Averil Y. Warren

Loss of endothelium‐dependent relaxation in myometrial resistance arteries in pre‐eclampsia

Objective To measure endothelium‐dependent relaxation in myometrial resistance arteries and to compare this parameter in nonpregnant and normotensive pregnant women and those with pregnancies complicated by pre‐eclampsia.

Plasma from women with pre-eclampsia induces an in vitro alteration in the endothelium-dependent behaviour of myometrial resistance arteries.

Objective To compare the in vitro effect of plasma from normal pregnant women and women with pre‐eclampsia on the endothelium‐dependent behaviour of myometrial resistance arteries from normal pregnant women.

Plasma from pre-eclamptic women and functional change in myometrial resistance arteries

This study assesses the ability of plasma from women with pre‐eclampsia to induce altered endothelial function in myometrial resistance vessels from normotensive women. Vessels from normotensive pregnant women (n= 7) were incubated with plasma from other pregnant women who were normotensive (n= 6)or had pre‐eclampsia (n= 7). A wire myograph was used to test the endothelium‐dependent relaxatory response to bradykinin of preconstricted vessels. The relaxation in vessels incubated with plasma from women with pre‐eclampsia was markedly less than in vessels incubated with plasma from normotensive pregnant women (P = 0.039). This supports the theory that a plasma‐borne factor contributes to the endothelial changes seen in pre‐eclampsia.

Vascular endothelial growth factor but not placental growth factor promotes trophoblast syncytialization in vitro.

OBJECTIVE: The object of this study was to determine the effect of epithelial growth factor (EGF), vascular endothelial growth factor (VEGF), and placental growth factor (PIGF) on the diferentiation of first-trimester and term cytotrophoblasts. METHODS: The first-trimester trophoblasts were isolated from villous tissue obtained at suction termination (n = 5), and the term trophoblasts were isolated from placentas (n = 6) at elective cesarean. Cultured cells were stimulated with EGF, VEGF, or PIGF at 0.5, 5, and 50 ng/mL, in the presence or absence of NG-nitro-L-arginine methyl ester hydrochloride (10-4 M). Syncytialized trophoblasts were identified by immunostaining with antidesmosomal protein and anti-cytokeratin-7, whereas nuclei were counted in each syncytia using hematoxylin. RESULTS: Without treatment, background levels of syncytialization were signficantly higher in term preparations than first-trimester cells. With VEGF and EGF, the number and size of syncytia increased signficantlyfor thefirst-trimester cytotrophoblasts (P < .05). Neither VEGF nor EGF had any effect on the syncytialization of cultured cells at term. Nitric oxide showed no involvement in syncytial induction, and PIGF had no effect on syncytialization of cytotrophoblasts, from either the first or third trimester. CONCLUSION: Both EGF and VEGF appeared to enhance the in vitro syncytialization of first trimester cytotrophoblasts.

The Eag potassium channel as a new prognostic marker in ovarian cancer.

BackgroundOvarian cancer is the second most common cancer of the female genital tract in the United Kingdom (UK), accounting for 6% of female deaths due to cancer. This cancer is associated with poor survival and there is a need for new treatments in addition to existing chemotherapy to improve survival. Potassium (K+) channels have been shown to be overexpressed in various cancers where they appear to play a role in cell proliferation and progression.ObjectivesTo determine the expression of the potassium channels Eag and HERG in ovarian cancer tissue and to assess their role in cell proliferation.MethodsThe expression of Eag and HERG potassium channels was examined in an ovarian cancer tissue microarray. Their role in cell proliferation was investigated by blocking voltage-gated potassium channels in an ovarian cancer cell line (SK-OV-3).ResultsWe show for the first time that high expression of Eag channels in ovarian cancer patients is significantly associated with poor survival (P = 0.016) unlike HERG channel expression where there was no correlation with survival. There was also a significant association of Eag staining with high tumour grade (P = 0.014) and presence of residual disease (P = 0.011). Proliferation of SK-OV-3 cells was significantly (P < 0.001) inhibited after treatment with voltage gated K+ channel blockers.ConclusionThis novel finding demonstrates a role for Eag as a prognostic marker for survival in patients with ovarian cancer.

A comparison of endothelium-dependent relaxation in omental and myometrial resistance arteries in pregnant and nonpregnant women

OBJECTIVES The study aimed to compare endothelium-dependent relaxation in the resistance arteries of the uterine vascular bed by use of a systemic comparison and to investigate the role of the endothelium in adaptation to pregnancy in these vascular beds. STUDY DESIGN Myometrial and omental resistance arteries were collected from 22 normotensive pregnant women and 27 nonpregnant women of reproductive age. On a wire myograph and preconstricted with vasopressin, the arteries were relaxed with the endothelium-dependent vasodilator bradykinin. RESULTS The omental arteries showed a consistently greater endothelium-dependent relaxation than the myometrial arteries, both in the nonpregnant state (p < 0.0001) and in pregnancy (p = 0.008); pregnancy did not significantly alter this relaxation in arteries from either the myometrial (p = 0.2075) or omental (p = 0.372) vascular beds. CONCLUSIONS The endothelium-dependent relaxation to bradykinin is less in myometrial resistance arteries than in omental resistance arteries. There appears to be no intrinsic difference between vessels from nonpregnant and pregnant women in endothelium-dependent response to bradykinin.

