Effects of acute and sub-chronic glucocorticoid treatments on hippocampal neurons of wild type and dystrophin-deficient DMDmdx mice: an in vitro and in vivo study

Duchenne muscular dystrophy (DMD) is a lethal X-linked disease characterized by progressive muscular wasting due to lack of full-length dystrophin (Dp427), a cytoskeletal protein expressed in muscle and selected brain regions (i.e. hippocampus). Dp427 binds to a large multi-proteic complex (Dystrophin Glycoprotein Complex, DGC), endowed with structural and functional properties, as the modulation of several intracellular signaling pathways. The presence of the dystrophin-DGC in areas involved in cognitive functions suggests that lack of Dp427 may be responsible for the neurological disturbances described in DMD patients. These could be further aggravated by the glucocorticoid (GC) therapeutic treatments of the muscular inflammation in DMD patients. As the hippocampus is one major GC target, in this study I analyzed whether in vitro (acute) and in vivo (acute and sub-chronic) treatments with either corticosterone (CORT) or dexamethasone (DEX) affected the already compromised hippocampal neuron physiology. Under any conditions we analyzed several parameters of the neuronal response to GCs: a) protein levels of the glucocorticoid receptor (GR) and of its phosphorylated (active) form pGR; b) mRNA levels of GR and GILZ; c) changes in the intensity of GR and pGR immunohistochemistry; d) protein levels of GR intracellular signaling effectors (i.e. caveolin 1, ERK 1/2); e) proliferation of hippocampal neural progenitor cells (NPC) (in vivo sub-chronic treatment only). In both in vitro and in vivo studies, mdx mouse hippocampal neurons respond differently than wild type to GC treatments. The general picture emerging is that they could be more sensitive to GCs and, therefore, more predisposed to be damaged. In fact, even acute GC administrations elicit a response similar to the more damaging chronic administration: i.e. reduction in GR levels, increase in the ration pGR/GR, possible reduction in GR gene expression, all aspects that are connotative of a chronic stress response. During high level of stress, which correspond to high and prolonged levels of secreted GCs, several physiological responses are altered, including those typical of hippocampal activity: i.e. synaptic plasticity, cognitive functions. These are accompanied by a reversal of the GC effects on hippocampal neurons: from the promotion of neuronal activity, and hence of its inhibitory control over the HPA axis, to its reduction, with consequent depression of HPA axis activity and increase in GC secretion. These are the basis for psychopathologies, as post-traumatic disorders. Therefore, the already compromised activity of the hippocampus in dystrophic subjects could be further damaged even by mild doses of GC, amplifying the risks for serious neural hilliness. Another crushing data is that sub-chronic treatments with DEX induce an increase in the proliferation of NPC in adult hippocampus, in contrast to what occurs in the wild type. This de-regulation of precursor cell cycle, responsible for of glia and neuronal self-renewal in adult brains, could further compromised hippocampal physiology. In conclusion, in the hope that new therapies could extend the life span of the young DMD patients, it is important to go deeper in the comprehension of how hippocampus and other brain areas affected by DMD, respond to anti-inflammatory (GCs) treatments

A micro-mechanical model of the elastic properties of a short fibre reinforced polyamide

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PRELIMINARY DESIGN OF AN X-RAY IMAGING SYSTEM FOR THE BONE STRUCTURAL INDEX EVALUATION

Osteoporosis (OP) is a very common disease in which the bones become weak and are more likely to break. Despite the huge costs in the EU and worldwide, the majority of individuals who have sustained an osteoporosis-related fracture or who are at high risk of fracture are left untreated. In effect, OP is a silent disease, with bones deteriorating without warning until fracture, and the current screening modalities are not significantly better than age alone, also because they consider only the bone quantity (bone mineral density, BMD) and the clinical risk factors, but disregard the bone quality, that is the structural soundness of the trabecular arrangement, which can be evaluated by simulations on virtual models. While 3D models can only be used in research because of high costs, an alternative approach based on the acquisition of planar hand radiograms for bone behaviour simulations, and the use of a Structural Index, SI, for bone quality ranking, have been developed at the University of Trieste. In this work, we discuss the preliminary design of a portable low dose X-ray hand scanner to be used as a low cost, user-friendly device (Fig.1) for imaging the trabecular pattern in the proximal phalanges of the non-dominant hand and for providing a radiogram suitable for the SI evaluation

