Serum Relaxin Concentrations Research Articles

Plasma relaxin, estrogens and progestogens concentration in coldblooded and hot-blood mares in the second half of gestation

Monitoring estrogens, progestogens, and relaxin plasma concentration can be important for determining pregnancies at risk of failure in mares. However, significant breed-related differences in values of reproductive hormones are known, and data concerning coldblooded (CB) mares are missing. The aim of the study was to determine and compare serum relaxin, estrone sulphate (E1S), estradiol-17β (E2), and progestogens concentration in pregnant CB and hot-blood (HB) mares during the second half of gestation. Blood samples obtained from 94 healthy mares in the second half of gestation with known mating dates were analyzed. Samples were collected from 36 CB mares aged from 3 to 16 years and 58 HB mares aged from 4 to 17 years. The hormone concentrations were measured using immunoenzymatic equine species-specific commercial kits. The serum relaxin concentration was almost three times lower in CB, whereas E1S and E2 almost twice as low, as compared to HB mares (P < 0.05). In conclusion, the extremely low concentration of relaxin in CB mares could be one reason for the increased amounts of difficult parturition requiring veterinary intervention noted in these breeds.

Role of relaxin in diastasis of the pubic symphysis peripartum

BACKGROUNDSeparation of the pubic symphysis can occur during the peripartum period. Relaxin (RLX) is a hormone primarily secreted by the corpus luteum that can mediate hemodynamic changes during pregnancy as well as loosen the pelvic ligaments. However, it is unknown whether RLX is associated with peripartum pubic symphysis separation and if the association is affected by other factors.AIMTo study the association between RLX and peripartum pubic symphysis separation and evaluate other factors that might affect this association.METHODSWe performed a cross-sectional study of pregnant women between April 2019 and January 2020. Baseline demographic characteristics, including gestational age, weight, neonatal weight, delivery mode and duration of the first and second stages of labor, were recorded. The clinical symptoms were used as a screening index during pregnancy, and the patients with pubic symphysis and inguinal pain were examined by color Doppler ultrasonography to determine whether there was pubic symphysis separation. Serum RLX concentrations were evaluated 1 d after delivery using an enzyme-linked immunosorbent assay, and pubic symphysis separation was diagnosed based on postpartum X-ray examination. We used an independent-sample t test to analyze the association between serum RLX levels and peripartum pubic symphysis separation. Multivariate regression analysis was used to evaluate whether the association between RLX and peripartum pubic symphysis separation was confounded by other factors, and the association between RLX and the severity of pubic symphysis separation was also assessed. We used Pearson correlation analysis to determine the factors related to RLX levels as well as the correlation between the degree of pubic symphysis separation and activities of daily living (ADL) and pain.RESULTSA total of 54 women were enrolled in the study, with 15 exhibiting (observational group) and 39 not exhibiting (control group) peripartum pubic symphysis separation. There were no statistically significant differences in terms of maternal age, gestational age, pre-pregnancy weight, weight gain during pregnancy, delivery modes, or duration of the first or second stages of labor between the 2 groups. We did, however, note a statistically significant difference in serum RLX concentrations and neonatal weight between the observational and control groups (122.3 ± 0.7 µg/mL vs 170.4 ± 42.3 µg/mL, P < 0.05; 3676.000 ± 521.725 g vs 3379.487 ± 402.420 g, P < 0.05, respectively). Multivariate regression analyses showed that serum RLX level [odds ratio (OR): 1.022) and neonatal weight (OR: 1.002) were associated with pubic symphysis separation peripartum. The degree of separation of the pubic symphysis was negatively correlated with ADL and positively correlated with pain. There was no statistically significant association between serum RLX levels and the severity of pubic symphysis separation after adjusting for confounding factors.CONCLUSIONSerum RLX levels and neonatal weight were associated with the occurrence, but not the severity, of peripartum pubic symphysis separation.

