Search PubMed⌕ Search

Biomedical subjects

N R Adams

Publications and source records attributed to N R Adams.

At least 55 records · Page 3Linked to original sources
PubMed1981

Characteristics of oestrogen-induced refractoriness in ovine cervical secretion.

Ovariectomized ewes treated with oestradiol benzoate (OB) had a reduced cervical mucus response to subsequent treatment with OB. This refractory effect was observed 48 h after a single dose of OB, but could be postponed until 72 h by a second dose of OB at 24 h. This postponement did not occur in animals which were recovering from previously induced refractoriness. Less mucus was recovered from refractory ewes, and it had an increased proportion of dry matter and normal Spinnbarkeit. Pretreatment of ewes with 10 mg progesterone for 10 days decreased the proportion of dry matter and increased the Spinnbarkeit of mucus collected after stimulation with OB. This change was different from that produced by increasing the dose of OB. Progesterone given to ewes after 10 days treatment with OB had a detectable effect on cervical mucus, but it did not specifically decrease refractoriness. The cervix provides a convenient site for studying oestrogen-induced refractoriness in the ewe, without possible confusion by an effects of progesterone.

Animals↗
PubMed1981

A changed responsiveness to oestrogen in ewes with clover disease.

When clover-infertile ewes are subsequently exposed to non-oestrogenic pasture, they have a reduced fertilization rate, due to an inability to store spermatozoa in the cervix, and the cervical mucus has a reduced spinnbarkeit, caused by a slower response to oestrogenic stimulation. Vaginal cell keratinization and oestrous behaviour occurred more slowly after treatment of affected ewes with oestrogen. Other changes in affected ewes suggest that phyto-oestrogens have permanent mild differentiating effects on adults. Sexual behaviour is masculinized, the cervix takes on a uterine-like appearance and the genital tract becomes permanently oestrogenized. The manner in which these changes relate to the altered responsiveness to oestrogen remains to be clarified.

Animals↗
PubMed1981

Abnormal function of the corpus luteum in some ewes with phyto-oestrogenic infertility.

Ewes with permanent phyto-estrogenic infertility show oestrus less regularly than normal ewes, and the present study examines the extent to which this results from abnormal ovarian function. Forty-nine affected ewes and 53 controls were run with rams fitted with marking crayons and harnesses, and crayon marks were recorded and laparoscopy performed at weekly intervals for 3 weeks. Fewer affected ewes showed oestrus accompanied by ovulation (28 v. 49, P less than 0.001), and four of these affected ewes had a second ovulation during the experiment. More of the ovulations observed in affected ewes were unaccompanied by behavioural oestrus than in controls (8 out of 38 v. 2 out of 50; P less than 0.05). Six affected ewes had no corpus luteum or oestrus, and five of these had adhesions over the genitalia. Hydrops uteri in five other affected ewes was accompanied by prolonged maintenance of the corpus luteum. Some other abnormalities were also observed. In a second study, plasma progesterone concentrations were measured twice daily in 12 affected ewes which were run with rams. Five ewes had oestrous cycles of abnormal duration (two of more than 23 days, two of 21 days, and one of 11 days), and these were accompanied by plasma progesterone patterns different from those of the ewes with an oestrous cycle duration of 16-18 days. It is concluded that the irregular oestrous cycles in affected ewes are due mainly to abnormal life span and progesterone secretion by the corpus luteum, which in turn largely result from changes in the uterus.

Animals↗
PubMed1980

Toxic effects of large amounts of DL-methionine infused into the rumen of sheep.

Four Merino wethers were fed ad libitum on a roughage diet comprised of equal parts of chopped lucerne hay and oaten chaff. The sheep received continuous infusions of DL-methionine into the rumen; the daily dose increasing from 0 g (control treatment) up to 30 g in 3 g amounts at weekly intervals. Dry matter intake (DMI) fell below the control level when 24 g/day or more of the amino acid was infused, while plasma free methionine levels increase substantially when 30 g/day was given. There was no effect of DL-methionine supplementation on the bodyweight of the animals. However, when 30 g/day of DL-methionine was infused one animal died and the acute condition of 2 others necessitated their slaughter. Significant lesions included acute nephrosis and haemolytic anaemia, with milder changes in the liver and pancreas. This report indicates that sheep are unlikely to show the kind of chronic methionine toxicity seen in other species.

Amino Acids↗
PubMed1980

Effect of equol on oestrogen receptors and on synthesis of DNA and protein in the immature rat uterus.

