ABSTRACT
PVP-capped silver nanoparticles with a diameter of the metallic core of 70 nm, a hydrodynamic diameter of 120 nm and a zeta potential of -20 mV were prepared and investigated with regard to their biological activity. This review summarizes the physicochemical properties (dissolution, protein adsorption, dispersability) of these nanoparticles and the cellular consequences of the exposure of a broad range of biological test systems to this defined type of silver nanoparticles. Silver nanoparticles dissolve in water in the presence of oxygen. In addition, in biological media (i.e., in the presence of proteins) the surface of silver nanoparticles is rapidly coated by a protein corona that influences their physicochemical and biological properties including cellular uptake. Silver nanoparticles are taken up by cell-type specific endocytosis pathways as demonstrated for hMSC, primary T-cells, primary monocytes, and astrocytes. A visualization of particles inside cells is possible by X-ray microscopy, fluorescence microscopy, and combined FIB/SEM analysis. By staining organelles, their localization inside the cell can be additionally determined. While primary brain astrocytes are shown to be fairly tolerant toward silver nanoparticles, silver nanoparticles induce the formation of DNA double-strand-breaks (DSB) and lead to chromosomal aberrations and sister-chromatid exchanges in Chinese hamster fibroblast cell lines (CHO9, K1, V79B). An exposure of rats to silver nanoparticles in vivo induced a moderate pulmonary toxicity, however, only at rather high concentrations. The same was found in precision-cut lung slices of rats in which silver nanoparticles remained mainly at the tissue surface. In a human 3D triple-cell culture model consisting of three cell types (alveolar epithelial cells, macrophages, and dendritic cells), adverse effects were also only found at high silver concentrations. The silver ions that are released from silver nanoparticles may be harmful to skin with disrupted barrier (e.g., wounds) and induce oxidative stress in skin cells (HaCaT). In conclusion, the data obtained on the effects of this well-defined type of silver nanoparticles on various biological systems clearly demonstrate that cell-type specific properties as well as experimental conditions determine the biocompatibility of and the cellular responses to an exposure with silver nanoparticles.
ABSTRACT
UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Open reconstructive surgery of the lower ureteric segment in adults often requires large incisions, as the basic prerequisite for such complex procedures is wide exposure. Published experience on minimally invasive techniques in this challenging surgical field, e.g. conventional laparoscopy or robot-assisted laparoscopy, still remains limited. We report our experience from one of the largest single institution series on robot-assisted reconstructive surgery of the distal ureter in adults, with a special focus on technical aspects of the different surgical procedures. OBJECTIVE: To describe the feasibility of and operative techniques used during different daVinci® robot-assisted laparoscopic reconstructive procedures of the distal ureter, and to report the short-term outcome of such procedures. PATIENTS AND METHODS: Between June 2009 and October 2011, 16 patients underwent robot-assisted operations of the distal ureter because of various underlying pathological conditions. We present a description of each procedure, the incidence of perioperative complications and the results of follow-up examination. The data were collected retrospectively using the patients' records and questionnaires sent to the patients and the referring urologists. The follow-up examinations were done at the discretion of the referring urologists. RESULTS: The surgical indications and operative techniques were as follows: seven distal ureteric resections [DUR] with psoas hitch procedures (+/- Boari flap; four), extravesical reimplantation (two) or end-to-end anastomosis (one) because of benign distal ureteric stricture; four DUR with psoas hitch procedure (+/- Boari flap) and pelvic lymphadenectomy for urothelial carcinoma of the ureter; one DUR with psoas hitch procedure and Boari flap because of unexpected locally recurrent prostate cancer; one extravesical reimplantation because of vesico-ureteric reflux; one bilateral intravesical reimplantation of ectopic ureters (as part of a radical prostatectomy); one resection of a non-functioning upper kidney pole with associated megaureter and ureterocele and intravesical reimplantation of lower pole ureter; one resection of pelvic endometriosis and ureterolysis with omental wrap. The median operative duration (including docking/undocking of the robot) was 260 min. There were no intraoperative complications but there was one conversion to open surgery. Complications according to the Clavien-Dindo classification occurred in 12 patients (75%) ≤ 90 days of surgery: 10 (62%) minor (grade I-II) and two (12%) major complications (grades IIIb and IVa, respectively). The median hospital stay after surgery was 7.5 days. At a median follow-up of 10.2 months, 15 patients (94%) remained without signs of urinary tract obstruction and 13 (81%) were asymptomatic. CONCLUSIONS: Robot-assisted reconstructive surgery of the distal ureter is feasible and can be used without compromising the generally accepted principles of open surgical procedures. The functional outcome was good in short-term follow-up and severe postoperative complications were rare.
