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  • 1
    Electronic Resource
    Electronic Resource
    Technique for visualization and quantification of three dimensional intracellular ion measurements in vascular endothelial cells (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2476-2492 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A first generation digital imaging video microscopy system has been developed that is able to provide both quantitative and visual three dimensional information from individual vascular endothelial cells. More specifically, with the combination of optical sectioning, video microscopy, digital image processing and analysis, deconvolution, fluorescence ratio imaging, and scientific visualization we are able to measure the dynamic changes in spatial distributions of intracellular ions. The technique presented involves the following steps: acquiring three dimensional biological data by optical sectioning of a specimen, preprocessing the digitized volume data, experimentally determining the digital imaging system's point spread function (PSF), deconvolving the volume data with the PSF to remove the inherent out-of-focus information, and finally postprocessing and volume rendering in order to display the volume data in a quantitative and comprehensible manner. This technique permits high resolution visualization and quantification of three dimensional spatial distributions of ions as well as traditional temporal changes in ion concentration. It has the potential to aid immensely in research since the three dimensional spatial information is often a prerequisite for understanding the molecular mechanisms involved in many complex cellular processes. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145645
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  • 2
    Electronic Resource
    Electronic Resource
    Shear sensitivity of hybridoma cells in batch, fed-batch, and continuous cultures (1990)
    s.l. : American Chemical Society
    Biotechnology progress 6 (1990), S. 114-120 
    Details
    ISSN: 1520-6033
    Source: ACS Legacy Archives
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bp00002a004
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  • 3
    Electronic Resource
    Electronic Resource
    Technique for visualization and analysis of mural thrombogenesis (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 892-897 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Epi-fluorescence video microscopy, digital image processing, and photodiode measurements were used to visualize and analyze mural thrombogenesis, the initial stages of blood platelet adhesion to and aggregation on a surface. This technique permitted real-time visualization, high-resolution, quantitative, off-line measurement of the growth of individual thrombi and high-resolution, quantitative, end-point measurement of the accumulation of platelets as a function of position on the surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138830
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  • 4
    Electronic Resource
    Electronic Resource
    Differential adhesion of metastatic RAW117 large-cell lymphoma cells under static or hydrodynamic conditions: role of integrin alpha v beta3 (1997)
    Springer
    Clinical & experimental metastasis 15 (1997), S. 3-11 
    Details
    ISSN: 1573-7276
    Keywords: cell adhesion ; integrin ; liver ; lymphoma ; metastasis ; vitronectin receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract RGD-containing substrates were used to study static and hydrodynamic adhesion of murine RAW117 large-cell lymphoma sublines with differential liver-metastatic potentials. Highly liver-metastatic RAW117-H10 cells had higher rates of static adhesion to vitronectin, fibronectin and (GRGDS) than poorly metastatic RAW117-P and moderately liver-metastatic RAW117-L17 cells. Under hydrodynamic conditions, adhesion stabilization was more rapid for H10 cells compared to P or L17 cells. Among the RGD peptides, only the polymeric RGD peptide (GRGDS) mediated strong static adhesion of H10 cells. Interestingly, all the RGD peptides mediated adhesion stabilization for H10 cells but still not for L17 or P cells under hydrodynamic conditions. Integrin αβ was involved in stabilizing hydrodynamic adhesion to (GRGDS), monomeric RGD peptide R1, but was less important in static adhesion to monomeric RGD peptides. Differential adhesion to liver sinusoidal endothelial cell-derived extracellular matrix (H10 ≫ L17 〉 P) was observed under hydrodynamic but not static conditions. Integrin αβ was also important in hydrodynamic adhesion to liver sinusoidal endothelial cell-derived extracellular matrix. We believe that strong static and hydrodynamic adhesion of H10 cells and their capability of altering adhesive behavior in response to fluid shear may contribute to liver metastasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018451616309
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  • 5
    Electronic Resource
    Electronic Resource
    Integrin α4β1/VCAM-1 pathway mediates primary adhesion of RAW117 lymphoma cells to hepatic sinusoidal endothelial cells under flow (1999)
    Springer
    Clinical & experimental metastasis 17 (1999), S. 669-676 
    Details
    ISSN: 1573-7276