RELAXIN AND IMMUNE FACTORS AS PREDICTORS OF BIOLOGICAL PREPARATION FOR LABOUR

Introduction. Biological preparedness for childbirth plays an important role in ensuring the normal course of spontaneous labour, as well as determining the criteria for preinduction and induction of labour with obstetrics pathologies. Recent studies have shown that labour involves a complex interaction between maternal and fetal factors that contribute to cervical maturation and myometrial contraction. In its turn it prompts the search for predictors that allow early identification of pathologies and improve the prognosis. The Relaxin hormone may function as one of the aforementioned predictors due to the emerging evidence for its involvement in the pathogenesis of abortion. Studies show that Relaxin plays a key role in the adaptation of a female 51 body by targeting the cervix among other organs. Relaxin acts on the cervix by degrading extracellular matrix components through activation of proteolytic enzymes, known as matrix metalloproteinases (MMPs). Remodeling of the cervix is a combination of endocrine and immune interactions. One of the hallmarks of cervix remodeling is infiltration of leukocytes prior to labour. These tissue granulocytes become the source of proinflammatory cytokines that upregulate MMPs. Relaxin controls the local inflammatory response by modulating matrix metalloproteinases. Thus, understanding the regulatory role of Relaxin in systemic production of cytokines and its effect on neutrophils at different stages of cervical maturation is of great interest. Aim: characterise the interplay between Relaxin, cytokines and their joint role in regulation of proteolytic enzymes to establish new criteria for prognosis of cervical maturation. Materials and methods. 69 pregnant women of gestational age 38-40 weeks were examined. The examined women were divided into 3 clinical groups, depending on the degree of cervix maturity at the time of hospitalisation. The degree of cervix maturity was assessed by the EH Bishop scale. Group I consisted of 23 patients with a mature cervix (9-13 points), group II included 21 pregnant women with an immature cervix (6-8 points), group III contained 25 pregnant women with a completely immature cervix (0-5 points). The control group consisted of 15 women of gestational age 35-36 weeks, who were pregnant for the first time. Women of the control group were examined prior to the start of physiological processes of remodeling of cervical tissues before labour and displayed no signs of premature labour. Control group was compared to women from the I, II and III groups by disease history and somatic data. All pregnant women underwent standardized clinical examination and immunological testing. Serum concentration of cytokines IL-6 and TNF-α, MMP-1 and MMP-9, and Relaxin levels were determined by enzyme-linked immunosorbent assay using commercial kits. Statistical analysis of the results was performed using the program "STATISTICA-6". Statistical significance was calculated by Student's t-test. Spearman's rank correlation coefficient was determined between the obtained parameters. The differences were considered accurate with a significance level of p&lt;0.05. Results. The average age of the examined pregnant women was 25 years 7 months (18-33). All patients of the examined groups could be compared to each other by their age, genital features and menstrual function (p ≤ 0.05). The study has shown that the lowest serum concentration of Relaxin was found in women with immature or completely immature cervix, which accounted to 189.7±34.6 pg / ml and 208, 9±27.6 pg / ml, respectively. This suggests that serum concentration of Relaxin could serve as a possible predictor of biological readiness of the body for labour. Furthermore, serum Relaxin concentration can serve as a prognostic marker of the effectiveness of induction and preinduction of labour. The data presented shows that women with mature cervix display maximum levels of matrix metalloproteinases MMP9 and MMP-1. Specifically, the concentration was 1.8 times higher than in the group of women with immature cervix. Thus, maturation of the cervix uterus involves a significant increase in the concentration of matrix metalloproteinases by peripheral neutrophils with a gradual increase in their proteolytic activity. Our study showed that high serum concentrations of the proinflammatory cytokines in pregnant women with a mature cervix before labour were higher compared to women with an immature or completely immature cervix. The interplay between proinflammatory cytokines and other modulators presented here during the preparation of the body for labour was evident from the observed correlation. We observed a strong correlation between the level of Relaxin and matrix metalloproteinases (r = 0, 78), as well as positive correlation between their content and the cytokines of interest. Conclusion. The study allowed to identify the most prognostically significant molecular predictors that characterize the body's preparation for labour, which include the "birth hormone" Relaxin. Furthermore, our analysis implicates immune mechanisms in regulating cervical maturation before labour.

Circulating pregnancy hormone relaxin as a first trimester biomarker for preeclampsia.

Preeclampsia, a multi-system hypertensive disorder, is associated with perturbations in the maternal cardiovascular system during early pregnancy. The corpus luteal hormone relaxin, a potent vasodilator, may contribute to physiological circulatory changes especially in early gestation when circulating levels are highest. This study investigated whether first trimester circulating relaxin may be a suitable biomarker for the early prediction of preeclampsia. Relaxin was initially measured in first-trimester samples of women who developed late-onset preeclamptic (LO-PE; delivery≥34weeks; n=33) and uncomplicated pregnancies (n=25) in Pittsburgh, USA. Subsequently, to expand the group numbers, relaxin was measured in women who developed LO-PE (n=95), early-onset preeclamptic (EO-PE; delivery<34weeks; n=57), and uncomplicated pregnancies (n=469) in Utrecht, the Netherlands. In the Pittsburgh subjects, low relaxin levels (lowest centile: <p10) showed an adjusted odds ratio (OR) of 5.29 (95%CI 1.10-25.5) for LO-PE. In the Utrecht population, low relaxin levels (<p10) demonstrated adjusted ORs of 1.45 (95%CI 0.54-3.90) and 2.03 (95%CI 1.06-3.88) for EO-PE and LO-PE respectively, the latter increasing to an adjusted OR of 3.18 (95%CI 1.41-7.20) when newborn weight was<10%. Serum relaxin concentrations slightly improved the detection rate of a previously derived prediction model for LO-PE from 42.5% to 45.1% at a fixed 10% false-positive rate. Relaxin shows little improvement in the performance of first trimester prediction models, which does not support its clinical implementation as a biomarker. Although this study was only correlational, the results point to a possible pathophysiologic role for low relaxin levels in pregnancies that later develop LO-PE.

