PubMed · 13632703
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
L H KENT, J H SLADE. 1959-01-31. Immunochemically active cross-linked polystyrene.. https://doi.org/10.1038/183325a0
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
We discuss the pulling force f required to extrude a lipid tube from a living cell as a function of the extrusion velocity L. The main feature is membrane friction on the cytoskeleton. As recently observed for neutrophils, the tether force exhibits a "shear thinning" response over a large range of pulling velocities, which was previously interpreted by assuming viscoelastic flows of the sliding membrane. Here, we propose an alternative explanation based on purely Newtonian flow: The diameter of the tether decreases concomitantly with the increase of the membrane tension in the lipid tube. The pulling force is found to vary as L(1/3), which is consistent with reported experimental data for various types of cells.
Reversible and irreversible states of pressure-dissociated casein micelles were studied by in situ light scattering techniques and ex situ atomic force microscopy. AFM experiments performed at ambient pressure reveal heterogeneities across the micelle, suggesting a sub-structure on a 20 nm scale. At pressures between 50 and 250 MPa, the native micelles disintegrate into small fragments on the scale of the observed sub-structure. At pressures above 300 MPa the micelles fully decompose into their monomeric constituents. After pressure release two discrete populations of casein aggregates are observed, depending on the applied initial pressure: Between 160 and 240 MPa stable micelles with diameters near 100 nm without detectable sub-structures are formed. Casein micelles exposed to pressures above 280 MPa re-associate at ambient pressure yielding mini-micelles with diameters near 25 nm. The implications concerning structural models are discussed.
Phosphonoformate oligodeoxyribonucleotides were prepared via a solid phase synthesis strategy. The first step in the preparation of appropriate synthons was condensation of bis(N,N-diisopropylamino)phosphine and diphenylmethylsilylethyl chloroformate in the presence of sodium metal to yield formic acid, [bis(N,N-diisopropylamino)phosphino]-beta-(diphenylmethylsilylethyl) ester. The product of this reaction was then condensed with appropriately protected 2'-deoxynucleosides using 4,5-dicyanoimidazole to yield the 3'-O-phosphinoamidite reactive monomers. The exocyclic amines of cytosine, adenine, and guanine were protected with 9-fluorenylmethyloxycarbonyl, and oligodeoxyribonucleotides were synthesized on controlled pore glass using the hydroquinone-O,O'-diacetic acid linker. Synthons were sequentially added to this support using tetrazole as an activator, oxidized to phosphonoformate, and the transient 5'-protecting group was removed with acid. Following total synthesis of an oligomer, protecting groups were removed with TEMED.HF and products purified by HPLC. These analogues were resistant to nucleases, formed duplexes with complementary RNA (A-form), and, as chimeric oligomers containing phosphate at selected sites, stimulated RNase H1 activity.