Investigating the effectiveness of the Mediterranean diet in pregnant women for the primary prevention of asthma and allergy in high-risk infants: protocol for a pilot randomised controlled trial.

BACKGROUND: Over recent decades there has been a substantial increase in asthma and allergic disease especially in children. Given the high prevalence, and the associated high disease burden and costs, there is a need to identify effective strategies for the primary prevention of asthma and allergy. A recent systematic review of the literature found strong supportive epidemiological evidence for a protective role of the Mediterranean diet, which now needs to be confirmed through formal experimental studies. This pilot trial in pregnant women aims to establish recruitment, retention and acceptability of a dietary intervention, and to assess the likely impact of the intervention on adherence to a Mediterranean diet during pregnancy. METHODS/DESIGN: This study was a pilot, two-arm, randomised controlled trial in a sample population of pregnant women at high risk of having a child who will develop asthma or allergic disease. DISCUSSION: The work ultimately aims to contribute to improving health outcomes through seeking to reduce the incidence of asthma and allergic problems. This pilot trial will prove invaluable in informing the subsequent planned large-scale, parallel group, randomised controlled trial.

Evaluation of a cycling pre-load time trial protocol in recreationally active humans.

The need for greater sensitivity in exercise performance measures is of particular importance in nutritional intervention studies and such measures have been investigated in trained cyclists, but not in those who have no experience of laboratory testing and/or the need to pace their effort. The aim of the present study was to evaluate a mixed design approach (constant load then time-trial) endurance type cycle ergometer protocol using recreationally active participants not well accustomed to cycling. Seven participants including one female (age 25 +/- 5 years; body mass 74.4 +/- 9.3 kg; peak VO(2) 3.91 +/- 0.96 l) completed four repeat cycle tests. The test consisted of a "pre-load" (60 min at 65% of peak VO(2)) followed by a 20 min time trial (performance measure). Reliability for the performance measure was assessed by calculating the individual participant coefficient of variation (CV) and a mean CV for the group. Excluding a familiarisation trial, mean CV for the group was 3.4% (95% confidence interval between 2.0 and 10.1%). It is concluded that the performance test described can be used in recreationally active young adults with lower variation after one familiarisation trial. The protocol might be used to evaluate an intervention if changes in performance are expected to be greater than 3.4%, or greater than around 7% if a signal to noise ratio of 2: 1 was to be considered appropriate.

Creatine supplementation does not affect human skeletal muscle glycogen content in the absence of prior exercise.

Due to the current lack of clarity, we examined whether 5 days of dietary creatine (Cr) supplementation per se can influence the glycogen content of human skeletal muscle. Six healthy male volunteers participated in the study, reporting to the laboratory on four occasions to exercise to the point of volitional exhaustion, each after 3 days of a controlled normal habitual dietary intake. After a familiarization visit, participants cycled to exhaustion in the absence of any supplementation (N), and then 2 wk later again they cycled to exhaustion after 5 days of supplementation with simple sugars (CHO). Finally, after a further 2 wk, they again cycled to exhaustion after 5 days of Cr supplementation. Muscle samples were taken at rest before exercise, at the time point of exhaustion in visit 1, and at subsequent visit time of exhaustion. There was a treatment effect on muscle total Cr content in Cr compared with N and CHO supplementation (P < 0.01). Resting muscle glycogen content was elevated above N following CHO (P < 0.05) but not after Cr. At exhaustion following N, glycogen content was no different from CHO and Cr measured at the same time point during exercise. Cr supplementation under conditions of controlled habitual dietary intake had no effect on muscle glycogen content at rest or after exhaustive exercise. We suggest that any Cr-associated increases in muscle glycogen storage are the result of an interaction between Cr supplementation and other mediators of muscle glycogen storage.

Altered regulation of the PINK1 locus: a link between type 2 diabetes and neurodegeneration?

Mutations in PINK1 cause the mitochondrial-related neurodegenerative disease Parkinson's. Here we investigate whether obesity, type 2 diabetes, or inactivity alters transcription from the PINK1 locus. We utilized a cDNA-array and quantitative real-time PCR for gene expression analysis of muscle from healthy volunteers following physical inactivity, and muscle and adipose tissue from nonobese or obese subjects with normal glucose tolerance or type 2 diabetes. Functional studies of PINK1 were performed utilizing RNA interference in cell culture models. Following inactivity, the PINK1 locus had an opposing regulation pattern (PINK1 was down-regulated while natural antisense PINK1 was up-regulated). In type 2 diabetes skeletal muscle, all transcripts from the PINK1 locus were suppressed and gene expression correlated with diabetes status. RNA interference of PINK1 in human neuronal cell lines impaired basal glucose uptake. In adipose tissue, mitochondrial gene expression correlated with PINK1 expression although remained unaltered following siRNA knockdown of Pink1 in primary cultures of brown preadipocytes. In conclusion, regulation of the PINK1 locus, previously linked to neurodegenerative disease, is altered in obesity, type 2 diabetes and inactivity, while the combination of RNAi experiments and clinical data suggests a role for PINK1 in cell energetics rather than in mitochondrial biogenesis.

L-arginine ingestion after rest and exercise: effects on glucose disposal.

PURPOSE: There is considerable interest, both in health and disease, in enhancing postexercise glucose uptake and glycogen resynthesis in skeletal muscle. The amino acid, arginine, is known to stimulate insulin release and enhance glucose-stimulated insulin release. METHODS: The present investigation examined whether an oral dose of L-arginine (10 g), when given with 70 g carbohydrate (CHO, in the form of simple sugars) improved factors associated with glucose disposal in previously exercised and nonexercised healthy males. The effects of different modes of activity (resistance or cycling exercise) upon these factors were also examined. RESULTS: Whole-blood glucose and serum insulin concentrations after L-arginine + CHO ingestion were not significantly different from the placebo condition (glycine + CHO ingestion) in all experimental treatments (nonexercised, resistance exercise, and cycling exercise). Similarly, CHO oxidation, forearm blood flow, blood pressure, and heart rate during the postingestion period were unaffected by L-arginine + CHO consumption in all three experimental treatments. CONCLUSION: A 10-g oral dose of L-arginine was found to have no effect on blood glucose disposal in human subjects after oral CHO ingestion, either when rested or after different modes of exercise known to differentially affect glucose disposal. These results suggest that the addition of L-arginine to a CHO beverage would not augment postexercise CHO replenishment in healthy human subjects.