EVALUATION OF SERUM RELAXIN CONCENTRATIONS AND KNEE VALGUS AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Background:Athletes who sustain an anterior cruciate ligament (ACL) injury are more likely to develop adverse health outcomes, such as knee osteoarthritis, knee pain, and obesity. It is assumed that the long-term consequences of ACL reconstruction are caused by the reconstruction itself. Studies have observed that relaxin, a peptide hormone similar in structure to insulin, interferes with the structural integrity of the ACL and elicits long term effects on bone, joint, muscle, and tendon health. Given the known effects of relaxin, it is reasonable to wonder if relaxin contributes to the development of these long-term health outcomes, independently of the ACL injury.Hypothesis/Purpose:The purpose of this study was to evaluate knee valgus and serum relaxin concentrations (SRC) in athletes who have and have not sustained an ACL injury. It was hypothesized that athletes who previously tore their ACL would have higher SRC and more knee valgus than those who were injury free.Methods:Twenty-two female athletes participated. Participants were assigned to one of two groups: ACL injury (6.0 ± 3.3 years after surgery, N = 4) and injury free (N = 18). Kinematic data were collected at 100 Hz using The MotionMonitor. Participants performed a single leg squat (SLS), single leg crossover dropdown (SCD), and drop vertical jump (DVJ) at two different time points in their menstrual period: pre-ovulatory phase and mid-luteal phase. Blood samples were collected when SRC are measurable (mid-luteal phase), and SRC were determined using a Quantikine Human Relaxin-2 Immunoassay.Results:Independent samples t-tests revealed significant differences between those who tore their ACL and those who were injury free in SRC and knee valgus during the SLS in the mid luteal phase, DVJ in both phases, and SCD in both phases. Specifically, the participants who tore their ACL had significantly higher SRC and more knee valgus than those who did not tear their ACL.Conclusion:These findings suggest that a previous ACL injury could place one at an increased risk of re-tear and other adverse effects on their joints, muscles, and tendons. Thus, further investigating hormonal risk factors during long term monitoring of recovery is needed.

The Relationship between Serum Relaxin Concentrations and Knee Valgus.

Female athletes are at an elevated risk for tearing their anterior cruciate ligament, compared to their male counterparts. Though injury screening clinical tests and neuromuscular training programs have been widely implemented, injury rates remain high among female athletes. The purpose of this study was to examine the relationship between serum relaxin concentrations and knee valgus during three clinical tests (single leg squat, drop vertical jump, and single leg crossover dropdown). Twenty-two female athletes volunteered. Participants were scheduled for collection during the mid-luteal phase, when serum relaxin concentrations are known to be measurable. Blood samples were collected, and serum relaxin concentrations were quantified. Kinematic data were collected while participants performed the three clinical tests. Regression analyses revealed statistically significant relationships between serum relaxin concentrations and knee valgus throughout all tests. These findings suggest that serum relaxin concentrations and knee valgus are not independent of each other and more holistic approaches may be necessary to truly map out the risk for injury and ultimately reduce the rate of anterior cruciate ligament injuries. Thus, concluding that knee valgus, a highly utilized modifiable biomechanical risk factor, and relaxin, a hormone that has been associated with anterior cruciate ligament injury in female athletes, are related to each other.

Preliminary Evaluation of Dynamic Knee Valgus and Serum Relaxin Concentrations After ACL Reconstruction.

