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PubMed2001

[Spectral analysis of the heart rate variability in various types of the left heart ventricle remodelling in patients with hypertension].

Autonomic cardiac regulation in different types (normal, concentric, and eccentric geometries) of the left ventricle (LV) was evaluated in 86 hypertensive patients. LV structure and function were evaluated by echocardiography). To calculate heart rate variability (HRV), 512 RR intervals were measured in supine rest and passive tilt. Power spectral analysis with fast Furrier transform was used to derive low- and high-frequency power spectra and the sympathovagal index (SVI). In the normal LV geometry group, there was a good response to the tilt test, by causing a 3-fold increase in SVI while in the two LV hypertrophy groups, the index was virtually unchanged or even decreased. The normal LV geometry group patients showed a positive correlation between low-frequency power and the relative LV wall thickness (RLVWT) while the two LV hypertrophy groups did increases in RLVWT and LV myocardial mass, which were associated with a reduction in HRV. In conclusion, HRV is significantly reduced in essential hypertension and is also closely connected with cardiac structure and function. Patients with normal LV geometry showed a preserved response to the tilt test. LVH produces significant autonomic regulatory disturbances possibly due to the lower sensitivity of cardiac adrenoceptors independently of the pattern of LV hypertrophy.

Adult↗
PubMed1997

Broadband spectral analysis of blood pressure and heart rate variability in very elderly subjects.

Systolic blood pressure (SBP) variability is increased and R-R interval variability is reduced in the elderly. Little is known, however, about how SBP and R-R interval variabilities change in the very elderly. More important, however, it is not known which frequency components of SBP and R-R interval variability are affected significantly. We addressed this issue in subjects older than 70 years by broadband spectral analysis, which allows all variability components from the lowest to the highest frequency to be considered. In 20 very elderly normotensive subjects (mean +/- SD age, 78.1 +/- 6.8 years) and 28 normotensive adult subjects (36.1 +/- 7.1 years), noninvasive finger blood pressure and R-R intervals were recorded continuously for 30 minutes in the supine position and 15 minutes in the upright position. SBP and R-R interval power spectral densities were computed over the entire frequency region between 0.005 Hz (0.007 Hz in the upright position) and 0.5 Hz. Overall SBP variability (SD) was greater and overall R-R interval variability was less in very old subjects than in adult subjects. All spectral R-R interval powers were reduced significantly in very elderly individuals. The spectral SBP powers were greater in the very elderly group than in the adult group only in the very-low-frequency range (<0.04 Hz). This was true in the supine and the standing positions. With subjects in the standing position, the shape of the broadband spectra differed in the very old and adult subjects because in the former group the increase in SBP and R-R interval power around 0.1 Hz that was seen in the latter was blunted. Therefore, in very elderly subjects a reduction in overall R-R interval variability is accounted for by a reduction in all of its frequency components. The accompanying increase in overall BP variability, however, results from a nonhomogeneous behavior of its frequency components, which consists of an increase in the very low frequency and a concomitant reduction in the higher frequency powers. The mechanisms responsible for these changes may be complex, but at least they may in part reflect the baroreflex impairment and autonomic dysfunction that characterize aging.

Adult↗
PubMed1988

Callosal and association neurons in the cortical space: a spectral analysis approach.

The tangential distributions of callosal neurons of area 5 projecting homotopically to the contralateral hemisphere and of association neurons of areas 4 and 6 projecting to ipsilateral area 5 were determined in the macaque monkey by using neuroanatomical methods based on the retrograde transport of horseradish peroxidase. Both distributions were studied qualitatively through 2-dimensional reconstructions of the cortical areas of origin and quantitatively through a spectral analysis. This approach facilitated the characterization of the spatial periodicities contained in these distributions revealing that, in area 5, callosal neurons were organized in bands of various shapes and width; these bands were composed of more discrete clusters of cells. In the frontal lobe, association neurons projecting to ipsilateral area 5 were arranged similarly. This study suggests that a common principle underlies the tangential organization of both callosal and association projecting cells in different cortical areas and emphasizes a basic similarity of interhemispheric and intrahemispheric connections.

Animals↗
PubMed2001

Locating nucleobase lesions within DNA sequences by MALDI-TOF mass spectral analysis of exonuclease ladders.

