Growth Factors Do Not Improve Muscle Function in Young or Adult mdx Mice

Hepatocyte growth factor; Leukemia inhibitory factor; Muscular regenerationFactor de crecimiento de los hepatocitos; Factor inhibidor de la leucemia; Regeneración muscularFactor de creixement dels hepatòcits; Factor inhibidor de la leucèmia; Regeneració muscularMuscular dystrophies constitute a broad group of genetic disorders leading to muscle wasting. We have previously demonstrated that treating a muscular atrophy mouse model with growth factors resulted in increased muscle mass. In the present study, we treated the Duchenne mouse model mdx for 12 weeks with myogenic growth factors peri- and post-onset of muscular degeneration to explore the effects in the oxidative muscle soleus and the glycolytic muscle extensor digitorum longus (EDL). We found no overall beneficial effect in the peri-onset group at the conclusion of the study. In the post-onset group, the functional improvement by means of electrophysiological examinations ex vivo was mostly confined to the soleus. EDL benefitted from the treatment on a molecular level but did not improve functionally. Histopathology revealed signs of inflammation at the end of treatment. In conclusion, the growth factor cocktail failed to improve the mdx on a functional level.This work was supported by grants from the Lundbeck Foundation (Grant No. R140-2013-13370 to J.V. and T.O.K.), Novo Nordisk Foundation (Grant No. 8091 to J.V. and T.O.K.), AP Møller Foundations (Grant No. 13-222 to T.O.K.), Instituto de Salud Carlos III y Fondos FEDER (FIS Project PI19/01313 to T.P.), and Augustinus Foundation (Grant No. 13-4153 to T.O.K.). None of the funding sources had any involvement in the study, data evaluation, or authoring of the manuscript

Acetaminophen treatment in children and adults with spinal muscular atrophy:a lower tolerance and higher risk of hepatotoxicity

Acute liver failure has been reported sporadically in patients with spinal muscular atrophy (SMA) and other neuromuscular disorders with low skeletal muscle mass receiving recommended dosages of acetaminophen. It is suggested that low skeletal muscle mass may add to the risk of toxicity. We aimed to describe the pharmacokinetics and safety of acetaminophen in patients with SMA. We analyzed acetaminophen metabolites and liver biomarkers in plasma from SMA patients and healthy controls (HC) every hour for six or eight hours on day 1 and day 3 of treatment with therapeutic doses of acetaminophen. Twelve patients with SMA (six adults and six children) and 11 HC participated in the study. Adult patients with SMA had significantly lower clearance of acetaminophen compared to HC (14.1 L/h vs. 21.5 L/h). Formation clearance of acetaminophen metabolites, glucuronide, sulfate, and oxidative metabolites were two-fold lower in the patients compared to HC. The liver transaminases and microRNAs increased nine-fold in one adult SMA patient after two days of treatment. The other patients and HC did not develop abnormal liver biomarkers. In this study, patients with SMA had lower clearance and slower metabolism of acetaminophen, and one patient developed liver involvement. We recommend giving 15 mg/kg/dose to SMA adults (with a maximum of 4000 mg/day) and monitoring standard liver biomarkers 48 h after first-time treatment of acetaminophen.</p