Biomedical subjects

J F Strauss

Publications and source records attributed to J F Strauss.

At least 163 records · Page 9Linked to original sources

PubMed1988

Human adrenodoxin: cloning of three cDNAs and cycloheximide enhancement in JEG-3 cells.

Adrenodoxin is an iron-sulfur protein serving as an electron transport intermediate for two mitochondrial steroidogenic cytochromes P450. We have cloned and sequenced three human adrenal adrenodoxin cDNAs. The longest 5'-untranslated region was 131 bases long, and the coding sequences, identical in all three clones, predict a preprotein of 180 amino acids. The 3'-untranslated regions were 235, 596, and 776 bases long due to the presence of alternate polyadenylation sites. RNA transfer blots showed multiple size species of adrenodoxin mRNA consistent with finding multiple polyadenylation sites. Similar sized cross-hybridizing RNA species are found abundantly in the adrenal and testis and to a lesser degree in RNA from human fetal brain, spleen, placenta, kidney, liver, and intestine, as well as in cultured fibroblasts, suggesting the same or a very similar iron-sulfur protein is found in mitochondria of nonsteroidogenic tissues. JEG-3 cells, a transformed progesterone-producing line of trophoblastic origin, accumulate mRNAs for cytochrome P450scc (the mitochondrial cholesterol side-chain cleavage enzyme), adrenodoxin, and the fos oncogene when stimulated with 8-bromo-cyclic AMP. Addition of actinomycin D to such cultures blocked cAMP-induced accumulation of mRNAs for cytochrome P450scc and adrenodoxin. Addition of cycloheximide or puromycin to such cultures substantially reduced basal levels and markedly attenuated the cAMP-induced accumulation of cytochrome P450scc mRNA, but augmented the accumulation of adrenodoxin and fos mRNAs in additive and multiplicative fashions, respectively. These data indicate that the cAMP-induced synthesis of the steroidogenic machinery is not wholly dependent on cycloheximide-sensitive protein mediators.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1988

The human villous cytotrophoblast: interactions with extracellular matrix proteins, endocrine function, and cytoplasmic differentiation in the absence of syncytium formation.

Human syncytiotrophoblasts are derived from villous cytotrophoblasts by cell fusion. Coincident with this morphologic transformation, trophoblasts acquire specific endocrine functions, including elaboration of chorionic gonadotropin (hCG). We wondered if syncytia formation was a prerequisite for biochemical differentiation or simply was one part of the differentiation program. By growing purified human cytotrophoblasts under serum-free conditions and manipulating the culture surface, we were able to disassociate morphologic from biochemical differentiation. We have shown previously (Endocrinology 1986, 118:1567) that human cytotrophoblasts grown in the presence of fetal calf serum flatten out, aggregate, and form functional syncytiotrophoblasts in vitro over 24-96 hr. Here we demonstrate that when grown in the absence of serum, the cells do not undergo these morphologic changes, but remain as individual spherical cells. If the culture surface was precoated with fibronectin or a variety of collagens, but not albumin, the cells regained their ability to flatten, aggregate, and form syncytia. Attachment to and syncytia formation on fibronectin was blocked by the addition of the R-G-D-S-containing peptide, Gly-Arg-Gly-Asp-Ser-Pro. Attachment to and syncytia formation on type I collagen was blocked by anti-human fibronectin F(ab')2 fragments, while association with type IV collagen was not affected by this antibody, suggesting that fibronectin mediates trophoblast association with type I collagen, but not type IV. Although syncytia formation did not occur when cytotrophoblasts were cultured under serum-free conditions in the absence of ECM proteins, biochemical differentiation was not affected. These cells secreted hCG at the same rate under serum-free conditions whether they were plated on plastic only--which prevented syncytia formation--or fibronectin, laminin or, type IV collagen--which allowed syncytia formation to occur. Furthermore, cytoplasmic differentiation in the absence of syncytia formation was confirmed by performing transmission electron microscopy on cytotrophoblasts grown under serum-free conditions in the presence of 8-bromo-cAMP. We conclude that syncytia formation is not a prerequisite for biochemical differentiation, but simply part of the trophoblast differentiation program.

