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PubMed1991

Spectral analysis of the ECG in patients during terminal state and in the postresuscitation period.

The use of amplitude end frequency analysis of the ECG in the terminal state end postresuscitation period is presented. One hundred one studies were carried out on 64 patients in critical condition. ECG recordings were done in 3 orthogonal leads (Frank's method) with a standard amplification of 1 mV. On each lead 5-7 cardiac cycles were recorded with analysis of 2 components of the ECG: QRS complex and T wave. In order to determine the feasibility of employing such a method for forecasting pathological states, an additional 68 patients, who had been subjected to studies, were taken. In the hope of matching patterns of ECG spectral signals with indices of central haemodynamics, a group of 67 patients, who were subjected to 138 studies during the postresuscitation period, was taken. The parameters for central haemodynamics were measured by impedance cardiography with automatic analysis of the results on the EBM EC-1022. The studies carried out show that the spectral analysis of the orthogonal leads (according to Frank) brought a series of changes in the amplitude-frequency characteristics of the ECG signal in patients in the terminal state and in the postresuscitation period. The noted changes facilitate the unveiling of the disorders of the functional activity of the myocardium and the forecasting of the development of the pathological condition.

Electrocardiography↗

PubMed1991

Comparison of spinal mobility and isometric trunk extensor forces with electromyographic spectral analysis in identifying low back pain.

This study compared conventional clinical measurements with electromyographic (EMG) spectral measurements for identification of individuals with low back pain (LBP). Twenty freshman sweep rowers were subjects for this study. Range-of-motion (ROM) measurements were taken for forward bending (FB), backward bending (BB) (double inclinometers), lateral bending (LB) (tape measure), and rotation (double-arm goniometer). Intratester reliability for ROM was also assessed. The Back Analysis System was used to determine static trunk extensor strength (ie, maximal voluntary contraction [MVC]) and to compute EMG spectral parameters from a paraspinal multi-electrode array. A two-group stepwise discriminant-analysis procedure for the ROM and MVC variables correctly identified 57% of the rowers with LBP and 63% of the rowers without LBP. A similar discriminant-analysis procedure for EMG spectral parameters correctly identified either 88% of the rowers with LBP and 100% of the rowers without LBP or 100% of the rowers with LBP and 88% of the rowers with LBP, depending on whether EMG measurements of recovery were calculated at 1 minute or at 2 minutes into the recovery period. Sensitivity (66%) and specificity (71%) results from the more traditional tests suggest that these techniques may be of limited usefulness for LBP screening or diagnosis.

Adult↗

PubMed1996

Estimation of respiratory frequency from autoregressive spectral analysis of heart period.

Variability in heart period is modulated by respiration. Using an autoregressive spectral analytic approach on the heart period time series produces a components analysis. The central frequency of the heart period spectral component in the frequency of respiration (HFFreq) has been suggested as an index of respiratory frequency. The present experiment measured heart period variability (HPV) using an autoregressive algorithm and respiratory frequency using a mercury strain gauge (SGResp) to assess the relationship between the respiratory frequency indexed by the two methods. Twenty human participants were studied during resting baseline, relaxation, and mental effort conditions. Within- and between-person Pearson correlations and t-tests were used to assess the concordance between HFFreq and SGResp. Both within-person and between-person correlations indicated good concordance among the two methods. Moreover, t-tests, corrected for Type I error, indicated no significant differences between the respiratory frequency estimates derived from the two methods. The resolution of the estimates was approximately 1 breath per minute. These results suggest that the HFFreq may be a useful index of respiratory frequency.

Electrocardiography↗

PubMed2003

Enkephalins: Raman spectral analysis and comparison as function of pH 1-13.

Raman spectral studies are carried out on Leu- and Met-enkephalin as a function of the pH value in the range of 1-13. The molecules are dissolved in KCl solvent and the pH is controlled at each value. Spectral analyses reveal the dependence of the structural conformation on the pH, and a comparison of the two molecules is made in three frequency regions: the tyrosine Fermi doublet (850-830 cm(-1)), aromatic side chains (1650-1550 cm(-1)), and carboxylate (1430-1400 cm(-1)). All regions and frequencies are presented, discussed, and compared for the two molecules.

Cell Line, Tumor↗

PubMed1989

Spectral analysis of courtship songs in behavioral mutants of Drosophila melanogaster.

Spectral analyses were applied to the courtship songs of the mutants cacophony (cac), dissonance (diss), fruitless (fru), and period (per), as well as to the double mutant cac diss. Aberrant intervals between song pulses were observed in diss, cac, cac diss, and fru songs. diss males displayed a defect in song hums manifested by an irregular sine wave, although the fundamental frequencies were normal. Sine song frequencies and intrapulse frequencies were aberrant in cac diss males. Two per mutant alleles (pero1 and pers) were associated with normal song [corrected] pulses and hums. These findings are discussed with regard to the mechanisms of song production and the role of these sounds in Drosophila reproduction.

