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1.
Br J Ophthalmol ; 108(9): 1263-1268, 2024 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-38290803

RESUMO

BACKGROUND: The purpose of the study is to compare visual acuity, complications and outer retinal integrity following subretinal fluid (SRF) drainage from the peripheral retinal breaks (PRBs) versus posterior retinotomy (PR) versus perfluorocarbon liquid (PFCL) for macula-off rhegmatogenous retinal detachments (RRDs) at 2 years post-surgery. METHODS: Retrospective analysis of 300 consecutive patients with primary RRD undergoing 23-gauge pars plana vitrectomy with SRF drainage through (1) PRB (n=100), (2) PR (n=100) or (3) with PFCL (n=100). Primary outcomes were visual acuity (best-corrected visual acuity (BCVA)) and complications (cystoid macular oedema (CMO) and epiretinal membrane (ERM)). Secondary outcomes were discontinuity of the external limiting membrane (ELM), ellipsoid zone (EZ) and interdigitation zone (IDZ) at 2 years post-surgery. RESULTS: Mean (±SD) logMAR BCVA at 24 months was better in the PRB compared with PR and PFCL, with PFCL having the worst BCVA (PRB 0.5±0.6; PR 0.7±0.5; PFCL 0.9±0.7, p=0.001). CMO was higher with PFCL (PRB 29.7%; PR 30.2%; PFCL 45.9%, p=0.0015) and ERM formation was higher in PR (PRB 62.6%; PR 93.0%; PFCL 68.9%, p=0.002). There were no differences in ELM or EZ discontinuity. However, IDZ discontinuity was higher in PFCL (PRB 34%; PR 27%; PFCL 46%, p=0.002) at 2 years. CONCLUSIONS: Visual acuity was worse and discontinuity of the IDZ and CMO was greater in eyes with PFCL-assisted drainage compared with PRB or PR. Drainage technique may impact long-term visual acuity and photoreceptor integrity.


Assuntos
Drenagem , Fóvea Central , Descolamento Retiniano , Líquido Sub-Retiniano , Tomografia de Coerência Óptica , Acuidade Visual , Vitrectomia , Humanos , Vitrectomia/métodos , Descolamento Retiniano/cirurgia , Descolamento Retiniano/fisiopatologia , Acuidade Visual/fisiologia , Estudos Retrospectivos , Feminino , Masculino , Drenagem/métodos , Pessoa de Meia-Idade , Idoso , Resultado do Tratamento , Fluorocarbonos/administração & dosagem , Seguimentos
2.
GMS Ophthalmol Cases ; 12: Doc14, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35912126

RESUMO

Objective: To review a case of toxoplasmosis chorioretinitis mimicking cytomegalovirus retinitis in an immunocompromised patient following bone marrow transplantation. Methods: Retrospective chart review of a 14-year-old female who had a history of leukemia and allogeneic bone marrow transplants prior to her ocular symptoms. Results: Anterior chamber fluid analysis was positive for Toxoplasma gondii. The patient responded well when cytomegalovirus retinitis treatment was switched to intravitreal clindamycin with systemic sulfadiazine and prednisone. Conclusions: This case demonstrates the challenges of diagnosing and treating retinal infections in immunocompromised patients as they may present with atypical findings that mimic other pathologies and may have contraindications against standard treatment.

