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W Bredt

Publications and source records attributed to W Bredt.

At least 55 records · Page 3Linked to original sources
PubMed1981

Filamentous structures in adherent Mycoplasma pneumoniae cells treated with nonionic detergents.

Mycoplasma pneumoniae cells adhering to glass or Parlodion-coated grids were extracted with Triton X-100. The extracted cells showed a cytoskeleton consisting of a rodlike tip structure and a filamentous network in the cytoplasm. The tip structure was up to 300 nm long and approximately 40 nm wide ending at the distal end in a bleb-like structure, and seemed to consist of filaments arranged in parallel, 4.8 +/- 0.5 nm wide. In the cytoplasm the filaments formed an irregular lattice. Similar filaments were found in platinum replicated critical-point dried extracted cells. An actinlike nature of the filaments is suggested by some of their properties, but the degree of homology with respect to eucaryotic actin is still unknown. The filaments were sensitive to protease treatment but stable in high molar KCl solutions. They were apparently destroyed by incubation in high molar KI solution, leaving only some parts of the tip structure. Formaldehyde-fixed M. pneumoniae cells treated with Triton X-100 bound rhodamine-labeled phalloidin specifically. Furthermore, they could be stained with antiactin antibodies. Binding of myosin subfragment 1 to the filaments was not observed.

Actins↗
PubMed1981

Role of energy metabolism in Mycoplasma pneumoniae attachment to glass surfaces.

Attachment values of Mycoplasma pneumoniae to glass are normally very low when tested in buffer containing bovine serum albumin (10 mg/ml). However, the addition of one of the metabolizable sugars glucose, fructose, or mannose increased attachment more than 10-fold. The effect was dose dependent with a distinct optimum at about 0.25 mg/ml. Higher concentrations reduced this effect. Not only the sugars themselves but also the products of their catabolism, pyruvate and phosphoenolpyruvate, enhanced attachment. Pyruvate was effective in the same range of concentrations as the sugars, whereas phosphoenolpyruvate enhanced attachment at a significantly lower concentration (0.001 mg/ml). Higher levels of these substances also resulted in a decrease of attachment. The glucose-induced increase could be partially inhibited by glucose analogs, especially by 3-O-methyl-glucopyranoside, and by various inhibitors or glycolysis. Furthermore, attachment was strongly reduced by the uncoupling agents carbonylcyanide m-chlorophenylhydrazone and 2,4-dinitrophenol, as well as by dicyclohexylcarbodiimide, an inhibitor of the membrane-bound Mg2+-adenosine triphosphatase, whereas the ionophore valinomycin increased attachment by about 30%. These findings provide strong evidence for coupling between the attachment process of M. pneumoniae to glass and the utilization of metabolic energy.

Chloramphenicol↗
PubMed1981

[Infectious non-gonococcal urethritis in males (author's transl)].

Infectious non-gonococcal urethritis (NGU) is a sexually transmitted disease of considerable importance. The etiologic agents are bacteria, to lesser extent yeasts, parasites (Trichomonas) or viruses. A considerable part of NGU is caused by bacterial groups with peculiar properties: Mycoplasmas, which lack a rigid cell wall, and chlamydiae, which are intracellular parasites. Because of the diversity of etiologic agents and qualified microbiological diagnosis is a prerequisite for a specific and successful therapy.

Anti-Bacterial Agents↗
PubMed1981

Attachment of mycoplasmas to erythrocytes: a model to study mycoplasma attachment to the epithelium of the host respiratory tract.

