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PubMed2005

Improving polylactide/starch biocomposites by grafting polylactide with acrylic acid--characterization and biodegradability assessment.

In this article, the properties of a polylactide and starch composite (PLA/starch) and an acrylic acid grafted polylactide and starch composite (PLA-g-AA/starch) were compared. The composite containing PLA-g-AA was found to have much better dispersion and homogeneity of starch in the polymer matrix than the composite containing PLA, indicating better compatibility between the two phases. Better mechanical and thermal properties of the PLA-g-AA/starch composite, notably an increase in tensile strength and elongation at breakpoint, evidenced its superiority to the PLA/starch composite. Furthermore, the lower viscosity of PLA-g-AA/starch makes it easier to process than PLA/starch. Weight loss on exposure to a soil environment over a period of three months showed that the starch in the composites was almost completely biodegradable, even at a high degree of substitution (60 wt.-% starch). After three months in soil, a reduction in the mechanical properties of the blends was observed, especially in those with higher starch contents.

Acrylates↗
PubMed2005

Amphipathic and membrane-destabilizing properties of the cationic acrylate polymer Eudragit E100.

The cationic acrylate polymer Eudragit E100 (E100) produces a biphasic effect on the stability of casein micelles disrupting their internal structure. These results suggested that this polymer could have some amphipathic character. Therefore, in this study the polymer was characterized with respect to its interaction with different amphipathic systems (bile-acid micelles, lipoproteins and liposomes), cell membranes (red blood cells) and virus membranes (Herpes simplex type 2 virus). As with caseins, a biphasic effect was observed with bile acids with a precipitation phase at low polymer/bile acid ratio and a solubilization phase when the polymer concentration was increased. Upon interaction with human plasma, an important reduction in cholesterol and triglycerides was observed upon remotion of E100 by a rise in pH to 8.5 and centrifugation. In agreement with this finding, an important reduction in plasma lipoproteins was observed upon its treatment with E100 and further remotion by pH rise and centrifugation. However, the amount of the major protein components of human plasma and the activity of several enzymes and antibodies were not affected by their treatment with E100. The membrane-destabilizing properties of E100 were confirmed by its lytic activity on liposomes and red blood cells and by an important antiviral effect of E100 on Herpes simplex virus type 2. Altogether, these results show that, despite its water solubility and cationic character, E100 displays a significative amphipathic and membrane-destabilizing character with potential biotechnological applications. [diagram in text].

Acrylates↗
PubMed2005

Microstructure formation and property of chitosan-poly(acrylic acid) nanoparticles prepared by macromolecular complex.

We report here a study on the microstructure formation process of polymeric nanoparticles based on polyelectrolyte complexes. When polyanion poly(acrylic acid) (PAA) was dropped into polycation chitosan (CS) solution, CS-PAA nanoparticles with diverse microstructure would be formed under different experimental conditions. The microstructure of CS-PAA nanoparticles changed from solid spherical nanoparticles to core-shell separative ones and turned back to solid spherical ones with the variation of preparation conditions. The influence of molecular weight of CS and PAA, shell cross-linking, dropping temperature on the size, stability and morphology of CS-PAA nanoparticles were also studied. The nanoparticle size was affected by the molecular weight of CS and PAA, the ratio of amino group to carboxyl group (na/nc) and the incubation temperature as well. The shell-cross-linking provides a means to stabilize these nanoparticles. These nanoparticles can encapsulate plasmid DNA very well, which makes them have great potential in gene delivery.

Acrylates↗
PubMed2005

Preparation and characterisation of thermoresponsive poly[(N-isopropylacrylamide-co-acrylamide-co-(hydroxyethyl acrylate)] microspheres as a matrix for the pulsed release of drugs.