3.
Am J Ophthalmol ; 241: 227-237, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35597323

RESUMO

PURPOSE: To compare visual acuity and photoreceptor integrity following pars plana vitrectomy with drainage from the peripheral retinal break(s) (PRB), posterior retinotomy (PR), or perfluorocarbon liquid (PFCL) for macula-off rhegmatogenous retinal detachment. DESIGN: Retrospective consecutive interventional comparative clinical study. METHODS: 300 consecutive patients (300 eyes) with primary macula-off rhegmatogenous retinal detachment underwent 23-gauge pars plana vitrectomy with subretinal fluid drainage through PRB (n = 100), PR (n = 100), or with PFCL (n = 100). Visual acuity and spectral-domain optical coherence tomography were performed preoperatively and at 3, 6, and 12 months postoperatively. Primary outcomes were visual acuity and discontinuity of the external limiting membrane, ellipsoid zone, interdigitation zone, and retinal pigment epithelium at 1 year. RESULTS: Baseline characteristics were similar. Single-operation reattachment rates were as follows: PRB 86%, PR 85%, and PFCL 83% (P = .9). Mean (±SD) logMAR visual acuity at 1 year was greater with PRB and PR compared with PFCL (PRB 0.6 ± 0.5, PR 0.7 ± 0.6, PFCL 0.9 ± 0.6, P = .002). There was an association between drainage technique and discontinuity of the external limiting membrane (PRB 26%, PR 24%, PFCL 44%, P = .001), ellipsoid zone (PRB 29%, PR 31%, PFCL 49%, P < .001), and interdigitation zone (PRB 43%, PR 39%, PFCL 56%, P = .004). There was an association between drainage technique and risk of cystoid macular edema (PRB 28%, PR 39%, PFCL 46%, P = .003) and epiretinal membrane (PRB 64%, PR 90%, PFCL 61%, P < .001). CONCLUSIONS: PFCL-assisted drainage is associated with worse visual acuity and greater risk of outer retinal band discontinuity and cystoid macular edema compared with PRB or PR. PR had a greater risk of epiretinal membrane compared with PRB and PFCL. PRB had the best outcomes overall. Drainage technique may impact long-term anatomic and functional outcomes.


Assuntos
Membrana Epirretiniana , Fluorocarbonos , Edema Macular , Descolamento Retiniano , Drenagem/métodos , Membrana Epirretiniana/cirurgia , Humanos , Edema Macular/cirurgia , Descolamento Retiniano/diagnóstico , Descolamento Retiniano/cirurgia , Estudos Retrospectivos , Líquido Sub-Retiniano , Tomografia de Coerência Óptica/métodos , Vitrectomia/métodos
4.
J Appl Physiol (1985) ; 127(5): 1419-1426, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31513447

RESUMO

Skeletal muscle satellite cells (SC) play an important role in muscle repair following injury. The regulation of SC activity is governed by myogenic regulatory factors (MRF), including MyoD, Myf5, myogenin, and MRF4. The mRNA expression of these MRF in humans following muscle damage has been predominately measured in whole muscle homogenates. Whether the temporal expression of MRF in a whole muscle homogenate reflects SC-specific expression of MRF remains largely unknown. Sixteen young men (23.1 ± 1.0 yr) performed 300 unilateral eccentric contractions (180°/s) of the knee extensors. Percutaneous muscle biopsies from the vastus lateralis were taken before (Pre) and 48 h postexercise. Fluorescence-activated cell sorting analysis was utilized to purify NCAM+ muscle SC from the whole muscle homogenate. Forty-eight hours post-eccentric exercise, MyoD, Myf5, and myogenin mRNA expression were increased in the whole muscle homogenate (~1.4-, ~4.0-, ~1.7-fold, respectively, P < 0.05) and in isolated SC (~19.3-, ~17.5-, ~58.9-fold, respectively, P < 0.05). MRF4 mRNA expression was not increased 48 h postexercise in the whole muscle homogenate (P > 0.05) or in isolated SC (P > 0.05). In conclusion, our results suggest that the directional changes in mRNA expression of the MRF in a whole muscle homogenate in response to acute eccentric exercise reflects that observed in isolated muscle SC.NEW & NOTEWORTHY The myogenic program is controlled via transcription factors referred to as myogenic regulatory factors (MRF). Previous studies have derived MRF expression from whole muscle homogenates, but little work has examined whether the mRNA expression of these transcripts reflects the pattern of expression in the actual population of satellite cells (SC). We report that MRF expression from an enriched SC population reflects the directional pattern of expression from skeletal muscle biopsy samples following eccentric contractions.


