Dehydroepiandrosterone sulfate levels reflect endogenous luteinizing hormone production and response to human chorionic gonadotropin challenge in older female macaque (Macaca fascicularis).

OBJECTIVE: We propose that the adrenal gland of an older higher primate female animal model will respond to human chorionic gonadotropin (hCG) hormone challenge by secreting additional dehydroepiandrosterone sulfate (DHEAS). Such a response in surgically and chemically castrated animals will provide proof of concept and a validated animal model for future studies to explore the rise in DHEAS during the menopausal transition of women. METHODS: Twenty-four 18- to 26-year-old female cynomolgus monkeys were screened for ovarian function and then either ovariectomized (n = 4) or treated with a gonadotropin-releasing hormone agonist (GnRHa; n = 20) to block ovarian steroid production. After a recovery period from surgical procedure or down-regulation, a single-dose challenge (1,000 IU/animal, IM) of hCG was then administered to determine if luteinizing hormone (LH)/chorionic gonadotropin could accelerate circulating DHEAS production. Serum DHEAS, bioactive LH, and urinary metabolites of ovarian sex steroids were monitored before, during, and after these treatments. RESULTS: Circulating LH bioactivity and immunoreactive DHEAS concentrations were suppressed in all animals 14 days postadministration of GnRHa. Urinary metabolites of estradiol and progesterone remained low after the surgical procedure or a flare reaction to GnRHa. Circulating DHEAS levels were increased after hCG administration, and the increase in individual animals was proportional to the pretreatment DHEAS at baseline. Circulating DHEAS concentrations were positively correlated to endogenous LH bioactive concentrations prior to hCG challenge and were subsequently further elevated by the hCG challenge while no concomitant change in ovarian steroid hormone excretion was observed. CONCLUSIONS: These data demonstrate a positive adrenal androgen response to LH/chorionic gonadotropin in older female higher primates and suggest a mechanism for the rise in adrenal androgen production during the menopausal transition in women. These results also illustrate that the nonhuman primate animal model can be effectively used to investigate this phenomenon.

Overcoming bioanalytical challenges in an Onglyza(®) intravenous [(14)C]microdose absolute bioavailability study with accelerator MS.

BACKGROUND: An absolute bioavailability study that utilized an intravenous [(14)C]microdose was conducted for saxagliptin (Onglyza(®)), a marketed drug product for the treatment of Type 2 diabetes mellitus. Concentrations of [(14)C]saxagliptin were determined by accelerator MS (AMS) after protein precipitation, chromatographic separation by UPLC and analyte fraction collection. A series of investigative experiments were conducted to maximize the release of the drug from high-affinity receptors and nonspecific adsorption, and to determine a suitable quantitation range. RESULTS: A technique-appropriate validation demonstrated the accuracy, precision, specificity, stability and recovery of the AMS methodology across the concentration range of 0.025 to 15.0 dpm/ml (disintegration per minute per milliliter), the equivalent of 1.91-1144 pg/ml. Based on the study sample analysis, the mean absolute bioavailability of saxagliptin was 50% in the eight subjects with a CV of 6.6%. Incurred sample reanalysis data fell well within acceptable limits. CONCLUSION: This study demonstrated that the optimized sample pretreatment and chromatographic separation procedures were critical for the successful implementation of an UPLC plus AMS method for [(14)C]saxagliptin. The use of multiple-point standards are useful, particularly during method development and validation, to evaluate and correct for concentration-dependent recovery, if observed, and to monitor and control process loss and operational variations.

Hourly human chorionic gonadotropin secretion profiles during the peri-implantation period of successful pregnancies.

OBJECTIVE: To characterize the hourly profiles of hCG secretion in blood during conceptive cycles that ended in successful pregnancy. DESIGN: Prospective study. SETTING: University fertility clinic and research laboratories. PATIENT(S): Healthy spontaneously ovulating women with regular menses, no history of infertility, and either no male partner or an azospermic partner. INTERVENTION(S): Frequent blood samples were collected daily from 11 spontaneously ovulating women during 11 cycles of artifical insemination with donor semen. The concentrations of hCG, LH, and FSH were measured in the blood by immunoassay. MAIN OUTCOME MEASURE(S): The concentration of hCG in the frequent blood samples and the rate that the concentration of hCG changed during the period of frequent sampling. RESULT(S): For the conceptive cycles resulting in successful pregnancies analyzed, hourly hCG concentrations were observed to increase in a consistent nonpulsatile manner. CONCLUSION(S): These data provide the first characterization of the hourly secretion profile of hCG in early pregnancy as well as provide further evidence that individual daily blood samples are sufficient for the accurate assessment of pregnancy.

