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At least 307 records · Page 17Linked to original sources
PubMed1989

Expression of biologically active human chorionic gonadotropin and its subunits by recombinant vaccinia virus.

Vaccinia virus (VV) expression vector was used to clone the genes for coding alpha and beta subunits of human chorionic gonadotropin (hCG). Recombinant viruses VSL3 and VSS1 containing these genes were selected as blue coloured plaques on the basis of co-expression of Escherichia coli beta-galactosidase in the infected cells. CV-1 cells when infected with VSL3 or VSS1 secreted 2.4 and 1.8 micrograms of alpha and beta hCG subunits, respectively, per 3 x 10(6) cells after 24 h of infection. The subunit proteins expressed individually had immunoreactivity with monoclonal and polyclonal antibodies specific to hCG. The subunit hormonal peptides associated with each other during co-infection to form the complete hCG dimer, which was biologically active as evident from the induction of steroidogenesis in a mouse Leydig cell system.

Animals↗
PubMed1981

Radioimmunoassay of human chorionic gonadotropin beta-subunit as an early diagnostic test in ectopic pregnancy.

Serum HCG-beta has been assayed in 100 cases of ectopic pregnancy. Results above 10 IU/l were considered positive. Positive values were found in 97 cases, of which 23 were within the range of a normal pregnancy, one was above and 73 below the normal range. In the 3 cases with a negative HCG-beta value, devitalized ectopic pregnancies were found at operation. The routine urine pregnancy test was negative in 53, positive in 29 and not performed in 18 cases.

Chorionic Gonadotropin↗
PubMed1985

Human chorionic gonadotropin alpha-subunit of normal placenta: characterization of synthesis and association with beta-subunit.

The forms of human chorionic gonadotropin (hCG) alpha-subunit synthesized and released by normal placental tissue were examined in explants of first trimester placenta that had been incubated for 30 min with [35S]methionine and then incubated for 6 h in medium containing unlabeled methionine. The media and tissue extracts collected at 0, 0.5, 1, 2, 4, and 6 h after the exposure to [35S]methionine were chromatographed on Sephadex G-100 and the amounts of radioimmunoassayable alpha-subunit and immunoprecipitable 35S-labeled alpha-subunit were determined. In tissue extracts, a single form of alpha-subunit was observed at 0 h that had an apparent molecular weight smaller (Ve/Vo = 1.90) than that of a urinary hCG alpha reference preparation (Ve/Vo = 1.81). With chase times of 0.5, 1, 2, and 4 h, a second peak of alpha-subunit was detected that had a larger apparent molecular weight (Ve/Vo = 1.68), and the ratio of large to small forms increased progressively with incubation time. In contrast to that in the extracts, the 35S-labeled alpha-subunit in the culture medium consisted entirely of the large form. Large and small intracellular forms of free alpha-subunit exhibited less than 2% recombination with beta-subunit, as evidenced by gonadotropin receptor binding activity. These studies suggest that normal placental tissue synthesizes a small precursor form of free hCG alpha-subunit that is converted to a larger form prior to secretion and that the free forms of alpha-subunit do not bind to purified hCG beta-subunit.

Chorionic Gonadotropin↗
PubMed1981

Use of glycosidase digested human chorionic gonadotropin beta-subunit to explain the partial binding of ectopic glycoprotein hormones to Con A.

Recent studies have demonstrated that ectopic glycoprotein hormones only partially bind Con A. To investigate the basis for these findings, the Con A binding of ectopic hCG beta from DoT cervical carcinoma cells was examined after digestion with various glycosidases. Ectopic hCG beta only partially bound Con A, as was the case after digestion with neuraminidase and beta-galactosidase. However, subsequent digestion with N-acetylhexosaminidase increased Con A binding to 96%. It is apparent that Con A binding of ectopic hCG can be inhibited by a residue removed by N-acetylhexosaminidase, probably extra beta-N-acetylglucosamine linked to beta-mannose on N-linked oligosaccharides. The method used involved the glycosidase digestion of glycoprotein alkylated under denaturing conditions and was first validated with milligram amounts of standard hCG beta.

