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At least 19 recordsLinked to original sources
PubMed1979

Controlled drug dissolution by radiation-induced polymerization in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer or methacrylic acid-methyl acrylate copolymer.

Polymer-containing tablet preparation was studied using radiation-induced polymerization of glass-forming monomers at low temperatures in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer or methyl acrylate-methacrylic acid copolymer. Drug dissolution from tablets was in the pH 3.0-8.0 range. A copolymer contained in the tablets dissolved in the dissolution medium at a specific pH. Drug dissolution from tablets took place rapidly at pH greater than 6.0 in the presence of methyl acrylate-methacrylic acid copolymer and at pH less than 5.0 in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer. The polymers had fibrous or capillary pore structures in contrast to the spherical pore structures formed in the presence of polyethylene glycol 600.

Acrylic Resins↗
PubMed1979

Controlled release of tetracycline I: In vitro studies with a trilaminate 2-hydroxyethyl methacrylate-methyl methacrylate system.

A membrane-controlled drug delivery device was developed to release tetracycline at zero-order rates. The tetracycline delivery vehicle is a trilaminate disk consisting of core and coating membranes fabricated from a series of 2-hydroxyethyl methacrylate and methyl methacrylate copolymers. Appropriate adjustment of the monomer composition ratio imparts a hydrophobic nature to the copolymer outer coating membrane (relative to the core material), which serves as the rate-limiting membrane in drug diffusion. The trilaminate disks demonstrated a zero-order tetracycline release over 4 months in vitro. The zero-order release rate was a function of the general device geometry, coating membrane thickness, disk surface, area, level of core reservoir drug loading, and membrane coating copolymer composition. Permeability parameters of tetracycline diffusion through a series of 2-hydroxyethyl methacrylate-methyl methacrylate copolymer membranes were determined by a flux-lag time method. Equilibrium hydration values of these membranes also were determined. The ability of trilaminate 2-hydroxyethyl methacrylate-methyl methacrylate devices to release tetracycline at constant rates over a prolonged period offers unique therapeutic and investigational possibilities.

Acrylates↗
PubMed1988

Genotoxicity of acrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate in L5178Y mouse lymphoma cells.

A series of monomeric acrylate/methacrylate esters (methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate) as well as acrylic acid were examined for genotoxic activity in L5178Y mouse lymphoma cells without exogenous activation. All five compounds induced concentration-dependent increases in mutant frequency. Small-colony, trifluorothymidine-resistant mutants were primarily induced, which suggests that these compounds may act via a clastogenic mechanism. This prediction was confirmed by the finding that all five compounds produced gross chromosome aberrations in mouse lymphoma cells. The two acrylates were much more potent in their response than acrylic acid. Methyl acrylate (22 micrograms/ml, survival = 18%) induced 385 mutants/10(6) survivors (total mutant frequency less the spontaneous mutant frequency) and 45 chromosome aberrations/100 cells analyzed (total aberrations less the spontaneous background). Ethyl acrylate (37.5 micrograms/ml, survival = 15%) induced 683 mutants/10(6) survivors and 48 aberrations/50 cells analyzed. Acrylic acid (500 micrograms/ml, survival = 22%) induced 245 mutants/10(6) survivors and 37 aberrations/100 cells analyzed. The two methacrylates required higher concentrations to induce a positive response. Methyl methacrylate (2,799 micrograms/ml, survival = 11%) induced 230 mutants/10(6) survivors and 29 aberrations/200 cells analyzed. Ethyl methacrylate was extremely difficult to test because of a plateau in the dose response, over which the toxicity fluctuated from 2% to 37% survival. Positive responses (twice the spontaneous background) were only obtained at toxicity levels with less than approximately 20% survival. A concentration of 1,626 micrograms/ml (survival = 16%) induced 83 mutants/10(6) survivors and 11 aberrations/200 cells analyzed. The evidence suggests that the genotoxicity of these compounds is most likely due to a clastogenic mechanism.

Acrylates↗
PubMed1988

pH-dependent swelling and solute diffusion characteristics of poly(hydroxyethyl methacrylate-co-methacrylic acid) hydrogels.

