Jacques M. Singer

The latex fixation test: I. Application to the serologic diagnosis of rheumatoid arthritis

Abstract 1.1. A latex fixation test for the serologic diagnosis of rheumatoid arthritis is described. 2.2. The principle of the test is similar to that of current technics depending upon the agglutination of erythrocytes but the substitution of biologically inert polyvinyl toluene and polysterene latex particles of uniform size obviates difficulties attendant upon the use of erythrocytes. The test consequently is more simple to perform and to interpret. 3.3. The latex fixation test must be performed under rigidly standardized conditions in order to obtain reproducible titers.

The Presence of Anti-gamma Globulin Factors in Sera of Patients with Active Pulmonary Tuberculosis

Excerpt The use of particulate carrier agglutination methods has made possible the serological detection of serum macroglobulins which interact with human or animal gamma globulin (1). These macrog...

Kinetics of flocculation of latex particles by human gamma globulin

Abstract A rate equation is derived for the initial rate of flocculation of latex particles upon addition of various amounts of protein molecules. The main assumption involved is that the rate of flocculation depends on the fraction of the latex particle surface that is covered with protein, with a maximum rate at 50% coverage and no reaction at all (protection) at 100% coverage. The rate of flocculation is studied experimentally by measuring the change in turbidity with time after addition of various amounts of human gamma globulin (IgG). The rate equation is qualitatively, if not quantitatively, confirmed in various types of experiments in which either the initial latex concentration, the initial protein concentration, or the ratio of the two concentrations was kept constant. From these experiments a maximum surface coverage can be derived of about 2200 IgG molecules per latex particle of 234 nm diameter, a value in good agreement with previous results.

Mechanism of Particulate Carrier Reactions: V. ADSORPTION OF HUMAN GAMMA GLOBULIN TO 0·2 MICRON DIAMETER LATEX PARTICLES AND THEIR AGGLUTINATION BY RHEUMATOID FACTOR

Polystyrene latex particles of 0 81. diameter have been in use since 1956 for the detection of rheumatoid factors in the latex-fixation test of Singer and Plotz (1956). The use of this test or of its various modifications in rheumatoid diseases has been widespread, and this subject has been recently reviewed (Singer, 1961). In the original procedure for the detection of rheumatoid factors, the suspension of 0 8 ,u diameter latex particles was sensitized by the addition of an excess of human gamma globulin (whole Fraction II). Under the conditions of the test procedure, about 90 per cent. of the added gamma globulin was not adsorbed and consequently remained in solution (Singer, Altmann, Goldenberg, and Plotz, 1960). This excess gamma globulin in the test system often resulted in variable and uncontrolled inhibition effects, thus making the test difficult to standardize and not always reproducible. More recently, several modifications have been introduced (Singer, Plotz, and Eason, 1961; Singer, Oreskes, Hutterer, and Ernst, 1962) in the original latex-fixation procedure. A smaller latex particle of 0 2 ,u diameter had been substituted for the previously employed 0 8 ,t particle. In addition, the excess unadsorbed gamma globulin remaining in solution has been removed by high speed centrifugation and washing of the coated particles. The present report is concerned with the quantitative aspects of human gamma globulin (HGG) adsorption to the 0 2 pt diameter latex particle. In addition, data on quantitative agglutination of sensitized latex particles by rheumatoid factor (RF) preparations are also reported.

The mechanism of particulate carrier reactions: III. The stabilizing effect of serum proteins☆

Abstract 1.1. FII and FV alone or in mixtures are adsorbed onto the surface of latex particles or tanned sheep cells and produce agglutination with both rheumatoid factor and antialbumin systems. 2.2. Adding FV or FIV stabilizes latex particles and lowers rheumatoid factor titers by their protective colloidal action. FIV is more effective than FV in this respect. 3.3. Added FIV produces a prozone effect with the FII latex particle system but not with the FII sheep cell system. 4.4. The probable mechanism of the protective action of serum protein fractions on particulate carrier systems is discussed.

INFLUENCE OF PH, IONIC STRENGTH AND HUMAN GAMMA GLOBULIN CONCENTRATION ON STABILITY OF POLYSTYRENE LATEX PARTICLE SUSPENSIONS.

Summary Polystyrene latex particle suspensions exhibit the properties of lyophobic colloids. Addition of small amounts of human gamma globulin serves to destabilize the LP whereas larger amounts exert a stabilizing protective action. The protective action of HGG is strongly pH dependent and is least at the protein isoelectric point. Use of uncoated latex particles for detection of rheumatoid factors may be complicated by the fact that such particles spontaneously precipitate in very dilute protein solutions.

The Mechanism of Inhibition of Aminoglycoside and Polymyxin Class Antibiotics by Polyanionic Detergents

Summary Polyanionic detergents, the most widely used of which is sodium poly-anethol sulfonate (SPS), inhibit polymor-phonuclear leukocyte, complement, lyso-zyme, and antibiotic activity. SPS has been utilized for years in the culture of blood for bacterial pathogens. Utilizing an agarose gel double diffusion system it was ascertained that polyanionic detergents, as represented by SPS, sodium lauryl sulfate, and disodium 4-dodecylated oxydibenzene-sulfonate, inactivate antibiotics by combining directly with them to form a precipitate. Only the positively charged aminoglycoside and poly-myxin classes of antibiotics were affected. Neither nonionic nor cationic detergents interacted with aminoglycoside antibiotics. It would appear that a polymer is formed with both the polyanionic detergent and antibiotic each at least divalent. The reaction is independant of and does not interfere with bacterial growth.

Determination of antibody concentration using a stopped-flow turbidimetric technique.

The aggregation of albumin and anti-albumin is studied during the first seconds of the reaction by measuring the rate of change of the optical density of the mixture. When this rate is plotted against the antigen concentration of a constant serum dilution, bell-shaped curves are obtained. The maxima of these rate curves parallel the maxima of precipitation curves. Thus, the maximum rate establishes the antigen concentration for maximum precipitate. On the basis of these experiments a method for relative quantitation of antibody in sera is proposed. The absolute concentration of precipitating antibody can be obtained by means of an additional one-tube precipitation experiment.

The quantitative nature of the reaction between aminoglycoside and polymyxin class antibiotics with polyanionic detergents.

Using classical tube and gel precipitation techniques aminoglycoside and polymyxin class antibiotics were found to quantitatively react with polyanionic detergents.