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Regulated removal of proteins and organelles by autophagy–lysosome system is critical for muscle homeostasis. Excessive activation of autophagy-dependent degradation contributes to muscle atrophy and cachexia. Conversely, inhibition of autophagy causes accumulation of protein aggregates and abnormal organelles, leading to myofiber degeneration and myopathy. Defects in lysosomal function result in severe muscle disorders such as Pompe (glycogen storage disease type II (GSDII)) disease, characterized by an accumulation of autophagosomes. However, whether autophagy is detrimental or not in muscle function of Pompe patients is unclear. We studied infantile and late-onset GSDII patients and correlated impairment of autophagy with muscle wasting. We also monitored autophagy in patients who received recombinant α -glucosidase. Our data show that infantile and late-onset patients have different levels of autophagic flux, accumulation of p62-positive protein aggregates and expression of atrophy-related genes. Although the infantile patients show impaired autophagic function, the late-onset patients display an interesting correlation among autophagy impairment, atrophy and disease progression. Moreover, reactivation of autophagy in vitro contributes to acid α -glucosidase maturation in both healthy and diseased myotubes. Together, our data suggest that autophagy protects myofibers from disease progression and atrophy in late-onset patients.

An abnormal structural form of glycogen (with less branching points or amylopectin-like polysaccharide) called polyglucosan (PG) may accumulate in various tissues such as striated and smooth muscles, brain, nerve, liver and skin, and cause a group of nine different genetic disorders manifesting with a variety of clinical phenotypes that affect mainly the nervous system (Lafora disease, adult PG body disease), the heart (glycogen storage disease type XV, hypertrophic cardiomyopathy type 6, PG body myopathy type 1) and the skeletal muscle (glycogen storage disease type IV, glycogen storage disease type VII, PG body myopathy type 2), depending on the organs which are mostly affected by the PG aggregates. The pathological feature of PG storage in tissues is a hallmark of these disorders. Whole-genome sequencing has allowed to obtain a diagnosis in a large number of patients with a previously unrecognized disorder. We describe the clinical, pathological and molecular features of these genetic disorders, for many of which the pathological mechanisms underlying the corresponding mutant gene have been investigated and, at least in part, understood.

Tracking symptoms of eutrophication over time with multiple lines of evidence provides critical information to support environmental management and restoration efforts. For this case study of the Greater Charlotte Harbor estuary system in southwest Florida (USA), we assembled and curated 22 years of monthly water quality data from a spatially stratified random sampling design; estimated trends in annual mean concentrations of nitrogen, phosphorus, and chlorophyll-a across 13 monitoring strata over a sliding 5-year window between 2000 and 2021; identified hot spots where annual mean concentrations were increasing or elevated between 2017 and 2021, relative to stratum-specific thresholds informed by regulatory criteria; and summarized concurrent data from long-term surveys of macroalgal abundance and seagrass acreage. The water quality trend analysis methodology, based on generalized additive models (GAMs), captured seasonality and nonlinear inter-annual tendencies while accounting for uncertainty. Throughout the system, concentrations of total nitrogen increased and exceeded stratum-specific thresholds during the 2010 decade, while concentrations of total phosphorus and chlorophyll-a typically decreased to levels near or below thresholds. Low concentrations of inorganic nitrogen fractions indicated rapid biological assimilation consistent with eutrophication, while low chlorophyll-a concentrations indicated that nitrogen enrichment did not translate into excessive phytoplankton production. Instead, macroalgal proliferation and substantial seagrass losses were observed following Hurricane Irma (September 2017). We speculate that nitrogen enrichment during the 2010s increased the system’s vulnerability to Irma’s effects and helped tip the system toward these profound ecological changes. This work provides a broadly applicable framework for documenting and evaluating symptoms of eutrophication in estuaries.