Effect of the vascular endothelium on norepinephrine-induced contractions in uterine radial arteries from the nonpregnant and pregnant human uterus

OBJECTIVE Our purpose was to investigate the role of the endothelium in the human uterine arterial response to norepinephrine in the nonpregnant and pregnant states. STUDY DESIGN Tissue was obtained from six pregnant and six nonpregnant women undergoing cesarean section or hysterectomy. Uterine radial arteries were isolated and subjected to norepinephrine dose-response curves with and without intact endothelium. RESULTS Responses were obtained over a dose range of 10(-8) to 10(-4) norepinephrine. Initially there was no difference between vessels from pregnant and nonpregnant patients, but removal of the endothelium significantly increased the response in vessels from pregnant women. Addition of nitro-L-arginine methyl ester when the endothelium was intact did not alter the dose-response curves. CONCLUSIONS In pregnancy human uterine radial arteries are more sensitive to norepinephrine than during the nonpregnant state. This increase is countered by an endothelium-derived relaxing factor. The factor is unlikely to be nitric oxide.

The role of Eag and HERG channels in cell proliferation and apoptotic cell death in SK-OV-3 ovarian cancer cell line

BackgroundThe voltage gated potassium (K+) channels Eag and HERG have been implicated in the pathogenesis of various cancers, through association with cell cycle changes and programmed cell death. The role of these channels in the onset and progression of ovarian cancer is unknown. An understanding of mechanism by which Eag and HERG channels affect cell proliferation in ovarian cancer cells is required and therefore we investigated their role in cell proliferation and their effect on the cell cycle and apoptosis of ovarian cancer cells.MethodsThe presence of Eag and HERG was determined in SK-OV-3 cells using immunofluorescence and western blotting. The effect of the Eag blockers (imipramine and clofilium) and HERG blockers (E-4031 and ergtoxin) on cell proliferation was assessed using the MTS assay with further investigation of their role in the cell cycle and apoptosis determined by flow cytometry.ResultsEag and HERG channels were present in the cytoplasm and nuclei of SK-OV-3 cells. There was significant inhibition of proliferation of SK-OV-3 cells by imipramine (P < 0.001) and ergtoxin (P < 0.05) at 72 hours of culture. Incubation of cells with ergtoxin led to the accumulation of cells in the S and G2/M phase, while cells accumulated in S phase after incubation with E-4031, with no effect on apoptosis. Imipramine did not affect the cell cycle but increased the proportion of SK-OV-3 cells undergoing early apoptosis.ConclusionBoth Eag and HERG channels are expressed in SK-OV-3 ovarian cancer cells and have a role in cell proliferation. HERG channels affect the cell cycle while Eag channels are implicated in the inhibition of apoptosis of ovarian cancer cells. The family of Eag channels may represent a new therapeutic target for the treatment of ovarian cancer.

Myometrial and placental artery reactivity alone cannot explain reduced placental perfusion in pre‐eclampsia and intrauterine growth restriction

Objectives (1) To investigate a possible association between myometrial and placental artery vasoreactivity and perfusion at the basal and chorionic plates, respectively. (2) To confirm that myometrial arteries from women with pre‐eclampsia and intrauterine growth restriction exhibit an attenuated endothelium‐dependent vasodilatory response.

Mechanisms of Endothelium-Dependent Relaxation in Myometrial Resistance Vessels and Their Alteration in Preeclampsia

OBJECTIVE To investigate the importance of prostacyclin and nitric oxide synthesis in endothelium-dependent relaxation in myometrial resistance vessels, and to test the hypothesis that a deficiency in nitric oxide synthesis contributes to the known alterations in endothelial function in preeclampsia. METHODS Thirty-six women with normal pregnancies and 14 with preeclampsia had the myometrium biopsied at cesarean section. Resistance arteries were dissected and mounted on a wire myograph. After preconstriction with vasopressin, vessels were treated cumulatively with bradykinin. The process was repeated in the presence of indomethacin and then indomethacin and NG-monomethyl-L-arginine (L-NMMA). RESULTS The vessels from women with normal pregnancies showed endothelium-dependent relaxation to bradykinin which was not significantly altered by the presence of indomethacin. The addition of L-NMMA significantly, but only partially, reduced the relaxation to bradykinin in the presence of indomethacin (p = 0.03). The vessels from women with preeclampsia showed markedly reduced relaxation to bradykinin (p < 0.0001), as compared to vessels from normal pregnant women. Relaxation of vessels from women with preeclampsia was increased by the addition of indomethacin (p = 0.03) but was virtually eradicated by the presence of L-NMMA. CONCLUSIONS Eicosanoid synthesis plays little part in the relaxation of normal pregnant myometrial vessels to bradykinin. Nitric oxide synthesis mediates part but not all of the endothelium-dependent relaxation. In preeclampsia, relaxation to bradykinin is reduced; inhibition of eicosanoid synthesis allows increased relaxation, and nitric oxide synthesis appears to mediate a greater proportion of the relaxation than in normal pregnant women.