Assuntos
Exercício Físico/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/metabolismo , Fatores de Regulação Miogênica/biossíntese , Células Satélites de Músculo Esquelético/metabolismo , Expressão Gênica , Humanos , Masculino , Fatores de Regulação Miogênica/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Adulto Jovem
5.
Ophthalmol Glaucoma ; 2(2): 78-85, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32672607

RESUMO

PURPOSE: To determine how well microinvasive glaucoma surgical (MIGS) trials conform to the World Glaucoma Association (WGA) guidelines. Lack of well-designed MIGS studies hinders meaningful evaluation of these technologies. DESIGN: Cross-sectional literature survey. METHODS: Using a predefined search strategy, the following databases were searched for comparative trials involving MIGS in the English peer-reviewed literature from January 1, 2000, through June 21, 2018: Medline, EMBASE, BIOSIS, Cochrane, and Web of Science. From the WGA guidelines, 53 outcomes were selected for evaluation: methodology (n = 31), definition of success (n = 7), ethics (n = 10), postoperative complications (n = 1), economic evaluation (n = 1), and statistical reporting (n = 3). Each article was assessed by 2 reviewers; differences were resolved by consensus. RESULTS: Twenty-five eligible publications were identified: 10 randomized controlled trials (RCTs) and 15 nonrandomized comparative trials (non-RCTs). The mean follow-up was 19.9±11.6 months (range, 6-48 months). The mean number of outcomes adhering to the WGA guidelines of the 53 evaluated was 24.2±6.1 (45.6% compliance): 28.0±6.2 (52.8%) and 21.6±4.7 (40.8%) for RCTs and non-RCTs, respectively (P = 0.01). Mean percent compliance for each subsection were: methodology, 48.8%; definition of success, 21.1%; ethics, 55.6%; postoperative complications, 88%; economic evaluation, 0%; and statistical reporting, 37.3%. In 16 studies (64%), at least 1 author reported an association with the industry. Thirty-two percent of studies reported an author being a shareholder. Twenty-four percent of studies had an industry employee author. The primary intraocular pressure (IOP) end point was defined as both an upper limit and percentage reduction in only 4 studies (16%; 1 RCT, 3 non-RCTs). An IOP-based survival curve was provided in 7 studies (28%; none of the RCTs). Two studies (8%) included an IOP scatterplot. Twelve studies (48%) reported 95% confidence intervals. Only 4 studies (16%) used the mean of 3 diurnal IOP readings as the baseline IOP. CONCLUSIONS: Published comparative MIGS trials show low adherence (45.6%) to the WGA guidelines. Development of standardized methodology and outcomes could enhance interpretation and transparency of study results and facilitate comparisons between trials. Authors and journals should be encouraged to follow the WGA guidelines.


Assuntos
Ensaios Clínicos como Assunto , Cirurgia Filtrante/normas , Glaucoma/cirurgia , Fidelidade a Diretrizes , Procedimentos Cirúrgicos Minimamente Invasivos/normas , Sociedades Médicas , Estudos Transversais , Cirurgia Filtrante/métodos , Humanos , Pressão Intraocular
6.
Can J Ophthalmol ; 51(5): 378-381, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27769330

