Pregnancy: Differential increase in the maternal serum concentrations of the placental proteins human chorionic gonadotrophin, pregnancy-specific β1-glycoprotein, human placental lactogen and pregnancy-associated plasma protein-A during the first half of normal pregnancy, elucidated by means of a mathematical model

Abstract

The present study was performed to compare the increase in maternal serum concentrations of four placental proteins during the first half of 240 normal pregnancies. The proteins were pregnancy-associated plasma protein-A (PAPP-A), human chorionic gonadotrophin (HCG), human placental lactogen (HPL) hormone, and pregnancy-specific beta 1-glycoprotein (PSG), all produced by trophoblast cells. The median increases were observed to be very close to exponential growth curves. Based on simple assumptions, these growth curves could be explained as being solely dependent on the growth of the placenta. The assumptions were that the proteins were produced in the placenta at a constant rate per gram of placental cell mass and secreted into the circulation shortly after synthesis. Our investigations showed that for two of the proteins, PSG and HPL, the rate constants were, in fact, close to the reported growth rate of the placenta, whereas the PAPP-A production rate constant was significantly higher than those of the others. The production curve for HCG was very different from that of the other proteins. PAPP-A and HCG must therefore have more complicated mechanisms for regulating the production. An equation was constructed that permitted estimation of the molar production of the placental proteins per gram of placental cell mass per day during the first half of normal pregnancy. The value was highest for HPL and lowest for PAPP-A.

Schwangerschaftsprotein 1 (Sp1) as a Maternal Serum Marker for Down Syndrome in the First and Second Trimesters

“…The values found for MSSP1 in normal controls correspond well to values reported by others (Lenton et al, 1981;Sørensen et al, 1995) and the distribution as a function of the gestational age, with an early very steep rise followed by what could be considered an exponential rise with decreasing slope, has previously been suggested as a model for the development of MSSP1 over gestational age (Sørensen et al, 1995). This finding, together with the good operational characteristics of the TrIFMA as described in this study, makes the TrIFMA suitable for inclusion in large volume screening programmes, particularly so, as a system for automation and simultaneous determination of other parameters by timeresolved immunofluorescence is commercially available (Wallac OY, Turku, Finland).…”

Comparison of syncytiotrophoblast generated from human embryonic stem cells and from term placentas

“…The pregnancy-specific glycoprotein (PSG) family of genes is expressed abundantly in the human placenta and can be detected in maternal serum, with concentrations rising as placental size increases (28). Interestingly, the PSG genes were expressed almost exclusively by PHTd, with only PSG4 transcripts detected above background in ESCd >70 (SI Appendix, Fig.…”

The Development of a Genetic Profile of Placental Gene Expression during the First Trimester of Pregnancy: A Potential Tool for Identifying Novel Secreted Markers

“…The RNA expression levels of HGF, PGF, hPL and PSG were all found to be up-regulated at week 13 compared to week 9. The levels of HGF have been found to rise significantly from the 10th week of pregnancy [16], PGF from the 15th week of pregnancy [17], hPL rising exponentially throughout pregnancy [4] and PSG rising from weeks 8 to 21 [3]. The ability of our procedure to detect changes at the mRNA expression level of these known and important secreted genes in the placenta is encouraging and opens up the possibility of identifying novel secreted proteins from the pool of 118 unknown genes and ESTs we have identified.…”

“…We chose to establish our placental gene profile on a comparison between normal placenta at different developmental stages instead of a comparison with aberrant placenta for a number of reasons. Many of the best diagnostic markers available are currently based on secreted placental proteins which are found to vary normally between two time points in the first trimester such as chorionic gonadotropin [1], pregnancy-associated plasma protein A [2], PSG [3] and hPL [4]. Also, we wanted to produce a profile of pregnancy events as early as possible to identify useful early markers.…”

“…Many of the best diagnostic markers are currently based on secreted placental proteins, which are found to vary normally between two time points in the first trimester. Some of these include chorionic gonadotropin [1], pregnancy-associated plasma protein A [2], pregnancyspecific ß 1 -glycoprotein (PSG) [3] and placental lactogen (hPL) [4]. Molecular profiling will allow the identification and characterisation of gene and hence protein expression Page/Butlin/Manyonda/Lowry patterns and cellular pathway modifications associated with physiological events at the onset.…”