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.

Birth weight-length ratios, ponderal indexes, placental weights, and birth weight-placenta ratios in a large population

BACKGROUND

Birth weight (BW)/length ratios, ponderal indexes, placental weights, and BW/placental weight ratios have been correlated with perinatal morbidity and mortality.

METHODS

Cross-sectional survey of live-born, structurally normal, singleton neonates delivered at a tertiary care center in Detroit, Mich, from 1984 through 1991. Subjects were included if dating based on menstrual dates and ultrasonographic estimations agreed with Ballard examination to within 2 weeks.

RESULTS

Of 33,138 neonates, 26,983 (81.4%) were black. While all indexes significantly increased with advancing gestational age, only placental weights (without prior draining of blood, blotting the placenta dry, or trimming the membranes or cord) and BW/length ratios significantly increased beyond 40 weeks' gestation. Multivariate analysis of variance revealed that placental weights, BW/placenta ratios, and BW/length ratios were significantly related to gender and ethnicity, but ponderal index was not. Placental weights were larger, and BW/placenta ratios were smaller than studies that trimmed the placentas before weighing.

CONCLUSIONS

All indexes were gestational age dependent, but ponderal index and BW/placenta ratios do not increase beyond 40 weeks' gestation. Except for ponderal index, interpretation of these indexes should be specific for ethnicity, gender, and manner of placental preparation.

Platelet activating factor-acetylhydrolase activity following chorionic villus sampling and amniocentesis

OBJECTIVE

Platelet activating factor (PAF) is essential for embryonic development and is a potent vasodilator. It increases vascular permeability and stimulates prostaglandin E2 (PGE2) production. Platelet activating factor-acetylhydrolase (PAF-AH), the enzyme that degrades PAF, is synthesized by decidual macrophages. The aim of this study was to test the hypothesis that chorionic villus sampling (CVS) and/or amniocentesis might cause an increase in maternal PAF-AH activity.

METHODS

Maternal plasma PAF-AH activity was evaluated before and after genetic amniocentesis (N = 13) and transcervical CVS (N = 29). A control group (N = 9) was evaluated to study the effects of venipuncture.

RESULTS

Chorionic villus sampling caused a significant elevation in PAF-AH activity (P < .0005). No changes were noted in PAF-AH activity in the amniocentesis or the control group.

CONCLUSIONS

Chorionic villus sampling causes subclinical release of PAF-AH, possibly from the decidual macrophages. Increased PAF-AH activity might result in decreased PAF levels, which might lead to vasoconstriction in the placental circulation due to lack of the vasodilator effects of PAF and possibly PGE2. This mechanism might explain the increased risk for fetal limb reduction noted with CVS performed at very early gestational ages.

A gestational-age-independent model of birth weight based on placental size

A placental weight (P) to birth weight (W) relationship, W = P1.5 x constant (A), was presented in 1966. However, based on histological and theoretical studies, placental efficiency increases proportionally to the square of the gestational age in weeks. The purpose of this study was to develop and validate a gestational-age-independent model of birth weight based on P2. Data were prospectively entered into a computerized database for liveborn, structurally normal neonates at a tertiary, urban center. 29,989 neonates had gestational ages based on menstrual dating, ultrasound and Ballard examination, 81.4% were African American. The 'best fit' of W = A x P1.5 had errors in predicting the mean birth weight by at least 10% from 24 to 33 weeks of gestation. In contrast, there was significant improvement (p < 0.05) when the model W = 0.0071 x P2 was used; errors of greater than 10% only occurred at 28 and 43 weeks of gestation. This model had similar accuracy when stratified according to gender or ethnicity. A gestational-age-independent model of mean birth weight can be based upon the square of placental weight. We hypothesize that this model may have utility in understanding disorders of intrauterine fetal growth.

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.

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 patient's 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.

