1,720,985 research outputs found
Bone texture modifications during bone regeneration and osteocyte cell-signaling changes in response to treatment with Teriparatide
No full textBone texture modifications during bone regeneration and osteocyte cell-signaling changes in response to treatment with Teriparatid
Understanding the endocrine crosstalk between bone and muscle: molecular investigation of the impact of myokines on osteogenesis using C2C12 myoblast and 2T3 osteoblast cell lines
Full text linkBones and skeletal muscles interact mechanically to allow locomotion in vertebrate and even invertebrate organisms. Until the last decade of research, the interactions between them had been gathered under the umbrella of the “mechanical coupling” theory, where muscles are the load suppliers and bones provide the attachment sites [1]. However, bone and skeletal muscle have recently been identified as endocrine organs, that secrete cytokines and chemokines, through which they interact to promote locomotion. This molecular and biochemical interplay has been named “bone-muscle crosstalk”. The bi-directional flow of signals between bone and muscle has been investigated experimentally by differentiating bone or skeletal muscle progenitor cells in a medium conditioned by myotubes or osteocytes respectively [2][3]. These studies have demonstrated that osteocyte (osteokines) and myotube (myokines) secreted factors have an inhibitory influence on myogenesis and osteogenesis respectively, since they reduce the majority of the mRNA levels of genes associated with differentiation. We propose to study the effects of myokines on osteogenesis by differentiating 2T3 osteoblastic cells in a medium conditioned by either early (3-5 days) or late (7-10 days) myo-tubes. We will then analyze mRNA and protein levels of marker genes of differentia-tion, to establish the effect of early and late patterns of myokines. Besides, we will characterize the differentiation process from a functional point of view by studying alkaline phosphatase activity and the deposition of mineralized matrix. As expected results, early and late myotube-conditioned media should affect differently the osteoblast lineage in the course of differentiation. If this is the case, we will proceed with a metabolomic profiling of the conditioned medium, to identify the cytokines most abundantly expressed. This first set of results will pave the way for further experiments of myoblast and osteoblast co-culture aimed at a real-time tracking of the bi-directional signaling betweeen these tissues and its impact on all stages of differentiation. The results of this study will deepen our understanding of how the muscle secretome protects osteocytes and preserve their function and vice versa how bone factors maintain muscle function. Such knowledge will help identify potential new therapies for bone and muscle diseases, especially when they co-exist, as is the case of the twin syndrome of osteoporosis and sarcopenia
Muscle-to-bone crosstalk: the Wnt/-catenin pathway is a candidate mechanism mediating the signalling between C2C12 muscle cells and 2T3 osteoblasts
No full textThe study aims to determine whether myokines can potentially regulate osteogenesis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Trabecular Bone as Keystone for the Interplay Among Calcium Diet Content, PTH(1-34) Treatment and Balance of Bone Homeostases in Rat Model
No full textThe present study aims to determine whether normal-diet restoration, with/without concomitant PTH(1-34) administration, can influence amounts and
deposition sites of the total bone mass. Histomorphometric evaluations and immunohistochemical analysis for Sclerostin expression were conducted on the vertebral bodies and femurs in the rat model.
Final goals 1) to define timing and manners of bone mass changes when calcium is restored to the diet; 2) to analyze the different involvement of the two bony architectures having different metabolism (i.e. trabecular versus cortical bone); 3) to verify the eventual role of PTH(1-34) administration. Results evidenced the greater involvement of the trabecular bone with respect to the cortical bone, in response to differing levels of calcium content in the diet, and the effect of PTH, mostly in the recovery of trabecular bony architecture.
The main findings emerged are: i) the importance of the interplay between mineral homeostasis and skeletal homeostasis in modulating and guiding bone’s response to dietary/metabolic alterations and ii) the evidence that the more involved bony architecture is trabecular bones, the most susceptible to the dynamical balance of mineral and skeletal homeostasis
Expression and localization of Phosphoinositide-specific Phospholipases C in cultured and differentiating human osteoblasts
Full text linkHomeostasis in the bone tissue primarily depends on the balance of the activities of osteoclasts and osteoblasts, primarily involved in bone formation
and turnover (Zaidi 2007; Khosla et al 2005). Osteoblasts maintain the bone
mass, and intervene in bone injuries repair. The limited number of therapeutic agents able to promote osteogenesis ingenerated great interest addressed
to manipulate the activity of osteoblasts. Insights in the events leading to the
differentiation and proliferation of osteoblasts might allow uncover potential
molecular therapy targets to control the complex mechanisms underlying the
skeletal remodeling (Marie 2015; Kawai et al 2011). Oscillations of calcium
act crucially during the remodeling of bone, affecting both the differentiation
and proliferation of osteoblasts. Signal transduction pathways contribute to
the differentiation and metabolic activities of osteoblasts, with special regard
to calcium-related signaling (Kimple et al 2011, Keinan et al 2014), including
the Phosphoinositide (PI) pathway and related Phospholipases C (PLCs).
In order to evaluate the role of PLC enzymes’ family in human osteoblasts
(HOBs), we analyzed the expression of PLC genes and the localization of
PLC enzymes both in cultured HOBs and in in vitro differentiating HOBs
after 3, 10, 17 and 23 days. Our results confirm the transcription of most PLC
genes and the presence of a number of PLC enzymes in HOBs, differently
localized in the nucleus, in the cytoplasm or both, as well as in cell protrusions. The presence of PLC enzymes within the HOBs suggests the activation
of the PI nuclear cycle in HOBs. Along both the culture and differentiation
culture periods, transcripts of splicing variants of selected PLC genes were
detected and the localization of most PLC enzymes varied, with special regard to enzymes belonging to the PLC , and sub-families. The behavior
of selected PLC enzymes will be discussed more in detail. The presented
results overall suggest that PLC signaling might provide further insights into
the complex signal transduction network in bone remodeling, also representing promising molecular targets
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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