gC1qR Antibody Can Modulate Endothelial Cell Permeability in Angioedema.

Angioedema is characterized by swelling of the skin or mucous membranes. Overproduction of the vasodilator bradykinin (BK) is an important contributor to the disease pathology, which causes rapid increase in vascular permeability. BK formation on endothelial cells results from high molecular weight kininogen (HK) interacting with gC1qR, the receptor for the globular heads of C1q, the first component of the classical pathway of complement. Endothelial cells are sensitive to blood-flow-induced shear stress and it has been shown that shear stress can modulate gC1qR expression. This study aimed to determine the following: (1) how BK or angioedema patients' (HAE) plasma affected endothelial cell permeability and gC1qR expression under shear stress, and (2) if monoclonal antibody (mAb) 74.5.2, which recognizes the HK binding site on gC1qR, had an inhibitory effect in HK binding to endothelial cells. Human dermal microvascular endothelial cells (HDMECs) grown on Transwell inserts were exposed to shear stress in the presence of HAE patients' plasma. Endothelial cell permeability was measured using FITC-conjugated bovine serum albumin. gC1qR expression and HK binding to endothelial cell surface was measured using solid-phase ELISA. Cell morphology was quantified using immunofluorescence microscopy. The results demonstrated that BK at 1 µg/mL, but not HAE patients' plasma and/or shear stress, caused significant increases in HDMEC permeability. The mAb 74.5.2 could effectively inhibit HK binding to recombinant gC1qR, and reduce HAE patients' plasma-induced HDMEC permeability change. These results suggested that monoclonal antibody to gC1qR, i.e., 74.5.2, could be potentially used as an effective therapeutic reagent to prevent angioedema.

Effect of Root Canal Filling Materials and Pretreatment with Solvents on the Shear Bond Strength of Composite Resin with Primary Tooth Dentin.

AIM: Root canal filling materials have the tendency to inhibit adhesion of resin-based composites. This study was aimed at evaluating the effect of root canal filling materials and their solvents on the shear bond strength (SBS) of resin composite with the primary tooth dentin. METHODS AND MATERIALS: Seventy-two intact anterior primary teeth were selected. Smooth dentinal surfaces were prepared to a minimum diameter of 3 mm and thickness of 1.5-2.0 mm. The samples were equally divided into six groups (n = 12). In group 1: control group, no root filling material; in group 2: Metapex, no solvent; in group 3: Metapex+ethanol solvent; in group 4: ZOE, no solvent; in group 5: ZOE+ethanol solvent; and in group 6: ZOE+orange oil solvent were applied. Then, dentin surfaces were etched, and composite restorations were placed and cured. The specimens were stored in distilled water at 37°C for 24 hours. SBS values were determined using a universal testing machine. RESULTS: The SBS values of composite to dentin in groups 2 and 4 were significantly lower than those in the control group (P < 0.001). Cleansing of the specimens with 96% ethanol after removal of Metapex significantly increased the composite-dentin bond (P < 0.001). Applying ZOE, only orange oil solvent significantly increased the SBS of the composite to the primary tooth dentin (P = 0.01). CONCLUSION: To reduce the negative effects of endodontic root filling materials on the SBS of composite and primary tooth dentin, ethanol is a suitable solvent when Metapex is used, while orange oil might be a better choice than ethanol when applying ZOE.

Effect of bleaching with carbamide peroxide on shear bond strength of orthodontic brackets: A meta-analysis of in vitro studies.

