O. Ylikorkala

Measurement of thromboxane B2 in human plasma or serum by radioimmunoassay

Abstract A radioimmunoassay for thromboxane B 2 (TxB 2 ), a stable metabolite of thromboxane A 2 , is described. The method consists of extraction of TxB 2 into ethyl acetate from acidified plasma or serum samples and saturation analysis using specific antibodies produced in rabbits against TxB 2 -BSA conjugate. The 50 % displacement level of the standard curve was 19.1 ± 2.9 pg/tube (mean ± S.D., n = 19). The method blank was 3.4 ± 3.1 pg/ml (n = 15) and the assay sensitivity thus 9.6 pg/ml (mean blank + 2 S.D.). When 100 to 200 pg of TxB 2 were added to plasma, 96.2–103.6 % were recovered. The intra-assay coefficient of variation varied from 6.7 to 9.7 %, and the inter-assay coefficient of variation was 18.6 % (n = 10). The TxB 2 concentration in the plasma of 14 healthy subjects varied from 29.3 to 120.8 pg/ml with a mean ± S.D. of 70.1 ± 26.1 pg/ml, when the blood was collected into tubes containing acetylsalicylic acid (ASA), whereas significantly higher (p 2 concentrations of 68.3 – 285.3 pg/ml with a mean ± S.D. of 151.8 ± 66.6 pg/ml were obtained from the same subjects in the plasma of blood which was collected into tubes containing no ASA. When blood samples from 10 subjects were allowed to clot at 0, +24 or +37°C for 60 min., the TxB 2 concentrations in the sera were 2053 ± 870 pg/ml, 4001 ± 1370 pg/ml and 178557 ± 54000 pg/ml, respectively. The TxB 2 levels in sera which were separated from blood samples incubated at +37°C, correlated significantly (p 2 productions in platelet-rich-plasma (PRP) after an induced aggregation. Our results indicate 1) when TxB 2 is measured in plasma, the use of prostaglandin synthesis inhibitor in the collection tubes is necessary and 2) the measurement of TxB 2 in serum of blood which has been kept at +37°C for a strictly standardized period of time could replace the use of PRP in TxB 2 studies.

Regulation of prostacyclin and thromboxane production by human umbilical vessels: The effect of estradiol and progesterone in a superfusion model

To study the production of the vasodilatory prostacyclin (PGI2) and vasoconstrictory thromboxane A2 (TxA2) by the human umbilical vessels, vascular segments collected from the cords of healthy newborns (n = 15) after normal pregnancies were superfused with Eagles medium at 37 degrees C under continuous oxygenation. The stable metabolites of PGI2 and TxA2, 6-keto-prostaglandin F1 alpha and thromboxane B2 (TxB2) respectively, were measured from the superfusates with radioimmunoassays. All vascular segments studied produced 6-keto-PGF1 alpha and TxB2 without any significant difference between the arteries and veins. 6-keto-PGF1 alpha was produced some 10-15 times more than TxB2. 17-beta-estradiol at concentrations of 10, 100 and 1000 ng/ml dose-dependently stimulated the 6-keto-PGF1 alpha formation, but had no effect on TxB2 generation. Progesterone 50, 500 and 5000 ng/ml caused no changes in 6-keto-PGF1 alpha or TxB2 generations but even the smallest concentration of progesterone abolished the stimulating effect of estradiol. These results thus suggest that the high circulating levels of 17-beta-estradiol and progesterone in the umbilical vessels may be important in the regulation of PGI2 synthesis in the umbilical vessels in vivo.

Comparison between antifibrinolytic and antiprostaglandin treatment in the reduction of increased menstrual blood loss in women with intrauterine contraceptive devices

Summary. The effects of a fibrinolysis inhibitor (tranexamic acid, TA) and prostaglandin synthesis inhibitor (diclofenac sodium, DS) were compared in the reduction of excessive menstrual blood loss in 19 women with an intrauterine contraceptive device (IUCD). These women (mean blood loss before treatment to 135.1±18.9 SE ml, range 70–294 ml) were treated in random order with TA (1.5 g three times daily for 5 days starting on the first day of menstruation for two periods), and with DS (50 mg three times on the first day followed by 25 mg three times daily for 4 days, for two periods), or with placebo (one period) in a double‐blind trial. The placebo treatment did not change menstrual blood loss (128.3±15.6 ml). The TA treatment decreased blood loss to 59.4±7.7 ml (P<0.001) and the DS treatment to 102.1±13.6 ml (P<0.01). Neither treatment abolished pelvic discomfort during menstruation or shortened its duration. Various side‐effects were noted by 12 women during 19 TA treatments and by five women during six DS treatments. Thus, while TA is generally far more effective, DS gave pronounced decreases in menstrual bleeding in some women and had less frequent side‐effects.

