bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation and cell culture studies on block copolymers prepared by ring opening polymerization of ϵ‐caprolactone in the presence of poly(ethylene glycol)
Authors: Huang Ming‐Hsi , Li Suming , Hutmacher Dietmar Werner , Schantz Jan‐Thorsten , Vacanti Charles Alfred , Braud Christian , Vert Michel 
Published: April 2004

AbstractPoly(ϵ‐caprolactone) (PCL) and its block copolymers with poly(ethylene glycol) (PEG) were prepared by ring‐opening polymerization of ϵ‐caprolactone in the presence of ethylene glycol or PEG, using zinc metal as catalyst. The resulting polymers were characterized by various analytical techniques such as 1H NMR, SEC, DSC, IR, X‐ray, ESEM, and CZE. PCL/PEG copolymers with long PCL chains presented the same crystalline structure as PCL homopolymer, whereas PEG‐bearing short PCL blocks retained the crystalline structure of PEG and exhibited an amphiphilic behavior in aqueous solutions. Degradation of PCL and PCL/PEG diblock and triblock copolymers was realized in a 0.13 M, pH 7.4 phosphate buffer at 37°C. The results indicated that the copolymers exhibited higher hydrophilicity and degradability compared with the PCL homopolymer. Large amounts of PEG were released from the bulk after 60 weeks' degradation. In vitro cell culture studies were conducted on scaffolds manufactured via solid free form fabrication by using primary human and rat bone marrow derived stromal cells (hMSC, rMSC). Light, scanning electron, and confocal laser microscopy, as well as immunocytochemistry, showed cell attachment, proliferation, and extracellular matrix production on the surface, as well as inside the scaffold architecture. Copolymers showed better performance in the cell culture studies than the PCL homopolymer. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 417–427, 2004
Modulation of differentiation and mineralization of marrow stromal cells cultured on biomimetic hydrogels modified with Arg‐Gly‐Asp containing peptides
Authors: Shin Heungsoo , Zygourakis Kyriacos , Farach‐Carson Mary C. , Yaszemski Michael J. , Mikos Antonios G. 
Published: April 2004

AbstractWe synthesized biomimetic hydrogels modified with an osteopontin‐derived peptide (ODP) and used them as a substrate for in vitro culture of marrow stromal cells (MSCs) to investigate the effect of the biomimetic surface on differentiation of MSCs into osteoblasts. Proliferation and biological assays for 16 days proved that MSCs became differentiated into osteoblasts secreting osteogenic phenotypic markers such as alkaline phosphatase (ALP), osteopontin, and mineralized calcium. In addition, there was an additive effect of the cell‐binding peptide on differentiation and mineralization of MSCs cultured in the presence of soluble osteogenic supplements in cell culture media. For example, calcium content at day 16 on peptide‐modified hydrogels was significantly higher than on tissue culture polystyrene. Two general trends were observed: (1) proliferation of MSCs decreased as the amount of differentiation markers increased, and (2) higher peptide concentrations accelerated the differentiation of MSCs. On the hydrogel modified with ODP, ALP activity exhibited a maximum value of 36.7 ± 4.2 pmol/cell/h at day 10 for the concentration of 2 μmol/g while the culture time needed for maximum ALP activity occurred on day 13 for the lower concentrations. On the same hydrogel, the calcium content at day 10 was 21.4 ± 2.3 ng/cell for the peptide concentration of 2 μmol/g and 1.0 ± 0.3 ng/cell for 1.0 μmol/g. We used Gly‐Arg‐Gly‐Asp‐Ser (GRGDS) for modification of the hydrogel as a comparison to the results with ODP. However, osteoblast development was not significantly affected by the nature of the binding peptide sequences. These results suggest that MSC function can be modulated by variation of the peptide concentration in biomimetic hydrogels used for scaffold‐based bone tissue engineering. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 535–543, 2004
Gentamicin release from two‐solution and powder–liquid poly(methyl methacrylate)‐based bone cements by using novel pH method
Authors: Merkhan Imad K. , Hasenwinkel Julie M. , Gilbert Jeremy L. 
Published: April 2004

