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At least 1,027 records · Page 57Linked to original sources
PubMed2003

Effect of choice of surgical gloves on dough time measurements of acrylic bone cement.

In this study we investigated the effect of the brand of surgical gloves on the dough time determination for acrylic bone cements. Four different brands of powder-free latex surgical gloves were tested. Two commercial bone cements, Surgical Simplex P and Palacos R, were used for dough time measurement following standard test methods for acrylic bone cements (ASTM F-451 and ISO 5833). The results show that the measured dough time depended largely on the brand of gloves used, and could vary by nearly 250%. The surface morphological structures of gloves, determined by SEM, probably contribute to the differences in the measured dough time. This study provides experimental evidence that supports the need to describe the type of gloves used, in detail, when dough time is reported. It also illustrates the importance of the glove brand, when bone cement is to be handled as a dough in the clinical setting.

Biocompatible Materials↗
PubMed1999

Release of 5-amino salicylic acid from acrylic type polymeric prodrugs designed for colon-specific drug delivery.

New acrylic type polymeric systems having degradable ester or amide bonds linked to the bioactive agent 5-amino salicylic acid (5-ASA), were prepared and evaluated as materials for colon-specific drug delivery. Methacryloyloxyethyl 5-amino salicylate (MOES), and N-methacryloylaminoethyl 5-amino salicylamide (MAES) were prepared as the polymerizable derivatives of 5-ASA using activated ester methodology. The drug-containing monomers were free radically copolymerized with methacrylic acid or hydroxyethyl methacrylate, utilizing azobisisobutyronitrile as initiator. The polymer bearing 5-ASA units as side substituents of the acrylic backbone were obtained in the form of poly pendent esters or poly pendent amides. The drug release studies were performed by hydrolysis in buffered solutions (pH 1, 7.2, 8.5), or simulated intestinal fluid containing pancreatin to measure the chemical degradation expected to occur in the intestinal tract. The release profiles indicated that the hydrolytic behavior of polymers strongly depends on their degree of swelling, type of comonomer, and the nature of hydrolyzable bond. Implication of the results for use of these polymers for colon targeting are discussed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

[Calcification of hydrophilic acrylic intraocular lenses: clinical and pathological aspects].

PURPOSE: The aim of this study was to evaluate the clinical aspects of ten eyes with calcified hydrophilic acrylic intraocular lenses and pathological data obtained from seven explanted lenses. MATERIAL AND METHODS: Forty-seven eyes of 40 patients received the same implant in the first 6-month period of 2001. Ten eyes showed intraocular lens opacification detected 6-18 months after the operation: seven lenses were explanted and three were left in place because they were not causing a decrease in visual acuity or glare at light. Five of ten eyes were diabetic. The explanted lenses were examined under the light microscope and the electron microscope. The elemental analysis of the lens surfaces was made by energy dispersive spectrometry. RESULTS: The light microscopy showed an irregular surface covered by a gray-white opacity. The electron microscopy detected multiple granulations on the front and back surfaces of the lenses including some portions of the haptics. The size and density of these granulations were smaller on the back surface. The energy dispersive spectrometry showed the presence of calcium and phosphate on both surfaces. The spikes of calcium and phosphate were smaller for the back surface of the lenses. DISCUSSION: Calcification was predominantly seen on the surfaces that were in contact with aqueous not covered with anterior capsule. Half (5/10) of the cases were diabetic even though 18% of all patients receiving this lens were diabetic. The presence of diabetes is very common in other series. These data suggest the role of a metabolic factor influencing the milieu of the lens in this calcification process. CONCLUSION: Calcification of the hydrophilic acrylic lenses is a relatively serious complication, but the conditions leading to its appearance and the physiopathology have not yet been fully elucidated. The surgeon should be very careful in the choice of the intraocular lens to implant, and even more so if the patient is diabetic.

Aged↗
PubMed2005

[Opacification of a hydrophilic acrylic intraocular lens].

