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PubMed1986

The use of lead methacrylate 2-ethylhexanoate to create a radio-opaque resin suitable for microvascular corrosion casting.

A radio-opaque methacrylate-based resin suitable for microvascular corrosion casting can be prepared by substituting lead methacrylate 2-ethylhexanoate for a proportion of the methyl methacrylate monomer normally used. Best results are achieved when conventional methacrylate resin is injected first to fill the vascular tree, and this is chased with the radio-opaque resin. The pattern of arterial and arteriolar distribution can then subsequently be followed by means of a radiographic survey of the cast, and this is of value prior to sampling from vascular systems which show functional subdivisions that cannot be correlated with any surface features. The radio-opacity of the resin and the quantity injected can be varied easily to suit individual requirements.

Acrylates↗

PubMed1981

The mechanism of interaction between chlorhexidine digluconate and poly(2-hydroxyethyl methacrylate).

The extent of the interaction between chlorhexidine digluconate and poly(2-hydroxyethyl methacrylate), (PHEMA), is independent of temperature between 22-50 degrees C which is consistent with an ion-ion interaction mechanism. Different contact lens materials exhibit different affinities for chlorhexidine digluconate, the extent of uptake correlating in rank order with the number of free carboxylic acid sites in the polymers. Esterification of the carboxyl groups with diazomethane, resulted in a reduction in the affinity of the treated polymers for chlorhexidine to a near basal level. The uptake of chlorhexidine in soaking solution experiments involving lenses made from PHEMA and the more ionic material, poly(2-hydroxyethyl methacrylate-co-isobutyl methacrylate-co-methacrylic acid), was consistent with their carboxylate content. However, the fraction of bound disinfectant released was lower from the terpolymer, suggesting there are differences in bonding strengths between chlorhexidine and different contact lens hydrogels.

Adsorption↗

PubMed1999

Alterations in cell lipid metabolism by glycol methacrylate (HEMA).

Components of dental resins such as dimethylaminoethyl methacrylate (DMAEMA) can alter cell lipid composition, presumably by esterase-mediated hydrolysis. The resulting dimethylethanolamine is incorporated into cell phospholipids, while the methacrylic acid may alter several metabolic pathways. We hypothesize that HEMA is cleaved in a similar manner and the released ethylene glycol is incorporated into cell lipids, yielding phosphatidylethylene glycol (PtEG), and the methacrylic acid alters other lipid pathways in a manner similar to that of methacrylic acid released from hydrolysis of DMAEMA. Cultures of hamster buccal pouch (HCP) and rabbit kidney (RK13) epithelial cells were exposed to subtoxic concentrations of HEMA in the presence of [14C]-acetate or [3H]-oleic acid. Other cultures were prelabeled with [14C]-acetate followed by exposure to various concentrations of HEMA. Cell lipids were extracted by the method of Bligh and Dyer and separated by thin layer chromatography on silica gel K-6 plates or SG-81 silica gel loaded chromatography paper. The fate of the ethylene glycol was traced using [14C]-ethylene glycol. Radioactive lipids were located using autoradiography and known standard lipids and quantitated by liquid scintillation spectrometry. In the presence of HEMA several classes of lipids were altered. Among the neutral lipids, the most notable changes involved sterol precursors, triglycerides, fatty acids, and cholesterol esters, while phosphatidylcholine was affected among the phospholipids. The results differed quantitatively between the two cell types. Results also suggest that EG, including that released by hydrolysis of HEMA, is incorporated into cell phospholipids, producing PtEG. The changes in neutral lipid labeling may occur by alteration of lipid synthetic pathways utilizing acetyl Co-A as well as inhibition of enzymes involved in synthesis of cholesterol from sterol precursors and hydrolysis of cholesterol esters. Synthesis of PtEG may take place via phospholipase D-mediated headgroup exchange. Alterations in the cellular lipids may affect cell membrane properties and associated cell functions.

