Effect of polymerization temperature on the properties of autopolymerizing resin.

STATEMENT OF PROBLEM: The polymerization conditions of an autopolymerizing resin affect its physical properties, and at chairside, 3 different methods are commonly used: cooling in cold water, warming in warm water, and heating in hot water. However, the effects of polymerization temperature on the physicomechanical properties of autopolymerizing resin are unclear. PURPOSE: The purpose of this in vitro study was to determine the effect of polymerization temperature on the physicomechanical properties of autopolymerizing resin, including shrinkage, water absorption, surface roughness, amount of residual monomer, and flexural strength. MATERIAL AND METHODS: The experiment was designed to simulate a direct technique commonly used for the fabrication of interim crowns. Autopolymerizing resin specimens were made according to the powder-to-liquid ratio recommended by the manufacturer and soaked in water at 13°C, 37°C, or 60°C for 2 minutes to mold the resin until polymerization was completed 4 minutes after mixing. Shrinkage, water absorption rate, surface roughness, residual monomer, and flexural strength were measured immediately after polymerization and after 1, 3, and 7 days in distilled water at 37°C. Differences among these properties among the 3 different temperatures groups were statistically analyzed by using 1-way ANOVA and the Tukey honest significant difference test (α=.05). RESULTS: Shrinkage tests showed that the 13°C group had significantly lower shrinkage (P=.004 for 37°C and P<.001 for 60°C) than the other groups immediately after specimen preparation. The 13°C group had significantly higher surface roughness after 0 (P<.001 for 37°C and P<.001 for 60°C), 1 (P=.025 for 37°C and P=.012 for 60°C), 3 (P<.001 for 37°C and P<.001 for 60°C), and 7 days (P<.001 for 37°C and P<.001 for 60°C) than those in the other groups and significantly higher water absorption rates (P=.033 for 37°C and P<.001 for 60°C) than the other groups during the 7 days after fabrication. However, the 13°C group showed significantly higher weight percentage of residual monomers than the 60°C group at 0 (P<.001) and 1 day (P<.001). Finally, 3-point bend tests showed that the 13°C group had significantly lower flexural strength at 0 (P<.001), 1 (P<.001), 3 (P<.001), and 7 days (P<.001) than the other groups. CONCLUSIONS: The temperature environment during dental chairside polymerization of the autopolymerizing resin affected the physicomechanical properties of shrinkage, water absorption rate, surface roughness, residual monomer, and flexural strength.

[USEFULNESS OF THE FORCED OSCILLATION TECHNIQUE IN THE DIAGNOSIS OF COUGH VARIANT ASTHMA WITH PROLONGED OR CHRONIC COUGH].

BACKGROUND: Usefulness of carrying out the reversibility test after inhaling bronchodilator by forced oscillation technique (FOT) in addition to spirometry was investigated in the diagnosis of bronchial asthma (BA), cough variant asthma (CVA) and allergic rhinitis (AR) with prolonged or chronic cough. METHODS: The subjects were the 622 patients at Idaimaeminamiyojo Clinic in Sapporo who complained cough over three weeks, and underwent bronchial reversibility test with salbutamol by using spirometry and FOT. We divided them into 5 groups; BA, BA+AR, CVA, CVA+AR, AR, and examined their lung functions. RESULTS: The mean of improvement of FEV1 after inhalation of salbutamol was significantly different (p<0.001); 465ml (26%) of BA, 136ml (5.5%) of CVA, and 44ml (1.6%) of AR. However, in CVA, the mean reversibility value was not over the diagnostic criteria of BA; 200ml (12%). Improvement of respiratory resistant at 5Hz (R5) using FOT in BA/CVA were 25.7%/24.1%, and significantly higher (p<0.001) than that in AR, and these results were alike even in cases accompanied by AR; BA+AR, CVA+AR, and AR. AUC value in the ROC curve for diagnosis of CVA from AR with R5 was 0.870, and highest among with R5, R20, R35 and Fres. When the cut off value of R5 improvement was 15%, sensitivity was 74% and specificity was 81%. CONCLUSION: It was suggested that the additional bronchial reversibility test using FOT may be useful especially in the diagnosis of cough variant asthma where the reversibility in spirometry alone is not sufficient.

Concomitant chemoradiotherapy and antiretroviral therapy for HIV-infected patients with locoregionally advanced non-small cell lung cancer: benefit and tolerability of treatment in 2 cases.

