ABSTRACT
We investigated the effects of resistance exercise (RE), hydrolysed collagen (HC) ingestion and circulating oestrogen concentration on collagen synthesis in a naturally menstruating female CrossFit athlete. In a double-blind, randomised cross-over design, the participant (36 years; height 1.61 m; mass 82.6 kg) consumed 0 or 30 g HC prior to performing back-squat RE when endogenous circulating oestrogen concentration was low (onset of menses, OM) and high (late follicular phase, LF) during two consecutive menstrual cycles. Ten 5-mL blood samples were collected during each of the four interventions to analyse concentrations of serum 17ß-oestradiol, and biomarkers of type I collagen turnover, that is serum procollagen type I N-terminal propeptide (PINP, a biomarker of collagen synthesis) and plasma ß-isomerised C-terminal telopeptide of type I collagen (ß-CTX, a biomarker of collagen breakdown), as well as the serum concentration of 18 collagen amino acids. 17ß-Oestradiol concentration was 5-fold higher at LF (891 ± 116 pmol L-1) than OM (180 ± 13 pmol L-1). The PINP concentration × time area under the curve (AUC) was higher in the 30 g HC OM intervention (201 µg L-1 h) than the 30 g HC LF (144 µg L-1 h), 0 g HC OM (151 µg L-1 h) and 0 g HC LF (122 µg L-1 h) interventions. ß-CTX concentration decreased 1.4-fold from pre-RE to 6 h post-RE in all interventions. Thus, high circulating oestrogen concentration was associated with lower collagen synthesis following RE in this female athlete. Ingesting 30 g HC, however, augmented the collagen synthesis response at LF and particularly at OM. HIGHLIGHTS: What is the central question of this study? Does resistance exercise-induced collagen synthesis vary according to circulating oestrogen concentration in a naturally menstruating female athlete, and if so, does hydrolysed collagen ingestion have any impact? What is the main finding and its importance? Exercise-induced collagen synthesis was low when circulating oestrogen concentration was high and vice versa. However, ingesting 30 g hydrolysed collagen prior to exercise reduced the negative effect of oestrogen on collagen synthesis. As high circulating oestrogen has been associated with greater injury risk in females, supplementing exercise with hydrolysed collagen may help protect these tissues from injury.
ABSTRACT
The mental health treatment gap remains wide across the world despite mental illness being a significant cause of disability globally. Both end-user and healthcare provider perspectives are critical to understanding barriers to mental healthcare and developing interventions. However, the views of providers are relatively understudied. In this review, we synthesized findings from current literature regarding providers' perspectives on barriers to mental healthcare in Canada. We searched Medline, PsycINFO, Embase, and CINAHL for eligible Canadian studies published since 2000. Analysis and quality assessment were conducted on the included studies. Of 4,773 reports screened, 29 moderate-high quality studies were reviewed. Five themes of barriers emerged: health systems availability and complexity (reported in 72% of the studies), work conditions (55%), training/education (52%), patient accessibility (41%), and identity-based sensitivity (17%). Common barriers included lack of resources, fragmented services, and gaps in continuing education. Interestingly, clinicians often cited confusion in determining the ideal service for patients due to an overwhelming number of potential services without clear descriptions. These five domains of barriers present a synthesized review of areas of improvement for mental healthcare spanning both patients and clinicians. Canadian mental health systems face a need to improve capacity, clinician training, and in particular service navigability and collaboration.
