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H G Schiefer

Publications and source records attributed to H G Schiefer.

13 recordsLinked to original sources
PubMed1979

Electron microscopic studies on the attachment of Mycoplasma pneumoniae to guinea pig erythrocytes.

A mechanism of pathogenicity of Mycoplasma pneumoniae is its ability to attach to the surface of mammalian cells. It has previously been demonstrated by others that M. pneumoniae adheres with a specialized terminal structure, the "tip," to ciliated epithelial cells of the respiratory tract. In this report we show by electron microscopy that M. pneumoniae adsorbs with membrane sites other than the tip to guinea pig erythrocytes.

Animals↗
PubMed1977

Ultrastructural investigations on surface structures involved in Coxiella burnetii phase variation.

By using the cytochemical staining procedure with concanavalin A, horseradish peroxidase, and diaminobenzidine, no surface carbohydrates with terminal alpha-glucosyl or sterically closely related residues could be detected on the cell walls of Coxiella burnetii phases I and II. Using a polycationized ferritin derivative as a cytochemical probe, anionic binding sites were visualized in the electron microscope on cell membranes of C. burnetii phase II, but not on phase I organisms. The sites appeared to be masked in phase I particles. Anionic sites could be demonstrated on phase I organisms after treatment with NaIO4 or dimethyl sulfoxide. A number of different biological properties of C. burnetii phases I and II may depend on the presence or absence of a net negative charge on the surface of the cell walls of these organisms.

Acetone↗
PubMed1977

Localization of a phosphoglycolipid in Mycoplasma membranes using specific anti-lipid-antibodies.

A phosphoglycolipid, presumably identical to glyceryl-phosphoryldiglycosyl diglyceride, is the main component of the membrane glycolipids of Mycoplasma mycoides subsp. capri. It is immunologically active. Anti-phosphoglycolipid antibodies were induced in rabbits by intravenous injection of the flocculated complexes of methylated bovine serum albumin with a mixture of the phosphoglycolipid and the auxiliary lipids, phosphatidyl-choline and cholesterol. The specificities of the antibodies directed against the phosphoglycolipid, are due to both the phosphate and carbohydrate moieties of the lipid molecule. Anti-phosphoglycolipid antibodies were detected in the sera of rabbits intravenously immunized with intact M. mycoides subsp. capri. The intravenous method of immunization was chosen in order to select for a response to surface antigenic determinants. Anti-phosphoglycolipid antibodies specifically reacted with intact organisms and isolated membranes of M. mycoides subsp. capri, as shown by complement fixation and agglutination tests. The antigenic determinants of the phosphoglycolipid are mainly located on the outer membrane surface. It is concluded that the antigenic determinants of the phosphoglycolipid in intact M. mycoides subsp. capri significantly contribute to the surface architecture of mycoplasma membranes.

Acholeplasma laidlawii↗
PubMed1977

[Ultrastructural investigations on anionic surface sites of Brucella canis (author's transl)].

Anionic sites on the surface of Brucella canis were visualized in the electron microscope by staining with positively charged ferric oxide hydrosols in acetic acid (AI-reagent), or propanoic acid (PI-reagent), and with a polycationic ferritin derivative. With the AI-reagent, single or small aggregates of ferric oxide particles were bound to the cell surface of Br. canis, whereas, with the lipophilic PI-reagent, the microorganisms were heavily stained with focal aggregates of iron granules. The polycationic ferritin label was uniformly distributed over the entire cell surface of Br. canis. The ferritin label was not bound on the surface of the organisms after prior treatment with trichloroacetic acid or methanolic hydrochloric acid. Treatment with aqueous acetone, chloroform/methanol, diethyl ether, sodium deoxycholate, pronase, lysozyme, hyaluronidase, and sodium periodate neither influenced the morphology of the Brucella nor diminished their ionic binding sites. Our results indicate that the anionic sites on the cell surface of Br. canis may be carboxyl and phosphate groups of lipopolysaccharides.

Anions↗
PubMed1977

Ultrastructural and cytochemical studies on anionic surface sites of Mycoplasma membranes.

