Effects of estrogen on tight junctional resistance in cultured human umbilical vein endothelial cells

OBJECTIVE: To study the effects of estrogen on transendothelial paracellular permeability in women. METHODS: Human umbilical vein endothelial cells (HUVEC) obtained from women were grown on filters. The paracellular permeability characteristics were determined in terms of changes in the permeability to the polar acid pyranine (Ppyr) and as changes in the transendothelial electrical resistance (RTE). Tight junctional resistance characteristics were assayed by lowering luminal NaCl and measuring the dilution potential, and were expressed as the ratio of monoion mobility uCl/uNa (cation selectivity). RESULTS: Low extracellular calcium and hyperosmolarity increased Ppyr and decreased RTE. The former but not the latter condition abolished the endothelium-specific cation selectivity. Treatment with 10 nM of estradiol-17 beta had no effect on RTE, but it increased the cation selectivity. The effect of estradiol required 1-6 hours' incubation with the hormone; it was dose dependent and saturable, with a median effective concentration of estradiol of 1 nM. Diethylstilbestrol, but not estriol, could mimic the effect of estradiol, and the estrogen receptor antagonist ICI-182, 780 blocked it. CONCLUSION: Cultured HUVEC cells form patent tight junctions. Estrogens increase the cation selectivity across HUVEC cultures. The effect of estrogen may be mediated by an estrogen receptor. These effects may be important for vasculoprotection in cases of sudden changes in ions levels across the capillary wall, such as ischemia or reperfusion.     

Thrombin promotes platelet-mediated melanoma cell adhesion to endothelial cells under flow conditions: role of platelet glycoproteins P-selectin and GPIIb-IIIA

We investigated the role of platelets in human melanoma cell (line 397) interaction with vascular endothelial cells (ECs) under flow conditions. The ability of the tumour cells to adhere to the EC monolayer was significantly reduced by application of flow at a shear rate of 250 s(-1). A 2.2-fold increase in tumour cell adhesion to ECs under flow was observed upon addition of thrombin receptor agonist peptide (TRAP)-activated platelets but not resting platelets. A similar increase (2.5-fold) in tumour cell adhesion to ECs under flow was observed when the tumour cells were incubated with resting platelets on thrombin-treated ECs. However, thrombin treatment of the ECs alone had no effect on tumour cell adhesion in the absence of platelets. The enhancement of tumour cell adhesion to ECs by TRAP-activated platelets was virtually abolished by blockade of the platelet glycoproteins P-selectin and GPIIb-IIIa by monoclonal antibodies. Blockade of P-selectin also inhibited the direct adhesion of TRAP-activated platelets to ECs, but did not affect the interaction of the tumour cells with platelets immobilized on subendothelial extracellular matrix (ECM). Blockade of GPIIb-IIIa inhibited both platelet-EC and platelet-tumor cell interactions. Our results indicate that tumour cell adhesion to the endothelium under flow is enhanced by platelets under conditions that allow platelet adhesion to ECs. Inhibition studies suggest that activated platelet adhesion to ECs is mediated by P-selectin and GPIIb-IIIA, and tumour cell adhesion to EC-bound platelets--mainly by GPIIb-IIIa.     

Direct effects of estradiol and tamoxifen on gene expressions of inhibit alpha- and beta A-subunits in rat granulosa cells in vitro

To analyze direct effects of estrogen on gene expressions of inhibin subunits in vitro, the mRNA levels of inhibin alpha- and beta A-subunits were measured in rat granulosa cells cultured with FSH or estradiol. Through the culture process of the granulosa cells with serum-free medium, both the alpha- and beta A subunit mRNAs decreased, and were partially increased again by adding FSH to the culture medium. To examine whether these FSH effects are mediated via estrogen production, estradiol or tamoxifen was added to the cultured granulosa cells. After 36-h culture with estradiol, the inhibin alpha-subunit decreased but the inhibin beta A-subunit increased, in a dose-responsive manner. Tamoxifen showed completely opposite effects to estradiol, and a combination of estradiol and tamoxifen resulted in similar levels of inhibin-alpha and -beta A mRNAs to the control. These results indicate that estrogen would by a certain pathway affect gene expressions of the inhibin subunits in the rat granulosa cells, and may regulate the production of inhibin and activin through the paracrine system.     

