bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subcutaneous, catheter‐related inflammation in a rabbit model correlates with peripheral vein phlebitis in human volunteers
Authors: Carruth William A. , Byron M. Parke , Solomon Donald D. , White Wain L. , Stoddard Gregory J. , Marosok Randy D. , Sherertz Robert J. 
Published: May 2005

AbstractIn the development of a polyurethane vascular catheter with anti‐infective properties, it became desirable to develop a measure of tissue inflammation. This was investigated in a rabbit model by implanting uncoated catheters and catheters coated with heparin (HEP), chlorhexidine (CH), or CH/HEP in the subcutaneous space with or without 104 Staphylococcus aureus. At intervals of 2, 4 and 7 days after implantation, animals were sacrificed; tissue blocks containing catheters were removed and preserved with formaldehyde; and sections were stained with hematoxylin and eosin. Using a histologic index, 240 sections (10 for each experimental condition) were evaluated by two investigators blinded to experimental conditions. Uncoated catheters or catheters coated with CH alone had a lower histologic index (less inflammation) than catheters coated with HEP alone or CH/HEP (P <.05). When catheters were inoculated with S. aureus, those coated with CH, with or without HEP, had a lower histologic index than uncoated catheters (P <.05). Next, 30 volunteers had a control catheter inserted in a vein in one forearm and a catheter coated with either CH alone or CH/HEP in a vein in the other forearm. After 96 h of observation there was a greater risk of phlebitis associated with CH/HEP catheters than control catheters (P <.05), and no difference in the risk of phlebitis between CH catheters and control catheters (P = 0.43). Thus, the amount of inflammation around the catheter in the subcutaneous space of rabbit correlated with the risk of peripheral vein phlebitis. © 1994 John Wiley & Sons, Inc.
In vitro study of the intrinsic toxicity of synthetic surfaces to cells
Authors: Ertel Sylvie I. , Ratner Buddy D. , Kaul Amarjeev , Schway Michael B. , Horbett Thomas A. 
Published: May 2005

AbstractA trypan blue inclusion assay was used to measure cell death on poly(dimethyl siloxane) (PDMS), polyethylene (PE), poly(methyl methacrylate) (PMMA), polyurethanes, glass, and glow‐discharge‐treated polystyrene or poly(ethylene terephthalate). Cell lines used were bovine aortic endothelial, 3T3, mouse peritoneal macrophage, and BHK cells. In the absence of proteins in the media, PDMS, PE, PMMA, and some polyurethanes were consistently found to induce cell death. This toxic effect disappeared if the cells were seeded in serum‐containing medium or if concentrated solutions of proteins (albumin, IgG, or fibronectin) were preadsorbed on the materials. The substrate toxicity appeared to be due to the physical properties of the substrate and not to the release of toxic leachables. © 1994 John Wiley & Sons, Inc.
Fixation of bioprosthetic tissues with monofunctional and multifunctional polyepoxy compounds
Authors: Tu Roger , Shen Shih‐Hwa , Lin David , Hata Cary , Thyagarajan Kalathi , Noishiki Yasuharu , Quijano Rodolfo C. 
Published: May 2005

AbstractCollagen from a native tissue is fixed with a polyepoxy compound (PC) for use as a new biologic prosthetic material. Prior studies have shown that this biomaterial has comparable properties with collagen fixed with glutaraldehyde (GA), and thus has great promise for biomedical applications. A prior kinetic study indicated that the reaction between the functional groups of collagen and the multifunctional epoxy EX‐313 is a 2.5th‐order reaction. The purpose of this study was to understand the mechanism of the amino acid‐PC reactions in a fixation process. Bovine arteries were fixed with a monofunctional PC (EX‐313) and a multifunctional PC (EX‐313) as a function of fixation time. A sequential fixation with a second fixative was used to identify the available remaining reactive sites from a prior fixation. The denaturation temperature (Td) was measured on each sample. Because the denaturation temperature is a direct indication of crosslinking of individual amino acids with the fixative, the increase in Td of a subsequent fixation may be indicative of the available remaining amino acids. The fixation index was measured on each sample to reflect the increase of fixation completion in a sequential fixation process. The fixation index and crosslink data also revealed that the reactive amino acids for EX‐131 and EX‐131 may not be exactly the same. The data in this study suggest that a monofunctional fixative can pre‐react with the amino acids of collagen to effectively block further fixation of collagen with a second fixative. This amino acid masking may be associated with collagen branching. Collagen branching and its effect on denaturation temperature are described. © 1994 John Wiley & Sons, Inc.
Correlation between corneal epithelial cell outgrowth and monoclonal antibody binding to the cell binding domain of adsorbed fibronectin
Authors: Pettit Dean K. , Hoffman Allan S. , Horbett Thomas A. 
Published: May 2005