A comparative study of two low-dose combined oral contraceptives: results from a multicenter trial

A comparative multicenter clinical trial of two low-dose combined oral contraceptives (OCs) was conducted in Malaysia, Egypt, Thailand, and Mexico. Efficacy, safety and acceptability were investigated in women taking either a norgestrel-based (NG) OC or a norethindrone acetate-based (NA) OC. This paper includes analysis of 892 women, all of whom were at least 42 days but within 26 weeks postpartum and randomly allocated to one of the above OCs. Follow-up visits were scheduled at 1, 4, 8 and 12 months after admission. Baseline sociodemographic characteristics were similar for both groups, as well as compliance. There were nine unintended pregnancies reported; eight of these occurring in the NA group. Adverse experiences were minor with headaches and dizziness being the most common complaints; frequency of reports was similar in both groups. The group taking the NG-based OC had significantly (p < .05) fewer menstrual-related complaints. Discontinuations due to menstrual problems were significantly more common among NA users (primarily amenorrhea). Discontinuations in the NG group were primarily for other personal reasons, e.g. unable to return to the clinic. There was also a significant difference between the two groups for the 11-month gross cumulative life table discontinuation rates due to menstrual problems (p < .01); the NA group had the higher rate.

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.

Amniotic fluid platelet factor 4 and beta-thromboglobulin

Platelet activating factor (PAF), a powerful platelet activator, has been identified in human embryos and fetuses, and may induce fetal lung maturation. The potential effect of PAF on fetal platelets as indicated by release of beta-thromboglobulin (BTG) and platelet factor 4 (PF4) has not been investigated. We measured BTG and PF4 in amniotic fluid from 78 genetic and 35 pulmonary maturity amniocenteses. BTG and PF4 were higher in the genetic amniocentesis samples (p < 0.001 in each case) than in the lung maturity samples. BTG and PF4 did not correlate with the pulmonary maturity parameters as measured by the lecithin to sphingomyelin ratio and phosphatidylglycerol concentration. Our findings suggest a fetal origin of BTG and PF4 in amniotic fluid.

Markers for endothelial injury, clotting and platelet activation in preeclampsia

The 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 beta-thromboglobulin (beta TG) 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 less than 0.0001, less than 0.05 and less than 0.01, respectively). beta TG, 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, beta TG, Pf4, suggests that endothelial injury is a more basic mechanism of preeclampsia than clotting or platelet activation.

Neonatal morphometry. Relation to obstetric, pediatric, and menstrual estimates of gestational age

OBJECTIVE

To determine gestational age-dependent neonatal morphometrics based on last menstrual periods (LMPs), Ballard examinations, and obstetric estimates of gestational age.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional survey of 38,818 live-born neonates at a tertiary care center in Detroit, Mich.

SELECTION PROCEDURES

Consecutive sample of all viable, structurally normal, singleton neonates delivered at Hutzel Hospital from 1984 through 1991.

MEASUREMENTS/MAIN RESULTS

Neonatal weights, lengths, and head circumferences were recorded at birth. Gestational age-dependent morphometrics were based solely on LMPs and compared with those based on obstetric estimates (using LMPs corrected by fetal ultrasound). Ballard examination had an 85.4% concurrence (within 14 days) with obstetric estimates of gestational age, but only a 69.9% (P less than .0001) agreement with LMP. Dating only by LMP significantly overestimated the prevalence of prematurity (odds ratio [OR], 1.3; 99% confidence interval [CI], 1.3 to 1.4) and postmaturity (OR, 5.0; 99% CI, 4.6 to 5.4), distorting apparent growth patterns, especially for preterm neonates. In contrast to previous studies based solely on LMPs, morphometric measurements increased beyond 40 weeks when dated by obstetric estimates.

CONCLUSIONS

Gestational age-dependent neonatal morphometrics should not be based solely on LMPs.

Cascaded, stagger-tuned, broadband, low-ripple optical amplifiers

We show theoretically that the gain spectrum obtained by cascading two or more semiconductor optical amplifiers can have a ripple amplitude that is significantly smaller than that currently attainable with a single stage of optical amplification. For example, by cascading two stagger-tuned amplifiers, each having 10 dB of coupling loss and facet reflectivities of 10(-3), one can achieve a net (fiber-to-fiber) gain of 30 dB with less than 2 dB of ripple amplitude. We also show that, under some conditions, simple cascading of optical amplifiers, without the stagger tuning and associated control, can lead to low-ripple, high-gain optical amplification.