PURPOSE: To report pathological and histochemical analysis of an explanted opacified hydrophilic acrylic intraocular lens. PATIENTS: and method: A hydrophilic acrylic intraocular lens--Orion IFP3D6--was explanted 2 years after routine phacoemulsification because of its opacification associated with significant visual impairment (20/40). The intraocular lens was examined by gross and light microscopy. Full-thickness cut sections of the lens were stained with 1% alizarin red (a special stain for calcium). RESULTS: Microscopic analyses revealed the presence of granules of various sizes distributed in a line parallel to the anterior and posterior curvatures of the lens. The granules stained positively for alizarin red. CONCLUSION: Such opacification has been described with the SC60B-OUV, MDR Inc., which is also a one-piece foldable-design intraocular lens (28% hydrophilic material). The opacification of the intraocular lens occurred over various periods after surgery. Forty percent of these lenses have been explanted. Microscopic and histochemical evaluation of these intraocular lenses revealed the same type of granulation deposits within the lenses. The origin and mechanism of the opacification are still not fully understood.

Female↗
PubMed2002

Solid-state plasticization of an acrylic polymer with chlorpheniramine maleate and triethyl citrate.

The influence of in situ plasticization of chlorpheniramine maleate (CPM) on Eudragit RS PO from hot-melt extruded matrix tablets, and from compressed granules prepared by thermal processing was investigated. CPM was studied as both a model drug substance and as a solid-state plasticizer for the acrylic polymer. Triethyl citrate (TEC) was incorporated into the polymer blend as a liquid plasticizer for the polymer. The influence of TEC and CPM concentration on the dissolution properties of CPM tablets was investigated. The glass transition temperature (T(g)) of the samples was determined by modulated differential scanning calorimetry (MDSC). The morphologies of the granules formed by hot-melt extrusion and hot-melt granulation processes were investigated by scanning electron microscopy. The addition of 12% TEC to the polymer reduced the T(g) by 32.5 degrees C, while the reduction in the T(g) for the same level of CPM was 16.4 degrees C. The effect of TEC levels on drug release was dependent on the tablet preparation method. At high TEC levels, the release rate of CPM decreased in tablets prepared by direct compression and tablets made from compressed granules that had been prepared by high shear hot-melt granulation. However, the CPM release rate increased from hot-melt extruded tablets with increasing blends of plasticizer in the extruded tablets. An increase in the CPM content in the tablets resulted in an increase in the drug release rate. During high shear hot-melt granulation, the model drug adhered to the polymer to form a porous discontinuous structure. Following hot-melt extrusion, the drug was distributed at a molecular level in the continuous polymeric structure. The influence of both CPM and TEC levels on the drug release rate from these polymeric drug delivery systems was shown to be a function of whether the granules or tablets were formed by either hot-melt granulation or hot-melt extrusion, as well as the plasticization effects of both TEC and CPM on the acrylic polymer.

Chemistry, Pharmaceutical↗
PubMed2000

In vitro release studies of methylmethacrylate liberation from acrylic cement powder.

Bone cement or polymethylmethacrylate (PMMA) is commonly used for anchoring cemented prosthesis to the bone. Cytotoxic effect of culture media exposed to PMMA powder may be related with long term problems associated with acrylic cement application, being the monomer (methylmethacrylate) one of the cement's component partly responsible for the cytotoxic effect. The present work reports the studies of monomer release from acrylic bone cement powder under different experimental conditions: setting time of PMMA (in solution and air) and different culture media composition. High-performance liquid chromatography was used for the determination of residual monomer. Mathematical models were applied to experimental dissolution data revealing that monomer release is lightly affected by the studied variables. The monomer release seems to be a surface phenomena, suggesting that the possible actions of monomer will mainly be due to the initial loss of non polymerized monomer rather than to further depolymerization of the already polymerized cement.

Bone Cements↗
PubMed2001

Surface abnormalities on hydrophilic acrylic intraocular lenses implanted by an injector.

PURPOSE: To describe and evaluate abnormalities on the surface of hydrophilic acrylic intraocular lenses (IOLs) that were implanted using an injector. SETTING: Department of Ophthalmology, University of Graz, Graz, Austria. METHODS: This study comprised 70 eyes having phacoemulsification and implantation of an EasAcryl (n = 50) or Inject-A (n = 20) IOL. Both hydrophilic IOLs are biconvex and have a high water content (26%), plate-haptic design, and no angulation. The IOLs were folded in a cartridge under hydroxypropyl methylcellulose and implanted by an injector. RESULTS: Thirteen EasAcryl and 5 Inject-A IOLs had multiple white lines in the direction of the longitudinal axis on the posterior surface immediately after implantation. On 1 EasAcryl IOL, the white lines were separated by a clear central zone and were on the anterior surface. Another EasAcryl IOL had a 1.0 mm crack. CONCLUSIONS: The abnormalities on the posterior surface of high-water-content hydrophilic acrylic IOLs disappeared or were almost gone within 1 month postoperatively and do not appear to be a concern for surgeons. These abnormalities are likely the result of the IOLs' hydrophilicity and high water content and friction in the injector barrel.

