Effects of repeated freeze-thaw cycles on concentrations of cholesterol, micronutrients, and hormones in human plasma and serum.

been demonstrated in cytotrophoblasts obtained from the placental beds of preeclamptic pregnancies (14). Increased incidence of apoptosis involving syncytiotropho-blasts has also been reported in preeclampsia (15). Further research on the correlation between fetal DNA concentrations and incidence of placental apoptosis may help to confirm this link. The potential clinical implication of our findings is that maternal plasma fetal DNA might be used as marker for predicting preeclampsia. However, our data showed that there was overlap in the fetal DNA concentrations between the preeclamptic and control groups. This implies that a relatively low sensitivity and specificity would result if maternal plasma fetal DNA measurement is used as the sole predictor for preeclampsia. Thus, ROC curve analysis (MedCalc 5.0) revealed that the best discrimination between the preeclamptic and control groups was obtained at a fetal DNA concentration of 33.5 genome-equivalents/mL. The sensitivity and specificity at this cutoff concentration were 67% (95% confidence interval, 41– 87%) and 82% (95% confidence interval, 65–93%), respectively. The area under the ROC curve was 0.778 (SE ϭ 0.073; 95% confidence interval, 0.639 – 0.882). Nonetheless , our data open up the possibility of predicting preeclampsia using maternal plasma fetal DNA, especially when used with other biochemical markers such as corticotropin-releasing hormone, ␣-fetoprotein, inhibin A, and activin A (16, 17). In this regard, it is also important to explore the use of fetal DNA markers outside the Y chromosome so that this type of analysis can be extended to pregnant women carrying female fetuses. Assays that are potentially applicable in this capacity have recently been described (18 –20). Finally, our preliminary data would serve to stimulate further large-scale studies to explore the possible correlation of this new marker to the severity of the disease. Pre-eclampsia is associated with widespread apoptosis of placental cytotrophoblasts within the uterine wall. Analysis of mid-trimester corticotrophin-releasing hormone and ␣-fetoprotein concentrations for predicting pre-eclampsia. al. Serum inhibin A and activin A are elevated prior to the onset of pre-eclampsia. The effects of repeated freeze-thaw cycles on concentrations of various analytes in plasma or serum were of little interest until the growth of plasma and serum banks during the latter part of the 20th century. By 1996, the number of such banks used primarily for cancer research had grown to 115 (1). Many also exist for other purposes, such as the WHO Serum Reference Banks (2) and banks associated with cardiovascular studies such as the …