bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Model to Predict How Individual Factors Influence Secchi Depth Variations among and within Lakes
Authors: Håkanson Lars , Boulion Viktor V. 
Published: May 2003

AbstractThis work presents a model to predict lake Secchi depth. It has been developed as a part of a comprehensive ecosystem model, LakeWeb. The Secchi depth model is based on a modelling technique using dimensionless moderators. It gives, e.g., weekly variations and accounts for how various factors influence Secchi depth individually in spite of the fact that many of them are interrelated in a complex manner. The model has been tested over a wide range of lakes. It gives predictions that agree well with empirical reference regressions, and also expected and requested divergences when the regressions do not provide sufficient resolution. The model is driven by the following data which are easily accessed from standard monitoring programs or maps: Total phosphorus, colour, pH, mean depth and lake area reflecting the three main processes influencing variations of Secchi depth within and among lakes, allochthonous inputs, autochthonous production and resuspension.
Functional groups on polystyrene model nanoparticles: Influence on protein adsorption
Authors: Gessner Andrea , Lieske Antje , Paulke Bernd‐R. , Müller Rainer H. 
Published: May 2003

AbstractThe surface characteristics of intravenously administered particulate drug carriers decisively influence the protein adsorption that is regarded as a key factor for the in vivo fate of the carriers. Latex nanoparticles were synthesized to study the influence of different basic and acidic functional groups on particulate surfaces on the protein adsorption from human serum. The protein mass adsorbed to the particles was assessed by BCA proteinassay, the protein adsorption patterns were analyzed by two‐dimensional electrophoresis. Considerable differences in the protein adsorption with regard to preferential adsorbed proteins were detectable for the different functional groups. Possible correlations between the surface characteristics and the protein adsorption are shown and discussed. The knowledge concerning the interactions of proteins and nanoparticles can be used for a rational development of particulate drug carriers and can also be useful for an optimized design of medical devices, e.g., hemodialysis membranes or implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 319–326, 2003
Production of interferon‐β by fibroblast cells on membranes prepared with RGD‐containing peptides
Authors: Higuchi Akon , Takanashi Yasunari , Tsuzuki Nobuya , Asakura Tetsuo , Cho Chong‐Su , Akaike Toshihiro , Hara Mariko 
Published: May 2003

AbstractThe production of interferon‐β by NB1‐RGB fibroblast cells cultured on protein and peptide membranes prepared from silk fibroin, motif peptides of silk fibroin [(AG)n] containing arginine–glycine–aspartic acid (RGD) peptide, and Pronectin™ was investigated. The cell density on various protein and peptide membranes was approximately the same, although the production of interferon‐β depended significantly on the membranes where the cells were cultured. The highest production of interferon‐β was observed when the cells were cultured on (AG)6RGD(AG)7 membranes prepared with hexafluoroacetone (HFA) as the casting solvent. On RGD‐containing peptide membranes more centrally located in the peptides, the cells produced more interferon‐β when the peptide membranes were prepared with HFA as the casting solvent. However, there was no enhanced production of interferon‐β by cells on (AG)6RGD(AG)7 membranes prepared with 9 mol/L LiBr or 4.5 mol/L LiClO4 solution as the casting solvent. Therefore, both the chemical composition and the secondary and higher order structure of the peptide membranes are important for enhanced production of interferon‐β. The blocking of integrin β1 on the cells by anti‐integrin β1 antibody prevented the enhanced production of interferon‐β on (AG)6RGD(AG)7 membranes prepared with HFA. We suggest that the cells must bind to the RGD sequence having the appropriate conformation through their integrin β1 for enhanced production of interferon‐β. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 369–378, 2003
Interfacial kinetics of titanium‐ and cobalt‐based implant alloys in human serum: Metal release and biofilm formation
Authors: Hallab Nadim James , Skipor Anastasia , Jacobs Joshua J. 
Published: May 2003