AbstractThe ability of corneal epithelial cells to attach, spread, and migrate on synthetic surfaces is largely determined by the characteristics of the adsorbed protein layer. In previous studies we have described an in vitro model for quantitating epithelial cell outgrowth from explanted corneal buttons onto synthetic materials (Pettit et al., Invest. Ophthalmol. Vis. Sci., 31, 2269 [1990]). We have also described the role of fibronectin (fn) adsorption and binding strength on epithelial cell outgrowth (Pettit et al., J. Biomed. Mater. Res., 26, 1259 [1992]). In the current study we have used a monoclonal antibody against the RGD cell binding domain of fn (mAb 3E3) to further characterize the role of adsorbed fn in promoting epithelial cell outgrowth. Ten materials of diverse chemical and physical properties were adsorbed with fn (0.1 mg/ml) or mixtures of fn and albumin (concentrations totaling 0.1 mg/ml) and tested for antibody recognition of the cell binding domain. The surface density of bound anti‐cell binding domain antibody varied from a low of 0.66 ± 0.11 for fluorinated ethylene propylene copolymer (FEP) to a high of 1.90 ± 0.26 for tissue culture polystyrene dish substrates (units are OD at 450 nm measured in the ELISA technique normalized to polyethylene). A general increase in cell outgrowth areas was noted, with increases in recognizable cell binding domain. However, several exceptions to this trend were noted as well (e. g., low cell outgrowth but high antibody recognizability for glass). These results suggest that, although the number of cell binding domains exposed on adsorbed fn molecules may influence cell outgrowth, other characteristics of the adsorbed protein, such as the binding strength to the underlying substrate, may be equally important in characterizing epithelial cell‐substrate interactions. © 1994 John Wiley & Sons, Inc.
Interspecies differences in systemic drug availability following subscutaneous pulsatile administration in cattle, sheep, dogs, and rats
Authors: Leppert Paula S. , Cammack Leilani , Cargill Robyn , Coffman Lori , Cortese Margot , Engle Karen , Krupco Colette , Fix Joseph A. 
Published: May 2005

AbstractRats, dogs, sheep, and cattle were implanted subcutaneously with stainless‐steel tissue cages. Bolus injections of cefoxitin and ivermectin were administered to the interiors of the tissue cages 11, 32, and 60 days after implantation to simulate pulsatile drug release from an implanted device. Plasma drug levels were determined for 6 h for cefoxitin and up to 8 days for ivermectin. Tissue cages were retrieved 3 and 6 months after implantation for macroscopic and microscopic examination. In dogs and rats, plasma levels of both drugs following administrations to the tissue cages were significantly lower than those following subcutaneous injection, suggesting that the tissue growth around and in the cages posed a barrier to systemic drug availability in those species. In cattle and sheep, the tissue cages and associated tissue did not inhibit systemic availability of either drug as compared with routine subcutaneous administration. © 1994 John Wiley & Sons, Inc.
Interpenetrating polymer network (IPN) as a permanent joint between the elements of a new type of artificial cornea
Authors: Chirila Traian V. , Vijayasekaran Sarojini , Horne Robert , Chen Yi‐Chi , Dalton Paul D. , Constable Ian J. , Crawford Geoffrey J. 
Published: May 2005

AbstractThe combination at the interface between two chemically identical polymers was investigated by light and electron (scanning, transmission) microscopy. The polymers constitute elements of a new type of artificial cornea in which the peripheral skirt is made from spongy poly(2‐hydroxyethyl methacrylate) (PHEMA) and the central optical zone from homogeneous, transparent PHEMA. Their two‐phase combination along the boundary fulfill formally the requirements for an interpenetrating polymer network (IPN). The procedure for the manufacture of prosthesis was described in detail. Thin and ultrathin sections excised from the interface region were investigated using microscopic techniques. Light microscopy allowed the measurement of the diffusion path length of transparent PHEMA into sponge, which was approximately 0.5 mm. Transmission electron microscopy revealed a cellular‐like morphology as well as larger segregated zones, which indicated network interpenetration on a molecular level and also a relatively poor miscibility of the two polymers despite their identical chemical structure. The latter was interpreted as a result of the submicroscopic restraints imposed by polymer I (sponge) upon polymer II. This study provides evidence that the interface combination of the prosthetic elements should be regarded as a gradient homo‐IPN. This system offers a union between elements much stronger than those previously reported in artificial corneas. © 1994 John Wiley & Sons, Inc.
Description of the mathematical law that defines the relaxation of bovine pericardium subjected to stress
Authors: Sestafe J. V. Garcia , GarcíA Paez J. M. , san Martín A. Carrera , Jorge‐Herrero E. , Navidad R. , Candela I. , Castillo‐Olivares J. L. 
Published: May 2005

