[Determination of the toxigenicity of Corynebacterium diphtheriae by using paper indicator disks]. / Opredelenie toksigennosti Corynebacterium diphtheriae s pomoshch'iu indikatornykh bumazhnykh diskov.

The method for the determination of the toxigenicity of C. diphtheriae by means of discs impregnated with diphtheria antitoxin is proposed. The discs can be prepared long before use and stored for a year. The determination of toxigenicity with these discs is not inferior in its sensitivity to the routine procedure of the immunoprecipitation test. The disc method decreases the consumption of unavailable diphtheria antitoxin by 10 times, that of culture media by 2-2.5 times: besides, it is less labor consuming.

Microtiter radioimmunoprecipitation assay of HSV-1 polypeptides with recovery and SDS-PAGE analysis of precipitated proteins: usefulness as screening test for large numbers of specimens including hybridoma supernates.

Immunoprecipitation of radiolabeled polypeptides from complex mixtures of proteins was performed in polystyrene microtiter plates using staphylococcus protein A and various antibody preparations. The method is (1) rapid, (2) uses multichannel micropipettor technology, (3) handles large numbers of specimens easily, (4) requires very small volumes of antigen and antibody (5-50 microliters), (5) provides replicates for statistical analysis and (6) allows recovery of precipitated proteins for direct SDS-PAGE analysis of precipitated proteins. We have shown it is useful as a test to screen large numbers of sera or to characterize monoclonal antibody-containing samples.

Automated immunoprecipitation of meconium albumin for cystic fibrosis screening in the newborn.

Cystic fibrosis is the most frequent substantially lethal inherited disease in the United States. Newborn screening for cystic fibrosis has been suggested because early diagnosis permits genetic counselling of parents and improved treatment and prognosis for cystic fibrosis patients. The fact that cystic fibrosis newborns have abnormally high meconium albumin seems to offer the best screening approach. Because we have had equivocal and false positive results with meconium albumin test strips, we have developed a nephelometric automated immunoprecipitation method for the quantitative and specific analysis of meconium albumin. On a total of 3895 meconiums so far examined, eleven albumin elevations of undetermined origin have been detected. Nine of these were associated with prematurity. There have been, so far, no detected true positives and no known false negatives. The normal range for meconium albumin is in agreement with previously published ranges determined using manual immunochemical methods. This method is rapid and economic. The question of sensitivity, specificity and predictive value of this and other detection methods is discussed.

Semi-micro quantitative gel precipitin reaction.

Quantitative gel precipitin reactions were made on a semi-micro-scale. This required overall reduction of the dimensions of the necessary apparatus. Resulting from this was the ability to use agarose gel at low concentration not possible with the conventional macro quantitative gel precipitin technique. Further advantages were the reduction of time for the completion of the experiments and also that of the volume of the reactants. Diffusion coefficients of antigens determined by the semi-micro technique agreed with those obtained with the more accurate optical methods.