Determinação do limiar anaeróbio por meio de biomarcadores salivares: cromogranina A como novo marcador de intensidade em natação

CHAPTER 2: This study examined intra-individual variations in salivary lactate (sLac), alpha-amylase (sAA) and chromogranin A (sCgA) with reference to the accumulation of blood lactate (bLac) during progressive maximal exercise in swimmers. Samples of blood and saliva were collected simultaneously from 12 professional athletes during an incremental test that consisted of eight series of 100 m in front crawl with increasing velocity (0.03 m x s-1 each) and 70-sec intervals. The concentration of blood and salivary lactate was determined by an electro-enzymatic assay whereas sAA and CgA were analyzed by western blotting. Inflection point in the concentration of bLAc, sLac, sAA and CgA were found in all subjects. The accumulation of lactate in saliva followed the same pattern observed in blood with a high correlation between the two (r = 0.92). Similar results were observed between the dynamics of sAA (r = 0.81) and sCgA (r = 0.82) when compared to bLac. These findings support the usefulness of saliva for the determination of the anaerobic threshold and provide the first demonstration of sCgA as a novel marker of exercise intensity in well-trained men.Mestre em Genética e BioquímicaCAPITULO 2: Este estudo investigou a variação intra-individual do lactato (sLac), alfa-amilase (sAA) e cromogranina A (sCgA) salivares com relação ao acúmulo de lactato sanguíneo (bLac) durante um teste de exercício incremental máximo em natação. Amostras de sangue e saliva foram coletadas de doze atletas profissionais da natação durante um teste de esforço que consistiu de oito séries de 100 metros com incremento de velocidade a cada série no estilo crawl. A concentração de lactato no sangue e na saliva foi determinada por meio de um ensaio eletro-enzimático enquanto que as concentrações de sAA e sCgA foram determinadas por Western blotting. O acúmulo de lactato na saliva apresentou uma dinâmica similar à observda no sangue (r=0.92). Resultados similares foram encontrados para as concentrações de sAA (r=0.81) e sCgA (r=0.82) quando comparadas ao bLac. Estes resultados corroboram a utilidade da saliva para a determinação do limiar anaeróbio e fornecem a primeira demostração de que sCgA pode ser utilizada como um marcador de intensidade do exercício em sujeitos altamente treinados

El VAR en la administración del riesgo

El riesgo se lentifica como la oportunidad de ocurrencia de un evento desfavorable. Corresponde igualmente la volatilidad de los flujos financieros no esperados, generalmente derivados del valor de los activos o los pasivos. Las empresas están expuestas a diferentes tipos de riesgos: de negocios, estratégicos y financieros.Riesgo. Una nueva función: la administración de riesgos. Importancia de la administración del riesgo frente a desastres financieros. VAR definición y usos. Conceptos claves para entender el cálculo de VAR. Metodologías de medición del VAR. Modelo de Var-método de covarianza. Proceso de implantación de un modelo de VAR.Especialista en finanzas corporativasEspecializaciónEMM

Representative blots of sAA and sCgA in response to training.

<p>Representative blots of sAA and sCgA in response to training.</p

Plasma catecholamines and salivary proteins.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064043#pone-0064043-g002" target="_blank">Figure 2A</a> shows the variation in adrenaline and noradrenaline in response to training. Adrenaline: • Different from Training week 16. *Different from Training Week 21. Noradrenaline: δ Different from Training Week 11. σ Different from Training Week 21. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064043#pone-0064043-g002" target="_blank">Figure 2B</a> shows the variation in dopamine. *Different from Training Week 16. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064043#pone-0064043-g002" target="_blank">Figure 2C</a> shows the response of sAA activity vs. concentration. sAA activity: *Different from Training Week 11. sAA concentration: • Different from Training Week 21. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064043#pone-0064043-g002" target="_blank">Figure 2D</a> shows the variation in sCgA and sTP in response to training. sTP: *Different from Training Week 11. sCgA: • Different from training week 6. δ Different from training week 11. σ Different from Training Week 16.</p

Heart rate and blood pressure throughout the 21-week training season.

<p>Values are Means (SD).</p

Pearson correlation coefficients between the biochemical markers and the training outcomes at p≤0.05.

<p>sAA = salivary alpha-amylase (activity); [sAA] = salivary alpha-amylase (concentration); Adr = adrenaline; Nor = noradrenaline; Dop = dopamine.</p

Daily dietary intake for the subjects during the 48 hours prior to each collection of the samples.

<p>Values are means (SD).</p

Plasma and salivary nitrite.

<p>*Different from Training Week 21 (pNO₂).</p

Salivary flow.

<p>No difference in salivary flow was observed throughout the training season.</p

Chronic stress induces a hyporeactivity of the autonomic nervous system in response to acute mental stressor and impairs cognitive performance in business executives

The present study examined the incidence of chronic stress in business executives (109 subjects: 75 male and 34 female) and its relationship with cortisol levels, cognitive performance, and autonomic nervous system (ANS) reactivity after an acute mental stressor. Blood samples were collected from the subjects to measure cortisol concentration. After the sample collection, the subjects completed the Lipp Inventory of Stress Symptoms for Adults and the Stroop Color-Word Test to evaluate stress and cognitive performance levels, respectively. Saliva samples were collected prior to, immediately after, and five minutes after the test. The results revealed that 90.1% of the stressed subjects experienced stress phases that are considered chronic stress. At rest, the subjects with chronic stress showed higher cortisol levels, and no gender differences were observed. No differences were found between the stressed and non-stressed subjects regarding salivary amylase activity prior to test. Chronic stress also impaired performance on the Stroop test, which revealed higher rates of error and longer reaction times in the incongruent stimulus task independently of gender. For the congruent stimulus task of the Stroop test, the stressed males presented a higher rate of errors than the non-stressed males and a longer reaction time than the stressed females. After the acute mental stressor, the non-stressed male group showed an increase in salivary alpha-amylase activity, which returned to the initial values five minutes after the test; this ANS reactivity was not observed in the chronically stressed male subjects. The ANS responses of the non-stressed vs stressed female groups were not different prior to or after the Stroop test. This study is the first to demonstrate a blunted reactivity of the ANS when male subjects with chronic psychological stress were subjected to an acute mental stressor, and this change could contribute to impairments in cognitive performance.Funding: This study was supported by grants from the funding agency FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais - grant nº. APQ 01347/08). TVSS, MMD, and OLB received graduate fellowships from CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.</p