Despite the large number of publications and patents concerning pH/thermoresponsive polymers, few data are available concerning the preparation of thermoresponsive cross-linked microspheres from preformed polymers. Therefore, N-isopropylacrylamide-co-acrylamide-co-(2-hydroxyethyl acrylate) copolymers were obtained as a new thermoresponsive material with a lower critical solution temperature (LCST) around 36 degrees C, in phosphate buffer at pH 7.4, and with a cross-linkable OH group in their structure. The LCST value was determined both by UV spectroscopy and microcalorimetric analysis. These copolymers were solubilised in acidified aqueous solution below their LCST, dispersed in mineral oil, and transformed into stable microspheres by cross-linking with glutaraldehyde. The thermoresponsive microspheres were characterised by optical and scanning electron microscopy, degree of swelling, and water retention. The pore dimensions of the microspheres and the retention volumes of some drugs and typical compounds were evaluated at different temperatures by liquid chromatography. Indomethacin, as a model drug, was included in the microspheres by the solvent evaporation method. Finally, the influence of temperature and of temperature cycling on drug release was investigated.

Acrylamides↗
PubMed2006

Rapid and precise release from nano-tracted poly(N-isopropylacrylamide) hydrogels containing linear poly(acrylic acid).

We investigated the rapid and precise molecular release from hydrogels in response to dual stimuli. To achieve precise on/off drug release using thermoresponsive poly(N-isopropylacrylamide) hydrogels, we prepared nano-structured semi-IPNs, which consisted of thermosensitive PNIPAAm networks penetrated by pH-responsive poly(acrylic acid) (PAAc) linear chains and perforated to create nano-tracts as a molecular pathway. The present nano-tracted semi-IPNs show a rapid deswelling response to both temperature and pH. Model drug releases were investigated when simultaneous changes in temperature and pH were applied. We observed that the cationic drug was rapidly released and then abruptly discontinued from the nano-tracted semi-IPNs in response to the dual stimuli, and clear release and stopping cycles were repeatedly observed on successive steps. Moreover, the release rates and amount of drug released were controllable by the deswelling speed of the gels and the PAAc content inside the gels. This novel release system using the nano-tracted semi-IPNs may be useful for the high performance, pulsed release of molecules.

Acrylamides↗
PubMed1993

Metabolism of acrylic acid to carbon dioxide in mouse tissues.

Acrylic acid (AA) is acutely irritating at sites of initial contact but causes little systemic toxicity probably due to its rapid metabolism to CO2 and acetyl-CoA via a secondary pathway of propionic acid catabolism. In this study, the rate of AA oxidation in 13 tissues of C3H mice was measured by incubating tissue slices with [1-14C]AA and collecting, 14CO2. Oxidation of AA followed pseudo-Michaelis-Menten kinetics in the liver, kidney, and skin. Pseudo-Km values were similar among these tissues and averaged 0.67 mM. The maximal rate of AA oxidation in kidney, liver, and skin was 2890 +/- 436 (mean +/- SE, N = 3), 616 +/- 62, and 47.9 +/- 5.8 nmol/hr/g, respectively. The remaining organs oxidized AA at rates less than 40% of the rate in liver. Rates of metabolism in tissues from male and female mice were similar. 3-Hydroxypropionic acid was the only metabolite detected by high-performance liquid chromatographic analysis following incubation of tissues with [1-14C]AA. Kidney and liver also oxidized [2,3-14C]AA and [1-14C]acetate well, thus providing for the complete metabolism of AA carbons to CO2. These results demonstrate that the rate of AA metabolism varies significantly among mouse tissues and suggest that the kidneys and liver are major sites of detoxification of AA.

Acrylates↗
PubMed1994

Evaluation of subchronic (13 week), reproductive, and in vitro genetic toxicity potential of 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate (Octocrylene).

