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L F Affronti

Publications and source records attributed to L F Affronti.

At least 37 records · Page 2Linked to original sources
PubMed1973

Comparison of the capillary tube and explant methods for the in vitro assay of tuberculin.

Purified antigens prepared from mycobacteria were tested for nonspecific toxicity and tuberculin activity by two in vitro methods. One technique utilized measurements of macrophage migration in 4-day-old cultures of spleen from normal and tuberculin-sensitive rabbits. The other method was a modification of the capillary tube technique. To obtain enough peritoneal macrophages for good quantitation, changes were made in the method of harvesting cells, and in some instances exudates from two or more Wright strain no. 13 guinea pigs were combined. The capillary tube method was as sensitive as the explant method for detecting nonspecific toxicity. Each tuberculin assay included a group of control cultures of cells from sensitive animals, test groups containing two widely spaced concentrations of a standard tuberculin, PPD-S, and one or more concentration of the tuberculin to be tested. Macrophages from tuberculin-sensitive animals were regularly inhibited by 0.25 mug of PPD-S per ml with both in vitro methods. The potency of the test tuberculins relative to that of PPD-S was somewhat greater in capillary tube assays than in explant cultures. A purified tuberculopolysaccharide was equally inhibitory for both normal and tuberculin-sensitive cells in both culture systems.

Animals↗
PubMed1972

Characterization and comparison of mycobacterial antigens by discontinuous pore gradient gel electrophoresis.

Concentrated culture filtrates and cell extracts were prepared from selected mycobacteria and analyzed by a multistage polyacrylamide electrophoretic procedure. Various staining procedures were used to detect protein, carbohydrate, nucleic acid, and lipid constituents. Visual examination of the more prominently stained components indicated differences and similarities in each species of Mycobacteria. The majority of the individual components were of small molecular weight; however, there appeared in all culture filtrates and extracts examined a slowly moving protein component of relatively large molecular size. Evidence based on immunodiffusion suggests that it is a common mycobacterial antigen.

Animals↗
PubMed1972

Characterization and comparison of mycobacterial antigens by two-dimensional polyacrylamide gel electrophoresis.

Cell extracts and culture filtrates were prepared from several mycobacterial species and subjected to two-dimensional acrylamide gel electrophoresis. The cell preparations were first electrophoresed in a 7% homogeneous gel followed by a second electrophoresis, at right angles to the first separation, in a 2 to 30% linear gel gradient slab. Because the stained slab resembled a "fingerprint" or "peptide map," this procedure has been called "electroprotein mapping." More than 200 protein-staining spots were detected in several of the cell extracts, each map being characteristic of the species examined. The single most characteristic portion of each map was the region between the 16 and 30% gel concentrations. This region consisted of several small-molecular-weight components (many of peptide proportions) which together appeared as the most anodic band in the 7% gel column (first separation). The number and location of these components in the linear gel slab (second separation) were specific for each species tested. By electrophoresis of molecular-weight markers (i.e., albumin, myoglobin, cytochrome c) with and across (transverse electrophoresis) the gel gradient, the relative molecular weights of the unknown cell extract components could be estimated. These results suggest that two-dimensional acrylamide gel electrophoresis is a useful tool for the characterization of mycobacterial cell constituents.

Antigens, Bacterial↗
PubMed1972

Characterization and comparison of mycobacterial antigens by two-dimensional immunoelectrophoresis.

