Leinamycin is a structurally novel Streptomyces-derived natural product that displays very potent activity against various human cancer cell lines (IC 50 values in the low nanomolar range). Previous in vitro biochemical studies have revealed that leinamycin alkylates DNA, generates apurinic (AP) sites and reactive oxygen species (ROS), and causes DNA strand breaks. However, it is not clear whether these events occur inside cells. In the present study, we have determined the endogenous amount of AP sites and DNA strand breaks in genomic DNA and the amount of oxidative stress in a human pancreatic carcinoma cell line, MiaPaCa, treated with leinamycin by utilizing the aldehydereactive probe (ARP) assay, the comet assay, and fluorescent probes, respectively. We demonstrated that AP sites are formed rapidly following exposure to leinamycin, and the number of AP sites was increased up to seven-fold in a dose dependent manner. However, only 25-50% of these sites remain 2 h after media containing drug molecules was aspirated and replaced with fresh media. We also observed leinamycin induced ROS generation and a concomitant increase in apoptosis of MiaPaCa cells. Because both AP sites and ROS have the potential to generate strand breaks in cellular DNA, the comet assay was utilized to detect damage to nuclear DNA in leinamycin-treated MiaPaCa cell cultures. Both alkaline and neutral electrophoretic analysis revealed that leinamycin produces both single-and double-stranded DNA damage in drug-treated cells in a dose-dependent manner. Taken together, the results suggest that rapid conversion of leinamycin-guanine (N7) adducts into AP sites to produce DNA strand breaks, in synergy with leinamycin-derived ROS, account for the exceedingly potent biological activity of this natural product.

No abstract

Objective. To describe the landscape of teaching and learning curriculum (TLC) programs sponsored by US schools and colleges of pharmacy and evaluate their adoption of best practice recommendations. Methods. A 28-item electronic survey instrument was developed based on best practice recommendations published by the American Association of Colleges of Pharmacy (AACP), American Society of Health-System Pharmacists (ASHP), and American College of Clinical Pharmacy (ACCP) for the conduct of TLC programs. The survey instrument was electronically distributed to 137 accredited colleges and schools of pharmacy in the United States. Results. Eighty-eight institutions responded, resulting in a response rate of 64%. Sixty-one TLC programs were included in the final analysis. Seventy-five percent of TLC programs reported using best practice recommendations; however, 10% of respondents indicated they were not aware of the published recommendations. Inconsistencies among programs were noted in required teaching experiences, participant evaluation, and ongoing programmatic assessment. Conclusion. Most institutions offering TLC programs are aware of published best practice guidelines and have adopted a majority of the published best practices. However, considerable variability exists across the country. Development of a formal external validation process for TLC programs is necessary to ensure consistent quality.

If externally validated in future studies, a tool for predicting the risk of recurrent CDAD using data readily available at the time of presentation could allow clinicians to identify patients at high risk for recurrence, address modifiable risk factors, and select tailored treatments to improve patient outcomes.