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PubMed1978

[Spectral analysis of blood pressure-, heart rate- and respiration rhythms in different postures in probands and patients with neurovegetative disorders].

In a statistical comparison between autospectra of blood pressure, heart rate, and respiration rhythms in 16 healthy volunteers in sitting and standing position and between these and results in 16 patients suffering from autonomic disorders there have been shown: (1) significantly higher power spectral densities in distinct frequency bands of the parameters in orthostasis (with exception of heart rate spectra) and (2) more distinct changes in patients. Moreover, a significant decrease of spectral densities of heart rate waves was computerized in patients. The physiological background is discussed.

Adult↗
PubMed1976

[Spectral analysis of the EEG in patients with cerebral contusions and traumatic intracranial hematomas].

The authors subjected to a mathematical analysis 80 electroencephalograms registered in 20 patients with contusional foci andintracranial hematomas, verified during surgical operations. In order to evaluate the peculiarities of the EEG spectrograms an adaptive system of filtration was proposed which was based on an approximation of the assessment of the spectral density. The used method with the aid of computers permitted to detect the characteristic disturbances of the frequency spectrum in the EEG which had a topical and differential diagnostical significance for patients in the acute period of a severe brain injury.

Adolescent↗
PubMed1993

Assessment of autonomic nervous activity by heart rate spectral analysis in patients with variant angina.

The purpose of this study was to assess the role of the autonomic nervous system in the pathogenesis of coronary artery spasm in patients with variant angina. We evaluated cardiac sympathetic and parasympathetic activity from the power (logarithmic scale) of the low-frequency (approximately 0.04 to 0.12 Hz) and the high-frequency (approximately 0.22 to 0.32 Hz) spectral components of heart rate variability with Holter monitoring in seven patients with nocturnal variant angina and in 11 healthy men who served as control subjects. None of the patients had organic coronary artery stenosis as determined by angiography. Low-frequency and high-frequency logarithmic values were calculated for each 5-minute period from 30 minutes before to immediately before each angina attack. The logarithmic low-frequency value during the 5-to-0-minute period was greater than the low-frequency values during most of the other periods (p < 0.05 - p < 0.01). The logarithmic high-frequency values during the 10-to-5-minute and 5-to-0-minute periods were greater than those during the 30-to-25-minute period (p < 0.05 and p < 0.01, respectively). These data indicate that parasympathetic activity increased during the 10 minutes before attacks of nocturnal variant angina, whereas sympathetic activity with vagal modulation increased during the 5 minutes before such attacks. The same pattern of changes in heart rate variability was found in the absence of ST-segment elevation in patients and in control subjects. So this phenomenon was not just associated with coronary spasm and variant angina. It is suggested that circadian variation in disease activity is also associated with spontaneous attacks.

Adult↗
PubMed1990

A spectral analysis of the high frequency QRS potentials observed during acute myocardial ischemia in dogs.

Electrocardiographic manifestations of transient myocardial ischemia were studied in 10 dogs undergoing occlusion of the left anterior descending coronary artery, using frequency domain analysis of the high frequency QRS potentials. Ischemia was induced via a balloon occluding cuff placed around the coronary artery. Electrocardiographic waveforms recorded before and during the ischemic state were averaged together and then filtered between 150 and 250 Hz to obtain the high frequency QRS complex. The spectral curve in the power spectrum of the high frequency QRS components was calculated using an algorithm for fast Fourier transformation. Balloon inflation was accompanied by morphological changes in the spectral curve in 7 of 10 experiments. Morphological changes, seen as zones of reduced amplitude in the time domain, appear as two separate peaks in the frequency domain. These changes were seen early in ischemia and were not accompanied by significant changes in the QRS complex or ST segment of the conventional surface electrocardiogram. The power spectrum of the high-frequency QRS potentials appears to detect evidence of transient ischemia and may provide useful information regarding the presence of myocardial ischemia.

Action Potentials↗
PubMed1995

Spectral analysis of arterial pressure lability in rats with sinoaortic deafferentation.

