The Role of Mitochondrial and Redox Alterations in the Skeletal Myopathy Associated with Chronic Kidney Disease

Significance: An estimated 700 million people globally suffer from chronic kidney disease (CKD). In addition to increasing cardiovascular disease risk, CKD is a catabolic disease that results in a loss of muscle mass and function, which are strongly associated with mortality and a reduced quality of life. Despite the importance of muscle health and function, there are no treatments available to prevent or attenuate the myopathy associated with CKD. Recent Advances: Recent studies have begun to unravel the changes in mitochondrial and redox homeostasis within skeletal muscle during CKD. Impairments in mitochondrial metabolism, characterized by reduced oxidative phosphorylation, are found in both rodents and patients with CKD. Associated with aberrant mitochondrial function, clinical and preclinical findings have documented signs of oxidative stress, although the molecular source and species are ill-defined. Critical Issues: First, we review the pathobiology of CKD and its associated myopathy, and we review muscle cell bioenergetics and redox biology. Second, we discuss evidence from clinical and preclinical studies that have implicated the involvement of mitochondrial and redox alterations in CKD-associated myopathy and review the underlying mechanisms reported. Third, we discuss gaps in knowledge related to mitochondrial and redox alterations on muscle health and function in CKD. Future Directions: Despite what has been learned, effective treatments to improve muscle health in CKD remain elusive. Further studies are needed to uncover the complex mitochondrial and redox alterations, including post-transcriptional protein alterations, in patients with CKD and how these changes interact with known or unknown catabolic pathways contributing to poor muscle health and function. Antioxid. Redox Signal. 38, 318-337.

Critical illness-associated weakness and related motor disorders

Weakness of limb and respiratory muscles that occurs in the course of critical illness has become an increasingly common and serious complication of adult and pediatric intensive care unit patients and a cause of prolonged ventilatory support, morbidity, and prolonged hospitalization. Two motor disorders that occur singly or together, namely critical illness polyneuropathy and critical illness myopathy, cause weakness of limb and of breathing muscles, making it difficult to be weaned from ventilatory support, commencing rehabilitation, and extending the length of stay in the intensive care unit, with higher rates of morbidity and mortality. Recovery can take weeks or months and in severe cases, and may be incomplete or absent. Recent findings suggest an improved prognosis of critical illness myopathy compared to polyneuropathy. Prevention and treatment are therefore very important. Its management requires an integrated team approach commencing with neurologic consultation, creatine kinase (CK) measurement, detailed electrodiagnostic, respiratory and neuroimaging studies, and potentially muscle biopsy to elucidate the etiopathogenesis of the weakness in the peripheral and/or central nervous system, for which there may be a variety of causes. These tenets of care are being applied to new cases and survivors of the coronavirus-2 disease pandemic of 2019. This chapter provides an update to the understanding and approach to critical illness motor disorders.

Anti-signal Recognition Particle Antibody-positive Immune-mediated Myopathy after mRNA-1273 SARS-CoV-2 Vaccination

A 26-year-old Japanese woman developed a fever, myalgia and gait disturbance one day after receiving the second dose of the mRNA-1273 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. A neurological examination revealed symmetrical weakness and myalgia in proximal lower limbs, and a blood examination showed prominent elevation of creatinine kinase. Magnetic resonance imaging (MRI) revealed a high signal intensity in the thigh muscles on short-tau inversion recovery images, and antibody testing revealed positive findings for anti-signal recognition particle (SRP) antibody. Thus, anti-SRP antibody-positive immune-mediated myopathy was diagnosed. We initiated immunotherapy, and she was ultimately able to walk stably.

COVID-19 associated myopathy

PURPOSE OF REVIEW

The global spread of severe acute respiratory syndrome coronavirus 2 resulted in many cases of acute and postacute muscular symptoms. In this review, we try to decipher the potential underlying pathomechanisms and summarize the potential links between viral infection and muscle affection.

RECENT FINDINGS

Disregarding single case studies that do not allow safe conclusions due to the high number of infections, histopathological evidence of myositis has only been reported in deceased individuals with severe COVID-19. Postacute myalgia and weakness seem to occur in a subset of patients up to one year after initial infection, reminiscent of postinfectious syndromes (PIS) described in prior epidemics and pandemics of the past.