Use of 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate (Octocrylene) in commercial sunscreen products has increased considerably in recent years. To support larger scale human exposure to this compound, additional toxicological information was needed in several key areas. The present studies evaluated subchronic toxicity, developmental toxicity, and in vitro genotoxic potential of Octocrylene. In the subchronic study, male and female New Zealand white (NZW) rabbits treated topically with concentrations of octocrylene up to 534 mg/kg/day for 13 weeks showed slight to moderate dose-dependent skin irritation that correlated positively with a mild depression in body weight gain. Lack of associated histopathologic or clinical hematology abnormalities suggested that the body weight effect probably reflected a nonspecific response to topical irritation. In percutaneous developmental toxicity studies, NZW does were treated topically with Octocrylene at levels up to 267 mg/kg/day on Days 6 through 18 of gestation. Body weight gain, food consumption, and all maternal, reproductive, and offspring parameters evaluated were comparable between Octocrylene-treated and control animals. In the oral developmental toxicity assay, female CD-1 mice received oral doses of Octocrylene up to 1000 mg/kg/day on Days 8-12 of gestation. No evidence of maternal or developmental toxicity was seen at any dose tested. Genotoxicity was evaluated in vitro using the Chinese hamster ovary cell assay to assess clastogenicity and the mouse lymphoma cell assay to assess forward gene mutations. Octocrylene did not induce any significant increase in genotoxicity. This evaluation of toxicological potential supports the use of Octocrylene as a human photoprotectant.

Acrylates↗
PubMed1993

Quantitation of an epithelial S-phase response in the rat forestomach and glandular stomach following gavage dosing with ethyl acrylate.

Gavage dosing of the irritant, ethyl acrylate (EA), has been found to induce hyperplasia in the rat forestomach, but no signs of toxicity in the glandular stomach or in organs remote from the site of dosing. To quantitatively describe this effect as a background for subsequent modeling studies, pulse measurements of the number of S-phase cells were made following a single gavage dose of EA. The time-course of the S-phase response in the forestomach epithelium following a high dose (200 mg/kg or a 4% solution in corn oil) indicated that the number of S-phase nuclei was decreased relative to control animals immediately following gavage dosing with a minimum at 6 hr, but that the number of S-phase nuclei increased significantly above control values by 20 hr and remained significantly elevated until at least 48 hr following the gavage dose. A single-dose dose-response study with gavage doses of 0, 2, 10, 20, 50, 100, or 200 mg/kg EA and S-phase analysis at 24 hr following gavage dosing indicated that a significant increase in S-phase nuclei was evident at doses of 20 mg/kg or higher. Dosing with EA for 2 weeks at dose levels of 0, 10, 50, or 200 mg/kg caused a prolonged elevation of S-phase nuclei only at the 200 mg/kg dose level during the 24 hr following the last gavage dose. Lower doses did not induce a significant increase in the S-phase nuclei. In contrast to the forestomach, the S-phase response of the glandular stomach was transient following a single 200 mg/kg gavage dose, and only a marginal response was observed following multiple 200 mg/kg doses. No effects were observed at lower doses. Comparison of these results to prior determinations of the effect of EA on the concentration of nonprotein sulfhydryls (primarily glutathione) in the forestomach and glandular stomach indicate a correlation of the stimulation in S-phase activity in the forestomach with the repletion and overshoot of tissue nonprotein sulfhydryl levels.

Acrylates↗
PubMed1998

Investigation of the positive response of ethyl acrylate in the mouse lymphoma genotoxicity assay.

To develop a better understanding of the relationship between ethyl acrylate (EA)-induced cytotoxicity and mutation frequency in the mouse lymphoma assay (MLA) we measured the effects of EA treatment to ML cells on: (1) nonprotein sulfhydryl (NPS) levels; (2) mitochondrial rhodamine 123 (Rh123) uptake; (3) the DNA elution slope (single-strand breakage) and Y intercept of fitted curves (cytotoxicity and double-strand breakage) in the alkaline elution assay; (4) the appearance of apoptosis; and (5) the pulsed-field gel electrophoretic resolution of high-molecular-weight DNA. EA reduced NPS in both a time- and concentration-dependent manner. By 30 min, > or = 20 micrograms/ml EA reduced NPS by 50% or greater. By 4 h, > or = 10 micrograms/ml markedly decreased both NPS cell content (> or = 71.5% reduction) and mitochondrial Rh123 uptake (10-50 micrograms/ml; 9-62%), the latter effect being further enhanced by washing and incubation for an additional 2 h (12-85%). EA did not induce single-strand breaks in the alkaline elution assay. Only highly cytotoxic EA concentrations (80-87% reduction in RCG at 40-50 micrograms/ml) caused both increases in the elution slope and parallel drops (Y intercept) in the elution curve in the alkaline elution assay. Conventional agarose gel electrophoretic analysis of the DNA neutral fraction of these high dose preparations showed evidence for both apoptosis (180-bp oligonucleosomal DNA laddering effect) and random smearing of DNA (necrosis). Pulsed-field gel electrophoresis of directly loaded high dose cell preparations revealed both high- and low-molecular-weight DNA double-strand breaks, but only at the highest concentrations. These observations indicated that the EA-induced mutagenic response correlated best with cellular cytotoxicity mediated by NPS depletion and mitochondrial membrane impairment.

