Urinary catheterization of male rabbits: a new technique and a review of urogenital anatomy.

Rabbits are widely used as an animal model for urologic research studies in which urinary bladder catheterization is required. However, standard manual retrograde urinary catheterization proved to be difficult to perform on anesthetized male rabbits in a research study, with frequent misplacement of the catheter into the vesicular gland. Attempts to reposition the catheter into the bladder after initial entry into the vesicular gland frequently failed and resulted in exclusion of the animal from the study. We assessed the normal anatomy of the lower urinary tract of male rabbits to determine the cause of catheterization misdirection into the vesicular gland and to develop a more reliable technique for urinary bladder catheterization. A modified 'digital (finger) pressure' catheterization technique was developed for successful urinary catheterization of male rabbits. Retrospective statistical analysis of 45 rabbits used for urinary catheterization studies showed improvement in the success rate of catheterization by using the digital pressure technique over the standard method of retrograde urinary catheter insertion. In addition, we here review the relevant gross and histologic anatomy of the urogenital tract of male rabbits.

Imaging long-term fate of intramyocardially implanted mesenchymal stem cells in a porcine myocardial infarction model.

The long-term fate of stem cells after intramyocardial delivery is unknown. We used noninvasive, repetitive PET/CT imaging with [(18)F]FEAU to monitor the long-term (up to 5 months) spatial-temporal dynamics of MSCs retrovirally transduced with the sr39HSV1-tk gene (sr39HSV1-tk-MSC) and implanted intramyocardially in pigs with induced acute myocardial infarction. Repetitive [(18)F]FEAU PET/CT revealed a biphasic pattern of sr39HSV1-tk-MSC dynamics; cell proliferation peaked at 33-35 days after injection, in periinfarct regions and the major cardiac lymphatic vessels and lymph nodes. The sr39HSV1-tk-MSC-associated [(18)F]FEAU signals gradually decreased thereafter. Cardiac lymphography studies using PG-Gd-NIRF813 contrast for MRI and near-infrared fluorescence imaging showed rapid clearance of the contrast from the site of intramyocardial injection through the subepicardial lymphatic network into the lymphatic vessels and periaortic lymph nodes. Immunohistochemical analysis of cardiac tissue obtained at 35 and 150 days demonstrated several types of sr39HSV1-tk expressing cells, including fibro-myoblasts, lymphovascular cells, and microvascular and arterial endothelium. In summary, this study demonstrated the feasibility and sensitivity of [(18)F]FEAU PET/CT imaging for long-term, in-vivo monitoring (up to 5 months) of the fate of intramyocardially injected sr39HSV1-tk-MSC cells. Intramyocardially transplanted MSCs appear to integrate into the lymphatic endothelium and may help improve myocardial lymphatic system function after MI.

A pilot trial of vascular targeted photodynamic therapy for renal tissue.

PURPOSE: Vascular targeted photodynamic therapy represents the newest generation of photodynamic therapy and a new paradigm for minimally invasive ablative therapy. We report a pilot trial of vascular targeted photodynamic therapy to evaluate the effect on porcine renal tissue. MATERIALS AND METHODS: Pigs underwent continuous infusion of WST-09 (Negma-Lerads, Toussous le Noble, France) and concurrent illumination with interstitial laser at a wavelength of 763 nm to the lower pole of the kidney. Drug doses were 0.5 to 1.0 mg/kg and light doses were 100 to 200 J. Nuclear renography was performed on postoperative day 5. On postoperative day 7 arteriography, pyelography, computerized tomography of the abdomen and necropsy were performed. RESULTS: Four of 7 animals completed therapy and all evaluations. Three animals died, including 1 of surgical complications and 2 of an anaphylactoid reaction to the Cremophor solvent in the compound. All kidneys in surviving animals functioned on nuclear renography. Renal function remained unchanged. No lesions or urine leakage was visible on imaging. On necropsy lesion size was 5 x 4 x 3 to 7 x 7 x 14 mm depending on the drug/light dose. Histology showed a distinct demarcation between the treated zone and the surrounding parenchyma at higher doses. Lesions were well demarcated with necrotic tubules, glomerular fibrinoid necrosis, capillary loop thrombosis, interstitial hemorrhage and lymphocytic infiltrates. CONCLUSIONS: Significant tissue effect with some necrosis was seen at these low drug/light combinations. This study provides the initial proof of principle that justifies further preclinical investigation of vascular targeted photodynamic therapy for renal tumors. A newer, water based formulation should decrease the incidence of reactions in swine. This newer formulation may allow further safe investigation of this novel treatment paradigm.

Evaluation of cerebral microemboli during radiofrequency ablation of lung tumors in a canine model with use of impedance-controlled devices.

PURPOSE: To evaluate the incidence of cerebral microemboli during radiofrequency (RF) ablation of lung tumors in a canine model and evaluate the adverse effects of these microemboli on the brain parenchyma with use of magnetic resonance (MR) imaging and histopathologic examination. MATERIALS AND METHODS: Percutaneous RF ablation of 12 lung tumors in 12 dogs was performed under computed tomography (CT) guidance with use of impedance-controlled devices. The common carotid artery was continuously monitored in each animal during RF ablation with duplex Doppler ultrasonography. All animals underwent brain MR imaging shortly after RF ablation. Delayed brain MR imaging (5-8 days after RF ablation) was performed in eight animals. The MR examinations included diffusion-weighted echo-planar imaging. The animals were euthanized 3-11 days after RF ablation. The brain was harvested from each animal and examined by an experienced veterinary pathologist for evidence of ischemia. RESULTS: RF ablation was technically successful in all animals. Microbubbles were detected in the carotid artery in two animals (17%). Acute and delayed MR studies demonstrated no evidence of ischemic brain injury in any of the animals. Gross and histopathologic assessment of brain tissue also demonstrated no ischemic changes. CONCLUSIONS: During RF ablation of lung tumors, microbubbles are detected in the carotid arteries in a small number of cases. These microbubbles are too few and too small to be detected by CT imaging of the brain and do not cause ischemic brain injury.