AbstractThe biocompatibility of metallic implant surfaces is governed in large part by the interfacial kinetics associated with metal release and protein binding. The kinetics of metal release from, and protein binding to, cobalt‐ and titanium‐based implant alloys in human serum were investigated by (1) measuring the temporal release of Cr and Ti into serum from Co‐Cr‐Mo (ASTM F‐75) and Ti implant alloys (Ti‐6Al‐4V: ASTM F136, and commercially pure Ti, cpTi: ASTM F67), respectively; (2) examining the composition of human serum proteins adsorbed onto the surfaces of Co‐ and Ti‐based implant alloys; and (3) identifying the serum proteins associated with the binding of soluble Cr and Ti degradation products. Analysis of metal dissolution kinetics found that Cr was released from Co‐based implant alloy at an order of magnitude higher than Ti was released from Ti‐based implant alloys. Serum became saturated with soluble CR and Ti at levels as high as 3,250 ng/mL Ti from cpTi; 3,750 ng/mL Ti from Ti‐6Al‐4V; and 35,400 ng/mL Cr from Co‐Cr‐Mo degradation. The observation that human serum binds more released metal from Co‐based alloy dissolution was consistent with the observed differences in biofilm composition between the two alloys, where additional serum protein(s) of approximately ≈140 (kDa) molecular weight were detected on Co‐based implant alloy surfaces. However, both Cr and Ti released from Co‐ and Ti‐based alloys exhibited a bimodal binding pattern to both low molecular weight serum protein(s) (<32 kDa), and to higher molecular weight protein(s) in the 180–250 kDa range. Identification of metal alloy–dependent biofilm compositions and dissolution products provides the basis for understanding the bioavailability and bioreactivity of these implant alloys and their degradation products. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 311–318, 2003
Efficacy of glow discharge gas plasma treatment as a surface modification process for three‐dimensional poly (D,L‐lactide) scaffolds
Authors: Chim Harvey , Ong Joo L. , Schantz Jan‐Thorsten , Hutmacher Dietmar W. , Agrawal C. Mauli 
Published: May 2003

AbstractGas plasma surface modification of three‐dimensional poly (D,L‐lactide) scaffolds fabricated by a novel vibrating particle fabrication technique was demonstrated to enhance cell adhesion, proliferation, and differentiation over 10 days in culture using human embryonic palatal mesenchyme cells. Characterization of corresponding two‐dimensional treated surfaces revealed decreased contact angle measurements of 54.2 ± 0.6° for treated surfaces compared to 72.3 ± 0.7° for control surfaces (p < 0.05). SEM of treated surfaces revealed increased surface roughness combined with marked pitting and erosion. This may contribute to increased cell adhesion. WST‐1 cell proliferation assay measurements as an index of cell numbers revealed a statistically significant increase in proliferation activity on treated surfaces on days 1 and 4 compared with controls. There was a fivefold increase in WST‐1 activity for both control and treated groups over 10 days. Confocal laser micrographs revealed increased cell numbers on treated specimens throughout all layers of the scaffold, indicating that the glow discharge process enhanced cell proliferation throughout the entire scaffold architecture. Scanning electron micrographs demonstrated increased cell adhesion for treated specimens at the polymer surface most evident after days 1 and 4 of culture. Alkaline phosphatase (ALP)‐specific activity peaked by day 7 for control and treated surfaces, indicating cellular differentiation. There was a trend for increased protein production on the treated specimens compared with controls at the initial time points although the differences were not statistically significant. These results demonstrated that gas plasma surface modification enhances osteoblast‐like cell function in a three‐dimensional scaffold model. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 327–335, 2003
In vitro osteoblast response to anodized titanium and anodized titanium followed by hydrothermal treatment
Authors: Rodriguez R , Kim Kyohan , Ong Joo L. 
Published: May 2003

