ABSTRACT
BACKGROUND AND AIMS: Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. MATERIALS AND METHODS: 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. RESULTS: The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P < 0.05). For UDMA the interaction was significant only after 1 week. In microhybrid composites, the CO subgroup showed more monomer release than LBH and LBO. In nanohybrid composites, LBH showed more monomer release than CIB and CO subgroups. For BIS-GMA monomers the interaction was significant at all time periods and the LBH subgroup of nanohybrid composite had significantly more BIS_GMA release in comparison to other subgroups. CONCLUSION: Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.
ABSTRACT
The potential for continuous infusion of cimetidine to affect the clearance of aminophylline was assessed in 18 critically ill patients treated for bronchospasm. This was a pharmacokinetic drug-drug interaction study in which the subjects were administered aminophylline as a continuous infusion at low doses (mean 10.8 mg/hr). Subjects were started on cimetidine (50 mg/hr) 24 hours post aminophylline drip and remained on it for 48 hours. Theophylline clearance was determined right before and 48 hours after starting cimetidine. There were no significant differences in theophylline clearance before and after infusion of cimetidine (P >.05). Based on our findings, cimetidine does not seem to affect the clearance of low doses of theophylline in critically ill patients.
Subject(s)
Anti-Ulcer Agents/administration & dosage , Bronchodilator Agents/administration & dosage , Bronchodilator Agents/pharmacokinetics , Cimetidine/administration & dosage , Theophylline/administration & dosage , Theophylline/pharmacokinetics , Adolescent , Adult , Aged , Bronchial Spasm/drug therapy , Bronchodilator Agents/blood , Critical Illness , Cross-Sectional Studies , Cytochrome P-450 CYP1A2/drug effects , Drug Interactions , Drug Monitoring , Female , Humans , Infusions, Intravenous , Male , Metabolic Clearance Rate , Middle Aged , Prospective Studies , Theophylline/blood , Time FactorsABSTRACT
Generalized least squares regression with variance function estimation was used to derive the calibration function for measurement of methotrexate plasma concentration and its results were compared with weighted least squares regression by usual weight factors and also with that of ordinary least squares method. In the calibration curve range of 0.05 to 100 microM, both heteroscedasticity and non-linearity were present therefore ordinary least squares linear regression methods could result in large errors in the calculation of methotrexate concentration. Generalized least squares regression with variance function estimation worked better than both the weighted regression with the usual weight factors and ordinary least squares regression and gave better estimates for methotrexate concentration.