Progesterone Immunoassays Research Articles

Assessment of a non-invasive approach to pregnancy diagnosis in gray whales through drone-based photogrammetry and faecal hormone analysis.

Knowledge of baleen whales' reproductive physiology is limited and requires long-term individual-based studies and innovative tools. We used 6 years of individual-level data on the Pacific Coast Feeding Group gray whales to evaluate the utility of faecal progesterone immunoassays and drone-based photogrammetry for pregnancy diagnosis. We explored the variability in faecal progesterone metabolites and body morphology relative to observed reproductive status and estimated the pregnancy probability for mature females of unknown reproductive status using normal mixture models. Individual females had higher faecal progesterone concentrations when pregnant than when presumed non-pregnant. Yet, at the population level, high overlap and variability in progesterone metabolite concentrations occurred between pregnant and non-pregnant groups, limiting this metric for accurate pregnancy diagnosis in gray whales. Alternatively, body width at 50% of the total body length (W50) correctly discriminated pregnant from non-pregnant females at individual and population levels, with high accuracy. Application of the model using W50 metric to mature females of unknown pregnancy status identified eight additional pregnancies with high confidence. Our findings highlight the utility of drone-based photogrammetry to non-invasively diagnose pregnancy in this group of gray whales, and the potential for improved data on reproductive rates for population management of baleen whales generally.

Design and Validation of a Sensitive Multisteroid LC-MS/MS Assay for the Routine Clinical Use: One-Step Sample Preparation with Phospholipid Removal and Comparison to Immunoassays.

Steroid analysis in clinical laboratories is dominated by immunoassays (IAs) that have a high sample turnover but are inherently limited in trueness, precision, and sensitivity. Liquid chromatography coupled to mass spectrometry (LC-MS/MS) has proved to be a far more capable tool, delivering better sensitivity, specificity, and the possibility of parallel analysis of multiple steroids and metabolites, providing the endocrinologist with more reliable and comprehensive diagnostic information. An LC-MS/MS assay with gradient elution over less than eight minutes and a one-step sample preparation combining protein precipitation with phospholipid removal of off-line solid-phase extraction was developed and validated. It allowed the quantification of 11-deoxycorticosterone (11-DOC), 11-deoxycortisol (11-DF), 17-OH-progesterone (17P), 21-deoxycortisol (21-DF), androstenedione (ANDRO), aldosterone (ALDO), corticosterone (CC), cortisol (CL), cortisone (CN), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), dihydrotestosterone (DHT), estradiol (E2), progesterone (PROG), and testosterone (TES) in human serum. Interday imprecision was generally better than 15%, trueness was proven by recovery experiments with ISO 17034-certified reference materials, proficiency testing (UK NEQAS), and measuring serum reference standards. In-house comparison against IVD-CE-certified immunoassays (IA) for 17P, ANDRO, CL, DHEAS, E2, PROG, and TES was conducted by assessing leftover routine patient samples and purpose-built patient serum pools. None of the compared routine IAs were meeting the standards of the LC-MS/MS. Insufficient overall comparability was found for ANDRO and 17P (mean bias > +65%). Accuracy limitations at lower concentrations were present in IAs for PROG, E2, and TES.

Analytical and clinical performance of a fluorescence enzyme immunoassay for progesterone and determination of ovulation day in bitches.

We evaluated the performance of a third-generation fluorescence enzyme immunoassay kit (FEIA; Tosoh Bioscience) for progesterone (P4) measurement in canine serum to identify the day of luteinizing hormone (LH) peak and ovulation in bitches. We conducted P4 assays on 54 serum samples using a FEIA and a chemiluminescence immunoassay (CLIA; Siemens). For the FEIA kit, the linearity test, recovery test, inter- and intra-assay CVs, and total error observed (TEo) were calculated. Serum samples from 28 bitches were used to evaluate the association of P4 concentration with the day of LH peak and the day of ovulation based on P4 thresholds (P4 ≥ 2 ng/mL, and doubling at 4-8 ng/mL in the following 48 h), and with pregnancy length. Linearity was 75-97% and 86-94% for high (37.0 ng/mL) and medium (3.8 ng/mL) pool serum samples, respectively. Recovery was 86.4-119%. Intra-assay CVs were 2.6%, 3.3%, and 5.2% for low (0.23 ng/mL), medium (6.24 ng/mL), and high (38.3 ng/mL) pool concentrations. Inter-assay CVs were 2.22% and 2.53% for P4 concentrations of 2.70 ng/mL and 8.2 ng/mL, respectively. TEo was 8.72% and 22.7% for P4 concentrations of 2 and 8 ng/mL, respectively. The mean pregnancy length from the day of LH peak and ovulation were 64.6 ± 1.7 and 63.3 ± 1.1 d, respectively. The third-generation FEIA kit that we tested was highly reliable.

