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1.
Teach Learn Med ; 29(1): 13-24, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-27141957

RESUMEN

Phenomenon: Peer assisted learning (PAL) is frequently employed and researched in preclinical medical education. Fewer studies have examined PAL in the clinical context: These have focused mainly on the accuracy of peer assessment and potential benefits to learner communication and teamwork skills. Research has also examined the positive and negative effects of formal, structured PAL activities in the clinical setting. Given the prevalence of PAL activities during preclinical years, and the unstructured nature of clinical placements, it is likely that nonformal PAL activities are also undertaken. How PAL happens formally and informally and why students find PAL useful in this clinical setting remain poorly understood. APPROACH: This study aimed to describe PAL activities within the context of clinical placement learning and to explore students' perceptions of these activities. An ethnographic study was conducted to gather empirical data on engagement in clinical placement learning activities, including observations and interviews with students in their 1st clinical year, along with their supervising clinicians. Thematic analysis was used to interrogate the data. FINDINGS: On average, students used PAL for 5.19 hours per week in a range of activities, of a total of 29.29 hours undertaking placements. PAL was recognized as a means of vicarious learning and had greater perceived value when an educator was present to guide or moderate the learning. Trust between students was seen as a requirement for PAL to be effective. Students found passive observation a barrier to PAL and were able to identify ways to adopt an active stance when observing peers interacting with patients. For example, learners reported that the expectation that they had to provide feedback to peers after task observation, resulted in them taking on a more critical gaze where they were encouraged to consider notions of good practice. Insights: Students use PAL in formal (i.e., tutorial) and nonformal (e.g., peer observation and feedback on the ward; discussion during lunch) situations in clinical education and find it useful. The educator is crucial in fostering PAL through providing opportunities for learners to practice together and in helping to moderate discussions about quality of performance. Student engagement in PAL may reduce passivity commonly reported in clinical rotations. Further directions for research into PAL in clinical education are identified along with potential strategies that may maximize the benefits of peer to peer learning.


Asunto(s)
Aprendizaje , Grupo Paritario , Estudiantes de Medicina , Humanos , Entrevistas como Asunto , Investigación Cualitativa
2.
FASEB J ; 31(1): 161-171, 2017 01.
Artículo en Inglés | MEDLINE | ID: mdl-27682205

RESUMEN

Adipocytes are major regulators of metabolism, and endurance exercise training improves adipocyte function; however, the molecular mechanisms that regulate chronic adaptive responses remain unresolved. microRNAs (miRNAs) influence adipocyte differentiation and metabolism. Accordingly, we aimed to determine whether adipocyte miRNA expression is responsive to exercise training and to identify exercise-responsive miRNAs that influence adipocyte metabolism. Next-generation sequencing was used to profile miRNA expression of adipocytes that were isolated from abdominal subcutaneous (ABD) and gluteofemoral (GF) adipose tissue of overweight men before and after 6 wk of endurance exercise training. Differentially expressed miRNAs were overexpressed or silenced in 3T3-L1 adipocytes, and lipid metabolism was examined. Next-generation sequencing identified 526 miRNAs in adipocytes, and there were no statistical differences in miRNA expression when comparing pre- and post-training samples for ABD and GF adipocytes. miR-10b expression was increased in ABD compared with GF adipocytes, whereas miR-204, miR-3613, and miR-4532 were more highly expressed in GF compared with ABD adipocytes. Blocking miR-10b in adipocytes suppressed ß-adrenergic lipolysis but generally had a minor effect on lipid metabolism. Thus, unlike their critical role in adipogenesis, stable changes in miRNA expression do not play a prominent role in the regulation of adipocyte function in response to endurance exercise training.-Tsiloulis, T., Pike, J., Powell, D., Rossello, F. J., Canny, B. J., Meex, R. C. R., Watt, M. J. Impact of endurance exercise training on adipocyte microRNA expression in overweight men.


