A three-colour flow cytometry technique for measuring trophoblast intracellular antigens: the relative expression of TAP1 in human cytotrophoblast and decidual cells

Flow cytometry is conventionally used to measure cell-surface antigen expression. However, many antigens are found within the cytoplasm, and it is necessary to fix and permeabilize cells to enable antibodies to gain access to them. In this study we have established the conditions for studying intracellular antigens in human trophoblast cells by flow cytometry using an antibody to TAP1 (a key molecule in the process of Class I MHC assembly). We have previously shown by immunocytochemistry that TAP1 expression is apparently greater on Class 1 positive extravillous cytotrophoblast than on any other fetal or maternal tissue. However, as immunohistochemistry is not quantitative we have used three-colour flow cytometry to measure the expression of TAP1 in different trophoblast populations. Villous and extravillous cytotrophoblast were identified in first trimester and term placental and decidual digests on the basis of their expression of cytokeratin and Class I MHC antigens. The level of expression of TAP1 for each population was investigated using a commercial kit that determines the number of antibody-binding sites per cell. TAP expression was found to be three- to fivefold higher in extravillous cytotrophoblast, confirming our previous findings. The techniques developed here are directly applicable to the measurement of other intracellular molecules in trophoblast, in particular cytokines.

How can the incidence of negative specimens resulting from large loop excision of the cervical transformation zone (LLETZ) be reduced? An analysis of negative LLETZ specimens and development of a predictive model

OBJECTIVE

To analyse biopsies of large loop excision of the transformation zone of the cervix; to identify factors associated with negative histology; and to develop predictive models in order to reduce the number of negative loop excisions.

DESIGN

Retrospective analysis of patient notes and audit database.

SETTING

Colposcopy clinic of a large district general hospital in North Staffordshire.

POPULATION

Four hundred and fifty-two women who underwent a large loop excision of the transformation zone (LLETZ) procedure for suspected cervical intraepithelial neoplasia.

METHODS

Women who underwent a LLETZ procedure were placed in two different groups, one positive for cervical intra epithelial neoplasia and the other negative for cervical intra epithelial neoplasia. Information was obtained on a number of clinical and colposcopic variables. Analysis was undertaken to determine if there were any differences between the two groups. These factors were then identified and three predictive models generated. Receiver-operator characteristic curves were used to assess and test these models.

MAIN OUTCOMES MEASURES

To identify factors associated with negative histology on a LLETZ specimen. To predict how to reduce the number of negative LLETZ specimens.

RESULTS

Four hundred and fifty-two women underwent a LLETZ procedure, 88 were negative (19%) and 364 were positive (81%). In women who were treated at their first visit, 56/316 (18%) had negative histology. There were significant associations between negative histology in the LLETZ and negative or low grade cytological atypia, negative colposcopic findings and years of age > 50 in both bivariate analysis and stepwise logistic regression. In the predictive models, the sensitivity ranged between 72% and 80%, the specificity 59%-72%, and the area under the receiver-operator characteristic was 0.75-0.77. If we had used the predictor models and managed women with negative or low grade cervical atypia and negative colposcopy findings conservatively, we would have reduced the negative biopsy rate from 19% to 14%, but five cases of high grade disease and 25 cases of low grade disease would have been missed. If we had also included women aged > 50 years in this model, the negative biopsy rate would have dropped from 19% to 15%, with only one case of high grade disease and 11 cases of low grade disease missed. All these women would require continued cytological and colposcopic surveillance. Importantly, no cases of invasion would have been missed.

CONCLUSION

Using a predictive model can reduce the number of negative LLETZ specimens, but at the expense of continued cytological and colposcopic surveillance and cannot be recommended in normal practice. This raises the question whether current standards for negative histology in LLETZ specimens are set unrealistically high.