INTRODUCTION: This study aimed to evaluate the effect of bleaching with carbamide peroxide (CP) according to different doses and intervals between bleaching and bonding on shear bond strength (SBS) of orthodontic brackets. METHODS: Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, PubMed, and Scopus were searched for articles published up to June 2018. After removing the duplicates, two of the authors screened the titles and abstracts independently. Assessing the eligibility of the selected full texts was also conducted by two of the authors independently. Disagreements were resolved by discussion. Modified version of Cochrane's risk of bias tool was used to assess the quality of studies. Fifteen studies were selected. RESULTS: Overall, bleaching with CP decreased the SBS by around 2MPa (P<0.0001). Using 10% CP decreased the SBS of the immediately bonded brackets by 5.13MPa (P<0.005). This value was 1.67MPa when the bonding procedure was postponed by one day (P<0.0001). Postponing the bonding procedure for longer periods did not cause a statistically significant change in SBS. Using 11-16% CP, the reduction in SBS of the immediately bonded brackets was 8.51MPa (P<0.01). The SBS decreased by 4.12MPa when the bonding procedure was postponed for 20days (P<0.05). According to one study, use of CP with>16% concentration seemed not to affect the SBS. CONCLUSIONS: Bleaching with CP decreases the SBS, especially if the bracket bonding is performed shortly after bleaching. However, given the small number of articles interpretation should be made with caution.

Hydrofluoric acid concentration, time and use of phosphoric acid on the bond strength of feldspathic ceramics.

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.

In vitro bleaching effect of hydrogen peroxide with different time of exposition and concentration on shear bond strength of orthodontic brackets to human enamel: A meta-analysis of in vitro studies.

INTRODUCTION: Controversy exists regarding the effect of bleaching on shear bond strength (SBS) of orthodontic brackets to enamel. This study aims to do a review and meta-analysis on the effect of bleaching with hydrogen peroxide on SBS according to the interval between bleaching and bonding to human enamel and the concentration of Hydrogen Peroxide. METHODS: An electronic search of the literature was performed in Scopus, PubMed and Cochrane databases including CENTRAL and Cochrane library for relevant in vitro studies on the effect of bleaching with hydrogen peroxide on shear bond strength of human enamel, published until June 2018. Modified Cochrane Risk of Bias tool was used to assess the quality of the individual studies. AMSTAR tool was used for assessing the quality of the study. RESULTS: Nineteen studies were included in the qualitative analysis. Regardless of the interval between bleaching and bonding, reduction in SBS was not statistically significant when the hydrogen peroxide of less than 35% is used. Bleaching with 35% hydrogen reduces SBS when the bonding is conducted immediately (P<0.0001) or the time interval was shorter than one day (P<0.0005). On the other hand, use of high dose hydrogen peroxide resulted in a statistically significant reduction in SBS irrespective of the time interval between the procedures (P<0.05 for all categories of time interval). CONCLUSION: Bleaching with hydrogen peroxide decreases the SBS of brackets in patients undergoing orthodontic treatment especially if the time interval between bleaching and bonding procedures is short and a high concentration of hydrogen peroxide is used.

Wortmannin targeting phosphatidylinositol 3-kinase suppresses angiogenic factors in shear-stressed endothelial cells.

Modifications on shear stress-based mechanical forces are associated with pathophysiological susceptibility and their effect on endothelial cells (EC) needs to be better addressed looking for comprehending the cellular and molecular mechanisms. This prompted us to better evaluate the effects of shear stress in human primary venous EC obtained from the umbilical cord, using an in vitro model to mimic the laminar blood flow, reaching an intensity 1-4 Pa. First, our data shows there is a significant up-expression of phosphatidylinositol 3-kinase (PI3K) in shear-stressed cells culminating downstream with an up-phosphorylation of AKT and up-expression of MAPK-ERK, concomitant to a dynamic cytoskeleton rearrangement upon integrin subunits (α4 and ß 3) requirements. Importantly, the results show there is significant involvement of nitric oxide synthase (eNOS), nNOS, and vascular endothelial growth factors receptor 2 (VEGFR2) in shear-stressed EC, while cell cycle-related events seem to being changed. Additionally, although diminution of 5-hydroxymethylcytosine in shear-stressed EC, suggesting a global repression of genes transcription, the promoters of PI3K and eNOS genes were significantly hydroxymethylated corroborating with their respective transcriptional profiles. Finally, to better address, the pivotal role of PI3K in shear-stressed EC we have revisited these biological issues by wortmannin targeting PI3K signaling and the data shows a dependency of PI3K signaling in controlling the expression of VGFR1, VGFR2, VEGF, and eNOS, once these genes were significantly suppressed in the presence of the inhibitor, as well as transcripts from Ki67 and CDK2 genes. Finally, our data still shows a coupling between PI3K and the epigenetic landscape of shear-stressed cells, once wortmannin promotes a significant suppression of ten-11 translocation 1 (TET1), TET2, and TET3 genes, evidencing that PI3K signaling is a necessary upstream pathway to modulate TET-related genes. In this study we determined the major mechanotransduction pathway by which blood flow driven shear stress activates PI3K which plays a pivotal role on guaranteeing endothelial cell phenotype and vascular homeostasis, opening novel perspectives to understand the molecular basis of pathophysiological disorders related with the vascular system.

