Off-target activity of TNF-α inhibitors characterized by protein biochips

Tumor necrosis factor-alpha inhibitors are widely and successfully used to treat rheumatic diseases. However, significant side effects have been reported. To detect the potential off-target activities of such inhibitors we characterized two therapeutic antibodies (adalimumab, infliximab) and one receptor fusion protein (etanercept) on protein biochips (UNIchip AV-400) containing a printed serial dilution of tumor necrosis factor-alpha and about 384 different human proteins. Etanercept binds to ten proteins (affinity: 20-33% of tumor necrosis factor-alpha recognition), and six of these proteins are related to ribosomal proteins. Interestingly, adalimumab binds to the same six proteins related to ribosomal proteins (affinity: 12-18%) as well as to four proteins crucially involved in ribosomal protein synthesis. Alignment of protein sequences indicates no significant sequence homology between these ten proteins bound by the biological drugs with the highest off-target activities. Taken together, our in vitro results demonstrate that a significant number of proteins are recognized by tumor necrosis factor-alpha inhibitors and are related to ribosome biogenesis.     

Effect of expanded graphite lattice in exfoliated graphite nanofibers on hydrogen storage

A graphite exfoliation technique, using intercalation of a concentrated sulfuric/nitric acid mixture followed by a thermal shock, has successfully exfoliated a herringbone graphite nanofiber (GNF). The exfoliated GNF retains the overall nanosized dimensions of the original GNF, with the exfoliation temperature determining the degree of induced defects, lattice expansion, and resulting microstructure. High-resolution transmission electron microscopy indicated that the fibers treated at an intermediate temperature of 700 degrees C for 2 min had dislocations in the graphitic structure and a 4% increase in graphitic lattice spacing to 3.5 A. The fibers treated at 1000 degrees C for 36 h were expanded along the fiber axis, with regular intervals of graphitic and amorphous regions ranging from 0.5 to >50 nm in width. The surface area of the starting material was increased from 47 m(2)/g to 67 m(2)/g for the 700- degrees C treatment and to 555 m(2)/g for the 1000- degrees C treatment. Hydrogen uptake measurements at 20 bar indicate that the overall hydrogen uptake and operative adsorption temperature are sensitive to the structural variations and graphitic spacing. The increased surface area after the 1000- degrees C treatment led to a 1.2% hydrogen uptake at 77 K and 20 bar, a 3-fold increase in hydrogen physisorption of the starting material. The uptake of the 700- degrees C-treated material had a 0.29% uptake at 300 K and 20 bar; although low, this was a 14-fold uptake over the starting material and higher than other commonly used pretreatment methods that were tested in parallel. These results suggest that selective exfoliation of a nanofiber is a means by which to control the relative binding energy of the hydrogen interaction with the carbon structure and thus vary the operative adsorption temperature.     

Hydrogen storage in graphite nanofibers: effect of synthesis catalyst and pretreatment conditions

A series of graphite nanofibers (GNFs) that were subjected to various pretreatments were used to determine how modifications in the carbon structure formed during either synthesis or pretreatment steps results in active or inactive materials for hydrogen storage. The nanofibers possessing a herringbone structure and a high degree of defects were found to exhibit the best performance for hydrogen storage. These materials were exposed to several pretreatment procedures, including oxidative, reductive, and inert environments. Significant hydrogen storage levels were found for several in situ pretreatments. Examination of the nanofibers by high-resolution transmission electron microscopy (TEM) after pretreatment and subsequent hydrogen storage revealed the existence of edge attack and an enhancement in the generation of structural defects. These findings suggest that pretreatment in certain environments results in the creation of catalytic sites that are favorable toward hydrogen storage. The best pretreatment resulted in a 3.8% hydrogen release after exposure at 69 bar and room temperature.