Serum inhibin A and activin A are elevated prior to the onset of pre-eclampsia

Serum inhibin A and activin A concentrations increase in pre-eclampsia. We investigated the time courses of the changes in relation to the onset of the maternal syndrome and if their measurement could be useful for clinical prediction particularly in relation to early onset disease, the most severe of the clinical presentations. Serial samples were taken from 1496 healthy nulliparae. Changes in activin A and inhibin A were analysed in women with: early onset pre-eclampsia (n = 11), pre-eclampsia delivering at 34-36 weeks (n = 14), term pre-eclampsia (n = 25) and gestational hypertension (n = 25); and in a subset with uncomplicated pregnancies (n = 25). Serum inhibin A and activin A were increased in all groups prior to pre-eclampsia, before 20 weeks in those with early onset pre-eclampsia. Screening efficacy was determined at 15-19 and 21-25 weeks in all women who developed pre-eclampsia (n = 70) and randomly selected controls (n = 240). Predictive sensitivities were low (16-59%) but much better for early onset pre-eclampsia: 67 and 44% at 15-19 weeks and 89 and 89% at 21-25 weeks for inhibin A and activin A respectively. Hence, serum inhibin A and activin A concentrations increase before the onset of pre-eclampsia at gestational ages that depend on when pre-eclampsia develops. On their own such measures are unlikely to prove efficient for screening.

An audit of the management of uterine malignancy within the West Midlands. West Midlands Gynaecological Oncology Group

OBJECTIVE

To audit the management of uterine malignancy.

DESIGN

Retrospective casenote analysis.

SETTING

Cancer units/centres within the West Midlands.

SAMPLE

The last 100 cases managed by each hospital in 1997.

RESULTS

Ninety-six cases of uterine malignancy from ten hospitals were analysed. Only six hospitals were able to provide a complete data set. Eighty-eight cases (92%) presented with abnormal, usually postmenopausal, vaginal bleeding. Over 90% of the cases were primary endometrial carcinomas. Of the 15 standards audited, 11 were met by at least one hospital. No hospital met all the standards, although every hospital was able to meet at least one. Standards concerned with initial referral and diagnostic intervals were universally failed. Outpatient diagnosis was made in only 30%. The availability of Rapid Access Clinics neither promoted outpatient diagnosis nor sped up diagnosis. Once the diagnosis had been made, surgery was usually performed within six weeks.

CONCLUSIONS

This audit has provided valuable baseline data for future activity. Serious attention must be given to improvement in clinical cancer data collection. Referral pathways for women with suspected uterine cancer, and endometrial cancer in particular, need improvement. It is recommended that the current standards remain unaltered, and after the West Midlands Gynaecological Oncology Group had the opportunity to consider and implement the necessary changes, the audit be repeated.

Modulation of indoleamine 2,3-dioxygenase by interferon-gamma in human placental chorionic villi

The effect of interferon-gamma on indoleamine 2,3-dioxygenase, a tryptophan catabolizing enzyme, was studied in cultured human placental chorionic villi. The activity of indoleamine 2,3-dioxygenase was markedly stimulated by interferon-gamma in a time- and concentration-dependent manner. Interferon-alpha and interferon-beta also showed a slight stimulatory effect on indoleamine 2,3-dioxygenase activity. The level of indoleamine 2,3-dioxygenase mRNA expression (determined by reverse transcription-polymerase chain reaction) was also enhanced by interferon-gamma. Interleukin-4 showed a dose-dependent inhibitory effect on interferon-gamma-induced stimulation of indoleamine 2,3-dioxygenase activity and mRNA expression.

Adhesion molecules of syncytiotrophoblast microvillous membranes inhibit proliferation of human umbilical vein endothelial cells

It has been shown previously that syncytiotrophoblast microvillous membranes (STBM), isolated from normal or pre-eclampsia placentae, specifically inhibit the proliferation of cultured human umbilical vein endothelial cells (HUVEC) and disrupt the cell monolayer without causing cell death. We have previously shown that this anti-proliferative activity resides in a self-aggregating complex in which eight proteins, namely integrins alpha(5)(CD49e) and alpha(V)(CD51), dipeptidyl peptidase IV (DPP IV, CD26), alpha-actinin, transferrin receptor (TfR, CD71), transferrin, placental alkaline phosphatase (PLAP) and monoamine oxidase A (MAO-A) were identified. In the present study, we investigated which of these components causes the anti-proliferative activity of STBM. Antibodies against integrin alpha(5)and alpha(V)and DPP IV all reduced the STBM-induced inhibition of proliferation of HUVEC, which was also reversed by added fibronectin. A preparation of PLAP inhibited endothelial proliferation, but this was not due to enzymatic activity. The preparation was shown to be impure with more than 12 bands present on Coomassie blue stained SDS-PAGE gels. These included integrins alpha(5)and alpha(V), which could account, at least in part, for the inhibitory activity. We could not exclude, however, the possibility of other unidentified factors being involved. We conclude that adhesion molecules account for a major part of the anti-proliferative activity of STBM; these appear to compete for ligands in the extracellular matrix or serum with the appropriate receptors on HUVEC.

