The phosphate content of Escherichia coli alkaline phosphatase and its effect on stopped flow kinetic studies.
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Biomedical subjects
Publications and source records attributed to W Bloch.
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Although important in neurodegeneration, systematic studies of nicotinic acetylcholine receptor expression in normal aging human brains are difficult to perform. We have studied the expression of nicotinic receptor alpha 4-1 and alpha 5 mRNA in the frontal and parietal isocortex of 3- (young adult), 24- (late middle aged), and 33-month-old (old) rats by nonisotopic in situ hybridization. In all groups transcripts were mainly present in layer II/III and V pyramidal neurons. The numerical densities of alpha 4-1 mRNA-containing neurons with respect to those of cresyl violet-stained neurons decreased with aging in the rat frontal and parietal cortex, while those of alpha 5 mRNA-containing neurons were not affected. These findings point to an age-related decrease of the percentages of numerical densities of alpha 4-1 mRNA-containing neurons, which has to be taken into account as a possible substrate for the well-known decrease of nicotine binding sites in the aging cerebral cortex.
Ricin A chain immunotoxins disulfide cross-linked with conventional, sterically unhindered reagents have unsatisfactorily short circulating life times in vivo. (Acetylthio)succinic anhydride, a thiolating reagent with partial steric hindrance of the sulfur atom, does not remedy this situation. Sulfosuccinimidyl N-[3-(acetylthio)-3-methylbutyryl]-beta- alaninate, a new cross-linker in which the carbon alpha to the sulfur is doubly methylated, creates disulfide bonds 2 orders of magnitude more resistant to reduction than unhindered disulfides. Nevertheless, this deactivated thiolating agent rapidly and reliably cross-links ricin A chain and antibodies to create immunotoxins with in vitro cytotoxicities comparable to those of 2-iminothiolane-coupled conjugates.