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Biomedical subjects

P T Ellison

Publications and source records attributed to P T Ellison.

At least 19 recordsLinked to original sources
PubMed1994

Reference values for luteal progesterone measured by salivary radioimmunoassay.

OBJECTIVE: To establish age-stratified reference values for salivary luteal P levels. DESIGN: One hundred thirty-six regularly menstruating women (18 to 48 years of age), screened for weight, exercise, and steroid medication use, collected daily saliva samples for one complete menstrual cycle. Luteal P levels were measured by 3H-RIA, and data were aligned by day of next menstrual onset. Means (+/- 1 SD range) and percentiles, calculated using both untransformed and log transformed data, were calculated for each luteal day and for indices of luteal P production. RESULTS: Reference values for salivary daily luteal P levels and indices of luteal P are presented for three age groups (18 to 24 years, 25 to 39 years, and 40 to 48 years). CONCLUSION: The age-stratified reference values presented here can be used, without collateral clinical procedures, to assess salivary luteal P levels. Salivary monitoring is ideally suited for research and long-term clinical observation, but the characteristics of salivary P data may limit the usefulness of these values for individual diagnosis.

Adolescent↗
PubMed1993

Brief communication: effect of coca-leaf chewing on salivary progesterone assays.

Although there is evidence for reduced fertility in Andean and Himalayan populations at higher altitudes, factors other than hypoxia may be primarily responsible. A valuable approach in the investigation of these fertility determinants is the use of salivary steroid assays. However, coca-leaf chewing--a ubiquitous practice among high altitude Andean populations--has negative consequences for the accurate measurement of ovarian steroids. This report evaluates the effects of coca-leaf chewing on assays of salivary progesterone. Study participants include naive and habitual users of coca leaf from La Paz and El Alto, Bolivia. Approximately 300 saliva samples were collected immediately before, during, and after coca-leaf chewing. The series includes samples with and without the alkaloid enhancer typically used by coca-leaf chewers. Coca chewing produces false salivary progesterone values that mimic luteal phase values. On the basis of this study, an appropriate protocol is developed for the collection of salivary samples in coca-leaf chewing populations. These results verify the feasibility of salivary assays, even for very difficult field conditions, and highlight the necessity of establishing suitable collection procedures before full field implementation of saliva sampling.

Adult↗
PubMed1993

The ecological context of human ovarian function.

New methods for monitoring ovarian function have allowed an extension of research venue beyond typical clinical settings to studies of human populations in their natural settings. Such studies have confirmed that patterns of variation in ovarian function with age and energetic factors are general features of human reproductive biology. Age patterns of ovarian function are extremely robust across populations of distinct genetic, ecological and cultural backgrounds. Comparable ovarian responses to energetic stresses are likewise observable in different populations where they arise as correlates of local ecologies rather than as correlates of voluntary patterns of diet or exercise. Maternal age and energetic factors also appear to interact with lactation in the modulation of postpartum, ovarian function. Average levels of ovarian function, however, differ considerably between populations, perhaps correlated with chronic environmental conditions that affect growth, development, and the establishment of adult set-points. Western populations appear to represent an extreme of the spectrum of variation in ovarian function, a fact which may relate to the epidemiology of breast and ovarian cancer.

Aging↗
PubMed1993

Seasonality of reproductive function and weight loss in rural Nepali women.

Menstrual and hormonal disturbances have been reported in thin, dieting and exercising Western women, and also recently in rural African women. A study of salivary progesterone profiles was undertaken in a Nepali population to examine whether seasonal increases in workload and changes in energy balance influenced ovarian function. Women's energy expenditure levels were moderately heavy in the winter and very heavy in the monsoon, and body mass fluctuated by -2.8 to +4.8 kg. Samples were collected from 24 normally menstruating women in two seasons, each individual serving as her own control. Progesterone levels were significantly depressed in the monsoon relative to winter for women who lost weight, but not for women who gained weight, indicating that energy imbalance is associated with a loss of fecundity. No differences in body mass index were found between women who lost or gained weight. Progesterone levels were age-dependent, and the degree of hormonal disturbance between age-groups was related to weight loss. The study demonstrates seasonal changes in the fecundity of hard-working Nepali women and a direct link between ovarian function and weight loss (negative energy balance), which is independent of current nutritional status.