P-615 Lack of analytical interference of dydrogesterone in progesterone immuno-assays: a multi-laboratory spike and recovery study of widespread used assays

Abstract Study question Does dydrogesterone (DYD) and its active metabolite 20-α-dihydrodydrogesterone (DHD) interfere with routinely used progesterone assays? Summary answer This multi-laboratory spike-and-recovery study does not indicate any relevant interference of DYD/DHD within routinely used progesterone assays. What is known already Progesterone (P4), a sex steroid, is measured in serum or plasma by competitive immunoassay or Liquid Chromatography mass spectrometry (LC-MS) in a variety of clinical contexts. One potential limitation of steroid hormone immunoassays is interference caused by compounds with structural similarity to the target steroid of the assay. Dydrogesterone, an orally active close stereoisomer of progesterone, is used for various indications in women’s health, including luteal phase support. To date, the potential interference of DYD/DHD with P4 immunoassays has not systematically been studied. Study design, size, duration The present systematic in-vitro study investigated potential interferences of DYD/DHD in seven widely used, commercially available P4 immunoassays and a LC-MS method over a range of concentrations of DYD/DHD and P4. The study was performed in collaboration with participants in the endocrine section of the Dutch foundation for quality assessments in medical laboratories. For each assay method, each laboratory received a set of nine blinded human plasma samples (containing different P4 and/or DYD/DHD concentrations). Participants/materials, setting, methods Routine human plasma samples were anonymized and pooled to create three graded concentration levels of progesterone (P4 high, P4 medium, P4 low). Each pooled P4 plasma sample (6-7 ml) was spiked at high, medium and “none” DYD/DHD concentration and was divided into 0.5 ml aliquots. The blinded aliquots were analyzed by seven different laboratories with their routine progesterone assay (six different immunoassays and LC-MS assay, respectively). Main results and the role of chance High, medium, and low P4 samples had concentrations of approximately 60 nmol/l progesterone, 20 nmol/l progesterone and <10 nmol/l (male plasma), respectively. The immuno- assays tested were Immulite 200XPI (Siemens Healthineers), Advia Centaur (Siemens Healthineers), Atellica (Siemens Healthineers), Architect I2000 (Abbott Diagnostics), Cobas 8000 (Roche Diagnostics), UniCel DxI 800 (Beckman-Coulter) and LC-MS (Agilent). The sample recovery rate (P4 result obtained by the assays tested for sample spiked with DYD/DHD, divided by the result obtained for the corresponding sample with no DYD/DHD x 100) was within a +/-10% window for the medium P4 and high P4 concentrations, but more variable for the low P4 samples. The latter is, however, attributable to high inter- and intra-method variability, especially at low P4 concentrations. The P4 plasma concentrations generally showed considerable inter-assay variability at each concentration level, with Immunlite 2000 at the lower end and Cobas 8000/801 and Dxi at the higher end of the reported results for the High and Medium P4 samples as compared to LC-MS. The study confirms the inherent method variability of P4 immunoassays casting doubts on the clinical use of P4 cut-offs to guide clinical management, especially at low concentrations. Limitations, reasons for caution Only one sample per concentration level was provided to the laboratories which didn't allow for a systematic quantification of intra-method variability. The concentrations of DYD/DHD haven't been verified by means of a validated bioanalytical method. Measurement of DYD and DHD is to date only feasible by a highly-selective LC-MS method. Wider implications of the findings The present study is strongly indicative that relevant interference of DYD/DHD does not exist. This finding implies that a clinician can reliably distinguish P4 concentrations from DYD/DHD concentrations in a blood sample within a routine care-setting. Trial registration number not applicable