SUMMARY

COVID-19 associated myopathy likely comprises different entities with heterogeneous pathomechanisms. Individual factors such as disease severity and duration, age, sex, constitutional susceptibilities, and preexisting conditions are important to consider when formulating a diagnosis. Persisting symptoms show overlapping features with PIS or postintensive care syndrome. In lack of strong evidence for a direct infection of myocytes, inflammatory myopathies associated with COVID-19 are presumably immune-mediated. Differential diagnosis of rheumatological and nonmuscular neurological origin coinciding with the infection need to be considered, due to the extremely high numbers of newly occurring infections the last 2 years.

[Sibling cases of four and a half LIM domains 1 (FHL1) myopathy who developed respiratory failure without apparent limb weakness]

A 60-year-old man developed dyspnea without apparent limb weakness. He had cardiomyopathy in his 30s and was treated for chronic heart failure since 42. He was diagnosed as having four and a half LIM domains 1 (FHL1) mutation at 53 following the same diagnosis of his younger brother. He was first admitted to the cardiology department for possible worsening of chronic cardiac failure. Blood gas analysis showing respiratory acidosis prompted his treatment with a respirator. Neurological examination revealed that he had mild weakness limited to the shoulder girdle muscles and contracture at jaw, spine, elbows and ankles. Skeletal muscle CT showed truncal atrophy. He, as well as his younger brother, was diagnosed with FHL1 myopathy resulting in ventilation failure and was discharged after successful weaning from the respirator in the daytime. The present sibling cases are the first with FHL1 mutation to develop respiratory failure without limb weakness and suggest that FHL1 myopathy as a differentially diagnosis of hereditary myopathies with early respiratory failure.

Electrical stimulated GLUT4 signalling attenuates critical illness-associated muscle wasting

BACKGROUND

Critical illness myopathy (CIM) is a debilitating condition characterized by the preferential loss of the motor protein myosin. CIM is a by-product of critical care, attributed to impaired recovery, long-term complications, and mortality. CIM pathophysiology is complex, heterogeneous and remains incompletely understood; however, loss of mechanical stimuli contributes to critical illness-associated muscle atrophy and weakness. Passive mechanical loading and electrical stimulation (ES) therapies augment muscle mass and function. While having beneficial outcomes, the mechanistic underpinning of these therapies is less known. Therefore, here we aimed to assess the mechanism by which chronic supramaximal ES ameliorates CIM in a unique experimental rat model of critical care.

METHODS

Rats were subjected to 8 days of critical care conditions entailing deep sedation, controlled mechanical ventilation, and immobilization with and without direct soleus ES. Muscle size and function were assessed at the single cell level. RNAseq and western blotting were employed to understand the mechanisms driving ES muscle outcomes in CIM.

RESULTS

Following 8 days of controlled mechanical ventilation and immobilization, soleus muscle mass, myosin : actin ratio, and single muscle fibre maximum force normalized to cross-sectional area (CSA; specific force) were reduced by 40-50% (P < 0.0001). ES significantly reduced the loss of soleus muscle fibre CSA and myosin : actin ratio by approximately 30% (P < 0.05) yet failed to effect specific force. RNAseq pathway analysis revealed downregulation of insulin signalling in the soleus muscle following critical care, and GLUT4 trafficking was reduced by 55% leading to an 85% reduction of muscle glycogen content (P < 0.01). ES promoted phosphofructokinase and insulin signalling pathways to control levels (P < 0.05), consistent with the maintenance of GLUT4 translocation and glycogen levels. AMPK, but not AKT, signalling pathway was stimulated following ES, where the downstream target TBC1D4 increased 3 logFC (P = 0.029) and AMPK-specific P-TBC1D4 levels were increased approximately two-fold (P = 0.06). Reduction of muscle protein degradation rather than increased synthesis promoted soleus CSA, as ES reduced E3 ubiquitin proteins, Atrogin-1 (P = 0.006) and MuRF1 (P = 0.08) by approximately 50%, downstream of AMPK-FoxO3.

