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G Hennen

Publications and source records attributed to G Hennen.

At least 73 records · Page 4Linked to original sources
PubMed1990

Regulation of growth hormone secretion in human trophoblastic cells in culture.

In this study, we have cultured in vitro purified trophoblastic cells from first-trimester and term human placenta. These cells were obtained by specific enzymatic digestion and centrifugation through a Percoll gradient. Using 2 specific monoclonal antibodies, the pituitary 22-kD growth hormone (GH) and the placental GH variant were assayed in the culture medium by radioimmunoassay. After 48 h of culture, only the placental GH variant was measured in the medium corresponding to first-trimester placenta (3.4 ng/24 h/10(5) cells). Surprisingly, an immunoactivity pattern of pituitary GH type was found in 3 out of 5 media conditioned with term placenta cells, while GH immunoactivity was very low, around the detection level, in the 2 others. These secretions are not modified with the time in culture and the state of differentiation of the cells from cytotrophoblast to syncytiotrophoblast. Neither in early nor in term placenta does the addition of GH-releasing factor (10(-6) M in the culture medium) stimulate the secretion of pituitary 22-kD GH or placental GH variant.

Cells, Cultured↗
PubMed1990

Identification of placental human growth hormone as the growth hormone-V gene expression product.

A GH variant of placental origin, placental GH, has recently been shown to replace pituitary GH in maternal serum during pregnancy. Besides, the GH variant (GH-V) gene has been demonstrated to be expressed in the placenta. The similarities between their known properties strongly suggest that the placental GH and the GH-V protein are the same molecular species. Here we provide final evidence that this is indeed the case by sequence analysis of both the 22K and 25K forms. Furthermore, the 25K form is shown to be glycosylated, while the 22K form is not. Both size variants of placental GH are, thus, likely to reflect the partial glycosylation of a unique peptidic chain.

Amino Acid Sequence↗
PubMed1990

Perinatal growth hormone (GH) physiology: effect of GH-releasing factor on maternal and fetal secretion of pituitary and placental GH.

To study regulation of the secretion of human pituitary GH (hGH) and placental GH (hPGH) in the pregnant woman and human fetus, the GH-releasing factor Sermorelin [GRF-(1-29)-NH2] was administered to pregnant women at term (n = 5), just before elective cesarean section; saline was administered in control studies (n = 5). The effects of GRF-(1-29)-NH2 administration on maternal and fetal serum concentrations of hGH and GRF-(1-29)-NH2 and maternal serum levels of hPGH were evaluated at birth. The mean time span between injection and birth was 20 min (range, 15-25 min). Cord serum hGH concentrations were similar in infants of GRF-(1-29)-NH2-injected mothers and control infants. GRF-(1-29)-NH2 elicited a consistent but small rise in maternal hGH serum concentrations (P = 0.08), whereas hPGH concentrations remained unaltered. Finally, GRF-(1-29)-NH2 concentrations were undetectable in cord serum, but readily detectable in concomitantly obtained maternal serum. In conclusion, these data suggest that hGH secretion in the pregnant woman at term is suppressed at the pituitary level, that GRF does not affect hPGH secretion, and that fetal hGH secretion is independent of circulating maternal GRF, probably because of lack of transplacental GRF passage.

Cesarean Section↗
PubMed1990

Placental and pituitary growth hormone secretion during pregnancy in acromegalic women.

It is now well established that during the second half of normal pregnancy, the human placenta secretes its specific GH variant (placental GH) in increasing amounts up to delivery. During the same period, pituitary GH secretion is progressively suppressed. The present study was aimed at clarifying the physiology of GH secretion in pregnant acromegalic women. Two young women remained acromegalic despite transphenoidal removal of their pituitary adenoma. Increased basal levels of GH and insulin-like growth factor-I (IGF-I) as well as paradoxical GH release after TRH injection were noted. Both women became pregnant and delivered term babies without any complication. In both patients, pituitary GH remained elevated during the entire pregnancy, contrary to the situation in normal women. Paradoxical GH release after TRH treatment was also present, whereas no response was observed in five normal control subjects. GH pulsatility studies revealed a highly pulsatile secretory pattern of pituitary GH, in contrast to that in normal woman, whose placental GH is secreted tonically. Tissue placental GH concentrations were within the range of levels in normal placentas. An increase in serum IGF-I in late pregnancy was also similar to that observed in normal pregnancy. These findings confirm that increased IGF-I levels are not pituitary GH dependent in late pregnancy. They add new evidence that adenomatous somatotrophs lack an IGF-I-dependent feedback regulation present in normal somatotrophs.