Lack of analytical interference of dydrogesterone in progesterone immunoassays

Progesterone, a sex steroid, is measured in serum by immunoassay in a variety of clinical contexts. One potential limitation of steroid hormone immunoassays is interference caused by compounds with structural similarity to the target steroid of the assay. Dydrogesterone (DYD), an orally active stereoisomer of progesterone, is used for various indications in women's health. Herein, we report a systematic in vitro investigation of potential interference of DYD and its active metabolite 20α-dihydrodydrogesterone (DHD) in seven widely used, commercially available progesterone assays. Routine human plasma samples were anonymized and pooled to create three graded concentration levels of progesterone (P4 high, P4 medium, P4 low). Each pooled P4 plasma sample (6-7mL) was spiked at high, medium, and "none" concentration with DYD/DHD and was divided into 0.5mL aliquots. The blinded aliquots were analyzed by seven different laboratories with their routine progesterone assay (six different immunoassays and one liquid chromatography-tandem mass spectrometry assay, respectively) within the Dutch working group on endocrine laboratory diagnostics of the Dutch Foundation for Quality Assessments in Medical Laboratories. The sample recovery rate (P4 result obtained for sample spiked with DYD/DHD, divided by the result obtained for the corresponding sample with no DYD/DHD × 100) was within a ±10% window for the medium and high P4 concentrations, but more variable for the low P4 samples. The latter is, however, attributable to high inter- and intra-method variability at low P4 concentrations. This study does not indicate any relevant interference of DYD/DHD within routinely used progesterone assays.

Commutability of possible external quality assessment materials for progesterone measurement

BackgroundThe commutability of control materials used for external quality assessment (EQA) programs is of great importance. Evaluating the commutability of control materials is crucial to assess their suitability for EQA programs. MethodsForty-eight individual patient serum samples, commercial EQA samples, human serum pools (HSPs), commercially available sterile filtered charcoal stripped serum (CS) and swine serum were analyzed using the isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) comparative method and six immunoassays for progesterone. The commutability was assessed according to the EP14-A2 guideline and the difference in bias approach, respectively. ResultsAccording to the EP14-A2 guideline, HSPs and CS were commutable for all the tested immunoassays, while swine serum showed positive matrix effects in some assays. Based on the difference in bias approach, a large number of inconclusive and noncommutable results appeared. ConclusionsThe commutability of the processed materials varied depending on which evaluation approach and criterion was applied. Noncommutability of the EQA materials was observed. And HSPs and CS were possible commutable candidate control materials according to the EP14-A2 guideline.

Reproducibility of saliva progesterone measured by immunoassay compared to liquid chromatography mass spectrometry

Immunoassay overestimates progesterone in blood, but no studies have tested whether this occurs in saliva. We measured progesterone in saliva using immunoassay and mass spectrometry. We tested the immunoassay for cross reactivity with dehydroepiandrosterone sulfate (DHEA-S) and 17α-hydroxyprogesterone (17α-OHP). Progesterone was significantly higher in immunoassay compared to mass spectrometry. Immunoassay progesterone levels increased in when incremental levels of 17α-OHP standard was added. This effect was not observed with the addition of DHEA-S. Research using salivary progesterone immunoassay techniques should be wary, particularly with individuals taking steroid supplementation or with high levels of progesterone metabolites.

Vaginal Microbiota Changes During Estrous Cycle in Dairy Heifers.

