A new biochemical effect of erythropoietin

Erythropoietin stimulated lactoperoxidase (LP) or horseradishperoxidase (HRP) catalyzed iodination of tyrosine, the stimulation being more pronounced in case of LP. The diiodotyrosine (DIT) formation was stimulated more than MIT formation although the total quantity of DIT formed was less than MIT. Both sheep plasma erythropoietin and human urinary erythropoietin exhibited the above phenomenon and the stimulatory effects were directly propertional to their potencies. Preincubation of erythropoietin with neuraminidase abolished its stimulatory effect. Other glycoprotein hormones like thyrotropic hormone (TSH) and human chorionic gonadotrophin (HCG) did not stimulate the above system.     

Agar-Gel Precipitin Technique in Anthrax Antibody Determinations

A modification of the agar-gel precipitation inhibition technique of Thorne and Belton for detecting anthrax antibodies reduces inconsistency of visually determined end points on the same sera observed by different technicians. Determination of the minimal reacting concentrations of the anthrax antigen and antibody reagents, modifications of the visualization apparatus, methods for combining reagents, and length of incubation periods contribute to the ease of the end-point determinations and the uniformity of results. When compared with the previous technique, the modified procedure is less time-consuming while retaining satisfactory reproducibility, simplicity, specificity, and sensitivity.     

Agar-Gel Precipitin-Inhibition Technique for C-Reactive Protein Determinations

An application of the agargel precipitin-inhibition technique of Ray and Kadull detects the C-reactive protein present in the acute-phase human sera. The sensitivity of this procedure is compared with the capillary tube-precipitin method of Selman and Halpern.     

Agar-Gel Precipitin-Inhibition Technique for C-Reactive Protein Determinations: III. Quantitation of C-Reactive Protein in Serum Specimens

A quantitative C-reactive protein serological procedure has been developed. By use of this method, which is performed in agar-gel plates, from 2 to 654 μg of C-reactive protein per ml of titrated human serum can be detected. The method is based on the inhibition of a specific C-reactive protein antigen-antibody precipitate formed in agar-gel by the minimal reactive dilutions of each reagent in 48 hr. It is simple, sensitive, and readily reproducible.