Humans↗
PubMed2002

Sulcus implantation of a 3-piece, 6.0 mm optic, hydrophobic foldable acrylic intraocular lens in phacoemulsification complicated by posterior capsule rupture.

To evaluate the safety of implanting a 3-piece, 6.0 mm optic, foldable acrylic intraocular lens (IOL) in cases of posterior capsule rupture during phacoemulsification. Department of Ophthalmology, Ahepa Hospital, Aristotle University Medical School, and Interbalkan Medical Center, Thessaloniki, Greece. This prospective noncomparative case series included 28 eyes (28 patients) having phacoemulsification complicated by extensive posterior capsule rupture with or without vitreous loss. In all eyes, a 3-piece, 6.0 mm optic, foldable acrylic IOL (AcrySof MA60BM, Alcon) was implanted in the sulcus. Postoperative examination included best corrected visual acuity (BCVA), anterior segment biomicroscopy, IOL centralization and position, intraocular pressure (IOP), and fundus biomicroscopy. The follow-up was 6 months. The most common postoperative complications were transient corneal edema in 12 eyes and increased IOP in 11 eyes. Slight asymptomatic decentralization from the center of the pupil (1.0 to 2.0 mm) and pseudophacodonesis were observed in 5 eyes each. Friction of the IOL with the iris occurred in 1 eye. Clinically significant cystoid macular edema occurred in 3 eyes. The final BCVA was between 20/15 and 20/25 in 18 patients, 20/30 in 2, between 20/40 and 20/50 in 4, and between 20/60 and 20/200 in 4. AcrySof IOL implantation in the sulcus during phacoemulsification complicated by posterior capsule rupture preserved the advantages of small-incision surgery. The postoperative behavior and centralization of the IOLs resembled those of poly(methyl methacrylate) lenses.

Aged↗
PubMed1989

Modified acrylic cap splint for dento-alveolar fractures.

A modified method of constructing an acrylic cap splint is introduced. The splint is made from wax and is then replaced by acrylic. The splint has a uniform thickness and is therefore suited for maintenance of a proper occlusion.

Alveolar Process↗
PubMed2000

Platelet and bacterial repellence on sulfonated poly(ethylene glycol)-acrylate copolymer surfaces.

Novel poly(ethylene glycol) (PEG) and sulfonated PEG (PEG-SO(3)) acrylate copolymers have been prepared and characterized to apply as coating and blending materials for biomedical applications. The modified surfaces using acrylate copolymers demonstrated increased hydrophilicity, possibly due to the hypothesized reorientation of PEG/PEG-SO(3) chains into water phase. All copolymer surfaces demonstrated less platelet adhesion than control. In addition, platelet adhesion on copolymer surfaces decreased as the chain length of PEG and sulfonated PEG in copolymers increases. All copolymer surfaces reduced bacterial adhesion significantly and the adhesion level differs depending on surfaces as well as media. The obtained results attest to the usefulness of these copolymers as a coating or additive material to improve the blood compatibility of blood contacting devices.

Journal Article↗
PubMed2002

Magnetic resonance imaging outcome after uterine artery embolization for leiomyomata with use of tris-acryl gelatin microspheres.

