L'anoestrus fonctionnel chez la génisse

Article for general public (1987)

Localisation immunocytochimique de l'alphamelanotropine dans le placenta bovin

in Comptes Rendus de l'Académie des Sciences. Série III, Sciences de la Vie (1985), 301(III-2), 41-46

The immunocytochemical study of the bovine placenta has demonstrated the presence of cells containing alphamelanotropic hormones, in the decidual epithelium, since the 4th month of pregnancy. The number ... [more ▼]

The immunocytochemical study of the bovine placenta has demonstrated the presence of cells containing alphamelanotropic hormones, in the decidual epithelium, since the 4th month of pregnancy. The number and the staining intensity of those cells grow up with the placental development. Since the 6th month, we observed the immunoreactional presence of cells in the foetal chorionic epithelium. [less ▲]

L'anoestrus du post-Partum

in Vlaams Diergeneeskundig Tijdschrift (1984), 53

The authors give a survey of the actual knowledge about the fundamental endocrinology of the ovarian cycle in the bovine. In an experiment using 5 dry cows, 20 cows milked twice daily, and 5 freely ... [more ▼]

The authors give a survey of the actual knowledge about the fundamental endocrinology of the ovarian cycle in the bovine. In an experiment using 5 dry cows, 20 cows milked twice daily, and 5 freely suckled cows, a comparative study was made about the post partum ovarian activity by checking heat, by rectal palpation, and by analysis of daily blood and milk samples for ovarian steroids and gonadotropins. For the 3 groups of cows, the first postpartum ovulation was noted at respectively 23, 45, 115 days after parturition. Originally it was thought that a hypersecretion of prolactin was responsible, but no effect could be observed after administration of the prolactin-inhibitor bromocryptine. More recent experimental studies have shown that milking and especially suckling acts as a stess factor, provoking an increased secretion and release of corticosteroids and a decreased blood level of LH, largely responsible for the prolonged post-partum anoestrus period. The logical treatment is weaning, but this technique is often economically difficult to apply in beef cattle. The most indicated alternative treatment to speed up the first postpartum oestrus is the use of the vaginal coil (PRID) containing 2-3 g of progesterone and carrying a capsule with 10 mg of oestradiolbenzoate. The latter stimulates the resorption of progesterone. The coil was removed after 12 days and 500 IU of PMSG were injected. In anoestrous beef cattle, an ovulatory oestrus was induced with a conception rate of 45%. [less ▲]

L'hormone placentaire somato-mammotrope bovine

Post doctoral thesis (1983)

Nos études ont porté en premier lieu sur l’isolement et la purification de l’hormone somato-mammotrope (HPSM) bovine à partir des cotylédons fœtaux de placentas provenant de vaches gestantes de 3 à 6 mois ... [more ▼]

Nos études ont porté en premier lieu sur l’isolement et la purification de l’hormone somato-mammotrope (HPSM) bovine à partir des cotylédons fœtaux de placentas provenant de vaches gestantes de 3 à 6 mois. La préparation d’HPSM purifiée s’est avérée homogène à l’électrophorèse en gel de polyacrylamide. Déterminé par comparaison avec celui de différentes protéines connues, le poids moléculaire de l’HPSM se situe à 33.000 daltons. Son point isolélectrique est de 5,2. Dans les dosages de la prolactine et de l’hormone de croissance par liaison radiocompétitive aux récepteurs membranaires, l’HPSM présente une activité bifonctionnelle, supérieure à celle de s préparations de référence (prolactine PRL-NIH-B4 et hormone de croissance GN-NIH-B18). Marquée à l’iode 125, une partie de l’HPSM conserve intactes ses caractéristiques de liaison. L’HPSM 125 I se lie aux récepteurs hépatiques et mammaires, confirmant l’activité bifonctionnelle de l’hormone. Une liaison spécifique de l’HPSM 125 I est observée chez la vache au niveau de différents tissus tels la glande mammaire, le foie, le corps jaune, l’endomètre et le tissus adipeux. La glande mammaire bovine comporte des sites de liaison différents et spécifiques pour la prolactine et l’hormone de croissance. L’immunisation de lapins au moyen de l’HPSM purifiée a permis l’obtention d’antisérums spécifiques, autorisant la mise au point d’un dosage radioimmunologique sensible. Les cotylédons fœtaux sont trois à quatre fois plus riches en hormone que les cotylédons maternels. Le dosage de l’HPSM dans les liquides amniotiques et allantoïdiens révèle leur faible teneur en hormone. La concentration en HPSM du sérum est élevée chez les fœtus jeunes, elle diminue ensuite régulièrement en fonction de l’âge. L’HPSM apparaît dans le sérum maternel entre le 26ème et le 110ème jour de la gestation. Ensuite, sa concentration s’élève régulièrement jusqu’à la parturition. [less ▲]

Plasma insulin level in double-muscled and conventional bulls during the first year of life

in Zeitschrift für Tierzüchtung und Züchtungsbiologie (1981), 98

Concentration of plasma insulin has been determined by radioimmunoassay in conventional and double-muscled bulls at 80 (I1), 131 (I2), 227 (I3) and 370 I(4) d of age. Double-musceld have lower plasma ... [more ▼]

