Midtrimester abortion was initiated for psychosocial reasons in 5 patients, and premature delivery in 2 patients with intrauterine fetal death using a new method for termination of pregnancy — the instillation of normal saline through the cervical canal into the extraovular space. Blood levels of 15-keto-13,14 dihydro-prostaglandin F2α(PGF2α-M) progesterone (P) and Human Chorionic Gonadotropin (HCG) were determined from the start of the procedure up to the expulsion of the fetus at frequent intervals in the peripheral circulation of these patients, by highly sensitive and specific RIA procedures. Following saline instillation and initiation of contractions, the concentration of PGF2α-M) increased significantly, reaching peak values either shortly before or at the time of delivery. This rise was associated with a significant decrease of P levels. Levels of HCG were variable. The possible significance of these results is discussed.

1. The effects of changes in sodium balance on renal prostaglandins have been hitherto studied mainly in experimental animals and the results have been controversial. In this study the 24 h urinary excretion of prostaglandins E2 and F2 alpha was measured by radioimmunoassay in seven normal subjects under basal conditions and after 5 days of a diet containing less than 20 mmol of sodium/day. Subsequently a sodium chloride (150 mmol/l: saline) load (300 mmol of sodium over 4 h) was infused and prostaglandins were again measured in hourly urine collections. Plasma renin activity and aldosterone were also measured under basal conditions, after the low sodium diet and at 2 and 4 h of the saline infusion. 2. Dietary sodium restriction was associated with a marked increase in prostaglandin E2 excretion (from 769.7 +/- 201.6 SEM to 1761.3 +/- 304.9 ng/24 h, P less than 0.0005). Prostaglandin F2 alpha also increased from 1187.0 +/- 390.1 to 1435.6 +/- 344.6 ng/24 h, but this was not statistically significant. The prostaglandin E2/prostaglandin F2 alpha ratio increased from 0.83 +/- 0.2 to 1.52 +/- 0.34 (P less than 0.01). Plasma renin activity and aldosterone rose significantly (P less than 0.05 and less than 0.0025 respectively). 3. During the saline load prostaglandin E2 decreased after 2 h from 142.4 +/- 29.9 to 86.7 +/- 22.9 ng/h (P less than 0.05) and to 36.9 +/- 5.96 ng/h after 4 h. Prostaglandin F2 alpha decreased at a slower rate, from 98.4 +/- 18.7 to 37.5 +/- 8.8 ng/h at 4 h (P less than 0.02). At 4 h the prostaglandin E2/prostaglandin F2 alpha ratio returned to control values (0.90 +/- 0.17). Plasma renin activity and aldosterone decreased significantly after 2 h (P less than 0.02 and less than 0.0025 respectively) and reached control values after 4 h. 4. The present study demonstrates that chronic and acute changes in sodium balance induce changes in the excretion of prostaglandin E2 parallel to changes in plasma renin activity and aldosterone. The similar but quantitatively smaller changes in prostaglandin F2 alpha and the inversion of the ratio between the two prostaglandins during sodium deprivation suggest that at least two factors are involved: increased delivery of substrate for prostaglandin synthase and decreased activity of the prostaglandin E1 9-keto-reductase. Prostaglandins probably play an important role in the adaptation of the kidney to changes in sodium balance.

Renal excretion of prostaglandin-E2 was measured by radioimmunoassay in patients with chronic renal diseases. Significantly elevated urinary prostaglandin-E2 amounts were found in patients with moderate renal insufficiency (creatinine clearances 20-59 ml/min). In mild and severe renal insufficiency, the urinary excretion of PGE2 was within the normal range. In the non-terminal stages of kidney failure, a definite correlation was found between the degree of renal impairment and the daily amounts of PGE2 in the urine. It is therefore concluded that in these stages of the disease the kidney produces elevated levels of PGE2 in an attempt to improve the decreased renal blood flow caused by the disease.

Urinary prostaglandin (PGE2) and plasma renin activity (PRA) were determined in 3 groups of hypertensive patients before and following 5 days of treatment with different antihypertensive drugs. In all 3 groups studied a substantial decrease of blood pressure was noted following treatment. However, whereas administration of chlorthalidone and hydralazine initiated a significant rise of PGE2 and PRA excretion, treatment with propranolol was associated with a decrease of these two parameters. In view of these findings it seems therefore as if renal production of PGE2 (at least with regard to propranolol, a beta-blocking agent), is not related to the hypotensive effect of the drug.