Activation of peripheral leukocytes in rat pregnancy and experimental preeclampsia

OBJECTIVE

The aim of this study was to search for activation markers of peripheral leukocytes in experimental preeclampsia in the rat.

STUDY DESIGN

Experimental preeclampsia was induced in 14-day-pregnant rats by infusion of endotoxin (1.0 microg/kg body weight). For comparison, rats with normal pregnancies that were infused with sodium chloride solution and cyclic rats that were infused with either endotoxin or sodium chloride solution were used. At various points before and after the infusion, blood samples were withdrawn and analyzed by means of whole-blood flow cytometry to evaluate expression of inflammation-associated adhesion molecules (CD11b, CD11a, CD49d, and CD62L) and CD14 on the leukocytes.

RESULTS

Normal pregnancy was associated with increased CD11b (granulocytes and monocytes), CD11a (monocytes and lymphocytes), and CD49d (granulocytes, monocytes, and lymphocytes) expression. In addition to these changes found in normal pregnancy, reduced CD62L and increased CD11a and CD49d expression was found on granulocytes after endotoxin treatment of pregnant rats. No effect of endotoxin was observed in cyclic rats.

CONCLUSION

Leukocytes of rats with experimental preeclampsia and, to a lesser extent, those of rats with normal pregnancies had an activated phenotype. These results are consistent with our previous findings in human subjects and suggest that (experimental) preeclampsia results from a generalized inflammatory response.

Inositol phosphoglycans and signal transduction systems in pregnancy in preeclampsia and diabetes: evidence for a significant regulatory role in preeclampsia at placental and systemic levels

Measurements have been made of the urinary content of inositol phosphoglycans IPG P-type and IPG A-type, putative insulin second messengers, in preeclampsia, in type I insulin-treated diabetic pregnant women and their matched control subjects, and nonpregnant women of child-bearing age. The content of IPG P-type and IPG A-type was also measured in the placenta from preeclamptic patients and from normal pregnancies. Pregnancy was associated with an increase, approximately twofold, in urinary output of IPG-P-type relative to nonpregnant controls (P<0.01). The 24-h output of IPG P-type in urine in preeclamptic women was significantly higher (2- to 3-fold) than in pregnant control subjects matched for age, parity, and stage of gestation (P<0.02). In contrast, insulin-dependent diabetic pregnant women did not show any significant change in urinary output of IPG P-type or IPG A-type relative to pregnant control subjects. Evidence for a possible relationship and correlation between the urinary excretion of IPG P-type and markers of preeclampsia, including proteinuria (r = 0.720, P<0.01), plasma aspartate transaminase (r = 0.658, P<0.05), and platelet counts (r = 0.613, P<0.05) is presented. A high yield of IPG P-type was extracted from human placenta, in preeclampsia some 3-fold higher (P = 0.03) than the normal value, whereas no IPG A-type (with lipogenic-stimulating activity) was found. Low concentrations of placental IPG A-type were detected relative to IPG P-type using assay systems dependent upon the effect of this mediator on cAMP-dependent protein kinase or on a proliferation assay using thymidine incorporation into DNA of EGFR T17 fibroblasts. It is postulated that the high urinary excretion IPG P-type in preeclampsia reflects high placental levels and relates to the accumulation of glycogen in the placenta. The paracrine effects of placental IPG P-type (stimulation off other endocrine glands and/or endothelial cells) could contribute to the pathogenesis of the maternal syndrome. A possible theoretical link between elevated placental IPG P-type and apoptosis is proposed.

A case report of acute pelvic thrombophlebitis missed by magnetic resonance imaging of the pelvic veins

A 29-year-old woman presented post-natally with pulmonary hypertension. Peripheral venous thrombosis was not detected by duplex ultrasound or conventional MRI. Despite anticoagulation, the patient arrested. Autopsy revealed right iliac vein thrombosis. The ability of conventional MRI to detect acute pelvic thrombophlebitis depends on obtaining appropriate views.

