16 research outputs found

    A new finite element based parameter to predict bone fracture

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    Dual Energy X-Ray Absorptiometry (DXA) is currently the most widely adopted non-invasive clinical technique to assess bone mineral density and bone mineral content in human research and represents the primary tool for the diagnosis of osteoporosis. DXA measures areal bone mineral density, BMD, which does not account for the three-dimensional structure of the vertebrae and for the distribution of bone mass. The result is that longitudinal DXA can only predict about 70% of vertebral fractures. This study proposes a complementary tool, based on Finite Element (FE) models, to improve the DXA accuracy. Bone is simulated as elastic and inhomogeneous material, with stiffness distribution derived from DXA greyscale images of density. The numerical procedure simulates a compressive load on each vertebra to evaluate the local minimum principal strain values. From these values, both the local average and the maximum strains are computed over the cross sections and along the height of the analysed bone region, to provide a parameter, named Strain Index of Bone (SIB), which could be considered as a bone fragility index. The procedure is initially validated on 33 cylindrical trabecular bone samples obtained from porcine lumbar vertebrae, experimentally tested under static compressive loading. Comparing the experimental mechanical parameters with the SIB, we could find a higher correlation of the ultimate stress, \u3c3ULT, with the SIB values (R2adj = 0.63) than that observed with the conventional DXA-based clinical parameters, i.e. Bone Mineral Density, BMD (R2adj = 0.34) and Trabecular Bone Score, TBS (R2adj = -0.03). The paper finally presents a few case studies of numerical simulations carried out on human lumbar vertebrae. If our results are confirmed in prospective studies, SIB could be used-together with BMD and TBS-to improve the fracture risk assessment and support the clinical decision to assume specific drugs for metabolic bone diseases

    OCT4 and the acquisition of oocyte developmental competence during folliculogenesis

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    The role that the transcription factor OCT4 plays during oocyte growth is yet unknown. In this review, we summarise the data on its potential role in the acquisition of oocyte developmental competence in the mouse. These studies describe the presence in MII oocytes and 2-cell embryos of an OCT4 transcriptional network that might be part of the molecular signature of maternal origin on which the inner cell mass and the embryonic stem cell-associated pluripotency is assembled and shaped. The Oct4-gene regulatory network thus provides a connection between eggs, early preimplantation embryos and embryonic stem cells

    Exploring Wound-Healing Genomic Machinery with a Network-Based Approach

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    The molecular mechanisms underlying tissue regeneration and wound healing are still poorly understood despite their importance. In this paper we develop a bioinformatics approach, combining biology and network theory to drive experiments for better understanding the genetic underpinnings of wound healing mechanisms and for selecting potential drug targets. We start by selecting literature-relevant genes in murine wound healing, and inferring from them a Protein-Protein Interaction (PPI) network. Then, we analyze the network to rank wound healing-related genes according to their topological properties. Lastly, we perform a procedure for in-silico simulation of a treatment action in a biological pathway. The findings obtained by applying the developed pipeline, including gene expression analysis, confirms how a network-based bioinformatics method is able to prioritize candidate genes for in vitro analysis, thus speeding up the understanding of molecular mechanisms and supporting the discovery of potential drug targets.grant of NATO ("RAWINTS": RApid Skin Wound healing by INtegrated Tissue engineering and Sensing) [G-984961]Open Access Journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

    Exploring Wound-Healing Genomic Machinery with a Network-Based Approach

    Get PDF
    The molecular mechanisms underlying tissue regeneration and wound healing are still poorly understood despite their importance. In this paper we develop a bioinformatics approach, combining biology and network theory to drive experiments for better understanding the genetic underpinnings of wound healing mechanisms and for selecting potential drug targets. We start by selecting literature-relevant genes in murine wound healing, and inferring from them a Protein-Protein Interaction (PPI) network. Then, we analyze the network to rank wound healing-related genes according to their topological properties. Lastly, we perform a procedure for in-silico simulation of a treatment action in a biological pathway. The findings obtained by applying the developed pipeline, including gene expression analysis, confirms how a network-based bioinformatics method is able to prioritize candidate genes for in vitro analysis, thus speeding up the understanding of molecular mechanisms and supporting the discovery of potential drug targets.status: publishe

