Hydrogel based in vivo reference electrode catheter.
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Animals↗
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Results for “Polyhydroxyethyl Methacrylate”
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Microencapsulation of mammalian cells in polyacrylates.
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Animals↗
Coupling of nuclear morphometry to cell geometry and growth in human fibroblasts.
The nuclear morphology of WI-38 cells plated on increasing thicknesses of the polymer, poly-2-hydroxyethylmethacrylate, was studied. Changes in nuclear morphometry were found to parallel changes in cellular morphometry: namely a transition to a more rounded and compact conformation, with increasing thicknesses of the polymer. Such changes in nuclear morphometry were opposite to those already observed after stimulation of proliferation by serum addition and similar to those observed with increasing confluency. These results suggest that coupling between cell and nuclear geometry may represent a mechanism for the control of proliferation by cell shape in nontransformed cells.
Cell Division↗
Optical biochemical sensor for determining hydroperoxides in nonpolar organic liquids as archetype for sensors consisting of amphiphilic conetworks as immobilisation matrices.
This paper reports the successful design of a prototype of an optical biochemical sensor for the determination of hydroperoxides in nonpolar organic liquids. The sensor consists of a matrix of an amphiphilic polymer conetwork (APCN), a novel class of very promising polymeric materials for easy preparation of biochemical sensor matrices. APCNs are characterised by nanoscopic phase separation between the hydrophilic and the hydrophobic phases. For medium ratios of conetwork composition, the domains of both phases are interconnected both on the surface of the conetworks and throughout the bulk. The APCNs have peculiar swelling properties-the hydrophilic phase swells in hydrophilic media and the hydrophobic phase swells in hydrophobic media. In both types of media dissolved reagents can diffuse from the solution into the swollen phase of the polymeric conetwork. This enables loading of the hydrophilic phase of the APCNs with enzymes and indicator reagents by simple impregnation. Hydrophobic analytes can diffuse into the polymeric conetwork via its hydrophobic phase and react with indicator reagents immobilised in the hydrophilic phase at the huge internal interface between the two opposite phases.To prepare the described hydroperoxide-sensitive biosensors, we used APCN films consisting of 58% (w/w) poly(2-hydroxyethyl acrylate) (PHEA) as hydrophilic chains and 42% (w/w) polydimethylsiloxane (PDMS) as hydrophobic linkers. Horseradish peroxidase (HRP) and diammonium 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as indicator reagent were co-immobilised in this optically clear and transparent matrix. In this feasibility study the conditions investigated were principally those relevant to characterisation of the innovative matrix material and the disposable biosensor produced from it; the biosensor was not optimised. Sensitivity toward tert-butylhydroperoxide (tBuOOH) dissolved in n-heptane was acceptable, between approximately 1 and at least 50 mmol L(-1), even in the dry state. The response time was 1.7 to 5.0 min. No leaching of immobilised reagents was observed during a period of at least one hour. Pre-swelling the sensors with water increased the reaction rate and the total turnover number of the enzyme. In a dry atmosphere at 4 degrees C the sensors were found to be stable for at least two weeks.
Biosensing Techniques↗
Biocompatibility of bacterial contaminated prosthetic meshes and porcine dermal collagen used to repair abdominal wall defects.
BACKGROUND AND AIMS: A contaminated or infected surgical site is considered a contraindication for the use of the nonabsorbable alloplastic materials employed to repair abdominal wall defects. Therefore, the biocompatibility of new prosthetic materials was investigated. MATERIALS AND METHODS: Meshes measuring 1.5x1.5 cm made of conventional and titanium-coated polypropylene, polyglycol, or porcine dermal collagen were implanted under the abdominal wall of 96 rats (eight groups of 12 animals each) employing the inlay technique. Implantation of all four materials was performed both under semisterile conditions and bacterial contamination of the mesh. The meshes were explanted after 28 days. RESULTS: All the materials implanted under semisterile conditions were incorporated into the abdominal wall with only few intraabdominal adhesions (mean adhesion scores: 1.0, 1.2, 1.0, 0.8 points, respectively, not significant). With the porcine dermal collagen, proliferation rate and the proportion of inflammatory cells were statistically lower (p<0.01). In the bacterial contamination group, all meshes were associated with a suppurating infection and strong adhesions between the bowel and mesh, which were most prominent in the case of dermal collagen (mean adhesion scores: 1.6, 1.7, 1.7, and 1.9 points, respectively, not significant). In this group, two animals died of peritonitis. In comparison with the other materials, the proliferation rate was significantly elevated (p=0.03). No significant differences were seen between the other materials employed. CONCLUSION: Irrespective of the material employed, implantation of alloplastic meshes in an abdominal wall contaminated with bacteria, is associated with suppurating infections, in particular in the case of the membrane-like porcine dermal collagen. Nonabsorbable alloplastic meshes and dermal skin grafts should therefore not be used to repair infected abdominal wall defects.
