Early events in human T cell ontogeny. Phenotypic characterization and immunohistologic localization of T cell precursors in early human fetal tissues.

During early fetal development, T cell precursors home from fetal yolk sac and liver to the epithelial thymic rudiment. From cells that initially colonize the thymus arise mature T cells that populate T cell zones of the peripheral lymphoid system. Whereas colonization of the thymus occurs late in the final third of gestation in the mouse, in birds and humans the thymus is colonized by hematopoietic stem cell precursors during the first third of gestation. Using a large series of early human fetal tissues and a panel of monoclonal antibodies that includes markers of early T cells (CD7, CD45), we have studied the immunohistologic location and differentiation capacity of CD45+, CD7+ cells in human fetal tissues. We found that before T cell precursor colonization of the thymus (7-8 wk of gestation), CD7+ cells were present in yolk sac, neck, upper thorax, and fetal liver, and were concentrated in mesenchyme throughout the upper thorax and neck areas. By 9.5 wk of gestation, CD7+ cells were no longer present in upper thorax mesenchyme but rather were localized in the lymphoid thymus and scattered throughout fetal liver. CD7+, CD2-, CD3-, CD8-, CD4-, WT31- cells in thorax and fetal liver, when stimulated for 10-15 d with T cell-conditioned media and rIL-2, expressed CD2, CD3, CD4, CD8, and WT31 markers of the T cell lineage. Moreover, CD7+ cells isolated from fetal liver contained all cells in this tissue capable of forming CFU-T colonies in vitro. These data demonstrate that T cell precursors in early human fetal tissues can be identified using a mAb against the CD7 antigen. Moreover, the localization of CD7+ T cell precursors to fetal upper thorax and neck areas at 7-8.5 wk of fetal gestation provides strong evidence for a developmentally regulated period in man in which T cell precursors migrate to the epithelial thymic rudiment.

Hypoxia and lactate production in trophoblast cells.

The etiology of preeclampsia is unknown but is thought to be related to hypoxia in the placenta. We previously reported that the enzyme lactate dehydrogenase (LDH) has increased activity and gene expression in placentas from preeclamptic pregnancies [Tsoi SCM, Zheng J, Xu F, Kay HH. Differential expression of lactate dehydrogenase isozymes (LDH) in human placenta with high expression of LDH-A(4) isozyme in the endothelial cells of pre-eclampsia villi. Placenta 2001;22:317-22]. LDH is responsible for pyruvate conversion to lactate through glycolysis. In this study, we further investigated the role of hypoxia in primary trophoblast cells and a cultured cell line, JEG3 cells, to obtain a better understanding of how it affects the activities of lactate dehydrogenase, lactate production and regulatory genes, as a possible model for preeclampsia. Primary trophoblast cells and JEG3 cells were cultured under 1% oxygen. At 6, 12 and 24h, cells were analyzed for LDHA and LDHB isozyme activities, mRNA and protein expression compared to standard culture conditions. Lactate was measured from cell medium. The hypoxia inducible transcription factor (HIF-1alpha) protein expression was confirmed by western blot. Two lactate transporters (MCT1 and MCT4) mRNA and protein expression were also studied under hypoxia. Finally, lactate was measured in plasma obtained from patients with severe preeclampsia. Under hypoxic conditions, LDHA mRNA is increased in primary trophoblast cells and JEG3 cells. The HIF-1alpha protein expression is higher in hypoxia-treated JEG3 cells than control. LDHA isozyme activity and its protein expression are increased most significantly at 24h of culture under hypoxia. However, LDHB protein is unchanged while its mRNA is decreased. Lactate secretion from JEG3 cells under hypoxia is increased, as is the lactate levels in the plasma from preeclampsia patients. Of the two lactate transporters studied, MCT4 mRNA and protein level are increased under hypoxia. Our findings support the role of hypoxia in inducing HIF-1alpha activity in trophoblasts and increasing LDH transcription as well as its activity. Higher levels of lactate are produced and secreted which may contribute to the higher lactate levels in plasma of preeclamptic patients. These mechanisms may be important in the pathophysiology of preeclampsia.

Differential expression of lactate dehydrogenase isozymes (LDH) in human placenta with high expression of LDH-A(4) isozyme in the endothelial cells of pre-eclampsia villi.