Asunto(s)
Adipocitos/fisiología , Ejercicio Físico/fisiología , Regulación de la Expresión Génica/fisiología , MicroARNs/metabolismo , Resistencia Física/fisiología , Células 3T3-L1 , Adulto , Animales , Técnicas de Silenciamiento del Gen , Humanos , Masculino , Ratones
3.
Teach Learn Med ; 29(2): 162-172, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-27997224

RESUMEN

Phenomenon: Peer learning has many benefits and can assist students in gaining the educational skills required in future years when they become teachers themselves. Peer learning may be particularly useful in clinical learning environments, where students report feeling marginalized, overwhelmed, and unsupported. Educational interventions often fail in the workplace environment, as they are often conceived in the "ideal" rather than the complex, messy real world. This work sought to explore barriers and facilitators to implementing peer learning activities in a clinical curriculum. APPROACH: Previous peer learning research results and a matrix of empirically derived peer learning activities were presented to local clinical education experts to generate discussion around the realities of implementing such activities. Potential barriers and limitations of and strategies for implementing peer learning in clinical education were the focus of the individual interviews. FINDINGS: Thematic analysis of the data identified three key considerations for real-world implementation of peer learning: culture, epistemic authority, and the primacy of patient-centered care. Strategies for peer learning implementation were also developed from themes within the data, focusing on developing a culture of safety in which peer learning could be undertaken, engaging both educators and students, and establishing expectations for the use of peer learning. Insights: This study identified considerations and strategies for the implementation of peer learning activities, which took into account both educator and student roles. Reported challenges were reflective of those identified within the literature. The resultant framework may aid others in anticipating implementation challenges. Further work is required to test the framework's application in other contexts and its effect on learner outcomes.


Asunto(s)
Educación de Pregrado en Medicina/métodos , Aprendizaje , Grupo Paritario , Aprendizaje Basado en Problemas , Estudiantes de Medicina , Femenino , Humanos , Masculino , Investigación Cualitativa
4.
Med Educ ; 50(6): 637-45, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27170082

RESUMEN

CONTEXT: There is ongoing debate regarding the optimal length of medical training, with concern about the cost of prolonged training. Two simultaneous tracks currently exist in Australia: direct entry from high school and graduate entry for students with a bachelor degree. Medical schools are switching to graduate entry based on maturity, academic preparedness and career-choice surety. We tested the assumption that graduate entry is better by exploring student preferences, coping, burnout, empathy and alcohol use. METHODS: From a potential pool of 2188 participants, enrolled at five Australian medical schools, a convenience sample of 688 (31%) first and second year students completed a survey in the middle of the academic year. Participants answered questions about demographics, satisfaction and coping and completed three validated instruments. RESULTS: Over 90% of students preferred their own entry-type, though more graduate-entry students were satisfied with their programme (82.4% versus 65.3%, p < 0.001). There was no difference between graduate-entry and direct-entry students in self-reported coping or in the proportion of students meeting criteria for burnout (50.7% versus 51.2%). Direct-entry students rated significantly higher for empathy (concern, p = 0.022; personal distress, p = 0.031). Graduate-entry students reported significantly more alcohol use and hazardous drinking (30.0% versus 22.8%; p = 0.017). CONCLUSIONS: Our multi-institution data confirm that students are generally satisfied with their choice of entry pathway and do not confirm significant psychosocial benefits of graduate entry. Overall, our data suggest that direct-entry students cope with the workload and psychosocial challenges of medical school, in the first 2 years, as well as graduate-entry students. Burnout and alcohol use should be addressed in both pathways. Despite studies showing similar academic outcomes, and higher total costs, more programmes in Australia are becoming graduate entry. Further research on non-cognitive issues and outcomes is needed so that universities, government funders and the medical profession can decide whether graduate entry, direct entry, or a mix, is ideal.