A comparison of the side effects of prilocaine with felypressin and lignocaine with adrenaline in large loop excision of the transformation zone of the cervix: results of a randomised trial

OBJECTIVE

To test the hypothesis that prilocaine with felypressin causes fewer side effects than lignocaine with adrenaline when performing large loop excision of the transformation zone of the cervix.

DESIGN

Randomised trial.

SETTING

Colposcopy clinic in a large district general hospital.

PARTICIPANTS

Two hundred consecutive women undergoing large loop excision of the transformation zone of the cervix.

METHODS

Two different local anaesthetic combinations (prilocaine with felypressin and lignocaine with adrenaline) were compared in women undergoing large loop excision of the transformation zone. Prospective collection of clinical and treatment data was undertaken with scoring using an ordinal scale of pain experienced by the women during the procedure. Peri-operative blood loss and any side effects were also recorded.

MAIN OUTCOME MEASURES

Side effects associated with the local anaesthetic agents.

RESULTS

Lignocaine with adrenaline resulted in less blood loss (P = 0.006) but was more likely to cause side effects, such as feeling faint (P = 0.017) and shaking (P < 0.001).

CONCLUSION

Prilocaine with felypressin causes fewer side effects than lignocaine with adrenaline and is therefore the preferred local anaesthetic combination for large loop excision of the transformation zone.

Expression and subcellular localization of cyclin D1 protein in epithelial ovarian tumour cells

The expression of cyclin D1 protein in tumour sections from 81 patients with epithelial ovarian cancer was analysed using immunohistochemistry. The tumours that overexpressed cyclin D1 in more than 10% of neoplastic cells were considered positive. Thus overexpression of cyclin D1 was observed in 72/81 (89%) of the cases examined. Protein was detected in both the nucleus and the cytoplasm in 24/81 (30%) and localized exclusively in the cytoplasm in 48/81 (59%) of the tumours. Cyclin D1 was overexpressed in both borderline and invasive tumours. There was no association between protein overexpression and tumour stage and differentiation. Furthermore, no correlation between cyclin D1 expression and clinical outcome was observed. However, in tumours overexpressing cyclin D1 (n = 72), the proportion displaying exclusively cytoplasmic localization of protein was higher in those with serous compared with non-serous histology (P = 0.004, odds ratio 4.8, 95% confidence interval 1.4-19.1). Western analysis using a monoclonal antibody to cyclin D1 identified a 36 kDa protein in homogenates from seven tumours displaying cytoplasmic only and one tumour demonstrating both nuclear and cytoplasmic immunostaining. Using restriction fragment length polymorphism polymerase chain reaction and PCR-multiplex analysis, amplification of the cyclin D1 gene (CCND1 was detected in 1/29 of the tumours demonstrating overexpression of cyclin D1 protein. We conclude that deregulation of CCND1 expression leading to both cytoplasmic and nuclear protein localization is a frequent event in ovarian cancer and occurs mainly in the absence of gene amplification.

Trophoblast deportation in human pregnancy--its relevance for pre-eclampsia

The maternal syndrome of pre-eclampsia is thought to result from endothelial cell damage caused by a circulating factor derived from the placenta. This study investigates the hypothesis that trophoblast deportation may be part of the process by which this factor enters the maternal circulation. The nature and incidence of trophoblast deportation was studied in uterine vein and peripheral blood taken from normal and pre-eclamptic women at caesarean section. Trophoblasts were enriched using immunomagnetic beads to deplete leucocytes and labelled with trophoblast-specific monoclonal antibodies. Syncytiotrophoblast, cytotrophoblast, cytotrophoblast clumps and anucleate trophoblast cells were found in uterine vein blood. Cytotrophoblast cells were found to be shed less frequently than syncytiotrophoblast and the majority were probably villous in origin. Trophoblasts were found in the uterine vein blood of normal pregnant women with higher levels in pre-eclampsia. However, trophoblasts were rarely found in the peripheral circulation. There was no correlation between trophoblast numbers and either the severity of the disease, the extent of placental pathology or the inhibitory effect of uterine and peripheral vein plasma on endothelial growth in vitro. Thus, it is speculated that increased trophoblast deportation in pre-eclampsia is secondary to the structural and functional changes occurring in the placenta, rather than directly linked with the circulating endothelial cell damaging factor in pre-eclampsia.

