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PubMedDate not supplied

First postoperative week activity patterns and recovery in women after coronary artery bypass surgery.

The purpose of this study was to examine the relationship between activity-rest patterns and recovery in women during the first week after coronary artery bypass surgery (CABS). Twenty-five women wore wrist actigraphs to measure activity objectively throughout the first postoperative week. The Sickness Impact Profile (SIP) and length of postoperative hospital stay (LOS) were used as measures of recovery. Analysis of the activity data indicated that 21 (84%) of the participants had statistically significant positive linear trends in activity. Spectrum analysis indicated that 18 participants had periods that could be defined as circadian, 1 had a shorter period, and 6 had longer periods. After controlling for the effect of preoperative functional status, the period and linear trend of activity explained 28% of the variance in the SIP score at 1 week and 33% of the variance in length of stay. Positive linear trends in activity and circadian activity periods were related to better functioning and shorter length of stay.

Activity Cycles↗
PubMed1997

Autonomic dysfunction in systemic sclerosis: time and frequency domain 24 hour heart rate variability analysis.

To evaluate the autonomic nervous control of the heart in patients with systemic sclerosis (SSc), spontaneous heart rate variability was investigated by means of time-domain and spectrum analysis of 24 h ECG ambulatory recordings in 30 SSc patients (four males, aged 45.2 +/- 9 yr, mean +/- S.D., range 27-60) and 30 age-matched healthy subjects. A significantly higher heart rate (P < 0.01) and lower circadian and spectral indices of heart rate variability (P < 0.01) were observed in SSc patients, compared with controls. A predictive value of age (P = 0.002), tachycardia (P = 0.002), circadian heart rate variability (P = 0.0025) and spectral power values (P = 0.005) for patient mortality was found. Moreover, the relative risk of death was higher (P = 0.05) in older subjects with circulating anti-Scl70. These abnormalities, detectable by a feasible, non-invasive diagnostic approach, indicate the presence of autonomic cardiac neuropathy in SSc patients.

Activities of Daily Living↗
PubMed1993

Twenty-four-hour power spectral analysis by maximum entropy method of blood pressure in primary hyperaldosteronism.

In the present study we estimated the periodic profiles and variance structure of systolic blood pressure, diastolic blood pressure, heart rate and mean arterial pressure by using an autoregressive model of power spectrum, Maximum Entropy Method (MEM) in 8 patients with primary aldosteronism, during long-term therapy with nicardipine slow release. The four blood pressure variables were measured at 30-min intervals, using a noninvasive device (Spacelabs 90202) in 8 hypertensive patients of whom 6 with idiopathic aldosteronism (IHA) and 2 with dexamethasone-suppressible aldosteronism (DSH), before and after 24 weeks of 80 mg nicardipine daily. Blood pressure data were processed by MEM and spectral profiles were obtained. During nicardipine therapy all patients showed a significant decrease of 24-h ambulatory blood pressure values (p < 0.01). Before therapy, spectrum analysis by MEM indicated the presence of high frequency distribution of peaks for SBP, DBP, MAP and HR. The MEM power spectrum showed an increase in amplitude of sharp peaks of systolic, diastolic, MAP and heart rate in all patients after therapy at 24 h corresponding to the circadian rhythm blood pressure. Furthermore, the trend of these variables synchronized themselves in the same period after 24 weeks of nicardipine therapy, with spectral patterns of blood pressure similar to those of normotensive subjects. This chronobiologic approach, by Maximum Entropy Method, may be used as an alternative statistical analysis to search for possible rhythmic behavior of ambulatory blood pressure data before and after pharmacological treatment in secondary hypertensive patients.

Activity Cycles↗
PubMed1993

A system approach to pharmacodynamics. Input-effect control system analysis of central nervous system effect of alfentanil.