Poly(hydroxyethyl methacrylate-co-methacrylic acid) hydrogels can swell extensively in a high-pH medium where the carboxyl groups are ionized. The swelling equilibrium is a strong function of the methacrylic acid composition of the polymer and pH of the medium. The nonionized gel structure was found to be rather insensitive to the amount of cross-linker, tetraethylene glycol dimethacrylate (TEGDMA), incorporated, within the range of 0.5 to 3%. This result is supportive of the existence of secondary interactions that shield the effect of covalent cross-links. Phenylpropanolamine (PPA) was used as a probe solute to study the diffusion characteristics of the poly(HEMA-co-MA) gels. Its diffusion coefficient in the swollen matrices of different methacrylic acid compositions at various pH's was measured via a desorption method. It is evident that these diffusion coefficients follow Yasuda's free volume theory, which expresses an exponential relationship between the solute diffusivity in a swollen polymer membrane and the reciprocal of the membrane hydration. Although interactions exist between PPA and the hydrogel matrix, these interactions are not significant enough to perturb the free volume relationship established. This observation can be explained by the high ionic strength of the system.

Acrylates↗
PubMed1976

Toxicology of methyl methacrylate: the rate of disappearance of methyl methacrylate in human blood in vitro.

1. The rate of disappearance of methyl methacrylate in blood has been determined using an isotope dilution technique. 2. At a concentration of 10(-4) mol dm(-3), methyl methacrylate disappears with pseudo first order kinetics. 3. The half-life of methyl methacrylate in blood at 37 degrees C lies in the range 20--40 min. 4. The half-life showed no dependence on the age or sex of the blood donor. 5. A major, possibly the only, pathway of metabolism is by hydrolysis to methacrylic acid.

Adult↗
PubMed1987

Glycol methacrylate embedding in histotechnology: the hematoxylin-eosin stain as a method for assessing the stability of glycol methacrylate sections.

Glycol methacrylate (GMA) samples containing inhibitor in the range of 200-300 ppm were included in a standard embedding mixture. The pH of the GMA samples was measured as a 10% solution of the sample in distilled water. The acidity of GMA due to methacrylic acid causes background staining of sections after basic dyes. The concentration of GMA and the amount of impurities such as methacrylic acid (MA) and ethylene glycol dimethacrylate (EDMA) were measured by gas chromatography. Distinct variations in purity were found among five samples of GMA. Sections derived from GMA samples containing more than 2% EDMA showed few, if any, minifolds after staining with hematoxylin and eosin and were more stable in alcoholic and basic solutions; sections from purer GMA showed minifolds and were less stable. Addition of crosslinkers, EDMA or triethylene glycol dimethacrylate (TEDMA) prevented these artifacts. Crosslinkers clearly influence dimensional changes in sections. Addition of crosslinkers to GMA samples containing minimal amounts of MA improved the results. The possibility of obtaining a high quality GMA embedding medium is discussed.

Acrylates↗
PubMed1989

The short-term blood biocompatibility of poly(hydroxyethyl methacrylate-co-methyl methacrylate) in an in vitro flow system measured by digital videomicroscopy.

An in vitro flow system for short-term blood biocompatibility testing of solution-castable polymeric biomaterials was developed. This system was relatively free of artefacts resulting from blood contact with materials other than the test material itself. In conjunction with epifluorescence videomicroscopy and digital image processing, this method provided a high resolution, quantitative, continuous analysis of platelet adhesion, aggregation, thrombus formation, and embolization on the biomaterial surface. This system was well suited for performing biochemical assays on post-contact blood for assessment of platelet activation and release as additional measures of the thrombogenicity of the test material. This method for biomaterials evaluation in vitro was demonstrated by a detailed examination of copolymers of hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA). Videomicroscopic analysis of fluorescently labelled platelets adhering per unit area of the polymer surface after 5 min of flow at a wall shear rate of 500 s-1 showed a dramatic decrease with increasing HEMA fraction in the polymer. The release of serotonin and thromboxane A2 by platelets decreased with increasing HEMA fraction. Reflection interference contrast microscopy was used to examine focal contacts of platelets on the copolymer surfaces as a qualitative measure of the platelet-surface interaction. A polymer-dependent gradation in contact extent and morphology was observed, ranging from large contacts on P(MMA) to none on P(HEMA).