CONCLUSIONS

ES maintained GLUT4 translocation through increased AMPK-TBC1D4 signalling leading to improved muscle glucose homeostasis. Soleus CSA and myosin content was promoted through reduced protein degradation via AMPK-FoxO3 E3 ligases, Atrogin-1 and MuRF1. These results demonstrate chronic supramaximal ES reduces critical care associated muscle wasting, preserved glucose signalling, and reduced muscle protein degradation in CIM.

Does COVID-19 increase the incidence of spontaneous rectus sheath hematoma?

BACKGROUND

The COVID-19 pandemic started to affect Turkey in March 2020. In this study, we retrospectively investigated spontaneous rectus sheath hematoma (S-RSH) in patients with COVID-19 presenting with acute abdominal pain during the ongoing pandemic.

METHODS

The demographic characteristics, laboratory findings, length of hospital stay, and treatment processes of COVID-19 cases with S-RSH detected between March and December 2020 were recorded. The rectus sheath hematoma diagnosis of the patients was made using abdominal computed tomography, and the patients were followed up. Low-molecular-weight heparin treatment, which was initiated upon admission, was continued during the follow-up.

RESULTS

S-RSH was detected in 13 out of 220 patients with COVID-19 who were referred to general surgery for consultation due to acute abdominal pain. The mean age of these patients was 78±13 years, and the female-to-male ratio was 1.6. Mechanical ven-tilation support was applied to three patients, all of whom were followed up in the intensive care unit. Two patients died for reasons independent of rectus sheath hematoma during their treatment. Among the laboratory findings, the activated partial thromboplastin time (aPTT) values did not deviate from the normal range. While there was no correlation between the international normalized ratio (INR) and aPTT (p>0.01), a significant correlation was found between INR and interleukin-6 (IL-6) (p<0.002). None of the patients required surgical or endovascular interventional radiology procedures.

CONCLUSION

In the literature, the incidence of S-RSH in patients presenting with acute abdominal pain is 1.8%. However, in our series, this rate was approximately 3 times higher. Our patients' normal INR and aPTT values suggest that coagulopathy was mostly secondary to endothelial damage. In addition, the significantly higher IL-6 values (p<0.002) indicate the development of vasculitis along with the acute inflammatory process. S-RSH can be more commonly explained the high severity of vasculitis and endothelial damage due to viral infection.

Development and early diagnosis of critical illness myopathy in COVID-19 associated acute respiratory distress syndrome

BACKGROUND

The COVID-19 pandemic has greatly increased the incidence and clinical importance of critical illness myopathy (CIM), because it is one of the most common complications of modern intensive care medicine. Current diagnostic criteria only allow diagnosis of CIM at an advanced stage, so that patients are at risk of being overlooked, especially in early stages. To determine the frequency of CIM and to assess a recently proposed tool for early diagnosis, we have followed a cohort of COVID-19 patients with acute respiratory distress syndrome and compared the time course of muscle excitability measurements with the definite diagnosis of CIM.

METHODS

Adult COVID-19 patients admitted to the Intensive Care Unit of the University Hospital Bern, Switzerland requiring mechanical ventilation were recruited and examined on Days 1, 2, 5, and 10 post-intubation. Clinical examination, muscle excitability measurements, medication record, and laboratory analyses were performed on all study visits, and additionally nerve conduction studies, electromyography and muscle biopsy on Day 10. Muscle excitability data were compared with a cohort of 31 age-matched healthy subjects. Diagnosis of definite CIM was made according to the current guidelines and was based on patient history, results of clinical and electrophysiological examinations as well as muscle biopsy.

RESULTS

Complete data were available in 31 out of 44 recruited patients (mean [SD] age, 62.4 [9.8] years). Of these, 17 (55%) developed CIM. Muscle excitability measurements on Day 10 discriminated between patients who developed CIM and those who did not, with a diagnostic precision of 90% (AUC 0.908; 95% CI 0.799-1.000; sensitivity 1.000; specificity 0.714). On Days 1 and 2, muscle excitability parameters also discriminated between the two groups with 73% (AUC 0.734; 95% CI 0.550-0.919; sensitivity 0.562; specificity 0.857) and 82% (AUC 0.820; CI 0.652-0.903; sensitivity 0.750; specificity 0.923) diagnostic precision, respectively. All critically ill COVID-19 patients showed signs of muscle membrane depolarization compared with healthy subjects, but in patients who developed CIM muscle membrane depolarization on Days 1, 2 and 10 was more pronounced than in patients who did not develop CIM.