Virtually all biological variables, including those affected by drugs, are subject to adaptive self regulation. In the description of the pharmacodynamics (PD) of drugs, it may be necessary to consider the endogenous control system (ECS) as an integral part of the PD. A PDECS model based on system analysis principles is presented and tested on PD data for alfentanil considering the central nervous system activity quantified by a power spectrum analysis of the electroencephalogram. The model was tested in terms of a proposed relative prediction performance criterion that measures the accuracy of future predictions relative to how well the model describes (fits) the past effect data. A mean value of 80% (standard deviation, 28) for relative prediction performance indicates that the model performs well when challenged by the complex multiple infusion scheme used in the test. The overshoot phenomenon observed in the data is considered by the PDECS model as a ECS-based tolerance phenomenon. The proposed development of tolerance is modeled as a variable gain in the ECS processing that influences the effect. Although the development and loss of tolerance is determined by a single rate constant in the tolerance model, the rates of increase and decrease of tolerance may be substantially different. Contrary to other PD tolerance models, the proposed PDECS approach models the tolerance in terms of an effect deviation from an ECS set point. The intrinsic (no tolerance) effect of the drug is isolated in terms of an open loop (no feedback) effect.

Alfentanil↗
PubMed1977

Identification of beta,beta-turns and unordered conformations in polypeptide chains by vacuum ultraviolet circular dichroism.

Different conformations of polypeptides were characterized by measurements of the circular dichroism (CD) extended into the vacuum ultraviolet region. (i) The linear beta-pleated sheet structure was characterized in a broad ultraviolet region down to 165 nm by examination of copolypeptides composed of alternating hydrophobic and hydrophilic amino-acid residues, e.g., poly(Lys-Leu-Lys-Leu). A short-wavelength intense band was found at about 169 nm, which is characteristic of beta-pleated sheet conformation. (ii) The beta-turns were experimentally measured using poly(Ala(2)-Gly(2)) in a broad spectral region down to 165 nm with accuracy. The observed CD spectrum is in excellent qualitative agreement with the theoretical curve calculated by Woody for the beta-turns of type II and/or I of Venkatachalam. The similarity in shape between the theoretical curve and the observed CD spectra suggests a dominance of beta-turn segments in the poly(Ala(2)-Gly(2)) structure. The presence of beta-turns in poly(Ala(2)-Gly(2)) is also in agreement with the characterization of this polypeptide by solid state methods (electron microscopy and x-ray diffraction). The CD spectrum of beta-turns is characterized by a very intense band at 207.5 nm and strong negative bands at 191 and 169 nm. Copolypeptides such as poly(Ala(2)-Gly(3)) and poly(Ala(3)-Gly(3)) yielded a similar type of CD spectrum, analysis of which indicates that a large fraction of their residues is contained in beta-turn regions. (iii) The CD spectrum of the unordered chain of these alternating copolypeptides in salt-free solution is observed in the vacuum ultraviolet region.

Circular Dichroism↗
PubMed1995

Blood pressure analysis.

Arterial blood pressure is influenced by sleep-related breathing disorders. As cardiovascular consequences can be diagnosed by an accurate recording and analysis of blood pressure, new recording methodologies and an approach to analysis are presented here. Invasive continuous blood pressure recording is the common reference for all methodologies. As blood pressure varies rapidly in parallel with sleep-related breathing disorders it is indispensible to record blood pressure continuously. To introduce non-invasive methodology the Finapres system was used during sleep studies; a validation study showed severe limitations. This study was followed by the validation of an improved system called Portapres, which is portable, has two finger cuffs and a hydrostatic height compensation. Analysis of continuous blood pressure in patients with sleep apnoea is carried out to detect mechanisms which influence the cardiovascular risk. Spectrum analysis of systolic blood pressure showed two different major oscillations present in patients with obstructive sleep apnoea. One oscillation (<0.06 Hz) occurs in parallel with each apnoeic episode and the other oscillation (0.2-0.4 Hz) occurs in parallel with the obstructive efforts during each apnoea and in parallel with respiration during periods of snoring. These two oscillations were so specific that the use of non-invasive continuous blood pressure recording allowed an estimation of the extent of underlying breathing disorders, and assessment of cardiovascular risk in a patient with obstructive apnoea in terms of hypertension and on the basis of ambulatory monitoring.

Journal Article↗
PubMed2000

Perioperative monitoring with the electroencephalogram and the bispectral index monitor.

