An evaluation of peripheral blood platelet enumeration as a monitor of fertilization and early pregnancy

Roberts, Timothy K.; Adamson, Louise; Smart, Y. C.; Stanger, James; Murdoch, R. N.

doi:10.1016/s0015-0282(16)59177-8

Cited by 16 publications

(8 citation statements)

References 10 publications

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“…The multiple maternal responses to early pregnancy that are apparently mediated by embryo-derived PAF show that it is released in vivo. Further¬ more, there are several independent reports that untreated ECM injected into mice can induce thrombocytopenia (O'Neill, 1985b;Roberts et al, 1987;Elias et al, 1989). Thus, embryoderived PAF is both active and bioavailable in vivo and can mimic at least one of the known effects of early pregnancy (thrombocytopenia; O'Neill, 1985b).…”

Section: Discussionmentioning

confidence: 99%

The role of albumin in the release of platelet-activating factor by mouse preimplantation embryos in vitro

Ammit¹,

O’Neill²

1997

Reproduction

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Platelet-activating factor (PAF) produced by embryos remained associated with mouse four-cell embryos after culture in vitro and was also released into the medium. The release of PAF into medium required albumin as a media supplement and the amount of PAF released increased (P < 0.05) with increasing albumin concentration. There was a trend for the amount of PAF remaining associated with embryos to decrease as the extracellular albumin concentration increased. The association of released PAF with albumin was confirmed by size fractionation with size exclusion membranes and high performance gel filtration, and by affinity chromatography (Cibacron blue and anti-BSA) and native PAGE. PAF released from embryos was not degraded by serum PAF:acetylhydrolase (PAF:AH; E.C. 3.1.1.47) after exposure for 24 h to the serum in vitro, while an equivalent concentration of synthetic PAF added to identical media was readily degraded, suggesting that PAF released from the embryo was protected from PAF:AH action. However, when the medium was subjected to organic extraction by the Bligh-Dyer (methanol/chloroform) method and the resulting extract added to equivalent media, embryo-derived PAF was readily degraded by PAF:AH. Furthermore, PAF in embryo-conditioned medium (30 two-cell embryos for 24 h) could not be detected after direct assay of the culture medium by radioimmunoassay or bioassay (platelet aggregation in vitro), yet after extraction, purification and addition to medium with BSA, the embryo-derived PAF was readily detected in either assay. To determine whether the different behaviour of synthetic PAF and embryo-derived PAF resulted from differences in the nature of their binding to albumin, the location to which PAF bound was assessed by limited proteolytic digestion of albumin. Digestion with pepsin or trypsin showed that embryo-derived PAF was located exclusively between amino acids 240 and 386 (domain II) of albumin. Most synthetic PAF added to equivalent medium not exposed to embryos was not at this location, suggesting that PAF released from embryos bound to a site on albumin not generally accessible to synthetic PAF added to similar media.

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Section: Discussionmentioning

confidence: 99%

The role of albumin in the release of platelet-activating factor by mouse preimplantation embryos in vitro

Ammit¹,

O’Neill²

1997

Reproduction

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“…Stress also plays a role, as splenectomized mice gently rotated for 3 min experience a significant decrease in their platelet count (Roberts et al, 1987). No apparent signs of stress were visible in the animals used during these samplings.…”

Section: Discussionmentioning

confidence: 99%

Platelet aggregating activity in human embryo culture media free of PAF-acether

et al. 1989

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A factor activating human platelets and liberated by the embryo was sought in the culture media of human embryos using two bioassays. The first bioassay demonstrated the existence of a thrombocytopaenic factor after the i.p. injection of culture media into splenectomized mice. This factor was found more frequently in media which contained an embryo compared to those which contained a non-fertilized oocyte. PAF-acether (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) was searched for with a specific bioassay, using washed rabbit platelets. This remained negative for all the media studied, including those which had contained an embryo giving rise to a pregnancy. In these experiments it was not possible to relate embryo-derived platelet activating factor (EDPAF) to PAF-acether. Neither were we able to use the detection of EDPAF to test embryonic viability, or attempt to identify those embryos which were susceptible to lead to a pregnancy after intrauterine transfer from among all the embryos transferred.

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“…hs(1,4,5)P3 releases Ca2+ from a nonmitochondrial pool which has characteristics to suggest that it is the endoplasmic reticulum, but only part of this pool seems to be Ins(l,4,5)P3-sensitive (Streb et al, 1984). Immunocytochemical studies using a specific antibody on Purkinje cells reveal that Ins(1,4,5)P3 receptor is localized on the nuclear envelope and on parts of the endoplasmic reticulum, near the nucleus (Ross et al, 1989). To release Ca2+, Ins(1,4,5)P3 must bind to receptors that are linked to Ca2* channels connected with the Ins( 1,4,5)P,-sensitive Ca2+ pool.…”

Section: Discussionmentioning

confidence: 99%

Platelet‐activating factor stimulates phospholipase C activity in human endometrium

Ahmed

Smith

1992

Journal Cellular Physiology

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Human preimplantation embryos secrete platelet-activating factor (PAF), which stimulates prostaglandin E2 synthesis from secretory endometrium. This study investigated the action of PAF on phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-specific phospholipase C activity in human endometrium. Slices of normal endometrium were incubated with 5 microCi/ml myo-[2-3H] inositol for 3 h at 37 degrees C in 95% O2 and 5% CO2 to label tissue phosphoinositides. Inositol phosphates were extracted using trichloroacetic acid precipitation and diethylether neutralization and production was measured using Dowex 1-X8 anion-exchange column chromatography. PAF induced rapid and concentration-dependent accumulation of inositol phosphates (IP) from secretory endometrium, but had no effect on endometrium removed in the proliferative phase of the menstrual cycle. The IP3 fraction was significantly elevated from a median value of 14.0 c.p.m. mg-1 dry wt [range: 8-41 c.p.m. mg-1 dry wt] to 28.0 c.p.m. mg-1 dry wt [range: 11-87 c.p.m. mg-1 dry wt, P less than 0.002] following 1 min exposure of secretory endometrium to PAF-acether, in the presence of 10 mM LiCl. PAF-induced hydrolysis of PtdIns(4,5)P2 was inhibited by the specific PAF receptor antagonist WEB 2086, in a dose-dependent manner (P less than 0.02), indicating that in human endometrium PtdIns(4,5)P2 hydrolysis is mediated via a PAF receptor. These results indicate that PAF receptor coupling activates endometrial PtdIns(4,5)P2-specific phospholipase C only in the secretory phase of the menstrual cycle, suggesting that the PAF response may be under ovarian steroid regulation. It is proposed that the ability of the endometrium to respond to PAF appears to be a feature of the preparation of this tissue for implantation and that the second messengers generated may play a role in cellular processes involved in the maternal recognition of very early human pregnancy.

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An evaluation of peripheral blood platelet enumeration as a monitor of fertilization and early pregnancy

Cited by 16 publications

References 10 publications

The role of albumin in the release of platelet-activating factor by mouse preimplantation embryos in vitro

The role of albumin in the release of platelet-activating factor by mouse preimplantation embryos in vitro

Platelet aggregating activity in human embryo culture media free of PAF-acether

Platelet‐activating factor stimulates phospholipase C activity in human endometrium

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