Pharmacologic and clinical studies of N4-behenoyl-1-beta-D-arabinofuranosylcytosine

Two metabolites of N4-behenoyl-1-beta-D-arabinofuranosylcytosine (BH-AC) were found in the plasma and urine, and a hydrolytic product, arabinosylcytosine (ara-C) and its deaminated product, arabinosyluraci (ara-U), were found in a preclinical study using monkeys. Of a given dose, 96% was found as ara-U and 3% as ara-C in urine in 24 h. The plasma disappearance curve of BH-AC is biphasic; the half-life of the initial phase is 40 min and that of the second phase is 120 min. At 8 h the BH-AC level is 21.9 micrograms/ml and falls exponentially to 3.6 micrograms/ml by 12 h. Ara-C was detected at the levels of 0.4-0.6 microgram/ml for 4 h. Comparative data of pharmacokinetic parameters among BH-AC, ara-C, and O2,2'-cyclocytidine showed that BH-AC had the longest plasma half-life, the smallest elimination-rate constant and the smallest excretion-rate constant. The plasma-clearance study of BH-AC in 13 patients showed essentially a pattern similar to that in monkeys; the plasma t 1/2 of 60 min in the first phase and of 180 min in the second. The BH-AC level at 2 h is 15.4 micrograms/ml, and 1.8 microgram/ml at 8 h. Initial phase I study of BH-AC was evaluated in 14 patients with leukemia and other malignancies. The starting dose was 1.5 mg/kg given as a single IV infusion for 3. The doses were when escalated up to 5.0 mg/kg. No side effects were noted with a single dose schedule. Daily consecutive infusions of 2.0 mg/kg-6.0 mg/kg for 4-21 days resulted in two patients having nausea, two anorexia, and one developing skin eruptions. Significant hematologic effects were noted with the daily infusion. One patient with acute myeloblastic leukemia achieved complete remission with 5.0 mg/kg BH-AC given daily for 21 days. It pharmacologic features, minimal toxicity, and the capability of inducing complete remission in acute leukemia indicate that BH-AC undoubtedly deserves further prospective clinical trials.

Inactivation of the mitogenic property of pokeweed mitogen by erythrocytes

In whole blood culture, pokeweed mitogen (PWM) is unable to stimulate human lymphocytes. This is because the mitogenic property of PWM is inactivated by erythrocytes, presumably due to absorption. The inactivation was observed with as few as 5 x 10(6)/ml of human erythrocytes. Therefore, when PWM is used to study the functions of human lymphocytes, especially of suppressor T lymphocytes, erythrocytes should be removed from lymphocyte preparations for accurate analysis.

Echocardiographic features of Uhl's anomaly. A case report

M-mode echocardiography on a fifty-eight year old female with Uhl's anomaly showed several characteristic findings, which were considered to be useful in differentiating Uhl's anomaly from Ebstein's. Those findings were normal tricuspid diastolic closing velocity, the relatively early tricuspid valve opening, easy visualization of the tricuspid valve in usual position and the unusual mid-diastolic pulmonic valve full opening. The premature opening of the pulmonic valve correlated with the right atrial and ventricular mid-diastolic pressure exceeding that of the pulmonary artery.