Search

Purpose: Syndactyly surgical release is one of the most common congenital hand surgeries performed by pediatric hand surgeons. The purpose of our study was to evaluate the complications associated with syndactyly release and determine factors that correlate with higher complication rates within the 2-year postoperative period., Methods: A retrospective chart review was completed for patients who underwent syndactyly release at a single pediatric center between 2005 and 2018. Patients were included if they had a diagnosis of syndactyly and underwent surgical release, and excluded for a diagnosis of cleft hand, incomplete surgical documentation, surgery performed at an outside institution, or follow-up care that did not extend beyond the first postoperative visit. Complications were classified using the Clavien-Dindo (CD) system., Results: Fifty-nine patients met the inclusion criteria, which included 143 webs released in 85 surgeries. A total of 27 complications occurred for the 85 surgeries performed. The severity of complications was CD grade I or II in 23% of surgeries, most commonly unplanned cast changes, and CD grade III in 8% of surgeries. No CD grade IV or V complications occurred. The CD grade III complications included 6 reoperations. The complication rate was higher when performing >1 syndactyly release per surgery. It also was higher for patients undergoing >1 surgical event. Rates of complication per surgery were similar between patients with multiple surgeries compared with those with a single surgery. Concomitant diagnoses and complexity of syndactyly was not associated with a higher complication rate., Conclusions: Syndactyly release was associated with a complication rate of 31% per surgical event with 44% of these complications related to unplanned cast changes and 8% of complications that required admission or reoperation. Risk factors for complications following syndactyly release include >1web operated on per surgery and undergoing >1 surgical event., Type of Study/level of Evidence: Prognosis IV., (Copyright © 2024 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

Purpose: Many patients with amyloidosis undergo carpal tunnel release (CTR) before amyloidosis diagnosis and before developing cardiac or other serious disease manifestations. The purposes of this study were to examine if our patient population had a similar prevalence of positive amyloidosis diagnoses to that in prior studies and to describe the results of implementing a screening program for amyloidosis., Methods: We retrospectively reviewed the biopsy results and subsequent interventions for all patients who underwent screening tenosynovial biopsy during CTR from March 2020 through December 2021. Amyloid screening was offered to patients who met the criteria for increased risk of disease using an appropriateness screening algorithm., Results: Seventy-five (48%) of 156 patients who underwent CTR met the eligibility criteria for amyloidosis testing. Of the 62 patients who agreed to undergo tenosynovial biopsy, 14 had amyloid-positive biopsy specimens (10 men and 4 women). All patients with positive tenosynovial biopsies had bilateral carpal tunnel syndrome and wild-type transthyretin amyloid subtype. One patient was diagnosed and started treatment for otherwise asymptomatic cardiac amyloidosis., Conclusions: The incidence of amyloid-positive tenosynovial biopsy results from CTR was 22.5% in patients using the criteria from an appropriateness screening algorithm, which was higher than previously reported. Implementation of a screening program for patients undergoing CTR requires a multidisciplinary approach and may result in early diagnosis and lifesaving interventions for patients with amyloidosis., Type of Study/level of Evidence: Differential diagnosis/symptom prevalence study, II., (Copyright © 2024 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

Introduction: The Orthopaedic Trauma Association (OTA) has maintained an accreditation process of orthopaedic trauma fellowships with various requirements including an annually reviewed list of qualifying trauma cases in the form of American Medical Association Current Procedural Terminology (CPT) codes. The correlation between these established and monitored CPTs and the actual practices of orthopaedic trauma surgeons has not been studied., Methods: American Board of Orthopaedic Surgery part II case logs (trauma subspecialty) (2012 to 2018) were compared with OTA fellowship case logs (2015 to 2019). Case logs from 447 surgeons and 166 trauma fellowship programs were compared. Four CPT code categories were defined: complex trauma (OTA required CPT codes, excluding Accreditation Council for Graduate Medical Education [ACGME] orthopaedic residency requirements), general trauma (ACGME residency required trauma codes), general orthopaedics (nontrauma ACGME residency requirements), and others (codes not included in residency or trauma fellowship requirements)., Results: OTA fellows performed a higher median percentage of complex trauma compared with American Board of Orthopaedic Surgery candidates (34% vs. 21%, P < 0.001): Both cohorts performed a similar percentage of general trauma (23%). OTA fellows performed more general orthopaedics (40% vs. 1%, P < 0.001). Several OTA required codes were performed infrequently (0 to 3 during board collection) by most surgeons, and several procedures are being performed that are not included in current CPT code requirements., Discussion: Early-career traumatologists are performing orthopaedic trauma procedures they were trained on during residency and fellowship, with varying complexity. Trauma fellows perform a higher percentage of complex trauma compared with early-career trauma surgeons. Continued surveillance is necessary such that educational improvements can be made to maximize the quality of trauma fellowship education., Level of Evidence: Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence., (Copyright © 2023 by the American Academy of Orthopaedic Surgeons.)