Recent clinical studies using the bispectral index monitor to predict movement, measure the level of consciousness, and reduce the cost of anesthesia have renewed interest in the use of a monitor to assess the effects of anesthetics on the brain. In 1937, Gibbs described electroencephalographic changes during the administration of general anesthetics. Artusio in 1954 used unprocessed electroencephalographic waveform analysis during an ether anesthetic to study the first stage of anesthesia. Some of the first automated electroencephalographic processors used power spectrum analysis for assessment of the patient's brain activity during surgery and anesthesia. The purpose of this article is to provide a historical perspective of the development and use of the processed electroencephalographic monitor. This article also describes studies of clinical usefulness of the bispectral index monitoring device in anesthesia practice today.

Anesthesia, General↗
PubMed1995

Spectroscopic diagnosis of esophageal cancer: new classification model, improved measurement system.

Laser-induced fluorescence spectroscopy was used to measure fluorescence emission of normal and malignant tissue during endoscopy in patients with esophageal cancer and volunteers with normal esophagus. The spectroscopy system consisted of a nitrogen-pumped dye-laser tuned at 410 nm for excitation source, an optical multichannel analyzer for spectrum analysis, and a fiberoptic probe designed for both the delivery of excitation light and the collection of fluorescence emission from tissue. The fluorescence lineshape of each spectrum was determined and sampled at 15-nm intervals from 430 to 716 nm. A calibration set of spectra from normal and malignant spectra was selected. Using stepwise discriminate analysis, significant wavelengths that separated normal from malignant spectra were selected. The intensities at these wavelengths were used to formulate a classification model using linear discriminate analysis. The model was then used to classify additional tissue spectra from 26 malignant and 108 normal sites into either normal or malignant spectra. A sensitivity of 100% and specificity of 98% were obtained.

Algorithms↗
PubMed1990

Sequential spectral analysis of 24-hour blood pressure and pulse interval in humans.

Blood pressure and pulse interval are characterized not only by erratic variations but also by rhythmic fluctuations at low-, mid-, and high-frequency (0.025-0.07, 0.07-0.14, and 0.14-0.35 Hz, respectively). However, information on these phenomena has largely been derived from analysis of short-term recordings taken in standardized laboratory conditions. In seven normotensive and 10 untreated mild essential hypertensive subjects, power spectrum analysis was performed on the intra-arterial blood pressure and pulse interval signal collected over a 24-hour period using the fast Fourier transform algorithm and splitting the recording into contiguous segments of 256 beats. About 70% of the segments were suitable for the analysis; the segments excluded for a nonstationary signal amounted to only 30%. All powers were characterized by a high segment-to-segment variability, but in each subject the mid- and high-frequency powers of diastolic blood pressure and the mid-frequency power of systolic blood pressure were markedly reduced during the night as compared with the daytime period, whereas the opposite occurred for the low- and high-frequency powers of the pulse interval. Over the 24-hour period, mid- and high-frequency powers of blood pressure were positively correlated to each other, but both accounted for less than 25% of the 24-hour blood pressure variance. No difference between mean normalized power values of normotensive and hypertensive subjects was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1978

Neuromuscular blocking agents and spontaneous sympathetic activity.

The action of neuromuscular blocking agents on the spontaneous sympathetic activity has been quantitated. "On line" spectrum analysis has been applied to the action potential of pre- and post ganglionic nerves of the coeliac plexus. The activity, the frequency spectrum and their changes after the injection of clinical and high doses of decamethonium, D-tubocurarine, succinylcholine, gallamine and pancuronium are determined.

Action Potentials↗
PubMed1989

[Fundamental study on morphological imaging and functional analysis of change in bone].

