A non-chromatographic radioimmunoassay of estrone and estradiol-17beta serum

A sensitive and efficient non-chromatographic procedure employing the Girard reagent and solvent-partitioning has been developed for the accurate radioimmunoassay (RIA) of estrone (E1) and estradiol-17β(E2) in a single 1.0 ml specimen of male or female serum. Using standard curves which permitted the discrimination of zero from 0.75–1.5 pg (p=0.05), the following mean procedural blanks (pg ± S.D.) were determined (1.0 ml water, n= 24): estrone, 2. 1 ± 1.1 (range 0–4.1); estradiol 1.0± 1.1 (range 0–3.6).A comparison of RIA of estrogens (1) in serum after separation by the Girard procedure and by TLC yielded correlation coefficients of 0.99 and 0.98 for E1 and E2 respectively. The following results (pg/ml ± S.D.) were obtained on RIA of E1 and E2 in 12 different 1.0 ml specimens of male and female serum using the Girard procedure: male. E1 (32.0 ± 9.2), E2 (24.1 ± 10.9); female, E1 (108.5 ± 60.8), E2 (126.4 ± 63.2).The intra-assay variability (c.v.) was found to be 12.6% for E1 and 9.4% for E2. The interassay variability was 14.2% for both estrogens.Twenty-four assays of E1 and E2 can be completed by one person in 2 working days.     

Gonadal development and steroid hormone profile of wild caught grey mullet (Mugil cephalus)

The grey mullet Mugil cephalus is one of the popular and fast growing fishes being cultured in tropical and subtropical regions. In the present study, histological observation of gonadal development and corresponding changes in sex steroid levels from different maturity stages of wild caught male and female were studied. In female, testosterone and 17β-estradiol increased with the advancement of maturation and reached peak (17β-estradiol, 323 ± 13 pg/ml; testosterone, 938 ± 7.87 pg/ml) in mature stage, whereas the level of progesterone was maximum (488 ± 4.9 pg/ml) during ripe stage. Vitellogenin level in serum showed a similar trend as 17β-estradiol. In case of male, the testosterone level in serum increased gradually with advancement of maturation and was maximum (1820 ± 40.25 pg/ml) during ripe stage, whereas significant decrease in 17β-estradiol and progesterone was noticed with advancement of maturation. The fundamental information from this investigation would be useful for developing protocol for accelerating maturation and spawning under captive condition.     

Seasonal reproductive cycle of the Galápagos tortoise (Geochelone nigra) in captivity

The reproductive physiology of nine Galápagos tortoises (Geochelone nigra) was studied from February 1988 to May 1989. The study encompassed the annual reproductive cycle to include complete mating and nesting sequences. Male (n = 4) and female (n = 5) seasonal reproductive changes were determined throughout the study with endocrine analysis and ultrasonographic examinations. Males displayed a prenuptial rise in serum testosterone (x― ±SE = 6.62 ± 0.92 ng/ml in August) during which gonadal maturation and spermatogenesis are thought to occur. The male reproductive cycle appears consistent with the prenuptial spermatogenic pattern exhibited by other tropical turtles. In the females, testosterone rose during the mating period (x― ± SE = 499.3 ± 124.6 pg/ml in October) prior to ovulation and is probably related to receptivity in the females. Progesterone was more variable, but also peaked during the mating period (x― ± SE = 1,017.2 ± 220.6 pg/ml in October) and appears related to ovulation. Estradiol rose several months prior to mating (x― ± SE = 75.5 ± 11.9 pg/ml in July) and was correlated with increased serum calcium levels. This increase in estradiol is thought to stimulate vitellogenesis several months prior to mating. Nesting occurred from November 1988 to April 1989, during which six clutches were laid. Clutch size ranged from eight to 17 eggs. Both male and female Galápagos tortoises display seasonal physiological changes that function to regulate annual reproductive patterns. Zoo Biol 17:505–517, 1998. © 1998 Wiley-Liss, Inc.     