Purpose: The purpose of this study is to evaluate and summarize the current literature on outcomes of arthroscopic-assisted tibial plateau fixation (AATPF) when applied for only lateral tibial plateau fractures., Methods: A comprehensive search of nine databases was conducted: ClinicalTrials.gov, Cochrane Library via Wiley, Embase and MEDLINE via Ovid, Global Index Medicus, PubMed, Scopus, SPORTDiscus via EBSCO, and Web of Science Core Collection. The study was performed in concordance with PRISMA guidelines. Studies eligible for inclusions included Schatzker I-III lateral tibial plateau fractures with a minimum of 6-month follow-up. Data extraction was performed by two authors independently using a predesigned form., Results: A total of 17 studies, 7 prospective and 10 retrospective, including 565 patients (age 15-82 years old) treated with AATPF were included in this review with follow-up ranging from 6 to 138 months. All 10 studies that used categorical functional outcomes demonstrated excellent/very good or good outcomes in > 90% of patients. When compared to patients managed with the traditional open reduction internal fixation (ORIF), patients treated with AATPF had statistically significantly better range of motion mean difference [5.21° (95% CI - 2.50 to 12.92, p < 0.0001)], lower blood loss [66.19 mL (95% confidence interval (CI) 32.54-99.84 mL, p < 0.0001)], shorter hospital stay [- 1.41 days (95% CI - 3.39 to 0.58 days, p < 0.0001)], better Hospital Special Surgery score [11.31 (95% CI 6.49-16.12, p < 0.0001)], and higher Rasmussen radiographic score [1.26 (95% CI - 0.72 to 3.23, p < 0.0001)]., Conclusion: AATPF is a promising treatment of lateral tibial plateau fractures with some advantages over the traditional ORIF., Level of Evidence: Therapeutic Level III., (© 2022. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Purpose: Treatment for tibial plateau fractures continues to evolve but maintains primary objectives of anatomic reduction of the joint line and a rapid recovery course. Arthroscopic-assisted percutaneous fixation (AAPF) has been introduced as an alternative to traditional open reduction internal fixation (ORIF). The purpose of the study is to compare clinical and radiographic outcomes in patients with low-energy Schatzker type I-III tibial plateau fractures treated with AAPF versus ORIF., Methods: A retrospective chart review was performed at a level 1 trauma centre to compare outcomes of 120 patients (57 AAPF, 63 ORIF) with low-energy lateral Schatzker type I-III tibial plateau fractures who underwent tibial plateau fixation between 2009 and 2018. Demographic information, injury characteristics, and surgical treatment were recorded. The main outcome measurements included reduction step-off, joint space narrowing, time to weight bearing, and implant removal., Results: There was no difference in age, gender distribution, BMI, ASA, Schatzker classification distribution, initial displacement, blood loss, and reduction step-off between the two groups (p > 0.05). Shorter tourniquet time (74.1 ± 21.7 vs 100.0 ± 21.0 min; p < 0.001), shorter time to full weight bearing (47.8 ± 15.2 vs. 69.1 ± 17.2 days; p < 0.001), and lower rate of joint space narrowing (3.5% vs. 28.6% with more than 1 mm, p < 0.001) were associated with the AAPF cohort, with no difference in pain, knee range of motion, or implant removal rate between the two cohorts., Conclusion: AAPF may be a viable alternative to ORIF for the management of low-energy tibial plateau fractures with outcomes not inferior compared to the traditional ORIF method., (© 2023. The Author(s) under exclusive licence to SICOT aisbl.)

Purpose: Respiratory complications are common following neuromuscular scoliosis (NMS) spinal fusion. Concern exists regarding the safety to perform complicated procedures in winter months when viral respiratory illness is common. The purpose of this study was to compare perioperative outcomes in children with NMS undergoing spinal fusion during peak (November-March) or non-peak (April-October) viral season., Methods: The Health Care and Utilization Project (HCUP) Kids' inpatient database (KID) from 2006 to 2012 was reviewed. Children 20 years or younger who underwent spinal fusion for NMS were included. Patients were grouped by date of surgery during peak or non-peak viral season. Continuous variables were compared using t tests and categorical variables were compared using the Rao-Scott Chi-square test. Weighted logistic regression models were performed., Results: This study identified 5082 records, including 1711 and 3371 patients who had surgery in peak and non-peak viral seasons, respectively. Patients who had spinal fusion during peak viral season were less likely to experience respiratory failure (p = 0.0008) and did not demonstrate an increased incidence of aspiration pneumonia (p = 0.26), respiratory complication (p = 0.43), or mortality (p = 0.68). Respiratory failure was associated with younger age (p = 0.0031), the presence of a tracheostomy (p < 0.0001), and the number of chronic conditions (p < 0.0001). Higher number of chronic medical conditions (mean of 5.0) was associated with an increased risk of in-hospital mortality (p < 0.0001), aspiration pneumonia (p = 0.0009), and respiratory failure (p < 0.0001)., Conclusion: Spinal fusion for NMS during peak viral season has a lower risk of respiratory failure without an increase in mortality or other complications compared to during non-peak viral season., (© 2022. The Author(s), under exclusive licence to Scoliosis Research Society.)

Park-Harris lines are radiographically apparent linear opacities that occur in a metaphyseal bone in proximity to a physis. Lines correspond to a temporary interruption of the normally ossifying physis with a sclerotic line corresponding to transversely oriented trabeculae. They were first appreciated in the long bones of diabetic children and have since been described in various metabolic, endocrinologic, infectious, neoplastic, and posttraumatic conditions as well as in response to systemic medications. Park-Harris lines are clinically useful in demarcating notable events in whole-body or individual bone development, in tracking longitudinal growth, or in assessing physeal arrest and responses to its treatment. There remains controversy about whether these lines are pathologic or a component of physiologic development and whether they constitute true "growth arrest" or rather "growth recovery." In this review, the history, pathophysiology, imaging, and clinical use of Park-Harris lines as well as an anthropological perspective on their utility for studying illness, nutrition, and historical living conditions over time are discussed., (Copyright © 2022 by the American Academy of Orthopaedic Surgeons.)

Background: Limb lengthening by distraction osteogenesis can be performed with motorized internal devices, but intramedullary implants risk avascular necrosis of the femoral head in young children. A method of internal limb lengthening using a motorized expandable plate has been developed and preliminary results are presented., Methods: Seven skeletally immature patients (ages 2.7 to 9.7 y) with congenital femoral deficiencies underwent femoral lengthening with the use of a magnetic expandable plate. Surgical details, lengthening parameters, Limb Lengthening and Reconstruction Society-Angular deformity, Infection, Motion index, and complications were reviewed and classified according to the modified Clavien-Dindo system., Results: An average lengthening was 4.1 cm (range, 3.3 to 4.4 cm) comprising 18% of initial femoral segment length (range, 14% to 21%). The average lengthening phase was 50.2 days (range, 40 to 57 d) and weight-bearing was initiated at an average of 13 weeks from surgery (range, 8 to 18 wk). Limb deformities and length discrepancies were of moderate complexity, with an Limb Lengthening and Reconstruction Society-Angular deformity, Infection, Motion score of 6.57 (range, 6 to 7). Complication rates were comparable to previously reported methods of femoral lengthening. One patient underwent reoperation for patellar instability and 1 patient experienced radiographic hip subluxation which was observed. Small magnitude varus was observed in regenerate in 3 of 7 cases, none requiring treatment. Preoperative planning consisted of careful localization of the corticotomy site, acute deformity correction at the lengthening site in 3 cases, and implant orientation., Conclusions: Limb lengthening with motorized internal plates is feasible for young children with congenital femoral deficiency for whom intramedullary lengthening is unsafe or if external fixation is to be avoided. However, the fundamental principles of distraction osteogenesis and risks of lengthening for congenital discrepancies remain unchanged. Specific considerations herein include: careful planning of implant length and positioning, adjacent joint protection with adjunctive means, and mitigating deformity of the regenerate during distraction., Level of Evidence: Level IV, retrospective case series., Competing Interests: M.T.D. is a paid consultant for NuVasive and a consultant for Stryker Trauma. The remaining authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Glucocorticoids (GCs) are among the most widely prescribed medications in dermatologic practice. Although considered generally safe and efficacious, prolonged use and high dosing regimens may precipitate GC-induced osteoporosis, which contributes to an increased risk for fragility fractures. Dermatologists using and prescribing GCs must be aware of the risk for GC-induced osteoporosis. This review details the risks for osteoporosis and osteoporotic (OP) fractures in the setting of topical, intralesional, intramuscular, and systemic GC treatment, as well as nutritional supplementation recommendations that may reduce the risk of these adverse effects.

