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Biomedical subjects

P T Ellison

Publications and source records attributed to P T Ellison.

33 records · Page 2Linked to original sources
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↗
PubMed1981

Threshold hypotheses, development age, and menstrual function.

Hypotheses relating the onset and maintenance of menstrual function to threshold levels of various parameters have been subject to statistical critique. Analysis of trends in parameter variance, applied here to data from the Berkeley Guidance Study, discriminates between the predictions of such hypotheses and those of the more traditional concept of developmental age.

Adipose Tissue↗
PubMed1981

Prediction of age at menarche from annual height increments.

The divergence in height velocity of early and late maturing girls in early adolescence is exploited to predict menarcheal age from a year's growth in height. Simple prediction equations are generated based on data from the Berkeley Guidance Study, and are subsequently tested against an independent sample from the Stuart Growth Study. The success of this prediction method compares favorably with others based on x-ray determinations of bone age; it is much more successful than a proposed method that utilizes estimations of body fat. The height increment method is recommended both by its simplicity and by the relative accessability of the information involved.

Adolescent↗
PubMedDate not supplied

Correlations of basal oestrogens with adrenal androgens and relative weight in normal women.

Serum levels of androstenedione, dehydroepiandrosterone, dehydroepiandrosterone-sulphate, cortisol, oestrone, and oestradiol are studied in 24 normal young women, and variation in basal oestrogen levels is examined in relation to adrenal androgen levels and relative weight. Between subjects no positive correlation is found between adrenal androgen levels or relative weight and basal oestrogen. Within subjects changes in adrenal androgen levels are positively correlated with changes in basal oestrogens. The results suggest that the basal oestrogen setpoint within each individual is unaffected by weight differences in the normal range, while variation about the setpoint within individuals may accompany fluctuations in adrenal androgen levels. This conclusion is discussed in relation to previous suggestions that relative weight, through an effect on extragonadal oestrogen production, may have an influence on female fecundity.

Adolescent↗