Publisher Summary This chapter discusses the use of carbodiimides in the preparation of immunizing conjugates. Sheehan and Hess introduced the use of carbodiimides for the synthesis of peptide bonds. The preparative procedure is simple and easy to perform, and therefore it became the most important coupling method. It is postulated that an intermediate is formed that can react, either with an amine to give the desired peptide or to rearrange to an acyl urea. The acyl ureas are the main side products at elevated temperatures, and in order to shift the reaction toward peptide bond formation, temperatures around 0° should be used. Presence of an amino group, during the reaction, also reduces the formation of acyl urea. The most commonly used carbodiimide for peptide synthesis performed in organic solvents is dicyclohexylcarbodiimide. In the field of immunology, the main use of carbodiimides has been in the conjugation of weakly immunogenic or nonimmunogenic compounds to larger carder proteins or to synthetic antigens, thus enhancing their immunogenicity. Among the immunogens synthesized, there are complexes containing low molecular weight peptides, such as protein fragments or hormones, steroidal hormones, prostaglandins, cyclic nucleotides, and plant hormones.

The urinary excretion of prostaglandins (PG) E2 and F2 alpha, which reflects the renal synthesis of these substances, was evaluated by radioimmunoassay before and after an i.v. injection of furosemide in 10 normal subjects and in 10 patients with essential hypertension. In most normal subjects, urinary PGE2 increased after furosemide injection, whereas PGF2 alpha decreased to undetectable levels. In the hypertensive subjects, PGE2 increased to a lesser degree or decreased, but PGF2 alpha excretion was unchanged or augmented. These results suggest that furosemide may increase PGE2 synthesis not only by increasing the availability of the substrate arachidonic acid or by inhibiting the action of the catabolizing enzyme 15-hydroxyl-PG-dehydrogenase, as has been proposed, but also by depressing the activity of the enzyme PGE2-9-ketoreductase, which catalyzes the conversion of PGE2 to PGF2 alpha. In essential hypertension, an increased activity of PGE2-9-ketoreductase could explain the decreased levels of PGE2 that have recently been described in these patients. Whether these abnormalities in PG interconversion play a role in the pathogenesis of the hypertensive state or are secondary to it remains a question for further investigation.

We examined the role of prostaglandins in three pivotal events of the female reproductive cycle: ovulation, luteolysis, and menstruation. Four general approaches were adopted, using in vivo and in vitro models: use of inhibitors of cyclooxygenase and of PG action; immunoneutralization of individual prostaglandins; administration of exogenous prostaglandins; and attempts to correlate PG levels in tissues and body fluids to physiologic events. It can be concluded that prostaglandins or related metabolites of arachidonic acid are essential in laboratory rodents for follicular rupture and the release of a fertilizable oocyte, but not for other LH actions on the follicle that are mimicked by PG or for the neuroendocrine triggering of ovulation. PGs control the cyclic regression of the corpus luteum and appear also to be implicated in the decidual reaction and in the menstrual shedding of the endometrium in primates. Some aspects of the control of follicular PG formation and of PG action were analyzed. Gonadotropins stimulate follicular PG synthesis by a steroid-independent cyclic nucleotide-mediated induction of cyclooxygenase. Both the thecal and granulosa cell compartments show this response. An effect of the phytolectin conconalavin A on ovarian PG synthesis is described. The response of follicular cells to prostaglandin E2 exhibits the phenomenon of desensitization and is influenced by agents modifying the structure and function of cytoskeletal elements. Evidence is put forward for the view that abrogation by PGF2 alpha of the stimulatory action of LH on luteal adenylate cyclase is the biochemical basis of the luteolytic action of this prostaglandin. While the precise mechanism of PG action on the endometrium remains to be defined, PG-synthetase inhibitors have already found useful applications in the management of menstrual disorders, such as functional dysmenorrhea and menorrhagia. The role in ovarian and uterine physiology of the more recently discovered labile arachidonate metabolites, such as the endoperoxides, prostacyclin, and thromboxanes, has not yet been adequately explored.

The ability of cytoplasmic and nuclear fractions from decidual tissue to bind [3H]-oestradiol-17β and the progesterone analogue [3H]-R-5020 was examined during the growth phase, maintenance and regression of trauma-induced unilateral deciduoma of pseudopregnant rats and compared to that of the control uterine horn. High affinity (Kd = 10−10 to 10−11 M) 8 S cytoplasmic oestrogen receptors, as well as nuclear oestrogen receptors, were detected at all stages of decidual life, but the concentration of both types of oestrogen receptors per unit DNA gradually decreased from the 6th to the 12th day of pseudopregnancy. Cytoplasmic progestin receptors (Kd = 10−9 to 2 × 10−9 M) sedimenting at 4–5 S and nuclear progestin receptors were present at all stages of decidual development. The concentration of these receptors declined sharply towards the 12th day of pseudopregnancy in the deciduoma, without comparable changes in the non-decidualized horn. It is possible that the terminal decline in the concentration of steroid receptors in the deciduoma accounts for the inability of exogeneous steroids to prolong the life-span of the deciduoma or to prevent its regression.

