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Biomedical subjects

J P Tyler

Publications and source records attributed to J P Tyler.

66 records · Page 4Linked to original sources
PubMed1978

The measurement of steroid glucuronides in urine from mice to monitor gonadal function. I. Pregnanediol-3 alpha-glucuronide as an index of progestogen output.

An attempt has been made to assess the output of progesterone in mice by measuring the concentration of pregnanediol-3 alpha-glucuronide (PdGl in serial samples of unextracted urine. Longitudinal studies with 95 animals have shown that sufficient urine (greater than 40 microliter) can be obtained from individual animals (80% success rate) without stress every day or at intervals of 2 h. The sc administration of 50 microgram progesterone in lauric acid ethyl ester resulted in a 9-fold increase in the concentration of urinary PdGl (within 4 h) and a significantly elevated output for the next 26 h. During the induction of superovulation with PMS and hCG, the values of PdGl increased significantly (P less than 0.0005; by Student's t test) from 2.08 +/- 0.97 to 3.99 +/- 2.55 ng/ml (mean +/- SD) at the time of corpus luteum formation. There was a good correlation (r = 0.84; n = 154) between the values expressed as nanograms per ml urine and nanograms per mg creatinine. The results demonstrate that the concentration of PdGl in serial samples of urine may be used as an index of gonadal function in female mice.

Animals↗
PubMed1978

Effects of medium composition and progesterone on maturation in vitro of rabbit oocytes from Graafian follicles of different sizes.

Rabbit oocytes from large (1-1.5 mm diam.), medium (0.5 mm) and small (0.15-0.25 mm) antral follicles were cultured in five chemically defined media. In all media, oocytes from large antral follicles showed the highest incidence of meiotic activity followed by those from follicles of medium size. Most oocytes from small follicles did not resume meiosis in culture. The addition of glutamine to a standard medium for ovum culture significantly improved maturation of oocytes from medium-sized follicles but did not affect those from large or small follicles. When polyvinylpyrrolidone was substituted for bovine serum albumin, maturation of oocytes from large and medium-sized follicles was reduced. Progesterone at a concentration of 10 micrometer did not affect maturation, but 100 micrometer-progesterone blocked germinal vesicle breakdown in oocytes from medium-sized follicles and reduced both germinal vesicle breakdown and polar body formation in oocytes from large follicles. This effect was reversible.

Animals↗
PubMed1975

Variations in the concentration of testosterone in peripheral venous plasma from healthy women.

The concentration of testosterone (ng/100 ml; mean +/- SD) has been determined in peripheral venous plasma at 4 hourly intervals for 24 h from 9 non-pregnant women (39.8 +/- 11.8) and 9 during late pregnancy (70 +/- 32). In addition, the level of this hormone has been measured in samples of plasma removed daily (between 08.30 and 10.00 h) throughout 9 ovarian cycles (41.6 +/- 11.8), and weekly from 10 women during gestation (57.6 +/- 14.7). The results show that there is considerable individual variation in both the concentration and pattern in serial samples over the respective time scales. The values of the arithmetic mean from non-pregnant subjects show that there is a tendency for the concentration to be lower between 20.00 and 04.00 h. However, the differences between the values at defined times over a 24 h period are not statistically significant. During the ovarian cycle 3 subjects had peak values during the peri-ovulatory phase, 2 in the luteal, 1 in the follicular and 3 showed no consistent pattern. There was no significant difference in values (40.9 +/- 11.8, 41.9 +/- 11.9 and 41.8 +/- 11.9) for the 3 phases of the cycle. There is a significant rise in the concentration of plasma testosterone during pregnancy (P less than 0.0005), but the pattern of the arithmetic mean is not related to the corresponding values for progesterone or oestradiol. During late pregnancy (34 weeks to term) there is a change in the nycterohemeral pattern, with the highest mean values occurring between 16.00 and 04.00 h. The results are discussed.

Adult↗
PubMed1975

The concentration of testosterone in serial samples of peripheral venous plasma from infertile women.

The concentration of testosterone has been determined in daily samples of peripheral venous plasma throughout one complete menstrual cycle from each of 4 women with regular, but anovulatory cycles (Group 1) and 13 apparently normal, but infertile women (Group 2). The individual patterns and combined values have been compared with those obtained from 9 healthy volunteers (Group 3), who appeared to satisfy strict criteria for normal ovarian and uterine function. The menstrual cycles from subjects in groups 2 and 3 were subdivided retrospectively into follicular, periovulatory and luteal phases according to the day of the LH peak. The results show that the values for every subject in Group 1 tended to remain relatively costant and the overall concentration (32.3 +/- 10.4; ng/100ml; mean +/- SD) was significantly lower (P less than 0,05, student's "t" test) than the corresponding figure for Group 3 (41.6 +/- 11.8). The patterns of testosterone in Groups 2 and 3 were variable, but the overall concentrations in Group 2 during the periovulatory phase (53.7 +/- 12.7) was significantly higher (P less than 0.025) than the corresponding value (41.9 +/- 11.9) for Group 3. The findings are discussed.

Adult↗