Exercise, mitochondrial dysfunction and inflammasomes in skeletal muscle

In the broad field of inflammation, skeletal muscle is a tissue that is understudied. Yet it represents about 40% of body mass in non-obese individuals and is therefore of fundamental importance for whole body metabolism and health. This article provides an overview of the unique features of skeletal muscle tissue, as well as its adaptability to exercise. This ability to adapt, particularly with respect to mitochondrial content and function, confers a level of metabolic "protection" against energy consuming events, and adds a measure of quality control that determines the phenotypic response to stress. Thus, we describe the particular role of mitochondria in promoting inflammasome activation in skeletal muscle, contributing to muscle wasting and dysfunction in aging, disuse and metabolic disease. We will then discuss how exercise training can be anti-inflammatory, mitigating the chronic inflammation that is observed in these conditions, potentially through improvements in mitochondrial quality and function.

Muscle mitochondrial transplantation can rescue and maintain cellular homeostasis

Mitochondria control cellular functions through their metabolic role. Recent research that has gained considerable attention is their ability to transfer between cells. This has the potential of improving cellular functions in pathological or energy-deficit conditions, but little is known about the role of mitochondrial transfer in sustaining cellular homeostasis. Few studies have investigated the potential of skeletal muscle as a source of healthy mitochondria that can be transferred to other cell types. Thus, we isolated intermyofibrillar mitochondria from murine skeletal muscle and incubated them with host cells. We observed dose- and time-dependent increases in mitochondrial incorporation into myoblasts. This resulted in elongated mitochondrial networks and an enhancement of bioenergetic profile of the host cells. Mitochondrial donation also rejuvenated the functional capacities of the myoblasts when respiration efficiency and lysosomal function were inhibited by complex I inhibitor rotenone and bafilomycin A, respectively. Mitochondrial transfer was accomplished via tunneling nanotubes, extracellular vesicles, gap junctions, and by macropinocytosis internalization. Murine muscle mitochondria were also effectively transferred to human fibroblast cells having mitochondrial DNA mutations, resulting in augmented mitochondrial dynamics and metabolic functions. This improved cell function by diminishing reactive oxygen species (ROS) emission in the diseased cells. Our findings suggest that mitochondria from donor skeletal muscle can be integrated in both healthy and functionally compromised host cells leading to mitochondrial structural refinement and respiratory boost. This mitochondrial trafficking and bioenergetic reprogramming to maintain and revitalize tissue homeostasis could be a useful therapeutic strategy in treating diseases.NEW & NOTEWORTHY In our study, we have shown the potential of mouse skeletal muscle intermyofibrillar mitochondria to be transplanted in myoblasts and human fibroblast cells having mitochondrial DNA mutations. This resulted in an augmentation of mitochondrial dynamics and enhancement of bioenergetic profile in the host cells. Our findings suggest that mitochondria from donor skeletal muscle can be integrated into both healthy and functionally compromised host cells leading to mitochondrial structural refinement and respiratory boost.

Scientific meeting report: International Biochemistry of Exercise 2022

Exercise is one of the only nonpharmacological remedies known to counteract genetic and chronic diseases by enhancing health and improving life span. Although the many benefits of regular physical activity have been recognized for some time, the intricate and complex signaling systems triggered at the onset of exercise have only recently begun to be uncovered. Exercising muscles initiate a coordinated, multisystemic, metabolic rewiring, which is communicated to distant organs by various molecular mediators. The field of exercise research has been expanding beyond the musculoskeletal system, with interest from industry to provide realistic models and exercise mimetics that evoke a whole body rejuvenation response. The 18th International Biochemistry of Exercise conference took place in Toronto, Canada, from May 25 to May 28, 2022, with more than 400 attendees. Here, we provide an overview of the most cutting-edge exercise-related research presented by 66 speakers, focusing on new developments in topics ranging from molecular and cellular mechanisms of exercise adaptations to exercise therapy and management of disease and aging. We also describe how the manipulation of these signaling pathways can uncover therapeutic avenues for improving human health and quality of life.