A DOSE RESPONSE RELATION BETWEEN IMPROVED LACTATION AND METOCLOPRAMIDE

In a placebo-controlled, cross-over study, thirty-seven puerperal women with inadequate production of breast-milk were treated with 5, 10, or 15 mg of metoclopramide three times a day for 2 weeks. Doses of 10 or 15 mg significantly raised maternal serum prolactin; they also increased breast-milk secretion by 42.5 +/- 34.7 (SD) ml and 50.0 + 35.9 ml per feed, respectively. This effect was unrelated to the phase of the puerperium during which treatment was started. The increase in milk secretion was associated with a decreased need for supplementary feeds, and 33% of the infants of these mothers needed no supplementary feeds during treatment. 5 mg doses did not stimulate prolactin milk secretion. Although placebo had no objective effect on the milk yield, 24% of the women judged its effect to be good, and 89% of women on metoclopramide reported a good effect. Seven women on metoclopramide and three women on the placebo complained of slight side-effects. No adverse effects upon the infants were observed. Metoclopramide therapy may be useful for improving poor lactation.

Metoclopramide and breast feeding: transfer into milk and the newborn.

SummaryThe pharmacokinetics and endocrinological effects of metoclopramide were investigated in 5 mothers with deficient lactation and in their children soon after delivery. In addition, the transfer of metoclopramide into breast milk was evaluated in 18 mothers during the 8th to 12th puerperal weeks. Metoclopramide was detected in all the milk samples studied, generally at a higher concentration than in maternal plasma. Metoclopramide was found in plasma from only 1 of the 5 neonates studied. Exposure of the child to metoclopramide, estimated by multiplying the daily breast milk volume by the concentration of metoclopramide in the milk, ranged from 6 to 24 µg/kg/day for the 5 children in the early puerperium to 1 to 13 µg/kg/day for the 18 children during the late puerperium. These quantities are considerably less than the therapeutic dose of 500 µg/kg/day recommended for children. However, the plasma concentration of prolactin in 4 out of 7 neonates sampled taken during administration of metoclopramide to the mother were higher than the highest plasma prolactin level in children of same age of untreated mothers. The plasma concentration of thyrotrophin in the newborns remained within the normal range.

Type 7 adenovirus pneumonia

Twenty-nine cases of severe type 7 adenovirus pneumonia in children ages 8 months to 6 4/12 years were observed in northern Finland in 1967 and 1968. Adenovirus type 7 was isolated from 17 patients. The other 12 had serologic evidence of adenovirus infection. The clinical picture and complications were compared with those of 17 children with pneumonia associated with bacterial or other viral infections hospitalized during the same period. The clinical course of the adenovirus type 7 infection was especially severe. Extrapulmonary manifestations (meningism, encephalitis, hepatomegaly, heart failure, and hemorrhagic tendency) were common especially in children less than 3 years of age. Three of the 29 patients died, and 4 of the survivors (14 per cent) had permanent pulmonary damage: 2 had bronchiectasis and 2 had residual lung fibrosis.

Prostaglandin biosynthesis inhibitors and endometriosis

Prostaglandins (PGs) may be involved in the development of the symptoms of endometriosis. Therefore 18 patients with pelvic endometriosis were treated in placebo controlled double-blind trial with different prostaglandin biosynthesis inhibitors. These drugs were: acetylsalicylic acid (0.5 g x 3) exerting a weak PG-synthetase inhibition, indomethacin (25 mg x 3) inhibiting PG-synthetase, and as a representative of fenamates, tolfenamic acid (200 mg x 3), which both inhibits PG-synthetase and antagonizes PGs at the target level. The therapeutic effect was evaluated using a specific endometriosis score separately during menstruation and in premenstrum. Prostaglandin biosynthesis inhibitors did not alleviate premenstrual complaints better than placebo. During menstruation tolfenamic acid relieved endometriotic symptoms more effectively than placebo while indomethacin and acetylsalicylic acid did not differ from placebo. A drug which inhibit both the synthesis and action of PGs can thus be used in the alleviation of secondary dysmenorrhea due to endometriosis.

