New Insights into Wnt-Lrp5/6-β-Catenin Signaling in Mechanotransduction

Mechanical loading is essential to maintain normal bone metabolism and the balance between bone formation and resorption. The cellular mechanisms that control mechanotransduction are not fully defined, but several key pathways have been identified. We discuss the roles of several components of the Wnt signaling cascade, namely Lrp5, Lrp6, and β-catenin in mechanical loading-induced bone formation. Lrp5 is an important Wnt co-receptor for regulating bone mass and mechanotransduction, and appears to function principally by augmenting bone formation. Lrp6 also regulates bone mass but its action might involve resorption as well as formation. The role of Lrp6 in mechanotransduction is unclear. Studies addressing the role of β-catenin in bone metabolism and mechanotransduction highlight the uncertainties in downstream modulators of Lrp5 and Lrp6. Taken together, these data indicate that mechanical loading might affect bone regulation triggering the canonical Wnt signaling (and perhaps other pathways) not only via Lrp5 but also via Lrp6. Further work is needed to clarify the role of the Wnt signaling pathway in Lrp5 and/or Lrp6-mediated mechanotransduction, which could eventually lead to powerful therapeutic agents that might mimic the anabolic effects of mechanical stimulation

ANONYMITY AND PERCEIVED NETWORK-STRUCTURE: A MODEL OF VIRTUAL COMMUNITY KNOWLEDGE INTENTIONS

This study investigates the underlying motivational factors with regard to the knowledge exchange intentions (intention to obtain and provide knowledge) in virtual community contexts. Perceived virtual network structure, namely, virtual network connectivity and virtual network closeness are suggested as the important antecedents of knowledge sharing intentions in the context of virtual knowledge exchange community. Anonymity, one of the unique characteristics of virtual community but controversial due to its multi-facet effects, is considered in a structural model as a factor having impacts on a virtual network structure

Postnatal β-catenin deletion from Dmp1-expressing osteocytes/osteoblasts reduces structural adaptation to loading, but not periosteal load-induced bone formation

Mechanical signal transduction in bone tissue begins with load-induced activation of several cellular pathways in the osteocyte population. A key pathway that participates in mechanotransduction is Wnt/Lrp5 signaling. A putative downstream mediator of activated Lrp5 is the nucleocytoplasmic shuttling protein β-catenin (βcat), which migrates to the nucleus where it functions as a transcriptional co-activator. We investigated whether osteocytic βcat participates in Wnt/Lrp5-mediated mechanotransduction by conducting ulnar loading experiments in mice with or without chemically induced βcat deletion in osteocytes. Mice harboring βcat floxed loss-of-function alleles (βcat(f/f)) were bred to the inducible osteocyte Cre transgenic (10)(kb)Dmp1-CreERt2. Adult male mice were induced to recombine the βcat alleles using tamoxifen, and intermittent ulnar loading sessions were applied over the following week. Although adult-onset deletion of βcat from Dmp1-expressing cells reduced skeletal mass, the bone tissue was responsive to mechanical stimulation as indicated by increased relative periosteal bone formation rates in recombined mice. However, load-induced improvements in cross sectional geometric properties were compromised in recombined mice. The collective results indicate that the osteoanabolic response to loading can occur on the periosteal surface when β-cat levels are significantly reduced in Dmp1-expressing cells, suggesting that either (i) only low levels of β-cat are required for mechanically induced bone formation on the periosteal surface, or (ii) other additional downstream mediators of Lrp5 might participate in transducing load-induced Wnt signaling

Exploring Satisfaction with and Trust in Social Networking Sites through the Lens of Fan Pages: Uncertainty Reduction and General Systems Theory Perspective

The purpose of this study is to examine social networking sites (SNS) users’ overall satisfaction with and trust in SNS, as related to their activities of visiting fan pages. We employ two theories—uncertainty reduction theory (URT) and general systems theory (GST)—to examine antecedents affecting overall satisfaction with and trust in SNS. Using a web-based survey, we analyzed 200 SNS users who follow at least one company’s fan page, and utilized seemingly unrelated regression (SUR) models to empirically test our hypotheses. Our findings indicate that uncertainty reduction strategies supported by URT are significantly associated with perceived usefulness of companies’ posts in their fan pages. In turn, perceived usefulness of those posts promotes more visits to the fan page. Finally, users’ perceived usefulness of fan page posts eventually accounts for the overall satisfaction with and trust in SNS. The implications and limitations are discussed at the end of this study

