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  • 1
    ISSN: 1432-2013
    Keywords: vasoactive agonists ; transendothelial electrical resistance ; HUVECs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Effects of vasoactive agonists on endothelial permeability was assessed by measurement of transendothelial electrical resistance (TEER) of human umbilical vein endothelial cells (HUVECs) grown on porous polycarbonate supports. Because of the low values of TEER obtained in this preparation (〈 5 Ωcm2) a design of an Ussing type recording chamber was chosen that provided for a homogeneous electric Held across the monolayer and for proper correction of series resistances. Precision current pulses and appropriate rates of sampling and averaging of the voltage signal allowed for measurement of 〈 0.1 Ω resistance changes of the endothelium on top of a 21 Ω series resistance of the support and bathing fluid layers. Histamine (10 μM) and thrombin (10 U/ml) induced an abrupt and substantial decrease of TEER, bradykinin (1 μM) was less effective, PAF (380 nM) and LTC4 (1 μM) had no effect TEER was also reduced by the calcium ionophore A-23187 (10 μM). The technique allows for measurements of TEER in low resistance monolayer cultures with high precision and time resolution. The results obtained extend previous observations in providing quantitative data on the increase of permeability of HUVECs in response to vasoactive agonists.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7217
    Keywords: breast cancer ; cell lines ; estrogen receptor ; nitric oxide ; nitric oxide synthase ; RT-PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For various human tumor cell lines (neuroblastoma, cervix carcinoma) the presence of constitutive nitric oxide synthase (cNOS) has been documented. Here, for the first time, we report about cNOS expression in 10 of 16 human breast cancer cell lines. cNOS expression correlates strongly with expression of estrogen receptor (ER). Competitive reverse transcription — polymerase chain reaction (cRT-PCR) was used to detect cNOS and ER mRNA expression. Our findings suggest that estradiol could stimulate constitutive NO release in breast tissue, where it acts as a free radical.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-7217
    Keywords: breast cancer ; immunohistochemistry ; nitric oxide synthases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Expression of inducible nitric oxide synthase (iNOS) by tumor cells has been suggested to abrogate metastasis in several tumor models, whereas constitutive NOS expression correlated positively with tumor grade in human breast carcinoma. Whether or not expression of one of the various NOS isoforms could predict the prognosis of breast cancer, however, has not been established. In the present report we investigated the cellular distribution of NOS isoforms in a series of benign and malignant breast tumors and in normal breast tissue. Immunohistochemistry revealed that in samples of benign disease the number of iNOS + epithelial cells or total epithelial cells was 69 ± 16% (n=50). In samples of grade II invasive ductal breast carcinomas the number of iNOS+ tumor cells or total tumor cells was 62 ± 20 (n=40), compared to 12 ± 9 (n=40) in samples of grade III carcinomas (P 〈 0.0001). iNOS protein was also identifiable in most of the epithelial cells of normal breast tissue (n=4). In contrast, eNOS protein was restricted to vascular endothelial cells in all of the specimens studied. Since the presence of tumor cell iNOS protein is inversely related to the tumor’s metastatic potential, we conclude that endogenous tumor cell mediated iNOS expression might have an inhibitory effect on the metastatic process in breast cancer.
    Type of Medium: Electronic Resource
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