Save life and improve quality: report from the 5th Congress of International Society for Hemodialysis

β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

Supplements and naturally occurring nutraceuticals effective for maintenance or enhancement of skeletal muscle mass are expected to contribute to prevention of decreased mobility and increased risk of developing metabolic diseases. However, information about available food components remains widely unavailable. In the present study, we investigated the effects of dietary β-carotene on the quantity and quality of skeletal muscle under physiological conditions. Male ddY mice (8 wk old) were orally administered β-carotene (0.5 mg once daily) for 14 d. Dietary β-carotene had no influence on body weight, but increased the soleus muscle/body weight ratio. The cross-sectional area (CSA) in muscle fibers of the soleus muscle was increased, indicating that administration of β-carotene induces muscle hypertrophy. In the soleus muscle of the β-carotene-administered mice, twitch force tended to be increased (p=0.06) and tetanic force was significantly increased, whereas specific force (force per CSA) remained unchanged. Dietary β-carotene increased the mRNA level of insulin-like growth factor 1 (Igf-1) as its splicing variant Igf-1ea, but had no influence on the liver Igf-1 mRNA level or serum IGF-1 level. β-Carotene promoted protein synthesis in the soleus muscle and reduced levels of ubiquitin conjugates, but had no influence on the mRNA levels of two atrogenes, Atrogin-1 and Murf1. On the other hand, β-carotene had no influence on the processing of the autophagy marker protein light chain 3. These results indicate that in mice, administration of β-carotene increases mass and induces functional hypertrophy in the soleus muscle, perhaps by promoting IGF-1-mediated protein synthesis and by reducing ubiquitin-mediated protein degradation.

Effects of three blood purification methods on serum fibroblast growth factor-23 clearance in patients with hyperphosphatemia undergoing maintenance hemodialysis

The aim of the present study was to investigate the effects of three blood purification methods on fibroblast growth factor-23 (FGF-23) clearance in patients with hyperphosphatemia undergoing maintenance hemodialysis (MHD). In addition, the correlation between serum FGF-23 and phosphorus (Pi) levels and the clinical implications were identified. Sixty-five MHD patients with hyperphosphatemia were randomly divided into three groups: Hemodialysis, HD (n=23); hemodiafiltration, HDF (n=21); and hemodialysis+hemoperfusion, HD+HP (n=21) groups. Serum Pi, FGF-23, blood urea nitrogen, serum creatinine and associated bio-marker levels were measured prior to and following treatment. The expression level of serum FGF-23 was observed to be positively correlated with Pi (r=0.45, P<0.01). The three blood purification methods that were adopted for the present study exhibited significant and effective clearance of serum Pi (P<0.05). The post-treatment serum FGF-23 levels were significantly decreased in the HDF and HD+HP groups (P<0.05). Therefore, HDF may be an effective method for clearing serum FGF-23 in MHD patients exhibiting hyperphosphatemia.