Abdominal Wall↗
In vitro and ex vivo blood compatibility study of 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer-coated hemodialysis hollow fibers.
To identify the advantages of 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer-coated polysulfone (PSf) hollow fibers for hemodialyzer and hemofilter minimodules with hollow fibers were made and blood compatibility was evaluated in vitro and ex vivo. Three types of hollow fibers, i.e., pure PSf (no additives), PSf alloyed with poly(1-vinyl-2-pyrrolidone) (PVPy), and PSf coated with the MPC copolymer, were processed in wet conditions. Commercially available hollow fibers (APS) were used as a control sample. The PSf hollow fibers have a condensed structure. A porous structure was observed when the PVPy was alloyed before wet processing, and no effect of the innercoated MPC copolymer on the porous structure was observed. One-tenth-sized minimodules of the conventional hemodialyzer were fabricated with 200 fibers each. The solute permeability of the hollow fibers was evaluated using 10% bovine serum in a buffer solution containing cytochrome C, which is a model protein of Beta(2)-microglobulin. After circulation for 2.5 h, the solute permeability of APS and PVPy-alloyed PSf hollow fibers decreased to 50% compared with their initial values. In contrast, the value for the hollow fibers innercoated with the MPC copolymer maintained its initial level. The inner surface of the dialysis membranes was observed with a transmission electron microscope and a layer of adsorbed protein on the PSf, APS, and PVPy-alloyed PSf hollow fibers was observed, but not on the MPC copolymer-coated fibers. Blood cell adhesion was then evaluated by circulation of whole rabbit blood without any anticoagulant ex vivo. Many adherent cells were observed on the PVPy-alloyed PSf hollow fibers; however, blood cells did not adhere or aggregate on the MPC copolymer-coated hollow fibers. From these results, we concluded that the in-situ coating of MPC copolymer on PSf hollow fibers is effective in preventing blood coagulation and maintaining the solute permeability of the fibers.
Animals↗
Effects of bacterial adhesion with respect to the type of material, structure and design of intraocular lenses.
The properties of the biomaterials used to constitute lenses are important factors choosing a lens for human implantation because these can influence in posterior clinical evolutions of patients. In this study, different characteristics of intraocular lenses such as chemical composition, surface roughness and lens design have been investigated in terms of their influence into a pathological environment. Eight commercial lenses were tested by optical profiling, Infrared spectra with Fourier transformation (FTIR), water-material contact angle and scanning electron microscope (SEM) to know their chemical composition and structural characteristics. These lenses were then exposed to infectious conditions in order to evaluate their responses to the bacterial environment.
Acrylic Resins↗
The laparotomy pad, the laundry and intestinal adhesions.
Uncoated laparotomy pads and pads coated with Hydron were put through an ordinary laundry procedure. A long-chain quaternary detergent remained in the pads and was not removed in the final rinse. In addition, Hydron was found, as expected. Implications of the presence of detergent in the peritoneal cavity are considered.
Detergents↗
Surface interaction between hydrophilic gels and articular cartilage.
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Acrylic Resins↗
The reaction of rat connective tissue to polyethylene tube implants filled with Hydron or gutta-percha.
A subcutaneous tube implant study was conducted on adult Sprague-Dawley rats. Polyethylene tubes sealed at one end were filled flush to the open end with Hydron or gutta-percha and sealer. These implants were immediately placed into dorsal subcutaneous connective tissue for periods ranging from three weeks to 6 months. Tubes filled with Hydron demonstrated expansion and resorption of material with its distribution into connective tissue. A moderately thick connective tissue capsule containing macrophages formed at the tissue-Hydron interface. Amorphous calcific deposits were localized within Hydron, being most dense at the Hydron--tissue interface. Tubes filled with gutta-percha and sealer demonstrated thinner connective tissue capsule formation, with little or no distribution or resorption of material. A mild lymphocyte response was noted within the capsule adjacent to the gutta-percha.
Animals↗
A histologic comparison of Hydron and zinc oxide-eugenol as endodontic filling materials in the primary teeth of dogs.
Currently available endodontic filling materials for primary teeth demonstrate several inadequacies. Therefore, this study histologically evaluates Hydron (2-hydroxyethylmethacrylate) and zinc oxide and eugenol (ZOE) as primary tooth endodontic filling materials in dogs to compare the materials' biocompatibility and to determine whether they undergo resorption in a physiologic manner. Primary molars of six mongrel dogs, 2 to 3 months old, received one-step endodontic therapy. By random selection, two thirds of the molars were filled with either Hydron or ZOE and the remainder were used as unoperated controls. Block sections taken during physiologic root resorption were used to obtain serial hematoxylin and eosin sections of periapical regions. Hydron was phagocytosed by mononuclear macrophages in a physiologic manner and at a rate comparable to that of root tissues. In contrast, ZOE demonstrated delayed resorption and transitory inflammation. Neither material showed cytotoxicity. Hydron may therefore be a suitable endodontic material for human primary teeth.