Small-cell neuroendocrine carcinoma of the breast

A small-cell carcinoma is one of the histologic subtypes of primary neuroendocrine carcinomas of the breast. A small-cell carcinoma is a rare entity of the breast and exhibits similar morphologic features as neuroendocrine tumors of the gastrointestinal tract and lung. We present the imaging and pathologic findings of a primary small-cell neuroendocrine carcinoma of the breast. This is the first report of a primary small-cell carcinoma arising from the breast in Korea

Multi-Color Luminescence Transition of Upconversion Nanocrystals via Crystal Phase Control with SiO2 for High Temperature Thermal Labels

Upconversion nanocrystals (UCNs)-embedded microarchitectures with luminescence color transition capability and enhanced luminescence intensity under extreme conditions are suitable for developing a robust labeling system in a high-temperature thermal industrial process. However, most UCNs based labeling systems are limited by the loss of luminescence owing to the destruction of the crystalline phase or by a predetermined luminescence color without color transition capability. Herein, an unusual crystal phase transition of UCNs to a hexagonal apatite phase in the presence of SiO2 nanoparticles is reported with the enhancements of 130-fold green luminescence and 52-fold luminance as compared to that of the SiO2-free counterpart. By rationally combining this strategy with an additive color mixing method using a mask-less flow lithography technique, single to multiple luminescence color transition, scalable labeling systems with hidden letters-, and multi-luminescence colored microparticles are demonstrated for a UCNs luminescence color change-based high temperature labeling system

Long-term outcome of patients with p22-deficient chronic granulomatous disease on Jeju Island, Korea

PurposeThis study investigated the long-term clinical outcomes of patients with p22phox-deficient chronic granulomatous disease (CGD) on Jeju Island and retrospectively evaluated the effects of interferon-gamma (IFN-γ) prophylaxis.MethodsThe medical records of 15 patients with CGD were retrospectively reviewed. The efficacy of IFN-γ prophylaxis was evaluated by comparing the frequency of severe infections before and after starting continuous prophylaxis with IFN-γ.ResultsAt the time of the analysis, 14 patients were alive, with a median age of 14.3 years. The diagnosis of CGD was made at a median age of 2.4 years, and the median age at onset of severe infection was 0.3 years. Thirteen of the 15 patients had their first severe infection within the first year of life. The overall incidence of severe infection was 1.36 infections per patient-year; pneumonia, suppurative lymphadenitis, and skin and subcutaneous abscesses were the most common infections. Aspergillus species were the most frequently isolated microorganisms, present in 15.8% of isolates. IFN-γ did not significantly change the rate of severe infection. The survival rate for patients after 2 years of age was 93%; there was a prolonged survival plateau beyond the age of 2.ConclusionCompared with cases of X-linked CGD reported in other studies, patients with CGD on Jeju Island did not show obviously different clinical manifestations, but they had a significantly higher survival rate. Further studies with a substantially longer period of observation, and with more patients under intensive surveillance are necessary to elucidate the prophylactic efficiency of IFN-γ

Successful Salvage Unrelated Umbilical Cord Blood Transplantation with Two Units After Engraftment Failure with Single Unit in Severe Aplastic Anemia

Severe aplastic anemia (SAA) patients without an HLA-matched sibling donor need alternative treatment options. Umbilical cord blood transplantation (UCBT) has become an alternative means for treating various diseases, but it has not been proved to be a satisfactory method to treat SAA. Here, we report the case of a girl who underwent successful two-unit UCBT after engraftment failure with a single unit. Two-unit UCBT is proposed to have better engraftment potential and to offer a better chance of survival, according to some reports. Increased cell dose and graft-versus-graft reaction could contribute to these advantages. With this promising result, two-unit UCBT could be an alternative treatment option for patients with SAA without an HLA-matched donor