Is the provision of information leaflets before colposcopy beneficial? A prospective randomised study

OBJECTIVE

To assess the usefulness of a leaflet distributed to women before colposcopy designed to reduce their anxiety and psychosexual morbidity by providing information.

DESIGN

Prospective randomised study.

SETTING

Colposcopy clinic of a large district general hospital.

SAMPLE

Two hundred consecutive women undergoing colposcopy for the first time for a cervical cytological abnormality of severity no greater than moderate dyskaryosis.

METHODS

Women were randomised into one of two groups (leaflet or control). Those in the leaflet group were sent an information leaflet prior to attending the clinic. In the colposcopy clinic all the women completed a State/Trait Anxiety Inventory (StAI/TrAI) and a modified psychosexual questionnaire before undergoing colposcopy. This was repeated at the six-month follow up visit. Women in the leaflet group also completed a further questionnaire on the leaflet.

MAIN OUTCOME MEASURES

Differences of anxiety and psychosexual scores between leaflet and control groups.

RESULTS

The leaflet was well received. There were no statistical differences in StAI and TrAI scores between the study group and the control group at either visit, although in the whole study population StAI and TrAI scores were reduced at the second visit. The leaflet group had significantly more psychosexual problems but by the second visit, the scores had improved and the two groups were similar. When the mean differences in anxiety and psychosexual scores at the initial and second visits were compared between the groups, the reduction in negative sexual feelings and deterioration of TrAI scores experienced by the leaflet group was significant.

CONCLUSIONS

This study suggests that the provision of sending an information leaflet prior to colposcopy is not beneficial in isolation. Other approaches need to be considered.

Maternal peripheral blood leukocytes in normal and pre-eclamptic pregnancies

OBJECTIVE

To analyse activation of maternal peripheral blood leukocytes by flow cytometric measurements of intracellular free-ionised calcium of lymphocytes, granulocytes and monocytes, separately.

DESIGN

Case-control study.

SETTING

High risk pregnancy service in a regional centre.

MATERIAL

Samples from 10 women with pre-eclampsia, 10 appropriately-matched women with normal pregnancy, nine multigravid normal women at mid-gestation selected as being least likely to demonstrate any tendencies towards pre-eclampsia, and 11 healthy nonpregnant women of reproductive age were studied.

METHODS

Using flow cytometry, intracellular free ionised calcium ([Ca2+]i) was estimated by loading the cells with Fluo-3 and measuring the changes in fluorescence intensity induced by free ionised calcium. After the basal levels were measured, the response of phagocytes to stimulation with n-formylmethionyl-leucyl-phenylalanine (fMLP) was determined.

MAIN OUTCOME MEASURES

Basal [Ca2+]i of peripheral blood leukocytes.

RESULTS

Median basal [Ca2+]i was significantly increased in all three subsets of leukocytes--lymphocytes, granulocytes and monocytes in pre-eclampsia--compared with the three control groups. Samples from both groups of women with normal pregnancy did not differ from those from nonpregnant women. The peak responses of monocytes to stimulation with 10 nmol fMLP were greater in samples from pre-eclamptic women, giving evidence of priming.

CONCLUSIONS

Peripheral blood leukocytes are activated in pre-eclampsia in terms of basal changes in the intracellular second messenger--free ionised calcium. Peripheral blood monocytes are primed to give greater responses after stimulation with fMLP.

31P magnetic resonance spectroscopy of the liver in HELLP syndrome

OBJECTIVES

Using magnetic resonance spectroscopy (MRS) to measure phosphorus-containing metabolites in the liver, this study aimed to investigate non-invasively whether or not women with haemolysis, elevated liver enzymes and low platelets (HELLP) have detectable abnormalities of hepatic energetics.

SETTING

John Radcliffe Hospital, Oxford.

DESIGN

Prospective study.

