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Biomedical subjects

Dong Xie

Publications and source records attributed to Dong Xie.

At least 19 recordsLinked to original sources

A novel comonomer-free light-cured glass-ionomer cement for reduced cytotoxicity and enhanced mechanical strength.

OBJECTIVE: The objective of this study was to develop a novel comonomer-free light-cured glass-ionomer system based on the 4-arm star-shape poly(acrylic acid). The mechanical strengths and in vitro cytotoxicity of the formed system were evaluated and compared with those of several representative commercial glass-ionomer cements. MATERIALS AND METHODS: The 4-arm poly(acrylic acid) was synthesized using ATRP and tethered with glycidyl methacrylate (GM). The GM-tethered polymer was formulated with water, photo-initiators, and Fuji II LC filler. Fuji II, Fuji II LC and Vitremer were used for comparison. Compressive strength (CS) and MTT assay were used as tools to evaluate the mechanical strengths and in vitro cytotoxicity of the cements, respectively. RESULTS: The experimental cement exhibited significantly high compressive, diametral tensile and flexural strengths as compared to commercial glass-ionomer cements, Fuji II, Fuji II LC and Vitremer. The effects of polymer/water (P/W) ratio, GM-grafting ratio, glass powder/polymer liquid (P/L) ratio and aging in water on strengths were significant. Similar to conventional glass-ionomer cement Fuji II, the eluates from the experimental cement showed little in vitro cytotoxicity to Balb/c mouse fibroblast cells, as compared to Fuji II LC and Vitremer that contain HEMA as a comonomer. CONCLUSIONS: It appears that this novel comonomer-free light-cured glass-ionomer cement will be a promising dental restorative because it demonstrated significantly improved mechanical strengths and almost no in vitro cytotoxicity as compared to current commercial light-cured glass-ionomer cements.

Acrylic Resins↗

Novel injectable and in situ curable glycolide/lactide based biodegradable polymer resins and composites.

Novel in situ polymerizable liquid three-arm biodegradable oligomeric polyesters based upon glycolic acid (GA), L-lactic acid (LLA), and their copolymers are synthesized and characterized. Injectable and in situ curable polymer neat resins and their composites formulated with bioabsorbable beta-tricalcium phosphate are prepared at room temperature using photo- and redox-initiation systems, respectively. The cured neat resins show the initial compressive yield strength (YCS, MPa), modulus (M, MPa), ultimate compressive strength (UCS, MPa), and toughness (T, kN mm), ranging from 4.0 to 20.1, 201.5 to 730.2, 82.7 to 310.5, and 1.02 to 3.93. The cured composites show the initial YCS, M, UCS and T, ranging from 27.7 to 56.4, 1440 to 4870, 81.6 to 158.9, and 0.94 to 1.97. Increasing GA/LLA ratio increases all the initial compressive strengths of both neat resins and composites. Increasing filler content increases YCS and M but decreases UCS and T. A diametral tensile strength test shows the same trend as a compressive strength test. There seems to be an optimal flexural strength for the composite at the filler content around 43%. An increasing molar ratio increases curing time but decreases the degree of conversion (DC). An increasing filler content increases curing time but decreases exotherm and DC. During the course of degradation, all the materials show a burst degradation behavior within 24 h, followed by an increase in CS. The poly(glycolic acid) neat resin completely loses its strength at around Day 45. The composites completely lose their strengths at different time intervals, depending on their molar ratio and filler content. The degradation rate is found to be molar ratio and filler-content dependent.

Absorbable Implants↗

Preclinical pharmacokinetics, pharmacodynamics, and activity of a humanized anti-CD40 antibody (SGN-40) in rodents and non-human primates.

1. Cell-surface expression of CD40 in B-cell malignancies and multiple solid tumors has raised interest in its potential use as a target for antibody-based cancer therapy. SGN-40, a humanized monoclonal anti-CD40 antibody, mediates antibody-dependent cytotoxicity and inhibits B-cell tumor growth in vitro, properties of interest for the treatment of cancers, and is currently in Phase I clinical trials for B-cell malignancies. In this study, we determined in vivo activity and pharmacokinetics properties of SGN-40. 2. Effect of SGN-40 in xenograft model of CD40-expressing B-cell lymphoma in severe-combined immune deficiency mice and its in vivo pharmacokinetics properties in normal mice, rats and cynomolgus monkeys were studied. 3. Treatment with SGN-40 significantly increased the survival of mice xenografted with human B-cell lymphoma cell line. SGN-40 exhibited nearly 100% bioavailability in mice and it cleared faster when given at a low dose. In monkeys, clearance of SGN-40 was also much faster at low dose, suggesting nonlinear pharmacokinetics in these species. In rats, however, SGN-40 clearance at all tested doses was similar, suggesting that pharmacokinetics were linear in this dose range in rats. Administration of SGN-40 to monkeys also produced marked, dose-dependent, and persistent depletion of peripheral CD20(+) B lymphocytes. 4. Data presented in this report suggest that SGN-40 is active in in vivo, and based upon interspecies scaling, SGN-40 clearance in humans is predicted to be similar to observed SGN-40 clearance in monkeys. These data suggest that SGN-40 has appropriate pharmacokinetic properties that support its clinical use.

