[Motilin - spectrum and analysis of effects].
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Animals↗
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Muscular tenderness evaluated by surface EMG frequency analysis of isometric contractions.
Myoelectric power spectrum analysis was used to compare muscular activity in the masseter and anterior temporal muscles between patients with tender masseter muscles and healthy controls. Surface EMG was recorded for 28 patients and nine controls while they were biting on a bite force transducer during a period of 10-15 s up to maximal effort (100% MVC). The mean frequency (MF) was calculated as a single estimate of the myoelectric power spectrum. Regression analyses of MF's for the masseter muscles versus the force level 0-60% MVC showed significantly less steep slopes of regression for the patients compared interindividually with the controls. As regards the anterior temporal muscles there was no significant difference between groups. One explanation for the difference in MF's for the masseter muscles between patients and controls is that the patients suffered an inhibition or difficulty in recruiting motor units. Different firing rate properties for motor units at high force levels (60-100% MVC) could be one reason for a significantly smaller decrease in MF for the patients' elevator muscles than for the controls.
Adult↗
New lipid formulation of amphotericin B: spectral and microscopic analysis.
UV-visible and dichroic spectrum analysis and electron microscopy have been used to characterize a new amphotericin B (AmB) lipid formulation prepared by a solvent displacement process. The composition was dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylglycerol (DMPG) in molar ratio DMPC/DMPG/AmB 7:3:5, a similar composition to that of Abelcet. Although the latter has a "ribbon-like" structure, our process gave a thin disc-like structure. Analysis of circular dichroism (CD) and UV-visible spectra of formulations containing different percentages of AmB revealed that a minimum of AmB self-association was observed with 7:3:5 molar ratio. Varying the lipid ratio (DMPC/DMPG) while maintaining the fixed ratio of AmB yielded similar results when DMPC was in excess (DMPC/DMPG from 10:0 to 6:4). However, when the ratio was between 5:5 to 3:7, AmB self-aggregation increased. For compositions rich in DMPG (2:8 and 0:10), inversion of the CD spectrum was observed. The influence of the lipid composition on the morphology of the complex was also evident in electron microscopy. DMPC/DMPG/AmB (10:0:5) gave large unfracturable lamellae. The presence of DMPG shortened the lamellae, which often appeared as disc-like structures. AmB content, the presence of DMPG and the preparation process all contribute to generating these original structures with particular CD spectra.
Amphotericin B↗
Analysis of the electroencephalogram in growing calves by use of power spectrum and cross correlation.
OBJECTIVE: To determine postnatal maturation of findings in the electroencephalogram (EEG) of calves and estimate the degree of electrophysiologic activity, using power spectrum and cross-correlation analyses of the EEG. ANIMALS: 10 clinically normal Japanese Black calves ranging in age from 1 to 10 weeks. PROCEDURE: EEG were recorded at various stages of consciousness. Power spectrum and cross-correlation analyses were applied to a relaxed state EEG. RESULTS: After the second week of age, rhythmic waves with frequencies of 6 to 9 Hz (alpha rhythm-like pattern) appeared in the EEG during the relaxed state, and were recorded in the occipital and vertex areas; duration of appearance was < 30 seconds. By use of power spectrum analysis, power distribution of the 7.5- to 10-Hz frequency band in the occipital area significantly increased after the sixth week. The highest frequency (18 to 30 Hz) band increased in the frontal and occipital areas after the seventh week. Normalized cross-correlation coefficients at 0 time shift were > 0.6 throughout the experimental period. The normalized cross-correlation coefficients obtained from caudal interhemispheric sites increased after the second week, and were significantly greater than those in rostral sites. CONCLUSIONS AND CLINICAL RELEVANCE: Developmental changes in the EEG of calves during the first 10 weeks could be characterized by appearance of the alpha rhythm-like pattern and increase of the power distributions of the 7.5- to 10-Hz and 18- to 30-Hz frequency bands, which might be a useful indicator for estimating brain activity in young calves and as standard data for evaluating abnormal brain activity in calves.
