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Biomedical subjects

E Milgrom

Publications and source records attributed to E Milgrom.

At least 163 records · Page 9Linked to original sources
PubMed1984

Absence of a direct inhibitory effect of the gonadotropin-releasing hormone (GnRH) agonist D-Ser (TBU)6, des-Gly-NH2(10) GnRH ethylamide (Buserelin) on testicular steroidogenesis in men.

The antigonadal effects of GnRH agonists (GnRH-A) are mediated both through pituitary and testicular inhibitory mechanisms in the rat. To investigate these effects in men, we studied patients having no gonadotropin secretion and compared their testicular response to hCG in the absence or in the presence of GnRH-A. Thirteen patients with acquired pituitary hypogonadotropism had plasma testosterone levels below 1.5 ng/ml and no gonadotropin responses to acute GnRH administration (100 micrograms iv). Testicular responsiveness was evaluated using a single im injection of hCG (5000 IU im). Plasma levels of testosterone, dihydrotestosterone, androstenedione, 17-hydroxyprogesterone (17-OHP), and progesterone were determined before and 4, 12, 24, 48, and 72 h after hCG stimulation. The same protocol was also used in the same patients on day 4 of a 6-day course of treatment with the GnRH-A, D-Ser-(TBU)6, des-Gly NH2 GnRH ethylamide (Buserelin) (3 sc injections of 250 micrograms/day). During the first 4 days of GnRH-A administration, plasma LH, FSH, and testosterone levels were measured daily in order to establish the completeness of the gonadotropin deficiency. Before treatment with hCG, plasma testosterone levels were 0.56 +/- 0.15 and 0.96 +/- 0.22 ng/ml (mean +/- SE) in the absence of GnRH-A and during GnRH-A administration, respectively. The administration of hCG elicited a significant increase in plasma testosterone in both situations; integrated testosterone concentrations were 123.7 +/- 24.9 and 155.5 +/- 27.9 ng/ml . 72 h (P greater than 0.1) in the absence of GnRH-A and during GnRH-A administration, respectively. Likewise the ratios of 17-OHP to progesterone, androstenedione to 17-OHP, and dihydrotestosterone to testosterone after hCG injection were similar in the presence or absence of GnRH-A. Since short term administration of buserelin did not inhibit hCG-induced testosterone secretion in patients with gonadotropin deficiency, we suggest that Buserelin does not grossly modify the function of testicular steroidogenesis enzymes. The antigonadal effects of GnRH-A in man appear to be mediated exclusively through the pituitary.

Buserelin↗
PubMed1983

The rabbit uteroglobin gene. Structure and interaction with the progesterone receptor.

The study of the regulation of uteroglobin gene in the rabbit endometrium constitutes a model for analyzing the mechanism of action of progesterone in mammals. The gene has been cloned into lambda phage and sequenced. Comparison of the sequence of the gene with the amino acid sequence of preuteroglobin and the three-dimensional structure of uteroglobin established by crystal x-ray diffraction showed that the 3 exons correspond to different functional domains of the protein and that at least one of the splice junctions does not map at the surface of the protein. S1 mapping allowed us to define the RNA polymerase initiation site. No difference was observed when analyzing premessengers from the endometrium, where the gene is controlled by progesterone and estradiol, and from lung where the gene is constitutively expressed and not controlled by these hormones. In addition, S1 mapping revealed the existence of several minor transcription initiation sites. In the 5' flanking region between positions -33 and -24 there is the sequence AATACAAAAA which may correspond to a Goldberg-Hogness box. Two other A- and T-rich sequences were found further upstream from the gene, one of these preceding by about 30 nucleotides a minor start of transcription. No obvious feature, possibly related to steroid regulation, was observed in the nucleotide sequence. A fragment of the gene containing the "promoter" region (from nucleotide +10 to nucleotide -394) was preferentially retained on nitrocellulose filters after incubation with purified rabbit uterine receptor. A competitive binding assay was used to compare the affinity for the receptor of various DNA fragments. Labeled "promoter" region DNA was incubated with receptor and various concentrations of nonlabeled competing DNA, and the nitrocellulose-bound radioactivity was measured. This method showed the existence of several high affinity binding sites in the 5' part of the gene and in adjacent regions. However, no high affinity binding sites were observed in the 3' part of the gene. Also, within the "promoter" region there were at least two high affinity binding sites for the receptor.

Amino Acid Sequence↗
PubMed1983

Monoclonal antibodies to rabbit progesterone receptor: crossreaction with other mammalian progesterone receptors.

A mouse was immunized with purified rabbit uterine cytosolic progesterone receptor (specific activity: 3 nmol of steroid bound per mg of protein). After fusion of its spleen cells with Sp2-OAg myeloma cells, supernatants of 11 hybrid cultures were found to react in both an immunoenzymatic test and a double-immunoprecipitation test with the progesterone receptor. Clones were obtained from the five hybrid cells that gave the strongest response in both tests. Antibodies from cell culture supernatants and ascitic fluids were characterized. Three are of the IgG1 and two of the IgG2a isotype. Their apparent affinity for the progesterone receptor was measured by immunoprecipitation in physiological salt conditions. The equilibrium dissociation constants were between 0.1 and 4 nM. All five monoclonal antibodies crossreacted with the rabbit nuclear receptor, the human cytosolic receptor, and other mammalian (rat, guinea pig) but not avian (chicken) cytosolic progesterone receptors. There was no interaction with the glucocorticoid receptor and corticosteroid binding globulin.

Animals↗
PubMed1983

Uteroglobin: a model for the sutyd of progesterone action in mammals.