Hydrofluoric acid concentration, time and use of phosphoric acid on the bond strength of feldspathic ceramics

Abstract The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.

Influence of the mode of application of universal adhesive systems on adhesive properties to fluorotic enamel.

The objective of this study is to compare the resin-enamel bond strength (mµSBS), in-situ degree of conversion (DC), and the enamel-etching pattern (SEM/EDX) of universal adhesive systems when applied to sound and fluorotic enamel. Ninety-eight human molars were sectioned into 4 parts and divided into 24 groups according to 1) enamel surface (sound or fluorotic enamel), 2) adhesive system (Clearfil Universal Bond [CUB], Futurabond U [FBU], iBond Universal [IBU], and Scotchbond Universal [SBU]), and 3) application mode (etch-and-rinse [ER], active self-etch [Active-SE], and passive self-etch [Passive-SE]). Specimens were stored at 37 °C, for 24 hours and tested at 1.0 mm/min (µSBS). Enamel-resin interfaces were evaluated for in-situ DC. The enamel-etching pattern was evaluated under a SEM/EDX. Data from mµSBS and in-situ DC was analyzed using a three-way ANOVA and Tukey's test at 5 % level of significance. For all adhesives, the ER resulted in a statistically significant higher mean mµSBS than the passive-SE in both substrates (p < 0.001). For all adhesives, active-SE resulted in mean mµSBS (p > 0.31) and in-situ DC (p > 0.45) that were statistically similar to those obtained with the ERs in both substrates. A statistically significant, higher mean mµSBS and in-situ DC were obtained in sound enamel (p < 0.001) than in fluorotic enamel. In general, SBU showed higher mean values for mµSBS and in-situ DC compared to those of CUB and IBU (p < 0.001). ER and active-SE showed the deepest enamel-etching pattern in both substrates. A higher amount of fluor was observed in fluorotic enamel. The active application of universal adhesives in the SE-mode may be a viable alternative to increase the adhesive properties in sound and fluorotic enamel.

TiO2 Coating and UV Photofunctionalization Enhance Blood Coagulation on Zirconia Surfaces.