Adolescent↗
PubMed1992

Normative study of age variation in salivary progesterone profiles.

Daily luteal progesterone levels were measured for 124 regularly menstruating women, aged 18-44, by radioimmunoassay of steroid levels in saliva. A consistent pattern of age variation in luteal function was found, with the lowest levels of progesterone in the 18-19-year-old and 40-44-year-old groups, the highest values in the 25-34 year olds, and intermediate values in the 20-24 and 35-39-year-old groups. The striking similarity of this pattern of age variation with empirically and theoretically generated curves of apparent fecundability, suggests that age-related changes in ovarian function may underlie observed age variation in fecundability.

Adolescent↗
PubMed1992

The ecology of birth seasonality among agriculturalists in central Africa.

The Lese are subsistence farmers living in the Ituri Forest of north-east Zaïre. They exhibit significant birth seasonality, with lowest frequencies of conception when food production is least, nutritional status is low and ovarian function, as measured by salivary steroid hormone levels, is reduced. Efe pygmy foragers, who live in the same geographical area but are less dependent on cultivated foods and have a more flexible life style, do not exhibit frequent fluctuations in nutritional status nor significant birth seasonality. These findings support a model of birth seasonality relating climatic variables to variation in fertility through a causal chain linking rainfall to food production to energy balance to ovarian function to fertility. The model, which emphasises an ecological approach to the study of human reproduction, should have broad applicability since seasonality of food production and energy balance is widespread geographically and across a wide variety of economies and cultures.

Agriculture↗
PubMed1992

Menstrual variation in salivary testosterone among regularly cycling women.

To determine menstrual variation in salivary testosterone daily saliva samples were collected from 20 regularly cycling women. Results indicate that the menstrual profile of salivary testosterone for both ovulatory and anovulatory cycles exhibits local peaks during the follicular phase and at midcycle, as well as a luteal trough. However, the testosterone profile for anovulatory cycles exhibited a later midcycle peak than that for ovulatory cycles, as well as significantly higher average testosterone levels. These results extend the observation of a midcycle peak in serum testosterone to saliva and suggest the existence of a follicular peak in unbound testosterone coincident with the early androgen production of a cohort of developing follicles.

Adult↗
PubMed1990

Salivary measurement of episodic progesterone release.

Episodes of luteal progesterone release which have been identified from serum samples can also be observed in saliva. Components of these release episodes--amplitude, duration, and frequency--can be separated and characterized. In a sample of 16 cycle days collected from 6 normal women, pulse duration and frequency increased significantly from the early to the mid-luteal phase, and then decreased by the late luteal phase (2-4 days before menses). Pulse amplitude also increased early to mid-luteal, but continued to increase significantly into the late luteal, and did not decline until the peri-menstrual phase (0-1 days before menses). Circadian variation, previously considered unimportant for progesterone, was also observed in late luteal samples. Extension of studies of ultradian release characteristics to groups known to vary from controls in broad-scale progesterone patterns, such as young, nutritionally stressed, or exercising women, should help to elucidate the potential functional significance of fine-grained release components. Such knowledge can also inform protocols of anthropological studies which seek to identify broad progesterone patterns or to classify and compare reproductive status.

Adult↗
PubMed1989

Ecology and ovarian function among Lese women of the Ituri Forest, Zaire.