Acetylglucosaminidase↗
PubMedDate not supplied

The influence of smoking and parity on serum markers for Down's syndrome screening.

OBJECTIVE: To evaluate the impact of smoking and number of previous births on maternal serum levels of alpha-fetoprotein and free beta-subunit of human chorionic gonadotropin (free beta-hCG). METHODS: The study included 3,252 completed unaffected singleton pregnancies that proceeded beyond 37 weeks' gestation and resulted with a birth of healthy child. Smoking status of mothers and data concerning gravidity and parity were collected at the sampling date. Serum markers were measured between 13 and 22 gestational weeks, corrected for maternal weight, and converted to multiples of median (MoM) for unaffected pregnancy of the corresponding gestational age. Median MoM values for both markers were examined in relation to both: smoking habits and number of previous births. RESULTS: Smokers had significantly decreased free beta-hCG MoM values compared to nonsmokers (p < 0.001). The median levels showed a negative relationship with the number of previous births. The significance of a decreasing trend was proved, both in smokers (p < 0.001) and nonsmokers (p < 0.001). The median maternal serum alpha-fetoprotein MoM values did not show any significant dependence, neither with regard to smoking (p = 0.65) nor with regard to parity (p = 0.07). CONCLUSIONS: The recommendable adjustment of serum markers to smoking habits, especially concerning the free beta-hCG levels, would be worthwhile. The evidence of the coexisting influence of parity on serum levels of free beta-hCG, both in smokers and nonsmokers, should perhaps be a stimulus for reconsideration of which corrections the screening performance is dependent on.

Adolescent↗
PubMed1991

Novel cyclic adenosine 3',5'-monophosphate response element in the human chorionic gonadotropin beta-subunit gene.

CG is encoded by separate alpha- and beta-subunit genes. Expression of both genes is stimulated by cAMP, but the kinetics of activation are different, with cAMP stimulation of the alpha gene preceding that of the beta gene. The cAMP response element (CRE) in the alpha gene contains a palindromic DNA sequence, TGACGTCA, that binds the transcription factor CREB, a nuclear phosphoprotein that is activated by protein kinase-A. Previously, detailed characterization of a CRE in the CG beta gene had been difficult due to low levels of expression in transfected cells. In this study the 5'-flanking sequence of the CG beta gene was fused to a sensitive luciferase (LUC) reporter gene, allowing delineation of a CG beta CRE in transient expression assays performed in JEG-3 choriocarcinoma cells. The full-length CG beta promoter, -3700 to 362 basepairs (bp), was stimulated 8- to 14-fold by treatment with 1 mM 8-bromo-cAMP. Analyses of a series of deletion mutants in the CG beta promoter demonstrated that -311 CG beta LUC retained nearly complete cAMP stimulation, but deletion to -187 bp eliminated cAMP responsiveness. Overlapping DNA fragments between -311 and -30 bp were fused to a heterologous promoter (-99 alpha LUC) to further define the locations of basal elements and CREs. Basal expression required a combination of at least two distinct elements between -311 and -30 bp, whereas cAMP responsiveness was conferred by sequences between -311 and -202 bp. Shorter DNA sequences within this region were insufficient for cAMP stimulation, suggesting that more than one element may be required. DNase-I footprinting and gel mobility shift studies demonstrated at least three distinct protein-binding sites within the CG beta CRE sequence. Recombinant CREB (expressed in E. coli) did not bind to these sites, and they share no sequence homology with the alpha gene CRE, indicating that a cAMP-responsive transcription factor other than CREB interacts with the CG beta promoter.

Base Sequence↗
PubMed1983

Relationship of prolactin and estradiol to human chorionic gonadotropin following molar gestation.

