Third trimester plasma neurokinin B levels in women with and without preeclampsia.

OBJECTIVE: This study was undertaken to measure neurokinin B (NKB) levels in pregnant women with and without preeclampsia (PE) in the third trimester. The study focused on the Black (sub-Saharan ancestry) and 'mixed ancestry' (synonymous with 'colored' and denotes an established race group of Khoisan, European, Malay, Malagascan, African, and South Indian ancestry) populations, constituting the majority of inhabitants of the Western Cape Province of South Africa. METHODS: Questionnaires were used to obtain clinical data from pregnant 'mixed ancestry' and Black women. Third trimester plasma NKB levels were determined by enzyme-linked immunosorbent assay technique (EIA) in 72 pregnant women with PE and in 94 healthy women. The EIA results were then correlated with clinical data. RESULTS: The mean NKB concentration in the PE groups (23.5 ng/L for 'mixed ancestry' and 15.0 ng/L for Black women) was significantly higher than in the control groups (3.8 ng/L and 4.4 ng/L, respectively; p < or = 0.001). No significant differences in maternal clinical data were found between the diseased groups. CONCLUSIONS: Using the EIA technique, this study confirms previous reports of elevated NKB levels in the plasma of PE women in the third trimester. Whether increased NKB levels are causative or merely associated with PE remains unknown, as do the causative molecular mechanisms. Future longitudinal studies are certainly needed to further elucidate the predictive value of NKB in PE.

Altered plasma neurokinin B levels in patients with pre-eclampsia.

OBJECTIVE(S): This study determines the levels of Neurokinin B (NKB) in the plasma of South African coloured pregnant women with and without preeclampsia (PE) and correlates these results with clinical data. Additionally, the peptide radioimmunoassay (RIA) and peptide enzyme immunoassay (EIA) methods were compared in the determination of the Neurokinin B levels, using 58 samples from patients with PE. METHODS: At the Tygerberg Hospital, Cape Town, SA, 43 pregnant women with PE and 62 healthy pregnant women were recruited, and clinical data were gathered using questionnaires; 58 patient samples were tested by both RIA and EIA. RESULTS: The comparison of RIA and EIA revealed an r-value of 0.904. The mean NKB concentration in the PE group (23.5 ng/l) was significantly higher than in the control group (3.8 ng/l). Within the PE cohort, two NKB subgroups could be discerned: those with levels <30 ng/l and those with levels >30 ng/l. CONCLUSION(S): This study, carried out within a distinct population, confirms previous reports of elevated NKB levels in the plasma of pre-eclamptic women in the third trimester, and established the suitability of EIA for determining NKB levels. Whether the altered NKB levels are causative or merely associated with PE still remains to be determined. The split in the two NKB groups (high and low values) needs further evaluation, as does whether NKB could be used as a screening test or as a predictive factor.

Minimal alteration in the ratio of circulatory fetal DNA to fetal corticotropin-releasing hormone mRNA level in preeclampsia.

OBJECTIVES: We have recently observed that fetal DNA and fetal corticotropin-releasing hormone (CRH) mRNA are associated with in vitro generated syncytiotrophoblast-derived microparticles, and that the ratio of fetal DNA to mRNA (CRH) varied according to whether the particles were derived by predominantly apoptotic, apo-necrotic or necrotic pathways. Hence, we examined whether these ratios varied in maternal plasma samples taken from normotensive and preeclamptic pregnancies in vivo. METHODS: Maternal plasma samples were collected from 18 cases with preeclampsia and 29 normotensive term controls. Circulatory fetal CRH mRNA and DNA levels were quantified by real-time PCR and RT-PCR. RESULTS: Circulatory fetal mRNA and fetal DNA levels were significantly elevated in the preeclampsia study group when compared to normotensive controls. Alterations in the fetal mRNA to DNA ratio between the study and control groups were minimal, even when stratified into early (<34 weeks of gestation) and late (>34 weeks of gestation) onset preeclampsia. CONCLUSIONS: Our data suggest that although circulatory fetal DNA and mRNA levels are significantly elevated in preeclampsia, the ratios in maternal plasma are not dramatically altered.

Analysis of plasma elastase levels in early and late onset preeclampsia.

BACKGROUND: Circulatory neutrophils have been reported to be activated in preeclampsia. It has been suggested that maternal plasma levels of elastase may serve as a possible cell-free marker to quantify such activation. Although plasma elastase levels have been found to be elevated in cases with manifest preeclampsia and eclampsia, this has not yet been examined in cases with early and late onset preeclampsia. We have now examined this aspect. METHODS: In this retrospective study, maternal plasma samples were examined from eight cases with early onset preeclampsia (<34 weeks of gestation), eight cases with late onset preeclampsia (>34 weeks of gestation) and an equal number of gestational age matched normotensive term controls. Plasma concentrations of elastase were measured by ELISA using a commercially available assay. RESULTS: Plasma elastase concentrations were significantly elevated the preeclampsia study group when compared to the normotensive control group (median=139.2 ng/ml versus median=72.1 ng/ml; P=0.0025). These elevations remained significant when the preeclampsia study group was stratified into case with early onset preeclampsia (median=118.8 ng/ml versus median=62.2 ng/ml; P=0.03), but jailed failed to attain significance for those cases with late onset preeclampsia (median=181.3 ng/ml versus median=86.3 ng/ml; P=0.061). CONCLUSIONS: Our data indicate that elastase levels are elevated in both early and late onset forms of preeclampsia, and imply that the activation of neutrophils may be more acute in the former than in the latter (238 words).

