Airway epithelial cells initiate the allergen response through transglutaminase 2 by inducing IL-33 expression and a subsequent Th2 response

Transglutaminase 2 (TG2) is a post-translational protein-modifying enzyme that catalyzes the transamidation reaction, producing crosslinked or polyaminated proteins. Increased TG2 expression and activity have been reported in various inflammatory conditions, such as rheumatoid arthritis, inflammation-associated pulmonary fibrosis, and autoimmune encephalitis. In particular, TG2 from epithelial cells is important during the initial inflammatory response in the lung. In this study, we evaluated the role of TG2 in the pathogenesis of allergic asthma, particularly whether TG2 affects initial activation signaling leading to Th2 differentiation against antigens. Methods We induced allergic asthma by ovalbumin sensitization and intranasal challenge in wild-type (WT) BALB/c and TG2-deficient mice. Broncheoalveolar lavage fluid cells and intracellular cytokine production were analyzed by flow cytometry. Interleukin (IL)-33 and TG2 expression in lung epithelial cells was detected by confocal microscopy. Results Airway responsiveness was attenuated in TG2-deficient mice compared to that in the WT control. In addition, recruitment of eosinophils and Th2 and Th17 differentiation decreased in TG2-deficient mice. Treatment with cysteamine, a transglutaminase inhibitor, also reduced airway hypersensitivity, inflammatory cell recruitment, and T helper cell differentiation. TG2-deficient mice showed reduced IL-33 expression following induction of allergic asthma compared to those in the WT control. Conclusions We found that pulmonary epithelial cells damaged by allergens triggered TG2-mediated IL-33 expression leading to type 2 responses by recruiting both innate and adaptive arms of the immune system.Peer Reviewe

Effect of Temperature on the Modal Variability in Short-Span Concrete Bridges

The dynamic characteristics of bridges are known to be affected by damages as well as by environmental factors such as temperature. Therefore, the changes in the dynamic characteristics caused by damages and environmental factors should be considered when evaluating the health of the structure. Accordingly, this study conducted long-term monitoring and modal identification of short-span concrete bridges, i.e., a RC (reinforced concrete) slab bridge a RC rahmen (rigid-frame) bridge. The investigation revealed that temperature is the factor having the greatest influence on the variability of the dynamic characteristics as the natural frequencies of the bridge decrease with higher temperatures. Model updating verified that such modal change resulted from the temperature dependency of the elastic modulus of concrete. The RC slab bridge showed higher temperature dependency than the RC rahmen bridge owing to the presence of elastomeric bearings. Apart from the effect of temperature, non-negligible modal changes caused by other environmental factors were also identified. The results of this study are expected to provide valuable data for the health evaluation of bridges

Model Updating Using Measurements from Sensors Installed in Arbitrary Positions and Directions

The present study proposes a method for model updating using measurements from sensors installed in arbitrary positions and directions. Modal identification provides mode shapes for physical quantities (acceleration strain, etc.) measured in specific directions at the location of the sensors. Besides, model updating involves the use of the mode shapes related to the nodal degrees-of-freedom of the finite element analytic model. Consequently, the mode shapes obtained by modal identification and the mode shapes of the model updating process do not coincide even for the same mode. Therefore, a method for constructing transform matrices that distinguish the cases where measurement is done by acceleration, velocity, and displacement sensors and the case where measurement is done by strain sensors was proposed to remedy such disagreement among the mode shapes. The so-constructed transform matrices were then applied when the mode shape residual was used as the objective function or for mode pairing in the model updating process. The feasibility of the proposed approach was verified by means of a numerical example in which the strain or acceleration of a simple beam was measured and a numerical example in which the strain of a bridge was measured. Using the proposed approach, it was possible to model the structure regardless of the position of the sensors and to select the location of the sensors independently from the model

A Sensor-Type PC Strand with an Embedded FBG Sensor for Monitoring Prestress Forces