This in vitro study was designed to evaluate the effect of sol-gel derived TiO2 coating on blood coagulation, blood protein adsorption, and platelet response on zirconia surfaces. Square-shaped zirconia (n=96) (10x10x2 mm) was cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n=32) were fabricated: (a) zirconia coated with sol-gel derived TiO2, (b) zirconia coated with sol-gel derived TiO2 and treated with ultraviolet (UV) irradiation for 1 hour, and (c) non-coated zirconia as control. The coatings were prepared from tetraisopropyl orthotitanate solution by dip-coating. The thrombogenicity of the specimens was evaluated using a whole blood kinetic clotting time method where the extent of blood clotting was evaluated at 10, 20, 30, 40, 50, and 60 minutes (n=4/time point, total n=24/group). Scanning electron microscope images were taken to observe platelet morphologies after 1-hour incubation with platelet-rich plasma (PRP) (n=5/group). Surface characteristics were visualized using atomic force microscopy (n=1/group). Adsorption of plasma proteins and fibronectin on each surface was studied by gel electrophoresis (n=2/group). Significant differences were observed in blood coagulation between the test groups at 20-, 30-, 40-, and 50-minute time points (p<0.005). UV treated TiO2 coated specimens showed fastest blood coagulation followed by TiO2 coated and non-coated specimens. Furthermore, platelets appeared at a higher activation state on coated specimens. Gel electrophoresis revealed no difference in protein adsorption among the experimental groups. In summary, TiO2 coatings promoted blood coagulation, and it was further enhanced by UV treatment, which has the potential to hasten the wound healing process in vivo.

Protocatechuic acid improved growth performance, meat quality, and intestinal health of Chinese yellow-feathered broilers.

The aim of this study was to investigate the effect of protocatechuic acid (PCA) on the growth performance, meat quality, and intestinal health of Chinese yellow-feathered broilers. Growing broilers were fed the basal diet or diets supplemented with 300 or 600 mg/kg PCA, or 200 mg/kg enramycin for 52 D. We found that addition of 300 mg/kg PCA significantly increased body weight, live weight, and carcass weight and decreased the feed to gain ratio of broilers; PCA improved meat quality through reducing shear force, and increasing a* (relative redness) and decreasing b* (relative yellowness) at 24 h after slaughter. The activities of alkaline phosphatase and diamine oxidase in plasma were significantly decreased by administration of 300 mg/kg PCA; PCA also significantly increased total antioxidant capability and decreased malondialdehyde content and activity of xanthine oxidase in liver. Meanwhile, it enhanced activities of total superoxide dismutase, glutathione s-transferase, and glutathione peroxidase in the jejunal mucosa. Interleukin-10 and transforming growth factor-ß were significantly increased in jejunal mucosa and plasma of 300 mg/kg PCA diet group, whereas interluekin-2 and interferon-γ dropped dramatically. Moreover, relative expression of apoptosis-related genes decreased in liver, whereas that of intestinal barrier-related and immunity-related genes increased in jejunum. Furthermore, 300 mg/kg PCA treatment significantly changed α-diversity and structure of the cecal microflora in broilers, with increasing relative abundance of Firmicutes and Actinobacteria while reducing Bacteroidetes and Proteobacteria. These results indicated that PCA improved the feed efficiency, growth performance, meat quality of broilers, and antioxidant capacity. It also enhanced intestinal immune function and improved the structure of intestinal flora to favor improved intestinal health in Chinese yellow-feathered broilers.

Effects of naturally-produced lovastatin on carcass characteristics, muscle physico-chemical properties and lipid oxidation and cholesterol content in goats.

This study investigated the carcass characteristics, physico-chemical properties, storage stability and cholesterol content of meat from goats fed with different levels of naturally-produced lovastatin used to mitigate enteric methane production. Twenty intact Saanen male goats of 5-6 months old with initial live weight of 25.8 ±â€¯4.0 kg were randomly allotted into four dietary treatments containing 0 (Control), 2 (Low), 4 (Medium) and 6 mg (High) per kg live weight (LW) of naturally-produced lovastatin for 12 consecutive weeks. No differences were found in all the parameters measured except for full LW, hot and cold carcass weight, shear force, color and cholesterol content among the treatment groups. Aging had significant effects on all the parameters measured in this study except a* (redness) of meat. Meat samples in the Medium and High treatments were of higher lightness and yellowness, more tender and lower cholesterol levels. We conclude that, in addition to mitigate enteric methane emissions, dietary supplementation of naturally-produced lovastatin at 4 mg/kg LW could be a feasible feeding strategy to produce tender meat containing lower cholesterol.