The vaginal microbiota plays an important role in the health of dairy cattle, and it could be manipulated for the prevention and treatment of reproduction-related infections. The present study profiles and compares the vaginal microbiota of healthy dairy heifers during the estrous cycle focusing the results in follicular (estrus) and luteal (diestrus) phases using 16S rRNA sequencing of the V3–V4 hypervariable region. Twenty 13–16-months-old virgin dairy heifers from a single farm were included in this study. Vaginal swabs and blood samples were obtained during estrus (6–8 h before artificial insemination) and diestrus (14 days after insemination). Estrus was evaluated by an activity monitoring system and confirmed with plasma progesterone immunoassay. Results showed that the taxonomic composition of the vaginal microbiota was different during the follicular and luteal phases. At the phylum level, the most abundant bacterial phyla were Tenericutes, Firmicutes, and Bacteroidetes which comprised more than 75% of the vaginal microbiota composition. The next more abundant phyla, in order of decreasing abundance, were Proteobacteria, Actinobacteria, Fusobacteria, Epsilonbacteraeota, and Patescibacteria. Together with Tenericutes, Firmicutes, and Bacteroidetes represented more than 96% of the bacterial composition. Ureaplasma, Histophilus, f_Corynebacteriaceae, Porphyromonas, Mycoplasma, Ruminococcaceae UCG-005, were the most abundant genera or families. The results also showed that the vaginal microbiota of dairy heifers was non-lactobacillus dominant. The genus Lactobacillus was always found at a low relative abundance during the estrous cycle being more abundant in the follicular than in the luteal phase. Despite more research is needed to explore the potential use of native vaginal microbiota members as probiotics in dairy heifers, this study represents an important step forward. Understanding how the microbiota behaves in healthy heifers will help to identify vaginal dysbiosis related to disease.

Correction to: EStradiol and PRogesterone in In vitro ferTilization (ESPRIT): a multicenter study evaluating third‑ versus second‑generation estradiol and progesterone immunoassays.

The article "EStradiol and PRogesterone inInvitro ferTilization (ESPRIT): amulticenter study evaluating third‑ versussecond‑generation estradiol andprogesterone immunoassays.

EStradiol and PRogesterone in In vitro ferTilization (ESPRIT): a multicenter study evaluating third- versus second-generation estradiol and progesterone immunoassays

PurposeTo assess estradiol (E2) and progesterone levels during ovarian stimulation determined by third-generation (Gen III) and second-generation (Gen II) Elecsys® immunoassays.MethodsE2 and progesterone concentrations were measured using Elecsys® Gen III and Gen II immunoassays, and progesterone concentrations on the day of ovulation triggering were determined by LC–MS/MS. This was a retrospective, non-interventional study conducted at European tertiary referral infertility clinics in women aged 18–45 years, with a body mass index 18–35 kg/m2, regular menses, and both ovaries.ResultsSerum samples were obtained from 230 women classified by oocyte retrieval as poor (33.0%; 0–3 oocytes), normal (40.9%; 4–15 oocytes), or high (26.1%; > 15 oocytes) responders. E2 and progesterone levels increased during ovarian stimulation, with greatest increases observed in high responders. Elecsys® Gen III and Gen II assay results were highly correlated for E2 (Pearson’s r = 0.99) and progesterone (r = 0.89); Gen III results were lower than Gen II for both E2 and progesterone. On the day of triggering, Gen III E2 and progesterone levels showed a difference of − 15.0% and − 27.9%, respectively. Progesterone levels (on day of triggering) measured by LC–MS/MS correlated better with Gen III (0.98) than Gen II (0.90). Mean relative differences for Gen III and Gen II assays versus LC–MS/MS were 14.6% and 62.8%, respectively.ConclusionE2 and progesterone levels determined with Elecsys® Gen II and III assays were highly correlated; results were lower for Gen III versus Gen II. Differences observed for progesterone on the day of triggering may be clinically relevant.

Accuracy of Two Progesterone Immunoassays for Monitoring In Vitro Fertilization.

Progesterone concentrations are routinely monitored during in vitro fertilization cycles. Immunoassay-based platforms are used most often in this setting because they are simple to use and amenable to same-day sample collection and result-reporting. However, immunoassay methods are subject to variation in specificity between different assay manufacturers. In this study, a set of unexpectedly high progesterone concentrations led to a method comparison between two in-house immunoassay platforms relative to the reference method. Progesterone was measured in 28 serum samples from women undergoing IVF cycles using the Siemens ADVIA Centaur Immunoassay system and the Abbott Architect i1000SR analyzer. A subset of these samples was selected for progesterone measurement by liquid chromatography-tandem mass spectrometry to define the accuracy of each immunoassay. The Siemens ADVIA Centaur immunoassay system overestimated progesterone concentrations by 19% and the Abbott Architect overestimated progesterone concentrations by 5%. The Abbott Architect progesterone immunoassay provides a more accurate measurement of serum progesterone than the Centaur immunoassay at concentrations relevant for monitoring in vitro fertilization populations.