Background:Athletes who have sustained a tear of the anterior cruciate ligament (ACL) are at a greater risk of re-tear and of developing other adverse outcomes, such as knee osteoarthritis, compared with uninjured athletes. Relaxin, a peptide hormone similar in structure to insulin, has been shown to interfere with the structural integrity of the ACL in female individuals. The purpose of the present study was to evaluate dynamic knee valgus and the serum relaxin concentration (SRC) in athletes who had previously sustained a torn ACL and in those who had not.Methods:The study included 22 female athletes, divided into 2 groups: those who had previously sustained a torn ACL (4 participants; torn ACL in the dominant leg in all cases) and those who had not (18 participants). Kinematic data were collected at 100 Hz. To assess dynamic knee valgus, participants performed a single-leg squat, a single-leg crossover dropdown, and a drop vertical jump at 2 time points in the menstrual cycle of the patient, pre-ovulatory and mid-luteal. SRC was determined with use of the Human Relaxin-2 Immunoassay using a blood sample obtained during the mid-luteal phase of the menstrual cycle.Results:Independent samples t tests were utilized to compare the differences in dynamic knee valgus and SRC between groups. For the single-leg squat, participants with a prior torn ACL were found to have significantly higher dynamic knee valgus at the mid-luteal phase but not at the pre-ovulatory phase. For the drop vertical jump and single-leg crossover dropdown, participants with a prior torn ACL were found to have significantly higher dynamic knee valgus at both the pre-ovulatory and mid-luteal phases. SRC was also significantly higher among participants with a prior torn ACL.Conclusions:Participants who had previously sustained a torn ACL had higher SRC and more dynamic knee valgus compared with those who had not. Further investigation of the effects of hormones as a risk factor for reinjury in participants with a prior ACL tear may be worthwhile. In addition, it may be worth monitoring hormonal and biomechanical properties in athletes during the long-term recovery from ACL reconstruction.Level of Evidence:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Optimal Paradigms for Measuring Peak Serum Relaxin in Eumenorrheic, Active Females

Sex disparity in anterior cruciate ligament injury is multifactorial. Sex hormones, such as relaxin, may play a role in the increased risk of injury in female athletes. In order to fully investigate this relationship, optimal strategies for capturing serum relaxin concentration across the menstrual cycle must be determined. The aim of this study was to describe the variability in the timing and magnitude of relaxin concentration changes across the menstrual cycle.

The Intracellular Effect of Relaxin on Female Anterior Cruciate Ligament Cells

Background: Female collegiate athletes with serum relaxin concentrations above 6.0 pg/mL have been shown to have more than 4 times increased risk for anterior cruciate ligament (ACL) tears. However, the intracellular effect of relaxin on ACL cells has not been elucidated. Hypotheses: The hypotheses were that relaxin binding to receptors on female ACL cells will result in (1) an increase in matrix metalloproteinase (MMP) and decrease in tissue inhibitor of metalloproteinase (TIMP) gene expression, (2) a decrease in collagen and alpha smooth muscle actin (αSMA) expression, (3) inhibition of transforming growth factor β1 (TGFβ1)–induced fibrosis, and (4) an increase in cyclic adenosine 3′,5′-monophosphate (cAMP) production and that these changes will not be observed in male ACL cells. Study Design: Controlled laboratory study. Methods: Ligament cells from ACL tissue were isolated from 7 male and 7 female human donors and expanded in vitro. The cells were incubated with escalating concentrations of relaxin-2, as well as with TGFβ1 or 17β-estradiol in certain groups. Cells were then lysed and analyzed for MMP1 (collagenase-1), MMP3 (stromelysin-1), MMP13 (collagenase-3), TIMP1, type I collagen, type III collagen, and/or αSMA mRNA expression using quantitative real-time polymerase chain reaction. Intracellular cAMP levels were assessed via an enzyme-linked immunoassay. Results: ACL cells primed with estrogen and treated with 10 ng/mL and 100 ng/mL relaxin illustrated increased MMP1 expression (P = .012 and .006, respectively) and MMP3 expression (P = .005 and .001, respectively). Treatment with 100 ng/mL relaxin decreased αSMA expression (P = .001). When ACL tissue isolated from female donors with a history of oral contraceptive use was excluded from the analysis, 100 ng/mL of relaxin decreased type I collagen (P = .005) and type III collagen (P = .028) expression in cells primed with estrogen. Relaxin exhibited no significant effect on male-derived ACL cells. Conclusion: Relaxin-2 significantly upregulated intracellular processes in human female ACL cells, but no effect was observed in male cells. Relaxin increased MMP (MMP1 and MMP3) and decreased αSMA and type I and III collagen expression, which may act to alter the structural integrity of the ACL tissue over time. Clinical Relevance: Female athletes with higher circulating relaxin levels may be more susceptible to ACL injury.

Association Between Serum Relaxin and Subsequent Shoulder Instability.