PURPOSE: To determine the imaging outcome after uterine artery embolization (UAE) with use of tris-acryl gelatin microspheres (Embospheres). MATERIALS AND METHODS: A retrospective analysis of magnetic resonance (MR) images was performed comparing studies completed 3-4 months after UAE to those performed before UAE. Twenty-three patients with 61 leiomyomata (as many as three fibroids per patient) were examined. Orthogonal T2, axial T1-weighted fat-saturated, sagittal T2 fast spin-echo, and dynamic T1-weighted sagittal images after Gadolinium injection were analyzed. Two abdominal imaging specialists examined the volume and uterine and leiomyoma perfusion. The Wilcoxon signed-rank test was used for inferences in leiomyoma size difference, infarction, and volume of fibroid tissue perfused. RESULTS: Median volume of all leiomyomata (n = 61) decreased by 52% (P <.001). For dominant fibroids alone (n = 23), a median 52% volume decrease (P <.001) was also noted, whereas the median uterine volume decreased 32%. Median perfused volume of all fibroids decreased from 31 mL to 0 mL, signifying a 100% decrease (P <.001). For dominant fibroids, a 100% median perfused volume decrease from 116 mL to 0 mL was noted (P <.001). Fifty-two of 61 fibroids (85%) and 20 of 23 dominant fibroids (87%) were completely devascularized and two fibroids disappeared. There was no myometrial ischemia identified. CONCLUSIONS: Tris-acryl gelatin microspheres (Embospheres) are an effective embolic agent for UAE, causing infarction and significant decrease in leiomyoma volume.

Adult↗
PubMed1975

Polynucleotide analogs: acrylic acid and maleic acid copolymers of 1-vinyluracil and 9-vinyladenine.

Radical-induced copolymerization of 1-vinyluracil and maleic anhydride gave, after hydrolysis, a polymer containing a 1:1 monomer ratio of 1-vinyluracil-maleic acid. Gamma-Ray-induced copolymerization of 1-vinyluracil with acrylic acid gave a polymer with a ratio of 1:1.7. Similar treatment of 9-vinlyadenine and acrylic acid resulted in a polymer with a 1:3.2 ratio. These three compounds are potent stimulants of poly (uridylic acid) coded polyphenylalanine synthesis in an in vitro cell free system purified from Escherichia coli MRE 600. The double-stranded polymer, poly(inosinic acid)-poly(cytidylic acid), also stimulates polyphenylalanine synthesis in this assay.

Adenine↗
PubMed2003

Acrylate intercalation and in situ polymerization in iron-, cobalt-, or manganese-substituted nickel hydroxides.

A chimie douce route based on successive redox and exchange reactions has allowed us to prepare new hybrid organic-inorganic materials, composed of polyacrylate macromolecules intercalated into layered double hydroxides (LDHs), deriving from Ni(OH)(2). Monomer intercalation and in situ polymerization mechanisms have appeared to be strongly dependent upon the nature of the substituting cation in the slabs. In the case of iron-based LDHs, a phase containing acrylate monomeric intercalates has been isolated and identified by X-ray diffraction and infrared spectroscopy. Second, interslab free-radical polymerization of acrylate anions has been successfully initiated using potassium persulfate. In cobalt- or manganese-based LDHs, one-step polymerization has been observed, leading directly to a material containing polyacrylate intercalate.

Journal Article↗
PubMed2001

Segmental dynamics of interfacial poly(methyl acrylate)-d(3) in composites by deuterium NMR spectroscopy.

The interface in composite materials containing an ultrathin layer of poly(methyl acrylate)-d(3) (PMA-d(3)) on silica was studied using deuterium NMR. PMA-d(3) was deposited from solution at saturation coverage from toluene onto silica. The samples were dried and composite samples made by hot pressing the PMA-d(3)/silica samples with hydrogenated polystyrene (PS) and high (HMW) and low (LMW) molecular weight hydrogenated poly(methyl acrylate) (PMA) as the overlayer. The interfacial layers of PMA-d(3) were studied at the air-polymer-silica and polymer-polymer-silica interfaces using deuterium solid-state quadrupole-echo NMR and the results compared to those for the bulk polymer. It was found that for samples at the air-polymer-silica interface, some of the polymer segments in the surface sample had segmental mobility higher than that of the corresponding bulk PMA-d(3) sample at the same temperature. When overcoated with unlabeled polymer, the interfacial polymer at the polymer-polymer-silica interface showed reduced mobility due to the presence of the overlayer. The adsorbed PMA-d(3), in the composite samples, decreased in mobility in the order of LMW-PMA > HMW-PMA > PS. The PS sample caused the greatest reduction in the PMA-d(3) interfacial mobility. The order was consistent with the segmental mobilities of the polymers used for the overlayers. The lower the mobility of the polymer used for the overlayer, the more restricted were the polymer segments in the adsorbed PMA-d(3) layer.