Two-dimensional immunoelectrophoresis (2D-IEP), in which a complex of antigens is subjected to electrophoresis first through an agarose matrix in one direction and secondly through an antiserum-agarose matrix at right angles to the first direction, was evaluated as a tool for analysis of mycobacterial antigens. Cell extracts from four species of mycobacteria, Mycobacterium tuberculosis (four strains), M. bovis strain BCG, M. scrofulaceum, and M. phlei, were assayed by 2D-IEP with four anti-mycobacterial antisera. Besides displaying the precipitin curves in a more easily interpreted format than did conventional immunoelectrophoresis (IEP), 2D-IEP offered greater sensitivity in terms of numbers of precipitin curves when like reactions were compared with IEP patterns. As many as 60 immunoprecipitates were observed on 2D-IEP slides compared to 18 on comparable IEP plates. Technical reproducibility of patterns from run to run was excellent. Other parameters, such as the influence of using different batches of antigen on the pattern, are discussed. Each of the cell extract antigens gave a unique pattern of precipitin peaks which could be easily differentiated from the patterns given by the other mycobacterial cell extracts when reacted with any of the antisera in 2D-IEP. Since both the species and strains of mycobacteria could be easily and reproducibly differentiated solely on the basis of two-dimensional immunoelectrophoretic patterns obtained with any of the antisera employed in this study, it may be possible, by using IEP, to differentiate and identify all species and strains of mycobacteria with one standard, highly sensitive antiserum, rather than a battery of antisera.

Animals↗
PubMed1969

Mycobacterial polysaccharides. II. Comparison of polysaccharides from strains of four species of mycobacteria.

Evidence from chemical and serological studies indicates that a cellular heteropolysaccharide, also found in lipid extracts and culture filtrate, is present as a group antigen in Mycobacterium tuberculosis H37Ra and in other strains of mycobacteria representing M. kansasii, scotochromogenic and Battey strains. Polysaccharides from the four strains contain the same main sugars, arabinose, and galactose, as revealed by thin-layer chromatography and spectrophotometric studies. In Ouchterlony gel diffusions, bands of identity are produced between the polysaccharides by using rabbit antiserum prepared against any of the four mycobacteria. Immune adsorption studies also confirm the presence of identical antigenic determinant groups. In skin tests with tuberculopolysaccharide I, a skin reaction of about equal size was elicited in guinea pigs sensitized with either M. tuberculosis H37Ra or heterologous mycobacterial antigens in Freund's incomplete adjuvant. In animals sensitized with M. tuberculosis H37Ra, skin tests with both homologous and heterologous polysaccharides elicited similar responses.

Animals↗
PubMed1969

Separation of folic acid reductase from Streptococcus faecium (ATCC 8043).

A strain of Streptococcus faecium (ATCC 8043) which is highly resistant to the antifolic acid compound, amethopterin, was gently ruptured by exposing protoplasts of the organism to a hypotonic solution. The crude lysate resulting there-from was treated by various chemical and physical techniques designed to separate folic acid reductase from dihydrofolic acid reductase. In the process, the enzyme was purified approximately 160-fold; however, throughout the process, the enzyme preparation maintained the ability to reduce folic acid to tetrahydrofolic acid. Attempts to isolate mutants showing a deficiency in either folic acid reductase or dihydrofolic acid reductase were unsuccessful. Based on these results, it is concluded that folic acid is reduced to tetrahydrofolic acid by one enzyme in S. faecium (ATCC 8043). The crude lysate was also subjected to ultracentrifugation. An analysis of the supernatant fluid and the sediment indicated that the reductive activity is located in the soluble fraction of the cell.

Bacterial Proteins↗
PubMed1968

Chemical and serological relationships between the heteropolysaccharides of Mycobacterium tuberculosis and Mycobacterium kansasii.

The identity of a heteropolysaccharide from cell walls of Mycobacterium tuberculosis H37Ra with Seibert's tuberculopolysaccharide I was demonstrated by thin-layer chromatography, chemical analysis, and antigenic tests. The polysaccharide of M. kansasii was shown to be identical with that of M. tuberculosis. Defatted cells were disintegrated by ultrasonic treatment in the presence of glass beads; cell walls were obtained by differential ultracentrifugation. Ethyl alcohol-precipitated carbohydrate extracts were analyzed for protein and nucleic acid; these impurities were removed. Tuberculopolysaccharide I from the mycobacterial culture filtrate is probably derived from a lipopolysaccharide of the cell wall, which is partially removed by chloroform in the intact state. Alkaline extraction releases additional polysaccharide, in varying degrees of association with cell wall murein.

Arabinose↗