The location of carcinogen-modified nucleobases (DNA adducts) within DNA sequences is a critical factor affecting their promutagenic properties and persistence in DNA. We now report the use of controlled exonuclease digestion followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to directly map modified nucleobases within DNA. The DNA sequence is determined by mass spectral analysis of the DNA ladders produced by sequential removal of nucleotides with either 5'-->3' or 3'-->5' exonuclease. Individual mononucleotides are identified from the mass differences between adjacent peaks corresponding to singly charged ions of the products of enzymatic cleavage. Chemically modified nucleotides are detected and identified by their molecular weight. The resolution and mass accuracy of this approach are sufficient to identify nucleobase modifications differing in mass by as little as 2 Da. No a priori information on the DNA sequence or adduct type is required. We demonstrate the general applicability of this method by sequencing synthetic oligonucleotides containing a range of nucleobase modifications: O(6)-methylguanine, peroxynitrite-induced oxidative lesions (oxaluric acid, oxazolone, cyanuric acid), and the N(2)-guanine adduct of (+,-)-7r,8t-dihydroxy-9t,10t-epoxy-7,8,9,10-tetrahydribenzo[a]pyrene. Sequence information is also obtained for DNA oligodeoxynucleotides containing O(6)-pyridyloxobutylguanine, despite the ability of this lesion to block 3'-phosphodiesterase.

DNA Adducts↗
PubMed1986

Sound spectral analysis of voice-transmitted sound.

There is a change in voice-generated sound heard over an area of pulmonary consolidation described as the "e" to "a" change. The lung may act as a low pass filter with properties that are changed by consolidation. We studied 5 patients with pneumonia. Using an electronic stethoscope, we recorded the voice-generated sounds "e" and "9-9-9." Sound spectral analysis using the fast Fourier transformation technique was used to characterize the frequency spectrum of the recorded sound. This technique allowed us to evaluate the filter properties of the normal and consolidated lung. We found that the normal lung allowed transmission of sound as high as 250 Hz with a gradual cutoff by 400 Hz. The consolidated lung allowed transmission of sound of a higher frequency; however, there was no significant transmission of sound with a frequency higher than 1,000 Hz.

Auscultation↗
PubMed1994

Power spectral analysis of electroencephalographic desynchronization induced by cocaine in the rat.

Whereas it is well-known that cocaine induces EEG desynchronization and behavioral excitation in animals and human subjects, the detailed effect of cocaine on EEG activity remains to be fully elucidated. This communication reports our attempts in quantifying the effect of cocaine on EEG signals recorded from the somatosensory cortex of adult male Sprague-Dawley rats under chloral hydrate anesthesia (400 mg/kg i.p.). Continuous, on-line and real-time power spectral analysis revealed that i.v. administration of two doses of cocaine (1.5 or 3.0 mg/kg) dose-dependently induced EEG desynchronization, as indicated by a decrease in the root mean square and an increase in the mean power frequency values. More interestingly, whereas both doses of cocaine promoted a reduction in the alpha (8-13 Hz), theta (4-8 Hz) and delta (1-4 Hz) spectral components, the beta band (13-32 Hz) underwent differential alterations. The lower dose of cocaine elicited a transient increase, followed by a decrease in the power of the beta band. A prolonged increase in the power of the beta band, on the other hand, was observed after the higher dose of cocaine. These results suggest that subtle changes in the individual EEG spectral components, which are dose-dependent, may underlie the EEG desynchronization induced by cocaine.

Animals↗
PubMed2006

Spectral analysis of skin blood flowmotion before and after exercise in healthy trained and in sedentary subjects.