CONCLUSIONS

This study reports a 55% prevalence of definite CIM in critically ill COVID-19 patients. Furthermore, the results confirm that muscle excitability measurements may serve as an alternative method for CIM diagnosis and support its use as a tool for early diagnosis and monitoring the development of CIM.

Crohn's Disease Presenting as Metabolic Myopathy: A Case Report

Myopathies associated with systemic diseases results from several different disease processes. Myopathy as the initial presenting symptom in Crohn's disease is a rare presentation. We report a 20-yearr-old lady who presented with a painful proximal myopathy. On examination, she was malnourished with pallor, angular cheilitis, Bitots spots, and bilateral pitting pedal edema. Laboratory evaluation showed iron deficiency anemia, hypoalbuminemia, and very low vitamin D levels with elevated creatine phosphokinase levels. A possibility of osteomalacic metabolic myopathy due to vitamin D deficiency was considered. The malabsorption workup was negative. A colonoscopic biopsy showed noncaseating granulomatous inflammation suggestive of Crohn's disease. With supplementary therapy and specific treatment, she was asymptomatic at 6-months follow-up with no residual neurological deficits. A detailed history and an algorithmic approach will be very useful in making the differential diagnosis in any patient presenting with muscle weakness in myopathy associated with systemic illness.

Approach to the diagnosis of metabolic myopathies

Metabolic myopathies are a diverse group of genetic disorders that result in impaired energy production. They are individually rare and several have received the 'orphan disorder' status. However, collectively they constitute a relatively common group of disorders that affect not only the skeletal muscle but also the heart, liver, and brain among others. Mitochondrial disorders, with a frequency of 1/8000 population, are the commonest cause of metabolic myopathies. Three main groups that cause metabolic myopathy are glycogen storage disorders (GSD), fatty acid oxidation defects (FAOD), and mitochondrial myopathies. Clinically, patients present with varied ages at onset and neuromuscular features. While newborns and infants typically present with hypotonia and multisystem involvement chiefly affecting the liver, heart, kidney, and brain, patients with onset later in life present with exercise intolerance with or without progressive muscle weakness and myoglobinuria. In general, GSDs result in high-intensity exercise intolerance while, FAODs, and mitochondrial myopathies predominantly manifest during endurance-type activity, fasting, or metabolically stressful conditions. Evaluation of these patients comprises a meticulous clinical examination and a battery of investigations which includes- exercise stress testing, metabolic and biochemical screening, electrophysiological studies, neuro-imaging, muscle biopsy, and molecular genetics. Accurate and early detection of metabolic myopathies allows timely counseling to prevent metabolic crises and helps in therapeutic interventions. This review summarizes the clinical features, diagnostic tests, pathological features, treatment and presents an algorithm to diagnose these three main groups of disorders.

[Muscle disease in the adults: when to suspect it?]

Muscle diseases or myopathies have heterogeneous clinical presentations and etiologies. The principal sign is muscular weakness, whose distribution can help diagnostic orientation. Exercise intolerance, even without weakness at rest, can indicate an underlying myopathy. An isolated CK elevation can have multiple causes, but its persistence after a period of rest can point towards a subclinical myopathy. Isolated myalgia, especially at rest, are usually not associated with muscle disease. If the suspicion of myopathy is high, the patient will be assessed by a neurologist trained in muscle disorders, with correlation of clinical and neurophysiological findings, muscle imaging and, if indicated, muscle biopsy and genetic analysis. Cardiac and respiratory assessments are mandatory if a myopathy is suspected.