ABSTRACT
PURPOSE: Stroke survivors must complete large amounts of practice to achieve functional improvements but spend many hours inactive during their rehabilitation. We conducted a mixed methods process evaluation exploring factors affecting the success of a 6-month behaviour change intervention to increase use of ward-based practice books. METHODS: Audits of the presence, quality and use of ward based-practice books were conducted, alongside focus groups with staff (n = 19), and interviews with stroke survivors (n = 3) and family members (n = 4). Quantitative data were analysed descriptively. Focus group and interview transcripts were analysed using qualitative analysis. RESULTS: Personal (patient-related) factors (including severe weakness, cognitive and communication deficits of stroke survivors), staff coaching skills, understanding and beliefs about their role, affected practice book use. Staff turnover, nursing shift work and a lack of action planning reduced success of the behaviour change intervention. CONCLUSIONS: Staff with the necessary skills and understanding of their role in implementing ward practice overcame personal (patient-related) factors and assisted stroke survivors to successfully practice on the ward. To improve success of the intervention, repeated training of new staff is required. In addition to audit and feedback, team action planning is needed around the presence, quality, and use of ward practice books.
Ward-based practice books are one evidence-based strategy that can be used by rehabilitation teams to increase the amount of practice completed by stroke survivors during inpatient rehabilitation.Stroke survivors' personal factors (including severe weakness, cognitive and communication deficits), staff beliefs about their role and coaching skills, affected stroke survivors ability to practice on the ward using practice books.Staff with the necessary skills, understanding and belief about their role in implementing ward practice can overcome personal (patient related) factors (such as severe weakness) and assist stroke survivors to successfully practice on the ward.To increase the success of ward practice, repeated booster training of staff is required along with audit and feedback and team action planning on the presence, quality, and use of ward practice books.
ABSTRACT
Rhabdomyosarcoma is the commonest soft tissue sarcoma in children. Around one-third of children with rhabdomyosarcoma experience relapse or have refractory disease, which is associated with a poor prognosis. This systematic review of early phase studies in pediatric relapsed/refractory rhabdomyosarcoma was conducted to inform future research and provide accurate information to families and clinicians making difficult treatment choices. Nine databases and five trial registries were searched in June 2021. Early phase studies of interventions for disease control in patients under 18 years old with relapsed/refractory rhabdomyosarcoma were eligible. No language/geographic restrictions were applied. Studies conducted after 2000 were included. Survival outcomes, response rates, quality of life and adverse event data were extracted. Screening, data extraction and quality assessment (Downs and Black Checklist) were conducted by two researchers. Owing to heterogeneity in the included studies, narrative synthesis was conducted. Of 16,965 records screened, 129 published studies including over 1100 relapsed/refractory rhabdomyosarcoma patients were eligible. Most studies evaluated systemic therapies. Where reported, 70% of studies reported a median progression-free survival ≤6 months. Objective response rate was 21.6%. Adverse events were mostly hematological. One-hundred and seven trial registry records of 99 studies were also eligible, 63 of which report they are currently recruiting. Study quality was limited by poor and inconsistent reporting. Outcomes for children with relapsed/refractory rhabdomyosarcoma who enroll on early phase studies are poor. Improving reporting quality and consistency would facilitate the synthesis of early phase studies in relapsed/refractory rhabdomyosarcoma (PROSPERO registration: CRD42021266254).
Subject(s)
Rhabdomyosarcoma , Sarcoma , Child , Humans , Adolescent , Quality of Life , Neoplasm Recurrence, Local/drug therapy , Rhabdomyosarcoma/drug therapy , Progression-Free Survival , Antineoplastic Combined Chemotherapy Protocols/adverse effectsABSTRACT
A survey sent to fellows of the Australian and New Zealand College of Anaesthetists (ANZCA) aimed to document issues affecting gender equity in the anaesthesia workplace. A response rate of 38% was achieved, with women representing a greater proportion of respondents (64.2%). On average women worked fewer hours than men and spent a larger percentage of time in public practice; however, satisfaction rates were similar between genders. There was a gender pay gap which could not be explained by the number of hours worked or years since achieving fellowship. The rates of bullying and harassment were high among all genders and have not changed in 20 years since the first gender equity survey by Strange Khursandi in 1998. Women perceived that they were more likely to be discriminated against particularly in the presence of other sources of discrimination, and highlighted the importance of the need for diversity and inclusion in anaesthetic workplaces. Furthermore, women reported higher rates of caregiving and unpaid domestic responsibilities, confirming that anaesthetists are not immune to the factors affecting broader society despite our professional status. The overall effect was summarised by half of female respondents reporting that they felt their gender was a barrier to a career in anaesthesia. While unable to be included in statistics due to low numbers, non-binary gendered anaesthetists responded and must be included in all future work. The inequities documented here are evidence that ANZCA's gender equity subcommittee must continue promoting and implementing policies in workplaces across Australia and New Zealand.
