Separation of antibodies into fractions with different binding properties

Fractionation of rabbit anti-horse cytochrome c--I. Specificity of the isolated fractions

High-field MR with both spin-echo and gradient-echo sequences was performed in 21 patients with (idiopathic, drug-responsive) Parkinson disease. The use of gradient echoes allowed more sensitive detection than did spin echoes of susceptibility changes in the putamina and substantia nigra. No statistically significant difference in putaminal hypointensity on long TR/long TE spin-echo sequences or on T2*-weighted images using gradient-echo sequences was observed between Parkinson patients and controls. There was also no statistically significant difference in the frequency of restoration of the signal intensity of the substantia nigra between the two groups of patients. The width of the pars compacta of the substantia nigra in patients with Parkinson disease was 2.12 + 0.82 mm (mean ± SO). This value in age- and gender-matched controls was 2.67 ± 0.5. Comparing these two groups with an unpaired t test resulted in a p value less than or equal to .005.

Our MR study with spin-echo and gradient-echo images in Parkinson and control patients was able to substantiate and elaborate on previously described MR features of Parkinson disease.

Immune reactions in polysaccharide media. Experiments with specific antibodies of different affinities for serum albumin

Rabbit antibody fractions of different affinities for human serum albumin were prepared by an immunosorbent technique. The fractions were used in studies on the enhancement of the precipitin reaction by polymers. Dextran increased the immune precipitation to about the same extent regardless of whether antibodies with high and low affinities were used. The effect should considerably facilitate the detection of antibodies with low precipitating ability in immunological assays. The results are discussed in terms of a steric-exclusion mechanism.