Animals↗

PubMed1984

A monomeric methyl and hydroxypropyl methacrylate injection medium and its utility in casting blood capillaries and liver bile canaliculi for scanning electron microscopy.

A mixture of 50-60% monomeric methyl methacrylate and 40-50% monomeric 2-hydroxypropyl methacrylate was supplemented with 1.5% benzoyl peroxide (catalyst) and 1.5% N,N-dimethylaniline (accelerator) and injected into glutaraldehyde-perfusion fixed rat hypophyseal and other endocrine organ blood vessels and biliary tracts. This injection medium rapidly polymerized at room temperature and did not require partial polymerization prior to injection. Good casts of blood vessels, including the hypophyseal capillaries, were obtained for scanning electron microscopy. The monomeric methacrylate medium possesses a great advantage over previous ones, as its fluidity enables the casting of very fine vessels such as bile canaliculi. In the case of non-fixed tissues, the monomeric methacrylate medium should be injected carefully, as it is toxic and destructive to the vessels.

Acrylates↗

PubMed1989

Use of semithin sections embedded in a water-miscible methacrylate for light microscopy of central nerve tissues.

Semithin sections embedded in water-miscible methacrylates were used for the study of fine structures of cells and tissues in the central nervous system by light microscopy instead of the conventional paraffin sections. This method used a water-miscible methacrylate mixture consisting of 2-hydroxypropyl methacrylate (HPMA), Quetol 523 and methyl methacrylate (MMA) as an embedding medium. The mixture had a low viscosity, was easy to handle and penetrated readily and completely into the specimen, producing a homogenous block from which it was easy to make sections 1.5 microns thick. Staining could be localized far more precisely in these sections than in paraffin sections owing to the thickness of the semithin sections and to the excellent structural preservation of cellular components.

Acrylates↗

PubMed1978

Remaining methacrylate groups in composite restorative materials.

The quantity of the remaining unreacted methacrylate groups in polymerized composite materials has been determined. Six proprietary composites were investigated by infrared multiple internal reflection spectroscopy. Infrared reflectance measurements were made before polymerization and repeated after the composites were subjected to polymerization at 37 degrees C for 24 hours. The quantities of remaining unreacted methacrylate groups were determined and the data expressed as percentages of the total amount of methacrylate groups in the unpolymerized materials. The specimens were specially prepared to ensure that the surface properties simulated the bulk properties of the polymerized composites. The quantities of remaining methacrylate groups in the six composites determined by this surface measuring technique ranged from 25 to 48%. The results demonstrate that commercially available composite materials exhibit different degrees of conversion 24 hours after the start of polymerization. These differences can be correlated to the different monomer compositions of the composite restorative resins.

Acrylates↗

PubMedDate not supplied

Microencapsulation of drugs by the coacervation technique using ethylcellulose and acrylate-methacrylate copolymer as wall materials.

In this study, ethylcellulose and acrylate-methacrylate copolymer (Eudragit RL 100, Eudragit RS 100) membranes were prepared by using appropriate types and amounts of plasticizers. Thirty percent and 20% of triacetin based on polymer weight were found to be appropriate plasticizers for ethylcellulose membranes and acrylate-methacrylate copolymer membranes, respectively. The ratios of 3:2 and 2:3 Eudragit RL 100: Eudragit RS 100 also gave transparent and flexible membranes. Cephalexin was chosen as a model drug. The coacervation technique was investigated for the preparation of cephalexin microcapsules. Ethylcellulose and acrylate-methacrylate copolymer corresponding to the above ratios were selected as wall materials of the microcapsules. The effects of core-to-wall ratios on the surface characteristics and dissolution of the microcapsules were also studied. The coacervation technique with ethylcellulose as wall material gave the higher yield (90%) of microcapsules. The release of cephalexin from ethylcellulose walled microcapsules was slow whilst the release from those of acrylate-methacrylate copolymer was faster. The increase of deposition of wall materials due to the decrease of the core-to-wall ratio resulted in a decrease of dissolution rate.