Serial plasma concentrations of the beta subunit of human chorionic gonadotropin (beta-hCG), prolactin, and estradiol were examined and correlated in 22 women after evacuation of a molar pregnancy for up to 15 weeks into the postmolar phase. The mean levels of prolactin were lower, estradiol levels were higher, and beta-hCG levels were slightly lower but comparable to those reported for women in the first postpartum week. Mean concentrations of all three hormones then declined during the postmolar period; however, beta-hCG remained detectable (greater than or equal to 5 mIU/ml) in some women for up to the fifteenth week, while the nadirs in mean prolactin and mean estradiol levels occurred at 14 and 13 weeks, respectively. The plasma concentrations of beta-hCG correlated with those of prolactin (r = 0.93) and estradiol (r = 0.94), while the levels of the latter two hormones also correlated (r = 0.84).

Adolescent↗
PubMed1982

Commercial radioimmunoassay for beta subunit of human chorionic gonadotropin: falsely positive determinations due to elevated serum luteinizing hormone.

Among 17 men who had received seemingly curative treatment for unilateral non-seminomatous germ cell tumors for the testis and who had consistently normal serum human chorionic gonadotropin (HCG) levels at a reference laboratory, 7 (41%) had at least one falsely positive commercial serum HCG determination. To investigate the cause of these falsely positive determinations the authors measured the cross reactivity of luteinizing hormone (LH) and follicle stimulating hormone (FSH) standards in the commercial HCG assay, and studied the relationship between commercial HCG levels and serum LH levels, serum FSH levels and gonadal status in men with and without normal gonadal function. The falsely positive HCG determinations appeared to be due to elevated serum LH levels and cross reactivity of LH in the commercial HCG assay because: 1) there was substantial cross reactivity of the LH standards in the commercial assay, 2) the serum LH was elevated in four of six men with solitary testes, 3) there was a striking correlation between elevated serum LH levels and falsely elevated commercial HCG levels in ten men with solitary or absent testes, and 4) there were no falsely positive HCG determinations in 13 normal men but there were falsely positive HCG determinations in seven of ten anorchid men.

Adolescent↗
PubMed1988

Altered glycosylation is induced in both alpha- and beta-subunits of human chorionic gonadotropin produced by choriocarcinoma.

The two subunits of human chorionic gonadotropin (hCG) purified from the urine of a patient with choriocarcinoma were successfully separated by SDS-polyacrylamide gel electrophoresis. A comparative study of the oligosaccharides released from the two subunits by hydrazinolysis revealed that altered glycosylation occurs in both subunits and possibly at all four asparagine sites of the choriocarcinoma hCG molecule.

Asparagine↗
PubMed1997

The stability of hCG and free beta-subunit in serum samples.

Human chorionic gonadotropin (hCG) free beta-subunit measurement is used as a screening test for Down syndrome pregnancies. Use, shipping, and storage conditions have, however, to some extent been limited by a stability problem; the swamping of serum free beta-subunit levels by new molecules coming from the dissociation of hCG. We examined the stability of free beta-subunit levels in six fresh serum samples from the first trimester of pregnancy. The mean hCG level in the fresh serum samples was 3710 +/- 886 micrograms/l; this included a 3.0 +/- 0.39 per cent nicked hCG component. The mean free beta-subunit level was 0.27 +/- 0.04 per cent and the nicked free beta-subunit level was 0.10 +/- 0.04 per cent of the hCG concentration. Samples were incubated for 0, 0.5, 1, 2, and 4 weeks at 21 degrees C, with no additives. After half a week, the free beta-subunit level rose to 137 +/- 17 per cent, and after 4 weeks to 360 +/- 53 per cent of the starting level (ANOVA P < or = 0.05). Parallel, but greater, increases were observed in nicked hCG and nicked free beta-subunit levels. The experiment was repeated with the addition of penicillin-streptomycin-fungizone to fresh serum. After half a week, the free beta-subunit level increased to only 101 +/- 3.0 per cent (t-test, with/without additive, P < or = 0.05), and after 4 weeks to only 136 +/- 7.8 per cent (P < or = 0.05) of the starting level. At 4 weeks, nicked hCG production was reduced from 499 +/- 83 to 158 +/- 15 per cent of the starting level. We infer that nicking of hCG and dissociation of unstable nicked hCG may be pathways supplementing free beta-subunit in serum samples. We further infer that hCG nicking activity comes from microbes, and that free beta-subunit levels can be stabilized for shipping and longer storage by antibiotic/antimycotic additives.