Animals↗

PubMed2003

Evaluation of counterions for electrospray ionization mass spectral analysis of a highly sulfated carbohydrate, sucrose octasulfate.

A systematic approach was used to evaluate the electrospray ionization mass spectral (ESI-MS) analysis of sucrose octasulfate (SOS), an important pharmaceutical agent. SOS represents a model for other suffated carbohydrates, such as heparin and glycosaminoglycan-derived oligosaccharides that also are highly sulfated and pose difficult analytical problems. A survey of ammonium counterions showed that 1 degree, 2 degrees, and 3 degrees ammonium salts of SOS gave substantial fragmentation as a result of sulfate loss. In contrast, quaternary ammonium and phosphonium salts gave excellent ESI spectra, particularly in the positive ion mode. This represents the first report of the ESI-MS analysis of sulfated carbohydrates in the positive ion mode.

Cations↗

PubMed1988

EEG spectral analysis after minor head injury in man.

A quantitative EEG analysis was performed on the posterior lead of 18 patients with their eyes closed 3-10 days after minor head injury. There was a significant increase of the mean power of slow alpha (8-10 c/sec), a reduction of fast alpha (10.5-13.5 c/sec), with a shift of mean alpha frequency towards lower values, and a reduction of fast beta (20.5-36 c/sec) in the patients with head injuries compared with the age- and sex-matched patients in the control group. Therefore, power spectral EEG analysis performed with the above-mentioned criteria may be suggested as a sensitive tool to be added to others during the neurophysiological follow-up studies of people with head injuries.

Accidents, Traffic↗

PubMed2004

Multiple time scales in serial production of force: a tutorial on power spectral analysis of motor variability.

We present a tutorial on a power spectral approach to variability in serial motor performance, describing as a case study two experiments on the form of the variance in two force production tasks. In Experiment 1 we examine grip force and load force in repetitive unimanual pulling; in Experiment 2, we describe repetitive bimanual pressing. In both experiments log-log plots of power spectral density of peak force of the responses in each stream against frequency (i.e. periodicity or repetition cycle defined with respect to the ordered succession of responses) were approximately linear with negative slopes which varied systematically with test conditions. We propose the two response streams in each experiment are associated with different levels of sustained attention and state a simple model involving summation of moving average processes on multiple time scales as a qualitative account of the changes in 1/f slope.

Adult↗

PubMed1984

Muscle fatigue in myophosphorylase deficiency: power spectral analysis of the electromyogram.

It has been postulated that the power spectral shift in the surface EMG during fatigue is due to accumulation of muscle lactate. This hypothesis has been directly tested by measuring such shift in 3 patients with myophosphorylase deficiency who performed sustained isometric contractions of the quadriceps muscle. It was found that the spectral shift in these patients was greater than that in normal subjects, rendering lactate as a cause of this phenomenon very unlikely. The mechanism of excessive fatiguability in myophosphorylase deficiency is thought to be due to failure of excitation of the muscle membrane; further support for this postulate is provided and it is contended that accumulation of extracellular potassium ions may explain the phenomena of spectral shift in normals and myophosphorylase deficient patients and the excessive fatiguability in the latter.

Adult↗

PubMedDate not supplied

Real time sound spectral analysis for diagnosis of thrombosed prosthetic valves.

A real time sound spectral analyzer was developed at the authors' institute and has been used for diagnosis of thrombosed valves for 15 years. The analyzer consists of a wider frequency microphone, a digital signal processor with multiple bandpass filters, and displays. To quantify the high frequency component in section pattern of opening and closing clicks, maximal frequency at -30 dB level was used at a diagnostic parameter (normalized maximal frequency, NMF). A total of 17 thrombosed valves with or without pannus formations have been experienced and SSA showed abnormality in 13 valves, which comprised of Björk-Shiley (N = 6), Starr-Edwards 2320, 6120, 6520 (N = 5) and Kay-Shiley (N = 2). The abnormal findings included NMF of opening or closing clicks lower than normal range of each type of prosthesis, and significant decrease of NMF more than 450 Hz from the value previously obtained. All diagnoses of thrombus formations and their locations were confirmed by operative or autopsy findings. The SSA failed to diagnose in four valves, which comprised of Starr-Edwards 6520 (N = 3) and Björk-Shiley (N = 1). Operative findings revealed that thrombi were formed in a manner that permitted direct collision of disc and valvular ring causing clicks with high frequency component. No pseudo-positive diagnosis for thrombosed valve was experienced in the authors series, and SSA is thought to be a reliable noninvasive technique that enables early diagnosis of a thrombosed valve.

