Relationship of serum theophylline concentration to inhibition of exercise-induced bronchospasm and comparison with cromolyn

Exercise-induced bronchospasm was induced by treadmill running in 12 children on two days preceding either inhaled cromolyn sodium (Intal) or oral theophylline (Slo-Phyllin tablets), 7.5 mg/kg, administered in a double-blind manner. A second exercise period identical to the first followed two hours later; the medication administration had been timed so that the second exercise stress followed two hours after theophylline administration and 15 minutes following cromolyn administration. The patients subsequently were exercised twice more at two-hour intervals on both days. Blood was drawn from serum theophylline measurement immediately after each of the exercise periods. There was little demonstrable exercise-induced bronchospasm resulting from the first postmedication exercise period following theophylline administration. The two subsequent exercise periods were associated with some return of postexercise bronchospasm. The degree of inhibition of exercise-induced bronchospasm correlated with serum theophylline levels that averaged 16, 13, and 10 microgram/ml at two, four and six hours after the theophylline dose (mean Spearman rank correlation coefficient = .71, P less than .01). The effect of cromolyn in suppression exercise-induced bronchospasm that matched or excelled that seen with theophylline.

Rh isoimmunization, Manitoba, 1963-75

The number of Rh-isoimmunized pregnancies in Manitoba has been reduced from 223 and 228 in the years ending Oct. 31, 1963 and 1964 to 60 and 62 in the years ending Oct. 31, 1974 and 1975. The number per 1000 total births in the same years has decreased from 10.0 and 10.6 to 3.4 and 3.5 Perinatal mortality rates in those years decreased from 13.8 amd 15.7% to 0 and 2.2%, respectively. The number of perinatal deaths has been reduced from 55 in the first 2 years reported to 1 in the last 2 years. Among the 121 isoimmunized women pregnant in the 2-year period ending Oct. 31, 1975, isoimmunization was due to failure to give Rh immune globulin after delivery in 33 and failure to give it during pregnancy in 48. Of the remaining 40, 37 were immunized before Rh immune globulin became available. Complete prevention of Rh isoimmunization and therefore of all perinatal deaths from Rh erythroblastosis can only be achieved through universal Rh testing prenatally and immediately after delivery, and institution of an antenatal Rh prophylaxis program.

An error in Rh testing in pregnancy

Anti-D (anti-Rho) in the blood of two Rh-negative pregnant women was believed to be due to active immunization. In the first case, however, antibodies were no longer detectable 2 weeks later. In the second case they disappeared by the end of 31 weeks. It was discovered that both women had been given immune globulin (human) because of exposure to rubella. The globulin given to the first woman probably contained about 0.1 mug of anti-D per ml; that given to the second probably contained about 0.6 mug of anti-D per ml. Both babies were O Rh-positive. Both women were given Rh immune globulin after delivery. Both have completed a further pregnancy and no anti-D has been found on many tests. In tests carried out in 1971 all samples of immune globulin (human) examined contained anti-D, but usually in inconsequential trace amounts.

The effect of anti-D IgG on D-positive recipients

When one standard prophylactic dose of anti-Rh(D) immunoglobulin (Connaught) (and in one case two doses) was injected into 15 D-positive volunteers it caused no reaction and no measurable alteration in readings of hemoglobin, hematocrit, reticulocytes or bilirubin, although some of the volunteers briefly became weakly direct Coombs'-positive. It is argued that since any isohemagglutinin that may contaminate anti-D IgG must be much less in amount than the anti-D it contains, the contaminating antibody cannot carry a greater potential for harm to a recipient having the corresponding antigen than the anti-D for a D-positive recipient, which is zero. It is suggested that the presence of anti-DC or G in so-called anti-Rh(D) IgG may, in fact, be a mark of excellence. The application of these facts to selection of plasma donors and to tests required before giving prophylactic treatment to women is briefly stated.