Uteroglobin, a progesterone-binding protein, is expressed in several organs, principally endometrium and lung, of the rabbit and other rodents. The phasic activation of the uteroglobin gene in the endometrium during early pregnancy is regulated by progesterone, which contrasts with the constitutive, nonregulated expression of this gene in the lung. Thus, uteroglobin provides a useful model for the study of differential gene regulation by hormones as well as for the study of steroid-protein interactions.

Aging↗
PubMed1983

[Quality control of the assay of receptors in human breast tumors].

Many technical problems are encountered when measuring estradiol and progesterone receptors in breast tumors biopsies. They are due to both intrinsic characteristics of the tissue, and to receptors instability. Suggestions are made to establish an internal quality control in each laboratory at the different steps: obtention and storage of biopsies, purity checking of the reagents, control of the assay protocol, and calculations. Several methods to prepare control pools have been proposed. They use either mammary tumors or animal target organs, and stable concentrations of receptors have been obtained by storage in liquid nitrogen or lyophilization. Published studies have demonstrated important interlaboratory variations. These discrepancies might be in part reduced by using the same assay protocol in the different participating laboratories.

Breast Neoplasms↗
PubMed1982

Estradiol and progesterone receptors content and response to norethisterone treatment in advanced breast cancer.

Twenty-six patients with advanced breast cancer and progressive disease were treated by norethisterone. Estradiol and progesterone receptors were measured before starting treatment, and in three cases after 2 to 4.75 months of therapy. Partial remissions (greater than 50% decrease of all lesions) or objective improvements (decrease of 20-50%) were obtained in 7 patients, with a mean duration of 6.7 months. Stabilization of the lesions (no change or decrease of less than 20% in the size of the target lesion) was observed in 7 patients. No clear-cut correlation was found between clinical response and presence in biopsies of estradiol and progesterone receptors. However, absence of response occurred more frequently if tumors did not contain progesterone receptors.

Adult↗
PubMed1981

Cloning of rabbit genomic fragments containing the uteroglobin gene.

Hybrid phages containing the uteroglobin gene were isolated from a library of Charon 4A lambda phages carrying fragments of rabbit genome. Two phages which contain overlapping rabbit DNA covering approximately 35 kilobase pairs (kb) on both sides of the uteroglobin gene have been analyzed. One of the phages contains the complete gene. Digestion of rabbit liver DNA by restriction endonucleases and Southern hybridization showed a pattern identical with that obtained with the DNA of recombinant phages suggesting that no rearrangement has taken place during cloning. These experiments also showed the presence of a single gene for uteroglobin in the rabbit genome. Isolation of this gene is of interest for the study of the mechanism of action of progesterone.

Animals↗
PubMed1981

Antibodies to rabbit progesterone receptor: crossreaction with human receptor.

Progesterone receptor from rabbit uterine cytosol was purified to a specific activity of approximately 2 nmol of bound hormone per mg of protein. A goat was immunized with this preparation and, after two injections of 0.7-0.8 nmol, yielded antireceptor antibodies. The antiserum reacted with both cytosolic and nuclear rabbit progesterone receptor and also with progesterone receptor from other rabbit tissues (vagina and pituitary). A crossreaction was observed with progesterone receptors from other mammalian, especially human, tissues (cytosolic receptor from rat and guinea pig uterus, cytosolic receptor from human breast cancer, and nuclear receptor from human endometrium). On the contrary, there was no interaction with a nonmammalian receptor (chicken oviduct progesterone receptor). The antibodies did not crossreact with other rabbit steroid receptors (uterine estradiol receptor and liver glucocorticoid receptor) or with nonreceptor progesterone-binding proteins (transcortin from plasma and uteroglobin from uterine fluid).

Animals↗
PubMed1981

Inhibin-like activity and steroid content in human follicular fluid during the periovulatory period.

Inhibin-like activity as well as estradiol-17 beta and progesterone content were assayed in human follicular fluid obtained at different stages of the periovulatory period. Between the start of the midcycle estrogen surge in plasma and the subsequent gonadotrophin peak, follicular fluid was found to contain similar levels of estradiol-17 beta and progesterone (8.2 pmol/microliter) and to induce a marked (44%) inhibition of gonadotrophin-releasing hormone-stimulated release of FSH. The midcycle gonadotrophin peak was characterized by a drop in estradiol-17 beta levels and a tripling in progesterone levels, whereas inhibin-like activity fell to almost half the previous value.

Adult↗
PubMed1981

Thyroid hormone receptors in human breast cancer.

Optimum conditions were established for preparation of nuclei from human breast cancer biopsies. Incubation of nuclei with various concentrations of L-3,3',5-[125I]triiodothyronine showed the presence of three binding systems: a high-affinity binding system (type I) (KD approximately 0.5 micro M); an intermediate-affinity saturable system (type II) (Kd approximately 0.5 micro M)p and a nonsaturable nonspecific system. Salt at high concentrations (0.4 M-KCl) extracted only type I triiodothyronine-binding protein, thus simplifying its study and quantification. Type I binding protein was shown to have the affinity for triiodothyronine and the hormonal specificity usually ascribed to thyroid hormone receptors. Its sedimentation coefficient was 3.6S at 0.4 M KCl. Extractable triiodothyronine receptors was measured in 58 individual biopsies of primary and metastatic breast cancer. It was present in all tumors, but its concentration was highly variable (average, 0.20 pmol/mg DNA; range 0.044 to 0.702). Triiodothyronine receptor concentration was not correlated with age or endocrine status of the patient or with extension or histological grading of the tumor. Moreover, there was no correlation with estradiol and progesterone receptor concentration.

Adult↗