Traditionally, the standard deviation (SD) of the mean arterial pressure (AP) has been used as an index for the AP lability produced by interruption of baroreceptor afferents. Although a useful measure of variance about the mean, the SD does not provide any information about the temporal characteristics of this variability. We employed two different spectral analytic techniques to characterize AP waveforms in rats with sinoaortic deafferentation (SAD) and in sham-operated (Sham) rats to determine if the AP waveform in SAD animals was qualitatively and/or quantitatively different from that of Sham animals. The SAD and Sham animals exhibited qualitatively different spectral profiles, suggesting that lability of AP in SAD animals is not simply an exaggeration of normal fluctuations. In addition, a low-frequency (0.3-0.5 Hz) spectral peak was found in Sham but not SAD animals, suggesting that it is associated with the baroreflex. Finally, we observed in both normal rats and rats without intact baroreceptors that the spectral components of AP are not static but rather vary continuously across time.

Afferent Pathways↗
PubMed1985

Evaluation of aortic stenosis by spectral analysis of the murmur.

A relation between the peak transaortic pressure gradient and the frequency content of the murmur (r = 0.79) was demonstrated in a prospective "test" set of 50 patients with the clinical diagnosis of aortic stenosis. After heart sounds were recorded and digitized, three segments of the systolic murmur were isolated and analyzed by fast Fourier transform technique. An average frequency spectrum was quantitated by a previously described empiric spectral estimator. Clinical data and spectral ratio were correlated with the transaortic pressure gradient and aortic valve area was calculated from cardiac catheterization data. The best prediction of the transaortic pressure gradient was obtained when a 170 ms murmur segment was analyzed and when the predictive algorithm also included the aortic dimension (r = 0.87). The aortic valve area was poorly predicted (r = -0.48) unless estimates of blood flow and valvular calcification were included in the algorithm (r = 0.84). Further refinement of this technique may provide a non-invasive and clinically useful method for the estimation of aortic valve stenosis.

Adult↗
PubMed1986

31P-NMR investigation of magnetically oriented rod outer segments. Spectral analysis and identification of individual phospholipids.

A 31P-NMR study of magnetically oriented bovine rod outer segments is presented. We demonstrate that carefully isolated bovine rod outer segments retain the capacity to orient in a magnetic field. Maximal orientation (85-90%) is achieved at field strengths over 4.7 T in the NMR spectrometer. The lineshape of the 'oriented spectra' is totally different from the 'bilayer lineshape' of randomly oriented photoreceptor membranes. The oriented spectra consist of two phospholipid peaks, a major low-field peak (75-80% of the total intensity) near 30 ppm, and a minor high-field peak near - 14 ppm as well as two sharp metabolite peaks around 0 ppm. The phospholipid peaks are a composite of three narrower partially resolved resonances assigned to the individual phospholipid classes phosphatidylserine, phosphatidylcholine and phosphatidylethanolamine. Based on the morphology and magnetic anisotropy of the rod outer segment, the major phospholipid peak is attributed to the flat part of the disk membranes while the phospholipids of the plasma membrane are thought to contribute only to the minor peak. Disk rim phospholipids and non-oriented material contribute to the minor peak and, in addition, contribute some intensity to the middle part of the spectrum. The phospholipid class composition of the major peak is estimated by spectral simulation and is consistent with the phospholipid class composition of rod outer segment membranes. Hence, 31P analysis of oriented rod outer segments resolves the main phospholipids in at least two different membrane pools in the rod outer segment and allows the differential investigation of these pools. Most of the mobile phosphate metabolite intensity resides in the Pi peak at 3.5 ppm. A slight shift in the Pi resonance position indicates a 0.2 pH unit acidification upon illumination of rhodopsin. The absence of detectable nucleotide resonances, when compared with chemical analysis, indicates that the majority of the nucleotide population present is rather immobile and probably bound to the membranes.

Animals↗
PubMed2006

[The spectral analysis of the variability of frequency and amplitude characteristics of tremor in patients with essential tremor and tremulous form of Parkinson's disease].

