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  • Cell & Developmental Biology  (3)
  • Electrical impedance  (3)
  • BHK-21/C13 cells in monolayer culture  (2)
  • Finite elements  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 13 (1975), S. 182-186 
    ISSN: 1741-0444
    Keywords: Blood resistivity ; Electrical impedance ; Cardiac output
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Pour pouvoir appliquer la méthode de l'impédance électrique pour la mesure du débit sanguin chez des patients à l'hémodialyse où l'on peut rencontrer use vaste gamme d'hématocrites, il est nécessaire d'avoir des connaissances sur la relation entre la résistivité et l'hématocrite du sang. Une relation linéaire optimale a été déterminée pour le sang humain à 37°C et 100 kHz sur la gamme d'hématocrites de 14 à 45%.
    Abstract: Zusammenfassung Um die elektrische Impedanzmethode zur Messung der Herzleistung bei Patienten anwenden zu können, die durch Blutidialyse behandelt werden, wo ein breiterer Bereich von Blutzentrifugenwerten angetroffen werden kann, ist die Kenntnis des Verhältnisses zwischen dem spezifischen Widerstand des Blutes und dem Blutzentrifugenwert enforderlich. Es wurde ein Verhältnis nach der linearen Methode der kleisten Quadrate für das menschliche Blut bei 37°C und 100 kHz über einen Blutzentrifugenwertbereich von 14 bis 45% bestimmt.
    Notes: Abstract In order to be able to employ the electrical-impedance method for the measurement of cardiac output in patients on haemodialysis where a wide range of haematocrits may be encountered, a knowledge of the relationship between the resistivity and haematocrit of blood is required. A linear least-squares relationship has been determined for human blood at 37°C and 100 kHz over the haematocrit range from 14 to 45%
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 13 (1975), S. 307-308 
    ISSN: 1741-0444
    Keywords: Residual urine volume ; Electrical impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 13 (1975), S. 187-191 
    ISSN: 1741-0444
    Keywords: Cardiac output ; Electrical impedance ; Radiocardiogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Vingt paires simultanées de valeurs de débit sanguin en provenance de patients ne présentant pas d'anormalités valvulaires ont été obtenues par la méthode radio-isotopique et la méthode d'impédance életrique deKubicek et al (1966). Si on a admis pour la résistité sanguine de chaque patient une valeur-type de 150Ω, la valeur d'impédance moyenne de débit sanguin était supérieure de 14·5% par rappórt à la valeur radio-isotopique moyenne. Dans la présente étude, les hématocrites des patients s'échelonnaient de 20 à 48%. En faisant passer la valeur de résistivité appropriée pour chaque patient dans l'équation de volume d'apoplexie de Kubicek à partir des données de Geddes et de Sadler (1973), on obtient une valeur d'impédance moyenne inférieure de 10·3% par rapport à la valeur isotopique moyenne. L'utilisation de nos données de résistivité mesurées ont amené la valeur d'impédance moyenne de débit sanguin à 21·5% au-dessous de la valeur isotopique moyenne. Le coefficient de corrélation entre les techniques à impédance et les techniques à isotopes était de 0·61 pour la valeur-type de résistivité de 150Ωcm. Ce coefficient a été amené à 0.87 par l'utilisation des données de résistivité de Geddes et Sadler (1973), contre 0·88 avec nos données.
    Abstract: Zusammenfassung Zwanzig simultane Herzleistungspaarwerte von Patienten ohne Herzklappen-Anomalitäten wurden durch das Radioisotopenverfahren und das elektrische Impedanzverfahren von Kubicek und anderen (1966) erhalten. Wenn ein Standardwert von 150Ωcm für den spezifischen Widerstand des Blutes eines jeden Patienten angenommen wurde, betrug der Durchschnittswert für die Impedanz-herzleistung 14·5%, was im Vergleich zum durchschnittlichen Radioisotopenwert hoch ist. In dieser Untersuchung lagen die Blutzentrifugenwerte der Patienten zwischen 20 and 48%. Wenn man den entsprechenden spezifischen Widerstandswert für jeden Patienten in die Hubvolumengleichung von Kubicek aus den Daten nach Geddes und Sadler (1973) eisetzt, ist der mittlere Impedanzwert von 10·3% im Vergleich zum mittleren Isotopenwert niedrig. Bei Anwendung unserer gemessenen Widerstandsdaten lag der mittlere Herzleistungs-impedanzwert um 21·5% unter dem mittleren Isotopenwert. Der Korrelationskoeffizient zwischen Impedanz-und Isotopen-technik betrug 0·61 für den Standard-Widerstandswert von 150Ωcm. Bei Verwendung der Widerstandsdaten nach Geddes und Sadler (1973) betrug der Korrelationskoeffizient 0·87 mit unseren Daten 0·88.