RESUMO

OBJECTIVE: The purpose of this study was to investigate the extent of agreement between physicians and patients in reporting ocular history and to determine whether there are any predictive factors for physician-patient consensus. DESIGN: Retrospective chart review. PARTICIPANTS: Between June and September 2014, adult patients undergoing cataract surgery were recruited for the study. METHODS: Before surgery, patient demographics and self-reported ocular history were extracted from a prospectively collected database. Medical charts were retrospectively examined to retrieve physician-reported ocular history. RESULTS: One hundred and thirty-eight patients participated. Mean cohort logMAR visual acuity was 0.46 ± 0.34 (Snellen equivalent of approximately 20/60) and mean age was 74.1 ± 8.3 years. For glaucoma, Cohen's kappa revealed a moderate-to-good concordance between physicians and patients (κ = 0.604), whereas a poor-to-fair level of agreement existed in reporting maculopathy, such as age-related macular degeneration and macular holes (κ = 0.254). The logistic regression model revealed that preoperative visual acuity (p = 0.223), sex (p = 0.736), age (p = 0.910), and education (p = 0.738) were not significant predictors of physician-patient agreement. CONCLUSIONS: The accuracy of patient-reported ocular history varies by pathology. Self-reported glaucoma history is consistent between patients and physicians; however, patients under-report the diagnosis of maculopathy. Age, sex, and level of education do not appear to influence patient-reported accuracy of ocular comorbidities.


Assuntos
Anamnese/normas , Oftalmologistas/estatística & dados numéricos , Pacientes/estatística & dados numéricos , Relações Médico-Paciente , Idoso , Idoso de 80 Anos ou mais , Catarata/diagnóstico , Extração de Catarata , Escolaridade , Feminino , Glaucoma/diagnóstico , Humanos , Degeneração Macular/diagnóstico , Masculino , Reprodutibilidade dos Testes , Estudos Retrospectivos
7.
Am J Physiol Regul Integr Comp Physiol ; 308(8): R734-41, 2015 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-25695287

RESUMO

Mitochondrial dysfunction may contribute to age-associated muscle atrophy. Previous data has shown that resistance exercise (RE) increases mitochondrial gene expression and enzyme activity in older adults; however, the acute response to RE has not been well characterized. To characterize the acute mitochondrial response to unaccustomed RE, healthy young (21 ± 3 yr) and older (70 ± 4 yr) men performed a unilateral RE bout for the knee extensors. Muscle biopsies were taken at rest and 3, 24, and 48 h following leg press and knee extension exercise. The expression of the mitochondrial transcriptional regulator proliferator-activated receptor γ coactivator 1-α (PGC-1α) mRNA was increased at 3 h postexercise; however, all other mitochondrial variables decreased over the postexercise period, irrespective of age. ND1, ND4, and citrate synthase (CS) mRNA were all lower at 48 h postexercise, along with specific protein subunits of complex II, III, IV, and ATP synthase. Mitochondrial DNA (mtDNA) copy number decreased by 48 h postexercise, and mtDNA deletions were higher in the older adults and remained unaffected by acute exercise. Elevated mitophagy could not explain the reduction in mitochondrial proteins and DNA, because there was no increase in ubiquitinated voltage-dependent anion channel (VDAC) or its association with PTEN-induced putative kinase 1 (Pink1) or Parkin, and elevated p62 content indicated an impairment or reduction in autophagocytic flux. In conclusion, age did not influence the response of specific mitochondrial transcripts, proteins, and DNA to a bout of RE.


Assuntos
Envelhecimento/metabolismo , Mitocôndrias Musculares/metabolismo , Proteínas Mitocondriais/metabolismo , Músculo Esquelético/metabolismo , RNA Mensageiro/metabolismo , Treinamento Resistido , Adolescente , Fatores Etários , Idoso , Envelhecimento/genética , Envelhecimento/patologia , Autofagia , Biópsia , DNA Mitocondrial/metabolismo , Regulação da Expressão Gênica , Humanos , Masculino , Mitocôndrias Musculares/patologia , Proteínas Mitocondriais/genética , Músculo Esquelético/patologia , Fatores de Tempo , Transcrição Gênica , Adulto Jovem
8.
Age (Dordr) ; 36(4): 9699, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25108351

