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Biomedical subjects

H Mayer

Publications and source records attributed to H Mayer.

At least 271 records · Page 15Linked to original sources
PubMed1980

Reactivity of isolated lipopolysaccharides of enterobacterial R mutants with complete or incomplete core structures with lectins.

Alkali-treated lipopolysaccharides of a range of enterobacterial R mutants with complete and incomplete core structures were investigated by agar gel and microcapillary precipitation onto their reactivity with three selected commercial lectins, namely Concanavalin A, Ricinus communis agglutinin and Wheat germ agglutinin. R lipopolysaccharides with complete R cores of the six so far established core types were differentiable from each other by their characteristic lectin reactivity pattern. One core type showed no reaction with all the three lectins. R lipopolysaccharides with incomplete core structure showed in general the reactivity pattern predictable from their individual chemical configuration. It was further shown that substitution of complete R cores by haptens (T1, T2 or ECA) or by a single repeating unit (SR mutant) did not change the reactivity pattern, although some interactions were less pronounced. It will be demonstrated that lectin precipitation can be of help for structural studies in recognizing, for example, terminal sugar units and their anomeric linkages.

Enterobacteriaceae↗
PubMed1979

A membrane glycoprotein of aggregating Dictyostelium cells with the properties of contact sites.

Aggregating cells of Dictyostelium discoideum form EDTA-stable contacts which are blocked by a Fab (antigen-binding fragment) preparation from antisera raised against membranes. The target site of the blocking Fab fragments has been identified as a specific glycoprotein. In this paper its purification, carbohydrate and amino acid composition are described. Purification was 800-fold, starting with cells lysed by digitonin. The plasma membranes, preserved as ghosts by this treatment, were purified in a two-phase system and extracted with butan-1-ol. The water phase contained predominantly concanavalin-A-binding glycoproteins and was particularly rich in contact sites A. These were further purified on DE-cellulose and sucrose gradients. Sodium dodecylsulphate/polyacrylamide gel electrophoresis of the purified material revealed one major glycoprotein band in the molecular weight region of 80 000 to 90 000, depending on the acrylamide concentration. The sugars found in contact sites A were mannose, N-acetylglucosamine, fucose, and possibly glucose. The protein moeity contained 8% proline and was particularly rich in hydroxy amino acids.

Amino Acids↗
PubMed1979

[A contribution about serious ophthalmic complications with oral contraceptives (author's transl)].

The treatment with oral contraceptives leads infrequently to serious thrombo-embolic cases of sickness in the eye and in the central nervous system with mostly irreversible results. Here is reported about three such cases in which--after intake of oral contraceptives with low-dose portion of oestrogen--ophthalmic complications have appeared, in which by reason of comprehensive internal, neurological and neuroradiological examinations, this treatment has very probably released the ophthalmic complications. As soon as there are appearing migraine-like headache attacks and vision disorders under treatment with oral contraceptives, termination of the treatment is recommended.

Adult↗
PubMed1978

Retinoids, a new class of compounds with prophylactic and therapeutic activities in oncology and dermatology.

A review of recent investigations in the retinoid field is presented. Retinoic acid exerts a prophylactic and a therapeutic effect on chemically induced benign and malignant epithelial tumors in mice. In clinical studies positive therapeutic results have been obtained in patients with preneoplastic and neoplastic epithelial lesions. However, treatment with retinoic acid is limited by serious side effects (hypervitaminosis A syndrome). Therefore, the synthesis of analogs of retinoic acid (retinoids) possessing a more favorable therapeutic ratio has been initiated. Among a large series of synthesized compounds, certain aromatic analogs proved to have a particularly favorable therapeutic ratio. The structure-activity relationship of the most active retinoids is discussed including some biological data concerning prophylaxis and therapy of epithelial tumors. The total synthesis of retinoids according to various building schemes is discussed in detail. Methods for the synthesis of the cyclic end group, of the polyene chain component, and of the full retinoid skeleton are described. Metabolic studies of retinoic acid and of the most active retinoid, as well as the synthesis of some isolated metabolites are outlined. Suggestions concerning the mechanism of action of retinoids are made. Some clinical results on the treatment of acne, psoriasis and precancerous conditions are reported.

Animals↗
PubMed1978

Structural studies on the immunogenic form of the enterobacterial common antigen.

