Search PubMed⌕ Search

Biomedical subjects

A Nowotny

Publications and source records attributed to A Nowotny.

At least 73 records · Page 4Linked to original sources
PubMed1974

Comparison of the chemical structure and biological activities of the glycolipids of Salmonella minnesota R595 and Salmonella typhimurium SL1102.

It has been assumed in the past that the lipid moieties of endotoxic lipopolysaccharides are quite similar if not identical. This has been tested in the reported work here, where the chemical composition and biological activities of the glycolipids of two heptoseless Re mutants, Salmonella minnesota R595 and Salmonella typhimurium SL1102, have been studied and compared. The two glycolipids, extracted with chloroform-methanol (4:1), showed identical thin-layer chromatographic patterns. The molar ratios for hexosamine, fatty acids, phosphorus, 2-keto-3-deoxyoctonate, total amines, and total nitrogen of the purified glycolipids were in the same range, but small differences could be established. Both glycolipids contained the same major fatty acids, i.e., lauric, myristic, palmitic, and 3-hydroxymyristic acids, in similar but not identical ratios. On paper electrophoresis, the acid hydrolysates of the two glycolipids showed analogous components. In the determination of molecular weight, whereas S. minnesota R595 glycolipid did not show concentration dependence, the molecular weight measured for S. typhimurium SL1102 increased with its concentration. The molecular weight of the fully endotoxic R595 glycolipid has been found to be 17,000 +/- 1,500. Both glycolipids showed similar activities in the Shwartzman skin reaction, Limulus-lysate clotting assay, mouse lethality, and enhancement of nonspecific resistance, but the R595 preparation appeared to be more active on a weight basis in some parameters than SL1102. Using passive hemagglutination, we observed cross-reactivity between the glycolipids. In the gel-diffusion test, they revealed clear identity. The antiserum against S. minnesota R595 neutralized the Shwartzman skin reactivity not only of R595 but also of SL1102 glycolipid. These results confirm that there are identical immunodeterminant group(s) in the two glycolipids. On the other hand, chemical analytical data for two glycolipids showed only similarities, indicating that although both glycolipids are of comparable chemical nature, differences between them exist.

Antibodies, Bacterial↗
PubMed1974

Effect of endotoxin on tumor resistance in mice.

As reported earlier, an intraperitoneal injection of 1 mug of endotoxin (ET) from Serratia marcescens rendered mice resistant against the nonspecific mouse ascites tumor TA3-Ha upon challenge 24 h after pretreatment with ET. Further studies were aimed at the elaboration of conditions which achieved maximal resistance. It appears that (i) a 10-mug dose of ET was approximately the optimal dose for protection; (ii) pretreatment with ET 3 to 0 days prior to tumor challenge gave best protection; and (iii) the intravenous injection of ET showed a lower protection against the tumor than intraperitoneal application. Studies on the mechanism of ET protection indicate that (i) ET does not have a direct cytotoxic effect on tumor cells; (ii) normal spleen cells exposed to ET in vitro can adoptively transfer protection against tumor; and (iii) spleen cells activated in vivo by intravenous injection of ET can adoptively transfer protection. The possible involvement of mononuclear cells is discussed.

Animals↗
PubMed1973

In vitro transformation of mouse bone-marrow-derived (B) lymphocytes induced by the lipid component of endotoxin.

An analysis of which component of lipopolysaccharide, the lipid or the polysaccharide, is mitogenic for mouse B-lymphocytes has been performed. A purified glycolipid derived from a rough mutant of Salmonella minnesota (R595) that does not contain any o-polysaccharide at all is more mitogenic than an intact lipopolysaccharide derived from a smooth strain of S. minnesota. Results using fractions produced by several different chemical modifications of whole lipopolysaccharide confirm this result. Acid hydrolysis separates lipopolysaccharide into two components. The lipid fraction is mitogenic, whereas the polysaccharide fraction is not. Those procedures which degrade or modify only the lipid moiety while preserving the antigenic integrity of the polysaccharide also destroy mitogenicity. These include alkaline hydrolysis and deacylation by a more specific treatment with potassium methylate. The lipid preparations are fully active on highly purified B-lymphocyte populations (prepared by anti-theta antiserum and complement), whereas they have no effect on highly purified T-lymphocyte populations (prepared by anti-immunoglobulin and complement). These data demonstrate that the lipid moiety of endotoxin is the B-lymphocyte mitogen, whereas the polysaccharide has no demonstrable mitogenic activity.

Animals↗
PubMed1972

Isolation and purification of endotoxin by hydrolytic enzymes.

Various commercial hydrolases were used in an attempt to degrade the endotoxic lipopolysaccharide macromolecule. Some inert components, such as peptides and nucleic acids, could be removed from endotoxin preparations. As a result, endotoxic activity, measured by pyrogenicity, Shwartzman reaction, and mouse lethality, was increased. The remarkable resistance of endotoxin to hydrolases led to the use of such enzymes for the liberation and purification of endotoxin from whole bacterial cells.

Alkaline Phosphatase↗
PubMed1968

Interactions of the complement system with native and chemically modified endotoxins.

Endotoxic lipopolysaccharides (LPS) isolated from Serratia marcescens, Veillonella alcalescens, and Salmonella typhosa were potent in their ability to induce fixation of complement (C') in normal guinea pig, rabbit, mouse, and human serum. The C'-fixing ability of LPS was pronounced even when assays were performed in undiluted serum, and was lost after each of four chemical modifications which resulted in loss of biological toxicities. The detoxification procedures had in common the cleavage of ester-bound, long-chain carboxylic acids. The ability of biologically active LPS to fix C' in normal guinea pig serum was reflected chiefly in dramatic uptake of classical C'3 (C'3t); fixation of C'1, C'4, and C'2 was virtually undetectable. Hence, it was the capacity for fixation of C'3t which was lost most overtly during detoxification. Addition of immune serum to the assay mixtures resulted in detectable fixation of C'1 and C'4. Biologically active LPS also fixed more of these components than did detoxified LPS. Immune serum restored the ability of detoxified LPS to fix C'3t, but whether this is by the original pathway is not yet clear. We concluded that the loss of certain biological activities and the loss of ability to fix C'3t in normal serum after LPS detoxification involved loss or rearrangement of substrates on LPS which either initiated or supported, or both, its interaction with the complement system. It was apparent that the ability to fix C' can serve as a valuable in vitro indicator of the integrity of the toxic conformation of biologically active LPS membrane fragments. These experiments supported the hypothesis that certain of the biological activities induced by endotoxins are mediated via the complement system.

Animals↗