Pulmonary rehabilitation: the reference therapy for undernourished patients with chronic obstructive pulmonary disease

Necrostatin-1 protects C2C12 myotubes from CoCl2-induced hypoxia

Necrostatin-1 (Nec-1) is a selective and potent allosteric inhibitor of necroptosis by specifically inhibiting the activity of receptor-interacting protein (RIP) 1 kinase. The aim of the present study was to determine the effect of Nec-1 on an anoxia model comprising mouse skeletal C2C12 myotubes. In the present study, a hypoxic mimetic reagent, cobalt chloride (CoCl₂), was used to induce hypoxia in C2C12 myotubes. The cytotoxic effects of CoCl₂-induced hypoxia were determined by a Cell Counting kit-8 assay and flow cytometry. Transmission electron microscopy (TEM) was used to characterize the morphological characteristics of dead cells at the ultrastructural level. To clarify the signaling pathways in CoCl₂-mediated cell death, the expression levels of RIP1, RIP3, extracellular signal-regulated kinase (ERK)1/2, hypoxia-inducible factor (HIF)-1α and B cell lymphoma-2 adenovirus E1B 19-kDa interacting protein 3 (BNIP3) were investigated by western blotting. Oxidative stress was determined using 2′,7′-dichlorofluorescin diacetate to measure intracellular reactive oxygen species (ROS) and the fluorescent dye JC-1 was used to measure mitochondrial membrane potential (Δψm). The results showed that the ratios of apoptotic and necrotic C2C12 cells were increased following CoCl₂ treatment, typical necroptotic morphological characteristics were able to observe by TEM, whereas Nec-1 exhibited a protective effect against CoCl₂-induced oxidative stress. Treatment with Nec-1 significantly decreased the levels of RIP1, p-ERK1/2, HIF-1α, BNIP3 and ROS induced by CoCl₂, and promoted C2C12 differentiation. Nec-1 reversed the CoCl₂-induced decrease in mitochondrial membrane potential. Together, these findings suggested that Nec-1 protected C2C12 myotubes under conditions of CoCl₂-induced hypoxia.

Effects of Cobalt Chloride, a Hypoxia-Mimetic Agent, on Autophagy and Atrophy in Skeletal C2C12 Myotubes

Background

Hypoxia-induced autophagy and muscle wasting occur in several environmental and pathological conditions. However, the molecular mechanisms underlying the effects of the hypoxia-mimetic agent CoCl₂ on autophagy and muscle atrophy are still unclear.

Methods

C2C12 myotubes were exposed to increasing concentrations of CoCl₂ for 24 hours. Quantitative RT-PCR, Western blotting, and transmission electron microscopy were performed to confirm autophagy occurs. Autophagy proteins were measured to understand the molecule mechanisms. We also inhibited hypoxic autophagy and examined the changes in myogenin expression, myotubes formation, and apoptosis.

Results

Our results showed that CoCl₂-mimicked hypoxia upregulated the expression of the autophagy-related proteins LC3, HIF-1α, BNIP3, p-AMPKα, and beclin-1, whereas p62 and p-mTOR were downregulated. In addition, the autophagosome could be observed after CoCl₂ induction. The expression of the autophagy-related E3 ligase parkin and the muscle-specific ubiquitin ligase atrogin-1 was increased by CoCl₂. Inhibition of autophagy by 3MA increased myogenin expression and promoted myotubes formation and the percentage of cell death was decreased.

Conclusions

Our results confirmed that CoCl₂-mimicked hypoxia induced autophagy via the HIF-1α/BNIP3/beclin-1 and AMPK/mTOR pathways. Our results also revealed an important link between autophagy and muscle atrophy under hypoxia, which may help to develop new therapeutic strategies for muscle diseases.

Effect of early rehabilitation on activities of daily living in patients with aspiration pneumonia

AIM

To assess the effect of early rehabilitation on improving activities of daily living (ADL) in elderly patients with aspiration pneumonia.

METHODS

Using the Japanese Diagnosis Procedure Combination inpatient database, we retrospectively analyzed consecutive patients with aspiration pneumonia at admission who received early rehabilitation (n = 48 201) or did not receive any rehabilitation (n = 64 357) from July 2010 to March 2013. Early rehabilitation was defined as any type of physical rehabilitation initiated within 7 days after admission. The proportions of improved ADL scores from admission to discharge were compared between the early rehabilitation group and the non-rehabilitation group using a multivariable logistic regression analysis and instrumental variable analysis.

RESULTS

The proportion of improved ADL scores was higher in the early rehabilitation group than in the non-rehabilitation group (25.4% vs 33.9%; P < 0.001). The multivariable logistic regression analysis showed that the early rehabilitation group exhibited significant improvement in ADL (odds ratio 1.57; 95% confidence interval 1.50-1.64; P < 0.001). The instrumental variable analysis showed that early rehabilitation was associated with increased proportion of improved ADL (risk difference 8.2%; 95% confidence interval 6.9-9.5%; P < 0.001).

CONCLUSIONS

The present results suggest that early rehabilitation might improve ADL during hospitalization in patients with aspiration pneumonia. Geriatr Gerontol Int 2016; 16: 1181-1187.

Guidelines for the evaluation and treatment of muscle dysfunction in patients with chronic obstructive pulmonary disease

In patients with chronic obstructive pulmonary disease (COPD), skeletal muscle dysfunction is a major comorbidity that negatively impacts their exercise capacity and quality of life. In the current guidelines, the most recent literature on the various aspects of COPD muscle dysfunction has been included. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) scale has been used to make evidence-based recommendations on the different features. Compared to a control population, one third of COPD patients exhibited a 25% decline in quadriceps muscle strength, even at early stages of their disease. Although both respiratory and limb muscles are altered, the latter are usually more severely affected. Numerous factors and biological mechanisms are involved in the etiology of COPD muscle dysfunction. Several tests are proposed in order to diagnose and evaluate the degree of muscle dysfunction of both respiratory and limb muscles (peripheral), as well as to identify the patients' exercise capacity (six-minute walking test and cycloergometry). Currently available therapeutic strategies including the different training modalities and pharmacological and nutritional support are also described.