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ABSTRACT: There is growing awareness that vitamin D sufficiency is required for overall optimal health. Most experts agree that 25-hydroxyvitamin D levels of at least 75 nmol/L, as sufficient vitamin D status. Our aim was to investigate the serum 25-hydroxyvitamin D concentration required in mid-October to ensure vitamin D sufficiency in early February, and to assess the rate of vitamin D insufficiency in both seasons.
We measured serum 25-hydroxyvitamin D, parathormone, and other related biochemical parameters, in a sample of 28 professional football players homogeneous in factors influencing serum 25-hydroxyvitamin D concentration in a sunny area of southern Spain.
The serum 25-hydroxyvitamin D concentration of 122.7 nmol/L was required; 14.3% reached this level. Ninety-three percent had levels ≥75 nmol/L in mid-October, and 64% had levels <75 nmol/l in early February (χ(2) test, ρ = 0.001).
Despite the homogeneity in sunlight exposure and vitamin D intake few football players reached the level ensuring vitamin D sufficiency in mid-winter, and two thirds had vitamin D insufficiency in early February. Given our findings, it would be advisable to assess the vitamin D levels in early autumn, although additional studies are necessary.
Clinical nutrition (Edinburgh, Scotland) 08/2011; 31(1):132-6. · 3.27 Impact Factor
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ABSTRACT: The Na+/H+ exchangers (NHEs) are a family of antiporters involved in the maintenance of neural steady-state intracellular pH. The NHE3 seems to be the predominant subtype in central chemosensitive cells. We aimed to analyze the effect of a selective NHE3 inhibition on the respiratory pattern in spontaneously breathing rats with intact vagi. Rats were intravenously infused for 10 min with the selective NHE3 inhibitor AVE1599 (Aventis Pharma Deustchland, 0.5 and 2 mg/kg) or with phosphate buffer. Whole-body plethysmography was used to monitor breathing pattern before, during, and up to 30 min after the drug infusion. Immunohistochemistry for the c-Fos protein was performed in the animal brains and c-Fos-positive cells were counted along the brainstem. Selective NHE3 inhibition induced a significant increase in the respiratory frequency and in the number of c-Fos immunopositive cells in the lateral parabrachial nucleus, the pre-Bötzinger complex and a rostral extension of the retrotrapezoid nucleus/parapyramidal region (p<0.05, ANOVA). We conclude that systemic administration of AVE1599 increases respiratory frequency and activates ponto-medullary areas implicated in the central control of breathing and chemoreception.
Respiratory Physiology & Neurobiology 01/2009; 165(2-3):254-60. · 2.24 Impact Factor
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ABSTRACT: Previous studies have shown that selective inhibition of Na+/H+ exchanger type 3 (NHE3) induces intracellular acidification and activates CO2/H+-sensitive medullary neurons, mimicking the responses evoked by hypercapnic stimuli. In addition, NHE3 blockers administration decreases the duration of apnoea induced by laryngeal stimulation, presumably by means of central chemoreceptor activation. To test the hypothesis that the central chemoreceptor network may be affected by NHE3 inhibition, brainstem c-Fos immunoreactive cell counting was performed after systemic administration of the NHE3 blocker AVE1599 (Aventis Pharma Deutschland GmbH) (2 mg/kg). The rostro-caudal quantitative c-Fos analysis showed a significant increase in the number of c-Fos positive cells in the rostral part of the ventral respiratory complex (VRC) as well as in the rostral part of the parapyramidal (Ppy) region. The VRC activated region (-4.2 to -3.2mm interaural) included the pre-Bötzinger complex, the rostral ventral respiratory group and the rostral ventrolateral medulla, all of them involved in cardiorespiratory control. The activated Ppy region corresponded with the rostral chemosensitive area, which elicits the strongest ventilatory response upon ventral medullary surface stimulation with H+/CO2. Most cells activated in Ppy after NHE3 inhibition were serotonergic. Hence, systemic application of NHE3 blockers may induce central chemoreceptors activation and an increase in the respiratory network activity in a similar way to known physiological stimuli such as hypercapnia. On the other hand, selective NHE3 blockers could be excellent tools for treatment of pathological states where central chemoreceptor function is diminished or absent, such as central hypoventilation syndrome or sudden infant death syndrome.
Autonomic Neuroscience 07/2006; 126-127:347-54. · 1.86 Impact Factor
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ABSTRACT: The caudal parapyramidal area of the rat brain contains a population of neurons that are highly sensitive to an increase in the extracellular hydrogen ion concentration ([H+]o). Some of them fire synchronously with respiration when [H+]o is increased. These chemosensitive neurons are located in the caudal ventrolateral medulla in a medial region, closest to the pyramidal tract, and a lateral region, beneath the lateral reticular nucleus. To assess the nature of medullary connections, biotinylated dextran amine injections were performed after recordings from the neurons had been completed. The injections were located within the areas containing serotonergic neurons of the caudal parapyramidal area. The injections within the medial and lateral parts of the caudal parapyramidal region revealed bilateral terminal fields of varicosities within the nucleus of the solitary tract and the ventral respiratory column. Efferent bilateral projections to the lateral paragigantocellular, lateral reticular, and inferior olive nuclei, as well as ipsilateral projections to medial and lateral caudal parapyramidal regions were also identified. Efferent projections towards the raphe obscurus from both medial and lateral caudal parapyramidal regions were found. Medial caudal parapyramidal regions also sent efferent projections towards the raphe pallidus, B1-B3 region, and to the dorsal and ventral parts of the medullary reticular nuclei. The detection of H(+)-sensitive neurons in the caudal parapyramidal area and their projections towards the nucleus of the solitary tract and to the ventral respiratory column, associated with respiratory regulation, indicate that this region could be an excellent candidate for central chemoreception.
Brain Research Bulletin 09/2005; 66(3):235-48. · 2.82 Impact Factor
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ABSTRACT: The effect of post-tetanic potentiation (PTP) induced in the pectoralis and triceps brachii muscles by high-frequency submaximal percutaneous electrical stimulation (PES) on average and maximal power attained in bench press throwing was measured in 12 healthy men. Three PES regimens were used: (a) a 7-second and (b) a 10-second trial at 100 Hz, and (c) an intermittent trial with 8 1-second tetanic trains at 100 Hz with rest periods of 20 seconds. Only nonsignificant (p > 0.05) increase was observed in average power at 8 minutes and in maximal power at 5, 8, and 11 minutes after tetanus after 7-second trial, and in maximal power at 5 and 8 minutes after tetanus after an intermittent trial. These data indicate that PES application was a noneffective stimulus for increased bench press performance. A great interindividual variability response was observed and, therefore, PTP induction for improving upper-body muscle performance needs further experiments.
The Journal of Strength and Conditioning Research 08/2005; 19(3):622-7. · 1.83 Impact Factor
