Pivotal roles of shear stress in the microenvironmental changes that occur within sentinel lymph nodes

A sentinel lymph node (SLN) is the first lymph node that receives drainage from a primary tumor. According to their physiological and biomechanical characteristics, we hypothesized that SLN contains lymphatic endothelial cells (LEC) that are constantly loaded with high levels of shear stress, which might contribute to the production of a suitable environment for micrometastasis within them. To test this hypothesis, we investigated the effects of shear stress stimulation on the expression of adhesion molecules on human LEC isolated from the lymph vessels nearest the SLN of breast cancers, and on the release of ATP from human LEC. The study clarified that the shear stress stimulation produced a significant increase of ICAM-1 expression at protein and mRNA levels in human LEC. Next, we examined whether the shear stress-mediated increase of ICAM-1 expression accelerates the attachment of carcinoma cells to human LEC. Finally, in in vivo experiments, we evaluated whether exogenous ATP facilitates the expression of carcinoma cell-ligated adhesion molecules in rat SLN. In conclusion, shear stress stimulation induces ICAM-1 expression on human LEC by activating cell surface F1/FO ATP synthase, which might contribute to the development of a premetastatic environment within SLN. (Cancer Sci 2012; 103: 12451252)ArticleCANCER SCIENCE. 103(7):1245-1252 (2012)journal articl

Real-time imaging of the lymphatic channels and sentinel lymph nodes of the stomach using contrast-enhanced ultrasonography with Sonazoid in a porcine model

The contrast-enhanced ultrasound (CEUS)-guided method in combination with Sonazoid has not been clinically or experimentally evaluated with regard to its use for identifying sentinel lymph node (SLN) in the stomach. Therefore, we attempted to evaluate the usefulness of the CEUS-guided method with Sonazoid for imaging of the lymphatic channels and SLN of the stomach in a porcine model by comparing it with the conventional Evans blue dye-guided method. Twenty-eight 2 to 3-month-old swine weighing 17-30 kg were used in this experiment. Anesthesia was maintained with 2.0-3.0% isoflurane/O(2) inhalation. Sonazoid was injected into the intra-and sub-mucosal layers of the stomach. The intragastric or transcutaneous CEUS-guided method was used to identify the lymphatic channels and SLN of the stomach. Contrast imaging using the CEUS-guided method with Sonazoid enabled us to produce clear images of the afferent lymph vessel and SLN of the stomach until 2 h after the injection of Sonazoid. In addition, intranodal flow of the microbubble agent could be clearly identified using tissue linear harmonic images of the SLN. The SLN detection rate was not significantly different between the CEUS- and dye-guided methods. However, the Evans blue dye flowed out quickly (similar to 15 min after the injection) through the true SLN into the next LN of stomach. In conclusion, the use of the CEUS-guided method with Sonazoid might be the most useful clinical procedure for producing real-time images of the SLN of the stomach, and the linear harmonic images are also useful for evaluating intranodal structure within the SLN. (Cancer Sci 2011; 102: 2073-2081)ArticleCANCER SCIENCE. 102(11):2073-2081 (2011)journal articl

Real-time TIRF observation of vinculin recruitment to stretched α-catenin by AFM

Adherens junctions (AJs) adaptively change their intensities in response to intercellular tension; therefore, they integrate tension generated by individual cells to drive multicellular dynamics, such as morphogenetic change in embryos. Under intercellular tension, α-catenin, which is a component protein of AJs, acts as a mechano-chemical transducer to recruit vinculin to promote actin remodeling. Although in vivo and in vitro studies have suggested that α-catenin-mediated mechanotransduction is a dynamic molecular process, which involves a conformational change of α-catenin under tension to expose a cryptic vinculin binding site, there are no suitable experimental methods to directly explore the process. Therefore, in this study, we developed a novel system by combining atomic force microscopy (AFM) and total internal reflection fluorescence (TIRF). In this system, α-catenin molecules (residues 276–634; the mechano-sensitive M1-M3 domain), modified on coverslips, were stretched by AFM and their recruitment of Alexa-labeled full-length vinculin molecules, dissolved in solution, were observed simultaneously, in real time, using TIRF. We applied a physiologically possible range of tensions and extensions to α-catenin and directly observed its vinculin recruitment. Our new system could be used in the fields of mechanobiology and biophysics to explore functions of proteins under tension by coupling biomechanical and biochemical information