RESUMO

Skeletal muscle satellite cells (SCs) have been shown to be instrumental in the muscle adaptive response to exercise. The present study determines age-related differences in SC content and activation status following a single bout of exercise. Ten young (22 ± 1 years) and 10 elderly (73 ± 1 years) men performed a single bout of resistance-type exercise. Muscle biopsies were collected before and 12, 24, 48, and 72 h after exercise. SC content and activation status were assessed in type I and type II muscle fibers by immunohistochemistry. Myostatin and MyoD protein and messenger RNA (mRNA) expression were determined by Western blotting and rtPCR, respectively. In response to exercise, it took 48 h (young) and 72 h (elderly) for type II muscle fiber SC content to exceed baseline values (P < 0.01). The number of myostatin + SC in type I and II muscle fibers was significantly reduced after 12, 24, and 48 h of post-exercise recovery in both groups (P < 0.01), with a greater reduction observed at 24 and 48 h in the young compared with that in the elderly men (P < 0.01). In conclusion, the increase in type II muscle fiber SC content during post-exercise recovery is delayed with aging and is accompanied by a blunted SC activation response.


Assuntos
Envelhecimento/fisiologia , Tolerância ao Exercício/genética , Regulação da Expressão Gênica , Proteína MyoD/genética , Miostatina/genética , RNA Mensageiro/genética , Células Satélites de Músculo Esquelético/metabolismo , Idoso , Biópsia , Western Blotting , Seguimentos , Humanos , Imuno-Histoquímica , Masculino , Proteína MyoD/biossíntese , Miostatina/biossíntese , Reação em Cadeia da Polimerase em Tempo Real , Células Satélites de Músculo Esquelético/citologia , Adulto Jovem
9.
Am J Physiol Cell Physiol ; 304(8): C717-28, 2013 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-23392112

RESUMO

Aging is associated with increased circulating interleukin-6 (IL-6) and a reduced myogenic capacity, marked by reduced muscle stem cell [satellite cell (SC)] activity. Although IL-6 is important for normal SC function, it is unclear whether elevated IL-6 associated with aging alters SC function. We hypothesized that mild chronically elevated IL-6 would be associated with a blunted SC response through altered IL-6 signaling and elevated suppressor of cytokine signaling-3 (SOCS3) in the elderly. Nine healthy older adult men (OA; 69.6 ± 3.9 yr) and 9 young male controls (YC; 21. 3 ± 3.1 yr) completed 4 sets of 10 repetitions of unilateral leg press and knee extension (75% of 1-RM). Muscle biopsies and blood were obtained before and 3, 24, and 48 h after exercise. Basal SC number was 33% lower in OA vs. YC, and the response was blunted in OA. IL-6(+)/Pax7(+) cells demonstrated a divergent response in OA, with YC increasing to 69% at 3 h and peaking at 24 h (72%), while IL-6(+)/Pax7(+) cells were not increased until 48 h in OA (61%). Type II fiber-associated phosphorylated signal transducer and activator of transcription (pSTAT3)(+)/Pax7(+) cells demonstrated a similar delay in OA, not increasing until 48 h (vs. 3 h in YC). SOCS3 protein was 86% higher in OA. These data demonstrate an age-related impairment in normal SC function that appears to be influenced by SOCS3 protein and delayed induction of IL-6 and pSTAT3 in the SCs of OA. Collectively, these data suggest dysregulated IL-6 signaling as a consequence of aging contributes to the blunted muscle stem cell response.


Assuntos
Envelhecimento/metabolismo , Interleucina-6/fisiologia , Células Musculares/metabolismo , Transdução de Sinais/fisiologia , Células-Tronco/metabolismo , Proteínas Supressoras da Sinalização de Citocina/biossíntese , Adolescente , Idoso , Envelhecimento/patologia , Exercício Físico/fisiologia , Humanos , Interleucina-6/antagonistas & inibidores , Masculino , Células Musculares/patologia , Fibras Musculares Esqueléticas/metabolismo , Força Muscular/fisiologia , Células-Tronco/patologia , Proteína 3 Supressora da Sinalização de Citocinas , Adulto Jovem
10.
Med Sci Sports Exerc ; 45(2): 230-7, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22968308