Serum concentrations of oestradiol and progesterone, and sexual behaviour during the normal oestrous cycle in the leopard (Panthera pardus)

Three mature nulliparous female leopards were studied for 5 years. During three separate 6-month periods serum oestradiol and progesterone concentrations were measured at weekly intervals. Oestradiol was elevated over 21 pg/ml for 54 weeks during these 3 periods, and 36 oestradiol peaks (65.8 +/- 6.3 pg/ml (mean +/- s.e.m.), range 21-172 pg/ml) were identified. Daily frequency of feline reproductive behaviours averaged over each week increased from 1.9 +/- 0.2 (n = 93) during weeks with low serum oestradiol concentrations (less than 21 pg/ml) to 5.3 +/- 0.6 (n = 54) during weeks when serum oestradiol concentrations (greater than 21 pg/ml) were high. Increased serum progesterone concentrations (13-98 n/gml) were observed on 5 occasions in 2 leopards housed together. These presumptive luteal phases lasted from 1 to 5 weeks. Baseline progesterone values were 1.6 +/- 0.4 ng/ml (n = 131). No progesterone increments were observed in isolated animals, and serum concentrations remained at baseline levels. These limited observations suggest that female leopards do not require intromission to induce ovulation and luteal function. The average interval between oestradiol peaks for cycles with no progesterone increment was 3.4 weeks (range 1-6 weeks). The interval for the 3 complete cycles associated with elevated progesterone concentrations was 7.3 weeks. Analysis of sexual behaviours over the 5-year study period revealed no evidence of seasonality in these captive leopards.     

Killer whale (Orcinus orca) reproduction at Sea World

Sea World has maintained killer whales (Orcinus orca) since 1965. The total killer whale inventory (1965–1993) has included 39 whales (25 females, 14 males); 28 were wild-caught and 11 captive-born, including one second-generation calf. As of September, 1993, there were 19 whales in the breeding program. Ten of these whales (53%) were captive-born, either at Sea World or other facilities in North America. The live wild-caught whales ranged in estimated age from 12–27 years (x? ± sd = 17.6 ± 4.2 years). The captive-born whales ranged in age from <1 to 8 years. In the Sea World breeding program (through September, 1993), there have been nine live births and one stillbirth, with eight calves part of the current inventory. Births occurred from July to February. Calving intervals ranged from 32–58 months. Female age at birth of first calves ranged from 8 years to an estimated 17 years (x? ± sd = 12.7 ± 3.0 years). Gestation, based on conception estimates from serum progesterone analysis, averaged 17 months (x? ± sd = 517 ± 20 days), but successful pregnancies with viable calves occurred from 15–18 months (468–539 days). Females, in the presence and absence of males, were polyestrus with periods of cycling interspersed with individually variable noncycling (presumed anestrous) periods ranging from 3–16 months. Mean serum progesterone levels (±se) were as follows: noncycling periods = 121 ± 20 pg/ml; peak elevations during nonconceptive ovulatory (estrous) cycles = 3,962 ± 2,280 pg/ml; first pregnancies = 14,592 ± 3,854 pg/ml; second pregnancies = 8,389 ± 395 pg/ml; and third pregnancy = 8,180 ± 4,556. © 1995 Wiley-Liss, Inc.     

Establishment of Radioimmunoassay for Human Macrophage Colony-stimulating Factor Using Recombinant Human Macrophage Colony-stimulating Factor as Tracer and Immunogen

A sensitive and reliable radioimmunoassay (RIA) for human macrophage colony-stimulating factor (M-CSF) was developed using recombinant human M-CSF (rhM-CSF) as tracer and immunogen. The assay was quantitative over the range of 50 pg/ml and 5.0 ng/ml for M-CSF in human urine and serum, and more sensitive and specific than the murine bone marrow assay. The average level of human M-CSF in urine from normal males (N = 71) and females (N = 46) was 3.94 ± 1.78 ng/ml (2.85 ± 1.15 μg/g creatinine), and 3.53 ± 1.70ng/ml (3.31 ± 1.12 μg/g creatinine), respectively. The serum levels were 1.95 ± 0.38ng/ml for males (N = 117), and 1.93 ± 0.49 ng/ml for females, (N = 16). The results with the urine and sera showed that there was no difference in the M-CSF levels due to age or gender.     

Gender, exercise training, and eNOS expression in porcine skeletal muscle arteries.