Prevalence of breast muscle myopathies (spaghetti meat, woody breast, white striping) and associated risk factors in broiler chickens from Ontario Canada

Spaghetti meat (SM), woody breast (WB), and white striping (WS) are myopathies that affect the pectoral muscle of fast-growing broiler chickens. The prevalence and possible risk factors of these myopathies have been reported in other countries, but not yet in Canada. Thus, the objective of this study was to assess the prevalence and risk factors associated with these myopathies in a representative population of Canadian broilers. From May 2019 to March 2020, 250 random breast fillets from each of 37 flocks (total, 9,250) were obtained from two processing plants and assessed for the presence and severity of myopathies. Demographic data (e.g., sex and average live weight), environmental conditions during the grow-out period (e.g., temperature), and husbandry parameters (e.g., vaccination) were collected for each flock. Associations between these factors and the myopathies were tested using logistic regression analyses. The prevalence of SM, severe WB, and mild or moderate WS was 36.3% (95% CI: 35.3–37.3), 11.8% (95% CI: 11.2–12.5), and 96.0% (95% CI: 95.6–96.4), respectively. Most (85.1%) of the fillets showed multiple myopathies. Regression analyses showed that the odds of SM increased with live weight (OR = 1.30, 95% CI 1.01–1.69) and higher environmental temperature during the grow-out period (OR = 1.75, 95% CI 1.31–2.34). The odds of WB increased with live weight (OR = 1.23, 95% CI 1.03–1.47) and when flocks were not vaccinated against coccidia (OR = 1.86, 95% CI 1.51–2.29). This study documents for the first time a high prevalence of myopathies in Ontario broilers, and suggests that these lesions may have a significant economic impact on the Canadian poultry industry. Our results indicate that environmental conditions and husbandry are associated with the development of breast myopathies, in agreement with the current literature. Future studies are needed to determine how risk factors can promote the occurrence of these conditions, in order to implement possible mitigating strategies.

COVID-19-Associated Critical Illness Myopathy with Direct Viral Effects

Coronavirus disease 2019 (COVID-19) severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2 infection) can lead to intensive care unit (ICU) admission and critical illness myopathy (CIM). We examined 3 ICU patients with COVID-19 who required mechanical ventilation for pneumonia and developed CIM. Pathological examination of the skeletal muscle biopsies revealed myopathic changes consistent with CIM, variable inflammation with autophagic vacuoles, SARS-CoV immunostaining + fibers/granules, and electron microscopy findings of mitochondrial abnormalities and coronavirus-like particles. Although mitochondrial dysfunction with compromised energy production is a critical pathogenic mechanism of non-COVID-19-associated CIM, in our series of COVID-19-associated CIM, myopathic changes including prominent mitochondrial damage suggest a similar mechanism and association with direct SARS-CoV-2 muscle infection. ANN NEUROL 2022;91:568-574.

Effect of freezing on the quality of breast meat from broilers affected by White Striping myopathy

The aim of this study was to evaluate possible changes in the quality of chicken breast meat containing white stripes during freezing for 12 mo. Samples of Pectoralis major muscle from male Cobb 500 broilers containing white stripes in moderate and severe degrees were used, as well as samples from a control group (normal - absence of myopathies). Part of the samples (n = 60; n = 20 for each severity degree) were analyzed on the day of collection (beginning) and the rest (n = 240) was frozen (-20°C) for up to 12 mo. At the end of each proposed freezing period (3, 6, 9, and 12 mo), color, pH, water holding capacity, cooking loss, tenderness, lipid oxidation, chemical composition, cholesterol and collagen concentrations, myofibrillary fragmentation, and sarcomere length were analyzed. Microbiological analysis of samples was performed at the beginning and after 12 mo of freezing. Myopathy linked to freezing showed results of increased meat tenderness, with reduction of crude protein and mineral matter and increase of moisture, fat, and cholesterol, without affecting the meat's collagen percentages. However, these variations with the onset of myopathy do not compromise the consumption of broiled chicken breast meat, kept frozen for up to 12 mo.

Immunometabolic signatures predict recovery from thyrotoxic myopathy in patients with Graves' disease

BACKGROUND

Thyroid hormone excess induces protein energy wasting, which in turn promotes muscle weakness and bone loss in patients with Graves' disease. Although most studies have confirmed a relationship between thyrotoxicosis and muscle dysfunction, few have measured changes in plasma metabolites and immune cells during the development and recovery from thyrotoxic myopathy. The aim of this study was to identify specific plasma metabolites and T-cell subsets that predict thyrotoxic myopathy recovery in patients with Graves' disease.

