Abdelaziz A. Saleh

Hyperinsulinemia and insulin resistance are associated with preeclampsia in African-Americans

There is evidence that hyperinsulinemia and insulin resistance play a role in the development of hypertension. Accordingly, in our ongoing longitudinal study of pregnancy-induced hypertension, we have measured fasting levels of insulin and glucose at 18 to 25 weeks gestation in 140 nulliparous African-American women followed prospectively to delivery. To test the hypothesis that hyperinsulinemia may be related to the development of preeclampsia, discriminant analysis of mean arterial pressure (MAP), fasting plasma insulin levels, insulin to glucose ratios, and left lateral forearm vascular resistance were examined as predictors of preeclampsia. Statistical analysis controlled for two factors known to be related to insulin levels, gestational age and pregestational body mass index. Gestational hypertensives were not different with regard to blood pressure and metabolic factors from normals and thus were placed in the control group. Women who subsequently developed preeclampsia had mean (+/- SE) fasting plasma insulin levels of 51.0 +/- 12.0 microU/mL at 20 weeks and controls had values of 29.0 +/- 2.8. Only MAP [F(4,135) = 8.8, P < .01] and insulin [F(1,135) = 6.5, P < .05] were related to the development of preeclampsia [F(4,135) = 4.39, R2 = 11.5%]. The finding that elevated second-trimester insulin levels characterize the subsequent development of preeclampsia with control for increased MAP supports the hypothesis that hyperinsulinemia and associated insulin resistance may contribute to the pathogenesis of preeclampsia.

Preeclampsia, delivery, and the hemostatic system

To determine the effects of preeclampsia and delivery, the hemostatic system was evaluated before and 24 to 48 hours after delivery in 59 nulliparous patients without clinical signs of disseminated intravascular coagulation. Fifteen patients with mild preeclampsia and 18 with severe preeclampsia were compared with 26 pregnant control patients. Preeclampsia was associated with high fibronectin (p less than 0.001), low antithrombin III (p less than 0.001), and low alpha 2-antiplasmin (p less than 0.005), suggesting endothelial injury, clotting, and fibrinolysis, respectively. After delivery, fibronectin decreased only in preeclamptic patients (p less than 0.005); alpha 2-antiplasmin increased in all groups (p less than 0.001). Endothelial injury in preeclampsia appeared to resolve soon after delivery, which could contribute to the rapid clinical improvement noted in the early puerperium.

Thrombosis and hormone replacement therapy in postmenopausal women.

OBJECTIVE The effects of postmenopausal hormone replacement therapy on thrombosis remain controversial. We tested the hypothesis that estrogen or progesterone has no significant effect on thrombosis by means of newly developed markers of blood clotting, specifically prothrombin fragment 1 + 2, a marker of factor Xa generation, and thrombin-antithrombin III complex, a marker of thrombin generation. STUDY DESIGN A prospective study that included 106 women, 68 postmenopausal women on hormone replacement therapy and 38 postmenopausal controls, was performed. Plasma levels of prothrombin fragment 1 + 2 and thrombin-antithrombin III complex were measured by enzyme-linked immunosorbent assay. Multivariate analysis of the covariance was used for statistical analysis, controlling for patients age because the hormone replacement therapy group was older. RESULTS There were no statistically significant differences between the hormone replacement therapy and control groups in either of the clotting parameters measured. A comparison of the levels of prothrombin fragment 1 + 2 and thrombin-antithrombin III complex in patients receiving estrogen alone or estrogen plus progestin also revealed no differences. CONCLUSIONS Current doses of postmenopausal hormone replacement therapy do not appear to enhance in vivo clotting. Thromboembolic complications among postmenopausal women receiving hormone replacement therapy may therefore be secondary to congenital or other acquired coagulation defects.

Markers for endothelial injury, clotting and platelet activation in preeclampsia

SummaryThe etiology of disseminated intravascular coagulation (DIC) in preeclampsia is not well understood. We measured plasma levels of fibronectin (FN), which may reflect endothelial cell injury, fibrinopeptide A (FPA), a specific marker of clotting, platelet counts (PLC) and mean platelet volumes (MPV), as well as β-thromboglobulin (βTG) and platelet factor 4 (Pf4), products of irreversible platelet activation in 24 preeclamptic patients and 24 controls matched for age, gestational age, labor status, and parity. In preeclampsia, FN and FPA were significantly elevated while PLC were significantly decreased (P<0.0001, <0.05 and <0.01, respectively). βTG, Pf4, and MPV values did not show significant differences. These findings support the hypothesis that endothelial injury, clotting activation and platelet consumption are increased in preeclampsia. However, the much closer association of preeclampsia with FN levels as compared to FPA, βTG, Pf4, suggests that endothelial injury is a more basic mechanism of preeclampsia than clotting or platelet activation.

