Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polymethacrylic Acids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMedDate not supplied

Pharmacokinetic and biodistribution studies of a bone-targeting drug delivery system based on N-(2-hydroxypropyl)methacrylamide copolymers.

Osteotropicity of novel bone-targeted HPMA copolymer conjugates has been demonstrated previously with bone histomorphometric analysis. The pharmacokinetics and biodistribution of this delivery system were investigated in the current study with healthy young BALB/c mice. The 125I-labeled bone-targeted and control (nontargeted) HPMA copolymers were administered intravenously to mice, and their distribution to different organs and tissues was followed using gamma counter and single photon emission computed tomography (SPECT). Both the invasive and noninvasive data further confirmed that the incorporation of D-aspartic acid octapeptide (D-Asp8) as bone-targeting moiety could favorably deposit the HPMA copolymers to the entire skeleton, especially to the high bone turnover sites. To evaluate the influence of molecular weight, three fractions (Mw of 24, 46, and 96 kDa) of HPMA copolymer-D-Asp8 conjugate were prepared and evaluated. Higher molecular weight of the conjugate enhanced the deposition to bone due to the prolonged half-life in circulation, but it weakened the bone selectivity. A higher content of bone-targeting moiety (D-Asp8) in the conjugate is desirable to achieve superior hard tissue selectivity. Further validation of the bone-targeting efficacy of the conjugates in animal models of osteoporosis and other skeletal diseases is needed in the future.

Animals↗
PubMed1990

Release of macromolecules and daunomycin from hydrophilic gels containing enzymatically degradable bonds.

The synthesis of hydrophilic gels based on N-(2-hydroxypropyl)methacrylamide copolymers crosslinked via degradable oligopeptide sequences is described. The influence of the conditions of preparation and of the gel structure on the equilibrium degree of swelling (network density) was determined. To evaluate the potential of such gels for controlled delivery of macromolecules and drugs, the release of FITC-dextrans of different molecular weights was studied and the rate of release was found to depend mainly on the equilibrium degree of swelling and not on the structure of the crosslinks. However, the degradation of the gels by a mixture of lysosomal enzymes isolated from rat liver (Tritosomes) or chymotrypsin was dependent on both the equilibrium degree of swelling and the structure of the crosslinks (length of the oligopeptide sequence and structure of the amino acid residues). The release of the anticancer drug daunomycin imbibed in gels was pH-dependent, the rate of release being higher at lower pH. In addition, a gel was synthesized which contained a pentapeptide in the crosslinks and daunomycin bound via a tetrapeptide side-chain, and in this case, incubation with Tritosomes led to degradation with simultaneous release of the drug.

Amino Acid Sequence↗
PubMedDate not supplied

Microencapsulation of beta-galactosidase with Eudragit L-100.

Microcapsules containing beta-galactosidase (lactase) were prepared by solvent evaporation using the pH sensitive polymer, Eudragit L-100. Formulations were prepared using various polymer-enzyme ratios with total solids content of the internal phase using sucrose stearate as a droplet stabilizer. Particle size distributions were invariant to relative proportion of ingredients but were dependent on stirring conditions. Although sucrose stearate had no effect on particle size distribution, release rate or encapsulation efficiency, its presence at a minimum 2% level was necessary to ensure intact microcapsules. Encapsulation efficiencies were higher for formulations prepared with 15% compared to 10% total solid content. DSC results revealed an interaction between encapsulated Eudragit L-100-enzyme-sucrose stearate vs their physical mixtures. The enzyme activities of the freshly prepared product vs those stored under stressed condition (40 degrees C and 75% RH) were 68 and 40% of their pre-processing activity, respectively. In vitro dissolution showed no enzyme release at 1 h in acidic media but 80% of the lactase was released from the microcapsules over 2.5 h in pH 6.8 media, thus establishing the feasibility of lactase microencapsulation to retard enzyme release in an acidic environment and ensuring release at intestinal pH.

