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Biomedical subjects

J Sirois

Publications and source records attributed to J Sirois.

66 records · Page 4Linked to original sources
PubMed1988

Transcervical collection of equine conceptuses between 10 and 16 days after ovulation.

To recover intact Day-10.5 to Day-16.5 equine conceptuses (Day 0 = ovulation), a rigid catheter was used for 131 collections from donor mares diagnosed pregnant by ultrasonography. A total of 139 conceptuses were recovered, comprising 124 singletons, six pairs of twins and one set of triplets. Of these, 120 (86%) were intact after the collection, 14 (10%) had collapsed, and in five cases (4%), collapsed trophoblastic membranes were surrounded by an intact capsule. The recovery rate of intact conceptuses ranged from 99% on Days 10.5 to 12.5 to 40% on Day 16.5. More uterine flushes per recovery were needed to collect conceptuses on Day 14.5 than on Days 10.5 and 11.5 (x +/- SEM : 3.1 +/- 0.5 vs 1.4 +/- 0.1 and 1.3 +/- 0.2 flushes, respectively, P<0.05), and the total volume of flushing medium used was greater on Day 14.5 than on Days 10.5, 11.5 and 12.5 (1040 +/- 193 vs 406 +/- 49, 396 +/- 48 and 499 +/- 59 ml, respectively, P<0.01). Seventy of the 100 mares inseminated at the first estrus following embryo collection became pregnant, indicating that the technique used had no major effect on subsequent fertility.

Journal Article↗
PubMed1988

Ovarian follicular dynamics during the estrous cycle in heifers monitored by real-time ultrasonography.

It is not clear whether the turnover of ovarian follicles during the estrous cycle in cattle is continuous and independent of the phase of the cycle, or whether waves of follicular growth occur at specific times of the cycle. To clarify this controversy, the pattern of growth and regression of ovarian follicles was characterized during a complete estrous cycle in ten heifers by daily ultrasonographic examinations. Follicles greater than or equal to 5 mm were measured and their relative locations within the ovary were determined in order to follow the sequential development of each individual follicle. Results indicated the presence of either two (n = 2 heifers), three (n = 7), or four (n = 1) waves of follicular growth per cycle. Each wave was characterized by the development of one large (dominant) follicle and a variable number of smaller (non-dominant) follicles. In the most common pattern observed (three waves/cycle), the first, second, and third waves started on Days 1.9 +/- 0.3, 9.4 +/- 0.5, and 16.1 +/- 0.7 (X +/- SEM), respectively. The dominant follicle in the third wave was the ovulatory follicle. The maximal size and the growth rate of the dominant follicle in the second wave were significantly lower than in the other waves, but no significant difference was observed between the first and third waves. For the two heifers that had two follicular waves/cycle, the waves started on Days 2 and 11, whereas in the remaining heifer (four waves/cycle), the waves began on Days 2, 8, 14, and 17, respectively. At 0, 1, 2, 3, and 4 days before estrus, the ovulatory follicle was the largest follicle in the ovaries in 100%, 95%, 74%, 35%, and 25% of follicular phases monitored, respectively. The relative size of the preovulatory follicle at the completion of luteolysis (progesterone less than 1 ng/ml) was negatively correlated (r = -0.90; p less than 0.0001) with the interval of time between the end of luteolysis and the luteinizing hormone surge, suggesting that the length of proestrus is determined by the size of the pre-ovulatory follicle at the beginning of proestrus. In conclusion, this study shows that the development of ovarian follicles greater than or equal to 5 mm in heifers occurs in waves and that the most common pattern is three waves per estrous cycle.

Animals↗
PubMed1987

Oxytocin stimulation of plasma 15-keto-13,14-dihydro prostaglandin F-2 alpha during the oestrous cycle and early pregnancy in the mare.

In Exp. 1, 4 mares were given oxytocin intravenously (10 i.u./500 kg body wt) daily between Days 9 and 14 (Day 0 = day of ovulation) when pregnant and on Days 9-14, 16, 18, 20 when non-pregnant (not inseminated). In the non-pregnant mares the increase in plasma PGFM response to oxytocin was greater at Day 13 (235 +/- 54 pg/ml) than at Day 11 (113 +/- 38 pg/ml; P less than 0.05) and was maximum at Day 16. However, these animals did not return to oestrus and plasma progesterone did not fall below 4 ng/ml. There was no significant increase in response to oxytocin between Days 9 and 14 in the pregnant animals. In Exp. 2, when these same mares were challenged with oxytocin on alternate day (Days 9, 11 and 13 for pregnant mares, Days 9, 11, 13, 15, 17 and 19 for non-pregnant mares) there was a significant difference in the response between non-pregnant and pregnant mares by Day 13 (383 +/- 19 pg/ml vs 88 +/- 9 pg/ml; P less than 0.005). Plasma progesterone concentrations declined normally and the mares returned to oestrus. During oestrus the response to oxytocin decreased dramatically in mares receiving oxytocin on alternate days, and no response was seen by Day 19. The response also declined after Day 16 in the non-pregnant mares that had daily injections of oxytocin even though plasma progesterone remained elevated. The decreased response coincided with the increase in plasma oestrogen concentrations, suggesting that oestrogens play a role in the control of the response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Steroid secretion by different cell types of the horse conceptus.

