MYOTONIC DYSTROPHIES: GENETICALLY-BASED DISEASES DUE TO TOXIC RNA

Myotonic dystrophies (DMs, the second most diffuse forms of muscular dystrophy, after Duchenne dystrophy) are genetically-based degenerative neuromuscular diseases exhibiting widely variable clinical features and characterized by myotonia (i.e., a prolonged contraction of skeletal muscles after short stimulation) and a delayed muscle relaxation after voluntary contraction. There are two form of DMs: the more severe DM1 (or Steinert's disease), and the milder form DM2. The intranuclear accumulation of expanded RNAs is considered as the pathogenetic factor of DMs: the presence of these RNAs exerts a toxic action on cell function which essentially depends on the ectopic sequestration of nuclear protein factors involved in the processing of transcripts. The aim of this mini-symposium is to describe the genetic and cellular bases of DMs, showing how the results of basic research may provide important clues for both diagnosis and therapy

Transcranial electric stimulation as a neural interface to gain insight on human brain functions: current knowledge and future perspective

Abstract The use of brain stimulation approaches in social and affective science has greatly increased over the last two decades. The interest in social factors has grown along with technological advances in brain research. Transcranial electric stimulation (tES) is a research tool that allows scientists to establish contributory causality between brain functioning and social behaviour, therefore deepening our understanding of the social mind. Preliminary evidence is also starting to demonstrate that tES, either alone or in combination with pharmacological or behavioural interventions, can alleviate the symptomatology of individuals with affective or social cognition disorders. This review offers an overview of the application of tES in the field of social and affective neuroscience. We discuss the issues and challenges related to this application and suggest an avenue for future basic and translational research

Characterizing the cortical oscillatory response to TMS pulse

No abstract available

Feulgen-DNA Content and C-Banding of Robertsonian Transformed Karyotypes in Dugesia Lugubris

SUMMARYIn the planarian species, Dugesia lugubris, two biotypes are found: E (2n = 8, n = 4) and F (2n = 6, n = 3); on the basis of karyometric studies it has been hypothesized that the second was derived from the first through a Robert-sonian mechanism of centric fusion. The quantitative cytochemical data reported here confirm the hypothesis of karyotype evolution, since there are no significant differences between the DNA content of the nucleus in the two biotypes. The regenerative blastemas of both biotypes contain a number of cellular populations with a variable Feulgen-DNA content; these correspond to successive doublings of the 2C diploid content. In addition, metaphase plates with multistranded chromosomes have been found. A difference between the chromosome C-banding in the two biotypes has also been observed

The Golgi apparatus is a primary site of intracellular damage after photosensitization with Rose Bengal acetate

The aim of the present investigation was to elucidate whether the Golgi apparatus undergoes photodamage following administration of the fluorogenic substrates Rose Bengal acetate (RBAc) and irradiation at the appropriate wavelength. Human HeLa cells were treated in culture and the changes in the organization of the Golgi apparatus were studied using fluorescence confocal microscopy and electron microscopy, after immunocytochemical labeling. To see whether the cytoskeletal components primarily involved in vescicle traffic (i.e., microtubules) might also be affected, experiments of tubulin immunolabeling were performed. After treatment with RBAc and irradiation, cells were allowed to grow in drug-free medium for different times. 24hr after irradiation, the cisternae of the Golgi apparatus became packed, and after 48-72 hr they appeared more fragmented and scattered throughout the cytoplasm; these changes in the organization of the Golgi cisternae were confirmed at electron microscopy. Interestingly enough, apoptosis was found to occur especially 48-72h after irradiation, and apoptotic cells exhibited a dramatic fragmentation of the Golgi membranes. The immunolabeling with anti-tubulin antibody showed that microtubules were also affected by irradiation in RBAc-treated cells

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Effect of adapted physical exercise on satellite cells from skeletal muscles of old mice: ex vivo and in vitro analyses

Aging is characterized by loss of skeletal muscle mass termed sarcopenia, which contributes to frailty, disability and premature death (1). The mechanisms leading to sarcopenia are manifold, the decline in muscle regeneration efficiency playing a crucial role. In the absence of specific therapies, studies have stressed the importance of physical exercise as an effective approach to prevent/limit the sarcopenic drive (2,3). We investigated the effect of adapted exercise on the number and myogenic properties of satellite cells (SCs) in the quadriceps femoris and gastrocnemius muscles of old mice (28 months). Both muscles contain about 90% of type II fibers, which are especially affected by sarcopenia (4). We compared old exercised mice with old sedentary mice, adult sedentary mice (12 months) being the control. SCs were identified and quantified ex vivo; the proliferation and differentiation potential of SC-derived myoblasts from the three groups of mice was studied in vitro. Ultrastructural morphology and immunocytochemistry at light and electron microscopy level localized molecular markers of SC activation and protein factors involved in RNA transcription and splicing. Results showed that: 1) physical exercise induces an increase in the total number as well as activated fraction of SCs compared with sedentary old specimens; 2) myoblasts from exercised old muscles show morphological features and nuclear activity quite similar to myoblasts from adult subjects, whereas myoblasts from non-exercised old muscles exhibit structural and functional alterations suggestive of a reduced metabolic activity; 3) myotubes differentiated from myoblasts of exercised old muscles resemble those from adult myoblasts, whereas myotubes from non-exercised old muscles show marked structural alterations. Physical exercise induces numerical increase and activation of SCs in old muscles and improves their capability to differentiate into structurally and functionally complete myotubes. Adapted physical exercise may represent a non-pharmacological approach to stimulate SCs, enhancing muscle quality at very advanced age. MC is a PhD student of the Doctoral Program “Multimodal Imaging in Biomedicine” (University of Verona)