PRELIMINARY DESIGN OF AN X-RAY IMAGING SYSTEM FOR THE BONE STRUCTURAL INDEX EVALUATION

Osteoporosis (OP) is a very common disease in which the bones become weak and are more likely to break. Despite the huge costs in the EU and worldwide, the majority of individuals who have sustained an osteoporosis-related fracture or who are at high risk of fracture are left untreated. In effect, OP is a silent disease, with bones deteriorating without warning until fracture, and the current screening modalities are not significantly better than age alone, also because they consider only the bone quantity (bone mineral density, BMD) and the clinical risk factors, but disregard the bone quality, that is the structural soundness of the trabecular arrangement, which can be evaluated by simulations on virtual models. While 3D models can only be used in research because of high costs, an alternative approach based on the acquisition of planar hand radiograms for bone behaviour simulations, and the use of a Structural Index, SI, for bone quality ranking, have been developed at the University of Trieste. In this work, we discuss the preliminary design of a portable low dose X-ray hand scanner to be used as a low cost, user-friendly device (Fig.1) for imaging the trabecular pattern in the proximal phalanges of the non-dominant hand and for providing a radiogram suitable for the SI evaluation

A 3-year follow-up study on bone structure elastic quality

Osteoporosis is called a silent disease because bone fragility manifests itself to the patient only in an advanced state, through fracture and pain. Medical and industry leaders recognize that the current golden standard diagnostic method, densitometry, or Dual Energy X-ray Absorptiometry (DEXA), may not always be sufficient to assess the patient’s real risk of fragility fracture [1]. Indeed, pathological alterations affect not only the mineral content (quantity) of the bone, but also its “quality”, which can be measured from the elastic properties of the bone internal trabecular structure by means of the Bone Elastic Structure Test, BES TEST®. In this study, the incidence of fragility fractures was assessed after a 3-year follow-up period in the women enrolled for a population study in 2015. The BES TEST® resulted an effective estimator of bone health, and can improve the assessment of the patient’s fracture risk map

Studio del danneggiamento mediante tomografia in luce del sincrotrone: impatto di un cono d’ombra sulla qualità finale delle ricostruzioni

Un’accurata osservazione della geometria tridimensionale di cricche e difetti è necessaria per lostudio dei meccanismi alla base del processo di danneggiamento. I metodi convenzionali utilizzati a questoscopo sono distruttivi o non possiedono una sufficiente risoluzione. Le tecniche di imaging che utilizzano laluce di sincrotrone, ed in particolare la microtomografia (micro-CT) a raggi X, invece, uniscono i vantaggi di unatecnica non distruttiva ad un’elevata risoluzione spaziale e risultano quindi particolarmente interessanti. Unlimite all’applicazione di questa tecnica è costituito dalla propensione della cricca a richiudersi una volta rimossoil carico che ha provocato il danneggiamento, superabile attraverso l’impiego di un dispositivo in grado diesercitare un carico di trazione durante l’acquisizione dei dati. Facendo riferimento al set-up sperimentale dellalinea SYRMEP di Elettra, il sincrotrone di Trieste, e tralasciando per il momento i vincoli legati a pesi eingombri, è possibile pensare di inserire tra camera di ionizzazione e CCD una macchina per prove di trazionemono-colonna commerciale, in grado di mantenere aperto il difetto per tutta la durata della tomografia. Inquesto lavoro viene valutato l’impatto di questo vincolo sulla qualità finale delle ricostruzioni

A Clinical Application of the Bone Structure Index

It has been recently estimated that about 30% of women and 20% of men over 50 will develop osteoporosis, a disease characterized by decreasing bone strength. Although low bone mineral density is generally associated with higher fracture risk, the spatial arrangement of the trabecular structure is a second key factor of bone resistance [1] and about 40-60% of the fractures affect people that can be considered at moderate risk on the basis of densitometry (DXA) assessment alone [2, 3]. Hence the need to develop innovative and low-cost diagnostic methods that can be used together with the consolidated systems. The recently introduced Bone Structure Index (BSI) gives an indication of the quality of the bone structure: it measures the weight-bearing capacity of the bone structure, evaluated from simulated application of loads on a virtual biopsy of the patient. The bone structure images are acquired by planar radiograms in the proximal epiphysis of the three central proximal phalanges of the non-dominant hand, a peripheral site of the human body [4-7]. In this work, we describe a recent application of the BSI in a clinical setting