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  • Electrogastrography  (7)
  • Biochemistry and Biotechnology  (4)
  • Electrogastrogram  (3)
  • GASTROINTESTINAL MOTILITY  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 27 (1999), S. 88-95 
    ISSN: 1573-9686
    Keywords: Electrogastrography ; Gastric motility ; Stomach ; Filter banks ; Neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Dysrhythmia in gastric myoelectrical activity has been frequently observed in patients with gastric motor disorders and gastrointestinal symptoms. The assessment of the regularity of gastric myoelectrical activity is of great clinical significance. The aim of this study was to develop an automated assessment method for the regularity of gastric myoelectrical activity from the surface electrogastrogram (EGG). The method proposed in this paper was based on the filter bank and neural network. First, the EGG signal was divided into frequency subbands using filter bank analysis. Second, a parameter called the subband energy ratio (SER) was computed for each subband signal. A multilayer perceptron neural network was then used to automatically classify the EGG signal into four categories: bradygastria, normal, tachygastria, and arrhythmia, using the SER as the input. The EGG recording was made using the standard method of electrogastrography by placing electrodes on the abdominal surface. The study was performed in 40 patients with various gastric motor disorders, ten healthy adults, and ten healthy children. The neural network was trained and tested using the EGG data obtained from the patients. The regularity of gastric myoelectrical activity was assessed based on the classification of the minute-by-minute EGG segments. Using the running spectral analysis method as a gold standard, the proposed automated method had an accuracy of 100% for the training set and 97% for the test set. It was concluded that the proposed method provides an accurate and automatic assessment of the regularity of gastric myoelectrical activity from the EGG. © 1999 Biomedical Engineering Society. PAC99: 8780-y, 8717-d, 0705Mh, 0270Hm
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; FUNCTIONAL DYSPEPSIA ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigateabnormalities in pediatric patients with functionaldyspepsia. Fifteen symptomatic pediatric patientsdiagnosed with functional dyspepsia and 17 aged-matchedhealthy controls were studied. Gastric myoelectricalactivity was recorded using surface electrogastrographyfor 1 hr in the fasting state and 1 hr after a testmeal. It was found that, in comparison with thecontrols, the children with functional dyspepsia had alower percentage of 2- to 4-cpm slow waves in bothfasting state (66.0 ± 4.7% vs 79.7 ± 3.1%,P 〈 0.07) and fed state (72.4 ± 5.4% vs 85.0± 2.9%, P 〈 0.04), and a significantly higherinstability of the dominant frequency in both fastingstate (0.50 ± 0.05 vs 0.31 ± 0.04, P 〈0.01) and fed state (0.39 ± 0.05 vs 0.25 ±0.03, P 〈 0.05). It was also found the postprandial increase inEGG dominant power in the patients was inverselycorrelated with the total symptom score (r = 0.63, P =0.03). It was concluded that abnormal gastricmyoelectrical activity may play a role in the pathogenesis ofpediatric functional dyspepsia.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 43 (1998), S. 1023-1030 
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING ; STOMACH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The efficiency and efficacy of theelectrogastrogram (EGG) involve a few practical factors,including recording length, sample size, and thecharacteristics of subjects. The aim of this study wasto investigate the effect of these factors on the accuracy ofEGG analysis. Gastric myoelectrical activity wasrecorded using electrogastrography in 24 subjects (ages22-91 years) for 1 hr in the fasting state and 2 hr after a test meal. Computerized spectralanalysis was performed to compute EGG parameters,including dominant frequency, dominant power, and thepercentage of 2-4 cycles per minute (cpm) slow waves. A parameter called misinterpretation was definedto investigate the effect of recording length. Theresults were as follows: (1) Using the recording lengthof 1 hr in each state as a gold standard, themisinterpretation for the recording length of 30 min was 27% forthe dominant frequency and 17% for the dominant power.When the recording length was reduced to 15 min, themisinterpretation increased to 61% for the dominant frequency and 38% for the dominant power. (2)With a sample size of 10 subjects and a recording lengthof 60 min, a statistically significant postprandialincrease was observed in the dominant frequency and power, and a trend in the postprandialincrease of the regularity of the EGG was noted. Whenthe sample size increased to 24 subjects, a significantpostprandial increase was found in all these parameters. (3) None of the EGG parameters exhibited anysignificant difference between the younger and oldersubjects or between men and women. In conclusion, arecording length of 30-60 min seems to be appropriate and produces reliable and predictable results.Age and gender do not affect any of the EGGparameters.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 43 (1998), S. 1678-1684 
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; FUNCTIONAL DYSPEPSIA ; GASTRIC EMPTYING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigate gastricmyoelectrical activity in patients with functionaldyspepsia. Thirteen healthy subjects and 14 patientswith functional dyspepsia participated in the study. The electrogastrogram (EGG) recording was madein each subject for 30 min in the fasting state and 120min after a standard test meal of 475 calories. Spectralanalysis methods were applied to derive quantitative EGG parameters. There was no difference in theEGG between the patients and controls in the fastingstate. However, abnormalities in the postprandial EGGwere found in the patients. The percentage of 2-4 cpmwaves was significantly lower (74.4 ± 4.0% vs85.7 ± 1.6%, P 〈 0.03) and the postprandialincrease in EGG dominant power was significantly less(–0.52 ± 0.92 dB vs 2.24 ± 0.88 dB,P 〈 0.03) in patients than in controls. It was alsofound that the percentage of postprandial 2-4 cpm wavescould be used to differentiate the patients withfunctional dyspepsia from the healthy controls with a specificity of 100% and a sensitivity of 43%. It was concluded that a subset of patients withfunctional dyspepsia have impaired gastric myoelectricalactivity in the fed state.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 28 (1990), S. 531-536 
    ISSN: 1741-0444