RESUMO

INTRODUCTION: Satellite cells (SCs) are of key importance in skeletal muscle tissue growth, repair, and regeneration. A single bout of high-force eccentric exercise has been demonstrated to increase mixed muscle SC content after 1-7 d of postexercise recovery. However, little is known about fiber type-specific changes in SC content and their activation status within 24 h of postexercise recovery. METHODS: Nine recreationally active young men (23 ± 1 yr) performed 300 eccentric actions of the knee extensors on an isokinetic dynamometer. Skeletal muscle biopsies from the vastus lateralis were collected preexercise and 24 h postexercise. Muscle fiber type-specific SC content and the number of activated SCs were determined by immunohistochemical analyses. RESULTS: There was no difference between Type I and Type II muscle fiber SC content before exercise. SC content significantly increased 24 h postexercise in Type II muscle fibers (from 0.085 ± 0.012 to 0.133 ± 0.016 SCs per fiber, respectively; P < 0.05), whereas there was no change in Type I fibers. In accordance, activation status increased from preexercise to 24 h postexercise as demonstrated by the increase in the number of DLK1+ SCs in Type II muscle fibers (from 0.027 ± 0.008 to 0.070 ± 0.017 SCs per muscle fiber P < 0.05). Although no significant changes were observed in the number of Ki-67+ SCs, we did observe an increase in the number of proliferating cell nuclear antigen-positive SCs after 24 h of postexercise recovery. CONCLUSION: A single bout of high-force eccentric exercise increases muscle fiber SC content and activation status in Type II but not Type I muscle fibers.


Assuntos
Exercício Físico/fisiologia , Fibras Musculares de Contração Rápida/citologia , Células Satélites de Músculo Esquelético/citologia , Análise de Variância , Biópsia , Humanos , Imuno-Histoquímica , Masculino , Consumo de Oxigênio/fisiologia , Adulto Jovem
11.
PLoS One ; 6(3): e17392, 2011 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-21408055

RESUMO

BACKGROUND: Although the satellite cell (SC) is a key regulator of muscle growth during development and muscle adaptation following exercise, the regulation of human muscle SC function remains largely unexplored. STAT3 signalling mediated via interleukin-6 (IL-6) has recently come to the forefront as a potential regulator of SC proliferation. The early response of the SC population in human muscle to muscle-lengthening contractions (MLC) as mediated by STAT3 has not been studied. METHODOLOGY/PRINCIPAL FINDINGS: Twelve male subjects (21±2 y; 83±12 kg) performed 300 maximal MLC of the quadriceps femoris at 180°â€¢s(-1) over a 55° range of motion with muscle samples (vastus lateralis) and blood samples (antecubital vein) taken prior to exercise (PRE), 1 hour (T1), 3 hours (T3) and 24 hours (T24) post-exercise. Cytoplasmic and nuclear fractions of muscle biopsies were purified and analyzed for total and phosphorylated STAT3 (p-STAT3) by western blot. p-STAT3 was detected in cytoplasmic fractions across the time course peaking at T24 (p<0.01 vs. PRE). Nuclear total and p-STAT3 were not detected at appreciable levels. However, immunohistochemical analysis revealed a progressive increase in the proportion of SCs expressing p-STAT3 with ∼60% of all SCs positive for p-STAT3 at T24 (p<0.001 vs. PRE). Additionally, cMyc, a STAT3 downstream gene, was significantly up-regulated in SCs at T24 versus PRE (p<0.05). Whole muscle mRNA analysis revealed induction of the STAT3 target genes IL-6, SOCS3, cMyc (peaking at T3, p<0.05), IL-6Rα and GP130 (peaking at T24, p<0.05). In addition, Myf5 mRNA was up-regulated at T24 (p<0.05) with no appreciable change in MRF4 mRNA. CONCLUSIONS/SIGNIFICANT FINDINGS: We demonstrate that IL-6 induction of STAT3 signaling occurred exclusively in the nuclei of SCs in response to MLC. An increase in the number of cMyc+ SCs indicated that human SCs were induced to proliferate under the control of STAT3 signaling.