The metabolic fate of [3H]estradiol in relation to dietary intake of boron in ovariectomized rats

It has been reported that boron (B) deprivation reversibly lowers plasma estradiol levels in postmenopausal women. In order to establish whether this reflects disturbances in the estrogen catabolic pathway and in particular in catechol estrogen metabolism, the influence of dietary B on the catabolism of [3H]estradiol-17 beta has been studied in ovariectomized rats. Rats were given diets containing < 0.1 or 40 mg B.kg-1, ovariectomized and then infused with [3H]estradiol-17 beta using osmotic pumps. Analysis of urine samples for conjugated, catechol and non-catechol estrogens did not reveal any effects of B on the recovery or the metabolic fate of tritium from the infused estradiol. These results do not therefore support the proposal that B influences estrogen catabolism by interacting with catechol estrogens.     

Inferior vena cava filters in cancer patients: indications and outcome

Estrogen, like other steroids, may induce rapid nongenomic cellular effects. We studied the effect on intracellular cAMP of short-term exposure (5 min) of cultured rat pulmonary vascular smooth muscle cells (VSMC) to estradiol 17 beta. At confluence, VSMC were incubated in phosphate buffer saline for 1 hr before exposure to different hormones. The reaction was stopped with 0.1 N HCl and cyclic adenosine monophosphate (cAMP) was measured by radioimmunoassay. The 5-min incubation with estradiol 17 beta (0.3-30 microM) significantly increased basal intracellular cAMP in a concentration-dependent manner. The stimulatory effect of estradiol on cAMP was time-dependent, increasing with prolonged exposure to the hormone, and was not affected by the protein synthesis inhibitor, actinomycin D (5 micrograms/ml), at 5 and 30 min. Comparable concentrations of testosterone or estradiol 17 alpha had no significant effect on cAMP. The estrogen receptor partial agonist, tamoxifen also significantly increased basal cAMP in a concentration-dependent manner, but inhibited the effect of estradiol. Furthermore, forskolin elicited a concentration-dependent increase in cAMP (396.6 +/- 53% at 10 microM concentration), which was significantly potentiated in presence of estradiol. The effect of estradiol is unlikely to be mediated by G-protein activation, because the G protein inhibitor, pertussis toxin (100 ng/ml), did not significantly affect estradiol-induced increase in cAMP. Removal of Ca++ from the incubation medium inhibited the stimulatory effect of estradiol 17 beta suggesting that estradiol may increase pulmonary VSMC cAMP via a Ca(++)-dependent pathway. We suggest that the effect of estradiol 17 beta in these experiments is nongenomic in nature, and is possibly mediated by direct interaction of the hormone with specific membrane binding sites.     

Transdermal estrogen replacement therapy: beneficial effects on hemostatic risk factors for cardiovascular disease

OBJECTIVES: To assess the effect of estrogen replacement therapy on hemostatic risk factors for cardiovascular disease (CVD) in postmenopausal women during 2 years of treatment. METHODS: In an open prospective study, patients (n = 42) were investigated before and during 2 years of treatment, and compared to an untreated postmenopausal control group (n = 18) followed during the same period, healthy premenopausal women (n = 20) being included as a reference group for premenopausal values. The patients underwent treatment with transdermal 17 beta-estradiol (E2) (50 micrograms/24 h), oral medroxyprogesterone acetate (5 mg/day) being added for 12 days every second month. RESULTS: After 2 years of treatment there was a significant increase in t-PA antigen (P = 0.01) and a significant decrease in F VII antigen (P = 0.01). PAI-1 antigen concentrations decreased slightly. Fibrinogen concentrations were already significantly decreased at 3-month follow-up (P = 0.01), and were still low after 2 years. By contrast, at 2-year follow-up the postmenopausal control group manifested significant increases in F VII and PAI-1 antigen and slight increases in fibrinogen, which resulted in significant differences between patients and controls. Regression analysis showed the increase in the serum estradiol concentrations to be inversely correlated to the decreases in the plasma concentrations of F VII antigen (r = -0.34, P = 0.001) and fibrinogen (r = -0.35, P = 0.001). There were no changes in AT III or protein C in any group. CONCLUSIONS: The increase in serum estradiol concentrations due to replacement therapy did not adversely affect the studied components of the fibrinolytic and protein C defense system against thrombosis, and resulted in beneficial decreases in F VII antigen and fibrinogen. These findings may help to explain the beneficial effects of estrogen replacement therapy in terms of protection from cardiovascular disease.     