Acromegaly↗
PubMed1989

Growth hormone 24-h serum profiles during pregnancy--lack of pulsatility for the secretion of the placental variant.

Serum profiles of growth hormone (GH) were recorded for 24 h in women at different stages of normal pregnancy. Two monoclonal antibodies directed against different epitopes and unaffected by human placental lactogen were used in radioimmunoassays to distinguish the pituitary 22K-GH from the placental GH variant. The 'normal' episodic peak activity of GH in non-pregnant and first trimester pregnant women was dramatically changed into a continuous very stable secretion during late pregnancy. This change was first observed at 17 weeks gestation. It is concluded that during the second half of pregnancy, serum measurements of GH reflect a major contribution from a non-episodically secreted placental GH variant and a concomitant suppression of pituitary GH. This specific signal, i.e. a continuous GH secretion, may be an important regulator of maternal liver metabolism during pregnancy.

Female↗
PubMed1989

Immunocytochemical localization of the human growth hormone variant in the human placenta.

Two monoclonal antibodies (Mab 5B4 and K24) were used for the immunocytochemical localization of human GH (hGH) and human placental GH in the human pituitary and placenta. On the basis of prior selection by RIA, Mab 5B4 was known to be directed to the N-terminal of hGH and was able to detect both pituitary and placental hGH, since their primary amino acid sequences are identical in this domain. Mab K24 was directed to an epitope present in hGH, but not in placental hGH, and was able to detect pituitary hGH only; neither the 5B4 or K24 Mab detected human placental lactogen. Five placentas were studied from women at term after elective cesarean section without labor. The cells of the anterior pituitary gland and the syncytiotrophoblast of the placental villi were stained with Mab 5B4, whereas K24 only stained the pituitary cells; results consistent with the RIA screen. Mab 5B4 specifically stained two different cell types in the placental basal plate. Neither antiserum stained any cell in the amniotic or chorionic membranes or the adherent decidua. The results demonstrate that pituitary hGH and placental hGH are expressed uniquely in the pituitary and fetal placenta, respectively. In addition, the placental hGH gene is also expressed in the placental basal plate, a region of mixed fetal and maternal cells.

Antibodies, Monoclonal↗
PubMed1989

Pituitary hormones dependent expression of insulin-like growth factors I and II in the immature hypophysectomized rat testis.

Since insulin-like growth factors I (IGF-I) and II (IGF-II) appeared involved in paracrine or autocrine regulation of both cell multiplication and differentiation of the rat testis, we have investigated the pituitary hormonal dependence of IGF-I and IGF-II mRNA production in the testis of immature hypophysectomized rats (22 days old) supplemented with highly purified FSH, LH, GH or PRL. Our data show that testicular expression of IGF-I mRNA as measured by dot-blot hybridization, is increased by LH, FSH or GH treatments of 7-, 6-, and 4-fold, respectively, above controls. Intensity of the signal was 3-fold lower after PRL treatment than in hypophysectomized control rats. On the contrary, IGF-II mRNA expression, was found low in the immature hypophysectomized rat testis and unmodified by any hormonal treatment. In contrast to the increase of IGF-I expression in the testis no significant change in the IGF-I plasma concentration was observed after LH or FSH supplementation. GH treatment, as expected, increased 4-fold the IGF-I plasma concentration of the experimental animals. Since we have previously shown that LH, FSH, and GH exhibit selective cell multiplication and differentiation in the testis of our animal model, it is proposed that testicular IGF-I expression could be the tissue response to pituitary hormone in these phenomena.

Animals↗
PubMed1989

Biopotency of highly purified porcine FSH and human LH on gonadal function.

The gonadotrophin preparations that have been used previously to study different aspects of testis function are of limited purity. We have, therefore, purified existing gonadotrophin preparations further. The demonstration of their purity and biological activity are reported as well as their suitability for in-vivo use. After separation of the subunits of the intact hormones by high-performance liquid chromatography followed by analytical sodium dodecylsulphate-polyacrylamide gel electrophoresis, no contaminating proteins could be detected in either the FSH or LH preparation. After immunoadsorption, contamination by other pituitary hormones (TSH, prolactin, FSH, LH and GH) was found to be less than 0.002% by weight for all the hormones tested. The biological activity of porcine FSH (pFSH) measured in a Steelman-Pohley assay was 150-170 times more potent than the NIH-FSH-P1 reference preparation. The biopotency of human LH (hLH) in the ovarian ascorbic acid depletion test was measured and appeared to be 8100-8300 IU/mg against the 68/40 International Standard. The dose-dependent effects of pFSH and hLH on testis weight and the number of FSH and LH receptors were measured in immature (22-day-old) hypophysectomized rats treated for 7 consecutive days. Treatment with FSH induced a dose-dependent increase in testis weight (threefold) when compared with the control. The concentration and total number of LH receptors were increased (two- to sixfold) in a dose-dependent manner. The number of FSH receptors per testis increased while the number of FSH receptors per mg of protein remained unchanged. Administration of human LH to immature hypophysectomized rats had no effect on either LH or FSH receptors, regardless of the dose administered.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effects of pure FSH and LH preparations on the number and function of Leydig cells in immature hypophysectomized rats.

