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PubMed1990

Maternal serum Down syndrome screening: free beta-protein is a more effective marker than human chorionic gonadotropin.

The use of quantitative human chorionic gonadotropin measurement in obstetrics has a long and successful history. Prior studies on the utility of human chorionic gonadotropin in Down syndrome screening have utilized assays that measure the intact human chorionic gonadotropin molecule. This study targeted a distinct marker, the human chorionic gonadotropin free beta-protein, which is present in second-trimester maternal serum at much lower concentrations than is intact human chorionic gonadotropin. Our study of 29 cases of trisomy 21 and 450 control samples shows 80% detection efficiency with maternal serum alpha-fetoprotein, the free beta-protein, and maternal age in pregnancies under 17 weeks' gestation. We conclude that the combination of maternal serum alpha-fetoprotein and the human chorionic gonadotropin free beta-protein will be useful in the prenatal detection of trisomy 21.

Antibodies, Monoclonal↗
PubMed1981

In vitro induction of human suppressor T cells by a chorionic gonadotropin preparation.

Human chorionic gonadotropin (hCG) in physiological retroplacental concentration has been shown to possess the capacity of inducing human lymphocytes which are subsequently competent to depress an antibody response induced by purified protein derivative of tuberculin, phytohemagglutinin, lipopolysaccharide and pokeweed mitogen. These suppressor cells inhibited the T cell-dependent mitogen-induced activation of lymphocytes synthesizing IgM, IgG and IgA. No suppression by hCG-induced cells was observed in Epstein-Barr virus activated cell cultures, indicating a T cell origin of the target cell. It is suggested that this may represent a mechanism for the cellular basis of an hCG-induced immunosuppressive effect in pregnancy.

Adult↗
PubMed1977

Carboxypeptidase digestion of human chorionic gonadotropin.

Native human chorionic gonadotropin (hCG) was resistant to carboxypeptidase digestion even in the presence of urea. Isolated alpha subunit of the hormone (hCG-alpha), though unreactive to enzyme treatment in the absence of denaturant, released up to four amino acid residues from the C-terminus on incubation with a mixture of carboxypeptidases A and B in urea. While an hCG-alpha product which lacked Ser-92 recombined completely with intact hCG-beta, hCG-alpha from which Ser-92 recombined completely with intact hCG-beta, hCG-alpha from which Ser-92 and Lys-91 were removed showed only partial recombination. The two recombinants were devoid of any in vivo biologic activity, but retained some of the immunologic activity of the native recombinant. These findings indicate that the integrity of the C-terminal residue of serine in hCG-alpha is essential for the expression of in vivo biologic activity of the native hormone.

Amino Acids↗
PubMed2000

Functional contributions of noncysteine residues within the cystine knots of human chorionic gonadotropin subunits.

Human chorionic gonadotropin (hCG) is a heterodimeric member of a family of cystine knot-containing proteins that contain the consensus sequences Cys-X(1)-Gly-X(2)-Cys and Cys-X(3)-Cys. Previously, we characterized the contributions that cystine residues of the hCG subunit cystine knots make in folding, assembly, and bioactivity. Here, we determined the contributions that noncysteine residues make in hCG folding, secretion, and assembly. When the X(1), X(2), and X(3) residues of hCG-alpha and -beta were substituted by swapping their respective cystine knot motifs, the resulting chimeras appeared to fold correctly and were efficiently secreted. However, assembly of the chimeras with their wild type partner was almost completely abrogated. No single amino acid substitution completely accounted for the assembly inhibition, although the X(2) residue made the greatest individual contribution. Analysis by tryptic mapping, high performance liquid chromatography, and SDS-polyacrylamide gel electrophoresis revealed that substitution of the central Gly in the Cys-X(1)-Gly-X(2)-Cys sequence of either the alpha- or beta-subunit cystine knot resulted in non-native disulfide bond formation and subunit misfolding. This occurred even when the most conservative change possible (Gly --> Ala) was made. From these studies we conclude that all three "X" residues within the hCG cystine knots are collectively, but not individually, required for the formation of assembly-competent hCG subunits and that the invariant Gly residue is required for efficient cystine knot formation and subunit folding.

Chorionic Gonadotropin↗
PubMedDate not supplied

Characterization of monoclonal antibodies recognizing alpha and beta subunits of human chorionic gonadotropin hormone.