Our purpose was to determine the effects of gender and exercise training on endothelial nitric oxide synthase (eNOS) and superoxide dismutase (SOD) protein content of porcine skeletal muscle arteries and to evaluate the role of 17beta-estradiol (E2) in these effects. We measured eNOS and SOD content with immunoblots and immunohistochemistry in femoral and brachial arteries of trained and sedentary male and female pigs and measured estrogen receptor (ER) mRNA and alpha-ER and beta-ER protein in aortas of male and female pigs. Results indicate that female arteries contain more eNOS than male arteries and that exercise training increases eNOS content independent of gender. Male and female pigs expressed similar levels of alpha-ER mRNA and protein and similar amounts beta-ER protein in their arteries. E2 concentrations as measured by RIA were 180 +/- 34 pg/ml in male sera and approximately 5 pg/ml in female sera, and neither was changed by training. However, bioassay indicated that biologically active estrogen equivalent to only 35 +/- 5 pg/ml was present in male sera. E2 in female pigs, whether measured by RIA or bioassay, was approximately 24 pg/ml at peak estrous and 2 pg/ml on day 5 diestrus. The free fraction of E2 in sera did not explain the low measurements, relative to RIA, of E2. We conclude that 1). gender has significant influence on eNOS and SOD content of porcine skeletal muscle arteries; 2). the effects of gender and exercise training vary among arteries of different anatomic origin; 3). male sera contains compounds that cause RIA to overestimate circulating estrogenic activity; and 4). relative to human men, the male pig is not biologically estrogenized by high levels of E2 reported by RIA, whereas in female pigs E2 levels are lower than in the blood of human women.     

Circadian rhythm of aldosterone in dairy cattle during the summer

Twelve Holstein heifers, pregnant from 120–150 days were used to study the circadian rhythm of aldosterone, cortisol, progesterone, sodium and potassium in dairy cattle during the summer in Louisiana. Cortisol was not significantly influenced by time (time 1 = 06.00 h). Aldosterone, sodium, potassium and progesterone changed significantly (P<.01) with time. Aldosterone peaked (116.5±17.2 pg/ml) at 08.00 h and then generally declined to 16.00 h (26.7±2.0 pg/ml). Sodium generally increased from 06.00 h (320.1±7.3 mg%) to 18.00 h (377.9±6.1 mg%), and then declined. Potassium generally increased from 06.00 h (20.9±0.5 mg%) to 22.00 h (23.0±0.3 mg%). Progesterone generally increased from 07.00 h (2.8±0.4 mg/ml) to 24.00 h (7.5±1.4 mg/ml). Aldosterone was significantly related to temperature associated with the time of the day samples were taken (r = 0.66, P<.02).     

Plasma Progesterone Assays in Superovulated Cattle

Plasma progesterone was measured in 14 normally cycling heifers and cows subjected to non-surgical recoveries of embryos. A radioimmunoassay (RIA) method was used for progesterone determination. The average progesterone concentration increased from 7.5 to 11.6 ng/ml in 8 of the animals following treatment with PMSG on day 8–12. Six animals had a decrease from 5.0 ± 2.1 to 3.9 ± 2.5 ng/ml. The overall increase was from 6.4 ± 2.7 ng/ml to 8.3 ± 4.8 ng/ ml. Prostaglandin F2a-analogue (cloprostenol) treatment resulted in a sharp decrease in plasma progesterone followed by a rapid increase to an average of 46.8 ng/ml on day 16. A high degree of variability in this peak value was observed, and it was not correlated with the number of corpora lutea. The superovulatory cycle was generally prolonged. The heat following the superovulatory treatment was silent, and a typical ovarian resting period was observed during which the progesterone concentration remained low and the ovaries small.     

