b) administering an effective amount of a composition comprising a linear peptide having the sequence X1HSX2N to said patient in need of such treatment, wherein X1 is either proline, histidine, or is absent and X2 is an amino acid selected from the group consisting of the L-isomer of cysteine, the D-isomer of cysteine, homo-cysteine, histidine, or penicillamine.