Patricia Wouters-Ballman

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).

SUMMARY Concentrations of estrogen ( er ) and progesterone ( pr ) receptors were measured by radioreceptor assay in tumor (n = 319) and normal (n = 166) mammary tissue from 248 bitches. Correlations between er and pr and between receptor expression in tumor and normal mammary tissue from the same bitches were evaluated. The influence of tumor, clinical, or hormonal variables on receptor expression also was studied. Approximately 80% of tumor and 95% of normal mammary tissue expressed detectable concentrations of er , pr , or both. Direct correlation was found between er and pr concentrations in normal and tumor tissues. Median er concentrations were significantly higher (46 ± 47 fmol/mg of cytosolic protein vs 27 ± 24 fmol/mg of cytosolic protein; P = 0.0002) in normal than in tumor tissue. On the other hand, pr concentrations were significantly higher (57 ± 52 fmol/mg vs 77 ± 99 fmol/mg; P = 0.03) in tumors (especially benign tumors) than in normal tissue. Poorly differentiated malignant tumors expressed lower concentrations of receptors than did benign or well differentiated malignant tumors. The er and pr concentrations decreased with increasing size of the lesion. Hormonal status of the bitch significantly ( P < 0.05) influenced receptor expression in normal tissue: bitches in the luteal phase of the estrous cycle had higher concentrations of er (69 ± 62 fmol/mg) than did ovariectomized bitches (24 ± 19 fmol/mg) or bitches in anestrus (38 ± 45 fmol/mg) or the follicular phase (13 ± 7 fmol/mg). For pr , higher concentrations were observed in normal tissue during anestrus than during pseudopregnancy or in bitches treated with medroxyprogesterone acetate. Similar, but nonsignificant, variations were seen in tumor tissue except in medroxyprogesterone acetate-treated bitches in which pr concentrations were high in tumors and low in normal tissue from the same bitches. Significant relation between age, hormonal history, number or location of lesions, and receptor expression was not observed. However, significantly ( P < 0.05) lower receptor concentrations were found in the normal tissue from the 3 cranial pairs of mammary glands ( er , 37 ± 45; pr , 43 ± 30 fmol/mg) than from the 2 caudal pairs ( er , 51 ± 50; pr , 62 ± 53 fmol/mg). A direct correlation was found for both receptor concentrations between normal tissue adjacent to and distant from the lesions and between normal tissue adjacent to the lesion and the corresponding tumor. In comparison with that in normal tissue, the general mechanism of modulation of receptor expression seems not to be modified in benign lesions and well differentiated malignant tumors. However, hormonal sensitivity is lost in dedifferentiated tumors.

The regulation of progesterone secretion and release by the corpus luteum and/or by the placenta in cats during pregnancy has been poorly studied and the relative roles of the corpus luteum and the placenta in the release of progesterone into the plasma is not well defined. It is generally assumed that after 40-45 days of pregnancy, circulating progesterone is mainly produced by the placenta and that after 45-50 days the corpus luteum is no longer necessary to maintain pregnancy, even if remnants of corpora lutea are detected in the ovaries during the following interoestrous period. In this study, the relative roles of the placenta and ovary in progesterone production after 30 days of pregnancy have been analysed in an attempt to define the role of progesterone in pregnant cats. Different experiments involved (1) analysis of the effects of an ovariectomy performed at 30 days of pregnancy, and of megestrol acetate supplementation on plasma progesterone during the second half of pregnancy, (2) analysis of the effects of an ovariectomy performed at 45 days on plasma progesterone production and on pregnancy and (3) analysis of the effects of an antiprolactin agent (cabergoline) at days 30 and 40 of pregnancy on progesterone secretion and pregnancy. These results were all compared with the normal plasma progesterone profiles during (a) pseudopregnancy and (b) pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)