Complexation of tauro- and glyco-conjugated bile salts with three neutral beta-CDs studied by ACE

Complexation of the bile salts (BS) taurocholate, tauro-beta-muricholate, taurodeoxycholate, taurochenodeoxycholate, glycocholate, glycodeoxycholate, and glycochenodeoxycholate common in rat, dog, and man with natural beta-CD and the chemically modified beta-CDs 2-hydroxypropyl-beta-CD and 2-O-methyl-beta-CD was studied using mobility shift ACE. The CDs were selected due to their frequent use in preformulation and drug formulation as oral excipients for the solubilization of drug substances with low aqueous solubility. ACE was demonstrated to be a feasible and efficient technique for investigation of the interactions between BS and beta-CDs. All the investigated BS possessed affinity for the three CDs with stability constants ranging from 2x10(3) to 4x10(5) M(-) (1). The requirements and assumptions related to the use of ACE for estimating high affinity stability constants were discussed. The extent and pattern of hydroxylation significantly influenced the affinity of the glyco- and tauro-conjugated BS toward the beta-CDs (chenodeoxycholates > deoxycholates > cholates) whereas the nature of the beta-CD derivatization and BS conjugation played a minor role only. The results indicate that displacement of drug substances from beta-CD inclusion complexes is likely to occur in the small intestine where BS are present potentially influencing drug bioavailability.     

Drug-liposome distribution phenomena studied by capillary electrophoresis-frontal analysis

The potential of using CE frontal analysis (CE-FA) for the study of low-molecular-weight drug-liposome interactions was assessed. The interaction of bupivacaine, brompheniramine, chlorpromazine, imipramine, and ropivacaine with net negatively charged 80/20 mol% 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine/egg yolk phosphatidic acid liposome suspensions in HEPES buffer at pH 7.4 was investigated. The fraction of free drug as a function of lipid concentration was measured and apparent liposome - buffer distribution coefficients were determined for the basic drug substances. The distribution coefficients increased in the order ropivacaine, bupivacaine, brompheniramine, imipramine, and chlorpromazine. The developed CE method was relatively fast allowing estimates of drug-liposome affinity to be obtained within 15 min. CE-FA may have the potential to become a valuable tool for the characterization of drug-liposome interactions in relation to estimation of drug lipophilicity and for the evaluation of drug distribution in liposomal drug delivery systems.     

Bladder squamous cell carcinoma biomarkers derived from proteomics

Proteomics provide powerful technology for analyzing the expression levels of thousands of proteins simultaneously both in health and disease. Here, we review proteomic strategies that we have developed to identify metaplastic lesions in bladder squamous cell carcinomas as well as biomarkers in the urine for follow-up studies of squamous cell carcinoma (SCC)-bearing patients.     

A comprehensive protein resource for the study of bladder cancer: http://biobase.dk/cgi-bin/celis

In our laboratories we are exploring the possibility of using proteome expression profiles of fresh bladder tumors (transitional cell carcinomas, TCCs; squamous cell carcinomas, SCCs) and random biopsies as fingerprints to subclassify histopathological types and as a starting point to search for protein markers that may form the basis for diagnosis, prognosis, and treatment. Ultimately, the goal of these studies is to identify signaling pathways and components that are affected at various stages of bladder cancer progression and that may provide novel leads in drug discovery. Here we present our ongoing efforts to establish comprehensive two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) databases of TCCs and SCCs which are being constructed based on the proteomic and immunohistochemical analysis of hundreds of fresh tumors, random biopsies and cystectomies received shortly after operation (http://biobase.dk/cgi-bin/celis).