Early Pregnancy Serum Research Articles

Serological detection of early pregnancy in cattle and partial characterization of a serum glycoprotein associated with early pregnancy

Sera from heifers prior to artificial insemination (AI), 1–8 days after AI, and 7 days after embryo removal were investigated by crossed immunoelectrophoresis (CIE) by use of rabbit antiserum produced against bovine early pregnancy serum and intensively absorbed with non-pregnancy serum. One precipitation peak appeared in the α-globulin region when sera of non-pregnant heifers were under study. An additional peak could be demonstrated in the same region when sera of early pregnant heifers were investigated. By this method 91.5% of 71 sera samples were classified correctly to be pregnant or non-pregnant. The glycoprotein character of the above two serum components could be shown by binding to concanavalin A (Con A) in lectin affinity CIE. Relative molecular weights were estimated to be about 70,000 and 80,000 for the peptides of these two proteins applying sodium dodecyl sulfate polyacrylamide gel electrophoresis of precipitates cut out from CIE-plates. As shown previously close relation of this early pregnancy associated protein (EPAP) to the early pregnancy factor is supposed because of its characteristics and its ability to affect cellular immunity.

CIRCULATING LEVELS OF PREGNANCY PROTEINS IN EARLY AND LATE PREGNANCY IN RELATION TO PLACENTAL TISSUE CONCENTRATION

The concentrations of human chorionic gonadotrophin (hCG), human placental lactogen (hPL), pregnancy specific beta 1 glycoprotein (SP1), ferritin (PP2) and placental protein 5 (PP5) were examined in maternal serum and placental tissue in early and late pregnancy. The circulating concentration of hPL, SP1, and PP5 were higher during late pregnancy than early pregnancy, that of hCG lower, and ferritin (PP2) levels showed no difference. Placental tissue levels of hPL and SP1 were higher in late pregnancy, hCG levels lower, and ferritin (PP2) and PP5 showed no change. The ratio of the concentration in maternal serum to that in placental tissue increased during pregnancy for all proteins with the exception of ferritin. It is proposed that the mechanism of secretion of trophoblast specific proteins varies widely and that this should be taken into account in the clinical interpretation of circulating levels in the mother.

Human placental lactogen (HPL) in serum in complicated early pregnancy.

SummaryThe clinical value of maternal serum HPL concentrations determined by radio‐immunoassay in complicated early pregnancy was studied between the 6th and 20th weeks of pregnancy. The subjects were 203 normally pregnant women and 188 whose pregnancy was complicated by uterine bleeding. In threatened abortion where the pregnancy continued successfully (102 patients) the HPL level was generally similar to that in normal pregnancy and showed a pattern of increase in serial determinations. In complicated pregnancies with an unsuccessful outcome (blighted ovum 19, incomplete abortion 42, and missed abortion 25) HPL values were low and decreased in serial samples. A single HPL determination seemed to be a sufficiently reliable index of viable pregnancy from the 14th week onwards, but before that serial HPL samples would seem to be needed.

Concerning Gonadotropic Substances in Mare Serum

Evans et al. have shown that there is a wide distribution of a substance in the urine and blood serum of mammals which resembles prolan, in that when it is mixed in vitro with the pituitary synergist the effect upon the ovary of the immature rat is enhanced. Evidence that a similar prolan-like substance is present in the blood serum of the non-pregnant and pregnant mare is given in Table 1. Further the data indicate that the prolan-like substance is distinct from the substance in the blood serum of the pregnant mare which is so highly effective in stimulating the gonads when given alone. Following our nomenclature in previous publications we will term the latter substance the gonad-stimulating hormone. Referring to Table 1 it may be seen that equivalent amounts of non-pregnant and mid-pregnancy mare serum are equally effective in stimulating the gonads of immature rats when combined with the pituitary synergist. The amount of gonad-stimulating hormone present in the 2 types of sera differs greatly. Two cc. of the mid-pregnancy serum when given alone induces follicular development and luteinization whereas 10 cc. of the non-pregnant serum produces no response. In fact, we have shown previously that doses of 60 cc. of non-pregnant serum are without response on the immature rat. Thus it is clear that there is no relationship between the response of the serum when given alone and the response of serum plus synergist. This fact is further demonstrated when the response of early pregnancy blood serum highly potent in gonad-stimulating hormone is compared to non-pregnant serum. The amount of early pregnancy serum injected contained 2 to 4 rat units of gonad-stimulating hormone while the non-pregnant serum contained none. Still the response of the early pregnancy serum plus synergist was less than the non-pregnant serum plus synergist.