Asunto(s)
Adaptación Psicológica , Agotamiento Profesional/psicología , Educación de Pregrado en Medicina , Satisfacción Personal , Estudiantes de Medicina/psicología , Adulto , Consumo de Bebidas Alcohólicas/psicología , Femenino , Humanos , Masculino , Motivación , Nueva Gales del Sur , Facultades de Medicina , Victoria
5.
Adv Health Sci Educ Theory Pract ; 21(3): 659-76, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26662035

RESUMEN

This study explored the contribution of peer-assisted learning (PAL) in the development of evaluative judgement capacity; the ability to understand work quality and apply those standards to appraising performance. The study employed a mixed methods approach, collecting self-reported survey data, observations of, and reflective interviews with, the medical students observed. Participants were in their first year of clinical placements. Data were thematically analysed. Students indicated that PAL contributed to both the comprehension of notions of quality, and the practice of making comparisons between a given performance and the standards. Emergent themes included peer story-telling, direct observation of performance, and peer-based feedback, all of which helped students to define 'work quality'. By participating in PAL, students were required to make comparisons, therefore using the standards of practice and gaining a deeper understanding of them. The data revealed tensions in that peers were seen as less threatening than supervisors with the advantage of increasing learners' appetites for thoughtful 'intellectual risk taking'. Despite this reported advantage of peer engagement, learners still expressed a preference for feedback from senior teachers as more trusted sources of clinical knowledge. While this study suggests that PAL already contributes to the development of evaluative judgement, further steps could be taken to formalise PAL in clinical placements to improve learners' capacity to make accurate judgements on the performance of self and others. Further experimental studies are necessary to confirm the best methods of using PAL to develop evaluative judgement. This may include both students and educators as instigators of PAL in the workplace.


Asunto(s)
Educación Médica/métodos , Evaluación Educacional/métodos , Juicio , Grupo Paritario , Competencia Clínica/normas , Educación Médica/normas , Femenino , Retroalimentación Formativa , Humanos , Aprendizaje , Masculino , Estudiantes de Medicina/psicología
6.
BMC Med Educ ; 15: 210, 2015 Nov 26.
Artículo en Inglés | MEDLINE | ID: mdl-26611692

RESUMEN

BACKGROUND: Enhancing a medical school curriculum with new men's health teaching and learning requires an understanding of the local capacity and the facilitators and barriers to implementing new content, and an approach that accommodates the systemic and cultural differences between medical schools. METHODS: A formative evaluation was undertaken to determine the perspectives of key informants (academics, curriculum developers) from four Australian medical schools about the strategies needed to enhance their curriculum with men's health teaching and learning. Through semi-structured questioning with 17 key informants, interviewees also described the contextual barriers and facilitators to incorporating new topic areas into existing curriculum. Interviews were recorded with consent, transcribed verbatim, and analysed by two researchers to identify key themes. RESULTS: Interviewees were enthusiastic about incorporating men's health content through a men's health curriculum framework but highlighted the need for systems to assist in identifying gaps in their current curriculum where the men's health topics could be integrated. The student experience was identified as a key driver for men's health teaching and learning. Furthermore, core men's health clinical outcomes needed to be defined and topic areas vertically integrated across the curricula. This would ensure that students were appropriately equipped with the skills and knowledge for subsequent clinical practice in a range of geographical settings. Interviewees consistently suggested that the best implementation strategy is to have someone 'on the ground' to work directly with medical school staff and champion the men's health discipline. Providing mechanisms for sharing knowledge and resources across medical schools was highlighted to facilitate implementation, particularly for those medical schools with limited men's health teaching resources. CONCLUSIONS: Despite the unanimous support for men's health teaching and learning, the evaluation highlighted that the student experience must be recognised as paramount when integrating new topic areas into an already packed curriculum. A community of practice, where medical schools share relevant resources and knowledge, could help to ensure a commonality of student experience with respect to men's health learning in medical schools across different geographical settings and with different levels of resourcing. Such an approach could also be adapted to other areas of curriculum enhancement.


