Summary— 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.
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
Photoacoustic microscopy (PAM) is a non-invasive and hybrid optical imaging technique that has a potential to visualize chorioretinal vasculature in vivo. The capability of PAM can be extended to better visualize the dynamic changes of the vasculature network in the retina when it is combined with another imaging modality such as fluorescence microscopy or OCT. In this study, an integrated PAM and OCT has been developed to identify the local tissue damage during laserinduced photocoagulation on major choroidal vessels. Choroidal lesion was induced using a high power green light laser at 532 nm with millisecond pulse duration in eight New Zealand rabbits. Each rabbit eye was irradiated for 0.5 s at a laser power of 750 mW and spot size of 100 μm. Six laser burn positions were created on each eye. At each laser burn, twenty shots of the laser were applied. Multimodal PAM, OCT, fundus, and FA were used to monitor thermal lesion at different time points (days 0, 1, 3, 5, 7, 14, 21, and 28) after photocoagulation. All thermal lesions were clearly identified with high resolution using PAM. In addition, the PAM images exhibited dynamic changes of density and morphology of choroidal vasculature. The OCT images provided visualization of the cross-sectional structure of retinal tissues and the location of thermal lesion. Multimodal PAM and OCT can provide a feasible tool for evaluation and monitoring of damaged tissues and the microvasculature of the retina.
Summary— 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.
Summary— The effects of irrigation with sterile and infected saline after acute ureteric dilatation by graded Teflon dilators were evaluated renographically and histologically in minipigs. The minipig ureter was dilated from its normal calibre of 4 F to 10 F, and 100 ml of sterile or infected saline were then introduced from a height of 60 cm under gravity. One week after irrigation and dilatation the ipsilateral kidney was either functioning less than 10% or there was an obstructive nephropathy. Histology at 3 months suggested that extravasation of infected irrigating fluid was the most likely cause of ureteric stricture formation.
pected by him; he certified it as due to pneumonia.It was carefully concealed from him that the deceased suffered from vomiting, purging, and intense pain in the abdominal region.Mr. Rafter expressed his opinion, after hearing all the evidence, that the deceased had died from poisoning by arsenic.
In the near-infrared optical window (NIR, 650 to 1000 nm), biological tissue generates a low intrinsic photoacoustic (PA) signal. This window can be utilized to reduce the background noise, and thus enhance visualization of contrast agents. Exogenous contrast agents have been investigated and co-applied with photoacoustic imaging such as organic materials (indocyanine green, astaxanthin, Prussian blue) and inorganic materials (gold nanorods, gold nanostars). However, these available contrast agents are usually associated with low thermal stability or large size, leading to unreliable photoacoustic signal. Conventional gold nanoparticles have an absorption peak of 520 nm, which corresponds to the absorption spectrum of hemoglobin. This study investigated the synthesis of novel ultrapure, biocompatible, and photostable chain-like gold nanoparticles (CGNPs), which shift the peak absorbance of GNPs from visible window (520 nm) to NIR window, while keeping the GNPs at a smaller size. These GNPs were fabricated by a femtosecond laser and were combined together with two organic polymers. The surface was then modified with PEG and conjugated with RGD ligands. The capacity of CGNPs for photoacoustic microscopy (PAM) and OCT were examined on 4 white New Zealand rabbits using a choroidal neovascularization (CNV) model. CNV was created by laser-induced retinal vein occlusion. Then, all animals were administered GNPs at concentration of 5 mg/mL. PAM and OCT were obtained before and after the injection at various time points, including 2 h, 4 h, 8 h, 24 h, days 2, 3, 5, 7, 9. 11, and 14. In vivo PAM and OCT imaging demonstrated that CNV was observed after the injection of CGNPs. In comparison with the signal before the injection, CGNPs produces 18- fold greater photoacoustic contrast and exhibits a 176 % increase in OCT signal, given the reduced background signal in the NIR window. The newly fabricated CGNPs have the capacity to improve visualization in living animals, while minimizing signal from hemoglobin and other endogenous contrast agents.
Photoacoustic microscopy (PAM) can be an effective imaging modality to visualize retinal vein occlusion during laserinduced photocoagulation on major retinal veins. Developments in the vessels could be observed before and after laser irradiation due to the change of the optical absorption spectrum of the target vessels. However, the suitable wavelength to achieve high contrast PAM images of occluded vessels is unclear. This study evaluates the effect of wavelength on PAM imaging to evaluate the photocoagulation lesions on the rabbit to optimize the wavelength for imaging. Retinal vein occlusion (RVO) was created using a 532 nm millisecond pulse duration green light with concurrent intravenous administration of Rose Bengal (5 mg/kg) in New Zealand rabbits. Imaging was acquired by the PAM system at various wavelengths ranging from 520 nm to 590 nm. In addition, the thermal lesion was also confirmed using optical coherence tomography (OCT). A group of 20 retinal veins was irradiated for 0.5 s at a laser fluence of 850 W/cm2 (power = 150 mW, beam diameter = 75 μm). Twenty shots of the laser were applied to each major vein. PAM results showed that the thermal lesion was obviously visualized and exhibited lower contrast in comparison with untreated vessels posttreatment. Photoacoustic spectroscopy exhibited that the highest PA contrast of vessels treated with Rose Bengal laserinduced RVO occurred at a wavelength of 563, 570, and 578 nm, which was higher than the PA amplitude at lower and longer wavelengths respectively. The use of multi-wavelength PAM can provide a better method for visualization and evaluation of retinal vein occlusions.
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