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At least 595 records · Page 33Linked to original sources
PubMed1988

Differential production of human chorionic gonadotropin and free subunits in gestational trophoblastic disease.

Serum levels of human chorionic gonadotropin (hCG) and its free subunits (alpha hCG and beta hCG) were determined by means of highly sensitive and specific monoclonal and antipeptide-based monoclonal immunoradiometric assays. During normal pregnancy, the beta hCG to hCG ratio appears constant at approximately 0.5% after 5 weeks of gestation. In contrast, gestational choriocarcinoma was characterized by absolute serum beta hCG levels varying from three to 280 times greater than the maximum values observed during pregnancy and by exceedingly high beta hCG to hCG ratios. In complete hydatidiform mole, this ratio was intermediate between normal pregnancy and choriocarcinoma. The ratios of free beta hCG to hCG will distinguish normal from complete molar pregnancy (p less than 10(-8)), hydatidiform mole from choriocarcinoma (p less than 10(-4)), and choriocarcinoma from normal pregnancy (p less than 10(-8)) with high probability. Finally, it was found by means of the high sensitivity hCG immunoradiometric assays (less than 0.02 ng/ml) that this assay predicted very early tumor recurrence in patients with gestational choriocarcinoma.

Adult↗
PubMed1987

Human chorionic gonadotropin in uterine and peripheral blood tested with an enzyme-linked immunosorbent assay and a radio-immuno assay in cases of spontaneous abortion.

Human chorionic gonadotropin (hCG) was analysed by a hCG-beta-subunit radio-immunoassay (hCG-beta-Ria) and a rapid serum test in uterine and peripheral blood in 29 cases of spontaneous abortion. The levels of hCG were significantly higher in uterine than in peripheral blood. The rapid serum test was correctly positive in all 29 samples of uterine and in 28 of peripheral blood.

Abortion, Spontaneous↗
PubMed1995

Fusing the carboxy-terminal peptide of the chorionic gonadotropin (CG) beta-subunit to the common alpha-subunit: retention of O-linked glycosylation and enhanced in vivo bioactivity of chimeric human CG.

The hCG beta-subunit contains a carboxy-terminal extension bearing four serine-linked oligosaccharides [carboxy-terminal peptide (CTP)], which is important for maintaining its longer half-life compared with the other glycoprotein hormones. Previously, we enhanced the in vivo half-life of FSH by fusing the CTP to the carboxy end of FSH beta coding sequence. The alpha-subunit is common to the glycoprotein family. We constructed alpha-subunit CTP chimeras, since such analogs with the appropriate O-linked glycosylation and conformation would increase the in vivo stability of the entire glycoprotein hormone family. Two chimeras were constructed using overlapping polymerase chain reaction mutagenesis: a variant with CTP at the carboxy end and another analog with the CTP at the N-terminal region of the subunit, between amino acids 3 and 4. The latter design was based on models showing that the amino-terminal region of alpha is not involved in assembly with the beta-subunit, nor is it essential for receptor binding and signal transduction. These chimeras were cotransfected with the hCG beta gene into Chinese hamster ovary cells. The chimeras were secreted and combined efficiently with the CG beta-subunit, comparable to the wild type alpha-subunit. CG dimers containing the alpha-subunit chimera with CTP at the carboxy end of the subunit had a much lower binding affinity for the hLH-hCG receptor in vitro, whereas the binding of the dimer containing the CTP at the amino-terminal end of the subunit was similar to wild type hCG. Furthermore, the in vivo activity of this analog was enhanced significantly. Moreover, regardless of the two insertion points in the alpha-subunit, the CTP sequence was O-glycosylated. These data suggest that the entire signal for O-glycosylation is primarily contained within the CTP sequence and is not dependent on the flanking regions of the recipient protein. The transfer of CTP to the alpha-subunit of hCG results in an agonist with prolonged biological action in vivo. These data further support the rationale for using the CTP as a general target to increase the potency of bioactive glycoproteins.

Androgens↗
PubMed1992

Design of a long-acting follitropin agonist by fusing the C-terminal sequence of the chorionic gonadotropin beta subunit to the follitropin beta subunit.