Cellulose↗

PubMed1978

N-Butyl methacrylate and paraffin as an embedding medium for light microscopy.

A method of tissue embedding using n-butyl methacrylate and paraffin is described. Following alcohol dehydration and infiltration with the methacrylate monomer, tissues are embedded in gelatin capsules in a mixture consisting of 3.5 g of paraffin for each 10 ml of methacrylate. Benzoyl peroxide (0.2 g for each 10 ml of monomer) is added as the catalyst and the methacrylate polymerized in a 50 C oven for 18--24 h. Following polymerization the block is trimmed and embedded in paraffin to provide a firm support during sectioning. A water trough attached to the microtome knife is essential to facilitate the handling of sections and ribbons. For serial sections a mixture of equal weights of beeswax and paraffin is used to make the sections adhere to each other. Usual staining procedures can be used since the embedding medium is readily soluble in xylene.

Acrylates↗

PubMed1993

Combined lectin binding and PAS/alcian blue staining in glycol methacrylate sections.

Evaluation of cryofixation and paraffin and glycol methacrylate embedding showed that lectin binding was essentially independent of the embedding medium. Fluorescence intensity increased in the following order: glycol methacrylate, paraffin and cryostat sections. The optical resolution increased in the reverse order. Semi-thin glycol methacrylate sections provided satisfactory fluorescence intensities and the best resolution of all embedding techniques applied. Furthermore the lectin treated sections can be stained further using routine histological or specific histochemical methods. The potassium hydroxide/alcian blue/periodic acid-phenylhydrazine-Schiff method was used successfully to demonstrate sulfated and nonsulfated sialomucins. Lectins combined with mucin histochemistry allowed visualization of specific sugar residues in the same glycol methacrylate plastic section.

Alcian Blue↗

PubMed2000

The effect of continuous poly (methyl methacrylate) fibres on some properties of acrylic resin denture base material.

This study investigated the effect of continuous poly (methyl methacrylate) fibres on the transverse strength and impact strength of poly (methyl methacrylate) denture base resin. The fibres were added in three arrangements, a single unidirectional (longitudinal in the length of the specimen) layer, two longitudinal layers and in cross ply form (a combination of an inferior longitudinal layer and a superior transverse layer). The results indicated that the transverse bend and impact strengths of poly (methyl methacrylate) denture base resin, were not significantly improved by the addition of poly (methyl methacrylate) fibres.

Acrylic Resins↗

PubMed2006

[Copolymer of 2-hydroxyethyl methacrylate for cerebral arteriovenous malformation: an experimental study].

OBJECTIVE: To investigate the feasibility of using methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) to embolize cerebral arteriovenous malformations (AVM). METHODS: Methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) in the ratio of 9:1 were solved in 16% alcohol so as to make a kind of copolymer (CoHEMA). 12 g glass beads 2 mm in diameter were put into a container so as to construct an in vitro model of AVM. The container was connected with a normal saline bottle via microcatheter. CoHEMA, as embolized, was injected through the microcatheter and the diffusion of CoHEMA was observed till the water flow was stopped. CoHEMA was injected through microcatheter into the pharyngeal ascending arteries near the rete mirabile (RMB) tissue, similar to the human AVM, under digital subtraction angiography until satisfactory embolization was obtained, totally 9 RMB tissues in 7 pigs. Five pigs were injected with normal saline as controls. The pigs were killed 2 days, 2 weeks, and 6 months after embolization respectively and the bilateral RMB tissues were taken out to undergo pathological examination. RESULTS: Nine AVM models in vitro were constructed with the copolymer dispersed symmetrically among the glass beads and stopped the fluid across the model effectively. No copolymer adhered to the wall of microcatheter. Nine RMB tissues of 6 pigs were embolized by using CoHEMA. Six of the seven pigs survived the procedure except one died of too fast injection of copolymer in the primary stage. Follow-up angiography was performed in four pigs and found that no recanalization occurred and the copolymer was diffused in the vessels 80-150 microm in diameter. In the specimens obtained 2 days after embolization, neutrophilic granulocytes scattered surrounding the copolymer, suggesting minor inflammatory reaction. In the specimens obtained 2 weeks after embolization no vessel wall damage and morphological change were found except minor inflammatory reaction inside the vessels and surrounding tissues. In the specimens obtained 2 to 6 months after embolization hyperplasia of connective tissue, minor or mediate chronic inflammatory reaction, and giant cell reaction inside the vessels and surrounding tissues. CONCLUSION: With low viscosity, better biocompatibility, and embolic instability, and easy to be injected through delivery microcatheter, CoHEMA is an excellent non-adhesive embolic material and can be used in embolic treatment of cerebral AVM.

