bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early lesions of osteochondrosis in the distal tibia of foals
Authors: Olstad Kristin , Ytrehus Bjørnar , Ekman Stina , S. Carlson Cathy , Dolvik Nils I. 
Published: April 2007

AbstractMaterial available for research into osteochondrosis (OC) in humans tends to represent chronic lesions. Comparative studies of early lesions in young animals are, therefore, important in clarifying the pathogenesis of OC in humans. Recent studies in pigs provide strong evidence that lesions of articular OC are associated with a focal failure in the cartilage canal vascular supply to epiphyseal growth cartilage (articular–epiphyseal cartilage complex excluding the articular cartilage). The purpose of the present study was to examine histological sections from a specific predilection site for articular OC in the distal tibia of a large number of young foals to determine if the same is true in horses. Material from the distal tibiae of 100 foals aged from 191 days of gestation to 153 days old was collected from routine submissions of fetuses and foals for post mortem examination. The tibiae were band‐sawed into slabs, and selected slabs were processed for histology, stained with hematoxylin and eosin, and examined using light microscopy. Early subclinical developmental stages of OC were found in the most common site for clinical OC lesions of horses in nine of 100 foals aged 12 to 122 days old. All lesions contained areas of chondrocyte necrosis that were associated with cartilage canal necrosis in five of nine foals. Five of these foals also had focal disruption of enchondral ossification at the chondro–osseous junction in the same site. Early lesions purported to play a role in the initial stages of articular OC in the distal tibia of horses were characterized by chondrocyte necrosis and likely occurred secondary to a failure of cartilage canal vascular supply to epiphyseal growth cartilage. The similarities in appearance between early lesions of piglets and foals suggest that information gained in one species may be transferable to others, including humans. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1094–1105, 2007
Improved accuracy of navigated drilling using a drill alignment device
Authors: Kendoff Daniel , Citak Musa , Gardner Michael J. , Stübig Timo , Krettek Christian , Hüfner Tobias 
Published: April 2007

AbstractDrilling procedures are common in orthopedic surgery and are one specific task that may be aided by computer‐assisted navigation. However, the inherent flexibility of drill bit bending may make this the limiting factor in achieving acceptable accuracy when using these systems. We designed an alignment device that was fit to a standard orthopedic drill that allowed an extension of the stabilizing point of a drill bit. In foam blocks with a similar density as cancellous bone, 208 total navigated drilling trials were performed, using four different sized drill bits (2.5, 3.2, 3.5, and 4.5 mm) with and without the alignment device. Drilling tracts of 80 mm were made towards an intended target on the other side of the block. Reduction in deviation from the intended target was significantly improved with the use of the guide, ranging from 33% to 45% for the four drill sizes. For the trails using the alignment device, the 2.5‐mm drill bit was significantly less accurate than the three larger drills. Our results demonstrate that the use of external devices to augment drill bit stabilization can improve drilling accuracy. This may have particular importance when using navigation systems to drill into small anatomic confines. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:951–957, 2007
Water/Ethanol Selectivity of New Organic‐Inorganic Hybrid Membranes Fabricated from Poly(vinyl alcohol) and an Oligosilane
Authors: Uragami Tadashi , Yanagisawa Shohei , Miyata Takashi 
Published: April 2007

AbstractTo control the swelling of PVA membranes, mixtures of PVA and an inorganic oligosilane were prepared using sol‐gel reactions to yield new PVA/oligosilane hybrid membranes. In the separation of an ethanol/water azeotropic mixture during pervaporation, the effect of the oligosilane content on the water/ethanol selectivity of PVA/oligosilane hybrid membranes was investigated. The water/ethanol selectivity of PVA/oligosilane hybrid membranes was higher than that of PVA membranes, but the water/ethanol selectivity of hybrid membranes decreased with increasing oligosilane content. In order to increase the water/ethanol selectivity, PVA/oligosilane hybrid membranes were annealed. The water/ethanol selectivity of annealed PVA/oligosilane hybrid membranes was greater than un‐annealed hybrid membranes, and significantly governed by the oligosilane content, which could be attributed to both sorption and diffusion selectivities. The relationship between the structure of un‐annealed and annealed PVA/oligosilane hybrid membranes along with permeation and separation characteristics of an ethanol/water azeotropic mixture during pervaporation are discussed in detail.magnified image
Synthesis of Saccharide‐Terminated Poly(ε‐caprolactone) via Michael Addition and ‘Click’ Chemistry
Authors: Xu Ning , Lu Feng‐Zhu , Du Fu‐Sheng , Li Zi‐Chen 
Published: April 2007

