In vitro studies of the effects of HAART drugs and excipients on activity of digestive enzymes.

Purpose: Side effects of diarrhea and steatorrhea diminish the therapeutic value of highly active antiretroviral therapy (HAART). We report in vitro studies of the effect of HAART drugs on the activity of pancrelipase, trypsin, and enterokinase and restoration of activity by subsequent addition of excess pancrelipase or colipase.

Methods: Commercial formulations of sixteen HAART drug formulations with solvent and four excipients were mixed with substrate.

Retroviral-like sequences specifically expressed in the rat ovary detect genetic differences between normal and transformed rat ovarian surface epithelial cells.

We have identified a repetitive DNA element in the rat genome that we demonstrate to be suitable to detect molecular genetic differences between normal and malignantly transformed rat ovarian surface epithelial cells by genome scanning. With fluorescence in situ hybridization, we show that these elements are widely distributed in the rat genome, and that a member of this family is present within a homogeneously staining chromosomal region of tumorigenic rat ovarian surface epithelial cells. The homogeneously staining chromosomal region infers the presence of an amplified DNA sequence in the tumor cells, and we provide molecular evidence for an amplicon in this DNA by genome scanning using a probe related to these elements.

An enzymatic cycling procedure for beta-NADP+ generated by 3'-phosphodiesterase, 2':3'-cyclic nucleotide.

An enzymatic cycling procedure for beta-NADP+ generated by the enzyme 3'-phosphodiesterase, 2':3'-cyclic nucleotide (EC 3.1.4.

A novel heterobifunctional linker for formyl to thiol coupling.

A maleimide hydrazide has been synthesized as a heterobifunctional cross-linking agent for thiol to formyl coupling. This linker has been applied to the coupling of the monoclonal antibody 17-1A, or an Fab' derived therefrom, to polyaldehyde dextran onto which the antineoplastic agent ellipticine has been attached. High binding avidities for the unshed antigen on the SW1116 colorectal tumor cell are retained in these drug-dextran-linker-antibody conjugates.

[Optimization of inlay care: pin anchorage].

The pin-technique in the application of inlays offers two important advantages: once the possibility to prepare with the utmost preservation of dental substance and highest stability and then to have more indications for inlays. Compared to the general technique in using inlays there are two major difficulties: keeping the parallelism of several pins and the danger of hurting the pulp. After a certain period of training both can be managed.

Misonidazole conjugates of the colorectal tumor associated monoclonal antibody 17-1A.

The radiation sensitizer misonidazole has been linked to the monoclonal antibody 17-1A which recognizes a nonshed antigen of a human gastrointestinal tumor. Linkage was accomplished through a hemisuccinate of misonidazole attached by a mixed anhydride coupling and gave a conjugate whose plasma half-life (for drug cleavage) was ca. 70 h.

Interactions of porphyrins and transfer RNA.

The interactions of the free base porphyrin, tetra-(4N-methylpyridyl)porphyrin and its copper(II), manganese(III) and zinc(II) complexes with brewer's yeast type V phenylalaninyl tRNA were evaluated by UV-visible spectroscopy, circular dichroism and melting temperature studies over a range of magnesium ion concentrations and ionic strengths. Scatchard analysis of absorption spectra of the porphyrins in the presence of tRNA showed the free base, copper and zinc porphyrins to have binding constants of 7.3 X 10(7), 1.

Radiosensitizer conjugation to the carcinoma 19-9 monoclonal antibody.

Misonidazole was covalently conjugated (3-68 mol drug/mol antibody) to 19-9 monoclonal antibody directed against a colorectal carcinoma tumor-associated antigen as a method for targeting radiosensitizing agents. This attachment was accomplished by the mixed anhydride method using the hemisuccinate derivative of misonidazole. Evaluation of conjugates in vitro shows a loss of antibody binding activity with increasing loading levels; however, significant binding activity is retained even at relatively high sensitizer/antibody ratios.

Macromolecular attachment as a metabolic stabilizer for a labile radiosensitizer.

4-Nitro-5-sulfonylimidazoles represent a class of hypoxic cell radiation sensitizers whose in vitro activity greatly exceeds that of the current clinical standard, misonidazole. However, in vivo studies with these 4,5-disubstituted imidazoles have shown that a rapid reaction with circulating thiols decomposes the agent and compromises its clinical utility. Drug-macromolecule conjugates prepared in this study from poly-L-glutamate, succinylated poly-L-lysine, dextran, and a succinylated polylysine-antibody, all demonstrated protection of the drug from glutathione displacement.

Further studies on the catalytic mechanism of human liver alpha-L-fucosidase.

Radiolabeling of human liver alpha-L-fucosidase (alpha-L-fucoside fucohydrolase, EC 3.2.1.

A spectrophotometric assay for nanogram quantities of biotin and avidin.

Parameters and conditions of an enzyme based assay for biotin and avidin are presented. Biotinylated glucose-6-phosphate dehydrogenase when complexed with avidin becomes inactivated. Thus it was possible to construct a competitive assay system for biotin.

Active-site-directed inactivation of human liver alpha-L-fucosidase by conduritol C trans-epoxide.

Conduritol C trans-epoxide was found to inactivate human liver alpha-L-fucosidase (alpha-L-fucoside fucohydrolase, EC 3.2.1.

Improved biotinylation of glucose-6-phosphate dehydrogenase using active-site-blocking agents.

Characteristics of the biotinylation of glucose-6-phosphate dehydrogenase are presented. The enzyme is inactivated in the presence of N-hydroxysuccinimido biotin but can be protected by an appropriate concentration of NADPH used as an active-site blocker. A Ki of 1.

Studies on the catalytic residues at the active site of human liver alpha-L-fucosidase.

Kinetic studies and chemical modifications were performed on purified human liver alpha-L-fucosidase (alpha-L-fucoside fucohydrolase, EC 3.2.1.

Protein quantitation of as low as 10-ng/ml concentrations by competitive binding to polystyrene latexes.

A protein quantitation method which offers protein detection as low as 10 ng protein/ml and accurate quantitation as low as 30-100 ng protein/ml, depending on the protein, has been designed. The assay, which is relatively quick and simple to perform, utilizes the strong, nonspecific adsorption of proteins onto polystyrene latexes. A competition is created between a marker enzyme and the analyte protein for a limited amount of latex surface area.

Comparative inactivation and inhibition of the anomerase and isomerase activities of phosphoglucose isomerase.

Several metabolic compounds have been found to be competitive inhibitors of the anomerase activity of phosphoglucose isomerase (EC 5.3.1.