Resistance Training's Ability to Prevent Cancer-induced Muscle Atrophy Extends Anabolic Stimulus.

PURPOSE: This study aimed to determine the role of mammalian target of rapamycin (mTORC1) activation and catabolic markers in resistance training's (RT) antiatrophy effect during cachexia-induced muscle loss. METHODS: Myofiber atrophy was induced by injecting Walker 256 tumor cells into rats exposed or not exposed to the RT protocol of ladder climbing. The role of RT-induced anabolic stimulation was investigated in tumor-bearing rats with the mTORC1 inhibitor rapamycin, and cross-sectional areas of skeletal muscle were evaluated to identify atrophy or hypertrophy. Components of the mTORC1 and ubiquitin-proteasome pathways were assessed by real-time polymerase chain reaction or immunoblotting. RESULTS: Although RT prevented myofiber atrophy and impaired the strength of tumor-bearing rats, in healthy rats, it promoted activated mTORC1, as demonstrated by p70S6K's increased phosphorylation and myofiber's enlarged cross-sectional area. However, RT promoted no changes in the ratio of p70S6K to phospho-p70S6K protein expression while prevented myofiber atrophy in tumor-bearing rats. Beyond that, treatment with rapamycin did not preclude RT's preventive effect on myofiber atrophy in tumor-bearing rats. Thus, RT's ability to prevent cancer-induced myofiber atrophy seems to be independent of mTORC1's and p70S6K's activation. Indeed, RT's preventive effect on cancer-induced myofiber atrophy was associated with its capacity to attenuate elevated tumor necrosis factor α and interleukin 6 as well as to prevent oxidative damage in muscles and an elevated abundance of atrogin-1. CONCLUSIONS: By inducing attenuated myofiber atrophy independent of mTORC1's signaling activation, RT prevents muscle atrophy during cancer by reducing inflammation, oxidative damage, and atrogin-1 expression.

Bone regeneration in osteoporotic conditions: healing of subcritical-size calvarial defects in the ovariectomized rat.

PURPOSE: Osteoporosis is a pathologic condition characterized by low bone mass and changes in the microarchitecture of the bone tissue. Although compromised bone strength and increased susceptibility to fracture have been established, little is known regarding the process of bone regeneration in osteoporotic conditions. Accordingly, this study sought to evaluate the intramembranous bone regeneration process in an ovariectomized rat model following the establishment of calvarial subcritical-size defects (sCSDs). MATERIALS AND METHODS: Calvarial sCSDs were established in rats that had been ovariectomized (Ovx) or sham-operated 2 months previously and left to heal, unfilled, for 6 months. Bone regeneration was assessed by radiographic, densitometric, histologic, and histometric analyses. RESULTS: Radiologic and histologic analyses showed reduced new bone formation in calvarial sCSDs in Ovx animals in comparison to sham animals. Densitometric analysis of radiologic images and histometric analysis showed significant quantitative differences between groups that converged to substantiate reduced bone regeneration in Ovx animals. CONCLUSIONS: The intramembranous ossification process is impaired in the Ovx rat model. This may suggest an impairment of the bone regeneration process in clinical conditions of postmenopausal osteoporosis and highlight the requirement for selective bone regenerative strategies in affected patients.

Analysis of salivary peptides using HPLC-electrospray mass spectrometry.

Salivary peptides are involved in a wide range of functions constituting the first line of defence of oral cavity and precursors of dental pellicle formation. The presence of mucins in saliva makes difficult the analysis of the proteic content. This is due mainly to aggregation phenomenon between mucins and other high molecular weight glycoproteins and salivary proteins. Considering the importance of salivary peptides in biological functions, we have evaluated the influence of four different extraction methodologies on the separation and identification of these proteins by HPLC-MS. Based on their molecular weight, we identified a total of 22 peptides when extraction was performed using a solution of guanidine (6 m), compared with 14 peptides identified when saliva is acidified with TFA, which is an often used procedure. Our results also show the presence of mucin bind peptides, which include statherin, PRP1, PRP3, Histatin 1 and Histatin 5.