Protein-polymer grafts. II

Arginine hydrochloride reacts with equimolar 4-hydroxybenzil smoothly, in 70% ethanolic potassium hydroxide (0.5 m), at room temperature to produceN ⁵-[5-(p-hydroxphenyl)-4-oxo-5-phenyl-2-imidazolin-2-yl]-L-ornithine, in 70% yield. Purification was affected by paper chromatography. The pure product crystallizes with 1.5 moles of water. It resists boiling in concentrated hydrochloric acid and potassium hydroxide.     

Protein-polymer grafts. III

Arginines found on protein backbone can be modified easily, using 10 molar excess of 4-hydroxybenzil in 70% ethanolic alkali solution (0.25M), at room temperature. 96% of the arginines are modified this way, as measured by Sakaguchi reaction. The phenolic hydroxide was available for an enzyme, tyrosinase, to be oxidized.Second paper of this series, this journal pp. 63–68.     

Brain grafts and Parkinson's disease

In animal models, grafts derived from several different tissues, principally fetal substantia nigra and adrenal medulla from young adults, have been found to be effective in alleviating some of the manifestations of lesions of the substantia nigra. It has been suggested that these grafts function by diffusely secreting dopamine, by exerting trophic effects on the host brain, or by producing a new innervation of the host corpus striatum. Evidence for each of these modes of action is briefly reviewed. Several brain tissue transplantation techniques have been described. Each of these techniques has significant limitations in animal models. The significance of these limitations for human application is described, and possibilities for improving the efficacy of brain tissue transplantation in animal models and for human application are discussed.