Cell Adhesion↗

PubMed1988

Control of bovine placental progestin synthesis: calcium dependent steroidogenesis is modulated at the site of the cholesterol side chain cleavage enzyme.

We have previously reported that progesterone synthesis in the bovine placenta is regulated by Ca2+ dependent and cyclic nucleotide independent mechanism. In studies conducted to further define the role of Ca2+ in the synthesis of progestins in bovine placental tissue, it was found that both protein kinase C (PKC), as determined by phosphorylation, and cytochrome P-450 side chain cleavage, as determined by Western blot analysis, were detectable in the steroidogenetically active portion of the placentome. To determine the site of action of PKC, fetal cotyledon cells were incubated in media containing 25-hydroxycholesterol in the absence or or presence of 10 ng/ml 12-O-tetradecanoyl-phorbol-13-acetate (TPA). It was found that TPA significantly (P less than 0.05) increased the conversion of the exogenous cholesterol analog to progesterone. To determine if the TPA could act synergistically with calcium activators, fetal cotyledon cells were incubated with either methyl isobutyl xanthine (MIX), an activator of intracellular calcium, or the calcium ionophore, A23187, which increases extracellular calcium influx, or both of these agents, in the presence or absence of TPA. It was found that TPA synergistically increased the conversion of sterol to progestins induced by submaximal concentrations of either MIX or A23187. In the presence of both compounds, TPA induced an even more dramatic increase in progestin synthesis. In experiments in which cyanoketone, an agent that inhibits the conversion of pregnenolone to progesterone, was added, TPA addition resulted in increased pregnenolone production, indicating that side chain cleavage of cholesterol is the site of action. The data, therefore, suggest that: (a) Ca2+ affects mechanisms regulating placental steroidogenesis; (2) one locus of Ca2+ is the cholesterol side chain cleavage reaction; and (3) PKC found in this tissue has a role in the Ca activated progestin production.

1-Methyl-3-isobutylxanthine↗

PubMed1988

Control of bovine placental progesterone synthesis: roles of cholesterol availability and calcium-activated systems.

It was previously reported that dispersed bovine placentome secretes progesterone and that the steroidogenic activity of these cells is stimulated by a calcium-mediated, cyclic nucleotide independent mechanism. In the present study, the influence of substrate availability was explored and the roles of calmodulin and protein kinase C in progestin production examined. Incubation of dispersed fetal cotyledon cells with 25-hydroxycholesterol (25-OH-C), a soluble sterol which readily enters cells and is metabolized to steroid hormones, increased progesterone secretion in a dose-dependent manner. The response to 25-OH-C was dependent on the extracellular calcium concentration. Methyl isobutyl xanthine (MIX) alone also increased pregnenolone as well as progesterone secretion, and the combination of 25-OH-C and MIX stimulated progesterone secretion was inhibited by trifluoperazine. The phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), caused no major effects on steroidogenesis but the stimulatory effects of MIX or the ionophore A23187 were enhanced in its presence. These findings suggest that (1) basal progesterone secretion by fetal cotyledon cells is limited by cholesterol availability; (2) MIX increases steroidogenesis in part by increasing the synthesis of pregnenolone, but its actions are expressed independently of cholesterol availability; (3) both calmodulin and protein kinase C may participate in the modulation of bovine placental steroidogenesis.

1-Methyl-3-isobutylxanthine↗

PubMed1988

Adenylate cyclase in human cytotrophoblasts: characterization and its role in modulating human chorionic gonadotropin secretion.