A clinical and electrophysiological analysis of tremor in patients with essential tremor and tremulous form of Parkinson's disease as well as healthy subjects has been conducted. The method of accelerometry was used for assessing the variability of frequency and amplitude tremor. A comparison of the time-domain characteristics and spectral components of tremor was made between the two groups of patients that allowed to find the series of typical characteristics, which were important for understanding of its pathogenesis and differential diagnosis of this disease.

Diagnosis, Differential↗
PubMed1999

[Power Doppler US in breast masses: correlation of spectral analysis findings with pathological features].

The purpose of this study was to clarify the usefulness of power Doppler imaging for the diagnosis of breast masses. Materials were histologically confirmed breast masses: 24 benign lesions, 4 non-invasive carcinomas, and 54 invasive carcinomas. In invasive breast carcinoma, pathological examination was used to classify the degree of intratumor fibrous stroma (IFS) into three groups. The relationships between IFS and Doppler spectral parameters (Vmax, Vmin, PI, RI) were evaluated retrospectively. High PI and low Vmin values were well correlated with IFS grade. Carcinomas with low IFS grades had higher Vmax values than benign lesions.

Adult↗
PubMed1996

Spectral analysis of lactoperoxidase. Evidence for a common heme in mammalian peroxidases.

The identity of the non-extractable heme of mammalian lactoperoxidase (LPO) has remained unsolved for over 40 years. Accepted possibilities include a constrained heme b or an 8-thiomethylene-modified heme b. Recent studies of myeloperoxidase (MPO) (Fenna, R., Zeng, J., and Davey, C. (1995) Arch. Biochem. Biophys. 316, 653-656; Taylor, K. L., Strobel, F., Yue, K. T., Ram, P., Pohl, J., Woods, A. S., and Kinkade, J. M., Jr. (1995) Arch. Biochem. Biophys. 316, 635-642) suggest possible prosthetic group similarities between MPO and LPO. To address heme identity for LPO, we used comparative magnetic circular dichroism (MCD) spectroscopy of LPO versus myoglobin (Mb), horseradish peroxidase (HRP), and MPO. MCD spectra of native Fe3+-LPO and Fe3+-CN--LPO are approximately 10 nm red shifted from analogous forms of Mb and HRP, including the formate-Mb adduct. MCD spectra of native LPO and MPO are opposite in sign, and MCD spectra of their cyanoadducts also differ. These data indicate the LPO heme is distinct from heme b of Mb and HRP as well as from "heme m" of MPO. From this work and literature analysis, we suggest that the non-extractable "heme l" of LPO has the two vinyl groups of heme b but lacks the 2-sulfonium-vinyl linkage of heme m. The observed red shifts in LPO spectra may derive from ester linkages to protein as for MPO. Strong spectral analogies between LPO and mammalian peroxidases (e.g. from saliva, eosinophils, thyroid, intestine) indicate similar prosthetic heme moieties.

Animals↗
PubMed1983

Noninvasive diagnosis of aortic and mitral valve disease with pulsed-Doppler spectral analysis.

To differentiate normal from abnormal left-sided heart valves, 34 adults (6 normal and 28 abnormal) with 48 valve lesions proved at catheterization were examined using a 3 MHz duplex pulsed Doppler echocardiograph with 2-dimensional verification of sample volume position and on-line display of the Doppler audio spectrum. A uniform protocol was used to position the sample volume for each lesion and to analyze the Doppler spectral data. Intracardiac blood turbulence, manifested by an increased Doppler spectral envelope area, was the noninvasive indicator of disease. The specific lesion present was determined by documenting the intracardiac location and timing of the turbulence. Doppler spectral envelope areas in all normal valve sites were smaller than those measured at the same sites in patients with aortic stenosis, mitral stenosis, and mitral regurgitation (p less than 0.01). Except for a single patient with minimal aortic regurgitation, spectral envelope area allowed complete separation of patients with valve disease from normal subjects (p less than 0.01). High sensitivity (97%) and specificity (100%) were noted despite the presence of multiple valve lesions in 67% of the patients. The data demonstrate application of a simple, noninvasive method of acquiring and analyzing Doppler echocardiographic data which allows accurate identification or exclusion of left-sided valve disease in adults, even in the presence of multiple valve lesions.