Asunto(s)
Curriculum , Educación de Pregrado en Medicina/organización & administración , Educación en Salud/organización & administración , Salud del Hombre , Australia , Femenino , Humanos , Aprendizaje/fisiología , Masculino , Evaluación de Programas y Proyectos de Salud , Investigación Cualitativa , Facultades de Medicina/organización & administración , Estudiantes de Medicina/estadística & datos numéricos , Enseñanza/métodos , Adulto Joven
7.
Perspect Med Educ ; 4(3): 110-8, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25962966

RESUMEN

An assessment framework provides a structured conceptual map of the learning outcomes of a programme of study along with details of how achievement of the outcomes can be measured. The rationale for using frameworks to underpin the targeting of essential content components is especially relevant for the medical education community. Frameworks have the capacity to improve validity and reliability in assessment, allowing test developers to more easily create robust assessment instruments. The framework used by the Australian Medical Assessment Collaboration (AMAC) is an interesting and relevant case study for the international community as it draws and builds on established processes in higher education assessment. The AMAC experience offers an insight into important considerations for designing assessment frameworks and implementing frameworks in differing contexts. There are lessons which have the potential to improve assessment and reporting practice and quality in not only medical education, but in other domains of assessment. Prior to implementing any programme of assessment, the framework considerations outlined here will hopefully improve the quality of assessment and reporting practice by making implicit assumptions explicit, and allowing more critical reflection and evaluation throughout assessment processes.

8.
PLoS One ; 9(7): e103062, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25054327

RESUMEN

Lipolysis involves the sequential breakdown of fatty acids from triacylglycerol and is increased during energy stress such as exercise. Adipose triglyceride lipase (ATGL) is a key regulator of skeletal muscle lipolysis and perilipin (PLIN) 5 is postulated to be an important regulator of ATGL action of muscle lipolysis. Hence, we hypothesized that non-genomic regulation such as cellular localization and the interaction of these key proteins modulate muscle lipolysis during exercise. PLIN5, ATGL and CGI-58 were highly (>60%) colocated with Oil Red O (ORO) stained lipid droplets. PLIN5 was significantly colocated with ATGL, mitochondria and CGI-58, indicating a close association between the key lipolytic effectors in resting skeletal muscle. The colocation of the lipolytic proteins, their independent association with ORO and the PLIN5/ORO colocation were not altered after 60 min of moderate intensity exercise. Further experiments in cultured human myocytes showed that PLIN5 colocation with ORO or mitochondria is unaffected by pharmacological activation of lipolytic pathways. Together, these data suggest that the major lipolytic proteins are highly expressed at the lipid droplet and colocate in resting skeletal muscle, that their localization and interactions appear to remain unchanged during prolonged exercise, and, accordingly, that other post-translational mechanisms are likely regulators of skeletal muscle lipolysis.


Asunto(s)
1-Acilglicerol-3-Fosfato O-Aciltransferasa/análisis , Ejercicio Físico/fisiología , Péptidos y Proteínas de Señalización Intracelular/análisis , Lipasa/análisis , Lipólisis , Proteínas Musculares/análisis , Músculo Esquelético/fisiología , Descanso/fisiología , 1-Acilglicerol-3-Fosfato O-Aciltransferasa/metabolismo , Adulto , Células Cultivadas , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Lipasa/metabolismo , Fibras Musculares Esqueléticas/química , Fibras Musculares Esqueléticas/fisiología , Fibras Musculares Esqueléticas/ultraestructura , Proteínas Musculares/metabolismo , Músculo Esquelético/ultraestructura , Perilipina-5 , Adulto Joven
9.
Med Teach ; 36(2): 139-47, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24171466

RESUMEN

BACKGROUND: The Australian Medical Assessment Collaboration (AMAC) began in 2010. This article charts the development of the collaboration over its initial years. AIMS: AMAC was instigated as a way of improving the quality of medical education through the recognition of the need for tools for comparison and evaluation of learning outcomes, acknowledgement of the need for high quality assessment, and to share expertise in these areas. In a climate of increasing regulation and accountability, this collaboration was formed as a means of increasing assessment practices by, with and for medical schools. METHOD: This article provides an overview of the background issues stimulating the development of AMAC, discussion of the formation of the collaboration and reflection on the lessons learnt through these processes. RESULTS: In a relatively short space of time, AMAC has fostered substantial collaboration among schools; developed an Assessment Framework, items and an online assessment; and provided benchmarking reports to students and schools. CONCLUSION: The intention here is to provide guidance for others (within the medical education community and those in other disciplines) with similar intentions and aims, by outlining the developmental pathway of the project and the systematic lessons that the collaboration team has learnt in establishing AMAC.