Biocompatible Materials↗
PubMed1991

Platelet adherence and detachment: a flow study with a series of hydroxyethyl methacrylate-ethyl methacrylate copolymers using video microscopy.

The adhesion and detachment of platelets were studied on glass coatings of a series of copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA). Observations of the interactions of mepacrine labelled washed platelets with these surfaces from a flowing (500 s-1 wall shear rate) suspension in Tyrode's solution containing albumin and red cells were made with epifluorescent video microscopy (EVM). Total platelet adhesion, including platelets which adhere on first contact and platelets which attach temporarily before adhesion, and the number of detaching platelets were minimal for the 0 and 20% EMA copolymers, reached a maximum for the 50% EMA copolymer and showed reduced values for the 80% and 100% EMA copolymers. For the 50, 80, and 100% EMA copolymers, the adhesion values expressed, as a percentage of total contacting platelets, were not different. Albumin adsorption to these copolymers shows a continuous increase from the 0% to the 100% EMA copolymer. It is likely that the peak in platelet adhesion at the 50% EMA composition is related to: low protein adsorption on the 0 and 20% EMA copolymers, too little albumin adsorption to block adhesion on the 50% EMA copolymer, and full-scale blocking on the 80 and 100% EMA copolymers due to greater albumin adsorption.

Adult↗
PubMed1992

Platelet adherence and detachment with adsorbed fibrinogen: a flow study with a series of hydroxyethyl methacrylate-ethyl methacrylate copolymers using video microscopy.

The adhesion and detachment of platelets were studied on glass coatings of a series of copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) with preadsorbed fibrinogen. Observations of the interactions of acridine-orange-labeled washed platelets with these surfaces from a flowing (500 s-1 wall shear rate) suspension in Tyrode's solution containing albumin and red cells were made with epifluorescent video microscopy (EVM). In some cases preadsorbed materials were incubated for 24 h, during which little or no loss of protein occurred. Protein surface concentration, by itself, was a poor indicator of expected cell adhesion and morphology. Surface chemistry was a second important factor which must be considered. A third observation is that for the 100% EMA copolymer, 24 h of incubation led to a large reduction in platelet adhesion when compared to the 100% EMA material without incubation. For the 0% and 100% EMA polymers, the percentage of contacting platelets which adhere and detach is greater for the 24-h incubation cases than for those not incubated. These results led to the conclusion that our most hydrophilic surface favors adhesion with detachment, transient cell contact, over long-term adhesion, as does incubation of adsorbed protein. A brief discussion is presented of a possible connection between this behavior and platelet consumption in vivo for hydrogels.

Adsorption↗
PubMed1990

Surface properties of copolymers of alkyl methacrylates with methoxy (polyethylene oxide) methacrylates and their application as protein-resistant coatings.

New polymeric surfactants, copolymers of alkyl methacrylates with methoxy (polyethylene oxide) methacrylates, were synthesized and characterized by gel permeation chromatography. They were studied as possible means to produce polyethylene oxide-rich surfaces by a simple coating treatment on common hydrophobic medical materials. They were further studied as cleaners for the removal of proteins preadsorbed on hydrophobic surfaces. The surface properties of the copolymers such as the adsorption properties of the copolymer on a hydrophobic surface, low density polyethylene, the protein-resistant character of the prepared polyethylene oxide surfaces and the effectiveness of the copolymers for removal of proteins pre-adsorbed on the surface, were investigated by X-ray photoelectron spectroscopy and by using 125I-labelled copolymers and 125I-labelled proteins. The surface properties of the synthesized copolymers were compared with those of commercially available polyethylene oxide containing block copolymer surfactants.