Tennis elbow. Current concepts of treatment and rehabilitation

OBJECTIVE: Estrogens are known to exhibit antioxidative effects. At present little information exists on the influence of co-administered progestins upon this effect. Therefore we investigated the influence of levonorgestrel, a potent antiestrogenic progestin, on the inhibition of the low-density lipoprotein (LDL) oxidation by 17 beta-estradiol or 17 beta-estradiol valerate in vitro and ex vivo. METHODS: After isolation from blood, the in vitro oxidation of LDL was induced by copper ions and measured continuously by monitoring the formation of conjugated dienes. In 21 female ovariectomized White New Zealand rabbits the antioxidative action of 17 beta-estradiol alone or in combination with levonorgestrel after subcutaneous infusion for 3 days was determined using the copper-induced LDL-oxidation as an endpoint. Eleven postmenopausal women were exposed to sequential estrogen-progestin replacement therapy (day 1-21:2 mg estradiol valerate/day, day 10-21: 0.15 mg levonorgestrel/day). Blood samples were collected at three times: on day 1, on day 10, on day 22 (after the combination phase). The lag time of ex vivo oxidation of LDL, the plasma estradiol and estrone levels were estimated. RESULTS: In the chosen cell-free system, 17 beta-estradiol increased the lag time of the LDL-oxidation in a dose-dependent manner. Levonorgestrel showed neither pro-oxidative nor antioxidative effects when administered alone in different concentrations. Co-administration of different doses of levonorgestrel did not modify the antioxidative action of estrogen either. The two ex-vivo models confirmed these results. In rabbits the co-administered 19-nortestosterone derivative levonorgestrel did not impair or reverse the estradiol-dependent effect. In postmenopausal women the daily oral administration of levonorgestrel in conjunction with 17 beta-estradiol valerate did not diminish the antioxidative action of this estrogen given for the first 9 days. CONCLUSION: The antioxidative potential of estradiol and estradiol valerate is maintained in the presence of levonorgestrel.     

Psychoneuroendocrinology of depression. Hypothalamic-pituitary-gonadal axis

Women are more susceptible than men to depression, particularly during periods of rapid fluctuation of gonadal hormones, such as premenstrually, postpartum, and during the climacteric. This review summarizes the evidence for the association of depression with abnormalities in reproductive hormones. Although there are similarities in stress hormones changes between depressed women and women with stress-related amenorrhea, no abnormalities in LH activity have been documented in depression. Similarly no abnormalities in LH, estradiol, or progesterone have been documented in premenstrual syndrome (PMS), although complete elimination of monthly cycling with leuprolide improves mood. Some studies have suggested beneficial effects of estrogen on mood in postmenopausal women but as yet there have been no adequately controlled studies of estrogen treatment of either premenopausal or postmenopausal women.     

Effects of tamoxifen in relation to breast cancer

It has been suggested that tamoxifen possesses estrogenic properties which may induce regression of mammary tumors in humans. However, it has been shown that tamoxifen inhibits the estradiol-stimulated changes in immature, ovariectomized, and mature rats. Whereas estradiol stimulates cell division, tamoxifen produces endometrial hypertrophy, even though it has been shown to bind to cytoplasmic estrogen receptors. In vitro experiments with human breast cancer cells have shown that tamoxifen has effects other than that of a simple estrogen antagonist. It is concluded that in addition to its antiestrogneic properties, it may act as a partial or a typical estrogen agonist, which may account for its antitumor activity in postmenopausal patients with breast cancer.     