AbstractIn this study, Titanium (Ti) surfaces were modified using anodization. The electrolyte used for anodization was a mixture of calcium glycerophosphate and calcium acetate. The anodized surfaces were divided into three groups. Hydrothermal treatments were performed on two of the anodized groups for either 2 or 4 h. In vitro osteoblast response to anodized oxide and the hydrothermal treated oxide after anodization was evaluated in this study. Calcium and phosphorus ions were deposited on the Ti oxide during anodization. Anodized surfaces following a 4‐h hydrothermal treatment were observed to promote the growth apatite‐like crystals as compared with anodized surfaces after a 2‐h hydrothermal treatment. Cellular function and onset of mineralization, as indicated by protein production and osteocalcin production, respectively, also were observed as enhanced on hydrothermal‐treated surfaces. It was thus concluded from this study that calcium phosphate and apatite‐like crystals could be deposited on Ti surfaces using anodization and a combination of anodization and hydrothermal treatment. It was also concluded that the phenotypic expression of osteoblast was enhanced by the presence of calcium phosphate or apatite‐like crystals on anodized or hydrothermally treated Ti surfaces. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 352–358, 2003
Mannosylerythritol lipids, yeast glycolipid biosurfactants, are potential affinity ligand materials for human immunoglobulin G
Authors: Im Jae Hong , Yanagishita Hiroshi , Ikegami Toru , Takeyama Yu‐ichiro , Idemoto Yasushi , Koura Nobuyuki , Kitamoto Dai 
Published: May 2003

AbstractThree mannosylerythritol lipids (MEL‐A, ‐B, and ‐C), yeast glycolipid biosurfactants, were independently attached to poly (2‐hydroxyethyl methacrylate) beads (PHEMA), and the three obtained MEL‐PHEMA composites were examined for their binding affinity to human immunoglobulin G (HIgG). Of the three composites, the composite bearing MEL‐A exhibited the highest binding capacity for HIgG. The binding amount of HIgG increased with increased applied concentration, reaching 106 mg HIgG (per g of composite), with a binding yield of 81%. Interestingly, the protein binding to the composite appeared to follow two different modes (Langmuir type and Freundlich type) depending on the applied concentration. The binding amount of human serum albumin to the composite was much smaller than that of HIgG. The bound human serum albumin, however, had minimal effect on the subsequent binding of HIgG, indicating that the two proteins have different binding sites onto the composite. More significantly, the bound HIgG was efficiently recovered under significantly mild elution conditions: Approximately 90% of the protein was eluted from the composite with phosphate buffer at pH 7. These results indicate that the glycolipid biosurfactant may have great potential as an affinity ligand material for HIgG. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 379–385, 2003
Expression of adhesion molecules and cytokines in vitro by endothelial cells seeded on various polymer surfaces coated with titaniumcarboxonitride
Authors: Lehle Karla , Buttstaedt Johannes , Birnbaum Dietrich E. 
Published: May 2003

AbstractAlthough endothelial cell (EC) seeding improves the patency of vascular prostheses, the detachment of adherent ECs after the restoration of circulation remains one of the major obstacles. Polymer surfaces for endothelialization can be optimized. In this study, polyethylene terephthalate (PET), polypropylene (PP), polytetrafluoroethylene (PTFE), polyurethane (PUR), and silicone were coated with a titaniumcarboxonitride (Ti(C,N,O)) layer by a plasma‐assisted chemical vapor deposition process to verify the effect of titanium onto human saphenous vein ECs. Almost confluent EC monolayers were evaluated for 1) proliferation activity and 2) expression of adhesion molecules using cellular enzyme‐linked immunosorbent assay and release of cytokines. The results showed that all titanium‐coated polymers and uncoated PET have no toxic effect on human saphenous vein ECs excepting uncoated PTFE, PP, and silicone. Moreover, growing ECs showed an insignificant decrease in cytokine production and an unessential change in basal expression of adhesion molecules. Tumor necrosis factor‐α–induced response depends on polymer surface: for example, intercellular adhesion molecule‐1 expression decreased. E‐selectin expression was unchanged for culturing ECs on coated PET, PP, and PTFE and reduced for polyurethane and silicone. Vascular cell adhesion molecule‐1 expression was unchanged for coated PUR and silicone and reduced for PET, PP, and PTFE. In summary, titanium‐coating layers promote adhesion of human ECs on polymer vascular grafts with no proinflammatory reaction of ECs. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 393–401, 2003
The proteoglycan contents of the temporomandibular joint disc influence its dynamic viscoelastic properties
Authors: Tanaka Eiji , Aoyama Junko , Tanaka Masao , van Eijden Theo , Sugiyama Masaru , Hanaoka Koichi , Watanabe Mineo , Tanne Kazuo 
Published: May 2003