Aging↗
31P NMR Bayesian spectral analysis of rat brain in vivo.
Bayesian spectrum analysis for parameter estimation is a rigorous statistical (non-Fourier-based) method. Herein the Bayesian quadrature NMR model is introduced and applied to analysis of 31P NMR time domain data from in vivo rat brain. Immunity to both the brain spectrum "baseline hump" and the phase twist is demonstrated.
Animals↗
INFRARED STUDY OF THE OH GROUPS IN EXPANDED KAOLINITE.
Expansion of kaolinite with potassium acetate and with hydrazine followed by deuteration, shifts the absorption frequency at 3695 cm(-1) to lower values, but does not aflect the intensity of the 3620-cm(-1) absorption band. The band at 3695 cm(-1) is correlated predominantly to inner-surface hydroxyls with the dipole at right angles to the basal plane and the band at 3620 cm(-1) is related to inner hydroxyls with the dipole inclined toward empty octahedral sites.
Hydroxyl Radical↗
[Prosthetic application of digital processing of speech signals].
The purpose of this study was to investigate the acoustic characteristics of the nine sounds, /sa/, /si/, /ka/, /ki/, /ci/, /hi/ and /ri/, which were reported affected by wearing complete denture, through the acoustic analysis of speech samples uttered by nine male subjects. Spectrum analysis was done within the frequency range of 0 to 10 KHz according to the auto-correlation method of liner predictive coding (LPC) analysis. Results 1. The consonant parts of /sa/, /si/, /ci/ and /hi/ wee characterized by the spectrum envelopes and their peak frequencies derived from the LPC analysis of order 5. 2. The consonant parts of /ka/ and /ki/ were characterized by their first spectrum peak frequencies derived from the LPC analysis of order 10. 3. The consonant part of /ri/ was characterized by the spectrum envelope derived from the LPC analysis of order 24, and the sound waveform. 4. The frequencies of the formants (F 1, F 2, F 3) of the following vowels /i/ were derived from the LPC analysis of order 24. They were influenced by individual variations and preceding consonants. 5. Each sound had its own characteristics in the duration of the consonant and of the closure interval and the time from the end of preceding vowel to the beginning of the following vowel.
Analog-Digital Conversion↗
Automatic removal of high-amplitude artefacts from single-channel electroencephalograms.
In this work, we present a method to extract high-amplitude artefacts from single channel electroencephalogram (EEG) signals. The method is called local singular spectrum analysis (local SSA). It is based on a principal component analysis (PCA) applied to clusters of the multidimensional signals obtained after embedding the signals in their time-delayed coordinates. The decomposition of the multidimensional signals in each cluster is achieved by relating the largest eigenvalues with the large amplitude artefact component of the embedded signal. Then by reverting the clustering and embedding processes, the high-amplitude artefact can be extracted. Subtracting it from the original signal a corrected EEG signal results. The algorithm is applied to segments of real EEG recordings containing paroxysmal epileptiform activity contaminated by large EOG artefacts. We will show that the method can be applied also in parallel to correct all channels that present high-amplitude artefacts like ocular movement interferences or high-amplitude low frequency baseline drifts. The extracted artefacts as well as the corrected EEG will be presented.
Algorithms↗
Quantitative analysis of EEG changes during hypothermia.
Power spectrum analysis of 4-channel EEGs was performed during cooling and rewarming using cardiopulmonary bypass. During rewarming, linear correlations of temperature with the total power and with peak power frequency of the high-frequency band were observed in a significant number of cases (85%, P less than 0.0001 and 76%, P less than 0.002, respectively). The magnitude of these changes were 1,215 microV2/degrees C (+/- 150 [SEM] ) and 0.39 Hz/degrees C (+/- 0.04 [SEM] ). Two other descriptors of the EEG power spectrum (the spectral edge and average frequencies) did not correlate with the temperature changes in a significant number of cases. Changes during cooling followed a similar trend but were more variable, presumably because of other physiologic changes associated with the start of bypass. Knowledge of the relationship of the EEG to temperature should permit distinguishing EEG changes secondary to hypothermia from those caused by acute hypoxia.
