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PubMed2004

structural elucidation of novel phosphocholine-containing glycosylinositol-phosphoceramides in filamentus fungi: (2). Spectral analysis of the sugar-inositol portion by 2D-NMR.

The sugar-inositol portion of the novel glycosylinositol-phosphoceramides, ZGL1 and ZGL2, from the filamentus fungi, Acremonium sp., were elucidated by a combination of NMR techniques including (1)H-(1)H (COSY and HOHAHA) and (1)H-(13)C (HMQC and HMBC) spectroscopy. Further, examination of the (1)H-(31)P HMQC spectrum showed connectivity of inositol and ceramide through phosphate.

Acremonium↗
PubMed2004

Spectral analysis of heart rate variability during exercise in trained subjects.

PURPOSE: To investigate the effects of strenuous exercise on heart rate variability (HRV). METHODS: We evaluated the effects of exercise intensity and duration on HRV indices in 14 healthy trained subjects. Each subject exercised for 3, 6, and 9 min at 60 and 70% of the power achieved at maximal oxygen consumption (PVO2(max)) and for 3 and 6 min (or 3 min twice) at 80% of PVO2(max). The electrocardiogram RR intervals were recorded then processed by fast(FFT) and short-time (STFT) Fourier transform for determination of low-frequency (LF, 0.045-0.15 Hz) and high-frequency (HF, 0.15-1.0 Hz) components. RESULTS: The LF and HF components expressed as absolute power (ms2) decreased significantly at the onset of exercise (P < 0.05). However, with increasing exercise intensity, the HF component expressed as normalized units (n.u.) (reflecting parasympathetic modulation) increased significantly, whereas the LF component (n.u.) and LF/HF ratio (both reflecting sympathetic modulation) decreased significantly (P < 0.05). STFT showed that increasing exercise intensity was associated with a shift in HF peak frequency related to an increase in respiratory rate and a marked decrease in LF power (ms2). Moreover, HFn.u. rose (r = 0.918, P < 0.01) and LFms2 fell as minute ventilation increased (r = 0.906, P < 0.01). CONCLUSIONS: Parasympathetic respiratory control and nonautonomic mechanisms may influence the HF-peak shift during strenuous exercise. HRV and the usual indexes of sympathetic activity do not accurately reflect changes in autonomic modulation during exhaustive exercise.

Adult↗
PubMed2000

Spectral analysis of vibrational harmonic motion by use of a continuous-wave CO2 Doppler lidar.

Vibrational motion of a harmonic oscillator was investigated with a focused continuous-wave (cw) CO2 Doppler lidar at 9.1-microm wavelength. A continuum of frequencies along with many discrete, equally spaced, resonant frequency modes was observed. The frequency modes are similar in structure to the oscillatory longitudinal modes of a laser cavity and arise because of interference of the natural resonant frequency of the oscillator with specific frequencies within the continuum. Each consecutive resonant frequency mode occurred for a movement of the oscillator much less than the wavelength of incident lidar radiation. For vigorous vibration of the oscillator, the observed spectra may be indicating nonlinear motion.

Journal Article↗
PubMed2001

Daytime sleepiness and EEG spectral analysis in apneic patients before and after treatment with continuous positive airway pressure.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent apneas during sleep, resulting in repetitive hypoxemic episodes and interruptions of the normal sleep pattern. A previous study showed EEG slowing (ie, a higher ratio of delta + theta frequencies to alpha + beta frequencies on EEG) during rapid eye movement (REM) sleep and wakefulness in untreated OSAS patients. STUDY AND OBJECTIVES: To determine whether EEG slowing is reversible with continuous positive air pressure (CPAP) treatment and to verify whether the persistence of excessive daytime sleepiness (EDS) is correlated with residual slowing of the EEG. PATIENTS: Ten healthy subjects (9 men and 1 woman) and 14 patients with moderate-to-severe OSAS (13 men and 1 woman) were studied before and after 6 months of treatment with CPAP. RESULTS: Untreated OSAS patients showed EEG slowing in frontal and central cortical regions during both wakefulness and during REM sleep compared to healthy control subjects. This EEG slowing was found to be independent of time spent with arterial oxygen saturation < 90%, severity of OSAS, or mean sleep latency as determined by the multiple sleep latency test. CPAP treatment was found to correct the EEG slowing for both REM sleep and wakefulness. Daytime sleepiness also greatly improved with treatment, but some degree of somnolence remained. CONCLUSION: CPAP treatment was found to correct the EEG slowing that was observed in untreated OSAS patients. Persistent EDS may be related to persistent obesity after CPAP treatment.

