robert P. , Tsubokawa Tamiji , Colohan Austin , Zhang John H. 
Published: April 2007

AbstractThe c‐Jun N‐terminal kinase (JNK) is induced by cerebral ischemia and injurious blood components acutely after subarachnoid hemorrhage (SAH). We hypothesized that inhibition of JNK will prevent damage to the neurovascular unit in the early brain injury period after SAH. Ninety‐nine male SD rats (300–350 g) were randomly assigned to sham, SAH, and SAH treated with JNK inhibitor groups. SAH was induced by endovascular perforation. The JNK inhibitor SP600125 was administered intraperitoneally at 1 hr before and 6 hr after SAH. At 24 hr after SAH, we observed increased phosphorylation of JNK and c‐Jun. Signs of neurovascular damage were observed in the hemorrhagic brains; these included the increases of aquaporin (AQP)‐1 expression and brain water content as well as enhanced matrix metalloproteinase (MMP)‐9 activity, vascular collagen IV loss, increased VEGF tissue level, and Evans blue extravasation. The appearances of cleaved caspase‐3 expression, TUNEL‐positive cells, and apoptotic morphology in cerebral tissues were associated with neurological deficit after SAH. JNK inhibition prevented c‐Jun phosphorylation and suppressed AQP1, MMP‐9, VEGF, and caspase‐3 activation, with concomitant diminution of neuronal injury, blood–brain barrier preservation, reduced brain swelling, and improved neurological deficit in rats after SAH. This study demonstrates a multitude of beneficial effects of JNK inhibition, including protection of the neurovascular unit in early brain injury after SAH. © 2007 Wiley‐Liss, Inc.
Vancomycin covalently bonded to titanium alloy prevents bacterial colonization
Authors: Antoci Valentin , King Samuel B. , Jose Binoy , Parvizi Javad , Zeiger Allen R. , Wickstrom Eric , Freeman Theresa A. , Composto Russell J. , Ducheyne Paul , Shapiro Irving M. , Hickok Noreen J. , Adams Christopher S. 
Published: April 2007

AbstractPeriprosthetic infection is a devastating consequence of implant insertion and can arise from hematogenous sources or surgical contamination. Microbes can preferentially colonize the implant surface and, by forming a biofilm, escape immune surveillance. We hypothesized that if an antibiotic can be tethered to a titanium alloy (Ti) surface, it will inhibit bacterial colonization, prevent biofilm formation, and avert late‐stage infection. To test this hypothesis, a Ti rod was covalently derivatized with vancomycin. Reaction efficiencies were evaluated by colorimetric and spectrophotometric measurements. The vancomycin‐modified surface was stable in aqueous solutions over extended time periods and maintained antibiotic coverage, even after press‐fit insertion into a cadaverous rat femora. When evaluated using fluorescently labeled bacteria, or by direct colony counts, the surface‐bound antibiotic prevented bacterial colonization in vitro after: (1) exposure to high levels of S. aureus; (2) extended incubation in physiological buffers; and (3) repeated bacterial challenges. Importantly, whereas the vancomycin‐derivitized pins prevented bacterial colonization, S. aureus adhered to control pins, even in the presence of concentrations of vancomycin that exceeded the strain MIC. These results demonstrate that we have effectively engineered a stable, bactericidal Ti surface. This new surface holds great promise in terms of mitigating or preventing periprosthetic infection. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:858–866, 2007
Effect of crosslinking, remelting, and aging on UHMWPE damage in a linear experimental wear model
Authors: Maher Suzanne A. , Furman Bridgette D. , Babalola Omotunde M. , Cottrell Jocelyn M. , Wright Timothy M. 
Published: April 2007

AbstractThe objective of this study was to establish the effect of postirradiation melting as a function of irradiation dose on the wear behavior and material characteristics of ultrahigh molecular weight polyethylene. Our hypothesis was that a low dose of irradiation followed by melting would have the same improved wear performance as is found with higher doses of irradiation, but without the disadvantages associated with reduced fracture toughness. The hypothesis was tested by measuring the wear performance (wear track area, incidence of pitting and delamination) in a linear doubly curved‐on‐flat cyclic test, material behavior (elastic modulus, fracture toughness), and aging response (density changes through the thickness) of the following materials: elevated crosslinked groups—radiated at 25, 65, and 120 kGy, melted, sterilized and aged; a melted group—melted, sterilized, and aged; and a control group—sterilized and aged. Our findings suggest that postirradiation melting, not the irradiation dose, dominates the material property changes and wear response. Melting ensured reduced modulus and therefore decreased contact stresses, superior wear performance, and good resistance to aging, even after low levels of irradiation (25 kGy). The low modulus of the 25 kGy elevated crosslinked group, coupled with increased fracture toughness compared to samples irradiated at higher doses and a resistance to aging not found in the melted group, support our hypothesis. A low dose of irradiation followed by heat treatment has the same beneficial effects in terms of improved wear performance, but without the disadvantages of reduced fracture toughness found with higher doses of irradiation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:849–857, 2007
Quantitative assessment of scaffold and growth factor‐mediated repair of critically sized bone defects
Authors: Oest Megan E. , Dupont Kenneth M. , Kong Hyun‐Joon , Mooney David J. , Guldberg Robert E. 
Published: April 2007

