This Month in Investigative Urology

Article Outline

• Differential Expression in Clear Cell Renal Cell Carcinoma Identified by Gene Expression Profiling
• Sildenafil for Secondhand Smoke Induced Erectile Dysfunction
• Manual Versus Computer Guidance for Transparenchymal Percutaneous Renal Needle Placement
• Laparoscopic Model of High Intensity Focused Untrasound Renal Tissue Ablation
• New Model for Benign Prostatic Hyperplasia
• Copyright

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Differential Expression in Clear Cell Renal Cell Carcinoma Identified by Gene Expression Profiling 

Renal cell carcinoma (RCC) is a heterogeneous entity, as classified genetically, histologically and clinically. Gene expression profiling has been shown to provide prognostic information on patients with solitary sporadic RCC. However, there is no reliable way to differentiate synchronous renal metastasis from bilateral primary tumors in patients with bilateral RCC. Lane et al (page 849) from Cleveland, Ohio presented data from 38 patients with clear cell RCC (cRCC). They used a cancer cDNA array containing 3,966 genes relevant to cancer or kidney development, and showed that this approach can predict outcomes in patients with unilateral and bilateral RCC. Using a gene expression profile distinguishing aggressive and indolent cRCC among 29 single cRCCs, 16 and 13 were predicted to be indolent and aggressive, respectively. Gene expression profile classification correlated with cancer specific survival at 5 years in 4 of 4 patients with metachronous cRCC but in only 2 of 4 with bilateral synchronous cRCC. The authors concluded that gene expression profiling using cDNA can differentiate between aggressive and indolent cRCC.

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Sildenafil for Secondhand Smoke Induced Erectile Dysfunction 

It is well established that cigarette smoke is associated with the development of erectile dysfunction, and that the underlying cause is decreased endothelial nitric oxide synthase (NOS) activity leading to endothelial dysfunction. However, the precise molecular mechanisms by which cigarette smoke causes erectile dysfunction have not yet been established. Bivalacqua et al (page 899) from Baltimore, Maryland studied the effects in mice of passive secondhand cigarette smoke on erectile function in vivo using cavernous nerve stimulation, and analyzed NOS activity, reactive oxygen species (ROS) generation, nitrotyosine formation and superoxide anion levels. They found that short-term exposure to secondhand smoke impairs in vivo endothelium and neurogenic mediated erectile responses via excessive penile ROS signaling, reduced constitutive NOS (endothelial NOS) activity and inducible NOS activity, leading to endothelial dysfunction. Interestingly the phosphodiesterase inhibitor sildenafil restored constitutive NOS activity and decreased ROS signaling, which resulted in improved erectile function.

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Manual Versus Computer Guidance for Transparenchymal Percutaneous Renal Needle Placement 

Image guided percutaneous procedures are being increasingly performed for the diagnosis and management of a variety of conditions. Skenazy et al (page 867) from New York, New York compared the placement of narrow caliber needles using a novel ultrasound coupled guidance system with other commonly used techniques for ultrasound guided percutaneous interventional procedures. The system has several degrees of freedom and the needle can be pivoted by the user in any dimension, which facilitates the targeting process. The in vitro model consisted of a bath of ultrasound medium with suspended metallic targets. The porcine model was used to test the software guide with and without support arm versus the freehand approach. In the in vitro model and in the porcine study the software guide and support arm were superior to freehand targeting, reducing the time and number of attempts required for successful targeting of simulated parenchymal lesions. They also reduced the subjective difficulty inherent in the standard freehand approach. Thus, this equipment has the potential to facilitate renal targeting for clinicians of all levels of experience.

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Laparoscopic Model of High Intensity Focused Untrasound Renal Tissue Ablation 

High intensity focused ultrasound (HIFU) is an ablative technique that destroys tissue by coagulative necrosis. It is currently used in urology for the treatment of prostate cancer and more recently for the treatment of benign prostatic hyperplasia (BPH). However, for renal lesions HIFU is still experimental and further investigations are needed. Orvieto et al (page 861) from Chicago, Illinois previously demonstrated the safety and efficacy of renal HIFU using a modified version of the standard transrectal prostate HIFU probe inserted through a 33 mm laparoscopic port. In this study they tested the safety and efficacy of a new, specifically designed 18 mm laparoscopic HIFU probe and transducer, and evaluated the efficacy of the newly developed ablation and motion control algorithms using a Sonatherm® 600 HIFU system in a porcine model. They found that laparoscopic HIFU of renal tissue using the newly developed probe was feasible and efficacious, and that it was possible to perform renal HIFU through an 18 mm laparoscopic port. This approach offers a new alternative for renal tumor ablation.

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New Model for Benign Prostatic Hyperplasia 

It has long been known that BPH tissue exhibits stromal hyperplasia, ie it consists mainly of smooth muscle, fibrous tissue elements and collagen. However, to date an adequate animal model has been lacking for the study of the pathological mechanisms of prostate stromal hyperplasia. Mori et al (page 890) from Saitama, Japan developed a model in which a fetal urogenital sinus (UGS) from male rats (20-day embryo) is implanted into pubertal male rat ventral prostate. After 3 weeks the weight of the implanted UGS was shown to increase from 1 to 100 mg and it exhibited a ratio of stroma-to-total area of approximately 70%. Chlormadinone acetate prevented this increase in UGS weight. The authors concluded that this model corresponds to clinical BPH in terms of stromal component composition and functional differentiation of the prostate.