Animals↗

PubMed1989

[Application of succinoxy methacrylates for direct bonding system].

Three types of succinoxy methacrylates [2-succinoxyethyl methacrylate (2SEM), 2-succinoxypropyl methacrylate (2PrM) and 2-succinoxy-3-phenoxypropyl methacrylate (SPPM)] were synthesized in order to develop a new direct-bonding adhesive which has sufficient bond strength to mild etched enamel and stainless steel brackets for occlusal and orthodontic force. Experimental direct-bonding adhesives consisted of a MMA solution containing synthesized monomers (5-10 mol%), PMMA powder and an oxidized tri-n-butyl borane as an initiator. A MMA solution without synthesized monomers was used as the control. Preparation of 10% and 40% phosphoric acid solutions and 1M maleic acid solution was carried out for use as etchants. The bond strength to unetched and etched enamel, polished stainless steel, simulated brackets and brackets was measured. The enamel surfaces etched with each etchant and the fractured resin and enamel surfaces after the bond test were observed with SEM and the ease of debonding of adhesive was investigated to totally evaluate the experimental direct-bonding adhesives. The results were as follows: 1) The amount of decalcification for 10% phosphoric acid and 1M meleic acid solutions was less than that for 40% phosphoric acid solution. The SEM micrograph showed most clearly the appearance of enamel prisms on the enamel surface treated with 40% phosphoric acid solution. 2) The experimental direct-bonding adhesives had higher bond strength to the polished enamel, the polished stainless steel and the simulated bracket than the control. 3) The bond strength to the etched enamel was comparable to that of the control. 4) The treatment of 1M maleic acid solution provided the same bond strength to enamel as that of 40% phosphoric acid solution and the higher bond strength than of 10% phosphoric acid solution. The bond strength to enamel treated with 1M maleic acid solution and 40% phosphoric acid solution decreased very slightly by immersion in water and thermal cycling. 5) The MMA solutions containing each 20 mol% synthesized monomer were adequate to direct-bonding adhesive monomers on the basis of the results of bond strength and manipulation. 6) The strongest bond strength between bracket and etched enamel was obtained with the direct-bonding adhesive containing 2SEM under all conditions. 7) The SEM micrographs showed that the tooth-resin interface failure for each adhesive occurred during bond testing. 8) There was little remaining of the resin on the tooth surface after debonding regardless of types of direct bonding adhesives.

Dental Bonding↗

PubMed1979

Methylmethacrylate metabolism in man. The hydrolysis of methylmethacrylate to methacrylic acid during total hip replacement.

Methylmethacrylate, the monomeric component of the polymethylmethacrylate cement used in orthopedic surgery, has been shown to undergo hydrolysis to methacrylic acid during hip replacement operations. Circulating levels of methacrylic acid were comparable with those of methylmethacrylate. Concentrations of both methylmethacrylate and methacrylic acid normally lay in the range 0--15 micrograms/cc. No correlation could be discerned between changes in the concentrations of methylmethacrylate and methacrylic acid, and changes in blood pressure.

Acetabulum↗

PubMed1980

[Simplified method of methacrylate embedding for undecalcified bone sections (author's transl)].