AbstractAn 8‐mm rat segmental defect model was used to evaluate quantitatively the ability of longitudinally oriented poly(L‐lactide‐co‐D,L‐lactide) scaffolds with or without growth factors to promote bone healing. BMP‐2 and TGF‐β3, combined with RGD‐alginate hydrogel, were co‐delivered to femoral defects within the polymer scaffolds at a dose previously shown to synergistically induce ectopic mineralization. A novel modular composite implant design was used to achieve reproducible stable fixation, provide a window for longitudinal in vivo micro‐CT monitoring of 3D bone ingrowth, and allow torsional biomechanical testing of functional integration. Sequential micro‐CT analysis showed that bone ingrowth increased significantly between 4 and 16 weeks for the scaffold‐treated defects with or without growth factors, but no increase with time was observed in empty defect controls. Treatment with scaffold alone improved defect stability at 16 weeks compared to nontreatment, but did not achieve bone union or restoration of mechanical function. Augmentation of scaffolds with BMP‐2 and TGF‐β3 significantly increased bone formation at both 4 and 16 weeks compared to nontreatment, but only produced bone bridging of the defect region in two of six cases. Histological evaluation indicated that bone formed first at the periphery of the scaffolds, followed by more limited mineral deposition within the scaffold interior, suggesting that the cells participating in the initial healing response were primarily derived from periosteum. This study introduces a challenging segmental defect model that facilitates quantitative evaluation of strategies to repair critically sized bone defects. Healing of the defect region was improved by implanting structural polymeric scaffolds infused with growth factors incorporated within RGD‐alginate. However, functional integration of the constructs appeared limited by continued presence of slow‐degrading scaffolds and suboptimal dose or delivery of osteoinductive signals. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:941–950, 2007
Self‐Assembled Structures in Block Copolymer Blends: SAXS, SANS and TEM Study
Authors: Holoubek Jaroslav , Baldrian Josef , Lal Jyotsana 
Published: April 2007

AbstractPhenomena associated with the order‐disorder transition, microdomain morphology and phase behavior of a deuterated block copolymer (BCP) blend I/II (where I is dPS‐block‐dPMMA and II is dPS‐block‐PI) were studied by SAXS, SANS and TEM. The studied, almost symmetric, copolymers differ essentially in microdomain morphology. One of them (I) is in disordered microdomain state, while the other (II) displays lamellar morphology at ordinary temperatures. Self‐assembled structures in blends were investigated as a function of concentration of the added microphase‐separated copolymer and temperature. The ODT positions were located in all the blends, the position of ODT depending only slightly on the concentration of the ordered copolymer. A systematic increase in long period D of the lamellar phase is observed with the growing content of the disordered copolymer. The evaluation of TEM shows the gradual diminishing of macrophase separated regions of disordered copolymer I with growing content of the lamellar copolymer II.magnified image
Initiator Efficiency of tert‐Alkyl Peroxyesters in High‐Pressure Ethene Polymerization
Authors: Buback Michael , Fischer Bart , Hinrichs Stefan , Jauer Stephan , Meijer John , Sandmann Johannes 
Published: April 2007

AbstractHigh‐pressure ethene polymerizations using thirteen tert‐alkyl peroxyester initiators, RC(CH3)2OOCOR′ (with R = methyl, ethyl, neo‐pentyl, tert‐butyl and R′ = methyl, i‐propyl, propyl, butyl, tert‐butyl, 2‐heptyl) have been carried out in a CSTR. The initiator efficiency f has been determined for each peroxyester at 2 000 bar over a range of temperatures, partly up to 250 °C. The highest initiator efficiencies, up to about f = 0.9, are observed for tert‐butyl peroxyesters, in which the R' species is a primary radical, as e.g., with tert‐butyl peroxypentanoate and tert‐butyl peroxyacetate. The lowest efficiency value, of about f = 0.37, occurs with tert‐butyl peroxypivalate. The radicals from initiator decomposition, R′COO· and RC(CH3)2O., may undergo β‐scission reactions to produce R′ radicals by decarboxylation and R radicals by “deacetonization”, respectively. In‐cage termination reactions between oxygen‐centered and carbon‐centered radicals essentially control initiator efficiency.magnified image
Chemoprevention of rat mammary carcinogenesis by black tea polyphenols: Modulation of xenobiotic‐metabolizing enzymes, oxidative stress, cell proliferation, apoptosis, and angiogenesis
Authors: Kumaraguruparan R. , Seshagiri P.B. , Hara Y. , Nagini S. 
Published: April 2007