Adsorption↗
PubMed1991

Study on antithrombogenicity of poly[beta-(acetylsalicylyloxy)ethyl methacrylate] relative to poly(hydroxyethyl methacrylate).

The antithrombogenicity of a polymer made of aspirin bound to hydroxyethyl methacrylate (HEMA), abbreviated as ASA-polymer, was compared with that of poly(hydroxyethyl methacrylate) (PHEMA). Platelet from platelet rich plasma (PRP) incubated with ASA-polymer surface exhibited noticeable decreases in adhesion and aggregation as compared to platelets incubated with PHEMA. Low molecular weight components other than aspirin, which may be released from ASA-polymer during the incubation with PRP, or contact with ASA-polymer causing denaturation of platelets without morphological changes could be responsible for the decrease of adhesion and aggregation. Both PRP and PPP exposed to ASA-polymer-coated surfaces exhibited a much smaller partial thromboplastin time (PTT) than if exposed to PHEMA-coated surfaces; the PTT of ASA-polymer was similar to that of glass exposed plasma. With respect to the in vivo antithrombogenicity, the ASA-polymer surface led to thrombus formation. This may be due to the partial hydrolysis of the acetyl groups resulting in the formation of a negatively charged surface which in turn accelerates the coagulation cascade despite its inhibitory effects on platelet adhesion and aggregation. On the other hand, neointima formed around a thrombus layer on PHEMA-coated sutures after 14 days.

Animals↗
PubMed1988

Microencapsulation of mammalian cells in a hydroxyethyl methacrylate-methyl methacrylate copolymer: preliminary development.

Erythrocytes were microencapsulated in a thermoplastic copolymer of poly-2-hydroxyethyl methacrylate (79% mole%) - co-methyl methacrylate (21 mole %) with little apparent initial cell lysis. Droplets of cell suspension and polymer solution were blown from the tip of a coaxial needle assembly into a receiving bath of hexadecane over phosphate buffered saline (PBS) containing a low concentration of nonionic surfactant. Capsules were trapped at the hexadecane/PBS interface where they were cured by the removal of polymer solvent to precipitate a polymer coating around the cell suspension. Important principles which were considered in the development of the successful process, included the need to prevent intermixing of polymer solution and cell suspension, to fully surround the cells with polymer solution prior to precipitation, and to prevent direct mixing of the curing bath with the polymer solution.

Artificial Organs↗
PubMed1976

Tissue reaction to methyl methacrylate monomer. A comparative study in the rabbit's ear on the toxicity of methyl methacrylate monomer of varying composition.

The aim of the present investigation was to evaluate if a bone cement monomer with a high concentration of accelerator (N,N-dimethyl-p-toluidine) is more toxic than a methyl methacrylate monomer, free from accelerator. 1) No difference in the acute local toxicity between CMW, Simplex-P and pure methyl methacrylate monomer was seen. 2) By gas chromatography. N,N-dimethyl-p-toluidine was shown to be water soluble to a small extent. Any bone cement monomer in current use can be fully dissolved in saline to a concentration of about 1 per cent.

Animals↗
PubMed1975

[Studies on the dental methacrylic resins (part 4). Flow properties and curing times of the pour methacrylic resins (author's transl)].

Flow properties and curing times of the pour resins consisted of polymethyl methacrylate and methyl methacrylate were investigated by the viscosity and the temperature measurements. The polymers with various article sizes and molecular weights and the monomer with 0.005 per cent hydroquinone were used the pour resins respectively. The initiator system of benzoyl peroxide--N, N-dimethyl-p-toluidine was used for the polymerization. The results were as follows: 1) The viscosities of the pour resins were increased with the time elapsed. That was for reasons of physical phenomenon, that is, dissolution of polymer into monomer. The logarithmic viscosities increased linearly in proportion to the time elapsed. 2) The viscosities of the pour resins were increased by the reduction of the particle size of the polymer and by the increase of the molecular weight of the polymer. 3) The curing times of the pour resins were reduced by the increase of the concentrations of benzoyl peroxide and N, N-dimethyl-p-toluidine, and by the reduction of the particle size and the molecular weight of the polymer respectively.