Measurement of thromboxane B2 in human plasma or serum by radioimmunoassay

A radioimmunoassay for thromboxane B₂ (TxB₂), a stable metabolite of thromboxane A₂, is described. The method consists of extraction of TxB₂ into ethyl acetate from acidified plasma or serum samples and saturation analysis using specific antibodies produced in rabbits against TxB₂-BSA conjugate. The 50 % displacement level of the standard curve was 19.1 ± 2.9 pg/tube (mean ± S.D., n = 19). The method blank was 3.4 ± 3.1 pg/ml (n = 15) and the assay sensitivity thus 9.6 pg/ml (mean blank + 2 S.D.). When 100 to 200 pg of TxB₂ were added to plasma, 96.2–103.6 % were recovered. The intra-assay coefficient of variation varied from 6.7 to 9.7 %, and the inter-assay coefficient of variation was 18.6 % (n = 10). The TxB₂ concentration in the plasma of 14 healthy subjects varied from 29.3 to 120.8 pg/ml with a mean ± S.D. of 70.1 ± 26.1 pg/ml, when the blood was collected into tubes containing acetylsalicylic acid (ASA), whereas significantly higher (p < 0.001) TxB₂ concentrations of 68.3 – 285.3 pg/ml with a mean ± S.D. of 151.8 ± 66.6 pg/ml were obtained from the same subjects in the plasma of blood which was collected into tubes containing no ASA. When blood samples from 10 subjects were allowed to clot at 0, +24 or +37°C for 60 min., the TxB₂ concentrations in the sera were 2053 ± 870 pg/ml, 4001 ± 1370 pg/ml and 178557 ± 54000 pg/ml, respectively. The TxB₂ levels in sera which were separated from blood samples incubated at +37°C, correlated significantly (p < 0.001) with the TxB₂ productions in platelet-rich-plasma (PRP) after an induced aggregation. Our results indicate 1) when TxB₂ is measured in plasma, the use of prostaglandin synthesis inhibitor in the collection tubes is necessary and 2) the measurement of TxB₂ in serum of blood which has been kept at +37°C for a strictly standardized period of time could replace the use of PRP in TxB₂ studies.     

Monitoring the gestation period of rescued Formosan pangolin (Manis pentadactyla pentadactyla) with progesterone radioimmunoassay

Eight species of pangolin have been identified in the world. However, understanding of pangolin reproductive biology has been limited to fragmentary records. In this study, the concentration of serum progesterone in three pregnant and two nonpregnant rescued female Formosan pangolins (Manis pentadactyla pentadactyla) was monitored using a commercial progesterone radioimmunoassay kit. During gestation, the serum progesterone of pregnant pangolins A, B, and C remained at 28.5–55 ng/ml (n = 31 samples), 10.9–50.1 ng/ml (n = 34), and 12.4 and 33.5 ng/ml with a peak at 47.6 ng/ml (n = 19), respectively, whereas the serum progesterone of nonpregnant pangolins D and E remained at 1.99 ± 1.62 ng/ml (n = 80) and 2.27 ± 1.64 ng/ml (n = 27), respectively. From this study, it was found that female pangolin weighing as low as 2.14 kg was already capable of reproduction. For pregnant pangolins to give birth to viable offspring, their body weight must increase significantly, 63.89 and 134.0% in the study, from the time of inception or early pregnancy until parturition. In addition, study has found that both viable offspring were born fully developed and exceeded 80 g in weight. The period of gestation was found to be as short as 318 or longer than 372 days. Therefore, the Formosan pangolin should only be able to reproduce once a year. This study is the first insight into hormone assay for determining the gestation period of pangolin. Further investigations on the same subject are necessary to establish criteria for the recognition of reproductive status in pangolins. Zoo Biol 31:479–489, 2012. © 2011 Wiley Periodicals, Inc.     

Luteinizing hormone,total estrogens and progesterone secretion during lactation and after weaning in sows