Acrylates↗
PubMed1988

Distribution and elimination of (14C)-2-ethylhexyl acrylate radioactivity in rats.

The fate of (14C)-2-ethylhexyl acrylate was studied in adult male Wistar rats given an intravenous (i.v.) or intraperitoneal (i.p.) injection of 10 mg/kg (0.054 mmol/kg). The elimination of radioactivity from blood was bi-exponential, irrespective of the route of (14C)-2-EHA administration or the age (weight) of the rats. The first phase half-lives after i.v. and i.p. administration in 4-month-old rats were 30 and 60 min, in 7-month-old rats 115 and 130 min, respectively. The corresponding values for the slow-phase were 5 and 6 h, and 14 and 14 h. Elimination of the radioactivity from tissues followed a pattern similar to that seen for blood. More than half of the administered radioactivity was exhaled as carbon dioxide. Exhalation of unchanged (14C)-2-EHA accounted for only 0.05% (i.v.) or 0.3% (i.p.) of the initial dose of radioactivity. The radioactivity excreted in the urine within the first 24 h post-treatment accounted for 7% (i.p.) or 14% (i.v.) of the initial dose, and only 2% was excreted as thioethers.

Acrylates↗
PubMed1989

Dermal oncogenicity study of 2-ethylhexyl acrylate by epicutaneous application in male C3H/HeJ mice.

A carcinogenicity bioassay of 2-ethylhexyl acrylate (2-EHA) was conducted by applying 25 microliters 86.5%, 21%, or 2.5% 2-EHA in acetone three times a week to the clipped dorsal skin of male C3H/HeJ mice (80 per group) over their lifetime. Another group was treated with a 43% 2-EHA solution for 24 weeks and thereafter observed for lifetime (stop-test). An untreated group and a group that received only the diluent acetone served as controls. Treatment-related changes in the skin indicative of irritation (scaling, scabbing, hyperkeratosis, hyperplasia) were found in all 2-EHA-treated groups. These lesions were reversible in the 43% group immediately after treatment was stopped, and in the 2.5% group after the 11th week of treatment. Only in the 86.5% and 21% test groups showing chronic irritative skin damage was there a high incidence of nepolastic skin lesions (papillomas, carcinomas, and melanomas) with no dose dependency. In contrast, no skin tumors were found in the control groups, in the group treated with 2.5% 2-EHA for lifetime or in the group treated with 43% 2-EHA for about 6 months and observed for lifetime.

Acrylates↗
PubMed1981

Whole-body autoradiography after systemic and topical administration of methyl acrylate in the guinea pig.

Whole-body autoradiography was performed in the guinea pig with methyl (2,3-14C)-acrylate. Radioactive material quickly disappeared from the body after oral and, somewhat slower, after i.p. administration for the greater part. After administration in a closed cup on the skin a slow penetration in the dermis occurred preceded by the toxic effect, mainly a strong edema. In the first 16 h metabolism was primarily restricted to the skin, internal organs showed a slow rise in radioactivity. A large part of the labeled material was retained in the dermis. The detoxification was screened by estimating the urinary thioether content and respiratory carbon dioxide. This showed that in addition to oxidation to carbon dioxide the binding to SH-groups was the principal way of metabolism.

Acrylates↗
PubMed1990

Post embedding immunoelectron microscopy of human breast cancer: a comparison of three acrylic resins.

