Myeloablation with diaziquone: in vitro assessment.

UNLABELLED: The promising antineoplastic agent diaziquone is associated with prolonged aplasia and rare instances of bone marrow necrosis, but only mild extramedullary toxicity. To explore the drug's potential as a myeloablative agent prior to bone marrow transplantation, we compared its effects on hematopoietic versus marrow stromal cells. After short-term (one to six hours) or prolonged (three to seven days) exposure to the drug, marrow was assayed for hematopoietic (CFU-Mix, BFU-E, CFU-GM) and stromal (CFU-F) colony-forming cells and studied in long-term marrow culture (LTMC). One- and three-hour treatments produced little cytotoxicity, even at 5000 ng/mL. After six-hour treatments with this dose, marrow was depleted of CFU-Mix, BFU-E, and CFU-GM, but produced CFU-GM in LTMCs, indicating an ongoing input of CFU-GM from a surviving pre-CFU-Mix population. In contrast, elimination of the latter may be inferred from the absence of CFU-GM in LTMCs exposed for three to seven days to diaziquone at only 150 ng/mL. Under these conditions, CFU-F recovery was 40% and adherent stromal layers in LTMCs were similar to untreated controls regarding rate of development and cellular composition. Our in vitro pre-CFU-Mix-ablative regimen correlates with clinical data that show prolonged but reversible myelosuppression at steady-state diaziquone plasma levels of 101 +/- 10 ng/mL (mean +/- standard error of mean) during 7-day constant infusions. IN CONCLUSION: hematopoietic cells are more sensitive than marrow stromal cells to the dose- and highly time-dependent cytotoxicity of diaziquone, a direct drug-induced noxious effect on the marrow microenvironment is an unlikely cause of the isolated episodes of marrow necrosis after the use of diaziquone in vivo, and prolonged infusion of diaziquone represents an attractive means for achieving myeloablation in selected clinical situations.

Renal toxicity of propyleneimine: assessment by non-invasive techniques in the rat.

The nephrotoxicity of three different dose levels of propyleneimine (10, 20 and 30 microliter/kg body wt) administered intraperitoneally to rats was studied and 20 microliters/kg body weight was found to be the most appropriate sublethal dose. Injection of propyleneimine (10 microliters/kg body wt) produced a small rise in N-acetyl-beta-D-glucosaminidase (NAG) activity, minor histological damage but no change in urine volume. Six rats were injected with 20 microliters/kg body weight, and urine was collected over the following 16 days. An immediate increase in urine volume, osmolality together with a concomitant decrease in specific gravity, was accompanied by a small increase in creatinine excretion and a more marked increase in the sodium and potassium content of urine after the administration of the nephrotoxin. NAG activity increased immediately and peaked on day 3, the activity remained elevated until day 12 when it fell to near normal levels. The activity of both beta-D-galactosidase and beta-D-glucosidase increased 9 days after administration of the nephrotoxin. In contrast, no consistent change was found in the excretion of the brush border marker enzymes, leucine aminopeptidase (LAP), alanine aminopeptidase (AAP) or alkaline phosphatase (ALP). Proteinuria increased sharply the day after injection and remained abnormal. Increased urinary albumin excretion and the predominance of low molecular weight proteins was demonstrated by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Evidence is presented that propyleneimine exerts its early toxic effect on the renal papilla.