Dynamic light scattering-based method to determine primary particle size of iron oxide nanoparticles in simulated gastrointestinal fluid.

Simple dynamic light scattering (DLS)-based methodologies were developed to determine primary particle size distribution of iron oxide particles in simulated gastrointestinal fluid. Iron oxide particles, which easily agglomerate in aqueous media, were converted into dispersed particles by modification of surface charge using citric acid and sodium citrate. After the modification, zeta-potential value decreased to -40mV at pH 7. Mean particle diameters in suspensions of iron oxide nano- and microparticles stabilized by the mixture of citric acid and sodium citrate were dramatically decreased to 166 and 358nm, respectively, which were close to the particle size distributions observed in the micrographs. In simulated gastrointestinal fluid, both iron oxide nano- and microparticles were heavily agglomerated with particle diameters of almost 2600 and 5200nm, respectively, due to charge shielding on the citrate-modified surface by ions in the media. For determining primary particle size distribution by using DLS-based approach, the iron oxide particles incubated in the simulated gastrointestinal fluid were converted to monodisperse particles by altering the pH to 7 and electrolyte elimination. The simple DLS-based methodologies are well suited to determine primary particle size distribution of mineral nanoparticles at various physical, chemical, and biological conditions.

Preoperative comorbidities and relationship of comorbidities with postoperative complications in patients undergoing transurethral prostate resection.

PURPOSE: We retrospectively identified preoperative comorbidities and analyzed the relationship of the comorbidities to postoperative complications in patients treated with transurethral prostate resection. MATERIALS AND METHODS: We reviewed the surgical and clinical records of 1,878 patients who underwent transurethral prostate resection at a single university hospital between January 2006 and December 2009. Variables included preoperative comorbidities, intraoperative data and postoperative complications, including mortality. RESULTS: Only 32.6% of the patients had no observed preoperative comorbidity and the other 67.4% had at least 1. The incidence of comorbidities increased with age (p <0.001). The overall postoperative complication rate was 5.8%. There were 3 deaths for an overall 0.16% 30-day mortality rate. The postoperative complication rate was significantly higher in patients who had a comorbidity preoperatively and were 50 to 59 (p = 0.043), 60 to 69 (p = 0.028) and 70 to 79 years old (p = 0.017). The Charlson comorbidity index was significantly associated with postoperative complications (r(2) = 0.221, p = 0.012). CONCLUSIONS: Almost two-thirds of the patients who underwent transurethral prostate resection had various preoperative comorbidities. The fact that the preoperative comorbidity was significantly related to postoperative complications after transurethral prostate resection should be considered in perioperative management in this population.