Treatment with connexin 46 siRNA suppresses the growth of human Y79 retinoblastoma cell xenografts in vivo.

Tumors with a hypoxic component, including human Y79 retinoblastoma cells, express a specific gap junction protein, Connexin 46 (Cx46), which is usually only found in naturally hypoxic tissues such as the differentiated lens. The aim of this study was to investigate if Cx46 downregulation would suppress Y79 tumor formation in vivo. Five-week old nude mice were subcutaneously implanted with human Y79 retinoblastoma cells and treated with intratumor siRNA injections of 30 µg Cx46 siRNA (n = 6), 30 µg non-silencing siRNA (n = 6), or no siRNA treatment (n = 6) every 2 days for a maximum of 10 treatments. Tumor volume (TV) was calculated from the recorded caliper measurements of length and width. Excised tumors were measured and weighed. Western blot analyses were performed to evaluate Cx46 and Cx43 expression in tumors which received Cx46 siRNA, non-silencing siRNA, or no siRNA treatment. Tumor histopathology was used to assess tumor features. Cx46 siRNA treated Y79 tumors had a reduced TV (287 mm(3) ± 77 mm(3)) when compared to the tumors of mice receiving the negative control siRNA (894 mm(3) ± 218 mm(3); P ≤ 0.03) or no siRNA (1068 mm(3) ± 192 mm(3); P ≤ 0.002). A 6-fold knockdown of Cx46 and a 3-fold rise in Cx43 protein expression was observed from western blots of tumors treated with Cx46 siRNA compared to mice treated with non-silencing siRNA. Knockdown of Cx46 with siRNA had an antitumor effect on human Y79 retinoblastoma tumors in the nude mouse model. The results suggest that anti-Cx46 therapy may be a potential target in the future treatment of retinoblastoma.

Quality improvement initiative to reduce deep vein thrombosis associated with peripherally inserted central catheters in adults with cystic fibrosis.

RATIONALE: Peripherally inserted central catheters (PICCs) are common in the treatment of patients with cystic fibrosis (CF). Previous reports suggest that patients with CF are at increased risk for PICC-associated deep vein thrombosis (DVT). OBJECTIVES: We assessed potential risk factors for symptomatic PICC-associated DVT with subsequent implementation of a quality improvement (QI) initiative to reduce PICC-associated DVT in patients with CF. METHODS: This was a 5-year retrospective cohort study with subsequent 21-month prospective observation following implementation of a QI intervention in adults (aged 18 yr or older) with CF. All patients with a PICC inserted from July 2006 to March 2013 at our CF Foundation-accredited center were included. Symptomatic DVT was diagnosed by Doppler ultrasound. PICC insertions were analyzed, and nine risk factors for DVT were analyzed to formulate a QI initiative to reduce risk of PICC-associated DVT. The QI program focused on staff education and included modification to PICC order entry with a 4 French (F) single-lumen (SL) catheter as standard for all patients with CF. MEASUREMENTS AND MAIN RESULTS: A total of 369 PICCs were analyzed in 117 unique patients for a total of 5,437 PICC-days of placement. Symptomatic DVT was diagnosed in 28 (7.6%) of the 369 PICCs analyzed. Using regression analysis, the strongest predictors for DVT occurrence were warfarin use (odds ratio [OR] = 9.2, P = 0.006) and history of PICC-associated DVT (OR = 2.97, P = 0.08). Insertion of a 4F SL PICC resulted in zero symptomatic DVT. Zero episodes of DVT associated with 4F PICC insertion prevented use of PICC size in regression analysis. However, univariate analysis revealed that insertion of a 4F SL PICC instead of either 5F double lumen or 6F triple lumen was associated with a reduction in PICC-associated DVT (P = 0.001). After the QI intervention, 4F SL catheter insertion substantially increased to 65.8% of all PICCs inserted, whereas 6F triple-lumen catheter insertion declined to 6.8% of PICCs inserted. The QI initiative resulted in an absolute risk reduction in DVT per PICC placed of 6.1% (P = 0.055). CONCLUSIONS: To reduce risk of PICC-associated DVT in patients with CF, QI strategies should focus on insertion of smaller-diameter 4F PICCs and reduction in PICC use in high-risk patients when possible.