In this study, we investigated the beneficial effects of high endogenous levels of n-3 polyunsaturated fatty acids (PUFAs) on skeletal muscle repair and regeneration using a mouse cardiotoxin (CTX, 20 μM/200 μL) -induced gastrocnemius muscle injury model. Transgenic fat-1 mice expressing the Caenorhabditis elegans fat-1 gene, encoding n-3 fatty acid desaturase, showed higher n-3 PUFA levels and lower n-6/n-3 PUFA ratios in gastrocnemius muscle tissues. Hematoxylin and eosin and Masson’s trichrome staining of gastrocnemius sections revealed increased muscle fiber size and reduced fibrosis in fat-1 mice on days 7 and 14 after CTX injections. Gastrocnemius muscle tissues from fat-1 mice showed reduced inflammatory responses and increased muscle fiber regeneration reflecting enhanced activation of satellite cells on day 3 after cardiotoxin injections. Gastrocnemius muscle tissues from cardiotoxin-treated fat-1 mice showed reduced levels of pro-apoptotic proteins (Caspase 3 and Bax) and increased levels of anti-apoptotic proteins (Bcl-2 and Survivin). Moreover, eicosapentaenoic acid (EPA) reduced the incidence of apoptosis among cardiotoxin-treated C2C12 mouse myoblasts. These findings demonstrate that higher endogenous n-3 PUFA levels in fat-1 mice enhances skeletal muscle repair and regeneration following cardiotoxin-induced injury.

BackgroundHand osteoarthritis (OA) is a chronic progressive disease characterized by disabling pain in the hand, with a high clinical burden. This study is designed to assess the epidemiological patterns of hand OA from 1990 to 2019 and analyze its secular trends based on sex, age, and socio-demographic index (SDI) at global, regional, and national levels.MethodsData on the incidence and disability-adjusted life years (DALYs) of hand OA were extracted from the 2019 Global Burden of Disease (GBD), and their respective age-standardized rates (ASRs) were calculated. The estimated annual percentage changes (EAPCs) in ASR were calculated to assess the prevalent trends of the incidence and DALYs of hand OA over the recent three decades. The relationship between ASR and SDI was analyzed by Pearson's correlation analysis.ResultsThe incidence of hand OA increased from 371.30 million in 1990 to 676.02 million in 2019, increasing by 82.07%, whereas its age-standardized incidence rate (ASIR) decreased, with a downward trend [EAPC = −0.34; 95% confidence interval: −0.39–−0.28]. With the changes in age, the incidence of hand OA exhibited a unimodal distribution before 70 years of age, peaking at 50–54 years, while its incidence had an upward trend in the >70 years age groups. Overall, hand OA-related DALYs increased in the recent 30 years. Meanwhile, its annual age-standardized DALY rate decreased, with EAPCs of −0.35 (95% CI, −0.38 –−0.32). The DALYs increased with age. In 2019, the ASIR and age-standardized DALY rate were positively associated with the SDI regions. The incidence and DALYs presented predominance in female patients. The burden of hand OA over the recent three decades displayed obvious geographical diversity.ConclusionThe incident cases of hand OA increased globally from 1990 to 2019, while the ASIR and age-standardized DALY rate decreased. However, in many countries and regions, there was a rising trend of ASR related to incidence and DALYs. In addition, the prevalence revealed geographical, sex, and age diversity. Thus, governments and medical institutions should reallocate medical resources based on the epidemiological characteristics of hand OA.

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