Effect of dietary omega-3 fatty acid deficiency on heart rate variability in hooded rats

Introduction: Recent reports in adult humans suggest that heart rate variability is modulated by the concentration of omega-3 polyunsaturated fatty acids (PUFA) contained in blood cell membranes. Material and methods: Hurst analysis of ECG data was conducted on 12 male adult hooded (Long-Evans) rats, representing the 3rd generation to be fed diets that were either deficient in, or supplemented with, omega-3 PUFA. ECG data were obtained from surface electrodes and 4000 beats were analyzed for each animal. Results: Dietary manipulation, despite leading to large changes in tissue omega- 3 PUFA levels, did not significantly affect the complexity of heart rate dynamics, with Hurst exponent (H) values of 0.15&plusmn;0.02 and 0.12&plusmn;0.03, for animals fed omega- 3 fatty acid-adequate and -deficient diets, respectively. Mean heart rate was also unaffected by the diets. A power calculation revealed that about one hundred animals per group would have been required to avoid a type II error. Conclusions: According to this model of dietary PUFA manipulation, omega-3 fatty acids are unlikely to exert a large effect on the autonomic functions that control heart rate variability. Prospective studies into the effect of omega-3 fatty acids on HRV should consider the need for large sample size as estimated by the results contained in this report.<br /

Serum 25-Hydroxyvitamin D and the Incidence of Acute Viral Respiratory Tract Infections in Healthy Adults

Declining serum concentrations of 25-hydroxyvitamin D seen in the fall and winter as distance increases from the equator may be a factor in the seasonal increased prevalence of influenza and other viral infections. This study was done to determine if serum 25-hydroxyvitamin D concentrations correlated with the incidence of acute viral respiratory tract infections.In this prospective cohort study serial monthly concentrations of 25-hydroxyvitamin D were measured over the fall and winter 2009-2010 in 198 healthy adults, blinded to the nature of the substance being measured. The participants were evaluated for the development of any acute respiratory tract infections by investigators blinded to the 25-hydroxyvitamin D concentrations. The incidence of infection in participants with different concentrations of vitamin D was determined. One hundred ninety-five (98.5%) of the enrolled participants completed the study. Light skin pigmentation, lean body mass, and supplementation with vitamin D were found to correlate with higher concentrations of 25-hydroxyvitamin D. Concentrations of 38 ng/ml or more were associated with a significant (p<0.0001) two-fold reduction in the risk of developing acute respiratory tract infections and with a marked reduction in the percentages of days ill.Maintenance of a 25-hydroxyvitamin D serum concentration of 38 ng/ml or higher should significantly reduce the incidence of acute viral respiratory tract infections and the burden of illness caused thereby, at least during the fall and winter in temperate zones. The findings of the present study provide direction for and call for future interventional studies examining the efficacy of vitamin D supplementation in reducing the incidence and severity of specific viral infections, including influenza, in the general population and in subpopulations with lower 25-hydroxyvitamin D concentrations, such as pregnant women, dark skinned individuals, and the obese

Assessing Free-Living Postural Sway in Persons With Multiple Sclerosis

Postural instability is associated with disease status and fall risk in Persons with Multiple Sclerosis (PwMS). However, assessments of postural instability, known as postural sway, leverage force platforms or wearable accelerometers, and are most often conducted in laboratory environments and are thus not broadly accessible. Remote measures of postural sway captured during daily life may provide a more accessible alterative, but their ability to capture disease status and fall risk has not yet been established. We explored the utility of remote measures of postural sway in a sample of 33 PwMS. Remote measures of sway differed significantly from lab-based measures, but still demonstrated moderately strong associations with patient-reported measures of balance and mobility impairment. Machine learning models for predicting fall risk trained on lab data provided an Area Under Curve (AUC) of 0.79, while remote data only achieved an AUC of 0.51. Remote model performance improved to an AUC of 0.74 after a new, subject-specific k-means clustering approach was applied for identifying the remote data most appropriate for modelling. This cluster-based approach for analyzing remote data also strengthened associations with patient-reported measures, increasing their strength above those observed in the lab. This work introduces a new framework for analyzing data from remote patient monitoring technologies and demonstrates the promise of remote postural sway assessment for assessing fall risk and characterizing balance impairment in PwMS

Analysis^a of variables between groups with 25-hydroxyvitamin D concentrations of ≥38 ng/ml and <38 ng/ml.

a<p>Contingency tables calculating two-tailed p values using Fisher's exact test with Bonferroni correction for multiple testing were used.</p

Length of time to viral infection related to initial serum concentration of 25-hydroxyvitamin D.

<p>Shown are the results of the pharmacodynamic model relating 25-hydroxyvitamin D to length of time before a viral respiratory tract infection. The model equation is Log(time to event) = b₀+b₁/(Maximal 25OH-Vit D–serum 25-OH vitamin D+1) calculated using a Weibull loss function. The parameters associated with the regression are as follows, given with 95% CI and P-values: b₀ = 4.29 (3.50–4.96), <0.001; b₁ = 38.33 (9.64–76.48), <0.001; Sigma = 0.79 (0.65–0.97), <0.001. Overall P-value for this model was <0.0023. Curves are fitted 0.1, 0.5 and 0.9 quantiles as a function of the regressor. The x points represent individuals who developed viral infections, and the other points represent individuals who did not develop infections and the three who were not followed until the end of the observation period. For the individuals who developed viral infections (x points) the mean age was 46.9 years; there were 47% men; 76.5% had light pigmentation, 18.8% intermediate pigmentation, 4.7% dark pigmentation; the mean initial 25-hydroxyvitamin D concentration was 26.12 ng/ml; and the mean vitamin D supplementation 292.5 IU. For the individuals who did not develop viral infections (the other points) the mean age was 47.0 years; there were 39.8% men; 78.8% had light pigmentation, 14.2% intermediate pigmentation, 7.0% dark pigmentation; the mean initial 25-hydroxyvitamin D concentration was 30.03 ng/ml; and the mean vitamin D supplementation 601.4 IU.</p

Serum 25-hydroxyvitamin D concentrations over the course of the study by gender and skin pigmentation.

<p>Serum 25-hydroxyvitamin D concentrations over the course of the study by gender and skin pigmentation.</p

Survival without respiratory viral infection over course of study, stratified by serum 25-hydroxyvitamin D concentrations.

<p>Results of Cox proportional hazard analysis for time to viral infection, stratified by serum 25-hydroxyvitamin D concentrations. Parameters included 103 events (viral infections), 3 in the ≥38 ng/ml group and 100 in the <38 ng/ml group, and 114 censorings (15 without infection in the ≥38 ng/ml group, 99 in the <38 ng/ml group, and 3 lost to follow-up). The parameter estimate for 25-hydroxyvitamin D≥38 ng/ml was −0.66 (−1.36—0.17) 95% CI and the risk ratio 0.51 (0.25 to 0.84) 95% CI (p<0.0001).</p