Animals↗

An integrated system for genetic analysis.

BACKGROUND: Large-scale genetic mapping projects require data management systems that can handle complex phenotypes and detect and correct high-throughput genotyping errors, yet are easy to use. DESCRIPTION: We have developed an Integrated Genotyping System (IGS) to meet this need. IGS securely stores, edits and analyses genotype and phenotype data. It stores information about DNA samples, plates, primers, markers and genotypes generated by a genotyping laboratory. Data are structured so that statistical genetic analysis of both case-control and pedigree data is straightforward. CONCLUSION: IGS can model complex phenotypes and contain genotypes from whole genome association studies. The database makes it possible to integrate genetic analysis with data curation. The IGS web site http://bioinformatics.well.ox.ac.uk/project-igs.shtml contains further information.

Chromosome Mapping↗

Synthesis and preparation of novel 4-arm star-shape poly(carboxylic acid)s for improved light-cured glass-ionomer cements.

OBJECTIVE: The objective of this study was to synthesize and characterize novel 4-arm star-shape poly(acrylic acid)s (poly(AA)s) via atom-transfer radical polymerization (ATRP) technique, tether in situ light-curable methacrylate functionalities onto the poly(AA) backbone, use these star-shape poly(AA)s to formulate the light-cured glass-ionomer cements (LCGICs), and evaluate the mechanical strengths of the formed cements. MATERIALS AND METHODS: The 4-arm poly(AA)s were synthesized using ATRP and tethered with either 2-isocyanatoethyl methacrylate (IEM) or glycidyl methacrylate (GM). The polymers were formulated with 2-hydroxyethyl methacrylte (HEMA) or methacryloyl beta-alanine (MBA), water, initiators, and Fuji II LC filler. Compressive strength (CS) was used as a tool to evaluate the formed cements. The specimens were conditioned in distilled water at 37 degrees C for 24h prior to testing. RESULTS: The 4-arm poly(AA) showed a lower viscosity as compared to its linear counterpart. Both IEM-tethered and GM-tethered 4-arm poly(AA) constructed LCGICs showed significantly high mechanical strengths. Both types of co-monomer and grafting agent dramatically affected the mechanical strengths. The MBA-containing poly(AA) cements exhibited much higher CS than the HEMA-containing cements. The IEM-tethered poly(AA) cements showed much higher CS and DTS than the GM-tethered cements. CONCLUSIONS: This study developed a novel light-curable 4-arm star-shape poly(AA) system. The system was 13% in CS, 178% in DTS and 123% in FS, compared to Fuji II LC.

Acrylic Resins↗

Novel amino acid-constructed polyalkenoates for dental glass-ionomer restoratives.

Several methacrylate or acrylate derivatives of natural amino acids were synthesized and characterized. Based upon these derivatives, novel amino acid-constructed polyalkenoic acids were prepared and used to formulate glass-ionomer cements (GICs) with Fuji II glass filler. The effects of type of derivatives, molar ratio, molecular weight, and powder/liquid ratio were investigated. The results show that amino acid-constructed polyalkenoic acids can be formed only from amino acid methacrylate derivatives or by copolymerization of methacrylate with acrylate derivatives. Strong hydrogen bond interactions failed the polymer formation from acrylate derivatives. The cement composed of poly(methacryloyl glutamic acid-co-acryloyl beta-alanine) with the molar ratio of 8:2 demonstrated the best mechanical strengths along with a workable viscosity. By using the powder/liquid ratio of 3.0/1, the experimental cement exhibited a significantly higher FS (27.7 MPa), and nearly the same CS (198.5 MPa) and DTS (11.8 MPa), as compared to Fuji II (18.9 for FS, 189.1 for CS, and 11.4 MPa for DTS). During aging, the cement showed a significant increase in strength over 24 h, followed by a slow increase over 6 months.