Mycoplasma pneumoniae, M. gallisepticum and M. pulmonis are pathogens of the respiratory tract. Their adherence to the host tissue is a prerequisite for manifestation of the disease. The attachment occurs between membrane components of the mycoplasmas and the host cells. In the attachment of M. pneumoniae and M. gallisepticum, binding sites of a protein nature of the mycoplasma membranes interact primarily with sialic acid residues of sialoglycoproteins of the host cell membranes. The latter was clearly indicated in studies on the pathogenic strain of M. pneumoniae and its nonpathogenic nonhemadsorbing mutants, and by the assessment of the direct binding of glycophorin [the major sialoglycoprotein of human red blood cells (RBC)] and other sialoglycoproteins to M. pneumoniae and M. gallisepticum. The components involved in the interaction of M. pulmonis with the host cells are not as well characterized, since the attachment is not affected by proteolytic treatment of the mycoplasmas, nor by removal of sialic acid residues from the host cell membranes. The attachment of the mycoplasmas to the host cells also occurs with nonviable organisms and can, in addition, by reproduced by isolated membranes. The binding sites of M. pneumoniae and M. gallisepticum were partially purified by affinity chromatography, using the high affinity of the binding sites for glycophorin. By this procedure the membranes were solubilized with detergents and chromatographed through glycophorin attached to Sepharose 4B as an affinity matrix. The binding sites retained the high affinity for glycophorin and bound to RBC membranes. Are the binding sites distributed throughout the membrane? Since the binding of the mycoplasma is via a polar structure (the tip or bleb), one may suggest that these structures harbor them. Experimental evidence for their distribution is being sought.

Adhesiveness↗
PubMed1981

Phagocytosis and complement action.

THe interaction of pathogenic mycoplasmas with two components of the "nonspecific" defence system is influenced by the lack of a cell wall and perhaps the tight attachment to host cells. On mycoplasmas, complement can act directly on the parasite membrane surface and cause damage comparable to the effects on animal cells, namely lysis and death. Results with Mycoplasma pneumoniae suggest a direct activation by this species of the complement sequence without participation of homologous antibody. Activation may occur via the alternate pathway and perhaps even by direct triggering of the classical pathway. The action results in rounding, opsonization and death of some or all of the cells. Since complement components have been found in bronchial washings, this direct activation may be of some importance in the first stages of infection. Furthermore, it sufficiently explains the fact that M. pneumoniae is found only on the surface but not in the deeper tissues of the respiratory tract even in severe infections. The interactions of mycoplasmas with phagocytes, one of the first lines of defence against infection, is of considerable interest. Mycoplasmas seem to be relatively resistant to phagocytosis as long as they are not opsonized. They have been observed attaching to macrophage surfaces without being ingested. Addition of homologous antibody triggered immediate engulfment and intracellular killing. The aspects of interaction of phagocytes with mycoplasmas are even more interesting because in most cases the mycoplasmas which have to be phagocytized are attached to the surface of other tissue cells. This raises the problem of secondary damage caused by the enzymes of the phagocytizing cell. Our knowledge about the mycoplasma-phagocyte-interaction is scarce and the experimental approaches are difficult.

Animals↗
PubMed1981

Antigenic components used in vaccines and their possible role in protection.

The success of active immunization depends on the production of antibodies or immunologically active cells directed against antigens of the parasite, which are involved in pathogenesis. These could be substances mediating attachment, antiphagocytic materials, structures involved in motility, or toxins and toxic enzymes. An additional target mechanism in mycoplasmas could be the exposed membrane and its metabolic mechanisms. The results of these immune reactions appear as inhibition of attachment, as opsonization, immobilization, antitotic effects or metabolic inhibition. Often only an infection with attenuated organisms will provide sufficient protection, suggesting the necessity of more intensive immunologic stimulation or an involvement of antigens that are present only in small quantities. To minimize side effects, the optimal vaccine should contain only antigens that are known to be relevant for protection.

Antigens, Bacterial↗
PubMed1981

Adherence of mycoplasmas to cells and inert surfaces: phenomena, experimental models and possible mechanisms.

Mycoplasmas are typical surface parasites colonizing the mucous membranes of animals and man. Efficient adherence mechanisms are therefore a prerequisite for survival and, in some species, for pathogenicity. The lack of a rigid cell wall enables the mycoplasmas, in contrast to bacterial mechanisms, to actively rearrange their surface structure in a vertical or horizontal direction. The energy requirement for attachment of M. pneumoniae in inert surfaces strongly suggests such a mechanism, although no supporting morphological data are yet available. There seem to exist different kinds of adherence mechanisms depending on the species of mycoplasma and the host involved. The receptors of sheep erythrocytes for M. pneumoniae, M. gallisepticum and M. dispar are neuraminidase-sensitive, whereas those for M. hominis and M. salivarium are not, but are protease-sensitive. On the other hand the receptors of rabbit red blood cells for M. pneumoniae and M. dispar are neuraminidase-resistant. The binding sites on the mycoplasma surface too differ in some properties. Data on M. pneumoniae suggest a protein as major constituent of the binding mechanism. The results of all studies are to some extent also dependent on the method used to examine adherence. Most work was done with either hemagglutination and hemadsorption or with attachment to cells and organ cultures. A special experimental system is provided by the adherence of some species to glass or plastic surfaces. On this model the role of energy metabolism could be studied in more detail. Further strategy of research must include biochemical methods as well as morphological and immunological approaches.