METHODS

One hundred patients (mean age, 40.0 ± 14.2 years; 67.0% female), with newly diagnosed or relapsed Graves' disease were enrolled at the start of methimazole treatment. Handgrip strength and Five Times Sit to Stand Test performance time were measured at Weeks 0, 12, and 24. In an additional 35 patients (mean age, 38.9 ± 13.5 years; 65.7% female), plasma metabolites and immunophenotypes of peripheral blood were evaluated at Weeks 0 and 12, and the results of a short physical performance battery assessment were recorded at the same time.

RESULTS

In both patient groups, methimazole-induced euthyroidism was associated with improved handgrip strength and lower limb muscle function at 12 weeks. Elevated plasma metabolites including acylcarnitines were restored to normal levels at Week 12 regardless of gender, body mass index, or age (P trend <0.01). Senescent CD8⁺ CD28^- CD57⁺ T-cell levels in peripheral blood were positively correlated with acylcarnitine levels (P < 0.05) and decreased during thyrotoxicosis recovery (P < 0.05). High levels of senescent CD8⁺ T cells at Week 0 were significantly associated with small increases in handgrip strength after 12 weeks of methimazole treatment (P < 0.05), but not statistically associated with Five Times Sit to Stand Test performance.

CONCLUSIONS

Restoring euthyroidism in Graves' disease patients was associated with improved skeletal muscle function and performance, while thyroid hormone-associated changes in plasma acylcarnitines levels correlated with muscle dysfunction recovery. T-cell senescence-related systemic inflammation correlated with plasma acylcarnitine levels and was also associated with small increases in handgrip strength.

VCP/p97 inhibitor CB-5083 modulates muscle pathology in a mouse model of VCP inclusion body myopathy

BACKGROUND

Pathogenic gain of function variants in Valosin-containing protein (VCP) cause a unique disease characterized by inclusion body myopathy with early-onset Paget disease of bone and frontotemporal dementia (also known as Multisystem proteinopathy (MSP)). Previous studies in drosophila models of VCP disease indicate treatment with VCP inhibitors mitigates disease pathology. Earlier-generation VCP inhibitors display off-target effects and relatively low therapeutic potency. New generation of VCP inhibitors needs to be evaluated in a mouse model of VCP disease. In this study, we tested the safety and efficacy of a novel and potent VCP inhibitor, CB-5083 using VCP patient-derived myoblast cells and an animal model of VCP disease.

METHODS

First, we analyzed the effect of CB-5083 in patient-derived myoblasts on the typical disease autophagy and TDP-43 profile by Western blot. Next, we determined the maximum tolerated dosage of CB-5083 in mice and treated the 2-month-old VCPR155H/R155H mice for 5 months with 15 mg/kg CB-5083. We analyzed motor function monthly by Rotarod; and we assessed the end-point blood toxicology, and the muscle and brain pathology, including autophagy and TDP-43 profile, using Western blot and immunohistochemistry. We also treated 12-month-old VCPR155H/+ mice for 6 months and performed similar analysis. Finally, we assessed the potential side effects of CB-5083 on retinal function, using electroretinography in chronically treated VCPR155H/155H mice.

RESULTS

In vitro analyses using patient-derived myoblasts confirmed that CB-5083 can modulate expression of the proteins in the autophagy pathways. We found that chronic CB-5083 treatment is well tolerated in the homozygous mice harboring patient-specific VCP variant, R155H, and can ameliorate the muscle pathology characteristic of the disease. VCP-associated pathology biomarkers, such as elevated TDP-43 and p62 levels, were significantly reduced. Finally, to address the potential adverse effect of CB-5083 on visual function observed in a previous oncology clinical trial, we analyzed retinal function in mice treated with moderate doses of CB-5083 for 5 months and documented the absence of permanent ocular toxicity.

CONCLUSIONS

Altogether, these findings suggest that long-term use of CB-5083 by moderate doses is safe and can improve VCP disease-associated muscle pathology. Our results provide translationally relevant evidence that VCP inhibitors could be beneficial in the treatment of VCP disease.

Protective effects of dietary curcumin and astaxanthin against heat-induced ROS production and skeletal muscle injury in male and female C57BL/6J mice

AIMS

This study aimed to: 1) investigate sex differences in heat-induced mitochondrial dysfunction, ROS production, and skeletal muscle injury in mice; 2) evaluate whether curcumin and astaxanthin, alone or together, would prevent those heat-induced changes.