L-Carnitine Functionalization to Increase Skeletal Muscle Tropism of PLGA Nanoparticles

Muscular dystrophies are a group of rare genetic pathologies, encompassing a variety of clinical phenotypes and mechanisms of disease. Several compounds have been proposed to treat compromised muscles, but it is known that pharmacokinetics and pharmacodynamics problems could occur. To solve these issues, it has been suggested that nanocarriers could be used to allow controlled and targeted drug release. Therefore, the aim of this study was to prepare actively targeted poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) for the treatment of muscular pathologies. By taking advantage of the high affinity for carnitine of skeletal muscle cells due to the expression of Na+-coupled carnitine transporter (OCTN), NPs have been actively targeted via association to an amphiphilic derivative of L-carnitine. Furthermore, pentamidine, an old drug repurposed for its positive effects on myotonic dystrophy type I, was incorporated into NPs. We obtained monodispersed targeted NPs, with a mean diameter of about 100 nm and a negative zeta potential. To assess the targeting ability of the NPs, cell uptake studies were performed on C2C12 myoblasts and myotubes using confocal and transmission electron microscopy. The results showed an increased uptake of carnitine-functionalized NPs compared to nontargeted carriers in myotubes, which was probably due to the interaction with OCTN receptors occurring in large amounts in these differentiated muscle cells

Proliferation characteristics and polyploidization of cultured myofibroblasts from a patient with fibroblastic rheumatism

Fibroblast-like cells were obtained from a nodule of a patient with fibroblastic rheumatism, and grown in culture for different times (from passage 3 to 21). These cells as well as the fibroblasts taken from an unaffected skin area (controls) of the same patient, have been investigated by fluorescence microscopy, cytochemical methods and cytometry, to evaluate their cytodifferentiation features and cytokinetic characteristics. In addition, in low-passage cultures, the secretion of collagen and of non-collagenic proteins was evaluated using electrophoretic techniques. The immunolabeling with antibodies against sm-specific a-actin (which was taken as a marker of myofibroblasts) showed that, already in low-passage cultures, the percentage of myofibroblasts was higher in the nodule-derived cell populations, and progressively increased with increasing passages. This suggests that myofibroblasts have higher proliferation potential than control fibroblasts. Myofibroblasts were also found to undergo polyploidization and hypertrophy, especially in high-passage cultures. Based on these results, it may be hypothesized that in fibroblastic rheumatism the development of the typical nodules could depend on the intrinsic capability of myofibroblats of proliferating faster than normal fibroblasts and of becoming polyploid and hypertrophic. Nodule-derived cells in culture synthesized slightly less collagen and non-collagen proteins than did the control fibroblasts; this suggests that the increased fibrosis observed in nodules in situ could be likely dependent on a reduced degradation of the extracellular matrix components

Transcranial magnetic stimulation of the precuneus enhances memory and neural activity in prodromal Alzheimer's disease

Memory loss is one of the first symptoms of typical Alzheimer's disease (AD), for which there are no effective therapies available. The precuneus (PC) has been recently emphasized as a key area for the memory impairment observed in early AD, likely due to disconnection mechanisms within large-scale networks such as the default mode network (DMN). Using a multimodal approach we investigated in a two-week, randomized, sham-controlled, double-blinded trial the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) of the PC on cognition, as measured by the Alzheimer Disease Cooperative Study Preclinical Alzheimer Cognitive Composite in 14 patients with early AD (7 females). TMS combined with electroencephalography (TMS-EEG) was used to detect changes in brain connectivity. We found that rTMS of the PC induced a selective improvement in episodic memory, but not in other cognitive domains. Analysis of TMS-EEG signal revealed an increase of neural activity in patients' PC, an enhancement of brain oscillations in the beta band and a modification of functional connections between the PC and medial frontal areas within the DMN. Our findings show that high-frequency rTMS of the PC is a promising, non-invasive treatment for memory dysfunction in patients at early stages of AD. This clinical improvement is accompanied by modulation of brain connectivity, consistently with the pathophysiological model of brain disconnection in AD