Human chorionic gonadotropin (hCG) hormone is required for maintenance of early pregnancy and is a potential marker in the diagnosis and prognosis of both pregnancy and trophoblastic diseases. Murine hybridomas were generated against purified hCG. Seven hybrid clones secreting antibodies against hCG molecule with IgG1/kappa subclass were established. The indirect ELISA result demonstrated that six MAbs (BEL-1 to BEL-6) recognized hCG in both holo and free beta subunit form with negligible cross-reactivity against a closely related hormone, human luteinizing hormone (hLH). In this fusion, only one MAb (ALC-1) showed a cross-reaction with hLH, which designated an alpha subunit specific. The outcome of Western blot ascertained that ALC-1 recognized the conformational epitope on alpha subunit of hCG at Mr 23 kDa band in nonreducing condition (NR). In contrast, epitopes belonging to all MAbs recognized beta subunit of hCG were in linear peptide structure at Mr 34 kDa band (NR) and Mr 26 kDa band (R). These six MAbs were further characterized by using two beta subunit carboxy-terminal synthetic peptides (beta109-119 and beta109-145). Three of them (BEL-1, BEL-3, and BEL-4) recognized only epitope harboring in beta109-145 fragment, the others recognized both types of the synthetic peptide. In order to select the most suitable MAbs specific to beta subunit of hCG for exploiting with ALC-1 in the sandwich-type immunometric assay, competitive ELISA was employed. Six individual MAbs specific to beta subunit of hCG were used to compete with biotinylated ALC-1 to evaluate the proximity of their epitopes on the holo form of hCG molecule. Of all six MAbs, BEL-5 depicted the lowest percent inhibition result, which indicated the bottom-most steric hindrance effect. Consequently, MAb BEL-5 will be the most appropriate antibody to utilize in concert with ALC-1 in place of devising a sandwich-type immunometric assay for measuring holo-hCG level.

Amino Acid Sequence↗
PubMed1990

Failure of gonadotropin-releasing hormone or human chorionic gonadotropin to enhance the fertility of repeat-breeder cows when administered at the time of insemination.

Repeat-breeder dairy cows failing to conceive to two previous inseminations were injected with saline (2 cc i.m.), gonadotropin-releasing hormone (GnRH, 2 cc i.m.) or human chorionic gonadotropin (hCG, 5000 IU i.v.) at the time of the third and succeeding inseminations. This field study involved 240 cows at three dairies. Mean conception rate was high (49.6%) for repeat-breeders, and did not differ among farms (P>0.10) or treatments (P>0.10), varying from 44.0 to 51.9% for farms and from 44.4 to 54.2% for treatments. The percentage of repeat-breeder cows bred during diestrus was very low on each of the three farms (mean = 7.9%). For this and other reasons discussed in the study, hormonal therapy was not successful in improving the conception rate of repeat-breeder cows under field conditions.

Journal Article↗
PubMed1983

Effects of ethanol on superovulation in the immature rat following pregnant mare's serum gonadotropin (PMSG) or PMSG and human chorionic gonadotropin treatment.

We sought to determine whether superovulation could occur in immature rats on a 5% ethanol diet and treated with pregnant mare's serum gonadotropin (PMSG) alone or with human chorionic gonadotropin (hCG). Holtzman female rats were divided into five groups at 20 days of age. Six rats (Group I) were killed at that age. Ten rats (Group II) were placed on an ad libitum laboratory chow diet and killed on Day 33. Twenty-four rats (Group III) were placed on an ad libitum laboratory chow diet. Twenty-four rats (Group IV) were placed on 5% ethanol liquid diet, while 24 rats in Group V were pair-fed with the animals in Group IV. At 30 days of age, 12 rats from each Group, III, IV, and V, received 25 IU of PMSG s.c. and were killed 74-76 h later. The remaining 12 rats from each Group, III, IV and V, received 25 IU of PMSG and 54-56 h later received 10 IU of hCG and were killed 20 h later. Ovulation occurred in all the rats of Groups III and V that received PMSG alone or with hCG. In the ethanol-treated rats that received PMSG alone, 75% ovulated, while 92% ovulated that received PMSG and hCG. The number of ova shed in the ethanol-PMSG-treated rats was significantly less than in the ethanol-PMSG-hCG-treated animals and in the controls. The uterine weights and morphology of the animals in Group IV were similar to those in Groups III and V. The study indicates that ethanol does not have a direct gonadotoxic effect on the ovary but indicates that ethanol has an effect on the hypothalamus and/or the pituitary, thereby disrupting the synthesis and/or release of luteinizing hormone releasing hormone (LHRH) or luteinizing hormone (LH).