Objective: To determine whether inpatient mobilization (defined as ambulation before hospital discharge) is associated with 1-year mortality and 90-day hospital readmission in patients treated with a hip hemiarthroplasty for a femoral neck fracture., Design: Retrospective case-control., Setting: Academic Level 1 trauma center., Patients/participants: Two hundred twelve consecutive femoral neck fractures were treated with hip hemiarthroplasties with a minimum of 1 year of follow-up., Intervention: All study patients were treated with a hip hemiarthroplasty and weight-bearing as tolerated postoperative day 1. Patients were prescribed daily physical therapy with the goal of mobilization before discharge from hospital., Main Outcome Measures: Mortality at 1 year; hospital readmission within 90 days., Results: Two hundred twelve patients were included in the study. One-year mortality was 29%. One hundred thirty-two (62%) patients were able to ambulate before hospital discharge. Ambulation with physical therapy before discharge from hospital was a significant predictor of 1-year mortality when compared with patients who were unable to ambulate (hazard ratio 0.57; 95% confidence interval, 0.34-0.94; P = 0.03), which equates to 43% reduction in risk of mortality. There was no difference in the 90-day readmission rates for ambulatory versus nonambulatory patients., Conclusions: Ambulation with physical therapy before discharge reduced the risk of 1-year mortality by 43%, without an effect on 90-day readmission. Sixty-two percentage of our cohort was able to ambulate before discharge. Future investigations are warranted to further identify those patients at heightened risk of mortality and readmission and the role of early rehabilitation in recovery., Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: The authors report no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Meniscal root tears are soft-tissue and/or osseous injuries characterized by an avulsion of, or tear within 1 cm of, the native meniscal insertion 1 . These injuries account for 10% to 21% of all meniscal tears, affecting nearly 100,000 patients annually 2 . Medial meniscal posterior-root tears (MMPRTs) expose the tibiofemoral joint to supraphysiologic contact pressure, decreased contact area, and altered knee kinematics similar to a total meniscectomy 3 . This injury predisposes the patient to exceedingly high rates of osteoarthritis and total knee arthroplasty secondary to an inability to resist hoop stress 4 . The arthroscopic transosseous repair of an MMPRT is described in the present article., Description: (1) Preoperative evaluation, including patient history, examination, and imaging (i.e., radiographs and magnetic resonance imaging). (2) Preparation and positioning. The patient is placed in the supine position, and anteromedial and anterolateral portals are created. (3) Placement of sutures. Two simple cinch sutures are placed into the posterior horn, within approximately 5 mm of each other. (4) Footprint decortication. Remove articular cartilage from the native root insertion site. (5) Drilling of the transosseous tibial tunnel. Introduce a tibial tunnel guide over the decorticated base, set guide to 45° to 50°, place a 2-cm vertical incision over an anteromedial tibial guide footprint, advance a 2.4-mm guide pin through the guide, and overream to 5 mm. (6) Passing of the sutures with use of a looped suture passer introduced retrograde through the tibial tunnel to retrieve sutures. (7) Anchor placement and fixation. Apply maximum suture traction, drill a second aperture 0.5 to 1.0 cm distal to the original aperture on the anteromedial aspect of the tibia, pass the suture ends through the anchor, and fix the anchor into the aperture. (8) Repair evaluation and closure. Note the position and stability of the meniscal root relative to the native footprint. Standard closure in layers is performed., Alternatives: If the patient experiences no relief from nonoperative treatment, an MMPRT can be treated operatively via partial meniscectomy or repaired via direct suture-anchor repair or indirect transosseous (transtibial) repair. Direct repair utilizes a suture anchor inserted at the root site 5 . Variations of the present technique include different suture configurations or numbers of tunnels. Although several suture configurations have been described, the simple cinch stitch (utilized in the present procedure) has been shown to be better at resisting displacement than the locking loop stitch 6 . Moreover, it has been suggested that simple stitches are less technically difficult and more able to resist displacement because they require less tissue penetration than other stitches 7 . Lastly, procedures that utilize a single versus a second transtibial tunnel have been shown to be equivalent in cadaveric studies 8 ., Rationale: The desired results of MMPRT repair include anatomic reduction, preservation of meniscal tissue and knee biomechanics, and preservation of hoop stress, which improve activity, function, and symptoms and mitigate degenerative changes and the risk of progression to total knee arthroplasty., Expected Outcomes: At a minimum of 2 years after transosseous repair, the Lysholm, Western Ontario and McMaster Universities Osteoarthritis Index, 12-Item Short Form, and Tegner activity scale were significantly improved 8,9 . Previous studies have shown significant improvement in the Hospital for Special Surgery and Lysholm scores without radiographic osteoarthritis progression at the same minimum follow-up 10 . Lastly, in the longest-term follow-up study to date, transosseous repair survivorship was reported to be 99% at 5 years and 92% at 8 years, with failure defined as conversion to total knee arthroplasty 11 ., Important Tips: Pearls○ Decorticate the native meniscal root down to bleeding bone.○ Consider fenestration or percutaneous release of the medial collateral ligament in order to further open a tight medial compartment.○ A self-retrieving suture passer allows the use of standard arthroscopy portals.○ A multiuse variable-angle tibial tunnel drill guide allows point-to-point placement over the native meniscal root insertion.○ A guide with a tip may be easier and more accurate to control.○ Consider different guides when drilling the tibial tunnel, according to the anatomy of the patient.○ A low-profile guide may provide better clearance along the condyles.○ Utilize a cannula when shuttling sutures through the tibial tunnel in order to prevent a soft-tissue bridge.○ With anchor fixation, consider drilling over a guide pin and tapping when the bone is hard.○ Study preoperative imaging to evaluate the amount of arthritis present. Evaluate all compartments on magnetic resonance imaging for additional pathology.Pitfalls○ Obliquity of the tibial tunnel can cause the guide pin and reamer to enter too anteriorly.○ Patient failure to adhere to postoperative rehabilitation and restrictions can lead to unfavorable outcomes.○ The use of lower-strength sutures may increase the risk of fixation failure., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

