This Month in Investigative Urology

Article Outline

• CO2 Pneumoperitoneum Causes Renal Cell Death
• Artifactual Supranormal Differential Renographic Evaluation of Large Hydronephrotic Kidneys
• Urine is Necessary to Provoke Bladder Inflammation
• Wave1 is Associated With Prostate Cancer Cell Invasiveness
• Urethral Reconstruction With Keratinocyte Seeded Bladder Acellular Matrix Grafts
• Copyright

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CO₂ Pneumoperitoneum Causes Renal Cell Death 

Laparoscopically recruited kidneys regain normal function more slowly than laparotomy harvested organs for several possible reasons. Khoury et al (page 1554) from Tel Aviv, Israel investigated the effects of CO₂ induced pneumoperitoneum on kidney function as reflected by blood and urine creatinine levels, and its relation to renal cell apoptosis. CO₂ pneumoperitoneum was established in anesthetized male rats randomly allocated into separate groups with an intraperitoneal pressure of 0 (control), 5, 8, 12, 15 or 18 mm Hg. Pressure was maintained for 30 to 60 minutes in all groups. Blood and urine creatinine levels were analyzed, and the abdominal organs were harvested. Various areas of the organs were analyzed for apoptotic cells using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. Creatinine levels in blood and urine changed as pressure and pneumoperitoneum duration progressed. Isolated TUNEL positive nuclei were detected in the outer medulla and the cortex of control kidneys. There was a significantly higher number of TUNEL positive nuclei in the cortex and the medulla of all pressurized kidneys, which increased in parallel with increasing intraperitoneal pressure and pneumoperitoneum exposure time. The CO₂ pneumoperitoneum gradient and its duration affect renal function and induce apoptosis. This mechanism could be involved in delayed renal graft dysfunction in recipients of laparoscopically harvested kidneys.

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Artifactual Supranormal Differential Renographic Evaluation of Large Hydronephrotic Kidneys 

It is postulated that significant obstruction leads to decreased ipsilateral renal function. However, maintained or even increased differential renal function is often seen in patients with large hydronephrotic kidneys, the reason for which is unclear. Pippi Salle et al (page 1559) from Toronto, Ontario, Canada designed an in vitro and ex vivo experimental model that permits controlled orientation of thinned renal parenchyma and background activity during gamma camera detection. A 5-step experimental study was designed with balloons or reservoirs containing known amounts of radioisotope. A balloon was incrementally compressed between 2 pieces of plexiglass. Simultaneous measurement of radio emission in 5 glass beakers of varying diameters filled with the same amount of water and ^99mtechnetium was performed. In addition, a single beaker containing diluted ^99mtechnetium was interfaced with air or water at various distances from the gamma camera. Finally, pig kidneys previously injected with dimercapto-succinic acid were removed and scanned. One of the kidneys was then progressively sliced, thinning the parenchyma, and sliced and nonsliced kidneys were simultaneously rescanned. Progressively increased counts were detected as the projected surface area of the radioactive balloons and beakers increased. Counts detected were inversely proportional to the amount of water interfaced between the container and the gamma camera. Significantly more radiation was detectable from sliced dimercapto-succinic acid containing kidneys than the intact control kidneys. These findings suggest that artifactual supranormal differential renal function observed during renographic evaluation of large hydronephrotic kidneys does exist. Parenchymal proximity and distribution in relation to the pelvis are critical determinants. Thus, the conjugate view technique may be more suitable for renographic evaluation of large hydronephrotic kidneys.

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Urine is Necessary to Provoke Bladder Inflammation 

The bladder is normally impermeable to possible hostile environmental factors and toxic urinary wastes. Any disruption of the permeability barrier would permit the leakage of urine constituents into the underlying cell layers and subsequent inflammation. Protamine sulfate, which increases urothelial permeability, is used in experimental models of cystitis. Soler et al (page 1527) from Sao Paulo, Brazil examined whether protamine sulfate alone could cause bladder inflammation or if the association of protamine sulfate and urine is needed for this condition.

Female rats had the bladder catheterized and instilled with protamine sulfate or sterile saline. To exclude urine other groups of rats underwent bilateral nephrectomy and the same procedure was performed. The intravesical instillation of protamine sulfate in nonnephrectomized rats led to inflammation in contrast to the findings in rats instilled with saline. Nephrectomized rats exhibited no inflammatory changes after the instillation of protamine sulfate or saline. Bladder inflammation in this experimental model of urothelial injury was not due to protamine sulfate alone. The association of protamine sulfate and urine was necessary to trigger the inflammatory cascade. Thus, urine has an important role in the development of bladder inflammation in an environment of higher urothelial permeability.

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Wave1 is Associated With Prostate Cancer Cell Invasiveness 

Acquisition of the ability to migrate and invade tissues allows cancer cells to proliferate in tissues (growth), expand to adjacent tissues (invasion) and spread to distant organs (metastasis). Cell migration through the extracellular matrix begins with the formation of cell protrusions that contain actin and recognize the external environment, which is a common feature of invasion. WAVE1 (WASP family verprolin-homologous protein 1) belongs to the Wiskott-Aldrich syndrome family (WASP) of proteins, which have an integral role in cell motility, a crucial step in cancer metastasis. Fernando et al (page 1515) from Cardiff, United Kingdom investigated the expression pattern and the effects of manipulating endogenous WAVE1 expression in prostate cancer cells. WAVE1 protein expression in normal and cancer specimens, and in prostate cell lines was assessed. Hammerhead ribozyme transgenes were synthesized and cloned into the mammalian expression vector pEF6/V5-His TOPO TA and transfected by electroporation into prostate cancer cell lines. In vitro invasion, adhesion and growth assays were used to assess the impact of WAVE1 knockdown. Reverse transcriptase-polymerase chain reaction for WAVE1 showed strong expression in the PC-3 and DU-145 cell lines. WAVE1 knockdown was associated with a significant decrease in invasion but not in adhesion. Further investigation to assess WAVE1 as a potential target for antimetastasis therapy needs to be explored.

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Urethral Reconstruction With Keratinocyte Seeded Bladder Acellular Matrix Grafts 

Li et al (page 1538) from Shanghai, People's Republic of China investigated the feasibility of urethral reconstruction using oral keratinocyte seeded bladder acellular matrix grafts. Autologous oral keratinocytes were isolated, expanded and seeded onto bladder acellular matrix grafts to obtain a tissue engineered mucosa. In 24 male rabbits a 2 cm ventral urethral mucosal defect was created. Urethroplasty was performed with autologous oral keratinocyte seeded bladder acellular matrix grafts or with bladder acellular matrix grafts with no cell seeding. Retrograde urethrography was performed at 1, 2 and 6 months after grafting. The urethral grafts were analyzed grossly and histologically. Retrograde urethrography revealed strictures of repaired defects in the unseeded control group at various sample times. In contrast, urethral reconstruction with bladder acellular matrix grafts with oral keratinocytes showed that a wide urethral caliber was maintained with no sign of stricture. Oral keratinocytes had good biocompatibility with the bladder acellular matrix grafts. The oral keratinocytes of the grafts still showed the structure typical of stratified squamous epithelium rather than of transitional cells even 6 months after grafting, while the margin between graft and host tissue was clearly discernible. This study shows that it is unsuitable to repair longer or more complex urethral strictures with bladder acellular matrix grafts without the addition of suitable cells.