Ovarian function is examined in 35 Lese women inhabiting the Ituri Forest of northeastern Zaire over a period of 4 months through measurements of progesterone in saliva samples collected twice weekly. Ovulatory frequency is found to be only 56% on average, with a pattern of age variation similar to that observed in western women, though lower in level at each age. Average luteal progesterone levels of the Lese women are lower than those of Boston controls even if only ovulatory cycles are considered. Women with the poorest nutritional status, inferred from longitudinal weight changes and weight for height, show the greatest compromise of ovarian function, and the average ovulatory frequency of the whole sample declines in parallel with a period of weight loss over four months. It is suggested that low ovulatory frequency and luteal insufficiency contribute to the low fecundity of the Lese population and that nutritional status is likely to be one of the ecological factors modulating this effect.

Adult↗
PubMed1989

Anomalously low endemic goiter prevalence among Efe pygmies.

The existence of endemic goiter, caused by iodine deficiency and the presence of a dietary goitrogen, has been noted in eastern Zaire by a number of authors (De Visscher et al.: Journal of Clinical Endocrinology and Metabolism 21:175-188, 1961; Delange et al.: Journal of Clinical Endocrinology and Metabolism 34:1059, 1972). In the Ituri Forest of Huate-Zaire, two distinct populations, the Efe (pygmy) and Lese (Bantu), live in association with each other and have similar diets. The goiter survey reported here documents differences in goiter prevalence and severity between the nomadic pygmy and village-living Bantu populations. While the Efe have an overall goiter prevalence of 9.4%, the Lese have a goiter prevalence of 42.9%. Furthermore, Efe women living in Lese villages and subsisting on a Lese diet have a prevalence of goiter similar to that of forest-living Efe women. Village-living individuals born of Efe mothers and Lese fathers have a prevalence of goiter greater than that of pure Efe but less than that of Lese. While our data cannot exclude dietary explanations for the difference in goiter prevalence between the Efe and Lese, they do support the hypothesis that the Efe possess an adaptation to an iodine-deficient environment that does not result in the development of goiters.

Adolescent↗
PubMed1987

Low profiles of salivary progesterone among college undergraduate women.

High incidences of amenorrhea and oligomenorrhea are often found among late adolescent, college-aged women. We studied menstrual profiles of salivary progesterone in 17 undergraduate women (average age 20.2 years) who were experiencing regular menstrual cycles, and compared the results with similar data obtained from older women, both recreational runners (30.7 years) and nonexercising controls (29.3 years), to see whether this late adolescent population showed evidence of compromised luteal function not manifested by menstrual irregularity. The profiles obtained from the undergraduates and the older women were similar in shape but different in level. The undergraduate profiles were significantly lower than the controls (average progesterone level during the luteal phase, 154 +/- 14 versus 287 +/- 30 pmol/L; peak progesterone level, 352 +/- 35 versus 655 +/- 46 pmol/L; mean +/- SE, p less than 0.01), and remained at a significantly elevated level for fewer days (1.3 +/- 0.4 versus 4.5 +/- 0.6 days, p less than 0.01). The undergraduates were more comparable in all measures to the older women runners; however, reported exercise and weight differences did not account for the low levels in the undergraduates. We suggest that the low progesterone levels in the undergraduates reflect an extended process of ovarian maturation that does not culminate until the mid to late twenties.

Adult↗
PubMed1986

Moderate recreational running is associated with lowered salivary progesterone profiles in women.

Salivary progesterone profiles were studied in a group of recreational women runners (average 12.5 miles per week) and nonexercising control subjects. Although no differences were observed in the average cycle lengths of the two groups, luteal progesterone levels, both peak and average, were found to be significantly lower in the runners. A salivary progesterone level two standard deviations above the follicular phase average was used to discriminate luteal activity with 95% confidence. Runners averaged fewer days with sample values two standard deviations above this level and a shorter average interval between first and last samples observed above this level. However, no evidence was found of a delayed luteal progesterone rise among the runners. These results suggest that even moderate amounts of aerobic exercise may have effects on female reproductive function which would not be suspected from menstrual patterns alone.

Adult↗