Ligamentous laxity correlates with shoulder instability. Relaxin is a hormone that has been linked to laxity in the knee and has been shown to be a risk factor for anterior cruciate ligament (ACL) injury. This study prospectively evaluated the association between relaxin and acute shoulder instability. A prospective cohort study of 1050 young athletes was performed between 2006 and 2010. The authors conducted a nested case-control analysis within this cohort to evaluate the association between preinjury serum relaxin concentration and the likelihood of subsequent shoulder instability. The study compared 53 patients who had shoulder instability and 53 control subjects who were matched for sex, age, height, and weight. The serum relaxin concentration in preinjury baseline samples was tested with enzyme-linked immunosorbent assay analysis in duplicate. Independent t tests were performed to identify differences in mean serum relaxin concentration between patients with shoulder instability and uninjured control subjects. Logistic regression was used to evaluate whether preinjury baseline serum relaxin concentration was associated with the subsequent likelihood of shoulder instability. Of the 53 patients with instability, 13 (25%) had a detectable serum relaxin concentration compared with 9 (17%) of uninjured control subjects (P=.34). Mean serum relaxin concentration in the injury group was 3.69±1.78 pg/mL and 2.20±0.97 pg/mL in uninjured control subjects (P=.02). Increased serum relaxin concentration was associated with the subsequent likelihood of acute shoulder instability. Subjects were 2.18 times (odds ratio, 2.18; 95% confidence interval, 1.01-4.76) more likely to have acute shoulder instability during the follow-up period for every 1-pg/mL increase in serum relaxin concentration at baseline. The findings suggest that serum relaxin concentration is associated with a risk of subsequent shoulder instability in young athletes. Further research on the role of relaxin in shoulder instability is warranted. [Orthopedics. 2016; 39(4):e724-e728.].

Diagnostic and predictive biomarkers for pre-eclampsia in patients with established hypertension and chronic kidney disease

Women with chronic kidney disease (CKD) and chronic hypertension (CHT) frequently develop superimposed pre-eclampsia, but distinction from pre-existing disease is challenging. Plasma placental growth factor (PlGF), B-type natriuretic peptide (BNP), neutrophil gelatinase-associated lipocalin (NGAL), and serum relaxin concentrations were quantified in a longitudinal prospective cohort of 121 women with CKD: 44 with chronic hypertension, and 79 healthy controls. Biomarker concentrations were compared with 32 women with pre-eclampsia without pre-existing disease. Test performance was evaluated for diagnosis of superimposed pre-eclampsia requiring delivery within 14days of sampling. PlGF was evaluated as a promising marker in a validation cohort of women with suspected pre-eclampsia (29 with CKD; 94 with chronic hypertension; 29 with superimposed pre-eclampsia requiring delivery within 14 days) and compared with women without pre-existing disease (290 with no pre-eclampsia and 176 with pre-eclampsia requiring delivery within 14 days). From 20and up to 42 weeks of gestation, lower maternal PlGFconcentrations had high diagnostic accuracy for superimposed pre-eclampsia requiring delivery within 14days (receiver operator characteristic 0.85) and confirmed in the validation cohort. The other plasma and serum biomarkers were not discriminatory. Thus, plasma PlGF concentrations could potentially help guide clinical decision making regarding admission and delivery for superimposed pre-eclampsia.

Physical fitness, serum relaxin and duration of gestation.

BackgroundWomen are recommended to perform regular exercise during pregnancy but the impact of physical fitness on duration of gestation and miscarriage is inconsistent. In addition, a dose-response relation between the amount of weekly exercise and increased risk of miscarriage in early pregnancy has been observed. Previous studies have mostly used an epidemiologic method. Larger studies using careful measurement of physical fitness are needed. Besides physical fitness, maternal circulating concentrations of the hormone relaxin have been associated with decreased duration of gestation.MethodsA prospective cohort including 20 women with miscarriage and 460 women with spontaneous onset of labour, recruited from maternal health care centres in central Sweden, were examined in early pregnancy regarding estimated absolute peak oxygen uptake ( dot{V}{O}_2 peak, est.) by cycle ergometer test, and maternal circulating serum relaxin concentrations.ResultsWomen with miscarriage displayed the highest level of absolute dot{V}{O}_2 peak, est. (2.61 l/min) and the lowest serum relaxin concentrations (640 ng/l). Among women with spontaneous onset of labour, the mean absolute dot{V}{O}_2 peak, est. increased successively from the lowest estimated oxygen uptake of 2.31 l/min among those with preterm birth (n = 28), to an oxygen uptake of 2.49 l/min among women with postterm birth (n = 31). An opposite trend was shown regarding serum relaxin concentrations from women with miscarriage to those with postterm birth. Serum relaxin concentrations, but not absolute dot{V}{O}_2 peak, est. was significantly and independently associated with duration of gestation in women with miscarriages, and absolute dot{V}{O}_2 peak, est., age and multiple pregnancy were independently associated with duration of gestation in women with spontaneous onset of labour.ConclusionsPhysical fitness appears to be a protective factor of established pregnancies and not significantly involved in the risk of early miscarriage. Additional studies are needed to more clearly define the role of relaxin in miscarriage.

