Biomedical subjects

Jonathan Thornburg

Publications and source records attributed to Jonathan Thornburg.

4 recordsLinked to original sources

PubMed2006

A prospective study of early pregnancy loss in humans.

OBJECTIVE: To test two hypotheses: In spontaneous conceptions, early pregnancy loss (EPL) is associated with [1] inadequate luteal (ovarian) P, and/or [2] elevated follicular (adrenal) P. DESIGN: A population-based prospective study. SETTING: Thirty rural Bolivian communities. PATIENT(S): Women volunteers (n = 191), 19-40 years old, in stable sexual unions and not using contraception. INTERVENTION(S): Collection of serial saliva samples throughout sequential ovarian cycles and urine samples during late luteal phases. Collections continued throughout pregnancy for each detected conception. MAIN OUTCOME MEASURE(S): Occurrence of spontaneous conceptions and subsequent outcomes. Salivary concentrations of P. Test for elevated urinary human chorionic gonadotropin (hCG). RESULT(S): Luteal (through implantation) P levels were similar in pregnancies lost within 5 weeks after conception (EPL; n = 8) and those pregnancies that were maintained longer (sustained conceptions, SC; n = 32). Follicular P was significantly higher in EPL than in SC. CONCLUSION(S): [1] Elevated follicular P was associated with EPL in natural conceptions in healthy women. [2] Early pregnancy loss exhibits absolute luteal P levels comparable to SC, but lower luteal/follicular P ratios.

Abortion, Spontaneous↗

PubMed2006

Accurate evolution of orbiting binary black holes.

We present a detailed analysis of binary black hole evolutions in the last orbit and demonstrate consistent and convergent results for the trajectories of the individual bodies. The gauge choice can significantly affect the overall accuracy of the evolution. It is possible to reconcile certain gauge-dependent discrepancies by examining the convergence limit. We illustrate these results using an initial data set recently evolved by Brügmann et al. [Phys. Rev. Lett. 92, 211101 (2004)10.1103/PhysRevLett.92.211101]. For our highest resolution and most accurate gauge, we estimate the duration of this data set's last orbit to be approximately 59MADM.

Journal Article↗

PubMed2004

Interpopulational differences in progesterone levels during conception and implantation in humans.

Clinical studies of women from the United States demonstrate a sensitivity of the ovarian system to energetic stress. Even moderate exercise or caloric restriction can lead to lower progesterone levels and failure to ovulate. Yet women in many nonindustrial populations experience as many as a dozen pregnancies in a lifetime despite poor nutritional resources, heavy workloads, and typical progesterone levels only about two-thirds of those of U.S. women. Previous cross-sectional studies of progesterone may, however, suffer from inadvertent selection bias. In a noncontracepting population, the most fecund women, who might be expected to have the highest progesterone, are more likely to be pregnant or breastfeeding and hence unavailable for a cross-sectional study of the ovarian cycle. The present longitudinal study was designed to ascertain whether lower progesterone also characterizes conception, implantation, and gestation in women from nonindustrialized populations. We compared rural Bolivian Aymara women (n = 191) to women from Chicago (n = 29) and found that mean-peak-luteal progesterone in the ovulatory cycles of Bolivian women averaged approximately 71% that of the women from Chicago. In conception cycles, progesterone levels in Bolivian women during the periovulatory period were approximately 63%, and during the peri-implantation period were approximately 50%, those of the U.S. women. These observations argue that lower progesterone levels typically characterize the reproductive process in Bolivian women and perhaps others from nonindustrialized populations. We discuss the possible proximate and evolutionary explanations for this variation and note the implications for developing suitable hormonal contraceptives and elucidating the etiology of cancers of the breast and reproductive tract.

Embryo Implantation↗

PubMed2002

Salivary progesterone levels and rate of ovulation are significantly lower in poorer than in better-off urban-dwelling Bolivian women.

BACKGROUND: Agriculturalists in less-developed countries (LDC) have lower progesterone levels than urban industrialized populations. However, it is unknown if urban LDC populations are also relatively lower. We tested whether urban Bolivia samples-poorer (Bol-p) and better-off (Bol-b)-have lower progesterone than a Chicago (USA) sample, and whether progesterone and rate of ovulation are lower in Bol-p than in Bol-b. METHODS: Serial salivary samples collected from Bolivians, screened according to strict exclusion criteria during two complete menstrual cycles, were radioimmunoassayed for progesterone; anthropometrics were collected at mid-follicular and mid-luteal phases. RESULTS: Progesterone levels are lower in the Bolivia samples, and higher in the Bol-b than Bol-p; ovulation rate is greater in Bol-b than Bol-p. For only ovulatory cycles, mean-follicular-P (pmol/l), mean-luteal-P (pmol/l), and mean-peak-P (pmol/l) are respectively 65, 142 and 208 in Bol-p; 76, 167 and 232 in Bol-b; and 96, 240 and 330 in Chicago. Principal components representing body-size and progesterone level are positively correlated (r = 0.404, P = 0.005). CONCLUSIONS: Progesterone levels appear to be influenced by chronic and acute ecological conditions, evidenced by the association with body-size and the probability of ovulation respectively. These findings have implications for understanding cancer aetiology, developing population-appropriate hormonal contraceptives, and modelling the evolution and functioning of the reproductive system.

Adult↗