AbstractThe release of gentamicin as a function of time was measured for Palacos and two‐solution bone cements by using a novel pH technique. The pH of an aqueous solution of gentamicin is a function of the gentamicin concentration and it decreases linearly over concentrations of 0.0–0.1 wt %. Therefore, a new, direct, and inexpensive in vitro technique was developed based on continuous readings of the pH in phosphate‐buffered saline (PBS) at 37°C to determine the release kinetics of gentamicin from poly(methyl methacrylate) (PMMA)‐based bone cement. In addition, this method was used to compare the release profiles of Palacos R‐40 bone cement with a two‐solution bone cement developed in our laboratory and loaded with two different concentrations of gentamicin sulfate. Finally, the pH‐based method was used to track the elution of gentamicin in both mixed and static conditions to determine the effect of mixing on the diffusion of gentamicin out of the cement. It was found that Palacos R‐40 released 4.95 ± 0.22 wt % of its gentamicin after 24 h in PBS solution. This data compares favorably with previously reported values of gentamicin elution from Palacos R‐40, which ranged from 3 to 8 wt % of the total amount of incorporated gentamicin, depending on the size and the surface area of the samples. The results show that Palacos samples released 4.84 ± 0.27 mg after 24 h, a two‐solution cement loaded with an equivalent concentration of gentamicin sulfate released 3.81 ± 0.52 mg, and two‐solution cement loaded with twice the concentration of Palacos released 5.53 ± 0.26 mg of gentamicin. A higher percentage of release was recorded from Palacos than from the two‐solution bone cement, and the effect of PBS mixing conditions on the release kinetics was only significant in the early stages of release and not at 24 h. It was concluded that monitoring the pH is an effective technique to measure gentamicin release from PMMA‐based bone cements in PBS solution. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 577–583, 2004
Micromechanical analysis of dentin/adhesive interface by the finite element method
Authors: Misra Anil , Spencer Paulette , Marangos Orestes , Wang Yong , Katz J. Lawrence 
Published: April 2004

AbstractThe interfacial microstructure and spatial distribution of the modulus of elasticity have a profound effect on load transfer at the dentin/adhesive (d/a) interface. The microstructure is influenced by the varying degree of demineralization of intertubular and peritubular dentin during etching as well as the depth of adhesive penetration into the hybrid layer. These factors lead not only to a unique microstructure in the vicinity of the dentinal tubules, but also to a mechanically graded hybrid layer. This article investigates the micromechanical stress distribution at a d/a interface with the use of finite element analysis (FEA). Such analysis is now feasible given the newly measured moduli of elasticity at micro‐ and nanoscales. The results indicate that the morphological and micromechanical properties of the d/a interface affects the stress field such that the fracture/failure is likely to initiate in the stress‐concentration zone of peritubular dentin next to the hybrid/exposed‐collagen layer. The results suggest that devising a full‐depth high modulus hybrid layer may considerably reduce the stress concentration zone and the magnitude of stress concentration in the peritubular dentin next to the hybrid/exposed‐collagen layer. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 56–65, 2004
Effects of water storage of E‐glass fiber reinforced denture base polymers on residual methyl methacrylate content
Authors: Bayraktar Gulsen , Duran Ozlem , Bural Canan , Guvener Bora 
Published: April 2004

AbstractThis study investigated the effect of water storage on residual methyl methacrylate (MMA) content of continuous E‐glass fiber (Wetrotex International) reinforced denture base polymers. Heat‐polymerization (short‐ and long‐term boiling and conventional curing cycle using Meliodent™), autopolymerization (processed in air at room temperature and in water at 60°C with the use of Meliodent Rapid Repair™), and microwave‐polymerization (3 min at 500 W with the use of Acron MC™) were employed. The residual MMA contents of 120 specimens were analyzed by high‐performance liquid chromatography at deflasking (control) and after water (37°C) storage of 1 day, 1 week, and 1 month. Bonferroni's pairwise comparison test was used for statistical analysis. Significant reduction were determined only in the long‐term terminal boiled heat‐polymerized test group at the end of 1 day (p < 0.01), 1 week (p < 0.05) and also 1 month of water storage (p < 0.01). Significant reduction in autopolymerized test groups started even after 1 week of water storage (p < 0.05). Microwave‐polymerized test groups did not show a significant residual MMA reduction in all time intervals (p > 0.05). The polymerization methods and cycles applied to the glass fiber reinforced denture base polymers influence both the content and the reduction of residual MMA after water storage. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 161–166, 2004
A precise boundary element method for macromolecular transport properties
Authors: Aragon Sergio 
Published: April 2004