Calorimetry↗
PubMedDate not supplied

Scanning electron microscope evaluation of CEREC II and CEREC III inlays.

In response to an increased public demand for esthetic restorations, dentists are using computer-aided design/computer-aided manufacture (CAD/CAM) technology to fabricate inlay/onlay, crown, and laminate veneers. This study evaluated the fit at the gingival margin of surface inlay restorations milled by the CEREC II as well as the more recently developed CEREC III. The marginal fit of inlays milled by the CEREC III was more accurate than the fit of those milled by the CEREC II, although both were within the ADA specifications of 50 micro.

Acetone↗
PubMed1992

Effect of cervical coating of ethyl cellulose polymer and metacrylic acid copolymer on the radicular penetration of hydrogen peroxide during bleaching.

Extraradicular leakage of oxidizing agents during bleaching is an undesirable event and thus need to be prevented. The effect of external cervical coating of ethyl cellulose (EC) and metacrylic acid copolymer (MAC) on the radicular penetration of hydrogen peroxide during intracoronal bleaching was examined. Single rooted human premolars extracted for orthodontic reasons were used. The cementum covering the cemento-enamel junction was mechanically removed and the teeth treated endodontically and bleached with 30% hydrogen peroxide. Radicular hydrogen peroxide penetration was measured before coating the teeth and after applications of 1-3 layers of EC or 3 layers of MAC external cervical coatings. It was found that the radicular penetration of 30% hydrogen peroxide was related to the number of layers of cervical EC coatings. Application of one layer of EC did not reduce the hydrogen peroxide penetration. Two and three layers of EC reduced the hydrogen peroxide penetration by 38% and 85% respectively. Three layers of MAC reduced the radicular hydrogen peroxide penetration in 83%. Statistically, a highly significant difference was found between the teeth coated with three layers of either EC or MAC and the noncoated teeth (p < 0.001). It was concluded that application of ethyl cellulose or metacrylic acid copolymer to exposed cervical root surfaces may effectively prevent extraradicular leakage of bleaching agents.

Cellulose↗
PubMed2004

Influence of Er:YAG laser on tensile bond strength of a self-etching system and a flowable resin in different dentin depths.

OBJECTIVE: The aim of this study was to evaluate the tensile resistance of a flowable resin in different dentin depths, after superficial treatment with Er:YAG laser. METHODS: Eighteen molars were selected and roots were removed. Crowns were bisected in half, embedded in polyester resin and ground until dentin was exposed. The bonding site was delimited and samples were randomly assigned into two groups: superficial dentin (SD--1 mm from amelodentinal junction) and deep dentin (DD--2 mm from amelodentinal junction). The samples were subdivided in three groups according to superficial treatment: non-rinsing conditioner (NRC) solely; Er:YAG laser (80 mJ/2 Hz)+NRC; Er:YAG laser solely. After conditioning, Prime and Bond NT/Dyract flow (Dentsply) was used for the manufacture of specimens. They were adapted to a metallic device, where resin cones were prepared. Samples were stored for 24 h and subjected to a bond strength test (50 kgf at 0.5 mm/min). RESULTS: Means in MPa were: SD-NRC solely 12.29 (+/-4.40); laser+NRC 12.11(+/-3.23); laser solely 5.74(+/-3.01) and DD-NRC solely 9.60 (+/-3.13); laser+NRC 10.44(+/-2.23); laser solely 3.50(+/-1.70). Data were submitted to statistical analysis by ANOVA and Scheffé test (p < 0.05). CONCLUSIONS: SD produced better results and tensile bond strength, while on DD the treatment with NRC or Laser+NRC had higher tensile bond strength. The results suggest that when Er:YAG laser for dentin treatment is used, it is mandatory to associate it to a conditioning agent.

Acid Etching, Dental↗
PubMed2001

Aggressiveness of contemporary self-etching systems. I: Depth of penetration beyond dentin smear layers.

