Experiments are described which show that the rabbit papilloma virus elicits an antibody of one type only, this being capable both of neutralizing the virus and of fixing complement in mixture with it. The virus and its antibody have a powerful, specific affinity for one another, each being capable of absorbing the other in great excess when they are brought together in the test tube. The union...

A population of RNA molecules that catalyze the template-directed ligation of RNA substrates was made to evolve in a continuous manner in the test tube. A simple serial transfer procedure was used to achieve approximately 300 successive rounds of catalysis and selective amplification in 52 hours. During this time, the population size was maintained against an overall dilution of 3 x 10(298). Bo...

A rapid method of evaluating the susceptibility of spirochaetes to antibiotics would be convenient for investigators. Schneierson (1954) described a method of testing the susceptibility of strains of potentially pathogenic species, in which discs containing standard amounts of antibiotics were dropped into broth, and the broth was inoculated with the organism under study. He found that the resu...

Minimum inhibitory and bactericidal concentrations of four antibiotics and their combinations were determined for 38 strains of enterococci by a microtitration tube dilution technique. The drugs were ampicillin, vancomycin, gentamicin, and streptomycin; the combinations were ampicillin-gentamicin, ampicillin-streptomycin, vancomycin-gentamicin, and vancomycin-streptomycin. At achievable serum c...

We studied adenosine triphosphate (ATP) synthesized by bacteria in tube dilution cultures to devise a rapid antibacterial susceptibility test. The ATP level was determined with a firefly (Photinus pyralis) luciferin/luciferase bioluminescence assay, which allows a direct quantifying of bacteria above 10,000 CFU/ml. At sub-MIC, total bacterial ATP levels were paralleled by increased viable bacte...

The activity of a new semisynthetic penicillin, carbenicillin, was determined against 241 strains of gram-negative bacilli with the tube-dilution technique. Of 143 strains of Pseudomonas sp., 99 had a minimal inhibitory concentration of 200 to 300 mug/ml. The majority of strains of Escherichia coli and Proteus spp. were sensitive to this antibiotic, with minimal inhibitory concentrations of 25 ...

Objective: To investigate the antifungal activity of crude extract of leaves of Tamarix dioica tree. Material and Methods: Antifungal activity of crude extract of T. dioica leaves was studied. The extract was dissolved in Dimethyl Sulfoxide, then six strains of fungi were subjected to crude extract separately by agar tube dilution method. Inhibitory effect of extract in millimeters was determin...

Venous blood, taken with EDTA-NaCl solution according to Schulz et al (1971, Z. Klin. Chem. Klin. Biochem. 9, 329-333) is used. The blood is centrifuged at IQOg for 10 min and 10 μΐ of the supernatant is added to 3000 μΐ of a suspending medium (dilution 1:80); 300 μΐ platelet suspension are read in a nephelometer cuvet or tube against blank. The number of platelets per liter blood are determine...

The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300-2100 K, pressure range of 0.1-1.0 MPa, equivalence ratio range of 0.5-2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal o...

A competitive binding assay for serum thyroxine has been automated, with the use of small, reusable Sephadex columns to separate thyroxine from endogenous thyroid-binding globulin and later to separate the bound and free thyroxine. Sixty samples an hour are run through columns, which are held in an aluminum turntable rotated by a fraction collector motor. Reagents and samples are fed to the col...