To evaluate the role of LDH isozymes in the human placenta during the third trimester, placentae were obtained from patients with normal pregnancy and pre-eclampsia. LDH-A(4)isozyme was immunolocalized primarily in the fetal endothelial cells while LDH-B(4)isozyme was predominantly present in syncytiotrophoblasts. This distinct cellular expression pattern of LDH isozymes was confirmed in HUVE and JEG cells. In addition to demonstrating the presence of five LDH isozymes in the placenta, zymograms showed that there was predominant activity of LDH-A(4)isozyme in HUVE cells and high activity of LDH-B(4)in JEG cells. Quantitative studies of LDH by agarose gel electrophoresis and Northern analysis in patients concluded that LDH-A(4)isozyme was increased in pre-eclampsia. The LDH-A(4)isozyme activity increased (P< 0.01) approx 1.6-fold in pre-eclampsia but there was no difference in the LDH-B(4)isozyme activity between placentae from normal compared to pre-eclampsia pregnancy. The level of LDH-A mRNA was increased (P< 0.05) approx twofold in pre-eclampsia. We conclude that the LDH-A gene in the endothelial cells of the placenta within the fetal microvasculature is increased in pre-eclampsia, probably as a result of hypoxia. LDH-A(4)isozyme activity and gene expression in placental endothelial cells, therefore, is a marker for the endothelial pathology seen in pre-eclampsia.

Extracellular superoxide dismutase localization and activity within the human placenta.

Maintenance of low vascular tone within the placenta is mediated by nitric oxide (NO). The half-life of NO is very short, as superoxide anion (O2-) rapidly inactivates NO to form peroxynitrite. Superoxide dismutases compete with NO for O2-. By scavenging O2-, superoxide dismutase promotes the vasodilatory action of NO. Extracellular superoxide dismutase (EC-SOD) is present in high concentrations within the extracellular matrix of systemic arteries and has been proposed to mediate vascular smooth muscle tone by increasing NO bioavailability. The localization and activity of EC-SOD within the human placenta has not been determined. Placental EC-SOD may be involved in placental vascular tone, and abnormal activity may lead to pre-eclampsia secondary to increased O2--mediated inactivation of NO. To investigate this possibility, the activity and localization of human placental EC-SOD was determined in normal women, and then compared to pre-eclamptic women. Placental EC-SOD localized within the villous extracellular matrix around arterioles, and there were no differences in distribution between normal and pre-eclamptic women. There were no differences in placental EC-SOD activity between normal and pre-eclamptic subjects in either center (33.7+/-4.1 versus 33.1+/-2.5, P=0.6), or peripheral (34.3+/-5.6 versus 34.0+/-3.5, P=0.9) samples. EC-SOD localization around villous vessels suggests that EC-SOD serves potentially to protect the fetal vasculature from O2-, in both normal and pre-eclamptic pregnancies. Placental EC-SOD distribution and activity is not different between pre-eclamptic and normal women, suggesting that EC-SOD is not involved in the vascular changes seen in pre-eclampsia.

Preliminary experience with magnetic resonance imaging in patients with third-trimester bleeding.

Fifteen patients with third-trimester bleeding, in whom transabdominal ultrasound had failed to identify a definitive source of bleeding, underwent magnetic resonance imaging (MRI). Magnetic resonance imaging correctly identified three cases of placenta previa. In four patients, intrauterine blood was identified in hematomas. One hematoma was associated with a previa, two progressed to acute abruptions, and one was associated with a clot at the marginal cord insertion. Blood was seen leading away from the placenta in a case that progressed to an acute abruption. It was also seen in the region of the cervix in two patients with placenta previa. One patient had a normal MRI but had a fresh clot at delivery, which presumably formed after the imaging. In the remaining seven patients, MRI scans were negative and the placentas were normal at delivery. Our preliminary results suggest that MRI is helpful in evaluating patients with unexplained third-trimester bleeding.

Magnetic resonance imaging of deep venous thrombosis in pregnant women with lower extremity edema.