Summary: Falls are the leading cause of injuries for geriatric patients, causing significant morbidity and mortality. Orthopaedic surgeons should take an active role in decreasing patient falls, improving patient bone health, and initiate care to prevent subsequent fracture. In this manuscript, we outline 5 areas for orthopaedic surgeons to intervene and prevent the next fall: (1) patient education; (2) modifying environment/home safety measures; (3) medical fall risk assessment; (4) bone health evaluation and optimization; and (5) physical/occupational therapy., Competing Interests: The authors report no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

➤: Despite an increasing rate of civilian low-velocity gunshot injuries, there remains a lack of evidence-based treatment standards., ➤: Most low-velocity gunshot-induced fractures of the extremity can be managed similarly to non-gunshot-induced fractures, with the goals of restoring function and minimizing complications., ➤: There are a limited number of high-quality studies to support the use of prophylactic antibiotics for nonoperatively treated gunshot wounds., ➤: Intra-articular retained bullets should be removed, while prophylactic irrigation and debridement for a transarticular bullet is not routinely warranted for infection prevention., ➤: Much of the literature on low-velocity gunshot wounds is Level-III or IV evidence, warranting the need for higher-powered, randomized, prospective investigations., Competing Interests: Disclosure: The authors indicated that no external funding was received for any aspect of this work. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work and “yes” to indicate that the author had other relationships or activities that could be perceived to influence, or have the potential to influence, what was written in this work (http://links.lww.com/JBJS/G419)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

Case: An 8-year-old girl was diagnosed with osteosarcoma of the distal femur. She underwent chemotherapy and wide resection with implantation of a noninvasive electromagnetic expandable distal femur prosthesis. Ninety-three days after chemotherapy, she developed anthracycline-induced cardiomyopathy with heart failure for which a ventricular assist device was placed. Device compatibility was tested, and she was successfully lengthened., Conclusion: Expandable prostheses allow limb length maintenance in skeletally immature patients who undergo limb salvage. Chemotherapy for osteosarcoma involves anthracyclines with a dose-dependent side effect of cardiotoxicity. Patients can be successfully and safely lengthened with expandable electromagnetic prostheses with in situ ventricular assist devices., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/B458)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

»: Longitudinal clinical and radiographic success of total shoulder arthroplasty (TSA) is critically dependent on optimal glenoid component position., »: Historically, preoperative templating utilized radiographs with commercially produced overlay implant templates and a basic understanding of glenoid morphology., »: The advent of 3-dimensional imaging and templating has achieved more accurate and precise pathologic glenoid interrogation and glenoid implant positioning than historical 2-dimensional imaging., »: Advanced templating allows for the understanding of unique patient morphology, the recognition and anticipation of potential operative challenges, and the prediction of implant limitations, and it provides a method for preoperatively addressing abnormal glenoid morphology., »: Synergistic software, implants, and instrumentation have emerged with the aim of improving the accuracy of glenoid component implantation. Additional studies are warranted to determine the ultimate efficacy and cost-effectiveness of these technologies, as well as the potential for improvements in TSA outcomes., Competing Interests: Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/A671)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

Background and Objectives: Soft-tissue sarcomas (STSs) are often treated with resection and radiation (RT)±chemotherapy. The role of RT in decreasing resection width to achieve local control is unclear. We evaluated RT on margin width to achieve local control and local recurrence (LR)., Methods: From 2000 to 2016, 514 patients with localized STS were identified from the US Sarcoma Collaborative database. Patients were stratified by a margin and local control was compared amongst treatment groups., Results: LR was 9% with positive, 4.2% with ≤1 mm, and 9.3% with >1 mm margins (P = .315). In the ≤1 mm group, LR was 5.7% without RT, 0% with preoperative RT, and 0% with postoperative RT (P < .0001). In the >1 mm group, LR was 10.2%, 0%, and 3.7% in the no preoperative and postoperative RT groups, respectively (P = .005). RT did not influence LR in patients with positive margins. In stage I-III and II-III patients, local recurrence-free survival was higher following RT (P = .008 and P = .05, respectively)., Conclusions: RT may play a larger role in minimizing LR than margin status. In patients with positive margins, RT may decrease LR to similar rates as a negative margin without RT and may be considered to decrease the risk of LR with anticipated close/positive margins., (© 2019 Wiley Periodicals, Inc.)

Purpose: Neoadjuvant radiotherapy ± chemotherapy and wide local excision is an accepted management of localized soft tissue sarcomas (STS). Necrosis is prognostic for survival in osteosarcomas, but the significance for STS is undetermined. This study aimed to determine if percent true necrosis, opposed to a combination of necrosis and fibrosis, leads to improved survival in extremity and trunk STS., Methods: From 2000 to 2015, 162 patients with STS were treated with neoadjuvant therapy and resection. Patient and tumor variables were reviewed, and resected specimens underwent pathological assessment. Necrosis was ratiometrically determined. Overall (OS), distant metastasis-free (DMFS), and progression-free survival (PFS) were calculated using Kaplan-Meier estimator. Survival was determined using the Fisher's exact test for univariate analysis (UVA) and logistic regression for multivariate analysis (MVA)., Results: Median follow-up was 4.5 years and median necrosis was 24.97%. Necrosis predicted worse OS, DMFS, and PFS on UVA, and DMFS and PFS on MVA. Necrosis was positively correlated with size and grade. To mitigate the role of size, a sub-analysis of ≥ 10 cm tumors was performed revealing necrosis predicted decreased DMFS and PFS on UVA and MVA. In high-grade tumors, necrosis correlated with decreased DMFS and PFS on UVA. Necrosis did not predict OS in ≥ 10 cm or high-grade tumors., Conclusions: Our data suggests necrosis may be an additional independent, prognostic variable with increased necrosis predicting a worse prognosis. Necrosis may not be a measure of treatment response and instead suggests more aggressive tumor biology as high-grade, large STS were associated with increased necrosis.