Horse conceptuses were recovered non-surgically at Day 12-Day 15 and were dissociated with collagenase. Separation of the cells on a 31.8% Percoll gradient gave two bands of cells and indirect evidence suggests that the low density cells (LDC) are endoderm and the higher density cells (HDC) are trophectoderm. Each band was incubated for 24 h in Minimum Essential Medium and concentrations of oestradiol and progesterone in the medium were measured by radioimmunoassay (RIA). The LDC secreted predominately progesterone (log oestradiol/progesterone = -0.994 +/- 0.141; N = 15) whereas the HDC secreted mainly oestradiol (log oestradiol/progesterone = 0.522 +/- 0.135). When incubated for a further 24 h in fresh medium the oestradiol production decreased by 85% and 84% whereas the progesterone production decreased by 57% and 50% for LDC and HDC respectively. When cells from each band were incubated for 24 h with [3H]pregnenolone, separation of the radiolabelled metabolites by reversed-phase high-pressure liquid chromatography revealed a different steroid profile for each cell type. Therefore, in the intact embryo, an interaction between cells may be important for oestrogen synthesis and thus the maintenance of pregnancy.

Androstenedione↗
PubMed1987

PGF-2 alpha release, progesterone secretion and conceptus growth associated with successful and unsuccessful transcervical embryo transfer and reinsertion in the mare.

The outcome of 23 collections and reinsertions of conceptuses on Days 10.5-13.5, 4 transfers of Day-10.5, and 13 transfers of Day-6.5 embryos (ovulation = Day 0) was monitored in 30 mares. Blood samples were taken before and after each procedure to measure plasma 15-keto-13,14-dihydroprostaglandin F-2 alpha (PGFM), and then daily for progesterone determinations. Mares were also subjected to daily teasing for detection of oestrus, and to uterine ultrasonography for tracing the development of the conceptus. After the reinsertions, 12/23 conceptuses were detectable immediately after the procedure. Of these, 1 developed into a normal foal but 11 disappeared during the next 4 days. All 4 Day-10.5 conceptuses transferred disappeared within 7 days. Of the 13 Day-6.5 conceptuses transferred, 8 were detectable by Day 11.5 and 5 of these developed into healthy foals. The 3 losses occurred between Days 14 and 25. Small increases in PGFM concentrations occurred in 8/23 collection-reinsertion procedures on Days 10.5-13.5 and after 2/25 Day-6.5 recoveries, but during none of the 13 Day-6.5 transfers. A marked reduction (greater than or equal to 40%) in progesterone concentration was noted within 24 h of the procedures in only one Day-10.5 embryo transfer and, in subsequent days, the disappearance of the conceptuses was associated with complete luteolysis in only 1 Day-6.5 transfer, 1 Day-10.5 transfer and 1 Day-12.5 reinsertion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Lissencephaly.

The first reported case of lissencephaly resulting from a consanguinous union strengthens the supposition that in some cases, it is transmitted as an autosomal recessive trait. Comparison of this case with a sporadically occurring case of lissencephaly, with different cortical morphology, suggests that lissencephaly may be an example of either varying gene expressivity or genetic heterogeneity. Lissencephaly and pachygyria may eventually be shown to be due to different causes, some inherited, some acquired. The classical examples of lissencephaly are different morphologically from a case in which antenatal cytomegalovirus infection had produced a small smooth brain. This suggests that antenatal viral infections are destructive rather than teratogenic.

Abnormalities, Multiple↗
PubMed1972

Crohn's disease of the appendix.

Granulomatous inflammation typifying Crohn's disease was centred within or confined to appendices in six patients, two of whom developed lesions attributable to Crohn's disease elsewhere in the gut. The remaining four patients have remained symptom-free for periods varying from two to six years. Histological evidence of Crohn's disease was also present in five of 46 appendices available for re-examination in a survey of 63 cases of Crohn's enterocolitis. It is adduced that appendiceal involvement in Crohn's disease is not uncommon.

Appendicitis↗
PubMed1966

[Traumatic thrombosis of the internal carotid artery].

Two cases of post-traumatic thrombosis of the internal carotid artery are presented, which are of interest because of their relative rarity. A detailed understanding of the pathogenesis and variety of clinical presentations, an adequate appraisal of the diverse proposed treatments, and an improvement in the prognosis, which is poor even in young patients-these await further enquiry and research.

Adolescent↗
PubMed1965

[Bilateral thromboses of the internal carotid].

A recent case of bilateral internal carotid artery thrombosis encountered by the authors prompted a review of the literature on this subject. The lesion is compatible with, if not a normal life, at least prolonged survival, owing to the development of collateral circulation, which until the onset of thrombosis is of negligible proportions. The prognosis, although poor, may nonetheless be improved in future years if the practice is adopted of investigating the patient completely upon the appearance of the slightest symptoms. This may lead to early diagnosis and perhaps to better treatment results.

Angiography↗