OBJECTIVE: To review our experience with magnetic resonance imaging (MRI) in the diagnosis of deep venous thrombosis in pregnant women. METHODS: Ten gravidas with lower extremity findings suspicious for pelvic or thigh thrombosis were examined by MRI using a gradient recalled echo technique. RESULTS: In one case, MRI confirmed pelvic extension of a femoral thrombus diagnosed by Doppler ultrasound. In a second case, MRI diagnosed thrombus isolated to the pelvis. In another, MRI detected a femoral thrombus without extension into the iliac veins. Although no thrombus was detected in the remaining seven cases, pelvic vein compression by the gravid uterus was identified in five. CONCLUSION: Magnetic resonance imaging can detect deep venous thrombosis during pregnancy and should be considered when thrombosis of the pelvic veins is a clinical consideration.

Villoglandular adenocarcinoma of the cervix: a case report.

BACKGROUND: Villoglandular adenocarcinoma of the cervix is a rare neoplasm associated with a favorable outcome and has not been described as a complication of pregnancy. CASE: A gravida at 20 weeks' gestation was found to have a bulky stage-IB adenocarcinoma of the cervix. She was delivered at 32 weeks' gestation by cesarean, then a radical hysterectomy and pelvic and periaortic lymphadenectomies were performed. Pathology revealed a deeply invasive, grade 1 villoglandular adenocarcinoma confined to the cervix. The patient remains free of disease at 14 months follow-up. CONCLUSION: Villoglandular adenocarcinoma of the cervix has a favorable prognosis and can be managed conservatively, even when complicated by pregnancy.

Endoscopic management of biliary disease during pregnancy.

BACKGROUND: The transient but substantial alterations in the biliary system during pregnancy increase the risk of cholecystitis, choledocholithiasis, and pancreatitis. Traditionally, these disorders are managed conservatively or with operative cholecystectomy. Recent advances in fiber-optic technology allow endoscopy to be used as a safe, effective, and definitive treatment alternative for pancreaticobiliary disease in pregnancy. CASES: Three gravid women with cholelithiasis, acute cholecystitis, and/or gallstone pancreatitis were treated endoscopically with stone extraction and experienced rapid resolution of symptoms and successful pregnancy outcomes. CONCLUSION: Aggressive endoscopic intervention for biliary disorders in pregnancy appears to decrease morbidity, mortality, and costs. Endoscopy offers a safer, more effective treatment alternative to prolonged medical management and traditional surgical intervention during pregnancy. Because biliary abnormalities resolve rapidly in the postpartum period, it is unlikely these women will need subsequent treatment.

Single-dose antibiotic prophylaxis in high-risk patients undergoing cesarean section.

A prospective, double-blind, placebo-controlled study was performed to determine the effectiveness of single-dose antibiotic prophylaxis in decreasing infectious complications after primary cesarean section. One hundred women at high risk for postoperative infectious morbidity were randomly assigned to receive either placebo or one 2-g dose of ceftizoxime at cord clamping. The incidence of endometritis in the antibiotic group was 6.0 versus 24.5% in the placebo group (P less than .05). The incidence of febrile morbidity in the group receiving one dose of ceftizoxime was 14.0 versus 32.7% in the placebo group (P less than .05). Single-dose ceftizoxime prophylaxis significantly reduced the incidence of endometritis and febrile morbidity in high-risk patients undergoing cesarean section.

Influence of maternal diabetes on placental fibroblast growth factor-2 expression, proliferation, and apoptosis.

OBJECTIVE: Type I diabetes mellitus during pregnancy is associated with dysregulation of the oxygen and glucose metabolic pathways, both of which affect placental villous growth and function. Alteration of placental development in women with diabetes may contribute to the increased risk of preeclampsia, macrosomia, or fetal growth restriction. METHODS: To evaluate placental growth in the setting of maternal diabetes, immunohistochemical techniques were used to examine fibroblast growth factor-2 (FGF-2) expression, cell proliferation (Ki67), and apoptosis (Apo-Tag) in placentas from diabetic and nondiabetic patients. RESULTS: Immunostaining for FGF-2 in placentas from diabetic women demonstrated an increase in intensity within the villous stroma and syncytiotrophoblast (P<.05). Associated with these changes in FGF-2 expression, placentas from diabetic women showed no change in villous mitotic activity but did show decreased stromal compartment apoptosis. When expressed as a ratio of Ki67-positive:Apo-Tag-positive nuclei as an index of relative cell turnover, the stromal compartment showed a significant trend towards decreased nuclei turnover (P<.05), suggesting relative tissue growth in diabetic patients. CONCLUSION: Increased FGF-2 expression and decreased stromal cell compartment turnover in the diabetic placenta might be a compensatory mechanism in response to the altered physiologic milieu of maternal diabetes on placental function.