Acrylic Resins↗
PubMed1979

[Studies of dental methacrylic resin. (Part. 6) Adhesive strength of self-curing methacrylic resin to polymethylmetacrylates with various cross-linking density. (author's transl)].

The adhesive property of dental acrylic resin to resin teeth and denture base resins is an important property, in the case of preperating, repairing and rebasing denture. Then, as models of denture base resin and resin tooth, heat-curing methacrylic resins which were cross-linked with three kinds of polyethylene glycol dimethacrylate, i.e., EDMA, tri-EDMA, nona-EDMA, were prepared, and the tensile adhesive strengths of self-curing methacrylic resin to them were examined. The results were as follows. 1) The tensile adhesive strength under the dry condition was dependent on cross-linking density of adherent resin, and decreased according to the increase of concentration of cross-linking agent added in adherent resin. 2) The greater the number of chain members of cross-linking agent used to adherent resin was, the higher the adhesive strength was. In particular, the adhesive strength to adherent resin added with nona-EDMA in concentration from 16.7 to 30 mole%, agreed with the tensile strength of adherent resin itself indicating a favourable adhesion. 3) The adhesive strengths under the wet condition, that is, when specimens were immersed in water at 37 degrees C for 21 days, decreased from 30 to 50%, compared with that under the dry condition.

Acrylic Resins↗
PubMed1979

[Studies of dental methacrylic resin. (Part 7) Adhesive strength of fluid methacrylic resin to polymethylmethacrylates with various cross-linked density (author's transl)].

Heat-curing methacrylic resins cross-linked with three kinds of dimethacrylates, i.e. EDMA, tri-EDMA and nona-EDMA, were prepared, and the tensile adhesive strength of fluid methacrylic resin to them was examined. The results obtained were as follows. (1) To adherent resin cross-linked with EDMA, the adhesive strength of fluid resin showed the maximum at the concentration near 2 mole% and decreased with increasing the concentration. (2) To adherent resin cross-linked with tri-EDMA or nona-EDMA, the effect of the concentration of cross-linking agent on the adhesive strength was little, except that the adhesive strength to the latter adherent resin showed a steep increase in the range of lower concentration. (3) The adhesive strength did not appreciably change in the range of L/P ratio of fluid resin from 0.57 to 0.71 ml/g. (4) The adhesive strength under the wet condition decreased about 40 to 50% compared under the dry condition. (5) To cross-linked adherent resin, the adhesive strength of fluid resin was somewhat higher than that of self-curing resin under the dry condition. But, under the wet condition this difference was little. (6) Contrarily, to non-cross-linked adherent resin, the adhesive strength of fluid resin was somewhat lower than of self-curing resin. This may be because the cracks, which are occured on the surface of non-cross-linked adherent resin by contact with abundant MMA of fluid resin, work as defects to decrease the adhesive strength.

Acrylic Resins↗
PubMed1976

Affinity chromatography on hydroxyalkyl methacrylate gels. III. Adsorption of chymotrypsin to poly(hydroxyalkyl methacrylates) with covalently bound benzyloxycarbonyl-glycyl-D-phenylalanine and -D-leucine as function of pH and ionic strength.

Chymotrypsin is specifically adsorbed at low ionic strength and alkaline pH to hydroxyalkyl methacrylate gels with N-benzyloxycarbonylglycl-D-phenylalanine or N-benzyloxycarbonylglycyl-D-leucine attached through 1,6-hexanediamine. Chymotrypsin is not adsorbed either to the unmodified gel (Spheron) or to the gel with attached, 1,6-hexanediamine (NH2-Spheron). The adsorption of chymotrypsin to Z-Gly-D-Phe-NH2-Spheron was investigated as a function of pH and ionic strength. Trypsin is not adsorbed to this gel. Chymotrypsin isolated from a crude pancreatic extract by affinity chromatography on Z-Gly-D-Phe-NH2-Spheron had the same activity as the enzyme isolated on a column of Spheron, to which the naturally-occurring trypsin inhibitor had been coupled.

Binding Sites↗