METHODS

After giving informed consent, patients with HELLP syndrome (n = 7) and controls with severe pre-eclampsia (n = 3), were studied by 31P MRS of the liver as soon as possible after delivery (range 2-4 days) and compared with normal nonpregnant controls (n = 6). Haematological and biochemical tests were performed serially and on the day of the MRS in all pregnant patients.

RESULTS

The severity of HELLP varied as follows: peak aspartate aminotransferase (range 129-2574), peak gamma glutamyl transferase (range 28-96), peak lactate dehydrogenase (range 305-2820), nadir platelets (range 25-114), peak international normalised ratio for prothrombin time (before fresh frozen plasma) (range 0.9-1.9). One pregnancy was terminated but all others resulted in live births and all mothers made uneventful, rapid recoveries. MRS-determined relative hepatic concentrations of phosphorus-containing metabolites and absolute concentrations of adenosine triphosphate did not differ significantly between groups. One patient with the most clinically severe HELLP syndrome (by laboratory criteria) exhibited magnetic resonance spectra which showed a relative increase in phosphomonoester and an absolute decrease in hepatic adenosine triphosphate (to 62% of control).

CONCLUSIONS

Enthusiasm for the conservative management of HELLP syndrome that develops remote from term has been tempered by the inability to identify patients at risk for progression to hepatic necrosis. We found that most patients with HELLP syndrome had normal liver metabolism as assessed by MRS. However, clinically severe HELLP syndrome can be associated with disturbed hepatic metabolism consistent with that seen in hepatic ischaemia and/or granulocytic infiltration of the liver.

Supernatants from co-cultured endothelial cells and syncytiotrophoblast microvillous membranes activate peripheral blood leukocytes in vitro

There is evidence for both endothelial cell and peripheral blood leukocyte (PBL) activation in pre-eclampsia. Syncytiotrophoblast microvillous membranes (STBM) are shed in greater quantities from the placenta in pre-eclampsia, disrupt cultured endothelial cells in vitro and may be the immediate cause of the maternal syndrome. The aim of this study was to determine if endothelial cells co-cultured with STBM release factors that can activate PBL in vitro. Flow cytometry was used to measure changes in intracellular free ionized calcium ([Ca2+]i), pH (pHi) and reactive oxygen species (iROS) as indices of leukocyte activation. PBL from male non-pregnant donors was exposed to supernatants from human umbilical vein endothelial cells (HUVEC) cultured with STBM. The time course of changes in [Ca2+]i, pHi and iROS was determined and compared with appropriate control measurements. The test supernatants caused significant activation of granulocytes and monocytes in terms of increases in [Ca2+]i and falls in pHi and release of iROS. Lymphocytes responded only with respect to increases in iROS. The results define a possible mechanism for the activation of PBL in pre-eclampsia, as being secondary to endothelial cell activation caused by circulating STBM shed in excess amounts from the placenta.

Gestational regulation of granulocyte-colony stimulating factor receptor expression in the human placenta

A number of cytokines and their receptors are abundantly expressed at the materno-fetal interface and are thought to have a function in the regulation of placentation. Granulocyte-colony stimulating factor (G-CSF) is expressed by stromal cells in both placental tissue and maternal decidua throughout placentation. In this study, we examined the expression of placental G-CSF receptor (G-CSFR) mRNA and protein throughout gestation by ribonuclease protection assays, Western blotting, and immunohistochemistry. The major placental form of G-CSFR mRNA, corresponding to a membrane-bound form of the protein, was present in first-trimester placental tissues; levels decreased in second- and were highest in third-trimester placental tissues. Two placental G-CSFR molecules, 120 kDa and 150 kDa, were detected in first- and third-, but not second-, trimester tissues. The level of the 150-kDa G-CSFR was greater in the third- than in first-trimester samples. These differences were irrespective of whether or not the patients had received prostaglandin E1 analogues, prostaglandin E1 analogues and oxytocin, oxytocin alone, or mifepristone before labor. We demonstrated by immunohistochemistry that interstitial cytotrophoblast in first- and second-trimester decidual tissue and cytotrophoblast in term fetal membranes express G-CSFR. These data demonstrate that the expression of specific forms of placental G-CSFR is strictly cell type- and developmental stage-specific, and they suggest that G-CSFR may be important in decidual invasion of cytotrophoblast and in trophoblast function during placentation.

