148 research outputs found
ANALYSIS OF THE DAMAGE STATE OF A MONUMENTAL BUILDING BY CONSIDERING THE VARIATIONS IN SOIL CONDITIONS
This paper investigates whether it is possible to identify the influence of soil conditions on the modal parameters of the structure for damage detection and overall structural health monitoring. To do so, the data gathered on a large monumental building damaged by differ-ential settlements are analyzed. In particular the dynamic response of the case study, a large monumental masonry building, was experimentally investigated within an operational modal analysis (OMA) campaign. Mechanical data obtained from the geophysical tests were in turn employed to build and characterize a numerical model of the soil underlying and sur-rounding the building. The resulting model was then used to study the sensitivity of the mod-al charasteristics of the building with respect to variations of external environmental factors (e.g., the water table level) which affect the underlying soil. The results obtained from this numerical study is deemed to represent a starting point for future experimental tests and investigations, whose final aim is relating ambient vibration measurement to the occurrence of differential settlements or subsidence, in order to detect progressive, and possibly pathological, behaviors
Combining satellite geophysical data with continuous on-site measurements for monitoring the dynamic parameters of civil structures
One key issue in the Structural Health Monitoring (SHM) of buildings is the influence of the soil on the dynamics of the system. The lack of accurate information on soil-structure interaction represents a source of significant uncertainty and generates difficulties in assessing the state of structural health. In this respect, satellite data could represent a valuable tool for soil knowledge. This paper presents the first study of satellite data coming from the environmental Copernicus program of the European Space Agency (ESA) for the alternative application in the field of SHM. In particular, Land Surface Temperature (LST) and Soil Water Index (SWI) data are elected to study surface temperature and moisture condition of the soil. Once examined and processed, these records have been statistically analyzed, crossed with on-site experimental quantities (natural frequencies and environmental variations), and given as input to a Finite Element (FE) model. The final goal is to understand the actual structural behavior, but also to monitor the evolution of the dynamic parameters for the purposes of structural and seismic monitoring. The largest oval masonry dome in the world was chosen as a prominent case study to demonstrate this novel approach to SHM
Flatfoot in children: anatomy of decision making
Concern about a child’s foot posture is a common reason for frequent consultations for an array of health care professionals; sports medicine specialists are often the first to recognize and advise on foot pathology. In the decision making process, it is essential to distinguish between the different types of flatfoot deformity: paediatric or adult, congenital or acquired, flexible or rigid. Although flatfoot in children is a common finding, evidence for the techniques of the reliable and reproducible assessment of the foot posture is scant. This general review presents the factors involved in the forming and supporting of the foot arches, discusses the protocols useful in the evaluation of the foot posture, and indicates how to differentiate between flatfoot cases needing treatment and cases that need only reassurance
A mechanistic study on the cardiotoxicity of 5-fluorouracil in vitro and clinical and occupational perspectives
AbstractFluoropyrimidines are key agents for the treatment of gastrointestinal tract adenocarcinomas. The possible cardiotoxic effects in patients and occupationally exposed workers are multifactorial and remain a puzzle to solve for investigators. In the present study, we study what cell death pathways and what doses can determine direct cardiotoxic effects of 5-fluorouracil (5-FU) and doxorubicin (DOXO) on rat cardiocytes (H9c2) and a human colon adenocarcinoma (HT-29) cell line, already reported to be sensitive to 5-FU. We have found that 5-FU induced 50% growth inhibition (IC:50) at 72h with concentrations of 400ÎĽM and 4ÎĽM on H9c2 and HT-29, respectively. Moreover, we have found that the addition of Levofolinic Acid (LF) to 5-FU potentiated the growth inhibition induced by 5-FU. The growth inhibition induced by 5-FU alone or in combination with LF in cardiocytes was paralleled by an increase of thiobarbituric acid-reactive species (Tbars) and end products of nitric oxide (NO) suggesting the increase of the oxidative stress status in cardiocytes. Interestingly, these effects were strongly potentiated by the addition of LF, a biochemical modulator of 5-FU activity.Our data suggest that agents such as 5-FU different from anthracyclines, conventionally related to the induction of cardiotoxic effects, can also induce cardiocyte damage paralleled by oxidative stress. The strategies based upon the use of scavengers could be used in order to prevent this effect
