Method of determination of specific length of histological specimens with the aid of square-net eyeglass]

The author has analytically expressed the relationship between the inaccessible for measurement total length of non-randomly oriented stretched objects and the sum of lengths of their projections on the longitudinal axis of the preparation (or another line). The sum of their projection lengths can be measured by means of a square-net ocular. The specific length of objects on a histological section is proportional to the number of their intersections with the transversal lines of the net and the value of its division and inversly proportional to the cosine of the average meaning of angles between the longitudinal axis of the preparation and the objects under study. Verification of the validity of the formula deduced was carried on in the histological section model prepared by the author. The proposed method ensures determination of the specific length of stretched histological preparations with a no more than 3% error.     

An immunochemical aid to sequence determination of proteins.

A specific radioimmunoassay for peptides has been developed using ¹²⁵I-labeled peptides and a double-antibody precipitation. Cross-reacting peptides are measured by inhibition of the binding of the labeled cyanogen bromide peptide to its antibody. The assay, which allows detection of picomole quantities, was used to monitor the purification of two overlapping tryptic peptides from a complex mixture of peptides. These were shown to contain a portion of the sequence of the radio-labeled cyanogen bromide peptide and a portion of the sequence of a cyanogen bromide peptide which follows in the polypeptide chain. The need to analyze many fractions in a digest in order to locate a desired peptide is thus avoided. The general suitability of this method for the purification of specific peptides from digestion mixtures of other large proteins is discussed.