Concentration of plasma insulin has been determined by radioimmunoassay in conventional and double-muscled bulls at 80 (I1), 131 (I2), 227 (I3) and 370 I(4) d of age. Double-musceld have lower plasma levels of insulin at all ages studied, which is consistent with the reduced fatty tissue of double-muscling. The correlations between insulin level and growth traits, estimated separately fo reach type of bulls, are low and most often positive and significant in double-muscled. Insulin level tends to be negatively correlated with the lean percent from the 7th rib cut. The correlation between the successive insulin levels are generally positive. The correlations between the concentration of insulin and of GH are low and negative. [less ▲]

Isolement d'une hormone placentaire bovine présentant une activité analogue à la prolactine et à l'hormone de croissance

in Annales de Médecine Vétérinaire (1980), 124

Isolation from bovine cotyledon extracts of an hormone with somatotrophic and mammotrophic activity was performed using this hormone during the successive steps of purification, its prolactinic and ... [more ▼]

Isolation from bovine cotyledon extracts of an hormone with somatotrophic and mammotrophic activity was performed using this hormone during the successive steps of purification, its prolactinic and somatotrophic activity was determined by radioreceptor assay. The purified hormone shows a prolactinic activity similar to that of PRL-NIH-B4 standard and a somatotrophic activity three times that of GH-NIH-B18 standard. [less ▲]

Variations nycthémérales de la testostérone et de la lutropine plasmatiques chez le chien

in Annales de Médecine Vétérinaire (1979), 123

Diurnal variations of plasmatic testosterone and lutropin were determined by radioimmunoassay in seven male beagle dogs. Blood samples were withdrawn hourly during 24 hours or every 20 min during 8 hours ... [more ▼]

Diurnal variations of plasmatic testosterone and lutropin were determined by radioimmunoassay in seven male beagle dogs. Blood samples were withdrawn hourly during 24 hours or every 20 min during 8 hours. LH concentrations ranged from 1.2+/-0.6 ng/ml (basal level) to 3.8+/-1.6ng/ml (peak level). Testosterone concentration varied from 1.4+/-0.8ng/ml to 3.5+/-1.8ng/ml. 5 to 8 LH peaks were observed during the 24 hours period and they were generally followed, after about 60 min., by corresponding testosterone peaks. On the other hand, no regular nycthemeral rythm could be established. [less ▲]

Dosages radioimmunologiques

Poster (1978, March)

Induction de l'oestrus chez les génisses en anoestrus fonctionnel

in Annales de Médecine Vétérinaire (1978), 122

Fuctional anoestrus is frequently encountered during winter months and most specially in beef cattle. Ovaries and genital tract display a resting, dormant conditions. Progesterone, 17-beta-oestradiol and ... [more ▼]

Fuctional anoestrus is frequently encountered during winter months and most specially in beef cattle. Ovaries and genital tract display a resting, dormant conditions. Progesterone, 17-beta-oestradiol and LH as measured by radioimmunoassay remain at a very low level. Insertion of an intravaginal device "Abbovestrol Prid" (progesterone 2.3 g 17-beta-oestradiol 10mg) is successful. During the course of the treatment; progesterone reaches normal (corpus luteum induced) levels; 17-beta-oestradiol which is at first very high decreases to a mean value of 4-5 pg/ml; LH remains at a basal level but rises slowly at the end of the treatment. Removal of the insert is generally (16/20) followed by oestrus after c.a. 48 hours. This oestrus is characterized by a normal hormonal profile. However, a PMSG injection when the insert is removed raises chances of favourable result. [less ▲]

Bovine follitropin: Isolation and characterization of the native hormone and its alpha and ß subunits

in Biochimie (1977), 59

1. A reproducible procedure was developed for the purification of bovine follitropin. 2. The methode involved ammonium sulfate precipitation, ion exchange and adsorption chromatography, concanavaline-A ... [more ▼]

1. A reproducible procedure was developed for the purification of bovine follitropin. 2. The methode involved ammonium sulfate precipitation, ion exchange and adsorption chromatography, concanavaline-A-Sepharose chromatography and gel filtration. 3. A specific radioligand receptor assay was used to monitor each chromatographical step. 4. The potency of highly purified bovine follitropin as measured by Steelman and Pohley bioassay was 62 times the NIH-FSH-B1 standard preparation. 5. Contaminations of bovine follitropin by other glycoprotein hormones such as thyrotropin and lutropin amounted to 3 and 0.45 per cent by weight respectively as measured by specific radioimmunoassays and radioligand receptor assays. 6. The subunits alpha and beta of bovine follitropin were obtained by incubation in acidic urea, the chains being then separated by anion exchange chromatography. The subunits were submitted to complete characterization. The amino terminal residue of the alpha subunit is phenylalanine while a half cystine residue was found at the amino-terminal end of the beta chain. 8. Cross-contamination of the alpha and beta subunit preparations was measured by specific radioimmunoassays and amounted to 0.02 and 0.1 per cent by weight respectively. [less ▲]