AbstractThe collagen fibers and proteoglycans in the disc of temporomandibular joint provide resistance to various loadings. Thus far, however, the role of the proteoglycans in determining the viscoelastic properties of the disc has not been investigated. In the present study the hypothesis was tested that the viscoelastic behavior of the disc decreases by the removal of proteoglycans. In 32 bovine discs, dynamic tensile tests with a wide range of frequencies were performed. Before testing, specimens were treated with different concentrations of α‐amylase to remove proteoglycans. As the frequency increased from 0.1 to 100 Hz, the disc became more viscoelastic. Increasing the concentration of α‐amylase significantly decreased its viscoelasticity. It was concluded that proteoglycans play an important role in determining the viscoelastic properties of the disc and, therefore, give the disc a greater capacity for distributing and reducing stresses. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 386–392, 2003
Hydroxylapatite and titanium: Interfacial reactions
Authors: Ergun Celaletdin , Doremus Robert , Lanford William 
Published: May 2003

AbstractThe chemical reactions between hydroxylapatite (HA) and titanium were studied in three different kinds of experiments to increase understanding of how to bond HA to titanium for implant materials. HA powder was bonded to a titanium rod with hot isostatic pressing. Interdiffusion of the HA elements and titanium was found in concentration profiles measured in the electron microprobe. Titanium was vapor‐deposited on sintered HA discs and heated in air; perovskite (CaTiO3) was found on the HA surface with Rutherford backscattering and X‐ray diffraction measurements. Powder composites of HA and titanium and TiO2 were sintered at 1100°C; again, perovskite was a reaction product, as well as β‐Ca3(PO4)2, from decomposition of the HA. These results demonstrate chemical reactions and interdiffusion between HA and TiO2 during sintering, resulting in chemical bonding between HA and titanium. Thus, cracks and weakness at HA–titanium interfaces probably result from mismatch between the coefficients of thermal expansion of these materials. HA composites with other ceramics and different alloys should lead to better thermal matching and better bonding at the interface. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 336–343, 2003
A new quantitative method to evaluate the in vitro bioactivity of melt and sol‐gel‐derived silicate glasses
Authors: Arcos D. , Greenspan D. C. , Vallet‐Regí M. 
Published: May 2003

AbstractTwo melt‐derived glasses (45S5 and 60S) and four sol–gel glasses (58S, 68S, 77S, and 91S) have been synthesized. The activation energy for the silicon release was determined, and a very close correlation was observed between this value and published results of the bioactive behavior of the glasses. This relationship can be explained in terms of the influence of chemical composition, textural properties, and structural density on the silanol group formation and silicon dissolution. These measurements provide a quantitative method to evaluate the in vitro bioactivity of SiO2‐based glasses. Preliminary studies suggest an activation energy gap (Ea) of 0.35–0.5 eV as a boundary between bioactive and nonbioactive glasses. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 344–351, 2003
Calcium‐deficient apatite: A first in vivo study concerning bone ingrowth
Authors: Bourgeois B. , Laboux O. , Obadia L. , Gauthier O. , Betti E. , Aguado E. , Daculsi G. , Bouler J.‐M. 
Published: May 2003

AbstractBiphasic calcium phosphate (BCP) materials are increasingly used to restore bone loss in surgery. Calcium‐deficient apatites (CDA), the precursors of BCP, are closer in structure to biological apatites and can be associated with therapeutic agents to form drug‐delivery systems. The purpose of this first in vivo study of CDA was to evaluate the osteoconductive properties of two composites, consisting of 40–80 μm granules carried by a cellulose‐derived polymer, used to fill critical size bone defects in rabbit femoral ends. Animals were sacrificed 2 or 3 weeks after implantation. Histomorphometric analysis of scanning electron microscopy implant surface files was performed using gray level threshold that distinguish between bone or materials (white) and noncalcified tissue (black). Quantitative results for new bone formation showed no significant differences between the composites or the implantation periods. However, nearly all of the CDA disappeared early while supporting more extensive bone colonization than biphasic calcium phosphates implanted in the same conditions. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 402–408, 2003
Effects of multigrooved surfaces on fibroblast behavior
Authors: Yoshinari M. , Matsuzaka K. , Inoue T. , Oda Y. , Shimono M. 
Published: May 2003