Amphotericin B↗
PubMed2000

Beta-human chorionic gonadotropin in semen: a marker for early detection of prostate cancer?

BACKGROUND AND PURPOSE: The beta subunit of human chorionic gonadotropin (beta-hCG) has been detected in prostate cancer by immunologic and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. Recently, prostate cells have been detected in human ejaculate. This study aimed to determine if beta-hCG could be detected by RT-PCR from prostatic mRNA isolated from semen, thus providing a noninvasive procedure for prostate cancer detection. RESULTS: Expression of beta-hCG in prostate cancer was confirmed by immunohistochemistry methods. The protein was associated with low-grade disease: Gleason Score 4 through 7 (N = 26; 69%) but not high-grade (Gleason 8 or 9) or metastatic (lymph node) disease (N = 12; 8%). Normal prostate tissue was negative for beta-hCG (N = 14). The beta-hCG RT-PCR was performed on RNA extracted from seven human prostate cancer cell lines, which showed variable expression of beta-hCG mRNA. Semen was collected from patients suspected of having carcinoma of the prostate (N = 94) and from volunteers who were under the age of 30 years and had no family history of prostate cancer (N = 9). mRNA for beta-hCG was detected in the ejaculates of 12% of the patients with confirmed prostate cancer (N = 42) but not in any patients found to be negative for cancer (N = 52). Expression of beta-hCG mRNA was found in 22% of the control samples. CONCLUSIONS: The beta-hCG protein is expressed in low-grade prostate cancer and can be detected by RT-PCR in both prostate cancer cell lines and human ejaculate. However, the low percentage of detection in ejaculate suggests that beta-hCG in semen does not provide a useful marker for early prostate cancer detection.

Adult↗
PubMed1980

Stimulation of N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate of ectopic production of the free beta subunit of chorionic gonadotropin by a human brain tumor cell line.

Previous studies have favored a basic difference in the regulation of specialized protein production by cells derived from the usual tissue of origin (eutopic) and cancer cells derived from a tissue not normally producing the protein (ectopic). Thus N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate was believed to stimulate only eutopic (but not ectopic) chorionic gonadotropin production, and butyrate to stimulate only ectopic (but not eutopic). However, in CBT, a human brain tumor cell line, we find that N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate, but not butyrate, stimulated ectopic production of the beta subunit of chorionic gonadotropin. We conclude that neither butyrate nor cyclic adenosine 3':5'-monophosphate derivatives reliably discriminate ectopic from eutopic regulation.

Brain Neoplasms↗
PubMed2004

False-positive human serum chorionic gonadotropin in a patient with a history of germ cell cancer.

Tumor markers, including the beta-subunit of human chorionic gonadotropin (beta-hCG), and radiological imaging methods are commonly used for the diagnosis and monitoring of testicular cancer. We report of a patient with a history of classical seminoma stage I who had elevated serum levels of beta-hCG suggesting relapse 5 years after initial treatment. Radiological evaluation revealed a pericardial cyst, which was surgically removed. Histological evaluation did not demonstrate malignant tissue, suggesting a false-positive beta-hCG. Further workup confirmed this suspicion as we could demonstrate false-positive test results due to heterophilic antibodies detectable in the patient's serum. This case stresses the need for verification of beta-hCG levels in patients where clinical results are not in line with laboratory results.

Adult↗