Effect of embryos on luteolysis and termination of early pregnancy in sheep with cloprostenol.

An investigation of the control of the function of the corpus luteum of early pregnancy in sheep has been carried out by assessing the luteolytic effects of a dose of 100 micrograms of the synthetic prostaglandin, cloprostenol. Cloprostenol injected into 21-day pregnant sheep carrying single or multiple embryos caused luteolysis and termination of pregnancy within 2--5 days in 8 of 23 sheep. The mean numbers of corpora lutea in these ewes differed significantly from those which carried their pregnancy (1.8 +/- 0.3, SEM, vs 3.2 +/- 0.4; P less than 0.05). It appeared that the greater number of embryos, or a greater mass of embryonic tissue, afforded increased protection to the corpora lutea through unidentified antiluteolytic or luteotrophic factors. The number of corpora lutea present did not appear to be an operative factor, as the same dose of cloprostenol was luteolytic in 43 of 46 nonpregnant ewes with 1--6 corpora lutea; the 3 refractive ewes each having only 1 corpus luteum. The progesterone concentration in the plasma of pregnant ewes which underwent luteolysis following cloprostenol treatment was 0.5 +/- 0.1 ng/ml 48 h after injection, while that of the ewes remaining pregnant was significantly higher at 2.1 +/- 0.3 ng/ml. Seven of these refractive ewes which were given a second injection of cloprostenol on Day 28 of pregnancy subsequently experienced luteolysis and abortion. The corpora lutea of the remaining 8 ewes were not affected by saline injections given on Day 28, but 4 of these ewes later aborted after Day 44. It is concluded that pregnancies on ewes carrying 1 embryo can be terminated by a single dose of 100 micrograms cloprostenol given around Day 21 of pregnancy, but 2 injections given about 7 days apart may be needed when multiple embryos are present. Hormonal control of the sensitivity of the corpus luteum to luteolytic prostaglandins appears to reside in the conceptus in such a way that a decrease in sensitivity is related to the number of embryos present.

Detection of induced death of embryos in sheep by the rosette inhibition test.

The rosette inhibition test has been used to monitor the decrease of an 'early pregnancy factor' in 2 groups of pregnant sheep (19-21 days) in which embryos were removed surgically or by induction of luteolysis with cloprostenol. The rosette inhibition titres of sera taken from sheep of each group declined from high (16-18) to low (8-10) levels within 48 h of treatment. Surgical removal of embryos caused little change in serum progesterone concentration whereas cloprostenol prompted a rapid decrease over the same period. Death of the embryo can therefore be detected by the rosette inhibition test within 48 h of occurrence, but not necessarily by the measurement of progesterone in blood within this period.

Detection of early pregnancy in sheep by the rosette inhibition test.

The rossette inhibition test, an established test for determining the immunosuppressive potential of antilymphocyte serum, has been applied to the serum of sheep after mating. The rosette inhibition titre was much higher (12--26) in 7 sheep which were fertilized and remained pregnant for up to 21 days than in 5 sterile ewes mated with intact rams (8--10). The difference was apparent by 24 h after mating. One ewe had high titres for 6 days after mating but these then dropped and she returned to oestrus; early embryonic loss was suspected. Another ewe which returned to oestrus had consistently low titres. The results indicate that the rosette inhibition test can be used to detect fertilization, early embryonic death and continued pregnancy in sheep.

Consultation-liaison scheme for self-poisoned patients in a general hospital.

In a prospective clinical trial 276 self-poisoned patients consecutively admitted to hospital were randomly allocated to medical teams or to psychiatrists for an initial psychiatric assessment and a decision about "disposal." Junior doctors and nurses received instruction in this work. While awaiting the outcome of the trial the randomisation was continued for 13 months and 729 allocations were made altogether. Physicians requested psychiatric opinions for roughly one in five of their patients. In other respects medical teams performed similarly to psychiatrists. Provided that due attention is given to teaching junior staff and to ensuring that psychiatric treatment and social-work support are available once patients have been assessed, such a consultation-liaison scheme could be adopted in other hospitals. This would help to change unfavourable attitudes towards self-poisoned patients and contribute to the general training of doctors and nurses.