References of "Ectors, Francis"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailFractionation and partial characterization of proteins extracted from the bovine fallopian tube: preparation of tools for further purifications
Remy, Benoît ULg; Rabahi, F.; Duwez, L. et al

in Theriogenology (1995), 44(1), 95-107

Described in the present paper is a combined biochemical and immunological approach to study oviductal proteins in the bovine. Antisera were raised against semi-purified proteins extracted from bovine ... [more ▼]

Described in the present paper is a combined biochemical and immunological approach to study oviductal proteins in the bovine. Antisera were raised against semi-purified proteins extracted from bovine tubal mucosal tissue and were characterized. These antisera are available to monitor puritications of specific oviductal proteins in the future. Oviducts from 170 cyclic cows were collected at a slaughterhouse, and high amounts of mucosal proteins were extracted. The proteins were fractionated after precipitation with ammonium sulfate, anti-bovine serum albumin (bSA) and anti-bovine immunoglobulins bIg) afiinity chromatography and ion exchange chromatography. Each of the 12 fractions obtained after ion exchange chromatography was used to immunize a rabbit. Conditioned media were recovered from bovine oviduct cell monolayers cultured without serum to cot&m the oviductal origin of the extracted proteins. After Western blot analysis, 15 proteins were detected in the bovine oviductal extracts, and their molecular weights and isoelectric points were determined by 2 dimensional electrophoresis. Among these 15 proteins, 11 were also detected in conditioned media of bovine oviductal cells. These results demonstrate an oviductal origin of the 11 detected proteins and strongly suggest their secretion by the oviductal cells. [less ▲]

Detailed reference viewed: 38 (1 ULg)
Full Text
Peer Reviewed
See detailIsolement et caractérisation partielle d'une glycoprotéine associée à la gestation chez la brebis
Zoli, A. P.; Beckers, Jean-François ULg; Ectors, Francis ULg

in Annales de Médecine Vétérinaire (1995), 139

Detailed reference viewed: 21 (0 ULg)
Full Text
Peer Reviewed
See detailMolécules de la famille des protéases aspartiques dans le placenta des ruminants: hormones ou protéines ?
Beckers, Jean-François ULg; Roberts, R. Michael; Zoli, André Pagnah et al

in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (1994), 149(8-11), 355-367

The placenta of ruminant contains binucleate trophoblastic cells synthesizing proteins, migrating cross the barrier and fusing with endothelial cells of the endometrium. Recently described were two ... [more ▼]

The placenta of ruminant contains binucleate trophoblastic cells synthesizing proteins, migrating cross the barrier and fusing with endothelial cells of the endometrium. Recently described were two glycoproteins from the family of aspartic proteases, apparently lacking the enzymatic activity: the pregnancy associated glycorproteins I and II (PAGI and PAGII). The first (PAGI) is largely secreted in maternal blood, this characteristic copes with the lack of proteolytic activity. The second (PAGII) is not completely characterized. However, it binds to lutropin (LH) receptors with high affinity. This binding allows to assume that PAGII is likely the same as the bovine chorionic gonadotropin identified earlier (bCG). A better characterization of these glycoproteins (PAGI and PAGII) and other members of the family (PAGIII...) will answer these questions together with the unexplained invasive process of the placenta. [less ▲]

Detailed reference viewed: 125 (5 ULg)
Full Text
Peer Reviewed
See detailLe point sur la production d’embryons in vitro: limitations et perspectives de la recherche
Thonon, Fabienne; Ectors, Fabien ULg; Delval, Alain et al

in Annales de Médecine Vétérinaire (1994), 138(1), 33-40

Recent progress in gamete biology and early embryo development was responsible for great evolution of reproduction techniques in farm animals. Among these techniques, in vitro production of bovine embryos ... [more ▼]

Recent progress in gamete biology and early embryo development was responsible for great evolution of reproduction techniques in farm animals. Among these techniques, in vitro production of bovine embryos was developed from slaughterhouse ovaries. This method has been used for individual animals. However, large variations in results were observed, due to several factors, including reproductive state and age of the donor. Inspite of this limitation, in vitro production of bovine embryos may be helpful, when slaughtering of valuable cows is recommended eg for brucellosis disease. Researches are purchased in order to increase the number of oocytes obtained per "elite" cow and to improve the ability of in vitro embryos to support freezing. [less ▲]