AbstractA very precise boundary element numerical solution of the exact formulation of the hydrodynamic resistance problem with stick boundary conditions is presented. BEST, the Fortran 77 program developed for this purpose, computes the full transport tensors in the center of resistance or the center of diffusion for an arbitrarily shaped rigid body, including rotation‐translation coupling. The input for this program is a triangulation of the solvent‐defined surface of the molecule of interest, given by Connolly's MSROLL or other suitable triangulator. The triangulation is prepared for BEST by COALESCE, a program that allows user control over the quality and number of triangles to describe the surface. High numerical precision is assured by effectively exact integration of the Oseen tensor over triangular surface elements, and by scaling the hydrodynamic computation to the precise surface area of the molecule. Efficiency of computation is achieved by the use of public domain LAPACK routines that call BLAS Level 3 hardware‐optimized subroutines available for most processors. A protein computation can be done in less than 10 min of CPU time in a modern Pentium IV processor. The present work includes a complete analysis of the sources of error in the numerical work and techniques to eliminate these errors. The operation of BEST is illustrated with applications to ellipsoids of revolution, and Lysozyme, a small protein. The typical numerical accuracy achieved is 0.05% compared to analytical theory. The numerical precision for a protein is better than 1%, much better than experimental errors in these quantities, and more than 10 times better than traditional bead‐based methods. © 2004 Wiley Periodicals, Inc. J Comput Chem 9: 1191–1205, 2004
GAD67 and GAD65 mRNA and protein expression in cerebrocortical regions of elderly patients with schizophrenia
Authors: Dracheva Stella , Elhakem Sharif L. , McGurk Susan R. , Davis Kenneth L. , Haroutunian Vahram 
Published: April 2004

Abstractγ‐Aminobutyric acid (GABA), the principal inhibitory neurotransmitter of CNS, has been consistently implicated in the pathophysiology of schizophrenia. GABA is synthesized from glutamate by the enzyme glutamic acid decarboxylase (GAD). Two isoforms of GAD have been identified and have been named GAD65 and GAD67 based on their apparent molecular weights. In this study, GAD65 and GAD67 mRNA and protein levels were measured by using real‐time RT‐PCR and immunoblotting, respectively, in post‐mortem brain tissue from the dorsolateral prefrontal cortex (DLPFC) and the occipital cortex of the elderly persons with schizophrenia and matched normal controls. In addition, the mRNA expression of GAT‐1, one of the principal transporters of GABA, was also studied in the same subjects. Expression of GAD65 and GAD67 mRNA in the DLPFC and in the occipital cortex was significantly elevated in patients with schizophrenia, whereas the expression of the corresponding proteins and GAT‐1 mRNA was unchanged. Although the levels of GAD65 and GAD67 messages were increased in schizophrenia subjects, the proportion of the two GAD isoforms remained constant in controls and schizophrenics. In the human DLPFC, GAD65 mRNA was found to be expressed significantly less than the message for GAD67, approximately 16% of that observed for GAD67. On the contrary, the abundance of GAD65 protein in the DLPFC was about 350% of that observed for GAD67. The results suggest a substantial dysregulation of GAD mRNA expression in schizophrenia and, taken together with the results of protein expression studies, raise the possibility that both cortical and subcortical GABA function may be compromised in the disease. © 2004 Wiley‐Liss, Inc.
Inhibition of methyl linoleate autoxidation by phenolics and other related compounds under mild oxidative conditions
Authors: Dávalos Alberto , Bartolomé Begoña , Gómez‐Cordovés Carmen 
Published: April 2004