Amino Acids↗

Preparation, formulation and evaluation of novel photo-cured glass ionomers based on co-polymers of (meth)acrylated amino acids.

A novel photo-cured amino-acid-constructed glass-ionomer cement system has been developed. Glutamic acid- and beta-alanine-based methacrylate and acrylate derivatives were synthesized, characterized and used to construct the polyalkenoic acids and formulated with water and Fuji II glass filler to form self-cured cement. Compressive strength (CS) of the cement and viscosity of the liquid were used as tools for evaluation. The effects of molar ratio and molecular weight (MW) were studied. The optimized co-polymer was further modified with glycidyl methacrylate (GM) and formulated with water, acrylic acid and Fuji II LC filler to form photo-cured cement. The effects of MW, GM tethering ratio, polymer liquid ratio and glass filler powder/polymer liquid (P/L) ratio were investigated. CS, flexural strength (FS) and viscosity were used as screening tools to find the optimal formulation. All the specimens were conditioned in distilled water at 37 degrees C for either 24 h or 7 days prior to testing. The results show that amino-acid-constructed polyalkenoic acids can be formed only from amino acid methacrylate derivatives or by co-polymerization of methacrylate with acrylate derivatives. Among the numerous co-polymers synthesized, poly(methacryloyl glutamic acid-co-acryloyl beta-alanine) or poly(MGA-co-ABA) with the molar ratio of 8:2 and MW of 19.5 kg/mol contributed the highest mechanical strengths and lower working viscosity to the cement. For photo-cured system, the effects of GM tethering ratio, polymer content and P/L ratio were significant. It is found that an appropriate ratio balance between these parameters is very important. The effect of molecular weight was not significant. The self-cured experimental cement was 32% higher in FS than Fuji II and the same in CS and DTS as Fuji II. The photo-cured experimental cement was 19%, 47% and 176% higher in CS, DTS and FS than Fuji II LC.

Amino Acids↗

Synthesis and evaluation of novel bifunctional oligomer-based composites for dental applications.

Five novel bifunctional oligomers containing both carboxylic acid and methacrylate groups are synthesized, characterized, and used to formulate compomers by mixing with strontium fluoroaluminosilicate glass powder at a filler level of 75% (by weight). Compressive strength (CS) of the cements and viscosity of the resin liquids are used as screening tools to find the optimal formulation. Diametral tensile (DTS) and flexural strengths (FS) are also determined. Results show that the oligomers derivatized with glycerol dimethacrylate exhibit higher CS than those with 2-hydroxyethyl methacrylate. The CS increases with increasing diluent content, filler level, and light-exposure time. During aging, the cement shows an increase of strength over 24 h and then remains unaltered for up to 3 months. The experimental compomer is 45 and 69% higher in CS, 35 and 174% higher in DTS, and 39 and 170% higher in FS, respectively, as compared to Dyract and Fuji II LC.

Acrylic Resins↗

Phase 1 study of erlotinib HCl alone and combined with temozolomide in patients with stable or recurrent malignant glioma.

The purpose of this study was to define the maximum tolerated dose of erlotinib and characterize its pharmaco-kinetics and safety profile, alone and with temozolomide, with and without enzyme-inducing antiepileptic drugs (EIAEDs), in patients with malignant gliomas. Patients with stable or progressive malignant primary glioma received erlotinib alone or combined with temozolomide in this dose-escalation study. In each treatment group, patients were stratified by coadministration of EIAEDs. Erlotinib was started at 100 mg orally once daily as a 28-day treatment cycle, with dose escalation by 50 mg/day up to 500 mg/day. Temozolomide was administered at 150 mg/m2 for five consecutive days every 28 days, with dose escalation up to 200 mg/m2 at the second cycle. Eightythree patients were evaluated. Rash, fatigue, and diarrhea were the most common adverse events and were generally mild to moderate. The recommended phase 2 dose of erlotinib is 200 mg/day for patients with glioblastoma multiforme who are not receiving an EIAED, 450 mg/day for those receiving temozolomide plus erlotinib with an EIAED, and at least 500 mg/day for those receiving erlotinib alone with an EIAED. Of the 57 patients evaluable for response, eight had a partial response (PR). Six of the 57 patients had a progression-free survival of longer than six months, including four patients with a PR. Coadministration of EIAEDs reduced exposure to erlotinib as compared with administration of erlotinib alone (33%-71% reduction). There was a modest pharmacokinetic interaction between erlotinib and temozolomide. The favorable tolerability profile and evidence of antitumor activity indicate that further investigation of erlotinib is warranted.