Negatively charged, chemical groups on the surfaces of mycoplasma membranes were studied in the electron microscope by staining with positively charged ferric oxide hydrosols in the acetic acid (AI-reagent) or propanoic acid (PI-reagent), respectively. The technique of thin sectioning was used. With the AI-reagent, no significant binding of the ferric oxide particles was observed on the mycoplasma membranes. With the lipophilic PI-reagent, the membrane surfaces of M. mycoides subsp. capri, M. mycoides subsp. mycoides, M. gallisepticum, and Acholeplasma laidlawii were heavily stained with focal aggregates of iron granules. M. hominis did not bind the label. Prior chemical and enzymatic treatments indicate that the cationic ferric oxide particles in propanoic acid interact with negatively charged, presumably lipid phosphate groups exposed on the surfaces of mycoplasma membranes.

Anions↗
PubMed1976

Complement-mediated killing of Acholeplasma laidlawii by antibodies to various membrane components.

Mycoplasmas are useful models for biochemical studies of the mechanism of complement-mediated killing by antibodies to various membrane components. The purpose of this study was to determine the membrane antigens involved in immune killing of Acholeplasma laidlawii. Antibodies to A. laidlawii membrane total lipids, glycolipids, and phospholipids could be induced in rabbits after injection of reaggregates of the purified lipids with Mycoplasma hominis protein as the carrier. Killing of A. laidlawii membrane lipids were less effective than anti-membrane protein antisera in killing the organisms. Of the antisera to lipid components of A. laidlawii membranes, antiserum to phospholipids showed a more pronounced killing effect than antiserum to glycolipids. The antibodies to A. laidlawii in the rabbit antisera belong predominantly to the immunoglobulin G class of immunoglobulins. Double-diffusion tests in agar indicated that two immunologically reactive proteins are located on the membrane surface.

Acholeplasma laidlawii↗
PubMed1976

Ultrastructural visualization of anionic sites on mycoplasma membranes by polycationic ferritin.

Anionic sites on mycoplasma membranes were visualized in the electron microscope by a polycationized ferritin derivative. The technique of thin sectioning was used. Staining prior to fixation led to clustering of ferritin granules on the mycoplasma cell surface. On glutaraldehyde-fixed Mycoplasma mycoides subsp. capri, M. gallisepticum, M. pneumoniae, and Acholeplasma laidlawii, the anionic sites were uniformly distributed over the entire membrane surface. M. hominis did not bind the polycationic ferritin label. Chemical and enzymatic treatments of the mycoplasmas indicated that the anionic sites may be lipid phosphate groups. Isolated M. mycoides subsp. capri membranes were labeled exclusively on only one membrane surface, presumably the outer one. Liposomes prepared from diphosphatidylglycerol and phosphatidylcholine were also labeled by the polycationic ferritin.

Acholeplasma laidlawii↗
PubMed1975

Electron spin resonance studies on the lipid-protein interaction between cardiolipin and anti-cardiolipin antibodies.

Electron spin resonance measurements were performed in order to investigate the influence of anti-cardiolipin antibodies on cardiolipin-containing liposomes. The physical state of the lipid structures and the alterations caused by the interaction with specific antibody were determined by measuring the freedom of motion of spin-labeled stearic acid derivatives incorporated into the lipid structures. The interaction of the cardiolipin-containing liposomes with the anti-cardiolipin antibodies reduced the mobility of the spin-labeled stearic acid probe I (12, 3), whose nitroxide group is assumed to be located near the polar region of the lipid bilayer. The restricted mobility, which qualitatively resembles the interaction of cardiolipin liposomes with calcium ions, is probably the result of a tighter packing of the polar groups in their crystalline array. The binding sites of the cardiolipin structures for anti-cardiolipin antibodies and Ca2 ions seem to be identical. As indicated by the spin-labeled stearic acid probe I (1, 14), the apolar region of the lipid bilayer is not affected by the interaction of the cardiolipin-containing liposomes with the anti-cardiolipin antibodies.

Antigen-Antibody Reactions↗