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Introduction: As skeletal muscle mass recovery after extensive injury is improved by contractile activity, we explored whether concomitant exercise accelerates recovery of the contractile and metabolic phenotypes after muscle injury., Methods: After notexin-induced degeneration of a soleus muscle, Wistar rats were assigned to active (running exercise) or sedentary groups. Myosin heavy chains (MHC), metabolic enzymes, and calcineurin were studied during muscle regeneration at different time points., Results: The mature MHC profile recovered earlier in active rats (21 days after injury) than in sedentary rats (42 days). Calcineurin was higher in the active degenerated than in the sedentary degenerated muscles at day 14. Citrate synthase and total lactate dehydrogenase (LDH) activity decreased after injury and were similarly recovered in both active and sedentary groups at 14 or 42 days, respectively. H-LDH isozyme activity recovered earlier in the active rats., Conclusions: Exercise improved recovery of the slow/oxidative phenotype after soleus muscle injury. Muscle Nerve 55: 91-100, 2017., (© 2016 Wiley Periodicals, Inc.)

Purpose: Creatine (Cr) supplementation may improve muscle functional capacity in patients with neuromuscular diseases, disuse atrophy, or muscular dystrophies. Activation of myogenic satellite cells has been reported to be enhanced by Cr both in vitro and in vivo. Therefore, we hypothesized that Cr supplementation may improve the early steps of regeneration after muscle injury and may accelerate the recovery of both muscle mass and phenotype., Methods: Degeneration of left soleus muscle was induced by notexin injection in rats supplemented or not with Cr. The mass of regenerated muscles was compared with contralateral intact muscles at days 1, 3, 7, 14, 21, 28, 35, and 42 after injury. We also studied protein levels of the proliferator cell nuclear antigen (PCNA) as a marker of cell proliferation, expression of myogenic regulatory factors (MRF) as a marker of differentiation, and the myosin heavy chain (MHC) profile and activities of citrate synthase (CS) and lactate dehydrogenase (LDH) isozymes as markers of muscle phenotype maturation., Results: Cr supplementation accelerated the recovery of muscle Cr content during the regeneration phase. Although there were no other differences between Cr-treated and nontreated rats, we observed that 1) regenerated muscle mass remained lower than that in intact muscle mass 42 d after injury, 2) PCNA and MRF expression strongly increased in regenerated muscles, 3) the MHC profile of regenerated muscles was recovered 28 d after injury, and 4) CS activity was fully recovered from day 14, whereas the specific H isozyme of lactate dehydrogenase activity remained lower than that in intact muscles until 42 d., Conclusions: In contrast with results from in vitro studies, Cr supplementation had no effects in vivo on the time course of recovery of rat skeletal muscle mass and phenotype after notexin-induced injury.

The present study was designed to test the hypothesis that increasing physical activity by running exercise could favor the recovery of muscle mass after extensive injury and to determine the main molecular mechanisms involved. Left soleus muscles of female Wistar rats were degenerated by notexin injection before animals were assigned to either a sedentary group or an exercised group. Both regenerating and contralateral intact muscles from active and sedentary rats were removed 5, 7, 14, 21, 28 and 42 days after injury (n = 8 rats/group). Increasing contractile activity through running exercise during muscle regeneration ensured the full recovery of muscle mass and muscle cross-sectional area as soon as 21 days after injury, whereas muscle weight remained lower even 42 days postinjury in sedentary rats. Proliferator cell nuclear antigen and MyoD protein expression went on longer in active rats than in sedentary rats. Myogenin protein expression was higher in active animals than in sedentary animals 21 days postinjury. The Akt-mammalian target of rapamycin (mTOR) pathway was activated early during the regeneration process, with further increases of mTOR phosphorylation and its downstream effectors, eukaryotic initiation factor-4E-binding protein-1 and p70(s6k), in active rats compared with sedentary rats (days 7-14). The exercise-induced increase in mTOR phosphorylation, independently of Akt, was associated with decreased levels of phosphorylated AMP-activated protein kinase. Taken together, these results provided evidence that increasing contractile activity during muscle regeneration ensured early and full recovery of muscle mass and suggested that these beneficial effects may be due to a longer proliferative step of myogenic cells and activation of mTOR signaling, independently of Akt, during the maturation step of muscle regeneration.

Malaria caused by Plasmodium falciparum remains the major life-threatening parasitic infection in the world. The number of cases in non-endemic countries continues to increase, and it is important that misdiagnosis of malaria should not occur, especially in non-immune travellers, because of the high risk of a fatal outcome. In a retrospective study of 399 sera, the Now Malaria rapid test was compared with the quantitative buffy coat (QBC) test and microbiological examination of thin blood films. Compared with the QBC test and thin blood films, the Now Malaria test had sensitivity and specificity values of 96.4% and 97%, respectively, for the detection of pure P. falciparum infection. A negative predictive value of 99.4% allows this test to be included in diagnostic strategies for patients presenting with clinical suspicion of malaria. Two false-negative results were associated with low levels of parasitaemia in the specimens. Thus, use of the Now Malaria test alone to detect P. falciparum infection in non-endemic countries could lead to misdiagnosis of malaria. This rapid diagnostic test should therefore be performed in association with another prompt traditional method such as examination of thin blood films.