The Glu298Asp variant of the endothelial nitric oxide synthase gene is associated with an increased risk for abruptio placentae in pre-eclampsia.

Attempts to define a pre-eclampsia susceptibility profile have been hampered by the wide clinical spectrum of the condition and the complex genetics underlying it. Genes that modulate blood pressure, fluid homeostasis and placental vascular development have been considered plausible candidates. Among these are the angiotensinogen (AGT) gene variant Met235Threo, which has been associated with pre-eclampsia and the endothelial nitric oxide synthase (eNOS) polymorphism Glu298Asp, which has been associated with both pre-eclampsia and abruptio placentae, a condition that often co-exists with pre-eclampsia. The aim of this study was to investigate a potential association between these gene variants and pre-eclampsia with and without abruptio placentae in a South African patient group. Fifty primigravidas with early onset, severe pre-eclampsia, 50 women presenting primarily with abruptio placentae (whether associated with pre-eclampsia or not) and a control panel of 50 healthy pregnant women constituted the study groups. The Met235Threo and Glu298Asp variants were characterised by polymerase chain reaction and restriction enzyme analysis. No association was demonstrated between the M235T variant of the AGT gene and pre-eclampsia or abruptio placentae. In contrast, the combined frequency of the eNOS variant genotypes (GT and TT) was significantly higher in the abruptio placentae group (49%) than the control group (21%) (p=0.006). Furthermore, in the pre-eclampsia patients who subsequently developed abruptio placentae, the eNOS GT genotype emerged as a major risk factor for the development of abruptio placentae (p<0.0001). These data suggest that the presence of a Glu298Asp eNOS variant may pre-dispose a pre-eclamptic woman to develop abruptio placentae or that it is a marker for predisposition.

Circulatory nucleosome levels are significantly increased in early and late-onset preeclampsia.

INTRODUCTION: Elevations in circulatory DNA, as measured by real-time PCR, have been observed in pregnancies with manifest preeclampsia. Recent reports have indicated that circulatory nucleosome levels are elevated in the periphery of cancer patients. We have now examined whether circulatory nucleosome levels are similarly elevated in cases with preeclampsia. METHODS: Maternal plasma samples were prepared from 17 cases with early onset preeclampsia (<34 weeks gestation) with 14 matched normotensive controls, as well as 15 cases late-onset preeclampsia (>34 weeks gestation) with 10 matched normotensive controls. Levels of circulatory nucleosomes were quantified by commercial ELISA (enzyme-linked immunosorbant assay). RESULTS: The level of circulatory nucleosomes was significantly elevated in both study preeclampsia groups, compared to the matched normotensive control group (p = 0.000 and p = 0.001, respectively). CONCLUSIONS: Our data suggests that preeclampsia is associated with the elevated presence of circulatory nucleosomes, and that this phenomenon occurs in both early- and late-onset forms of the disorder.

Analysis of two mutations in the MTHFR gene associated with mild hyperhomocysteinaemia--heterogeneous distribution in the South African population.

OBJECTIVE: The frequencies of mutations 677C-->T and 1298A-->C in the methylenetetrahydrofolate reductase (MTHFR) gene, previously shown to be associated with decreased enzyme activity that may lead to hyperhomocysteinaemia and consequently increased risk of cardiovascular disease (CVD), were determined in the South African population. METHODS: HinfI (677C-->T) and MboII (1298A-->C) restriction enzyme analyses were performed on amplified DNA samples of 76 white, 73 coloured and 60 black subjects. RESULTS: The mutant alleles of mutations 677C-->T and 1298A-->C were more common in the white (allele frequencies 0.36 and 0.37, respectively) than in the black population (0.04 and 0.09), while intermediate frequencies were detected in the coloured population (0.18 and 0.30). Homozygosity for mutation 677C-->T was not detected in the black cohort, while this genotype was detected in 1 coloured (1.4%) and 8 white (10.5%) subjects. In the black population, 5% of the 60 subjects analysed were homozygous for mutation 1298A-->C, compared with approximately 12% in both the white and coloured populations. CONCLUSIONS: Since hyperhomocysteinaemia is a risk factor for premature CVD, the heterogeneous distribution of the 677C-->T and 1298A-->C mutations across ethnic groups may partly explain ethnic differences in heart disease risk through decreased enzyme activity and hence increased homocysteine levels.