Two experiments were conducted to determine changes in serum concentrations of LH, total free estrogens and progesterone before and after weaning in sows. Blood was collected either via indwelling anterior vena cava cannula or by venipuncture and serum hormones were measured by radioimmunoassay. In Exp. I, blood was collected at 15-min intervals for 4 hr on day 7 and day 21 postpartum from three sows on each day. In addition, individual samples were collected from 10 sows on days 4 and 14 postpartum and from 11 sows on days 1, 3 and 5 after weaning (day 23 postpartum). Serum LH ranged from .2 to .8 ng/ml during lactation and averaged 1.1 ± .7, 1.1 ± .7 and 2.7 ± .7 on days 1, 3 and 5 after weaning, respectively. Progesterone was low (< 1 ng/ml) during lactation and averaged 1.9 ± .3, .6 ± .3 and 1.2 ± .3 on days 1, 3 and 5 after weaning. Estrogens were variable during lactation, averaged 121 ± 36 pg/ml on day 1 after weaning and decreased thereafter. Estrus began on day 3 after weaning in 1 sow and on day 5 in the remaining 10 sows.In Exp. II, blood was collected from seven sows at 12 to 24 hr intervals from 2 days before until 5 days after weaning (day 26 postpartum). Mean serum LH was .7 ± .1 ng/ml during 48 hr before weaning and remained unchanged after weaning until day 3 when LH increased to 6.1 ± .8 ng/ml. Serum LH concentrations then declined to 1.3 ± .8 and .9 ± .8 ng/ml on days 4 and 5 after weaning. Total estrogens averaged 31 ± 4 pg/ml during 48 hr prior to weaning and 32 ± 4, 43 ± 17, 28 ± 1, 30 ± 2, 16 ± 2 and 18 ± 2 on days 0 to 5 after weaning. Progesterone increased from 1.0 ± .3 ng/ml 24 hr before weaning to 3.0 ± .3 at weaning and then remained low (< 1 ng/ml) until after ovulation when progesterone increased. Estrus began on day 4 after weaning in all seven sows.Results from these two experiments indicate that in sows: (1) LH is suppressed during early lactation (day 7), gradually increases during late lactation (day 21) and then reaches peak concentrations after weaning near the onset of estrus, (2) estrogens increase between weaning and estrus and decline thereafter, and (3) progesterone rises transiently at weaning and then increases after estrus and ovulation.     

Radioimmunoassay of estrone sulfate in the serum of normal men after a non-chromatographic procedure that eliminates interference from dehydroepiandrosterone sulfate

Duplicate aliquots of 20 fresh-frozen normal human male sera were prepared for estrone sulfate (ES) radioimmunoassay (RIA) by each of three different methods: the thin-layer chromatography (TLC) procedure we previously reported, a new procedure including overnight heating (100 C) of an ethanol extract reconstituted in dilute acetate buffer, and the new procedure with the hot incubation omitted. The purpose of the 100 C incubation was the selective thermal solvolysis of dehydroepiandrosterone sulfate (DS), the only steroid conjugate present in serum in high enough concentrations to interfere with a high-specificity ES RIA. Dehydroepiandrosterone released by solvolysis and endogenous unconjugated steroids were extracted from the samples with ether before RIA. Estrone sulfate values obtained after the thermal solvolysis preparation averaged 854 +/- 501 pg/ml (SD) versus 826 +/- 474 pg/ml (SD) after the TLC method, with excellent correlation between the two (r = 0.97). Samples prepared by the new method but with thermal solvolysis omitted averaged a 33.8% elevation of measured ES level, an elevation significantly correlated (P less than 0.02) with DS levels obtained from the same specimens. In addition, a single specimen showed no elevation after preparation by the thermal solvolysis method when up to 8 micrograms/ml authentic DS as added before extraction. Compared with the TLC method, the new method also provides substantial savings in specimen volume requirements and sample processing time.     

Demonstration of a specific binding protein for testosterone and 5alpha-dihydrotestosterone in rabbit serum. Separation from the corticosteroid binding globulin (CBG)

Rabbit serum contains a specific androgen binding protein which can be separated from the corticosteroid binding globulin (CBG) in rabbit serum by sucrose gradient ultracentrifugation and polyacrylamide gel electrophoresis. It has a sedimentation constant of 4–5 S (mean 4.4 S) and high binding affinities for 5α-dihydrotestosterone, 5α-androstan-3α, 17β-diol and testosterone but negligible affinity for androstenedione, progesterone or corticosterone. Concentrations of the androgen binding protein expressed as 5α-dihydrotestosterone (DHT) binding capacity at saturation are higher in adult female (4.0 ± 0.3 μg DHT bound/100 ml) than in adult male sera (1.4 ± 0.8 μg DHT bound/100 ml). Immature male sera contain slightly higher amounts than adult females.     