Our previous work demonstrated that 8-bromo-cAMP promotes the secretion of both hCG and progesterone by cultured cytotrophoblasts. This study was conducted to characterize the adenylate cyclase of cytotrophoblasts and to examine the effects of agents that stimulate adenylate cyclase on hCG secretion. Adenylate cyclase activity was detected in purified cytotrophoblasts, as were membrane-bound stimulatory and inhibitory guanine nucleotide regulatory proteins, Gs and Gi. Adenylate cyclase was stimulated by MnCl2 and MgCl2, and the effects of MgCl2 were amplified by the GTP analog guanylylimidodiphosphate. Cholera toxin stimulated both cAMP and hCG production by cultured cytotrophoblasts, confirming the coupling of Gs to the adenylate cyclase. Forskolin also stimulated adenylate cyclase, cAMP synthesis, and hCG secretion. Pertussis toxin did not affect hCG secretion in either the absence or presence of forskolin. 8-Bromo-cAMP stimulated cytotrophoblast protein kinase activity, resulting in the increased phosphorylation of a protein with a mol wt of about 70,000, and produced a marked stimulation of hCG secretion. Our findings suggest that the level of expression of adenylate cyclase activity is one determinant of the endocrine function of the differentiating trophoblast.

1-Methyl-3-isobutylxanthine↗

PubMed1988

Involvement of cyclic AMP in the functions of granulosa and luteal cells: regulation of steroidogenesis.

The findings reviewed above demonstrate that cAMP can act at several distinct loci to enhance steroidogenesis. Analogs of cAMP stimulate the accumulation of the mRNAs which encode components of the steroidogenic machinery, such as the receptor for LDL and the system for the cleavage of the cholesterol sidechain. This apparently coordinated accumulation of specific mRNAs results from increased transcription of the relevant genes. Transacting factors modulated by cyclic AMP may influence common enhancer sequences (e.g., TGACGTCA), and such interactions would account for the simultaneous increase in expression of specific genes on several different chromosomes. These actions of cyclic AMP enable ovarian cells to support long-term increases in steroid synthesis by increasing the quantities of proteins involved in steroidogenesis. Such changes would obviously be important during luteinization, when the potential of granulosa cells to secrete progesterone is greatly increased. Although we speak of these effects as "long-term", it is evident that they occur within a relatively short time (hours) after exposure of cells to the tropic agent. Cyclic AMP also acts to stimulate steroidogenesis post-transcriptionally. It may influence events at the translational level via interactions in the formation of "labile" proteins. In addition, the regulation of cholesteryl ester hydrolase, as well as of other enzymes involved the metabolism of cholesterol, seems to involve post-translational modifications (e.g., phosphorylation). The effects of cAMP on the cytoskeleton may be another manifestation of a post-translational response. These actions of cAMP promote acute increases in steroidogenesis (i.e., within minutes). They encompass the transport of cholesterol to the mitochondria and the regulation of access of sterol to the inner mitochondrial membranes. Future research should be directed at elucidating the exact mechanisms which permit cAMP to exert coordinate effects on the genome (Figure 8), as well as its post-transcriptional effects on various proteins and enzymes which play a role in the synthesis of steroid hormones.

Animals↗

PubMed1988

Ovarian response of individuals to different doses of human menopausal gonadotropin.

Hormonal profiles were compared in 14 ovulatory women who were treated with two different doses of gonadotropins in successive in vitro fertilization cycles. All patients suffered from mechanical causes of infertility. Serum estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and progesterone (P) were measured daily during the follicular phase. Women were arbitrarily classified as high responders (E2 greater than 1000 pg/ml on the day of human chorionic gonadotropin administration, n = 8) or as low responders (E2 less than 1000 pg/ml, n = 6), according to the peak E2 levels during the cycle when they received 3 ampules of human menopausal gonadotropin (hMG). When patients were treated with 3 ampules of hMG, serum FSH, LH, and P concentrations increased significantly during the follicular phase in high responders but remained unchanged in low responders. When these patients were treated with 2 ampules of hMG, the temporal profiles of the hormones were similar, but the magnitude of increases in serum levels of gonadotropins and sex steroids was significantly reduced in high responders. The authors conclude that temporal individuality of endocrine profiles cannot be altered by varying the dose of gonadotropin. Increases in hormone levels accompanying a high response to hMG can, however, be dampened by lowering the dose. In contrast, hormone concentrations are not influenced by changing the dose of hMG in low responders.