Subject(s)
Anesthesia , Anesthesiology , Humans , Female , Male , Australia , Surveys and Questionnaires , Workplace , SexismABSTRACT
Post-assessments psychometric reports are a vital component of the assessment cycle to ensure that assessments are reliable, valid and fair to make appropriate pass-fail decisions. Students' scores can be summarised by examination of frequency distributions, central tendency measures and dispersion measures. Item discrimination indicies to assess the quality of items, and distractors that differentiate between students achieving or not achieving the learning outcomes are key. Estimating individual item reliability and item validity indices can maximise test-score reliability and validity. Test accuracy can be evaluated by assessing test reliability, consistency and validity and standard error of measurement can be used to measure the variation. Standard setting, even by experts, may be unreliable and reality checks such as the Hofstee method, P values and correlation analysis can improve validity. The Rasch model of student ability and item difficulty assists in modifying assessment questions, pinpointing areas for additional instruction. We propose 12 tips to support test developers in interpreting structured psychometric reports, including analysis and refinement of flawed items and ensuring fair assessments with accurate and defensible marks.
Subject(s)
Educational Measurement , Students, Medical , Humans , Psychometrics , Reproducibility of Results , Educational Measurement/methods , LearningABSTRACT
Phenomenon: Ad hoc entrustment decisions reflect a clinical supervisor's estimation of the amount of supervision a trainee needs to successfully complete a task in the moment. These decisions have important consequences for patient safety, trainee learning, and preparation for independent practice. Determinants of these decisions have previously been described but have not been well described for acute care contexts such as critical care and emergency medicine. The ad hoc entrustment of trainees caring for vulnerable patient populations is a high-stakes decision that may differ from other contexts. Critically ill patients and children are vulnerable patient populations, making the ad hoc entrustment of a pediatric critical care medicine (PCCM) fellow a particularly high-stakes decision. This study sought to characterize how ad hoc entrustment decisions are made for PCCM fellows through faculty ratings of vignettes. The authors investigated how acuity, relationship, training level, and task interact to influence ad hoc entrustment decisions. Approach: A survey containing 16 vignettes that varied by four traits (acuity, relationship, training level, and task) was distributed to U.S. faculty of pediatric critical care fellowships in 2020. Respondents determined an entrustment level for each case and provided demographic data. Entrustment ratings were dichotomized by "high entrustment" versus "low entrustment" (direct supervision or observation only). The authors used logistic regression to evaluate the individual and interactive effects of the four traits on dichotomized entrustment ratings. Findings: One hundred seventy-eight respondents from 30 institutions completed the survey (44% institutional response rate). Acuity, relationship, and task all significantly influenced the entrustment level selected but did not interact. Faculty most frequently selected "direct supervision" as the entrustment level for vignettes, including for 24% of vignettes describing fellows in their final year of training. Faculty rated the majority of vignettes (61%) as "low entrustment." There was no relationship between faculty or institutional demographics and the entrustment level selected. Insights: As has been found in summative entrustment for pediatrics, internal medicine, and surgery trainees, PCCM fellows often rated at or below the "direct supervision" level of ad hoc entrustment. This may relate to declining opportunities to practice procedures, a culture of low trust propensity among the specialty, and/or variation in interpretation of entrustment scales.
