Effects of antigen removal on a porcine osteochondral xenograft for articular cartilage repair.

Given the limited availability of fresh osteochondral allografts and uncertainty regarding performance of decellularized allografts, this study was undertaken as part of an effort to develop an osteochondral xenograft for articular cartilage repair. The purpose was to evaluate a simple antigen removal procedure based mainly on treatment with SDS and nucleases. Histology demonstrated a preservation of collagenous structure and removal of most nuclei.

Sealing and healing of clear corneal incisions with an improved dextran aldehyde-PEG amine tissue adhesive.

Purpose: To create a non-cytotoxic, spontaneously curing tissue adhesive that is strongly bonding and persistent enough that 1-2 μL is capable of sealing a clear corneal incision throughout the first five days of healing.

Methods: A novel prototype delivery device capable of delivering 1-2 μL of a two-component adhesive delivered aqueous solutions of dextran aldehyde and star PEG amine, which mixed by diffusion and crosslinked to form an adhesive hydrogel. Adhesive hydrogels were tested for rates of degradation in phosphate-buffered saline, leak pressures when used to seal clear corneal incisions in enucleated rabbit eyes, and in vitro cytotoxicity when placed in contact with NIH3T3 fibroblast cells.

Characterization of star adhesive sealants based on PEG/dextran hydrogels.

Swellable PEG amine/dextran aldehyde composite materials are emerging as a controlled, biocompatible tissue adhesive. We explain how preservation of natural tissue amines provides biocompatibility for PEG/dextran that exceeds the stringent, destructive cyanide-based chemistry of cyanoacrylates, and adhere far better than fibrin glue. Strategic variations of material composition allow for the improvement of biocompatibility and adhesion strength.

Polysaccharide-based tissue adhesives for sealing corneal incisions.

Purpose: To investigate the ability of a novel polysaccharide-based tissue adhesive to seal corneal incisions, and to determine the effect of the tissue adhesive on corneal endothelial cells.

Methods: A polysaccharide-based tissue adhesive composed of dextran aldehyde and star PEG amines was applied to a 5-mm corneal incision on an enucleated rabbit eye, and the leak pressure of the eye was measured. The tissue adhesive was additionally incubated in direct contact with bovine corneal endothelial cells to evaluate cytotoxicity.

Interactions of polysaccharide-based tissue adhesives with clinically relevant fibroblast and macrophage cell lines.

The effects of polysaccharide-based tissue adhesives on cell survival and inflammatory cell activation were determined using in vitro mouse cell cultures. Cytotoxicity of tissue adhesives was evaluated by placing adhesives in direct contact with 3T3 fibroblast cells. Polysaccharide-based tissue adhesives composed of dextran aldehyde and star PEG amine were non-cytotoxic to fibroblasts; in contrast, a commercial adhesive composed of 2-octyl cyanoacrylate was highly cytotoxic to fibroblasts.

Mechanism of Hydrolysis of Isopropenyl Glucopyranosides. Spectroscopic Evidence Concerning the Greater Reactivity of the alpha Anomer.

The mechanism of hydrolysis of isopropenyl alpha- and beta-glucopyranosides (1 and 2, respectively) has been studied by temperature-dependent reaction kinetics, stereochemical analysis of products by (1)H NMR, solvent (18)O- and (2)H-labeling experiments, kinetic solvent deuterium isotope effects, and alpha-values for general acid catalysis. Compounds 1 and 2 are the first vinyl acetals to be shown to undergo hydrolysis exclusively by cleavage of the vinyl ether and not the acetal C-O bond. While both glucopyranosides undergo irreversible, rate-limiting C-protonation, 1 hydrolyzes approximately four times faster than 2 and has an enthalpy of activation that is 5.

A comparison of the alpha-helix forming propensities and hydrogen bonding properties of serine phosphate and alpha-amino-gamma-phosphonobutyric acid.

The ability of serine phosphate (SerP) or alpha-amino-gamma-phosphonobutyric acid (AbuP) and arginine to form a salt bridge between their side chains appears to be much greater when they are spaced i/i+4 than when they are spaced i/i+3. The side chain-side chain interaction between SerP/Arg and AbuP/Arg, positioned i/i+4, contribute 0.45 and 0.

Probing interactions between viral DNA and human immunodeficiency virus type 1 integrase using dinucleotides.

Retroviral integrases are essential for viral replication and represent an attractive chemotherapeutic target. In the current study, we demonstrated the activity of micromolar concentrations of dinucleotides against human immunodeficiency virus type 1 (HIV-1), HIV type 2 (HIV-2), simian immunodeficiency virus, and feline immunodeficiency virus integrases. The structure-activity relationship indicates that 5'-phosphorylation enhances potency and that phosphodiester and sugar modifications affect the inhibition of HIV-1 integrase.

Synthetic Utility of Yeast Hexokinase. Substrate Specificity, Cofactor Regeneration, and Product Isolation.

Yeast hexokinase (EC 2.7.1.

Selective inhibition of metabolic enzymes by enzymatically synthesized D-glucal-6-phosphate.

Yeast hexokinase (EC 2.7.1.

Regeneration of nicotinamide cofactors for use in organic synthesis.

The high cost of nicotinamide cofactors requires that they be regenerated in situ when used in preparative enzymatic synthesis. Numerous strategies have been tested for in situ regeneration of reduced and oxidized cofactors. Regeneration of reduced cofactors is relatively straightforward; regeneration of oxidized cofactors is more difficult.