Abstract T P249: Upregulation of Relaxin After Experimental Subarachnoid Hemorrhage

Background and Purpose: Relaxin is a pregnancy hormone which exerts vasodilatory effects by activating nitric oxide synthase and matrix metalloproteinases through receptor (RXFP1). Recently, this vasodilatory effect has been considered useful as a potential therapeutic target in acute heart failure. However, the role of relaxin in the cerebral artery has not been fully explored. In this study, we investigated the role of relaxin in rabbit basilar artery (BA) after subarachnoid hemorrhage (SAH). Methods: Basilar arteries were collected from a rabbit SAH model on days 3, 5, and 7 after SAH. Total RNA was extracted from the BA and a cDNA microarray containing 43,623 genes was performed. The expression of relaxin and RXFP1 mRNA was investigated by quantitative RT-PCR. Serum and cerebrospinal fluid (CSF) relaxin concentrations were measured by ELISA. Perfusion fixation was performed on days 0, 3, 5 and 7, and the localization of RXFP-1 in the BA was examined using immunohistochemistry. Results: The expression of relaxin mRNA was significantly up-regulated on days 5 and 7 compared to the control sample. The expression of RXFP1 mRNA was significantly down-regulated on day 3 and sustained on day 7. The serum relaxin concentration in the rabbit SAH model was not significantly changed after SAH, whereas the CSF relaxin concentration was significantly elevated on days 5 and 7. Immunohistochemistry revealed strong RXFP1 staining in media of the BA on day 0, and showed weak staining on days 3, 5 and 7. Conclusions: Relaxin expression in the BA and relaxin concentration in the CSF increase after SAH, and considerably, relaxin expression is negatively correlated with the RXFP1 expression in the rabbit BA after SAH.

The effects of aglepristone alone and in combination with cloprostenol on hormonal values during termination of mid-term pregnancy in bitches

This study was designed to assess endocrine changes associated with termination of mid-term pregnancy after use of two different protocols. For this purpose we compared the effects of aglepristone (AGL) alone and in combination with cloprostenol (CLO) on serum concentrations of progesterone (P4), estradiol (E2) and relaxin (RLN) measured at short-term intervals during the abortion period in bitches. Fourteen pregnant bitches between day 25 and 32 of gestation were used in the study. In the AGL group (n=7), aglepristone was administered solely (10mg/kg body weight (BW), subcutaneously, once daily on two consecutive days) whereas in the AGL-CLO group (n=7), aglepristone (dosage as in AGL group) and cloprostenol (1μg/kg BW, subcutaneously, same with aglepristone) were combined. All pregnancies were successfully terminated 5.2±1.6 days after initiation of treatments, which was significant in both groups (P>0.05). At the time of the start of abortion (SA) and the end of abortion (EA), the mean P4 concentrations were 26.6±7.3 and 12.0±6.4ng/ml in AGL group, and 2.7±0.7 and 0.9±0.1ng/ml, in AGL-CLO group, respectively (P<0.01). Serum E2 concentrations were significantly higher (P<0.05) in AGL group at 42, 48, 54h and SA after initiation of treatment. In the AGL-CLO group, serum RLN concentrations did not significantly change from the initiation of treatment to EA (P>0.05). However, markedly higher RLN concentrations (P<0.05) were observed in the AGL group at 48h (1.5±0.7ng/ml) and at SA (1.6±0.5ng/ml). The results of the present study indicate that changes in the hormonal concentrations affect the mechanism of abortion in different ways. Further in depth studies investigating changes in the expression of hormone receptors inside the ovary, endometrium and placenta might be helpful to our understanding of the endocrinological differences observed in this study.

Prospective Correlation Between Serum Relaxin Concentration and Anterior Cruciate Ligament Tears Among Elite Collegiate Female Athletes