Branched-chain amino acids (BCAA) such as leucine stimulate favorable metabolic processes involved in lean tissue preservation and skeletal muscle metabolism. However, higher levels of circulating BCAA correlate with severity of metabolic disease (including diabetes/insulin resistance), and may result from dysregulated BCAA catabolism. Past observations have demonstrated potential interaction between BCAA and dietary fat; however, much of this relationship remains underexplored. This study investigated the effect of leucine both with and without palmitate on oxidative and glycolytic metabolism, as well as indicators of BCAA catabolism using cultured skeletal muscle cells. Specifically, C2C12 myotubes were treated with or without varying concentrations of leucine both with and without palmitate for 24 h. Leucine treatment significantly elevated mRNA expression of metabolic regulators including peroxisome proliferator-activated receptor-gamma coactivator 1-alpha versus leucine with concurrent palmitate treatment. Interestingly, leucine-only, palmitate-only, and leucine with palmitate all significantly increased cellular lipid content, which translated into significantly increased oxidative capacity under substrate-limited conditions. However, upon the addition of excess substrate and carnitine, discrepancies in peak metabolic capacities between various treatments were no longer observed, suggesting leucine, palmitate, or the combination thereof causes a shift in metabolic preference from glycolytic to oxidative. These data also suggest leucine's effect on mitochondrial metabolism may result in part from increased lipid stores in addition to other previously documented pathways., (© 2019 AOCS.)

Background: Soft tissue sarcomas (STS) are often treated with pre-operative radiation (RT), with or without chemotherapy, followed by wide local excision. Prognosis for these patients involves an interplay of tumor and patient characteristics. Known prognostic determinants include tumor size, grade, response to therapy, and patient characteristics such as age. While smoking is negatively correlated with outcomes in various malignancies, the impact on STS is unknown. We aimed to assess if smoking impacts overall (OS), distant metastasis-free (DMFS), and progression-free (PFS) survival in patients with STS treated with pre-operative RT., Methods: Between 2000 and 2015, 166 patients with STS were identified from our prospective database. Patient variables were retrospectively reviewed. Smoking was defined as a ≥ 10 pack year history of current and former smokers. Survival was evaluated using the fisher exact test for univariate (UVA) and logistic regression for multivariate (MVA) analysis., Results: Fifty-seven (34.3%) patients had smoking histories of ≥ 10 pack years. On UVA, smoking was associated with decreased DMFS (p = 0.0009) and PFS (p = 0.0036), but not OS (p = 0.05). Smoking held significance on MVA for both DMFS and PFS. Current smokers and patients with ≥ 24-month follow-up demonstrated decreased DMFS and PFS on UVA and MVA., Conclusions: Current smokers and patients with a significant smoking history demonstrated decreased DMFS and PFS in STS patients treated with pre-operative RT. Smoking may cause immunologic compromise and therefore lead to higher rates of progression and distant metastasis.

Branched-chain amino acids (BCAAs) appear to influence several synthetic and catabolic cellular signaling cascades leading to altered phenotypes in mammals. BCAAs are most notably known to increase protein synthesis through modulating protein translation, explaining their appeal to resistance and endurance athletes for muscle hypertrophy, expedited recovery, and preservation of lean body mass. In addition to anabolic effects, BCAAs may increase mitochondrial content in skeletal muscle and adipocytes, possibly enhancing oxidative capacity. However, elevated circulating BCAA levels have been correlated with severity of insulin resistance. It is hypothesized that elevated circulating BCAAs observed in insulin resistance may result from dysregulated BCAA degradation. This review summarizes original reports that investigated the ability of BCAAs to alter glucose uptake in consequential cell types and experimental models. The review also discusses the interplay of BCAAs with other metabolic factors, and the role of excess lipid (and possibly energy excess) in the dysregulation of BCAA catabolism. Lastly, this article provides a working hypothesis of the mechanism(s) by which lipids may contribute to altered BCAA catabolism, which often accompanies metabolic disease., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Caffeine has been shown to stimulate multiple major regulators of cell energetics including AMP-activated protein kinase (AMPK) and Ca 2+ /calmodulin-dependent protein kinase II (CaMKII). Additionally, caffeine induces peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and mitochondrial biogenesis. While caffeine enhances oxidative metabolism, experimental concentrations often exceed physiologically attainable concentrations through diet. This work measured the effects of low-level caffeine on cellular metabolism and gene expression in myotubes, as well as the dependence of caffeine's effects on the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPARβ/δ). C2C12 myotubes were treated with various doses of caffeine for up to 24 h. Gene and protein expression were measured via qRT-PCR and Western blot, respectively. Cellular metabolism was determined via oxygen consumption and extracellular acidification rate. Caffeine significantly induced regulators of mitochondrial biogenesis and oxidative metabolism. Mitochondrial staining was suppressed in PPARβ/δ-inhibited cells which was rescued by concurrent caffeine treatment. Caffeine-treated cells also displayed elevated peak oxidative metabolism which was partially abolished following PPARβ/δ inhibition. Similar to past observations, glucose uptake and GLUT4 content were elevated in caffeine-treated cells, however, glycolytic metabolism was unaltered following caffeine treatment. Physiological levels of caffeine appear to enhance cell metabolism through mechanisms partially dependent on PPARβ/δ.

A genome-wide association study (GWAS) reported that common variation in the human Niemann-Pick C1 gene ( NPC1 ) is associated with morbid adult obesity. This study was confirmed using our BALB/cJ Npc1 mouse model, whereby heterozygous mice ( Npc1 +/- ) with decreased gene dosage were susceptible to weight gain when fed a high-fat diet (HFD) compared with homozygous normal mice ( Npc1 +/+ ) fed the same diet. The objective for our current study was to validate this Npc1 gene-diet interaction using statistical modeling with fitted growth trajectories, conduct body weight analyses for different measures, and define the physiological basis responsible for weight gain. Metabolic phenotype analysis indicated no significant difference between Npc1 +/+ and Npc1 +/- mice fed a HFD for food and water intake, oxygen consumption, carbon dioxide production, locomotor activity, adaptive thermogenesis, and intestinal lipid absorption. However, the livers from Npc1 +/- mice had significantly increased amounts of mature sterol regulatory element-binding protein-1 (SREBP-1) and increased expression of SREBP-1 target genes that regulate glycolysis and lipogenesis with an accumulation of triacylglycerol and cholesterol. Moreover, white adipose tissue from Npc1 +/- mice had significantly decreased amounts of phosphorylated hormone-sensitive lipase with decreased triacylglycerol lipolysis. Consistent with these results, cellular energy metabolism studies indicated that Npc1 +/- fibroblasts had significantly increased glycolysis and lipogenesis, in addition to significantly decreased substrate (glucose and endogenous fatty acid) oxidative metabolism with an accumulation of triacylglycerol and cholesterol. In conclusion, these studies demonstrate that the Npc1 gene interacts with a HFD to promote weight gain through differential regulation of central energy metabolism pathways., (Copyright © 2017 the American Physiological Society.)

