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Results for “Polyhydroxyethyl Methacrylate”

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PubMedDate not supplied

The interaction of urea with the generic class of poly(2-hydroxyethyl methacrylate) hydrogels.

Work reported here shows that, contrary to reports in the literature, hydrogels made from pure poly(2-hydroxyethyl methacrylate), pHEMA, at crosslinker content greater than 0.15 mol % do not swell above the usual equilibrium values of 39-42% water content in aqueous urea solution. However, hydrogels containing small (impurity) amounts of methacrylic acid (MAA) do swell dramatically (approximately 90%) in dilute urea solution, but not directly due to the urea. The urea decomposes to produce ammonium ions, thus raising the pH of the solution. Ionization of MAA occurs above pH 6, causing electrostatic interactions within the gel. The grossly swollen state of these gels represents an internal equilibrium among forces due to rubber elasticity, polymer-polymer/solvent affinity, and electrostatic interactions.

Aluminum Hydroxide↗

PubMed1989

Separation of B and T lymphocytes by cellular adsorption chromatography with polyamine graft copolymers as column matrices. II. Recovery of adsorbed B cell enriched populations from the column.

Poly(2-hydroxyethyl methacrylate)-graft-polyamine copolymers were developed for column adsorbents for separating lymphocyte subpopulations collected from rat mesenteric lymph nodes. Bead-shaped adsorbents were prepared by coating poly(2-hydroxyethyl methacrylate)-graft-polyamine copolymer on glass beads. Separation features of the column packed with poly(2-hydroxyethyl methacrylate)-graft-polyamine copolymer-coated glass beads were evaluated under various operating conditions. Separation efficacy, AB/AT, was significantly affected by the infusion rate of lymphocyte suspension into the column, increasing with decreasing infusion rate. T cell purity in the column effluent was almost 95% at the infusion rate of 0.1 ml/min. The infusion rate was also found to affect the detachment of adsorbed lymphocytes from the poly(2-hydroxyethyl methacrylate)-graft-polyamine copolymer surface by mechanical pipetting; lymphocytes adsorbed at a low infusion rate were able to be detached quantitatively by suspending the lymphocyte-adsorbed beads with gentle pipetting. The detached lymphocytes thus obtained were confirmed to be enriched in B cells 1.4 times the initial mixture of B and T cells. The addition of albumin in the medium was found to affect the processes of adsorption and recovery of lymphocyte.

Adsorption↗

PubMed1999

A study on hydroxyapatite formation on/in the hydroxyl groups-bearing nonionic hydrogels.

Using the biomimetic method, we formed a hydroxyapatite (HAp) layer on/in certain types of nonionic hydrogels that contain hydroxyl groups. The hydrogels used were poly(vinyl alcohol) (PVA), poly(2-hydroxyethyl methacrylate) (PHEMA), poly(glucosyloxyethyl methacrylate) (PGEMA), and agarose. Under an optical microscope, we observed a thin, continuous HAp layer on the top surface of the PVA, PHEMA, and PGEMA gels. On the other hand, we only observed an intermittent HAp layer on the surface of the agarose gel. The swelling ratio and the bound water content of these hydrogels were measured as an essential character in HAp formation. There was some relation among the HAp formation, the swelling ratios, and the bound water content.

Calcinosis↗

PubMed1978

A comparison of iron histochemical methods for use on glycol methacrylate embedded tissues.

Four histochemical tests for iron and four procedures for its removal were investigated in regard to their suitability for glycol methacrylate embedded tissues. The HCl-ferrocyanide and chlorate hematoxylin methods were easily modified for plastic sections. The latter does not use iron-containing reagents. Desiderization was complete both after a fifteen minute exposure in 1% Na2S2O4 in 0.1 M acetate-HCl buffer (pH 4.5) and, if an acid method is preferred, after twelve hours in 5% oxalic acid. A six hour treatment in 3.7 N H2SO4 also removed all histochemical iron but was accompanied by a relatively greater loss of tissue basophilia.

Animals↗

PubMed1979

Immunohistological staining of antigens on semithin sections of specimens embedded in plastic (GMA-Quetol 523).

Glycol methacrylate-Quetol 523, introduced by Kushida (1977) for combined light and electronmicroscopy studies at low magnification, also permits application of immunofluorescence methods to semithin sections. To recover the antigenicity of proteins fixed with formaldehyde, abrupt dehydration before embedding and subsequent treatment of the semithin sections with protease were essential. Post-staining with suitable histological stains allows exact correlation of antigen localization with tissue structure.

Acrylic Resins↗

PubMed1979

Poly-HEMA sponge: a biocompatible calcification implant.

Poly-hydroxyethyl methacrylate (Poly-HEMA) was investigated for biocompatibility and calcification potential. S.C. and I.M. implants and transplants to subperiosteal sites were examined. The material was judged to be tolerated by the host tissue since no inflammatory or degenerative changes were observed. This study established that calcification does occur. This calcification does not simulate bone formation; osteoblasts were not observed. The x-ray diffraction pattern resembles that of calcium hydroxyapatite.

