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G Caldes

Publications and source records attributed to G Caldes.

32 records · Page 2Linked to original sources

Production and Properties of Antisera to Membrane Glycolipids of Mycoplasma pneumoniae.

The glycolipid haptens of Mycoplasma pneumoniae became immunogenic when bound to membrane proteins of Acholeplasma laidlawii by reaggregation. This process consisted of the solubilization of lipid-depleted A. laidlawii membranes and M. pneumoniae glycolipids in 20 mm sodium dodecyl sulfate and dialysis of the mixed solutions against 20 mm Mg(2+). The antibodies produced in rabbits to the reaggregated glycolipids inhibited the metabolism of M. pneumoniae, fixed complement with M. pneumoniae glycolipids or whole cells, precipitated M. pneumoniae glycolipids, and agglutinated M. pneumoniae cells. All these antibody activities could be blocked or absorbed by the purified glycolipids but not by a series of carbohydrates containing glucose and galactose. It was concluded that the antiserum to the reaggregated glycolipids may be regarded as a specific serum to membrane glycolipids of M. pneumoniae, since the antibodies to A. laidlawii membrane proteins, present in this serum, did not react with the glycolipids or with any other cell component of M. pneumoniae.

Journal Article↗

Role of Glycolipids and Phosphatidylglycerol in the Serological Activity of Mycoplasma pneumoniae.

Mycoplasma pneumoniae lipids were fractionated by combined silicic acid and diethylaminoethyl-cellulose chromatography. The lipid fractions were tested for complement-fixing activity and for blocking of metabolism-inhibiting antibodies in human and rabbit antisera to M. pneumoniae. Thin-layer chromatography and carbohydrate analysis of hydrolysates of the lipid fractions indicated that glycolipids were responsible for the specific serological activities of the lipid extracts of the organism. Phosphatidylglycerol, which accompanied the glycolipids, was serologically inactive when isolated free from glycolipids. Phosphatidylglycerol considerably enhanced the serological activity of the glycolipids, serving as an auxiliary lipid. Because of this auxiliary effect, minute quantities of contaminating glycolipids sufficed to render serological activity to "purified" phosphatidylgylcerol preparations, providing an explanation to the previous identification of the active lipid as a phospholipid.

Journal Article↗

Isolation and characterization of fractions of Mycoplasma pneumoniae. I. Chemical and chromatographic separation.

Prescott, B. (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), O. Sobeslavsky, G. Caldes, and R. M. Chanock. Isolation and characterization of fractions of Mycoplasma pneumoniae. I. Chemical and chromatographic separation. J. Bacteriol. 91:2117-2125. 1966.-Fractionation of Mycoplasma pneumoniae, cultured on a beef heart infusion-horse serum-yeast extract medium, was carried out by chemical and chromatographic procedures. The chemical method yielded eight fractions consisting of lipid, carbohydrates, and proteins. Four protein-rich fractions were isolated by chromatographing a supernatant fluid of sonically treated organisms on Sephadex G-25. The 12 fractions were tested for serological and antigenic activity in vitro and in vivo. The lipid fraction was serologically active and the relative order of activity of the protein fractions appeared to depend on the amount of lipid present in the molecule. The highly serologically active Sephadex G-25 protein fraction 1 prepared chromatographically contained 15% lipid in the molecule, whereas the less serologically active protein fraction 2 prepared by chemical means contained 2% lipid. The acetone-extracted lipid fraction was chromatographed on thin-layer chromatography plates and found to consist of nine fractions. Serological activity was associated with only the first three spots above the origin. Lipid extracted from the protein fractions seemed to be similar to the acetone-extracted lipid from the sediment of the sonically treated organisms.

Amino Acids↗

Regulation of the antibody response to pneumococcal polysaccharide by thymus-derived cells.

The dose-response relationships in mice immunized with capsular polysaccharide of type 3 Streptococcus pneumoniae (SSS-III) show a distinctive pattern characterized by a single optimal dose for immunization within a relatively narrow range of immunizing doses. Most of the antibody produced is of the IgM class, and the kinetics for the development of both the cellular and serum antibody response to this antigen are parallel up to the peak of the immune response. Although thymus-derived (T) cells are not needed to initiate an antibody response to SSS-III, the magnitude of the antibody response is influenced greatly by the activities of two types of T cells with opposing functions; such regulatory T cells have been termed suppressor and amplifier T cells. The mode of action of suppressor and amplifier T cells as well as the manner in which they might interact during the antibody response to SSS-III are discussed.

Animals↗