ABSTRACT
BACKGROUND: Resistance exercise (RE) stimulates collagen synthesis in skeletal muscle and tendon but there is limited and equivocal evidence regarding an effect of collagen supplementation and exercise on collagen synthesis. Furthermore, it is not known if a dose-response exists regarding the effect of hydrolyzed collagen (HC) ingestion and RE on collagen synthesis. OBJECTIVE: To determine the HC dose-response effect on collagen synthesis after high-intensity RE in resistance-trained young men. METHODS: Using a double-blind, randomized crossover design, 10 resistance-trained males (age: 26 ± 3 y; height: 1.77 ± 0.04 m; mass: 79.7 ± 7.0 kg) ingested 0 g, 15 g, or 30 g HC with 50 mg vitamin C 1 h before performing 4 sets' barbell back squat RE at 10-repetition maximum load, after which they rested for 6 h. Blood samples were collected throughout each of the 3 interventions to analyze procollagen type â N-terminal propeptide (PINP) and ß-isomerized C-terminal telopeptide of type I collagen (ß-CTX) concentration, and the concentration of 18 collagen amino acids. RESULTS: The serum PINP concentration × time area under the curve (AUC) was greater for 30 g (267 ± 79 µg·L-1·h) than for 15 g (235 ± 70 µg·L-1·h, P = 0.013) and 0 g HC (219 ± 88 µg·L-1·h, P = 0.002) but there was no difference between 0 and 15 g HC (P = 0.225). The AUCs of glycine and proline were greater for 30 g than for 15 and 0 g HC (P < 0.05). Plasma ß-CTX concentration decreased from -1 to +6 h (P < 0.05), with no differences between interventions. CONCLUSIONS: Ingesting 30 g HC before high-intensity RE augments whole-body collagen synthesis more than 15 g and 0 g HC in resistance-trained young males.
ABSTRACT
BACKGROUND: After an initial period of uncertainty during the COVID-19 pandemic, medical universities responded to the pandemic by innovating their methods of teaching-learning and assessment. This scoping review aimed to identify innovations in assessment in medical, dental and nursing education at the undergraduate and postgraduate levels during the pandemic. METHODS: This review was conducted utilising Arksey and O'Malley's framework where three electronic databases-PubMed, Embase and Web of Science-were systematically searched in February 2022 for articles in English describing innovations in assessments published in or after January 2020. RESULTS: A total of 70 articles were included in the review. Among the primary research articles, 82.1% reported online assessment, 76.1% were related to medical speciality, 74.6% described assessment at the undergraduate level, 68.7% described summative assessment and 58.2% reported assessment of practical skills. All assessments of theoretical knowledge were done virtually with MCQ being the most used assessment tool and virtual OSCE being the most popular assessment tool to assess practical skills; however, it was acknowledged that the assessment of procedural skills was its limitation. Although the studies described the newer forms of assessments as feasible and acceptable, few studies reported the reliability and validity of the assessments. CONCLUSIONS: This scoping review identified several innovations in assessment during the COVID-19 pandemic with an overall shift towards virtual or hybrid forms of assessment. However, there was a dearth of evidence regarding the effectiveness of these assessment tools suggesting a need for more research before the tools can be implemented post-pandemic.
Subject(s)
COVID-19 , Medicine , Humans , COVID-19/epidemiology , Pandemics , Reproducibility of ResultsABSTRACT
Objectives: To measure intra-standard-setter variability and assess the variations between the pass marks obtained from Angoff ratings, guided by the latent trait theory as the theoretical model. Methods: A non-experimental cross-sectional study was conducted to achieve the purpose of the study. Two knowledge-based tests were administered to 358 final-year medical students (223 females and 135 males) as part of their normal summative programme of assessments. The results of judgmental standard-setting using the Angoff method, which is widely used in medical schools, were used to determine intra-standard-setter inconsistency using the three-parameter item response theory (IRT). Permission for this study was granted by the local Research Ethics Committee of the University of Nottingham. To ensure anonymity and confidentiality, all identifiers at the student level were removed before the data were analysed. Results: The results of this study confirm that the three-parameter IRT can be used to analyse the results of individual judgmental standard setters. Overall, standard-setters behaved fairly consistently in both tests. The mean Angoff ratings and conditional probability were strongly positively correlated, which is a matter of inter-standard-setter validity. Conclusions: We recommend that assessment providers adopt the methodology used in this study to help determine inter and intra-judgmental inconsistencies across standard setters to minimise the number of false positive and false negative decisions.