Rapid flow-through enzyme immunoassay of progesterone in whole cows' milk

A rapid flow-through immunoassay using an enzyme (horseradish peroxidase) as a label for quantitative and semi-quantitative determination of progesterone in whole cows' milk was developed. The flow-through test device consisted of a porous nitrocellulose membrane coated with antibodies and an absorbent membrane. The substrate solution containing 3,3′,5,5′ -tetramethylbenzidine was used for colour visualization. The detection limit of 0.4 ng/mL P4 was obtained by this method; analysis time did not exceed 15 min. To eliminate matrix interference a simple sample preparation procedure was used. Results of analysis of whole cows' milk samples with flow-through method were in good correlation with ELISA results (R = 0.96, n = 34). The developed rapid flow-through test system showed high efficiency for the determination of progesterone level in whole cow's milk and can be used on-site for quick identification of milk samples with low and high progesterone concentration.

Erratum to: Dehydroepiandrosterone (DHEA) supplementation results in supraphysiologic DHEA-S serum levels and progesterone assay interference that may impact clinical management in IVF.

Dehydroepiandrosterone (DHEA) is often prescribed for poor responders in IVF in an effort to improve response to ovarian stimulation. The effect of DHEA supplementation and resultant supraphysiologic DHEA-S serum levels on sex steroid assays has not been evaluated in this population. This study seeks to determine the relationship between DHEA supplementation and progesterone measurements to characterize the degree of interference with particular immunoassays. Characterization was accomplished in two phases. First, DHEA-S standard control reagents with no progesterone present were assayed for both DHEA-S and progesterone levels. Second, serum pools from 60 unique IVF patients’ serum were used to create six pooled serum samples: three from patients on DHEA supplementation and three from patients not on DHEA supplementation. The three pools were composed of patients whose serum fell into low, medium, and high progesterone ranges. Baseline DHEA-S and progesterone were measured, and the mean level of DHEA-S in the mid-range progesterone pool was used as the mid-point for addition of DHEA-S standard to the serum pools from patients without DHEA supplementation. Progesterone from these pools was then measured on three commercially available immunoassay systems. The first experiment revealed a linear increase in progesterone when analyzing the DHEA-S standard ranging from 0.5 ng/mL in the blank control (no DHEA-S) to up to 2.0 ng/mL in the high control (DHEA-S >700 μg/mL), indicating that the DHEA-S cross-reacts with the progesterone assays. In the second experiment, patients’ serum DHEA-S and progesterone were measured from pooled serum samples of those taking DHEA and those not taking DHEA. Adding DHEA-S to the pooled serum of those not taking DHEA resulted in a linear increase in progesterone levels on two of three commercially available immunoassays (p < 0.05). DHEA-S can interfere with standard progesterone immunoassays used in clinical ART programs, and thus serum progesterone levels in IVF patients on DHEA supplementation may not reflect truly bioactive progesterone.

Accuracy of a Direct Progesterone Immunoassay.

Beyond the established role of serum progesterone measurement in the luteal phase of menstrual cycle to confirm recent ovulation, it is also increasingly used to detect premature luteinization during in vitro fertilization (IVF) hyperstimulation, where late follicular phase increase in serum progesterone is reportedly associated with adverse pregnancy outcomes. Virtually all serum progesterone measurements in clinical and IVF practice use direct, nonextraction immunoassays, often in multiplex, high-throughput platform assays optimized for high, postovulatory, midluteal phase serum progesterone concentrations. However, the performance of direct progesterone immunoassays for smaller increases is not established. We studied 254 women undergoing IVF hyperstimulation with serum progesterone around the time of human chorionic gonadotropin (hCG) administration, measured in each sample by a direct progesterone immunoassay (Beckman Coulter Access) and by LC-MS. Immunoassay overestimated serum progesterone in almost every sample with an increasingly high variability and deviation at lower concentrations (immunoassay <5 nmol/L, equivalent to LC-MS <2 nmol/L). Immunoassay consistently overestimates serum progesterone levels so that low measurements (immunoassay <5 nmol/L) are too inaccurate to be used quantitatively. The utility of higher serum progesterone measurements by immunoassay and serum progesterone and other steroids measured by multiplex LC-MS profiling in predicting IVF pregnancy outcomes warrants further investigation. There is a need for caution in clinical diagnosis of premature luteinization based on increased late follicular phase serum progesterone measurements using direct progesterone immunoassay that consistently overestimates low serum progesterone concentrations.