Fibrinolytic parameters in women undergoing ovulation induction

OBJECTIVE The purpose of this study was to evaluate the effect of elevated levels of circulating estradiol on the clotting and fibrinolytic system in patients undergoing controlled ovarian hyperstimulation. STUDY DESIGN Fifty-two patients undergoing controlled ovarian hyperstimulation with human menopausal gonadotropins or urofollotropin were asked to participate. Blood for hemostasis parameters was obtained on the days that patients returned for estradiol sampling. Sample days were identified as cycle days 1 to 5 (baseline), 6 to 9, and 10 to 14. Each factor was analyzed by repeated-measures analysis of variance and correlation analysis. RESULTS A significant decline was observed for tissue plasminogen activator antigen and plasminogen activator inhibitor type 1 activity from baseline to cycle days 10 to 14. As serum estradiol levels increased throughout each phase (maximum mean estradiol 739.8 pg/ml), a significant linear decrease was observed for both tissue plasminogen activator antigen and plasminogen activator inhibitor type 1 activity, whereas thrombin-antithrombin III complexes did not change significantly. A significant positive correlation was also observed for plasminogen activator inhibitor activity and tissue plasminogen activator antigen level over all cycle days examined. CONCLUSION Down-regulation of the fibrinolytic system was observed as estradiol levels increased. However, thrombin formation did not change, thus suggesting that elevated circulating estradiol alone does not predispose to a thromboembolic event.

Mechanisms for reduced colloid osmotic pressure in preeclampsia

The determinants of plasma colloid osmotic pressure were studied in 32 patients with preeclampsia and their matched control subjects. Although plasma colloid osmotic pressure was significantly related to preeclampsia, its severity, and proteinuria, it was most highly correlated with an elevated fibronectin level, suggesting that endothelial injury, rather than proteinuria, is the major mechanism of reduced colloid osmotic pressure in preeclampsia.

Hemostasis and diagnosis of preeclampsia.

The diagnosis of preeclampsia, with all of its consequences, is at times difficult to establish, especially when the patient has underlying chronic hypertension and is not known from prior prenatal care visits. Many screening tests have been proposed. These should be sensitive, relatively specific, easy to perform, of low cost, and have a reasonable interval from prediction to disease onset. Laboratory assays would obviously be useful. We evaluated hemostasis tests for the diagnosis of preeclampsia, and compared fibronectin, antithrombin III and alpha 2-antiplasmin in 48 preeclamptics and 86 control nulliparas. Receive operator characteristic (ROC) curve analysis suggested that fibronectin is the most effective of these tests. A similar analysis comparing the results of previous studies using serum iron, angiotensin infusion, urinary calcium/creatinine ratio, the rollover test and uric acid suggested a possible role for fibronectin in the diagnosis of preeclampsia. While not ideal, there seems to be, at present, no other, easy to perform laboratory test that outperforms fibronectin in predicting preeclampsia.

TAT complexes and prothrombin fragment 1+2 in oral contraceptive users

A group of 56 women on OCs and a control group of 47 women not taking OCs were studied. The mean time of OC use was 4.2 + or - 4.1 years. 38 patients took triphasic pills (Orthonovum 777 [35 mcg ethinyl estradiol] or Triphasal [30 40 30 mcg ethinyl estradiol]) 11 took low-dose estrogen combination products and 7 took Ovral (50 mcg ethinyl estradiol). Blood plasmas were separated for batch analysis. The effect of these OCs was tested on 2 newer molecular markers of in vivo clotting activation using commercially available kits: Thrombin-Antithrombin III (TAT) complexes and Prothrombin Fragment 1+2 (F 1+2). TAT complexes form when thrombin is generated in vivo and bound to antithrombin III. Elevated plasma levels suggest increased in vivo thrombin generation. F 1+2 represents the NH2 terminal part of the prothrombin molecules that does not contain the thrombin moiety. Elevated plasma levels suggest the formation of thrombin. The normal levels of TAT complexes range from 1.0 to 5.0 mcg/L with no sex differences. Normal F 1+2 levels range from 0.36 to 0.95 nMol/L. Females have higher values (0.64 + or - 0.19) than males (0.46 + or - 0.15). While the mean age between the 2 study groups was significantly different (p 44 years). The control group was significantly older (36 + or - 12) than the OC user group (25 + or - 5) yet their F 1+2 levels were not different. OCs do not seem to affect the hemostasis system directly however those women who develop thromboembolic complications while on oral contraceptives might have congenital or acquired hemostasis defects predisposing them to thromboembolism.

Amniotic Fluid Acetylcholinesterase Is Found in Gastroschisis but Not Omphalocele

Amniotic fluid acetylcholinesterase (ACHE) has been used to evaluate neutral tube defects. It has also been detected in ventral wall defects. However, the role of ACHE to differentiate between omphalocele and gastroschisis has not been established. We examined amniotic fluid ACHE in 16 pregnancies complicated by gastroschisis and 8 by omphalocele. One ruptured omphalocele was excluded. ACHE was negative in all 7 omphaloceles and either positive or suspicious in all gastroschises (chi 2 = 17.3, p < 0.0001). Amniotic fluid ACHE may be useful to differentiate between omphalocele and gastroschisis.

Amniotic Fluid Platelet Factor 4 and Beta-Thromboglobulin as Markers of Structural Abnormalities

Platelet factor 4 (PF4) and beta-thromboglobulin (BTG) are unique markers of irreversible platelet activation. We measured PF4 and BTG in amniotic fluid from 102 genetic amniocenteses, in which 78 had normal amniotic fluid alpha-fetoprotein (AFP) levels with normal pregnancies, and 24 had high amniotic fluid AFP levels with abnormal pregnancies. PF4 and BTG were significantly higher in the abnormal pregnancy/elevated amniotic fluid AFP group (p < 0.002 in each case) and correlated with AFP expressed as multiples of the median (p < 0.05 and p < 0.0001, respectively). Our results are compatible with passage of PF4 and BTG across fetal membranes and/or enhanced fetal platelet activation in fetuses with structural anomalies and elevated AFP.