    Keywords: Autoregressive moving average modelling ; Electrogastrography ; Gastric motility ; Gastric slow wave ; Spectral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The recording of the human, gastric myoelectrical activity, by means of cutaneous electrodes is called electrogastrography (EGG). It provides a noninvasive method of studying electrogastric behaviour. The normal frequency of the gastric signal is about 0·05 Hz. However, sudden changes of its frequency have been observed and are generally considered to be related to gastric motility disorders. Thus, spectral analysis, especially online spectral analysis, can serve as a valuable tool for practical purposes. The paper presents a new method of the adaptive spectral analysis of cutaneous electrogastric signals using autoregressive moving average (ARMA) modelling. It is based on an adaptive ARMA filter and provides both time and frequency information of the signal. Its performance is investigated in comparison with the conventional FFT-based periodogram method. Its properties in tracking time-varying instantaneous frequencies are shown. Its applications to the running spectral analysis of cutaneous electrogastric signals are presented. The proposed adaptive ARMA spectral analysis method is easy to implement and is efficient in computations. The results presented in the paper show that this new method provides a better performance and is very useful for the online monitoring of cutaneous electrogastric signals.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 26 (1998), S. 859-869 
    ISSN: 1573-9686
    Keywords: Spectral analysis ; Matching pursuit ; Stomach ; Gastric motility ; Electrogastrography ; Evolutionary programming ; Signal analysis ; Electrogastrogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The electrogastrogram (EGG) is a surface measurement of gastric myoelectrical activity. The normal frequency of gastric myoelectrical activity in humans is 3 cycles/min. Abnormal frequencies in gastric myoelectrical activity have been found to be associated with functional disorders of the stomach. The aim of this article was, therefore, to develop new time-frequency analysis methods for the detection of gastric dysrhythmia from the EGG. A concept of overcomplete signal representation was used. Two algorithms were proposed for the optimization of the overcomplete signal representation. One was a fast algorithm of matching pursuit and the other was based on an evolutionary program. Computer simulations were performed to compare the performance of the proposed methods in comparison with existing time-frequency analysis methods. It was found that the proposed algorithms provide higher frequency resolution than the short time Fourier transform and Wigner-Ville distribution methods. The practical application of the developed methods to the EGG is also presented. It was concluded that these methods are well suited for the time-frequency analysis of the EGG and may also be applicable to the time-frequency analysis of other biomedical signals. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 0705Kf
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 533-549 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A periodic countercurrent whole beer process was developed for the recovery of novobiocin to eliminate the high cost of mycelium filtration and accompanying antibiotic losses in the filter cake. In such a process screened, but unfiltered, novobiocin fermentation beer is contacted with a special grade of an anionic-exchange resin in a series of specially designed, well mixed columns. Each column is fitted with a screen sized to retain resin within the column but allow the cells to press. Periodically the lead column is isolated from the column train, washed free of beer solids, and eluted. A freshly eluted column is placed in the trail position to allow countercurrent operation. The eluate is then processed to crystalline product.A mathematical model for the sorption of novobiocin was developed based on a suitable continuity equation and mass transfer and equilibrium relationships determined in the laboratory. Digital computations of this model correlated well with laboratory and pilot plant data, and predicted well the performance of the production units. This simulation has been in continued use to predict and reoptimize plant operation as process changes (such as improved beer titers, increased production rate, and the evaluation of superior ion-exchange resins) occurred or were anticipated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 271-292 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxygen transfer coefficients were evaluated for a 14-liter stirred tank fermentor equipped with an oxygen probe, employing elemental copper adsorbed on a weakly basic anion-exchange resin as a solid phase oxygen acceptor. The use of a solid phase oxygen acceptor allowed evaluation of mass transfer resistances associated with the solid phase, and the effect of an oxygen adsorbing solid phase on the overall oxygen transport system, portions of the oxygen transfer process that are neglected by the conventional sulfite oxidation method commonly employed. It was concluded from the data obtained that a transport pathway involving transfer of oxygen to particles present near the air-water interface was a significant oxygen transport pathway for the system studied. Oxygen probe measurements performed on the bulk liquid did not recognize this pathway, suggesting that data taken on biological systems by use of techniques involving oxygen concentration measurements in the bulk liquid may not give the true oxygen absorbing capacity of a system.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 4 (1962), S. 65-78 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mathematical models for the kinetics of 1-dehydrogenation of steroids by Septomyxa affinis are considered. A model providing for product inhibition fits experimental data best. Product inhibition was also demonstrated directly.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 151-155 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physiological activity of microorganisms in environments with low dissolved oxygen concentrations often differs from the metabolic activity of the same cells growing under fully aerobic or anaerobic conditions. This article describes a laboratory-scale system for the control of dissolved oxygen at low levels while maintaining other parameters, such as agitator speed, gas flowrate, position of sparger outlet, and temperature at fixed values. Thus, it is possible to attribute in dilute nonviscous fermentations all physiologic changes solely to changes in dissolved oxygen. Experiments were conducted with Azotobacter vinelandii and Escherichia coli. Critical oxygen concentrations for growth (that value of oxygen allowing growth at 97% of μmax) were measured as 0.35 ± 0.03 mg/L for A. vinelandii and 0.12 ± 0.03 mg/L for E. coli. These values are significantly different from the commonly quoted values for critical oxygen concentrations based on respiration rates. Because of the superior dissolved oxygen control system and an improved experimental protocol preventing CO2 limitation, we believe that the values reported in this work more closely represent reality.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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