Cutaneous blood flowmotion (CBF) can contribute to a reduction in the resistance in skin microvascular networks. The increase of CBF during exercise can improve the capacity of skin microvascular networks to transport and eliminate heat. In order to verify if the physical training could increase the skin blood flowmotion during exercise, we performed spectral analysis of cutaneous forearm laser Doppler signal, before and after acute maximal exercise in 15 healthy trained subjects (TS) and in 15 control sedentary subjects (SS). Within the total spectrum of 0.009 - 2.3 Hz, five frequency intervals of CBF were analysed: 0.009 - 0.02 Hz (endothelial activity), 0.02 - 0.06 Hz (sympathetic activity), 0.06 - 0.2 Hz (vascular myogenic activity), 0.2 - 0.6 Hz (respiratory activity), and 0.6 - 2.3 Hz (heart activity). In basal conditions, no difference between TS and SS was observed in the cutaneous blood perfusion (CBP), expressed in conventional perfusion units (PU), and in the mean value of CBF total spectrum power density (PD), measured in PU/Hz, while the absolute PD of the endothelial and myogenic CBF components was significantly higher (p < 0.05) in TS (0.69 +/- 0.62 PU/Hz and 0.47 +/- 0.43 PU/Hz, respectively) than in SS (0.29 +/- 0.16 PU/Hz and 0.23 +/- 0.16 PU/Hz, respectively). In both TS and SS, acute exercise induced a significant increase of CBP mean value (30.91 +/- 20.28 PU, p < 0.0005 and 16.45 +/- 7.02 PU, p < 0.0005; respectively) and of CBF total spectrum PD (6.65 +/- 4.13 Hz/PU, p < 0.001 and 4.17 +/- 1.86 Hz/PU, p < 0.05; respectively), with a significant difference of these two parameters between the two groups (p < 0.05). After exercise, CBF components regarding endothelial and myogenic activities maintained a higher PD mean value in TS in respect to SS (1.69 +/- 1.34 PU/Hz and 1.59 +/- 0.93 versus 0.91 +/- 0.44 and 0.98 +/- 0.48 PU/Hz respectively, p < 0.05). These findings suggest that physical training is associated with the increase of CBF and particularly on its endothelial and myogenic components in response to exercise. This can favour a greater reduction of resistance in skin microvascular networks during exercise and consequently an increase of its capacity to transport and eliminate heat.

Adult↗
PubMed1994

In vitro sound spectral analysis of prosthetic heart valves by mock circulatory system.

A comparative study was made of the sounds produced by normal prosthetic valves (St. Jude Medical, Bjork-Shiley, polymer) with those produced by the same valves but having simulated thrombosis at the stent, hinge, or strut. Comparisons of the closing sound were made for the power frequency spectra associated with individual valves. We used periodogram approach to obtain the spectral characteristics of the valve prostheses. The closing sound of the abnormal mechanical valves displayed lower apparent peak frequency. But the abnormal polymer valve produced higher apparent peak frequency. The results showed that frequency spectra gave information pertinent to the simulated malfunction. Sound spectral analysis is believed to be a simple and a good diagnostic tool for detection of prosthetic valve malfunction. Also it seemed to be superior to other methods such as phonocardiography and echocardiography.

Fourier Analysis↗
PubMed1998

Power spectral analysis of heart rate variability by autoregressive modelling and fast Fourier transform: a comparative study.

OBJECTIVE: To compare the results from autoregressive modelling (ARM) and from fast Fourier transform (FFT), the most commonly used methods for the analysis of short-term heart rate variability in the frequency domain. METHODS & RESULTS: RR interval and respiratory activity were recorded in the supine and standing positions under standardized laboratory conditions in a population-based sample of 614 subjects. The low-(LF) and high-frequency (HF) components of heart rate variability were identified by power spectral analysis, by use of FFT, with application of two sets of frequency ranges, and by ARM; LF and HF power were expressed in both normalized (%) and absolute units (ms2). The RR interval, its variance and the HF power decreased from the supine to the standing position (P < 0.001). The LF power increased on standing when expressed in normalized units, but decreased in absolute units, whereas the LF-to-HF ratio increased (P < 0.001). On the low side of the spectrum, FFT slightly overestimated the LF component obtained with ARM, when the predefined frequency range was 0.05-0.15 Hz (P < 0.001); the underestimation of LF in the frequency range 0.07-0.14 Hz was more pronounced, particularly in the erect position (P < 0.001). Both FFT methods overestimated (P < 0.001) the ARM HF component, more so for the 0.15-0.50 Hz range than for the 0.14-0.35 Hz range. Finally, we observed considerable within-subject differences between methods, which were estimated by calculation of the limits of agreement. CONCLUSIONS: Different methods for spectral decomposition of short-term heart rate variability yield similar qualitative results, but the quantitative results differ between ARM and FFT, and within the FFT method according to the selected frequency range.