OBJECTIVE: This study examined, with the use of transmission electron microscopy (TEM), the aggressiveness of three self-etching adhesive systems in penetrating dentin smear layers of different thickness. METHODS: Dentin disks were produced from extracted human third molars. For the control group, the middle dentin surface was cryofractured to create a bonding surface that was devoid of a smear layer. The experimental teeth were polished with wet 600 or 60-grit SiC paper to produce bonding surfaces with thin and thick smear layers. They were bonded using one of the three self-etching systems: Clearfil Mega Bond (Kuraray), Non-Rinse Conditioner and Prime&Bond NT (Dentsply DeTrey) and Prompt L-Pop (ESPE). Bonded specimens were then demineralized and embedded in epoxy resin for TEM examination. RESULTS: For Mega Bond, thin authentic hybrid layers between 0.4-0.5 microm were found. Smear layer and smear plugs were retained as part of the hybridized complex. For Non-Rinse Conditioner/Prime&Bond NT, the authentic hybrid layers were between 1.2-2.2 microm thick. Smear layer and smear plugs were completely dissolved in dentin with thin smear layers, but were partially retained as part of the hybridized complex in those with thick smear layers. For Prompt L-Pop, authentic hybrid layers were 2.5-5 microm thick and smear layer and smear plugs were completely dissolved even in dentin with thick smear layers. SIGNIFICANCE: Contemporary self-etching systems may be classified as mild, moderate and aggressive based on their ability to penetrate dentin smear layers and their depth of demineralization into the subsurface dentin. The more aggressive system completely solubilized the smear layer and smear plugs and formed hybrid layers with a thickness approaching those of phosphoric acid conditioned dentin.

Acid Etching, Dental↗
PubMed1998

Targeting of human and mouse T-lymphocytes by monoclonal antibody-HPMA copolymer-doxorubicin conjugates directed against different T-cell surface antigens.

Binding of HPMA copolymer-conjugated doxorubicin targeted with monoclonal antibodies directed against various T-cell surface receptors, i.e. Thy1.2 (CDw90), I-A (MHC class II. glycoprotein), L3T4 (CD4), IL-2R (CD25) and CD3, is considerably increased in Con A stimulated T-lymphocytes. FACS analysis showed that the binding is most intensive with anti-Thy1.2 and anti-L3T4 targeted derivatives and it is proportional to the antiproliferative effect of the antibody-targeted drug. No binding and no antiproliferative capacity was observed after in vitro incubation of mouse T-cells with a nonspecific mouse IgG-HPMA-DOX conjugate. [3H]-TdR incorporation was inhibited considerably more in Con A stimulated T-cell culture and in EL4 mouse T-cell lymphoma as compared with the culture of nonactivated T-lymphocytes. This proves that intensively proliferating cells are more susceptible to the inhibitory action of an antibody-targeted drug. The cytotoxic efficacy of HPMA copolymer with GlyPheLeuGly or GlyLeuPheGly side-chains to which the drug is conjugated was superior to HPMA copolymer with GlyPheGly or GlyLeuGly side-chains. However, there is no direct correlation between the rate of in vitro drug release and the in vitro cytotoxicity of the respective conjugates. This suggests that the rate of drug release from the conjugate is only one factor responsible for the pharmacological efficacy of the preparation. Furthermore, we detected substantial and prolonged inhibition of proliferation of Con A activated T-cells only if doxorubicin was injected in vivo in the form of an anti-Thy1.2-targeted conjugate.

Amino Acid Sequence↗
PubMed2001

Microtensile bond strengths of one-bottle dentin adhesives.