Adult↗

PubMed1987

Regulation of urokinase-type plasminogen activator production by cultured human cytotrophoblasts.

Cultured human cytotrophoblasts synthesize and secrete urokinase-type plasminogen activator (uPA) during the first 24 h of culture, but secretion declines during the subsequent day. In contrast, synthesis and secretion of fibronectin increases during the 2 days of culture. The levels of uPA mRNA parallel the changes in synthesis and secretion of uPA. Treatment of cytotrophoblasts with 8-bromo-cAMP (1.5 mM) transiently raises uPA mRNA levels and uPA secretion. This treatment reduces fibronectin mRNA levels and causes a sustained increase in beta chorionic gonadotropin mRNA content and chorionic gonadotropin secretion. We conclude that a cAMP-mediated process up-regulates uPA expression in cytotrophoblasts. However, the stimulatory effect of the cyclic nucleotide analog on uPA is transient.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1987

Evaluation of the average of patients: application to endocrine assays.

Recent work (Cembrowski et al, Am J Clin Pathol 1984;81:492-499) has shown that the average of selected patient data can theoretically be used to demonstrate systematic errors. We formerly demonstrate that the sensitivity or power of the 'average of patients' (AOP) is related to the index (NpSw2)/Sp2 where Np is the number of patient results averaged, Sw the within-run component of the standard deviation of the analytical method and Sp the standard deviation of the trimmed population. The utility of the AOP can therefore be assessed rapidly without power function curves or the calculation of the daily AOP itself. The index showed that, for 12 radioimmunoassays done in our laboratory, the power of the AOP was greatest for T3 uptake, then FTI, then T4. Daily AOP were followed for these tests with control results on parallel Shewhart plots. We also applied an exponential smoothing procedure on the AOP and control results to improve trend detection. These analyses demonstrated that the AOP can improve the detection of systematic errors and the differentiation of true errors from errors affecting only control specimens.

Endocrine System Diseases↗

PubMed1987

Hepatic lipase. Synthesis, processing, and secretion by isolated rat hepatocytes.

Hepatic lipase, a glycoprotein synthesized and secreted by the hepatocyte, binds to sinusoidal endothelium where it is involved in metabolism of lipoprotein phospholipid and triglyceride. To better understand the regulation of hepatic lipase, we investigated the synthesis, post-translational processing, and secretion of the enzyme by isolated rat hepatocytes. Metabolically labeled [35S]methionine hepatic lipase protein, produced by the collagenase-dispersed hepatocytes, was immunoisolated from detergent-solubilized cells and incubation medium at designated times, using a polyclonal rabbit anti-rat hepatic lipase antibody raised against hepatic lipase purified to homogeneity from rat liver post-heparin perfusates. Following polyacrylamide gel electrophoresis and fluorography, radiolabeled hepatic lipase was quantitated by densitometry. Newly synthesized hepatic lipase was rapidly secreted and accumulated in the medium as a 59,000-dalton protein in a manner consistent with a constitutive process. An intracellular 53,000-dalton precursor of the mature 59,000-dalton hepatic lipase was identified by immunoprecipitation. The 53,000-dalton form could also be generated by endoglycosidase digestion of the secreted 59,000-dalton protein. In pulse-chase experiments, the 53,000-dalton protein was converted into the 59,000-dalton form. A 47,000-dalton form of hepatic lipase was immunoisolated from cell lysates only after tunicamycin treatment and could be generated from the secreted 59,000-dalton enzyme by prolonged endoglycosidase digestion. These data show that hepatic lipase is synthesized and rapidly secreted by isolated rat hepatocytes. Further, an intracellular 47,000-dalton precursor peptide can be identified after tunicamycin treatment, which may represent the hepatic lipase polypeptide, presumably after removal of its signal sequence; a 53,000-dalton partially glycosylated peptide exists as a major precursor form in the cell; and the mature 59,000-dalton hepatic lipase is present in the hepatocyte, but it is rapidly secreted.