Comparative evaluation of effects of natural antioxidants on the shear bond strength of composite resin to bleached enamel.

CONTEXT: The use of antioxidants immediately after bleaching showed increased bond strength. AIMS: This study aimed to compare the effects of natural antioxidants on the shear bond strength of composite resin to bleached enamel. MATERIALS AND METHODS: Fifty extracted single-rooted upper incisors were decoronated by sectioning the roots 2 mm below the cementoenamel junction, and then, crowns were embedded in autopolymerizing acrylic resin block (3.0 cm × 3.0 cm × 3.0 cm) with the labial surface exposed. They were randomly divided into five groups, depending on the type of antioxidant used (n = 10): (i) Group 1: control (no bleaching), (ii) Group 2: bleaching only, (iii) Group 3: bleaching + 10% sodium ascorbate (antioxidant), (iv) Group 4: bleaching + green tea, and (v) Group 5: bleaching + white tea. Labial surfaces of 40 teeth were bleached with 38% hydrogen peroxide for 20 min following manufacturer's instructions. After that, the experimental groups (Groups 3, 4, and 5) were treated with respective antioxidant solutions before composite restorations were done using a cylindrical plastic mold (3 mm × 5 mm). Shear bond strength of the specimens was tested under universal testing machine. STATISTICAL ANALYSIS: Data were analyzed with ANOVA and Tukey's post hoc test. RESULTS: There were statistically significant differences between shear bond strength of control groups (Groups 1 and 2) and experimental groups (P < 0.05), but no significant difference in bond strength was observed among the antioxidants used. CONCLUSION: Application of antioxidants immediately after bleaching showed increased bond strength. Green tea and white tea extract can be used as alternative antioxidants in improving the bond strength of enamel.

Rapid flow-induced activation of Gαq/11 is independent of Piezo1 activation.

Endothelial cell (EC) mechanochemical transduction is the process by which mechanical stimuli are sensed by ECs and transduced into biochemical signals and ultimately into physiological responses. Identifying the mechanosensor/mechanochemical transducer(s) and describing the mechanism(s) by which they receive and transmit the signals has remained a central focus within the field. The heterotrimeric G protein, Gαq/11, is proposed to be part of a macromolecular complex together with PECAM-1 at EC junctions and may constitute the mechanochemical transducer as it is rapidly activated within seconds of flow onset. The mechanically activated cation channel Piezo1 has recently been implicated due to its involvement in mediating early responses, such as calcium and ATP release. Here, we investigate the role of Piezo1 in rapid shear stress-induced Gαq/11 activation. We show that flow-induced dissociation of Gαq/11 from PECAM-1 in ECs at 15 s is abrogated by BIM-46187, a selective inhibitor of Gαq/11 activation, suggesting that Gαq/11 activation is required for PECAM-1/Gαq/11 dissociation. Although siRNA knockdown of Piezo1 caused a dramatic decrease in PECAM-1/Gαq/11 association in the basal condition, it had no effect on flow-induced dissociation. Interestingly, siRNA knockdown of Piezo1 caused a marked decrease in PECAM-1 expression. Additionally, selective blockade of Piezo1 with ion channel inhibitors had no effect on flow-induced PECAM-1/Gαq/11 dissociations. Lastly, flow onset caused increased association of Gß1 with Piezo1 as well as with the p101 subunit of phosphoinositide 3-kinase, which were both blocked by the Gßγ inhibitor gallein. Together, our results indicate that flow-induced activation of Piezo1 is not upstream of G protein activation.

Nanopillared Surfaces Disrupt Pseudomonas aeruginosa Mechanoresponsive Upstream Motility.