Flatfoot in children: anatomy of decision making
Concern about a child’s foot posture is a common reason for frequent consultations for an array of health care professionals; sports medicine specialists are often the first to recognize and advise on foot pathology. In the decision making process, it is essential to distinguish between the different types of flatfoot deformity: paediatric or adult, congenital or acquired, flexible or rigid. Although flatfoot in children is a common finding, evidence for the techniques of the reliable and reproducible assessment of the foot posture is scant. This general review presents the factors involved in the forming and supporting of the foot arches, discusses the protocols useful in the evaluation of the foot posture, and indicates how to differentiate between flatfoot cases needing treatment and cases that need only reassurance
Aorta and pulmonary trunk - comparison of wall structure in typical and atypical (Ross procedure) blood pressure conditions
The ascending aorta and pulmonary trunk develop from the common truncus arteriosus that later becomes symmetrically divided by the aorticopulmonary septum. Normally, the systolic pressure value and the diastolic pressure gradient in the aorta is much higher than that in the pulmonary artery. In the Ross procedure, patient’s diseased aortic valve is replaced with their own pulmonary valve and as a consequence the pulmonary trunk is placed in the aortic root position. Typically, a reinforcement of transposed pulmonary trunk is necessary to avoid vessel dilation. In order to investigate how the blood flow characteristics determine the vessel wall structure we examined by immunochemistry the wall of normal aorta (NA), normal pulmonary trunk (NPT), transposed pulmonary trunk (trPT) and transposed pulmonary trunk with reinforcement (trPT-R). Throughout the tunica media of NA, elastic fibers form numerous, conspicuous and orderly arranged wavy lamellae that parallel thin layers of smooth muscle cells between the internal and external elastic membrane. In the NPT, smooth muscle cells run amid collagen fibers and form layers that are thicker and irregular, with elastic fibers arranged accordingly. In the trPT, intima denudation and media disruptions were observed. In the tunica media, smooth muscle cells were abundant, but muscle fibers, with irregular profiles and no discernible alignment, were widely spaced with intervening collagen fibers. In the trPA-R, the endothelial lining was preserved and elastic fibers formed a thick and highly organized layer of concentric lamellae in the middle third of tunica media. The structure of normal aorta and pulmonary trunk, both elastic arteries, with common embryological origin, differs significantly in terms of smooth muscle and elastic sheets number and organization. The animal model of Ross procedure with pulmonary trunk in aorta position further underscores the role of blood pressure and mechanical stress in vessel wall modification
Biological properties of cardiac stem cells in normal and pathological conditions - matrix makes a difference
Cardiac cells and extracellular matrix (ECM) are reciprocally related and their characteristics are modified in response to developmental or pathophysiological cues. Adult human cardiac tissue regeneration mediated by cardiac stem cells (CSCs) is strictly regulated and, hypothetically, impaired by the ECM-CSC signalling in the pathological conditions. To test this hypothesis, we isolated cardiac fibroblasts (CFs) and CSCs from the atria of age-matched adult human normal (n=9) and pathological hearts (ischemic cardiomyopathy, n=11). The CFs were cultured in order to obtain ECM coating and conditioned medium, which were characterized by immunoblotting and ELISA, respectively. Next, we examined the effects of CF-derived ECM and CF-conditioned medium on normal and pathological CSC proliferation, apoptosis, and migration in vitro. The ECM produced by CFs from normal heart was composed mainly of fibronectin, laminin α2 and collagen I, while that produced by CFs from hearts with ischemic cardiomyopathy contained also laminin α1 and tenascin X. Compared to the normal CF-conditioned medium, that conditioned by pathological CFs contained twice as much IGF1 and HGF, and it stimulated proliferation and migration, while reducing apoptosis of CSCs. In the presence of pathological CF-derived ECM, there was a nearly 2-fold increase (p<0.05) in proliferation of normal and pathological CSCs, when compared to normal CF-derived ECM. Moreover, pathological CF-derived ECM reduced CSC apoptosis, specifically in cells from pathological heart. However, in the same conditions, the migration of pathological CSCs was significantly lower. These results indicate that the activity of CFs and its modification in chronic ischemic conditions determines biological properties of CSCs. Such an influence should be taken into consideration when attempting ischemic cardiac tissue stem cell-based regeneration
Bioresorbable reinforcement induces histological rearrangement of pulmonary autograft in an experimental model of Ross operation