Adult↗

PubMed1996

[A spectral analysis of heart rate variability during postural tilt].

We analyzed the spectral characteristics of heart rate variability during the 4-minute periods just before and after postural tilt and during the 4-minute period just before the occurrence of syncope or the end of the test. 6 subjects with syncope had a progressive increase in low-frequency segment during these three periods, and highfrequency segment was significantly lower than that of the 10 subjects without syncope during the three periods. Those with syncope had a significantly higher segment ratio of low-frequency segment to high-frequency than those without syncope during these three periods. Thus, the imbalance of sympathetic and parasympathetic neural tones plays an important role in the syncope induced during postural tilt. The ratio of low-frequency segment to high-frequency is a practical measure which reflects the accuracy and sensibility of interaction of sympathetic and parasympathetic neural tones.

Adult↗

PubMed1985

Multiprocessing computer system for sensory evoked potentials and EEG spectral analysis for clinical neurophysiology laboratory.

A general-purpose minicomputer has been adapted and interfaced for the averaging and analysis of clinical evoked potentials and for compressed spectral arrays (CSA) of the routine EEG. In the first 2 years of operation, over 1,000 routine clinical studies of visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) have been performed with it, as well as over 100 CSAs and a variety of special and research studies. The CSA modality gives comparative frequency-domain pictures of left and right hemisphere power. An attached graphics terminal gives a live cumulative display of the EP and CSA. In addition, the system has automated and comprehensive physician-interactive graphics analysis and report generation capabilities. The reports are finalized versions used in the patient's chart, minimizing clerical efforts.

Brain Stem↗

PubMed2005

A graph spectral analysis of the structural similarity network of protein chains.

We present a simple method for the analysis of large networks based on their graph spectral properties. One of the advantages of this method is that it uses a single numerical computation to identify subclusters in a connected graph, which can significantly simplify the complexity involved in analyzing large graphs. This is illustrated using a network of protein chains constructed on the basis of their structural similarities. The large-scale network properties and the cluster and subcluster organization of the protein chain network are presented. We summarize the results of structural and functional analyses of the nodes present in these clusters and elucidate the implications of structural similarity in the protein chain universe.

Cluster Analysis↗

PubMed2001

Color and spectral analysis of daylight in southern Europe.

We have analyzed the colorimetric and spectral characteristics of 2600 daylight spectra (global spectral irradiances on a horizontal surface) measured for all sky states during a 2-year period at Granada, Spain. We describe in detail the chromaticity coordinates, correlated color temperatures (CCT), luminous efficacies, and relative UV and IR contents of Granada daylight. The chromaticity coordinates of Granada daylight lie far above the CIE locus at high CCTs (>9,000 K), and a CCT of 5,700 K best typifies this daylight. Our principal-components analysis shows that Granada daylight spectra can be adequately represented by using six-dimensional linear models in the visible, whereas seven-dimensional models are required if we include the UV or near-IR. Yet on average only three-dimensional models are needed to reconstruct spectra that are colorimetrically indistinguishable from the original spectra.

Journal Article↗

PubMed2004

[Power spectral analysis on heart rate variability of hypoxaemia in fetal lambs].

To analyze the effect of hypoxaemia on heart rate variability (HRV) in fetal lambs by means of power spectrum, the intrauterine surgical operations were performed at 116-125 gestational days in 7 lambs. Arterial catheter was inserted in the fetal femoral artery and sent to aorta abdominalis, and blood pressure was recorded continually on tape recorder. The microspheres were injected via the arterial catheter to block the micrangium of placenta, thus making an animal model of fetal hypoxaemia. The fetal blood sample was drawn through the catheter for blood gas analysis. In terms of the heart beat variability power spectral density, there were four consistent components, namely very low (VL, 0.01-0.025 cycle/beat), low (L, 0.025-0.125 cycle/beat), middle (M, 0.125-0.2 cycle/beat), and high (H, 0.2-0.5 cycle/beat). Integrated peaks in the power spectrum were compared before and after administration of microsphere. The spectral power in the L frequency components was significantly increased (0.07 +/- 0.01 vs. 0.21 +/- 0.03, P<0.01), and the spectral power in the H frequency components was significantly reduced (0.53 +/- 0.1 vs. 0.27 +/- 0.05, P<0.05). There was no significant difference in M and VL. The times of microsphere injection were related to fetal blood pH (r=0.585, p<0.01), PCO2 (r=0.5, p<0.05) and PO2 (r=0.75, P<0.01). The results clearly demonstrate the association between change of power spectrum of heart rate variability and the effect of hypoxia of the fetus in labour.

