ABSTRACT
Cellulose acetate phthalate (CAP, cellulose acetate 1,2-benzenedicarboxylate) is a common polymeric oral tablet coating. CAP is also a vaginal microbicide candidate that potently inhibits HIV-1 proliferation. This paper describes the development of a precise, stability-indicating gel permeation chromatography (GPC) assay for CAP. During accelerated stability studies monitored by separate reversed-phase high performance liquid chromatography (RP-HPLC) and GPC analyses, an apparent loss of mass balance was observed. This deficit was corrected by recalculating the response factor (RF) for each degraded sample, proportional to the fraction of phthalate remaining bound to the polymeric CAP. The correction factor enabled CAP and the degradation product phthalic acid (PA) to be quantitated by a single GPC analysis. The chromatographic approach taken here could potentially apply to any polymer containing degradable chromophores.
Subject(s)
Cellulose/analogs & derivatives , Chromatography, Gel/methods , Anti-HIV Agents/pharmacology , Cellulose/analysis , Cellulose/chemistry , Cellulose/pharmacology , Chromatography, Gel/economics , Chromatography, High Pressure Liquid/methods , Drug Stability , Female , HIV-1/drug effects , Humans , Hydrolysis , Molecular Structure , Reproducibility of Results , Solutions/chemistry , Solvents/chemistryABSTRACT
OBJECTIVES: To identify a 50.8-kDa biomarker to perform a preliminary clinical evaluation of its utility as an aid in the early detection of prostate cancer. METHODS: The 50.8-kDa protein, previously called NMP48, was partially purified from the serum of an individual with prostate cancer and identified by peptide mass fingerprinting of tryptic peptides from an in-gel digest. Serum samples were obtained from men with biopsy-confirmed prostate cancer, high-grade prostatic intraepithelial neoplasia, and benign histologic features, from men with clinically defined benign prostatic hyperplasia, and from controls without prostatic disease. These samples were analyzed for the presence of the biomarker by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. RESULTS: The 50.8-kDa protein was identified by peptide mass fingerprinting as being related to vitamin D-binding protein. It was found in 96% of the sera from individuals with prostate cancer (n = 52) including 11 of 12 specimens that exhibited prostate-specific antigen values of less than 4 ng/mL. The 50.8-kDa protein was found in 10 of 19 samples from men with prostatic intraepithelial neoplasia; however, it was not detected in the sera of 5 (75%) of 20 individuals with benign prostatic histologic features, 7 (70%) of 10 with clinical benign prostatic hyperplasia, 8 (80%) of 10 patients who had previously undergone radical prostatectomy, or 48 (96%) of 50 specimens from healthy controls. CONCLUSIONS: Although the study cohort was relatively small, the data suggest that an assay for the 50.8-kDa protein may be useful for the early detection of prostate cancer. Additional elucidation of its structure may yield insight into the development of this disease.