AbstractMicrogrooves have been investigated as substrates for the control of cell alignment. However, they are relatively too narrow and shallow for controlling the orientation of extracellular matrices (ECM) such as collagen. Multigrooves, a combination of microgrooves and macrogrooves, are expected to be able to control the orientation of both cells and ECM. This study investigated a method for fabricating multigrooves and evaluated fibroblast behavior on these novel surfaces. Multigrooved patterns were fabricated on a gold–alloy metal die, in which 90‐degree V‐shaped microgrooves with a 2‐μm pitch were cut on trapezoidal macrogrooves. The macrogrooves had a 50‐μm ridge width, a 50‐μm wall width, a 50‐μm bottom width, and a 25‐μm depth. The grooves were made by an ultraprecision micromachine using a single crystal diamond. This metal die served as a template for making surface replicas from polystyrene. Microgrooved and smooth polystyrene replicas also were prepared as comparative substrates. Mouse fibroblast L929 cells were cultured in each type of replica substrate for 7 to 21 days. After these periods, the cells were fixed with 2.5% glutaraldehyde, treated with conventional methods, and, finally, observed by SEM. Confocal laser scanning microscopy was performed to investigate ECM formation. The multigrooved metal die exhibited the desired sharp configuration without defects. The dimensional values of the multigrooves on the polystyrene replicas were almost the same as the designed values. The fibroblasts on the multigrooved and microgrooved substrates were aligned parallel to the surface grooves after 7 days of incubation. In contrast to the microgrooved and flat surfaces, a dense extracellular matrix was produced along the multigrooves after 21 days of incubation. These results suggest that multigrooves can control the orientation of ECM as well as cells and thus enhance the production of ECM. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 359–368, 2003
An expression system for the functional analysis of pheromone genes in the tetrapolar basidiomycete Schizophyllum commune
Authors: Gola Susanne , Kothe Erika 
Published: May 2003

AbstractThe investigation of putative pheromone genes of basidiomycetes has been difficult since the small open reading frames are essentially annotated on the basis of a C‐terminal farnesylation signal. In order to identify the functional reading frame, expression of small DNA fragments in the fungus is necessary. The expression system developed in the presented paper allows fusion to the promoter of the tef1 gene encoding the constitutively and highly expressed translation elongation factor EF1α. This system has been shown to be functional using an easily selectable gene, ura1. The application to identification of functional pheromone genes has been shown with the newly detected bap2(4) gene. The Bap2(4) pheromone is the first Bα pheromone gene activating only a single receptor specificity.
Transformations of testosterone and related steroids in Absidia glauca culture
Authors: Huszcza Ewa , Dmochowska‐Gladysz Jadwiga 
Published: May 2003

AbstractIn the following study, the course of transformations of testosterone and its derivatives with an additional C1–C2 double bond and/or 17α‐methyl group or without 19‐methyl group in Absidia glauca culture was investigated. The fungi were observed to hydroxylate these compounds and to oxidise the 17β‐hydroxyl group. The products of 6β, 7α, 7β, 11α, 12β or 15β hydroxylation were obtained. 19‐Nortestosterone was also hydroxylated at the 10β position.The position and stereochemistry of the introduced hydroxyl group was dependent on the presence of the additional C1–C2 double bond, while hydroxylation at the C‐6β was unaffected. The incubation of testosterone with Absidia glauca gave hydroxyderivatives of androstenedione: 7α‐hydroxyandrostenedione and 6β,11α‐dihydroxyandrostenedione. When 1‐dehydrotestosterone and 1‐dehydro‐17α‐methyltestosterone were used, the products were hydroxylated at 6β, 7β or 15β position while 17α‐methyltestosterone and 19 nortestosterone products were hydroxylated at 6β, 7α, 11α or 12β position. Two metabolites: 6β,11α‐dihydroxyandrostenedione and 6β,12β‐dihydroxy‐17α‐methyltestosterone were dihydroxylated. The presence of 17α‐methyl group in 17α‐methyltestosterone and 1‐dehydro‐17α‐methyltestosterone did not influence the position of hydroxylation.