Subject(s)
Academic Performance , Education, Medical , Program Evaluation , Humans , Male , Female , Students, Medical , Education, Medical/standards , Cross-Sectional Studies , Models, TheoreticalABSTRACT
OBJECTIVE: This implementation study aimed to enhance the key elements of clinical practice goal-setting across 5 rehabilitation services. DESIGN: This study followed a participatory action research approach guided by the Knowledge to Action framework. METHODS: Medical record audits and structured client interviews were conducted prior to and following 12 weeks of implementation, in order to evaluate the success of the goal-setting implementation package. RESULTS: Medical record audits and interviews conducted pre-implementation (audits n = 132, interviews n = 64), post-implementation (audits n = 130, interviews n = 56) and at 3-month follow-up (audits n = 30) demonstrated varied success across sites. Following implementation 2 sites significantly improved their common goal focus (site 1 p ≤ 0.001, site 2 p = 0.005), these sites also demonstrated a significant increase in clients reporting that they received copies of their rehabilitation goals (site 1 p ≤ 0.001, site 2 p ≤ 0.001). Four sites improved client action planning, feedback and review, and 3 sites enhanced their specificity of goal-setting. At 3-month follow-up 4 sites had continued to improve their common goal focus; however, all sites decreased the specificity of their goal-setting. CONCLUSION: Elements of the implementation package were successful at enhancing the goal-setting process; however, how the package is implemented within the team may impact outcomes.
Subject(s)
Goals , Rehabilitation , Humans , Rehabilitation/standards , Benchmarking , Clinical AuditABSTRACT
We investigated the effect of collagen hydrolysate supplementation on changes in patellar tendon (PT) properties after 10 weeks' training in female soccer players from a Football Association Women's Super League Under 21 s squad. We pair-matched n = 17 players (age: 17 ± 0.9 years; height: 1.66 ± 0.06 m; mass: 58.8 ± 8.1 kg) for baseline knee extension (KE) maximum isometric voluntary contraction (MIVC) torque, age, height, and body mass, and randomly assigned them to collagen (COL) or placebo (PLA) groups (COL n = 8, PLA n = 9). Participants consumed 30 g collagen hydrolysate supplementation or energy-matched PLA (36.5 g maltodextrin, 8.4 g fructose) and plus both groups consumed 500 mg vitamin C, after each training session, which comprised bodyweight strength-, plyometric- and/or pitch-based exercise 3 days/week for 10 weeks in-season. We assessed KE MIVC torque, vastus lateralis muscle thickness and PT properties using isokinetic dynamometry and ultrasonography before and after 10 weeks' soccer training. KE MIVC torque, muscle thickness and tendon cross-sectional area did not change after training in either group. However, COL increased PT stiffness [COL, +18.0 ± 12.2% (d = 1.11) vs. PLA, +5.1 ± 10.4% (d = 0.23), p = 0.049] and Young's modulus [COL, +17.3 ± 11.9% (d = 1.21) vs. PLA, +4.8 ± 10.3% (d = 0.23), p = 0.035] more than PLA. Thus, 10 weeks' in-season soccer training with COL increased PT mechanical and material properties more than soccer training alone in high-level female soccer players. Future studies should investigate if collagen hydrolysate supplementation can improve specific aspects of female soccer performance requiring rapid transference of force, and if it can help mitigate injury risk in this under-researched population.