AbstractChemoprevention of dietary constituents has emerged as a cost‐effective approach to control the incidence of breast cancer. The present study was therefore designed to evaluate the chemopreventive efficacy of black tea polyphenols (Polyphenon‐B) during the preinitiation phase of 7,12‐dimethylbenz[a]anthracene (DMBA) induced mammary carcinogenesis using xenobiotic‐metabolizing enzymes, cellular redox status, cell proliferation, apoptosis, and angiogenesis as biomarkers of chemoprevention. Intragastric administration of DMBA induced adenocarcinomas that showed enhanced activities of phase I carcinogen activation and phase II detoxification enzymes with increased lipid and protein oxidation and decrease in antioxidant status. This was associated with increased cell proliferation, angiogenesis, and evasion of apoptosis as revealed by upregulation of proliferating cell nuclear antigen (PCNA), Bcl‐2, and vascular endothelial growth factor (VEGF), and downregulation of Bax, caspase 3, and poly(ADP‐ribose) polymerase (PARP). Dietary administration of Polyphenon‐B effectively suppressed the incidence of mammary tumors as evidenced by modulation of xenobiotic‐metabolizing enzymes and oxidant–antioxidant status, inhibition of cell proliferation and angiogenesis, and induction of apoptosis. The present study provides evidence that Polyphenon‐B exerts multifunctional inhibitory effects on DMBA‐induced mammary carcinogenesis and suggests that it can be developed as a potential chemopreventive agent. © 2007 Wiley‐Liss, Inc.
Identifying incident cases of parkinsonism among veterans using a tertiary medical center
Authors: White Donna , Moore Suzanne , Waring Stephen , Cook Karon , Lai Eugene 
Published: April 2007

AbstractTo better understand the impact of incident Parkinson's disease (PD) on the Veteran's Health Administration (VHA) and to develop methods applicable to future epidemiological research, we performed a medical record review study at a tertiary referral VHA medical center. Searching the local data base, we identified 782 veterans with diagnostic codes for PD or secondary parkinsonism (SP) between 1998 and 2000. Based on structured medical record review, a movement disorders specialist confirmed diagnoses for incident parkinsonism cases. Among the 782, 191 incident parkinsonism cases were identified (100 PD, 75 SP, and 16 Parkinson's Plus). Incident PD cases were older at diagnosis (74.5 vs. 70.4 yr; P < 0.05) and more likely to be white (81% vs. 62; P < 0.07) than incident SP cases. Diagnostic codes were insufficient to distinguish between incident PD and SP (positive predictive value, 57% and 39%, respectively), and VHA sources failed to identify 21% of confirmed deaths among the incident PD cohort by November 2004. Although the large number of incident cases identified suggests PD is an important cause of disability among elderly VHA users, observed limitations of VHA sources for identifying incident PD cases and determining their vital status should be considered when designing future studies. © 2006 Movement Disorder Society
Defining mild cognitive impairment in Parkinson's disease
Authors: Caviness John N. , Driver‐Dunckley Erika , Connor Donald J. , Sabbagh Marwan N. , Hentz Joseph G. , Noble Brie , Evidente Virgilio Gerald H. , Shill Holly A. , Adler Charles H. 
Published: April 2007

AbstractOur purpose was to characterize a state of mild cognitive impairment (MCI) in Parkinson's disease (PD) (PD‐MCI) that would be analogous to the MCI that is posited as a precursor of Alzheimer's disease (AD). We categorized 86 PD subjects in a brain bank population as either cognitively normal (PD‐CogNL), PD‐MCI using criteria that included a 1.5 standard deviation or greater deficit upon neuropsychological testing consistently across at least one cognitive domain without dementia, and PD dementia (PD‐D) using DSM‐IV criteria. Twenty‐one percent of our PD sample met criteria for PD‐MCI, 62% were PD‐CogNL, and 17% had PD‐D. The mean duration of PD and MMSE scores of the PD‐MCI group were intermediate and significantly different from both PD‐CogNL and PD‐D. The cognitive domain most frequently abnormal in PD‐MCI was frontal/executive dysfunction followed by amnestic deficit. Single domain PD‐MCI was more common than PD‐MCI involving multiple domains. We conclude that a stage of clinical cognitive impairment in PD exists between PD‐CogNL and PD‐D, and it may be defined by applying criteria similar to the MCI that is posited as a precursor of AD. Defining PD‐MCI offers an opportunity for further study of cognitive impairment in PD and targets for earlier therapeutic intervention. © 2007 Movement Disorder Society
Entanglement Tightening and Stress Relaxation
Authors: O'Donnell Robert G. , Edward Graham H. 
Published: April 2007