Heat stress has been reported to reduce uncoupling proteins (UCP) expression, which in turn should improve mitochondrial efficiency. Such an improvement in efficiency may translate to the systemic level as greater exercise economy. However, neither the heat-induced improvement in mitochondrial efficiency (due to decrease in UCP), nor its potential to improve economy has been studied. Determine: (i) if heat stress in vitro lowers UCP3 thereby improving mitochondrial efficiency in C2C12 myocytes; (ii) whether heat acclimation (HA) in vivo improves exercise economy in trained individuals; and (iii) the potential improved economy during exercise at altitude. In vitro, myocytes were heat stressed for 24 h (40°C), followed by measurements of UCP3, mitochondrial uncoupling, and efficiency. In vivo, eight trained males completed: (i) pre-HA testing; (ii) 10 days of HA (40°C, 20% RH); and (iii) post-HA testing. Pre- and posttesting consisted of maximal exercise test and submaximal exercise at two intensities to assess exercise economy at 1600 m (Albuquerque, NM) and 4350 m. Heat-stressed myocytes displayed significantly reduced UCP3 mRNA expression and, mitochondrial uncoupling (77.1 ± 1.2%, P < 0.0001) and improved mitochondrial efficiency (62.9 ± 4.1%, P < 0.0001) compared to control. In humans, at both 1600 m and 4350 m, following HA, submaximal exercise economy did not change at low and moderate exercise intensities. Our findings indicate that while heat-induced reduction in UCP3 improves mitochondrial efficiency in vitro, this is not translated to in vivo improvement of exercise economy at 1600 m or 4350 m., (© 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Leucine modulates synthetic and degradative pathways in muscle, possibly providing metabolic benefits for both athletes and diseased populations. Leucine has become popular among athletes for improving performance and body composition, however little is known about the metabolic effects of the commonly consumed leucine-derived metabolite β-hydroxy-β-methyl butyrate (HMB). Our work measured the effects of HMB on metabolic protein expression, mitochondrial content and metabolism, as well as lipid content in skeletal muscle cells. Specifically, cultured C2C12 myotubes were treated with either a control or HMB ranging from 6.25 to 25 μM for 24 h and mRNA and/or protein expression, oxygen consumption, glucose uptake, and lipid content were measured. Contrary to leucine's stimulatory effect on metabolism, HMB-treated cells exhibited significantly reduced regulators of lipid oxidation including peroxisome proliferator-activated receptor alpha (PPARα) and PPARβ/δ, as well as downstream target carnitine palmitoyl transferase, without alterations in glucose or palmitate oxidation. Furthermore, HMB significantly inhibited activation of the master regulator of energetics, AMP-activated protein kinase. As a result, HMB-treated cells also displayed reduced total mitochondrial content compared with true control or cells equivocally treated with leucine. Additionally, HMB treatment amplified markers of lipid biosynthesis (PPARγ and fatty acid synthase) as well as consistently promoted elevated total lipid content versus control cells. Collectively, our results demonstrate that HMB did not improve mitochondrial metabolism or content, and may promote elevated cellular lipid content possibly through heightened PPARγ expression. These observations suggest that HMB may be most beneficial for populations interested in stimulating anabolic cellular processes.

Leucine stimulates anabolic and catabolic processes in skeletal muscle, however little is known about the effects of leucine on peroxisome proliferator-activated receptor (PPAR) activity. This work characterized the effects of 24-h leucine treatment on metabolic parameters and protein expression in cultured myotubes. Leucine significantly increased PPARβ/δ expression as well as markers of mitochondrial biogenesis, leading to significantly increased mitochondrial content and oxidative metabolism in a PPARβ/δ-dependent manner. However, leucine-treated cells did not display significant alterations in uncoupling protein expression or oxygen consumed per relative mitochondrial content suggesting leucine-mediated increases in oxidative metabolism are a function of increased mitochondrial content and not altered mitochondrial efficiency. Leucine treatment also increased GLUT4 content and glucose uptake as well as PPARγ and FAS expression leading to increased total lipid content. Leucine appears to activate PPAR activity leading to increased mitochondrial biogenesis and elevated substrate oxidation, while simultaneously promoting substrate/lipid storage and protein synthesis., (Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

There is increasing interest in dietary chemicals that may provide benefits for pathologies such as diabetes and obesity. Capsaicinoids found in chili peppers and pepper extracts, are responsible for the "hot" or "spicy" sensation associated with these foods. Capsaicinoid consumption is also associated with enhanced metabolism, making them potentially therapeutic for metabolic disease by promoting weight loss. This review summarizes much of the current experimental evidence (ranging from basic to applied investigations) of the biochemical and molecular metabolic effects of capsaicinoids in metabolically significant cell types. Along with influencing metabolic rate, findings demonstrate capsaicinoids appear to alter molecular metabolic signaling, regulate hunger and satiety, blood metabolites, and catecholamine release. Notably, the majority of the experiments summarized herein utilized isolated supplemental or research grade capsaicinoids rather than natural food sources for experimental interventions. Additional work should be conducted using primary food sources of capsaicin to explore pharmacological, physiological, and metabolic benefits of both chronic and acute capsaicin consumption. © 2016 BioFactors, 42(3):229-246, 2016., (© 2016 International Union of Biochemistry and Molecular Biology.)

Leucine is an essential nutrient with potent abilities to stimulate both muscle protein synthesis as well as increased oxidative metabolism supported by mitochondrial biogenesis. Few studies have simultaneously investigated anabolic and catabolic responses following leucine treatment with the exception of master regulator of cellular energetics, AMPK. The unique ability of leucine to stimulate both favorable anabolic and catabolic processes in highly metabolically active tissues suggests leucine consumption/supplementation may provide benefits beyond hypertrophic gains. This review highlights original investigations reporting leucine’s ability to stimulate both anabolic and catabolic processes in muscle. Additionally, this report discusses potential explanations for the simultaneous activation of two seemingly opposing processes, as well as the interplay between them. The role of cellular energetics is of undeniable importance in sustaining increased protein synthesis following leucine administration; however, the dependence of leucine-induced mitochondrial biogenesis on heightened energy expenditure from elevated protein synthesis remains to be defined experimentally.