Adult↗
PubMed1974

Photon propagation function: spectral analysis of its asymptotic form.

The physical attitudes of source theory, displacing those of renormalized, perturbative, operator field theory, are used in a simple discussion of the asymptotic behavior of the photon propagation function. A guiding principle is the elementary consistency requirement that, under circumstances where a physical parameter cannot be accurately measured, no sensitivity to its precise value can enter the description of those circumstances. The mathematical tool is the spectral representation of the propagation function, supplemented by an equivalent phase representation. The Gell-Mann-Low equation is recovered, but with their function now interpreted physically as the spectral weight function. A crude inequality is established for the latter, which helps in interpolating between the initial rising behavior and the ultimate zero at infinite mass. There is a brief discussion of the aggressive source theory viewpoint that denies the existence of a "bare charge".

Journal Article↗
PubMed2004

Power spectral analysis of heart rate variability during helium pneumoperitoneum: The mechanism of increased cardiac sympathetic activity and its clinical significance.

BACKGROUND: Carbon dioxide pneumoperitoneum (PP) is known to induce increased cardiac sympathetic expression. The role of the insufflated gas involved in this mechanism should be elucidated in an attempt to eliminate its possible serious consequences. METHODS: Twenty-five patients undergoing elective laparoscopic cholecystectomy were prospectively analyzed for cardiac autonomic nervous activity by spectral heart rate variability. In 15 patients, helium was used as CO(2) substitution for abdominal insufflation (study group). Four frequency bands of interest were obtained from the power spectrum of R-R intervals, as well as the ratio between the low and high frequency (LF/HF), using the fast Fourier transformation algorithm to characterize the synergy of both autonomic branches during PP. RESULTS: Significantly increased values of the power spectrum related to the LF and VLF bands (from 130 to 377 msec(2)/Hz and from 145 to 516 msec(2)/Hz, respectively) were inspected during CO(2) PP, as well as increased LF/LH ratio (2.1). Using helium as CO(2) substitution has eliminated the significant changes in the power spectrum that reflect increased cardiac sympathetic activity. CONCLUSIONS: The elimination of sympathetic predominance by helium PP indicates the central role of CO(2) in establishing this phenomena. Considering this information and its other known advantages, helium should be considered for use during prolonged laparoscopic procedures for high-risk patients.

Adult↗
PubMed1993

[Spectral analysis of sounds produced by musical instruments and other sounding bodies for hearing screening of children].

Some time ago audiological screening in infants was mostly performed using musical instruments or equivalents. The use of acoustic evoked potentials and oto-acoustic emissions changed the strategies of hearing assessment in newborns and infants, however, musical instruments are still in use. An adequate interpretation of screening results obtained with musical instruments necessitates a profound knowledge of frequencies and intensities derived from these instruments. In this study spectral analyses of sounds from these instruments were performed. The results may be of value for those using musical instruments as a tool for audiological screening. In addition, the results show that with some instruments intensities able to cause inner ear damage can be generated.

Child↗
PubMed1998

Dynamic spectral analysis of event-related potentials.

This paper presents a new method for the identification of individual event related potential (ERP) components in both frequency and time domains. Using the similar basis function (SBF) algorithm the method provides a time to frequency transform, representing a frequency domain equivalent of the component waveform. Notable features of the SBF algorithm are that it allows for unevenly spaced sampled functions in both the time and frequency domains, and estimates of spectral densities are obtained by numerical computation of finite Fourier integrals. Application of this method to ERP data from 20 normal subjects demonstrated a similar shape of component amplitude frequency characteristics for traditional late component waveforms (N1, P2, N2 and P3). On this basis, a low-frequency band was found where the component amplitude frequency characteristic was described by a Gaussian function, while the component phase frequency characteristic was a linear function of frequency. These relationships are interpreted as frequency domain equivalents of the component. Transformed to the time domain, they provided an analytical description of the ERP as the sum of positive- and negative-going monopolar waves. The study points to similar mechanisms underlying these component waveforms, and analytically defines dynamic properties for the components both in the frequency and time domains.

