Zebrafish teeth as a model for repetitive epithelial morphogenesis: dynamics of E-cadherin expression

Background: The development of teeth is the result of interactions between competent mesenchyme and epithelium, both of which undergo extensive morphogenesis. The importance of cell adhesion molecules in morphogenesis has long been acknowledged but remarkably few studies have focused on the distribution and function of these molecules in tooth development. Results: We analyzed the expression pattern of an important epithelial cadherin, E-cadherin, during the formation of first-generation teeth as well as replacement teeth in the zebrafish, using in situ hybridization and whole mount immunostaining to reveal mRNA expression and protein distribution. E-cadherin was detected in every layer of the enamel organ during the different stages of tooth development, but there were slight differences between first-generation and replacement teeth in the strength and distribution of the signal. The dental papilla, which is derived from the mesenchyme, did not show any expression. Remarkably, the crypts surrounding the functional teeth showed an uneven distribution of E-cadherin throughout the pharyngeal region. Conclusions: The slight differences between E-cadherin expression in zebrafish teeth and developing mouse and human teeth are discussed in the light of fundamental differences in structural and developmental features of the dentition between zebrafish and mammals. Importantly, the uninterrupted expression of E-cadherin indicates that down-regulation of E-cadherin is not required for formation of an epithelial tooth bud. Further research is needed to understand the role of other cell adhesion systems during the development of teeth and the formation of replacement teeth

Age Estimation of Fetal Skeletal Remains from the Forensic Context

This study tested the efficacy of the traditional method (Fazekas and Kosa, 1978) of aging fetal remains from the forensic context against ultrasound (Chevernak et al., 1998)and radiographic (Sherwood et al., 2000) methods to determine which was most accurate. Two data sets were used in this study. The first consisted of measurements from historic (1902-1917) fetal remains of known age. The second consisted of measurements from modern fetal remains of known age from the forensic context. Using these samples in the different prediction models for aging fetal remains, the accuracy of each was determined

Insights from an Industry Advisory Board about Online Education for Practitioners

Higher education institutions are increasingly using media and Internet for teaching and learning. The 2011 Survey of Online Learning reported that the number of students taking at least one online class was 6.7 million (Allen & Seaman, 2013). Sixty-five percent of higher education organizations perceive online education as a necessary part of their long-term development strategy (Babson Survey Research Group). Moreover, online education not only applies to college students, but also expands to continuing education of industry employees. Increasing technical skill requirements in apparel companies cause employees to need continued training, to keep up with the ever-changing work environment

“You get to know the people and whether they’re talking sense or not”: Negotiating trust on health-related forums

AbstractThe internet is increasingly being used as a source of health advice and information by individuals with long term conditions (LTCs). Specifically, online forums allow people to interact with others with similar conditions. However, it is not clear how online health information is assessed by those with LTCs. This study aims to address this gap by exploring how individuals with contested and uncontested LTCs utilise internet forums. Semi-structured interviews were conducted with 20 participants with ME/CFS and 21 participants with type 1 and 2 diabetes and analysed using thematic analysis. Participants were recruited via online and offline routes, namely forums, email lists, newsletters, and face-to-face support groups. The findings indicate that the use of online forums was a complex and nuanced process and was influenced by a number of individual and illness-specific factors. Participants trusted those with similar experiences and perspectives as themselves, while also valuing conventional biomedical information and advice. By accessing support online, forum users were able to draw on a personalised form of support based on the lived experiences of their peers. However, the role of digital literacy in developing and maintaining online relationships must be acknowledged

Effects of arcing due to spacecraft charging on spacecraft survival

A quantitative assessment of the hazard associated with spacecraft charging and arcing on spacecraft systems is presented. A literature survey on arc discharge thresholds and characteristics was done and gaps in the data and requirements for additional experiments were identified. Calculations of coupling of arc discharges into typical spacecraft systems were made and the susceptibility of typical spacecraft to disruption by arc discharges was investigated. Design guidelines and recommended practices to reduce or eliminate the threat of malfunction and failures due to spacecraft charging/arcing were summarized

Corrigendum: Probiotics Reduce Health Care Cost and Societal Impact of Flu-Like Respiratory Tract Infections in the USA: An Economic Modeling Study.

[This corrects the article DOI: 10.3389/fphar.2019.00980.]

TALEN-mediated apc mutation in Xenopus tropicalis phenocopies familial adenomatous polyposis

Truncating mutations in the tumor suppressor gene adenomatous polyposis coli (APC) are the initiating step in the vast majority of sporadic colorectal cancers, and they underlie familial adenomatous polyposis (FAP) syndromes. Modeling of APC- driven tumor formation in the mouse has contributed substantially to our mechanistic understanding of the associated disease, but additional models are needed to explore therapeutic opportunities and overcome current limitations of mouse models. We report on a novel and penetrant genetic cancer model in Xenopus tropicalis, an aquatic tetrapod vertebrate with external development, diploid genome and short life cycle. Tadpoles and froglets derived from embryos injected with TAL effector nucleases targeting the apc gene rapidly developed intestinal hyperplasia and other neoplasms observed in FAP patients, including desmoid tumors and medulloblastomas. Bi-allelic apc mutations causing frame shifts were detected in the tumors, which displayed activation of the Wnt/β-catenin pathway and showed increased cellular proliferation. We further demonstrate that simultaneous double bi-allelic mutation of apc and a non-relevant gene is possible in the neoplasias, opening the door for identification and characterization of effector or modifier genes in tumors expressing truncated apc. Our results demonstrate the power of modeling human cancer in Xenopus tropicalis using mosaic TALEN-mediated bi-allelic gene disruption