Brain↗
EMG power spectrum, turns-amplitude analysis and motor unit potential duration in neuromuscular disorders.
The diagnostic value of power spectrum analysis of the needle EMG pattern at a force of 30% of maximum was compared to that of turns-amplitude analysis and to that of manual measurements of motor unit potential (MUP) duration in the brachial biceps muscle of 20 patients with myopathy and 11 patients with neurogenic disorders. In myopathy the power spectrum analysis had the same diagnostic value as the turns-amplitude analysis and MUP duration measurements and the 3 methods supplemented each other. In patients with neurogenic disorders the diagnostic value of the power spectrum analysis as well as that of the turns-amplitude analysis were lesser than that of MUP duration measurement. In diseased muscles the amount of high frequencies increased with increasing ratio of turns to mean amplitude while there was no relation between the power spectrum and the MUP changes. The results suggest that the power spectrum analysis of EMG can be used as a diagnostic tool in patients with neuromuscular disorders.
Adolescent↗
Power spectrum and turns analysis of EMG at different voluntary efforts in normal subjects.
The power spectrum and the number of turns of the needle EMG were analysed at different degrees of voluntary contraction in the brachial biceps muscle or the first dorsal interosseus muscle of 23 normal subjects. During a stepwise increase in force HF/LF amplitude ratio showed a slight decrease with increasing force from 10% to 80% maximal voluntary contraction (MVC). At moderate to high force (i.e., 30-80% MVC) the HF/LF amplitude ratio increased with increasing turns at the individual site of the muscle. This relation probably reflects that both the HF/LF amplitude ratio and the number of turns are influenced by the degree of summation in the electrical activity. There was no correlation between HF/LF amplitude ratio and mean amplitude. The finding of a relation between HF/LF amplitude ratio and turns suggests that power spectrum analysis may differentiate between controls and patients with neuromuscular diseases.
Adolescent↗
Analysis of drug-induced effect patterns to link structure and side effects of medicines.
The high failure rate of experimental medicines in clinical trials accentuates inefficiencies of current drug discovery processes caused by a lack of tools for translating the information exchange between protein and organ system networks. Recently, we reported that biological activity spectra (biospectra), derived from in vitro protein binding assays, provide a mechanism for assessing a molecule's capacity to modulate the function of protein-network components. Herein we describe the translation of adverse effect data derived from 1,045 prescription drug labels into effect spectra and show their utility for diagnosing drug-induced effects of medicines. In addition, notwithstanding the limitation imposed by the quality of drug label information, we show that biospectrum analysis, in concert with effect spectrum analysis, provides an alignment between preclinical and clinical drug-induced effects. The identification of this alignment provides a mechanism for forecasting clinical effect profiles of medicines.
Computer Simulation↗
Statistical handling of EEG-data.
This contribution focusses on the treatment of EEG data as time series. More emphasis is placed on spontaneous activity than on event-related potentials. Smoothing techniques are discussed, both for the nonparametric estimation of regression functions and of densities. Some new promising methods are presented. The fundamentals of time series analysis, and in particular of spectrum analysis, are reviewed. For the difficult area of parameterization of EEG time series, we compare desirable characteristica of parameters with the methods already in use.
Electroencephalography↗
Execution and observation of bringing a fruit to the mouth affect syllable pronunciation.