Adult↗
PubMed1999

Heart rate and blood pressure power spectral analysis during calcium channel blocker induced hypotension.

PURPOSE: To observe heart rate (HRV) and blood pressure variability (BPV) as indices of neurocirculatory responses to induced hypotension with diltiazem and/or nicardipine for hip surgery. METHODS: Thirty-six ASA I-II patients received diltiazem (group D, n = 12), nicardipine (group N, n = 12) or combination of diltiazem/nicardipine (group DN, n = 12). The intensity of HRV and BPV, was determined by spectral analysis of HRV and BPV before anesthesia (T0), just before induced hypotension (T1), and at 10 and 30 min after the start of induced hypotension (T2 and T3, respectively). The logarithmic HRV and BPV were integrated: sympathetic and parasympathetic mediated low frequency area (0.06-0.1 Hz, LF), parasympathetic related high frequency area (0.15-0.4 Hz, HF) and total frequency area (0.01-0.4 Hz). Blood loss was assessed by weighing gauzes and measuring suction. RESULTS: Group DN had less blood loss (466 +/- 46 ml, mean +/- SEM) than group D (733 +/- 100 ml, P < 0.05). Diltiazem (11.4 +/- 0.9 microg x kg(-1) x min(-1)), and combination of diltiazem (0.25 +/- 0.01 mg x kg(-1)) and nicardipine (5.9 +/- 0.9 microg x kg(-1) x min(-1)) decreased LF-HRV at T2 and T3 (P < 0.05 vs T0 and T1), while nicardipine (8.1 +/- 0.8 microg x kg(-1) x min(-1)) showed increase in LF-HRV at T2 (P < 0.05 vs T1). HF-HRV unchanged through hypotension except for a decrease in group N at T3 (P < 0.05 vs T1). There were no increases in HF-BPV, and LF-BPV, except for a diltiazem induced decrease in LF-BPV at T3 (P < 0.05 vs T0 and T1). CONCLUSION: Group D and group DN can be used for deliberate hypotension without an increase in sympathetically mediated LF-HRV.

Adult↗
PubMed2002

Effects of clothing pressure caused by different types of brassieres on autonomic nervous system activity evaluated by heart rate variability power spectral analysis.

The present study was designed to investigate the effects of clothing skin pressures exerted by two different types of brassieres (a conventional higher skin-pressured brassiere and a newly devised low skin-pressured brassiere) on the autonomic nervous system (ANS) activity. Six healthy young women (22.8 +/- 1.4 yrs.) with regular menstrual cycles participated in this study. The ANS activities were assessed by means of heart rate variability power spectral analysis. The skin pressures exerted by the brassieres were measured with an air-pack type contact surface pressure sensor at five different points. The total amount of clothing pressure, and the pressures at the center and the side regions of the brassieres were significantly greater in the high than in the low skin-pressured brassiere (Total 9816.1 +/- 269.0 vs. 6436.8 +/- 252.4 Pa, P < 0.01; Center 2212.1 +/- 336.3 vs. 353.8 +/- 85.8 Pa, P < 0.01; Side 2556.8 +/- 316.1 vs. 1747.2 +/- 199.2 Pa, P < 0.05). Concerning the ANS activity, the Total power, and the very low frequency (VLF) and the high frequency (HF) components were significantly decreased in the high skin-pressured brassiere than those in the low skin-pressured brassiere (Total 531.6 +/- 57.3 vs. 770.5 +/- 54.2 ms2, P < 0.01; VLF 60.7 +/- 14.6 vs. 179.2 +/- 38.1 ms2, P < 0.05; HF 209.5 +/- 33.2 vs. 283.2 +/- 61.5 ms2, P < 0.01). Our data indicate that the higher clothing pressures exerted by a conventional brassiere have a significant negative impact on the ANS activity, which is predominantly attributable to the significant decrease in the parasympathetic as well as the thermoregulatory sympathetic nerve activities. Since the ANS activity plays an important role in modulating the internal environment in the human body, excess clothing pressures caused by constricting types of foundation garments on the body would consequently undermine women's health.

Adult↗
PubMed1994

Protein sequence and structure relationship ARMA spectral analysis: application to membrane proteins.