Animals↗

PubMed1991

Assessment of early stage autonomic nerve dysfunction in diabetic subjects--application of power spectral analysis of heart rate variability.

To assess early stage autonomic nerve dysfunction, power spectral analyses were conducted on the consecutive RR records of healthy subjects (N/C, n = 21) and age-matched diabetic patients without neuropathy (DNN, n = 11), with peripheral neuropathy alone (DPN, n = 14), and with autonomic neuropathy (DAN, n = 13) during resting, deep breathing, and tilting. From the analyses, power spectral densities of low frequency (0.05-0.1 Hz) component (LF; msec2) and of high frequency (0.2-0.35 Hz) component (HF; msec2) were calculated as expressing sympathetic activity and parasympathetic activity, respectively. In N/C, LF and HF were 466 +/- 332 and 251 +/- 151, respectively. Deep breathing significantly (p less than 0.05 by paired t-test) increased HF to 403 +/- 305 and tilting increased LF significantly to 593 +/- 375. In diabetics as a group, both LF and HF were significantly smaller than those in N/C. DNN showed significantly smaller HFs than N/C. DPN showed a significantly smaller HF during deep breathing (135 +/- 93) and a significant smaller LF during tilting (122 +/- 119) than N/C. DAN showed a significantly smaller HF during deep breathing (49 +/- 49) and a significantly smaller LF during tilting (54 +/- 52) than DPN. Tilting increased LF significantly (p less than 0.001) in N/C but not in diabetics. Deep breathing increased HF significantly (p less than 0.001) in N/C and DNN. HF in diabetics highly correlated with known duration of diabetes. LF in diabetics did not correlate with known duration of diabetes nor level of hemoglobin A1c.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Ramipril Enhances Autonomic Control in Essential Hypertension: A Study Employing Spectral Analysis of Heart Rate Variation.

We estimated the effect of an angiotensin-converting enzyme inhibitor, ramipril, on the sympathetic and parasympathetic input to the sinoatrial node of hypertensive patients using spectral and time domain analysis of heart rate variation (HRV). The heart rate of patients with essential hypertension was recorded during spontaneous breathing at rest and during controlled deep breathing. The periodic HRV was quantified at low-frequency (0.025--0.075 Hz), mid-frequency (0.075--0.125 Hz) and high-frequency (0.15--0.40 Hz) bands. Ramipril changed the balance of autonomic nervous system assessed by spectra: the parasympathetic tone increased (p < 0.05) and the sympathetic tone decreased (p < 0.01). There was an inverse correlation between the decrease in diastolic blood pressure and increase in the mid-frequency HRV, which is connoted with resetting of the baroreceptor reflex by ramipril. Thus, ramipril treatment was associated with improved autonomic control of the circulatory system.

Journal Article↗

PubMed1999

Time-varying spectral analysis of heart rate and left ventricular pressure variability during balloon coronary occlusion in humans: a sympathoexicitatory response to myocardial ischemia.

OBJECTIVES: We assessed time-varying spectral components of heart rate and left ventricular (LV) pressure variability during coronary angioplasty to elucidate dynamic autonomic responses to transient myocardial ischemia. BACKGROUND: Sympathoexcitatory reflexes elicited by acute coronary occlusion are rarely addressed in the clinical settings because of a lack of technique to monitor transient changes in sympathetic activation. METHODS: RR interval and LV pressure and volume were serially recorded in 14 patients with effort angina during balloon coronary angioplasty. Wavelet analysis was applied for determination of nonstationary spectral components of RR interval and LV peak pressure variability. RESULTS: The wavelet analysis revealed that coronary occlusion provoked low-frequency (LF) fluctuations of RR interval (seven patients) and LV peak pressure (six patients) at 0.06 +/- 0.01 Hz, but not in the remaining patients. Following the balloon inflation, the LF component of RR interval began to increase after the onset of myocardial ischemia, peaked at about 80 s, and then declined in the late phase of inflation. Consequently, the ratio of low to high frequency component rose to be significantly greater in the LF augmentation group than in the no LF augmentation group in the middle phase of coronary occlusion. The patients with no LF augmentation had little evidence of myocardial ischemia as reflected by changes in ST segment and LV systolic function during coronary occlusion. CONCLUSIONS: The wavelet analysis of RR interval and LV pressure variability clearly showed a dynamic profile of spectral components in response to transient coronary artery occlusion. The resultant regional myocardial ischemia elicited a profound sympathoexcitatory response followed by a gradual suppression. This method provides a useful tool to gain a new insight into the nonstationary autonomic influence on the cardiovascular system.

Adult↗