Kinematic analysis of lip and voice spectrum analysis were used to assess the influence of both execution and observation of arm-mouth-related actions on speech production. In experiments 1 and 2 participants brought either a cherry or an apple to their mouth and either pronounced the syllable BA (experiment 1) or emitted a nonspeech-related vocalization (experiment 2). In the other three experiments participants observed arm actions performed by the experimenter and pronounced the syllable BA. In experiment 3, they observed the action of bringing the cherry or apple to the mouth. In experiments 4 and 5, they observed a pantomime of the same action performed by the experimenter with his own arm (experiment 4) or with a nonbiological arm (experiment 5). The results showed that the formant 2 of the vowel 'a' increased when participants executed the bringing-to-the-mouth act with the apple or observed its execution or pantomime with the experimenter's arm (experiments 1, 3 and 4). In contrast, no modification in the vowel formants was found during a nonspeech-related vocalization (experiment 2) and during observation of an action with a nonbiological arm (experiment 5). Finally, the opening of the lips was larger when the participant brought the apple rather than the cherry to the mouth and pronounced BA (experiment 1). Taken together, the results of the present study suggest that the execution and observation of the bringing-to-the-mouth action activate a mouth articulation posture (probably due to the act of food manipulation with the mouth) which selectively influences speech production. They support the idea that the system involved in speech production shares and may derive from the neural substrate which is involved in the control of arm-mouth interactions and, in general, of arm actions.
Adult↗
Gastric myoelectrical activity in neonates of different gestational ages by means of electrogastrography.
PURPOSE: to describe the patterns of the gastric myoelectrical activity, pre-and postprandially, in clinically stable neonates of different gestational ages, during their first two weeks of life by means of Electrogastrography. PATIENTS AND METHODS: Electrogastrography was recorded in forty-five clinically stable neonates of different gestational ages (group I: 15 neonates of > 37 weeks, group II: 15 premature neonates of 32-37 weeks; Group III: 15 premature neonates of 28-31 weeks) receiving intermittent enteral feedings during their first two weeks of life. Electrogastrography recordings were performed for 1 hour pre-and postprandially. The Electrogastrography signal was recorded using the portable MicroDigitrapper Electrogastrography recording device and after motion artifacts were deleted, the remaining Electrogastrography data were submitted to quantitative analysis based on the "Running Spectrum Analysis". RESULTS: The percentages of normogastria, pre-and postprandially were greater than the percentages of gastric dysrythmias in all three studied groups. Furthermore, all neonates had the mean values of the Electrogastrography dominant frequency predominantly within the normogastria range, in both periods analyzed. There were no significant differences in the relative change of the Electrogastrography dominant power among the groups. CONCLUSION: This study demonstrates that the Electrogastrography patterns are similar between premature and full term neonates during the pre-and postprandial periods. The results of this study also indicate that the gastric myoelectrical activity in premature and full term neonates is immature, as compared to that described for older neonates, children and adults.
Electromyography↗
Importance of spectral analysis indices for assessment of the grade of stenosis of the arteria carotis interna.
The authors evaluated the indices of Doppler power frequency spectrum analysis in 106 patients with suspected extracranial carotid occlusive disease. Blackshear, Norrving and Knox indices appeared to be most sensitive for identification of the grade of stenosis of the arteria carotis interna. Sensitivity of ultrasound examination was correlated with angiography. The highest sensitivity (90%), specificity (100%), and overal accuracy (97%) were recorded in the group of hemodynamic significances disturbances of ACI, i.e. high stenoses with occlusions. Calculation of indices of spectral analysis has been performed routinely in all non-invasive ultrasound examinations of carotid arteries by means of Echoflow method.
Carotid Artery Thrombosis↗
Simplified estimation of calcium in biological materials by flame photometry.
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Calcium↗
Quantitative analysis of carotid artery Doppler spectral waveforms: diagnostic value of parameters.
Continuous-wave ultrasonic Doppler recordings made at the carotid bifurcation have been processed by spectrum analysis and off-line microprocessor software. Data reduction algorithms were defined and tested prior to incorporation in an integrated, hard-wired device. Subsequent analysis of waveforms in real-time provided measures of peak and mode frequencies and degree of spectral broadening. Correlation of results with 123 angiographically visualized internal carotid arteries showed that peak and mode frequencies generally increased with degree of stenosis while the systolic window decreased. Ratios of peak and mode frequencies in the proximal to the distal internal carotid artery and the systolic window at the distal internal carotid artery were retrospectively found to have diagnostic value with a combination of these three parameters providing the best overall accuracy.
Adult↗