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Biomedical subjects

R C Bonney

Publications and source records attributed to R C Bonney.

At least 55 records · Page 3Linked to original sources
PubMed1985

Observations on variability in LH release and fertility during oestrus in the domestic cat (Felis catus).

Hormonal changes, behaviour, ovulation and fertility were examined in response to coitus at two different times during oestrus in the female domestic cat housed in conditions of natural light (N = 13). On Day 2 or Day 4/5 of oestrus females were allowed 1 copulation in 15 min (single matings) or 2-3 copulations in 30 min (multiple matings). Plasma LH, oestradiol-17 beta and progesterone concentrations during the 24-h period after coitus were measured by radioimmunoassay; ovulation was assumed to have occurred if progesterone values were elevated 7-30 days after coitus. With the exception of 2 out of 3 animals receiving single matings on Day 2 of oestrus, all animals showed subsequent elevated progesterone values. Females receiving multiple matings had significantly greater releases of LH as measured by the area under the curve than those receiving single matings. There was significantly greater variability in the LH response of queens on Day 2 of oestrus compared to those on Day 4/5 for peak values and area under the curve; the only failure in release of LH was in queens on Day 2. Oestradiol levels did not differ significantly between Day 2 and Day 4/5 of oestrus. Progesterone values remained less than 1 ng/ml for 24 h after coitus. Both LH peak values and area under the curve were significantly greater for animals that became pregnant. There were also significant differences in coital behaviour between queens on Day 2 and those on Day 4/5 of oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Measurement of phospholipase A2 activity in human endometrium during the menstrual cycle.

Phospholipase A2 activity was measured in human endometrium throughout the menstrual cycle using an assay based on the liberation of oleic acid from 1-palmitoyl-2-[14C]oleoyl phosphatidylcholine. The enzyme was shown to be calcium dependent, to have an optimum pH of 8-9 and an apparent Michaelis constant of 110 mumol/l. Enzyme activity was low in early proliferative-phase tissue (6.08 +/- 1.42 (S.E.M.) pmol oleic acid released/mg protein per min) but rose significantly (P less than 0.01) during the late proliferative phase (10.86 +/- 2.79 pmol/mg per min). There was a tenfold increase in activity 2-4 days after ovulation (45.6 +/- 13.6 pmol/mg per min) which thereafter declined to reach values which at menstruation were not significantly different from those of the proliferative phase (4.5 +/- 1.76 pmol/mg per min). The results indicate that phospholipase A2 activity in human endometrium is related to the stage of the menstrual cycle and suggest that arachidonic acid release may be influenced by oestradiol and progesterone.

Adult↗
PubMed1984

The interrelationship between plasma 5-ene adrenal androgens in normal women.

Plasma concentrations of 5-androstene-3 beta,17 beta-diol (ADIOL) dehydroepiandrosterone (DHA) dehydroepiandrosterone sulphate (DHAS) and cortisol were measured by radioimmunoassay in a group of women aged between 27 and 88 years of age. There was a significant negative correlation with increased age for all three adrenal androgens but not for cortisol. The decrease in adrenal androgens was not related to an excessive divergence from ideal body weight. There was a highly significantly positive correlation between plasma concentrations of all three adrenal androgens which supports a metabolic interrelationship.

Adult↗
PubMed1984

Adrenal androgen concentrations in breast tumours and in normal breast tissue. The relationship to oestradiol metabolism.

Concentrations of ADIOL, DHA and DHAS were measured in human breast tumours and normal tissue from the same breast and related to 17 beta-hydroxysteroid dehydrogenase (17 beta HSD) activity in these tissues. ADIOL and DHA were significantly higher in tumour tissue compared to normal tissue from the same breast (paired t-test: P less than 0.05 and P less than 0.01 respectively) whereas the difference between concentrations of DHAS in normal tissue and tumour tissue was not significant. There was a positive correlation between ADIOL and DHA in both tissues (P less than 0.001) but for DHAS the relationship was only significant in normal tissue (ADIOL:DHAS, P less than 0.001; DHA:DHAS, P less than 0.002). An increase in 17 beta-HSD activity was associated with an increase in DHAS concentrations in both normal and tumour tissue (P less than 0.01 and P less than 0.001 respectively) and with an increase in DHA concentrations in normal tissue (P less than 0.05). These results might be explained by an impairment in the balance between sulphatase and sulphotransferase activity in breast tumours.

17-Hydroxysteroid Dehydrogenases↗
PubMed1984

Adrenal androgen concentrations in endometrium and plasma during the menstrual cycle.