Preeclampsia: an excessive maternal inflammatory response to pregnancy

The maternal syndrome of preeclampsia has previously been ascribed to generalized maternal endothelial cell dysfunction. In this review we suggest that the endothelial dysfunction is a part of a more generalized intravascular inflammatory reaction involving intravascular leukocytes as well as the clotting and complement systems. We provide evidence from our recent work and that of others that not only supports this proposal but indicates that such an inflammatory response is already well developed in normal pregnancy and that the differences between normal pregnancy and preeclampsia are less striking than those between the normal pregnant and nonpregnant states. From this we argue that preeclampsia arises when a universal maternal intravascular inflammatory response to pregnancy decompensates in particular cases, which may occur because either the stimulus or the maternal response is too strong. We conclude that there is no specific cause for the disorder, which can be better considered as the extreme end of the range of maternal adaptation to pregnancy. We propose that poor placentation is not the cause of preeclampsia but is a powerful predisposing factor. We predict that a single preeclampsia gene will not be found, nor will either a single specific predictive test or single preventive effective measure be devised. Aspects of the hypothesis are testable, and future work should allow its confirmation or refutation.

Quantitative abnormalities of fetal DNA in maternal serum in preeclampsia

BACKGROUND

There is much recent interest in the biologic and diagnostic implication of cell-free non-host DNA in the plasma and serum of human subjects. To determine if quantitative abnormalities of circulating non-host DNA may be associated with certain pathologic processes, we used circulating fetal DNA in preeclampsia as a model system.

METHODS

We studied 20 preeclamptic women and 20 control subjects of comparable gestational age (means, 32 and 33 weeks, respectively). Male fetal DNA in maternal serum was measured using real-time quantitative PCR for the SRY gene on the Y chromosome.

RESULTS

The imprecision (CV) of the assay was 2.7%. The median circulating fetal DNA was increased fivefold in 20 preeclamptic women compared with 20 control pregnant women (381 vs 76 genome-equivalents/mL, P <0.001).

CONCLUSIONS

These observations suggest that preeclampsia is associated with disturbances in the liberation and/or clearance mechanisms of circulating DNA. These results also raise the possibility that measurement of circulating DNA may prove useful as a marker for the diagnosis and/or monitoring of preeclampsia.

Purification and characterization of a complex from placental syncytiotrophoblast microvillous membranes which inhibits the proliferation of human umbilical vein endothelial cells

The signs of pre-eclampsia are thought to arise from maternal endothelial dysfunction caused by circulating factors of placental origin. Syncytiotrophoblast microvillous membranes (STBM) cause endothelial disruption and inhibit proliferation in vitro. Significantly increased amounts of STBM can be detected in blood from pre-eclamptic women and could contribute to endothelial dysfunction in vivo. This study purified a complex from STBM which inhibits the proliferation of cultured human endothelial cells. Integral membrane proteins were solubilized with sucrose monolaurate. Anion exchange chromatography yielded two peaks of anti-proliferative activity. Only the second peak was specific to STBM and was subjected to further separation by Sephacryl S-200 gel filtration chromatography (GFC). A single peak of specific activity eluted close to the void volume, at a position unaltered by added denaturing agents, guanidium chloride or urea. On Sephacryl S-300 GFC, two peaks were obtained of 410 and 820 kDa, with similar anti-proliferative activity and protein components (by SDS-polyacrylamide gel electrophoresis). The major protein bands were as integrins alpha5 and alpha v, dipeptidyl peptidase IV, alpha-actinin, transferrin, transferrin receptor, placental alkaline phosphatase and monoamine oxidase A.

Fetal heart rate patterns in term labor vary with sex, gestational age, epidural analgesia, and fetal weight

OBJECTIVES

Our purpose was to analyze the previously unreported effect of fetal sex on the fetal heart rate in labor and to measure its magnitude in relation to the effects of other independent clinical variables.

STUDY DESIGN

The last hour of the intrapartum heart rates of 1884 term singleton fetuses collected during routine clinical monitoring over 19 months in Oxford, United Kingdom, was analyzed by computerized techniques. The records were selected for completeness and continuity until within at least 30 minutes of delivery. A subset of records from earlier in labor and a separate archive of antepartum normal term records were also examined.