Assuntos
Interleucina-6/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Fator de Transcrição STAT3/metabolismo , Células Satélites de Músculo Esquelético/metabolismo , Células Satélites de Músculo Esquelético/patologia , Transdução de Sinais , Doença Aguda , Núcleo Celular/enzimologia , Proliferação de Células , Creatina Quinase/sangue , Exercício Físico , Humanos , Janus Quinase 2/metabolismo , Masculino , Fator de Transcrição PAX7/metabolismo , Transporte Proteico , Proteínas Proto-Oncogênicas c-myc/metabolismo , Fatores de Tempo , Adulto Jovem
12.
PLoS One ; 4(6): e6027, 2009 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-19554087

RESUMO

BACKGROUND: The regulation of muscle stem cells in humans in response to muscle injury remains largely undefined. Recently, interleukin-6 (IL-6) has been implicated in muscle stem cell (satellite cell)-mediated muscle hypertrophy in animals; however, the role of IL-6 in the satellite cell (SC) response following muscle-lengthening contractions in humans has not been studied. METHODOLOGY/PRINCIPAL FINDINGS: Eight subjects (age 22+/-1 y; 79+/-8 kg) performed 300 maximal unilateral lengthening contractions (3.14 rad.s(-1)) of the knee extensors. Blood and muscle samples were collected before and at 4, 24, 72, and 120 hours post intervention. IL-6, IL-6 receptor, IL-6R(alpha), cyclin D1, suppressor of cytokine signling-3 (SOCS3) mRNA were measured using quantitative RT-PCR and serum IL-6 protein was measured using an ELISA kit. JAK2 and STAT3 phosphorylated and total protein was measured using western blotting techniques. Immunohistochemical analysis of muscle cross-sections was performed for the quantification of SCs (Pax7(+) cells) as well as the expression of phosphorylated STAT3, IL-6, IL-6R(alpha), and PCNA across all time-points. The SC response, as defined by an amplification of Pax7(+) cells, was rapid, increasing by 24 h and peaking 72 h following the intervention. Muscle IL-6 mRNA increased following the intervention, which correlated strongly (R(2) = 0.89, p<0.002) with an increase in serum IL-6 concentration. SC IL-6R(alpha) protein was expressed on the fiber, but was also localized to the SC, and IL-6(+) SC increased rapidly following muscle-lengthening contractions and returned to basal levels by 72 h post-intervention, demonstrating an acute temporal expression of IL-6 with SC. Phosphorylated STAT3 was evident in SCs 4 h after lengthening contraction, and the downstream genes, cyclin D1 and SOCS3 were significantly elevated 24 hours after the intervention. CONCLUSIONS/SIGNIFICANCE: The increased expression of STAT3 responsive genes and expression of IL-6 within SCs demonstrate that IL-6/STAT3 signaling occurred in SCs, correlating with an increase in SC proliferation, evidenced by increased Pax7(+)/PCNA(+) cell number in the early stages of the time-course. Collectively, these data illustrate that IL-6 is an important signaling molecule associated with the SC response to acute muscle-lengthening contractions in humans.


Assuntos
Interleucina-6/metabolismo , Contração Muscular , Músculo Esquelético/fisiologia , Tamanho do Órgão/fisiologia , Células Satélites de Músculo Esquelético/citologia , Células Satélites de Músculo Esquelético/metabolismo , Transdução de Sinais , Humanos , Janus Quinase 2/metabolismo , Masculino , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/citologia , Fator de Transcrição STAT3/metabolismo , Adulto Jovem
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