AbstractA material subjected to traction stress increases in length; if we maintain the elongation constant, the stress varies over a period of time. This phenomenon has been referred to as relaxation. The purpose of this study was to define a mathematical law that relates the variation in stress to time when elongation remains constant in bovine pericardium. The mathematical function obtained after assaying 34 samples to the point of relaxation, subjected to initial stresses ranging from 0.17‐10.07 MPa, responds to the following equation:y= −0.0252 + 0.953 α ‐ (0.0165 + 0.015 α)lnt, where γ is the stress withstood at an instant in time,t, after initial stress α. A normogram, validated by assays of up to 6,340 min duration (4.40 days), is presented for graphic calculation, permitting the computation of the loss of stress due to relaxation of this biomaterial, with initial stresses ranging from 1‐10 MPa. © 1994 John Wiley & Sons, Inc.
Optimization of photopolymerized bioerodible hydrogel properties for adhesion prevention
Authors: Sawhney Amarpreet S. , Pathak Chandrashekhar P. , van Rensburg Jillian J. , Dunn Randall C. , Hubbell Jeffrey A. 
Published: May 2005

AbstractThe aim of this study was to optimize the properties of a lubricious bioerodible hydrogel barrier for the prevention of postoperative adhesions. Water‐soluble macromers based on block copolymers of poly(ethylene glycol) (PEG) and poly(lactic acid) or poly(glycolic acid) with terminal acrylate groups were used, and these macromers were gelled in vivo by exposure to long wavelength ultraviolet light. The precursor was photopolymerized from buffered saline solution while in contact with the tissues. This resulted in the conformal coating of the tissue with an adherent hydrogel film, while forming a nonadhesive barrier at the free surface, on the treated wound site. The hydrogels were evaluated in two animal models of postsurgical adhesions, first in a rat cecum abrasion model and then in a rabbit utreine hornischemia model. In the rat cecum model, six of seven animals treated with a hydrogel, with glycolide in the precursor as the comonomer, showed no adhesions; untreated animals and animals treated with precursor, but not gelled with light, showed consistent dense adhesions. In the rabbit uterine horn ischemia model, using hydrogels with lactide in the precursor as the comonomer, and PEG of molecular weight from 6,000 to 18,500 Da, adhesions were dramatically reduced, with occurrence in none of seven animals treated with a gel containing PEG 10,000. By contrast, the seven animals in the control group demonstrated a mean of 35% involvement of the horn length in dense, fibrous adhesions. These materials, photopolymerized in vivo in direct contact with the tissues, appear to form an adherent hydrogel barrier that is highly effective in reducing postoperative adhesions in the models used. An optimum exists in the molecular weight of the PEG and in the composition of the degradable link for most effective performance. © 1994 John Wiley & Sons, Inc.
The effects of ultrasound irradiation on a biodegradable 50–50% copolymer of polylactic and polyglycolic acids
Authors: Agrawal C. M. , Kennedy M. E. , Micallef D. M. 
Published: May 2005

AbstractThe aim of this study was to investigate the effects of ultrasound irradiation on a biodegradable drug delivery system. Microporous, disk‐shaped specimens of a 50‐50% copolymer of polylactic and polyglycolic acids were gel cast from an acetone solution. A protein was incorporated in these specimens, which were then immersed in phosphate buffered saline and subjected to ultrasound irradiation every second day. The investigation was performed in two phases: in the first, a study was performed for 58 days to determine if ultrasonic irradiation affected the kinetics of protein release from the specimens. In the second phase, effects of frequency and duration of the ultrasound signal on the degradation of the implant were studied for 40 days. The results indicate that ultrasound irradiation resulted in almost a threefold increase in protein elution from the specimens. Both the ultrasound frequency and signal duration affected the molecular weight loss and mass loss, and changed the overall degradation kinetics of the polymer. © 1994 John Wiley & Sons, Inc.
The effect of additive hyaluronic acid on animal joints with experimentally reduced lubricating ability
Authors: Mabuchi Kiyoshi , Tsukamoto Yukio , Obara Takeo , Yamaguchi Toshijiro 
Published: May 2005

