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Biomedical subjects

R M Eley

Publications and source records attributed to R M Eley.

16 recordsLinked to original sources
PubMed1993

The effect of high and low dose Theileria parva infection on the reproductive function of Boran/Friesian heifers.

Two separate experiments were carried out to find the effect of infection with low and high doses of Theileria parva sporozoites on the cyclical status of Boran/Friesian cross heifers. In each experiment, ten heifers were infected and another four heifers acted as controls. Routine monitoring of estrous behavior, determination of serum progesterone concentrations and palpation of the ovaries per rectum were used to assess the cyclical status of each animal. Two and eight animals died in the T . parva low (TpL) and high (TpH) dose experiments, respectively. Five of eight recovered animals in the TpL group cycled regularly postinfection, while three others had extended periods of ovarian dysfunction postinfection. Both infected and recovered animals in the TpH-group similarly had extended periods of ovarian dysfunction postinfection. All controls in both experiments cycled regularly throughout the study period. Differences in cyclical status were not related to the febrile response, parasitological or hematological differences. The animals that continued to cycle throughout lost the least amount of weight. Animals that stopped cycling lost between 16 and 29% of their initial body weights postinfection. In conclusion, this study confirmed previous anecdotal evidence that theileriosis has an adverse effect on reproduction. Results of this study suggested that this was as an indirect result of weight loss associated with infection and not directly attributed to pathology of target organs.

Journal Article↗
PubMed1993

Trypanosoma congolense in the microvasculature of the pituitary gland of experimentally infected Boran cattle (Bos indicus).

The pituitary glands of seven Boran cattle (Bos indicus), five infected with a clone of Trypanosoma congolense IL 1180 (ILNat 3.1) transmitted by Glossina morsitans centralis and two uninfected controls, were examined by light and electron microscopy 43 (experiment 2) or 56 (experiment 1) days after fly challenge. The three cattle used in the first experiment included a 15-month-old female (No. 1), a 24-month-old female (No. 2), and a 21-month-old male (No. 3) as a control. In the second experiment, four cattle were used: two females (Nos. 4, 5) and one male (No. 6), all between 15 and 24 months of age, and one female control (No. 7) of similar age. In all the infected animals, dilation of both the sinusoids and microvasculature was apparent, as was an increase in the thickness of the extracellular matrix between the pituitary lobules. Trypanosomes were found in the microvasculature of the adenohypophysis and neurohypophysis in all the infected animals. Focal degenerative changes were seen in the adenohypophyseal section of glands from the infected animals euthanatized 56 days post-infection. These degenerative structural changes were confined to the somatotrophic cells. The possible role that trypanosomes in the microvasculature may play in inducing pituitary damage and dysfunction is discussed.

Animals↗
PubMed1993

Reduced responsiveness of the hypothalamic-pituitary-adrenal axis in Boran (Bos inducus) cattle infected with Trypanosoma congolense.

The response of the pituitary-adrenal axis to corticotrophin-releasing hormone (CRH) and the adrenal response to adrenocorticotrophin hormone (ACTH) stimulation were studied during infection of Boran (Bos indicus) cattle with Trypanosoma congolense. For CRH, 15 animals were challenged during preinfection and infection phases, while for ACTH 10 animals were challenged during pre-infection, infection and post-treatment phases of the experiments. The axis showed a reduced responsiveness after CRH challenge during patent parasitaemia, manifested by low (p < 0.05) plasma ACTH and cortisol concentration as compared to the pre-infection CRH challenge concentrations. Cortisol concentration after ACTH challenge during pre-infection, infection and post-treatment phases did not differ. The reduced pituitary-adrenal response to CRH challenge and the normal adrenal response to ACTH challenge found during trypanosomiasis indicates pituitary dysfunction due to infection.

Adrenocorticotropic Hormone↗
PubMed1992

Hypothalamic-pituitary-adrenal axis responsiveness to insulin-induced hypoglycaemia is modified by trypanosome infection in Boran (Bos indicus) cattle.