Prestressed Concrete Wire and Strand (PC) strands are the most used materials to introduce prestress in a Pre-Stressed Concrete (PSC) structure. However, it is difficult to evaluate the final prestress force of the PC strand after prestressing or its residual prestress force after completion of the structure on site. This impossibility to assess eventual loss of prestress of the PC strand has resulted in a number of serious accidents and even in the collapse of several structures. This situation stresses the necessity to maintain the prestress force residual or after prestressing for the evaluation of the health of the concrete structure throughout its lifespan. Recently, several researchers have studied methods enabling one to verify the prestress force by inserting an optical fiber sensor inside the strand but failed to provide simple techniques for the fabrication of these devices to fulfill measurement performance from the design prestress to failure. Moreover, these methods require the additional installation of electrical resistance strain gages, displacement sensors and load cells on the outer surface of the structure for long-term precise measurement. This paper proposes a method enabling one to evaluate precisely and effectively the prestress force of the PC strand and intends to verify the applicability of the proposed method on actual concrete structures. To that end, an innovative PC strand is developed by embedding a Fiber Bragg Grating (FBG) sensor in the core wire of the PC strand so as to enable short term as well as long term monitoring. The measurement performance of the developed strand is then evaluated experimentally and the reliability of the monitoring data is assessed

Analytical Model of Nonlinear Stress-Strain Relation for a Strand Made of Two Materials

Unlike conventional steel strands, the smart strand supports strain-measuring function and adopts different materials for its core wire and helical wires. This study intends to analytically derive the nonlinear stress-strain model of this strand made of two materials. The effect of the bending moment and torsional moment of the helical wires on the overall load within the range of geometric shapes shown by actually used strands is verified to be negligible and is thus ignored in order to simplify the analytical model. Moreover, the slight difference between the actual and analytic behaviors, which only appears in the slope varying part in the case of bilinear behavior, such as that of steel, is also ignored. The proposed constitutive model of the smart strand obtained by introducing the experimental stress-strain relation between the carbon fiber reinforced polymer core wire and the helical steel wires is in good agreement with the experimental data. The previous analytical models are applicable only to strands made of a unique linear material, whereas the model proposed in this study is also applicable to strands in which the core wire and the helical wires are made of two different materials, exhibiting nonlinear behavior

Estimation of Tendon Force Distribution in Prestressed Concrete Girders Using Smart Strand

The recently developed smart strand offers the possibility of measuring the prestress force of the tendon from jacking and all along its service life. In the present study, a method estimating the force distribution in all the tendons of a prestressed concrete (PSC) girder installed with one smart strand is proposed. The force distribution in the prestressed tendons is formulated by the friction and the anchorage slip, and is obtained through an optimization process with respect to the compatibility conditions and equilibrium of the forces in the section of the PSC girder. The validation of the proposed method through a numerical example and experiment shows that it can be used to estimate the force developed in the tendon

Estimation of Prestress Force Distribution in the Multi-Strand System of Prestressed Concrete Structures

Prestressed concrete (PSC) is one of the most reliable, durable and widely used construction materials, which overcomes the weakness of concrete in tension by the introduction of a prestress force. Smart strands enabling measurement of the prestress force have recently been developed to maintain PSC structures throughout their lifetime. However, the smart strand cannot give a representative indication of the whole prestress force when used in multi-strand systems since each strand sustains a different prestress force. In this paper, the actual distribution of the prestress force in a multi-strand system is examined using elastomagnetic (EM) sensors to develop a method for tracking representative indicators of the prestress force using smart strands

Numerical and Experimental Analysis of the Shear Behavior of Ultrahigh-Performance Concrete Construction Joints

Shear performance of plain UHPC (ultrahigh-performance concrete) construction joints is studied in both experimental and analytical ways. In push-off tests, three different contact surfaces of the construction joint were considered, while the case without any joint was provided for the reference. Test results indicate that the geometry of contact surfaces greatly affects shear performance of the construction joint. With simplifying structural behavior of contact surfaces and UHPC substrate, the finite-element analysis model is developed for every case studied by utilizing the ABAQUS software and validated against the test results. Agreement between experimental and numerical simulation results is excellent especially in terms of displacement, strength, and failure mechanism. It is expected that the present work provides a basis for further study on reinforced UHPC construction joints