Extensive platelet activation in preeclampsia compared with normal pregnancy: enhanced expression of cell adhesion molecules

OBJECTIVES: Platelets play an important role in the pathophysiologic mechanisms of preeclampsia. Our purpose was to investigate by means of flow cytometry to what extent platelets circulate in an activated state during normal pregnancy and whether this activation is more extensive in preeclampsia. STUDY DESIGN: Platelets in whole blood from 10 preeclamptic third-trimester pregnant women (highest diastolic blood pressure range 100 to 130 mm Hg, proteinuria range 0.59 to 11.5 gm/24 hr) and from 10 normotensive third-trimester pregnant controls were analyzed with the following activation markers: anti-P-selectin (alpha-granule secretion), anti-CD63 (lysosomal secretion), PAC-1 (monoclonal antibody against fibrinogen receptor conformation of the glycoprotein IIb/IIIa complex), anti-platelet endothelial cell adhesion molecule-1, and annexin-V (a placental protein that binds to negatively charged phospholipids, present on the outside of the platelet plasma membrane after activation). The differences in surface antigen exposure between the two groups were determined by double-label flow cytometry. Flow cytometric data were analyzed in two ways: first, the percentages of activated platelets above a certain threshold compared with a nonpregnant control sample were determined, indicative for activation of a subpopulation of cells, and, second, the mean fluorescence intensities were determined, indicative of the mean surface antigen expression of the total platelet population. RESULTS: Analysis of the percentage of activated platelets proved most informative. With this analysis an enhanced platelet activation status was present in 4 of 10 normotensive patients and a more extensive platelet activation status in all 10 preeclamptic patients, as indicated by P-selectin (p = 0.008) and CD63 (p = 0.03) expression. Increased platelet endothelial cell adhesion molecule-1 (p = 0.005) expression was also observed in preeclampsia. CONCLUSIONS: Flow cytometric analysis clearly indicated that platelets circulate in a more extensively activated state during preeclampsia than during normal pregnancy. The increased platelet endothelial cell adhesion molecule-1 expression in preeclamptic patients demonstrates that, besides alpha-granular and lysosomal release, other hitherto unknown mechanisms are involved. Platelet endothelial cell adhesion molecule-1 appears to be the best marker to distinguish preeclamptic patients from normotensive pregnant women. Only a subpopulation of the platelets appears to be activated.     

Platelet/polymorphonuclear leukocyte interaction in dynamic conditions: evidence of adhesion cascade and cross talk between P-selectin and the beta 2 integrin CD11b/CD18

Adhesion between platelets and polymorphonuclear leukocytes (PMN) is a key event in thrombosis and inflammation. Double color fluorescence-activated cell sorter (FACS) analysis was used to determine the extent and kinetics of adhesion of thrombin-activated platelets to resting or activated PMN when mixed cell populations were incubated in dynamic conditions. Activated platelets bound very rapidly to PMN. Mixed cell conjugates reached a maximum at 1 minute and were reversible within 10 minutes. Platelet/PMN adhesion required both Ca2+ and Mg2+ and was markedly increased by the presence of Mn2+. The latter made mixed cell conjugates stable up to 10 minutes. Adhesion of platelets required metabolic activity of PMN and was abolished by tyrosine kinase inhibitors. Furthermore, adhesion of platelets to PMN resulted in binding of a monoclonal antibody (MoAb 24) known as beta 2 integrins "activation reporter." When PMN were activated by exogenous stimuli, the adhesion of platelets was markedly increased: fMLP induced a rapid and transient effect, while PMA resulted in a slower, but stable, increase in mixed conjugates formation. The hypothesis that activated PMN beta 2 integrins are able to bind a counter-receptor on platelets was directly demonstrated by the increase of mixed cell conjugates following PMN treatment with KIM127 and KIM185, two anti-CD18 antibodies able to induce the active conformation of beta 2 integrins. Consistently, two other anti-CD18, as well as an anti-CD11b inhibitory antibody abolished platelet/PMN adhesion. PMN beta 2 integrin activation was not the only mechanism for activated platelet/PMN adhesion to occur: indeed, this phenomenon could also be inhibited by two anti-P-selectin antibodies. Resting platelets did not adhere to resting PMN, but markedly adhered to fMLP- or PMA-activated PMN. Resting platelet/fMLP-activated PMN adhesion was abolished by anti-CD18 antibodies, but not by anti-P-selectin antibodies. In conclusion, activated platelet/PMN interaction can be modeled as an adhesion cascade involving a P-selectin-dependent recognition step and a functional signal. The latter proceeds through tyrosine kinase activation and enables a beta 2 integrin-dependent adhesion to a not yet identified counter-receptor constitutively expressed on platelet surface.     