    Notes: Abstract Twenty simultaneous pairs of cardiac output values from patients who did not have valvular abnormalities were obtained by the radioisotope method and the electrical-impedance method of Kubicek et al. (1966). If a standard value of 150Ω-cm was assumed for the resistivity of each patient's blood, the mean value for the impedance cardiac output was 14·5% high compared with the mean radioisotope value. In this study the patient's haematocrits ranged from 20 to 48%. Inserting the appropriate value of the resistivity for each patient into the stroke volume equation of Kubicek from the data of Geddes and Sadler (1973) made the mean impedance value 10·3% low compared with the mean isotope value. The use of our measured resistivity data made the mean impedance cardiac output value 21·5% lower than the mean isotope value. The correlation coefficient between the impedance and isotope techniques was 0·61 for the standard value of resistivity of 150Ω-cm. Using the resistivity data of Geddes and Sadler (1973) the correlation became 0·87, and with our data it was 0·88.
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We investigated the actions of human placental lactogen (HPL) and human growth hormone (HGH) on [3H]thymidine incorporation and the release of immunoassyable somatomedin-C (SM-C) by isolated myoblasts, dermal fibroblasts, and costal cartilage explants taken from human fetuses, at 11-21 weeks of gestation. The incorporation of [3H] thymidine by myoblasts and fibroblasts was significantly increased after incubation for 20 hr or 44 hr, and cell number after incubation for 7 days, in the presence of 50-250 ng/ml HPL. Incubation with HPL did not increase [3H]thymidine incorporation into cartilage explants, whereas incubation with HGH failed to enhance the uptake of this isotope by any of the tissues. Following extraction with acid-ethanol, culture medium conditioned by exposure to myoblasts or fibroblasts for 44 hr, and to cartilage explants for 7 days, contained radioimmunoassayable SMC. Myoblast-conditioned medium contained significantly more SM-C [1,609 ± 953 mU/mg cell protein (mean ± SD) n = 10] than did that conditioned by fibroblasts (637 ± 323; n = 5; P 〈 0.02). In 1 week of culture, cartilage explants released 4.1 ± 1.1 mU/mg wet weight (n = 7). The release of immunoassayable SM-C from cultured cells was significantly increased in the presence of 250 ng/ml HPL in five of eight experiments with myoblasts and two of four experiments with fibroblasts. Neither fibroblasts or myoblasts showed increased SM-C release following exposure to HGH.The results suggest that HPL, but not HGH, is growth-promoting for some human fetal tissues in vitro and that this action is mediated, at least in part, by an increased release of somatomedins.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 128 (1986), S. 322-328 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We investigated the influence of transforming growth factor-β (TGF-β) on DNA synthesis in human fetal fibroblasts, as measured by the incorporation of [3H] thymidine and cell replication. In serum-free medium, without additional peptide growth factors, TGF-β had no action on thymidine incorporation. However, in the presence of 0.1% v/v fetal calf serum, TGF-β exhibited a bi-functional action on the cells. A dose-dependent stimulation of [3H] thymidine incorporation, and an increase in cell number, occurred with fibroblasts established from fetuses under 50 g body weight, with a maximum stimulation seen at 1.25 ng/ml. For fibroblasts from fetuses of 100 g or greater body weight, TGF-β caused a dose-related decrease in thymidine uptake with a maximal inhibition at 2.5 ng/ml, and a small decrease in cell number. When DNA synthesis was stimulated by the addition of somatomedin-C/insulin-like growth factor I, epidermal growth factor, or platelet-derived growth factor, their actions were potentiated by the presence of TGF-β on cells derived from fetuses under 50 g body weight, but inhibited on cells obtained from the larger fetuses wieghing more than 100 g. Similar results were found for changes in cell number in response to TGF-β when stimulated by SM-C/IGF I. The ability of TGF-β to modulate [3H] thymidine incorporation did not involve a change in the time required for growth-restricted cells to enter the S phase of the replication cycle. These data suggest that TGF-β may exert either a growth-promoting or growth-inhibiting action on human fetal connective tissues in the presence of other peptide growth factors, which is dependent on fetal age and development.
    Additional Material: 8 Ill.
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  • 6
    ISSN: 0197-8462
    Keywords: millimeter-wave radiation ; BHK-21/C13 cells in monolayer culture ; scanning electron microscopy ; transmission electron microscopy ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Both thermal and athermal effects of millimeter-wave radiation on BHK-21/C13 cells were sought using scanning and transmission electron microscopy in conjunction with an in vitro technique that allows direct exposure of monolayer cultures to high average power densities. Culture dishes were irradiated by placing them on the open end of an E- or U-band wave guide. This technique exposes different regions of the cell monolayer lying along the longer axis of the wave guide aperture to varying power densities ranging from zero at each edge to twice the average power density at the center.Cell ultrastructure was unaffected by microwave radiation for 1 hour (41.8 or 74.0 GHz, average power densitites = 320 or 450 mW/cm2, respectively) with or without cooling by rapid recirculation of the culture medium. Temperature in recirculated cultures was held at 37.2 °C, and that in noncooled cultures never exceeded 42 °C during irradiation at either power density. In contrast, cell morphology was affected by microwave exposure whenever irradiation conditions were altered so that the temperature of the monolayer reached or exceeded 44.5 °C. Ultrastructural alterations included breakage of cell processes, progressive detachment of cells from the substrate, increased clumping of heterochromatin in the nuclei, and the appearance of large empty vesicles in the cytoplasm. Such morphological changes resulted from either application of higher average power densities or irradiation at the power densities described above at a higher ambient temperature (〉38.5°C).