Adult↗
PubMed1989

24 h sequential spectral analysis of arterial blood pressure and pulse interval in free-moving subjects.

A procedure for the 24 h tracking of the 0.25, 0.1, and 0.05 Hz oscillations in blood pressure (BP) and pulse interval (PI) in ambulant subjects has been developed. It includes: 1) sampling of a 24 h intra-arterial BP recording, extraction of the systolic (S) and diastolic (D) BP and PI from each heart beat followed by storage into separate series; 2) high-pass filtering and a splitting of each series into consecutive records of 256 values; 3) estimation of power spectral density (PSD) via FFT in each stationary record, and finally, computation of the power of each target oscillation. Using this procedure we analyzed data from ten hospitalized free-moving subjects in whom BP was recorded by the Oxford technique. The results revealed different patterns of the 0.25, 0.1, and 0.05 oscillations over the day-night cycle, showing a differentiated involvement during the 24 h of the mechanisms responsible for such rhythmic phenomena. Moreover, in order to reinforce the meaning of the obtained results and to exclude the possible negative effects due to the drawbacks typical of the FFT algorithm, we also performed a second spectral estimate based on the AR modeling. The obtained results validates the FFT approach.

Blood Pressure Determination↗
PubMed2006

Spectral analysis of laser Doppler skin blood flow oscillations in human essential arterial hypertension.

The aim of this study was to investigate whether human essential arterial hypertension (EHT) is associated with modification of the skin blood flowmotion (SBF), which could be a sign of skin microcirculatory impairment. Forearm skin perfusion was measured by laser Doppler flowmetry (LDF) in conventional perfusion units (PU) before and after ischemia in 20 middle-age newly diagnosed EHT untreated patients, in 20 middle-age long standing EHT treated patients and in 30 age and sex matched healthy normotensive subjects (NS). Power spectral density (PSD) of SBF total spectrum (0.009-1.6 Hz), as well of five different frequency intervals (FI), each of them related to endothelial (0.009-0.02 Hz), sympathetic (0.02-0.06 Hz), myogenic (0.06-0.2 Hz), respiratory (0.2-0.6) or cardiac (0.6-1.6) activity, was also measured in PU(2)/Hz before and after ishemia, using Fourier analysis of LDF signal. The three studied groups did not differ in basal and post-ischemic skin perfusion or in basal SBF parameters considered. However, while a significant post-ischemic increase in PSD of total spectrum SBF (P < 0.001) and of its different FI, with the only exception of respiratory FI, was observed in NS, a significsnt post-ischemic increase in PSD was observed only for total spectrum (P < 0.01) and for endothelial FI (P < 0.001) in newly diagnosed EHT patients and only for myogenic FI (P < 0.05) in long standing EHT patients. These findings suggest that the mechanisms which mediate the post-ischemic increment of SBF are perturbed earlier in human EHT than the mechanisms which mediate the skin post-ischemic hyperaemia. The same findings also suggest that the impairment of the endothelial mechanism involved in SBF control occurs by the time in the course of EHT.

Adult↗
PubMed2003

[Study on the method of skin's spectral analysis and diagnosis].

A kind of systematic structure to test skin color with optic-fiber probe is introduced. The system can be used to measure skin's reflecting spectrum by using a grating instrument system and a linear CCD sensor. According to the color theory and skin's reflecting spectrum, the formulae for calculating skin's color tri-stimulus value and chromatic error and the identified area of diseased skin's color are given. By measuring skin's surface color and reflecting spectral curve, a way to distinguish its feature, automatically and objectively, is offered. Some skin disease auto-diagnosis can be realized, comparing the reflecting spectrum and chromatic aberration of malignant skin with those of healthy skin. Good results were achieved by using this system to analyze and diagnose skin disease.

Color↗