    Amh transcript: a non-invasive cumulus cells marker of the oocyte developmental competence

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    In the field of assisted reproductive technologies (ARTs) there is a growing need to identify non-invasive markers of the oocyte quality. To this end, a number of studies have screened various molecules and morphological characteristics, but reached contrasting and yet not widely accepted results. This study aims at identifying cumulus cell (CC) markers of the oocyte development competence. To this purpose, mouse fully-grown antral follicles were isolated and the CCs separated from the oocytes enclosed. Then, based on their chromatin organization, oocytes were classified as surrounded nucleolus (SN, with a ring of Hoechst-positive heterochromatin surrounding the nucleolus) and non-surrounded nucleolus (NSN, when they displayed spots of heterochromatin widespread within the nucleus). SN oocytes, when matured in vitro to the MII stage, fertilized and the preimplantation embryo transferred in the uterus of a pseudo-pregnant female may reach full term; on the contrary, NSN oocytes arrest development at the 2-cell stage. CCs belonging to SN (SN-CCs) or NSN (NSN-CCs) oocytes were collected separately and analysed. We first made a microarray analysis of the whole transcriptome profile that brought up a list of 422 differentially regulated genes, most of which (97.6%) were down-regulated in NSN-CCs surrounding developmentally incompetent oocytes. A bioinformatics analysis associated these genes to 11 major biological processes, including development and reproduction. In addition, a bibliographic analysis of the literature based on a list of MeSH terms brought out a group of 26 differentially regulated genes involved in ovarian functions. Then, by Real Time PCR (qRT-PCR), we studied the expression of a group of CC-related genes: Has2, Ptx3, Ptgs2 and Tnfaip6, involved in cumulus expansion prior to ovulation and Amh involved in primordial follicles recruitment and dominant follicles selection. In the comparison between NSN-CCs vs. SN-CCs, Has2, Ptx3, Ptgs2 and Tnfaip6 resulted down regulated, whereas Amh showed a strong 4-fold up-regulation, confirming the microarray data. Among the gene sequences highlighted in our study, Amh was clearly the most differentially regulated in the comparison between NSN-CCs vs. SN-CCs, a difference that was confirmed also at the protein level (immunofluorescence). In conclusion, with the use of a model study that allows the identification, a priori, of the developmental capacity of antral mouse oocytes, for the first time, we identified a number of transcripts that could be used as markers of the oocyte developmental competence

    Met-Activating Genetically Improved Chimeric Factor-1 Promotes Angiogenesis and Hypertrophy in Adult Myogenesis

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    BACKGROUND: Myogenic progenitor cells (activated satellite cells) are able to express both HGF and its receptor cMet. After muscle injury, HGF-Met stimulation promotes activation and primary division of satellite cells. MAGIC-F1 (Met-Activating Genetically Improved Chimeric Factor-1) is an engineered protein that contains two human Met-binding domains that promotes muscle hypertrophy. MAGIC-F1 protects myogenic precursors against apoptosis and increases their fusion ability enhancing muscle differentiation. Hemizygous and homozygous Magic-F1 transgenic mice displayed constitutive muscle hypertrophy. METHODS: Here we describe microarray analysis on Magic-F1 myogenic progenitor cells showing an altered gene signatures on muscular hypertrophy and angiogenesis compared to wild-type cells. In addition, we performed a functional analysis on Magic-F1+/+ transgenic mice versus controls using treadmill test. RESULTS: We demonstrated that Magic-F1+/+ mice display an increase in muscle mass and cross-sectional area leading to an improvement in running performance. Moreover, the presence of MAGIC-F1 affected positively the vascular network, increasing the vessel number in fast twitch fibers. Finally, the gene expression profile analysis of Magic-F1+/+ satellite cells evidenced transcriptomic changes in genes involved in the control of muscle growth, development and vascularisation. CONCLUSION: We showed that MAGIC -F1-induced muscle hypertrophy affects positively vascular network, increasing vessel number in fast twitch fibers. This was due to unique features of mammalian skeletal muscle and its remarkable ability to adapt promptly to different physiological demands by modulating the gene expression profile in myogenic progenitor
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