Significance of the circadian fluctuation of estradiol, somatotropin, IGF I, prolactin, cortisol and DHEA-S for the body-shape of pre- and postmenopausal women

With 23 postmenopausal and 33 premenopausal females the interactions between circadianic secretion patterns of estradiol, growth hormone, IGF I, prolactin, DHEA-S as well as cortisol and the amount and distribution of subcutaneous body fat, estimated by using 10 absolute body measures and 10 anthropometric indices were tested. Premenopausal and postmenopausal women differed regarding the secretion patterns of estradiol and growth hormone significantly from each other. Furthermore it turned out, that the daily secretion rate, estimated by using the area under the curve, of growth hormone and estradiol correlated significantly with the amount and the distribution of body fat. In both proband groups more corpulent women had lower growth hormone levels and higher estradiol levels. The age dependent reduction of growth hormone secretion may be co-responsible for the general weight gain with increasing age. The reduced estrogen secretion however, seems to be the major determinant of the expression of a more masculine type of fat distribution during climacteric and after the menopause.     

The effects of a low-fat dietary intervention and tamoxifen adjuvant therapy on the serum estrogen and sex hormone-binding globulin concentrations of postmenopausal breast cancer patients

The purpose of the study was to determine the effect of a low-fat dietary intervention, with or without concomitant tamoxifen adjuvant therapy, on serum estrogen and sex hormone-binding globulin (SHBG) levels in postmenopausal patients with resected breast cancer. Ninety-three patients were randomized to either reduce their fat intake to 15-20% of total calories, or to a dietary control group. Serum estradiol, estrone, estrone sulfate, and SHBG concentrations were assayed at baseline, and at 6, 12, and 18 months thereafter. In 19% of patients, the preintervention serum estradiol levels were below the sensitivity of the assay (5 pg/ml). Tamoxifen had no significant effect on serum estrogen levels, but produced an elevation in SHBG. Patients with reliably quantifiable preintervention estradiol concentrations (> or = 10 pg/ml) showed a significant reduction in serum estradiol after 6 months on the low-fat diet (average, 20%; p < 0.005); this was sustained over the 18 month study period. Serum SHBG levels were increased by tamoxifen therapy, but were reduced significantly (p = 0.01) after 12 months on the low-fat diet in patients not receiving tamoxifen. No changes in serum estrone or estrone sulfate resulted from the dietary intervention. While the low-fat diet produced significant weight loss, patients treated with tamoxifen without dietary intervention showed a gain in body weight. These weight changes produced disruptions in the normal positive correlation between body weight and serum estrone sulfate, and the negative correlation with SHBG concentration.     

Platelet/polymorphonuclear leukocyte interaction: P-selectin triggers protein-tyrosine phosphorylation-dependent CD11b/CD18 adhesion: role of PSGL-1 as a signaling molecule