Asunto(s)
Benchmarking , Conducta Cooperativa , Evaluación de Resultado en la Atención de Salud/normas , Australia , Educación Médica , Humanos , Desarrollo de Programa
11.
PeerJ ; 1: e22, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23638357

RESUMEN

Working memory (WM) is often poorer for a second language (L2). In low noise conditions, people listening to a language other than their first language (L1) may have similar auditory perception skills for that L2 as native listeners, but do worse in high noise conditions, and this has been attributed to the poorer WM for L2. Given that WM is critical for academic success in children and young adults, these speech in noise effects have implications for academic performance where the language of instruction is L2 for a student. We used a well-established Speech-in-Noise task as a verbal WM (vWM) test, and developed a model correlating vWM and measures of English proficiency and/or usage to scholastic outcomes in a multi-faceted assessment medical education program. Significant differences in Speech-Noise Ratio (SNR50) values were observed between medical undergraduates who had learned English before or after five years of age, with the latter group doing worse in the ability to extract whole connected speech in the presence of background multi-talker babble (Student-t tests, p < 0.001). Significant negative correlations were observed between the SNR50 and seven of the nine variables of English usage, learning styles, stress, and musical abilities in a questionnaire administered to the students previously. The remaining two variables, Perceived Stress Scale (PSS) and the Age of Acquisition of English (AoAoE) were significantly positively correlated with the SNR50, showing that those with a poorer capacity to discriminate simple English sentences from noise had learnt English later in life and had higher levels of stress - all characteristics of the international students. Local students exhibited significantly lower SNR50 scores and were significantly younger when they first learnt English. No significant correlation was detected between the SNR50 and the students' Visual/Verbal Learning Style (r = -0.023). Standard multiple regression was carried out to assess the relationship between language proficiency and verbal working memory (SNR50) using 5 variables of L2 proficiency, with the results showing that the variance in SNR50 was significantly predicted by this model (r (2) = 0.335). Hierarchical multiple regression was then used to test the ability of three independent variable measures (SNR50, age of acquisition of English and English proficiency) to predict academic performance as the dependent variable in a factor analysis model which predicted significant performance differences in an assessment requiring communications skills (p = 0.008), but not on a companion assessment requiring knowledge of procedural skills, or other assessments requiring factual knowledge. Thus, impaired vWM for an L2 appears to affect specific communications-based assessments in university medical students.

12.
Am J Physiol Endocrinol Metab ; 303(4): E534-41, 2012 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-22713505

RESUMEN

Intramyocellular triacylglycerol provides fatty acid substrate for ATP generation in contracting muscle. The protein adipose triglyceride lipase (ATGL) is a key regulator of triacylglycerol lipolysis and whole body energy metabolism at rest and during exercise, and ATGL activity is reported to be enhanced by 5'-AMP-activated protein kinase (AMPK)-mediated phosphorylation at Ser(406) in mice. This is a curious observation, because AMPK activation reduces lipolysis in several cell types. We investigated whether the phosphorylation of ATGL Ser(404) (corresponding to murine Ser(406)) was increased during exercise in human skeletal muscle and with pharmacological AMPK activation in myotubes in vitro. In human experiments, skeletal muscle and venous blood samples were obtained from recreationally active male subjects before and at 5 and 60 min during exercise. ATGL Ser(404) phosphorylation was not increased from rest during exercise, but ATGL Ser(404) phosphorylation correlated with myosin heavy chain 1 expression, suggesting a possible fiber type dependency. ATGL Ser(404) phosphorylation was not related to increases in AMPK activity, and immunoprecipitation experiments indicated no interaction between AMPK and ATGL. Rather, ATGL Ser(404) phosphorylation was associated with protein kinase A (PKA) signaling. ATGL Ser(406) phosphorylation in C(2)C(12) myotubes was unaffected by 5-aminoimidazole-4-carboxaminde-1-ß-d-ribofuranoside, an AMPK activator, and the PKA activator forskolin. Our results demonstrate that ATGL Ser(404) phosphorylation is not increased in mixed skeletal muscle during moderate-intensity exercise and that AMPK does not appear to be an activating kinase for ATGL Ser(404/406) in skeletal muscle.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Tejido Adiposo/enzimología , Ejercicio Físico/fisiología , Lipasa/metabolismo , Serina/metabolismo , Tejido Adiposo/efectos de los fármacos , Adulto , Aminoimidazol Carboxamida/farmacología , Glucemia/metabolismo , Células Cultivadas , Colforsina/farmacología , Metabolismo Energético/efectos de los fármacos , Metabolismo Energético/fisiología , Ácidos Grasos no Esterificados/sangre , Humanos , Ácido Láctico/sangre , Masculino , Músculo Esquelético/metabolismo , Consumo de Oxígeno/efectos de los fármacos , Consumo de Oxígeno/fisiología , Fosforilación , Adulto Joven
13.
PLoS One ; 7(12): e53080, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23285255