Adhesiveness↗
PubMed1980

Scanning electron microscopy of mycoplasmas adhering to erythrocytes.

The interaction of Mycoplasma pneumoniae and Mycoplasma gallisepticum with human erythrocytes (RBC) was studied by scanning electron microscopy. The tight nature of the attachment of the microorganisms to the RBC was indicated by the indentation of the RBC surface at the site of attachment of M. gallisepticum cells and by traction and resulting distortion in the shape of the RBC at the point of its attachment to M. pneumoniae filaments growing on glass or plastic. In many cases attachment took place via the tip of the filaments, the membrane of the parasite appearing to be fused with that of the RBC. The morphology of the mycoplasmas growing on cover slips conformed in general with previous descriptions obtained by scanning electron microscopy. Growth of M. pneumoniae on glass or plastic consisted of branching filaments spread on the inert surface and microcolonies made up of intertwining filaments projecting into the medium. The filaments had a bulbous swelling adjacent to a tapered tip end. A few filaments were shown to have a ropelike helical twist. M. gallisepticum grown on the cover slips of Leighton tubes had a peculiar fusiform or teardrop shape with blebs at one or both poles of the cells. Elongated filamentous forms and chains of coccobacillary bodies were observed as well.

Cell Adhesion↗
PubMed1980

Isolation of binding sites to glycophorin from Mycoplasma pneumoniae membranes.

Sialoglycoproteins are major receptor sites for attachment of Mycoplasma pneumoniae to respiratory epithelium and erythrocytes (RBC). We used glycophorin, the major sialoglycoprotein of human RBC, as a ligand in affinity chromatography for the isolation of the binding sites from M. pneumoniae membranes. Membranes isolated from M. pneumoniae cells, radioiodinated by the lactoperoxidase technique, were treated with 0.5% deoxycholate. The insoluble residue, exhibiting an increased capacity to bind to RBC, was solubilized by 0.1% sodium dodecyl sulfate. The solubilized material was subjected to chromatography on a glycophorin-Sepharose column. The fraction retained on the column was eluted with 0.2% sodium dodecyl sulfate. It lacked the high-molecular-weight polypeptides and was highly enriched with two polypeptides (apparent molecular weights, 45,000 and 25,000). The eluted fraction exhibited a high capacity to bind to glycophorin-Sepharose beads and a lower capacity to bind to RBC. The binding of the eluted fraction to RBC was almost completely abolished by glycophorin, but not by its hydrophobic moiety. Binding of the fraction to glycophorin-Sepharose beads was inhibited to about the same extent by both glycophorin and its hydrophobic moiety, suggesting that components of the eluted fraction are also capable of binding to the hydrophobic moiety of glycophorin, which is apparently exposed on the beads but not on the RBC surface.

Binding Sites↗
PubMed1979

Simulation and prevention of retrovirus--specific reactions by mycoplasmas.

From human mycosis fungoides tumor-derived cell lines, Mycoplasma hyorhinis was isolated. This mycoplasma shared the following characteristics with retroviruses: uptake of 3H-uridine, but not of 3H-thymidine in cell culture; banding at 1.16 g/ml sucrose density and partial shift to retrovirus core density position (approximately equal to 1.24 g/ml) after detergent treatment; incorporation of 3H-TMP into high molecular weight material in standard reverse transcriptase assays with the template-primer poly (A) . (dT)12. On the other hand, the specific reverse transcriptase reaction of retroviruses with poly(A) . (dT)12 and poly(C) . (dG) approximately 16 was almost completely abolished in the presence of the mycoplasma. Thus, M. hyorhinis may interfere with identification and isolation procedures for retroviruses.