MAIN METHODS

Male and female C57BL/6J mice were treated with curcumin and astaxanthin for 10 days, then exposed to 39.5 °C heat for up to 3 h. Heat-induced hyperthermia, changes in mitochondrial morphology and function, and oxidative damage to skeletal muscle were evaluated.

KEY FINDINGS

Although female mice had a slightly higher basal core body temperature (Tc) than male mice, peak Tc during heat exposure was significantly lower in females than in males. Heat increased ROS levels in skeletal muscle in both sexes; interestingly, the increases in ROS were greater in females than in males. Despite the above-mentioned differences, heat induced similar levels of mitochondrial fragmentation and membrane potential depolarization, caspase 3/7 activation, and injury in male and female skeletal muscle. Individual treatment of curcumin or astaxanthin did not affect basal and peak Tc but prevented heat-induced mitochondrial dysfunction, ROS increases, and apoptosis in a dose-dependent manner. Moreover, a low-dose combination of curcumin and astaxanthin, which individually showed no effect, reduced the heat-induced oxidative damage to skeletal muscle.

SIGNIFICANCE

Both male and female mice can develop mitochondrial dysfunction and oxidative stress in skeletal muscle when exposed to heat stress. High doses of either curcumin or astaxanthin limit heat-induced skeletal muscle injury, but a low-dose combination of these ingredients may increase their efficacy.

Diabetic Bone Disease and Diabetic Myopathy: Manifestations of the Impaired Muscle-Bone Unit in Type 1 Diabetes

Type 1 diabetes is associated with complications affecting muscle and bone, with diabetic bone disease and diabetic myopathy becoming increasingly reported in the past few decades. This review is aimed at succinctly reviewing the literature on the current knowledge regarding these increasingly identified and possibly interconnected complications on the musculoskeletal system. Furthermore, this review summarizes several nonmechanical factors that could be mediating the development and progression of premature musculoskeletal decline in this population and discusses preventative measures to reduce the burden of diabetes on the musculoskeletal system.

Extrapelvic endometriosis located individually in the rectus abdominis muscle: a rare cause of chronic pelvic pain (a case report)

Endometriosis of the rectus abdominis muscle is an extremely rare form of extrapelvic localization of the disease. It is usually iatrogenic and develops after caesarean section or gynecological surgery. Preoperative diagnosis is very difficult and a challenge for gynecologists and surgeons; thus, the diagnosis is histological. The treatment of choice consists of wide local excision of the lesion on healthy margins. We cite a case of isolated endometriosis in the rectus abdominis muscles in a 46-year-old patient with a previous caesarean section, the diagnosis of which was made randomly when performing abdominal total hysterectomy for the treatment of chronic pelvic pain. Histological examination of the surgical specimen confirmed the diagnosis. Simultaneously, the surgical specimen of the uterus and ovaries was free of endometriosis. Postoperatively, the patient mentioned discharge of her symptoms. No further therapeutic intervention was deemed necessary, as it was considered that a complete resection of the endometrial tissue implantation from the muscles of abdominal wall was performed. The present case report lay emphasis on the significant difficulties involved in the preoperative diagnosis of endometriosis of the rectus abdominis muscle. Concurrently, it is pointed out that, despite its rarity, individual extrapelvic endometriosis located in the rectus abdominis muscle should be included among other pathological entities in the differential diagnosis of chronic pelvic pain in women of reproductive age, who gave birth by caesarean section or underwent gynecological surgery with abdominal or laparoscopic access.

Evaluation of Muscle Mass and Stiffness with Limb Ultrasound in COVID-19 Survivors

BACKGROUND

acute illnesses, like COVID-19, can act as a catabolic stimulus on muscles. So far, no study has evaluated muscle mass and quality through limb ultrasound in post-COVID-19 patients.

METHODS

cross sectional observational study, including patients seen one month after hospital discharge for SARS-CoV-2 pneumonia. The patients underwent a multidimensional evaluation. Moreover, we performed dominant medial gastrocnemius ultrasound (US) to characterize their muscle mass and quality.