Pseudomonas aeruginosa is an opportunistic, multidrug-resistant, human pathogen that forms biofilms in environments with fluid flow, such as the lungs of cystic fibrosis patients, industrial pipelines, and medical devices. P. aeruginosa twitches upstream on surfaces by the cyclic extension and retraction of its mechanoresponsive type IV pili motility appendages. The prevention of upstream motility, host invasion, and infectious biofilm formation in fluid flow systems remains an unmet challenge. Here, we describe the design and application of scalable nanopillared surface structures fabricated using nanoimprint lithography that reduce upstream motility and colonization by P. aeruginosa. We used flow channels to induce shear stress typically found in catheter tubes and microscopy analysis to investigate the impact of nanopillared surfaces with different packing fractions on upstream motility trajectory, displacement, velocity, and surface attachment. We found that densely packed, subcellular nanopillared surfaces, with pillar periodicities ranging from 200 to 600 nm and widths ranging from 70 to 215 nm, inhibit the mechanoresponsive upstream motility and surface attachment. This bacteria-nanostructured surface interface effect allows us to tailor surfaces with specific nanopillared geometries for disrupting cell motility and attachment in fluid flow systems.

Inhibition by Ethanol of Shear Stress-Induced Formation of Platelet Thrombi in Whole Blood.

AIMS: The risk of thromboatherosclerotic disease is lower in moderate drinkers than in non-drinkers. We investigated the effects of ethanol on platelet aggregation under a condition with shear stress. SHORT SUMMARY: Shear stress-induced formation of platelet thrombi is inhibited by ethanol at its attainable concentrations after drinking. This effect is prominent at the early stage of thrombus formation, being in agreement with inhibitory actions of ethanol on the initial steps of platelet activation such as Ca2+ entry and phospholipase A2 activation. METHODS: Platelet aggregation was evaluated by using a total thrombus-formation analysis system, and shear rates of 1000 s-1 (low), 1500 s-1 (middle) and 2000 s-1 (high) were loaded to whole blood. The times required to generate increases in flow pressure of 10 kPa (T10), 30 kPa (T30) and 50 kPa (T50) in microchips containing the blood, which depend on the degree of thrombus generation, were recorded. RESULTS: Under the conditions of the low-grade and middle-grade shear rates, T10 and T30 were significantly longer in the presence of ethanol at 0.25-1% than in the absence of ethanol. T10 under the condition of the low-grade shear rate and T30 under the conditions of the low-grade and middle-grade shear rates were also significantly longer in the presence of ethanol at 0.125% than in the absence of ethanol. On the other hand, T50 under the conditions of the low-grade and middle-grade shear rates was not significantly different in the absence and presence of ethanol at 0.125, 0.25 and 0.5%. Under the condition of the high-grade shear rate, T10, T30 and T50 were not significantly different in the absence and presence of ethanol at its lower concentrations. CONCLUSIONS: Ethanol at attainable concentrations inhibits platelet thrombus formation induced by shear stress, and the inhibitory effect of ethanol is prominent at the early stage of thrombus formation.

Impact of Shear History on Powder Flow Characterization Using a Ring Shear Tester.

In this study, we have investigated the impact of repeated shear displacement on powder flow properties. We show that when multiple yield loci are obtained using the same bulk solid specimen by stepping through different stress levels (i.e., stress walk [SW]), the shear deformation of the powder in a rotational shear cell, that is, Schulze Ring Shear Tester, is maximized, reducing the powder shear strength. This approach is material and time sparing; however, it imprecisely predicts better powder flowability. The magnitude of the change in the unconfined yield strength, σc, due to this prolonged shear displacement appears to be material-dependent, being less impactful for free-flowing powders. Using the SW and the individual yield loci-generated flow properties, we have demonstrated that in hopper design, the shear displacement effect impacts the computed critical arching diameter more than the critical mass flow angle. This knowledge of powder flow properties highlights limitations associated with the SW. An exponential function was found to describe the relationship between the change in σc at the highest major principal stress and the density weighted flowability, ffρ, with an R2 of 0.98. Such a model could be a valuable tool for correcting shear strength results obtained from SW, saving time, and material.