The suitability of three acrylic resins for the immunoelectron microscopical localization of cell surface and cytoskeletal antigens in surgically excised, immersion fixed human breast cancer, using an immunogold system, has been assessed. Good localization of milk fat globule membrane was achieved with LR White, LR Gold and Lowicryl K11M, although the embedding schedule for LR White had to be modified. The best results were achieved with Lowicryl K11M. Only scanty labelling of actin and cytokeratin was seen in LR White embedded tissue, whereas there was clear localization in LR Gold and Lowicryl K11M embedded samples. Tubulin and alpha-actinin was detected at low level in tissues in the low temperature embedding resins, but not in LR White embedded samples. The morphology of the latter was poorer, and there was greater variability in ultrastructure and labelling. Of the two low temperature embedding resins, Lowicryl K11M gave slightly better results. However, the advantages could be outweighed by the problem incurred in achieving the low temperatures, and by poorer handling properties than LR Gold.

Acrylic Resins↗
PubMed1981

Acrylic fixation in displaced dens fractures.

Non-union of odontoid process fractures with displacement in old patients have been treated operatively stable acrylic fixation. Immediate mobilization without external fixation was achieved.

Acrylic Resins↗
PubMed1984

Use of acrylic prosthesis in cervical spine pathology (report of 45 cases).

The authors report on their experience with the use of a reinforced acrylic prosthesis in cervical spine pathology. The study of their own 45 cases enables the advantages and disadvantages of the technique to be demonstrated. A discussion of possible improvements in the technique and its indication completes the report.

Acrylic Resins↗
PubMed1977

[Stablization of destructive processes in the cervical spine by means of acrylic prostheses (author's transl)].

Stabilization of destructive processes in the cervical spine by means of acrylic prostheses has hitherto been carried out either by an anterior approach or by a posterior approach. With progressively destructive lesions the stability achieved by either of these methods is unsure, and therefore the author has employed a combination of both approaches. The first two patients treated with this new technique have now been followed up for two years. The position and stability of the prosthesis in each case has remained excellent.

Acrylic Resins↗
PubMed1996

Modification of the agar overlay assay: assessment of the influence of acrylics used in orthodontics on proliferation and differentiation of primary and transformed fibroblasts.

In orthodontics, removable acrylic appliances are preferably produced from methylmetacrylates. However, in the adjacent oral mucosal tissue, cell damage may be caused by the evaporation of residual monomer. The aim of this study was to modify the classic agar overlay assay in order to apply histochemical methods by comparing conventionally used transformed mouse fibroblasts (L-929) with primary human gingival fibroblasts to further elucidate the term toxicity. While proliferation was assessed via the incorporation of the base analogon bromdesoxyuridine, differentiation was investigated by detection of the fibroblast-specific intermediate filament vimentin. After the monomers had taken effect, reduced proliferation extending over the inhibition area was observed by indirect immunofluorescence, independent of cell type. In contrast to this observation, a few cells within the inhibition area which could not be clearly detected by neutral red staining still exhibited mitotic activity. Detection of the differentiation-specific intermediate filament vimentin was comparable with the degree of neutral red fading visible in the classic agar overlay assay. The study showed that the inhibition areas with primary gingival fibroblasts were smaller (approximately 1/3) after monomer action compared with conventionally applied transformed fibroblasts. The results indicate that the modified assay is comparable with the classic method. Evaluation of neutral red staining with respect to toxic material influence can moreover be supplemented by histochemical studies of typical cell properties.

Acrylic Resins↗
PubMed1987

Synthesis and properties of vinyl monomer/enzyme conjugates. Conjugation of L-asparaginase with N-succinimidyl acrylate.

Monomer conjugation of an enzyme followed by copolymerization with free monomer is a useful method of enzyme immobilization. L-asparaginase was conjugated with N-succinimidyl acrylate. Analysis of the conjugated enzyme via isoelectric focusing showed that a molar ratio of 9.5 free monomers per enzyme was needed during the conjunction for each vinyl group bound. Only 3% of the enzyme activity was lost per vinyl group added, and conjugation of an average of four monomers per enzyme thermally destabilized the enzyme only at temperatures above 50 degrees C. Activity of the enzyme at physiological temperatures was relatively unaffected.

Acrylates↗