Detailed reference viewed: 192 (9 ULg)
Full Text
Peer Reviewed
See detailClonage par greffe de blastomère: naissance d'un premier veau
Ectors, Fabien ULg; Delval, Alain; Touati, Kamal ULg et al

in Annales de Médecine Vétérinaire (1993), 137(8), 573-574

Detailed reference viewed: 51 (8 ULg)
Full Text
See detailLe clonage par transfert de noyau dans l'espèce bovine: premiers résultats
Ectors, Francis ULg; Ectors, Fabien ULg; Delval, Alain et al

in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (1993), 148

In 1987, Prather et al. have performed the first embryo cloning by nuclear transfer in the bovine species. Since, many researchers try to develop and to apply the technique. While the enucleation of the ... [more ▼]

In 1987, Prather et al. have performed the first embryo cloning by nuclear transfer in the bovine species. Since, many researchers try to develop and to apply the technique. While the enucleation of the recipient oocyte, the injection of the donor blastomere and the fusion procedure are now well controlled, on the other hand, maturation and activation as the development and freezing of the cloned embryos need tobe more investigated. The cloned embryo is more fragile. An increase in embryonic mortality is observed after transfer in a recipient cow. [less ▲]

Detailed reference viewed: 83 (3 ULg)
Full Text
Peer Reviewed
See detailClonage par transfert de noyau dans l'espèce bovine: premiers résultats
Ectors, Fabien ULg; Delval, Alain; Touati, Kamal ULg et al

in Annales de Médecine Vétérinaire (1993), 137(6), 427-431

Detailed reference viewed: 19 (5 ULg)
Full Text
Peer Reviewed
See detailPurification and characterization of a bovine pregnancy-associated glycoprotein
Zoli, André Pagnah; Beckers, Jean-François ULg; Wouters-Ballman, Patricia et al

in Biology of Reproduction (1991), 45(1), 1-10

A 67000 Mr bovine pregnancy-associated glycoprotein (bPAG) has been isolated from fetal cotyledons and purified to homogeneity by HPLC. The purification was monitored by a double immunodiffusion test and ... [more ▼]

A 67000 Mr bovine pregnancy-associated glycoprotein (bPAG) has been isolated from fetal cotyledons and purified to homogeneity by HPLC. The purification was monitored by a double immunodiffusion test and by RIA in conjunction with an antiserum raised against a crude fraction of placenta-specific antigens. The molecular weight of bPAG was estimated to be 67000 by SDS-PAGE. The isoelectric points (pI) of the four isoforms, determined by high-resolution analytical electrofocusing in polyacrylamide gel, were 4.4, 4.6, 5.2, and 5.4. The carbohydrate content of the bPAG consisted of approximately 10.02 +/- 1.09% neutral sugar and variant amounts of sialic acid (from 0.29 +/- 0.06% in the most basic isoform to 2.1 +/- 0.31% in the most acidic isoform). A specific antiserum was raised against the purified bPAG. A specific RIA showed that the bPAG was antigenically unrelated to BSA, alphafetoprotein (AFP), and human schwangerschafts-spezifischen (pregnancy-specific) beta 1 glycoprotein (SP1). According to some characteristics (e.g. the molecular weight), the purified bPAG may correspond to a form of the pregnancy-specific protein B previously described by Sasser and colleagues (Biol Reprod 1986; 35:936-942). [less ▲]

Detailed reference viewed: 51 (6 ULg)
Full Text
See detailMultiplication des embryons chez les bovins: possibilités actuelles et futures
Ectors, Francis ULg; Beckers, Jean-François ULg; Ectors, Fabien ULg et al

in Biotechnologie en Sélection animale - IRSIA (1989)

Since several years, research efforts have been focused towards improving the reproductive potential of domestic animals. The authors present a review of different technics in particular the ... [more ▼]

Since several years, research efforts have been focused towards improving the reproductive potential of domestic animals. The authors present a review of different technics in particular the superovulation and priming, embryo micromanipulation and clonage. The technic of superovulation allows an increase of the total number fo the offspring by an increase of the ovocytes total number. Different FSH injections at the end of the cycle, preceded by small FSH quantity at the beginning of the cycle, procure a great number of mature follicles available for reproduction. Micromanipulation allows a multiplicaton by sectioning the embryo in two or more segments. Isolated blastmeres can also be used but it was observed that those cells very rapidly loose their differentiation potential. Clonage allows the reproduction of an animal from only one of his own cells. The nucleus of this cell is extracted and reimplanted in an enucleated ovocyte. Meanwhile from a practical point of vue, this technic is, at present, only possible using a stem cell and not using a mature somatic cell. [less ▲]