Adult↗
PubMed1993

Spectral analysis of radial pulse in patients with acute, uncomplicated myocardial infarction.

The aim of this study was to examine the frequency spectrum of arterial pulses in 17 patients with acute, uncomplicated myocardial infarction. Recordings of right radial pulses were taken from these patients immediately after their arrival at the emergency room. This information was considered as baseline data and was monitored at the same time each day for up to 7 days. These serial recordings of radial pulses were then analyzed together with recordings from 3 control groups of patients not suffering from myocardial infarction. These included subjects who underwent coronary arteriography (n = 24), coronary angioplasty (n = 18), and mitral valvuloplasty (n = 13). The method of analysis involved a discrete Fourier transformation of radial pulses recorded from an external pulsation transducer to obtain "power spectra" for pulse waves. There was no significant change in the power spectrum for each of the 3 control groups although significant clinical and hemodynamic improvement was observed in the coronary angioplasty and mitral valvuloplasty patients. In sharp contrast, the intensity of the frequency moduli C2 and C3 in the target group fell on arrival at the emergency room and then gradually increased while the average pulse energy (frequency modulus C0) decreased simultaneously with stable recovery from the acute myocardial infarction. In order to investigate the changes in C2 and C3 in the target group, the effective renal plasma flow (ERPF) was first determined for 10 of the 17 patients using intravenous I-131 labelled iodo-ortho-hippurate. A second reading was taken a week later. Eight of the 10 patients were found to have a relatively "higher" ERPF at the onset of acute myocardial infarction with an average reading of 450.1 +/- 168.9 ml/min, compared with the data obtained a week later (374.1 +/- 130.4 ml/min, p < 0.02). An inverse correlation existed between the percentage of "initial drop" in frequency moduli C2 and C3 in the power spectra of the radial pulses and the percentage of "initially higher" ERPF (r = -0.66 and -0.70, respectively, p < 0.05). It is concluded that there was a specific change in the power spectrum of the radial pulses which were recorded and analyzed noninvasively in patients with acute, uncomplicated myocardial infarction. Changes in the ERPF may exert an influence on the frequency moduli C2 and C3 of the power spectra of the radial pulses after heart attack, suggesting that the aorta and the closely organs may cause coupled oscillation. Theoretically this structure is equivalent to a resonance circuit.

Aged↗
PubMed1988

Power spectral analysis of photic driving elicited by flickering dot pattern and red flicker stimuli in adult psychiatric outpatients--with special reference to age and gender.

Power spectrum of photic driving elicited by 5/sec flickering dot pattern (FDP) and 5/sec red flicker (RF) stimuli was investigated in 137 psychiatric outpatients. They consisted of 61 adults (33 males and 28 females) from 20 to 44 years of age, 55 preseniles (25 males and 30 females) from 45 to 64 years and 21 seniles (9 males and 12 females) over 65 years of age. Powers of 5 and 10/sec photic driving elicited by FDP and RF stimuli were greater than those of the other higher harmonics and increased significantly with age. When such a finding was compared in relation to gender, significant increase of power with age was found for 5 and 10/sec photic driving elicited by both stimuli in females, whereas it was found only for 5/sec photic driving elicited by RF stimulation in males. Our findings suggest that the visual system of older female patients is very responsive not only to patterned stimuli but also to red flicker stimulation.

Adult↗
PubMed1987

Spectral analysis of instantaneous frequency responses to sinusoidal stimulation in cutaneous mechanoreceptor afferent units of frogs.

While applying the Fast Fourier Transform to the instantaneous frequency responses to sinusoidal indentations of the cutaneous mechanoreceptor afferent units in frogs, we examined quantitatively the dynamic responses of these units. In two kinds of slowly adapting (SA) units, i.e., frog type I and frog type II units, and in rapidly adapting (RA) type I units, the instantaneous frequency responses could be reconstructed by summation of the DC component and the major 3-5 harmonics in the power spectra. In both types of SA units, the fundamental wave was the largest in power of the spectrum, but in the RA units, the 2nd harmonic was the largest. In SA units, the phase of the fundamental wave advanced by 20-55 degrees relative to the sinusoidal stimulation, but the phase of the 2nd harmonic of the RA units advanced by ca. 90 degrees. The magnitude of each component in the power spectra, especially the fundamental wave of the two SA units and the 2nd harmonics of the RA unit, increased with an increase in stimulus amplitude and frequency. The phases of the harmonics in both SA and RA types were fairly constant over varying amplitudes and frequencies of sinusoidal stimulation. The present findings indicate that both the frog type I and type II cutaneous mechanoreceptor afferent units detect both indentation magnitude and positive velocity, and that the RA type I cutaneous mechanoreceptor afferent units detect the stimulus velocity.