AbstractMaleimido‐terminated PCL (M‐PCL) and alkyne‐terminated PCL (A‐PCL) are prepared by the ring‐opening polymerization of ε‐caprolactone with N‐hydroxyethyl maleimide and 4‐pentyn‐1‐ol as initiators catalyzed by tin(II) trifluoromethane sulfonate at 25 °C, respectively. A series of saccharide‐terminated PCLs have also been synthesized under mild conditions by two chemical strategies: 1). Michael addition of M‐PCL and amino‐containing maltose, and 2). a ‘click’ reaction of A‐PCL and azide‐containing saccharide. The amphiphilic nature of these maltose‐terminated PCLs make self‐assembly into aggregates in water possible. These aggregates have been characterized by transmission electron microscopy and dynamic light scattering measurements.magnified image
New Insights into Nickel(II), Iron(II), and Cobalt(II) Bis‐Complex‐Based Metallo‐Supramolecular Polymers
Authors: Chiper Manuela , Meier Michael A. R. , Kranenburg Johannes M. , Schubert Ulrich S. 
Published: April 2007

AbstractOne of the most important characterization methods for macromolecules is SEC. The main difficulty for this type of measurements concerning metallo‐supramolecular polymers based on terpyridines is related to the interaction between the charged supramolecular species and the SEC column material. In this paper, we report new studies on the characterization and the stability of supramolecular polymers based on terpyridine metal complexes utilizing SEC. The main aspects concerning the equilibrium between complexed and uncomplexed species are discussed in detail. The present study reveals a strong relationship between the binding strength of the metal ion used and the stability of the terpyridine metal complex during the SEC measurements, which is in agreement with previously published results regarding the stability of small terpyridine metal complexes in solution. These results can lead to improved analytic possibilities and to a better fundamental understanding of the mentioned metallo‐supramolecular polymers. Furthermore, the prepared chain‐extended supramolecular‐polymer was analyzed by depth‐sensing indentation proving an increase in elastic modulus in comparison with the starting material.magnified image
Effect of Structure of Large Aromatic Molecules Grafted onto Cellulose on Hydrolysis of the Glycosidic Linkages
Authors: Karst David , Yang Yiqi 
Published: April 2007

AbstractMolecular modeling is used to explain how grafting various molecules that contain large aromatic structures and different reactive groups onto cellulose dramatically increases the hydrolysis of the glycosidic linkages of cellulose. Hydrolysis is found to increase with the increasing size of the molecule grafted to cellulose, and experiments support this finding. A larger substituent on cellulose increases hydrolysis by causing the hydrolyzed cellulose structure to be more stable compared to hydrolyzed cellulose grafted to a smaller substituent. A larger substituent forms stronger interactions with cellulose and has a greater ability to reduce the mobility of the cleaved cellulose chain to which it is bonded, which allows the cleaved cellulose to form stronger cellulose‐cellulose interactions after hydrolysis. A substituent on the C6 position of cellulose increases hydrolysis to a greater extent than does the same substituent on the C3 or C2 position.magnified image
Chromatin changes on the GSTP1 promoter associated with its inactivation in prostate cancer
Authors: Okino Steven T. , Pookot Deepa , Majid Shahana , Zhao Hong , Li Long‐Cheng , Place Robert F. , Dahiya Rajvir 
Published: April 2007