Follitropin (FSH) is a pituitary glycoprotein hormone that is essential for the development of ovarian follicles and testicular seminiferous tubules. FSH is used clinically to stimulate follicular maturation for in vitro fertilization and treatment of anovulatory women. One issue regarding the clinical use of FSH is its short half-life in the circulation. To address this point, we constructed chimeric genes containing the sequence encoding the C-terminal peptide of the chorionic gonadotropin beta subunit (CG beta) fused to the translated sequence of the human FSH beta subunit (FSH beta). This region of CG beta is important for maintaining the prolonged plasma half-life of human CG dimer. The presence of the C-terminal peptide sequence did not significantly affect assembly of FSH beta with the alpha subunit or secretion of the dimer. In vitro receptor binding and steroidogenic activity of dimer bearing the FSH beta-C-terminal peptide chimera were the same as wild-type FSH. However, both the in vivo potency and half-life in circulation of the dimer bearing either one or two C-terminal peptide units were enhanced. Dimers containing FSH beta-CG beta chimeras could serve as potent FSH agonists for clinical use, and the present strategy may have wide applications for enhancing the in vivo half-life of diverse proteins.

Animals↗
PubMedDate not supplied

[Pharmacokinetics of mifepristone and kinetics of chorionic gonadotropin beta-subunit (beta-HCG) and progesterone in plasma of pregnant women during pharmacological interruption of early pregnancy].

Reliable correlations between the parameters of mifepriston pharmacokinetics describing the rate of drug elimination from the blood plasma and the levels of beta-human chorionic gonadotropin (beta-HCG) and progesterone reflecting the state of gestation in females have been established fore the first time. According to these relationships, the half elimination time, the mean retention time, and the plasma clearance of mifepriston can be considered as predictors of the clinical efficacy of this drug for the early pregnancy interruption.

Abortifacient Agents, Steroidal↗
PubMed1986

A new radioimmunoassay for human chorionic gonadotropin using monoclonal antibody.

A new radioimmunoassay (RIA) for human Chorionic Gonadotropin (hCG) was developed using murine monoclonal antibody to the beta-subunit of hCG (beta-hCG). The IgG fraction of the monoclonal antibody which did not react with 125I-beta-hCG was purified from hybridoma ascites, and covalently coupled to Sepharose 4B. This solid-phase antibody was incubated with standard hCG or serum sampled for 48 hours. The reaction medium was then removed by centrifugation and 125I-beta-hCG and anti-beta-hCG rabbit polyclonal antibody were added to the precipitate. The alcohol precipitation method was used for separating "bound" and "free" forms in the second reaction. The sensitivity for hCG in this assay system was 0.5 mIU/ml serum and the cross-reactivity with human Luteinizing Hormone (hLH) was 0.4%. This assay system was shown to be clinically applicable. Serial serum samples from two patients with trophoblastic disease were assayed and minute amounts of hCG, which could not be determined by conventional assay methods, could be assayed by this new RIA.

Adult↗
PubMed1995

Triple marker (alpha-fetoprotein, unconjugated estriol, human chorionic gonadotropin) versus alpha-fetoprotein plus free-beta subunit in second-trimester maternal serum screening for fetal Down syndrome: a prospective comparison study.

OBJECTIVE: Our purpose was to compare the efficacy of triple-marker screening (alpha-fetoprotein, unconjugated estriol, human chorionic gonadotropin) with alpha-fetoprotein plus free beta-human chorionic gonadotropin. STUDY DESIGN: Free beta-human chorionic gonadotropin was concurrently assayed in 2349 maternal serum samples. Trivariate and bivariate algorithms were used to calculate the risk for fetal Down syndrome by the two protocols. Free beta-human chorionic gonadotropin from 12 cases of fetal Down syndrome previously screened with the triple marker was retrospectively assayed. RESULTS: Mean maternal age of our study was 29.8 years (range 14 to 51 years). The initial screen-positive rate with the triple marker was 8.0% compared with 12.8% for alpha-fetoprotein plus free beta-human chorionic gonadotropin. All three cases of fetal Down syndrome ascertained in our prospective study were detected by the triple marker; in contrast, one of three was detected by alpha-fetoprotein plus free beta-human chorionic gonadotropin. By adding 12 additional cases of fetal Down syndrome, 12 of 15 (80%) were screen positive with triple marker and nine of 15 (60%) were screen positive with alpha-fetoprotein plus free beta-human chorionic gonadotropin. CONCLUSION: The detection rate of fetal Down syndrome was greater by use of a triple marker screen than when using alpha-fetoprotein plus free beta-human chorionic gonadotropin. Our data do not support the claims of other studies that suggest that alpha-fetoprotein plus free beta-human chorionic gonadotropin is superior to triple markers.