Concentrations of 5-androstene-3 beta, 17 beta-diol (androstenediol), dehydroepiandrosterone (DHA) and DHA sulphate (DHAS) were measured in endometrium and plasma from normal premenopausal and perimenopausal women (average ages 37 and 48 years respectively) at different stages of the menstrual cycle. Plasma levels did not vary with the stage of the cycle for any of the three steroids. Mean plasma levels of androstenediol ranged between 2.03 and 2.92 nmol/l for premenopausal women and 1.38 and 1.58 nmol/l for perimenopausal women while mean concentrations of DHA were 20.80-36.41 nmol/l (premenopausal women) and 13.87-19.07 nmol/l (perimenopausal women). The values for DHAS were more variable and ranged between 3.20 and 4.56 and 2.94 and 4.25 mumol/l for pre- and perimenopausal women respectively. In premenopausal women endometrial tissue concentrations of androstenediol and DHA increased three to fourfold in the secretory phase while no increase was observed in DHAS. There was a similar increase in androstenediol but not DHA or DHAS during the secretory phase for perimenopausal women. A significant positive correlation was found for tissue androstenediol and DHA in both groups of women but the relationship between DHAS and the other androgens was significant only for perimenopausal women. We suggest that the increase in androstenediol and DHA concentrations could be due to an increase in a receptor or binding protein, possibly progesterone dependent, present in secretory phase endometrium.

Adult↗
PubMed1983

Inhibition of 17 beta-hydroxysteroid dehydrogenase activity in human endometrium by adrenal androgens.

The effect of dehydroepiandrosterone sulphate (DHA-S) and its metabolites dehydroepiandrosterone (DHA) and 5-androstene-3 beta, 17 beta-diol (ADIOL) on the activity of 17 beta-hydroxysteroid dehydrogenase in human endometrial tissue was investigated by an isotope ratio technique. The apparent KM for oestradiol was 1.59 X 10(-6) M. All three androgens inhibited the metabolism of oestradiol and the apparent Ki values were: ADIOL, 2.05 X 10(-6) M; DHA-S and DHA, 1.59 X 10(-6) M. However, ADIOL acted by direct competition with oestradiol for the active enzyme site whereas inhibition by DHA and its sulphate was non-competitive. DHA-S and DHA were more potent inhibitors of oestradiol metabolism than was ADIOL. These results support the hypothesis that adrenal androgens could be involved in the development of endometrial hyperplasia and adenocarcinoma. Inhibition of oestradiol metabolism could increase the concentration of oestradiol in endometrial tissue and if unopposed by progesterone, e.g. after the menopause or in subjects with ovulatory defects, could stimulate abnormal endometrial growth.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Endometrial tissue and plasma concentrations of 5-androstene-3 beta, 17 beta-diol during the menstrual cycle in normal premenopausal and perimenopausal women.

A radioimmunoassay for 5-androstene-3 beta, 17 beta-diol (ADIOL) in human endometrium and plasma is described. The recognised criteria of reliability have been fulfilled. Plasma and endometrial tissue concentrations of ADIOL were determined in samples obtained from normal premenopausal and perimenopausal women (average ages 37 and 48 years respectively) at different phases of the menstrual cycle. In perimenopausal women plasma concentrations of ADIOL did not vary throughout the cycle (proliferative phase: 411 +/- 95 (SEM) pg/ml; secretory phase: 462 +/- 28.5 (SEM) pg/ml). For the premenopausal group the pattern was similar (proliferative phase: 568.4 +/- 56.9 (SEM) pg/ml; secretory phase: 663.1 +/- 64.7 (SEM) pg/ml) although a significant difference (P less than 0.05) was noted between late proliferative and late secretory phase levels in these women. A different pattern was observed for endometrial tissue concentrations of ADIOL. In both groups of women a significant (3-4-fold) increase occurred during the secretory phase. There was no apparent relationship between plasma and tissue concentrations of ADIOL either during the proliferative or the secretory phase. There was, however, an age associated decrease for both tissue and plasma ADIOL. Theories are proposed to account for the increase in ADIOL concentration during the luteal phase.

Adult↗
PubMed1983

The relationship between 17 beta-hydroxysteroid dehydrogenase activity and oestrogen concentrations in human breast tumours and in normal breast tissue.

The activity of 17 beta-hydroxysteroid dehydrogenase (17 beta HSD) was measured in human breast tumours and in normal breast tissue from premenopausal, perimenopausal and postmenopausal women. Enzyme activity was higher in tumour tissue than in normal tissue from the same breast and under the conditions of the assay the oxidation of oestradiol was higher than the reduction of oestrone. The physiological status of the women in the study did not relate to the activity of the enzyme in either normal or tumour tissue although fibroadenomas had less activity than adenocarcinomas. In postmenopausal women tumour tissue oestrogens were 2-3 fold higher than in normal tissue from the same breast. Furthermore, tumour tissue concentrations of oestradiol tended to be higher than those of oestrone although in normal tissue the two oestrogens were present in similar concentrations. In plasma from the same women oestrone was the predominant oestrogen. There appears to be no direct relationship between 17 beta HSD activity and oestrogen concentrations but the enzyme may play a part in determining the balance between oestrone and oestradiol according to substrate and cofactor availability.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Hormonal changes in the immature rat after administration of pregnant mare serum gonadotrophin: influence of body weight.