Acrylic Resins↗

PubMed1983

Improved techniques using Giemsa stained glycol methacrylate tissue sections to quantitate basophils and other leukocytes in inflammatory skin lesions.

Improved techniques were developed for processing inflammatory skin lesions in glycol methacrylate (JB-4, Polysciences, Inc.) and for quantitating their leukocyte infiltrates by light microscopy: (1) fixation of entire pelts from rabbits, guinea pigs, rats and mice bearing multiple lesions eliminated artifacts due to biopsy and produced uniformly oriented skin sections; (2) adding dimethylsulfoxide and hydrogen peroxide to the Karnovsky-type fixative increased the rate and effectiveness of fixation; (3) the presence of glycerol in the infiltrating methacrylate and the polymerized plastic block improved the sectionability of skin and other tissues; (4) coating slides with JB-4 Solution A prevented detachment of specimens; (5) Giemsa staining at a carefully selected pH provided optimal differentiation of leukocytes from the several species examined, including man. These techniques, which allowed an accurate histologic assessment of inflammatory skin lesions, were especially valuable for quantitating basophils.

Animals↗

PubMed1989

Fat intestinal absorption in the catfish--a histochemical study in glycol methacrylate embedded tissue.

The intestinal absorption of lipids was investigated in plastic sections from glycol methacrylate embedded intestine after fat administration. In the catfish, the lipids are absorbed by the enterocytes of the proximal intestinal segment, thus forming fat cytoplasmic inclusions that were demonstrated by Sudan black B staining. The histochemical characterization of lipids by the Nile blue sulphate test revealed the neutral or triglyceride nature of the cytoplasmic droplets, both after the corn oil and oleic acid feeding. There is lipid accumulation in the lamina propria and lymphatic vessels.

Animals↗

PubMed1980

Delivery of the topical antimicrobial agents silver sulfadiazine, gentamicin and nystatin to infected burn wounds in rats from preloaded synthetic dressings.

1. A synthetic burn dressing made from polyethylene glycol - 400 (PEG) and poly-2-hydroxyethyl methacrylate (PHEMA) can be prepared to contain topical antimicrobial agents. 2. Sheets of these antimicrobial loaded dressings may be applied to the wounds or alternatively, the synthetic dressing incorporating the active drugs may be formed directly on the burn wound from the PEG-PHEMA drug mixture. 3. The antimicrobials (silver sulfadiazine, gentamicin and nystatin) are continuously and effectively released from the solid dressing over 2-11 days.

Animals↗

PubMed1990

Silicone rubber-hydrogel composites as polymeric biomaterials. II. Hydrophilicity and permeability to water-soluble low-molecular-weight compounds.

The surface and transport properties of water-swollen silicone rubber-hydrogel composites were investigated. Surface wettability of these materials, composed of a polysiloxane matrix and the hydrogel phase consisting of very fine particles of lightly cross-linked poly(2-hydroxyethylmethacrylate), increased markedly with increasing content of the hydrogel phase. For composite materials containing a lightly cross-linked 2-hydroxyethylmethacrylate (HEMA)-methacrylic acid (MAA) copolymer and polymethacrylic acid (PMAA) as the hydrogel phase, permeability to water-soluble organic compounds and drugs were measured. The permeability varied within a broad range depending on the composition and content of the hydrogel phase. High permeation rates could be obtained while still retaining relatively fair mechanical properties. Relationships between the composition of silicone rubber-hydrogel composites, their structure and the permeation coefficients of the individual permeates are discussed.

Biocompatible Materials↗

PubMed1983

Cell shape and phenotypic expression in chondrocytes.

The relationship between cell shape, proliferation, and phenotypic expression was studied in human chondrocytes. Shape was controlled independent of serum concentration, anchorage, and cell density by alteration of substratum adhesiveness with poly(2-hydroxyethyl methacrylate) (poly[HEMA]). Cells that were held rounded displayed features of the chondrocyte phenotype; i.e., they were round, proliferated slowly, incorporated low levels of [3H]thymidine into DNA, and incorporated large amounts of 35SO4 into glycosaminoglycans. In contrast, cells that were held flat were fibroblast-like: they exhibited flattened morphology, more rapid growth, greater incorporation of [3H]thymidine, and less incorporation of 35SO4. These studies suggest that cell shape may play an important role in phenotypic expression in chondrocytes.

Cartilage↗

PubMed1985

Effect of age on calcification of poly(hydroxyethyl methacrylate) in animals.

The effect of age on the calcification of biomaterials was studied by the subcutaneous implantation of poly(hydroxyethyl methacrylate) hydrogel in rats. The hydrogel sheets were implanted in rats 6, 12, 24, and 52 weeks (1 year) of age. The retrieved implants were compared and the percentage weight increase by mineralization was determined quantitatively. Significant differences in the rate and amount of calcification were observed between the growing (6 weeks old) and the adult (greater than or equal to 12 weeks of age) rats. The onset of calcification in the adult rats was significantly delayed. The immature rats had deposits three to four times as heavy as the mature rats.