If it is assumed that the primary sequence determines the three-dimensional folded structure of a protein, then the regular folding patterns, such as alpha-helix, beta-sheet, and other ordered patterns in the three-dimensional structure must correspond to the periodic distribution of the physical properties of the amino acids along the primary sequence. An AutoRegressive Moving Average (ARMA) model method of spectral analysis is applied to analyze protein sequences represented by the hydrophobicity of their amino acids. The results for several membrane proteins of known structures indicate that the periodic distribution of hydrophobicity of the primary sequence is closely related to the regular folding patterns in a protein's three-dimensional structure. We also applied the method to the transmembrane regions of acetylcholine receptor alpha subunit and Shaker potassium channel for which no atomic resolution structure is available. This work is an extension of our analysis of globular proteins by a similar method.

Amino Acid Sequence↗
PubMed1988

Mass spectral analysis of some derivatives and in vitro metabolites of steviol, the aglycone of the natural sweeteners, stevioside, rebaudioside A, and rubusoside.

Steviol (ent-13-hydroxykaur-16-en-19-oic acid), the aglycone of various plant-derived glycoside sweeteners consumed by human populations, is known to be mutagenic toward Salmonella tymphimurium strain TM677 when metabolically activated using a 9000 x g supernatant fraction derived from the liver of Aroclor 1254-pretreated rats. Mass spectral analysis of this diterpenoid and some analogs revealed characteristic patterns reflecting differential stereochemistry at the C/D rings and variations in the nature of the substituents present. Such information has been used to help identify several in vitro metabolites of steviol in conditions known to produce a mutagenic response, when analyzed by gas chromatography/mass spectrometry. The major pathways of such steviol mammalian metabolism proved to be allylic oxidation and epoxidation. 15-Oxosteviol, a product of oxidation of the major steviol metabolite, 15alpha-hydroxysteviol, was found to be a direct-acting mutagen [corrected].

Biotransformation↗
PubMed2001

Absence of sleep EEG markers in fatal familial insomnia healthy carriers: a spectral analysis study.

OBJECTIVES: Fatal familial insomnia (FFI) is linked to a mutation at codon 178 (C178) of the prion protein gene (PRNP). FFI is pathologically characterized by selective atrophy of the anteroventral and mediodorsal thalamic nuclei and clinically by loss of sleep, dysautonomia and motor signs. A key early polysomnographic sign of the disease onset is the loss of sleep spindling (sigma activity, SA). In FFI the loss of SA leads to the spectral representation of a sudden slow wave activity (SWA) increase from an awake state, the reaching of a stable plateau without oscillations, followed by abrupt fall down to REM sleep. We evaluated the presence of differences in the spectral sleep EEG pattern in FFI relatives carriers (C178(pos)) or non-carriers (C178(neg)) of the C178 mutation. METHODS: Seventeen healthy relatives of FFI patients, 8 carriers of the C178 FFI mutation in a preclinical condition and 9 non carriers, underwent two-night polysomnography. The absolute and relative EEG power of the 4 main bands (delta: SWA, 0.5-4.0 Hz; theta: TB, 4.5-8 Hz; alpha: AB, 8.5-12 Hz; sigma: SA, 12.5-16 Hz) has been studied for the total sleep time, the period of delta increase after sleep onset, and the period of delta plateau. Multiple regression has been applied to investigate relations between the power of the bands studied and 3 parameters: age, the gender of the subjects and the C178 genotype. RESULTS: Our study could not show evidence of differences in the sleep EEG composition between carriers and non-carriers of the C178 FFI mutation. CONCLUSIONS: The spectral analysis techniques we used were not able to disclose sleep EEG markers linked to the FFI C178(pos) in the preclinical condition. Key sleep EEG alteration become evident only at the clinical onset of the disease.

Adult↗
PubMed2000

Spectral analysis of electroencephalogram during sleep-related apneas in pre-term and term born infants in the first weeks of life.

