INVIVO MONITORING OF SERUM-PROTEIN CROSS-LINKING IN PATIENTS WITH DIABETES-MELLITUS - EVIDENCE FOR PHARMACOLOGICAL MODIFICATION OF IMMUNOGLOBULIN-G CROSS-LINKS

It is well known that increased cross linking of proteins due to nonen zymatic glycosylation occurs in diabetic animals and humans leading to accumulation of proteins (e.g. collagen). This in turn is strongly as sociated with diabetic long term complications. We developed a noninva sive method for studying in vivo cross linking and its pharmacological inhibition by L-arginine in a blind placebo controlled study with cro ssing over of two treatment periods of three months each. Glycemic con trol was assessed by determining blood glucose, HbA1c, fructosamine, a nd total glycosylated hemoglobin. The patients were randomly assigned to two treatment groups A (n = 14) and B (n = 16). 20 healthy voluntee rs served as controls. Treatment consisted of two daily dosages of 1 g L-arginine free base. Cross linking of a human serum protein (IgG) wa s assessed by SDS polyacrylamide gel electrophoresis and subsequent We stern blotting. Diabetic patients showed a statistically increased num ber of cross links compared to normal controls (Group A: 3.6 vs 2.0 ba nds, group B: 3.8 vs 2.0 bands). L-arginine led to a significant reduc tion of cross links in both treatment groups (Group A: 3.6 to 2.1 band s, group B: 3.8 to 2.5 bands). The described noninvasive method for as sessing in vivo cross linking requires only mul amounts of serum and c ould serve to monitor protein cross linking in patients with diabetes mellitus.