RESUMEN

Reduced activation of exercise responsive signalling pathways have been reported in response to acute exercise after training; however little is known about the adaptive responses of the mitochondria. Accordingly, we investigated changes in mitochondrial gene expression and protein abundance in response to the same acute exercise before and after 10-d of intensive cycle training. Nine untrained, healthy participants (mean±SD; VO(2peak) 44.1±17.6 ml/kg/min) performed a 60 min bout of cycling exercise at 164±18 W (72% of pre-training VO(2peak)). Muscle biopsies were obtained from the vastus lateralis muscle at rest, immediately and 3 h after exercise. The participants then underwent 10-d of cycle training which included four high-intensity interval training sessions (6×5 min; 90-100% VO(2peak)) and six prolonged moderate-intensity sessions (45-90 min; 75% VO(2peak)). Participants repeated the pre-training exercise trial at the same absolute work load (64% of pre-training VO(2peak)). Muscle PGC1-α mRNA expression was attenuated as it increased by 11- and 4- fold (P<0.001) after exercise pre- and post-training, respectively. PGC1-α protein expression increased 1.5 fold (P<0.05) in response to exercise pre-training with no further increases after the post-training exercise bout. RIP140 protein abundance was responsive to acute exercise only (P<0.01). COXIV mRNA (1.6 fold; P<0.01) and COXIV protein expression (1.5 fold; P<0.05) were increased by training but COXIV protein expression was decreased (20%; P<0.01) by acute exercise pre- and post-training. These findings demonstrate that short-term intensified training promotes increased mitochondrial gene expression and protein abundance. Furthermore, acute indicators of exercise-induced mitochondrial adaptation appear to be blunted in response to exercise at the same absolute intensity following short-term training.


Asunto(s)
Ciclismo/fisiología , Complejo IV de Transporte de Electrones/genética , Ejercicio Físico/fisiología , Proteínas de Choque Térmico/genética , Músculo Esquelético/metabolismo , Educación y Entrenamiento Físico/métodos , Factores de Transcripción/genética , Adolescente , Adulto , Complejo IV de Transporte de Electrones/metabolismo , Regulación de la Expresión Génica , Proteínas de Choque Térmico/metabolismo , Humanos , Masculino , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Esfuerzo Físico/fisiología , Recuperación de la Función/genética , Recuperación de la Función/fisiología , Factores de Tiempo , Factores de Transcripción/metabolismo , Adulto Joven
16.
Am J Physiol Regul Integr Comp Physiol ; 300(2): R511-8, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21148475

