Investigation on placental lactogen in bovine foetus
Alvarez Oxiley, Andrea Vivian
Doctoral thesis (2012)Detailed reference viewed: 134 (6 ULg)
Effect of exogenous circulating anti-bPL antibodies on bovine placental lactogen measurements in foetal samples.
Alvarez Oxiley, Andrea Vivian ; Melo de Sousa, Noelita ; Hornick, Jean-Luc et al
in Acta Veterinaria Scandinavica (2010), 52
BACKGROUND: The involvement of placental lactogen (PL) in the regulation of foetal growth has been investigated in different species by in vivo immunomodulation techniques. However, when circulating ... [more ▼]
BACKGROUND: The involvement of placental lactogen (PL) in the regulation of foetal growth has been investigated in different species by in vivo immunomodulation techniques. However, when circulating antibodies are present together with the hormone, the procedure for hormonal measurement becomes considerably complex. The aim of this study was the immunoneutralization of bovine placental lactogen (bPL) concentrations in bovine foetal circulation by direct infusion of rabbit anti-bPL purified immunoglobulins (IgG) via a foetal catheter (in vivo study). The ability of a RIA based on guinea pig anti-bPL antiserum, for the measurement of bPL concentrations in samples containing exogenous rabbit anti-bPL immunoglobulins, was also analyzed in in vitro and in vivo conditions. METHODS: Six bovine foetuses were chronic cannulated on the aorta via the medial tarsal artery. Infusion of rabbit anti-bPL IgG was performed during late gestation. Pooled rabbit anti-bPL antisera had a maximal neutralization capacity of 25 microg bPL/mL of immunoglobulin. Interference of rabbit anti-bPL immunoglobulin with radioimmunoassay measurement using guinea pig anti-bPL as primary antibody was first evaluated in vitro. Polyclonal anti-bPL antibodies raised in rabbit were added in foetal sera to produce 100 samples with known antibodies titers (dilutions ranging from 1:2,500 till 1:1,280,000). RESULT(S): Assessment of the interference of rabbit anti-bPL antibody showed that bPL concentrations were significantly lower (P < 0.05) in samples added with dilutions of rabbit antiserum lower than 1:80,000 (one foetus) or 1:10,000 (four foetuses). It was also shown that the recovery of added bPL (12 ng/mL) was markedly reduced in those samples in which exogenous rabbit anti-bPL were added at dilutions lower than 1:20,000. Concentrations of foetal bPL were determined in samples from cannulated foetuses. In foetuses 1 and 6, bPL concentrations remained almost unchanged (<5 ng/mL) during the whole experimental period. In Foetus 3, bPL concentrations decreased immediately after IgG infusion and thereafter, they increased until parturition. CONCLUSION(S): The use of a bPL RIA using a guinea pig anti-bPL as primary antiserum allowed for the measurement of bPL concentrations in foetal plasma in presence of rabbit anti-bPL IgG into the foetal circulation. Long-term foetal catheterization allowed for the study of the influence of direct infusion of anti-bPL IgG on peripheral bPL concentrations in bovine foetuses. [less ▲]Detailed reference viewed: 103 (17 ULg)
Native and recombinant bovine placental lactogens.
Alvarez Oxiley, Andrea Vivian ; Melo de Sousa, Noelita ; Beckers, Jean-François
in Reproductive Biology (2008), 8(2), 85-106
The bovine placenta produces a wide variety of proteins that are structurally and functionally similar to the pituitary proteins from the GH/PRL gene family. Bovine placental lactogen (bPL) is a 200-amino ... [more ▼]
The bovine placenta produces a wide variety of proteins that are structurally and functionally similar to the pituitary proteins from the GH/PRL gene family. Bovine placental lactogen (bPL) is a 200-amino acid long glycoprotein hormone that exhibits both lactogenic and somatogenic properties. The apparent molecular masses of purified native (n) bPL molecules (31-33 kDa) exceed 23 041 Da, which is the theoretical molecular mass of the protein core. At least six isoelectric variants (pI: 4.85-6.3) of bPL were described in cotyledonary extracts and three different bPL isoforms (pI: 4.85-5.25) were found in fetal sera. The bPL molecules that are detected in higher concentrations in peripheral circulation exhibit a more acidic pI than those present in placental homogenates. This may reflect an important glycosylation process occurring just prior to the bPL secretion. The bPL mRNA is transcribed in trophectoderm binucleate cells starting from Day 30 of pregnancy until the end of gestation. In mothers, bPL is involved in the regulation of ovarian function, mammogenesis, lactogenesis, and pregnancy stage-dependent adaptation of nutrient supplies to the fetus. Due to the higher fetal, compared to maternal concentrations of circulating hormone, it has been suggested that bPL primarily targets fetal tissues. [less ▲]Detailed reference viewed: 31 (1 ULg)
The Pregnancy-Associated Glycoproteins: Biochemical Aspects and Clinical Application for Pregnancy Follow-up
Melo de Sousa, Noelita ; ; Bella, Amina et al
Pregnancy diagnosis is an important part in reproduction management of ruminants. In the last years, a large polymorphic family of placenta-expressed proteins has been discovered in ruminant species and ... [more ▼]
Pregnancy diagnosis is an important part in reproduction management of ruminants. In the last years, a large polymorphic family of placenta-expressed proteins has been discovered in ruminant species and used for pregnancy diagnosis. Members of this family are named pregnancy-associated glycoproteins (PAG), being synthesized in the mono- and binucleate cells of the ruminant’s trophectoderm. Part of them are released in the maternal blood circulation where they can be assayed by different laboratory techniques. Due to large variety of expressed molecules and to large variations in the post-translational processing of the PAG, different immuno-systems present different ability to quantify the PAG released in blood. The sensitivity (92 to 100%) and specificity of PAG radioimmunoassay when used for pregnancy diagnosis are very high. The assay of PAG can also bring very interesting information for researchers working in programs focused on the study of embryonic and fetal mortalities, as well as on embryo biotechnology (ET, FIV, clonage), animal nutrition, or infections diseases resulting in pathologies affecting the pregnancy. [less ▲]Detailed reference viewed: 41 (1 ULg)
Fetal profiles of bovine placental lactogen (PL) and insulin like growth factors (IGF-I and IGF–II) through the late gestation
Alvarez Oxiley, Andrea Vivian ; Melo de Sousa, Noelita ; et al
in Prooceedings of the 10e Journée de Rencontre Bioforum (2006)Detailed reference viewed: 136 (0 ULg)
A preliminary study of serum haptoglobin in bovine fetal blood.
Humblet, Marie-France ; Melo de Sousa, Noelita ; et al
in Proceedings of the 6th European Colloquium on Acute Phase Proteins (2006)Detailed reference viewed: 12 (0 ULg)
Validation of two homologous radioimmunoassays for measuring pregnancy-associated glycoprotein in ewes.
; ; et al
in Reproduction in Domestic Animals (2003), 38(4), 358Detailed reference viewed: 11 (1 ULg)
Pregnancy-associated glycoprotein concentrations in plasma and milk samples for early pregnancy diagnosis in Lacaune dairy sheep.
; ; et al
in Reproduction in Domestic Animals (2003), 38(4), 322Detailed reference viewed: 8 (0 ULg)