Differential Effects of 25-Hydroxyvitamin D3 versus 1α 25-Dihydroxyvitamin D3 on Adipose Tissue Browning in CKD-Associated Cachexia

Patients with chronic kidney disease (CKD) often have low serum concentrations of 25(OH)D3 and 1,25(OH)2D3. We investigated the differential effects of 25(OH)D3 versus 1,25(OH)2D3 repletion in mice with surgically induced CKD. Intraperitoneal supplementation of 25(OH)D3 (75 μg/kg/day) or 1,25(OH)2D3 (60 ng/kg/day) for 6 weeks normalized serum 25(OH)D3 or 1,25(OH)2D3 concentrations in CKD mice, respectively. Repletion of 25(OH)D3 normalized appetite, significantly improved weight gain, increased fat and lean mass content and in vivo muscle function, as well as attenuated elevated resting metabolic rate relative to repletion of 1,25(OH)2D3 in CKD mice. Repletion of 25(OH)D3 in CKD mice attenuated adipose tissue browning as well as ameliorated perturbations of energy homeostasis in adipose tissue and skeletal muscle, whereas repletion of 1,25(OH)2D3 did not. Significant improvement of muscle fiber size and normalization of fat infiltration of gastrocnemius was apparent with repletion of 25(OH)D3 but not with 1,25(OH)2D3 in CKD mice. This was accompanied by attenuation of the aberrant gene expression of muscle mass regulatory signaling, molecular pathways related to muscle fibrosis as well as muscle expression profile associated with skeletal muscle wasting in CKD mice. Our findings provide evidence that repletion of 25(OH)D3 exerts metabolic advantages over repletion of 1,25(OH)2D3 by attenuating adipose tissue browning and muscle wasting in CKD mice.

Breast muscle myopathies in broiler: mechanism, status and their impact on meat quality

Almost a decade ago, the sudden rise of breast muscle defects in fast-growing commercial broiler breeds challenged the broiler production industry and meat scientists to address the issue of these novel muscle abnormalities. After that, a widespread hypothesis showing a correlation between high muscle yield and incidence of these muscle myopathies got much acceptance from the research community. Increased muscle hypertrophy and unbalanced growth of connective tissues lead to an inadequate blood supply that ultimately causes hypoxia in muscle fibers. Reduced blood vascular density in muscle fibers induces oxidative stress and mitochondrial dysfunction, leading to muscle fibrosis, lipidosis and myodegeneration. Along with physical changes, the myopathic muscles exhibit poor sensory properties, abnormal texture properties and a low nutritional profile. As these myopathies alter meat’s physical appearance, they have a negative impact on customer’s behavior and preference. A better production environment with proper dietary supplementation with balanced breeding strategies can minimize the incidence of muscle myopathies in broiler chicken. This review aims to address the underlying mechanism behind these myopathies and their impact on poultry meat quality, including nutritional value and consumer behavior. It describes the link between genetic and non-genetic elements influencing myopathies, along with the strategies to minimize the occurrence of breast muscle myopathies.

1425 Surgical Management of a Long-Standing Temporomandibular Joint Dislocation: A Case Report

Background Temporomandibular joint (TMJ) dislocation is a common presentation to Oral & Maxillofacial Surgery. In most cases, the condylar head is displaced anterior to the articular eminence and can be relocated by closed reduction. Severe dislocation into the infratemporal fossa is uncommon. Long-standing dislocation is rare and makes closed reduction difficult to achieve. Presentation A 60-year-old female presented to the outpatient clinic with long-standing bilateral TMJ dislocation which onset months prior following a seizure. Both condylar heads could be palpated superior to the zygomatic arches and could not be reduced under local anaesthetic. Mandibular range of movement was severely limited and creating an oral seal was not possible, affecting speech function. There was a history of discomfort and declining oral intake. Computed tomography revealed both condyles were displaced into the infratemporal fossa. Management The patient and family expressed a desire to avoid risk of damage to the facial nerve and therefore surgery was limited to an intra-oral approach only. Closed reduction was impossible due to the degree of muscle fibrosis present. Bilateral coronoidectomies were performed under a short general anaesthetic which immediately improved range of movement. Full articulation and occlusion were achieved by performing bilateral condylotomies. Outcome The patient was reviewed by video consultation 2 weeks later and had recovered well. They reported good masticatory function and improved dietary intake. No additional physiotherapy or surgical input was required, and they have been discharged from further review.

Characteristics of the Passive Muscle Stiffness of the Vastus Lateralis: A Feasibility Study to Assess Muscle Fibrosis

Skeletal muscle fibrosis occurs with aging and has been suggested to impair muscle performance, thereby decreasing quality of life. Recently, muscle stiffness, a surrogate measure of muscle fibrosis, was noninvasively quantified as the shear modulus using ultrasound shear wave elastography (SWE) in humans. We aimed to investigate thigh muscle stiffness in females and males, respectively, across a broad range of ages by using SWE. Eighty-six community-dwelling Japanese people who were aged 30 to 79 years and did not regularly exercise participated in this study. The vastus lateralis (VL) shear modulus was measured at three different knee joint angles: full extension, 90° of flexion, and full flexion. There were no significant main effects of sex or age on the VL shear modulus in full extension or 90° of flexion of the knee. However, the VL shear modulus in knee full flexion was significantly smaller in females than in males and increased with age from 47.9 years. The results suggest that the accelerated increase in VL stiffness that occurs after an individual passes their late 40s may be an important therapeutic target for developing effective treatments and programs that preserve and improve quality of life.

Satellite Cells Are Activated In A Rat Model of Radiation-Induced Muscle Fibrosis

Background: Radiation-induced muscle fibrosis is a long-term side effect of radiotherapy that significantly affect the quality of life and even reduces the survival of cancer patients. We have demonstrated that radiation induces satellite cell (SC) activation at the molecular level; however, cellular evidence in a rat model of radiation-induced muscle fibrosis was lacking. In this study, we evaluated SC activation in vivo and investigated whether radiation affects the proliferation and differentiation potential of SCs in vitro. Methods: For in vivo studies, Sprague-Dawley rats were randomly divided into six groups (n = 6 per group): a non-irradiated control group and 90 Gy-1 w, 90 Gy-2 w, 90 Gy-4 w, 90 Gy-12 w, and 90 Gy-24 w groups.Left groin area of the rats received a single dose of irradiation and rectus femoris tissues were collected in the indicated weeks. Fibrosis, apoptosis, and autophagy were evaluated by Masson’s trichrome staining, TUNEL staining, and electron microscopy, respectively. SC activation and central nuclear muscle fibers were evaluated by immunofluorescence staining and hematoxylin and eosin staining. IL-1β concentrations in serum and irradiated muscle tissue samples were determined by ELISA. For in vitro studies, SCs were isolated from rats with radiation-induced muscle fibrosis and their proliferation and differentiation were evaluated by immunofluorescence staining.Results: In vivo, fibrosis increased over time following irradiation. Apoptosis and autophagy levels, IL-1β concentrations in serum and irradiated skin tissues, and the numbers of SCs and central nuclear muscle fibers were increased in the irradiated groups when compared with control group. In vitro, cultured SCs from irradiated muscle were positive for proliferation marker Pax7, and differentiated SCs were positive for myogenic differentiation marker MyHC.Conclusion: This study provided cellular evidence of SC activation and proliferation in rats with radiation-induced muscle fibrosis. Radiation does not affect the proliferation and differentiation potential of SCs in vitro.