RESUMEN

In sheep, central leptin infusion reduces food intake and increases energy expenditure in adipose tissue and skeletal muscle. The mechanisms for these peripheral effects of central leptin in sheep are not known but, on the basis of rodent studies, may involve AMPK. In mice, central leptin acutely increases both skeletal muscle AMPK activation and glucose uptake. Thus, to investigate whether these effects exist in higher-order mammals, ovariectomized Corriedale ewes (n = 4 per group) received a continuous lateral ventricular infusion (60 µl/h) of either leptin (50 µg/h) or artificial cerebrospinal fluid (aCSF; CON) for 8 days. Tritiated glucose (3-(3)H-glucose) was infused intravenously for calculation of whole body glucose turnover during both acute (6 h) and chronic (7-8 days) leptin/aCSF infusion. Muscle biopsies were also obtained. Leptin infusion reduced (P < 0.05) food intake and body weight, and it also increased plasma epinephrine concentration at 6 h and 7 days, suggesting increased sympathetic nerve activity. Despite this, and in contrast to rodent studies, central leptin infusion did not increase skeletal muscle AMPKα Thr(172) phosphorylation or ACCß Ser(221) phosphorylation. Surprisingly, the glucose rate of appearance (glucose Ra) and rate of disappearance (glucose Rd) were reduced by both acute and chronic leptin infusion. Direct infusion of the AMPK activator 5-aminoimidazole-4-carboxyamide-ribonucleoside (AICAR) into the femoral artery increased skeletal muscle AMPK phosphorylation. In conclusion, although central leptin infusion in sheep caused the predicted reduction in food intake and increases plasma epinephrine concentration, it had no effect on AMPK activation in skeletal muscle and actually reduced glucose disposal. This suggests that there are species differences in the peripheral responses to central leptin infusion.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Leptina/farmacología , Músculo Esquelético/metabolismo , Ovinos/fisiología , Transducción de Señal/efectos de los fármacos , Acetil-CoA Carboxilasa/metabolismo , Aminoimidazol Carboxamida/administración & dosificación , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacología , Estructuras Animales/metabolismo , Animales , Glucemia/efectos de los fármacos , Glucemia/metabolismo , Peso Corporal/efectos de los fármacos , Catecolaminas/sangre , Ingestión de Alimentos/efectos de los fármacos , Ácidos Grasos no Esterificados/sangre , Femenino , Glicerol/sangre , Glucógeno/metabolismo , Hormona del Crecimiento/sangre , Hidrocortisona/sangre , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/farmacocinética , Infusiones Intraarteriales , Infusiones Intraventriculares , Insulina/sangre , Leptina/administración & dosificación , Hígado/efectos de los fármacos , Hígado/metabolismo , Músculo Esquelético/efectos de los fármacos , Ovariectomía , Fosforilación/efectos de los fármacos , Subunidades de Proteína/metabolismo , Ribonucleótidos/administración & dosificación , Ribonucleótidos/farmacología , Transducción de Señal/fisiología , Grasa Subcutánea/efectos de los fármacos , Grasa Subcutánea/metabolismo
18.
J Appl Physiol (1985) ; 107(1): 283-9, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19359609

RESUMEN

AMP-activated protein kinase (AMPK) has been extensively studied in whole muscle biopsy samples of humans, yet the fiber type-specific expression and/or activation of AMPK is unknown. We examined basal and exercise AMPK-alpha Thr(172) phosphorylation and AMPK subunit expression (alpha(1), alpha(2), and gamma(3)) in type I, IIa, and IIx fibers of human skeletal muscle before and after 10 days of exercise training. Before training basal AMPK phosphorylation was greatest in type IIa fibers (P < 0.05 vs. type I and IIx), while an acute bout of exercise increased AMPK phosphorylation in all fibers (P < 0.05), with the greatest increase occurring in type IIx fibers. Exercise training significantly increased basal AMPK phosphorylation in all fibers, and the exercise-induced increases were uniformly suppressed compared with pretraining exercise. Expression of AMPK-alpha(1) and -alpha(2) was similar between fibers and was not altered by exercise training. However, AMPK-gamma(3) was differentially expressed in skeletal muscle fibers (type IIx > type IIa > type I), irrespective of training status. Thus skeletal muscle AMPK phosphorylation and AMPK expression are fiber type specific in humans in the basal state, as well as during exercise. Our findings reveal fiber type-specific differences that have been masked in previous studies examining mixed muscle samples.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Ejercicio Físico/fisiología , Fibras Musculares Esqueléticas/enzimología , Aptitud Física/fisiología , Proteínas Quinasas Activadas por AMP/biosíntesis , Biomarcadores/metabolismo , Humanos , Inmunohistoquímica , Masculino , Fibras Musculares Esqueléticas/química , Fibras Musculares Esqueléticas/clasificación , Consumo de Oxígeno , Fosforilación , Adulto Joven
19.
Med Sci Sports Exerc ; 41(3): 546-65, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19204596