AbstractMethyl linoleate (MeLo) is a commercially available substrate widely used for studying the inhibitory properties of pure compounds and plant extracts against lipid oxidation. In this paper, 13 phenolic (benzoic and cinnamic acids, aldehydes and derivatives, and flavonoids) and other related compounds (butylated hydroxyanisole, butylated hydroxytoluene and tocopherols) as well as nine complex mixtures rich in phenolics (wines) or tocopherols (soybean oil extracts) were assayed for their inhibitory activity against MeLo autoxidation under mild conditions (40 °C, darkness and atmospheric pressure). Samples were also assayed for their free radical‐scavenging capacity against 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•). Protocatechuic aldehyde, a compound that has not been previously evaluated by either of the two methods, showed the highest antioxidant activity. Some variations in the antioxidant ranking for some compounds were found between our results and those obtained by other authors using accelerated conditions for MeLo oxidation. Antioxidant activity of wines and soybean oil extracts was related to their richness in phenolics and tocopherols respectively. Correlation between antioxidant capacity measured by the MeLo and DPPH• methods was found for wines but not for the other samples studied. Therefore the measure of the free radical‐scavenging capacity of a compound is not always a reliable indicator of its lipid oxidation inhibitory ability. Copyright © 2004 Society of Chemical Industry
Pre‐harvest calcium treatments in relation to the respiration rate and ethylene production of ‘Golden Smoothee’ apples
Authors: Recasens I , Benavides A , Puy J , Casero T 
Published: April 2004

AbstractMultivariate procedures were used to evaluate the effect of different pre‐harvest calcium treatments on the changes of respiratory rate and ethylene production in apples both at harvest and after extended cold storage. The study was carried out over two years on ‘Golden Smoothee’ apple trees from Lleida (Spain). Trees were sprayed with a calcium chloride based formulation (STOPIT) at a concentration of 1% (v/v). The first (6 applications) and second (12 applications) treatments began 60 days after full bloom (DAFB) and were repeated at intervals of 15 and 7 days respectively. After harvesting, the fruit was stored for 4 and 6 months under controlled ultra‐low oxygen atmosphere conditions (CA‐ULO). Each time fruit was withdrawn from storage, carbon dioxide and ethylene production were measured for 14 days at 20 °C. Independently of the calcium treatments, respiration rates fell from harvesting until 6 months of storage, while ethylene production was greater on withdrawal from storage than at harvest. Respiratory rate and ethylene production correlated negatively with calcium content. However, calcium apparently had a greater effect on the respiratory capacity (CO2) of fruit than on ethylene production. Copyright © 2004 Society of Chemical Industry
Fluoride: A toxic or therapeutic agent in the treatment of osteoporosis?
Authors: Aaseth Jan , Shimshi Mona , Gabrilove J. Lester , Birketvedt Grethe Støa 
Published: April 2004

AbstractThis article summarizes recent studies and is a review of the literature on the fluoride compounds and their influence on bone mineral mass. It is well known that fluoride is an important element for mineralization of body tissues. The use of topical and systemic fluoride for oral health has resulted in major reduction in dental caries, but fluoride also plays a role in bone health. Dieticians and other health professionals are advised to recommend adequate use of systemic and topical fluorides, especially in children and adolescents. Population studies as well as earlier studies of individuals exposed to fluorides indicate that doses above 30–40 mg daily can result in fluorosis, characterized by increased fracture risk. Numerous clinical studies have demonstrated increased bone mineral density in subjects treated with appropriate doses of fluoride. However, the clinical interpretation of these studies has been a matter of debate. Therapeutically, fluoride seems to be useful when the agent is started in the early stages of osteoporosis, especially in patients with intact trabecular bone. It is well established that fluoride can act as an effective stimulator of bone formation by the osteoblasts. Bisphosphonates, which can also increase bone density, act by inhibiting bone resorption by osteoclasts. As a result of this, owing to the tight paracrine association characterizing skeletal metabolism, bone formation is slowed down by the antiresorptive agents. It is of particular interest that great benefit in the treatment of osteoporoses is seen when adequate osteoblast‐stimulating doses of fluorides are given in combination with antiresorptive medication, but further research is needed to substantiate this promising concept. J. Trace Elem. Exp. Med. 17:83–92, 2004. © 2004 Wiley‐Liss, Inc.
Effect of aging on sensory nerve conduction study parameters
Authors: Tong Henry C. , Werner Robert A. , Franzblau Alfred 
Published: April 2004