Detailed reference viewed: 86 (2 ULg)
Full Text
Peer Reviewed
See detailEffet d'une préstimulation ovarienne en début de cycle sur la réponse au traitement de superovulation chez la vache
Touati, Kamal ULg; Bormans, M.; Ectors, Fabien ULg et al

in Annales de Médecine Vétérinaire (1989), 133

In this study, we have induced superovulation in 67 heifers according to a known based treatment based on the administration of 32 mg (Armour Units) of FSH/LH (ratio LH/FSH=20%). The animals were divided ... [more ▼]

In this study, we have induced superovulation in 67 heifers according to a known based treatment based on the administration of 32 mg (Armour Units) of FSH/LH (ratio LH/FSH=20%). The animals were divided in two groups: 30 control and 37 receiving 2.5mg (Armour units) of pure FSH on the third day and the fourth day of the estrous cycle. This pretreatment ("priming") was followed by a larger number of total (11.7 versus 6.4) and transferable (7.1 versus 3.6) embryos. This experiment demonstrates the efficiency of low doses of pure FSH administered 6 or 8 dyas before a superovulation in the final selection of ovarian follicles. [less ▲]

Detailed reference viewed: 108 (10 ULg)
Full Text
Peer Reviewed
See detailMise au point sur la folliculogenèse
Touati, Kamal ULg; Ectors, Fabien ULg; Beckers, Jean-François ULg et al

in Annales de Médecine Vétérinaire (1989), 133

Folliculogenesis is usually divided in two stages: the first one going from the primordial follicle to the secondary or preantral, the second leading the preantral follicle to the preovulatory or Graafian ... [more ▼]

Folliculogenesis is usually divided in two stages: the first one going from the primordial follicle to the secondary or preantral, the second leading the preantral follicle to the preovulatory or Graafian follicle. During the first period, follicular development is depending on intra ovarian factors mainly of growth-factors. However, many studies involve the FSH hormone in this period, when follicles have reached the 40 cells stage. During the second period, FSH plays an essential role in follicular growth and maturation. Regulatory process for FSH secretion and liberation depends mainly on inhibin. This fact is underlined in many species by typical FSH secretion profiles. The FSH levels can explain the ovarian control leading to one or to a limited number of preovulatory follicles according to the species characteristic (dominant follicle). [less ▲]

Detailed reference viewed: 431 (7 ULg)
Full Text
Peer Reviewed
See detailDetermination of porcine plasma follitropin levels during superovulation treatment in cows
Demoustier, M.; Beckers, Jean-François ULg; Van Der Zwalmen, P. et al

in Theriogenology (1988), 30(2), 379-386

Porcine follicle stimulating hormone (pFSH) and porcine luteinizing hormone (pLH), are widely used to induce superovulation in cows. An advantage of this treatment is that the LH:FSH ratio can be varied ... [more ▼]

Porcine follicle stimulating hormone (pFSH) and porcine luteinizing hormone (pLH), are widely used to induce superovulation in cows. An advantage of this treatment is that the LH:FSH ratio can be varied to optimize the growth of the ovarian follicles. However, due to the relatively short half-life of FSH, the superovulatory treatment requires numerous injections. A performant radioimmunoassay system (sensitivity=0.2 ng/ml plasma) was used to determine plasma pFSH levels in cows that were superovulated with 2 daily injections of 4 Armour Units (A.U.) of pFSH for 4 d. From plasma profiles, the half-life and the disappearance of pFSH were estimated at 5 h and at 10 to 12 h, respectively, confirming the necessity of using two daily injections. [less ▲]

Detailed reference viewed: 85 (10 ULg)
Full Text
Peer Reviewed
See detailObtention de blastocystes après maturation et fécondation in vitro d'ovocytes de bovin: premiers résultats
Ectors, Fabien ULg; Van Der Zwalmen, P.; Touati, Kamal ULg et al

in Annales de Médecine Vétérinaire (1988), 132

74.4% of two cells cow embryos are following in vitro maturation and fertilisation. Some embryos developed in rabbit's oviducts to morula and blastocyst stages. They wer frozen and thawed before transfer ... [more ▼]