AbstractThe contribution of entanglements to the modulus of a time independent polymer is satisfactorily accounted for by the C2/λ term in the Mooney‐Rivlin equation. On the other hand, the role of entanglements in time dependent polymers is less evident and seems to give rise to a non‐linear Mooney plot. A model is introduced which considers an entanglement as a topological knot that tightens with initial deformation and subsequently inhibits chain slippage. The observed maximum in a Mooney plot at small values of λ is predicted, and the experimental data of plasticised PVC polybutadiene and styrenebutadiene copolymer are fitted reasonably well.
Processing Aids: The Effect of Polymethyl Methacrylate on the Fusion of Rigid Poly(vinyl chloride)
Authors: Kosior E. I. , Stachurski Z. H. 
Published: April 2007

AbstractThe fusion process of a PVC dryblend, both with and without a PMMA processing aid, was studied in a Brabender Plasticorder over a range of mixer temperatures. charge masses and rotor speeds. The progress of fusion was monitored by the examination of the morphology of the PVC samples taken during different stages of the fusion process. The technique of examining the acetone‐swollen samples by optical microscopy before and after shearing,1 provided an insight to the mechanism of action of the PMMA processing aid. The study established that the PMMA processing aid modified both the inter‐grain coefficient of friction and the packed density which had a significant effect on the initiation of the fusion process. The fusion process of both PVC compounds, i.e. with and without PMMA processing aid, was shown to proceed via a comminution mechanism, where the PVC grains were randomly broken into sub‐grains and primary particle agglomerates. Concurrent with this breakdown, the cohesion of PVC agglomerates was observed.
An Experimental Study of the Thermodynamics of Rubber in Extension and Torsion
Authors: Mohsin Mahmood A. , Berry John P. , Treloar Leslie R. G. 
Published: April 2007

AbstractThe stress‐strain properties of three different rubbers have been measured using two different techniques, in order to evaluate the relative internal energy contribution to the total stress fe/f and the corresponding value of Me/M over a range of strain and temperatures. Two different experimental techniques have been designed; one is to allow measurement in simple extension of the length of a rubber sample in relation to the temperature at constant force, and the other is to measure the variation of torsional couple M in a cylinder of rubber (subjected to combined torsion about the axis and extension in the axial direction) with temperature. The thermoelastic results obtained for natural rubber and butyl rubber do not contain any surprising features, and are found to be in good agreement with other reported experimental results for these rubbers. Values of fe/f and Me/M obtained for cis‐trans polybutadiene rubber show different trends between the two techniques.
Homogeneous Polymerisation of Methylmethacrylate Initiated by Alkali Metal Salts of Methanol and t‐Butyl Alcohol in the Presence of Cryptands and Macrocyclic Crown Ether Compounds
Authors: Viguier Michel , Collet André , Schué François , Mula Bernard 
Published: April 2007

AbstractThe polymerisation of methylmethacrylate initiated by alkali alkoxides is greatly promoted in the presence of macrocyclic compounds, cryptands and crown ethers. The solubility in toluene and the reactivity of alkoxides is enhanced by these complexing agents. Polymerisations have been carried out in a non‐polar solvent in the homogeneous phase.
Reactions of Living Polytetrahydrofuran with Amines V ‐ Tertiary Amine Terminated Polybutadienes; The Synthesis of Novel Ionically Linked Block Copolymers
Authors: Hurley J. , Richards D. H. , Stewart M. J. 
Published: April 2007

AbstractThe reactions of mono‐ and difunctional tertiary amine ended polybutadienes with mono‐ and difunctional living cationic poly THF have been studied. It is shown that the reaction to form quaternary ammonium linking groups takes place rapidly in all cases, and AB. ABA, BAB and (AB) block copolymers have been prepared. The efficiency of the process is extremely high and the degree of conversion is essentially controlled by the efficiency with which the terminal tertiary amine groups can be introduced on to the polybutadiene. The block copolymers show anomalous behaviour on gel permeation chromatography columns and this has been related to a specific interaction of the created ionic groups with polar species on the column packing. This effect is greatest with (AB) block copolymers where substantial proportions are retained indefinitely on the columns.
The Initial Thermal Stability of Poly(vinyl chloride)
Authors: Gracia Martinez J. A. , Gutierrez Fernandez F. , Manley T. R. 
Published: April 2007

AbstractThe use of a fluidised bed reactor and a conductivity cell provide a technique for the study of degradation of PVC with greatly increased sensitivity. The kinetics of the reaction may be studied at 350 K and for small (1%) amounts of degradation. The effects of diffusion within the particles may be distinguished from that of diffusion in the surrounding atmosphere. The influence of temperature and particle size and sintering were examined. The catalytic effect of HCl was confirmed and an apparent activation energy of 29 kcal mol−1 was observed.