Polymorphonuclear leukocyte (PMN) adhesion to activated platelets is important for the recruitment of PMN at sites of vascular damage and thrombus formation. We have recently shown that binding of activated platelets to PMN in mixed cell suspensions under shear involves P-selectin and the activated beta2-integrin CD11b/CD18. Integrin activation required signaling mechanisms that were sensitive to tyrosine kinase inhibitors.1 Here we show that mixing activated, paraformaldehyde (PFA)-fixed platelets with PMNs under shear conditions leads to rapid and fully reversible tyrosine phosphorylation of a prominent protein of 110 kD (P approximately 110). Phosphorylation was both Ca2+ and Mg2+ dependent and was blocked by antibodies against P-selectin or CD11b/CD18, suggesting that both adhesion molecules need to engage with their respective ligands to trigger phosphorylation of P approximately 110. The inhibition of P approximately 110 phosphorylation by tyrosine kinase inhibitors correlates with the inhibition of platelet/PMN aggregation. Similar effects were observed when platelets were substituted by P-selectin-transfected Chinese hamster ovary (CHO-P) cells or when PMN were stimulated with P-selectin-IgG fusion protein. CHO-P/PMN mixed-cell aggregation and P-selectin-IgG-triggered PMN/PMN aggregation as well as P approximately 110 phosphorylation were all blocked by antibodies against P-selectin or CD18. In each case PMN adhesion was sensitive to the tyrosine kinase inhibitor genistein. The antibody PL-1 against P-selectin glycoprotein ligand-1 (PSGL-1) blocked platelet/PMN aggregation, indicating that PSGL-1 was the major tethering ligand for P-selectin in this experimental system. Moreover, engagement of PSGL-1 with a nonadhesion blocking antibody triggered beta2-integrin-dependent genistein-sensitive aggregation as well as tyrosine phosphorylation in PMN. This study shows that binding of P-selectin to PSGL-1 triggers tyrosine kinase-dependent mechanisms that lead to CD11b/CD18 activation in PMN. The availability of the beta2-integrin to engage with its ligands on the neighboring cells is necessary for the tyrosine phosphorylation of P approximately 110.     

Estradiol inhibits LDL oxidation: do the progestins medroxyprogesterone acetate and norethisterone acetate influence this effect?

Estrogen replacement therapy in postmenopausal women must be combined with progestin to avoid endometrial cancer. However, progestin addition could antagonize cardioprotective effects of estradiol. Therefore we investigated the effect of the two most commonly used progestins--medroxyprogesterone acetate (progesterone-derivative) and norethisterone acetate (nortestosterone-derivate)--alone and in combination with 17 beta-estradiol on copper-mediated oxidation of low density lipoprotein (LDL). Whereas 17 beta-estradiol alone inhibited the onset of LDL oxidation at the concentrations 0.5, 1.0, 5 and 10 microM, the progestins alone did not demonstrate any significant effect. In the estrogen-progestin combinations of 0.5 microM 17 beta-estradiol with 0.5, 1.0, 5 and 10 microM progestin, respectively, the estradiol effect was not changed. These results suggest that medroxyprogesterone acetate as well as norethisterone acetate do not counteract the beneficial effect of 17 beta-estradiol on LDL oxidation when used in hormone replacement therapy.     

Initial interactions of platelets and plasma proteins in flowing non-anticoagulated human blood with the artificial surfaces Dacron and PTFE

The purpose of the present study was to investigate and to compare the interactions of platelets and proteins in flowing non-anticoagulated human blood with the biomaterials polyethylene-terephthalate (Dacron) and polytetrafluoroethylene (PTFE, Teflon). The respective biomaterials were positioned in a parallel-plate perfusion chamber, and exposed to flowing blood for 5 min at wall shear rates characteristic for veins (100/s), medium sized (650/s) and moderately stenosed arteries (2,600/s). Blood-material interactions were morphologically quantified as platelet-surface adhesion, thrombus volume and fibrin deposition. Platelet adhesion to Dacron was highest at the lowest shear rate (13%) and decreased with increasing shear (4% at 2600/s). In contrast, platelet adhesion to PTFE was shear rate independent (17-19%), and significantly higher than the adhesion to Dacron at 2600/s (P < 0.05). A hallmark of the platelets adherent to PTFE and Dacron was the large percentage of platelets not spread out on the surface. This indicates that both materials were poor platelet activators, even though immunostaining demonstrated the adsorption of the platelet adhesive proteins von Willebrand factor and fibronectin. Adsorption of fibrinogen was also prevailing on both materials. Virtually no thrombi formed on Dacron, while a few small platelet thrombi were observed on PTFE. Less than 1% of the Dacron and PTFE surfaces were covered by fibrin, irrespective of the shear rate. Thus, Dacron and PTFE interact differently with flowing non-anticoagulated human blood, and Dacron is apparently the least thrombogenic material.     