74.4% of two cells cow embryos are following in vitro maturation and fertilisation. Some embryos developed in rabbit's oviducts to morula and blastocyst stages. They wer frozen and thawed before transfer in receptors. [less ▲]

Detailed reference viewed: 86 (7 ULg)
Full Text
Peer Reviewed
See detailL'anoestrus du post-Partum
Derivaux, Jules; Beckers, Jean-François ULg; Ectors, Francis ULg

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 ▲]

Detailed reference viewed: 305 (7 ULg)
Full Text
Peer Reviewed
See detailDosage de l'hormone placentaire somatotrope et mammotrope bovine par liaison radio-compétitive aux récepteurs membranaires
Beckers, Jean-François ULg; Ectors, Francis ULg

in Annales de Médecine Vétérinaire (1981), 125

Bovine placental somatomammotropin was labelled with I125 using the lactoperoxidase method. This allowed the development of radioreceptor assays using hepatic and mammary tissues of pregnant rabbits ... [more ▼]

Bovine placental somatomammotropin was labelled with I125 using the lactoperoxidase method. This allowed the development of radioreceptor assays using hepatic and mammary tissues of pregnant rabbits. These assays were used to compare binding properties to hepatic and mammary receptors of highly purified Bovine Placental Somatomammotropin and the native hormone present in cotyledons. Normal levels of this hormone in foetal and maternal cotyledons were also determined using these assays. [less ▲]

Detailed reference viewed: 77 (7 ULg)
Full Text
Peer Reviewed
See detailIsolement d'une hormone placentaire bovine présentant une activité analogue à la prolactine et à l'hormone de croissance
Beckers, Jean-François ULg; Fromont-Liénard, Ch; Van Der Zwalmen, P. et al

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 ▲]

Detailed reference viewed: 213 (5 ULg)
Full Text
Peer Reviewed
See detailEffet de l'azide de sodium sur la dégradation de la progestérone dans les échantillons de sang total chez les bovins
Delahaut, Philippe; Beckers, Jean-François ULg; Ectors, Francis ULg

in Annales de Médecine Vétérinaire (1979), 123

Progestérone degradation was measured in bovine blood samples left on the bench in air at room temperature for a few days. Progesterone level is reduced by 50% after 4 to 6 h and this degradation seems to ... [more ▼]

Progestérone degradation was measured in bovine blood samples left on the bench in air at room temperature for a few days. Progesterone level is reduced by 50% after 4 to 6 h and this degradation seems to be due to the presence of red blood cells. The addition to each sample of 5 mg/ml sodium azide assure a 90% protection of progesterone after 4 day room temperature. [less ▲]

Detailed reference viewed: 328 (13 ULg)
Full Text
Peer Reviewed
See detailVariations nycthémérales de la testostérone et de la lutropine plasmatiques chez le chien
De Coster, R.; Beckers, Jean-François ULg; Wouters-Ballman, Patricia et al

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 ▲]

Detailed reference viewed: 221 (1 ULg)
Full Text
Peer Reviewed
See detailVariations de la LH, de la FSH, du 17 ß oestradiol et de la progestérone au cours du cycle oestral de la chienne
De Coster, R.; Beckers, Jean-François ULg; Wouters-Ballman, Patricia et al

in Annales de Médecine Vétérinaire (1979), 123

Plasma levels of progesterone, 17-beta-oestradiol, LH and FSH were measured by radioimmunoassay in five beagle bitches during two consecutive estrous cycles. Progesterone level rises at the end of ... [more ▼]

Plasma levels of progesterone, 17-beta-oestradiol, LH and FSH were measured by radioimmunoassay in five beagle bitches during two consecutive estrous cycles. Progesterone level rises at the end of proestrus to reach 40 to 50ng/ml and then decreases progressively to its basal level (0.64 ng/ml), attained 80 to 100 days after oestus. A 17-beta-oestradiol peak (75.1 pg/ml) is evident in proestrus and reaches its maximum level 24h before LH surge. The fall of estrogen leads to a discharge of gonadotropins lasting 48 to 72 hours. The FSH surge reaches his maximum level 48 h after that of LH. Pregnancy does not change the secretory pattern of these hormones but progesterone falls just before parturition. [less ▲]

Detailed reference viewed: 336 (5 ULg)