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Biomedical subjects

M Banai

Publications and source records attributed to M Banai.

31 records · Page 2Linked to original sources
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↗
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

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↗
PubMed1978

Specificity of nucleotide binding sites in isolated chloroplast coupling factor (CF1).

The binding of various nucleotides to chloroplast coupling factor CF1 was studied by two dialysis techniques. It was found that the number of nucleoside diphosphate sites and their specificities for the base moiety is dependent on the magnesium concentration. In the presence of 50 micrometer added MgCl2, the protein has a single strong site/mol protein with Kd = 0.5 micrometer for ADP and high specificity (Kd greater than 20 micrometer for epsilonADP, GDP, CDP). In the presence of 5 mM MgCl2, the protein has two independent tight ADP sites (Kd = 0.4 micrometer) of low specificity (Kd approximately 0.8, 2, and 2 micrometer, respectively for episilonADP, GDP, and CDP). These results are compared with the specificity of the partial reactions for photophosphorylation.

Binding Sites↗
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↗
PubMed1976

[Control-lateral sciatrica after surgery for herniated disk].

A study of 1,427 case records permitted the authors to discover 10 cases of reoperation for sciatica which appeared on the opposite side after removal of a dischernia. A new hernia was noted in 6 cases, whereas radiculitis of unknown origin, appeared to be responsible in 4 cases. The 10 patients who became cured, either after removal of the hernia, or after decompression through the foramin. These few cases, in fact rare, may be considered as relapses and thus poor surgical results. The provide a contribution to the understanding of intervertebral disc disease and raise an interesting medico-legal problem.

Adult↗
PubMed1976

[Synovectomies of the knee. Apropos of 47 cases tuberculous synovitis].

UNLABELLED: The authors carried out synovectomy of the knee in 70 cases, including 47 for tuberculous synovitis, with follow up periods of 2 years and half to 18 years. The subjects included: -30 children from 2 to 15 years; -17 adults from 16 to 50 years, with 3 cases of more than 50 years. RESULTS: Very good: greater or equal to 110 degrees in 2 cases; -Good: greater or equal to 90 degrees in 26 cases; -Average: greater or equal to 45 to 90 degrees in 11 cases; -Poor: less than 45 degrees in 8 cases. The authors believe that synovectomy in tuberculous synovitis of the knee without an osteocartilagenous lesion, or with slight lesions of the joint is more efficacious than medical treatment alone and may shorten the duration of treatment.

Adolescent↗
PubMedDate not supplied

Brucellosis: an unusual diagnosis for a seronegative patient with abscesses, osteomyelitis, and ulcerative colitis.

A 16-year-old girl developed multiple subcutaneous abscesses, osteomyelitis, and severe colitis. On the patient's second admission, a single blood culture--and, subsequently, a specimen of pus--yielded Brucella melitensis biovar 1. A second set of serologic tests, including the rose bengal test, the standard tube agglutination test, the CF test, and Coombs' test, were all negative for Brucella on the patient's second admission and 1 month later. However, a lymphocyte proliferation assay with extracted antigen of Brucella was markedly positive. Thus, this case illustrates that patients with B. melitensis infection may have a unique clinical presentation and that the lymphocyte proliferation assay is an important diagnostic tool for patients whose serologic test results are negative but for whom brucellosis is suspected.

Abscess↗
PubMedDate not supplied

Attachment of mycoplasmas to host cell membranes.

Pathogenic mycoplasmas rarely invade the tissues or bloodstream. Their adherence to epithelial cell surface, the first stage in disease, involves protein binding sites on the mycoplasmal cell membrane and receptors on the host cell membrane. Strong evidence indicates that Mycoplasma gallisepticum and Mycoplasma pneumoniae adhere with the aid of sialic acid residues on host cells, but the data do not preclude participation by other host-cell membrane components. Several studies indicate that these mycoplasmas adhere by blebs or terminal structures; others suggest that binding occurs via other cell areas. Scanning electron microscopy suggests tight interaction between these mycoplasmas and red blood cell membranes, causing imprints resembling those from interaction of viruses with red blood cells. Because sialoglycoproteins are major sites for attachment of M. pneumoniae to respiratory epithelium and red blood cells, glycophorin--the major sialoglycoprotein of human red blood cells--was the ligand used in affinity chromatography for isolation of the binding sites specific for sialic acid receptors from M. pneumoniae membranes solubilized by detergents. The fraction eluted with 0.2% sodium dodecylsulfate from the glycophorin-Sepharose column, highly enriched with two proteins, exhibited high binding capacity to glycophorin-Sepharose beads and lower binding capacity to human red blood cells. The latter capacity was nearly abolished by glycophorin, but not by its hydrophobic moiety.

Adhesiveness↗