Tuning Toehold Length and Temperature to Achieve Rapid, Colorimetric Detection of DNA from the Disassembly of DNA-Gold Nanoparticle Aggregates.

Gold nanoparticles have been widely utilized to achieve colorimetric detection for various diagnostic applications. One of the most frequently used methods for DNA detection involves the aggregation of DNA-modified gold nanoparticles driven by target DNA hybridization. This process, however, is intrinsically slow, limiting its use in rapid diagnostics. Here we take advantage of the reverse process: the disassembly of preformed aggregates triggered by the addition of target DNA via a strand displacement mechanism. A systematic study of the dependence of the disassembly rate on temperature, with and without toeholds, has delivered a system that produces an extremely rapid colorimetric response. Furthermore, using an optimal toehold length of 5 nucleotides, target triggered disassembly is rapid over a wide range of ambient temperatures. Using this overhang system, simple visualization of low picomole amounts of target DNA is possible within 10 min at room temperature.

Rat animal model for preclinical testing of microparticle urethral bulking agents.

OBJECTIVES: To develop an economic, practical and readily available animal model for preclinical testing of urethral bulking therapies, as well as to establish feasible experimental methods that allow for complete analysis of hard microparticle bulking agents. METHODS: Alumina ceramic beads suspended in hyaluronic acid were injected into the proximal urethra of 15 female rats under an operating microscope. We assessed overall lower urinary tract function, bulking material intraurethral integrity and local host tissue response over time. Microphotographs were taken during injection and again 6 months postoperatively, before urethral harvest. Urinary flow rate and voiding frequency were assessed before and after injection. At 6 months, the urethra was removed and embedded in resin. Hard tissue sections were cut using a sawing microtome, and processed for histological analysis using scanning electron microscopy, light microscopy and immunohistochemistry. RESULTS: Microphotographs of the urethra showed complete volume retention of the bulking agent at 6 months. There was no significant difference between average urinary frequency and mean urinary flow rate at 1 and 3 months postinjection as compared with baseline. Scanning electron microscopy proved suitable for evaluation of microparticle size and integrity, as well as local tissue remodeling. Light microscopy and immunohistochemistry allowed for evaluation of an inflammatory host tissue reaction to the bulking agent. CONCLUSIONS: The microsurgical injection technique, in vivo physiology and novel hard tissue processing for histology, described in the present study, will allow for future comprehensive preclinical testing of urethral bulking therapy agents containing microparticles made of a hard material.

Urethral Mucinous Adenocarcinoma of the Prostate: An Uncommon and Diagnostically Complex Disease.

A 66-year-old male presented with hematuria and mucosuria. A transurethral resection of the prostate revealed adenocarcinoma in situ with mucinous features. He underwent a robotic-assisted radical prostatectomy with lymph node dissection. Pathology confirmed T2 primary mucin-producing urothelial type adenocarcinoma in the prostatic urethra. Urothelial adenocarcinoma arising in the prostatic urethra is an uncommon disease that warrants clear differentiation from other malignancies due to its aggressive nature. The differential includes urologic and gastrointestinal malignancies making diagnosis complex. Accurate diagnosis is critical to providing appropriate treatment as these patients are at high risk of developing recurrence and metastatic disease.

Invasive High-grade Upper Tract Urothelial Carcinoma in a 14-Year-Old Girl.

We present an unusual pediatric case of invasive upper tract urothelial carcinoma with an associated genetic predisposition. A 14-year-old female presented with intermittent right flank pain, and was found to have a poorly functioning hydronephrotic right kidney. Laparoscopic nephrectomy was performed. Pathology demonstrated upper tract urothelial carcinoma, and she subsequently underwent completion ureterectomy. Genetic studies demonstrated a double-hit constitutional deletion of a DNA mismatch repair protein, revealing a rare Lynch syndrome variant known as Constitutional Mismatch Repair Deficiency Syndrome. This disease places her at high risk for multiple malignancies, including upper tract urothelial carcinoma.