technetium-tc-99m-sulfur-colloid and hydroxyethylcellulose

Understanding the distribution of microbicide and human immunodeficiency virus (HIV) within the gastrointestinal tract is critical to development of rectal HIV microbicides. A hydroxyethylcellulose-based microbicide surrogate or viscosity-matched semen surrogate, labeled with gadolinium-DTPA (diethylene triamine pentaacetic acid) and 99mTechnetium-sulfur colloid, was administered to three subjects under varying experimental conditions to evaluate effects of enema, coital simulation, and microbicide or semen simulant over 5 h duration. Quantitative assessment used single photon emission computed tomography (SPECT)/computed tomography (CT) and magnetic resonance imaging (MRI) imaging, and sigmoidoscopic sampling. Over 4 h, radiolabel migrated cephalad in all studies by a median (interquartile range) of 50% (29-102%; P<0.001), as far as the splenic flexure (approximately 60 cm) in 12% of studies. There was a correlation in concentration profile between endoscopic sampling and SPECT assessments. HIV-sized particles migrate retrograde, 60 cm in some studies, 4 h after simulated ejaculation in our model. SPECT/CT, MRI, and endoscopy can be used quantitatively to facilitate rational development of microbicides for rectal use.

Topics: Administration, Rectal; Adult; Anti-HIV Agents; Anti-Infective Agents, Local; Cellulose; Coitus; Contrast Media; Diagnostic Imaging; Ejaculation; Enema; Feasibility Studies; Gadolinium DTPA; Gels; HIV Infections; Humans; Magnetic Resonance Imaging; Pilot Projects; Radiopharmaceuticals; Rectum; Semen; Sigmoidoscopy; Technetium Tc 99m Sulfur Colloid; Time Factors; Tissue Distribution; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Unsafe Sex