In 28-day-old rats injected with PMSG, ovarian cyclic AMP and PGE and PGF increased 2 and 3-4 h respectively after the LH peak.

The concentration of prostaglandin E and the activity of prostaglandin synthetase were determined in mature and immature mouse thymocytes. Hydrocorthisone resistant thymocytes, or thymocytes separated from the immature cell population after agglutination of the latter by peanut agglutinin served as a source of mature thymocytes. It was found that mature thymocytes contain a much higher concentration of prostaglandin E and have an increased activity of prostaglandin synthetase than immature cells.

Extracts of decidual tissue produced in pseudopregnant rats were found to suppress in vitro antibody response to alpha-2,4-dinitrophenyl-polylysine. The peak levels of both the total antibody response and the 2-mercaptoethanol-resistant fraction were reduced. Extracts prepared in a similar manner from uteri of normal untreated or pseudopregnant rats did not exert such an effect.

Mature female rats were immunized with BSA-conjugates of oestradiol-17beta-6-carboxymethyloxime or progesterone-11-hymisuccinate. Sera tested two months later at 1/2000 dilution bound 63.3% +/- 3.1 SEM and 21.2% +/- 2.3 of the homologous tritiated hormone (10 pg),--oestradiol-17beta(Oe2) and progesterone (P), respectively. Rats immunized against Oe2 had a significantly longer oestrous cycle (8.2 days vs. 4.5 days in BSA-immunized rats), with a prolonged leukocytic phase. The cycle of rats immunized against P was also prolonged (10.5 days), but in this group the cornified smear phase was abnormally extended. The luteinizing hormone (LH) normally observed on the afternoon of pro-oestrus failed to occur in the rats immunized against Oe2 and in 70% of rats immunized against P. The latter animals, however, showed sporadic LH discharges during periods of persistent cornification. Immunization against P resulted in elevated total (free plus bound) plasma P levels; immunization against Oe2 prevented the pro-oestrous rise in plasma P. Mating of rats immunized against Oe2 resulated in normal pregnanices, while none of the rats immunized against P delivered.

The concentrations of testosterone, progesterone and 20alpha-hydroxypregn-4-en-3-one (20alpha-OHP) were measured in the ovaries of immature rats in which ovulation was induced by treatment with pregnant mare serum gonadotrophin (PMSG) and, 48 h later, with human chorionic gonadotrophin (HCG). The concentration of testosterone in the tissue increased significantly 48 h after treatment with PMSG, reached a peak 4 h after the administration of HCG and declined to the basal level 4 h later. Increases in the levels of progesterone and 20alpha-OHP were observed 4 h after the administration of HCG. Whereas the level of 20alpha-OHP continued to rise during the subsequent 30 h, progesterone levels declined near the presumed time of ovulation (12 h after administration of HCG). It is concluded that 20alpha-hydroxysteroid dehydrogenase activity is present in the immature rat ovary before ovulation and that an increase in the production of testosterone in the ovaries of rats treated with PMSG and HCG precedes increased production of progesterone and 20alpha-OHP in these ovaries.

Immune reactivity in lymhoid organs of rats during the last week of syngeneic (Lewis: L x L) or allogeneic (females Lewis x males Wistar: L x W) pregnancy was compared with that found in non-pregnant animals. The thymus weight was slightly reduced and the response of thymic lymphocytes to phytohaemagglutinin and concanavalin A was slightly, but not significantly, elevated in pregnant rats. By contrast, the response of lymphoid cells from spleen and mesenteric lymph nodes to the mitogens was reduced in rats during advanced pregnancy. The immune response of lymphocytes from pregnant L x W rats to allogenic (Brown-Norway: BN) or semiallogeneic (W) irradiated cells was tested by the mixed lymphocyte culture (MLC) assay. The MLC response of para-aortic lymph nodes towards the unrelated BN cells was elevated over that of non-pregnant rats on day 15 of pregnancy. No significant enhancement was observed at the same time in the MLC response of mesenteric lymph nodes. On day 20 of pregnancy, a reduced MLC response towards BN cells was found in the mesenteric and para-aortic lymph nodes. On day 15 of pregnancy, the MLC response of mesenteric and, more markedly, that of para-aortic lymph nodes to paternal (W) cells was enhanced, as compared to that of non-pregnant rats. On day 20 of pregnancy, the response of mesenteric lymph nodes was suppressed, while the response of para-aortic lymph nodes was similar to that found in non-pregnant rats. Since the latter lymph nodes are the most directly exposed to antigenic stimulation from the uterus, it seems unlikely that the suppression in response to T-cell mitogens observed in the spleen and mesenteric lymph nodes during pregnancy accounts for the survival of the foetus. It seems more plausible that local factors in the vicinity of the uterus protect the foetus from being rejected.