AbstractGlutathione‐S‐transferases (GSTs) are metabolic enzymes that help detoxify and eliminate harmful chemicals. In prostate tumors, expression of GST π (encoded by GSTP1) is frequently lost because of promoter hypermethylation. Here we analyze the native GSTP1 promoter in cancerous and noncancerous human prostate cells to identify structural features associated with its cancer‐related transcriptional silencing. We find that in noncancerous prostate cells (RWPE‐1 and PWR‐1E) GSTP1 is constitutively expressed, not methylated, highly accessible, bound by transcription factors and associated with histones with activating modifications (histone H3 methylated at lysine 4 and acetylated histones H3 and H4). In contrast, in cancerous prostate cells (LNCaP) GSTP1 is not expressed, extensively methylated, inaccessible, lacks bound transcription factors and is not associated with histones with activating modifications. We do not detect significant levels of histones with repressive modifications (histone H3 methylated at lysine 9 or 27) on GSTP1 in any cell line indicating that they are not associated with cancer‐related GSTP1 silencing. Treatment of LNCaP cells with 5‐azacytidine restores activating histone modifications on GSTP1 and reactivates transcription. We conclude that, in the process of prostate carcinogenesis, activating histone modifications on GSTP1 are lost and the DNA becomes methylated and inaccessible resulting in transcriptional silencing. © 2007 Wiley‐Liss, Inc.
Construction and validation of a Parkinson's disease mutation genotyping array for the Parkin gene
Authors: Clark Lorraine N. , Haamer Eneli , Mejia‐Santana Helen , Harris Juliette , Lesage Suzanne , Durr Alexandra , Bs Sabine Janin , Hedrich Katja , Louis Elan D. , Cote Lucien J. , Andrews Howard , Fahn Stanley , Waters Cheryl , Ford Blair , Frucht Steven , Scott William , Klein Christine , Brice Alexis , Roomere Hanno , Ottman Ruth , Marder Karen 
Published: April 2007

AbstractParkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age‐related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early‐onset PD case probands and 45 relatives. © 2007 Movement Disorder Society
Abnormality of motor cortex excitability in peripherally induced dystonia
Authors: Bohlhalter Stephan , Leon‐Sarmiento Fidias E. , Hallett Mark 
Published: April 2007

AbstractIt is widely accepted that peripheral trauma such as soft tissue injuries can trigger dystonia, although little is known about the underlying mechanism. Because peripheral injury only rarely appears to elicit dystonia, a predisposing vulnerability in cortical motor areas might play a role. Using single and paired‐pulse pulse transcranial magnetic stimulation, we evaluated motor cortex excitability of a hand muscle in a patient with peripherally induced foot dystonia, in her brother with craniocervical dystonia, and in her unaffected sister, and compared their results to those from a group of normal subjects. In the patient with peripherally induced dystonia, we found a paradoxical intracortical facilitation at short interstimulus intervals of 3 and 5 milliseconds, at which regular intracortical inhibition (ICI) occurred in healthy subjects. These findings suggest that the foot dystonia may have been precipitated as the result of a preexisting abnormality of motor cortex excitability. Furthermore, the abnormality of ICI in her brother and sister indicates that altered motor excitability may be a hereditary predisposition. The study demonstrates that the paired‐pulse technique is a useful tool to assess individual vulnerability, which can be particularly relevant when the causal association between trauma and dystonia is less evident. © 2007 Movement Disorder Society
Rate of clinical progression in Parkinson's disease. A prospective study
Authors: Schrag Anette , Dodel Richard , Spottke Annika , Bornschein Bernhard , Siebert Uwe , Quinn Niall P. 
Published: April 2007

AbstractFew prospective data on the clinical progression of Parkinson's disease (PD) in patient groups outside treatment trials in selected patients are available, and controversy exists on the rate of clinical disease progression with advancing disease. In this study, we investigated the rate of clinical progression of PD in a clinic‐based sample of 145 patients over 1 year and in a community‐based sample of 124 patients over 4 years. Depending on the sample and clinical scale used, mean deterioration of motor and disability scores ranged from 2.4 to 7.4% of the maximum possible score per year, and standard deviations indicated that there was considerable variability of progression rates between individuals. The progression of motor scores decreased with follow‐up over 4 years and significantly decreased in more advanced disease stages. Deterioration of disability scores did not differ between disease stages; this may reflect the increasing rate of disease complications, which contribute to increasing disability in addition to motor impairment alone, in more advanced disease. Thus, motor fluctuations, hallucinations, depression, memory problems, and bladder symptoms were all reported more often at follow‐up in the community‐based sample (all P < 0.01), and dyskinesias, motor fluctuations, falls, and hallucinations were more common and cognitive and depression scores worse in higher disease stages in the clinic‐based sample (all P < 0.001). We conclude that progression of motor scores in PD decreases with advancing disease in PD. However, disability continues to deteriorate with advancing disease and with the development of disease complications that are likely to be related to additional extrastriatal pathology. © 2007 Movement Disorder Society
Dielectric Response of Commercial Polycarbonate
Authors: Pratt Graeme J. , Smith Michael J. A. 
Published: April 2007