Dehydroepiandrosterone (DHEA) supplementation results in supraphysiologic DHEA-S serum levels and progesterone assay interference that may impact clinical management in IVF.

Dehydroepiandrosterone (DHEA) is often prescribed for poor responders in IVF in an effort to improve response to ovarian stimulation. The effect of DHEA supplementation and resultant supraphysiologic DHEA-S serum levels on sex steroid assays has not been evaluated in this population. This study seeks to determine the relationship between DHEA supplementation and progesterone measurements to characterize the degree of interference with particular immunoassays. Characterization was accomplished in two phases. First, DHEA-S standard control reagents with no progesterone present were assayed for both DHEA-S and progesterone levels. Second, serum pools from 60 unique IVF patients' serum were used to create six pooled serum samples: three from patients on DHEA supplementation and three from patients not on DHEA supplementation. The three pools were composed of patients whose serum fell into low, medium, and high progesterone ranges. Baseline DHEA-S and progesterone were measured, and the mean level of DHEA-S in the mid-range progesterone pool was used as the mid-point for addition of DHEA-S standard to the serum pools from patients without DHEA supplementation. Progesterone from these pools was then measured on three commercially available immunoassay systems. The first experiment revealed a linear increase in progesterone when analyzing the DHEA-S standard ranging from 0.5 μg/dL [corrected] in the blank control (no DHEA-S) to up to 2.0 μg/dL [corrected] in the high control (DHEA-S >700 μg/dL), [corrected] indicating that the DHEA-S cross-reacts with the progesterone assays. In the second experiment, patients' serum DHEA-S and progesterone were measured from pooled serum samples of those taking DHEA and those not taking DHEA. Adding DHEA-S to the pooled serum of those not taking DHEA resulted in a linear increase in progesterone levels on two of three commercially available immunoassays (p < 0.05). DHEA-S can interfere with standard progesterone immunoassays used in clinical ART programs, and thus serum progesterone levels in IVF patients on DHEA supplementation may not reflect truly bioactive progesterone.

Development of a Competitive Lateral Flow Immunoassay for Progesterone in Dairy Cows’ Milk

The routine monitoring of progesterone, a hormone that plays important roles during pregnancy, has become increasingly important in dairy cows. In this study, 11α-OH-progesterone-hemisuccinate-BSA was used to immunize Balb/c mice for the preparation of mouse anti-progesterone monoclonal antibodies (mAbs). A competitive lateral flow immunoassay for progesterone was developed with the use of purified mAbs. Standard progesterone solutions or milk samples containing different concentrations of progesterone were added to the sample pad of the test strip. A bright or weak test line represented progesterone levels &lt;3 ng&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td class="keywords"&gt;Key words: progesterone; lateral flow immunoassay; pregnancy diagnosis; dairy cows&lt;/td&gt; &lt;/tr&gt; &lt;/tbody&gt;

The Bioluminescence Resonance Energy Transfer from Firefly Luciferase to a Synthetic Dye and its Application for the Rapid Homogeneous Immunoassay of Progesterone.

The sensitive BRET system for the homogeneous immunoassay of a low-molecular weight antigen was developed using progesterone as an example. Two thermostable mutants of the Luciola mingrelica firefly luciferase (Luc)-the "red" mutant with λmax.em = 590 nm (RedLuc) and the "green" mutant with λmax.em = 550 nm (GreenLuc)-were tested as the donors. The water-soluble Alexa Fluor 610× (AF) dye was selected as the acceptor because its two absorption maxima, located at 550 and 610 nm, are close to the bioluminescence maxima of the GreenLuc and RedLuc, respectively. The methods for the synthesis of the luciferase-progesterone (Luc-Pg) conjugate and the conjugate of the dye and the polyclonal antiprogesterone antibody (AF-Ab) were developed. Both conjugates retained their functional properties, had high antigen-antibody binding activity, and demonstrated a high BRET signal. The homogeneous immunoassay system based on the BRET from the firefly luciferase to the synthetic dye was established to assay progesterone as a model antigen. Optimization of the assay conditions, the composition of the reaction mixture, and the concentrations of the donor and the acceptor made it possible to reach the minimum detectable progesterone concentration of 0.5 ng mL(-1) .