PURPOSE: To investigate the in vitro performance of three one-bottle adhesives by measuring their dentin microtensile strength. MATERIALS AND METHODS: Extracted human molars had the dentin exposed on the occlusal surface. The teeth were randomly assigned to three dentin adhesives: Group 1 - Prime & Bond 2.1; Group 2 - Prime & Bond NT; and Group 3 - Experimental (unfilled NT). All materials were applied as recommended by the manufacturer. A high-density resin composite (Surefil) was packed on the bonding area in five increments. Specimens (sticks) were obtained using a diamond disc and were stored in distilled water for 24 hrs. The microtensile bond strengths were measured with a universal testing machine. RESULTS: Group 1: 54.3+/-15.6 MPa; Group 2: 62.0+/-17.6 MPa; Group 3: 54.6+/-16.8 MPa. Although no statistically significant difference was found between pairs of means, Prime&Bond NT showed a tendency for higher bond strengths.

Acetone↗
PubMed2002

Microtensile bond strength of thermally stressed composite-dentin bonds mediated by one-bottle adhesives.

PURPOSE: To evaluate the effects of thermally stressing composite-dentin bonds in teeth subjected to a modified microtensile bond test that allowed application of two bonding agents side-by-side to the same tooth. MATERIALS AND METHODS: Extracted human molars with a slot dissecting the occlusal dentin surface were conditioned and primed on one side with Prime & Bond NT (PBNT) and Prime One Mirage (P-One) on the other side. The composite was light-cured onto the surface. Approximately 0.5 mm thick dumbbell-shaped tensile specimens were tested after 24-hour water storage or after thermocycling 2400 times at 5 and 55 degrees C. Interfacial morphologies were evaluated by scanning electron microscopy (SEM). RESULTS: Mean tensile bond strengths (TBS +/- standard deviation) were (36 +/- 24 MPa and 31 +/- 16 MPa) for PBNT, and (51 +/- 25 MPa and 40 +/- 18 MPa) for P-One without and with thermocycling, respectively. 97% of all tested specimens failed adhesively. Differences between the bonding systems and the therrmal treatments were significant (two-way ANOVA, P < 0.05). Regression analysis showed regional correlation between mean TBS of each bonding agent when grouped by the teeth from which they were obtained (r = 0.66, P = 0.002). SEM revealed that both bonding agents effectively wetted the conditioned dentin producing a typical hybrid layer, surface-textured resin tags with multiple lateral branches.

Acid Etching, Dental↗
PubMed2005

Shear bond strength of self-etching bonding systems in combination with various composites used for repairing aged composites.

PURPOSE: Repair of worn, broken or discolored composite restorations can be accomplished using new composite material and dentin bonding systems. The purpose of this study was to investigate the effectiveness of self-etching adhesive systems for composite re-bonding procedures onto different composite substrates that had been aged for 6 years prior to testing. MATERIALS AND METHODS: Two hundred cylinders (4 mm x 5 mm) of composite were fabricated using 4 hybrid composites [AeliteFil (Bisco), Prodigy (SDS Kerr), TPH (Dentsply Caulk), and Z100 (3M ESPE)] following manufacturers' directions and stored for 6 years in 1% NaCl solution. After aging, each specimen was wet polished through 600-grit SiC and randomly assigned to a self-etching bonding system (Adper Prompt L-Pop/Z100 [3M ESPE]; Tyrian One-Step Plus/AeliteFil [Bisco]; OptiBond Solo Plus SE/Prodigy [SDS Kerr], Xeno III/TPH [Dentsply Caulk]) or a total-etch control (Prime&Bond NT/TPH [Dentsply Caulk]) (n = 10 per group). Shear bond strengths (SBS) for repairs were evaluated after 48 h (crosshead speed = 0.5 mm/min) and were compared by two-way ANOVA (p = 0.05) with Tukey post-hoc tests. RESULTS: Significant differences (p < or = 0.05) were detected for the main effects (substrates and bonding systems), but the interaction was not significant. SBS for bonding systems were from highest to lowest: (1) Prime&Bond NT, (2) OptiBond Solo Plus SE, (3) Adper Prompt L-Pop, (4) Xeno III, (5) Tyrian One-Step Plus. SBS of the repair systems to Z100 were significantly lower than those to the other composite substrates. CONCLUSION: Self-etching systems can be used to repair aged composite, but the efficacy of repair of aged composite is system dependent.

