Caspase-independence and characterization of bisnaphthalimidopropyl spermidine induced cytotoxicity in HL60 cells.

Bisnaphthalimides are DNA intercalators of potential use as chemotherapeutics but for which the range of mechanism of action is only gradually being elucidated. Using human promyelocytic HL-60 cells, we extend characterization of the cytotoxicity of bisnaphthalimidopropylspermidine (BNIPSpd) and examine the relationship with caspase-activity. Within 4 h exposure, BNIPSpd (1-10 µM) induced significant DNA strand breakage. Evidence of apoptosis was progressive through the experimental period. Within 6 h, BNIPSpd increased the proportion of cells exhibiting plasma membrane phosphatidylserine exposure. Within 12 h, active caspase expression increased and was sustained with 5 and 10 µM BNIPSpd. Flow cytometric analysis revealed caspase activity in cells with and without damaged membranes. By 24 h, 5 and 10 µM BNIPSpd increased hypodiploid DNA content and internucleosomal DNA fragmentation (DNA ladders) typical of the later stages of apoptosis. 1 µM BNIPSpd exposure also increased hypodiploid DNA content by 48 h. Polyamine levels decreased by 24 h BNIPSpd exposure. The pan-caspase inhibitor, z-VAD-fmk, significantly decreased DNA degradation (hypodiploid DNA and DNA ladders) and cytotoxicity. Despite this, cell growth and viability remained significantly impaired. We propose that BNIPSpd cytotoxicity arises through DNA damage and not polyamine depletion and that cytotoxicity is dominated by but not dependent upon caspase driven apoptosis.

Cross-sectional survey of patients in receipt of long-term repeat prescriptions for antidepressant drugs in primary care.

This cross-sectional survey describes the clinical characteristics of 92 patients from across 12 general medical practices, in receipt of a long-term repeat prescription of an antidepressant for the treatment of depression. Psychiatric diagnoses were determined using the Schedule for Clinical Assessment in Neuropsychiatry. Fifty-three participants (57.6%) failed to meet criteria for any psychiatric diagnosis (95% confidence interval (CI): 47.5-67.7%). Independent clinical assessments based upon diagnoses and other clinical data indicated that 26 (31.0%) participants (95% CI: 28.9-49.7%) had no clear clinical reason for continued receipt of an antidepressant. Reasons for the continued use of antidepressants in this population require further investigation.