Hemostasis in hypertensive disorders of pregnancy

We studied parameters of hemostasis reported to be altered with "pure" preeclampsia in hypertensive disorders of pregnancy. Plasma fibronectin, antithrombin, and alpha-2 antiplasmin were measured in normal pregnancies (N = 26) and in pregnancies complicated by preeclampsia (N = 19), hypertension (N = 11), and chronic hypertension with superimposed preeclampsia (N = 11). Preeclampsia, both pure and superimposed, was associated with high fibronectin (P less than .001), low antithrombin III (P less than .001), and low alpha-2 antiplasmin (P less than .05) levels, suggesting endothelial injury, clotting, and fibrinolysis, respectively. Alpha-2 antiplasmin was increased with chronic hypertension (P less than .001), regardless of whether there was superimposed preeclampsia. Fibronectin appeared to be more closely linked with preeclampsia than antithrombin III or alpha-2 antiplasmin and may prove valuable in detecting preeclampsia when evaluating hypertension in pregnancy.

Effect of some recent analgesics on labor pain and maternal and fetal blood gases and pH

This study attempts to determine the analgesic properties of nalbuphine, pentazocine and butorphanol during labor and their potential effects on maternal and fetal blood gases and pH. Butorphanol analgesia was superior to either nalbuphine or pentazocine in relieving labor pain. The studied analgesics caused significant maternal respiratory acidosis and fetal metabolic acidosis. These acidotic changes were most marked with pentazocine, moderate with nalbuphine and minimal with butorphanol.

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.

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.

Potential anticancer agents, XI. X-ray structure determination of acantholide

The X-ray structure of acantholide, a melampolide sesquiterpene lactone from Acanthospermum glabratum (DC.) Willd. was determined by the aid of direct methods. The compound was cytotoxic but displayed no antitumor activity. Evaluation of the X-ray and NMR data indicated that the same conformation exists in the solid state as in solution.

Oncogenic and tumor-promoting Spermatophytes and Pteridophytes and their active principles

A survey and discussion are presented of plants classified as Spermatophyta and Pteridophyta, extracts of which have been shown to be oncogenic or tumor-promoting in animals. The active oncogenic and tumor-promoting principles, where known, have been identified. They represent tannins; pyrrolizidine, indole, tropolone, quinoline, purine, and benzophenanthridine alkaloids; nitroso compounds; triterpene glycosides; lignans; isoflavans; allyl benzenoids; simple (nu-pyrenes; and carbocyclic hydroxy acids. A total of 28 compounds of known structure have been identified as oncogens and several phorbol esters as tumor-promoters. Plants known to contain any of the 28 oncogens (excluding shikimic acid and caffeine) have been tabulated; they represent at least 454 species, 110 genera, and 34 families of Spermatophyta and Pteridophyta.

Modification of diffusion rates of benzocaine from topical vehicles using sodium salicylate as complexing agent

The release of benzocaine from various topical vehicles containing benzocaine, alone and in the presence of a complexing agent, sodium salicylate, was measured at 37 degrees using dialysis through a cellulose membrane. Sodium salicylate had a marked effect on the release of benzocaine, depending upon the the type of vehicle, with the largest increase observed for the water-miscible base, polyethylene glycol (macrogol ointment BPC). The amount of drug released from preparations containing 1% (w/w) and 2% (w/w) benzocaine in this vehicle depended upon the sodium salicylate concentration. Results are discussed in terms of the differing physical properties of the complexes formed.

Guidance of surface waves by multilayer coatings

A periodic sequence of layers with alternately high and low refractive indices can guide loosely bound surface waves parallel to the layers. Most of the power flows in free space, and, thus, the losses may be considerably smaller than the bulk losses of the dielectric materials used. Possible applications are briefly discussed.