AbstractA series of in vitro experiments demonstrated a clear effect of additive hyaluronic acid (HA) on animal joints with experimentally reduced lubricating ability. Eleven canine hip joints were utilized and the experimental conditions tested were: (i) intact joints, (ii) after washing the joint surfaces, and (iii) after adding 1% HA to them. The frictional coefficient of every joint increased after washing and subsequently decreased after adding HA. The mean values were 0.007 (SD 0.004) on the intact joints, 0.020 (SD 0.009) after washing, and 0.013 (SD 0.005) after the addition of HA. The differences between the three values of frictional coefficients were shown to be statistically significant (p < 0.01). © 1994 John Wiley & Sons, Inc.
Evaluation of a series of tyrosine‐derived polycarbonates as degradable biomaterials
Authors: Ertel Sylvie I. , Kohn Joachim 
Published: May 2005

AbstractA series of four polycarbonates derived from the ethyl, butyl, hexyl, and octyl esters of desaminotyrosyl‐tyrosine was prepared by condensation polymerization. The resulting polymers had weight average molecular weights ranging from 120,000–450,000, and their chemical structure was confirmed by elemental analysis, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The polycarbonates were evaluated as degradable biomaterials. Their surface properties were determined by electron spectroscopy for chemical analysis, attenuated total reflectance‐Fourier transformed infrared spectroscopy, and contact angle measurement. The degree of surface hydrophobicity was related to the length of the alkyl ester pendent chain. The tensile properties were dependent on the chemical structure of the polymers: For thin, solvent cast film specimens, the tensile modulus varied from 1.2–1.6 GPa, and the strength at break from 60–220 MPa. The degradation of polymeric films was followed in vitro by measuring changes in mechanical strength for up to 40 weeks, and the decrease in molecular weight and changes in surface chemistry for up to 80 weeks. The length of the pendent chain affected the degradation behavior and strength retention; the polymers with short pendent chains were more readily hydrolyzable. For sterilization, ethylene oxide treatment was less destructive, as judged by molecular weight retention, than γ‐irradiation. Spin‐cast films of all tested polycarbonates were not cytotoxic toward cultured rat lung fibroblasts. The cell response was influenced by the chemical structure of the polymer. The least hydrophobic polycarbonate (having a short ethyl ester pendent chain) was a more stimulating substrate for cell growth than the more hydrophobic polymers (carrying longer alkyl ester pendent chains).
Effect of molecular structure of poly(glycidyl ether) reagents on crosslinking and mechanical properties of bovine pericardial xenograft materials
Authors: Lee J. Michael , Pereira Christopher A. , Kan Lincoln W. K. 
Published: May 2005

AbstractWith the identification of the exacerbating effect of glutaraldehyde on calcification of heart valve materials, there exists a renewed interest in both alternative reagents and the effects of crosslinking on connective tissues. One potentially useful class of reagents are poly(glycidyl ether) compounds. We have examined 5 of these reagents with different molecular sizes and functionalities for their effects on mechanical properties and collagen denaturation (shrinkage) temperature. Samples of bovine pericardium were tested fresh or after 48 h fixation in one of the five compounds for denaturation temperature, stress‐strain response, stress relaxation, plastic deformation, and fracture properties. Of the compounds tested, those with intermediate length backbones and 4 or 5 epoxide groups were most effective in producing intrahelical crosslinking and increased denaturation temperature over 48 h. However, in samples examined after 17 months of fixation, all reagents had equivalently increased the denaturation temperature. Examination of mechanical results revealed two distinct mechanisms for mechanical change. Observed shifting of the stress‐strain curve to the right (due to shrinkage), increased plastic deformation, and some reduction of stress relaxation are all unrelated to denaturation temperature (and hence to changes in intrahelical crosslinking). An alternate mechanism, perhaps formation of intermolecular crosslinks may be responsible. Intrahelical crosslinking produces only lesser reductions in stress relaxation. Cross‐comparison of reagents of differing molecular structure provides a useful tool toward increased understanding of the mechanical consequences of tissue crosslinking. © 1994 John Wiley & Sons, Inc.
In vivo reactions of Ca,P particle containing surface reactive glasses
Authors: Kangasniemi I. M. O. , Vähätalo K. , Happonen R.‐P. , Yli‐Urpo A. , De Groot K. 
Published: May 2005