Adult↗

Ovarian carcinomas: CCN genes are aberrantly expressed and CCN1 promotes proliferation of these cells.

PURPOSE: The connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed (CCN) family consists of six matricellular proteins that are involved in various cellular functions, such as proliferation, development, and angiogenesis. The purpose of this study was to explore the possibility that CCN genes are involved in ovarian cancers. EXPERIMENTAL DESIGN: We quantified CCN expression in a series of 59 ovarian cancers using quantitative real-time reverse transcription-PCR. CCN1 protein levels were further determined by immunohistochemistry and Western blot analysis. Overexpression and inhibition of CCN1 expression by small interfering RNA were used to examine its role in ovarian cancer cell proliferation in vitro and in vivo. RESULTS: We found dysregulation of levels of the various CCN mRNAs in ovarian cancers compared with their expression in normal whole ovaries. Expression of CCN1 protein was detected in normal ovarian epithelial cells and ovarian tumors as well as in ovarian cancer cell lines. Furthermore, estrogen increased CCN1 mRNA and protein levels in ovarian cancer cells. Ectopic expression of CCN1 enhanced the growth of ovarian cancer cells in liquid culture, whereas inhibition of its expression decreased proliferation and increased apoptosis in these cells. The observed changes in cell growth were accompanied with activation of Akt and extracellular signal-regulated kinase (ERK) signaling pathways. Stable expression of CCN1 in SKOV3 cells significantly increased tumorigenicity in nude mice. Finally, overexpression of CCN1 conferred resistant to carboplatin-induced apoptosis in SKOV3 cells. CONCLUSIONS: This is the first study to show abnormalities in CCN expression in ovarian carcinomas. Furthermore, our results suggest that CCN1 may play a role in ovarian carcinogenesis by stimulating survival and antiapoptotic signaling pathways.

Adult↗

Phase I/II trial evaluating the anti-vascular endothelial growth factor monoclonal antibody bevacizumab in combination with the HER-1/epidermal growth factor receptor tyrosine kinase inhibitor erlotinib for patients with recurrent non-small-cell lung cancer.

PURPOSE: Bevacizumab (Avastin; Genentech, South San Francisco, CA) is a recombinant, humanized anti-vascular endothelial growth factor monoclonal antibody. Erlotinib HCl (Tarceva, OSI-774; OSI Pharmaceuticals, New York, NY) is a potent, reversible, highly selective and orally available HER-1/epidermal growth factor receptor tyrosine kinase inhibitor. Preclinical data in various xenograft models produced greater growth inhibition than with either agent alone. Additionally, both agents have demonstrated benefit in patients with previously treated non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: A phase I/II study in two centers examined erlotinib and bevacizumab (A+T) in patients with nonsquamous stage IIIB/IV NSCLC with > or = one prior chemotherapy. In phase I, erlotinib 150 mg/day orally plus bevacizumab 15 mg/kg intravenously every 21 days was established as the phase II dose, although no dose-limiting toxicities were observed. Phase II assessed the efficacy and tolerability of A+T at this dose. Pharmacokinetic parameters were evaluated. ResultsForty patients were enrolled and treated in this study (34 patients at phase II dose); the median age was 59 years (range, 36 to 72 years), 21 were female, 30 had adenocarcinoma histology, nine were never-smokers, and 22 had > or = two prior regimens (three patients had > or = four prior regimens). The most common adverse events were mild to moderate rash, diarrhea, and proteinuria. Preliminary data showed no pharmacokinetic interaction between A + T. Eight patients (20.0%; 95% CI, 7.6% to 32.4%) had partial responses and 26 (65.0%; 95% CI, 50.2% to 79.8%) had stable disease as their best response. The median overall survival for the 34 patients treated at the phase II dose was 12.6 months, with progression-free survival of 6.2 months. CONCLUSION: Encouraging antitumor activity and safety of A + T support further development of this combination for patients with advanced NSCLC and other solid tumors.

Adult↗

Cytoprotection of PEG-modified adult porcine pancreatic islets for improved xenotransplantation.

