Objectives – An increased expression of adenine nucleotide translocator (ANT1), found in facioscapulohumeral muscular dystrophy (FSHD), is known to lead to a decrease in nuclear factor-κB (NF-κB) DNA binding and to sensitize muscle cells to oxidative stress and apoptosis. Receptor for advanced glycation end products (RAGE) mediated by NF-κB activation is involved in proinflammatory pathomechanism and in muscle fiber regeneration in inflammatory myopathies and in limb girdle muscular dystrophy. Oxidative stress can stimulate RAGE- NF-κB pathway. Our purpose was to verify if oxidative stress may induce RAGE- NF-κB pathway activation in FSHD, contributing to the pathogenesis of such a disease. Materials and methods – On muscle samples of eight patients with FSHD, eight patients with Duchenne muscular dystrophy and eight normal controls the following studies were carried out: immunocytochemistry for activated NF-κB; electrophoretic mobility shift assay of NF-κB DNA binding activity; Western blot studies of RAGE and ANT1; hydrogen peroxide (HP), peroxidase and glutathione peroxidase (GPx) assays. Results – An increased RAGE and ANT1 expression in FSHD with moderate increase of NF-κB DNA binding activity was found together with an increased production of HP and a reduced activity of peroxidase and GPx. Conclusions – Our data confirm that response to oxidative stress and ANT1 increased activity are early events in FSHD muscle. The study also reveals that the RAGE- NF-κB pathway, induced by oxidative stress, is activated independently of the presence of a clear histochemical evidence of muscle damage in FSHD.

Excitotoxic studies using isolated chick embryo retina indicated that such an in vitro model provides a valid tool to characterize the effect of different agonists for subtypes of glutamate ionotropic receptors. In retinas maintained for 24 h in a Krebs medium, after a brief exposure (30 min) to glutamate agonists, we compared the effects produced by NMDA and non‐NMDA‐agonists, such as kainic acid (KA) or α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA). Delayed retinal damage was assessed by measuring lactate dehydrogenase (LDH) present in the medium after exposure to the previously named agonists. Although at high concentrations, both KA and AMPA produced more relevant release than NMDA, 7–8% of total retinal LDH was released after exposure to a 50 µm concentration of non‐NMDA agonists. These values were similar to those obtained after 100 µm NMDA. In this regard, retinal tissue appeared to be less sensitive to excitotoxicity based on the activation of NMDA receptor subtype. All three agents produced histopathological lesions typical for excitotoxic damage. A delayed form of excitotoxicity observed in retina segments was predominated by necrotic features. However, the activation of apoptotic machinery early during the incubation period subsequent to brief exposure to NMDA (100 µm) was also present. The activation of caspase enzymes was studied by a fluorometric protease activity assay as well as by western blot analysis. Caspase‐3‐like activity reached the highest value within 3 h of incubation after exposure to excitotoxin, then the level of enzyme activity declined to lower values. As confirmed by a time‐related appearance of TUNEL‐positive nuclei, apoptotic features appeared to be specific for retina response to NMDA. In contrast, the exposure to a 50 µm concentration of KA or AMPA induced necrotic cell damage which was evident through the incubation, leading to a delayed mechanism of excitotoxicity. These observations provide evidence that in the retinal model, with regard to agonist concentrations and subtype of glutamate receptors, the cascade of events leading to excitotoxicity may result in either apoptotic or necrotic neuronal cell damage.

TO establish whether botulinum A toxin (BTX-A) acts on modifying reciprocal inhibition between forearm muscles in spasticity, 20 patients with post-stroke upper limb spasticity lasting for more than 1 year were studied. Clinical examination, physiotherapeutic evaluation, standardized video-tape assessment and electrophysiological testing (flexor carpi radialis muscle M and H responses with study of reciprocal inhibition) were performed at baseline and 2 weeks, 1, 2, 3, 4 months after BTX-A treatment. BTX-A induced a significant decrease of tone and an improvement of motility and functional status, with a significant decrease of the M wave and the H reflex. The reduction in both inhibitory phases of reciprocal inhibition did not change after BTX-A treatment differently from that reported in upper limb dystonia. These findings indicate that the efficacy of BTX-A in upper limb spasticity is mainly due to peripheral effects.