Animals↗

PubMed1987

Regulation of low density lipoprotein receptor and cytochrome P-450scc mRNA levels in human granulosa cells.

hCG and 8-bromo-cAMP increase the levels of the mRNAs encoding the LDL receptor and cytochrome P-450scc in human granulosa cells. The increment in these mRNAs occurs rapidly after stimulation (within hours). Actin mRNA levels are not changed by hCG and 8-bromo-cAMP treatment. The tropic hormone effects on LDL receptor mRNA are observed even in the presence of 25-hydroxycholesterol and aminoglutethimide, which by themselves suppress LDL receptor mRNA. Actinomycin D blocks the hCG and 8-bromo-cAMP promoted augmentation of LDL receptor mRNA, suggesting that the tropic factors act to increase transcription of this gene. Treatment of cells with cycloheximide increases LDL receptor mRNA levels, and the stimulatory response to hCG and 8-bromo-cAMP is enhanced in the presence of cycloheximide. This indicates that tropic hormones act to increase LDL receptor mRNA levels without requiring synthesis of intermediary proteins and suggests that some short-lived protein may actually be reducing LDL receptors mRNA levels in these cells. We conclude that gonadotropins increase steroidogenesis in human granulosa cells, in part, by increasing expression of mRNAs encoding specific proteins involved in cholesterol metabolism.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1987

Relationships between polypronuclear fertilization and follicular fluid hormones in gonadotropin-treated women.

Similar incidences of congenital abnormalities in in vitro fertilization and embryo transfer (IVF-ET) pregnancies and births in the general population have not supported earlier concerns that IVF may increase chromosomal aberrations. Nevertheless, polypronuclear fertilization is a common, undesirable, and poorly understood outcome of IVF. We evaluated hormone levels in 20 follicular fluids that were associated with mature oocytes that have fertilized abnormally (greater than or equal to pronuclei) and compared them to follicles with mature oocytes that cleaved normally, fertilized but failed to cleave, or did not fertilize. Progesterone (P), androstenedione, estradiol, percent free estradiol, sex hormone-binding globulin, insulin, and prolactin were measured. P levels were significantly higher in follicular fluids associated with oocytes that fertilized abnormally than in the other groups. Levels of the other hormones were similar in all the study groups. We conclude that IVF of oocytes from highly luteinized follicles as judged by P levels may result in polypronuclear fertilization.

Body Fluids↗

PubMed1987

Human chorionic gonadotropin and 8-bromo cyclic adenosine monophosphate promote an acute increase in cytochrome P450scc and adrenodoxin messenger RNAs in cultured human granulosa cells by a cycloheximide-insensitive mechanism.

Treatment of human granulosa cells with human chorionic gonadotropin (hCG) or an analogue of its second messenger, cyclic AMP (cAMP), promotes a rapid accumulation of the messenger RNAs (mRNAs) for cytochrome P450 side-chain cleavage (scc) and adrenodoxin. A twofold increase in the cellular content of these mRNAs was observed within 4 h of exposure to 8-bromo-cAMP, and was maintained for up to 48 h. Inhibition of protein synthesis by cycloheximide did not prevent the hCG- or 8-bromo-cAMP-stimulated accumulation of either cytochrome P450scc or adrenodoxin mRNAs. We conclude that human granulosa cells respond rapidly to hCG and cAMP analogues with a coordinate increase in levels of the mRNAs encoding two key proteins of the steroidogenic machinery, and that this stimulation does not require synthesis of a protein intermediate.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1987

Detection of vitamin D binding protein on the surface of cytotrophoblasts isolated from human placentae.