Prostaglandins and Endometriosis

To study the production of prostacyclin (PGI2) and thromboxane A2 (TxA2) in endometriosis in vitro, samples of endometriotic tissue taken during operation from 6 women were superfused for 4.5 hours in 95% O2/5% CO2 at 37 degrees C, and the stable metabolites of PGI2 (=6-keto-PGF1 alpha), and TxA2 (=TxB2) were measured by radioimmunoassays from the superfusates. All samples studied produced 6-keto-PGF1 alpha in the range from 0.2 to 10.5 nanograms/gram of dry tissue/minute with a mean of 3.6 ng/g/min during the whole experiment. TxB2 was also released by each sample at rates between 0.2 and 11.9 ng/g/min (mean 2.6 ng/g/min). The production of these prostanoids tended to be greater in the serosal (n = 2) than in the ovarian (n = 4) endometriosis. The addition of indomethacin of 10(-5) - 10(-3) moles/l to the superfusion medium inhibited concentration-dependently the synthesis of these prostanoids. Apart from these in vitro data implying the production of PGs in endometriosis, 18 patients with pelvic endometriosis sustained no relief for their endometriotic symptoms from the treatments with three anti-prostaglandins (acetylsalicylic acid, indomethacin, tolfenamic acid) in a double-blind, placebo-controlled trial.

Amniotic fluid prostacyclin and thromboxane in normal, preeclamptic, and some other complicated pregnancies

To study the involvement of the antiaggregatory and vasodilator prostacyclin (PGI2) and proaggregatory and vasoconstrictor thromboxane A2 (TxA2) in complicated pregnancies, we measured by radioimmunoassay the stable metabolites of PGI2 and TxA2, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TxB2), respectively, in samples of amniotic fluid collected at amniocentesis from 88 women between 30 and 40 weeks normal or complicated pregnancy. The concentrations (mean +/- SE) of 6-keto-PGF1 alpha were 171.8 +/- 9.0 pg/ml in normal pregnancies (N = 27), 134.4 +/- 9.3 pg/ml in severe preeclampsia (N = 13) (0.001 less than p less than 0.005 in comparison with normal pregnancy), 175.6 +/- 13.9 pg/ml in mild preeclampsia (N = 14) (0.01 less than p less than 0.05 in comparison with severe preeclampsia), 168.5 +/- 16.9 pg/ml in diabetic pregnancies (N = 14), 158.7 +/- 5.9 pg/ml in rhesus-immunized pregnancies (N = 10), and 178.7 +/- 13.7 pg/ml in pregnancies with intrauterine fetal growth retardation (N = 10). The corresponding TxB2 concentrations were, respectively, 35.0 +/- 5.7 pg/ml, 29.1 +/- 4.6 pg/ml, 31.3 +/- 3.1 pg/ml, 35.3 +/- 4.0 pg/ml, 31.4 +/- 5.9 pg/ml, and 39.2 +/- 3.2 pg/ml, and these levels did not differ from each other. The level of 6-keto-PGF1 alpha in amniotic fluid correlated with the pregnancy week in normal and preeclamptic pregnancies, and the levels of TxB2 in amniotic fluid in normal, preeclamptic, and rhesus-immunized pregnancies. Furthermore, these two prostanoids correlated with each other in normal pregnancy and in all complications except rhesus-immunized pregnancies. Thus, it is evident that the release of PGI2 into the amniotic fluid is decreased in severe preeclampsia.

Prostacyclin in the treatment of neonatal pulmonary hypertension

PERSISTENT pulmonary hypertension often complicates a variety of neonatal distrubances, 1 leads to right-to-left shunting across the ductus arteriosus or foramen ovale, and may thereby cause or exacerbate neonatal hypoxemia. ~ Although vasodilating agents, such as tolazoline, have been used with variable success in the treatment of neonatal pulmonary vasoconstriction, 2 a generally acceptable therapy is still lacking. Prostacyclin (epoprostenol, PGI2) is a potent vasodilatory and antiaggregatory agent that may participate in postnatal pulmonary vasodilation. 3, 4 It has been used successfully in the management of pulmonary hypertension in adults 5 and in one newborn infant. 6 We describe five newborn infants with pulmonary hypertension who received intravascular infusion of PGI2.