Circadian pattern of plasma melatonin concentrations in the marmoset monkey (Callithrix jacchus)

This study describes the concentrations of melatonin in plasma samples taken from marmoset monkeys (Callithrix jacchus) every 4 h over three 24-h periods. A circadian pattern of secretion was apparent, with higher levels recorded at night (20.00–08.00 h) than during the day (08.00–20.00 h) and a peak concentration at 20.00 h. There was a significant difference in the mean day and night concentrations (32.5 ± 4.5 pg/ml versus 49.0 ± 6.9 pg/ml, respectively) with individual concentrations ranging between<10–60 pg/ml in the day and 15–200 pg/ml at night. Circadian plasma melatonin concentrations were similar over the three 24-h periods, in male (n = 3) and female (n = 3) monkeys, and in dominant (cyclic, n = 5) and subordinate (acyclic, n = 4) females. The results show a less pronounced circadian profile in the marmoset than is seen in the human but a similar profile to that in the seasonally breeding rhesus monkey.     

Evaluation of adrenocortical function in Florida manatees (Trichechus manatus latirostris)

The study objectives were to determine the predominant manatee glucocorticoid; validate assays to measure this glucocorticoid and adrenocorticotropic hormone (ACTH); determine diagnostic thresholds to distinguish physiological vs. pathological concentrations; identify differences associated with sex, age class, female reproductive status, capture time, and lactate; and determine the best methods for manatee biologists and clinicians to diagnose stress. Cortisol is the predominant manatee glucocorticoid. IMMULITE 1000 assays for cortisol and ACTH were validated. Precision yielded intra‐ and inter‐assay coefficients of variation for serum cortisol: ≤23.5 and ≤16.7%; and ACTH: ≤6.9 and ≤8.5%. Accuracy resulted in a mean adjusted R²≥0.87 for serum cortisol and ≥0.96 for ACTH. Assay analytical sensitivities for cortisol (0.1 µg/dl) and ACTH (10.0 pg/ml) were verified. Methods were highly correlated with another IMMULITE 1000 for serum cortisol (r=0.97) and ACTH (r=0.98). There was no significant variation in cortisol or ACTH with sex or age class and no correlation with female progesterone concentrations. Cortisol concentrations were highest in unhealthy manatees, chronically stressed by disease or injury. ACTH was greatest in healthy free‐ranging or short‐term rehabilitating individuals, peracutely stressed by capture and handling. Cortisol concentrations ≥1.0 µg/dl were diagnostic of chronic stress; ACTH concentrations ≥87.5 pg/ml were diagnostic of peracute stress. In healthy long‐term captive manatees, cortisol (0.4±0.2 µg/dl) and ACTH (47.7±15.9 pg/ml) concentrations were lower than healthy free‐ranging, short‐term rehabilitated or unhealthy manatees. Capture time was not significantly correlated with cortisol; ACTH correlation was borderline significant. Cortisol and ACTH were positively correlated with lactate. Zoo Biol 30:17–31, 2011. © 2010 Wiley‐Liss, Inc.     

Evidence that 19-hydroxyandrostenedione is secreted by the adrenal cortex and is under the control of ACTH and the renin-angiotensin system in man

Plasma 19-hydroxyandrostenedione (19-OH-A-dione) concentrations in man were evaluated using a specific and sensitive radioimmunoassay. Plasma 19-OH-A-dione concentrations (mean ± SE) in normal subjects are 151 ± 14 pg/ml (n=13) in males and 141 ± 9 pg/ml (n=14) in females. Plasma 19-OH-A-dione (mean ± SE) rises significantly during ACTH stimulation (116 ± 25 pg/ml vs 288 ± 38 pg/ml; P<0.01; n=5), declines significantly during dexamethasone suppression (180 ± 30 pg/ml vs 36 ± 14 pg/ml; P<0.01; n=4) and rises significantly during angiotensin II infusion (89 ± 10 pg/ml vs 159 ± 27 pg/ml; P<0.05; n=5). Plasma 19-OH-A-dione in the adrenal vein is much higher than that in the inferior vena cava (2076–3076 pg/ml vs 115–184 pg/ml; n=2). These results demonstrate that 19-OH-A-dione is directly secreted by the adrenal cortex and is under the control of ACTH and the renin-angiotensin system.     

