Novel compounds of formulae to, which more particularly include sulfonylurea derivatives, sulfonylthiourea derivatives, sulfonylguanidine derivatives, sulfonylcyanoguanidine derivatives, thioacylsulfonamide derivatives, and acylsulfonamide derivatives which are effective platelet ADP receptor inhibitors. A client data record is received from a client and a determination is made of a server data record corresponding to the client data record and a stored digest generated from a previously received version of the received client data record. Additionally, the file system may employ a hierarchical namespace to store files. This makes it possible to accomplish load distribution for the processing servers. These plasmids and their host cells can be used for biomedical applications.