Cell Line↗
PubMed1979

Adherence of Mycoplasma gallisepticum to glass.

Attachment of washed Mycoplasma gallisepticum cells to glass was quantified with organisms in which membrane lipids were labelled with 3H. Siliconization of the test tubes decreased attachment, while centrifugation increased it. Attachment increased with temperature, decreased with increasing pH and ionic strength of the attachment mixture, but was unaffected by Ca2+, Mg2+ and EDTA. This suggests that ionic bonds, but not salt bridges, participate in the attachment process. Glycophorin, the major receptor responsible for M. gallisepticum attachment to erythrocytes, partially inhibited the attachment of the organisms to glass. However, bovine serum albumin also decreased attachment. Extensive pretreatment of the organisms with trypsin decreased their ability to attach to glass by about 35 to 40%. Trypsin and pronase failed to detach the organisms already bound to glass, suggesting that external mycoplasma cell components, other than membrane proteins, also participate in attachment of the organisms to glass.

Cell Count↗
PubMed1979

Interaction of Mycoplasma pneumoniae with alveolar macrophages: viability of adherent and ingested mycoplasmas.

Guinea pig peritoneal or alveolar macrophages were inoculated with Mycoplasma pneumoniae cells. Extracellular mycoplasms were killed by complement treatment, and the effect of macrophage action on the number of the remaining viable mycoplasmas was observed. The complement killing was to some extent inhibited by the presence of the macrophages, but the mechanism of this protection remains unknown. Opsonized mycoplasmas were ingested, and approximately 98% were killed within 4 h. The killing rate was somewhat lower than comparable data for bacteria, but lack of cell wall and high lipid content of the membrane apparently do not cause a significant delay in intracellular destruction.

Animals↗
PubMed1979

Adherence of erythrocytes to Mycoplasma pneumoniae.

The human pathogen Mycoplasma pneumoniae adheres to a variety of cells, including erythrocytes. A hemadsorption technique was developed to quantitate adherence by photometric measurement of lysates of erythrocytes that attached to sheets of M. pneumoniae grown in cups of Linbro plates. Attachment of sheep erythrocytes (SE) increased with higher ionic strength, was unaffected by minor pH variations (6 to 9), and was blocked by anti-M. pneumoniae antiserum, but was not inhibited by a variety of sugars, amino acids, and bovine serum albumin. The reaction was time and temperature dependent. The temperature curve showed peaks at 14 and 28 degrees C with untreated SE but only one peak at about 38 degrees C with glutaraldehyde-treated SE. The temperature dependence indicated involvement of either metabolic or membrane activities in the binding process. Trypsin treatment of the M. pneumoniae sheet abolished adherence of SE but was only partially effective with human erythrocytes and noneffective with rabbit erythrocytes. The binding capacity of the mycoplasma cells for SE was restored by incubation in growth medium for 3 to 4 h; this restoration was inhibited by 10 mug of chloramphenicol per ml. Neuraminidase treatment of SE removed their attachment capacity but had no effect on attachment of rabbit erythrocytes and only a slight effect on attachment of human erythrocytes. Pretreatment of M. pneumoniae with neuraminic acid partially blocked the adherence of SE, whereas rabbit erythrocyte attachment was not affected. Attached SE could be detached by trypsin, but not by neuraminidase. For human and rabbit erythrocytes, the results suggest binding mechanisms other than the interaction between neuraminidase-sensitive receptors and protein-containing binding sites shown for SE.

Animals↗
PubMed1979

Adherence of Mycoplasma pneumoniae to glass surfaces.

Attachment of M. pneumoniae to glass was quantitated in an experimental system enabling the settling down of [3H]palmitic acid-labeled cells onto glass cover slips. Attachment of mycoplasmas suspended in buffer increased with temperature, decreased with higher ionic strength, and showed a maximum at about pH 5.5. The findings suggest a participation of ionic bonds in the attachment process. Trypsin did not detach glass-bound mycoplasmas, and treatment of the cells with glutaraldehyde did not reduce their attachment to glass, suggesting that membrane components other than proteins may be involved in the attachment. Low concentrations (up to 20 mg/ml) of bovine serum albumin buffer. However, during the next few hours, attachment increased far above the bovine serum albumin control. This marked increase was reduced by more than half in the presence of chloramphenicol. Increased attachment was also observed when glucose (0.1 to 2 mg/ml) was added to the bovine serum albumin-containing buffer. The findings suggest different mechanisms for the attachment in protein-free buffer and in growth medium or glucose-containing bovine serum albumin buffer, respectively. The latter apparently requires metabolic activity of the mycoplasmas.