Effects of Fipronil on Non-target Ants and Other Invertebrates in a Program for Eradication of the Argentine Ant, Linepithema humile

Pesticides are frequently used to eradicate invasive ant species, but pose ecological harm. Previous studies assessed non-target effects only in terms of the increase or decrease of abundance or species richness after pesticide applications. Positive effects of the release from pressure caused by invasive ant species have not been considered so far. To more accurately assess pesticide effects in the field, the non-target effects of pesticides should be considered separately from the positive effects of such releases. Here, we used monitoring data of ants and other invertebrates collected in a program for the eradication of the Argentine ant, Linepithema humile (Mayr), using fipronil. First, we separately assessed the effects of L. humile abundance and fipronil exposure on non-target ants and other invertebrates using generalized linear models. The abundance of L. humile and the number of pesticide treatments were negatively associated with the total number of non-target individuals and taxonomic richness. We also noted negative relationships between the number of individuals of some ant species and other invertebrate taxonomic groups. The L. humile × pesticide interaction was significant, suggesting that the abundance of L. humile affected the level of impact of pesticide treatment on non-target fauna. Second, we evaluated the dynamics of non-target ant communities for 3 years using principal response curve analyses. Non-target ant communities treated with fipronil continuously for 3 years recovered little, whereas those treated for 1 year recovered to the level of the untreated and non-invaded environment

Symmetrical Skin Lesions on the Gluteal Region in a Patient with Anti-Laminin-332 Mucous Membrane Pemphigoid

Mucous membrane pemphigoid (MMP), previously called cicatricial pemphigoid, is a rare subepidermal immunobullous disorder that primarily affects the mucous membranes (1,2). MMP is divided into two major subtypes, anti-BP180-type MMP and anti-laminin-332 (previously called laminin 5 or epiligrin) MMP. Anti-laminin-332 MMP is known to be associated with malignant tumors (3), which may cause overexpression of autoantibodies and induce autoimmunity to laminin-332 (4). MMP primarily affects the mucous membranes, and widespread skin lesions are rare. In MMP, circumscribed skin lesions have been previously reported as occurring on the head, neck, and upper trunk (5). We report a case of anti-laminin-332 MMP presenting with symmetrical skin lesions characteristic of MMP on the weightbearing areas of the gluteal regio

Symmetrical Skin Lesions on the Gluteal Region in a Patient with Anti-Laminin-332 Mucous Membrane Pemphigoid

Mucous membrane pemphigoid (MMP), previously called cicatricial pemphigoid, is a rare subepidermal immunobullous disorder that primarily affects the mucous membranes (1,2). MMP is divided into two major subtypes, anti-BP180-type MMP and anti-laminin-332 (previously called laminin 5 or epiligrin) MMP. Anti-laminin-332 MMP is known to be associated with malignant tumors (3), which may cause overexpression of autoantibodies and induce autoimmunity to laminin-332 (4). MMP primarily affects the mucous membranes, and widespread skin lesions are rare. In MMP, circumscribed skin lesions have been previously reported as occurring on the head, neck, and upper trunk (5). We report a case of anti-laminin-332 MMP presenting with symmetrical skin lesions characteristic of MMP on the weightbearing areas of the gluteal regio

Mechano-adaptive sensory mechanism of α-catenin under tension

The contractile forces in individual cells drive the tissue processes, such as morphogenesis and wound healing, and maintain tissue integrity. In these processes, α-catenin molecule acts as a tension sensor at cadherin-based adherens junctions (AJs), accelerating the positive feedback of intercellular tension. Under tension, α-catenin is activated to recruit vinculin, which recruits actin filaments to AJs. In this study, we revealed how α-catenin retains its activated state while avoiding unfolding under tension. Using single-molecule force spectroscopy employing atomic force microscopy (AFM), we found that mechanically activated α-catenin fragment had higher mechanical stability than a non-activated fragment. The results of our experiments using mutated and segmented fragments showed that the key intramolecular interactions acted as a conformational switch. We also found that the conformation of α-catenin was reinforced by vinculin binding. We demonstrate that α-catenin adaptively changes its conformation under tension to a stable intermediate state, binds to vinculin, and finally settles into a more stable state reinforced by vinculin binding. Our data suggest that the plastic characteristics of α-catenin, revealed in response to both mechanical and biochemical cues, enable the functional-structural dynamics at the cellular and tissue levels