BACKGROUND: Human immunodeficiency virus (HIV)-infected patients are surviving longer since the advent of antiretroviral therapy. Therefore, more patients are developing non-AIDS-defining cancers which increasingly determine mortality. CASE REPORTS: Here we present 2 cases of locally advanced non-small cell lung cancer treated initially with concomitant chemoradiotherapy and antiretroviral therapy. Both patients were male, ages 69 and 66, with known HIV infection and immunologically stable on antiretroviral therapy. Presenting symptoms included superior sulcus tumor with left arm immobility and sensory disturbance in case 1 and right lower bronchus constriction in case 2. Symptoms were controlled by chemoradiotherapy. CONCLUSION: These cases illustrate that intensive anticancer therapy administered to the HIV-infected population can be tolerated even though these patients seem to be too fragile for both chemotherapy and radiotherapy, especially since the potential benefit remains uncertain. Recent improvements in chemoradiotherapy and supportive care have enhanced tolerance for such therapy.

Refeeding activates neurons in the dorsomedial hypothalamus to inhibit food intake and promote positive valence.

OBJECTIVE: The regulation of food intake is a major research area in the study of obesity, which plays a key role in the development of metabolic syndrome. Gene targeting studies have clarified the roles of hypothalamic neurons in feeding behavior, but the deletion of a gene has a long-term effect on neurophysiology. Our understanding of short-term changes such as appetite under physiological conditions is therefore still limited. METHODS: Targeted recombination in active populations (TRAP) is a newly developed method for labeling active neurons by using tamoxifen-inducible Cre recombination controlled by the promoter of activity-regulated cytoskeleton-associated protein (Arc/Arg3.1), a member of immediate early genes. Transgenic mice for TRAP were fasted overnight, re-fed with normal diet, and injected with 4-hydroxytamoxifen 1 h after the refeeding to label the active neurons. The role of labeled neurons was examined by expressing excitatory or inhibitory designer receptors exclusively activated by designer drugs (DREADDs). The labeled neurons were extracted and RNA sequencing was performed to identify genes that are specifically expressed in these neurons. RESULTS: Fasting-refeeding activated and labeled neurons in the compact part of the dorsomedial hypothalamus (DMH) that project to the paraventricular hypothalamic nucleus. Chemogenetic activation of the labeled DMH neurons decreased food intake and developed place preference, an indicator of positive valence. Chemogenetic activation or inhibition of these neurons had no influence on the whole-body glucose metabolism. The labeled DMH neurons expressed prodynorphin (pdyn), gastrin-releasing peptide (GRP), cholecystokinin (CCK), and thyrotropin-releasing hormone receptor (Trhr) genes. CONCLUSIONS: We identified a novel cell type of DMH neurons that can inhibit food intake and promote feeding-induced positive valence. Our study provides insight into the role of DMH and its molecular mechanism in the regulation of appetite and emotion.

Effect of laser groove treatment on shear bond strength of resin-based luting agent to polyetheretherketone (PEEK).

PURPOSE: The mechanical properties of polyetheretherketone (PEEK) are ideally suited for fixed dental prostheses. However, PEEK typically has low adhesion strength to resin-based luting agent. This study assessed the shear bond strength between laser groove treated PEEK and resin-based luting agent. METHODS: A total of 230 specimens were randomly divided into five groups (n=46): no-treatment, air abrasion treatment, 100µm-deep, 150µm-deep, and 200µm-deep laser groove treatments. The surface roughness was measured, scanning electron microscopy was used to observe the specimen surfaces, and X-ray photoelectron spectroscopy (XPS) was used to analyze the surfaces. Each group was divided into four resin-based luting agent subgroups: Panavia V5, RelyX Ultimate Resin Cement, G-CEM Link Force, and Super-Bond C&B. After the resin-based luting agent was bonded to the specimens, the bond strength was measured using shear tests and the failure modes were assessed by stereomicroscopy. The surfaces were also observed by scanning electron microscopy (SEM) after the shear bond strength measurements. The data were statistically analyzed using a two-way analysis of variance and Tukey's honest significant difference test (α=0.05). RESULTS: The PEEK surface after laser groove treatment groups exhibited the highest mean Ra values. In the XPS analysis, the laser treated PEEK surface exhibited an effective surface composition for bonding with resin-based luting agent. The shear bond strengths for the laser groove treated samples were significantly higher (p<0.05) than those of the no-treatment and air abrasion treatment groups. CONCLUSIONS: The shear bond strength between PEEK and resin-based luting agent was substantially improved by laser groove treatment.

Enhancement of calcification by osteoblasts cultured on hydroxyapatite surfaces with adsorbed inorganic polyphosphate.

