Biomedical subjects

K Ernst-Cabrera

Publications and source records attributed to K Ernst-Cabrera.

3 recordsLinked to original sources

PubMed1989

Effects of covalently bound silica-nitroimidazole drug particles on Entamoeba histolytica.

Most commonly used antiamoebic drugs are effective in invasive amebiasis, but their response against trophozoites of Entamoeba histolytica, present in the lumen of the human colon, is inadequate. We report the development of an antiamoebic drug carrier that may be effective against luminal infections. Our preparation consists of small silica particles (5-10 microns in diameter) covalently linked to a potent antiamoebic drug, 2-(4-aminophenoxymethyl)-5-nitro-1-methyl imidazole. Silica-drug particles were injected into mice, hamsters, and guinea pigs. We found that trophozoites phagocytosed the particles in vivo and in vitro, followed by rapid cell death due to the released drug. Analysis of mouse serum revealed that no drug was absorbed from the intestine after placement of the drug-containing particles in the intestine. The antiamoebic activity of particles recovered from the intestine was almost fully retained. This novel antiamoebic concept may be useful for luminal therapy for asymptomatic amebiasis and may minimize side effects and frequency of administration.

Amebicides↗

PubMed1987

Coupling of ligands to primary hydroxyl-containing silica for high-performance affinity chromatography. Optimization of conditions.

Silicas of different particle and pore sizes were derivatized with three different silanes. The functionalized silica contained either epoxide, methacrylate or amino groups. These groups were further modified to yield primary hydroxyl functions. Activation of the resultant primary hydroxyl groups for the purpose of chemically coupling proteins was studied with a variety of reagents and optimized for p-nitro-phenyl chloroformate. The effect of pH on the efficiency of coupling proteins (BSA and trypsin) to p-nitrophenyl carbonate-silica was studied in detail. Slightly acidic conditions (pH 6) gave the highest yields. In a dynamic recycling process, bovine pancreatic trypsin inhibitor was immobilized to activated primary hydroxyl-silica packed into a stainless-steel column. The high-performance affinity chromatography purification of trypsin on this column is demonstrated.

Animals↗

PubMed1986

Silica containing primary hydroxyl groups for high-performance affinity chromatography.

Primary hydroxyl groups were incorporated into silica by a four-step reaction procedure which includes modification of the silica surface with gamma-glycidoxypropyltrimethoxysilane, leading to an epoxide silica; hydrolysis with acid to yield a diol silica; oxidation of the diol silica with periodate to yield a silica resin with aldehyde functions; and reduction with sodium borohydride to obtain the primary hydroxyl-containing silica. The hydroxyl groups were activated with chloroformates or carbodiimidazole. Proteins were coupled under mild conditions in high yield to these activated silica resins. Columns containing these newly developed silica derivatives were used for the fast and efficient purification of antibodies on antigen-containing silica, as well as for the purification of trypsin on a trypsin inhibitor column (or vice-versa). The effect of pressure on association and dissociation of the affinity complex is discussed.

Antibodies↗