376 SPO Abstracts

360 ARACHIDONIC ACID APPEARS TO CAUSE RELAXATION OF PLACENTAL ARTERIES AND VEINS VIA A CYfOCHROME P-450 METABOLITE. R. Figueroa, HA OmarX, N. Tejani and M.S. Wolinx, Depts. Physiol. & Ob/Gyn, New York Medical College, Valhalla, NY

Isolated endothelium-intact ( + E) and endothelium-denuded (-E) human placental arteries (PA) and veins (PV) of 1-2 mm dIameter obtained from normal term deliveries and precontracted with PGF2,a were found to undergo an endothelium­independent relaxation of 40-50% and 60-70%, respectively, when exposed to micromolar concentratIOns of arachidonic acid (AA). This relaxation (e.g. @ 10 ~ M AA P A + E = 37± 8% (n=7) & PV + E = 61±6% (n=6», was not altered by pretreatment with the inhibitor of prostaglandin production, 1(l£ M indomethacin (P A + E = 46± 9%, PV+E = 59±15%), but was significantly (p<O.05) reduced (from PA+E = 49±11% (n=7), PV+E = 65±8% (n=8) @ 10 ~M AA) by pretreatment with an inhibitor of cytochrome P450, 3(l£ M SKF525A (PA+E = 26±4% & PV+E = 27±4%), suggestive of AA metabolism via.the epoxygenase/monooxygenase pathway. Thus, in HP A and HPV the relaxation to exogenous AA seems to be mediated by metabolites formed via cytochrome P450-linked enzymes. This mechanism could help prevent vasospasm in the placental circulation.

361 COCAINE METABOLISM DURING PREGNANCY IN MATERNAL, PLACENTAL, AND FETAL COMPARTMENTS: AN IN VIVO ANIMAL MODEL. R. William Stettler. M.D., +, Van R. Bohman, M.D.: Donna I. Standard, B.S.: K.L. Westfall, M.S.: Bertis B. Little, Ph.D! Dept. of Ob/Gyn, The University of Texas Southwestern Medical Center, Dallas, Texas.

Others have shown rodent fetuses can metabolize cocaine (C) to norcocaine (NC), and human placentae transform C to ecgonine methyl ester (EME). This implies that placentae possess cholinesterase activity (CA), and term rodent (parallel to human second trimester) fetal livers have N-demthylase. EME and NC were not previously quantitated in a single study. It is unknown whether: (1) EME crosses to the fetus, or if (2) the fetus possesses CA. We studied this in rats given C (25 mg/kg) on day 18 of gestation. Four animals were sacrificed at each time period (0, 25, 45, 90, and 135 min. post-IV injection). Maternal and fetal tissues (liver, kidney, brain, heart), placentae, and maternal blood were collected at sacrifice. C, EME and NC levels were analyzed by gas chromatography. C metabolized to NC and EME in the mother, and both were found in placentae. Fetal tissues contained NC and C, but only trace amounts of EME. Fetal liver NC levels increased over time. This implies: (1) fetal liver produces NC and (2) EME and NC only minimally transfer across placenta, perhaps due to high polarity. Thus, C metabolism is different in mother and fetus, likely due to immature fetal enzyme complement. NC in fetus has clinical implications: (1) NC was higher in fetal brain over time, (2) NC is 9-fold more active than C, and (3) fetal brain growth retardation is associated with cocaine abuse.

January 1992 Am J Obstet Gynecol

362 T CELL DEVELOPMENT IN THE HUMAN FETAL THYMUS: AN IN VITRO MODEL JP Smithx, CK Walker, WC Hyunx, DY Landers, Dept. Ob/Gyn and Reprod. Sci~ University of California at San Francisco General Hospital, San Francisco, California

Objective: Current knowledge of T cell development in the fetal thymus has been largely derived from murine studies. Studies of the human fetal thymus has been limited by the difficulty in obtaining specimens. This system was developed to study human fetal thymocyte maturation in vitro. Methods: We studied six human fetal thymuses, IS to 22 weeks gestation. Single cell suspensions were co-cultured with an EBV transfonned B cell line as an allogeneic stimulus. Cell surface antigens, CD3 (pan T cell marker), CD4 (helperfmducer), CDS (supressor/cytotoxic), IL-2R (activation) and T cell receptor (TCR), were analyzed by flow cytomebic analysis at days 0, 2, 5, and 7. Results: The majority of thymocytes expressed the characteristic double positive (CD4/CDS) precursor T cell fonn. At this point in development 2.5% of the cells expressed IL-2R and 35% expressed the TCR. After 7 days in vitro the thymocytes lost the immature double positive expression and developed into either CD4+/CDS- or CD4-/CDS+ phenotypically mature T cells. By day 7 expression of IL-2R and TCR was 79% and 90%, respectively. Conclusion: Although the cells were not subjected to positive and negative selection which occurs in the thymus before release into the periphery, this in vitro system parallels the in vivo phenotypic maturation processes. This system may prove useful in studying the effects of infectious agents (i.e., my) on fetal T cell development

363 DO PATIENTS WITH A HISTORY OF RECURRENT ABORTION (RA) HAVE SOME UNDERLYING IMMUNOLOGICAL ABNORMALITY? M ~+, R Wilson+, C Jenkins+, S H Miller+", JA Thomson+, JJ Walker. Departments of Obstetrics and Medicine, Glasgow Royal Infirmary, Scotland, UK.

We have shown that compared to healthy pregnant women, patients w~h a history of RA have a number of immunological abnormalities. As it is not known whether these changes are triggered by the pregnancy we have investigated 5 patients with a history of RA prior to and following confirmation of their pregnancy. The results show that while there was no sign~icant difference pre and post pregnancy all parameters differed significantly from a group of healthy controls (n = 25).

PRE PREG POST PREG

3H THYMIDINE X 103CPM C PWM PHA

0.3 15.4 27.3

0.5 17.0 31.1

B CELLS CYTOTOXICITY CON A Ig %51Cr 23.2 1373 35.0

24.7 1407 36.8

CONTROL 2.1" 34.5 52.0" 46.9' 844" 23.2" •• P < 0.002 'P < 0.02

Mixed lymphocyte reactions carried out between the 5 women and their partners showed activity to be significantly reduced compared to controls (76 + 28 vs 118 + 25% p<0.03)), suggesting there are a number of common antigens between the partners. Conclusions. These results would suggest that in women with RA there is some underlying immunological abnormal~y which is present prior to the pregnancy.