Bmi1 enhances skeletal muscle regeneration through MT1-mediated oxidative stress protection in a mouse model of dystrophinopathy

The Polycomb group (PcG) protein Bmi1 is an essential epigenetic regulator of stem cell function during normal development and in adult organ systems. We show that mild up-regulation of Bmi1 expression in the adult stem cells of the skeletal muscle leads to a remarkable improvement of muscle function in a mouse model of Duchenne muscular dystrophy. The molecular mechanism underlying enhanced physiological function of Bmi1 depends on the injury context and it is mediated by metallothionein 1 (MT1)–driven modulation of resistance to oxidative stress in the satellite cell population. These results lay the basis for developing Bmi1 pharmacological activators, which either alone or in combination with MT1 agonists could be a powerful novel therapeutic approach to improve regeneration in muscle wasting conditions.Skeletal muscle is characterized by a remarkable capacity to regenerate after injury, mainly due to the function of satellite cells, the main skeletal muscle stem cells (Brack and Rando, 2012; Wang and Rudnicki, 2012). Polycomb group (PcG) proteins are essential regulators of stem cell function during normal development and in adult organs. They form multi-protein chromatin-associated complexes that play an essential role in the genome-wide epigenetic-mediated remodeling of gene expression during myogenic differentiation of satellite cells, mainly through posttranslational modifications of histones (Asp et al., 2011). Ezh2 and Bmi1 are required for adult satellite cell homeostasis and proliferation in response to muscle injury, an effect mediated at least in part by repression of the ink4a locus (Juan et al., 2011; Robson et al., 2011). Importantly, although Bmi1 is expressed in several types of cancer and its mechanism of action may be similar in a non-neoplastic and neoplastic context, its overexpression does not initiate tumorigenesis (He et al., 2009; Yadirgi et al., 2011).An emerging role for PcG proteins is their involvement in DNA repair (Liu et al., 2009; Facchino et al., 2010; Ismail et al., 2010; Ginjala et al., 2011; Pan et al., 2011). Bmi1^−/−-derived cells show significant mitochondrial dysfunction accompanied by sustained increase in reactive oxygen species (ROS) production that are sufficient to engage the DNA repair pathway (Liu et al., 2009), which is in turn impaired, thus leading to a magnified cellular damage. The balance between intracellular ROS and antioxidant molecules is vital in determining the rate of oxidative damage accumulation and the impaired function of satellite cells in aging and in myopathies, in which decreased anti-oxidative capacity has been documented (Fulle et al., 2005; Whitehead et al., 2006; Tidball and Wehling-Henricks, 2007). X-linked Duchenne muscular dystrophy (DMD) is the most common primary myopathy caused by the loss of the dystrophin protein from the plasma membrane, which causes loss of its integrity and fiber damage during repeated cycles of muscle degeneration and regeneration (Duncan, 1989). The proliferative capacity of myogenic cells was reported to be rapidly exhausted in dystrophin-deficient muscle, also because they are more sensitive to oxidative stress injury, leading to reduced and defective regeneration of the muscle as the disease progresses (Blau et al., 1983, 1985; Disatnik et al., 1998). Moreover, enzymatic adaptations to exercise-induced production of ROS and free radical damage are significantly decreased in dystrophic compared with normal muscles (Faist et al., 1998, 2001). Overall, an impaired protection against ROS in dystrophic muscle appears to contribute to disease progression as also indicated by the beneficial, albeit transient, effect of antioxidants in ameliorating the skeletal muscle pathophysiology of DMD patients (Whitehead et al., 2008).Metallothionein 1 (MT1) and MT2 are ubiquitously expressed (Kägi and Hunziker, 1989) low molecular weight, cysteine–rich zinc binding proteins. Although the role of MT1 in promoting cell proliferation is controversial (Smith et al., 2008), studies on MT-null liver cells showed their failure to regenerate after oxidative stress injury (Oliver et al., 2006).Here, we show that overexpression of Bmi1 in the satellite cells significantly improves muscle strength through enhanced MT1-mediated protection of these cells from oxidative stress in a mouse model of dystrophinopathies but not after acute traumatic injury.     

