Muscle fiber morphometry and physicochemical characteristics of the Longissimus thoracis muscle of hair male lambs fed zilpaterol hydrochloride and implanted with steroids.

Muscle fiber morphometry and physicochemical characteristics were evaluated in LT muscles obtained from entire male lambs treated with zilpaterol hydrochloride (ZH, 0 and 0.15 mg/kg body weight) and/or steroidal implant (SI, with and without trenbolone acetate/estradiol). ZH and SI acted synergistically to increase LT area, type-IIb fiber cross-sectional area and soluble collagen content, likewise to decrease metmyoglobin concentration and insoluble collagen content. Ash content and ultimate pH showed a decrease due to an antagonistic effect between ZH and SI. Content of total collagen, protein, fat, moisture, oxidized lipids and water-holding capacity were unaffected by ZH and SI. Supplemental ZH, but not SI, decreased all color parameters and tended to increase shear force. Overall, the SI implantation of male lambs followed by a ZH supplementation promoted greater LT hypertrophy, without affecting protein and fat content, and physicochemical characteristics in their meat.

PIEZO2: A Novel Molecule Involved in the Development of AIS.

STUDY DESIGN: A case-control study. OBJECTIVE: This study aimed to investigate the potential role of PIEZO2 gene in the development of AIS. SUMMARY OF BACKGROUND DATA: Mutations of PIEZO2 gene have been reported to be associated with progressive scoliosis and impaired proprioception. Previous studies showed that patients with AIS may have impaired proprioception. However, there is lack of knowledge concerning the mechanism underlying the proprioception of AIS patients and the role of PIEZO2 gene in the etiology of AIS. METHODS: Proprioception tests were performed in both AIS patients and age-matched healthy controls. Based on the falling risk scores, AIS patients were divided into impaired proprioception group and unimpaired proprioception group. Paraspinal muscle was collected from 34 AIS patients during surgery. The tissue expression of PIEZO2 was compared between the impaired group and the unimpaired group. In addition, the average number of muscle fibers in the muscle spindle was compared between the two groups. RESULTS: Proprioception test showed that patients had significantly higher falling index (41.7 ±â€Š16.5 vs. 11.3 ±â€Š8.3, P = 0.004). In addition, the expression of PIEZO2 gene was remarkably decreased in the impaired group (0.51 ±â€Š0.24 vs. 1.00 ±â€Š0.33, P = 0.04). The average number of muscle fibers in the muscle spindle was significantly decreased in AIS patients of the impaired group than those of the unimpaired group (2.2 ±â€Š1.3 vs. 3.5 ±â€Š2.1, P = 0.04). PIEZO2 expression level was remarkably correlated with the average number of muscle fibers in the muscle spindle (r = 0.352, P = 0.04). CONCLUSION: Proprioception is remarkably impaired in patients with AIS. Abnormal expression of PIEZO2 may play a role in AIS via altered proprioception and number of muscle fibers in the muscle spindles. Further investigation is warranted to illustrate the mechanism regulating PIEZO2 expression in AIS. LEVEL OF EVIDENCE: 4.

Change of fatty acid composition of the lumbar longissimus during the final stage of fattening in the Japanese Black cattle.

Consideration of the shortened fattening period seems to be worthwhile for the realization of profitable beef production. In this study, change of fatty acid composition of the lumbar longissimus during the final stage of fattening was investigated in Japanese Black cattle. Each of 110 fattening animals was sampled three times: the initial two samples were taken by biopsy (25.7 months and 27.5 months on average) and the final one was from carcasses (29.9 months on average). Preliminary analysis indicated that removing muscle tissues from the constant body position of the living animals should be essential for sampling. Average monounsaturated fatty acids (MUFA) at three sampling points were 58.1%, 58.5% and 60.5%, and the differences of the third sampling with the first and second samplings were significant. Both in steers and heifers, MUFA also increased as the fattening stage proceeded, and MUFA of the heifers at all the sampling points were significantly higher than those of the steers. The increasing rate of MUFA rose from 0.21 percentage points (pp)/month at period 1 (from the first sampling to the second sampling) to 0.84 pp/month at period 2 (from the second sampling to the slaughter).

Multifidus Muscle Changes After Back Injury Are Characterized by Structural Remodeling of Muscle, Adipose and Connective Tissue, but Not Muscle Atrophy: Molecular and Morphological Evidence.

STUDY DESIGN: Longitudinal case-controlled animal study. OBJECTIVE: To investigate putative cellular mechanisms to explain structural changes in muscle and adipose and connective tissues of the back muscles after intervertebral disc (IVD) injury. SUMMARY OF BACKGROUND DATA: Structural back muscle changes are ubiquitous with back pain/injury and considered relevant for outcome, but their exact nature, time course, and cellular mechanisms remain elusive. We used an animal model that produces phenotypic back muscle changes after IVD injury to study these issues at the cellular/molecular level. METHODS: Multifidus muscle was harvested from both sides of the spine at L1-L2 and L3-L4 IVDs in 27 castrated male sheep at 3 (n = 10) or 6 (n = 17) months after a surgical anterolateral IVD injury at both levels. Ten control sheep underwent no surgery (3 mo, n = 4; 6 mo, n = 6). Tissue was harvested at L4 for histological analysis of cross-sectional area of muscle and adipose and connective tissue (whole muscle), plus immunohistochemistry to identify proportion and cross-sectional area of individual muscle fiber types in the deepest fascicle. Quantitative polymerase chain reaction measured gene expression of typical cytokines/signaling molecules at L2. RESULTS: Contrary to predictions, there was no multifidus muscle atrophy (whole muscle or individual fiber). There was increased adipose and connective tissue (fibrotic proliferation) cross-sectional area and slow-to-fast muscle fiber transition at 6 but not 3 months. Within the multifidus muscle, increases in the expression of several cytokines (tumor necrosis factor α and interleukin-1ß) and molecules that signal trophic/atrophic processes for the 3 tissue types (e.g., growth factor pathway [IGF-1, PI3k, Akt1, mTOR], potent tissue modifiers [calcineurin, PCG-1α, and myostatin]) were present. CONCLUSION: This study provides cellular evidence that refutes the presence of multifidus muscle atrophy accompanying IVD degeneration at this intermediate time point. Instead, adipose/connective tissue increased in parallel with the expression of the genes that provide putative mechanisms for multifidus structural remodeling. This provides novel targets for pharmacological and physical interventions. LEVEL OF EVIDENCE: N/A.