Functional poly(ethylene glycol) (PEG) derivatives, including monosuccinimidyl PEG (MSPEG) with molecular weight (MW) of 2000 (2 kDa) as well as 5 kDa and disuccinimidyl PEG (DSPEG) with MW of 3 and 6 kDa, were synthesized and characterized. They were used to modify the surface of adult porcine islets for cytoprotection. The islets were isolated, purified and modified with functional PEG. Untreated porcine islets were used as control. An in vitro human antibody/complement-mediated cytotoxicity test based on the release of intracellular lactate dehydrogenase was used to evaluate cytotoxicity of human serum to the modified islets. In vitro cell viability was assessed using membrane-integrity straining and islet metabolism in culture. In vitro islet functionality was evaluated by glucose-stimulated insulin release of islets in static incubation with human serum. In vivo islet functionality was evaluated by monitoring non-fasting blood glucose level in streptozotocin-induced diabetic (SCID) immunocompromized mice after intraportal transplantation of porcine islets. Results show that all the PEG derivatives used in the study showed significant in vitro and in vivo cytoprotections against cytotoxic effects elicited by human serum and diabetic SCID mice, respectively, to porcine islets. DSPEG derivatives combined with human albumin exhibited a better cytoprotection, as compared to MSPEG ones, due to the capacity of the succinimidyl groups to selectively react with amino groups of the albumin under physiological conditions. The effects of both MW and concentration of the PEG derivatives on cytoprotection were significant. It appears that this novel biotechnology will be an attractive approach for improved xenotransplantation of islets.

Animals↗

Novel amino acid modified zinc polycarboxylates for improved dental cements.

OBJECTIVE: The objective of this study was to develop a novel amino acid modified zinc/calcium polycarboxylate cement system, formulate the cements, and evaluate their mechanical strengths. MATERIALS AND METHODS: Acrylate and methacrylate derivatives of four amino acids were synthesized and characterized using FT-IR and 1HNMR spectroscopy. The derivatives were formulated with polymer having pendent methacrylate group, water, and synthesized novel filler. Compressive (CS) as well as flexural strengths (FS) and viscosities of the resin liquids were used as tools to evaluate the formulations and formed cements. The specimens for CS and FS tests were conditioned in distilled water at 37 degrees C for 24 h and 7 d, respectively, prior to testing. RESULTS: The measured CS and FS of the cements was in the decreasing order of methacryloyl beta-alanine > acryloyl glutamic acid = acryloyl beta-alanine > methacryloyl glutamic acid > 2-hydroxyethyl methacrylate. Methacryloyl beta-alanine was selected for further formulations due to its relatively low solution viscosity and high CS as well as FS. Effects of polymer content, P/L ratio, tartaric acid and initiator concentration were significant. During aging, the cement showed a constant increase in CS for up to 1 month and then kept constant for up to 3 months. CONCLUSIONS: This study developed a novel amino acid modified zinc/calcium polycarboxylate cement system. This system was 85% higher in CS, 98% higher in DTS and 183% higher in FS, compared to Durelon.

Amino Acids↗

Cyr61 suppresses the growth of non-small-cell lung cancer cells via the beta-catenin-c-myc-p53 pathway.

Cysteine-rich protein 61 (Cyr61) is a growth factor-inducible, immediate-early gene that has multifaceted activities in various cancers. In a previous study, we found that Cyr61 inhibited the growth of the H520 and H460 non-small-cell lung cancer (NSCLC) cell lines. In further studies, we now report that p53 plays a pivotal role in Cyr61-dependent cellular growth arrest. Blocking Cyr61 with a Cyr61 antibody resulted in the downregulation of expression of p53 and p21, as well as partially reversing the growth suppression of H520-Cyr61 cells. Proliferation of NSCLC cell lines (NCI-H157, H125, H1299), having a mutant p53, were not suppressed by Cyr61. Inhibition of wild-type p53, by either human papilloma virus type 16 E6 or a dominant-negative p53, resulted in the rescue of the growth suppression mediated by Cyr61 in the H520-Cyr61 cells. The enhanced levels of p21WAF1 and p130/RB2, in the Cyr61-expressing H520-Cyr61 cells, were also inhibited by blocking p53 showing that p21 and p130 were induced by p53 in these cells. In addition, levels of both c-myc and beta-catenin increased in Cyr61 stably transfected H520 cells. Moreover, beta-catenin was translocated into the nucleus in these cells. Inhibition of c-myc expression in the H520-Cyr61 cells with antisense c-myc resulted in their decreased levels of p53. Transfecting cells with a dominant-negative T-cell factor (TCF4), the specific inhibitor of the beta-catenin/TCF4 complex, downregulated the expression of c-myc. Taken together, the data suggest that Cyr61 suppressed the growth of NSCLC cells by triggering a signal transduction pathway through beta-catenin. In this pathway, Cyr61 activated the beta-catenin/TCF4 complex, which promoted the expression of c-myc and the latter induced expression of p53, and p53 upregulated p21WAF1 and p130/RB2, resulting in growth arrest.