In immature, 3-week-old female rats, 5 mg equol given by subcutaneous injection increased uterine wet weight 24 h later to the same degree as did 5 microgram oestradiol-17 beta. At this dose there was more receptor complex binding to the nucleus in the equol-injected rats than in the rats injected with oestradiol-17 beta even after 6 h. However, the equol-receptor complex that bound to the nucleus was more extractable with 0 x 3 M-KCl. In the equol-injected rats the duration of uterine growth was shorter and there was less receptor replenishment and synthesis of protein and DNA than in the rats injected with oestradiol-17 beta 30 h after either injection. It was concluded that equol is a weakly oestrogenic compound which is antagonistic to oestradiol-17 beta by competing with oestradiol-receptor complex for nuclear binding and yet fails to initiate the replenishment of oestrogen receptors effectively in the cytoplasm.

Animals↗
PubMed1979

Depressed incidence of oestrus in ewes with clover disease at the beginning of the breeding season.

The incidence of oestrus was depressed in ewes with permanent clover infertility running on non-oestrogenic pasture, particularly in the first part of the breeding season. The depression was due to the failure of some ewes to display oestrus, and to a more erratic pattern of oestrous activity in the other ewes. The incidence of oestrus was restored to normal by treatment with progesterone. In contrast, the incidence of oestrus was reduced in affected ewes grazing in oestrogenic pasture.

Animals↗
PubMed1979

Masculinisation of the external genitalia in ewes with clover disease.

Prolonged exposure of ewes to oestrogenic pasture resulted in partial fusion of the labia of the vulva and hypertrophy of the clitoris. Partial fusion of the labia was also seen in ewes which had grazed oestrogenic pastures on normal commercial properties, and was related to the amount of histological change in the cervix. This lesion may be useful as a screening test for previous exposure to oestrogenic pasture.

Animals↗
PubMed1979

Altered response of cervical and vaginal epithelia to oestradiol benzoate in ewes after prolonged exposure to oestrogenic pasture.

Ovariectomized ewes, 10 clover disease infertility and 10 controls, were injected daily for 3 days with 25 micrograms oestradiol benzoate. At the end of this period, the Spinnbarkeit of cervical mucus and the keratinization of the vaginal epithelium were less in the infertile ewes. It is suggested that the infertility in clover-affected ewes is due to an inability of target organs to give a continued response to the 'priming' action of oestrogen.

Animals↗
PubMed1979

Changes in ovine cervical mucus in response to oestrogen treatment.

After 10 days pretreatment with 10 mg progesterone daily, ovariectomized ewes were injected i.m. with 12.5, 25, 50 or 100 micrograms oestradiol benzoate (OB) and cervical mucus was collected 16, 24, 32, 40 and 48 h later (Exp. 1), or were injected with 12.5, 40 or 100 micrograms OB daily, and the mucus examined, for 9 days (Exp. 2). The Spinnbarkeit was affected by the dose of OB over 9 days, but at all doses it increased over the first 3 days of treatment (Exp. 2). The wet weight of the mucus, the amount and proportion of water, and therefore the degree of arborization, increased with the dose of OB but decreased after 3 days in Exp. 2. The amount of dry matter, protein or carbohydrate did not have any clear relationship to dose or duration of OB treatment.

Animals↗
PubMed1979

Increase in plasma cortisol concentrations in ewes fed oestrogenic subterranean clover.

Pen-feeding oestrogenic clover to ewes increased their plasma cortisol concentration by the third day. This was not due to any change in the variation of cortisol concentration with time of day. Ovulation rate was not affected during the experiment as judged by the levels of plasma progesterone and laparoscopy. The plasma cortisol concentration of ewes also rose within three days of their being placed on oestrogenic clover pasture. During the next 21 days, their mean plasma cortisol was increased by 58 per cent. A previous history of clover disease did not affect this response.

Animal Feed↗
PubMed1978

Enzyme activities and protein and carbohydrate concentrations in cervical secretions at dioestrus in normal ewes and ewes with permanent phytooestrogenic infertility.

Cervical secretions of clover-affected and control ewes in the luteal phase of the ovarian cycle were obtained by flushing the anterior vagina. The flushings were analysed for proteins, carbohydrates and enzyme activities, and were found to be similar to the secretions of the normal ovine uterus. There was significantly more protein, carbohydrate and acid-soluble glycoprotein but less alkaline phosphatase, N-acetylglycosidases (EC 3.2.1.30 and 3.2.1.53) and ribonuclease I in the vaginal flushings of clover-affected ewes. The observed changes were not due to more inflammation in the cervix of clover-affected ewes as there were fewer bacteria, leukocytes and epithelial cells and no elevation of lysozomal enzyme activities in their flushings. It is suggested that the cervix of the clover-affected ewe behaves as though under a stronger than normal oestrogenic stimulation during dioestrus.

Animals↗