Ten Boran (Bos indicus) cattle were used to study the stress responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis during trypanosome infection. Five cattle were infected with Trypanosoma congolense IL 1180 by tsetse challenge and five cattle served as controls. All infected animals developed acute trypanosomiasis. Insulin-induced hypoglycaemia (50 per cent of pre-insulin glucose concentration) was used as a stress factor. Acute hypoglycaemia was observed in three infected and three control animals after insulin challenge. Two animals from each group either did not respond or responded slowly. Hypoglycaemia in infected animals completely failed to induce an HPA axis response, while in control animals an HPA axis response was indicated by a significant increase in plasma adrenocorticotrophic hormone (ACTH) and cortisol concentrations (P less than 0.01). The results show that trypanosomiasis in Boran cattle can cause a decrease in the stress responsiveness of the HPA axis as indicated by a blunted ACTH/cortisol response to insulin-induced hypoglycaemia.

Adrenocorticotropic Hormone↗
PubMed1991

Effect of clomiphene citrate upon periovulatory endometrial development in the baboon.

Endometrial histology in baboons (Papio cynocephalus anubis) was evaluated after five days of clomiphene citrate (CC) treatment initiated on either cycle day six (n = 8) or ten (n = 4). Biopsies performed before and after a human chorionic gonadotropin (hCG) induced ovulation were compared to non-CC treated controls. Although CC had a definite antiestrogenic effect on perineal skin, no significant effect of endometrial proliferation was demonstrable.

Animals↗
PubMed1987

The effect of LHRH analogs on pregnancy in the baboon.

Thirty-three baboons were maintained throughout their peri-ovulatory period in group enclosures with fertile males. They received treatment on days 14-19 of presumed pregnancy with either twice daily injection of 50 micrograms of an LHRH agonist or of 2 mg of an LHRH antagonist. Three pregnancies from 14 cycles were maintained in each of the treatment groups as compared to 5 of 14 in controls. Four abortions were noted but as 1 occurred in a control group the response could not be attributed to treatment. The agonist had no apparent effect on urinary progestins in nonpregnant animals but both analogs did cause a transient decline in pregnant animals. Results indicated that LHRH analogs are not suitable agents for early pregnancy termination under the present treatment regimen.

Animals↗
PubMed1987

Failure of the prostaglandin F2 alpha analogue, cloprostenol, to induce functional luteolysis in the olive baboon (Papio cynocephalus anubis).

The prostaglandin F2 alpha analogue, cloprostenol, which is an effective luteolytic agent in the common marmoset, was administered intramuscularly to olive baboons to determine if it possessed luteolytic properties in this species. The results showed that functional luteolysis was not induced when cloprostenol was administered during the mid- to late luteal phase or during early pregnancy.

Animals↗
PubMed1986

Reproduction in the vervet monkey (Cercopithecus aethiops): endometrial oestrogen and progestin receptor dynamics during normal and prolonged menstrual cycles.

Sixteen individually caged adult female vervet monkeys (Cercopithecus aethiops), whose reproductive parameters had been studied for 5 years, were hysterectomized/ovariectomized during three reproductive states; i.e. the late follicular (15.4 +/- 4.7 (S.D.) days) and luteal (27.8 +/- 4.7 days) phases of the normal cycle (20-50 days), and during prolonged intermenstrual intervals (PII; 99.0 +/- 2.5 days since the previous menses). These latter animals showed characteristics of both follicular and luteal phases; i.e. their ovaries contained both corpora lutea and large antral follicles and systemic oestradiol and progesterone concentrations were raised. Analysis of cytoplasmic oestrogen and progestin receptors (CER and CPR) revealed that endometrium during PII had CER levels of 0.58 +/- 0.07 pmol/mg protein, similar to those of the follicular phase (0.60 +/- 0.12); CPR levels (1.20 +/- 0.87) were not different from those of the luteal phase (1.05 +/- 0.45). The ratio of CPR to CER during the luteal phase was about tenfold higher than that of the follicular phase. Levels during PII were intermediate between the two phases. Under receptor-activating conditions, the DNA-binding components of the PII cytoplasmic fraction underwent over 40% loss while those present during both phases of the normal cycle doubled. The hormone-binding sites at all times remained intact indicating that the DNA and hormone-binding sites are distinct on both CER and CPR. Less than 50% interaction of CER/CPR with DNA-cellulose was obtained, indicating the presence of only limited quantities of cytoplasmic activating factors which may be a prerequisite for receptor binding to the genome. During PII, factors which deactivate DNA-binding sites may also have been induced. Extensive accumulation of nuclear oestrogen receptor was evident in PII endometrium with 80% being salt-resistant. This level is higher than that in the follicular and luteal phases (37 and 52% respectively). These data, suggesting a possible aberration of receptor activation in vitro and receptor processing in vivo, may be indicative of endometrial dysfunction during PII. This could lead to a delay in menstruation.

