The oat compared with the wheat cereal produced lower concentrations of small, dense LDL cholesterol and LDL particle number without producing adverse changes in blood triacylglycerol or HDL-cholesterol concentrations. These beneficial alterations may contribute to the cardioprotective effect of oat fiber.

Heart rate variability (HRV) is a major noninvasive technique for evaluating the autonomic nervous system (ANS). Use of time-frequency approach to analyze HRV allows investigating the ANS behavior from the power integrals, as a function of time, in both steady-state and non steady-state. Power integrals are examined mainly in the low-frequency and the high-frequency bands. Traditionally, constant boundaries are chosen to determine the frequency bands of interest. However, these ranges are individual, and can be strongly affected by physiologic conditions (body position, breathing frequency). In order to determine the dynamic boundaries of the frequency bands more accurately, especially during autonomic challenges, we developed an algorithm for the detection of individual time-dependent spectral boundaries (ITSB). The ITSB was tested on recordings from a series of standard autonomic maneuvers with rest periods between them, and the response to stand was compared to the known physiological response. A major advantage of the ITSB is the ability to reliably define the mid-frequency range, which provides the potential to investigate the physiologic importance of this range.

The continuous wavelet transform (CWT) is specifically efficient in the analysis of transient and non-stationary signals. As such, it has become a powerful candidate for time-frequency analysis of cardiovascular variability. CWT has already been established as a valid tool for the analysis of single cardiovascular signals, providing additional insights into the autonomous nervous system (ANS) activity and its control mechanism. Intercorrelation between cardiovascular signals elucidates the function of ANS central control and the peripheral reflex mechanisms. Wavelet transform coherence (WTC) can provide insight into the transient linear order of the regulatory mechanisms, via the computation of time-frequency maps of the time-variant coherence. This paper presents a framework for applying WTC for quantitative analysis of coherence in cardiovascular variability research. Computer simulations were performed to estimate the accuracy of the WTC estimates and a method for determining the coherence threshold for specific frequency band was developed and evaluated. Finally, we demonstrated, in two representative situations, the dynamic behaviour of respiration sinus arrhythmia through the analysis of the WTC between heart rate and respiration signals. This emphasizes that CWT and its application to WTC is a useful tool for dynamic analysis of cardiovascular variability.

The results of epidemiologic studies suggest that increased intake of dietary fiber is associated with lower levels of arterial blood pressure (BP). However, there is little information available addressing the possibility that increased oat consumption may reduce arterial BP in individuals with elevated arterial BP. To test this hypothesis, middle-aged and older men (n = 36; body mass index, 25-35 kg/m(2); aged 50-75 y) with elevated BP (systolic BP 130-159 mmHg and/or diastolic BP 85-99 mmHg) were randomly assigned to consume an additional 14 g/d of dietary fiber in the form of oat (5.5 g beta-glucan, n = 18) or wheat cereals (no beta-glucan, n = 18) for 12 wk. Casual resting arterial BP was measured at baseline and after 4, 8 and 12 wk of intervention. The 24-h ambulatory arterial BP was measured at baseline and after 12 wk of intervention. There were no differences in casual resting or 24-h ambulatory BP at baseline in the two groups. Casual systolic BP (SBP) did not change as a result of the 12-wk intervention in the oat (138 plus minus 2 vs. 135 plus minus 3 mmHg) or wheat (142 plus minus 2 vs. 140 plus minus 3 mmHg) groups, respectively (all P > 0.05). Casual diastolic BP (DBP) also did not change in the oat (89 plus minus 2 vs. 88 plus minus 2 mmHg) or wheat (90 plus minus 2 vs. 91 plus minus 2 mmHg) group during this period (all P > 0.05). Further, 24-h, daytime and nighttime SBP and DBP did not decrease with the intervention. Therefore, the results of the present study suggest that any cardioprotective benefit of regular oat consumption may not be conferred via an arterial BP-lowering effect.

One of the primary pathologies associated with hypertension is a complex autonomic dysfunction with evidence of sympathetic hyperactivity and/or vagal withdrawal. We investigated the possibility for early detection of essential hypertension on the basis of the analysis of heart rate (HR) and blood pressure fluctuations, which reflect autonomic control. Young adult normotensive offspring of one hypertensive parent (KHT; n = 12) and normotensive offspring of two normotensive parents (YN; n = 14) participated in this study. ECG, continuous blood pressure, and respiration were recorded during steady-state conditions and under various autonomic challenges. Time-frequency decomposition of these signals was performed with the use of a continuous wavelet transform. The use of the wavelet transform enables the extension of typical HR variability analysis to non-steady-state conditions. This time-dependent spectral analysis of HR allows time-dependent quantification of different spectral components reflecting the sympathetic and parasympathetic activity during rapid transitions, such as an active change in posture (CP). During an active CP from the supine to standing position, KHT demonstrated a significantly greater increase in the low-frequency fluctuations in HR than YN, indicating enhanced sympathetic involvement in the HR response to CP, and a reduced alpha-index, indicating decreased baroreceptor sensitivity. On recovery from handgrip, vagal reactivation was more sluggish in KHT. These results indicate the early existence of malfunctions in both branches of autonomic control in individuals at increased risk of hypertension.