ABSTRACT
In 1999, in a review by Beardsley, the potential of adult stem cells, in repair and regeneration was heralded (Beardsley Sci Am 281:30-31, 1999). Since then, the field of regenerative medicine has grown exponentially, with the capability of restoring or regenerating the function of damaged, diseased or aged human tissues being an underpinning motivation. If successful, stem cell therapies offer the potential to treat, for example degenerative diseases. In the subsequent 20 years, extensive progress has been made in the arena of adult stem cells (for a recent review see (Zakrzewski et al. Stem Cell Res Ther 10:68, 2019)). Prior to the growth of the adult stem cell research arena, much focus had been placed on the potential of embryonic stem cells (ESCs). The first research revealing the potential of these cells was published in 1981, when scientists reported the ability of cultured stem cells from murine embryos, to not only self-renew, but to also become all cells of the three germ layers of the developing embryo (Evans and Kaufman Nature 292:154-156, 1981), (Martin Proc Natl Acad Sci U S A 78:7634-7638, 1981). It took almost 20 years, following these discoveries, for this technology to translate to human ESCs, using donated human embryos. In 1998, Thomson et al. reported the creation of the first human embryonic cell line (Thomson et al. Science 282:1145-1147, 1998). However, research utilising human ESCs was hampered by ethical and religious constraints and indeed in 2001 George W. Bush restricted US research funding to human ESCs, which had already been banked. The contentious nature of this arena perhaps facilitated the use of and the research potential for adult stem cells. It is beyond the scope of this review to focus on ESCs, although their potential for enhancing our understanding of human development is huge (for a recent review see (Cyranoski Nature 555:428-430, 2018)). Rather, although ESCs and their epigenetic regulation will be introduced for background understanding, the focus will be on stem cells more generally, the role of epigenetics in stem cell fate, skeletal muscle, skeletal muscle stem cells, the impact of ageing on muscle wasting and the mechanisms underpinning loss, with a focus on epigenetic adaptation.
Subject(s)
Epigenesis, Genetic , Muscle, Skeletal , Adult , Mice , Humans , Animals , Aged , Muscle, Skeletal/physiology , Cell Differentiation , Stem Cells , AgingABSTRACT
Proteins in the cellular milieu reside in environments crowded by macromolecules and other solutes. Although crowding can significantly impact the protein folded state stability, most experiments are conducted in dilute buffered solutions. To resolve the effect of crowding on protein stability, we use 19 F nuclear magnetic resonance spectroscopy to follow the reversible, two-state unfolding thermodynamics of the N-terminal Src homology 3 domain of the Drosophila signal transduction protein drk in the presence of polyethylene glycols (PEGs) of various molecular weights and concentrations. Contrary to most current theories of crowding that emphasize steric protein-crowder interactions as the main driving force for entropically favored stabilization, our experiments show that PEG stabilization is accompanied by significant heat release, and entropy disfavors folding. Using our newly developed model, we find that stabilization by ethylene glycol and small PEGs is driven by favorable binding to the folded state. In contrast, for larger PEGs, chemical or soft PEG-protein interactions do not play a significant role. Instead, folding is favored by excluded volume PEG-protein interactions and an exothermic nonideal mixing contribution from release of confined PEG and water upon folding. Our results indicate that crowding acts through molecular interactions subtler than previously assumed and that interactions between solution components with both the folded and unfolded states must be carefully considered.