Sensitive Progesterone Determination Using a Magnetic Particle-Based Enzyme-Linked Immunosorbent Assay

A highly sensitive magnetic nanoparticle enzyme immunoassay of progesterone was established using horseradish peroxidase as a label. The “enzyme label” was prepared by coupling of progesterone-3-(O-carboxymethyl)oxime to horseradish peroxidase. The antiprogesterone antibody was immobilized on the aminomodified magnetic nanoparticles by glutaraldehydе. The typical standard curve for progesterone in buffer by the magnetic nanoparticles enzyme immunoassay was obtained with a detection limit of 0.04 ng mL−1. These results were compared to the data obtained for progesterone in milk. It has been shown that the progesterone magnetic particle-based enzyme-linked immunosorbent assay in milk had a minor depression in sensitivity (detection limit of 0.09 ng mL−1). The progesterone calibration curves obtained by the random antibody immobilization were compared with results by protein A oriented immobilization of the antibodies. The sensitivity of progesterone magnetic particle-based enzyme-linked immunosorbent assay in milk using random antibody immobilization method was lower than sensitivity of the progesterone magnetic particle-based enzyme-linked immunosorbent assay using protein A oriented immobilization method (detection limit of 0.08 ng mL−1). The influences of milk type and the fat content in milk on the immunoassay were investigated. With an improved sensitivity and simple operation, the magnetic particle-linked antibody for immunoassay of progesterone has great potential to supersede the traditional enzyme-linked immunosorbent assay for progesterone determination.

Competitive immunoassay of progesterone by microchip electrophoresis with chemiluminescence detection

A sensitive and rapid homogeneous immunoassay method based on microchip electrophoresis-chemiluminescence detection (MCE-CL) using luminol-hydrogen peroxide as chemiluminescence system catalyzed by horseradish peroxidase (HRP) was developed for the determination of progesterone (P). The assay was based on the competitive immunoreactions between HRP-labeled P antigen (HRP-P) and P with a limited amount of anti-P mouse monoclonal antibody (Ab), and MCE separation of free HRP-P and HRP-P-Ab immunocomplex followed by CL detection. The effect of various factors such as conditions for the CL reaction, MCE and incubation time for the immunoreactions were examined and optimized. Under optimal assay conditions, the MCE separation was accomplished within 80s. The linear range of detection for P was 8-800nM with a detection limit of 3.8nM (signal/noise ratio=3). This present method has been applied to determine P in human serum samples from normal and pregnant women. The result indicates that the proposed MCE-CL based homogeneous immunoassay method can serve as an alternative tool for clinical assay of P.

High rates of pregnancy loss by subordinates leads to high reproductive skew in wild golden lion tamarins (Leontopithecus rosalia)

Across taxa, cooperative breeding has been associated with high reproductive skew. Cooperatively breeding golden lion tamarins (Leontopithecus rosalia) were long thought to have a monogynous mating system in which reproduction was limited to a single dominant female. Subordinates with few reproductive opportunities delayed dispersal and remained in the natal group to provide alloparental care to siblings, thus allowing dominant reproductive females to meet the energetic needs associated with high rates of reproduction and successful infant rearing. The goal of this study was to re-assess monogyny in wild golden lion tamarin groups based upon pregnancy diagnoses that used non-invasive enzyme immunoassay for progesterone and cortisol, combined with weekly data on individual weight gain, bi-annual physical examinations noting pregnancy and lactation status and daily behavioral observations. We established quantitative and qualitative criteria to detect and determine the timing of pregnancies that did not result in the birth of infants. Pregnancy polygyny occurred in 83% of golden lion tamarin groups studied. The loss of 64% of subordinate pregnancies compared to only 15% by dominant females limited reproductive success mainly to dominant females, thus maintaining high reproductive skew in female golden lion tamarins. Pregnancy loss by subordinate adults did not appear to result from dominant interference in subordinate hormonal mechanisms, but more likely resulted from subordinate abandonment of newborn infants to mitigate dominant aggression.