Although photoacoustic microscopy (PAM) and optical coherence tomography (OCT) allow visualization of the retinal microvasculature, distinguishing early neovascularization from adjacent vessels remains challenging. Herein, gold nanostars (GNSs) functionalized with an RGD peptide were utilized as multimodality contrast agents for both PAM and OCT. GNSs have great absorption and scattering characteristics in the near-infrared region where most vasculature and tissue generates a less intrinsic photoacoustic signal while having a small size, excellent biocompatibility in vivo, and great photostability under nanosecond pulsed laser illumination. This enabled visualization and differentiation of individual microvasculature in vivo using multimodal PAM and OCT imaging. Detailed three-dimensional imaging of GNSs was achieved in an important choroidal neovascularization model in living rabbits. Through the administration of GNSs, PA contrast increased up to 17-fold and OCT intensities increased 167%. This advanced molecular-imaging platform with GNSs provides a unique tool for detailed mapping of the pathogenesis of the microvasculature.

The effects of three methods of acute ureteric dilatation (by graded Teflon dilators, low and high pressure balloon dilators) were evaluated radiologically, renographically and histologically in minipigs. The minipig ureter was dilated from its normal calibre of 4 F to 10 F. All three methods caused upper urinary tract dilatation and an obstructive nephropathy which had not resolved 96 h after dilatation. Histology at 24 h showed destruction of the transitional epithelium, with inflammation throughout the ureteric wall. Four weeks after dilatation the ureter was still dilated and urothelial nests were seen in the lamina propria and in the muscle coats. There was no evidence of ischaemic necrosis or ureteric stricture formation. The implications of these findings for clinical practice are discussed.

Urothelial biopsies from ureters intubated with silicone (11) and other polymer (13) double J stents revealed features of mucous metaplasia in 12/24 cases. These changes were associated with encrustation of the stents and occurred principally in stone-forming patients.