RESULTS

Female fetuses had significantly faster heart rates than male fetuses (P <.0001). Epidural analgesia, weight percentile (adjusted for age and sex), parity, the duration of first and second stages of labor, and a fall in umbilical arterial blood pH at birth also independently modulated the fetal heart rate (all P <.0001). The effects of these independent variables on heart rate were additive, the most important being epidural analgesia as a cause of tachycardia. The effect of fetal sex was less in the first stage, 6 to 7 hours before delivery, and was not present before the onset of labor (in another 552 pregnancies at 37 to 38 weeks).

CONCLUSIONS

The fetal heart rate response of female fetuses to normal labor differs from that of male fetuses. Computerized numeric analysis of intrapartum fetal heart rate patterns will need to take into account the multiple factors that influence the fetal heart rate to identify precisely which patterns predict clinical outcome.

Prenatal diagnosis of fetal RhD status by molecular analysis of maternal plasma

BACKGROUND

The ability to determine fetal RhD Status noninvasively is useful in the treatment of RhD-sensitized pregnant women whose partners are heterozygous for the RhD gene. The recent demonstration of fetal DNA in maternal plasma raises the possibility that fetal RhD genotyping may be possible with the use of maternal plasma.

METHODS

We studied 57 RhD-negative pregnant women and their singleton fetuses. DNA extracted from maternal plasma was analyzed for the RhD gene with a fluorescence-based polymerase-chain-reaction (PCR) test sensitive enough to detect the RhD gene in a single cell. Fetal RhD status was determined directly by serologic analysis of cord blood or PCR analysis of amniotic fluid.

RESULTS

Among the 57 RhD-negative women, 12 were in their first trimester of pregnancy, 30 were in their second trimester, and 15 were in their third trimester. Thirty-nine fetuses were RhD-positive, and 18 were RhD-negative. In the samples obtained from women in their second or third trimester of pregnancy, the results of RhD PCR analysis of maternal plasma DNA were completely concordant with the results of serologic analysis. Among the maternal plasma samples collected in the first trimester, 2 contained no RhD DNA, but the fetuses were RhD-positive; the results in the other 10 samples were concordant (7 were RhD-positive, and 3 RhD-negative).

CONCLUSIONS

Noninvasive fetal RhD genotyping can be performed rapidly and reliably with the use of maternal plasma beginning in the second trimester of pregnancy.

Vascular smooth muscle oxygen consumption is reversibly stimulated by sera from women with preeclampsia

OBJECTIVE

Preeclampsia is a complication of pregnancy that causes maternal vasoconstriction and hypertension. The disease may progress to eclampsia, which is thought to be related to cerebral vasospasm. Although there is evidence for more than one circulating factor that causes endothelial cell dysfunction in preeclampsia, little work has focused on the possibility that vascular smooth muscle function might be directly stimulated by a circulating factor. The aim of this study was to determine whether such a factor or factors could be detected by the vessels.

STUDY DESIGN

Excessive vascular smooth muscle oxygen consumption was used as a screen for metabolic stimulation because pathologic arterial constriction would require oxidative metabolism to generate adenosine triphosphate. De-endothelialized porcine carotid artery (a well-validated model of human arterial contractile function) was exposed to sera from patients with preeclampsia (1:30 dilution) in a sealed chamber with an oxygen electrode, and the rate of oxygen consumption by the tissue was measured. Comparisons with the effects of sera from matched normal pregnant patients and from nonpregnant women were made.

RESULTS

Exposure of vascular smooth muscle to sera from women with preeclampsia for 90 minutes resulted in greater oxygen consumption by the tissue (0.66 +/- 0.16 micromol O2 /min per gram of dry weight) than did exposure to sera of matched pregnant and nonpregnant control subjects (0.34 +/- 0.08 micromol O2 /min per gram of dry weight, P <.001, and 0.29 +/- 0.03 micromol O2 /min per gram of dry weight, P <.001, respectively). This stimulation was completely reversed by rinsing.

CONCLUSIONS

There is a factor in the circulation of women with preeclampsia that has the reversible effect on vascular smooth muscle of accelerating oxygen consumption. We discuss the implications of this observation in terms of known aspects of vascular smooth muscle contractile function.