Subject(s)
Polyethylene Glycols , Proteins , Animals , Proteins/chemistry , Macromolecular Substances/chemistry , Thermodynamics , Polyethylene Glycols/chemistry , Magnetic Resonance Spectroscopy , Drosophila , Protein FoldingABSTRACT
NEW FINDINGS: What is the central question of this study? Does the concentration of human serum affect skeletal muscle differentiation and cellular respiration of LHCN-M2 myoblasts? What is the main finding and its importance? The concentration of serum used to differentiate LHCN-M2 skeletal muscle cells impacts the coverage of myosin heavy chain, a marker of terminally differentiated myotubes. Normalisation of mitochondrial function data to total protein negates the differences observed in absolute values, which differ as a result of increased protein content when differentiation occurs with increasing concentration of serum. ABSTRACT: The human LHCN-M2 myoblast cell line has the potential to be used to investigate skeletal muscle development and metabolism. Experiments were performed to determine how different concentrations of human serum affect myogenic differentiation and mitochondrial function of LHCN-M2 cells. LHCN-M2 myoblasts were differentiated in serum-free medium, 0.5% or 2% human serum for 5 and 10 days. Myotube formation was assessed by immunofluorescence staining of myosin heavy chain (MHC) and molecularly by mRNA expression of Myogenic differentiation 1 (MYOD1) and Myoregulatory factor 5 (MYF5). Following differentiation, mitochondrial function was assessed to establish the impact of serum concentration on mitochondrial function. Time in differentiation increased mRNA expression of MYOD1 (day 5, 6.58 ± 1.33-fold; and day 10, 4.28 ± 1.71-fold) (P = 0.012), while suppressing the expression of MYF5 (day 5, 0.21 ± 0.11-fold; and day 10, 0.06 ± 0.03-fold) (P = 0.001), regardless of the serum concentration. Higher serum concentrations increased MHC area (serum free, 11.92 ± 0.85%; 0.5%, 23.10 ± 5.82%; 2%, 43.94 ± 8.92%) (P = 0.001). Absolute basal respiration approached significance (P = 0.06) with significant differences in baseline oxygen consumption rate (P = 0.025) and proton leak (P = 0.006) when differentiated in 2% human serum, but these were not different between conditions when normalised to total protein. Our findings show that increasing concentrations of serum of LHCN-M2 skeletal muscle cells into multinucleated myotubes, but this does not affect relative mitochondrial function.
Subject(s)
Muscle Fibers, Skeletal , Myosin Heavy Chains , Humans , Myosin Heavy Chains/metabolism , Muscle Fibers, Skeletal/metabolism , Myoblasts/metabolism , Cell Differentiation , RNA, Messenger/metabolism , Muscle, Skeletal/physiology , Muscle Development/geneticsABSTRACT
Myonuclei transcriptionally regulate muscle fibers during homeostasis and adaptation to exercise. Their subcellular location and quantity are important when characterizing phenotypes of myopathies, the effect of treatments, and understanding the roles of satellite cells in muscle adaptation and muscle "memory." Difficulties arise in identifying myonuclei due to their proximity to the sarcolemma and closely residing interstitial cell neighbors. We aimed to determine to what extent (pericentriolar material-1) PCM1 is a specific marker of myonuclei in vitro and in vivo. Single isolated myofibers and cross sections from mice and humans were studied from several models including wild-type and Lamin A/C mutant mice after functional overload and damage and recovery in humans following forced eccentric contractions. Fibers were immunolabeled for PCM1, Pax7, and DNA. C2C12 myoblasts were also studied to investigate changes in PCM1 localization during myogenesis. PCM1 was detected at not only the nuclear envelope of myonuclei in mature myofibers and in newly formed myotubes but also centrosomes in proliferating myogenic precursors, which may or may not fuse to join the myofiber syncytium. PCM1 was also detected in nonmyogenic nuclei near the sarcolemma, especially in regenerating areas of the Lmna+/ΔK32 mouse and damaged human muscle. Although PCM1 is not completely specific to myonuclei, the impact that PCM1+ macrophages and interstitial cells have on myonuclei counts would be small in healthy muscle. PCM1 may prove useful as a marker of satellite cell dynamics due to the distinct change in localization during differentiation, revealing satellite cells in their quiescent (PCM1-), proliferating (PCM1+ centrosome), and prefusion states (PCM1+ nuclear envelope).