An Integrated Mobile Platform for Automated Data Collection and Real-Time Patient Monitoring in Diabetes Clinical Trials

We present a new mobile platform to be used in clinical trials aimed at both collecting data and assessing new technologies and treatments for diabetes care. The main components of the platform are a mobile app, that automatically collects data from continuous glucose monitoring sensors and activity trackers, and also allows users to manually log daily events; a cloud database for safe data storage; a web interface, which allows clinicians to monitor patients’ status in real-time. The platform is modular and highly customizable for a multitude of purposes in clinical research. Preliminary tests performed for daily-life data gathering by both clinicians and users are extremely encouraging.     

Cost-effectiveness analysis of two vacuum-assisted breast biopsy systems: Mammotome and Vacora

Purpose

This study was undertaken to compare the cost effectiveness of two vacuum-assisted breast biopsy devices, the Mammotome and Vacora systems.

Materials and methods

Between January and June 2006, 238 vacuum-assisted breast biopsies were performed at our radiology department. Five out of 238 lesions were excluded because of inadequate sampling. The Mammotome system was used in 108/233 lesions and the Vacora system in 125/233. Fifty-eight lesions underwent ultrasound-guided breast biopsy, and 50 lesions underwent mammography-guided biopsy with both Mammotome and Vacora devices. Magnetic-resonance-guided biopsy was possible with the Vacora system only (17/125 lesions).

Results

All procedures were successfully completed. No significant differences were found between the results of the Mammotome and Vacora biopsies in terms of effectiveness: sensitivity was 84.4% and 86.2%, respectively, and specificity 100%. In terms of cost, the Mammotome system has higher costs per procedure compared with the Vacora.

Conclusions

Our clinical results confirm the diagnostic accuracy of both the Mammotome and Vacora systems, whereas our cost analysis shows that there is a considerable difference, mostly related to the initial investment.     

Seizure duration and latency of hypermotor manifestations distinguish frontal from extrafrontal onset in sleep‐related hypermotor epilepsy

Sleep‐related hypermotor epilepsy (SHE) is an epilepsy syndrome that is characterized by the occurrence of sleep‐related hypermotor seizures of variable complexity and duration. Seizures usually arise in the frontal lobe, but extrafrontal seizure onset zones are well described. To identify clinically relevant ictal features of SHE that could distinguish a frontal from an extrafrontal onset zone, we conducted a retrospective analysis of seizure characteristics in 58 patients with drug‐resistant SHE (43 frontal and 15 extrafrontal) who underwent video‐stereo‐electroencephalographic recordings and became seizure‐free after epilepsy surgery. We found that the mean duration of electrographic seizures and clinically observable ictal manifestations were significantly shorter in frontal SHE compared to extrafrontal SHE. The mean latency between electrographic seizure onset and the onset of hypermotor manifestations was also shorter in frontal SHE. Accordingly, a latency > 5 seconds between the first video‐detectable movement (eg, eye opening or a minor motor event) and the onset of hypermotor manifestations yielded a sensitivity of 75% and a specificity of 90% for an extrafrontal onset, thereby indicating that specific ictal features in SHE can provide clinically useful clues to increase diagnostic accuracy in this syndrome.     

Spray-dried microspheres based on methylpyrrolidinone chitosan as new carrier for nasal administration of metoclopramide.

The work purpose was to study the application of 5-methylpyrrolidinone chitosan (MPC) for preparing mucoadhesive microparticles for the nasal administration of drugs. Microspheres were produced by the spray-drying technique using MPC; metoclopramide hydrochloride (MC) was chosen as model drug. Chitosan microparticles were prepared as a comparison. The microparticles obtained were characterised (encapsulation efficiency, morphology, size and drug release behaviour). In-vitro mucoadhesive tests, swelling tests and ex-vivo studies using sheep nasal mucosa were performed. The hydrogel formation from microspheres was studied in different media and at different pHs. Microspheres are able to control the in-vitro MC release. MPC microparticles show good in-vitro mucoadhesive properties and ex-vivo controlled permeation profiles. The hydrogel formation is dependent mainly on the medium used: ionically crosslinked hydrogel was hypothesized. These in-vitro and ex-vivo preliminary results show that spray-dried microspheres based on MPC could be a suitable nasal delivery system for the administration of metoclopramide.