AbstractContour maps of complex relative permittivity within the range ‐ 175°C to 195°C and 0.1 Hz to 3 MHz are presented for basic and ultraviolet resistant grades of a commercial poly(dian carbonate). Several dispersion regions common to both materials are identified, together with an additional region at high temperatures in the ultraviolet resistant material. Comparisons are made with earlier investigations, and possible sources are suggested for each dispersion.
The Effect of Uncertainties in the Kuhn‐Mark‐Houwink‐Sakurada Constants on the Quantitative Analysis by Gel Permeation Chromatography
Authors: Deniz Veli , Güven Olgun 
Published: April 2007

AbstractThe effect of uncertainties in Kuhn‐Mark‐Houwink‐Sakurada (KMHS) constants on weight average and number average molecular weights and molecular weight distributions of some poly(ethyl methacrylate) samples have been investigated. Parameters were computed by the Weiss and Cohn‐Ginsberg method. Whereas errors introduced in Mw, Mn and HI values due to uncertainty in the K value are insignificant, uncertainties in the KMHS exponent present a serious problem. Deviations of ± 3% around a particular a value cause a ± 20% error in Mw and ± 15% error in Mn, values. The effect of deviations in the KMHS exponent on the HI values is dependent on the polydisperity of the sample investigated.
Chemical Evidence for Remnant cis Bonds in ‘trans’‐Polyacetylene
Authors: Gibson Harry W. , Weagley Ronald J. , Mosher Ralph A. , Kaplan Samuel , Prest William M. , Epstein Arthur J. 
Published: April 2007

AbstractResidual 740 cm−1 absorption, a signature of the cis isomer, is always observed to the extent of ± 5% in ‘trans’‐polyacetylene prepared thermally from the Shirawaka cis isomer, regardless of the temperature or duration of treatment. The view that a significant fraction of the ‘remnant cis bonds’ is in the form of or can be converted to cisoid single bonds is supported by the results of a Diels‐Alder trapping experiment with maleic anhydride. The presence of the remnant cis linkages leads to simple rationalisation of free radical (soliton) generation and diffusion, conjugation lengths determined by Raman spectroscopy, x‐ray structural evolution and electrical conductivity.
Dichlorocarbene Modified Natural Rubber
Authors: Howard Bradbury J. , Senake Perera M. C. 
Published: April 2007

AbstractNatural rubber dissolved in chloroform was reacted with aqueous NaOH using a phase transfer reagent or with solid NaOH to produce dichlorocarbene modified natural rubber. The 13C n.m.r. spectrum of the 100% modified natural rubber showed the presence of diastereoisomers due to two modes of addition of dichlorocarbene units as previously observed in epoxidation. There was no evidence of cis‐trans iso‐merisation, occurrence of other side reactions or of chain scission (shown by measurements of intrinsic viscosity). Partially dichlorocarbene modified natural rubber gave rise to a complex 13C n.m.r. spectrum that was assigned in terms of triad structures (for methylene carbon atoms)and pentad structures (for olefinic carbon atoms). Using 13C n.m.r. and measurements of glass transition temperature, it was found that reaction with aqueous NaOH and with solid NaOH both gave a random distribution of dichlorocarbene units, as compared with a block copolymer structure observed by previous workers with dichlorocarbene modified polybutadiene. The thermal stability of natural rubber is intermediate between that of the more stable 100% dichlorocarbene modified rubber and the less stable partially modified rubber.
13C Nuclear Magnetic Resonance Studies of Phenol‐Formaldehyde Resins 1 ‐ Model Compounds
Authors: Pethrick Richard A. , Thomson Barry 
Published: April 2007

