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Biomedical subjects

M LANDY

Publications and source records attributed to M LANDY.

At least 19 recordsLinked to original sources
PubMed1965

INVOLVEMENT OF THYMUS IN IMMUNE RESPONSE OF RABBITS TO SOMATIC POLYSACCHARIDES OF GRAM-NEGATIVE BACTERIA.

Plaque-forming cells elaborating antibody specific for Salmonella enteritidis somatic antigen have been demonstrated in the thymus of rabbits 5 days after a single systemic injection of a minute amount of this bacterial polysaccharide. A marked decrease in organ weight and loss of thymic cellularity was also seen, and was most pronounced at the time when antibody-forming cells made their appearance.

Animals↗
PubMed1964

EXTRACTION AND PURIFICATION OF ENDOTOXIN FROM ENTEROBACTERIACEAE: A COMPARISON OF SELECTED METHODS AND SOURCES.

Fukushi, K. (National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Mont.), R. L. Anacker, W. T. Haskins, M. Landy, K. C. Milner, and E. Ribi. Extraction and purification of endotoxin from Enterobacteriaceae: a comparison of selected methods and sources. J. Bacteriol. 87:391-400. 1964.-Endotoxins containing only 0.2% N (accounted for by amino sugars) and 2% ester- and amide-linked fatty acids (calculated as palmitic acid) were prepared from Salmonella enteritidis. These products were of high biological potency, and were rapidly destroyed by acid hydrolysis. Equally potent acid-susceptible products were derived from different strains of Escherichia coli and Serratia marcescens. No correlation was evident between potency and content of nitrogen, fatty acids, and hexosamine; however, low values for carbohydrate were invariably associated with reduced endotoxic activity. Factors such as strain, method of cultivation, and extraction procedure markedly affected the chemical composition and activity of primary extracts. Results are given which demonstrate significant advantages in the use of cell walls for the isolation and purification of endotoxins.

Carbohydrates↗
PubMed1964

ORIGIN AND PROPERTIES OF NATURALLY OCCURRING HAPTEN FROM ESCHERICHIA COLI.

Anacker, R. L. (National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Mont.), R. A. Finkelstein, W. T. Haskins, M. Landy, K. C. Milner, E. Ribi, and P. W. Stashak. Origin and properties of naturally occurring hapten from Escherichia coli. J. Bacteriol. 88:1705-1720. 1964.-Haptens found in preparations of endotoxin and in fractions of disrupted cells, particularly one termed "native hapten," which appeared to be associated with the protoplasm of cells rather than with cell walls, have been further investigated with a view to establishing their origin and composition as well as their host-reactive properties. For this purpose, cells from a smooth strain of Escherichia coli O111:B4 were either extracted directly or disrupted and separated into cell-wall and protoplasmic fractions. Haptens were obtained by gel filtration of endotoxins, by trichloroacetic acid extraction of protoplasm, and by a mild acid hydrolysis of endotoxin. Several lines of evidence indicated that native hapten originated in the protoplasm rather than by autolysis or degradation of cell-wall endotoxin during procedures employed in disruption. In gel diffusion and quantitative precipitin tests, no hapten was identical with endotoxin, but native hapten was serologically the most complex of the haptens and precipitated the most antibody. Native and acid haptens, on a weight basis, fixed about 1% of the quantity of complement fixed by homologous endotoxin. Haptens did not stimulate the production of antibodies in mice or rabbits and did not elicit endotoxic host reactions. Chemically, native hapten differed from endotoxin and from acid hapten in that it lacked phosphorus, heptose, long-chain fatty acids, and 2-keto-3-deoxyoctonate. These substances did not appear to be determinants of antigenic specificity, but they may provide necessary bonds for assembling hapten-like units into fully antigenic and toxic macromolecules.

Animals↗
PubMed1963

Suppression of blood group agglutinability of human erythrocytes by certain bacterial polysaccharides.