Carcinoma, Non-Small-Cell Lung↗

Cyr61 is overexpressed in gliomas and involved in integrin-linked kinase-mediated Akt and beta-catenin-TCF/Lef signaling pathways.

Cyr61 is a member of the CCN family of growth factors; these proteins are secreted and can act as ligands of distinct integrins. We show that Cyr61 can enhance tumorigenicity of glioma cells acting through activated integrin-linked kinase (ILK) to stimulate beta-catenin-TCF/Lef and Akt signaling pathways. Overexpression of Cyr61 occurred in highly tumorigenic glioma cell lines and in 68% of the most malignant glioblastoma multiforme brain tumors. Forced expression of Cyr61 in U343 glioma cells accelerated their growth in liquid culture, enhanced their anchorage-independent proliferation in soft agar, and significantly increased their ability to form large, vascularized tumors in nude mice. Overexpression of Cyr61 in the U343 cells led to the up-regulation of distinct integrins, including beta1 and alphanubeta3, which have been shown to interact with Cyr61 and ILK. The activity of ILK was increased dramatically in these cells. Overexpression of Cyr61 also resulted in the phosphorylation of glycogen synthase kinase-3beta and accumulation and nuclear translocation of beta-catenin, leading to activation of the beta-catenin-TCF/Lef-1 signaling pathway. Furthermore, forced expression of Cyr61 in the glioma cells activated phosphatidylinositol 3'-kinase pathway, resulting in prominent phosphorylation of Akt and the antiapoptotic protein Bad. Cyr61 appears to stimulate several signaling pathways in the development of gliomas.

Animals↗

Levels of expression of CYR61 and CTGF are prognostic for tumor progression and survival of individuals with gliomas.

The biological properties of CCN proteins include stimulation of cell proliferation, migration, and adhesion, as well as angiogenesis and tumorigenesis. We quantified CYR61, CTGF, WISP-1, and NOV mRNA expression levels in samples from sixty-six primary gliomas and five normal brain samples using quantitative real-time PCR assay. Statistical analysis was performed to explore the links between expression of the CCN genes and clinical and pathological parameters. Overexpression of CYR61, CTGF, WISP-1, and NOV occurred in 48% (32 of 66), 58% (38 of 66), 36% (24 of 66), and 15% (10 of 66) of primary gliomas, respectively. Interestingly, significant associations were found between CYR61 expression versus tumor grade, pathology, gender, and age at diagnosis. Also, a significant correlation existed between CTGF mRNA levels versus tumor grade, gender, and pathology. In contrast to CYR61 and CTGF, no significant association was found between expression of either WISP-1 or NOV versus any of the pathological features. Furthermore, Cox regression analysis showed that CYR61 and CTGF expression had a significant correlation with patient survival. These results suggest that CYR61 and CTGF may play a role in the progression of gliomas; their levels at diagnosis may have prognostic significance; and these proteins might serve as valuable targets for therapeutic intervention.

Adult↗

An amino acid-modified and non-HEMA containing glass-ionomer cement.

It is known that unreacted 2-hydroxyethyl methacrylate (HEMA) in current resin modified glass ionomer cements (RMGICs) shows potential cytotoxicity to pulp and surrounding tissues. Elimination of HEMA could make RMGICs more attractive for dental applications. In this research, novel six acrylate and methacrylate derivatives of amino acids were synthesized, characterized and used for replace HEMA in RMGICs. The experimental RMGICs were formulated with vinyl-containing polymer, amino acid derivative, water, and commercial Fuji II LC glass. Among all the derivatives, methacryloyl beta-alanine (MBA) was selected for further formulations due to its relatively low solution viscosity and high CS. Effects of polymer content and powder/liquid, P/L, ratio were significant. The formulation with liquid composition of 50/25/25 (polymer/MBA/water) and P/L ratio of 2.7/1 was found the optimal. It appears that this novel non-HEMA-containing RMGIC system based on amino acid derivatives will be a better dental restorative because it demonstrated improved mechanical strengths and may eliminate potential cytotoxicity in current RMGICs caused by leached HEMA. The optimal MBA-modified GIC were 20% higher in CS, 70% higher in DTS and 93% higher in FS, compared to Fuji II LC.

Acrylates↗