A fifty percent reduction of platelet surface glycoprotein Ib does not affect platelet adhesion under flow conditions

Glycoprotein (GP) Ib is an adhesion receptor on the platelet surface that binds to von Willebrand Factor (vWF). vWF becomes attached to collagens and other adhesive proteins that become exposed when the vessel wall is damaged. Several investigators have shown that during cardiopulmonary bypass (CPB) surgery and also during platelet activation in vitro by thrombin or thrombin receptor activating peptide (TRAP) GPIb disappears from the platelet surface. Such a disappearance is presumed to lead to a decreased adhesive capacity. In the present study, we show that a 65% decrease in platelet surface expression of GPIb, due to stimulation of platelets in Orgaran anticoagulated whole blood with 15 micromol/L TRAP, had no effect on platelet adhesion to both collagen type III and the extracellular matrix (ECM) of human umbilical vein endothelial cells under flow conditions in a single-pass perfusion system. In contrast to adhesion, ristocetin-induced platelet agglutination was highly dependent on the presence of GPIb. Immunoelectron microscopic studies showed that GPIb almost immediately returned to the platelet surface once platelets had attached to collagen. In a subsequent series of experiments, we showed that when less than 50% of GPIb was blocked by an inhibitory monoclonal antibody against GPIb (6D1), platelet adhesion under flow conditions remained unaffected.     

Better postural balance in elderly women receiving estrogens

OBJECTIVE: The amount of bone mass and the tendency to fall are main risk factors for hip fractures and both deteriorate with advancing age. The dynamics between estrogen exposure and fracture protection seem too rapid to be explained by an effect on bone mass only. Postural balance function may be another potential mechanism for the fracture-protecting effect of estrogens. STUDY DESIGN: We examined 16 long-term users of 17 beta-estradiol implants (20 mg) (mean age 67.9 years and mean duration of treatment 17.3 years [3.3 to 34 years]) and 16 age-matched (+/-2 years) nonusers (mean age 68.3 years). Postural balance (sway velocity) was measured by static posturography before and after blindfolding and application of vibration stimulus (20 to 100 Hz) to the calf muscles to disturb the proprioception and to induce imbalance. RESULTS: Sway velocities were significantly lower in estrogen users than in nonusers (p = 0.0067) and similar to those in young premenopausal women. The differences were accentuated after provocation by blindfolding and by increasing frequencies of vibration stimulus to the calf muscle. Serum levels of estradiol and estradiol/sex hormone-binding globulin were negatively and follicle-stimulating hormone levels positively associated with sway velocity (p = 0.0194, p = 0.0036, and p = 0.0052, respectively) and independent of age (p = 0.02 to 0.005), supporting causality between estrogen exposure and postural balance. CONCLUSIONS: These data indicate that postural balance function is better preserved in long-term estrogen users than in nonusers. Effects on postural balance function may be one mechanism explaining the rapid increase in distal forearm fractures early after menopause and the rapid dynamics between estrogen exposure and hip fracture protection and may potentially reduce the fracture risk in elderly women starting estrogen replacement therapy in spite of marginal increases in bone mass.     