Vitamin D binding protein (DBP), a Mr 56,000-58,000 alpha 2-glycoprotein, is the major serum protein involved in the transport of vitamin D sterols. Recently it has been suggested that DBP may also be involved in immunoglobulin G binding to cells. Because the trophoblast is involved in the transport of molecules such as vitamin D and immunoglobulin G to the fetus, we asked whether DBP could be detected on the surface of human placental trophoblast cells. Cytotrophoblasts purified from human term placentae were fixed and made permeant with Triton X-100 and examined by indirect immunofluorescence after incubation with a monoclonal antibody to DBP. Greater than 90% of these cells stained positively, whereas no staining was observed with nonimmune antiserum. The presence of DBP on/in the surface of cytotrophoblasts could also be demonstrated by fluorescent cytometry. When cell surface-associated proteins of cytotrophoblasts were radioiodinated, a Mr 57,000 radiolabeled protein could be immunoisolated from the cell lysate with a purified monospecific polyclonal antibody to DBP. Immunoisolation of this radiolabeled protein was prevented by the addition of excess unlabeled human DBP to the cell lysate before incubation with antibody. This Mr 57,000 radiolabeled protein could also be isolated by affinity chromatography selecting for proteins that bind to globular actin. When cytotrophoblasts were incubated with [35S]methionine for 3 or 18 h, active synthesis of DBP could not be demonstrated by immunoisolation techniques. These studies demonstrate the presence of DBP on the surface of well washed, human cytotrophoblasts. This DBP may be maternally derived, since active synthesis of DBP could not be demonstrated.

Actins↗

PubMed1987

The insulin-like growth factor, somatomedin-C, modulates low density lipoprotein metabolism by swine granulosa cells.

Insulin-like growth factor I (IGF-I) synergistically amplified the stimulatory effect of low density lipoprotein (LDL) on progesterone biosynthesis by primary cultures of swine ovarian cells. The mechanisms subserving this facilitative interaction included the following. IGF-I's synergism with LDL was associated with a decrease in the mean half-maximally stimulatory concentration of LDL from 20-3.5 micrograms/ml. IGF-I increased by 3- to 6-fold the number of specific high affinity LDL receptors on ovarian cells, with no change in apparent binding affinity. IGF-I augmented by 3- and 18-fold the maximal rates of [125I]iodo-LDL internalization and degradation, respectively, without altering half-maximally effective concentrations of LDL supporting these processes. IGF-I increased by 2- to 2.5-fold the total mass of free and esterified cholesterol contained in granulosa cells. IGF-I stimulated the intracellular accumulation of free [3H]cholesterol and [3H]cholesteryl ester from exogenous [3H]cholesteryl linoleate-labeled LDL, and amplified [3H]progesterone secretion by granulosa cells exposed to this source of lipoprotein-borne sterol. These actions of IGF-I were demonstrated at 30- to 100-fold lower concentrations of IGF-I than insulin. We conclude that IGF-I and LDL synergistically enhance progesterone biosynthesis by ovarian cells. This synergism occurs in part via mechanisms that regulate the effectual delivery of lipoprotein-borne cholesterol substrate into cellular sterol pools that participate in steroid hormone biosynthesis.

Animals↗

PubMed1987

The effects of hyperinsulinemia on serum testosterone, progesterone, dehydroepiandrosterone sulfate, and cortisol levels in normal women and in a woman with hyperandrogenism, insulin resistance, and acanthosis nigricans.