Animals↗
PubMed1985

Gonadotropin-releasing hormone test and human chorionic gonadotropin test in the diagnosis of gonadotropin deficiency in prepubertal boys.

The discriminatory power of a gonadotropin-releasing hormone test and a human chorionic gonadotropin test in diagnosing gonadotropin deficiency was studied in 23 prepubertal boys with hypogonadotropic hypogonadism (HH). The boys were originally referred because of genital hypoplasia, delayed sexual maturation, or suspicion of HH. The diagnosis of HH was established clinically, in most cases after follow-up of several years. The results were compared with those of a reference group consisting of 44 prepubertal boys with incomplete testicular descent. Post-hCG serum testosterone level was the most sensitive discriminating variable, and was subnormal in 11 of 12 boys with HH (in one of 16 in the reference group). Post-GnRH serum LH concentration was the second most sensitive, and was subnormal in 15 of 23 boys with HH (two of the reference group). Our data indicate that post-hCG testosterone levels are of greater value than post-GnRH gonadotropin levels in the diagnosis of HH in prepubertal boys.

Adolescent↗
PubMed1997

cis-Acting elements and trans-acting proteins in the transcriptional inhibition of gonadotropin-releasing hormone gene by human chorionic gonadotropin in immortalized hypothalamic GT1-7 neurons.

We investigated the cis-acting elements and trans-acting proteins required for the transcriptional inhibition of the gonadotropin-releasing hormone (GnRH) gene by human chorionic gonadotropin (hCG) in GT1-7 neurons. Transient transfection of GT1-7 neurons with the 5'-flanking region of the rat GnRH gene-luciferase fusion constructs revealed that a 53-base pair (bp) sequence between -126 and -73 bp is required for the hCG inhibition. Nuclear extracts from GT1-7 neurons contained 110- and 95-kDa proteins that formed two complexes with the 53-bp sequence. These proteins are not related to Fos, cAMP response element-binding protein, Oct-1, or progesterone receptors, and hCG treatment selectively increased the 95-kDa protein. DNase I footprinting with GT1-7 cell nuclear extracts protected the -99 to -79-bp region, which contained a so-called imperfect AP-1 site (-99 to -94 bp) and two AT-rich palindromic sequences (-91 to -87 bp and -85 to -81 bp). The mutagenesis of the AT-rich regions, but not the AP-1 site, resulted in a loss of DNA binding of the 95-kDa protein and the inhibitory effect of hCG. In summary, our results are consistent with hCG inducing a 95-kDa trans-acting protein, which binds to -91- to -81-bp AT-rich sequences in the 5'-flanking region to inhibit the transcription of the GnRH gene.

Animals↗
PubMed1997

Primary gonadotropin releasing hormone and adjunctive human chorionic gonadotropin treatment in cryptorchidism: a clinical trial.

OBJECTIVES: The effect of intranasal gonadotropin-releasing hormone (GnRH) and intramuscular human chorionic gonadotropin (hCG) in the treatment of cryptorchidism was investigated in 48 prepubertal boys. METHODS: Forty-eight prepubertal boys with 70 undescended testes were enrolled into a prospective study between November 1989 and November 1991. GnRH was applied as nasal spray at a dose of 1.2 mg/day for 4 weeks. The patients with partial descent were subsequently treated with 1500 IU hCG weekly for 3 weeks. RESULTS: Complete descent was observed in 53% (37 of 70) of testes; 58% (15 of 26) in unilateral and 50% (22 of 44) in bilateral undescended testes. One abdominally located testicle did not respond to therapy. Of 37 testes located in the inguinal canal, seven (19%) descended. On the other hand, descensus rates were 100% for the testes located at the external inguinal ring and at a high scrotal level. Six primarily descended testes (16%) showed relapse during the follow-up. Surgery was performed in 12 patients (14 testes), revealing associated hernia in nine testes and epididymal anomalies in four. CONCLUSIONS: We believe that the GnRH and hCG combination is an effective therapy for undescended testes located at and beyond the external inguinal ring and should be the first treatment choice because of its noninvasiveness. Both unilateral and bilateral undescended testes responded with similar success rate to hormonal therapy. Surgery should be considered for proximal cryptorchidism.