Adolescent↗
PubMed2001

Utility of commonly used commercial human chorionic gonadotropin immunoassays in the diagnosis and management of trophoblastic diseases.

BACKGROUND: Patients with trophoblastic diseases produce ordinary and irregular forms of human chorionic gonadotropin (hCG; e.g., nicked hCG, hCG missing the beta-subunit C-terminal segment, hyperglycosylated hCG, and free beta subunit) that are recognized to differing extents by automated immunometric hCG (or hCG beta) assays. This has led to low or false-negative results and misdiagnosis of persistent disease. False-positive hCG immunoreactivity has also been detected, leading to needless therapy for trophoblastic diseases. Here we compare seven commonly used hCG assays. METHODS: Standards for five irregular forms hCG produced in trophoblastic diseases, serum samples from 59 patients with confirmed trophoblastic diseases, and serum samples from 12 women with previous false-positive hCG results (primarily in the Abbott AxSYM assay) were blindly tested by commercial laboratories in the Beckman Access hCG beta, the Abbott AxSYM hCG beta, the Chiron ACS:180 hCG beta, the Baxter Stratus hCG test, the DPC Immulite hCG test, the Serono MAIAclone hCG beta tests, and in the hCG beta RIA. RESULTS: Only the RIA and the DPC appropriately detected the five irregular hCG standards. Only the Beckman, DPC, and Abbott assays gave results similar to the RIA in the patients with confirmed trophoblastic diseases (values within 25% of RIA in 49, 49, and 54 of 59 patients, respectively). For samples that were previously found to produce false-positive hCG results, no false-positive results were detected with the DPC and Chiron tests (5 samples, median <2 IU/L), but up to one-third of samples were false positive (>10 IU/L) in the Beckman (1 of 5), Serono (2 of 9), and Baxter assays (1 of 5), and the hCG beta RIA (3 of 9; median for all assays, <5 IU/L). These samples, which produced false-positive results earlier in the Abbott AxSYM assay, continued to produce high values upon reassessment (median, 81 IU/L). CONCLUSIONS: Of six frequently used hCG immunometric assays, only the DPC detected the five irregular forms of beta hCG, agreed with the RIA, and avoided false-positive results in the samples tested. This assay, and similarly designed assays not tested here, seem appropriate for hCG testing in the diagnosis and management of trophoblastic diseases.

Choriocarcinoma↗
PubMed1991

Goat antibodies to amino acid sequences of human chorionic gonadotropin (hCG)

Human chorionic gonadotropin, its two subunits and its conjugate with thyroglobulin were used for immunization. The strongest immunogens were demonstrated to be the intact hormone and beta subunit, the weakest was alpha subunit. Using three peptides corresponding to hormone subunits coupled to Sepharose 4B various antibodies were isolated from goat antiserum by immunoaffinity chromatography. Specificity of the purified antibody preparations was studied. It was demonstrated that enzyme linked immunosorbent assay with two goat antibodies--one for coating of microtiter plates and the other one conjugated with peroxidase--is suitable for sensitive assays of both human chorionic gonadotropin and luteinizing hormone. Specific and sensitive assays were performed using combination of goat antibody anti-122-145-beta hCG and monoclonal antibody anti-alpha hCG.

Amino Acid Sequence↗
PubMed1983

Nucleotide sequence of the cDNA encoding the precursor of the beta subunit of rat lutropin.

We have determined the nucleotide sequences of cDNAs encoding the precursor of the beta subunit of rat lutropin, a polypeptide hormone that regulates gonadal function, including the development of gametes and the production of steroid sex hormones. The cDNAs were prepared from poly(A)+ RNA derived from the pituitary glands of rats 4 weeks after ovariectomy and were cloned in bacterial plasmids. Bacterial colonies containing transfected plasmids were screened by hybridization with a 32P-labeled cDNA encoding the beta subunit of human chorionic gonadotropin, a protein that is related in structure to lutropin. Several recombinant plasmids were detected that by nucleotide sequence analyses contained coding sequences for the precursor of the beta subunit of lutropin. Complete determination of the nucleotide sequences of these cDNAs, as well as of cDNA reverse-transcribed from pituitary poly(A)+ RNA by using a synthetic pentadecanucleotide as a primer of RNA, provided the entire 141-codon sequence of the precursor of the beta subunit of rat lutropin. The precursor consists of a 20 amino acid leader (signal) peptide and an apoprotein of 121 amino acids. The amino acid sequence of the rat lutropin beta subunit shows similarity to the beta subunits of the ovine/bovine, porcine, and human lutropins (81, 86, and 74% of amino acids identical, respectively). Blot hybridization of pituitary RNAs separated by electrophoresis on agarose gels showed that the mRNA encoding the lutropin beta subunit consists of approximately 700 bases. The availability of cDNAs for both the alpha and beta subunits of lutropin will facilitate studies of the regulation of lutropin expression.