A simplified technique of methacrylate embedded bone biopsies for the diagnosis of bone and haemoblastic disorders is described. Hard tissues are fixated for routine purposes in the Schaffner mixture. Fixations are carried out for fluorescent marked bone using Carnoy mixture and for histochemical methods using 4% purified formaldehyde buffered in 0.1 M solidum cacodylate at pH 7.2. Then, the bone cylinders are dehydrated, defetted and stored at 4 degrees C in methacrylate solution (1 vol. of methyl-methacrylate, 3 vol. of butylmethacrylate, 2.5% benzodylderoxide for 24 hours in vacuum). After the immersion the bones are transferred to plastic capsules filled with the methacrylate mixture described above. The polymerisation takes place in a water bath at 25--26 degrees C. Sections of 4--6 micron thickness can be cut on a special microtome, and after removal of the plastic material by means of toluene they are stained. Results of the method are demonstrated by micrographs.

Acrylates↗

PubMed1996

Lichen planus-like contact dermatitis due to methacrylic acid esters.

We report a patient who had lichen planus-like lesions on sites repeatedly exposed to methacrylic acid esters used in the car industry. Histologically, the lesions showed all the features of classical lichen planus. Patch testing revealed positive reactions to methacrylic acid esters in concentrations as low as 5 x 10(-3)%. As dental devices contain methacrylic acid esters, it is possible to speculate that methacrylic acid esters may be one of the causative agents for oral lichen planus.

Dermatitis, Occupational↗

PubMed1977

On the fate of methyl methacrylate in blood.

The fate of methyl methacrylate in fresh human blood was investigated in vitro by using gas chromatography. It was found that methyl methacrylate is present in cells in concentrations twice as large as in plasma, but it disappears exponentially with time at a rate that is at least 10 times faster than that in cells. The rate constant in cells is very small or even zero. The half-life of methyl methacrylate in whole blood is 3 hr at 20 degrees C. Gas chromatography is a convenient method for the rapid determination of methyl methacrylate levels in blood.

Blood Cells↗

PubMed1977

GI motor inhibition associated with acute exposure to methyl methacrylate vapor.

A mixture of monomeric methyl methacrylate vapor in air was delivered into the breathing air of chloralose-urethan anesthetized dogs. Fixed length exposures to 2000-ppm doses of the vapor resulted in a transient drop in arterial blood pressure and a marked inhibition of ongoing GI motor activities. Motor inhibition always continued for a variable time (approximately 10-15 min) subsequent to the cessation of methyl methacrylate vapor administration. This inhibitory response was not blocked by bilateral vagotomy, spinal transection, splanchnectomy, or the intravenous administration of tetraethylammonium chloride. Another series of experiments determined that the administration of blood from a dog receiving methyl methacrylate vapor produced GI motor inhibition in another dog not connected to the experimental gas mixture. Therefore, it is concluded that, aside from any reflex effects produced, methyl methacrylate vapor in sufficient concentration probably exerts a direct inhibitory effect upon GI smooth muscle that is mediated by the cardiopulmonary systems.

Aerosols↗

PubMed1995

Transcranial Doppler penetrance of methyl methacrylate: technical note.

Methyl methacrylate is often used in cranioplasties and reconstructions of crainiectomies at sites through which transcranial Doppler (TCD) examinations are performed for assessment of cerebral hemodynamics. To assess the penetrance of methyl methacrylate by a transcranial Doppler ultrasound beam, methyl methacrylate discs of thickness from 4 to 10 mm were constructed and placed in the path of the ultrasound beam during routine-insonation of the middle cerebral artery and femoral artery in a healthy volunteer. The quality of ultrasound signals obtainable markedly deteriorated as thicker discs were used, and was almost completely absent at a thickness of 10 mm. The impairment of ultrasound transmission at frequencies used for transcranial Doppler ultrasound by methyl methacrylate is significant and represents a limitation in TCD studies that should be recognized by the clinician.

Blood Flow Velocity↗