Simultaneous radioimmunoassay of testosterone and dihydrotestosterone

A radioimmunoassay, which simultaneously measures both testosterone (T) and dihydrotestosterone (DHT) in the same serum sample, is presented. Celite column chromatography is employed to separate T from DHT, and these two steroids from other potentially cross-reacting and interfering steroids. The normal values for men, women in the follicular phase, women in the luteal phase, ovariectomized and adrenal ectomized women, post-menopausal women and ovariectomized women for T are 5, 140 ± 1190 pg/ml, 307 ± 97 pg/ml, 285 ± 46 pg/ml, undetectable (<5 pg/ml), 262 ±47 pg/ml and 199 ±44 pg/ml; and for DHT 470 ± 165 pg/ml, 160 ±45 pg/ml, 147 ±44 pg/ml, undetectable (<5 pg/ml), 168 ± 27 pg/ml, 94 ± 15 pg/ml. The maximum sensitivity of the method was 10 pg/ml for T and 14.3 pg/ml for DHT when 1 ml was extracted. The blank in most assays was undetectable, but rarely exceeded 10 pg.     

Cytokine profile in cases with premature elevation of progesterone serum concentrations during ovarian stimulation

The aim of this study was to investigate the concentrations of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), leptin, tumor necrosis factor-alpha, interleukin (IL)-1beta and IL-6, in cycles with a premature rise of serum progesterone. 25 intracytoplasmic sperm injection (ICSI) cycles with (Group 1) and 25 ICSI cycles without a premature progesterone elevation (Group 2) were included. The cut-off value of serum progesterone on the day of human chorionic gonadotropin (hCG) administration was 0.9 ng/ml. The indication for ICSI was male factor infertility exclusively. On the day of hCG injection, serum IL-6, VEGF and bFGF were significantly higher in Group 1 (7.7+/-24.5 pg/ml, 290.2+/-161.4 pg/ml and 15.7+/-8.2 ng/ml respectively) than in Group 2 (1.7+/-0.7 pg/ml, 175.2+/-92.1 pg/ml, and 9+/-1.6 ng/ml respectively). On the day of follicular puncture, serum cytokine concentrations were similar in the two groups. IL-6 intrafollicular concentrations were higher in Group 1 (14.7+/-20.7 pg/ml) than in Group 2 (9+/-9.3 pg/ml, p=0.031). There were no differences regarding the ICSI outcome. Patients with serum progesterone above 0.9 ng/ml, have elevated serum concentrations of IL-6, VEGF, and bFGF, as well as elevated intrafollicular concentrations of IL-6. The outcome of ICSI cycles is not associated with premature elevation of progesterone when the cut-off value is set at 0.9 ng/ml.     

Endocrine profiles during the estrous cycle and pregnancy in the Baird's tapir (Tapirus bairdii)

Serum samples were collected 1–3 times weekly from two Baird's tapirs (Tapirus bairdii) for 6 months in 1987–1988, and for more than 3 consecutive years beginning in 1989 to characterize hormone patterns during the estrous cycle and pregnancy. Based on serum progesterone concentrations, mean (±SEM) duration of the estrous cycle (n = 20) was 30.8 ± 2.6 days (range, 25–38 days) with a luteal phase length of 18.1 ± 0.4 days (range, 15–20 days). Mean peak serum progesterone concentrations during the luteal phase were 1.35 ± 0.16 ng/ml, and nadir concentrations were 0.19 ± 0.03 ng/ml during the interluteal period. Distinct surges of estradiol preceded luteal phase progesterone increases in most (14/20) cycles. Gestation length was 392 ± 4 days for three complete pregnancies. Mean serum progesterone concentrations increased throughout gestation and were 1.83 ± 0.13, 2.73 ± 0.13, and 4.30 ± 0.16 ng/ml during early, mid- and late gestation, respectively. Serum estradiol concentrations began to rise during mid-gestation, increasing dramatically during the last week of pregnancy. Patterns of serum estriol and estrone secretion during pregnancy were similar to that observed for estradiol. In contrast to progesterone and estrogens, serum cortisol concentrations were unchanged during pregnancy or parturition. Females resumed cycling 16.2 ± 2.0 days after parturition (n = 4) and, on two occasions, females became pregnant during the first postpartum estrus. These data suggest that the tapir cycles at approximately monthly intervals and that increases in serum progesterone are indicative of luteal activity. The interluteal period is relatively long, comprising approximately 40% of the estrous cycle. During gestation, progesterone concentrations are increased above luteal phase levels, and there is evidence of increased estrogen production during late gestation. The absence of increased cortisol secretion at the end of gestation suggests that this steroid does not play a major role in initiating parturition in this species. © 1994 Wiley-Liss, Inc.