It has been shown that enterobacterial common antigen is chemically linked to the hexose region of the R1-type lipopolysaccharide fo the Escherichia coli strain F470 which is immunogenic for this antigen. The number of R core stubs substituted is very small but it is a-parently sufficient to induce antibody formation to the enterobacterial common antigen in the rabbit.

Acetylglucosamine↗
PubMed1978

Location of O-methyl sugars in antigenic (lipo-)polysaccharides of photosynthetic bacteria and cyanobacteria.

An attempt was made to localize a number of O-methyl sugars in lipopolysaccharides and antigenic polysaccharides isolated from photosynthetic bacteria and from cyano-bacteria. Methylation analysis with [2H3]methyl iodide as methylating agent was the method of choice. One has to differentiate between (lipo-)polysaccharides having only trace amounts (less than 1% of polymer dry weight) of O-methyl sugars and those having them in larger amounts (more than 4% of polymer dry weight). In the former case O-methyl sugars occupy either non-reducing or reducing terminals. When present in larger quantities they may be present as part of each repeating unit either in chain-linked or in terminal positions or in both. A possible role of O-methyl sugars in biosynthesis of O-chains, and their contribution to the lipophilic character of the cell surface are discussed.

Antigens, Bacterial↗
PubMed1978

Structural studies on the D-arabinose-containing lipid A from Rhodospirillum tenue 2761.

Structural studies carried out on the isolated free lipid A of Rhodospirillum tenue 2761 revealed a new type of structure for this lipid. The lipid A backbone of 1',6-linked glucosamine disaccharide (central disaccharide) is substituted by three different sugar residues: the non-reducing end of the disaccharide by 4-amino-4-deoxy-L-arabinose 1-phosphate and its reducing end glycosidically by D-arabinofuranose 1-phosphate; further, the reducing glucosamine of the disaccharide is branched to a third glucosamine residue by a 1'',4-glycosidic linkage. The amino and the hydroxyl groups of the central disaccharide are acylated by 3-hydroxydecanoic acid (amide-linked) and palmitic and myristic acids (ester-linked). Neither amino nor hydroxyl groups of the three external sugar residues are acylated. The results suggest the following chemical structure for the lipid A of R. tenue 2761: (formula: see text).

Arabinose↗
PubMed1978

Chemical structure and biological activities of lipid A's from various bacterial families.

The endotoxic principle of lipopolysaccharides (LPS) is localized in their lipid A component. Biological effects of LPS on, for instance, body temperature, blood pressure, and blood picture, are also induced by free lipid A. In contrast to the great variability of the 0-specific chains, the chemical structure of lipid A is much more constant. It is common for Salmonella and similar for other genera of the Enterobacteriaceae. Recently, a number of lipid A's have been recognized that exhibited distinct structural features compared with Enterobacteriaceae. These lipid A's were found to be also distinct with regard to some of their biological properties.

Carbohydrates↗
PubMed1978

Isolation and characterization of the lipopolysaccharide of Thiocapsa roseopersicina.

The lipopolysaccharide from Thiocapsa roseopersicina was isolated by phenol/water, being found in the water phase. It is cleaved into a polysaccharide moiety (degraded polysaccharide) and lipid A by hydrolysis with 10% acetic acid (100 degree C, 3 h). D-Mannose, L-rhamnose, 3-amino-3, 6-dideoxy-D-galactose and D-glucose are the major constituents of the degraded polysaccharide. 2-O-Methyl-L-rhamnose, 3-O-methyl-D-mannose, D-galactose, glucosamine and quinovosamine are minor constituents. D-Glycer-D-manno-heptose (tentatively identified) and 3-deoxy-D-manno-octulosonic acid were detected in only small amounts. Conspicuously, lipid A from T. roseopersicina contains a neutral sugar, D-mannose, in addition to D-glucosamine, as had been observed with lipid A from Chromatium vinosum D. Major fatty acids are beta-hydroxymyristic and lauric acids. Only trace amounts of phosphorus were found indicating this lipid A to be free of phosphate. The lipopolysaccharide of T. roseopersicina represents the O-antigen of the strain. It reacts with antisera prepared against living or heat-killed cells in passive hemagglutination.

Carbohydrates↗