    Keywords: alpha-4 integrins ; flow assay ; RAW117 cells ; tumor cell adhesion ; VCAM-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adhesion and stabilization of circulating tumor cells to endothelial cells in target blood vessels play an important role in the complex process of metastasis. We examined the cell surface receptors involved in the liver-metastatic adhesive interactions of murine RAW117 large-cell lymphoma cells to unstimulated hepatic sinusoidal endothelial cells (HSE) under physiological flow conditions. Flow cytometric analysis indicated that VCAM-1, ICAM-1 and PECAM-1 are constitutively expressed on the surfaces of both HSE and RAW117 cells. However, monoclonal antibody (mAb) blockade studies showed that ICAM-1 and PECAM-1 affected neither the attachment nor the stabilization step of the adhesion of RAW117 cells to HSE cell monolayers under flow. In contrast, RAW117 cells required a significantly lower shear stress to establish adhesion to HSE cells when VCAM-1 receptors on HSE cells were blocked with mAb. Furthermore, the presence of the anti-VCAM-1 mAb significantly decreased the extent of adhesion compared to that of the control, without affecting adherent cell stabilization times. Blocking the α4integrin subunits present mainly on RAW117 cells produced similar results to those previously observed with anti-VCAM-1 mAb. Although constitutively present mainly on the surfaces of RAW117 cells, MAdCAM-1 and β7 integrin subunit do not appear to play a role in either the arrest or stabilization of RAW117 cells on HSE cell monolayers. However, blocking the β1integrin subunit on the RAW117-H10 cells reduced adhesion to the same extent as anti-α4 and anti-VCAM-1 treatments. These observations suggest that an interaction of integrin α4β1on RAW117 cells with liver endothelial VCAM-1 occurs during the early stages of the adhesion process and may be important in liver metastasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006747106885
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  • 6
    Electronic Resource
    Electronic Resource
    Growth Factor Delivery for Tissue Engineering (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 497-504 
    Details
    ISSN: 1573-904X
    Keywords: tissue engineering ; growth factors ; controlled release ; bone ; nerve ; liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A tissue-engineered implant is a biologic-biomaterial combination in which some component of tissuehas been combined with a biomaterial to create a device for the restoration or modification of tissue ororgan function. Specific growth factors, released from a delivery device or from co-transplanted cells,would aid in the induction of host paraenchymal cell infiltration and improve engraftment of co-deliveredcells for more efficient tissue regeneration or ameliorate disease states. The characteristic properties ofgrowth factors are described to provide a biological basis for their use in tissue engineered devices. Theprinciples of polymeric device development for therapeutic growth factor delivery in the context of tissueengineering are outlined. A review of experimental evidence illustrates examples of growth factor deliveryfrom devices such as micropaticles, scaffolds, and encapsulated cells, for their use in the applicationareas of musculoskeletal tissue, neural tissue, and hepatic tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007502828372
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  • 7
    Electronic Resource
    Electronic Resource
    Shear Stress Differentially Regulates PGHS-1 and PGHS-2 Protein Levels in Human Endothelial Cells (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 824-833 
    Details
    ISSN: 1573-9686
    Keywords: Prostaglandin H synthase ; Gene regulation ; Endothelium ; Cyclooxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The secretion of prostacyclin (PGI2) by endothelial cells is regulated by shear stress.Prostaglandin H synthase (PGHS) is considered to be a key limiting enzyme in the synthesis of PGI2from arachidonic acid. Endothelial cells were cultured in the presence of 4, 15, or 25 dyn/cm2shear stress using a parallel plate flow chamber to assess the effect of shear stress on both PGHS isoforms, PGHS-1 and PGHS-2.In cells exposed to 4, 15, or 25 dyn/cm2 shear stress PGHS-1 and PGHS-2 protein levels initially decreased.The decrease was followed by a sustained increase for PGHS-1 but only a transient increase for PGHS-2. The duration of the PGHS-2increase depended on the magnitude of the shear stress. The effect of altering shear stress levels on PGHS protein levels in cellspreconditioned to either 4, 15, or 25 dyn/cm2 shear stress for 48 h was also studied. Changing shear stresslevels effected PGHS-2 but not PGHS-1. Increases in shear stress levels from 4 to 15 or 25 dyn/cm2 caused a decreasein PGHS-2. In contrast, decreases in shear stress levels from 15 or 25 to 4 dyn/cm2 caused PGHS-2 to increase.There was a continual decrease in PGHS-2 when the shear stress was changed from 15 to 25 or 25 to 15 dyn/cm2In summary, the regulation of PGHS-2 by shear stress is dependent upon the magnitude of the shear stress, whereas the regulation of PGHS-1protein levels seems to be independent of the shear stress magnitude. The regulation of PGHS-1 and PGHS-2 protein levels by shear stressindicates that these proteins play an important role in the maintenance of cardiovascular homeostasis as regulators of PGI2production. © 2000 Biomedical Engineering Society. PAC00: 8717-d, 8719Rr
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.1289472
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  • 8
    Electronic Resource
    Electronic Resource
    The structural properties and contractile force of a clot (1982)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 445-455 
    Details
    ISSN: 0886-1544