Type 2 diabetes is characterized by insulin resistance and chronic hyperglycemia, and is increasing in incidence and severity. This work explored the effects of trans-cinnamaldehyde (CA) on carbohydrate metabolism, mitochondrial content, and related metabolic gene and protein expression in cultured myotubes treated with various concentrations of CA for up to 24 h. CA treatment increased myotube myocyte enhancer factor 2 (MEF2) along with glucose transporter 4 (GLUT4) content. CA treatment also significantly increased expression of markers of improved oxidative metabolism including 5' adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α), cytochrome c (CytC), as well as peroxisome proliferator-activated receptor α (PPARα) and PPARβ/δ. Despite increased expression of proteins associated with improved oxidative metabolism and glucose uptake, CA-treated myotubes exhibited significantly reduced oxidative metabolism compared with controlled cells. Additionally, CA treatment increased markers of glucose-mediated lipid biosynthesis without elevated PPARγ and sterol receptor element binding protein 1c (SREBP-1c) expression. The ability of CA to stimulate mitochondrial biogenesis and GLUT4 expression suggests CA may offer possible benefits for metabolic disease. However, increases in markers of fatty acid synthesis with simultaneously reduced oxidative metabolism suggest CA may have counterproductive effects for metabolic disease, warranting a need for further investigation., (Copyright © 2015 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Exercise offers several benefits for health, including increased lean body mass and heightened energy expenditure, which may be partially attributable to secretory factors known as myokines. Irisin, a recently identified myokine, was shown to increase metabolic rate and mitochondrial content in both myocytes and adipocytes; however, the mechanism(s) of action still remain largely unexplained. This work investigated if irisin functions by acting as an inflammatory myokine leading to cellular stress and energy expenditure. C2C12 myotubes were treated with various concentrations of irisin, TNFα, or IL6 for various durations. Glycolytic and oxidative metabolism, as well as mitochondrial uncoupling, were quantified by measurement of acidification and oxygen consumption, respectively. Metabolic gene and protein expression were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and immunoblotting, respectively. Mitochondrial content was assessed by fluorescent imaging. NFκB activity was assessed using an NFκB GFP-linked reporter system. Consistent with previous findings, irisin significantly increased expression of several genes including peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) leading to increased mitochondrial content and oxygen consumption. Despite some similarities between TNFα and irisin treatment, irisin failed to activate the NFκB pathway like TNFα, suggesting that irisin may not act as an inflammatory signal. Irisin has several effects on myotube metabolism which appear to be dependent on substrate availability; however, the precise mechanism(s) by which irisin functions in skeletal muscle remain unclear. Our observations support the hypothesis that irisin does not function through inflammatory NFκB activation like other myokines (such as TNFα).

Obesity is an increasingly prevalent and preventable morbidity with multiple behavioral, surgical and pharmacological interventions currently available. Commercial dietary supplements are often advertised to stimulate metabolism and cause rapid weight and/or fat loss, although few well-controlled studies have demonstrated such effects. We describe a commercially available dietary supplement (purportedly containing caffeine, catechins, and other metabolic stimulators) on resting metabolic rate in humans, and on metabolism, mitochondrial content, and related gene expression in vitro . Human males ingested either a placebo or commercially available supplement (RF) in a randomized double-blind placebo-controlled cross-over fashion. Metabolic rate, respiratory exchange ratio, and blood pressure were measured hourly for 3 h post-ingestion. To investigate molecular effects, human rhabdomyosarcoma cells (RD) and mouse myocytes (C2C12) were treated with various doses of RF for various durations. RF enhanced energy expenditure and systolic blood pressure in human males without altering substrate utilization. In myocytes, RF enhanced metabolism, metabolic gene expression, and mitochondrial content suggesting RF may target common energetic pathways which control mitochondrial biogenesis. RF appears to increase metabolism immediately following ingestion, although it is unclear if RF provides benefits beyond those provided by caffeine alone. Additional research is needed to examine safety and efficacy for human weight loss.

Exercise has been shown to reduce risk and improve prognosis of several types of cancers. Irisin is a myokine linked to exercise and lean body mass, which is thought to favorably alter metabolism systemically, potentially providing benefit for metabolic disease (including cancer). We evaluated the effects of various concentrations of irisin (with and without post-translational modifications) on malignant and non-malignant breast epithelial cell number, migration and viability. Irisin significantly decreased cell number, migration and viability in malignant MDA-MB-231 cells, without affecting non-malignant MCF-10a cells. Moreover, irisin enhanced the cytotoxic effect of doxorubicin (Dox) when added to a wide spectrum of irisin concentrations in the malignant cell type (with simultaneous reduction in Dox uptake), which was not observed in non-malignant MCF-10a cells. Additionally, we found that irisin decreases malignant cell viability in part through stimulation of caspase activity leading to apoptotic death. Interestingly, we found that irisin suppresses NFκB activation, an opposite effect of other myokines such as tumor necrosis factor alpha (TNF-α). Our observations suggest that irisin may offer therapeutic benefits for breast cancer prevention and treatment possibly through an anti-inflammatory response, induction of apoptotic cell death, or through enhanced tumor sensitivity to common antineoplastic agents such as Dox., (© 2014 UICC.)

Beetroot ( tián cài) juice consumption is of current interest for improving aerobic performance by acting as a vasodilator and possibly through alterations in skeletal muscle metabolism and physiology. This work explored the effects of a commercially available beetroot supplement on metabolism, gene expression, and mitochondrial content in cultured myocytes. C2C12 myocytes were treated with various concentrations of the beetroot supplement for various durations. Glycolytic metabolism and oxidative metabolism were quantified via measurement of extracellular acidification and oxygen consumption, respectively. Metabolic gene expression was measured using quantitative reverse transcription-polymerase chain reaction, and mitochondrial content was assessed with flow cytometry and confocal microscopy. Cells treated with beetroot exhibited significantly increased oxidative metabolism, concurrently with elevated metabolic gene expression including peroxisome proliferator-activated receptor gamma coactivator-1 alpha, nuclear respiratory factor 1, mitochondrial transcription factor A, and glucose transporter 4, leading to increased mitochondrial biogenesis. Our data show that treatment with a beetroot supplement increases basal oxidative metabolism. Our observations are also among the first to demonstrate that beetroot extract is an inducer of metabolic gene expression and mitochondrial biogenesis. These observations support the need for further investigation into the therapeutic and pharmacological effects of nitrate-containing supplements for health and athletic benefits.