Acid Etching, Dental↗
PubMed2006

Bonding of dual-curing resin cements to dentin.

PURPOSE: The purpose of the study was three-fold: 1) to determine the strength of the bond between a number of dual-curing resin cements and dentin treated with corresponding adhesive systems, 2) to determine the effect on bond strength of not light curing the cements, and 3) to investigate whether application of a solution of sodium sulfinate or ascorbic acid would increase the bond strength in the cases where the manufacturer's version of an adhesive system resulted in low bond strength with chemically cured cement, ie, cement cured without light. MATERIALS AND METHODS: The adhesive systems comprised 5 simplified systems (Adper Scotchbond 1 XT, ED Primer II, Excite DSC, OptiBond Solo Plus, and Prime and Bond NT), and as controls, two three-step etch and rinse systems (Adper Scotchbond Multi-Purpose Plus and Gluma Solid Bond). The corresponding dual-curing resin cements were RelyX ARC, Panavia F 2.0, Variolink II, Nexus 2, Calibra, RelyX ARC, and 2Bond2. The cements were either light and chemically cured or only chemically cured. The adhesive systems were used as recommended by the manufacturers, which for some systems involved inclusion of a so-called activator or catalyst when used with chemically cured cement. Sodium sulfinate and ascorbic acid were applied as a 1% ethanol solution. The bond strengths were measured in shear after storing specimens for 24 h in 37 degree C water. RESULTS: When the dual-curing resin cements had been both light and chemically cured, the bond strengths increased in this order: Gluma Solid Bond < ED Primer II < Prime and Bond NT < Adper Scotchbond Multi-Purpose Plus < Excite DSC < Adper Scotchbond 1 XT < OptiBond Solo Plus. Omission of light curing of the cements decreased the bond strengths with OptiBond Solo Plus and Prime and Bond NT. The use of activator in conjunction with OptiBond Solo Plus and Prime and Bond NT increased the bond strength to chemically cured cement, but not to the level obtained when the cement was both light and chemically cured. The use of the catalyst of Adper Scotchbond Multi-Purpose Plus did not increase the bond strength with chemically cured cement. Pretreatment with a solution of sodium sulfinate or ascorbic acid increased the bond strength with chemically cured cement in the case of OptiBond Solo Plus, whereas only the solution of sodium sulfinate was effective with Prime and Bond NT. CONCLUSION: Clinicians should be aware that in situations where a dual-curing resin cement cannot be light cured, some adhesive systems suffer a loss of efficacy, even when respective activators are used. Pretreatment with a 1% ethanol solution of sodium sulfinate may restore much of the lost bond strength.

Ascorbic Acid↗
PubMed1991

Preparation and evaluation of Eudragit gels. I: Eudragit organogels containing drugs as rectal sustained-release preparations.

New organogels containing salicylic acid, sodium salicylate, procaine, and ketoprofen were prepared by using Eudragit L and S, and propylene glycol. The physical properties (e.g., penetration and extensibility) of the organogels were affected considerably by the incorporation of a basic drug, such as procaine, rather than an acidic drug, such as salicylic acid. In in vivo evaluation using rabbits, it was found that 30% Eudragit L organogels containing 1.25% (w/w) salicylic acid or 2.5% (w/w) ketoprofen showed sustained plasma salicylic acid or ketoprofen levels and almost the same AUC as compared with Witepsol H-15 suppositories containing these drugs. Furthermore, the relative bioavailability for salicylic acid and ketoprofen released from 30% Eudragit L organogels, with 10% (w/w) linolic acid or oleic acid as absorption enhancer, increased to 1.55-1.75- and 1.46-1.85-fold, respectively, compared with 30% Eudragit L organogels without these unsaturated fatty acids.

Acrylic Resins↗