Culture Media↗
PubMed1978

Adherence of Mycoplasma gallisepticum to human erythrocytes.

Pathogenic mycoplasmas adhere to and colonize the epithelial lining of the respiratory and genital tracts of infected animals. An experimental system suitable for the quantitative study of mycoplasma adherence has been developed by us. The system consists of human erythrocytes (RBC) and the avian pathogen Mycoplasma gallisepticum, in which membrane lipids were labeled. The amount of mycoplasma cells attached to the RBC, which was determined according to radioactivity measurements, decreased on increasing the pH or ionic strength of the attachment mixture. Attachment followed first-order kinetics and depended on temperature. The mycoplasma cell population remaining in the supernatant fluid after exposure to RBC showed a much poorer ability to attach to RBC during a second attachment test, indicating an unequal distribution of binding sites among cells within a given population. The gradual removal of sialic acid residues from the RBC by neuraminidase was accompanied by a decrease in mycoplasma attachment. Isolated glycophorin, the RBC membrane glycoprotein carrying almost all the sialic acid moieties of the RBC, inhibited M. gallisepticum attachment, whereas asialoglycophorin and sialic acid itself were very poor inhibitors of attachment. Only part of the (125)I-labeled glycophorin bound to mycoplasmas could be removed by neuraminidase or by exchange with unlabeled glycophorin. It is suggested that glycophorin, representing the isolated major RBC receptor for M. gallisepticum, binds to the mycoplasmas both specifically, through its sialic acid moieties, and nonspecifically, through its exposed hydrophobic polypeptide moiety.

Calcium↗
PubMed1977

Interactions between mycoplasma pneumoniae and the first components of complement.

Mycoplasma pneumoniae cells were rounded and killed by fresh guinea pig serum (GPS) which did not contain detectable amounts of antibody. The first component of complement (C1) was bound by M. pneumoniae in considerable amounts from both GPS and purified C1. The C1 bound by the cells was reacting with C4. Sequential addition of C1, C4, C2, and C-ethylenediaminetetraacetate to glass-grown M. pneumoniae cells resulted in rounding of a significant number of cells. M. orale and M. fermentans showed a reduced binding capacity for C1 as compared with M. pneumoniae. Both species were only slowly killed by fresh GPS, whereas M. hominis was as sensitive as M. pneumoniae. The results suggest an antibody-independent interaction between some components of the membrane surface of M. pneumoniae and C1, resulting in an activation of the complement system leading to the killing of the mycoplasma cells.

Animals↗
PubMed1977

Motility of Mycoplasma pneumoniae.

Cell of Mycoplasma pneumoniae FH gliding on a glass surface in liquid medium were examined by microscopic observation and quantitatively by microcinematography (30 frames per min). Comparisons were made only within the individual experiments. The cells moved in an irregular pattern with numerous narrow bends and circles. They never changed their leading end. The average speed (without pauses) was relatively constant between o.2 and 0.5 mum/s. The maximum speed was about 1.5 to 2.0 mum/s. The movements were interrupted by resting periods of different lengths and frequency. Temperature, viscosity, pH, and the presence of yeast extract in the medium influenced the motility significantly; changes in glucose, calcium ions, and serum content were less effective. The movements were affected by iodoacetate, p-mercuribenzoate, and mitomycin C at inhibitory or subinhibitory concentrations. Sodium fluoride, sodium cyanide, dinitrophenol, chloramphenicol, puromycin, cholchicin, and cytochalasin B at minimal inhibitory concentrations did not affect motility. The movements were effectively inhibited by anti-M. pneumoniae antiserum. Studies with absorbed antiserum suggested that the surface components involved in motility are heat labile. The gliding of M. pneumoniae cells required an intact energy metabolism and the proteins involved seemed to have a low turnover.

Anti-Bacterial Agents↗