Effects of an Antioxidant on the Shear Bond Strengths of Orthodontic Brackets After Conventional and Laser-Assisted Extra-Coronal Bleaching / Efecto de un antioxidante sobre la fuerza de unión de brackets de ortodoncia posterior al blanqueamiento convencional y asistido por láser

RESUMEN El objetivo del presente estudio fue evaluar los efectos de la aplicación de un antioxidante sobre las fuerzas de unión (SBS) de brackets de ortodoncia posterior al blanqueamiento con peróxido de hidrógeno (HP). Metodología: Cincuenta premolares recién extraídos se dividieron aleatoriamente en tres grupos. El Grupo 1 se trató con 40% de HP (n=20), el grupo 2 con 40% de HP y se activó con láser de Nd: YAG (n=20) y un grupo de control (Grupo 3) no recibió tratamiento (n=10). Después del blanqueamiento, los Grupos 1 y 2 se dividieron en dos subgrupos (Grupo 1a, Grupo 1b, Grupo 2a y Grupo 2b). Las muestras en los subgrupos 1a y 2a (n=10) no recibieron ninguna aplicación del antioxidante. Se aplicó una solución de ascorbato de sodio al 10% a las muestras en los Grupos 1b y 2b (n=10). Luego, los brackets se adherieron a las superficies de esmalte de todos los grupos experimentales. Las muestras se sometieron a pruebas de SBS y los datos analizados estadisticamente. Resultados: La fuerza de unión de los grupos 1 y 2 fue significativamente más baja que el grupo de control (p <0.001); sin embargo, no se observaron diferencias estadísticamente significativas en SBS entre los grupos 1 y 2 (p>0.001). Las muestras tratadas con antioxidantes de los grupos 1b y 2b fueron significativamente mayores que las de los grupos 1a y 2a (p <0,001). Conclusion: La aplicación de 40% HP tuvo un efecto negativo en la resistencia de unión de los brackets. El uso de antioxidante durante 15 minutos mejoró significativamente la SBS.

ABSTRACT Purpose: The purpose of this study was to evaluate the effects of the application of antioxidant on the shear bond strengths (SBS) of orthodontic brackets bonded to human enamel after extra-coronal bleaching with hydrogen peroxide (HP). Materials and methods: Fifty freshly extracted premolars were randomly divided into three groups. One group (Group 1) was bleached with 40% HP (n=20), another group (Group 2) was bleached with 40% HP and activated with an Nd: YAG laser (n=20), and a control group (Group 3) received no treatment (n=10). After the bleaching procedure, Groups 1 and 2 were further divided into two subgroups (Group 1a, Group 1b, Group 2a, and Group 2b). Specimens in Groups 1a and 2a (n=10) received no antioxidant application. A 10% sodium ascorbate solution was applied to specimens in Groups 1b and 2b (n=10). The brackets were then bonded with light-cure adhesive paste to the enamel surfaces of all experimental groups. Specimens were subjected to SBS tests for debonding. Results: The SBS of brackets bonded in Groups 1 and 2 were significantly lower than those of brackets bonded to the control group (p<0.001); however, no statistically significant differences in SBS were noted in Groups 1 and 2 (p>0.001). The antioxidant-treated SBS of brackets in Groups 1b and 2b were significantly higher than those of Groups 1a and 2a (p<0.001). Conclusions: The application of 40% HP had a negative effect on the bond strength. The use of antioxidant for 15 min resulted in the reversal of failed bond strength.

Effect of mangosteen peel extract as an antioxidant agent on the shear bond strength of orthodontic brackets bonded to bleached teeth.