    Additional Material: 5 Ill.
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  • 7
    ISSN: 0197-8462
    Keywords: millimeter-wave radiation ; BHK-21/C13 cells in monolayer culture ; quantitative autoradiography ; ribonucleic acid (RNA) synthesis ; protein synthesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A method has been devised whereby both the thermal and possible athermal biological effects resulting from microwave radiation can be assessed. Monolayer cultures of BHK-21/C13 cells were grown on microwave-transparent polystyrene coverslips, placed directly on the open end of a wave guide, and irradiated for 1 hour. In experiments seeking athermal biological effects of millimeter waves, culture medium was continuously recirculated over the cells to prevent temperature increases greater than 0.1 °C. Incorporation of 3H-uridine into RNA and of 3H-methionine into protein was quantified by measurement of optical densities of the autoradiographs in contiguous rectangular regions corresponding to portions of the cell monolayer immediately above the wave guide aperture and lying along its longer axis. Since power density was shown to vary with position along this axis according to a cosine2 relationship, it was possible to assess the extent of microwave effects on macromolecular synthesis at power densities ranging from zero at each edge to twice the average power density at the center of the waveguide.Monolayer cultures maintained at 37.2 °C by recirculation of the medium did not show microwave-induced changes in synthesis of RNA and protein (41.8 or 74.0 GHz at average power densities of 320 or 450 mW/cm2, respectively). Since macromolecular synthesis was examined both during and after irradiation, our results exclude both transient and persistent athermal biological effects of acute exposure to millimeter waves. In contrast, irradiation of cultures incubated in a small volume of nonrecirculated medium resulted in 1) marked heating of the monolayer, 2) a graded decline in macromolecular synthesis with increasing incident power, and 3), in some cases, destruction of the cell monolayer in the region immediately above the center of the waveguide aperture.
    Additional Material: 12 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 20 (1995), S. 169-185 
    ISSN: 0271-2091
    Keywords: Finite elements ; Multiblock ; Quadratic elements ; Equal-order ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new multiblock pressure-based finite element algorithm has been developed. This methodology implements quadratic interpolation for both the elemental velocity and pressure fields. A direct streamline upwinding scheme previously developedby the authors is used to model the non-linear inertia effects. Details of the algorithm and its multiblock foundation are provided along with validating test cases. The results presented clearly demonstrate the accuracy of this new approach and the differences in the pressure field for an element using quadratic versus the traditional bi linear approximation of the pressure field.
    Additional Material: 15 Ill.
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  • 9
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Isolated adult rat hepatocytes were used to investigate and compare the actions of glucose or amino acids and insulin, glucagon, growth hormone, and dexamethasone on the expression of insulin-like growth factor binding protein (IGFBP) mRNA, or the release of IGFBP and IGF peptides in vitro. Ligand blot analysis of culture medium conditioned for 24 h by monolayers of hepatocytes in the presence of 6.5 mM glucose revealed two species of IGFBPs, and abundant form of 30-32 kDa and a minor species of 22-24 kDa. Western blotting showed that two IGFBPs of 29-30 and 32 kDa were recognized by antiserum against hIGFBP-1, whereas hepatocytes contained a 1.6 kb transcript on Northern blot with a rat IGFBP-1 cDNA. Insulin-like growth factor BP-2 mRNA was not detected in hepatocytes and IGFBP-2 immunoreactive peptide not present in conditioned medium. The release of IGFBP-1, determined by ligand blot, was independent of gucose concentration over the range of 2.7 mM-11.1 mM, but IGFBP-1 mRNA was decreased following incubation with 6.5 mM gucose compared with 2.7 mM glucose. The release of IGFBP-1 by hepatocytes was inhibited by insulin (10nM-1μM), as was mRNA abundance. However, these effects of insulin on IGFBP-1 diminished with increasing glucose concentration. Increasing concentrations of total amino acids increased IGFBP-1 release as did dexamethasone (100 pM-100nM), whereas growth hormone and gucagon were without effect. The release of IGF I was increased by insulin, growth hormone and dexamethasone but was decreased by glucagon and amino acids, whereas changes in glucose concentration had no effect. The results show that isolated adult rat hepatocytes release IGF I and IGFBP-1 under the interactive control of nutrients and hormones involved in metabolic homeostasis. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 17 (1993), S. 463-475 
    ISSN: 0271-2091
    Keywords: Finite elements ; Streamline upwind ; Quadratic elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A direct streamline upwind method has been developed for convection-dominated flow problems utilizing quadratic elements. The approach presented retains the curve-sidedness feature offered by these elements. This facilitates the use of boundary conforming elements in domains that possess extreme curvature such as turbomachinery bladed components, for which the method is particularly suited. Three test cases are solved to evaluate the stability and diffusive characteristics of the numerical solution. The results presented clearly demonstrate that the proposed method does not exhibit any non-physical spatial oscillations, nor does it suffer from the traditional problem of excessive numerical diffusion.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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