Child↗
PubMed1987

Mature and immature oocytes in large and medium follicles after clomiphene citrate and human menopausal gonadotropin stimulation without human chorionic gonadotropin.

After ovarian stimulation with clomiphene citrate combined with human menopausal gonadotropin, 24 large (greater than 16 mm) and 16 medium (7 to 15 mm) human follicles were classified according to plasmatic estradiol (E2), luteinizing hormone (LH), and histology of the follicle and oocytes (in thin sections). An asynchronism of several hours between the stage of development of the largest and large cohort follicles is observed; overripeness of oocyte cumulus complex (OCC) is revealed. An asynchronous response to gonadotropins in granulosa and cumulus is also seen in the cohort of medium follicles of the same ovary, but not resumption of nuclear maturation of the oocyte. The efficiency of these oocytes after fertilization is discussed.

Adult↗
PubMed1992

Gonadotropin-releasing hormone agonist versus human chorionic gonadotropin for triggering follicular maturation in in vitro fertilization.

OBJECTIVE: To compare the use of gonadotropin-releasing hormone agonist (GnRH-a) with human chorionic gonadotropin (hCG) for triggering the final stage of follicular maturation for in vitro fertilization (IVF). DESIGN: In vitro fertilization outcome was determined in a randomized, prospective study. SETTING: The University of Toronto IVF program at The Toronto Hospital, Toronto General Division. PATIENTS AND INTERVENTIONS: One hundred seventy-nine women in the IVF program were given a subcutaneous injection of leuprolide acetate (500 micrograms) or an intramuscular injection of hCG (5,000 IU) 34 to 36 hours before oocyte retrieval. Vaginal progesterone (P) suppositories (50 mg) were used two times a day for luteal phase support. A subgroup of 41 women had serum estradiol (E2) and P levels determined 2 and 7 days after embryo transfer (ET). MAIN OUTCOME MEASURES: Pregnancy rates and luteal phase E2 and P were compared. RESULTS: In the GnRH-a group, there were 18 pregnancies from 84 ETs (20%). In the hCG group, there were 19 pregnancies from 95 ETs (19%). Luteal phase E2 and P levels were significantly lower in the GnRH-a group compared with the hCG group, and 18% of the former group had an apparent short luteal phase. CONCLUSIONS: Gonadotropin-releasing hormone agonist appears to be an effective alternative to hCG for inducing follicular maturation in IVF. The lower luteal phase E2 concentrations may potentially be beneficial in preventing ovarian hyperstimulation and for enhancing implantation. Better luteal phase support or a different dose of GnRH-a is needed to prevent luteal phase deficiency.

Chorionic Gonadotropin↗
PubMed1989

Elimination of disulfide bonds affects assembly and secretion of the human chorionic gonadotropin beta subunit.

Human chorionic gonadotropin (hCG) consists of two noncovalently joined alpha and beta subunits similar to the other glycoprotein hormones. To study the function of the individual disulfide bonds in subunit assembly and secretion, site-directed mutagenesis was used to convert the 12 cysteine (Cys) residues in the beta subunit of hCG to either alanine or serine. Both cysteines of proposed disulfide pairs were also mutated. These mutant hCG beta genes were transfected alone or together with the wild-type alpha gene into Chinese hamster ovary cells. Only 3-10% assembly could be achieved with derivatives containing single Cys mutations at positions 26, 110, 72, and 90, whereas no assembly was detected with the other 8 mutants. However, double mutations of pairs 26-110 or 23-72 showed increased dimer formation (11 and 36%, respectively). The secretion rate of individual mutants varied significantly. Whereas the Cys-23 and 72 mutants were secreted normally (t1/2 = 140-190 min), the Cys-26 mutant was secreted faster (t1/2 = 70 min), and the other 9 mutants were secreted slower (t1/2 = 280-440 min); mutations of both Cys at 26 and 110 caused much faster secretion (t1/2 = 34 min). Although the secretion rate of these mutants differed, they were quantitatively recovered in the medium except for mutant Cys-88, Cys-23-72, and Cys-34-88 (40, 55, and 10% secreted, respectively). Thus, interruption of any disulfide bond in the hCG beta subunit alters the structure sufficiently to block dimer formation and in some cases slow secretion, although the stability for most of the mutant hCG beta subunits is not greatly affected. The data indicate that interruption of any hCG beta disulfide bond generates different structural forms that are unable to assemble with the alpha subunit, and that the structural requirements for stability and assembly are different.

Animals↗