Animals↗
Prevention of alveolar bone loss postextraction with HTR grafting material.
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Adult↗
Enhanced osseointegration of hydroxylapatite implant material.
This study was undertaken to determine whether the addition of calcium sulfate to hydroxylapatite (HA) implant material would improve its working properties without adversely affecting its osseointegration. The clinical and histologic examinations of bone response of three implant materials, hard tissue replacement (HTR), HA, and HA composite (HA plus calcium sulfate), were performed after 2-, 4-, and 6-week implantation in tibia and mandible of rabbits. No sign of extensive chronic inflammatory response was detected. The highest rate of bone ingrowth occurred with the HA composite, followed by HA, with HTR showing the least ingrowth. Bone was deposited directly on the surface of HA and HA composite implant materials. In contrast, HTR particles had a thin layer of fibrous tissue encapsulation with the normal bony investment.
Analysis of Variance↗
In vivo release of testosterone from protein--vinyl polymer composites.
Hydrophilic vinyl polymer-protein composites containing testosterone were made by means of thermal denaturation of albumin after radiation-induced polymerization of 2-hydroxyethylmethacrylate (HEMA) at--78 degrees C. The albumin-HEMA mixed polymer can be considerably digested with trypsin. The degree of digestion was smaller than that expected from calculation. It was deduced that the digestion of the albumin component was retarded in the presence of HEMA. The same tendency was observed in in vivo experiments. At the same time, in vivo release of testosterone was depressed in albumin-HEMA mixed polymer composite in accordance with the weight decrease of polymer composite resulting from digestion. The effect of testosterone on the weight of ventral prostate was investigated using composites in castrated Wistar rats. The effect was larger in the controlled slow release from implanted composites rather than that of dosage by injection. The microscopic observation showed that the inflammation and foreign body reaction in rat tissue were retarded in albumin-HEMA mixture polymer composite compared with 100% albumin composite.
Animals↗
Subcutaneous polymeric matrix system poly(HEMA-BGA) for controlled release of an anticancer drug (5-fluorouracil). I. Synthesis and structure.
The present study was an attempt to design a new polymer-drug composite system for local chemotherapy. Poly(hydroxyethylmethacrylate-bisglycolacrylate) carriers containing an anticancer drug, 5-fluorouracil, were prepared by low temperature radiation polymerization technique. By changing the relative amounts and the types of ingredients, drug loading and radiation dosage, polymer-drug composites with different structural properties were obtained. This paper presents the preparation procedure and analyses some of the structural properties of these novel composites.
Acrylates↗
Laser-induced damage to transparent polymers: chemical effect of short-pulsed (Q-switched) Nd:YAG laser radiation on ophthalmic acrylic biomaterials. I. A review.
The use of short-pulsed lasers in ophthalmic surgery inspired and called for research on the damage inflicted by the laser radiation upon the acrylic polymers from which artificial intraocular lenses are made. The possible release of toxic monomers by laser-induced depolymerization is of great concern but past investigations of this phenomenon have been very limited. The present knowledge of various types of laser-induced damage to transparent polymers is reviewed with particular emphasis on the acrylic materials and intraocular lenses.
Lasers↗
Structural alterations of p(HEMA)--collagen implants.
Samples of linear (additionally crosslinked) p(HEMA) with different amounts of fibrillar collagen were implanted into the popliteal region of rats. After 3 month, the implanted materials were harvested and examined by SEM. The implants underwent marked structural or morphological changes. While the fibrillar collagen was readily resorbed by invading cells, the synthetic constituent persisted to biodegradation. The p(HEMA) residues were shaped into spherical particles, approx. 1-15 microns in diameter. The possible fate of these microparticles in the host organism is discussed.
Animals↗
Incorporation and release of fluorescein isothiocyanate-linked dextrans from a bead-formed macroporous hydrophilic matrix with potential for sustained release.
Freeze-thaw polymerization has been used to generate a bead-formed (100-3000 microns) macroporous hydrophilic matrix with potential for the sustained release of macromolecules. While the incorporation of FITC-dextrans marginally increased the equilibrium water content, their in vitro release profiles were characterized by an initial burst followed by a low but sustained release lasting > 21 d. The total cumulative release of FD-150 and the percentage of the incorporated FD-150 load subsequently released were reduced compared with FD-20S but for both dextrans these parameters could be enhanced by increasing the bead size and increasing the incubation temperature to 37 degrees C.
Biocompatible Materials↗