Intravillous eicosanoid compartmentalization and regulation of placental blood flow.

OBJECTIVE: To determine the roles of the eicosanoids thromboxane and prostacyclin, and their compartmentalization, in the regulation of placental blood flow. METHODS: First, the sites of production of thromboxane and prostacyclin were determined within the placental villus using immunohistochemical staining for thromboxane and prostacyclin synthetase. Second, the production of both eicosanoids was studied in cultured trophoblasts and compared with that in the villous core by measuring the metabolites thromboxane B2 and 6-keto-prostaglandin F 1 alpha. Finally, eicosanoid production was assessed in intact villi after stimulation by an acute change in oxygen content, 5% to 95%. RESULTS: Immunohistochemical staining showed that thromboxane production was primarily within the trophoblasts, whereas prostacyclin production was localized to the endothelial cells within the villi. In culture, we found preferential production of prostacyclin by the villous core cells and increased production of thromboxane by trophoblasts. Perifusion of intact villi demonstrated increased production of thromboxane by trophoblasts in response to an increase in oxygen content. Prostacyclin levels were too low to be detected. CONCLUSIONS: Placental blood flow appears to be regulated by compartmentalized eicosanoids, with thromboxane affecting primarily the maternal side of the placental circulation and prostacyclin affecting primarily the fetal side.

Antenatal steroid treatment and adverse fetal effects: what is the evidence?

This article reviews current animal and human data regarding possible adverse fetal effects from antenatal steroid treatment. Although it is now well accepted that such treatment is of benefit to fetal lung development, the potential for adverse fetal outcomes as a result of single or multiple glucocorticoid dosing has not been widely recognized. There are now growing concerns, based on animal and some human data, that repeated antenatal doses could lead to a decrease in birth weight, a decrease in fetal brain and other organ size, and abnormal neuronal development. Previous investigations have been hampered by nonstandardization in the type of glucocorticoid, route of delivery, timing of administration, and number of treatment courses. It is recommended that these concerns be addressed through large randomized, controlled clinical trials. In the meantime, it would be prudent to minimize antenatal steroid treatments to a single course with repeated dosing only if there is a persistent threat of preterm delivery. The practice of giving weekly injections of steroids starting at fetal viability and continuing into the third trimester is not supported.

Placental villous glucose metabolism and hormone release respond to varying oxygen tensions.

OBJECTIVE: The effects of varying oxygen tensions on tissue metabolic behavior are not well understood, yet many intracellular pathways are influenced by them. In the placenta, optimal in vivo oxygen tension at the villous level is unknown. The purpose of this study was to determine effects of varying oxygen tensions on glucose metabolism and hormone release from perifused placental villous explants. METHODS: Placentas from term normal pregnancies (n = 8) were individually minced into villous fragments, placed into three parallel chambers for each placenta, and continuously perifused for 6 hours with nonrecirculating medium aerated with either 0%, 20%, or 95% oxygen yielding mean oxygen tensions of 76 mmHg, 167 mmHg, and 543 mmHg respectively. Outflow medium was removed at regular intervals and compared to the inflow medium to determine oxygen and glucose consumption as well as lactate, lactate dehydrogenase, hCG, estradiol, and progesterone release. RESULTS: Oxygen consumption was directly proportional to oxygen tension. Glucose consumption was lowest at low oxygen tension, while both lactate and LDH release were lowest at high oxygen tension. Both hCG and progesterone release rates were lowest at high oxygen tensions. Estradiol release demonstrated a trend similar to that of the other hormones although there was no statistically significant difference among the three different levels of oxygen tension. CONCLUSION: Varying oxygen tensions affect placental villous glucose metabolism and hormone release. Under lower oxygen tensions, glucose is metabolized through glycolysis rather than through oxidative phosphorylation and is associated with higher lactate release. Exposure to higher oxygen tensions results in reduced hCG and progesterone release. Higher oxygen tensions may be associated with tissue toxicity.

Effect of magnetic resonance imaging on Xenopus laevis embryogenesis.