Regulatory networks controlling mitochondrial quality control in skeletal muscle

The adaptive plasticity of mitochondria within skeletal muscle is regulated by signals converging on a myriad of regulatory networks that operate during conditions of increased (i.e. exercise) and decreased (inactivity, disuse) energy requirements. Notably, some of the initial signals that induce adaptive responses are common to both conditions, differing in their magnitude and temporal pattern, to produce vastly opposing mitochondrial phenotypes. In response to exercise, signaling to PGC-1α and other regulators ultimately produces an abundance of high quality mitochondria, leading to reduced mitophagy and a higher mitochondrial content. This is accompanied by the presence of an enhanced protein quality control system that consists of the protein import machinery as well chaperones and proteases termed the UPR^mt. The UPR^mt monitors intra-organelle proteostasis, and strives to maintain a mito-nuclear balance between nuclear- and mtDNA-derived gene products via retrograde signaling from the organelle to the nucleus. In addition, antioxidant capacity is improved, affording greater protection against oxidative stress. In contrast, chronic disuse conditions produce similar signaling but result in decrements in mitochondrial quality and content. Thus, the interactive cross-talk of the regulatory networks that control organelle turnover during wide variations in muscle use and disuse remain incompletely understood, despite our improving knowledge of the traditional regulators of organelle content and function. This brief review acknowledges existing regulatory networks and summarizes recent discoveries of novel biological pathways involved in determining organelle biogenesis, dynamics, mitophagy, protein quality control and antioxidant capacity, identifying ample protein targets for therapeutic intervention that determine muscle and mitochondrial health.

Estimating the cost of informal caregiving for elderly patients with cancer

PURPOSE

As the United States population ages, the increasing prevalence of cancer is likely to result in higher direct medical and nonmedical costs. Although estimates of the associated direct medical costs exist, very little information is available regarding the prevalence, time, and cost associated with informal caregiving for elderly cancer patients.

MATERIALS AND METHODS

To estimate these costs, we used data from the first wave (1993) of the Asset and Health Dynamics (AHEAD) Study, a nationally representative longitudinal survey of people aged 70 or older. Using a multivariable, two-part regression model to control for differences in health and functional status, social support, and sociodemographics, we estimated the probability of receiving informal care, the average weekly number of caregiving hours, and the average annual caregiving cost per case (assuming an average hourly wage of $8.17) for subjects who reported no history of cancer (NC), having a diagnosis of cancer but not receiving treatment for their cancer in the last year (CNT), and having a diagnosis of cancer and receiving treatment in the last year (CT).

RESULTS

Of the 7,443 subjects surveyed, 6,422 (86%) reported NC, 718 (10%) reported CNT, and 303 (4%) reported CT. Whereas the adjusted probability of informal caregiving for those respondents reporting NC and CNT was 26%, it was 34% for those reporting CT (P <.05). Those subjects reporting CT received an average of 10.0 hours of informal caregiving per week, as compared with 6.9 and 6.8 hours for those who reported NC and CNT, respectively (P <.05). Accordingly, cancer treatment was associated with an incremental increase of 3.1 hours per week, which translates into an additional average yearly cost of $1,200 per patient and just over $1 billion nationally.

CONCLUSION

Informal caregiving costs are substantial and should be considered when estimating the cost of cancer treatment in the elderly.

Cost of outpatient blood transfusion in cancer patients

PURPOSE

To determine the cost of outpatient RBC transfusion from the provider's perspective at a major urban, academic cancer center.

PATIENTS AND METHODS

We retrospectively studied 517 cancer patients with hematologic or solid tumors who received blood during fiscal year 1995 to 1996. A process-flow diagram was developed, and cost and utilization data for 12 months were collected and analyzed. A structured interview process was used to identify all direct and indirect costs from within the inpatient unit, blood bank, and outpatient clinic. Average costs were computed for the entire sample and for specific subgroups.

RESULTS

In 1998 dollars, the average cost per RBC unit was $469 for adults and $568 for pediatric cancer patients. Adults and children generally received two and one RBC units per transfusion, respectively. Therefore, the average cost of a two-unit transfusion was $938 for adults. Patients with hematologic tumors required more RBC units (7.1 RBC units per year) at a higher average cost ($512 per RBC unit) than patients with solid tumors (4.7 RBC units per year, $474 per RBC unit). Further variations across tumor types were observed. Overhead, direct material, and direct labor represented 46%, 19%, and 35% of total costs respectively.