Action Potentials↗
PubMed2006

Power spectral analysis of heart rate variability during the 100-g oral glucose tolerance test in pregnant women.

OBJECTIVE: The aims of the present study were to 1) evaluate autonomic function during the oral glucose tolerance test (OGTT) in pregnant women and 2) investigate whether gestational diabetes mellitus (GDM) modifies autonomic control of heart rate variability. RESEARCH DESIGN AND METHODS: We prospectively studied 27 pregnant women (15 without GDM, 12 with GDM) during a 100-g OGTT. The maternal electrocardiogram was recorded before and 60 min after glucose ingestion, when peak glucose levels are expected. The time and frequency domains of maternal cardiac intervals were analyzed. RESULTS: There was a significant decrease in the high-frequency (HF) band in both groups after the ingestion of glucose. The normalized low-frequency (LF) band significantly increased and the normalized HF band significantly decreased after glucose ingestion. The LF-to-HF ratio was significantly higher in the group with GDM at baseline and significantly increased in both groups after glucose ingestion. A regression analysis revealed a significant decrease in the HF band with increasing blood glucose levels. CONCLUSIONS: Acute elevation of blood glucose levels during the OGTT caused substantial autonomic alterations, including sympathetic activation and parasympathetic withdrawal. Both arms of the autonomic system were affected during the test, thus lending support to the concept that these changes are centrally integrated. The autonomic changes were less pronounced in women with GDM compared with in normal control subjects, suggesting that chronic hyperglycemia and hyperinsulinemia may alter modulation of the autonomic nervous system.

Adult↗
PubMed2003

Spectral analysis of heart rate variability in dogs with mild mitral regurgitation.

OBJECTIVE: To assess autonomic function in dogs with mild mitral regurgitation (MR) that did not have clinical signs of the condition. ANIMALS: 6 healthy adult Beagles. PROCEDURE: Mild MR was experimentally induced. A 24-hour ambulatory ECG was recorded before and after induction of MR. Heart rate variability was analyzed in frequency domains by use of the ambulatory ECG. Low-frequency (LF) and high-frequency (HF) power were calculated by integrating over their frequency intervals, and the ratio of LF to HF was also calculated. Measurements of frequency domains were analyzed for 4 time periods (midnight to 6 AM, 6 AM to noon, noon to 6 PM, and 6 PM to midnight). RESULTS: Dogs with experimentally induced MR were classified as International Small Animal Cardiac Health Council class Ia. The HF power of dogs with MR was significantly decreased between 6 AM and noon. The ratio of LF to HF in dogs with MR was significantly increased for the periods between midnight and 6 AM, 6 AM and noon, and noon and 6 PM. CONCLUSIONS AND CLINICAL RELEVANCE: Compensatory response through autonomic modulation was observed in dogs with mild MR that did not have abnormalities, except for cardiac murmur, during clinical examination. This result suggests that treatment during the early stages of mild MR may be beneficial. Additional studies are necessary to determine whether such treatment will delay the onset of congestive heart failure and prolong survival in dogs affected with mild MR.

Animals↗
PubMed1980

Human intelligence and power spectral analysis of visual evoked potentials.

The relationship between intelligence and power spectra of visual evoked potential was investigated using 8 normal and 8 mentally retarded children as subjects. The results showed the power spectrum of mentally retarded has a peak at 4 to 6 Hz, whereas that of normal has two apparent peaks at 4 and 12 Hz. It appears the peak at 12 Hz reflects the difference of intelligence.

Adolescent↗
PubMed1990

Spectral analysis of interviews conducted by Rogers and Ellis.

Recordings of famous therapeutic interviews were digitized by computer, then subjected to time-series analysis. Spectrograms produced by the same therapist seeing different patients were similar, while spectrograms of different therapists were rather divergent. Further analyses were carried out on the digitized data. The techniques used offer promise as an objective way of quantifying therapeutic interview data.

Arousal↗