Insulin may mediate the hyperandrogenism that frequently occurs in patients with insulin-resistant states. To test this hypothesis, we studied five normal women and one woman with hyperandrogenism, insulin resistance, and acanthosis nigricans with the hyperinsulinemic-euglycemic clamp technique. Each woman received a 0.1 U/kg insulin bolus dose, followed by a 10 mU/kg X min insulin infusion for 12-16 h. In the normal women, an average insulin level of 1832 +/- 292 (+/- SEM) microU/ml was achieved; serum glucose was clamped at 116 +/- 5 mg/dl. At this level, insulin may bind to the insulin-like growth factor I receptor as well as to its own receptor. Contrary to our working hypothesis, a rise in serum testosterone did not occur in any women during insulin infusion, and in one women, serum testosterone levels decreased. When analyzed as a percentage of the basal value, serum progesterone levels fell 20% in the normal women within the first 2 h of insulin infusion, but did not change thereafter. Dehydroepiandrosterone sulfate (DHEA-S) levels, however, uniformly and progressively decreased by 39% after 12 h of insulin infusion in the normal women and by 31% at 14 h in the woman with hyperandrogenism, insulin resistance, and acanthosis nigricans. The fall in serum DHEA-S levels was not due to diurnal rhythmicity, as the changes in serum DHEA-S levels did not correlated with those in serum cortisol. Suppression of PRL release also was excluded as a cause of the fall in DHEA-S levels. These results indicate that acute hyperinsulinemia of 12- to 16-h duration does not increase serum testosterone or DHEA-S concentrations and, indeed, can cause a decline in serum DHEA-S levels in both normal women and the single woman studied with hyperandrogenism, insulin resistance, and acanthosis nigricans.

Acanthosis Nigricans↗

PubMed1987

Endometrial cytosolic and nuclear progesterone receptors in the luteal phase defect.

Basal body temperature profiles, serial serum progesterone levels, and serial endometrial biopsies were studied in 15 infertile women during 21 ovulatory cycles. Ten cycles (in 9 women) demonstrated luteal phase defects (LPD), diagnosed by a histological lag in endometrial maturation, normal luteal phase length, and normal luteal phase serum progesterone levels. Both normal and LPD cycles had a maximum amount of endometrial cytosolic progesterone receptor (PgR) on days 13-15, with a significant decline thereafter. LPD cycles had significantly lower endometrial nuclear PgR concentrations than did normal cycles during the proliferative phase, but luteal phase endometrial nuclear PgR levels were similar in both groups. In 2 LPD women treated with dydrogesterone, normal endometrial maturation and a decline in endometrial cytosolic PgR concentrations in the late luteal phase were found. Therefore, with the exception of endometrial nuclear PgR concentrations during the proliferative phase, we found no evidence for a major abnormality in endometrial PgR levels in LPD cycles with a lag in endometrial histology.

Adult↗

PubMed1987

8-Bromo-adenosine 3',5'-monophosphate regulates expression of chorionic gonadotropin and fibronectin in human cytotrophoblasts.

Addition of 8-bromo-cAMP to primary cultures of human placental cytotrophoblasts results in significant alterations in the synthesis of secreted proteins, as detected by labeling with pulses of [35S]methionine. Using immunoprecipitation techniques, we demonstrated that exposure to 8-bromo-cAMP prevented the de novo synthesis and secretion of the extracellular matrix component fibronectin, but enhanced the production of hCG subunits. The effects of the cyclic nucleotide on synthesis and secretion of these proteins were evident within 24 h. 8-Bromo-cAMP increased the cellular content of mRNA encoding the hCG alpha- and beta-subunits and prevented the increase in fibronectin mRNA, as determined by blot hybridization analysis using specific cDNA probes. These findings demonstrate that cyclic nucleotides regulate the synthesis of several specific proteins in cultured human trophoblast by regulating levels of the mRNAs encoding the proteins. The actions of cyclic nucleotides in this regard may be essential for the normal expression of trophoblast endocrine function.

8-Bromo Cyclic Adenosine Monophosphate↗