The effects of pure FSH and/or LH preparations on the number of Leydig cells and their function in immature hypophysectomized rats have been investigated. As a result of hypophysectomy at the age of 17-18 days, the number of recognizable Leydig cells per testis decreased, as did the steroidogenic capacity in vivo and in vitro. Treatment with 64 micrograms FSH on both 22 and 23 days of age, did not affect the number of recognizable Leydig cells. In contrast, two injections of LH (10 micrograms) caused a sixfold increase in the number of Leydig cells, but had a negative effect on spermatogenesis. These stimulatory and inhibitory effects of LH diminished when FSH was added. Treatment with FSH for 7 days caused a twofold increase in the number of Leydig cells when compared with hypophysectomized controls. 3 beta-Hydroxysteroid dehydrogenase (3 beta-HSD) and esterase activity in Leydig cells also increased under the influence of FSH. The pregnenolone production per Leydig cell in the presence of 5-cholesten-3 beta,22(R)-diol (22R-hydroxycholesterol) as substrate showed a sevenfold increase. Plasma testosterone levels 2 h after injection of human chorionic gonadotrophin in intact rats and hypophysectomized FSH-treated rats were the same. Following LH treatment for 7 days, the number of Leydig cells proved to be 11 times higher, and 3 beta-HSD and esterase activity were not different from intact controls. The testicular pregnenolone production was four- to fivefold higher when compared with untreated hypophysectomized rats. However, pregnenolone production per Leydig cell in LH-treated rats was only slightly different from the hypophysectomized controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

A non-radioactive method to detect RNA or DNA using an oligonucleotide probe with bromodeoxyuridine free ends, a monoclonal antibody against bromodeoxyuridine and immunogold silver staining.

A non radioactive method for probing RNA or DNA on dot and Northern blots using a synthetic oligonucleotide with bromodeoxyuridine free ends is described. The present experiment was carried out with human testis and placental RNA's. The probe was the 21 base long sequence coding for the amino acids 18 to 24 of the insulin-like growth factor I (IGF-I) with two bromodeoxyuridine dinucleotides added at the 5' and 3' ends. The probe was detected with a monoclonal antibody against bromodeoxyuridine and immunogold silver staining (IGSS). Our method was compared to the peroxydase (HRP) revelation of the same probe. The results obtained show a lower background with IGSS than with HRP revelation. A sensitivity similar to that of 32P labelling was found with the advantages of an increase in the rapidity of the procedure (24 hours instead of 9 days exposure) and the absence of handling radioactive substances. Moreover, as the monoclonal antibody against BrdU detects single stranded DNA only, the use of BrdU free ends-labelled oligonucleotide allows the development of the revelation procedure without any previous denaturation of the hybrid. This particular point is an indisputable advantage for detecting hybridization in situ.

Antibodies, Monoclonal↗
PubMed1989

[Endocrine, paracrine and autocrine factors in the maturation and functional development of the testis].

We have studied the specific effects of highly purified pituitary hormones on testicular cell multiplication and differentiation in the immature hypophysectomized rat. LH exhibits multiplicative effects on Leydig cells and, curiously, regressive effects on germ cells. Seminiferous tubules are the main site of action of FSH which induces direct differentiation of Sertoli cells and paracrine effects on germ cells resulting in their multiplication to the pachytene stage (in the absence of androgen). Through interstitium-directed paracrine effects, FSH promotes the differentiation of Leydig cells. Prolactin and lactogenic growth hormones are capable of exerting both differentiative and multiplicative effects on Leydig cells. The purity of the hormone preparations permit to define their specific and direct effects and those mediated by paracrine or autocrine factors synthetized locally under their control. Among these potential factors, we have demonstrated the pituitary-dependent expression of IGF-I, c-myc, c-fos proteins. The purity of the preparations used in this work permits to distinguish clearly the specific and direct effect of each pituitary hormone from those mediated by paracrine or autocrine factors.