RESULTS

two hundred fifty-nine individuals (median age 67, 59.8% males) were included in the study. COVID-19 survivors with reduced muscle strength had a lower muscle US thickness (1.6 versus 1.73 cm, p =0.02) and a higher muscle stiffness (87 versus 76.3, p = 0.004) compared to patients with normal muscle strength. Also, patients with reduced Short Physical Performance Battery (SPPB) scores had a lower muscle US thickness (1.3 versus 1.71 cm, p = 0.01) and a higher muscle stiffness (104.9 versus 81.07, p = 0.04) compared to individuals with normal SPPB scores. The finding of increased muscle stiffness was also confirmed in patients with a pathological value (≥ 4) at the sarcopenia screening tool SARC-F (103.0 versus 79.55, p < 0.001). Muscle stiffness emerged as a significant predictor of probable sarcopenia (adjusted OR 1.02, 95% C.I. 1.002 - 1.04, p = 0.03). The optimal ultrasound cut-offs for probable sarcopenia were 1.51 cm for muscle thickness (p= 0.017) and 73.95 for muscle stiffness (p = 0.004).

DISCUSSION

we described muscle ultrasound characteristics in post COVID-19 patients. Muscle ultrasound could be an innovative tool to assess muscle mass and quality in this population. Our preliminary findings need to be confirmed by future studies comparing muscle ultrasound with already validated techniques for measuring muscle mass and quality.

American Ginseng Attenuates Eccentric Exercise-Induced Muscle Damage via the Modulation of Lipid Peroxidation and Inflammatory Adaptation in Males

Exercise-induced muscle damage (EIMD) is characterized by a reduction in functional performance, disruption of muscle structure, production of reactive oxygen species, and inflammatory reactions. Ginseng, along with its major bioactive component ginsenosides, has been widely employed in traditional Chinese medicine. The protective potential of American ginseng (AG) for eccentric EIMD remains unclear. Twelve physically active males (age: 22.4 ± 1.7 years; height: 175.1 ± 5.7 cm; weight: 70.8 ± 8.0 kg; peak oxygen consumption [V˙O2peak] 54.1 ± 4.3 mL/kg/min) were administrated by AG extract (1.6 g/day) or placebo (P) for 28 days and subsequently challenged by downhill (DH) running (−10% gradient and 60% V˙O2peak). The levels of circulating 8-iso-prostaglandin F 2α (PGF2α), creatine kinase (CK), interleukin (IL)-1β, IL-4, IL-10, and TNF-α, and the graphic pain rating scale (GPRS) were measured before and after supplementation and DH running. The results showed that the increases in plasma CK activity induced by DH running were eliminated by AG supplementation at 48 and 72 h after DH running. The level of plasma 8-iso-PGF2α was attenuated by AG supplementation immediately (p = 0.01 and r = 0.53), 2 h (p = 0.01 and r = 0.53) and 24 h (p = 0.028 and r = 0.45) after DH running compared with that by P supplementation. Moreover, our results showed an attenuation in the plasma IL-4 levels between AG and P supplementation before (p = 0.011 and r = 0.52) and 72 h (p = 0.028 and r = 0.45) following DH running. Our findings suggest that short-term supplementation with AG alleviates eccentric EIMD by decreasing lipid peroxidation and promoting inflammatory adaptation.

Muscle involvement with pseudohypertrophy in systemic light chain amyloidosis: Case report

RATIONALE

Muscle pseudohypertrophy is a rare manifestation of light chain amyloidosis (AL) amyloidosis.

PATIENT CONCERNS

A 63-year-old woman presented with a 2-year history of progressive asthenia, macroglossia, dysphonia, cachexia, hypotension, paresthesia, and lower limb muscle hypertrophy.

DIAGNOSIS

Free serum lambda light chains were increased, and fat pad biopsy demonstrated Congo red-positive deposits. Additionally, electromyography showed a myopathic pattern, whereas muscle biopsy revealed amyloid deposits. A diagnosis of λAL with cardiac, renal, nervous system, and skeletal muscle involvement was established.

INTERVENTIONS AND OUTCOMES

The patient received 3 subsequent lines of therapy over the following 23 months, with very slow hematological remission followed by resolution of organ dysfunction.

LESSONS

Despite its rarity, muscle involvement should be considered in patients diagnosed with AL amyloidosis associated with unexplained muscle hypertrophy or weakness associated with macroglossia or elevated troponin T levels in the absence of clear cardiac involvement.