Age Factors↗

PubMed1992

An interpretation of cell separation mechanism on polyamine graft copolymers.

Interaction between polyamide microcapsules having different balances of negative and positive charges on their surface, that is, different isoelectric points and copolymers with different numbers of polyamine macromer of a definite chain length grafted on poly(2-hydroxyethyl methacrylate) backbone was studied by measuring the amount adhered of the microcapsules onto the surface of copolymer-coated glass beads at different pH values. Maximum microcapsule adhesion was observed for a proper combination of microcapsule and copolymer to suggest that separation of a specified cell population from others on the surface of copolymer-coated glass beads can be explained in terms of preferential adhesion through electrostatic interaction of the specified cells with the copolymer.

Cell Separation↗

PubMed1994

Poly(vinyl alcohol) hydrogels as soft contact lens material.

A new type of soft contact lens was developed from the poly(vinyl alcohol) (PVA) hydrogel prepared by a low temperature crystallization technique using a water-dimethyl sulfoxide mixed solvent. The PVA contact lens materials had a water content of 78% and a tensile strength of 50 kg/cm2, five times as strong as that of commercial poly(2-hydroxyethyl methacrylate) soft contact lens. The amount of proteins adsorbed to the PVA soft hydrogel material was half to one thirtieth of that of conventional soft contact lenses. Histological and scanning electron microscopic observation of rabbit eyes which had worn the PVA soft contact lens for 12 weeks showed no difference in corneal epithelium and cell arrangement in the corneal epithelium from the non-wearing eyes.

Adsorption↗

PubMed2005

Dispersion of DMPC liposomes in contact lenses for ophthalmic drug delivery.

Approximately 90% of all ophthalmic drug formulations are now applied as eyedrops. Although eyedrops are convenient and well accepted by patients, about 95% of the drug contained in the drops is lost due to absorption through the conjunctiva or through the tear drainage. A major fraction of the drug eventually enters the bloodstream and may cause side effects. To reduce drug loss and side effects, it is proposed to encapsulate the ophthalmic drug formulations in liposomes and to disperse the drug-laden liposomes in the lens material. Upon insertion into the eye, the liposome-laden lens will slowly release the drug into the pre-lens (the film between the air and the lens) and the post-lens (the film between the cornea and the lens) tear films and thus provide drug delivery for extended periods of time. This paper focuses on dispersing dimyristoyl phosphatidylcholine (DMPC) liposomes in poly-2-hydroxyethyl methacrylate (p-HEMA) hydrogels, which are a common contact lens material. The results of this study show that the p-HEMA gels loaded with liposomes are transparent and that these gels release drugs for a period of about 8 days. Contact lenses made of particle-laden gels are expected to deliver drugs at therapeutic levels for a few days. The delivery rates can be tailored by controlling the particle and the drug loading.

Biological Availability↗

PubMed1980

Ultrastructural visualization of concanavalin A binding sites using alkaline phosphatase-labeled Con A and ultrathin glycol methacrylate sections.

A method for the visualization of concanavalin A (Con A) binding sites by electron microscopy of glycol methacrylate sections is presented. This method, which is an application of the alkaline phosphatase-labeled Con A conjugate technique, solves the problems not only of limited penetration of chemicals into tissue blocks but also of injuries to tissue sections due to irritative reagents experienced in Con A-peroxidase staining. Glycol methacrylate sections are incubated successively with an alkaline phosphatase-labeled Con A solution and a lead citrate medium for the enzyme activity. Different kinds of tissues from adult rats have been used to test the method; tracheal cartilage, aorta and jejunum. The localization of Con A binding sites demonstrated by this method is consistent with the results of other published studies. Appropriate controls have been performed (ie., omission of the conjugated lectin, lectin plus its inhibitor) and these substantiate the specificity of the method.

Alkaline Phosphatase↗

PubMed1978

Role of cell shape in growth control.

Tissue culture plastic adhesivity was precisely varied by applying different concentrations of poly(2-hydroxyethyl methacrylate). The extent of cell spreading was thus accurately controlled so that cells cultured on these substrata could be held at any one of a graded series of quantitated cell shapes. Cell shape was found to be tightly coupled to DNA synthesis and growth in nontransformed cells. These findings suggest a mechanism that is important in growth control of mammalian cells, and provide a more fundamental interpretation of such phenomena as density dependent inhibition of cell growth and anchorage dependence.

Cell Adhesion↗

PubMedDate not supplied

Cultivation and grafting of human keratinocytes on a poly(hydroxyethyl methacrylate) support to the wound bed: a clinical study.

Cultured epithelial sheets on a textile support are used for the treatment of seriously burned patients. In this study we demonstrate a new procedure for the grafting of keratinocytes directly on a polymer cultivation support. This procedure is much easier in comparison with classical techniques, and encouraging results of clinical trials demonstrate the improved healing of the wound bed after the use of this procedure. There is no difference in the cytokeratine pattern (LP-34, cytokeratin-10) of the reconstructed epidermis and normal human skin.

Adult↗