AbstractHigh resolution 13C n.m.r. data are presented for a series of model compounds generated by the acid catalysed reaction of either phenol or cresol with formalin. The pure compounds prepared for this study allow unambiguous identification of features associated with ortho‐ortho, ortho‐para and para‐para linked moieties, and hence allow analysis of the sequence structure in the typical resin. To aid assignment of the spectra a comparison is made between the predictions of the spectra using simple additivity relationships and the experimentally observed shifts. It is found that the differences between theory and experiment vary systematically with structure, and averaged correction factors are presented for various characteristic structures.
Differential Scanning Calorimetry Cure Studies of Tetra‐N‐glycidyldiaminodiphenylmethane Epoxy Resins 3 ‐ Reaction with Dicyandiamide
Authors: Barton John M. , Greenfield David C. L. 
Published: April 2007

AbstractContinuation of work on the curing characteristics of an epoxy resin which is widely used as a composite matrix is reported. Results are given of study of the cure of the resin with dicyandiamide as hardener and diuron as accelerator, using differential scanning calorimetry to monitor the cure. The effect of diuron on the cure of the resin with an aromatic amine curing agent is also described. Distinctive effects of composition are found and values of the apparent activation energy of the curing reaction are derived.
Structural Versatility of Homo‐peptides from Cα,α‐dialkylated Glycines
Authors: Toniolo Claudio 
Published: April 2007

AbstractA theoretical and experimental analysis of the preferred conformations of homo‐peptides from Cα,α‐dialkylated glycines revealed that these compounds are characterised by a marked structural versatility. Fully extended (C5‐conformations). folded (of theβ‐bend type), and 310‐helical structures are adopted as a function of side‐chain nature. Dimethylated and cyclic side chains favour folded and helical structures, whereas diethylated and longer acyclic side chains favour the fully extended structure. By means of conformational energy calculations the preferred screw sense of the helical structure of homo‐peptides from a representative chiral acyclic residue is also anticipated.
Direct Mass Spectrometry of Polymers
Authors: Montaudo Giorgio 
Published: April 2007

AbstractThe analysis of polymers by direct mass spectrometry is reviewed, and the principles of the method and some experimental aspects are discussed. Both pyrolysis and desorption methods are described. The mass spectrometric method provides the characterisation of intractable materials and their detection at the submicrogram level; the simultaneous identification and detection of additives or oligomers contained in polymer samples; the identification of components of polymer mixtures, the sequential analysis of copolymers; the identification of the primary thermal fragmentation products of polymers. Direct mass spectrometry has been widely applied to the structural analysis of synthetic and natural polymers. Published work covers nearly all classes of polymers.
Effects of Ultrasonic Vibration on the Electroinitiated Copolymerisation of Styrene and Isoprene
Authors: Akbulut Ural , Toppare Levent , Yurttaş B. 
Published: April 2007

AbstractCopolymerisation of styrene and isoprene by constant potential electrolysis in dichloromethane was achieved at different polymerisation potentials. Effect of ultrasonic vibration on the rate and the yield of polymerisation has been discussed. The composition of the copolymers was found to be affected by the vibration as well as the polymerisation potential (Epol). At Epol=+3.30 V we found that r1=r2 and mole percents of isoprene and styrene in copolymer were equal to each other. Equality was also observed on reacted monomer concentrations, at that potential, which can be called critical polymerisation potential. At Epol values above or below the critical polymerisation potential none of the above‐mentioned properties were equal. Monomer reactivity ratios were determined by the integrated Lewis‐Mayo equation. Ultrasonic vibration as well as polymerisation potential was found to affect reactivity ratios.
Recent Advances with Glycidylamine Resins
Authors: Thoseby Michael R. , Dobinson Bryan , Bull Christopher H. 
Published: April 2007

AbstractA new procedure for the glycidylation of aromatic amines has been developed recently, which leads to resins of lower viscosity, longer shelf‐life and higher purity than methods used previously. Resins made by the new process show considerable processing and applications advantages over those made by earlier methods. The new process has also made accessible high purity glycidyl derivatives of amines which have hitherto proved difficult to glycidylate effectively.