Secretion and excretion of human chorionic gonadotropin during early pregnancy.

OBJECTIVE: To characterize the profiles of human chorionic gonadotropin (hCG) secretion in blood and its subsequent excretion in urine during conceptive cycles that ended in successful pregnancy and in spontaneous abortion. DESIGN: A prospective study. SETTING: University fertility clinic and research laboratories. PATIENT(S): Healthy, spontaneously ovulating women with regular menses, no history of infertility, and either no male partner or an azoospermic partner. INTERVENTION(S): Blood and urine samples were collected daily from 63 spontaneously ovulating women during 167 cycles of artificial insemination (AI) with donor semen; hCG concentrations were measured in blood and urine, and luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations were measured in blood by immunoassay. MAIN OUTCOME MEASURE(S): Fecundity, the day of ovulation, the day of hCG detection, and the concentration of hCG on the day of detection in blood and urine. RESULT(S): In 62 conceptions detected, 14 resulted in clinical spontaneous abortion (CAB) and 8 resulted in early pregnancy loss (EPL). When successful pregnancies and pregnancy losses were compared, no significant differences existed between the days of hCG appearance in serum or in urine, the concentrations of hCG on the day of detection, or the incremental change in hCG concentration on the day of detection. CONCLUSION(S): These data validate the use of urinary hCG as a biomarker for assessing peri-implantation pregnancy events.

Bone resorption is affected by follicular phase length in female rotating shift workers.

Stressors as subtle as night work or shift work can lead to irregular menstrual cycles, and changes in reproductive hormone profiles can adversely affect bone health. This study was conducted to determine if stresses associated with the disruption of regular work schedule can induce alterations in ovarian function which, in turn, are associated with transient bone resorption. Urine samples from 12 rotating shift workers from a textile mill in Anqing, China, were collected in 1996-1998 during pairs of sequential menstrual cycles, of which one was longer than the other (28.4 vs. 37.4 days). Longer cycles were characterized by a prolonged follicular phase. Work schedules during the luteal-follicular phase transition (LFPT) preceding each of the two cycles were evaluated. All but one of the shorter cycles were associated with regular, forward phase work shift progression during the preceding LFPT. In contrast, five longer cycles were preceded by a work shift interrupted either by an irregular shift or a number of "off days." Urinary follicle-stimulating hormone levels were reduced in the LFPT preceding longer cycles compared with those in the LFPT preceding shorter cycles. There was greater bone resorption in the follicular phase of longer cycles than in that of shorter cycles, as measured by urinary deoxypyridinoline. These data confirm reports that changes in work shift can lead to irregularity in menstrual cycle length. In addition, these data indicate that there may be an association between accelerated bone resorption in menstrual cycles and changes of regularity in work schedule during the preceding LFPT.

Hormonal characteristics in the early luteal phase of conceptive and nonconceptive menstrual cycles.

To determine whether serum hormone profiles are different in nonconceptive and conceptive menstrual cycles after ovulation and before implantation. Daily blood samples obtained during the luteal phase of nonconceptive cycles (n = 31) and conceptive cycles (n = 19) were analyzed (intersubject comparison). Samples obtained in sequential nonconceptive and conceptive cycles from five subjects (intrasubject comparisons) were analyzed to confirm results obtained with intersubject analysis. Serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E(2)), progesterone, and relaxin were measured by immunoassay. A cell-based bioassay was used to determine whether the measurement of serum immunoreactive LH is a result of cross-reaction with human chorionic gonadotropin (hCG). Intersubject analysis showed that mean serum LH levels were significantly higher in conceptive cycles on day 4 and day 5 after the FSH peak in urine, and this was confirmed by intrasubject analysis. The addition of antibodies that precipitate hCG did not affect the activity of LH receptor ligand molecules in serum samples collected during the early luteal phase of conceptive cycles, as measured by bioassay. In contrast, this LH receptor binding activity was completely removed when precipitating antibodies for LH were added. The mean levels of serum E(2) were higher in conceptive cycles after day 4 following the FSH peak in urine. The mean values of serum FSH, progesterone, and relaxin were not significantly different in nonconceptive and conceptive cycles during the same time interval. The differences in luteal phase hormones may reflect alterations in signaling in the hypothalamic-pituitary-ovarian axis that begin during the preovulatory period of nonconceptive cycles.