INTRODUCTION: The number of patients who seek orthodontic treatment that may have a history of tooth bleaching is increasing over the time. Bleaching may influence the decrease of the bond strength of orthodontic brackets. OBJECTIVE: To determine and prove the effect of mangosteen peel (MP) extract to reverse the reduced shear bond strength (SBS) of orthodontic brackets after bleaching. METHODS: A total of 150 maxillary first premolar teeth were randomly divided into 6 experimental groups as follow (n=25): negative-control (N: no bleaching), positive-control (P: bleaching + no treatment), and the treatment groups (bleaching + 10% sodium ascorbate (SA), 10% (MP-10), 20% (MP-20) and 40% (MP-40) MP extract gel). After treatment, the brackets were bonded with the resin-modified glass ionomer cement, SBS testing was performed using universal testing machine, and the adhesive remnant index (ARI) was examined using stereoscopic microscope after debonding. The SBS data were analyzed by analysis of variance (Anova) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. RESULT: There was significant SBS difference (p< 0.001) between various groups. The group without bleaching showed significantly higher SBS (8.19 ± 2.26 MPa) compared to others, while SBS in the group treated with 40% MP gel was significantly higher (7.93 ± 1.92 MPa) than other groups treated with antioxidants. The failure of orthodontic brackets bonded after bleaching and treatment using MP extract occurred at the enamel-adhesive interface. CONCLUSION: The application of MP extract as an antioxidant after bleaching was effective in reversing the reduced shear bond strength of orthodontic brackets after bleaching.

A comparison of the effect of application of sodium ascorbate and amla (Indian gooseberry) extract on the bond strength of brackets bonded to bleached human enamel: An In vitro study.

INTRODUCTION: Whitening of teeth is a popular choice among dental clinicians and patients. However, the changes in enamel structure and composition induced by the bleaching agents cause a decrease in the shear bond strength of brackets leading to premature bracket debonding. Among several methods to overcome this, the most common is delaying bonding by 2-4 weeks. This waiting period can be eliminated by applying an antioxidant (sodium ascorbate) which causes a reversal in the reduction of bond strength. AIM: This study aims to compare the efficacy of a naturally occurring antioxidant (gooseberry) and sodium ascorbate in normalizing the bond strength of enamel to prebleached levels. MATERIALS AND METHODS: Seventy-two extracted premolars were divided into 4 equal groups; 1st group - control group - unbleached teeth, bonded directly, 2nd group - bleached with 16% carbamide peroxide (8 h for 1 week), then bonded. 3rd and 4th group - similarly bleached, followed by application of 10% sodium ascorbate and gooseberry extract (3 h respectively), then bonded. Bond strength was checked using Instron Universal Testing Machine. RESULTS: The bond strength of the control group was the highest and that of the carbamide group was drastically reduced. Considerable increase in the bond strength was seen after treatment with sodium ascorbate with negligible difference between sodium ascorbate and control group (P > 0.05). CONCLUSION: Treatment with gooseberry extract did improve the bond strength but was not as effective as sodium ascorbate postbleaching.

Fluid shear stress sensing in vascular homeostasis and remodeling: Towards the development of innovative pharmacological approaches to treat vascular dysfunction.

Blood circulation, facilitating gas exchange and nutrient transportation, is a quintessential feature of life in vertebrates. Any disruption to blood flow, may it be by blockade or traumatic rupture, irrevocably leads to tissue infarction or death. Therefore, it is not surprising that hemostasis and vascular adaptation measures have been evolutionarily selected to mitigate the adverse consequences of altered circulation. Blood vessels can be broadly categorized as arteries, veins, or capillaries, based on their structure, hemodynamics, and gas exchange. However, all of them share one property: they are lined with an epithelial sheet called the endothelium, which typically lies on a basement membrane. This endothelium is the primary interface between the flowing blood and the rest of the body, and it has highly specialized molecular mechanisms to detect and respond to changes in blood perfusion. The purpose of this commentary will be to highlight some of the recent developments in the research on blood flow sensing, vascular remodeling, and homeostasis and to discuss the development of innovative pharmaceutical approaches targeting mechanosensing mechanisms to prolong patient survival and improve quality of life.