Recent epidemiological studies on the general population reveal that up to 1.3% have oligo/asymptomatic hyperCKemia. This guideline aims to provide updated, evidence-based recommendations on investigating persons older than 18 years. The guideline followed EAN standard operating procedures and was developed according to the GRADE methodology. Fourteen neuromuscular experts from the EAN neuromuscular group were joined by a methodologist and a patient representative. There are two types of recommendations: evidence-based recommendations, based on published studies, and consensus statements if the quality of evidence is poor. We recommend that: (1) Persistent oligo/asymptomatic hyperCKemia with a CK > 1.5 ULN be investigated (Consensus statement); (2) Neurogenic and non-neuromuscular causes of hyperCKemia be excluded (Expert opinion); (3) A Dried Blood Spot (DBS) be done (Strong recommendation); (4) A NCS/EMG to identify whether there is a myopathy or neuropathy be performed (Weak recommendation); (5) A resting lactate and fasting acyl-carnitine assays, if a metabolic myopathy is suspected, be done (Consensus statement); (6) A skeletal muscle MRI be performed to guide/interpret genetic testing (Strong recommendation); (7) NGS is recommended over sequential gene testing (Consensus statement); (8) NGS is recommended over muscle biopsy (Strong recommendation); (9) A muscle biopsy may be offered, if genetic testing is uninformative and one or more applies: a genetic variant of unknown significance (VUS), suspected metabolic myopathy, suspected inflammatory myopathy, abnormal muscle MRI, a CK ≥ 3 ULN, a family history of muscle disease or age, less than 25 years (Expert opinion). An evidence-based guideline is suggested for when and how to investigate adults with oligo/asymptomatic hyperCKemia.

The objective of this study was to describe a large Italian cohort of patients with late-onset glycogen storage disease type 2 (GSDII) at various stages of disease progression and to evaluate the clinical effectiveness of alglucosidase alpha enzyme replacement therapy (ERT). Previous studies showed in late-onset patients ERT efficacy against placebo and variable response in uncontrolled studies. Seventy-four juvenile or adult GSDII patients were treated with ERT in a multicenter open label, non-randomized study, from 12 months up to 54 months. Recombinant human alpha glucosidase (rh-GAA) was injected by intravenous route at 20 mg/kg every second week. Patients were divided into three groups according to ERT duration: Group A received treatment for 12–23 months ( n  = 16), Group B for 24–35 months ( n  = 14), and Group C for more than 36 months ( n  = 44). Clinical assessment included a 6-min walk test (6MWT), forced vital capacity (FVC), the Walton and Gardner-Medwin score, the number of hours of ventilation, body mass index, echocardiography and blood creatine kinase (CK). Included in our cohort were 33 males and 41 females (M:F = 0.8:1), with a mean age at first symptoms of 28.3 years (range 2–55 years) and a mean age of 43 years at study entry (range 7–72 years). Seven wheelchair bound patients, as well as 27 patients requiring ventilation support, were included. After treatment we could observe an increase in distance walked on the 6MWT in the large majority of patients (48/58; 83%), with an overall mean increase of 63 m (from 320 ± 161 to 383 ± 178 m). After treatment in the majority of patients FVC was improved or unchanged (45/69; 65%). In ventilated patients we observed an improvement in average number of hours off the ventilator (from 15.6 to 12.1 h). Six patients stopped mechanical ventilation and two others started it. The effect of therapy was not related to ERT duration. Nine of 64 patients (13%) that underwent to echocardiography showed a variable degree of cardiac hypertrophy (left ventriculum or septum), and a positive effect was observed after 36 months of ERT in one adult case. Discontinuation of treatment occurred in four patients: one drop-off case, one patient died for a sepsis after 34 months of treatment and two patients stopped ERT for worsening of general clinical condition. Mild adverse effects were observed in four cases (5%). This study represents the largest cohort of late-onset GSDII patients treated with ERT, and confirm a positive effect of treatment. These results, obtained in a large case series on therapy, indicate a favourable effect of ERT therapy, even in more advanced stage of the disease.

