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  • Biochemistry and Biotechnology  (4)
  • Physics  (4)
  • Cell & Developmental Biology  (3)
  • Electrogastrogram  (3)
  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 29 (1991), S. 351-357 
    ISSN: 1741-0444
    Keywords: Bioelectric potential ; Electrogastrogram ; Electromyography ; Gastric motility ; Slow wave ; Stomach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The gastric electric activity paces the contractions of the stomach and can be measured noninvasively using surface electrodes placed on the abdomen. In this paper, response of the gastric electric activity to water and a solid meal was investigated using surface electrodes. Applying an improved recording technique, power spectral analysis and statistical analysis methods, the gastric electric activity in preprandial, postwater and postprandial states was measured and analysed from ten healthy volunteers. To more convincingly show the effect of water and the solid meal on the gastric slow wave and gastric motility, simultaneous recordings of the cutaneous EGG and manometric activities in the stomach were performed in three gastroparetic patients. It was found that water does not induce contractions of the stomach, but the gastric slow wave amplitude increases (p〈0·05) and frequency decreases (p〈0·05). The solid meal results in an increase in both the amplitude (p〈0·01) and the frequency (p〈0·02) of the gastric slow wave. It appears that the postprandial EGG amplitude increases because of a combination of stomach contractions and gastric distension bringing the stomach closer to the recording electrodes. The slow wave frequency, however, correlates well with stomach contractions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 31 (1993), S. 60-67 
    ISSN: 1741-0444
    Keywords: Electrogastrogram ; Electrogastrography ; Gastric motility ; Intestinal motility ; Myoelectrical activity ; Spectral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 25-29 
    ISSN: 1040-452X
    Keywords: Hemizona assay (HZA) ; Rhesus monkey ; Oocyte ; Sperm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The hemizona assay (HZA) in Rhesus monkeys was employed to study the correlation of zona-binding ability with sperm motility or with naturally developing oocytes at various maturational stages. Oocytes from unstimulated ovaries were retrieved within 2 hr from monkeys sacrificed for vaccine production (in reproductive season, but with their menstrual cycles not determined). Oocytes were divided into four groups based on their morphological maturation: 1) Oocytes surrounded by more than one cumulus layer (MC); 2) Oocytes retaining intact germinal vesicle nuclei (GV); 3) Oocytes with germinal vesicle breakdown showing distinct perivitelline space (PVS); and 4) Oocytes extruding the first polar body (PBI). The mean numbers of sperm bound to hemizona for PB1, PVS, GV, and MC groups were 132.9 ± 12.0, 71.5 ± 10.1, 36.1 ± 4.0, and 20.1 ± 2.9 (Mean ± SE), respectively. The four groups showed significant differences from each other in sperm/egg binding ability (P 〈 0.01). The number of bound sperm significantly increased with oocyte maturation. The present study also showed that zona-binding ability was also affected by sperm motility. For sperm with 67.7% motility and sperm with 31.2% motility, the average numbers of bound sperm were 43.5 ± 2.2 and 25.3 ± 2.9 (Mean ± SE), respectively. There was significantly higher binding ability for sperm with higher motility (P 〈 0.01). The results suggest that: 1) The rhesus monkey model can serve as a very sensitive model for studying sperm/egg interaction by HZA; 2) Sperm motility positively correlated with sperm/egg binding; and 3) Sperm/egg binding ability increases with oocyte maturation. The binding ability is highest when oocytes matured to the PB1 stage, which is also the best opportunity for fertilization. This is strong evidence for the “zona maturation” hypothesis. © 1994 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 110-117 
    ISSN: 1040-452X
    Keywords: Rabbit embryos ; Hypertonic sucrose ; Micromanipulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rabbit zygotes and embryos were exposed to hypertonic sucrose in phosphate-buffered saline (SPBS). In experiment one, 144 zygotes shrank to 32-36% of their initial volume in 1.0 M SPBS within 30 min. Neither hypertonic treatment with 0.5 M or 1.0 M SPBS nor micropuncture of the zona pellucida after shrinkage affected embryo development into blastocysts in vitro (88%, 83%, and 82%, respectively), compared to that of the controls (93%, P 〉 .05). In experiment two, 252 two- to four-cell- and 177 morula-stage embryos were exposed to isotonic PBS control or 0.5 M, 1.0 M, or 1.5 M SPBS for 30, 60, 90, 120, and 150 min before transfer to PBS (290 mOsm). Embryo development was significantly reduced (P 〈 .05) when embryos were exposed in 0.5 M and 1.0 M SPBS for more than 60 min or in 1.5 M SPBS for more than 30 min. In experiment 3, morulae exposed for 60 min to 0.5 M or 1.0 M SPBS shrank to 37-39% or 32-35% of their initial volume and then expanded to 87-94% or 81-90% of their initial volume, respectively, after being returned to isotonic PBS for 60 min, but embryos in 1.5 M SPBS had erratic osmotic behavior. In experiment four, 192 two- to four-cell embryos exposed to 0.5 M SPBS for 0, 30, and 60 min before transfer to oviducts of recipients resulted in the production of 39%, 42% and 31% young, respectively (P 〉 .05). Exposure of embryos to 0.5 M sucrose for 60 min clearly does not compromise developmental potential and can simplify and speed up micromanipulation procedures.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 134 (1988), S. 189-199 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The growth of tissue culture TO-2 cells derived from the warm water fish Tilapia, the induction of thermotolerance, and protein synthesis profiles of these cells in response to temperature changes were examined. TO-2 cells can grow between 15 to 34°, with an optimal growth temperature of 31°. There is no apparent killing of the cells when the temperature is lowered to 4° for up to 3 days. Survival of TO-2 cells at 43° was studied after various preheat treatments: (1) acute heating at 40° for 15 min followed by 31° incubation, (2) chronic exposure at 37° for several hr, or (3) long-term thermal adaptation at 34°. The cells acquire thermotolerance from pre-exposure to 37° for as short as 6 hr. Preheating at 40° followed by incubation at 31° also induces thermotolerance against a subsequent 43° heat challenge. In addition, 34° thermal adapted cells are resistant to 43° heating. One- and two-dimensional gel electrophoresis of proteins after heat treatments show that three major heat shock proteins with molecular weights around 87, 70, and 27 kD are preferentially synthesized. The synthesis of two additional proteins with an isoelectric point of 6.9 and molecular weights of 60 and 44 kD are significantly enhanced in 34° thermal-adapted and 37° chronic heated cells, but not in cells subjected to an acute heat shock at either 40° or 43°. On the other hand, the 27 kD heat shock proteins are mainly present in the 43°, 40°, and 37° heat-shocked cells, but not in the 34° thermal-adapted cells.
    Additional Material: 12 Ill.
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