Onconase® (ONC) is a member of the ribonuclease A superfamily that is toxic to cancer cells in vitro and in vivo. ONC is now in Phase IIIb clinical trials for the treatment of malignant mesothelioma. Internalization of ONC to the cytosol of cancer cells is essential for its cytotoxic activity, despite the apparent absence of a cell‐surface receptor protein. Endocytosis and cytotoxicity do, however, appear to correlate with the net positive charge of ribonucleases. To dissect the contribution made by the endogenous arginine and lysine residues of ONC to its cytotoxicity, 22 variants were created in which cationic residues were replaced with alanine. Variants with the same net charge (+2 to +5) as well as equivalent catalytic activity and conformational stability were found to exhibit large (> 10‐fold) differences in toxicity for the cells of a human leukemia line. In addition, a more cationic ONC variant could be either much more or much less cytotoxic than a less cationic variant, again depending on the distribution of its cationic residues. The endocytosis of variants with widely divergent cytotoxic activity was quantified by flow cytometry using a small‐molecule fluorogenic label, and was found to vary by twofold or less. This small difference in endocytosis did not account for the large difference in cytotoxicity, implicating the distribution of cationic residues as being critical for lipid‐bilayer translocation subsequent to endocytosis. This finding has fundamental implications for understanding the interaction of ribonucleases and other proteins with mammalian cells.

SSIs and BSIs remain important complications after cardiac surgery in infants.

Few recent studies have assessed the epidemiology of health care-associated infections (HAIs) in the pediatric population after cardiac surgery. A retrospective cohort study was performed to assess the epidemiology of several types of HAIs in children 18 years of age or younger undergoing cardiac surgery from July 2010 to June 2012. Potential pre-, intra-, and postoperative risk factors, including adherence to the perioperative antibiotic prophylaxis regimen at the authors' hospital, were assessed by multivariable analysis using Poisson regression models. Microorganisms associated with HAIs and their susceptibility patterns were described. Overall, 634 surgeries were performed, 38 (6 %) of which were complicated by an HAI occurring within 90 days after surgery. The HAIs included 7 central line-associated bloodstream infections (CLABSIs), 12 non-CLABSI bacteremias, 6 episodes of early postoperative infective endocarditis (IE), 9 surgical-site infections (SSIs), and 4 ventilator-associated pneumonias (VAPs). Mechanical ventilation (rate ratio [RR] 1.07 per day; 95 % confidence interval [CI] 1.03-1.11; p = 0.0002), postoperative transfusion of blood products (RR 3.12; 95 %, CI 1.38-7.06; p = 0.0062), postoperative steroid use (RR 3.32; 95 % CI 1.56-7.02; p = 0.0018), and continuation of antibiotic prophylaxis longer than 48 h after surgery (RR 2.56; 95 % CI 1.31-5.03; p = 0.0062) were associated with HAIs. Overall, 66.7 % of the pathogens associated with SSIs were susceptible to cefazolin, the perioperative antibiotic prophylaxis used by the authors' hospital. In conclusion, HAIs occurred after 6 % of cardiac surgeries. Bacteremia and CLABSI were the most common. This study identified several potentially modifiable risk factors that suggest interventions. Further studies should assess the role of improving adherence to perioperative antibiotic prophylaxis, the age of transfused red blood cells, and evidence-based guidelines for postoperative steroids.

Ribonucleases are evoking medical interest because of their intrinsic cytotoxic activity. Most notably, ranpirnase, which is an amphibian ribonuclease, is in advanced clinical trials as a chemotherapeutic agent for the treatment of cancer. Here, we describe a strategy to create a novel antiviral agent based on bovine pancreatic ribonuclease (RNase A), a mammalian homologue of ranpirnase. Specifically, we have linked the N- and C-termini of RNase A with an amino-acid sequence that is recognized and cleaved by human immunodeficiency virus (HIV) protease. This linkage obstructs the active site, forming an HIV-specific RNase A zymogen. Cleavage by HIV-1 protease increases ribonucleolytic activity by 50-fold. By relying on the proper function of HIV-1 protease, rather than its inhibition, our approach will not engender known mechanisms of resistance. Thus, we report an initial step towards a new class of agents for the treatment of HIV/AIDS.

Background A lack of perioperative antibiotic prophylaxis guidelines for neonates undergoing cardiac surgery has resulted in a wide variation in practice. We sought to: 1) determine the safety of a perioperative antibiotic prophylaxis protocol for neonatal cardiac surgery as measured by surgical site infections (SSIs) rates before and after implementation of the protocol and 2) evaluate compliance with selected process measures for perioperative antibiotic prophylaxis. Methods This quasi-experimental study included all cardiac procedures performed on neonates from July 2009 to June 2012 at a single center. An interdisciplinary task force developed a standardized perioperative antibiotic prophylaxis protocol in the fourth quarter of 2010. SSI rates were compared in the pre-intervention (July 2009 to December 2010) versus the post-intervention periods (January 2011 to June 2012). Compliance with process measures (appropriate drug, dose, timing, and discontinuation of perioperative antibiotic prophylaxis) was compared in the two periods. Results During the study period, 283 cardiac procedures were performed. SSI rates were similar in the pre- and post-intervention periods (6.21 vs. 5.80 per 100 procedures respectively). Compliance with the four process measures significantly improved post-intervention. Conclusions Restricting the duration of perioperative antibiotic prophylaxis after neonatal cardiac surgery to 48 hours in neonates with a closed sternum and to 24 hours after sternal closure was safe and did not increase the rate of SSIs. Compliance with selected process measures improved in the post-intervention period. Additional multicenter studies are needed to develop national guidelines for perioperative prophylaxis for this population.