Beta-hydroxy-beta-methylbutyrate associated with low-intensity exercise training improves skeletal muscle regeneration through the IGF-Akt pathway

The effect of beta-hydroxy-beta-methylbutyrate (HMB) supplementation associated with exercise training at different intensities and frequencies on skeletal muscle regeneration of muscle-injured rats was investigated. Male Wistar rats were divided into sedentary and trained groups. The sedentary groups were subdivided into non-injured (SED-Ct), non-injured supplemented with HMB (SED-Ct-HMB), injured (SED), and injured with HMB (SED-HMB), and the trained groups were injured, supplemented with HMB, and then divided into training three times a week without load (HT3) or with load (HT3L) and training five times a week without load (HT5) and with load (HT5L). The rats received a daily dose of HMB associated with 60 min of swimming with or without 5% body mass load for 14 days. On the 15th day, cryoinjury was performed in the right tibialis anterior muscle (TA), and 48 h later, supplementation and training continued for 15 days. After the last session, the TA was dissected and a cross-sectional area (CSA) of muscle fibers was used to determine the percentage of CSA fibers and connective tissue (%CT), as well as the total and phosphorylated protein contents. SED-HMB showed increased CSA and decreased %CT and TGF-β when compared to SED. HT3 showed increased CSA and reduced %CT accompanied by increased IGF-1/Akt, myogenin, and MuRF1, and decreased TGF-β. The CSA of HT5L also increased, but at the cost of a higher %CT compared to the other groups. Our results demonstrated that HMB associated with training without load and with lower frequency per week may be a valuable strategy for skeletal muscle regeneration.

Conocimientos, actitudes y motivaciones respecto a la afiliación al colegio de enfermeras en docentes universitarios / Knowledge, attitudes, and motivations among university teachers regarding the affiliation to a Chilean College of Nurses / Conhecimentos, atitudes e motivações ao respeito da filiação ao colégio de enfermeiras em docentes universitários

Resumen Introducción: La participación en el colegio de enfermeras es una instancia relevante para el desarrollo de la profesión a nivel país, debido a la defensa que realiza por la enfermería desde los diferentes ámbitos de actuación; es indispensable inculcar esta visión desde la formación universitaria a través de los profesionales de enfermería que se dedican a la docencia. Materiales y métodos: Se realizó un estudio cuantitativo, transeccional y correlacional, en 49 académicos de las diferentes casas de estudio de la ciudad de Puerto Montt-Chile, en quienes se evaluó su afiliación al colegio de enfermeras, además de sus conocimientos, actitudes y motivaciones respecto a participar en dicha instancia gremial; para tal fin se aplicó un instrumento de elaboración propia (α Cronbach 0.71). Resultados: Se encontró que el 40.9% de los docentes está afiliado al colegio de enfermeras y que existe conocimiento suficiente respecto a esta organización, con una actitud desfavorable hacia el mismo, evidenciándose asociación entre la actitud y aspectos como la dinámica de trabajo (p=0.043 Correlación de Spearman: 0.158) y la afiliación al colegio (p=0.02 Coeficiente de Spearman: 0.142). Discusión: La participación colegiada permite el fortalecimiento de la profesión, además de favorecer la visibilidad, liderazgo e identidad profesional; aunque se reconocen estos aspectos no son suficientes para generar la afiliación o una actitud favorable a ésta. Conclusiones: En la promoción de la afiliación debe considerarse la tendencia a no afiliación de los docentes más jóvenes y los aspectos de motivación, ambos relevantes para destacar la participación colegial como un aspecto deontológico que forma parte del modelaje hacia los enfermeros en formación.

Abstract Introduction: The participation with the College of Nurses is a relevant action to support the development of nursing in Chile because this organization stands as an important defender to the practice. Therefore, it is advisable that nursing teachers promote this vision among the nursing community. Materials and Methods: This is a quantitative, transectional and correlational study with 49 academicians from diverse teaching centers in the city of Puerto Montt, Chile, who were assessed in terms of their affiliation to the College of Nurses, their knowledge, attitudes, and motivations regarding their participation with this organization. A locally-designed instrument (α Cronbach 0.71) was used. Results: 40.9% of the teachers were affiliated to the College of Nurses. Associations between attitudes and working dynamics (Spearman Correlation = 0.158, p =0.043), and affiliation to the College (Spearman Correlation = 0.142, p = 0.02) were found. Discussion: The participation with the College of Nurses can allow the strengthening of the profession by favoring its visibility, leadership, and professional identity, though these important gains are not always sufficient to encourage an affiliation or a positive attitude towards this organization. Conclusions: In order to better promote the affiliation to the College of Nurses, young teachers' indifference attitudes, as well as other overall motivation factors should be considered first.

Resumo Introdução: A participação no colégio de enfermeiras é uma instancia relevante para o desenvolvimento da profissão ao nível do país, devido à defesa que realiza pela enfermagem desde os diferentes âmbitos de atuação; é indispensável inculcar esta visão desde a formação universitária a través dos profissionais de enfermagem que se dedicam à docência. Materiais e métodos: Realizou-se um estudo quantitativo, transecional e correlacional, em 49 docentes das diferentes casas de estudo da cidade de Puerto Montt-Chile, em quem se avaliou sua filiação ao colégio de enfermeiras, além de seus conhecimentos, atitudes e motivações referentes a participar na instância gremial; para tal fim aplicou-se um instrumento de elaboração própria (α Cronbach 0.71). Resultados: Encontrou-se que o 40.9% dos docentes forma parte do colégio de enfermeiras e que existe conhecimento suficiente ao respeito desta organização, com uma atitude desfavorável a ele mesmo, evidenciando-se uma associação entre a atitude e aspectos como a dinâmica de trabalho (p=0.043 Correlação de Spearman: 0.158) e a filiação ao colégio (p=0.02 Coeficiente de Spearman: 0.142). Discussão: A participação colegiada permite o fortalecimento da profissão, além de favorecer a visibilidade, liderança e identidade profissional; ainda que se reconheçam estes aspectos, não são suficientes para gerar a filiação ou uma atitude favorável a esta. Conclusões: Na promoção da filiação deve considerar-se a tendência à não filiação dos docentes mais jovens e os aspectos de motivação, ambos relevantes para salientar a participação colegial como um aspecto deontológico que forma parte da modelagem aos enfermeiros em formação.