We have shown previously that pregnant mare serum gonadotrophin (PMSG) induces ovulation only in rats weighing over 60 g on the day of injection. The under-60 g rats do not ovulate although they secrete a preovulatory surge of a pleiomorphic form of LH. Presumably this pleiomorph is inactive. Comparisons were made of plasma hormone concentrations in rats treated with PMSG that weighed over and under 60 g. The measurements were made on samples taken between 13.00 and 22.00 h on the day of the expected preovulatory LH surge. Prolactin and corticosterone levels were lower in the lighter group compared with the heavier group. A midday pulse of GH detected in the over-60 g animals did not occur in the under-60 g group. Levels of ACTH were slightly higher in the under-60 g rats and together with the low corticosterone concentrations indicate adrenal insensitivity. Oestradiol, progesterone and TSH concentrations were the same in the two groups. Since progesterone secretion is under LH control, the 'inactive' pleiomorphic form of LH must have steroidogenic activity. There was an indication that the under-60 g rats also secreted a pleiomorphic form of FSH. Reports in the literature indicate that prolactin, corticosterone and GH have a positive modulatory influence on natural puberty. They may also influence precocious puberty induced by PMSG, since in the unresponsive under-60 g rat plasma levels of these three hormones were low. Perhaps the release of one or more of these hormones is dependent upon the physical maturity of the animal as represented by body weight.

Adrenocorticotropic Hormone↗
PubMed1982

Endocrine correlates of behavioural oestrus in the female giant panda (Ailuropoda melaneleuca) and associated hormonal changes in the male.

Urinary excretion of oestrogens and androgens by a pair of giant pandas was monitored by radioimmunoassay during behavioural oestrus through two successive breeding seasons. The excretion of oestrogens by the female was at a maximum during the proceptive period and lower during the period of receptivity. In the first breeding season studied, elevated androgen excretion in the male coincided with peak receptivity in the female. The study indicates that accurate timing of natural mating or artificial insemination could be achieved by monitoring oestrogen excretion in the female.

Androgens↗
PubMed1981

Displacement of the optic nerve head. Response to acute intraocular pressure elevation in primate eyes.

Mechanical compression of axons within the lamina scleralis has been suggested as a mechanism of damage in glaucoma. Movement within the optic nerve head was studied after acute intraocular pressure elevation in the enucleated primate eye. Fine platinum wire was positioned with the lamina scleralis and displacement characterized after IOP elevation. These studies demonstrate the following: (1) retrodisplacement increases significantly with increasing pressure, (2) maximum retrodisplacement occurs at the center and minimum retrodisplacement occurs at the periphery of the optic nerve, (3) retrodisplacement at the position of minimum movement in the optic nerve is indistinguishable from that in the sclera, (4) 67% of the net retrodisplacement occurs after a 15-mm Hg increase in IOP, and (5) tangential displacements within the lamina scleralis also increase with increasing pressure but are only 50% of the magnitude of retrodisplacements.

Animals↗
PubMed1981

Plasma concentrations of oestradiol-17 beta and progesterone, and laparoscopic observations of the ovary in the puma (Felis concolor) during oestrus, pseudopregnancy and pregnancy.

Plasma levels of oestradiol and progesterone in 3 pumas during oestrus and artificially induced pregnancy and pseudopregnancy were determined by radioimmunoassay. During oestrus, basal levels of oestradiol (5-30 pg/ml) were interrupted by surges of 30-375 pg/ml at intervals of 17-25 days. Considerable variation occurred between and within animals. Periods of oestrus and follicular development were confirmed by laparoscopy and vaginal smear patterns. Absence of an increase in plasma progesterone following elevated levels of oestradiol and failure to observe corpora lutea in the ovary indicated that ovulation was probably not spontaneous. Plasma oestradiol values rose dramatically in response to PMSG but were low during pseudopregnancy until the return to oestrus. During pregnancy surges of oestradiol occurred at mid-term and immediately before parturition. Ovulation, confirmed by laparoscopy, occurred 24-48 h after hCG and progesterone levels (usually less than 2 ng/ml) then increased to reach 150-300 ng/ml on Days 24-28. In the pseudopregnant animals progesterone concentrations had returned to baseline by Days 45-50 but during pregnancy progesterone remained elevated, declining only gradually to basal values by Day 85. A minor peak of progesterone, coincident with the pre-partum oestradiol surge, occurred on Day 87, 1 week before parturition on Day 95.

Animals↗
PubMed1980

Plasma concentrations of oestradiol-17 beta, oestrone, progesterone and testosterone during the ovarian cycle of the owl monkey (Aotus trivirgatus).

Oesterone, oestradiol-17 beta, progesterone and testosterone were measured by radioimmunoassay in daily plasma samples throughout the ovarian cycle in 4 female owl monkeys. Clearly defined peaks of oestradiol-17 beta occurred at intervals of 15.5 +/- 0.56 days and confirmed the length of the cycle reported previously. Progesterone rose on the day on the day of the oestradiol-17 beta to reach a maximum 4--6 days later, thereafter decreasing gradually to low levels before the onset of the next cycle. On the basis of these data the follicular and luteal phases were estimated to be 6 and 10 days respectively. Osterone and testosterone peaks preceded that of progesterone by 24 and remained elevated throughout the luteal phase. Plasma concentrations of all steroids were markedly higher than for other primate species. Vaginal cytology was considered unsuitable as an indicator of the stage of the ovarian cycle.

Animals↗