Influence of Food Restriction Combined with Voluntary Running on Bone Morphology and Strength in Male Rats

Athletes, in particular endurance athletes and dancers, are chronically exposed to a state of low energy availability due to insufficient dietary energy intake and massive exercise energy expenditure. Low energy availability sometimes causes bone fragility, thereby increasing the risk of bone disorders. Although the decrease in energy availability shows no sexual dimorphism, epidemiological studies have reported that bone disorders are less frequent in male athletes than in female athletes. We hypothesized that bone tissue was not affected by low energy availability in males. The purpose of this study was to examine the influence of food restriction combined with voluntary running training on bone morphology and strength in adult male rats. Fourteen-week-old male Sprague–Dawley rats were divided randomly into four groups: control (C) group, food restriction (R) group, exercise (Ex) group, and food restriction plus exercise (REx) group. For the R and REx groups, 30 % food restriction was carried out in comparison with the C group. Bone strength, bone mineral density (BMD), bone architecture, and bone turnover rate were measured after a 13-week experimental period. Bone strength was not significantly lower in the REx group compared with the C group. BMD and trabecular bone volume showed no difference among groups. These findings indicate that bone morphology and strength were little affected by food restriction combined with exercise training in adult male rats.     

The serum vaspin levels are reduced in Japanese chronic hemodialysis patients

Background

Visceral adipose tissue-derived serine proteinase inhibitor (vaspin) is an adipokine identified in genetically obese rats that correlates with insulin resistance and obesity in humans. Recently, we found that 7% of the Japanese population with the minor allele sequence (A) of rs77060950 exhibit higher levels of serum vaspin. We therefore evaluated the serum vaspin levels in Japanese chronic hemodialysis patients.

Methods

Healthy Japanese control volunteers (control; n?=?95, 49.9±6.91?years) and Japanese patients undergoing hemodialysis therapy (HD; n?=?138, 51.4±10.5?years) were enrolled in this study, and serum samples were subjected to the human vaspin RIA system.

Results

The measurement of the serum vaspin levels demonstrated that a fraction of control subjects (n?=?5) and HD patients (n?=?11) exhibited much higher levels (> 10?ng/ml; Vaspin_High group), while the rest of the population exhibited lower levels (< 3?ng/ml; Vaspin_Low group). By comparing the patients in the Vaspin_Low group, the serum vaspin levels were found to be significantly higher in the control subjects (0.87±0.24?ng/ml) than in the HD patients (0.32±0.15?ng/ml) (p?<?0.0001). In the stepwise regression analyses, the serum creatinine and triglyceride levels were found to be independently and significantly associated with the vaspin concentrations in all subjects.

Conclusions

The creatinine levels are negatively correlated with the serum vaspin levels and were significantly reduced in the Japanese HD patients in the Vaspin_Low group.

     

Surgery for a gastroenteropancreatic neuroendocrine tumor (GEPNET) in multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited endocrine tumor syndrome characterized by tumor development in various endocrine organs such as the parathyroid, endocrine pancreas, anterior pituitary and adrenal cortex. The first extensive database for Asian patients with MEN1 was established by the MEN Consortium of Japan. Although the clinical features of Japanese patients with MEN1 are similar to those from Western countries, there are several characteristic differences between them. In particular, gastroenteropancreatic neuroendocrine tumor (GEPNET) is seen in approximately 60 % of patients with MEN1 in Japan. Although its development is the strongest prognostic factor in patients with MEN1, the characteristics of MEN1-associated GEPNET still remain unclear. This is especially true for the differences in clinical features of GEPNET with and without MEN1. Improved long-term survival is obtained by curative surgery for patients with MEN1-associated GEPNET. The current surgical indications are expanding even in patients with hepatic metastases because of the improved surgical outcome. This article reviews the clinical characteristics in these patients with a particular focus on surgery, diagnosis, surgical indications, surgical method, and surgical outcome.     

Degree of biological apatite c‐axis orientation rather than bone mineral density controls mechanical function in bone regenerated using recombinant bone morphogenetic protein‐2

The aim of the present study was to assess the bone regeneration process in defects introduced into rabbit long bones, which were regenerated with controlled release of recombinant bone morphogenetic protein‐2 (rBMP‐2). The orientation of the biological apatite (BAp) c‐axis and bone mineral density (BMD) were compared as predictors of bone mechanical function. A 20‐mm‐long defect was introduced in rabbit ulnas, and 17 µg of rBMP‐2 was controlled‐released into the defect using a biodegradable gelatin hydrogel as the carrier. In the bone regeneration process, two characteristic phases may have been governed by different factors. First, new bone formation actively occurred, filling the bone defect with newly formed bone tissue and increasing the BMD. This process was regulated by the strong osteoinductive capacity of rBMP‐2. Second, after filling of the defect and moderate BMD restoration, preferential BAp c‐axis orientation began to increase, coincident with initiation of remodeling. In addition, the BAp c‐axis orientation, rather than BMD, was strongly correlated with Young's modulus, an important index of bone mechanical function, particularly in the later stage of bone regeneration. Thus, preferential BAp c‐axis orientation is a strong determinant and predictor of the mechanical function of tissue‐engineered bone. Therefore, analysis of BAp preferential c‐axis orientation in addition to measurement of BMD is crucial in assessment of bone mechanical function. © 2013 American Society for Bone and Mineral Research © 2013 American Society for Bone and Mineral Research