Inorganic polyphosphate has been expected to accelerate bone regeneration. However, there are limited evidences to prove that polyphosphate adsorbed on the surface of a hydroxyapatite plate enhances calcification of cultured osteoblasts. In this study, we examined the effect of polyphosphate adsorbed onto the surface of a hydroxyapatite plate on the attachment, proliferation, differentiation, and calcification of osteoblasts. After hydroxyapatite plates were soaked in solutions of polyphosphate, the plate surfaces were analyzed by scanning electron microscopy and toluidine blue staining to confirm adsorption of polyphosphate. The hydroxyapatite plates were further subjected to the measurements of surface roughness, water contact angle, and the binding capacity of calcium ions. Cell culture experiments were carried out using MC3T3-E1 pre-osteoblastic cells. It was found that soaking a hydroxyapatite plate in a polyphosphate solution gave rise to an increase in surface roughness and reduction in water contact angle in a concentration-dependent manner, suggesting the adsorption of polyphosphate onto the surface of a hydroxyapatite plate. It was further observed that surface-adsorbed polyphosphate exhibited an inhibitory effect on cell adhesion and proliferation. In contrast, cell differentiation was promoted on hydroxyapatite plates with adsorbed polyphosphate, when assessed from expression of differentiation marker genes including alkaline phosphatase, osteopontin, and osteocalcin. In addition, calcification of the culture was enhanced on hydroxyapatite plates with relatively low density of adsorbed polyphosphate. Our results as a whole provided an evidence to show that there is a narrow window with regard to the surface density of adsorbed polyphosphate for the enhancement of osteoblast calcification.

Factors related to masticatory performance in healthy elderly individuals.

PURPOSE: Maintenance of natural dentition and/or prosthodontic rehabilitation is necessary for good masticatory function. Although other factors such as physical and oral functions are also important for masticatory performance, only a few studies have evaluated their roles. The aim of the current study was to assess factors associated with masticatory performance among elderly individuals, while maintaining and/or reconstructing all occlusal support areas. METHODS: The present study was designed and implemented as a cross-sectional study, involving a total of 262 participants (mean age: 74.2±5.9years) who participated in the Kyoto Elders Physical Fitness Measurement Research Project. Individuals with partial or complete edentulousness who did not use dentures were excluded from the study. The predictor variables included physical status (i.e., age, gender, body-mass index, and grip strength), oral conditions (i.e., number of present teeth, temporomandibular joint noise, and denture wearer), and oral functions (i.e., maximum voluntary occlusal force; occlusal contact area; cheek pressure; oral diadochokinesis test /pa/, /ta/, /ka/; and maximum voluntary tongue pressure). The variable outcome was masticatory performance. These variables among the participants using univariate and multivariate analyses were compared. RESULTS: Grip strength, number of present teeth, maximum voluntary occlusal force, occlusal contact area, oral diadochokinesis /ka/ /ta/, and maximum voluntary tongue pressure were significant factors for masticatory performance. Stepwise regression analysis showed that grip strength, maximum voluntary occlusal force, and diadochokinesis /ta/ significantly affected masticatory performance. CONCLUSIONS: Masticatory performance was closely associated with grip strength, maximum voluntary occlusal force, and diadochokinesis /ta/ among healthy elderly participants.

Clinical outcomes after first-line EGFR inhibitor treatment for patients with NSCLC, EGFR mutation, and poor performance status.

BACKGROUND: The phase II NEJ001 trial suggested that gefitinib was active against advanced non-small cell lung cancer (NSCLC) even in patients with poor performance status (PS). Clinical response among the patients harboring epidermal growth factor receptor (EGFR) mutation with poor PS is fair; however, gefitinib does not have as much continued efficacy as in patients with good PS. This study has retrospectively investigated the clinical outcomes of gefitinib treated patients with advanced NSCLC, EGFR mutations, and poor PS. PATIENTS AND METHODS: A total of 208 patients with advanced NSCLC and poor PS treated with gefitinib from 2004 to 2013 were retrospectively evaluated. Outcomes were studied after stratification for gender, smoking status, histological subtype, and EGFR mutation status. RESULTS: Fifty-two patients (25.0%) with advanced NSCLC, EGFR mutation, and poor PS were treated with gefitinib. The overall response rate was 65.4%. The median progression-free survival, median survival time, and one-year survival rate was 6.6 months, 19.6 months, and 62.9%, respectively. Death due to interstitial lung disease occurred in 11.5% of the patient population. In multivariate analysis, a PS of 4 was independently associated with poor outcomes (hazard ratio=10.5; 95% Confidence interval=1.92-50.19; p=0.0091). CONCLUSION: Patients with advanced NSCLC, EGFR mutation, and poor PS have poor outcomes in response to gefitinib. However, the indication of gefitinib for such patients will not be changed in clinical practice and oncologists should treat these patients with more careful follow-up since for those with poor PS, therapy may be more toxic than for patients with good PS.