Animals↗
PubMed1986

Enclosure design and reproductive success of baboons used for reproductive research in Kenya.

Three 125mz enclosures were designed to enable collection of urine from female baboons (Papio sp.) during early pregnancy, while maintaining them in close continuous social contact to permanent breeding groups. Attached to each enclosure were individual cages to which females were confined for urine collections. Over the 18-month period following group formation, 60 of 67 females became pregnant and then 51 reconceived following surgical termination of pregnancy. A total of 181 pregnancies were recorded. Over 75% of reconceptions occurred within the first two cycles following surgery. The enclosures have proved to be extremely versatile, allowing sampling of individual animals maintained in group conditions with the ability to interact socially.

Abortion, Induced↗
PubMed1984

Limitations of the nonhuman pregnancy kit for pregnancy diagnosis in baboons.

The Nonhuman Primate Pregnancy Test (NHPPT) kit was evaluated for diagnosis of pregnancy in baboons. Unreadable controls rendered 33% of all tests inconclusive. Refrigeration and dilution did little to improve the number of inconclusive tests. Positive-and false-negative results from readable tests on days 20 to 27 of confirmed pregnancy were 75% and 25%, respectively. The NHPPT did not always provide an accurate diagnosis of pregnancy and often proved unreadable.

Analysis of Variance↗
PubMed1979

Hormonal and physical changes associated with bovine conceptus development.

Conceptus (placental membranes, fetal fluids and fetus) development was characterized between Days 27 and 111 of gestation. Progestagens, oestrone, oestradiol, oestrone sulphate and prostaglandins (PG) F were measured in maternal plasma and allantoic and amniotic fluids. Protein concentrations are described for fetal fluids. The early increase in placental membrane weight from 1.12 g (27 days) to 58.45 g (50 days) was associated with oestrogen production presumably of conceptus origin. Oestrogens increased significantly in allantoic and amniotic fluids throughout the period studied with oestrone being the primary free oestrogen, rising from 2 pg/ml (Day 33) to 144 ng/ml by 111 days in allantoic fluid. Changes in plasma oestrogens of the maternal circulation were not detected until after Day 70 at which time oestrone concentration was greater than that of oestradiol. Fetal fluid concentrations of progestagens, oestrone sulphate and PGF were not related to maternal plasma levels and a sequestration of these hormones by the allantois is postulated.

Allantois↗
PubMed1979

Luteolytic effect of oestrone sulphate on cyclic beef heifers.

The action of oestrone sulphate on luteal function was tested in cyclic beef heifers. Once daily injection of 28 or 56 mg oestrone sulphate in corn oil beginning on Day 10 of the cycle had a significant luteolytic effect as compared to corn oil-treated controls.

Animals↗
PubMed1978

Development of the conceptus in the bovine.

Growth of fetuses, fetal membranes, and fetal fluids was characterized by least squares analysis for 254 conceptuses ranging from 25 to 278 days of gestation. Prior to 100 days of gestation, increases in allantoic fluid volume and chorio-allantoic membrane weight preceded those of fetal weight, amnio-allantoic membrane weight, and amniotic fluid volume. The relative rate of growth of components suggests a prerequisite of chorio-allantoic membrane expansion for subsequent fetal growth. Male fetuses were heavier than female fetuses as early as 100 days of gestation. Rate of growth of all fetuses was maximal at 230 days of gestation with a peak rate of greater than 200 g/day. Growth rate then declined to less than 100 g/day by term.

Allantois↗
PubMedDate not supplied

Trypanosome-induced hypothyroidism in cattle.

Three Boran (Bos indicus) cattle infected with T. congolense IL 1180, and two uninfected control Boran cattle were used to study the effect of trypanosomiasis on the function of the thyroid gland. On a weekly basis, plasma thyroxine (T4) was measured by 125I-radioimmunoassay. Results indicated that T. congolense caused a significant decline in plasma T4 concentration in infected animals.

Animals↗