Antistreptolysin O (ASO) titers were determined on 117 human sera with rabbit, human, and sheep red blood cells (RBC) as the indicator system in the ASO tube test. The titers of 65% of the sera were one dilution step higher when a 5% suspension of sheep RBC was used instead of a 5% suspension of rabbit RBC. Titers were one dilution step higher in 42.7% of the sera when a 5% suspension of human ...

(4) In the remaining tubes of each row is placed 0.5 ml. of 0.85% sodium chloride. (5) To the first tube of each row 0.1 ml. of serum is added and mixed thoroughly. (6) Then 0.5 ml. of the diluted serum is carried over into tube 2 and so on until tube 10, the last 0.5 ml. being discarded. (7) To each tube 0.5 ml. of washed fresh sheep cells is added, thus giving a final serum dilution of 1:20 u...

The effectiveness of imploding waves at detonation initiation of stoichiometric ethyleneand propane–oxygen– nitrogen mixtures in a tube was investigated. Implosions were driven by twice-shocked gas located at the end of a shock tube, and wave strength was varied to determine the critical conditions necessary for initiation as a function of diluent concentration for each fuel. Hydrocarbon–air mi...

The results of the attempts here described to cultivate the incitant of mosaic disease of tobacco and tomato plants give good reason to suppose that this has been accomplished. The agent in the tissues of affected plants induces the disease not infrequently in a dilution of 1:10,000 but only very rarely at a higher dilution. During its transference from tube to tube of the special medium used i...

An automated hemagglutination-inhibition (HI) test for the "shipping fever" strain (SF-4) of parainfluenza 3 antibody in bovine sera was developed and compared to manual tube and microtiter test procedures. The automated system operating at 60 samples per hr provided the most test results per specified time period, and the manual tube test provided the least. The manual microtiter test and the ...

Representative dilution tube sampling techniques for particulate and gas phase vehicle emissions are described using Teflon filter media and XAD-2 resin. More than 90% of the total gas (C8-C18) and particulate direct acting Ames assay mutagenicity (TA 98) was found in the particulate phase. The gas and particulate phase material was fractionated by HPLC into nonpolar, moderately polar and highl...

Minimum inhibitory concentrations, minimum bactericidal concentrations, and killing curve assays were measured after Legionella pneumophila was grown in human lung fibroblasts. Results of susceptibility testing of organisms grown intracellularly are compared with results for organisms grown by standard tube dilution methods.

A simple method for the measurement of 5-fluorocytosine in the presence of amphotericin B is described. The antifungal activity of amphotericin B is abolished by heating serum at 100 C for 45 min. 5-Fluorocytosine is unaffected by this treatment, and serum levels can be subsequently assayed by either tube dilution or disk diffusion methods.

A relatively simple procedure for measuring H2SO4 in auto exhaust will be presented. The system is compatible with the Federal constant volume sampler (CVS unit). The time required to get sufficient sample for titration is 15-30 min. Values on sulfates in exhaust with a catalyst car and a noncatalyst car agree well with literature data obtained by dilution tube and filtration techniques.

A rapid, simple, and inexpensive method for quantitation of viable mycoplasmas is described. Serial dilutions were made in sterile microtiter plates with standard microtiter equipment. The results were multiplied by a factor of 2.38 to obtain colony-forming units comparable to those obtained with the laborious glass pipette-tube dilution method.