Oxidation of corticosteroids to steroidal carboxylic acids by an enzyme preparation from hamster liver

Enzyme activity which catalyzes the oxidation of 11-deoxycorticosterone to 21-oic acids accompanies the "detritiating" enzyme (isomerase) of hamster liver recently isolated by Martin, K. O., et al. ((1977) Biochemistry 16 (preceding paper in this issue)). The metabolites isolated were 20alpha- and 20beta-hydroxy-3-oxo-pregn-4-en-21-oic acid and 3,20-dioxo-pregn-4-en-21-oic acid. When 21-hydroxy[4-14C, 21-3H]pregn-4-en-3,20-dione was the substrate, about half of the tritium was retained in position 20 of the hydroxy acids. The system which catalyzes the conversion of the ketol side chain of corticosteroids to acid metabolites appears to be a cluster of closely related enzymes. As a result of these studies, we believe that the hamster liver enzyme preparation provides a useful model system for studies on the biosynthesis of acid metabolites of the corticosteroids in man.

Study of trans-cyclopropylbis (diketopiperazine) and chelating agents related to ICRF 159. Cytotoxicity, mutagenicity, and effects on scheduled and unscheduled DNA synthesis

The cytotoxicity, mutagenicity, and DNA damaging potential of trans-cyclopropylbis (diketopiperazine) (3) and chelating agents related to ICRF 159 (1) were examined as a function of concentration and duration of exposure in the Chinese hamster cell line V79A. At a concentration of 10(-3) M, 1 and the trans-cyclopropanediamine tetraacid 8 and ester 7 proved to be cytotoxic and mutagenic. The trans-cyclopropyl analogue 3 of ICRF 159 and acyclic tetraacid 6 were less cytotoxic at all concentrations; analogue 3 exhibited no mutagenic activity at any of the concentrations tested. Compounds 1, 7, and 8, at lethal concentrations, exhibited significantly different mutation frequencies with 7 being sixfold more mutagenic than 8 at the same molar concentration. At 10(-3) M compounds 8 was several times more effective blocking DNA replication than other analogues but did not induce unscheduled DNA synthesis as did 1,3, and 6. With the exception of 8, there was an excellent correlation between mutagenesis and the induction of unscheduled DNA synthesis.

Acidic metabolite of prednisolone

The metabolic fate of the 17beta-ketol side chain of (21-3H) prednisolone was studied with an enzyme preparation from male golden hamster liver. The acidic metabolite of prednisolone was identified by mass spectrometry as 11beta, 17alpha,20epsilon-trihydroxy-3-oxo-1,4-pregnadien-21-oic acid. The enzyme showed substrate specificity, depending on the nature of substituent on the steroid nucleus.

Atypical progressive angina pectoris caused by a congenital coronary-pulmonary shunt and coronary atherosclerosis

A 57-year-old man with atypical progressive angina caused by congenital coronary-pulmonary shunt and coronary atherosclerosis is described. The angina was rather consistently unresponsive to nitroglycerin. Following closure of the shunt and aortocoronary bypass surgery, the patient became asymptomatic and has remained free of angina 2 year postoperatively. Although the congenital anomaly is rare in adults, it may be considered in the differential diagnosis of atypical angina pectoris, particularly when there is either continuous murmur or systolic murmur over the lower parasternal area.

Interactions of selenium, cadmium and copper in sheep

Cadmium supplements (7 5 or 15 mg/day) significantly Increased cadmium concentrations in blood, liver, kidney and muscle in sheep and reduced the concentrations of copper and blood and liver. The small amount of selenium released in the rumen from heavy selenium pellets increased selenium levels in blood, liver, kidney and muscle but did not reduce the concentrations of cadmium In these tissues significantly nor counteract the effect of cadmium on copper storage.