No abstract

Permeabilized bovine adrenal chromaffin cells have been used to characterize the MgATP requirement of processes preceding exocytosis. Incubation of primary cultures with the membrane‐permeable phenylarsine oxide (PAO) at 20 microM inhibited the phosphorylation of phosphatidylinositol (PtdIns) and completely blocked secretion. This block could be reversed by addition of 2,3‐dimercaptopropanol to the permeabilized cells. Simultaneous addition of [gamma32P]ATP and 2,3‐dimercaptopropanol permitted a comparison between recovery of secretion and phosphorylation of intracellular components. Recovery of secretion closely correlated with phosphorylation of PtdIns and PtdIns4P. Subcellular fractionation of permeabilized cells after recovery of secretion revealed that the majority of newly phosphorylated PtdIns4P was localized on the chromaffin granules. In accordance with these results, PtdIns 4‐kinase activity was found in protein extracts of permeabilized cells as well as associated with purified chromaffin granules, sensitive in both cases to PAO. Additionally, PtdIns 4‐kinase activity in these two assays was inhibited by quercetin. In permeabilized cells, quercetin decreased the levels of labeled PtdIns4P and Ptdlns(4,5)P2 and inhibited secretion. Our data suggest that a chromaffin granule‐associated PtdIns 4‐kinase acts in the priming of exocytosis.

66Evidence acquisition: A systematic literature search was undertaken incorporating Medline, 67 Embase, and the Cochrane Library. Studies were critically appraised for risk of bias (QUIPS). 68For prognosis, the primary outcome was progression to muscle-invasive or metastatic 69 disease. Secondary outcomes were disease recurrence, overall and cancer-specific survival. 70For reproducibility, the primary outcome was inter-observer variability between 71 pathologists. Secondary outcome was intra-observer variability (repeatability) by the same 72 pathologist. Progression rates in G1 patients were similar to those in low grade patients; progression 77 rates in G3 patients were higher than in high grade patients. Survival data was limited.

The adhesion force and specificity in the first experimental evidence for cell–cell recognition in the animal kingdom were assigned to marine sponge cell surface proteoglycans. However, the question whether the specificity resided in a protein or carbohydrate moiety could not yet be resolved. Here, the strength and species specificity of cell–cell recognition could be assigned to a direct carbohydrate–carbohydrate interaction. Atomic force microscopy measurements revealed equally strong adhesion forces between glycan molecules (190–310 piconewtons) as between proteins in antibody–antigen interactions (244 piconewtons). Quantitative measurements of adhesion forces between glycans from identical species versus glycans from different species confirmed the species specificity of the interaction. Glycan-coated beads aggregated according to their species of origin, i.e., the same way as live sponge cells did. Live cells also demonstrated species selective binding to glycans coated on surfaces. These findings confirm for the first time the existence of relatively strong and species-specific recognition between surface glycans, a process that may have significant implications in cellular recognition.