CONCLUSION

The cost of outpatient RBC transfusions in cancer patients is higher than previously reported, in part because overhead costs and fixed costs might have been underestimated in previous studies. Furthermore, age, tumor type, and geographic variations in the cost of fixed assets and labor have a substantial impact on the cost of blood. The results indicate that the cost-effectiveness of alternatives to transfusions in the management of cancer patients may have been underestimated in the existing literature.

Pharmacoeconomics and health policy. Current applications and prospects for the future

The use of pharmacoeconomic tools has grown dramatically in the past decade as provision of healthcare throughout the industrialised world has required increased cost consciousness. However, pharmacoeconomic analysis has not yet been fully exploited as a conceptual underpinning for public or private health policy decisions. Pharmacoeconomics is likely to become an increasingly important basis for health policy decisions as a number of significant dynamics evolve in the marketplace, including: (i) consumers acting on their growing access to information and becoming more actively involved in treatment decisions; (ii) payers, providers and patients deepening their interaction and overcoming their traditional (narrow) focus on either costs or benefits alone; and (iii) manufacturers being challenged by other healthcare constituencies as sponsors of cost-based outcomes studies.

Cost effectiveness, quality-adjusted life-years and supportive care. Recombinant human erythropoietin as a treatment of cancer-associated anaemia

OBJECTIVE

To measure the cost effectiveness of a supportive care intervention when the no-treatment option is unrealistic in an analysis of recombinant human erythropoietin (epoetin) treatment for anaemic patients with cancer undergoing chemotherapy. Further, to assess whether quality-adjusted life-years (QALYs) can provide the basis for an appropriate measure of the value of supportive care interventions.

DESIGN

A modelling study drawing cost and effectiveness assumptions from a literature review and from 3 US clinical trials involving more than 4500 patients with cancer who were treated with chemotherapy, radiotherapy, epoetin and blood transfusions as needed under standard care for patients with cancer.

MAIN OUTCOME MEASURES AND RESULTS

When compared with transfusions, epoetin is cost effective under varying assumptions, whether effectiveness is measured by haemoglobin level or quality of life. Specifically, under a base-case scenario, the effectiveness resulting from $US1 spent on standard care can be achieved with only $US0.81 of epoetin care. Due in part to the health-state dependence of the significance patients attach to incremental changes in their responses on the linear analogue scale, cost per QALY results are ambiguous in this supportive care context.

CONCLUSIONS

Under a broad range of plausible assumptions, epoetin can be used cost effectively in the treatment of anaemic patients with cancer. Further, QALYs have limited applicability here because, as a short term supportive treatment, epoetin enhances the quality but not the length of life. Future research would benefit from the establishment of consistent values for quality-of-life changes across patients and health status, and the extension of the QALY framework to supportive care.

Single dose oral fluconazole vs intravaginal terconazole in treatment of Candida vaginitis. Comparison and pilot study

Candida vaginitis develops in approximately one-fourth of women in their childbearing years. Conventional management consists of antifungal creams or tablets/suppositories administered intravaginally. Many patients have stated preferences for oral therapy. A randomized, double-blind placebo trial compared the efficacy of a single oral 200 mg dose of fluconazole with the application of terconazole 80 mg vaginal suppository daily for 3 days. Twenty-two patients (fluconazole = 12, terconazole = 10) were evaluated during a four-month period and favorable clinical responses were observed at both early and late evaluations. Mycologic cure was attained by 75% of the fluconazole group and 50% of the terconazole group at the early evaluation. At the late evaluation, mycologic cure was 75% and 100% respectively. The mean time to onset of symptom relief was 2.4 (1.7) days for the fluconazole group and 1.8 (1.8) days for the terconazole group. The mean time to complete relief of symptoms was 6.08 (2.84) and 6.6 (2.95) days respectively. A statistically significant difference did not exist for any of these measures. Seventy-three percent of the patients preferred oral therapy.