Paul D. Johnston

RADIOIMMUNOASSAY OF RELAXIN IN PREGNANCY WITH AN ANALOGUE OF HUMAN RELAXIN

A radioimmunoassay for relaxin was developed in which a synthetic analogue of human relaxin was used as standard, tracer, and immunogen. Relaxin could not be measured in sera from men or non-pregnant women, but was measurable in pregnant women from the tenth week of gestation until term. Concentrations ranged from 0.19-1.18 ng/ml, with highest levels measured in the first trimester.

Increase in cyclic AMP levels by relaxin in newborn rhesus monkey uterus cell culture.

SummaryA novel relaxin sensitive cell line of apparent smooth muscle origin has been established from a newborn rhesus monkey uterus (NRMU). NRMU cells respond to relaxin, in the presence of 1 μM forskolin, by producing intracellular adenosine 3′, 5′-cyclic monophosphate (cAMP). The increase in cAMP levels is dose, time and cell density dependent, reaching peak levels at 10 min when cells are seeded at 1×105 cells/well. Specificity was demonstrated by neutralization of the relaxin activity with anti-relaxin monoclonal and polyclonal antibodies, degradation of cAMP in the presence of phosphodiesterase, and confirmation of the absence of cGMP. Three synthetic analogs of human relaxin generated a dose-related cAMP response as did synthetic native human relaxin. Natural relaxin purified from human corpora lutea tissue also generated a response similar to synthetic human relaxin. Porcine and rat relaxins also increased levels of cAMP. Insulin, but not IGF I or IGF II, was capable of increasing cAMP levels in NRMU cells, however, 200 ng/mL were required to achieve cAMP levels comparable to 6.25 ng/ml relaxin. Combinations of relaxin with insulin, IGF I or IGF II did not increase cAMP levels above levels obtained with relaxin alone. The effect on NRMU cells of other hormones, growth factors and drugs potentially present in cell culture systems or serum samples was evaluated. In combination with relaxin, oxytocin significantly decreased the cAMP production below the levels induced by relaxin alone, whereas progesterone and prostaglandin E2 resulted in additive increases in cAMP. These data suggest that the NRMU cell line is an appropriate target tissue for studying relaxin-mediated biological responsesin vitro as well as functioning as the primary component of a relaxinin vitro bioassay.

Antenatal serum levels of relaxin in patients having preterm labour

Summary. This study is the first report of antenatal levels of relaxin measured by homologous radioimmunoassay in peripheral serum from patients who subsequently had a preterm delivery. Serial blood samples were collected antenatally from a group of subjects known to be at increased risk of preterm labour because of a past history of shortened pregnancy. Serum relaxin was measured using an homologous radioimmunoassay based on a synthetic bioactive analogoue of the native hormone. In women whose pregnancies ended preterm most measurements were within the range of values previously established in normal antenatal patients although some measurements early in pregnancy were above the normal range. These findings suggest that low serum levels of relaxin are not causatively related to the onset of labour before term.

Relaxin levels in antenatal patients following in vitro fertilization

The aim of this study was to investigate the relationship between serum relaxin and pregnancy outcome in a group of patients pregnant after in vitro fertilization (IVF). Patients who delivered a single live infant at term after IVF had mean serum levels of relaxin more than double the mean levels in normal antenatal patients. The high relaxin levels were compatible with delivery at term. However, because of the proposed role of relaxin in the process of cervical ripening, the high serum levels may help explain the high rate of preterm labor observed among IVF patients.

Prediction structure type for human leukocyte Interferon subtype A from circular dichroism

Vacuum UV circular dichroism studies were carried out on human leukocyte interferon subtype A. The secondary structure analysis for the CD spectrum shows 59% α‐helix, 16% antiparallel β‐sheet, no parallel β‐sheet, 18% β‐turns and 13% other structures. The analysis of the CD features for the prediction of tertiary structural class reveals that it is an all‐α type protein.

Relaxin Levels in Antenatal Patients following in Vitro Fertilization

The aim of this study was to investigate the relationship between serum relaxin and pregnancy outcome in a group of patients pregnant after in vitro fertilization (IVF). Patients who delivered a single live infant at term after IVF had mean serum levels of relaxin more than double the mean levels in normal antenatal patients. The high relaxin levels were compatible with delivery at term. However, because of the proposed role of relaxin in the process of cervical ripening, the high serum levels may help explain the high rate of preterm labor observed among IVF patients.

Relaxin, CA-125, progesterone, estradiol, Schwangerschaft protein, and human chorionic gonadotropin as predictors of outcome in threatened and nonthreatened pregnancies**Supported by the John Rock Chair, Department of Obstetrics and Gynecology, Tulane University School of Medicine.††Presented in part at the 36th Annual Meeting of the Society for Gynecologic Investigation, San Diego, California, March 15 to 18, 1989.

Progesterone (P), estradiol (E2), relaxin, CA-125, Schwangerschaft protein, and human chorionic gonadotropin (hCG) were measured in 221 pregnancies (less than or equal to 77 days gestation). The cohort was divided into asymptomatic subjects (group I, n = 117) and those with threatening symptoms (group II, n = 104). Outcome was ascertained as viable (normal at 14 weeks, n = 131), spontaneous abortion (n = 58), or ectopic gestation (n = 32). Statistical analysis revealed no differences in the mean maternal or gestational ages among the viable pregnancies, abortions, and ectopics in group I and group II. In group I, significant differences in the means were noted for P, hCG, relaxin, and CA-125 among those destined to abort, compared with those who were not. In group II, differences were noted in P, hCG, relaxin, and E2 when viable and nonviable pregnancies were compared. Within group II, there were significant differences between the means of E2 and CA-125 when the aborters were contrasted with ectopics. Receiver operating characteristic curve analysis revealed that P was the single most reliable predictor and was most effective in threatened pregnancies. Stepwise logistic regression of the six markers in group II provided an equation of possible clinical utility in differentiating abortion versus ectopic pregnancy in threatened gestations based on CA-125 and E2 levels.