Effect of melatonin on the functional recovery from experimental traumatic compression of the spinal cord

Spinal cord injury is an extremely severe condition with no available effective therapies. We examined the effect of melatonin on traumatic compression of the spinal cord. Sixty male adult Wistar rats were divided into three groups: sham-operated animals and animals with 35 and 50% spinal cord compression with a polycarbonate rod spacer. Each group was divided into two subgroups, each receiving an injection of vehicle or melatonin (2.5 mg/kg, intraperitoneal) 5 min prior to and 1, 2, 3, and 4 h after injury. Functional recovery was monitored weekly by the open-field test, the Basso, Beattie and Bresnahan locomotor scale and the inclined plane test. Histological changes of the spinal cord were examined 35 days after injury. Motor scores were progressively lower as spacer size increased according to the motor scale and inclined plane test evaluation at all times of assessment. The results of the two tests were correlated. The open-field test presented similar results with a less pronounced difference between the 35 and 50% compression groups. The injured groups presented functional recovery that was more evident in the first and second weeks. Animals receiving melatonin treatment presented more pronounced functional recovery than vehicle-treated animals as measured by the motor scale or inclined plane. NADPH-d histochemistry revealed integrity of the spinal cord thoracic segment in sham-operated animals and confirmed the severity of the lesion after spinal cord narrowing. The results obtained after experimental compression of the spinal cord support the hypothesis that melatonin may be considered for use in clinical practice because of its protective effect on the secondary wave of neuronal death following the primary wave after spinal cord injury.

Comportamento das reservas de glicogênio no músculo desnervado de ratas tratadas com diferentes doses de estrógeno / Glycogen reserve behavior in denervated muscles of female rats treated with different estrogen doses

OBJETIVO: Avaliar a ação estrogênica sobre o perfil glicogênico do músculo esquelético desnervado de ratas. MÉTODOS: Os animais foram divididos em seis grupos experimentais (n=6): controle; desnervado durante 15 dias; desnervado tratado com estrógeno na concentração de 20µg/peso/dia; desnervado tratado com estrógeno na concentração de 40µg/peso/dia; desnervado tratado com estrógeno na concentração de 80µg/peso/dia e desnervado tratado com estrógeno na concentração de 160µg/peso/dia. Os animais foram tratados com a substância cipionato de estradiol durante 15 dias. As análises realizadas foram: conteúdo de glicogênio dos músculos sóleo, gastrocnêmio branco e gastrocnêmio vermelho (misto), realizadas por meio do método do fenol sulfúrico, além do peso corporal e do músculo sóleo. A análise estatística incluiu ANOVA e teste post-hoc de Tukey (p<0,05). RESULTADOS: A desnervação promoveu redução no conteúdo de glicogênio dos músculos sóleo, gastrocnêmio branco e misto. Por outro lado, nos grupos tratados com estrógeno, foi observada uma elevação progressiva no conteúdo de glicogênio concomitante com a elevação da dose, restabelecendo as reservas glicogênicas, sendo que a concentração mais efetiva foi a de 160µg/peso/dia, em que foram observadas as melhores respostas químio-metabólicas e a menor perda de peso. CONCLUSÃO: Esses resultados sugerem que o estrógeno na concentração de 160µg/peso/dia foi a mais eficiente para minimizar o comprometimento metabólico e pode ser um importante instrumento farmacológico aplicado na prática fisioterapêutica durante a reabilitação.

OBJECTIVE: To evaluate the action of estrogen on the glycogen profile of denervated skeletal muscle in female rats. METHODS: The animals were divided into six experimental groups (n=6): control; denervated for 15 days; denervated and treated with estrogen at a concentration of 20µg/weight/day; denervated and treated with estrogen at a concentration of 40µg/weight/day; denervated and treated with estrogen at a concentration of 80µg/weight/day; and denervated and treated with estrogen at a concentration of 160µg/weight/day. The animals were treated with estradiol cypionate for 15 days. The following analyses were carried out: glycogen content of the soleus, white gastrocnemius and red (mixed) gastrocnemius, by means of the phenol-sulfuric acid method as well as body weight and soleus muscle weight. The statistical analysis included ANOVA and the post-hoc Tukey test (p<0.05). RESULTS: The denervation induced a reduction in glycogen content in the soleus and the white and mixed gastrocnemius muscles. In contrast, there was a progressive elevation of glycogen content concomitant with dose elevation in the groups treated with estrogen, thereby reinstating the glycogen reserves. The most effective concentration was 160µg/weight/day, which showed the best chemometabolic responses and least weight loss. CONCLUSION: These results suggest that estrogen at the concentration of 160 µg/weight/day was the most efficient at minimizing metabolic impairment and that it may be an important pharmacological instrument for physical therapy practice during rehabilitation.