Erythrocytes coated with bacterial capsular polysaccharides, notably the Vi antigen, were no longer agglutinated by antibodies directed against the various antigens native to the red cell surface. These effects could not be attributed to prevention of antibody uptake even though in some systems the uptake of antibody was diminished. In fact, agglutination by Rh-incomplete antibody was brought back to the original titer only after the sensitized Vi-coated cells had been subjected to ten alternating exposures to globulin and antiglobulin. Hemagglutination by Newcastle, mumps, and influenza viruses was also suppressed. Erythrocytes coated with Vi polysaccharide assumed the distinctive physicochemical attributes of this acidic polymer which results in a stabilization of the erythrocyte suspension as manifested by increased electrophoretic mobility and a striking decrease in the rate of sedimentation. Among the possible models for explaining the nature of the Vi effect on immune agglutination, the data favor interference with lattice formation.

Antibodies↗
PubMed1962

Studies on natural antibodies to gram-negative bacteria.

A study was made of the origin, occurrence, and properties of natural antibodies to Gram-negative bacteria in the normal serum of several species. Antibody was measured by a procedure based on the bactericidal reaction carried out under conditions in which activity was a function of the amount of antibody contributed by the test serum. Antibody to seven genera of the family Enterobacteriaceae were demonstrated in normal human serum. The specificity of these antibodies was affirmed by absorption with homologous bacteria and by inhibition of bactericidal activity with purified homologous somatic antigen. Absorption with graded amounts of bacterial suspensions showed that a large excess of bacteria led to non-specific removal of antibodies. Analogous findings were also made with immune antibody. As determined by quantitative absorption tests no difference could be found in the avidity of natural and immune antibody. Natural antibody in the serum of various species differed considerably as regards their lability to heat, but in parallel tests immune antibody of each species was significantly more heat-stable. The time and appearance of the antibodies varied in young animals, of different species. Mice developed these antibodies at the earliest age, with guinea pigs, rats, and rabbits following in that order. Serum from germ-free rats and chickens had no demonstrable antibodies to E. coli or S. typhosa whereas these antibodies were present in the serum of litter mates reared under conventional conditions. On the other hand germ-free and conventional mice did not differ appreciably as regards the levels of these same antibodies.

Animals↗
PubMed1962

Bactericidal method for the measurement in normal serum of antibody to gramnegative bacteria.

Landy, Maurice (National Cancer Institute, Bethesda, Md.), J. Gabriel Michael, and James L. Whitby. Bactericidal method for the measurement in normal serum of antibody to gram-negative bacteria. J. Bacteriol. 83:631-640. 1962.-The bactericidal effect of normal serum on gram-negative bacteria was investigated with the objective of determining whether this antibody-complement reaction could be used for the measurement of antibody. The major variables affecting the outcome of this complement-dependent reaction were explored systematically to establish the test conditions in which specific antibody was the limiting factor. Among these were the use of an excess of absorbed human serum as a complement source, inoculum, reaction conditions, and precise enumeration of surviving bacteria. It was demonstrated that the test conditions could be controlled so as to provide a sensitive and objective assay for antibody to representative strains of various gram-negative genera.

Anti-Bacterial Agents↗
PubMed1962

Physicochemical changes in endotoxin associated with loss of biological potency.

Ribi, Edgar (National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Mont.), Willard T. Haskins, Kelsey C. Milner, Robert L. Anacker, Daniel B. Ritter, Granville Goode, Robert-John Trapani, and Maurice Landy. Physicochemical changes in endotoxin associated with loss of biological potency. J. Bacteriol. 84:803-814. 1962.-The preparation of endotoxins whose gross chemical composition approached that of refined polysaccharide haptenes raised anew the question of which features of composition and structure are essential for their characteristic host reactivity. Alterations in the physicochemical, immunochemical, and biological properties of Salmonella enteritidis endotoxin subjected to hydrolysis with 0.1 n acetic acid were therefore investigated to relate physical characteristics to biological attributes. As hydrolysis proceeded, the decline in biological potency was paralleled by dissociation of endotoxin into particles of the size of haptenic polysaccharide. The potency still present at various stages of hydrolysis could be accounted for by residual undissociated endotoxin. These findings are consistent with the hypothesis that a macromolecular complex of critical size is one of the major requirements for endotoxin to elicit its characteristic effects in the mammalian host.

Animals↗