Double level fractures of the femur treated with closed intramedullary nailing

Breast cancer patients receiving tamoxifen (Tam) are at an increased risk for developing endometrial carcinomas, possibly due to the partial estrogenic effect of Tam on endometrial cells. Progestational therapy has not routinely been included in Tam regimens. It was our aim to determine the presence of estrogen receptors (ERs) and progesterone receptors (PRs) in normal and abnormal endometria from postmenopausal women with breast cancer who were treated with Tam. Standard immunohistochemical staining of ERs and PRs was performed on paraffin sections from formalin-fixed uterine curettings or hysterectomy specimens from 40 patients who had received 20-40 mg of Tam daily for a minimum of 3 months. For comparison, normal endometria from 20 women who had not received Tam (11 premenopausal, 9 postmenopausal) were also studied for ER and PR expression. Staining was evaluated using semiquantitative immunoreactivity scores (IRS) ranging from 0 (negative) to 12 (strongly positive). In the group of patients receiving Tam, ERs and PRs were detected in the nuclei of glandular cells in 24/24 cases of endometrial atrophy (ER/PR-IRS, 2-12), in 8/8 endometrial polyps (ER-IRS, 6-12; PR-IRS, 4-12), in 4/4 adenomatous endometrial hyperplasias (ER-IRS, 3-8; PR-IRS, 1-12), and in 4/4 well-differentiated endometrioid adenocarcinomas (ER-IRS, 2-12; PR-IRS, 6-8). Of the 11 endometria from premenopausal patients who had not received Tam, 8 were ER+/PR+ (ER-IRS, 1-12; PR-IRS, 1-12), 1 was ER+/PR- (ER-IRS, 3; PR-IRS, 0), 1 was ER-/PR+ (ER-IRS, 0; PR-IRS, 2), and 1 was ER-/PR- (ER/PR-IRS, 0). Among 9 atrophic endometria from women not treated with Tam, 6 were ER+/PR+ (ER-IRS, 4-12; PR-IRS, 3-6), 1 was ER+/PR- (ER-IRS, 4; PR-IRS, 0), and 2 were ER-/PR- (ER/PR-IRS, 0). The consistent finding of ER and PR expression in endometria from postmenopausal women receiving Tam further supports the suspected estrogenic effect exerted by Tam on endometrial cells. Progestational therapy could be beneficial in the prevention of Tam-induced abnormal endometrial proliferations.     

Effects of hormonal replacement therapy on plasma sex hormone-binding globulin, androgen and insulin-like growth factor-1 levels in postmenopausal women

Plasma sex hormone-binding globulin (SHBG) levels are important in the regulation of plasma free and albumin-bound androgens and estrogens. In postmenopausal women associated to the decrease of estrogen production, a decrease of plasma SHBG levels occurs. Hormone replacement therapy (HRT) in postmenopausal women modulates plasma SHBG levels, in relationship with the different regimens and routes of administration. The present study aimed to compare the effect of different HRT on plasma SHBG levels in relationship with the changes of plasma androgen [dehydroepiandrosterone sulphate (DHEAS), testosterone (T), androstenedione (A)] and insulin-like growth factor-1 (IGF-1) levels. In a retrospective study 443 postmenopausal women were studied and divided into 2 groups. The group 1 (n = 170) was subdivided in 4 groups of women as follows: A) treated with transdermal 17-beta estradiol + medroxyprogesterone acetate, B) treated with oral conjugated estrogens, C) treated with sequential HRT (estradiol valerate (EV) + norgestrel), and D) treated with a combined HRT (micronized estradiol (E2) + noretisterone acetate). Women of group 2 (n = 273) did not receive HRT and served as controls. All groups of women treated with different HRT showed plasma estradiol levels significantly higher than controls (p < 0.01), showing the highest values in women treated with oral HRT. Plasma SHBG levels were not significantly different between patients treated with transdermal 17-beta estradiol + medroxyprogesterone acetate and controls. On the other hand, all the groups of patients treated with oral conjugated estrogen with or without progestagens showed plasma SHBG levels significantly higher than controls (p < 0.01). Plasma SHBG levels were higher in the group treated with estrogen alone than in groups of women treated with sequential or combined HRT. Plasma DHEAS, T and A levels in patients treated with different HRT regimens were in the same range of levels as control women. Plasma IGF-1 levels were not significantly affected by the various HRT regimens and remained in the same range as controls. In conclusion, plasma SHBG levels increase following oral HRT while are not affected by transdermal HRT. Plasma IGF-1 and androgen levels are not influenced from oral or transdermal HRT.