Journal Article↗
PubMed2004

Anisotropic in-plane gradients of poly(acrylic acid) formed by electropolymerization with spatiotemporal control of the electrochemical potential.

Laterally varying thickness gradients of poly(acrylic acid) (PAA) were formed by Zn(II)-catalyzed electropolymerization of acrylic acid (AA) in the presence of an in-plane electrochemical potential gradient applied to Au working electrodes. In the static potential gradient (SPG) approach, two ends of a Au working electrode were clamped at distinct potentials for the duration of the electropolymerization process, thereby generating a time-independent in-plane electrochemical potential gradient, V(x). A dynamic potential gradient (DPG) approach was also used, in which the two end potentials were varied in time, while maintaining a constant voltage offset, to generate an in-plane electrochemical potential gradient, V(x,t). Because the kinetics of heterogeneous electron transfer vary with the local overpotential, these two methods produce PAA films with laterally varying thickness gradients, although they exhibit different spatial characteristics. X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance (SPR) imaging were used to characterize the PAA gradients. The in-plane thickness variations of PAA gradients formed by both SPG and DPG approaches agree with predictions of the Butler-Volmer equation at small absolute overpotentials, while at large (negative) overpotentials, mass transport dominates, and the thickness reaches a plateau value independent of local potential. DPG-produced PAA gradients are generally broader than SPG gradients with the same initial potential and comparable effective growth time, indicating that the DPG approach is more suitable for formation of thicker gradients.

Journal Article↗
PubMed2003

Ru-catalyzed highly enantioselective hydrogenation of beta-alkyl-substituted beta-(acylamino)acrylates.

Highly enantioselective hydrogenation of beta-alkyl-substituted (E)-beta-(acylamino)-acrylates catalyzed by Ru((R)-Xyl-P-Phos)(C(6)H(6))Cl(2) complex (cat. 1c) was achieved in up to 99.7% ee. Moderate to good enantioselectivities in the hydrogenation of corresponding (Z)-isomers in the presence of [Rh((R)-Xyl-P-Phos)(COD)]BF(4) (cat. 2c) were also obtained. The results demonstrated that the electronic and steric properties of the dipyridylphosphine ligands as well as the different transition metal ions have significant influences on the catalytic properties in the hydrogenation of beta-(acylamino)acrylates.

Journal Article↗
PubMed2004

A computational study of the Diels-Alder reaction of ethyl-S-lactyl acrylate and cyclopentadiene. Origins of stereoselectivity.

The eight diastereoisomeric transition structures of the Diels-Alder addition of ethyl-S-lactyl acrylate and cyclopentadiene have been investigated in the gas phase and in solution by HF, MP2, and density functional theory (B3LYP and B3PW91) methods with the 6-31G(d,p) basis set. At all levels of theory used, the s-cis transition structures are more stable than the s-trans ones. The contribution of the s-trans transition structures increases in solution and, although still small, has to be taken in consideration for correct prediction of stereoselectivity. Diastereofacial selectivity is interpreted in terms of electrostatic (weak hydrogen bonding) C=O...H(C) interactions between the carbonyl group(s) of the dienophile and cyclopentadiene in the energetically favored transition structures. Endo/exo reaction selectivity is attributed to positive orbital interactions between the diene and the acrylate carbonyl oxygen in the endo s-cis transition structures. Ab initio methods reproduce well the experimentally observed trends in both endo/exo and diastereofacial selectivity. Density functional calculations in the gas phase correctly reproduce the observed trends in diastereofacial selectivity but single-point MP2 calculations are necessary to reproduce the experimental trend in endo/exo selectivity.

Journal Article↗
PubMed2000

Base-promoted in situ generation of methyl acrylate from dimethyl 3, 3'-dithiodipropionate. Application To N-alkylation of heterocycles

In basic medium, dimethyl 3,3'-dithiopropionate generates methyl acrylate, which serves in situ as a source of propionate moiety. This property was applied to the alkylation of indoles and other nitrogen heterocycles leading to a series of 3-(heteroaryl-substituted) propionates. A mechanistic rationale for the generation of acrylate is presented along with supportive experimental data.

Journal Article↗