RESUMEN

PURPOSE: We used gene microarray analysis to compare the global expression profile of genes involved in adaptation to training in skeletal muscle from chronically strength-trained (ST), endurance-trained (ET), and untrained control subjects (Con). METHODS: Resting skeletal muscle samples were obtained from the vastus lateralis of 20 subjects (Con n = 7, ET n = 7, ST n = 6; trained [TR] groups >8 yr specific training). Total RNA was extracted from tissue for two color microarray analysis and quantative (Q)-PCR. Trained subjects were characterized by performance measures of peak oxygen uptake (V x O 2peak) on a cycle ergometer and maximal concentric and eccentric leg strength on an isokinetic dynamometer. RESULTS: Two hundred and sixty-three genes were differentially expressed in trained subjects (ET + ST) compared with Con (P < 0.05), whereas 21 genes were different between ST and ET (P < 0.05). These results were validated by reverse transcriptase polymerase chain reaction for six differentially regulated genes (EIFSJ, LDHB, LMO4, MDH1, SLC16A7, and UTRN. Manual cluster analyses revealed significant regulation of genes involved in muscle structure and development in TR subjects compared with Con (P

Asunto(s)
Perfilación de la Expresión Génica , Músculo Esquelético/metabolismo , Resistencia Física , Entrenamiento de Fuerza , Adaptación Fisiológica , Adulto , Biopsia , Estudios de Casos y Controles , Prueba de Esfuerzo , Humanos , Masculino , Proteínas Mitocondriales/metabolismo , Dinamómetro de Fuerza Muscular , Músculo Esquelético/patología , Análisis de Secuencia por Matrices de Oligonucleótidos , Consumo de Oxígeno , Aptitud Física , Reacción en Cadena de la Polimerasa , ARN Mensajero/metabolismo , Deportes , Regulación hacia Arriba
20.
Am J Physiol Endocrinol Metab ; 295(6): E1427-38, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18827172

RESUMEN

Endurance training represents one extreme in the continuum of skeletal muscle plasticity. The molecular signals elicited in response to acute and chronic exercise and the integration of multiple intracellular pathways are incompletely understood. We determined the effect of 10 days of intensified cycle training on signal transduction in nine inactive males in response to a 1-h acute bout of cycling at the same absolute workload (164 +/- 9 W). Muscle biopsies were taken at rest and immediately and 3 h after the acute exercise. The metabolic signaling pathways, including AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR), demonstrated divergent regulation by exercise after training. AMPK phosphorylation increased in response to exercise ( approximately 16-fold; P < 0.05), which was abrogated posttraining (P < 0.01). In contrast, mTOR phosphorylation increased in response to exercise ( approximately 2-fold; P < 0.01), which was augmented posttraining (P < 0.01) in the presence of increased mTOR expression (P < 0.05). Exercise elicited divergent effects on mitogen-activated protein kinase (MAPK) pathways after training, with exercise-induced extracellular signal-regulated kinase (ERK) 1/2 phosphorylation being abolished (P < 0.01) and p38 MAPK maintained. Finally, calmodulin kinase II (CaMKII) exercise-induced phosphorylation and activity were maintained (P < 0.01), despite increased expression ( approximately 2-fold; P < 0.05). In conclusion, 10 days of intensified endurance training attenuated AMPK, ERK1/2, and mTOR, but not CaMKII and p38 MAPK signaling, highlighting molecular pathways important for rapid functional adaptations and maintenance in response to intensified endurance exercise and training.


Asunto(s)
Ejercicio Físico/fisiología , Músculo Esquelético/fisiología , Transducción de Señal/fisiología , Proteínas Quinasas Activadas por AMP/metabolismo , Adulto , Humanos , Masculino , Redes y Vías Metabólicas/fisiología , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Modelos Biológicos , Músculo Esquelético/metabolismo , Resistencia Física/fisiología , Proteínas Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Serina-Treonina Quinasas TOR , Factores de Tiempo , Adulto Joven
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