PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 6792056-2 1981 When the surface charge of HRC was reduced by treating them with neuraminidase (to remove some negative sialic acid residues) or coating them with polylysine (a positively charged polymer), no substantial binding to macrophages was obtained. N-Acetylneuraminic Acid 104-115 histidine rich calcium binding protein Homo sapiens 27-30