In this study a comparison was made in determining morphometrical changes in bone utilizing standard dental radiographic technique and dental xeroradiography. In terms of energy intensity, results demonstrated that spectrum analysis is consistent with visual evaluation and useful as a technique for objective evaluation of changes in bone. Changes in trabecular patterns were experimentally reproduced using quantitative determinations of calcium and phosphate. The relation between radiographic changes in bone associated with decalcification and variations in bone mineral content actually eluted from a particular site were examined. Changes in radiographic contrast and morphometry are important as indicators in radiographic interpretation, and their effects on visual evaluation of the radiograms were also studied. Also evaluated was the usefulness of the technique of using a spectrum analyzer to physically analyze the energy intensity distribution changes in bone. The findings in this study indicate that changes in both contrast and morphometry provide indicators for radiographic interpretation in DF, and that changes in contrast play a more dominant role with increasing bone density. It was also demonstrated that radiographic interpretation in DXR depends on morphometrical changes rather than changes in contrast as a major indicator. Since there was no difference in the efficiency of visual detection between DF and DXR, the use of DXR appears more beneficial in view of lower radiation exposure. When the detectability was 80%, actual variations in bone mineral content ranged from 24% to 38%. Thus, it may be possible to visually identify much smaller variations in bone mineral content on radiograms by using additional indicators such as pattern recognition and marginal changes of the lesion.

Alveolar Bone Loss↗
PubMed1995

Deamination of 3-hydroxykynurenine in bovine lenses: a possible mechanism of cataract formation in general.

BACKGROUND: 3-Hydroxykynurenine, a metabolite of tryptophan, acts as UV filter in the human lens. In this study, we looked for this substance and its metabolites in young and old bovine lenses, because of their possible role in the formation of cataract. METHODS: The substances were detected by HPLC analysis. The fluorescent substance formed from 3-hydroxykynurenine was characterized by thin-layer chromatography followed by reaction with ninhydrin, UV and fluorescence spectrum analysis, and atom bombardment for molecular mass determination. The kynurenine aminotransferase activity was determined by the method of Tobes. RESULTS: 3-Hydroxykynurenine was detected at concentrations of 0.07, 0.19, and 1.14 micrograms/g of tissue in the bovine iris/ciliary body, retina, and transparent bovine lenses respectively. 3-Hydroxykynurenine was deaminated in old bovine eyes but not in calf eyes. In old eyes, kynurenine aminotransferase activity was 2.7, 3.5, and 9.6 mumol/g of tissue per h in retina, iris/ciliary body, and lens respectively. CONCLUSION: The deamination of 3-hydroxykynurenine resulted in the formation of a fluorescent substance which was identified as oxidized xanthurenic acid. This substance, accumulating in the bovine lens and interacting with lens proteins, could induce cataract formation.

Animals↗
PubMed1997

Pulmonary arterial impedance analysis by the use of the oscillated assist flow.

Pulmonary arterial impedance is an important and interesting characteristic that can be used to evaluate the physiological properties of the pulmonary vessel. However, power spectrum analysis of the pulmonary artery pressure and flow pattern have suggested that peak power in the relatively high frequency range (> 10 Hz) is significantly low; thus, we cannot analyze the vessel properties in the high frequency range. In this study, we used the newly developed vibrating flow pump (VFP), which can generate oscillated blood flow with a relatively high frequency (10-50 Hz) for right heart bypass, to evaluate the pulmonary arterial impedance pattern in the high frequency range. Acute animal experiments of the right heart bypass from the right atrium to the pulmonary artery using 6 healthy adult goats were performed. The flow pattern and pressure of the pulmonary artery, electrocardiograms (ECGs), and arterial and right atrial pressures were continuously monitored during the experiments. Spectral analysis of the hemodynamic parameters using the fast Fourier transform (FFT) method was performed to evaluate the spectral properties. The coherence function, transfer function, and phase patterns were calculated to analyze the impedance pattern in the relatively high frequency area. Previously, various investigators had tried to analyze the impedance patterns of the pulmonary artery; however, they could not analyze the impedance patterns over 10 Hz because the spectral patterns of the pulmonary flow do not have high power at high frequencies. These physiological analyses may be useful in designing the optimal pulmonary circulation.

Animals↗
PubMed1993

Spectral analysis of heart rate variability in the sepsis syndrome.