Xenopus laevis embryos, exposed to various lengths of magnetic resonance imaging (MRI), demonstrated no abnormal morphology, function, or developmental delays. The overall protein profiles and nucleic acid ratios were similar compared to controls. Results suggest there are no adverse effects of MRI components on the development of this vertebrate.

Correlation of amniotic fluid estrogens with L/S ratios and urinary estriols.

17 beta-estradiol (E2) and estriol-16-glucuronide in amniotic fluid from 87 patients (normal and stressed pregnancies) were studied with radioimmunoassays. Overall, amniotic fluid estradiol and estriol increased with gestation and paralleled the increase in the L/S ratio. Statistical correlations between amniotic fluid E2 and E3 with L/S were fair and better for E3 than for E2. Correlations were better from 31 to 35 weeks of gestation than from 36 to 40 weeks. A threshold of 0.34 ng/ml should be used for E2; levels above that possibly represent fetal maturity and well-being. A threshold of 540 ng/ml should be used for E3; levels above that possibly indicate fetal maturity and wellbeing. Urine E3 correlated poorly statistically with amniotic fluid E3. Serum E3 was not studied.

Sonographic measurements with umbilical and uterine artery Doppler analysis in suspected intrauterine growth retardation.

A retrospective analysis was performed to evaluate the role of sonographic measurement with umbilical and uterine artery Doppler studies in cases of suspected intrauterine growth retardation (IUGR). The sonogram was more sensitive (72%), but the umbilical artery Doppler scan was more specific (90%), for the diagnosis of IUGR. Abnormal uterine artery Doppler measurements in cases of IUGR diagnosed with a sonogram and umbilical artery Doppler scan were associated with chronic maternal hypertension. Those fetuses fared worse than those in which the uterine artery Doppler scans were normal. In contrast, small infants from pregnancies in which all three studies were normal performed well overall. Complementary use of these three studies to evaluate suspected IUGR fetuses may help us distinguish the small, troubled fetus from the small but healthy one.

Simple ovarian cysts. Clinical features on a first-trimester ultrasound scan.

OBJECTIVE: To determine the clinical features of simple ovarian cysts, often seen on a first-trimester ultrasound scan. STUDY DESIGN: All initial examinations from patients scanned in 1993 (N = 1,001) were reviewed, and the clinical features of simple ovarian cysts were determined. Relationships were determined between the presence of a cyst and first-trimester pregnancy outcomes, including progression beyond the first trimester, blighted ovum, ectopic pregnancy and fetal demise. RESULTS: A simple ovarian cyst was observed in 29% of patients. Cysts were seen less often after 8 weeks' gestation, and there was an equal distribution between those on the right and those on the left side of the pelvis. Cyst diameters did not vary with gestational age, and most mean diameters were within a range of 1-3 cm. The absence of a cyst was more often associated with a blighted ovum on follow-up ultrasound scan (relative risk, 2.8), but its presence or absence did not correlate with failure to progress beyond the first trimester, ectopic pregnancy or intrauterine fetal demise. CONCLUSION: The presence of simple ovarian cysts in the first trimester, which may represent corpus luteal cysts, appears to support early pregnancy development due to its association with a lower incidence of blighted ova.

Color Doppler ultrasonography for distinguishing myomas from uterine contractions in pregnancy.

OBJECTIVE: To determine the applicability and reliability of color Doppler ultrasonography (US) for distinguishing a uterine myoma from a focal myometrial contraction. STUDY DESIGN: Images from 36 patients with uterine thickenings were classified as myomas when color Doppler US demonstrated no centralized flow with a circumscribed vessel pattern at the border. Thickenings were classified as focal myometrial contractions when there was demonstrable vascular flow throughout the thickening. RESULTS: Using these diagnostic criteria, images from 36 patients were reliably characterized as representing myomas or contractions. The diagnosis was made more reliable by using the lowest velocity settings and exclusion of power Doppler US in nonretroplacental lesions. CONCLUSION: Color Doppler US is a sensitive and reliable tool for distinguishing uterine myomas from focal myometrial contractions.

Relapsing fever (Borrelia) in an adolescent tourist in Israel.

A case of an adolescent tourist who contracted relapsing fever (Borrelia) in Israel is presented. Travel in an infested area, a fever of irregular nature, and a strong history of tick bites are clues to diagnosis.