AbstractFour Ca,P particle containing surface reactive glass composites and two glasses(in the SiO2‐aO‐P2O5‐Na2O‐Al2O3 system) were implanted in the diaphyseal area of goat femora up to 24 weeks. Scanning electron microscopic, energy dispersive x‐ray, and histological analysis were performed to evaluate the material‐tissue interactions. A new type of integration mechanism was observed. Instead of the bone growing to the material surface, a gel‐like silica formation appeared between the cortex bone and the material surface. In time the gel‐like formation was replaced by a Ca,P layer. The results provided indirect evidence that pure silica gel formed in the tissues could also achieve an apatite layer formation and bone bonding on its surface. © 1994 John Wiley & Sons, Inc.
Feasibility of agarose microbeads with xenogeneic islets as a bioartificial pancreas
Authors: Iwata Hiroo , Kobayashi Kazuo , Takagi Tatsuya , Oka Takayuki , Yang Hua , Amemiya Hiroshi , Tsuji Takayuki , Ito Fumiaki 
Published: May 2005

AbstractA bioartificial pancreas, that is, transplantation of islets of Langerhans (islets) which are enclosed in a semipermeable membrane, has been proposed as a treatment for type I diabetes. The islets are immuno‐isolated from the host by the semipermeable membrane preventing rejection while maintaining control of glucose metabolism for an extended period. The purpose of the current research is to evaluate the feasibility of preparing agarose microbeads with xenogeneic hamster islets as a bioartificial pancreas in streptozotocin induced diabetic mice. In the recipients with a low level of anti‐hamster antibodies, the combination of encapsulation of hamster islets in 5% agarose microbeads and in vitro culture of them prolonged xenograft survivals. Four of 6 recipients were still normoglycemic at 100 days after implantation. However, the same procedure was not effective in the recipients which were sensitized in advance by transplantation of free hamster islets and thus had high levels of anti‐hamster antibodies. The average normoglycemic period was 32 days. Antibodies permeated through the microbeads and activated complement on the cell surfaces. The network of agarose microbeads was rendered dense by increasing the concentration of agarose to restrict the diffusion of antibodies. Graft survivals were prolonged with increasing concentrations of agarose. As an analysis using diffusion equations predicted, the survivals were inversely proportional to the diffusion coefficient of IgG in each agarose gel. Islet xenotransplantation was enabled by the combination of the microbeads with a concentration of agarose higher than 7.5% and in vitro culture even in recipients having a high level of preformed antibodies. © 1994 John Wiley & Sons, Inc.
Biocompatibility of a new semisolid bioerodible poly(ortho ester) intended for the ocular delivery of 5‐flurouracil
Authors: Bernatchez Stéphanie F. , Merkli Alain , Minh Tri Le , Tabatabay Cyrus , Anderson James M. , Gurny Robert 
Published: May 2005

AbstractThe biocompatibility of a new semisolid, hydrophobic poly‐(ortho ester) (POE) intended for controlled drug delivery to the eye was evaluated. The polymer was injected subconjunctivally in rabbits, and clinical and histologic examinations were performed 3, 10, 15, and 21 days after injection. Polymers injected as controls were an aqueous gel of sodium hyaluronate (SH), 1% in phosphate buffer, and medical grade silicone oil. After injection, the POE emulsified into small droplets and a focal eosinophilic reaction was noted at 3 days' implantation. At 10 days' implantation, the inflammatory reaction had resolved, with fibroblasts being the predominant cell type. At 15 and 21 days, no POE was identified and normal appearing tissue was present in the injection site. Sodium hyaluronate was not inflammatory over the period of the implantations. Silicone oil induced a slight inflammation at 3 days, with the presence of eosinophils and limited necrosis with cellular debris. Silicone oil was present in the implantation site at 3, 10, 15, and 21 days. The inflammatory response to the respective polymers was evaluated in the subconjunctival tissue. The inflammatory reaction was quantified at the implant site, adjacent subconjunctival tissues, and scleral and corneal stroma. The inflammatory cell densities in these respective tissue zones were determined, and the ratio of eosinophils over total inflammatory cells was calculated. POE did not become encapsulated with fibrous tissue, but biodegraded in a short time, indicating its potential for use after glaucoma filtration surgery. © 1994 John Wiley & Sons, Inc.