Amino Acid Sequence↗
PubMedDate not supplied

[Proceedings: Development and clinical applications of radioimmunoassays specific to luteinizing hormone and human chorionic gonadotropin (author's transl)].

Antisera directed against the beta subunit of human Luteinizing Hormone (h. LH) and Chorionic Gonadotropin (HCG) were made totally specific to either gonadotropin by adsorbing cross-reacting antibodies. Simple absorption in solution or immunosorption on solid phase were employed. Pituitary functions were examined during pregnancy and until three weeks following delivery h.LH and HCG were assayed before and after injection of Luteinizing Hormone Releasing Hormone (LH-RH). Similiarly TSH was assayed in a homologous TSH beta subunit system before and after injection Thyrotropin Releasing Hormone (TRH). No pituitary release of LH was observed after LH-RH in our experimental conditions while TRH induced a surge of pituitary TSH in the blood.

Chorionic Gonadotropin↗
PubMed1991

[Diagnosis of ovum viability: comparative analysis between ultrasound and chorionic gonadotropin hormone].

In a retrospective study carried out in the Hospital de Gineco-Obstetricia del Centro Médico León, Gto., Instituto Mexicano del Seguro Social, 61 patients were studied in order to compare the sensitivity and specificity values and the correlation coefficient between the hormonal assays (Human Chorionic Gonadotropin, HCG) and the ultrasound scanning. The qualitative concentrations of HCG had a sensitivity of 37.5% and a specificity of 100%. The levels of subunit beta of HCG had sensitivity of 25% and specificity of 100%. The whole correlation coefficient of the hormonal method (HCG) was R = 0.51 (P less than 0.01). The ultrasound monitoring had a sensitivity of 855 and specificity of 100%, with a correlation coefficient R = 0.88 (P less than 0.01). It was concluded that ultrasound scanning has a better sensitivity and higher correlation than human chorionic gonadotropin assays in the diagnosis of ovum vitality.

Abortion, Incomplete↗
PubMed2000

Disulfide bond formation is not required for human chorionic gonadotropin subunit association. Studies with dithiothreitol in JEG-3 cells.

To study the influence of disulfide bridge formation on the assembly of the subunits of human chorionic gonadotropin in JEG-3 choriocarcinoma cells, dithiothreitol (DTT) was used to create a reducing milieu in the endoplasmic reticulum (ER) in vivo. In the presence of 5 mM DTT during pulse-chase experiments all of the beta-subunit precursors observed in unperturbed cells (pbeta(0), pbeta(1), pbeta(2), and beta(*)) collapsed into the pbeta(0) form. The reducing milieu of the ER was reoxidized in less than 5 min after removal of DTT from the medium. DTT markedly increased the half-life of the pbeta(0) precursor from 8.8 to 65.2 min. Under reoxidation conditions, the beta-subunit precursors folded back from pbeta(0) in less than 5 min. In unperturbed JEG-3 cells, the alpha-subunit was present in both fully glycosylated and monoglycosylated precursor (pre-alpha) forms. The attachment of the second N-linked glycan residue of the alpha-subunit was accelerated in the presence of DTT, and consequently pre-alpha-subunit was missing from the DTT-treated cultures. The formation of alphabeta-dimers appeared to be at least partially independent of the oxidation state in the ER. The alphabeta-dimer was present under conditions in which disulfide bridge formation was prevented by exposure to 5 mM DTT before and during the pulse period. This clearly suggests that the human chorionic gonadotropin subunits may acquire association-competent conformations even when no disulfide bridge formation has taken place.

Chorionic Gonadotropin, beta Subunit, Human↗