    Keywords: clot structure ; platelet contractility ; protein networks ; rheological techniques ; viscoelasticity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When citrated plasma is recalcified, it forms a viscoelastic gel-a clot. The relationship between platelet contractility and clot rigidity was studied by using a rheological technique which simultaneously measured both the dynamic rigidity modulus and the contractile force during gel formation with platelet rich plasma (PRP). Protein network formation in a clot was accompanied by a contractile force throughout the clotting process. PRP demonstrated a maximum elastic modulus of 6,000 dynes/cm2 and a maximum contractile force/area of 1,500 dynes/cm2. The values of these parameters for a platelet-free clot (PFP) were 700 dynes/cm2 and less than 100 dynes/cm2 respectively. Sonicated control PRP and PRP from a Glanzmann thrombasthenia patient both clotted in a manner similar to PFP. Metabolic inhibitors, 2-deoxy-D-glucose and KCN (5 mM each), retarded the clotting curves of PRP. Cytochalasin B and E suppressed both structural rigidity and force generation in a concentration-dependent manner similar to their inhibitory effect on actin polymerization in platelets. Colchicine (2.5 mM) or vinblastine (0.11 mM) did not affect these clotting curves. Thrombi-activated, fixed platelets did not generate any force, nor did they significantly increase clot rigidity. Streptokinase induced a concurrent decrease of both rigidity and force in PRP clots. The elastic modulus of a PFP clot could be increased to 2,500 dynes/cm2 by externally straining the network with an axial force/area of 1,500 dynes/cm2. Our results indicate that clot structure formation in PRP is strongly coupled to the contractile force generated by the platelet microfilament system and that this force modulates clot rigidity.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970020504
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  • 9
    Electronic Resource
    Electronic Resource
    Computerized analysis of tumor cells flowing in a parallel plate chamber to determine their adhesion stabilization lag time (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 26 (1993), S. 88-98 
    Details
    ISSN: 0886-1544
    Keywords: transglutaminase ; melanoma ; digital image analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The importance of cell adhesion in a variety of physiological phenomena requires development of an understanding of the factors and molecular mechanisms underlying these behaviors. Cell adhesion is a multistep process involving primary receptor-ligand interactions followed by secondary events that may lead to the formation of focal contacts. Due to the lack of well-defined assays to study adhesion stabilization, little is known about this process, except that it may involve signaling events, receptor recruitment, and, as we have demonstrated, covalent peptide cross-linking by cell membrane-associated transglutaminase [Menter et al.: Cell Biophys. 18:123-143, 1992]. To study the stabilization process we have developed a dynamic assay employing a parallel plate flow chamber coupled with video microscopy and digital image processing. Our studies utilize wheat germ agglutinin-selected human metastatic melanoma cell variants that exhibit differences in their experimental metastatic potential and expression of transglutaminase. Using this assay, quantifying cell-substrate stabilization was found to be quick, reliable, reproducible, and useful in evaluating agents that block this process. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970260109
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of shear stress on86Rb+ efflux from calf pulmonary artery endothelial cells (1993)
    Springer
    Annals of biomedical engineering 21 (1993), S. 1-7 
    Details
    ISSN: 1573-9686
    Keywords: Endothelial cells ; Shear stress ; K+ permeability ; 86Rb+ ; Calf pulmonary artery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The effect of flow-induced shear stress on membrane K+ permeability was investigated by measuring86Rb+ efflux in cultured calf pulmonary artery endothelial cells. Cells were subjected to step changes in shear stress from 1 dyn/cm2 to 2.4, 4.8, or 10 dyn/cm2 in a parallel-plate flow chamber. Increasing shear stress produced a graded, transient increase in86Rb+ efflux which peaked within 1 min and subsequently declined rapidly toward pre-stimulus levels. Upon returning shear stress to 1 dyn/cm2,86Rb+ efflux initially decreased, but returned slowly to basal values. In contrast, application of bradykinin at a constant shear stress of 1 dyn/cm2 produced a transient increase in86Rb+ efflux that was followed by a sustained elevated phase during which time efflux gradually returned to pre-stimulus levels. In order to exclude the possibility that the transient increase in86Rb+ efflux with shear stress simply reflects a flow-dependent change in the washout of radiotracer, the transient convection-diffusion equation was solved using finite element simulation. When the flux of86Rb+ from the cell monolayer was assumed to be constant with time, the mathematical model predicted an increase in efflux rate coefficients upon step increases in flow that were only 7–19% of that observed experimentally. The numerical predictions correlated well with the experimentally obtained peaks when the flux of86Rb+ from the cell monolayer was simultaneously increased with flow to a new steady value. These simulations however, could not predict the transient nature of the response to increased shear stress. The results from the computer modeling suggest that the transient increase in86Rb+ efflux does not reflect a washout phenomenon and supports the hypothesis that shear stress produces a graded, transient increase in the K+ permeability of vascular endothelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368159
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