Animals↗
PubMed1988

Detection of cell proliferation in pig testis and intestine sections using monoclonal anti-bromodeoxyuridine antibody and immunogold silver staining.

For the first time a monoclonal antibody against 5-bromodeoxyuridine was used to detect cell proliferation in pig testis and intestine sections. The influence of several parameters such as mode of injection, addition of thymidine biosynthesis inhibitor, tissue fixation, hydrolysis and revelation was examined. The technique of choice consisted in intravenously injecting the animals with 50 mg/kg BUdR added to 10 mg/kg FUdR 2 h before tissue collection and Bouin fixation; hydrolysis of sections was performed by HC1 4N: Ethanol 70 degrees (1:1 v/v); revelation of BUdR was made by a secondary antibody linked to colloidal gold particles, followed by a silver enhancement step. The data were superior when compared to those obtained by direct immunofluorescence and by the PAP technique. The described method is convenient and sensitive, provides an intense nuclear labelling without background and allows simultaneous examination of histology. The advantages over the technique using tritiated thymidine are particularly obvious when fast screening of numerous samples is required or when new experimental protocols are developing.

Animals↗
PubMed1988

The physiology of growth hormones (GHs) in pregnant women and partial characterization of the placental GH variant.

This work was undertaken to study the heterogeneity of GH in serum and placental and pituitary extracts and to study GH physiology in pregnant women. Two distinct monoclonal antihuman GH (anti-hGH) antibodies (MAb) coded 5B4 and K24 were selected for their high binding affinity and specificity. The 5B4 MAb recognized the epitope comprising the NH2-terminal end of hGH, and the K24 MAb recognized an internal epitope. Both MAbs were used in RIAs to measure serum GH concentrations in various circumstances, including pregnancy. The two RIAs yielded slightly different serum GH results in normal men and nonpregnant women, but the overall correlation between the data was excellent. Since the RIAs were not affected by human placental lactogen, the evolution of serum GH in pregnant women could be studied. In such women, serum GH levels progressively declined to undetectable levels during the second half of pregnancy, while a pregnancy-associated serum GH-like antigen [tentatively called human placental growth hormone (PGH)] appeared in the circulation at midpregnancy and increased thereafter up to term. PGH contained the NH2-terminal epitope of pituitary GH, but lacked the internal one. Consequently, it reacted selectively with the 5B4 MAb only. After delivery, PGH disappeared from maternal serum within 1 h. Amniotic fluid contained low GH concentrations; cord serum contained high GH levels, but no PGH. Thus, PGH appears to be secreted selectively into the maternal compartment. PGH was purified from term placenta extracts. According to its chromatographic behavior, it appears more basic than pituitary 22K and 20K GHs. Size dimorphism was demonstrated; PGH was composed of two entities of 22K and 25K, respectively. Pure PGH, obtained in small quantities by preparative electrophoresis, was found to bind to hepatic GH receptor with an apparent high potency compared to that of pituitary GH, PGH, thus, should act in vivo as a GH agonist sharing most of its biological properties. These results lead to the conclusion that PGH is likely to replace the pituitary hormone in governing maternal metabolism during the second half of pregnancy.

Amniotic Fluid↗
PubMed1988

Mammosomatotropes in human pituitary adenomas as revealed by electron microscopic double gold immunostaining method.

Hormone production was studied in situ by immunocytochemical methods in 20 pituitary adenomas. Special attention was given to 13 adenomas removed from acromegalic patients. Out of them, 6 had mild to moderate hyperprolactinemia. Immunohistochemistry revealed PRL-containing cells without any close relationship with high PRL serum level in 6 patients. Double immunogold staining revealed mammosomatotrope cells characterized by simultaneous presence of GH and PRL in the same granules in 2 patients. Since mammosomatotropes have never been demonstrated in the normal pituitary, our results probably signify gene dysregulation in pituitary cells of those acromegalic patients.

Adenoma↗
PubMed1988

Growth hormone secretion during termination of pregnancy. Further evidence of a placental variant.

Serum profiles of growth hormone (GH), hPL and hCG were recorded in 5 pregnant women during termination of pregnancy at cesarean section and legal abortion. Two monoclonal antibodies directed against different epitopes on the GH molecule were used to distinguish the pituitary 22K-GH from the placental GH variant. After placental removal at cesarean section, a rapid fall in GH as well as in hPL and hCG concentrations was recorded. On the other hand GH levels were unaffected when early pregnancy was terminated by legal abortion. The importance of an intact placental function for the maintenance of high GH levels lends further support to the concept that a placental GH variant is produced during late pregnancy.

Abortion, Induced↗