Background: The female anterior cruciate ligament may be more susceptible to injury than the male anterior cruciate ligament because of the gender-specific expression of receptors for relaxin, a collagenolytic hormone that promotes remodeling of the anterior cruciate ligament. Purpose: This study was undertaken to investigate whether collegiate female athletes with elevated serum relaxin concentrations (SRC) sustain anterior cruciate ligament tears at an increased rate compared with those with lower SRC. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: From 2005 to 2010, 143 Division I female athletes from 2 universities participating in sports at high risk for anterior cruciate ligament tears (basketball, lacrosse, field hockey, soccer, gymnastics, and volleyball) were recruited to participate. Questionnaires and urine luteinizing hormone (LH) tests were used to determine participants’ anterior cruciate ligament injury and menstrual history and to identify their mid-luteal phase or projected cycle days 21 to 24. Serum samples were obtained for progesterone and relaxin ELISA (enzyme-linked immunosorbent assay) analysis. Participants were monitored for anterior cruciate ligament injury over their 4-year National Collegiate Athletic Association athletic career. Results: A total of 128 participants completed the study and were eligible for data analysis. The cumulative incidence of complete anterior cruciate ligament tear over the 4-year study period was 21.9%, and varied significantly by sport (P < .001). The mean SRC for athletes with anterior cruciate ligament tears (6.0 ± 8.1 pg/mL) was significantly higher than that for those without anterior cruciate ligament tears (1.8 ± 3.4 pg/mL; P = .013). In subgroup analysis of the 46 athletes who had detectable SRC, the cumulative incidence of anterior cruciate ligament tear was 14 of 46 (30.4%); the mean SRC among athletes with anterior cruciate ligament tears (14 of 46) was 12.1 ± 7.7 pg/mL and without anterior cruciate ligament tears (32 of 46), 5.7 ± 3.6 pg/mL (P = .002). When 6.0 pg/mL was set as the SRC cutoff for screening athletes for risk of anterior cruciate ligament tear in the subgroup with detectable relaxin levels, the test had 71% sensitivity, 69% specificity, 52% positive predictive value, 88% negative predictive value, and a relative risk of 4.4. These values were significant by χ2 test (P = .003) and receiver operating characteristic analysis (P = .002). Conclusion: Elite female athletes with anterior cruciate ligament tears have higher SRC than those without tears. Those with an SRC greater than 6.0 pg/mL had over 4 times increased risk for a tear. Clinical Relevance: Females with higher serum relaxin levels may be at increased risk for anterior cruciate ligament tears. Further investigation of the clinical utility of SRC testing is warranted.

Trends in serum relaxin concentration among elite collegiate female athletes

Purpose:This study was designed to investigate the relationship between serum relaxin concentration (SRC) and menstrual history and hormonal contraceptive use among elite collegiate female athletes. Evaluation of SRC in athletes is necessary, because relaxin has been associated with increased knee joint laxity and decreased anterior cruciate ligament (ACL) strength in animal models.Methods:National Collegiate Athletic Association Division I female athletes participating in sports at high risk for ACL tears – basketball, field hockey, gymnastics, lacrosse, soccer, and volleyball – were invited to participate. All participants completed a questionnaire about their menstrual history and hormonal contraceptive use. Venipuncture was performed to obtain samples of serum progesterone and relaxin. Samples were obtained during the mid-luteal phase from ovulating participants, and between the actual or projected cycle days 21 to 24, from anovulatory participants. Serum concentration of relaxin and progesterone was determined by ELISA and the data were analyzed using SPSS statistical software with significance set at P = 0.05.Results:169 female athletes participated. The mean SRC among all participants was 3.08 ± 6.66 pg/mL). The mean SRC differed significantly between those participants using hormonal contraceptives (1.41 pg/mL) and those not using hormonal contraceptives (3.08 pg/mL, P = 0.002). Mean SRC was lowest among amenorrheic participants (1.02 pg/mL) and highest among oligomenorrheic participants (3.71 pg/mL) and eumenorrheic participants (3.06 pg/mL); these differences were not significant (P = 0.53). Mean serum progesterone concentration (SPC) differed significantly between those participants using hormonal contraceptives (2.80 ng/mL), and those not using hormonal contraceptives (6.99 ng/mL, P < 0.0001).Conclusions:There is a positive correlation between serum progesterone and SRC and an attenuation of SRC with hormonal contraceptive use. Our results underscore the significant role that hormonal contraceptives can play in decreasing relaxin levels, if future investigations establish a link between relaxin levels and ligamentous injury among female athletes.

The effect of infertility and assisted reproduction on first-trimester placental and fetal development

Our investigation of differences in first-trimester placentation and/or fetal biometry in pregnancies conceived spontaneously compared with those conceived through fertility treatment, and comparing less invasive fertility treatment with in vitro fertilization found no statistically significant difference in first-trimester abnormal placentation or fetal growth between pregnancies conceived spontaneously and those conceived through fertility treatment, or between the in vivo and in vitro subgroups.

Time-resolved fluoroimmunoassay (TR-FIA) of porcine relaxin.

