No abstract

We previously reported that polymethoxyflavones (PMFs) in black ginger (Kaempferia parviflora) extract (KPE) increased energy production by activating AMP-activated protein kinase (AMPK) in C2C12 myoblasts. We herein evaluated the effects of KPE on physical fitness performance and muscular endurance in mice. Male mice were orally administered KPE for 4 weeks, and then forced swimming test, open-field test, inclined plane test, and wire hanging test were performed. KPE significantly increased the swimming time, motility after swimming, and grip strength. IL-6 and TNF-α mRNA expression levels were decreased in the soleus muscle, whereas peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and glycogen synthase mRNA expression levels, mitochondrial number, and glycogen content were increased. These results were in agreement with those obtained for KPE and PMFs in C2C12. Therefore, the activation of AMPK by PMFs may be one of the mechanisms by which KPE improves physical fitness performance and muscular endurance.

Mg diffusion is a common problem in GaN devices with p–n junctions. Although this impurity diffusion is reported to occur through threading dislocations (TDs), no direct evidence has yet been obtained. Therefore, we tried the direct observation of Mg diffusion by atom probe tomography (APT) analysis. The n-type drift layer of the fabricated p–n diode was exposed, and etch pits were formed on the drift layer to identify the TD position. The APT analysis around TDs was carried out by lifting out the drift layer around specific etch pits using a focused ion beam to include TDs. The relationship between the etch pit shape and the TD type was confirmed by cross-sectional scanning transmission electron microscopy observation. The APT analysis of two types of etch pits formed on the mixed dislocations was performed, and Mg diffusion was clearly observed through the mixed dislocations. In this work, we show direct evidence of Mg diffusion via mixed dislocations in GaN p–n diodes and its effect on reverse leakage current.

Enhancement of muscular energy production is thought to improve locomotive functions and prevent metabolic syndromes including diabetes and lipidemia. Black ginger (Kaempferia parviflora) has been cultivated for traditional medicine in Thailand. Recent studies have shown that black ginger extract (KPE) activated brown adipocytes and lipolysis in white adipose tissue, which may cure obesity-related dysfunction of lipid metabolism. However, the effect of KPE on glucose and lipid utilization in muscle cells has not been examined yet. Hence, we evaluated the effect of KPE and its constituents on energy metabolism in pre-differentiated (p) and differentiated (d) C2C12 myoblasts. KPE (0.1-10 μg/ml) was added to pC2C12 cells in the differentiation process for a week or used to treat dC2C12 cells for 24 h. After culturing, parameters of glucose and lipid metabolism and mitochondrial biogenesis were assessed. In terms of the results, KPE enhanced the uptake of 2-deoxyglucose and lactic acid as well as the mRNA expression of glucose transporter (GLUT) 4 and monocarboxylate transporter (MCT) 1 in both types of cells. The expression of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α was enhanced in pC2C12 cells. In addition, KPE enhanced the production of ATP and mitochondrial biogenesis. Polymethoxy flavonoids in KPE including 5-hydroxy-7-methoxyflavone, 5-hydroxy-3,7,4'-trimethoxyflavone and 5,7-dimethoxyflavone enhanced the expression of GLUT4 and PGC-1α. Moreover, KPE and 5,7-dimethoxyflavone enhanced the phosphorylation of 5'AMP-activated protein kinase (AMPK). In conclusion, KPE and its polymethoxy flavonoids were found to enhance energy metabolism in myocytes. KPE may improve the dysfunction of muscle metabolism that leads to metabolic syndrome and locomotive dysfunction.

A previous clinical study on pre-obesity subjects revealed that Bifidobacterium breve B-3 shows anti-obesity effects and possibly increases muscle mass. Here, we investigated the effects of B-3 on muscle function, such as muscle strength and metabolism, and some signaling pathways in skeletal muscle. Male rodents were orally administered live B-3 (B-3L) or heat-killed B-3 (B-3HK) for 4 weeks. We found that administration of B-3 to rats tended to increase muscle mass and affect muscle metabolism, with stronger effects in the B-3HK group than in the B-3L group. B-3HK significantly increased muscle mass and activated Akt in the rat soleus. With regard to muscle metabolism, B-3HK significantly increased phosphorylated AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and cytochrome c oxidase (CCO) gene expression in the rat soleus, suggesting an effect on the AMPK-PGC1α-mitochondrial biogenesis pathway. Furthermore, B-3HK promoted oxidative muscle fiber composition in the gastrocnemius. We also observed a significantly higher level of murine grip strength in the B-3HK group than in the control group. These findings suggest the potential of heat-killed B-3 in promoting muscle hypertrophy and modifying metabolic functions, possibly through the Akt and AMPK pathways, respectively.