Chronic insulin resistance can lead to type II diabetes mellitus, which is also directly influenced by an individual's genetics as well as their lifestyle. Under normal circumstances, insulin facilitates glucose uptake in skeletal muscle and adipose tissue by stimulating glucose transporter 4 (GLUT4) translocation and activity. GLUT4 activity is directly correlated with the ability to clear elevated blood glucose and insulin sensitivity. In diabetes, energy excess and prolonged hyperinsulinemia suppress muscle and adipose response to insulin, in part through reduced GLUT4 membrane levels. This work uniquely describes much of the experimental data demonstrating the effects of various dietary components on GLUT4 expression and translocation in skeletal muscle. These observations implicate several individual dietary chemicals as potential adjuvant therapies in the maintenance of diabetes and insulin resistance., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aims: This work explored the effects of irisin on metabolism, gene expression and mitochondrial content in cultured myocytes., Methods: C2C12 myocytes were treated with various concentrations of irisin for various durations. Glycolysis and oxidative metabolism were quantified by measurement of extracellular acidification and oxygen consumption, respectively. Metabolic gene expression was measured by quantitative real-time polymerase chain reaction (qRT-PCR) and mitochondrial content was assessed by flow cytometry and confocal microscopy., Results: Cells treated with irisin exhibited significantly increased oxidative metabolism. Irisin treatment also significantly increased mitochondrial uncoupling at various doses and durations. Lastly, treatment with irisin also significantly elevated metabolic gene expression including peroxisome proliferator-activated receptor γ coactivator-1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), irisin, glucose transporter 4 (GLUT4) and mitochondrial uncoupling protein 3 (UCP3) leading to increased mitochondrial biogenesis., Conclusions: Our observations are the first to document increased metabolism in myocytes through irisin-mediated induction of mitochondrial biogenesis and uncoupling with corresponding gene expression. These observations support the need for further investigation into the therapeutic and pharmacological effects of irisin, as well as development of irisin-based therapy., (© 2014 John Wiley & Sons Ltd.)

Background: Deregulated energetics is a property of most cancer cells. This phenomenon, known as the Warburg Effect or aerobic glycolysis, is characterized by increased glucose uptake, lactate export and extracellular acidification, even in the presence of oxygen. β-alanine is a non-essential amino acid that has previously been shown to be metabolized into carnosine, which functions as an intracellular buffer. Because of this buffering capacity, we investigated the effects of β-alanine on the metabolic cancerous phenotype., Methods: Non-malignant MCF-10a and malignant MCF-7 breast epithelial cells were treated with β-alanine at 100 mM for 24 hours. Aerobic glycolysis was quantified by measuring extracellular acidification rate (ECAR) and oxidative metabolism was quantified by measuring oxygen consumption rate (OCR). mRNA of metabolism-related genes was quantified by qRT-PCR with corresponding protein expression quantified by immunoblotting, or by flow cytometry which was verified by confocal microscopy. Mitochondrial content was quantified using a mitochondria-specific dye and measured by flow cytometry., Results: Cells treated with β-alanine displayed significantly suppressed basal and peak ECAR (aerobic glycolysis), with simultaneous increase in glucose transporter 1 (GLUT1). Additionally, cells treated with β-alanine exhibited significantly reduced basal and peak OCR (oxidative metabolism), which was accompanied by reduction in mitochondrial content with subsequent suppression of genes which promote mitochondrial biosynthesis. Suppression of glycolytic and oxidative metabolism by β-alanine resulted in the reduction of total metabolic rate, although cell viability was not affected. Because β-alanine treatment reduces extracellular acidity, a constituent of the invasive microenvironment that promotes progression, we investigated the effect of β-alanine on breast cell viability and migration. β-alanine was shown to reduce both cell migration and proliferation without acting in a cytotoxic fashion. Moreover, β-alanine significantly increased malignant cell sensitivity to doxorubicin, suggesting a potential role as a co-therapeutic agent., Conclusion: Taken together, our results suggest that β-alanine may elicit several anti-tumor effects. Our observations support the need for further investigation into the mechanism(s) of action and specificity of β-alanine as a co-therapeutic agent in the treatment of breast tumors.

Leucine has been largely implicated for increasing muscle protein synthesis in addition to stimulating mitochondrial biosynthesis. Limited evidence is currently available on the effects and potential benefits of leucine treatment on skeletal muscle cell glycolytic and oxidative metabolism. This work identified the effects of leucine treatment on oxidative and glycolytic metabolism as well as metabolic rate of human and murine skeletal muscle cells. Human rhabdomyosarcoma cells (RD) and mouse myoblast cells (C2C12) were treated with leucine at either 100 or 500 μM for 24 or 48 h. Glycolytic metabolism was quantified by measuring extracellular acidification rate (ECAR) and oxidative metabolism was quantified by measuring oxygen consumption rate. Peroxisome proliferator-activated receptor coactivator 1 alpha (PGC-1α), an important stimulator of mitochondrial biosynthesis, was quantified using flow cytometry and verified by immunofluorescent confocal microscopy. Mitochondrial content was quantified using mitochondrial and cytochrome C staining measured by flow cytometry and confirmed with confocal microscopy. Treatment with leucine significantly increased both basal and peak oxidative metabolism in both cell models. Leucine treated cells also exhibited significantly greater mitochondrial proton leak, which is associated with heightened energy expenditure. Basal ECAR was significantly reduced in both cell models following leucine treatment, evidence of reduced lactate export and more complete carbohydrate oxidation. In addition, both PGC-1α and cytochrome C expression were significantly elevated in addition to mitochondrial content following 48 h of leucine treatment. Our observations demonstrated few dose-dependent responses induced by leucine; however, leucine treatment did induce a significant dose-dependent expression of PGC-1α in both cell models. Interestingly, C2C12 cells treated with leucine exhibited dose-dependently reduced ATP content, while RD ATP content remain unchanged. Leucine presents a potent dietary constituent with low lethality with numerous beneficial effects for increasing oxidative preference and capacity in skeletal muscle. Our observations demonstrate that leucine can enhance oxidative capacity and carbohydrate oxidation efficiency, as well as verify previous observations of increased mitochondrial content.