We developed and validated a new assay system for porcine relaxin that overcame the drawbacks of RIA by adapting time-resolved fluoroimmunoassay (TR-FIA), which was recently introduced as a non-RIA format. The assay system was a solid-phase TR-FIA based on competition for a polyclonal anti-porcine relaxin antibody between europium (Eu)-labeled porcine relaxin and test samples. Antibody-relaxin complexes were then bound to the second antibody coated on the solid phase, achieving rapid and complete separation of bound and free antigen. A standard curve was produced over the range of 1 pg/well to 1000 pg/well. Serum and corpus luteum extracts from pigs in late pregnancy exhibited inhibition curves parallel to that of the relaxin standard, whereas male pig serum caused no displacement of the labeled hormone. No cross-reactivity was seen with other hormones, such as insulin, LH, and FSH, indicating a high specificity of the assay. The sensitivity was 4 pg/well (80 pg/ml), which was high and equivalent to that of the porcine relaxin RIA. The intra-assay and inter-assay coefficients of variation were less than 3.8% and 6.7%, respectively. Recovery of porcine relaxin added to male pig serum sample averaged 103%. The advantages of this TR-FIA were that addition of tyrosine was not necessary for labeling, unlike the RIA, Eu-labeled relaxin was stable enough to allow long-term storage for more than one year, the assay was completed in only 5 h versus two to seven days for the RIA, and no special safety precautions were needed. To validate this TR-FIA, the serum relaxin concentrations during late pregnancy, parturition and early lactation were investigated in pigs. Serum relaxin levels determined by this assay were similar to those obtained previously by RIA. In conclusion, this TR-FIA could replace RIA as the method of choice for assay of relaxin.

166 POTENTIAL OF URINARY RELAXIN AS A USEFUL INDICATOR OF PREGNANCY IN THE MANED WOLF

The maned wolf (Chrysocyon brachyurus), a neotropical canid, lives in habitats severely compromised by agricultural development. Therefore, maintaining a healthy and viable zoo population is crucial, because it serves as hedge against extinction. However, the North American ex situ population of maned wolves is far from self-sustaining, mainly due to low pregnancy success and high neonatal mortality. Currently, there is no non-invasive way to determine pregnancy in this species. Therefore, the goal is to determine whether urinary relaxin can be used as an indicator of pregnancy in this species. Objectives were to (1) determine the relationship between serum and urinary relaxin in canids, using pregnant domestic bitches as a model, and (2) evaluate the patterns of urinary relaxin in pregnant v. non-pregnant female maned wolves. Serum and urine samples were obtained weekly from six pregnant domestic bitches starting from the day of natural breeding until 3 weeks before the estimated whelping dates. For the maned wolf, urine and feces were obtained weekly during a breeding season (October to February) from six females, three of which were pregnant and gave birth. Concentrations of serum and urinary relaxin were measured using the double antibody canine relaxin radioimmunoassay (Steinetz et al. 1996 Biol. Reprod. 54, 1252–1260). Fecal progestagen were determined using an enzyme immunoassay (Songsasen et al. 2006 Theriogenology 66, 1743–1750). The relationship between serum and urinary relaxin concentrations was determined using the Pearson Product Moment Correlation Analysis. The relationship between urinary relaxin concentrations and days before whelping (for pregnant females) or time after the initial rise of progestagen for each individual were determined using a linear regression analysis. Serial dilutions of pooled dog urine produced displacement curves parallel to those of the appropriate synthetic canine relaxin standards, while wolf samples showed limited parallelism with low concentration of immunoactive antigen. Concentrations of urinary relaxin were significantly correlated with the serum counterpart in pregnant dogs (P &lt; 0.01, r2 0.58). In pregnant maned wolves, relaxin level increased two- to six-fold as gestation progressed (P &lt; 0.05, r2 ranged from 0.15 to 0.56). In contrast, urinary relaxin remained at the baseline in non-pregnant females throughout the diestrus period (P &gt; 0.05). In conclusion, our findings suggest that urinary relaxin mirrors serum relaxin during pregnancy in domestic bitches and may have potential as a tool to diagnose pregnancy in the maned wolf. Further studies are required to improve the specificity and sensitivity of this non-invasive assay.

Mid‐trimester serum relaxin concentrations and post‐partum pelvic floor dysfunction

To compare mid-trimester serum relaxin concentration (SRC) in primiparous women with or without pelvic floor dysfunction (PFD--stress urinary incontinence (SUI), genital prolapse). Nested observational cohort study. Urogynecology clinic of affiliated University hospital. Primiparous women one to four years post-partum, who had, at time of index pregnancy, participated in a prospective observational study looking at mid-trimester serum relaxin and preterm delivery. Relaxin had been obtained during the index pregnancy at 24 and 28 weeks. Primiparous women who had not given birth to a subsequent child were contacted and asked to return for a single visit assessing pelvic floor function. Pelvic Organ Prolapse Quantification system (POPQ) and Urogenital Distress Inventory (UDI-6). Fifty women participated, of whom 40 delivered vaginally. Seventeen (34%) women had prolapse and 23 (46%) had stress incontinence. Relaxin was slightly higher (not significantly) in women with PFD than in those without. Relaxin concentration declined significantly more rapidly from 24 to 28 weeks in incontinent women, after adjusting for baseline and obstetrical factors. In contrast to previous reports, mid-gestation relaxin tended to be higher and fall significantly faster in women with PFD. Acknowledging relaxin's effects on collagen turnover, our findings explore the association between childbirth and PFD.