In this work, the presence of calcium-dependent calcium channels and their receptors (RyR) has been investigated in Paracentrotus lividus eggs and early embryos, from unfertilized egg to four-blastomere stages. Electrophysiological recordings of RyR single-channel current fluctuations showed that RyRs are functional during the first developmental events with a maximum at zygote stage, c. 40 min after fertilization, corresponding to the first cleavage. The nature of vertebrate-like RyRs active at this stage was established by specific activation/blockade experiments.

Myotonic dystrophy (DM) is caused by a (CTG) n expansion in the 3′-untranslated region of DMPK gene. Mutant transcripts are retained in nuclear RNA foci, which sequester RNA binding proteins thereby misregulating the alternative splicing. Controversy still surrounds the pathogenesis of the DM1 muscle distress, characterized by myotonia, weakness and wasting with distal muscle atrophy. Eight primary human cell lines from adult-onset (DM1) and congenital (cDM1) patients, (CTG) n range 90–1800, were successfully differentiated into aneural-immature and contracting-innervated-mature myotubes. Morphological, immunohistochemical, RT-PCR and western blotting analyses of several markers of myogenesis indicated that in vitro differentiation–maturation of DM1 myotubes was comparable to age-matched controls. In all pathological muscle cells, (CTG) n expansions were confirmed by long PCR and RNA fluorescence in situ hybridization. Moreover, the DM1 myotubes showed the splicing alteration of insulin receptor and muscleblind-like 1 ( MBNL1 ) genes associated with the DM1 phenotype. Considerable myotube loss and atrophy of 15-day-differentiated DM1 myotubes indicated activated catabolic pathways, as confirmed by the presence of apoptotic (caspase-3 activation, cytochrome c release, chromatin fragmentation) and autophagic (P62/LC3) markers. Z-VAD treatment significantly reduced the decrease in myonuclei number and in average width in 15-day-differentiated DM1 myotubes. We thus propose that the muscle wasting typical in DM1 is due to impairment of muscle mass maintenance–regeneration, through premature apoptotic–autophagic activation, rather than altered myogenesis.

This updated and expanded new edition of a successful book describes genetic diagnostic entities of neuromuscular disorders. Neuromuscular syndromes are presented clinically either as a case study or as an overview from the literature, accompanied by text presenting molecular defects, and differential diagnosis. This collection of neuromuscular disorders features the differential clinical phenotypes related to each genotype and are representative of the whole spectrum of a genetic muscle disorder, helping the clinician and neuromuscular physician to make a diagnosis.

ObjectiveA multicentre observational study was aimed to assess the prevalence of late-onset Pompe disease (LOPD) in a large high-risk population, using the dried blood spot (DBS) as a main screening tool.Design/methods17 Italian neuromuscular centres were involved in the late-onset Pompe early diagnosis (LOPED) study. Inclusion criteria were: (1) age ≥5 years, (2) persistent hyperCKaemia and (3) muscle weakness at upper and/or lower limbs (limb-girdle muscle weakness, LGMW). Acid α-glucosidase (GAA) activity was measured separately on DBS by fluorometric as well as tandem mass spectrometry methods. A DBS retest was performed in patients resulted positive at first assay. For the final diagnosis, GAA deficiency was confirmed by a biochemical assay in skeletal muscle, whereas genotype was assessed by GAA molecular analysis.ResultsIn a 14-month period, we studied 1051 cases: 30 positive samples (2.9%) were detected by first DBS screening, whereas, after retesting, 21 samples were still positive. Biochemical and molecular genetic studies finally confirmed LOPD diagnosis in 17 cases (1.6%). The median time from the onset of symptoms/signs to diagnosis was 5 years. Among those patients, 35% showed presymptomatic hyperCKaemia and 59% showed hyperCKaemia+LGMW, whereas 6% manifested with LGMW.ConclusionsLOPED study suggests that GAA activity should be accurately screened by DBS in all patients referring for isolated hyperCKaemia and/or LGMW. A timely diagnosis was performed in five patients with presymptomatic hyperCKaemia, but two had already manifested with relevant changes on muscle morphology and MRI. Consequently, enzyme replacement therapy was started in 14/17 patients, including the 2 patients still clinically presymptomatic but with a laboratory evidence of disease progression.