OBJECTIVES: A correlation between sudden infant death syndrome (SIDS) and apnea has been discussed in a variety of studies. We analyzed polysomnographic data in 51 infants and investigated correlations between the manifestation of apneas and changes in EEG pattern. METHODS: Measurements were performed by means of the commercial polysomnographic device 'ALICE III'. Spectral analysis of certain parts of the registered EEG was performed. RESULTS: During apnea a reduction of the EEG amplitude was seen. The extent of the decrease differed slightly between the frequency bands. CONCLUSIONS: According to the widespread agreement that a lower voltage of electrical brain activity is a fundamental sign of waking up, we hypothesize that the observed change might be an immature type of arousal reaction.

Brain↗
PubMed2004

Rapid characterization of amyloid-beta side-chain oxidation by tandem mass spectrometry and the scoring algorithm for spectral analysis.

PURPOSE: Amyloid-beta (Abeta) is a self-aggregating protein found in senile plaques in Alzheimer's disease (AD) brain and is thought to play a major role in the disease process. Oxidative stress may be a predominant cause of the formation of these Abeta aggregates. This study aims at identifying possible sites of copper-catalyzed oxidation of Abeta1-40 using liquid chromatography tandem mass spectrometry (LC/MS/MS) and scoring algorithm for spectral analysis (SALSA). Traditionally, identification of post-translational modifications by tandem mass spectrometric analysis requires users to inspect manually thousands of MS/MS spectra, which can be a tedious and time-consuming process. With the use of SALSA, users can automatically search for post-translational modifications based on the spacing of the m/z values associated with the ion series of an amino acid sequence. METHODS: Abeta1-40 was subjected to copper-catalyzed oxidative stress. LC/MS/MS and SALSA analyses were used to determine the sites of post-translational modification within the tryptic fragments. RESULTS: Oxidation was found to occur preferentially at the histidine residues Hisl3 and Hisl4 and at the methionine residue (Met35) of Abeta1-40. CONCLUSIONS: The combination of LC/MS/MS and SALSA searches could dramatically improve the efficiency and accuracy of determining the specific sites of oxidation of in vitro, copper-oxidized Abeta1-40 as well as other oxidized proteins.

Algorithms↗
PubMed2005

Autonomic function in elderly uremics studied by spectral analysis of heart rate.

BACKGROUND: Aging determines an altered response of the autonomic nervous system (ANS) to physiologic stresses. A widespread autonomic damage is well recognized in chronic renal failure (CRF). METHODS: We studied 30 CRF patients, aged 19 to 85 years, who were on bicarbonate hemodialysis. Surface electrocardiogram was recorded on lying and 65 degrees head-up tilt standing positions. A dedicated software, using an autoregressive modeling technique, allowed to calculate power spectral analysis (PSA) of heart rate variability, assessing a low-frequency band in the range 0.03 to 0.15 Hz, and a high-frequency band in the range 0.15 to 0.33 Hz. Low-frequency and high-frequency components are regarded, but not invariably, as specific markers of sympathetic and parasympathetic activities, respectively, and the low-frequency/high frequency ratio as an index of sympathovagal balance. RESULTS: In normal controls, low-frequency band value and low-frequency/high-frequency ratio on standing resulted significantly reduced in the group older than 65 years when compared with those younger than 65 years; an opposite finding was seen in high-frequency band value on standing. In uremic patients, low-frequency band on lying resulted significantly lower only in elderly uremics when compared with elderly controls, whereas low-frequency band on standing was significantly lower in elderly than in younger uremics. Regression analysis showed a significant inverse relationship between aging and most low-frequency band values, especially in uremics. The comparison of linear regression models confirmed that a sympathetic autonomic derangement is greatly present in older uremics, in particular after 50 years of age. CONCLUSION: Our data support assertion that combination of aging and CRF increases the chance of autonomic derangement being present.

Adult↗
PubMed1979

[Possibility of the spectral analysis of heterogeneous biological systems. The determination of the mycelium concentration of Actinomyces aureofaciens, a producer of tetracycline, cultured on a medium with corn meal].

A possibility of using spectroscopy of attenuated total reflection in the IR region for analysis of the heterogenic system consisting of the microorganisms and plant cells is discussed. The method of spectroscopy is proposed for estimating the mycelium concentration of Act. aureofaciens producing tetracycline in the presence of corn meal in the medium. The experimental data confirming this possibility are presented. The peculiar properties of the spectral analysis under these particular conditions are discussed. It is supposed that the method may be used for analysis of heterogenous systems including other microorganisms.

Culture Media↗