AbstractResearch evaluating the changes in nerve conduction with time has been limited to cross‐sectional studies. We present a cohort study estimating how sensory nerve conduction study (NCS) parameters change with time when subjects are measured at two time‐points. We evaluated 440 working adults by performing median and ulnar antidromic sensory NCS of both hands on two occasions, about 5.4 years (range, 4.3–7.0 years) apart. The rate of change in the NCS parameters was estimated using a mixed‐models analysis controlling for each hand, gender, age, and body mass index (BMI). After controlling for gender, age, height, and BMI, the amplitudes of the median sensory nerve action potentials (SNAP) decreased by about 2.3 μV, peak latencies increased by 0.11 ms, onset latencies increased by 0.07 ms, and conduction velocities decreased by 1.1 m/s over 5 years. Corresponding values for the ulnar nerve were 1.75 μV, 0.06 ms, 0.04 ms, and 0.71 m/s, respectively. The findings are consistent with the findings of previous cross‐sectional studies. The rate of change over time was not affected by hand (dominant versus nondominant hand), gender, age, or BMI at baseline. The rate of change seen with some of the median nerve parameters was significantly greater than that with the ulnar nerve. Muscle Nerve 29: 716–720, 2004
Posterior tibial nerve stimulation in the treatment of voiding dysfunction: Urodynamic data
Authors: Vandoninck Vera , van Balken Michael R. , Finazzi Agrò Enrico , Heesakkers John P.F.A. , Debruyne Frans M.J. , Kiemeney Lambertus A.L.M. , Bemelmans Bart L.H. 
Published: April 2004

AbstractObjectivesTo determine urodynamic changes and predictive factors in patients with voiding dysfunction who underwent 12 percutaneous tibial nerve stimulations.MethodsThirty nine patients with chronic voiding dysfunction were enrolled in a prospective multicenter trial in the Netherlands (n = 19) and in Italy (n = 20). A 50% reduction in total catheterised volume per 24 hr was taken as a primary objective outcome measure. Patients' request for continuation of treatment was regarded as subjective success. Objective urodynamic parameters and bladder indices were determined. Odds ratios and their 95% confidence interval were computed as a measure for predictive power in order to reveal predictive factors (Pdet at Qmax, Qmax, BVE, and BCI).ResultsPrimary outcome measure was obtained in 41%, an additional 26% reduced their 24 hr residuals with more than 25%. Fifty nine percent of patients chose to continue treatment. Detrusor pressure at maximal flow, cystometric residuals, and bladder indices improved significantly for all patients (P < 0.05). Patients with minor voiding dysfunction were more prone to notice success (Odds ratio: 0.73; 95% CI: 0.51–0.94).ConclusionsPTNS is a young treatment modality, minimally invasive, and easily accessible. It might be an attractive first line option for patients with (minor) voiding dysfunction. Neurourol. Urodynam. 23:246–251, 2004. © 2004 Wiley‐Liss, Inc.
ERRATUM: Rapid electrical and delayed molecular signals regulate the serum response element after nerve injury: Convergence of injury and learning signals
Authors: Lin Hana , Bao Jianxin , Ying Ju‐Sung , Walters Edgar T. , Ambron Richard T. 
Published: April 2004

AbstractThe original article to which this Erratum refers was published inJournal of Neurobiology (2003) 57(2) 204–220The name of the third author of this article was spelled incorrectly. It should read:Ying‐Ju SungThe publisher regrets this error.
Natural superconvergent points of triangular finite elements
Authors: Lin Runchang , Zhang Zhimin 
Published: April 2004

AbstractIn this work, we analytically identify natural superconvergent points of function values and gradients for triangular elements. Both the Poisson equation and the Laplace equation are discussed for polynomial finite element spaces (with degrees up to 8) under four different mesh patterns. Our results verify computer findings of Babuška et al., especially, we confirm that the computed data have 9 digits of accuracy with an exception of one pair (which has 8‐7 digits of accuracy). In addition, we demonstrate that the function value superconvergent points predicted by the symmetry theory of Schatz et al. are the only superconvergent points for the Poisson equation. Finally, we provide function value superconvergent points for the Laplace equation, which are not reported elsewhere in the literature. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004.
A new linearized method for Benjamin‐Bona‐Mahony equations
Authors: Li Chen , Wu Xionghua 
Published: April 2004

AbstractIn this article, a new method called linearized and rational approximation method based on differential quadrature method (DQM) is proposed for the Benjamin‐Bona‐Mahony (BBM) equation on a semi‐infinite interval. Numerical result indicates the high accuracy and relatively little computational effort of this method. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004