The Ross procedure has emerged as a popular choice for aortic valve replacement in infants and children. However, pulmonary artery (PA) autograft dilation remains the major concern; hence, several modifications of the valve implantation techniques, such as reinforcing the autografts with a tubular synthetic mesh, have been reported. With the aim to prevent dilation and permit the normal growth of the neo-aortic root following pulmonary autograft implantation, we assessed the biological effect and long term performance of an external bioresorbable reinforcement for PA autograft in an experimental Ross model in growing animals. An experimental model of translocation of the pulmonary trunk as autograft in aortic position, funded on the Hook’s law and Laplace equilibrium, has been developed and performed under cardiopulmonary bypass in young lambs. The PA without reinforcement (n=5) was compared to PA reinforced with new scaffold polymer with an external armour of Polytetrafluoroethylene. The PA autograft diameter was measured using transoesophageal echography at day 0 and at 6 months and compared to the distal aortic diameter. Pathological analysis of the PA autograft reinforced was performed at 6 months and the results were compared to those of a control group with no reinforcement (n=5) Animal weight was 25+5 kg at day 0 and 58+10 kg at 6 months and the reference aortic diameter increased from 14+1mm at day 0 to 17+2mm at 6 months. With no reinforcement, an instantaneous PA graft distension (27,4+2mm) was noted followed by an aneurysmal formation at 6 months (38+3mm). Reinforcement with scaffold polymer on polidioxanone allowed maintaining the PA graft diameter close to the reference value (17+2mm at day 0). Immunohistochemistry revealed MMP-9 overexpression indicating the induction of a matrix remodeling process that are not detectable in the control group. Mallory staining revealed elastin deposition in the reinforced PA in comparison to the collagen present in the non-reinforced group, reliably suggesting a shift towards an elastic remodeling and arterialization. PicroSirius red staining reveled in the control group collagen fibers non- homogeneously distributed with a increased cellularity indicating inflammatory infiltrates. The reinforced PA displays more organized and dense collagen fibers in the “elastic zone” of the vessel and less pronounced cellular infiltrate. In conclusion, bioresorbable external polydioxanone-based reinforcement allowed a structural rearrangement of PA autograft consisting of media reorganization with an increase in the elastic wall component. Such histological outcome arguably prevented autograft dilation and conferred enhanced mechanical properties on the PA wal
Positional memory of fibroblasts may affect efficiency of iPSC reprogramming
Induced Pluripotent Stem cells (iPSC) are pluripotent stem cells reprogrammed from adult somatic cells. Although iPSC hold great potential for applications in regenerative medicine, technical problems, mostly related to the low efficiency of reprogramming, are yet to be solved. Since the most used cells for iPSC reprogramming are skin fibroblasts (FB), and since FB preserve positional memory, we hypothesize that the anatomic origin of FB might influence iPSC reprogramming.We isolated FB from skin of five different sites (neck, arm, thigh, breast, abdomen) of 13 patients undergoing plastic surgery or from heart wall or ascending aorta wall of the explanted heart of 3 patients receiving heart transplantation. FB from different anatomic sites and control FB from neonatal foreskin, were cultured for one week to evaluate morphology, proliferation rate and proneness to apoptosis. Additionally, expression of vimentin, cadherin, smooth muscle actin and Factor VIII was investigated to exclude the presence of other cell types. Transcriptome analysis including genes involved in stemness maintenance, embryogenesis, cell growth, activation and development, was performed by real-time PCR. Despite the similar morphology of FB from different sites, and immunopositivity for vimentin, along with the absence of other cell type markers, FB isolated from abdomen and heart had 1.5-fold higher doubling time, while FB from heart, abdomen and breast were less susceptible to apoptosis. Intriguingly, Real-Time PCR revealed that in abdomen, breast, neck, arm and heart FB genes involved in cell growth, development, proliferation, and migration, as TM4SF1, GPC4, CSPG2, DDIT4, ID1 were up-regulated, while genes regulating embryogenesis and tissue morphogenesis, like VCAN, FN1, HOXA5, CD49a were up-regulated in FB isolated from abdomen, arm and heart. However, all FBs had transcripts of markers of Mesenchymal Stem Cells (MSC), as CD105 and CD90. Our results provide evidence that human adult FB from different sites have different genetic program. Therefore, FB may respond to reprogram technology in different manner, thus affecting reprogramming efficiency. While offering novel perspective of the reprogramming technology, our study also demonstrates that abdomen and breast FB share cardiac genetic signature of cardiac FB while expressing markers of MSC and they might represent the ideal cell for cardiac reprogramming
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