Sympathetic and parasympathetic activity was evaluated on 39 occasions in 17 patients with the sepsis syndrome, by measurement of the variation in resting heart rate using frequency spectrum analysis. Heart rate was recorded by electrocardiography and respiratory rate by impedance plethysmography. The sepsis syndrome was established on the basis of established clinical and physiological criteria. Subjects were studied, whenever possible, during the period of sepsis and during recovery. Spectral density of the beat-to-beat heart rate was measured within the low frequency band 0.04 to 0.10 Hz (low frequency power, LFP) modulated by sympathetic and parasympathetic activity, and within a 0.12 Hz band width at the respiratory frequency mode (respiratory frequency power, RFP) modulated by parasympathetic activity. Results were expressed as the total variability (total area beneath the power spectrum), as the spectral components normalized to the total power (LFPn, RFPn) or as the ratio of LFP/RFP. During the sepsis syndrome, total heart rate variability and the sympathetically mediated component, LFPn were significantly lower than during the following recovery phase (ANOVA, p < 0.0001, p < 0.01 respectively). Both APACHE II (Acute Physiological and Chronic Health Evaluation) and TISS (Therapeutic Intervention Scoring System) scores showed an inverse correlation with total heart rate variability, logLFP, LFPn and the LFP/RFP ratio (p < 0.002 to 0.0001). Sympathetically mediated heart rate variability was significantly lower during the sepsis syndrome and was inversely proportional to disease severity.

Adult↗
PubMed2006

Software studies for germanium detectors data analysis.

Efficiency calibrations of multiple high-purity germanium (HPGe) detectors are being maintained at the National Institute of Standards and Technology (NIST). Four generally available software packages for HPGe detector gamma-ray spectrum analysis, including the one currently used at NIST, were tested on spectra collected from two HPGe detectors at different source-to-detector distances and using point sources and ampoules as calibration geometries. The resulting efficiency curves were inter-compared.

Algorithms↗
PubMed2001

Image-spectroscopy--I. The advantages of increased spectral information for compositional EFTEM analysis.

The acquisition of a series of energy-filtered TEM images over the energy-loss range of interest creates a three-dimensional data set comprising both spatial and spectral information. Such an image-series contains energy-loss information not available with conventional two- or three-window methods, allowing standard techniques for quantitative EELS analysis to be applied to extracted 'image-spectra'. The increase in spectral information enables improved ionisation edge background extrapolation and interactive image-spectrum analysis to be performed. In this paper, the many advantages of the image-spectroscopy approach are outlined by reference to an example of elemental segregation in an AlZnMgCu alloy.

Journal Article↗
PubMed2001

Innocuous mechanical stimulation of the neck and alterations in heart-rate variability in healthy young adults.

The present study examined the effects of cervical spinal manipulation, a widely applied form of physical therapy, which involves innocuous mechanical stimulation, on heart rate and heart-rate variability, in a cohort of healthy young adults. Using a cross-over treatment design, with a one-week washout period and, in contrast to a sham procedure, the authentic manipulation produced significant alterations in both heart rate and measures of heart-rate variability calculated from power spectrum analysis. In particular, there was an increase in the ratio of low-frequency (LF)-to-high-frequency (HF) components of the power spectrum of heart-rate variability, which may reflect a shift in balance between sympathetic and parasympathetic output to the heart.

Adult↗
PubMed1988

Spectrum factors relevant to phonetogram measurement.

Phonetograms showing the sound-pressure level (SPL) in loudest and softest possible phonation are frequently used in some voice clinics as an aid for describing the status of voice function. Spectrum analysis of the vowel /a/ produced by ten females and ten males with healthy, untrained voices revealed that the fundamental was mostly the strongest spectrum partial in soft phonation while the loudest partial in loud phonation was generally an overtone. Also, the first-formant frequency was generally lower in soft than in loud phonation. Measuring SPL in dB(A) rather than in dB lowered the phonetogram contour for soft phonation, an effect increasing with decreasing fundamental frequency. SPL measurements on a group of 22 females with healthy voices showed that the vowel /a/ gave higher SPL values than other vowels in loud phonation. The effect of using dB rather the dB(A) was great but similar for all vowels in soft phonation while, in loud phonation, the effect was small, particularly for /a/. In dB, the effect of using different vowels amounts to about +/- 5 dB, approximately. Interpretation of a phonetogram in terms of voice physiology is facilitated if SPL is given in dB and if a vowel with a high first-formant frequency is used.

Adult↗